WO2017038051A1

WO2017038051A1 - Shaping apparatus and shaping method

Info

Publication number: WO2017038051A1
Application number: PCT/JP2016/003835
Authority: WO
Inventors: Itaru Watanabe; Ken-Ichi Abe; Kikuo Naito; Ikuo Sobue
Original assignee: Canon Kabushiki Kaisha
Priority date: 2015-08-31
Filing date: 2016-08-23
Publication date: 2017-03-09

Abstract

A shaping apparatus fabricating a three-dimensional object formed of a shaping material on a stage includes a detection unit that detects a position of the material layer on the transfer member; a measurement unit that measures from detection results obtained by the detection unit a positional shift amount of the material layer on the transfer member; and an adjustment unit that is capable of adjusting a relative position between the transfer member and the stage by moving the stage in a direction orthogonal to a stacking direction of the material layer and a rotation direction about an axis extending in the stacking direction of the material layer, based on the positional shift amount measured by the measurement unit.

Description

SHAPING APPARATUS AND SHAPING METHOD

The present invention relates to a shaping apparatus and a shaping method.

Shaping apparatuses which form a three-dimensional shaping object by stacking a large number of layers are drawing attention. A shaping technique of this type is referred to as additive manufacturing (AM), three-dimensional printing, rapid prototyping, and the like. Various shaping methods are proposed to implement the shaping technique. PTL 1 and PTL 3 disclose shaping methods utilizing an electrophotographic process while PTL 2 discloses a laser sintering method.

Japanese Patent Application Laid-open No. H10-224581 US Patent Application Publication No. 2009/0060386 (Specification) Japanese Patent Application Laid-open No. 2003-053846

In the shaping apparatus using these methods, a shape accuracy of a sectional image of each layer (image formation accuracy) and a positional accuracy when stacking the respective layers (stacking accuracy) may have a significant impact on quality of a final shaping object. In particular, this becomes a major issue with stacking methods involving independently forming images of respective layers and sequentially stacking the images as is the case of the apparatuses according to PTL 1 and PTL 3. However, with the apparatuses disclosed in PTL 1 and PTL 3, distortion of images and variation in image positions are not addressed and image formation accuracy and stacking accuracy are not guaranteed.
PTL 2 discloses a position calibration method for an apparatus adopting a laser sintering method, in which a calibration plate is scanned prior to start of shaping to determine a center reference of an image. However, this method cannot be applied to stacking methods involving independently forming images of respective layers and sequentially stacking the images as described in PTL 1 and PTL 3.

With the foregoing in view, an object of the present invention is to provide a technique for improving the quality and accuracy of a three-dimensional object in a shaping apparatus which employs a method of forming respective layers independently and stacking these layers sequentially to obtain the three-dimensional object.

A first aspect of the present invention resides in a shaping apparatus, comprising: a material layer forming unit that forms a material layer formed of a shaping material, based on given data; a transfer member that conveys the material layer transferred from the material layer forming unit; and a stage on which the material layer conveyed by the transfer member is stacked, the shaping apparatus fabricating a three-dimensional object formed of the shaping material on the stage, the apparatus further comprising: a detection unit that detects a position of the material layer on the transfer member; a measurement unit that measures from detection results obtained by the detection unit a positional shift amount of the material layer on the transfer member; and an adjustment unit that is capable of adjusting a relative position between the transfer member and the stage by moving the stage in a direction orthogonal to a stacking direction of the material layer and a rotation direction about an axis extending in the stacking direction of the material layer, based on the positional shift amount measured by the measurement unit.

A second aspect of the present invention resides in a shaping method using a shaping method used for a shaping apparatus including: a material layer forming unit that forms a material layer formed of a shaping material, based on given data; a transfer member that conveys the material layer transferred from the material layer forming unit; and a stage on which the material layer conveyed by the transfer member is stacked, the shaping apparatus fabricating a three-dimensional object formed of the shaping material on the stage, the method comprising: a step of appending data of a registration marker to the data given to the material layer forming unit; a step of operating a detection unit to detect the registration marker included in the material layer on the transfer member; a step of operating a measurement unit to measure from detection results obtained by the detection unit a positional shift amount of the material layer on the transfer member; and a step of adjusting a relative position between the transfer member and the stage by moving the stage in a direction orthogonal to a stacking direction of the material layer and a rotation direction about an axis extending in the stacking direction of the material layer, based on the positional shift amount measured by the measurement unit.

According to the present invention, it is possible to improve the quality and accuracy of a three-dimensional object in a shaping apparatus which employs a method of forming respective layers independently and stacking these layers sequentially to obtain the three-dimensional object.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a shaping apparatus according to Embodiment 1. FIG. 2 is a diagram illustrating an example of a configuration of a control unit according to Embodiment 1. FIG. 3 is a flowchart illustrating the flow of a registration process according to Embodiment 1. FIG. 4 is a diagram illustrating registration markers on a transfer member according to Embodiment 1. FIGS. 5A to 5C are conceptual diagrams for describing detection of registration markers and calculation of a correction amount. FIG. 6 is a conceptual diagram for describing detection of registration markers and calculation of a correction amount. FIG. 7 is a conceptual top view of a stage correction mechanism of a stacking stage according to Embodiment 1. FIGS. 8A and 8B are diagrams for describing a skew adjustment unit according to Embodiment 1. FIGS. 9A and 9B are diagrams illustrating another example of a stage correction mechanism. FIG. 10 is a diagram illustrating registration markers on a transfer member according to Embodiment 2. FIG. 11 is a diagram illustrating registration markers on a transfer member according to Embodiment 3. FIG. 12 is a cross-sectional view illustrating a schematic configuration of a shaping apparatus according to Embodiment 4. FIG. 13 is a cross-sectional view illustrating a schematic configuration of a stacking and shaping apparatus according to Embodiment 5. FIG. 14 is a flowchart illustrating the flow of a correction process according to Embodiment 5. FIG. 15 is a conceptual diagram for describing calculation of a moving amount of a transfer member according to Embodiment 5.

