US2903943A - Device for developing cutter profiles - Google Patents

Description

Sept. 15, 1959 G. J. J. TURNER 2,903,943

- DEVICE FOR DEVELOPING CUTTER PROFILES Filed Dec. 19, 1956 2 sheets-sneet'l //VV/V T06 k 61 0 6 41 JJ, nae Y8K l 15, 1959 G. J. J. TURNER 2,903,943

DEVICE FOR DEVELOPING CUTTER PROFILES Filed Dec. 19, 1956 2 Sheets-Sheet 2 INVENTaR Geo/e as J. J. TUE/Y6K United States Patent Q DEVICE FOR DEVELOPING CUTTER PROFILES George James John Turner, London, England Application December 19, 1956, Serial No. 629,291

Claims priority, application Great Britain December 21, 1955 3 Claims. (Cl. 8824) This invention relates to a device for developing cutter profiles, particularly, although not exclusively, for woodworking machinery.

In wood-wo-rking machine practice, apart from the socalled French Head, all cutters and cutter blocks employ a positive cutting angle which varies with the design of the block and with the projection of the cutter therefrom. In consequence, progressive distortion of cutter profile results, in order to produce a required shape or moulding. If accuracy is required, geometrical development or prepared projection scales are used, requiring much time and considerable skill if accuracy is to be obtained.

The object of the present invention is to provide for economy in time while obtaining considerable accuracy in cutter profile development without the need of the skill required in geometrical and projection scale methods.

According to the invention there is provided a device for developing cutter profiles comprising a recording member and means for optically projecting the shape of a cutter profile on to the recording member by relative movement of the recording member through the pro jection. The recording member may automatically take the cutter shape as it is applied thereto, or an operator or marker may draw the cutter outline as it is. received by said member.

According to a feature of the invention, there is provided a device for developing cutter profiles comprising a recording member, an optical projection system for projecting a required shape and means for causing relative movement between the recording member and the projected shape in correspondence with the movement of a cutter for that shape when in use, whereby there is projected on to the recording member the cutter profile corresponding to the required shape.

In carrying out the invention to one form given by way of example, the optical system is fixed, and the simulator with a recording template is rotationally adjustable about an axis at right angles to and offset from the projection axis, so that the template can be turned through a focussing plane containing said rotational axis, thereby progressively bringing the outline of the projected shape into sharp definition on the template. The template may carry a photographic strip or plate for automatic recording, or may carry a recording card or paper on which the shape can be drawn as the outline is defined thereon. Adjustment of the simulator to and from the projection axis may provide for positioning the cutter shape relatively to the simulator. Alternatively, for the same purpose, provision may be made for adjusting the shape to be projected, relatively to the optical axis.

The optical system may comprise a co-axially aligned light source, (with or without) condenser lens, a frame for holding a transparency of the cutter shape and an object lens, the whole conveniently being mounted in a horizontal or vertical stand so that the projection axis is either horizontal or vertically downwards. As applied 2,903,943 Patented Sept. 15, 9

ice

to cutter blocks for wood-working machines, the simulator comprises a representative cutter block having projecting therefrom oifset from the axis a recording template so that the combination simulates an actual cutter block with cutter.

In order that the invention may be readily understood, reference will now be made to the accompanying drawings, in which:

Figure 1 is a pictorial diagrammatic view of a horizontal unit according to the invention.

Figure 2. is a pictorial view showing an actual cutter and cutter block assembly, with the cutter being set against a developed profile obtained from the unit.

Figure 3 is a pictorial view of part of the projector casing and shows particularly the mounting provided for adjusting the profile transparency (i.e., the shape to be projected and for which the cutter profile is required) relatively to the projection axis to obtain the required cutter projection.

Figure 4 shows in diagrammatic elevation a vertical unit according to the invention, and

Figure 5 shows in diagrammatic pictorial view a cutter simulator with a masking arrangement for photographically recording the projected profile as the simulator is turned through the focal plane.

