Control device for wire electrical discharge machine and control method for wire electrical discharge machine

Abstract

In a control device (18) of an online electric discharge machine (10), a path shape determination section (32) determines whether a path shape defined by two program blocks is a right corner or a left corner, based on coordinates of three points determined by start points and end points of the two program blocks, in a case where it is determined that lengths of the paths defined by the two program blocks are below a diameter of a wire electrode (12). An inside-outside corner determination section (36) determines whether it is an inside corner or an outside corner, based on a bias direction, in a case where it is determined that the path shape is the left corner or the right corner.

Description

Technical Field

[0001] This invention relates to a control device for a wire electrical discharge machining (EDM) machine and a control method for such a machine. Background Technology

[0002] Japanese Patent Application Publication No. 2021-041475 discloses a wire electrical discharge machining (EDM) machine. This EDM machine performs machining by changing the machining conditions according to the path shape specified by the machining program. This improves the machining accuracy of the workpiece. Summary of the Invention

[0003] Sometimes, the path shape of a curve is defined by combining multiple program blocks that specify extremely short paths. In this case, the machining shape cannot be determined based on the movement instructions of each program block. Therefore, in the wire electrical discharge machining machine disclosed in Japanese Patent Application Publication No. 2021-041475, there is a problem of reduced machining accuracy of the workpiece.

[0004] The purpose of this invention is to solve the above-mentioned problems.

[0005] The first aspect of the present invention is a control device for a wire electrical discharge machining (EDM) machine. The EDM machine moves a wire electrode relative to a workpiece according to a machining program with a predetermined program path, and applies a voltage between the wire electrode and the workpiece to perform EDM machining. The control device includes: a minimum program block determination unit that determines whether the length of a path defined by two consecutive program blocks is less than or equal to the diameter of the wire electrode; and a path shape determination unit that, when determining that the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the wire electrode, determines the path shape based on the length of the two consecutive program blocks. The coordinates of three points determined by the start and end points of the program blocks are used to determine whether the path shape defined by two consecutive program blocks is a right corner that bends to the right or a left corner that bends to the left in the direction of travel of the wire electrode; an offset direction acquisition unit obtains the offset direction from the machining program in two consecutive program blocks; an inner and outer corner determination unit determines whether it is an inner or outer corner based on the offset direction if the path shape is determined to be a left or right corner; and an electrical discharge machining control unit controls the electrical discharge machining based on the determination result of the inner and outer corner determination unit.

[0006] The second aspect of the present invention is a control method for a wire electrical discharge machining (EDM) machine. The EDM machine moves a wire electrode relative to a workpiece according to a machining program with a defined program path, and applies a voltage between the wire electrode and the workpiece to perform EDM machining. The control method includes the following steps: a minimum program block determination step, determining whether the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the wire electrode; and a path shape determination step, when it is determined that the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the wire electrode, determining the path shape based on the length of the path defined by the two consecutive program blocks. The coordinates of three points determined by the start and end points of the two program blocks are used to determine whether the path shape defined by the two consecutive program blocks is a right corner that bends to the right or a left corner that bends to the left in the direction of travel of the wire electrode; the offset direction acquisition step obtains the offset direction from the two consecutive program blocks in the machining program; the inner and outer corner determination step determines whether it is an inner or outer corner based on the offset direction if the path shape is determined to be a left or right corner; and the electrical discharge machining control step controls the electrical discharge machining based on the determination result in the inner and outer corner determination step.

[0007] According to the present invention, the machining accuracy of the workpiece can be improved. Attached Figure Description

[0008] Figure 1 This is a schematic diagram representing a wire electrical discharge machining (EDM) machine.

[0009] Figure 2 This is a table showing the combination of G-codes representing circular interpolation and G-codes representing offset direction, and their correspondence with inner and outer corners.

[0010] Figure 3 This is a schematic diagram illustrating an example of a path with an outward corner.

[0011] Figure 4 This is a diagram illustrating the method for determining the shape of a path.

[0012] Figure 5 This is a diagram illustrating the method for determining the shape of a path.

[0013] Figure 6 This is a diagram illustrating the method for determining the shape of a path.

