WO2007094629A1

WO2007094629A1 - Apparatus and method for manufacturing pipe with multi-layer wall

Info

Publication number: WO2007094629A1
Application number: PCT/KR2007/000824
Authority: WO
Inventors: Woon Yong Park
Original assignee: Green Polytech Co., Ltd.
Priority date: 2006-02-15
Filing date: 2007-02-15
Publication date: 2007-08-23
Also published as: JP2009526675A; MY148015A; JP4912415B2; AU2007215670B2; AU2007215670A1

Abstract

Disclosed is an apparatus and method for manufacturing a pipe having multiple layers. The apparatus comprises a winder having a cylindrical shape, a driving means for rotating the winder, an internal and an external layer extruder for extruding resin into resin sheets to form an internal layer and an external layer, respectively, a middle layer sheet supply device for pulling out a middle layer sheet using a pair of rollers from fused material, and a pressure roller for pressing a resultant structure, in which the sheets are wound around the winder. The manufacturing apparatus and method according to the present invention have advantageous effects of making it possible to manufacture a pipe having multiple layers and having high internal and external pressure strength, sufficient hardness to endure thermal shocks, and good durability and reliability.

Description

[DESCRIPTION]

APPARATUS AND METHOD FOR MANUFACTURING PIPE WITH MULTILAYER WALL

[Technical Field] The present invention relates to an apparatus and a method for manufacturing a pipe having multiple layers made of synthetic resin, and more particularly to an apparatus and a method for manufacturing a pipe having multiple layers, having high internal and external pressure strength, and excellent airtightness .

[Background Art]

FIG. 1 and FIG. 2 illustrate one exemplary conventional multi-layer pipe, which is disclosed in Korean Patent Publication No. 10-0290302, which is entitled "Apparatus and Method for Manufacturing Three-wall Pipe" .

The conventional art will be described with reference to FIG. 1 and FIG. 2.

The three-layer pipe 1 shown in FIG. 1 comprises an inner layer 2 made by winding a strip manufactured through an extrusion method in a manner such that edges thereof overlap, a middle layer 3 provided on the inner layer 2 and in a manner such that edges thereof overlap and the overlapping portion is extruded, and an external layer 4 provided on the middle layer 3 in a manner such that edges thereof overlap and the overlapping portion is extruded, in which the internal layer 2, the middle layer 3 and the external layer 4 are heat extruded.

The external layer 4 and the internal layer 2 are made of polyethylene (PE) , and the middle layer 3 is made of a recycled material . A method of manufacturing the three-layer pipe described above will be described with reference to FIG. 2.

The internal layer 2 which has the strip shape and is extruded through one nozzle (not shown) is wound along a roller (not shown) of a winder. At this time, the edge of the strip constituting the internal layer 2 is overlapped.

After the internal layer 2 is wound on the winder, the middle layer 3, which is a strip extruded through another nozzle, is wound along the surface of the internal layer 2.

At this time, the edge of the strip of the middle layer 3 is overlapped, as shown in (b) of FIG. 2. If the middle layer 3 is extruded from the nozzle 13 and wound on the internal layer 2, the internal 2 and the middle layer 3 are thermally bonded to each other, and then cooled as water is sprayed thereto from a cooling device. In this instance, the overlapping portions of the middle layer 3 and the overlapping portions of the internal layer 2 are disposed so as to be spaced apart from (alternate with) each other.

After the winding of the middle layer 3 is finished, the overlapping portions of the middle layer 3 are pressed using a roller 3, shown in (b) of FIG. 2, to make the surface of the middle layer 3 smooth and planar.

Next, the external layer 4 is extruded from a nozzle which is different from the nozzles for the internal layer 2 and the middle layer 3 and is wound on the middle layer 3 in a manner such that the edges thereof overlap each other. At this time, the location of the overlapping portions of the external layer 4 does not overlap the location of the overlapping portions of the middle layer 3, as shown in (d) of FIG. 2. The external layer 4 is thermally bonded onto the surface of the middle layer 3 , which is not yet cooled, while it is extruded and wound, and is then cooled by a cooling device.

After the winding of the external layer 4 is finished, the overlapping portions of the external layer 4 are pressed using a roller 31, as shown in (d) of FIG. 2, so that the pipe having the sectional shape shown in (e) of FIG. 2 is produced. After the external layer 4 is cooled, the production of the pipe is complete. The three-layer pipe 1 manufactured through the above- described method extends a long distance over a work table in front of the winder, and is marketed after being cut to have a desired length.

The conventional three-layer pipe cannot endure large external shocks because it is manufactured in a manner such that only the edges of each layer overlap, and further it has upper internal pressure strength and tensional strength limits .

Further, in the case in which the adjacent layers are made of different materials, the binding force between the adjacent layers is weak, so that the layers can be separated or cracked, resulting decreased strength when thermal shocks are applied to the pipe.

Still further, according to the Korean Patent, because part of each layer is overlapped when each layer is wound, there is an upper limit to the thickness of the middle layer 3. That is, in order to increase the thickness of the middle layer 3, two or three strips must be separately extruded and wound in an overlapping manner.

The conventional multiple-layer pipe has problems in that the productivity and quality thereof is low because it is difficult to continuously supply waste plastic having an optimal thickness, and in that it is difficult to adjust the thickness of the middle layer and melting state of the waste plastic for the middle layer. [Disclosure]

[Technical Problem]

In order to solve the above problems, it is an object of the present invention to provide an apparatus and a method for manufacturing a pipe having multiple layers, which has high internal and external pressure strength and has strong thermal endurance. That is, the pipe has good durability and high reliability.

