Methods of manufacturing a workpiece fixture for supporting a workpiece in a precision manufacturing process; method of generating a support blade machining pattern; and target material fixture

Abstract

Disclosed are methods of manufacturing a workpiece fixture (10) and also a target material fixture (10), for use in precision manufacturing processes. A sheet material is supported on a generic material fixture (10) and the sheet material precision processed to form support blades (16, 18) for a target workpiece fixture (10). Each support blade (16, 18) has a support locus and interstices are positioned in the support loci where a target pattern and the support loci coincide. Thus, there are no unnecessary clearances between the workpiece support (10) and the workpiece. The interstices that are present are located only where necessary to reduce or eliminate any interference between the precision manufacturing process and the fixture (10), when it is used in a precision process involving the target pattern.

Claims

1. A method of manufacturing a workpiece fixture, for supporting a workpiece in a precision manufacturing process; the method comprising: providing a generic material fixture and a sheet material supported on the generic material fixture; precision processing the sheet material to form support blades for a target workpiece fixture, each support blade having a support locus, the support locus of at least one said support blade having at least one interstice, wherein each interstice is a gap or break in a continuous support locus, wherein a majority of a length of each support locus is defined by an edge of the support blade, and a minority of the length by each interstice; and constructing a target workpiece fixture comprising the support blades, wherein the support loci together define a workpiece support and wherein the at least one interstice is positioned based on where a target pattern and the support loci coincide.

2. The method of claim 1, wherein each support locus is linear, and wherein the loci are co-planar, together defining a workpiece support for a planar workpiece.

3. The method of claim 1, wherein one or more or each said interstice is a slot or an indent in a said support locus.

4. The method of claim 1 wherein, wherein the target pattern is a 2—or 3-dimensional model reflecting a shape and configuration of a portion of the workpiece to be supported.

5. The method of claim 1, wherein the target pattern includes a machining, cutting or etching pattern to be applied to the workpiece.

6. The method of claim 1, wherein the precision processing of the sheet material comprises laser machining the sheet material, or wherein the precision processing comprises chemical etching, photochemical machining, electrical discharge machining, water jetting or precision mechanical CNC machining the sheet material.

7. The method of claim 1, comprising forming the target workpiece fixture by interlocking the support blades, by way of slots or other interlocking formations, to form the target workpiece fixture.

8. The method of claim 1, wherein precision processing the sheet material to form the support blades comprises following a support blade machining pattern and wherein the support blade machining pattern is generated based on the target pattern.

9. The method of claim 1, comprising determining the coincidence between the target pattern and a model of the support loci of the target workpiece support; and determining the location of the at least one required interstice therefrom.

10. The method of claim 9, wherein said interstice is required where the target pattern and the model of the support loci coincide; and/or wherein a said interstice is required where the target pattern and the model of the support loci do not coincide.

11. The method of claim 9, comprising aligning all or a selection of a template workpiece support model and all or a corresponding selection of the target pattern, and determining the coincidence therebetween.

12. The method of claim 9, comprising: generating a first cross section of the template workpiece support model corresponding to the position of a first support blade, and a corresponding first cross section of the target pattern; aligning the cross sections; and determining the location of any required interstice(s) based on where the cross sections coincide.

13. The method of claim 12, comprising generating a cross section of the template workpiece support model in a one or more XZ— and/or YZ-planes corresponding to the position of one or more support blades, and a generating corresponding cross section of the target pattern in the one or more XZ— and/or YZ-planes; aligning the cross sections; and determining the location of any required interstice(s) based on where the cross sections coincide.

14. The method of claim 9, wherein the target pattern is 2-dimensional, the method comprising selecting a first line across the template workpiece support model and plotting a corresponding first line across the target pattern and aligning the lines to determine the required location of any interstice or interstices.

15. A method of precision processing a sheet material, the method comprising: generating a support blade machining pattern, the generating a support blade machining pattern comprising: for use in precision processing a sheet material to form support blades of a target workpiece fixture; the method comprising: providing a target pattern; providing a model of support loci of a target workpiece support; determining coincidence between the target pattern and a model of the support loci of the target workpiece support; and determining a location at least one interstice based on the coincidence; and generating the support blade machining pattern, comprising an outline of each support blade for the target workpiece fixture, wherein at least one said outline comprises at least one interstice, wherein each interstice is a gap or break in a continuous support locus, wherein a majority of a length of each support locus is defined by an edge of the support blade, and a minority of the length by each interstice; and precision processing the sheet material by following the support blade machining pattern and machining at least a part of the outline of each support blade through the sheet material.