[0014] Figure 7 This is a flowchart illustrating the process of determining the path shape in the control device. Detailed Implementation

[0015] [First Implementation]

[0016] [Structure of a wire electrical discharge machining (EDM) machine]

[0017] Figure 1 This is a schematic diagram showing a wire electrical discharge machining (EDM) machine 10. The EDM machine 10 generates a discharge by applying a voltage between the wire electrode 12 and the workpiece 14 (hereinafter sometimes referred to as the machining gap). This performs EDM machining on the workpiece 14. The EDM machine 10 includes a machine body 16 and a control device 18.

[0018] The machining machine body 16 includes a machining power supply 20, an X-axis motor 22, and a Y-axis motor 24. The machining power supply 20 applies voltage to the machining gap. The X-axis motor 22 and the Y-axis motor 24 move a worktable (not shown). The workpiece 14, fixed to the worktable, moves together with the worktable, thereby causing the wire electrode 12 to move relative to the workpiece 14.

[0019] The control unit 18 includes an arithmetic unit 26 and a storage unit 28. The arithmetic unit 26 is, for example, a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). The arithmetic unit 26 includes a minimal program block determination unit 30, a path shape determination unit 32, a bias direction acquisition unit 34, an inner and outer corner determination unit 36, and a discharge machining control unit 38. The minimal program block determination unit 30, the path shape determination unit 32, the bias direction acquisition unit 34, the inner and outer corner determination unit 36, and the discharge machining control unit 38 are implemented by the arithmetic unit 26 executing a program stored in the storage unit 28. At least a portion of the minimal program block determination unit 30, the path shape determination unit 32, the bias direction acquisition unit 34, the inner and outer corner determination unit 36, and the discharge machining control unit 38 can also be implemented using integrated circuits such as ASICs (Application Specific Integrated Circuits) or FPGAs (Field-Programmable Gate Arrays). At least a portion of the minima block determination unit 30, the path shape determination unit 32, the bias direction acquisition unit 34, the inner and outer corner determination unit 36, and the electrical discharge machining control unit 38 can also be implemented by a circuit containing discrete components.

[0020] The storage unit 28 comprises volatile memory (not shown) and non-volatile memory (not shown). The volatile memory is, for example, RAM (Random Access Memory). The non-volatile memory is, for example, ROM (Read Only Memory), flash memory, etc. Data is stored, for example, in the volatile memory. Programs, tables, mappings, etc., are stored, for example, in the non-volatile memory. At least a portion of the storage unit 28 may also be provided in the aforementioned processor, integrated circuit, etc. At least a portion of the storage unit 28 may also be mounted in a device connected to the wire EDM machine 10 via a network.

[0021] [Regarding paths with corners]

[0022] Typically, paths with corners are defined by program blocks with G-codes "G02" or "G03" indicating circular interpolation. A path defined by a program block with G-code "G02" has a right corner. A path defined by a program block with G-code "G03" has a left corner. A right corner refers to a path that bends to the right in the direction of travel of the wire electrode 12. A left corner refers to a path that bends to the left in the direction of travel of the wire electrode 12.

[0023] In this case, by combining the G-code representing circular interpolation and the G-code representing the offset direction, it is possible to determine whether the path shape is an inner corner or an outer corner. Figure 2 This is a table showing the combination of G-codes representing circular interpolation and G-codes representing offset direction, as well as the correspondence between inner and outer corners. An inner corner refers to the path shape of the surface of the machined object 14 protruding inwards towards the inside of the machined object 14. An outer corner refers to the path shape of the surface of the machined object 14 protruding outwards towards the outside of the machined object 14.

[0024] like Figure 2 As shown, the combination of the G-code "G03" representing a left corner and the G-code "G41" representing a left offset determines that the path shape is an inner corner. Figure 2 As shown, the combination of the G-code "G03" representing a left corner and the G-code "G42" representing a right offset determines that the path shape is an outer corner. Figure 2 As shown, the combination of the G-code "G02" representing a right corner and the G-code "G41" representing a left offset determines that the path shape is an outer corner. Figure 2 As shown, the combination of the G code "G02" representing a right corner and the G code "G42" representing a right offset determines that the path shape is an inner corner.