It is a further object of the present invention to provide an apparatus and method for manufacturing a pipe having multiple layers, in which sheets for an internal layer and an external layer are provided through an extrusion method and a sheet for a middle layer is provided through a pulling method so that recycled material for the middle layer can be smoothly and continuously supplied, and the adjustment of the thickness and fusing status of the middle layer is easy, which results in the ease of manufacture of a pipe having multiple layers and improved pipe quality.

It is a still further object of the present invention to provide an apparatus and method for manufacturing a pipe having multiple layers, which has high density and strength and high quality by increasing the binding force between adjacent layers constituting the pipe through a method in which cooling water is supplied to stacked sheets so that they are cooled somewhat, compressed air is sprayed on a structure in which the adjacent layers are stacked in order to remove moisture, and a new layer is deposited on the dried structure.

[Technical Solution]

In order to achieve the above objects and advantageous effects, according to one aspect of the present invention, there is provided an apparatus for manufacturing a pipe having multiple layers, comprising a winder having a cylindrical shape, a driving means for driving the winder, an internal layer extruder and an external layer extruder for extruding resin sheets used for forming an internal layer and an external layer, respectively, a middle layer sheet supply device for pulling a resin sheet for a middle layer using a pair of pulling rollers from fused material for the middle layer, and a pressure roller installed on the side surface of the winder for pressing a structure in which resin sheets for forming the internal layer, the middle layer and the external layer are wound.

The apparatus may further comprise a cooling water sprayer arranged near the winder for spraying cooling water when the resin sheets are wound.

The apparatus may further comprise a moisture remover installed behind the cooling water sprayer in the rotational direction of the winder for removing moisture remaining on the surface of the resin sheets which are wound.

The moisture remover may have a structure which can spray compressed air. The cooling water sprayer is preferably installed in a manner such that it can spray cooling water to a lower side of the winder, and the moisture remover is preferably installed in a manner such that it can spray compressed air to an upper side of the winder. The moisture remover can be configured in a manner such that it can spray compressed air in a slanted direction against the surface of the resin sheets which are wound.

The middle layer sheet supply device includes a tank in which fused material for the middle layer is stored, a pair of pulling rollers is installed under the tank for pulling the fused material when rotated by the driving means, and a distance adjustment device for adjusting the distance between the pair of pulling rollers.

The pulling roller has a structure through the inside of which cooling water passes in order to cool fused material .

According to another aspect of the present invention, there is provided a method for manufacturing a pipe having multiple layers, comprising a sorting step for collecting waste plastic and sorting paper, metal, glass, and cloth from the collected waste plastic to obtain only plastic; a pulverizing step for pulverizing the plastic into plastic chips of a predetermined size or smaller; a fusing and mixing step for fusing the plastic chips by introducing the pulverized plastic chips into a double screw fusing device, applying heat to the plastic chips to fuse them at a predetermined temperature, and mixing the plastic chips while fusing them; a middle layer sheet forming step for pulling a middle layer sheet, having a predetermined thickness and width, using a pair of pulling rollers, which is a middle layer sheet supply device; a pipe forming step for extruding resin sheets for forming an internal layer and an external layer using an internal layer extruder and an external layer extruder, and continuously winding the middle layer sheet for forming the middle layer and the resin sheets for the internal layer and the external layer around a winder in a spiral manner in order to form the shape of a pipe; and a cooling step for cooling the pipe by spraying cooling water onto the wound resin sheets and chopping the pipe into pieces having predetermined sizes .

In the method, the fusing and mixing step may include a first fusing and mixing step, a second fusing and mixing step and a third fusing and mixing step, and wherein a heating temperature of the first fusing and mixing step is in a range from 240 to 280^°C, and a heating temperature of the second and third fusing and mixing steps is in a range from 180 to 220^°C, which is lower than a range for the first fusing and mixing step.

In the method, a supply of the middle layer sheet in the middle layer sheet forming step may be conducted through a gravity feeding method, in which the middle layer sheet, pulled out by the two pulling rollers falls naturally.

In the pipe forming step, when the sheets are wound, cooling water may be directly sprayed onto surfaces of the resin sheets for every layer so that the resin sheet can be rapidly cooled. In the method, a temperature of the resin sheets which are rapidly cooled may be in a range from 100 to 150^°C. In the method, if the resin sheets are cooled by the cooling water sprayed onto the surface thereof, moisture remaining on the resin sheets may be removed by compressed water sprayed onto the surface thereof right before a new layer is wound.

According to a still further aspect of the present invention, there is provided a method for manufacturing a pipe having multiple layers, in which the pipe is manufactured in a manner such that a middle layer sheet for forming a middle layer of the pipe and resin sheets for forming an internal layer and an external layer are supplied to a winder so that the sheets are continuously wound around the winder in a spiral manner, wherein cooling water is directly sprayed onto all outer surfaces of the resin sheets when the resin sheets are wound, and moisture remaining on the surfaces of the resin sheets is removed by compressed air which is sprayed on the surfaces of the resin sheet before a new layer is wound.