The present invention relates to a shaping apparatus and a shaping method for fabricating a three-dimensional object (solid object) by stacking a material layer formed of a shaping material.
A shaping apparatus according to the present invention converts three-dimensional shape data of a solid object obtained by appending a support body necessary during shaping to a shaping target object to shaping slice data to form an image formed of a shaping material of each layer according to the slice data of each layer. The shaping apparatus shapes a shaping object by stacking the images formed of these shaping materials sequentially.

As the shaping material, it is possible to select various materials in accordance with the use, function, and purpose of a solid object to be fabricated. In the present specification, a material constituting a three-dimensional object as a shaping target is referred to as “a build material”, and a portion formed of the build material is referred to as a build body. A material constituting a support body for supporting the build body in the process of fabrication (e.g., a pillar supporting an overhang portion from below) is referred to as “a support material”. In addition, in the case where it is not necessary to distinguish between them, a term “shaping material” is simply used. As the build material, it is possible to use thermoplastic resins such as, e.g., polyethylene (PE), polypropylene (PP), ABS, and polystyrene (PS). Further, as the support material, in order to facilitate removal from the build body, it is possible to use a material having thermoplasticity and water solubility preferably. Examples of the support material include carbohydrate, polylactic acid (PLA), polyvinyl alcohol (PVA), and polyethylene glycol (PEG).

In addition, in the present specification, digital data obtained by slicing three-dimensional shape data of a solid model as the shaping target into several layers along a stacking direction is referred to as “slice data”. A layer formed of the shaping material based on the slice data is referred to as “a material layer”. Further, a target solid model that is to be fabricated by using the shaping apparatus (i.e., a three-dimensional object represented by three-dimensional shape data given to the shaping apparatus) is referred to as “a shaping target object”, and a three-dimensional object (solid object) fabricated (outputted) by the shaping apparatus is referred to as “a shaping object”. In the case of the shaping of a three-dimensional object needing the support material, the shaping object includes the build body and the support body. And the build body, that is, the shaping target object is acquired by removing the support body from the shaping object.

(Embodiment 1)
Hereinafter, Embodiment 1 will be described.
(Configuration of Shaping Apparatus)
A configuration of a shaping apparatus according to the present embodiment will be described with reference to FIG. 1. FIG. 1 is a cross-sectional view schematically illustrating a schematic configuration of a shaping apparatus according to the present embodiment. In FIG. 1, reference numeral 1 indicates a shaping apparatus body, and a line surrounding the constituent members therein illustrated in the drawing illustrates the boundary (that is, a contour line) between the shaping apparatus body and the external space.

The shaping apparatus body 1 receives slice data from an external data processing device (not illustrated) and allows a material layer forming unit 2 to form a material layer 3 corresponding to the slice data using a shaping material. The material layer forming unit may employ an electrophotographic method, an inkjet method, or the like.
The material layer 3 formed by the material layer forming unit 2 is transferred to a transfer surface (the front surface) of a transfer member 5 which is a belt-shaped conveying member and is conveyed by a driving roller 4 up to a stacking unit in the direction indicated by an arrow in the drawing. In the course of being conveyed to the stacking unit, the material layer 3 is heated and melted by a heating unit 6, and the shaping material which is a powder form is changed to a material layer which is integrated in a sheet form. Here, the stacking unit includes a stacking stage 14, a transfer member 5, and an opposing member 17 disposed on an inner circumference side of the transfer member 5 so as to face the stacking stage 14. Moreover, in the course in which the material layer 3 is conveyed to the stacking unit by the transfer member 5, the position of the material layer 3 is detected by a non-contact-type position sensor (detection unit) 8.

A skew adjustment unit 7 may be preferably provided in relation to movement of the transfer member 5. FIGS. 8A and 8B are diagrams for describing an example of the skew adjustment unit 7 and are top views of the transfer member 5.
In FIGS. 8A and 8B, mechanisms capable of applying force independently are provided at both ends of a rotation axis of a driving roller 4 that stretches the transfer member 5 as the skew adjustment unit 7. In this way, it is possible to create a difference in the stretching force for stretching the transfer member 5 at both ends in the rotation axis direction of the driving roller 4 and to adjust the skew of the transfer member 5.

The stacking stage 14 includes a stage correction mechanism 12 and is movable in an up-down direction by the stage lifting mechanism 13 and is capable of correcting the positions of the material layer 3 and the shaping object 15 with the aid of a correction control unit (described later).
In the present embodiment, the shaping object 15 is formed on a base plate (base member) 9 which is detachably disposed on an upper surface of the stage correction mechanism 12. Thus, the following means is provided so that the base plate 9 is detachably positioned and fixed in relation to the stage correction mechanism 12 and the base plate 9 is immovable on the stage correction mechanism 12 during stacking. The means includes a positioning unit 11 that positions the base plate 9 on the stage correction mechanism 12 and a fixing and releasing unit 10 for attaching and detaching the base plate 9 to and from the stage correction mechanism 12.
In the shaping apparatus of the present embodiment, the base plate 9 that can be conveyed is disposed on the stacking stage 14 and a shaping object is shaped on the base plate 9. However, the present invention is not limited to this. That is, the present invention can be ideally applied to a shaping apparatus in which a shaping object is directly shaped on the stacking stage (the stage correction mechanism 12 in the present embodiment).

