Method for correcting flat pattern

Abstract

A one-side elongation value in V-bending of two flanges formed when a workpiece (1) is V-bent at a first bending line (BL) by a press brake and a one-side elongation value in L-bending of two flanges formed when the workpiece (1) is L-bent at the first bending line (BL) by a panel bender are obtained in advance. A computer sets, as a second bending line (BL'), a position obtained by offsetting, by a distance based on the difference between the one-side elongation value in the V-bending and the one-side elongation value in the L-bending, the position of the first bending line (BL) in a first flat pattern for use in bending the workpiece (1) at the first bending line (BL) by the press brake. The computer replaces the first bending line (BL) in the first flat pattern with the second bending line (BL'), thereby correcting the first flat pattern into a second flat pattern for use in bending at the second bending line (BL') by the panel vendor.

Description

Development drawing correction method

[0001] The present disclosure relates to a development correction method.

[0002] When bending a plate-shaped workpiece, a press brake such as that described in Patent Document 1 may be used, or a panel bender such as that described in Patent Document 2 may be used. Bending in which the workpiece is sandwiched between a punch and a die in a press brake and bent is called V-bending, while bending in which the workpiece is clamped by a plate holder in a panel bender and bent with a bend beam is called L-bending.

[0003] JP 2024-61620 A JP 2019-118913 A

[0004] When bending a workpiece using a press brake, a development drawing for a V-bend must be prepared, and when bending the workpiece using a panel bender, a development drawing for an L-bend must be prepared. Preparing two different development drawings like this is cumbersome. If it were possible to correct one development drawing to the other, preparing one type of development drawing would be sufficient, eliminating the cumbersome task of preparing two types of development drawings. There is a need for a development drawing correction method that can correct a V-bend development drawing to an L-bend development drawing, or correct an L-bend development drawing to a V-bend development drawing.

[0005] One aspect of one or more embodiments provides a development view correction method in which an one-sided V-bend elongation value of two flanges formed when a plate-shaped workpiece is V-bent at a predetermined angle at a first bend line by a press brake, and an one-sided L-bend elongation value of two flanges formed when the workpiece is L-bent at the first bend line by a panel bender are determined in advance, and a computer corrects the first development view to a second development view to be used to bend the workpiece at the second bend line at the predetermined angle at the first bend line by one of the press brake and the panel bender by replacing the first bend line in the first development view with the second bend line, the second bend line being offset by a distance based on the difference between the one-sided V-bend elongation value and the one-sided L-bend value.

[0006] According to one or more embodiments of the development correction method, a development for a V bend can be corrected to a development for an L bend, or an L bend development can be corrected to a development for a V bend.

[0007] FIG. 1 is a perspective view showing a plate-shaped workpiece to be bent by a press brake or a panel bender. FIG. 2 is a view showing the workpiece shown in FIG. 1 after being bent by a press brake. FIG. 3 is a side view showing a product shape obtained by the bending process shown in FIG. 2. FIG. 4 is a development for V-bending to obtain the product shape shown in FIG. 3. FIG. 5 is a side view showing the workpiece shown in FIG. 1 before being bent by a panel bender. FIG. 6 is a side view showing the workpiece shown in FIG. 1 after being bent by a panel bender. FIG. 7 is a side view showing an unbalanced elongation value in an L-bend when the workpiece shown in FIG. 1 is bent by a panel bender. FIG. 8 is a development for L-bending. FIG. 9 is a side view showing a development correction method according to one or more embodiments, which corrects a development for V-bending to a development for L-bending. FIG. 10 is a side view showing a development correction method according to one or more embodiments, which corrects a development for L-bending to a development for V-bending. Figure 11 is a flowchart showing a process for bending a workpiece by selecting a press brake or a panel bender as the machine for bending the workpiece using a development view correction method according to one or more embodiments. Figure 12 is a diagram showing the state of the workpiece before bending, for explaining a method for calculating the one-sided elongation value in an L-bend. Figure 13 is a diagram showing the state of the workpiece after being bent at 90 degrees, for explaining a method for calculating the one-sided elongation value in an L-bend. Figure 14 is a diagram showing the state of the workpiece after being bent at an obtuse angle.

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A development correction method according to one or more embodiments will now be described with reference to the accompanying drawings.

[0009] Assume that a plate-shaped workpiece 1 shown in Figure 1 is bent using a press brake along a bend line BL indicated by a dashed line. The workpiece 1 is sheet metal. As shown in Figure 2, the press brake clamps the workpiece 1 between a punch 11 and a die 12, and bends the workpiece 1 to a predetermined angle, for example, 90 degrees, by lowering the punch 11 toward the die 12. The regions formed by bending the workpiece 1, from one end of the workpiece 1 to the bend line BL and from the other end to the bend line BL, are referred to as flanges 2 and 3, respectively.

