Method for producing a connection bridge with reduced thickness when cutting a workpiece part from a plate-

Abstract

The invention relates to a method for producing at least one connection bridge (21) with a reduced thickness when cutting a workpiece part (19) from a plate-shaped workpiece (16), the cut workpiece part (19) being held attached to a remaining grid (26) of the workpiece (16) by means of the connection bridge (21), according to the invention, the method comprises the following method steps: producing the at least one connecting bridge (21) in the workpiece (16) prior to the cutting of the workpiece part (19); pressing the connecting bridge (21) in the thickness direction (24) of the workpiece (16) at least on a bridge section (23) adjoining the workpiece part (19) to be cut, in order to retract the pressed connecting bridge (21 ') in the direction of the center of the workpiece relative to at least one of the two plate flanks (16a, 16b) of the workpiece (16), the edges (25a, 25b) of the workpiece (16) formed by the retraction of the indented connecting bridge (21 ') form the edges of the workpiece part (19) that is still to be cut; and-cutting in the workpiece (16) a dividing slit (22) corresponding to the contour of the workpiece part (19), which dividing slit is interrupted along the edges (25a, 25b) formed by the retraction of the indented connecting bridge (21 '), whereby the workpiece part (19) remains attached to the remaining grid (26) of the workpiece (16) by means of the indented connecting bridge (21').

Description

Technical Field

[0001] The present invention relates to a method for generating at least one connecting bridge with a reduced thickness when cutting workpiece parts from a plate-shaped workpiece, and a controller program product including code instructions, the code instructions being adapted to perform the method according to the present invention when the program runs on a controller of a suitable machine tool. Background Art

[0002] Such a method is known, for example, from EP 3 088 096 A1.

[0003] During stamping or stamping-laser processing, connecting bridges (Verbindungsstege), so-called "micro joints (Microjoint, joints of the same thickness as the plate thickness)", are left to fix the cut workpiece parts, and the workpiece parts are still attached to the remaining grid through the connecting bridges. The micro joints make it very difficult to remove the workpiece parts from the remaining grid by hand, especially when the metal plate thickness is greater than 2 mm. In addition, the edges of the workpiece parts cannot be rounded or chamfered at the positions of the micro joints because the micro joints extend over the entire workpiece thickness.

[0004] In the method known from EP 3 088 096 A1, the workpiece parts are cut from the plate-shaped workpiece while leaving the connecting bridges. Then, a forming tool is used to perform pressure forming on the connecting bridges to reduce the thickness of the connecting bridges.

[0005] It is also known from WO 2022 / 037797 A1 that during laser cutting of workpiece parts from a plate-shaped workpiece, one or more connecting bridges are left between the workpiece parts and the remaining grid, and the cutting edges of the workpiece parts still connected to the remaining grid are processed with a laser beam, especially rounded. Summary of the Invention

[0006] In contrast, the object of the present invention is to provide an alternative method for generating at least one connecting bridge with a reduced thickness when cutting workpiece parts from a plate-shaped workpiece. In particular, subsequent edge processing can be performed along the entire contour of the workpiece parts despite the presence of the connecting bridges.

[0007] In the method mentioned at the beginning, according to the present invention, this object is achieved by the following method steps:

[0008] - Generating at least one connecting bridge before cutting the workpiece parts;

[0009] - At least indent (Quetschen, sink it by extrusion) the connecting bridge along the thickness direction of the workpiece in the bridging section adjacent to the workpiece part to be cut / not yet cut, so that the indented connecting bridge retracts towards the center / middle of the workpiece relative to at least one of the two plate sides of the workpiece, wherein the edge formed by the retraction of the indented connecting bridge of the workpiece forms the edge of the workpiece part to be cut; and

[0010] - Cut a dividing seam corresponding to the contour of the workpiece part in the workpiece, and the dividing seam is interrupted along the edge formed by the retraction of the indented connecting bridge, whereby the workpiece part remains attached to the remaining grid of the workpiece by means of the indented connecting bridge.

[0011] According to the invention, the connecting bridge ("micro joint") is indented on one or both sides, and thus its thickness is reduced, so that the metal attachment point of the connecting bridge is displaced towards the center of the metal plate. Due to the reduction of the thickness of the indented connecting bridge, even when the workpiece thickness is greater than 2 mm, the cut workpiece part can be easily removed from the remaining grid. In addition, the retraction of the indented connecting bridge forms a straight edge of the subsequent workpiece part in the workpiece, and this straight edge together with the subsequent cutting edge of the workpiece part forms a continuous edge of the workpiece part. Then, in subsequent processing steps, the continuous edge can be rounded or chamfered using an edge processing tool.