When the material layer 3 transferred to the transfer member 5 moves to the stacking unit, the stacking stage 14 is moved up by the stage lifting mechanism 13 capable of moving the stacking stage 14 in an up-down direction (stacking direction).
As a result, the material layer 3 which is transferred to the transfer member 5 and is heated and melted in a sheet form is sandwiched, together with the transfer member 5, between the upper surface of the shaping object 15 on the base plate 9 positioned and fixed to the stacking stage 14 and the opposing member 17. In this case, the material layer 3 is transferred from the transfer member 5 to the upper surface of the shaping object 15 on the base plate 9 and is stacked on the upper surface. After that, the stacking stage 14 is moved down by the stage lifting mechanism 13 in order to stack the material layer 3 conveyed subsequently. This operation is performed repeatedly whereby a shaping object is shaped on the base plate 9.

After the shaping operation ends, in the present embodiment, the base plate 9 is removed from the shaping apparatus in a state of being integrated with the shaping object 15.
In a period after the present shaping operation ends before a subsequent shaping operation starts, the stage correction mechanism 12 moves from the position to which the stage correction mechanism 12 is moved continuously due to correction to the coordinate of the origin of the shaping apparatus body 1, obtained by an origin detection unit 21 illustrated in FIG. 1. In this case, the transfer member 5 is driven to rotate and returned to a predetermined center position by the skew adjustment unit 7.
When such an adjustment sequence is performed, the correction mechanism is returned to an initial position (reference position) of the shaping apparatus body 1 in a period after the shaping operation ends before a subsequent shaping operation starts.

Such a shaping process is controlled by a control unit 16. Hereinafter, the control unit 16 according to the present embodiment will be described.
(Configuration of Control Unit)
FIG. 2 is a diagram illustrating an example of a configuration of the control unit 16 according to the present embodiment. The control unit 16 includes an image generation control unit 201, a stacking control unit 202, a temperature control unit 203, and a correction control unit (adjustment unit) 204.

The image generation control unit 201 has the following functions. The functions include a function of generating data of a support body to be appended according to the shape of a shaping target object and a function of generating slice data from three-dimensional shape data of the shaping target object and the data of a support body. Further, the functions include a function of controlling the shaping apparatus body 1 to allow the material layer forming unit 2 to generate the material layer 3 on the transfer member 5 using slice data of each layer, a function of an appending unit that appends the data of registration markers to slice data, and the like.
The image generation control unit 201 can generate three-dimensional shape data using data created by a three-dimensional CAD, a three-dimensional modeler, a three-dimensional scanner, or the like. Although the format of the three-dimensional shape data is not particularly limited, polygon data such as, for example, stereolithography (STL) can be preferably used. Moreover, multi-value image data (each value represents the type of a material) and multi-plane image data (each plane represents the type of a material) can be used as the format of the slice data, for example. Further, the image generation control unit 201 performs resolution conversion or decoding of the slice data, and controls a formation position of the material layer 3, formed by the material layer forming unit 2 and the transfer timing of the material layer 3 to the transfer member, for example. In addition to these functions, the image generation control unit 201 may have the same function as a printer controller incorporated into a general laser printer (2D printer). In the present embodiment, although the image generation control unit 201 has a function of generating slice data and a function of generating three-dimensional shape data such as STL, the image generation control unit 201 may not necessarily have these functions. For example, a device outside the shaping apparatus 1 may generate slice data and three-dimensional shape data, and the generation results may be transmitted to the image generation control unit 201 of the shaping apparatus 1 via a network.

The stacking control unit 202 has a function of controlling the shaping apparatus body 1 so that the material layer 3 generated on the transfer member 5 by the image generation control unit 201 is stacked on the shaping object 15 on the stacking stage 14.
Specifically, the stacking control unit 202 controls the driving roller 4 so that the material layer 3 transferred to the transfer member 5 is conveyed up to the stacking unit and is stopped temporarily. Further, the stacking control unit 202 controls the movement of the stacking stage 14 so that the stacking stage 14 is moved vertically and the material layer 3 is stacked on the shaping object 15 shaped on the base plate 9. When the control of stacking the material layer 3 on the shaping object 15 ends, the stacking control unit 202 starts conveying the transfer member 5 again. When control of controlling the material layer forming unit 2 to form the material layer 3 is performed in parallel in a stopping period of the transfer member 5, efficiency is improved.
The temperature control unit 203 controls the heating unit 6 so as to melt the material layer 3.

The correction control unit 204 has a measurement unit that measures a positional shift amount of the material layer 3 on the transfer member 5, and a function of adjusting a relative position between the transfer member 5 and the stacking stage 14. In particular, the correction control unit 204 has a function of correcting a positional shift between the material layer 3 generated on the transfer member 5 and the shaping object 15 of the stacking unit.
As in the present embodiment, in a shaping apparatus of such a type that stacks a number of material layers 3 to form a shaping object, the positional accuracy during stacking determines the quality of a final shaping object. If a positional variation is large when the material layer of each layer is stacked on the shaping object 15 formed on the stacking stage 14, a large unevenness is formed on a side surface of a final shaping object and a smooth surface cannot be obtained. Even when processing is implemented at a later stage, a long processing time is required due to the large unevenness. This is a problem unique to a shaping apparatus that superimposes several hundreds to several tens of thousands of material layers to shape one final shaping object.
Thus, the correction control unit 204 measures the position of each material layer 3 on the transfer member 5 to achieve positioning between the material layer 3 on the transfer member 5 and the shaping object 15 on the stacking stage 14 during stacking in order to secure the positional accuracy during stacking. In the following description, this positioning is referred to as “registration” and a position correction function is referred to as a “registration function”.

(Registration Function)
Here, a registration function will be described. The registration function involves burying registration markers in a material layer to perform positioning during stacking based on the detected positions of the markers.
FIG. 3 illustrates an example of a flowchart illustrating the flow of a registration process according to the present embodiment. Hereinafter, the flow of the registration process will be described with reference to FIG. 3.