The unit shown in Figure 1 comprises a base plate 1 (for convenience it is used horizontally and thus the unit is referred to as a horizontal unit) having at one end the cutter simulator mounting, and at the opposite end the optical projection system,'either or both of which may be slidably mounted on the base plate by means of slides and rails for relative movement towards and away from each other along the optical axis (xx) which is parallel to the base plate.

The simulator mounting consists of a pair of support blocks 2 spaced one on each side of the optical axis with base flanges 3 which in this instance are secured to the base plate by means of screws 4, but they may be slidable in guide rails on the base plate as indicated by the dotted lines 5.

At the top of the support blocks, open, e.-g., V-bearing grooves 6 are provided for exchangeably supporting the pivot pin 7 of a cutter simulator block 8. The shape of the simulator block depends on the shape and character of the actual cutter to be simulated. That shown is of rectangular shape, but it may be circular, hexagonal or conical. The pivot pin 7 of the simulator corresponds to the centre hole 9 of the actual cutter 10 (a standard moulding machine block is shown in Figure 2)but a hole with a through axle may be employed instead-and each cutter is provided with a plurality of dovetail grooves 11 by which a cutter 12 can be mounted by a clamping nut 13 so that it projects from the side of the cutter at a position offset from the rotational axis, as will be clear from Figure 2.

It will be evident that, due to the offset of the cutter blade, its shape requires to be a development of the actual shape to be cut thereby.

To obtain this shape, the device now being described is employed, the motion of the simulator being arranged to correspond with the cutter in use, with an image of the shape to be cut projected on to a recording member which is the equivalent of the cutter and which cuts progressively through a focal plane of projection as the simulator is rotated.

The recording member on the simulator consists of a template 14 which projects ofiset from the pivot axis from one side of the simulator block 8, the template providing a support fora paper or other record strip 15, which may, for example, be held in position on the plate by side flanges 16. l

The focal plane (yy) of projection is conveniently arranged to be a vertical plane containing, or in line with, the pivot axis 7 of the simulator, and the record template is of such length that it can pass through the focal plane and optical axis (x-x) throughout an angular displacement of the simulator which will cover the required cutter development.

The optical system is designed to project an inverse image of the required shape for which a cutter profile is to be developed on to the focal plane y-y, and, as the simulator block is rotated away from the optical projector, a sharp focussed outline is impressed on the template. For this purpose, the optical projector system consists of an elongated rectangular optically closed box 17 which is carried upon flanged feet 18, the flanges 19 of which may be screwed down on to the base plate 1 or may be slidably adjustable in the guides 5.

At the outer end of the box 17 there is a lamp housing 20 having a holder 21 for an electric lamp 22. At the inner end of the box there is a projecting lens system 23 comprising an object lens of any suitable shape and power for projecting an inverse image of a shape which is held in a position between the lamp and the lens. The shape to be projected takes the form of a transparency 24 on which the shape 25 is shown and which is conveniently carried by a glass mounting 26 consisting of two sheets of glass between which the transparency is a friction fit so that it can be set into any position relative to the projection axis xx when the mounting 26 has been inserted in position between the lamp 22 and the object lens 23. Thus the required amount of projection of the cutter profile on the recording template may be obtained. For the purpose of adjustment of the transparency it is provided with projecting ears 29a.

Figure 3 shows the general arrangement and construction, but it will be noted that the projection setting for the cutter is made first before the actual profile is drawn on to the template.

It will be observed that the lamp housing has an outlet 27 at the top for hot air circulation. The side walls of the optical box 17 have slots 28 through which the transparency mounting 26 can be positioned, either fixed or removable as may be desired.

The method of use of the device will be apparent from the foregoing. Firstly, a representative cutter block simulating that on which the eventual cutter is to be secured is selected and placed on the simulator mounting blocks 2 so that it can rotate in like manner to the actual cutter when in use on the machine. The transparency 24 with the shape 25 for which a cutter profile is to be developed therein is placed between the glass mounting 26 and positioned to give the required cutter projection on the record template 14. This positoning is effected by switching on the lamp 22 so that the image of the shape is projected by the object lens on to the recording template, and the amount the image projects from the simulator block can be studied by the operator and adjustment made of the transparency in the mounting 26 until the required projection setting is obtained.