16. The method of claim 1, comprising providing the target pattern by laser scanning a surface of a workpiece to be supported by the target workpiece fixture.

17. The A method of claim 1 comprising: supporting a workpiece on the target workpiece fixture; and performing said precision manufacturing process on the workpiece, to form one or more parts from the workpiece.

18. The method of claim 17, comprising precision manufacturing more than one part from the workpiece, and/or precision manufacturing one or more parts from each of two or more workpieces in turn.

19. A target material fixture adapted for supporting a workpiece during a precision manufacturing process, the target material fixture comprising two or more support blades coupled together; each support blade having a support locus and the support locus of at least one said support blade having at least one interstice; wherein each interstice is a gap or break in a continuous support locus, wherein a majority of a length of each support locus is defined by an edge of the support blade, and a minority of the length by each interstice; wherein the support loci together define a workpiece support for supporting the workpiece in use; and wherein the at least one interstice is positioned to provide a clearance between the workpiece support and the workpiece in predetermined locations based on the precision manufacturing process.

20. The method of claim 15, comprising providing the target pattern by laser scanning a surface of a workpiece to be supported by the target workpiece fixture.

Description

DESCRIPTION OF THE DRAWINGS

(1) Example embodiments will now be described with reference to the following Figures in which:

(2) FIG. 1 is a perspective view of a generic material fixture in the well of a laser machining apparatus.

(3) FIG. 2 is a close-up photograph of the generic material fixture

(4) FIGS. 3(a) and 3(b) show a schematic cross-sectional side view of the apparatus of FIG. 1, during a laser machining process.

(5) FIGS. 4(a) and 4(b) show a schematic cross-sectional side view of a target material fixture within the well of the laser machining apparatus, during a laser machining process.

(6) FIGS. 5(a)-(e) are schematic illustrations of the steps of generating a support blade machining pattern.

(7) FIGS. 6(a)-(e) are schematic illustrations of an alternative embodiment of generating a support blade machining pattern.

(8) FIG. 7 shows a perspective view of a support blade machining pattern for a target material fixture being laser machined into a sheet material.

(9) FIG. 8 is a perspective view of a workpiece on a target material fixture.

(10) FIG. 9 is an example processor for generating a support blade machining pattern, from a template workpiece support model and a target pattern.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(11) FIG. 1 shows a generic material fixture 10 positioned in the well 12 of a laser machining apparatus 14. The laser machining head has been omitted for clarity. Also visible in FIG. 1 is a vent 13 from the well 12. In used, a reduced pressure can be applied to the vent to draw away fumes and dust generated during machining.

(12) The fixture 10 includes an array of longitudinal blades 16 and an array of transverse blades 18, coupled together by interlocking slots (not shown). In the example shown, the longitudinal blades 16 have slots extending to a lower edge and the transverse blades 18 have slots positioned to cooperatively engage therewith, extending to an upper edge. The generic material fixture 10 can thus be lifted by the transverse blades 18; and peripheral transverse blades 18a, 18b are provided with eyelets 19 for this purpose.

(13) As can be seen in the photographic close up view of the fixture 10, in FIG. 2, the upper parts of the blades 16, 18 are provided with triangular crenellations 20; the tip 22 of which are coplanar. Accordingly, the crenellations of each blade define a linear (in the example shown) support locus 21. The support loci of each of the blades 16, 18 define a workpiece support.

(14) FIGS. 3(a) and 3(b) show a schematic cross-sectional side view of the apparatus of FIG. 1, during a laser machining process. The laser machining head 26 directs a focused laser beam at a workpiece 28 (in the example shown a sheet material) which is supported by the fixture 10 across the well 12.

(15) Between the tips 22 of the crenellations 20 are a regular array of interstices 23 (V-shaped in this instance), which provide a regular array of clearances between the tips 22 running along the support locus 21, upon which the underside 30 of the workpiece 28 is supported.

(16) The laser beam vaporizes material from the workpiece according to a predetermined machining pattern. Since the position of the crenellations 20 and interstices 30 are unrelated to any particular machining pattern, normally in at least some regions the tips 22, such as the tip 22a shown in the figure, are underneath or close to where the machining pattern crosses a blade.

(17) Where the material forming a blade is close to a machining pattern, the laser beam may vaporize both the workpiece 28 and some of the material fixture 10, as illustrated in FIG. 3(b). Such collateral machining can cause vibration or movement of the workpiece (due to ejected plumes of material) and in addition limit the working lifetime of the material fixture 10.