[0012] Particularly preferably, the cutting edge of the cut workpiece part and the edge formed by the retraction of the indented connecting bridge of the workpiece part (which together form the continuous edge of the workpiece part) are processed by an edge processing tool guided along the (entire) contour of the workpiece part, in particular rounded or chamfered.

[0013] Compared with the end of the connecting bridge on the side of the remaining grid, the end of the connecting bridge on the side of the workpiece part can be indented to a smaller thickness, so as to advantageously form a predetermined breaking point of the workpiece part on the end of the connecting bridge on the side of the workpiece part. Here, the indented connecting bridge preferably has a cross-section that narrows towards the end of the connecting bridge on the side of the workpiece part, for example in a wedge shape, in the longitudinal plane formed by its longitudinal direction and its thickness direction.

[0014] Particularly preferably, the connecting bridge is dimpled on both sides in the thickness direction at least in the bridge section adjacent to the workpiece part to be cut, so that the dimpled connecting bridge retracts towards the center of the workpiece relative to the two plate sides of the workpiece. The edges formed by the retraction of the dimpled connecting bridge on both sides of the workpiece each form an edge of the workpiece part to be cut. The dimpled connecting bridge is only located at the center of the metal sheet thickness; thus, it is possible to apply a continuous edge rounding or chamfering on both sides over the entire contour of the workpiece part still attached to the remaining grid despite the presence of the dimpled connecting bridge.

[0015] Subsequently, the cutting edges of the cut workpiece part and the edges formed by the retraction of the dimpled connecting bridge on both sides of the workpiece part (which together form a continuous edge of the workpiece part) are processed simultaneously by an edge processing tool guided along the (entire) contour of the workpiece part, in particular rounded or chamfered.

[0016] Preferably, the connecting bridge in the workpiece is produced by two mutually spaced incisions, and the two incisions form the connecting bridge between them. Here, the dividing seam can lead into the incisions on both sides of the dimpled connecting bridge, in particular into the incision tips of the incisions. In this case, the dimpled connecting bridge is only connected to the workpiece part at the end sides. If the dividing seam does not lead into the incisions on both sides of the dimpled connecting bridge, the dimpled connecting bridge is still connected to the remaining grid on both sides. The ideal shape of the incision is triangular, because in this way, when the edge of the workpiece part is subsequently processed by an edge processing tool, the remaining grid can exert a supporting force on the dimpled connecting bridge, and the edge rounding tool will not be pushed aside. Incisions with shapes other than triangular are also conceivable. The incisions can be punched out in the workpiece or cut out using a processing beam (e.g., a laser beam).

[0017] Instead of first producing the connecting bridge by means of two incisions and then dimpling it in two separate steps, this can alternatively be carried out in a single step by dimpling the connecting bridge on one or both sides in the thickness direction of the workpiece by means of a suitable stamping tool while stamping and at least in the bridge section adjacent to the workpiece part to be cut. That is, the workpiece is not completely punched through at the location of the connecting bridge. The dimpled connecting bridge is preferably located in the lower third of the thickness of the workpiece part.

[0018] Preferably, the dividing seam is cut using a processing beam, such as a laser beam or a stamping tool.

[0019] On the other hand, the present invention also relates to a controller program product including code instructions, which are adapted to execute all steps of the method according to the present invention when the program runs on a controller of a machine tool suitable for executing all steps of the method according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Additional advantages of the present invention will become apparent from the specification and the drawings. Similarly, the features mentioned above, as well as those yet to be further cited, can be used separately or in any combination for multiple features. The embodiments shown and described should not be construed as exhaustive, but rather as having exemplary characteristics for describing the present invention. In the drawings:

[0021] Figure 1 A machine tool for metal sheet processing having a cutting station and a forming station is shown;

[0022] Figure 2 A metal sheet having two cuts with a connecting bridge formed between the cuts is shown in a perspective top view;

[0023] Figure 3a 、 Figure 3b 、 Figure 3c In a perspective top view ( Figure 3a ) and a perspective cross-sectional view ( Figure 3b )

[0024] and a longitudinal cross-section of the dimpled connecting bridge ( Figure 3c ) show a metal sheet having a dimpled connecting bridge;