[Advantageous Effect] According to the apparatus and method of the present invention, it is possible to manufacture the pipe having multiple layers, which has excellent durability and high reliability due to high internal and external pressure strength and high tolerance to thermal shock. Further, it is possible to easily manufacture the pipe having multiple layers having the above-described advantageous effects because recycled material for the middle layer can be smoothly and continuously supplied. This is because the sheets for the internal layer and the external layer are provided through an extrusion method, and the sheet for the middle layer is provided through a pulling method using a roller. Further, since two rollers are used to form the middle layer, the adjustment of the thickness of the middle layer and of the fusing status of material for the middle layer is easy. This results in the effective production of a pipe having a desired size.

Still further, it is possible to improve the bonding force between adjacent layers, resulting in increased strength and density of the pipe and improvement of pipe quality through a method in which cooling water is supplied to a structure in which sheets are stacked in order to cool the structure to a predetermined degree, moisture is removed from the structure by spraying compressed air onto the structure, and then the new sheet is provided on the stacked sheets . [Description of Drawings]

FIG. 1 is a perspective view illustrating a three-layer pipe according to the conventional art;

FIG. 2 is an enlarged view illustrating part of the three-layer pipe shown in FIG. 1; FIG. 3 is an enlarged view illustrating part of a pipe having multiple layers according to one embodiment of the present invention;

FIG. 4 is a sectional view taken along line A-A of FIG. 3;

FIG. 5 is a view illustrating the winding process during a process of manufacturing a pipe, using an apparatus for manufacturing a pipe according to the embodiment of the present invention;

FIG. 6 is a sectional view illustrating the part of the pipe that is being wound, taken along line B-B shown in FIGH. 5;

FIG. 7 is a side view illustrating an apparatus for manufacturing a pipe according to one embodiment of the present invention;

FIG. 8 is a front view illustrating the apparatus for manufacturing a pipe according to one embodiment of the present invention;

FIG. 9 is a sectional view illustrating a middle supplier, taken along line C-C shown in FIG. 8; and

FIG. 10 is a sectional view illustrating a wound part of a pipe having multiple layers according to another embodiment of the present invention.

[Best Mode]

An apparatus for manufacturing a pipe having multiple layers comprises a winder having the cylindrical shape, a driving means for rotating the winder, an internal layer extruder and an external layer extruder for extruding sheets of resin for forming an internal layer and an external layer, respectively, a middle layer sheet supply device for pulling a sheet of resin for forming a middle layer using a pair of pulling rollers from fused material, and a pressure roller disposed on the side surface of the winder for pressing the structure in which resin sheets are wound around the winder to be bonded to each other.

A method for manufacturing a pipe having multiple layers comprises a sorting step for collecting waste plastic and sorting out paper, metal, glass and cloth from the collected waste plastic, so as to obtain only plastic, a pulverizing step for pulverizing the waste plastic into plastic chips smaller than a predetermined size, a fusing and mixing step for fusing the plastic chips by inputting the plastic chips into a double screw fusing device and applying heat to the plastic chips to heat them to a predetermined temperature while mixing the plastic chips while fusing them, a middle layer sheet forming step for pulling a sheet having a predetermined thickness and width from the fused plastic using a pair of pulling rollers, a pipe forming step for forming a cylinder-type pipe having multiple layers by extruding internal layer and external layer sheets for forming an internal layer and an external layer, respectively, using an internal layer extruder and an external layer extruder, and continuously winding the internal layer and external layer sheets and a middle layer sheet around a winder in a spiral manner, and a cooling step for cooling the wound structure by spraying cooling water onto the wound structure and chopping the cooled wound structure into predetermined lengths . In the manufacturing method, the middle layer sheet for forming the middle layer of the pipe and the internal layer sheet and the external layer sheet for forming the internal layer and the external layer are continuously supplied to the winder so as to be wound around the winder in a spiral manner, at the same time the cooling water is sprayed onto the surface of each layer while the sheets are wound so that each layer can be rapidly cooled, and compressed air is sprayed onto the surface of each cooled layer to remove moisture before a new layer is applied on the surface of the layer.

[Mode for Practicing the Invention]

Hereinafter, the preferred embodiment of the present invention will be described with reference to the accompanying drawings . The embodiment mainly refers to a pipe having three layers, but the apparatus and method according to the present invention are not limited thereto. That is, the pipe having multiple layers may be a pipe having two layers or a pipe having four layers. FIG. 3 is a schematic view illustrating a pipe having multiple layers manufactured using an apparatus and a method for manufacturing a pipe having multiple layers according to one embodiment of the present invention, in which the pipe is partially cut away and is viewed in an enlarged state, and FIG. 4 is a sectional view taken along line A-A, shown in FIG. 3.

As shown in FIG. 3 and FIG. 4, the pipe having multiple layers 50, manufactured using the apparatus and through the method according to the present invention, comprises an internal layer 51, a middle layer 52 and an external layer 53, which are wound in a stacking manner. Each layer of the layers 51, 52 and 53 is preferably made of synthetic resin such as PE.

The middle layer 52 may be made by fusing recycled material such as waste plastic. The specific blending ratio of raw material for the middle layer will be disclosed below.

Each layer of the layers 51, 52 and 53 is made through a method in which a sheet of synthetic resin, which has a predetermined width, is extruded from fused synthetic resin, the synthetic resin sheet is helically wound, and the helically wound synthetic resin sheet is cured by thermosetting.

When winding the synthetic resin sheets, portions of each synthetic resin sheet are interposed between adjacent (upper and lower) resin sheets. That is, referring to FIG. 3, the external layer 53 is formed to have a portion 53a interposed between turns of the middle layer 52, and the internal layer 51 has a portion 51a interposed between turns of the middle layer 52.