(18) The blades 16, 18 of a generic material fixture 10 of this type are therefore provided with a large number of interstices that are not required and, in addition, lack interstices to provide clearance in some regions where clearance is required.

(19) Whilst illustrated for laser machining, similar issues may be associated with other forms of precision machining.

(20) The present invention provides a method for manufacturing a target workpiece fixture in which interstices are located where the support loci coincide, so as to reduce or eliminate such collateral machining.

(21) This is illustrated in FIGS. 4(a) and (b), which shows a corresponding blade 102 of a target workpiece fixture 100. In contrast to the fixture 10, an upper edge 104 of the blade 102 runs along the support locus 119.

(22) An interstice 106 (a slot or cut out from the upper edge 104 of the blade 102) is provided where the workpiece 28 above is to be machined. The interstice provides clearance underneath the workpiece, where the machining pattern and the blade 102 coincide (in this case in the vertical, Z-axis). Thus, the blade provides support along a far great portion of the support locus than the blades 16, 18 of the generic fixture 10, whilst at the same time providing a degree of both lateral 110a (i.e. in an x— or y— axis) and vertical 110b clearance between the blade 102 and the region 112 where the machining pattern coincides with the support locus 119.

(23) The method includes providing a generic material fixture 10 as described above. A sheet material for forming blades of a target workpiece fixture 100 is supported on the generic material fixture 10.

(24) The outline of support blades of a target workpiece fixture 100 are then machined from the workpiece, sheet material 50 (see FIG. 7).

(25) A support blade machining pattern, to be machined into the sheet material is generated based on the coincidences between a target machining pattern and a model of the support loci of the workpiece support.

(26) With reference to FIG. 5(a), in one example, the model of the support loci comprises a 2D grid pattern 115, where grid lines in the X-axis represent the positions of the support loci 119x of longitudinal blades and support loci 119y of transverse blades. Optionally, the grid pattern may be generated from a 3D model of a template fixture, by plotting lines at a Z-axis value corresponding to the workpiece support along each X- and Y-value corresponding to the position of a corresponding blade.

(27) To determine the required locations of interstices, a target pattern 200 (in this case a laser cutting pattern) and the grid pattern 115 are aligned (FIG. 5(b)). The intersections 120 between the grid 115 and the target pattern 200 (i.e. where the two coincide) represent the required positions of the interstices 106. An example is illustrated in the exploded view, A.

(28) In the example shown, the interstices can be a standardized size to provide the required clearance. The profile of the upper edges of each blade can be derived by the provision of an outline of an interstice into the template upper blade edge.

(29) In alternative examples, the workpiece support model can also represent the thickness of the sheet material, wherein the dimension of an interstices is determined by the difference between the maximum and minimum X- or Y-values (as the case may be) that the aligned model and pattern coincide.

(30) An outline of each blade of the target material fixture can then be generated from the upper edge profile of each blade, applied to a generic outline of the remainder of the blade. An example of the profile 133 of the upper edges of a longitudinal blade 118c is shown in FIG. 5(c), with the positions 106a of interstices 106 positioned the locus 119x as determined by aligning the patterns as described above.

(31) In a next step (FIG. 5(d)) this is combined with a generic outline 134 of a blade, to create a blade outline pattern 136.

(32) As illustrated in FIG. 5(e), this process is repeated for each blade 116, 118 and each outline 136 is then arrayed to form a support blade machining pattern 140.

(33) Optionally, the support blade machining pattern may be indexed, to assist in constructing the target material fixture with the blades in the correct order. This can be achieved by machining indicia into the sheet material 50 and/or by ordering and positioning of the outlines on the support blade machining pattern and/or in some embodiment the configuration (e.g. depth) of the respective slots 134 by which the blades are coupled.

(34) The support blade machining pattern 140 is then cut into a sheet of material 50, which is supported in a well 12 by a generic material fixture 10, as shown in FIG. 7. The support blades 116, 118 are then pressed from the sheet and assembled into a target material fixture (these conventional assembly steps are not illustrated). The target material fixture may then be used to manufacture parts by following the target pattern 200.

(35) Any collateral machining of the generic fixture 10 while following the support blade machining pattern 140 does not reduce the precision of the subsequent part manufacture using the target material fixture, since any variability in the position/dimensions of the interstices 106 is less (typically at least an order of magnitude) than the clearance between the workpiece and the target material fixture, where the target pattern 200 and support loci 119 coincide.