[0025] The electrical discharge machining (EDM) control unit 38 adjusts the machining conditions based on the path shape. Based on the adjusted machining conditions, the EDM control unit 38 outputs command values ​​to the machining power supply 20, the X-axis motor 22, the Y-axis motor 24, etc., thereby controlling the EDM machining of the workpiece 14. Specifically, the EDM control unit 38 controls the machining speed, the number of applications, etc., based on the path shape. The machining speed refers to the relative movement speed of the wire electrode 12 relative to the workpiece 14. The number of applications refers to the number of times voltage is applied to the machining gap per unit time.

[0026] For example, when the path shape has an inner corner, the EDM control unit 38 slows down the processing speed compared to when the path shape is a straight line. Furthermore, when the path shape has an inner corner, the greater the curvature of the path shape, the slower the processing speed is. When the path shape has an inner corner, the EDM control unit 38 performs more passes compared to when the path shape is a straight line. Furthermore, when the path shape has an inner corner, the greater the curvature of the path shape, the more passes are performed by the EDM control unit 38.

[0027] For example, when the path shape has an outer corner, the EDM control unit 38 increases the processing speed compared to when the path shape is a straight line. Furthermore, when the path shape has an outer corner, the smaller the curvature of the path shape, the faster the EDM control unit 38 increases the processing speed. When the path shape has an outer corner, the EDM control unit 38 reduces the number of passes compared to when the path shape is a straight line. Furthermore, when the path shape has an outer corner, the smaller the curvature of the path shape, the fewer passes the EDM control unit 38 reduces.

[0028] Figure 3 This is a schematic diagram illustrating an example of a path with an outward corner. Figure 3 The path shown is defined by multiple program blocks having the G-code "G01" representing linear interpolation. The length of the path defined by each program block is less than or equal to the diameter of the line electrode 12. Hereinafter, program blocks whose defined path length is less than or equal to the diameter of the line electrode 12 are sometimes referred to as minimal program blocks. Furthermore, regarding the definition... Figure 3 The program blocks in the path shown are set to the right-biased G code "G42".

[0029] Figure 3 The path shape shown is an outer corner. However, since the G code of each program block is "G01" which represents linear interpolation, the EDM control unit 38 determines the path shape to be a straight line. The EDM control unit 38 adjusts the machining conditions to the straight-line path shape and performs EDM. Therefore, the accuracy of the machined surface of the workpiece 14 may deteriorate after machining.

[0030] It can also be defined by multiple tiny program blocks with G-code "G02" representing circular interpolation of a right corner. Figure 3 Equal path shape. Set the G-code "G42" to indicate right offset for each block.

[0031] Figure 3 The path shape shown is an outer corner. However, the G-code of each program block is "G02" indicating circular interpolation for a right corner, and "G42" indicating right offset is set. Therefore, the EDM control unit 38 determines the path shape to be an inner corner. The EDM control unit 38 adjusts the machining conditions to the condition when the path shape is an inner corner and performs EDM. As a result, the accuracy of the machined surface of the workpiece 14 may deteriorate.

[0032] It can also be defined by multiple tiny program blocks with G-code "G03" representing circular interpolation of a left corner. Figure 3 Equal path shape. Set the G-code "G42" to indicate right offset for each block.

[0033] Figure 3 The path shape shown is an outer corner. The G-code for each program block is "G03" indicating circular interpolation for a left corner, and "G42" indicating right offset is set. Therefore, the EDM control unit 38 determines that the path shape is an outer corner. The EDM control unit 38 adjusts the machining conditions to those for an outer corner path and performs EDM. However, the path shape cannot be determined from the G-code of each program block. Figure 3 The curvature of the path shape at the outer corner is shown. Therefore, the accuracy of the machined surface of the machined object 14 may deteriorate after machining.

[0034] Therefore, the path shape determination unit 32 of this embodiment determines the path shape based on the coordinates of three points determined by the start and end points of two consecutive program blocks. Specifically, the path shape determination unit 32 determines the path shape using the method described below.

[0035] [Judgment Method (1)]

[0036] Figure 4 This is a diagram illustrating the method for determining the path shape. In the determination method (1), the path shape determination unit 32 determines the path shape based on the cross product of the vector from the start point to the end point of the first program block and the vector from the start point to the end point of the second program block in the consecutive first program block and second program block.