According to one embodiment of the present invention, the three layers 51, 52 and 53 are interleaved, but the present invention is not limited thereto. That is, under certain circumstances, only the external layer 53 is interposed between turns of the middle layer 52, or only the middle layer 52 can be interposed between turns of the internal layer 51. Further, each of the layers 51, 52 and 53 can be formed in a manner such that the turns of each layer overlap each other.

If the turns of each layer of the layers 51, 52 and 53 are wound to overlap each other and are also interleaved with turns of the other layers 41, 52 and 53, the bonding force between the layers 51, 52 and 53 is increased, the compressive and tensional strength of the completed pipe is improved, and the ability to withstand thermal shocks is improved. Further, when winding the relatively thick layer, out of the layers 51, 52 and 53, the synthetic resin sheet for the relatively thick layer is preferably wound in a manner such that it is inclined in the longitudinal direction of the pipe and the turns thereof overlap each other. According to the embodiment of the present invention, the synthetic resin sheet for the middle layer 52 is wound to be inclined in the longitudinal direction of the pipe while the turns of the synthetic resin sheet for the middle layer 52 overlap each other .

The structure of the pipe will be described in detail with reference to FIG. 5 and FIG. 6.

FIG. 5 illustrates the process by which the resin sheets are wound using the apparatus for manufacturing a pipe having multiple layers, and FIG. 6 illustrates a portion of the pipe having multiple layers being wound according to the embodiment of the present invention.

As shown in the drawings, the pipe 50 is manufactured through a method in which resin sheets 51, 52 and 53 for forming layers 51, 52 and 53, respectively, which are extruded using extruders, and an inserting device which will be described below, are wound along the surface of a winder 60, stacked on each other, thermally fused and bonded, and then cooled and cured.

As described above, in order to manufacture the pipe 50 in which a portion of the external layer 53 is interposed between turns of the middle layer 52, and a portion of the middle layer 52 is interposed between turns of the internal layer 51 (the internal layer is interposed between turns of the middle layer after winding) , as shown in FIG. 5, an end portion 53a (left side in the drawing) of the sheet 53P for forming the external layer 53 is disposed under the sheet 52P for forming the middle layer 52 , and an end portion 52a of the sheet 52P for forming the middle layer 52 is disposed under the sheet 51P for forming the internal layer 51.

In this instance, the width of the overlapping portion of the sheets 53P and 51P for the external layer and the internal layer is in the range in which the overlapping portion of the sheets 53P and 5Ip can be interposed between overlapping portions of turns of the sheet 52 for forming the middle layer, and a portion of the sheets 53P and 51P, other than the overlapping portion, has a width in the range that can be overlapped by turns of the sheets 53P and 51P which were previously wound.

The process of winding the pipe is shown in FIG. 6. That is, as shown in FIG. 5, in the case in which the sheets 51P, 52P and 53P for forming the internal layer 51, the middle layer 52 and the external layer 53, respectively, are wound around the winder 60 in a manner such that predetermined portions thereof overlap each other, a portion of the sheet for forming the external layer 53 is interposed between turns of the sheet for forming the middle layer 52, which is wound at an incline in the longitudinal direction of the pipe, and the sheet for forming the middle layer 52 is interposed between turns of the sheet for forming the internal layer 51.

In this manner, after the sheet for forming the external layer 53 is wound, the structure in which the sheets for forming the internal layer, the middle layer and the external layer is pressed using a pressure roller 65, and thus the layers 51, 52 and 53, which are not yet cured but are in a fused state, are bonded to each other when the external layer is pressed. As a result, the pipe having multiple layers is manufactured.

Further, since the middle layer 52 is wound in an overlapping manner in a state in which it is inclined, the middle 52 can be relatively thick in comparison with the internal layer 51 and the external layer 53. The method for manufacturing a pipe having multiple layers according to the embodiment of the present invention will be described below.

FIG. 7 is a side plan view illustrating the apparatus for manufacturing a pipe having multiple layers, FIG. 8 is a front plan view illustrating the apparatus for manufacturing a pipe having multiple layers, and FIG. 9 is a sectional view taken along line C-C shown in FIG. 8.

As shown in FIG. 7 and FIG. 8, the apparatus for manufacturing a pipe having multiple layers comprises a winder 60 in which a plurality of winding rollers 61 is arranged in a cylindrical arrangement, a motor 63 for rotating the winder 60, an internal layer extruder 71 and an external layer extruder 73 for extruding fused resin to realize resin sheets for forming the internal layer 51 and the external layer 53, a middle layer supply device 72 for supplying a resin sheet for the middle layer, a pressure roller 65 installed around the winder 60 for pressing a structure in which the resin sheets are wound, a cooling water sprayer 67 installed around the winder 60 for spraying cooling water when the resin sheets are wound around the winder 60, and a moisture remover 68 installed behind the cooling sprayer 67 in the rotating direction of the winder 60 for removing moisture present on the surfaces of the wound resin sheets .

The middle layer sheet supply device 72, the internal layer extruder 71, and the external layer extruder 73 are arranged in a manner such that the sheets 51P, 52P and 53P for forming the layers 51, 52 and 53, respectively can be wound around the winder 60 to overlap each other.