[0025] Figure 4a 、 Figure 4b 、 Figure 4c In a perspective top view ( Figure 4a ) a metal sheet with workpiece parts that are cut and separated except for the dimpled connecting bridge is shown, and in a top view ( Figure 4b ) and a perspective cross-sectional view ( Figure 4c ) the dimpled connecting bridge is shown;

[0026] Figure 5a 、 Figure 5b 、 Figure 5c In a perspective top view ( Figure 5a ) and a longitudinal cross-section ( Figure 5b ) and a perspective cross-sectional view ( Figure 5c ) an edge rounding of workpiece parts that are cut and separated except for the dimpled connecting bridge is shown by means of an edge rounding tool; and

[0027] Figure 6 A completed workpiece part is shown in a perspective top view. DETAILED DESCRIPTION OF THE INVENTION

[0028] Figure 1The machine tool 1 shown is configured as a combined stamping - laser processing machine. The machine frame 2 of the machine tool 1 has a C - shaped shape and has upper frame legs 3 and lower frame legs 4. At the free ends of the upper frame legs 3 and the lower frame legs 4, a laser cutting station 5 and a forming station 6 are provided.

[0029] The laser cutting station 5 includes a laser cutting head 7 on the upper frame leg 3 and a laser beam receiver 8 on the lower frame leg 4. The forming station 6 has an upper tool receiver 9 on the upper frame leg 3 and a lower tool receiver 10 on the lower frame leg 4. An upper tool configured as a die 11 can be swapped into the upper tool receiver 9, and a lower tool configured as a bottom die 12 can be swapped into the lower tool receiver 10. The die 11 and the bottom die 12 are tool components of a forming tool or stamping tool 13.

[0030] By means of a conventional lifting drive, the die 11 can be raised and lowered relative to the bottom die 12 along a lifting axis 14. The upper tool receiver 9 and the lower tool receiver 10 can be rotationally adjusted together with the die 11 and the bottom die 12 about the lifting axis 14 ( Figure 1 the double - headed arrow in). All functions of the machine tool 1 are controlled by a programmable numerical control controller 15.

[0031] At the laser cutting station 5 and the forming station 6, a plate - shaped workpiece 16, in the example shown a metal sheet, is processed. For the purpose of processing, the metal sheet 16 is moved on the workpiece support 18 of the machine tool 1 in a biaxial horizontal movement by means of a conventional coordinate guide 17, and thereby moves relative to the laser cutting head 7 and the laser beam receiver 8 and also relative to the forming tool 13. In Figure 1 the metal sheet 16 is shown cut - through, whereby the laser beam receiver 8 and the lower tool receiver 10 of the forming bottom die 12 with the forming tool 13 can be seen. Based on the movement of the metal sheet 16 generated by the coordinate guide 17, the laser beam directed from the laser cutting head 7 onto the metal sheet 16 cuts out metal sheet components (e.g., finished components) while leaving connection bridges ("micro - joints"). Due to the remaining connection established via the connection bridges, the remaining grid and the metal sheet components are only incompletely separated from each other. Instead of the laser cutting beam, other types of cutting tools, in particular stamping tools swapped onto the forming station 6, can also be used for the incomplete separation of the remaining grid and the metal sheet components.

[0032] Figures 2 to 6 The method steps of a processing method according to the invention, which is carried out on the machine tool 1, are shown for cutting out a workpiece component 19, hereinafter referred to as a finished component, from a metal sheet 16 (e.g., 2 - mm structural steel) ( Figure 6 ) and for machining the edges of the finished component 19 along the entire finished - component contour during which the finished component 19 is still attached to the remaining grid of the metal sheet 16 via a thickness - reduced connection bridge.

[0033] In a first method step, two apertures or incisions 20 spaced apart from one another are punched out in the metal sheet 16 with a corresponding punching tool 13, and a connecting bridge (“micro joint”) 21 is formed between the two apertures or incisions ( Figure 2 ). Thus, during subsequent forming of the connecting bridge 21, material can flow laterally into the two incisions 20. Preferably, the incisions 20 lead into a dividing seam 22 yet to be produced. Alternatively, the incisions 20 can also be introduced by means of the laser beam of the laser cutting head 7. The incisions 20 are configured, for example, as triangles, in particular triangles with rounded corners, which form the connecting bridge 21 between the triangle sides facing one another, and each of which leads into the dividing seam 22 yet to be produced with a triangle tip.