[0037] Let P0 be the starting point of the first program block, P1 be the ending point, and a vector from P0 to P1 be denoted as 'a'. Let the coordinates of P0 be (x0, y0), and the coordinates of P1 be (x1, y1). The starting point of the next program block, the second program block, is the same as the ending point P1 of the first program block. Let P2 be the ending point of the second program block, and a vector from P1 to P2 be denoted as 'b'. Let the coordinates of P2 be (x2, y2). The cross product of vectors a and b, a×b, is calculated using the following formula.

[0038] [Formula 1]

[0039] a×b=(x1-x0)(y2-y1)-(y1-y0)(x2-x1)…(1)

[0040] When the cross product of vectors a and b is 0, the path shape determination unit 32 determines that the path shape defined by the first and second program blocks is a straight line. When the cross product of vectors a and b is positive, the path shape determination unit 32 determines that the path shape defined by the first and second program blocks is a left-turn. When the cross product of vectors a and b is negative, the path shape determination unit 32 determines that the path shape defined by the first and second program blocks is a right-turn. Furthermore, the larger the absolute value of the cross product of vectors a and b, the greater the curvature determined by the path shape determination unit 32.

[0041] [Judgment Method (2)]

[0042] Figure 5 This is a diagram illustrating the method for determining the path shape. In determination method (2), the path shape determination unit 32 determines the path shape based on the curvature of the line passing through the start and end points of the first and second consecutive program blocks.

[0043] Set the start point of the first program block to P0 and the end point to P1. Set the coordinates of the start point P0 to (x0, y0) and the coordinates of the end point P1 to (x1, y1). The start point of the next program block, the second program block, is the same as the end point P1 of the first program block. Set the end point of the second program block to P2. Set the coordinates of the end point P2 to (x2, y2).

[0044] The path shape determination unit 32 sets a function f(x), which represents the line passing through the start and end points of the first and second program blocks. The function f(x) is a function that can be differentiated twice. That is, the function f(x) is a function of degree two or higher, or a trigonometric function. Furthermore, the number of coefficients of the function f(x) is three or less. The curvature κ of the line passing through the start and end points of the first and second program blocks is calculated by the following formula.

[0045] [Formula 2]

[0046]

[0047] When the curvature κ is 0, the path shape determination unit 32 determines that the path shape defined by the first program block and the second program block is a straight line. When the curvature κ is positive, the path shape determination unit 32 determines that the path shape defined by the first program block and the second program block is a left corner. When the curvature κ is negative, the path shape determination unit 32 determines that the path shape defined by the first program block and the second program block is a right corner.

[0048] [Judgment Method (3)]

[0049] Figure 6 This is a diagram illustrating the method for determining the path shape. In the determination method (3), the path shape determination unit 32 determines the path shape based on the perpendicular bisector of the line segment connecting the start and end points of the first program block in the consecutive first program block and the second program block, and the perpendicular bisector of the line segment connecting the start and end points of the second program block.

[0050] Set the start point of the first program block to P0 and the end point to P1. Set the coordinates of the start point P0 to (x0, y0) and the coordinates of the end point P1 to (x1, y1). The start point of the next program block, the second program block, is the same as the end point P1 of the first program block. Set the end point of the second program block to P2. Set the coordinates of the end point P2 to (x2, y2).

[0051] The path shape determination unit 32 determines the perpendicular bisector L1 of the line segment connecting the start point P0 and the end point P1 of the first program block. The path shape determination unit 32 determines the perpendicular bisector L2 of the line segment connecting the start point P1 and the end point P2 of the second program block. The perpendicular bisector L1 and the perpendicular bisector L2 can be expressed by the following formulas.

[0052] [Formula 3]

[0053] L1:a1·x+b1·y+c1=0…(3)

[0054] [Formula 4]

[0055] L2:a²·x+b²·y+c²=0…(4)

[0056] Using the coefficients a1 and b1 of the perpendicular bisector L1 and the coefficients a2 and b2 of the perpendicular bisector L2, the decision value J is calculated. The decision value J is calculated by the following formula.

[0057] [Formula 5]

[0058] J = a2·b1 - a1·b2…(5)

[0059] When the determination value J is 0, the path shape determination unit 32 determines that the path shape defined by the first program block and the second program block is a straight line. When the determination value J is positive, the path shape determination unit 32 determines that the path shape defined by the first program block and the second program block is a left corner. When the determination value J is negative, the path shape determination unit 32 determines that the path shape defined by the first program block and the second program block is a right corner.