For reference, FIG. 7 and FIG. 8 illustrate only dies of the internal layer extruder 71 and the external layer extruder 73, but the pars, but the dies, each with a slot from which fused resin is extruded, are connected to a resin supply device which supplies fused resin, like known extruders. Further, locations of the extruders 71 and 73 are determined based on whether the layers 51, 52 and 53 can be partially overlapped by adjacent layers thereof. That is, the locations of the extruders 71 and 73 can be changed.

In FIG. 7, the die of the internal layer extruder 71 is installed under the die of the external layer extruder 73, but this installation structure is just an example. Accordingly, alternatively, the die of the internal layer extruder 71 can be installed on the left side of the middle layer sheet inserting device 72.

Alternatively, as shown in FIG. 10, in the case in which the layers 51, 52 and 53 are not inserted between adjacent layers thereof when the pipe is manufactured, the locations of the extruders 71 and 73 and the middle layer sheet inserting device 73 may be determined in order to achieve this purpose.

The configuration of the middle layer sheet supply device 72 will be described below.

The middle layer sheet supply device 72 includes a tank 72A in which fused material is stored and a pair of pulling rollers 72B is driven by a motor 72C so as to discharge the fused material from the tank 72A. With reference to FIG. 9, the pulling rollers 72B, the distance between which can be adjusted by a distance adjustment device 85, are arranged parallel to each other, and the rollers 72B are rotated by the motor 72C, so that the sheet 52P for forming the middle layer is discharged. The distance adjustment device 85 adjusts the distance between the pulling rollers 72B in order to adjust the thickness of the sheet 52P for the middle layer which is pulled out from between the pulling rollers 72B. Reference numeral 86 denotes a thickness adjustment handle for adjusting the distance in the distance adjustment device 85. The distance adjustment device 85 can adjust the distance between the two rollers 72B by changing the locations of support structures, such as a bearing 89 supporting the two rollers 72B.

The two rollers 72B pivots on shafts 88, and the shafts 88 are supported by the support structures 90 using the bearings 89. Accordingly, the distance adjustment device 85 can adjust the distance between the two rollers 72B by adjusting the distance between the support structures 90 supporting the bearings 89, and the thickness adjustment handle 86 is connected to the support structure 90 in a turn- buckle screwing manner, thereby making it possible to adjust the distance between the two rollers 72B.

The pulling rollers 72B are configured in a manner such that cooling water can pass therethrough, so that a resin sheet having a predetermined thickness can be continuously pulled from between the two rollers 72B because fused material for forming the middle layer 52 is slightly cured before it is pulled out. The pulling roller 72 has a structure through which cooling water can pass, meaning that it has a cooling water introducing hole 81 in one side thereof and a cooling water discharging hole 83 in another side thereof.

The cooling water introducing hole 81 and the cooling water discharging hole 83 is preferably coupled to the shafts 88 of the pulling rollers 72B. In this case, the shafts 88 of the two rollers, which are rotating bodies, are inserted into the cooling water introducing hole 81 and the cooling water discharging hole 83, which are tubular.

Further, it will be obvious that sealing members are provided at the coupling portions between the cooling water inserting hole 81 and the cooling water discharging hole 83 and the shafts 88 of the rollers.

Alternatively, in the case in which the middle layer 52 is made of normal fused resin rather than complex plastic waste, the middle layer sheet supply device 72 is not used, but an extruder, similar to the internal layer extruder 71 or the external layer extruder, can be used to form the middle layer .

The cooling water sprayer 67 and the moisture remover 68 will be described below. As shown in FIG. 5 and FIG. 7, the cooling water sprayer 67 includes a plurality (preferably 3 to 5) of nozzles, so that it can spray cooling water upward to a resin sheet wound around the winder 60 from the underside of the winder 60. The cooling water sprayers 67 may be installed on both sides of the winder 60 under the winder 60.

The moisture remover 68 is preferably a nozzle structure so that it can spray compressed air. The cooling water sprayer 67 is installed under the winder 60 but the moisture remover 68 is installed above the winder 60 so as to spray compressed air to the upper surface of the winder 60. AS shown in FIG. 5, the moisture remover 68 is configured in a manner such that it can spray compressed air onto the surface of the resin sheet wound around the winder

60 in a slanted direction in order to easily remove moisture remaining on the surface of the resin sheet.

The apparatus for manufacturing a pipe having multiple layers further includes a cooling device for curing the completed pipe wound around the winder 60. The cooling device 60 is configured in a manner such that it can spray cooling water from the inside of the winder 60 or from the outside of the winder 60. The configuration of the cooling device is generally known, and thus a detailed description thereof will be omitted.

The method for manufacturing the pipe having multiple layers using the above-described apparatus will be described below.

With reference to FIG. 8, if the motor 63 rotates the winder 60, the internal layer extruder 71, the external layer extruder 73, and the middle layer sheet supply device 72 are driven, so that the sheets 51P, 52P and 53P for forming the internal layer, the middle layer and the external layer are discharged.

The sheets 51P, 52P and 53P are wound around and stacked on the winder 60. At this time, as shown in FIG. 6, a portion of the sheet 53P for forming the external layer is overlapped by a portion of the sheet 52P for forming the middle layer, and a portion of the middle layer 52P for forming the middle layer is overlapped by the sheet 51P for forming the internal layer.

In FIG. 6, the dotted line shows the state right before the sheets are wound around the winder 60, and the solid line shows the state after the sheets have been pressed by the pressure roller 65 and bonded to each other.