[0034] In a second method step, the connecting bridge 21 is indented in the thickness direction 24 of the metal sheet 16 on a bridge section 23 adjacent to the later finished component 19 yet to be cut out (or alternatively over the entire bridge length of the bridge) with a corresponding forming tool (embossing tool) 13, so that the connecting bridge 21 retracts relative to one of the two sheet sides 16a, 16b of the metal sheet 16, or as shown, relative to the two sheet sides 16a, 16b in the direction of the workpiece center ( Figures 3a to 3c ). The indented connecting bridge or the bridge section is marked by 21' and forms, for example, a so-called nanojoint (a joint with a thickness less than the sheet thickness). The excess material from the indentation process flows into the previously introduced incisions 20. The indented connecting bridge 21' is now located in the center of the metal sheet thickness and is preferably at most 1 / 3 of the metal sheet thickness. Here, the straight upper and lower edges 25a, 25b formed on the later finished component 19 by the retraction of the indented connecting bridge 21' correspond to the contour of the later finished component 19.

[0035] As Figure 3c shown, the connecting bridge 21 is indented more strongly at the finished-component-side bridge end 21a of the connecting bridge, which is attached to the future finished component 19, than at the remaining-grating-side bridge end 21b of the connecting bridge, which is attached to the later remaining grating 26. As a result, the indented connecting bridge 21' has a cross section that narrows in the direction of the finished-component-side bridge end 21a and is wedge-shaped here in the longitudinal plane spanned by its longitudinal direction and its thickness direction 24. The bridge thickness d1 of the finished-component-side bridge end 21a is less than the bridge thickness d2 of the remaining-grating-side bridge end 21b, i.e., d1 < d2, in order to form a predetermined breaking point of the finished component 19 at the finished-component-side bridge end 21a of the workpiece component.

[0036] Instead of first producing and then indenting the connecting bridge 21 in two separate steps, this can alternatively also be done in a single step by simultaneously stamping and indenting the connecting bridge 21 with a suitable stamping tool. That is, the metal sheet 16 is not completely punched through at the location of the connecting bridge 21. The indented connecting bridge 21' is preferably located in the lower third of the metal sheet thickness.

[0037] In a third method step, a dividing seam 22 corresponding to the contour of the finished part 19 is cut out in the metal sheet 16, and this dividing seam is interrupted along the indented connecting bridge 21' or the upper and lower edges 25a, 25b ( Figures 4a to 4c ). The dividing seam 22 leads into the cutouts 20 on both sides of the indented connecting bridge 21', whereby the finished part 19 is only still held on the remaining grid 26 by the indented connecting bridge 21'. The dividing seam 22 is cut out using a laser beam or alternatively produced using a stamping tool 13. Preferably, a laser beam should be used to cut out the contour, because the cut seams with dimensions in the order of a few tenths of a millimeter have an ideal shape for the subsequent edge processing tools.

[0038] In an optional fourth method step, by means of an edge processing tool 28 that is swapped in instead of the forming tool or stamping tool 13, the edges of the finished part 19 are processed, for example rounded, along the entire contour of the finished part 19, that is, along the upper and lower cutting edges 27a, 27b and along both the upper and lower edges 25a, 25b ( Figures 5a to 5c ). Here, the edge processing tool 28 is exemplarily implemented as a roller clamping tool, which has an upper tool roller 28a in the upper tool and a lower tool roller 28b in the lower tool. Thus, edge rounding can be carried out simultaneously on the upper and lower sides of the metal sheet. The tool rollers 28a, 28b have annular rounding protrusions 29a, 29b on the circumferential side and engage into the dividing seam 22, and the rounding protrusions have a rounding radius (for example, 0.5 mm or less). The tool rollers 28a, 28b are displaced or loaded in the dividing seam 22 towards the finished part 19 in order to round the upper and lower edges 25a, 25b and the cutting edges 27a, 27b of the finished part 19. The die of the upper tool is pressed onto the upper tool roller 28a to generate the necessary pressing force. The die is elastically supported and can thus compensate for fluctuations in the metal sheet thickness. Instead of the shown rounding of both side members, corresponding edge processing tools can alternatively also be used to process, for example round, only the upper edge 25a, 27a or only the lower edge 25b, 27b (single-side member rounding). For example, a spherical deburring tool can also be used as the edge processing tool 28 in order to round the edges 25a, 25b and 27a, 27b by means of rolling deburring.

[0039] The finished component 19 is now complete and can be discharged from the machine tool 1( Figure 6 ). For this purpose, the recessed connecting bridge 21' can be punched out in the machine tool 1 or cut off by means of a laser beam, and then the now free finished component 19 is discharged via the component chute. Alternatively, the finished component 19 can also remain attached to the remaining grid 26 and be removed manually or with mechanical assistance from the remaining grid 26 at a later point in time after disconnecting the recessed connecting bridge 21'.