As has been indicated, the image of the shape 25 is focussed in a plane yy containing the simulator axis; to see the image at any time the simulator block 8 has to be rotated so that the template cuts through the focus plane. After projection setting has been done, the simulator block is rotated again, and as the various parts of the optically projected image of the shape 25 come sharply into focus, the outline, consisting of a clearly defined shadow line, is seen and can be sketched in by the opera tor on to the recording sheet 15 until the complete cutter profile 29 developed from the shape 25 is obtained.

The developed cutter profile 29 can be matched to existing cutters 12 as indicated in Figure 2, or placed upon a tool steel body for grinding the same to the shape of the cutter. The cutter so made is then applied to the basic cutter block of the s mulator (see Figure 2 working a section of the shape.

In Figure 4 the device is shown as a vertical unit; the various parts and arrangements are generally the same as in the previously described horizontal unit so that corresponding reference numerals are applicable, but in this case the optical axis X1X1 is vertical and the focus plane Yl-Yl is horizontal. The optical system includes a condenser lens 30 and the simulator support blocks are mounted upon a carriage 31 which runs on a base 1 so that the recording template can be traversed horizontally across the optical axis, and if necessary at right angles thereto, to provide for relative positioning of the template 14 to the projection axis, whereby the amount of projection of the cutter from the block can be determined. This adjustable carriage arrangement may be an alternative or an additional provision to the adjustment of the transparency provided by the glass mounting 26 as in Figures 1 and 3.

The embodiments described herein will be generally associated with a set of representative cutter blocks, each with projecting templates for registering the shape of the cutter projected by the optical system. The representative blocks may be made of wood, plastic, metal or any suitable material, and may be of square, triangular, circular or other shape employing positive cutting angles, including cutter blocks in which the cutter seating is machined at an angle to the axis of rotation, e.g., shear blocks as used on a tenoning machine or blocks for automatic latches.

Instead of a plurality of representative blocks, a compound block capable of adjustment to different shape and to take different form of cutters or templates may be employed as the simulator.

It will be understood that the optical system may have the necessary or desirable refinements of shrouding or screening, with appropriate access to enable the template to be worked upon by the operator as the projected cutter shape is focussed thereon by movement of the simulator.

Figure 5 is a typical example of such screening. In this example the screen consists of a plate 32 which is mounted between guide flanges 33 on the template 34 of the cutter simulator block 35. In the plate there is a narrow slot 36 extending transversely so that it reveals only a portion of the recording strip at a time. This slot is maintained in the focus plane automatically, e.g. by a crank pin and slot drive from the simulator pivots 7 or by the operator as the simultator block is turned so that the sharply focussed outline of the cutter profile is contained within the slot and can be readily marked on the record strip. If the record strip is photographically sensitised the marking is automatic, only those parts of the projected image in actual focus at any moment being exposed. In this case the underside of the mask plate is optically black and the top side is optically white.

I claim:

1. A device for developing a cutter profile corresponding to a particular shape, comprising a support for a cutter simulator having a recording template projecting therefrom offset from a rotational pivot in correspondence with an actual cutter, bearing means on said support for exchangeably mounting the simultator pivot therein, an optical projector having means for mounting therein a transparency of the said shape and focussing an image of said shape along an optical axis, and means mounting the simulator support with the template cutting the optical axis and so that the projected image falls in a focal plane which is behind the template and contains the simulator pivot axis.

2. A device according to claim 1, wherein the transparency mounting means comprise optically transparent sheets in face to tace juxtaposition with a space between which permits of insertion of the transparency with a friction fit, and a support holding the sheets in an optical casing of the projector at right angles to and cutting through the optical axis whereby the transparency can be adjusted relatively to the axis to determined cutter projections.

3. A device according to claim 1, comprising a traversab le carriage on which the simulator support is mounted,

and means supporting the carriage to traverse relative to the optical axis for adjusting the position of the template relative thereto.

References Cited in the file of this patent UNITED STATES PATENTS

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