[0010] Figure 3 is a side view of workpiece 1 bent at 90 degrees. The dimension of flange 2 is X, and the dimension of flange 3 is F. If the length L1 of workpiece 1 shown in Figure 1 is (X + F), and workpiece 1 is bent using a press brake, the dimension of flange 2 will not be X, and the dimension of flange 3 will not be F. This is because both flanges 2 and 3 are slightly elongated by the bending process using the press brake. The elongation values ​​of both flanges 2 and 3 are called one-sided elongation values, and the one-sided elongation value is d. The one-sided elongation value d is common to flanges 2 and 3. The one-sided elongation value d is the one-sided elongation value of the V-bend in flanges 2 and 3.

[0011] Figure 4 shows a development of workpiece 1 for V-bending, taking into account the one-sided elongation value d. The development shown in Figure 4 corresponds to a side view of workpiece 1 before bending it to obtain the product shape shown in Figure 3. As shown in Figure 4, the dimension of flange 2 is X-d, and the dimension of flange 3 is F-d. The one-sided elongation value d may be a measured value measured in advance, an empirical value, or a calculated value by a computer such as an NC device that controls the press brake.

[0012] Assume that the plate-shaped workpiece 1 shown in FIG. 4 is bent using a panel bender along the bend line BL indicated by the dashed line. As shown in FIG. 5, the panel bender clamps the flange 2, which has a dimension X-d, with a pair of plate holders 21 along the bend line BL, and contacts the bend beam 22 with, for example, the end of the flange 3, which has a dimension F-d. The bend beam 22 does not have to contact the end of the flange 3. As shown in FIG. 6, the bend beam 22 is raised and moved toward the plate holders 21 to bend the workpiece 1. When the workpiece 1 is bent in this way, the dimension X' of the flange 2' differs from the dimension X, and the dimension F' of the flange 3' differs from the dimension F. Therefore, even if the workpiece 1 is bent using a panel bender using the V-bend development of the workpiece 1 shown in FIG. 4, the product shape shown in FIG. 3 cannot be obtained.

[0013] FIG. 7 shows the one-sided elongation values ​​for L-bending of workpiece 1 using a panel bender. The one-sided elongation value for flange 2' is d1, and the one-sided elongation value for flange 3' is a negative value, d2. The one-sided elongation values ​​d1 and d2 are the one-sided elongation values ​​for L-bending of flanges 2' and 3'. A computer such as an NC device that controls the panel bender can calculate the bending radius between flanges 2' and 3' when workpiece 1 is L-bent based on conditions such as the material and thickness of workpiece 1 and the distance between plate holder 21 and bend beam 22. The computer can calculate the one-sided elongation values ​​d1 and d2 based on the bending radius. The method for calculating the one-sided elongation values ​​d1 and d2 will be described in detail later.

[0014] 8 shows a development view of the workpiece 1 for L-bending, taking into consideration the one-sided elongation values ​​d1 and d2. As shown in FIG. 8, the dimension of the flange 2' is X-d1, and the dimension of the flange 3' is F-d2.

[0015] Using Figure 9, we will explain a development correction method for correcting a development for a V-bend to a development for an L-bend. When V-bending workpiece 1 at bend line BL, the dimension of flange 2 is X-d, and the dimension of flange 3 is F-d. Although flanges 2' and 3' are not shown in Figure 9, when L-bending workpiece 1, the dimension of flange 2' is X-d1, and the dimension of flange 3' is F-d2. Although d ≠ d1 and d ≠ d2, it can be seen that 2d = d1 + d2. Therefore, by offsetting the bend line BL for a V-bend by a distance (d1 - d) so that flange 2 is shorter and flange 3 is longer, it is possible to create a bend line BL' for an L-bend. The distance (d1 - d) is the offset amount.

[0016] A method for correcting a development for a V-bend to a development for an L-bend according to one or more embodiments is as follows. The development for a V-bend shown in FIG. 4 is defined as the first development. The bend line BL for a V-bend is defined as the first bend line, and the bend line BL' for an L-bend is defined as the second bend line. Flanges 2 and 3 obtained when workpiece 1 is V-bent along the first bend line by a press brake are defined as the first and second flanges, respectively. Flanges 2' and 3' obtained when workpiece 1 is L-bent along the first bend line by a panel bender are defined as the third and fourth flanges, respectively. The third flange is the flange clamped by plate holder 21 of the panel bender, and the fourth flange is the flange bent by bend beam 22 of the panel bender.

[0017] The one-sided elongation value d is the first one-sided elongation value, and the one-sided elongation values ​​d1 and d2 are the second and third one-sided elongation values, respectively. The first one-sided elongation value common to the first and second flanges is determined in advance. The second one-sided elongation value of the third flange and the third one-sided elongation value of the fourth flange are determined in advance.