In step S301, in a process of forming the material layer 3, the image generation control unit 201 allows the material layer forming unit 2 to form registration markers simultaneously based on registration marker data and transfer the registration markers to the transfer member 5. The details of the registration markers transferred to the transfer member 5 will be described with reference to FIG. 4.
Subsequently, in step S302, the correction control unit 204 monitors the output of the non-contact-type position sensor 8 while the stacking control unit 202 moves the registration markers on the transfer member 5 toward the stacking unit. The correction control unit 204 stores a distal end position and a passing distance of each registration marker detected by the non-contact-type position sensor 8.

Subsequently, in step S303, the positional shift amounts (correction amounts) in X, Y, and θ-directions of the material layer are calculated from the detection results of the registration markers detected in step S302. Here, the X-direction is a travelling (moving) direction of the transfer member 5, the Y-direction is a direction orthogonal to the travelling direction of the transfer member 5, and the θ-direction is a rotation direction about an axis orthogonal to a transfer surface of the transfer member 5 to which the material layer 3 is transferred.
Subsequently, in step S304, the correction control unit 204 controls the stacking stage 14 so as to correct the positional shift corresponding to the positional shift amounts in the three directions, calculated in step S303. Moreover, the stacking control unit 202 moves the stacking stage 14 vertically so that the material layer 3 is stacked on the shaping object 15.

FIG. 4 is a diagram illustrating an example of registration markers on the transfer member 5 according to the present embodiment. In FIG. 4, reference numerals different from the reference numerals used for the constituent elements illustrated in FIG. 1 are used for the sake of convenience.
Reference numeral 40 in FIG. 4 corresponds to the transfer member 5, and FIG. 4 is a top view of the transfer member 40.

Reference numerals

41 and 42 correspond to the non-contact-type position sensor 8 illustrated in FIG. 1. In the present embodiment, the non-contact-type position sensor 8 is an optical area sensor or a line sensor, and two sensors are disposed in a direction orthogonal to the travelling direction of the transfer member 5 so as to correspond to the formation positions of registration markers. In FIG. 4, reference numeral 401 indicates a region (hereinafter referred to as a shaping region) in which the material layer 3 can be formed on the transfer member and the boundary may be invisible.

Reference numerals

402 and 403 in FIG. 4 indicate registration markers. The

registration markers

402 and 403 are formed at a predetermined position (a position that does not overlap the material layer 3) at the distal end of the shaping region 401. The registration marker of the present embodiment is a right-angled triangular figure having a first edge orthogonal to the travelling direction (X-direction) of the transfer member and a second edge that is oblique to the X-direction. Moreover, the two registration markers are disposed in a direction orthogonal to the travelling direction of the transfer member 5 so that the registration markers are detected by the non-contact-type position sensors 8.

Reference numeral 404 in FIG. 4 corresponds to the material layer 3 formed on the transfer member by the material layer forming unit 2.
The

registration markers

402 and 403 are transferred to a predetermined position in the shaping region 401 by the material layer forming unit 2 simultaneously with the material layer 404. Thus, it is possible to acquire a positional shift amount of the material layer based on the detection results of the registration markers.

(Calculation of Correction Amount)
FIGS. 5A, 5B, 5C and 6 are conceptual diagram for describing detection of registration markers on the transfer member 5 in step S302 of FIG. 3 and calculation of a correction amount in step S303.
In FIGS. 5A, 5B, and 5C, the same constituent elements as the constituent elements illustrated in FIG. 4 are denoted by the same reference numerals.

The

registration markers

402 and 403 are detected using the fixed non-contact-

type position sensors

41 and 42 while moving the transfer member 40 upward in the drawings. Reference sign S1 in the drawings illustrates an example of a detection signal of the registration marker 402 detected by the non-contact-type position sensor 41. The signal changes from low level to high level when the first edge of the registration marker 402 is detected and the signal changes from high level to low level when the second edge of the registration marker 402 is detected. Similarly, reference sign S2 illustrates an example of a detection signal of the registration marker 403 detected by the non-contact-type position sensor 42.

Here, it is assumed that the

registration markers

402 and 403 are transferred in a state of being shifted by Δθ in the rotation direction from the travelling direction of the transfer member 40. In such a case, the positional shift amount Δθin the rotation direction can be calculated using a difference between the detection positions (detection timings) of the upper edges of the

registration markers

402 and 403. Specifically, the positional shift amount Δθ can be expressed as follows using a known distance L1 that connects the detection centers of the non-contact-

type position sensors

41 and 42 and the difference L2 between the detection positions of the

registration markers

402 and 403. That is, the positional shift amount Δθ can be expressed as Δθ=Arctan(L2/L1) using the inverse function Arctan of the tangent Tan of a trigonometric function.

Moreover, it is assumed that ΔY is a shift amount of the center position of the shaping region 401 in relation to the center position in the Y-direction of the transfer member 40 and that the

registration markers

402 and 403 are transferred in a state of being shifted in a direction vertical to the travelling direction of the transfer member as illustrated in FIG. 5A. In such a case, the positional shift amount ΔY can be calculated using the ratio between the detection distances of the

registration markers

402 and 403. Specifically, if the length of the upper edge of a triangle is 1, the following equation is established for a detection distance L3 of the registration marker 402 and a detection distance L4 of the registration marker 403 using the ratio of similitude of triangles.
(0.5-ΔY):L3=(0.5+ΔY):L4
ΔY=0.5×(L4-L3)/(L3+L4)
Moreover, referring to FIG. 5C, a positional shift amount ΔX in the travelling direction of the transfer member, of each of the

registration markers

402 and 403 is calculated. The positional shift amount ΔX is a detection distance L5 from a certain reference point on the transfer member to the upper edge of each of the

registration markers

402 and 403. The reference point may a point corresponding to a moving start time of the transfer member, for example, and a marker serving as a reference position may be formed on the transfer member when the transfer member 5 moves continuously.