As described above and shown in FIG. 3 and FIG. 6, the sheets 51P, 52P and 53P are stacked in a manner such that portions of the internal layer 51 and the external layer 53 are interposed between turns of the middle layer 52.

After the sheets 51P, 52P and 53P are stacked, if cooling water is sprayed to the stacked sheets from the inside of the pipe or from the outside of the pipe using the cooling device (not shown) , the bonded portions are cured and the pipe having three layers is completed.

The method for manufacturing the pipe according to the present invention will be described in detail .

According to embodiment of the present invention, the middle layer sheet 52P of the pipe 50 is manufactured using complex synthetic resin such as complex plastic waste.

The method for manufacturing the pipe having multiple layers comprises a waste plastic collection and sorting step for collecting one or more kinds of waste plastic and sorting out non-plastic material, such as paper, metal, glass and cloth from the collected waste plastic, a pulverizing step for pulverizing the sorted plastic into plastic chips of a size smaller than predetermined size, a fusing and mixing step for fusing the pulverized plastic in a double screw fusing device by applying heat to the plastic until the plastic reaches a predetermined temperature and mixing the plastic while it is being fixed, a middle layer sheet forming step for pulling a middle layer sheet having a predetermined width and thickness using a middle layer sheet supply device 72 and a pair of pulling rollers 72B, using the fused and mixed plastic, a pipe forming step for forming a pipe structure by extruding resin sheets for forming an internal layer 71 and an external layer 73 using an internal layer extruder and an external layer extruder, using the middle layer sheet for forming the middle layer 52, and continuously winding the resin sheets for the internal layer 51 and the external layer 53 around a winder 60 in a spiral manner, and a cooling and chopping step for cooling the pipe by spraying cooling water onto the surface of the pipe and chopping the pipe into pieces of desired length. Each step of the manufacturing method will be described below in detail .

In the sorting step, a plurality of kinds of waste plastic is collected, and non-plastic material, such as paper, metal, glass and cloth, is sorted out from the collected waste plastic, so that pure plastic is obtained. If metal is mixed with the waste plastic, the pipe having multiple layers cannot be manufactured, or is low in quality.

Before pulverizing the complex waste plastic, the ratio of different kinds of plastic must be adjusted. This is because the middle layer sheet must have predetermined tensile force and shear stress in order to form fused plastic into a plastic sheet or pipe when manufacturing the pipe using the middle layer sheet supply device 72. Accordingly, the blending ratio of raw material is important.

The optimum blending ratio of raw material in complex waste plastic is as follows:

50% or more of PE, 10% or less of PP, 10% or less of

PET, 10% or less of PS, 10% or less of PA, and 5% or less of other materials, such as PC, ABS, PMMA or PBT, but excluding

PVC, and 5% or less of stiffening agent for organic material (aluminum and soil) .

The blending ratio of raw material can be adjusted to within a predetermined range according to the conditions under which the present invention is practiced. That is, only one kind of plastic can be used, or alternatively, two or more kinds of plastic can be blended. However, the above blending ratio is preferable.

In the pulverizing step, a conventionally known pulverizing apparatus can be used. The collected and sorted waste plastic is pulverized to have a predetermined size and is then mixed to be uniform. The pulverized plastic can be fused with little heat, thus saving energy and preventing machinery from aging.

The fusing and mixing step includes a first fusing and mixing step, a second fusing and mixing step, and a third fusing and mixing step. In the first fusing and mixing step, the pulverized waste plastic is introduced into a double screw fusing device and is heated to a predetermined temperature, so that the waste plastic is fused. At this time, the pulverized plastic is fused while it is mixed until uniform. The double screw fusing device is a conventional apparatus having two screws arranged parallel to each other and rotating in opposite directions for forcibly mixing the pulverized plastic. The device preferably uses a speed variation method in order to adjust the discharge rate. A heat source for providing heat to the double screw fusing device can be a burner using gas, gasoline or electricity. The burner can use one of gas, gasoline or electricity depending on the circumstances . The temperature of the double screw fusing device may be in the range from 240^°C to 280^°C.

If the temperature is higher than 280^°C, PE, having a relatively low melting temperature compared to the rest of the raw material of the plastic, is burnt, or the physical properties thereof are changed. However, if the temperature is lower than 240^°C, PET, having a relatively high melting point out of the raw material of the plastic, is not fused well, so that the discharge rate is decreased due to pressure and it is possible to form the resin sheet or the pipe.

In the second and third fusing and mixing steps, fused material discharged after the first fusing and mixing step is fused further while it is mixed using a second and/or a third fusing device.

In the second and third fusing and mixing step, the material passing out of the first fusing and mixing step is minutely minced to have a dense structure, and various kinds of raw material having different physical properties are uniformly mixed. As a result, the physical properties of the material for forming the middle layer 52 are improved, that is, the middle layer 52 is hardened and strengthened.

In the second and third fusing and mixing steps, moisture and gas are exhausted in order to prevent air

(bubbles) from being generated in the raw material, so that the hardness and density of the material is improved, resulting in a pipe having high quality.

The heat source used in the second and third fusing and mixing step can be the same burner used in the first fusing and mixing step.

The temperature for fusing the second and third fusing and mixing steps is in the range from 180 to 220^°C, which is lower than the range for the first fusing and mixing step. In the second and third fusing and mixing steps, fusing is conducted by heating an outer vessel of the fusing device so that the temperature of the screw is maintained within a predetermined range.