[0018] The computer determines the position of the second bend line as a position obtained by offsetting the position of the first bend line in the first developed view by a distance obtained by subtracting the first one-sided elongation value (d) from the second one-sided elongation value (d1) so that the third flange is shorter and the fourth flange is longer. The computer corrects the first developed view to a second developed view for an L-bend by replacing the first bend line in the first developed view with the second bend line.

[0019] According to the development correction method according to one or more embodiments shown in FIG. 9, a development for a V-bend can be corrected to a development for an L-bend.

[0020] A method for correcting an L-bend development to a V-bend development will be described using Figure 10. When correcting an L-bend development to a V-bend development, the L-bend bending line BL can be offset by a distance (d1-d) so that flange 2' is longer and flange 3' is shorter, resulting in a V-bend bending line BL'.

[0021] A method for correcting a development for an L-bend to a development for a V-bend according to one or more embodiments is as follows. The development for an L-bend shown in FIG. 8 is defined as the first development. The bend line BL for an L-bend is defined as the first bend line, and the bend line BL' for a V-bend is defined as the second bend line. When workpiece 1 is bent into an L-bend along the first bend line by a panel bender, flanges 2' and 3' are defined as the first and second flanges, respectively. The first flange is the flange clamped by plate clamp 21, and the second flange is the flange bent by bend beam 22. When workpiece 1 is bent into a V-bend along the first bend line by a press brake, flanges 2 and 3 are defined as the third and fourth flanges, respectively.

[0022] The one-sided elongation values ​​d1 and d2 are the first and second one-sided elongation values, respectively, and the one-sided elongation value d is the third one-sided elongation value. The first one-sided elongation value of the first flange and the second one-sided elongation value of the second flange are determined in advance. The third one-sided elongation value common to the third and fourth flanges is determined in advance.

[0023] The computer determines the position of the second bend line as a position obtained by offsetting the position of the first bend line in the first developed view by a distance obtained by subtracting the third one-sided elongation value (d) from the first one-sided elongation value (d1) so that the third flange is longer and the fourth flange is shorter. The computer corrects the first developed view to a second developed view for a V-bend by replacing the first bend line in the first developed view with the second bend line.

[0024] According to the development correction method of one or more embodiments shown in FIG. 10, a development for an L-bend can be corrected to a development for a V-bend.

[0025] The above-described development correction method for correcting a development for a V-bend to a development for an L-bend, and the development correction method for correcting a development for an L-bend to a development for a V-bend, can be summarized as follows: The one-sided elongation value of the V-bend in the two flanges formed when the workpiece 1 is V-bent at a predetermined angle at the first bend line by a press brake, and the one-sided elongation value of the L-bend in the two flanges formed when the workpiece 1 is L-bent at a predetermined angle at the first bend line by a panel bender are determined in advance.

[0026] The computer sets the second bend line to a position obtained by offsetting the position of the first bend line in the first development drawing used to bend the workpiece 1 to a predetermined angle at the first bend line by one of the press brake and the panel bender by a distance based on the difference between the one-sided elongation value for the V-bend and the one-sided elongation value for the L-bend. By replacing the first bend line in the first development drawing with the second bend line, the computer corrects the first development drawing to a second development drawing used to bend the workpiece to a predetermined angle at the second bend line by the other of the press brake and the panel bender.

[0027] The flowchart shown in Figure 11 will be used to explain a process for selecting whether to bend a workpiece using a press brake or a panel bender when a development drawing for V-bending has been created. In Figure 11, when the process starts, an operator or a computer determines the one-sided elongation value d for V-bending in step S1. The computer creates a development drawing for V-bending in step S2. The computer that executes the process in step S2 is preferably a computer that is equipped with and executes a CAD (Computer Aided Design) / CAM (Computer Aided Manufacturing) program.

[0028] In step S3, the operator selects a machine to bend the workpiece. If the operator selects a press brake, the operator determines that the machine to bend the workpiece is the press brake in step S11. In step S12, the press brake bends the workpiece using the development drawing for V-bending, and the process ends.

[0029] When the operator selects a panel bender, the operator determines in step S21 that the machine that will bend the workpiece is the panel bender. The NC device of the panel bender, which is an example of a computer, calculates the one-sided elongation values ​​d1 and d2 for the L-bend in step S22, and calculates the offset amount of the bend line BL in step S23. In step S24, the NC device offsets the position of the bend line BL in the development drawing for the V-bend to correct it to an L-bend development. In step S25, the panel bender bends the workpiece using the development drawing for the L-bend, and then ends the process.