In FIGS. 5A, 5B, and 5C, the positional shift amounts in the X, Y, and θ-directions are calculated independently assuming that a positional shift in one direction occurs in a state in which no positional shift occurs in the other directions. In contrast, even when a positional shift occurs simultaneously in the X, Y, and θ-directions, it is possible to calculate the positional shift amount in each direction by combining the above-described calculations geometrically.
Moreover, in the present embodiment, although a right-angled triangular shape is used as the shape of the registration marker, the registration marker is not limited to this shape. A figure which has at least an edge vertical to the travelling direction of the transfer member and an edge that skews in the travelling direction may be used as the registration marker.
Moreover, in the present embodiment, although two opposing right-angled triangular figures are used as the registration markers, only one registration marker may be used if it is known that there is no positional shift in the θ-direction. By using one registration marker, it is possible to calculate the positional shift amounts in the X and Y-directions.

(Noise Reduction Process)
It is assumed that the non-contact-

type position sensors

41 and 42 of the present embodiment are optical laser sensors.
In FIG. 5, the waveforms of the signals S1 and S2 indicating that the

registration markers

402 and 403 are detected by the non-contact-

type position sensors

41 and 42 are illustrated as ideal waveforms.
However, in an actual waveform, as indicated by reference sign S2' in FIG. 6, a noise component 601 which results from, e.g., a density difference in the material layer due to low transfer efficiency may appear in a marker region and a noise component 602 which results from scratches and depressions in the transfer member may also appear outside the marker region.

The correction control unit 204 performs a noise reduction process of removing these noise components in step S303 (correction amount calculation) of FIG. 3. Specifically, the correction control unit 204 acquires a large number of waveforms in which noise components appear to create a profile in advance and performs a filtering process of removing the noise components only. For example, the correction control unit 204 sets the thresholds of the frequencies of noise components occurring inside and outside the marker region from the profile and removes waveforms having frequencies higher than the threshold set for each zone as noise components. In this way, it is possible to convert the signal S2' in FIG. 6 to the signal S2.

By performing such a process, it is possible to calculate a correction amount which is robust to deterioration of the transfer member and the shaping accuracy of the registration marker.
Even if the waveform obtained by the non-contact-

type position sensors

41 and 42 has such an ideal shape as the waveform S2 illustrated in FIG. 6, a shift of a marker detection zone may occur due to, e.g., a fragmented marker edge and the obtained correction values ΔX, ΔY, and Δθ may be larger than the actual values. In order to prevent such a problem, the present embodiment collects a large number of items of data in advance to calculate maximum and minimum values that fall within a certain setting range of measurement values. When a measurement value is larger than the maximum value or smaller than the minimum value, the measurement value is determined to be a noise component, the moving amounts ΔX, ΔY, and Δθ are set to 0, and the previous correction position (that is, the correction position only layer before) of the material layer 3 is maintained without moving the correction mechanism 12. By performing such a process, it is possible to prevent excessive correction due to the shift value obtained by the non-contact-type position sensors.

(Correction Process)
FIG. 7 is a conceptual top view of the stage correction mechanism 12 of the stacking stage 14 illustrated in FIG. 1.
The stage correction mechanism 12 executes a correction process in step S304 based on the correction amount calculated in step S303 of FIG. 3.

The stage correction mechanism 12 has

motors

701, 702, and 703 and the feed amounts of the respective motors for moving the base plate 704 in the X, Y, and θ-directions are defined. The correction control unit 204 controls the

motors

701, 702, and 703 so that the base plate 704 is moved by the correction amounts ΔX, ΔY, and Δθ calculated in step S303. In this way, the positional shift between the material layer 3 and the shaping object 705 stacked on the base plate 704 is eliminated.

When a material layer of the second or subsequent layer is stacked, the correction amount of the stage correction mechanism 12, calculated in step S303 is not used as it is, but a previous correction position may be stored and a difference between the previous and present correction positions may be corrected.

Moreover, when it is determined during shaping that a predicted value of the correction amount is likely to exceed a correction range of the stage correction mechanism 12, the control unit 16 may perform the following control. That is, the control unit 16 may form the material layer after shifting the image position in the material layer forming unit so that the correction amount falls within the correction range and may transfer the material layer to the transfer member, detect the correction amount, and move the base plate. As a method of shifting the image in the material layer forming unit, a method of processing image data, a method of shifting the position of the material layer forming unit in relation to the transfer member, and the like may be used.
With such control, it is possible to reduce the correction range of the stage correction mechanism 12 and to decrease the size and the cost.

In the configuration of the present embodiment, although the shaping object 15 on the stacking stage 14 is moved in relation to the material layer 3 on the transfer member 5 to perform correction, the present invention is not limited to this. When the transfer member 5 is configured to be movable in the X, Y, and θ-directions, it is possible to correct the relative positional shift between the material layer 3 and the shaping object 15 by moving the material layer 3. In the correction of the present embodiment, the transfer member 5 and the stacking stage 14 may be moved in relation to each other to adjust the relative position between the transfer member 5 and the stacking stage 14.

Moreover, although the position of the material layer 3 is detected during movement of the transfer member 5 using an area sensor or a line sensor as the non-contact-type position sensor 8, the detection is not limited to this and the position of the material layer 3 may be detected in a stopping state of the transfer member 5 using an image sensor.
The stage correction mechanism 12 may include means for returning the respective motors to their origin positions and may have a function of returning the respective motors to the origin positions after a necessary shaping operation ends. In this way, a new shaping operation can start from the reference position of the stage correction mechanism 12.

As described above, according to the configuration of the shaping apparatus of the present embodiment, it is possible to suppress a positional shift during shaping as much as possible by performing registration. Thus, it is possible to form a high-quality shaping object having high shape accuracy and dimensional accuracy.
As a result, even when secondary processing such as sanding other end surface the shaping object surface is required, it is possible to shorten the time required for secondary processing. This leads to reduction of a manual operation and enables the cost to be decreased further. Moreover, the present invention can be ideally applied to even a case of forming a shape, where, e.g., secondary processing cannot be performed on an inner surface of a shaping object.