[0060] When the path shape specified by the first and second program blocks is a left or right corner, the curvature κ is calculated using the following formula.

[0061] [Formula 6]

[0062]

[0063] In the above formula, xc and yc are the coordinates of the intersection point O of the perpendicular bisectors L1 and L2.

[0064] [Path Shape Determination]

[0065] Figure 7 This is a flowchart illustrating the path shape determination process performed in the control device 18. The wire electrical discharge machining (EDM) machine 10 repeatedly performs the path shape determination process at predetermined cycles during EDM. Hereinafter, the first program block refers to the program block in the machining program that will be processed next. The second program block refers to the program block that will be processed following the first program block.

[0066] In step S1, the minimal program block determination unit 30 determines whether the length of the path of the first program block is less than or equal to the diameter of the wire electrode 12. If the length of the path of the first program block is less than or equal to the diameter of the wire electrode 12, the process proceeds to step S2. If the length of the path of the first program block is longer than the diameter of the wire electrode 12, the path shape determination ends.

[0067] In step S2, the minimal program block determination unit 30 determines whether the length of the path of the second program block is less than or equal to the diameter of the wire electrode 12. If the length of the path of the second program block is less than or equal to the diameter of the wire electrode 12, the process proceeds to step S3. If the length of the path of the second program block is longer than the diameter of the wire electrode 12, the path shape determination ends.

[0068] In step S3, the path shape determination unit 32 determines the path shape defined by the first program block and the second program block. The path shape determination unit 32 determines whether the path shape is a straight line, a left corner, or a right corner. Then, the process proceeds to step S4.

[0069] In step S4, the path shape determination unit 32 determines whether the path shape defined by the first program block and the second program block is a straight line. If the path shape is a straight line, the path shape determination ends. If the path shape is not a straight line, the process proceeds to step S5.

[0070] In step S5, the bias direction acquisition unit 34 acquires the bias directions in the first program block and the second program block. Then, the process proceeds to step S6.

[0071] In step S6, the inner / outer corner determination unit 36 ​​determines whether the path shape defined by the first program block and the second program block is an inner corner or an outer corner. Then, the path shape determination ends.

[0072] The electrical discharge machining (EDM) control unit 38 adjusts the machining conditions based on the path shape determination result. Furthermore, if the path shape determination result is either an inner corner or an outer corner, the EDM control unit 38 adjusts the machining conditions based on the curvature of the path shape. Based on the adjusted machining conditions, the EDM control unit 38 outputs command values ​​to the machining power supply 20, the X-axis motor 22, the Y-axis motor 24, etc. This controls the EDM machining of the workpiece 14. In addition, the EDM control unit 38 can also adjust items other than the machining conditions based on the path shape determination result.

[0073] [Effects]

[0074] When the path shape is defined by multiple minima, the control device 18 may incorrectly determine the path shape defined by the multiple minima. If the path shape is incorrectly determined, the electrical discharge machining control unit 38 cannot properly adjust the machining conditions, and the accuracy of the machined surface of the workpiece 14 may deteriorate.

[0075] Therefore, in the control device 18 of this embodiment, the minimum program block determination unit 30 determines whether the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the wire electrode 12. If the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the wire electrode 12, the path shape determination unit 32 determines whether the path shape is a right-hand corner or a left-hand corner. The path shape determination unit 32 performs this determination based on the coordinates of three points determined by the start and end points of the two consecutive program blocks. The offset direction acquisition unit 34 acquires the offset direction from the machining program in the two consecutive program blocks. Then, if the path shape is determined to be a left-hand corner or a right-hand corner, the inner / outer corner determination unit 36 ​​determines whether it is an inner / outer corner based on the offset direction. The electrical discharge machining control unit 38 controls the electrical discharge machining based on the determination result of the inner / outer corner determination unit 36. Thus, in paths defined by multiple minimum program blocks with inner or outer corners, the accuracy of the machined surface of the workpiece 14 can be improved.

[0076] Furthermore, in the control device 18 of this embodiment, the path shape determination unit 32 determines the path shape based on the outer product of two vectors derived from two consecutive program blocks. These two vectors are a vector from the start point of one of the two consecutive program blocks toward the end point, and a vector from the start point of the other of the two consecutive program blocks toward the end point. Thus, the path shape defined by a plurality of minimal program blocks can be determined.