[0030] In FIG. 11, if the computer creates an L-bend development drawing instead of steps S1 and S2, steps S22 to S24 can be omitted, and a step of correcting the L-bend development drawing to a V-bend development drawing can be provided between steps S11 and S12.

[0031] 12 and 13, a method for calculating the one-sided elongation values ​​d1 and d2 in an L-bend will be described. As can be seen from FIGS. 7 and 8, d1 = X' - X and d2 = F' - F. Let X be the dimension of flange 32 and F be the dimension of flange 33 when workpiece 31 shown in FIG. 12 is divided by bend line BL. Between flanges 32 and 33, there is an arc portion 33R that becomes the bend R when workpiece 31 is bent in an L-bend. If the bend angle of workpiece 31 is 90 degrees, then the dimension X' of flange 32 shown in FIG. 13 is X + R, and d1 = R.

[0032] If the arc portion 33R indicated by the dashed line has an angle φ [rad], the length of the arc portion 33R is R×φ, and the length of the flange 33 excluding the arc portion 33R is F−R×φ. The length of the flange 33 shown in Figure 13 is F−R×φ+R, and since d2 = F'−F, d2 = F−R×φ+R−F = R(1−φ). The one-sided elongation values ​​d1 and d2 of the L-bend in step S22 shown in Figure 11 can be calculated geometrically in this way.

[0033] 14 shows a case where the bending angle of the workpiece 31 is an obtuse angle. Even if the predetermined bending angle of the workpiece 31 is an obtuse angle, the one-sided elongation values ​​d1 and d2 of the L-bend can be calculated geometrically.

[0034] The present invention is not limited to one or more of the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the present invention.

[0035] This application claims priority based on Japanese Patent Application No. 2024-140818, filed with the Japan Patent Office on August 22, 2024, the entire disclosure of which is incorporated herein by reference.

Claims

1. A development correction method in which a V-bend elongation value of two flanges formed when a plate-shaped workpiece is V-bent at a predetermined angle along a first bend line by a press brake, and an L-bend elongation value of two flanges formed when the workpiece is L-bended at the first bend line by a panel bender are determined in advance, and a computer corrects the first development to a second development to be used to bend the workpiece at the second bend line to the predetermined angle along the first bend line by one of the press brake and the panel bender by replacing the position of the first bend line in the first development with the second bend line, offsetting the position of the first bend line by a distance based on the difference between the V-bend elongation value and the L-bend elongation value.

2. The two flanges formed when the workpiece is V-bent at the first bend line to the predetermined angle by the press brake are defined as the first and second flanges, and the two flanges formed when the workpiece is L-bent at the first bend line to the predetermined angle by the panel bender are defined as the third and fourth flanges, the third flange is a flange that is clamped by a plate holder of the panel bender, and the fourth flange is a flange that is bent by a bend beam of the panel bender, the one-sided elongation value of the V-bend is a first one-sided elongation value that is common to the first and second flanges, the one-sided elongation value of the L-bend is a second one-sided elongation value that is the one-sided elongation value of the third flange, and a third one-sided elongation value that is the one-sided elongation value of the fourth flange, when the first development drawing is a development drawing used to V-bend the workpiece at the first bend line to the predetermined angle by the press brake, 2. The development correcting method according to claim 1, wherein the position of the first bend line in the first development is offset by a distance obtained by subtracting the first one-sided elongation value from the second one-sided elongation value so that the third flange is shorter and the fourth flange is longer, and the second bend line is set to a position where the first bend line is offset, and the first bend line in the first development is replaced with the second bend line, thereby correcting the first development to the second development used for bending the workpiece at the second bend line to the predetermined angle by the panel bender.

3. The two flanges formed when the workpiece is L-bent at the first bend line to the predetermined angle by the panel bender are the first and second flanges, and the two flanges formed when the workpiece is V-bent at the first bend line to the predetermined angle by the press brake are the third and fourth flanges, the first flange is the flange clamped by the plate holder of the panel bender, and the second flange is the flange bent by the bend beam of the panel bender, the one-sided elongation value of the L-bend is a first one-sided elongation value that is the one-sided elongation value of the first flange, and a second one-sided elongation value that is the one-sided elongation value of the second flange, and the one-sided elongation value of the V-bend is a third one-sided elongation value that is common to the third and fourth flanges, when the first development drawing is a development drawing used to L-bend the workpiece at the first bend line to the predetermined angle by the panel bender, 2. The development correcting method according to claim 1, wherein the position of the first bend line in the first development is offset by a distance obtained by subtracting the third one-sided elongation value from the first one-sided elongation value so that the third flange is longer and the fourth flange is shorter, and the second bend line is set to a position where the first bend line in the first development is replaced with the second bend line, thereby correcting the first development to the second development used for V-bending the workpiece at the second bend line to the predetermined angle by the press brake.

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