(Another Configuration Example of Stage Correction Mechanism)
Here, another configuration example of the stage correction mechanism 12 is illustrated in FIGS. 9A and 9B.
The stage correction mechanism 12 illustrated in FIG. 9A includes a base 31 for mounting the shaping object 15 and a first axis driving mechanism 32, a second axis driving mechanism 33, and a rotation axis driving mechanism 34 for adjusting the position of the base 31. Here, the rotation axis driving mechanism 34 is used for correcting a rotation direction about an axis vertical to a conveying surface of the transfer member. Moreover, the second axis driving mechanism 33 is used for correcting a conveying direction of the transfer member. Further, the first axis driving mechanism 32 is used for correcting a vertical direction in relation to the conveying direction within the conveying surface of the transfer member.
With this three-axis correction mechanism, it is possible to align the position of the material layer 3 on the transfer member and the position of the shaping object 15 stacked on the base 31.

The stage correction mechanism 12 illustrated in FIG. 9B includes a base 35 for mounting the shaping object 15 and a first axis driving mechanism 36, a second axis driving mechanism 38, and a third axis driving mechanism 37 for adjusting the position of the base 35. Here, the third axis driving mechanism 37 is used for correcting the conveying direction of the transfer member. Moreover, the first axis driving mechanism 36 and the second axis driving mechanism 38 are used for correcting a vertical direction in relation to a conveying direction within a conveying surface of the transfer member.
A rotation shaft 39 that rotatably supports the base 35 is formed at a distal end of each driving mechanism. When correction is made in the conveying direction of the transfer member 5, the third axis driving mechanism 37 only is moved. Moreover, when correction is made in a direction orthogonal to the conveying direction of the transfer member 5, the first and second axis driving mechanisms 36 and 38 are moved by the same amount. Moreover, since the base 35 can be rotated by driving the three axis driving mechanisms simultaneously, it is possible to align the position of the material layer 3 on the transfer member 5 and the position of the shaping object 15 on the base 35 using this combination of three axis driving mechanisms.
In this example, although the stage correction mechanism having a three-axis correction function has been described, the number of correction axes may be decreased when the accuracy of the mechanism is suppressed.

(Embodiment 2)
Hereinafter, Embodiment 2 will be described. In the present embodiment, constituent elements different from those of Embodiment 1 will be described, and the description of the same constituent elements as those of Embodiment 1 will not be provided.
FIG. 10 is a diagram illustrating a state in which registration markers used in the present embodiment are transferred to the transfer member 5.
In Embodiment 1 described above, registration markers are detected using a pair of opposing

registration markers

402 and 403. In contrast, in the present embodiment, an example in which positional shift amounts in the X, Y, and θ-directions are detected using a plurality of pairs of registration markers will be described.

In the present embodiment, a pair of opposing

registration markers

801 and 802 similar to the

registration markers

402 and 403 illustrated in FIG. 4 is used. Further, another pair of opposing

registration markers

803 and 804 having the same triangular shape as and reverse orientations from the

registration markers

801 and 802 is used. Further, still another pair of opposing

registration markers

805 and 806 similar to the pair of opposing

registration markers

801 and 802 is used. Further, still another pair of opposing

registration markers

807 and 808 similar to the pair of opposing

registration markers

803 and 804 is used.

The positional shift amounts Δθ, ΔX, and ΔY can be calculated for the four pairs of registration markers illustrated in FIG. 10 similarly to the method illustrated in FIGS. 5A to 5C and an overall positional shift amount can be calculated from the calculation results. Further, a positional shift amount in the Y-direction between the markers (801 and 803 and 805 and 807) arranged in the travelling direction can be calculated using the trigonometric ratio similarly to FIG. 5B.
In this way, even when it is not possible to detect a portion of a registration marker, it is possible to calculate the correction amount and to obtain a correction amount which is robust to the shape accuracy of a marker itself.

(Embodiment 3)
Hereinafter, Embodiment 3 will be described. In the present embodiment, constituent elements different from those of

Embodiments

1 and 2 will be described, and the description of the same constituent elements as those of Embodiment 1 will not be provided.
FIG. 11 is a diagram illustrating a state in which a registration marker used in the present embodiment is transferred to the transfer member 5.
In

Embodiments

1 and 2, an example in which a one-dimensional detection signal is acquired by a sensor having a circular or elliptical spot diameter. In contrast, in the present embodiment, an example in which shift amounts in the X, Y, and θ-directions are detected using a line sensor 91 capable of scanning a direction vertical to the conveying direction of the transfer member two-dimensionally is illustrated.

Reference numeral 901 is a registration marker configured such that a rectangular shape having sides parallel to the shaping region falls within a line width of a line sensor 91. The line sensor 91 scans the registration marker 901 two-dimensionally at a constant sampling interval.
Reference signs S1, S2, and S3 in FIG. 11 are examples of signals obtained by the line sensor 91 scanning the positions L1, L2, and L3 on the registration marker 901 and are herein referred to as sectional profiles.

In a cross-section at the position L1 of the registration marker 901, the signal S1 has High level in a region in which the registration marker 901 is present and has Low level in a region in which the registration marker 901 is not present. Here, when a shift in the θ-direction occurs in the registration marker 901, a line that connects the points P1, P2, and P3 indicating the edges of the registration marker in the respective sectional profiles skews as illustrated in FIG. 11. Thus, it is possible to calculate a shift amount Δθ in the θ-direction using the shift amount of the edge on the sectional profile and the sampling interval of the profile. Moreover, similarly to Embodiment 2, a shift amount ΔX in the X-direction can be calculated from the position of the upper end of the registration marker 901 after the shift Δθ is corrected, and a shift amount ΔY in the Y-direction can be calculated from the position of an edge in the horizontal direction of the registration marker 901.