The reason that the temperature for the second and third fusing and mixing steps is lower than the temperature for the first fusing and mixing step is that the material for the middle layer 52 is already fused in the first fusing and mixing step. The second and third fusing and mixing steps maintain the fused state of the material for the middle layer at a relatively low temperature and prevents the physical properties of the material from being degraded and the material from being hardened, resulting in a decreased discharging speed.

The second and third fusing and mixing steps can be omitted depending on the conditions under which the present invention is implemented. However, in order to improve the quality of the product, the second and third fusing and mixing steps are preferably conducted after the first fusing and mixing step. If needed, an additional fusing and mixing step other than the first to third fusing and mixing steps can be conducted.

In the middle layer sheet forming step, raw material is supplied to the middle layer sheet supply device 72, as shown in FIG. 7, which forms a sheet of resin having predetermined thickness, which forms the sheet 52P for the middle layer. The thickness and width of the sheet 52P for the middle layer 52 can be varied according to the diameter of the pipe, but the thickness may be in the range from 4 to 10 millimeters and the width may be in the range from 100 to 500 millimeters . The thickness and width of the sheet 52P is adjusted using the two pulling rollers 72B. Since the sheet 52P pulled by the pulling rollers 72B falls in a natural manner, the sheet 52P is continuously supplied unbroken, so that productivity is improved.

At this time, the temperature of the sheet 52P is slightly cooled, by 10 to 20%, using ambient air. Predetermined physical properties of the sheet 52P, such as tensile force and density, can be achieved when the temperature is maintained. However, since the sheet 52P is cooled somewhat and foreign matter and air (bubbles) are removed while complex waste plastic is sorted, pulverized, fused, and mixed, the problems in which the sheet 52P can be cut during the supply process and in which the shape of the pipe can vary while the sheet 52P is supplied using the middle layer sheet supply device 72 can be solved.

In the pipe forming step, as shown in FIG. 7 and FIG. 8, the sheets 51P, 52P and 53P, supplied from the middle layer sheet supply device 72 and the internal and external layer extruders 71 and 73, are continuously wound around the winder 60 in a spiral manner, so that a pipe having a cylindrical shape is formed. Material extruded by the internal and external layer extruders 71 and 73 may be PE, which is not recycled or waste material .

The pipe having multiple layers manufactured through the above-described manufacturing method can be the pipe described with reference to FIG. 3 through FIG. 5 or can be the pipe described with reference to FIG. 10, in which the internal layer sheet 52P, the internal layer sheet 51P and the external layer sheet 53P do not overlap each other. That is, while the pipe having multiple layers comprises the middle layer 52, the internal layer 51 and the external layer 53, the middle layer 52 can be formed by winding a sheet of waste plastic in a manner such that the turns of the sheet of waste plastic overlap each other three to six times, and the internal layer 51 and the external layer 53 can be formed by winding a PE sheet in a manner such that turns of the PE sheet overlap each other two times, or such that the turns of the PE sheet do not overlap each other. As a result, the pipe having multiple layers may have 4 to 8 layers in total.

As the width of the middle layer 52 increases, the number of turns of the sheet, which overlap each other, is increased too. That is, when manufacturing a relatively thick pipe, the number of turns of the middle layer sheet, which overlap each other, is increased by increasing the width of the sheet 52P. That is, a thick pipe can be easily manufactured. As described above, when winding the sheets for the internal layer 51, the middle layer 52 and the external layer 53 are wound to overlap each other, and the layers are perfectly bonded when the sheets for the layers are cooled to a predetermined degree.

For this, when winding the sheets 5IP, 52P and 53P, cooling water is directly sprayed onto the surface of the turns of the sheets 51P, 52P and 53P so that the sheets 51P, 52P and 53P are cooled down to 100 to 150^°C.

Before every turn of the sheets 51P, 52P and 53P, compressed air is sprayed in order to remove moisture remaining on the surface of turns of the sheets 51P, 52P and 53P. This is because the turns of the sheets 51P, 52P and 53P can be separated from each other due to moisture.

After the sheets 51P, 52P and 53P are all wound, pressure is applied to the structure in which the sheets 51P, 52P and 53P are wound using the pressure roller 65.

Accordingly, because the sheets 51P, 52P and 53P are cooled to a predetermined temperature, the shape of the pipe having multiple layers can be easily formed and the pipe has a good shape, and further, production time is greatly reduced. Further, thanks to the removal of moisture generated due to the cooling water, separation between adjacent layers is prevented. Further, thanks to a reciprocal reaction between the cooling, the moisture removal and remaining heat (100 to 120^°C) , the bond between layers is strengthened, the hardness of the pipe is improved, and a high quality pipe can be produced. In the cooling step, after the shape of the pipe is formed, by making cooling water flow inside the pipe or outside the pipe, the pipe is continuously cooled. By continuously cooling the pipe until the pipe has a predetermined length, productivity is increased, deformation and distortion of the shape of the pipe, which can occur during the manufacturing process, are prevented, and the inner and external surface of the pipe can be smoothed.

In the chopping step, the pipe is chopped into pieces having desired lengths.

[industrial Applicability]

According to the present invention, the apparatus and method for manufacturing the pipe having multiple layers can improve the internal and external pressure strength and ability to withstand thermal shocks of the pipe, thereby being capable of producing a pipe having good durability and reliability.