Claims

1. A method for generating at least one connecting bridge (21) with a reduced thickness when cutting a workpiece part (19) from a plate-shaped workpiece (16), wherein, The cut workpiece part (19) is held attached to the remaining grid (26) of the workpiece (16) by means of the connecting bridge (21). It is characterized by the following method steps: - generating the at least one connecting bridge (21) in the workpiece (16) before cutting the workpiece part (19); - indenting the connecting bridge (21) at least in the bridge section (23) adjacent to the workpiece part (19) to be cut in the thickness direction (24) of the workpiece (16), so that the indented connecting bridge (21') retracts in the direction towards the workpiece center with respect to at least one of the two plate sides (16a, 16b) of the workpiece (16), wherein the edges (25a, 25b) of the workpiece (16) formed by the retraction of the indented connecting bridge (21') form the edges of the workpiece part (19) to be cut; and - cutting a dividing seam (22) corresponding to the contour of the workpiece part (19) in the workpiece (16), the dividing seam being interrupted along the edges (25a, 25b) formed by the retraction of the indented connecting bridge (21'), whereby the workpiece part (19) is held attached to the remaining grid (26) of the workpiece (16) by means of the indented connecting bridge (21').

2. The method according to claim 1, characterized in that The cutting edges (27a, 27b) of the cut workpiece part (19) and the edges (25a, 25b) of the workpiece part (19) formed by the retraction of the indented connecting bridge (21') are machined by means of an edge machining tool (28) guided along the contour of the workpiece part (19).

3. The method according to claim 1 or 2, characterized in that, The connecting bridge (21) is indented to a smaller thickness at the bridge end (21a) on the workpiece part side than at the bridge end (21b) on the remaining grid side.

4. The method according to any one of the preceding claims, characterized in that, The indented connecting bridge (21') has a cross-section narrowing in the direction towards the bridge end (21a) on the workpiece part side in the longitudinal plane formed by its longitudinal direction and its thickness direction (24).

5. The method according to any one of the preceding claims, characterized in that, The connecting bridge (21) is indented on both sides in the thickness direction (24) at least in the bridge section (23) adjacent to the workpiece part (19) to be cut, so that the indented connecting bridge (21') retracts in the direction towards the workpiece center with respect to the two plate sides (16a, 16b) of the workpiece (16) respectively, wherein the edges (25a, 25b) of the workpiece (16) formed by the retraction on both sides of the indented connecting bridge (21') form the edges of the workpiece part (19) to be cut respectively.

6. The method according to claim 5, characterized in that, The cutting edges (27a, 27b) of the cut workpiece part (19) and the edges (25a, 25b) of the workpiece part (19) formed by the retraction on both sides of the indented connecting bridge (21') are machined simultaneously by means of an edge machining tool (28) guided along the contour of the workpiece part (19).

7. The method according to any one of the preceding claims, characterized in that, The connection bridge (21) in the workpiece (16) is produced by two mutually spaced-apart incisions (20), and the two incisions form the connection bridge (21) therebetween.

8. The method according to claim 7, characterized in that, The dividing seam (22) leads into the incisions (20) on both sides of the recessed connection bridge (21'), respectively.

9. The method according to claim 7 or 8, characterized in that, The dividing seam (22) leads into the incision tips of the incisions (20) on both sides of the recessed connection bridge (21'), respectively.

10. The method according to any one of claims 7 to 9, characterized in that, The incisions (20) are configured as triangles, and the connection bridge (21) is formed between the mutually facing triangular sides.

11. The method according to any one of claims 7 to 10, characterized in that, The incisions (20) are punched out in the workpiece (16) or cut out using a machining beam.

12. The method according to any one of claims 1 to 6, characterized in that The connection bridge (21) is recessed unilaterally or bilaterally in the thickness direction (24) of the workpiece (16) by means of a stamping tool (13) while being stamped and at least on a bridge section (23) adjacent to a workpiece part (19) to be cut.

13. The method according to any one of the preceding claims, characterized in that, The dividing seam (22) is cut out using a machining beam or a stamping tool.

14. A controller program product having code instructions adapted to perform all steps of the method according to any one of the preceding claims when the program runs on a controller (15) of a machine tool (1) adapted to execute all steps of the method according to any one of the preceding claims.

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