According to the shaping apparatus of the present embodiment, since the registration marker edges are reproduced from many sectional profiles, it is possible to realize registration which is robust to shaping accuracy of the registration marker.

(Embodiment 4)
Hereinafter, Embodiment 4 will be described. In the present embodiment, constituent elements different from those of Embodiments 1 to 3 will be described, and the description of the same constituent elements as those of Embodiments 1 to 3 will not be provided.
FIG. 12 is a cross-sectional view schematically illustrating a schematic configuration of a shaping apparatus according to the present embodiment. In FIG. 12, constituent elements indicated by reference numerals 41 to 57 and 61 have the same functions as the constituent elements indicated by reference numerals 1 to 17 and 21 in FIG. 1.
The present embodiment is different from Embodiments 1 to 3 described above in that a linear motion stage 62 is provided on the stacking stage 54 in addition to a stage correction mechanism 52. The stacking stage 54 is movable in an up-down direction by a stage lifting mechanism 53.
The operation of the stage lifting mechanism 53 allowing a material layer 43 on the transfer member to be sandwiched between an opposing member 57 and the upper surface of the shaping object 55 together with a transfer member 45 is the same as that of Embodiment 1. Thus, the operation after the material layer 43 is sandwiched between the opposing member 57 and the upper surface will be described with reference to FIG. 12.

As illustrated in FIG. 12, after the material layer 43 is sandwiched between the opposing member 57 and the upper surface of the shaping object 55 together with the transfer member 5, the material layer 43 is moved in the direction indicated by arrow 63 illustrated in FIG. 12 by synchronizing the tangential speed of the linear motion stage 62 and the transfer member 45. In this case, the stage correction mechanism 52 continues correction according to the shift of the transfer member 45. The shift amount of the transfer member 45 is obtained by a sensor (not illustrated) that detects an end surface or the like of the transfer member 45. Even when a conveying shift of the transfer member 45 occurs due to this correction, a shift does not occur in the interface between the shaping object 55 and the transfer member 45 and reliable stacking bonding strength can be secured.

(Embodiment 5)
Hereinafter, Embodiment 5 will be described. In the present embodiment, constituent elements different from those of Embodiments 1 to 4 will be described, and the description of the same constituent elements as those of Embodiments 1 to 4 will not be provided.
FIG. 13 is a cross-sectional view schematically illustrating a schematic configuration of a stacking and shaping apparatus according to the present embodiment. The present embodiment is different from Embodiments 1 to 4 in that the shaping apparatus includes a non-contact-type skew sensor (transfer member end detection unit) 22 that is disposed near an upper portion of the stacking stage 14 so as to measure a belt end position in a direction orthogonal to the conveying direction of the transfer member 5.
In the correction control method of Embodiments 1 to 4, correction is performed based on a positional shift of the material layer detected by the non-contact-type sensor 8. Thus, although it is possible to correct a positional shift of the material layer occurred up to the position of the non-contact-type sensor 8 after the material layer is generated, it is not possible to correct a conveying error occurring in the course in which the material layer is conveyed from the non-contact-type sensor 8 up to a position at which the material layer is attached to the stacking object 15. In contrast, according to the present embodiment, it is possible to correct a positional shift including a conveying error occurring in a path between the non-contact-type sensor 8 and the stacking position.

The flow of a correction process according to the present embodiment will be described with reference to the example of the flowchart of the correction process illustrated in FIG. 14.
In step S1501, the image generation control unit 201 causes registration markers to be transferred to the transfer member 5. This is the same step as step S301 of FIG. 3. In step S1502, the registration markers on the transfer member 5 are detected by the non-contact-type sensor 8, and with the correction control unit 204 a distal end position and a passing distance of each of the registration markers are stored. Subsequently, in step S1503, the positional shift amounts in the X, Y, and θ-directions, of the material layer are calculated from the detection results in step S1502.

In step S1504, the correction control unit 204 measures an end position in a direction orthogonal to a conveying direction of the transfer member 5 with the aid of the non-contact-type skew sensor 22. In step S1505, the correction control unit 204 calculates the movement amounts in the Y and θ-directions of the transfer member 5 from a time point at which the registration markers are detected in step S1502 to a time point at which the material layer reaches a stacking position from the detection result of the end position of the transfer member 5 obtained in step S1504.
Subsequently, in step S1506, the correction control unit 204 superimposes the positional shift of the material layer calculated in step S1503 and the movement amount of the transfer member 5 calculated in step S1505 to calculate the correction amount. In step S1507, the correction control unit 204 controls the stacking stage 14 so that a positional shift corresponding to the positional shift amounts in the three directions calculated in step S1506 is corrected. Moreover, the stacking control unit 202 moves the stacking stage 14 vertically to stack the material layer 3 on the shaping object 15.

FIG. 15 is a diagram illustrating an example of a method of measuring the end position of the transfer member 5 according to the present embodiment and is a diagram illustrating the lower surface of the transfer member 5 as seen from a vertically lower side in the direction of the stacking stage 14. In FIG. 15, a state in which the transfer member 5 skews is indicated by solid line 1601 and a state in which the transfer member 5 does not skew is indicated by dot line 1602.
In the present embodiment, the non-contact-type skew sensor 22 is a transmission-type line sensor and measures the end position of the transfer member 5 near the stacking position. Reference numeral 1606 indicates the position detected by the non-contact-type sensor 8 and reference numeral 1607 indicates the position detected by the non-contact-type skew sensor 22.