(36) Whilst the foregoing steps of generating a support blade machining pattern may be conducted by hand, conveniently these steps are conducted in silico. A non-limiting example of suitable software or processing architecture for carrying out these steps is shown in FIG. 9.

(37) With reference to FIG. 6(a), in one example, a 3D template workpiece support model 615 is provided. In this instance, the model 615 is of an entire template fixture. The model includes a representation of an array of blades 616 extending in the X-direction, and of blades 618 extending in the Y-direction. The support loci 619 of the blades 616, 618 together define a template workpiece support.

(38) A selection of the model 615 is taken in an XZ-plane corresponding to the position of each of the blades 316. Thus, each cross section represents a generic blade outline. An example of an XZ-cross section 617 is shown. Selections are also taken through each of the YZ-planes corresponding to the positions of the blades 618 (not shown).

(39) FIG. 6(b) shows a target pattern 700. In this example, the target pattern represents a circuit board substrate 701, to which components 702, 704 have already been attached and extend from a lower face thereof. The circuit board is the workpiece to be supported by the target workpiece fixture, without impinging upon the components 702, 704.

(40) A selection of the target pattern 700 is taken in each XZ-plane and YZ-plane corresponding to the positions the blades 616, 618. An example of a cross section 717 corresponding to the cross section 617 is shown in FIG. 6(b).

(41) To determine the required locations of interstices, the corresponding cross sections are aligned. FIG. 6(c) shows the aligned cross sections 617 and 717 of the template model 615 and the target pattern 700. The position of the required interstice can then be determined based on the coincidence between these two selections.

(42) When aligned the position of the support locus 619 and the position in the target pattern corresponding to the underside of the circuit board coincide along regions 801, 803. There is a deviation therebetween in region 805.

(43) In this example, an interstice is required were the selections do not coincide, i.e. in the deviation region 805.

(44) FIG. 6(d) shows the interstice 706 being configured by providing a clearance in the X-direction to either side of the component 702 and a larger clearance in the Z-direction below the component 702, and a blade outline pattern 736 is generated which comprises the required interstice 706.

(45) As illustrated in FIG. 6(e), this process is repeated for each blade 616, 618 and each outline 736 is then arrayed to form a support blade machining pattern 740.

(46) The support blade machining pattern 740 is then cut into a sheet of material 50, which is supported in a well 12 by a generic material fixture 10, as illustrated in FIG. 7. The support blades are then pressed from the sheet and assembled into a target material fixture 900 (these conventional assembly steps of slotting the blades together are not illustrated). The target material fixture 900 can then be used to support a workpiece 701 as shown in FIG. 8, in a precision manufacturing process, such as further circuit board assembly.

(47) A processing resource 300 for generating a support blade machining pattern such as patterns 140 and 740, is shown in FIG. 9. The processing resource includes a data store 302, for example a hard drive or cloud storage arrangement, on which the target pattern 200, 700 and the model of the support loci of the target workpiece support. In some cases, a 3D model of the entire template material fixture is stored by the data store.

(48) A comparator module 304 is provided to determine the coincidence(s) between the target pattern 200, 700 and the stored model 115, 615. A selector module 303 (separate from or forming part of the comparator module 304) may also be provided to select individual loci 119x,y from the model (or, in some embodiments, XZ— or YZ—slices 616, 618 therethrough, corresponding to the positions of the support blades, as described above in relation to FIG. 6), and provide these to the comparator module.

(49) The comparator module 304 aligns the model and the pattern, or alternatively aligns the selections provided by the selector module with the corresponding selections of the target pattern 200, 700, to determine the positions of the interstices 106, 706 in relation to the support loci 119, 719, and generate upper edge profiles of the support blades 116, 118 or outlines 136, 736, as described above. In some embodiments, the upper edge profiles are generated by a machine pattern generating module 306.

(50) The machining pattern generating module 306 (which may form part of the comparator module) takes the upper edge profiles 133 and combines these with generic outlines 134 (which may also be stored on the data store 302, or which may be obtained from the selector module 303) to generate blade outline patterns 136 and array these to generate a support blade machining pattern 140. Alternatively, the machining pattern generating module 306 arrays the patterns 136, 736 generated by the comparator module to form the support blade machining pattern.

(51) The pattern 140, 740 may be stored on the data store 302 and/or output to a further computing device 400 (e.g. running on a precision machining apparatus), or storage medium 500.

(52) Whilst exemplary embodiments have been described herein, these should not be construed as limiting to the modifications and variations possible within the scope of the invention as disclosed herein and recited in the appended claims.