[0077] Furthermore, in the control device 18 of this embodiment, the path shape determination unit 32 determines the path shape based on a function that represents a line passing through three points determined by the start and end points of two consecutive program blocks. This function has a coefficient of three or fewer. Additionally, this function is capable of second differentiation. Therefore, the path shape defined by multiple minimal program blocks can be determined.

[0078] Furthermore, in the control device 18 of this embodiment, the path shape determination unit 32 determines the path shape based on the perpendicular bisector of the line segment connecting the start and end points of two consecutive program blocks. Specifically, the path shape determination unit 32 determines the path shape based on the coefficient of the formula representing the perpendicular bisector of the line segment connecting the start and end points of one of the two consecutive program blocks, and the coefficient of the formula representing the perpendicular bisector of the line segment connecting the start and end points of the other of the two consecutive program blocks. Thus, the path shape defined by multiple minima can be determined.

[0079] Furthermore, the present invention is not limited to the embodiments described above, and various structures can be adopted without departing from the spirit of the present invention.

[0080] [Invention obtained by means of embodiments]

[0081] The invention described below is an invention that can be grasped from the above embodiments.

[0082] A control device (18) for a wire electrical discharge machining (10) wherein the wire electrical discharge machining (10) moves a wire electrode (12) relative to a workpiece (14) according to a machining program with a defined program path, and applies a voltage between the wire electrode and the workpiece to perform electrical discharge machining on the workpiece, the control device (18) comprising: a minimum program block determination unit (30) that determines whether the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the wire electrode; and a path shape determination unit (32) that, when determining that the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the wire electrode, determines the path shape based on... Based on the coordinates of three points determined by the start and end points of two consecutive program blocks, it is determined whether the path shape defined by the two consecutive program blocks is a right corner bending to the right or a left corner bending to the left in the direction of travel of the wire electrode; the bias direction acquisition unit (34) acquires the bias direction in the two consecutive program blocks from the machining program; the inner and outer corner determination unit (36) determines whether it is an inner corner or an outer corner based on the bias direction when it is determined that the path shape is a left corner or a right corner; and the electrical discharge machining control unit (38) controls the electrical discharge machining based on the determination result of the inner and outer corner determination unit. Thus, in paths with inner or outer corners defined by multiple minima, the accuracy of the machined surface of the machined object can be improved.

[0083] In the control device of the aforementioned wire electrical discharge machine, the path shape determination unit determines the path shape based on the cross product of the vector from the start point to the end point of one of the two consecutive program blocks and the vector from the start point to the end point of the other of the two consecutive program blocks. This allows for the determination of the path shape defined by multiple minimal program blocks.

[0084] In the control device of the aforementioned wire electrical discharge machining (EDM) machine, the path shape determination unit determines the path shape based on the curvature derived from a function that represents a line passing through three points determined by the start and end points of two consecutive program blocks, and has a coefficient of three or fewer. This allows for the determination of the path shape defined by multiple minimal program blocks.

[0085] In the control device of the aforementioned wire electrical discharge machine, the function is a function that can be differentiated twice. Therefore, the path shape defined by multiple minimal program blocks can be determined.

[0086] In the control device of the aforementioned wire electrical discharge machine, the path shape determination unit determines the path shape based on the coefficients of the formula representing the perpendicular bisector of the line segment connecting the start and end points of one of the two consecutive program blocks, and the coefficients of the formula representing the perpendicular bisector of the line segment connecting the start and end points of the other of the two consecutive program blocks. This allows for the determination of the path shape defined by multiple minima.

[0087] A control method for a wire electrical discharge machining (EDM) machine, wherein the EDM machine moves a wire electrode relative to a workpiece according to a machining program with a defined program path, and applies a voltage between the wire electrode and the workpiece to perform EDM machining on the workpiece, the control method comprising the following steps: a minimum program block determination step, determining whether the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the wire electrode; and a path shape determination step, wherein when it is determined that the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the wire electrode, the method determines the path shape based on the length of the path defined by the two consecutive program blocks. The program program determines the coordinates of three points, including the start and end points of the program block, and then determines whether the path shape defined by two consecutive program blocks is a right-hand corner bending to the right or a left-hand corner bending to the left in the direction of travel of the wire electrode. The offset direction acquisition step obtains the offset direction from the machining program within two consecutive program blocks. The internal / external corner determination step, if the path shape is determined to be a left or right corner, determines whether it is an internal or external corner based on the offset direction. Finally, the electrical discharge machining control step controls the electrical discharge machining based on the determination result in the internal / external corner determination step. Therefore, in paths defined by multiple minima of program blocks with internal or external corners, the accuracy of the machined surface of the workpiece can be improved.