In FIG. 15, it is assumed that the transfer member 5 has moved from the position indicated by dot line 1602 to the position of solid line 1601 in a period from a time point at which the registration markers was detected by non-contact-type sensors 8-1 and 8-2 to a time point at which the material layer 3 reached the stacking position 1607. A difference ΔYb of the

end positions

1601 and 1602 measured by the non-contact-type skew sensor 22 in this period is a conveying error in a direction orthogonal to the travelling direction of the transfer member 5, occurring in the course in which the material layer 3 is detected by the non-contact-type sensor 8 and is conveyed to the stacking position 1607. Moreover, a conveying error Δθb in the rotation direction can be calculated using the difference ΔYb and the distance Lb that the material layer 3 detected at the position 1606 moves until the material layer 3 is detected at the position 1607. The correction control unit 204 performs a correction process by adding the errors ΔYb and Δθb calculated in the present embodiment to the amounts ΔY and Δθ calculated from the registration markers by the method illustrated in FIG. 5.

According to the present embodiment, it is possible to correct a conveying error occurring in the course in which the material layer 3 conveyed from the non-contact-type sensor 8 to the stacking position in addition to the positional shift occurring in the course in which the material layer 3 is conveyed to the position of the non-contact-type sensor 8 after the material layer 3 is generated. Thus, it is possible to generate a shaping object with higher accuracy.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2015-170700, filed on August 31, 2015 and Japanese Patent Application No. 2016-153995, filed on August 4, 2016, which are hereby incorporated by reference herein in their entirety.

Claims

A shaping apparatus comprising:
a material layer forming unit that forms a material layer formed of a shaping material, based on given data;
a transfer member that conveys the material layer transferred from the material layer forming unit; and
a stage on which the material layer conveyed by the transfer member is stacked,
the shaping apparatus fabricating a three-dimensional object formed of the shaping material on the stage, the apparatus further comprising:
a detection unit that detects a position of the material layer on the transfer member;
a measurement unit that measures from detection results obtained by the detection unit a positional shift amount of the material layer on the transfer member; and
an adjustment unit that is capable of adjusting a relative position between the transfer member and the stage by moving the stage in a direction orthogonal to a stacking direction of the material layer and a rotation direction about an axis extending in the stacking direction of the material layer, based on the positional shift amount measured by the measurement unit.
The shaping apparatus according to claim 1, further comprising:
an appending unit that appends data of a registration marker to the data given to the material layer forming unit, wherein
the detection unit is provided at a position corresponding to the registration marker to detect a position of the registration marker.
The shaping apparatus according to claim 2, wherein
the registration marker is a figure having a first edge disposed to be orthogonal to a travelling direction of the transfer member and a second edge disposed to be oblique to the travelling direction of the transfer member,
the measurement unit acquires from a detection timing of the first edge the position of the material layer in relation to the travelling direction of the transfer member and acquires from a difference between the detection timing of the first edge and a detection timing of the second edge a positional shift amount of the material layer in relation to a direction orthogonal to the travelling direction of the transfer member,
two registration markers are arranged in a direction orthogonal to the travelling direction of the transfer member, and
the measurement unit acquires from a difference between the detection timings of two first edges a positional shift amount of the material layer in relation to the rotation direction about an axis orthogonal to a transfer surface of the transfer member to which the material layer is transferred.
The shaping apparatus according to claim 2 or 3, wherein
the measurement unit performs a noise reduction process of removing noise components from a signal of the registration marker detected by the detection unit.
The shaping apparatus according to any one of claims 1 to 4, wherein
the adjustment unit adjusts a relative position between the transfer member and the stage, based on a difference between a positional shift amount of the material layer and a positional shift amount of a previous material layer, which is one layer before the material layer, based on a relative position between the transfer member and the stage when the material layer on the transfer member is stacked on the stage and the previous material layer, which is one layer before the material layer, is stacked on the stage.
The shaping apparatus according to any one of claims 1 to 5, wherein
when a value of the positional shift amount of the material layer measured by the measurement unit exceeds a predetermined range, the adjustment unit maintains a relative position between the transfer member and the stage when the material layer is stacked on the stage and a previous material layer, which is one layer before the material layer, is stacked on the stage.
The shaping apparatus according to any one of claims 1 to 6, further comprising:
a skew adjustment unit that adjusts skew of the transfer member.
The shaping apparatus according to any one of claims 1 to 6, further comprising:
a transfer member end detection unit that is disposed near a stacking position, at which the material layer is stacked on the stage, so as to detect an end position of the transfer member, wherein
the measurement unit calculates from a detection result obtained by the transfer member end detection unit a conveying shift amount of the transfer member within a surface of the transfer member, the shift occurring from the detection unit up to the stacking position, and
the adjustment unit adds the conveying shift amount of the transfer member to the positional shift amount of the material layer acquired by the measurement unit to adjust the relative position between the transfer member and the stage.
The shaping apparatus according to any one of claims 1 to 8, further comprising:
an origin detection unit that detects an origin position of the stage; and
a storage unit that stores a moving amount of the origin position of the state in relation to a reference position of a shaping apparatus body, wherein
the adjustment unit returns the stage to the reference position after a three-dimensional object fabricating operation ends.
A shaping method used for a shaping apparatus including:
a material layer forming unit that forms a material layer formed of a shaping material, based on given data;
a transfer member that conveys the material layer transferred from the material layer forming unit; and
a stage on which the material layer conveyed by the transfer member is stacked,
the shaping apparatus fabricating a three-dimensional object formed of the shaping material on the stage,
the method comprising:
a step of appending data of a registration marker to the data given to the material layer forming unit;
a step of operating a detection unit to detect the registration marker included in the material layer on the transfer member;
a step of operating a measurement unit to measure from detection results obtained by the detection unit a positional shift amount of the material layer on the transfer member; and
a step of adjusting a relative position between the transfer member and the stage by moving the stage in a direction orthogonal to a stacking direction of the material layer and a rotation direction about an axis extending in the stacking direction of the material layer, based on the positional shift amount measured by the measurement unit.