Since the pipe is manufactured in a manner such that the internal layer sheet and the external layer sheet are supplied in an extruding manner, and the middle layer sheet is supplied in a pulling manner using rollers, the middle layer sheet, made of waste plastic (recycled material) , can be smoothly supplied, rather than being cut in the middle portion thereof. Accordingly, a pipe having multiple layers is manufactured. Further, since the two rollers are used when supplying the middle layer sheet, the thickness and the fused state of the middle layer sheet can be adjusted, and thus the pipe having multiple layers can be effectively produced.

Further, according to the present invention, since the cooling water is sprayed on the sheet while the pipe is manufactured, and moisture generated due to the cooling water is removed by spraying compressed air before a new layer sheet is stacked, the bonding force between stacked layers is increased and the hardness and density of the pipe are increased, resulting in improved pipe quality.

Claims

[CLAIMS]

[Claim l]

An apparatus for manufacturing a pipe having multiple layers, comprising: a winder having a cylindrical shape and a driving means for rotating the winder; an internal and an external layer extruder for extruding resin into resin sheets to form an internal layer and an external layer, respectively; a middle layer sheet supply device for pulling out a middle layer sheet using a pair of rollers from fused material ; and a pressure roller for pressing a resultant structure, in which the sheets are wound around the winder.

[Claim 2]

The apparatus according to claim 1, further comprising: a cooling water sprayer installed near the winder for spraying cooling water when the resin sheets are wound around the winder.

[Claim 3]

The apparatus according to claim 2, further comprising: a moisture remover installed behind the cooling water sprayer in a rotational direction of the winder for removing moisture remaining on a surface of the resin sheet which is wound.

[Claim 4]

The apparatus according to claim 3 , wherein the moisture remover has a structure which can spray compressed air.

[Claim 5]

The apparatus according to claim 4, wherein the cooling water sprayer is installed under the winder so as to spray cooling water to the resin sheet which is wound, and the moisture remover is installed above the winder so as to spray compressed air to the resin sheet wound around the winder.

[Claim 6]

The apparatus according to claim 5, wherein the moisture remover has a structure which can spray compressed air onto the surface of the resin sheet which is wound in a slanted direction relative to the surface of the resin sheet.

[Claim 7]

The apparatus according to claim 1, wherein the middle layer sheet supply device includes a tank in which fused resin for forming the middle layer sheet is stored, a pair of pulling rollers installed under the tank for pulling the fused resin by being rotated by the driving means, and a distance adjustment device for adjusting a distance between the pair of pulling rollers .

[Claim 8]

The apparatus according to claim 7, wherein each of the pulling rollers is configured in a manner such that cooling water can pass therethrough in order to cool the fused material .

[Claim 9] A method for manufacturing a pipe having multiple

1ayers , comprising: a sorting step for collecting waste plastic and sorting out paper, metal, glass, and cloth from the collected waste plastic to obtain only plastic; a pulverizing step for pulverizing the plastic into plastic chips of a predetermined size or smaller; a fusing and mixing step for fusing the plastic chips by introducing the pulverized plastic chips into a double screw fusing device and applying heat to the plastic chips to reach a predetermined temperature, and mixing the plastic chips while fusing the plastic chips; a middle layer sheet forming step for pulling a middle layer sheet having a predetermined thickness and width using a pair of pulling rollers, which is a middle layer sheet supply device; a pipe forming step for extruding resin sheets for forming an internal layer and an external layer using an internal layer extruder and an external layer extruder, and continuously winding the middle layer sheet for forming the middle layer and the resin sheets for the internal layer and the external layer around a winder in a spiral manner in order to form a shape of a pipe; and a cooling step for cooling the pipe by spraying cooling water onto the wound resin sheets and chopping the pipe into pieces having predetermined lengths.

[Claim lθ] The method according to claim 9, wherein the fusing and mixing step includes a first fusing and mixing step, a second fusing and mixing step and a third fusing and mixing step, and wherein a heating temperature of the first fusing and mixing step is in a range from 240 to 280^°C, and a heating temperature of the second and third fusing and mixing steps is in a range from 180 to 220^°C, which is lower than a range for the first fusing and mixing step.

[Claim 11] The method according to claim 9, wherein a supply of the middle layer sheet in the middle layer sheet forming step is conducted through a gravity feeding method, in which the middle layer sheet, pulled out by the two pulling rollers falls naturally.

[Claim 12]

The method according to claim 9, wherein, in the pipe forming step, when the sheets are wound, cooling water is directly sprayed onto surfaces of the resin sheets for every layer so that the resin sheet is rapidly cooled.

[Claim 13]

The method according to claim 12, wherein a temperature of the resin sheets which are rapidly cooled is in a range from 100 to 150^°C.

[Claim 14]

The method according to claim 13, wherein, if the resin sheets are cooled by the cooling water sprayed onto the surface thereof, moisture remaining on the resin sheets is removed by compressed water sprayed onto the surface thereof right before a new layer is wound.

[Claim 15]

A method for manufacturing a pipe having multiple layers, in which the pipe is manufactured in a manner such that a middle layer sheet for forming a middle layer of the pipe and resin sheets for forming an internal layer and an external layer are supplied to a winder so that the sheets are continuously wound around the winder in a spiral manner, wherein cooling water is directly sprayed onto all outer surfaces of the resin sheets when the resin sheets are wound, and moisture remaining on the surfaces of the resin sheets is removed by compressed air which is sprayed on the surfaces of the resin sheet before a new layer is wound.