[0088] In the above-described control method for a wire electrical discharge machining (EDM) machine, the path shape determination step is performed by calculating the cross product of the vector from the start point to the end point of one of the two consecutive program blocks and the vector from the start point to the end point of the other of the two consecutive program blocks. This allows for the determination of the path shape defined by multiple minimal program blocks.

[0089] In the above-described control method for a wire electrical discharge machining (EDM) machine, the path shape determination step is based on the curvature derived from a function that represents a line passing through three points determined by the start and end points of two consecutive program blocks, and has a coefficient of three or fewer. This allows for the determination of the path shape defined by multiple minimal program blocks.

[0090] In the control method for the wire electrical discharge machining described above, the function is a function that can be differentiated twice. Therefore, the path shape defined by multiple minimal program blocks can be determined.

[0091] In the above-described control method for a wire electrical discharge machining (EDM) machine, in the path shape determination step, the path shape is determined based on the coefficients of the formula representing the perpendicular bisector of the line segment connecting the start and end points of one of two consecutive program blocks, and the coefficients of the formula representing the perpendicular bisector of the line segment connecting the start and end points of the other of two consecutive program blocks. This allows for the determination of the path shape defined by multiple minima.

[0092] Explanation of reference numerals in the attached figures

[0093] 10… wire electrical discharge machining

[0094] 12… wire electrodes

[0095] 14…Processed objects

[0096] 18…Control device

[0097] 30…Minimum Program Block Decision Section

[0098] 32…Path Shape Determination Unit

[0099] 34…Offset Direction Acquisition Unit

[0100] 36…Inner and outer corner determination section

[0101] 38…Electrical Discharge Machining Control Department.

Claims

1. A control device (18) for a wire electrical discharge machining (10), wherein the wire electrical discharge machining (10) moves a wire electrode (12) relative to a workpiece (14) according to a machining program with a predetermined program path, and applies a voltage between the wire electrode and the workpiece, thereby performing electrical discharge machining on the workpiece. Its features are, The control device (18) includes: The minimal program block determination unit (30) determines whether the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the line electrode. The path shape determination unit (32) determines whether the path shape defined by the two consecutive program blocks is a right corner that bends to the right or a left corner that bends to the left in the direction of travel of the line electrode when it determines that the length of the path defined by the two consecutive program blocks is less than the diameter of the line electrode, based on the coordinates of three points determined by the start and end points of the two consecutive program blocks. The bias direction acquisition unit (34) acquires the bias direction from two consecutive program blocks in the machining program; The inner and outer corner determination unit (36) determines whether the path shape is an inner corner or an outer corner based on the offset direction when it determines that the path shape is a left corner or a right corner. as well as The electrical discharge machining control unit (38) controls the electrical discharge machining based on the determination results of the inner and outer corner determination unit.

2. The control device for a wire electrical discharge machining machine according to claim 1, characterized in that, The path shape determination unit determines the path shape based on the cross product of the vector from the starting point to the ending point of one of the two consecutive program blocks and the vector from the starting point to the ending point of the other of the two consecutive program blocks.

3. The control device for a wire electrical discharge machining machine according to claim 1, characterized in that, The path shape determination unit determines the path shape based on the curvature obtained from the following function, which represents a line passing through three points determined by the start and end points of two consecutive program blocks, and has a coefficient of three or less.

4. The control device for a wire electrical discharge machining machine according to claim 3, characterized in that, The function is a function that can be differentiated twice.

5. The control device for a wire electrical discharge machining machine according to claim 1, characterized in that, The path shape determination unit determines the path shape based on the coefficients of the formula representing the perpendicular bisector of the line segment connecting the start and end points of one of the two consecutive program blocks, and the coefficients of the formula representing the perpendicular bisector of the line segment connecting the start and end points of the other of the two consecutive program blocks.

6. A control method for a wire electrical discharge machining (EDM) machine, wherein the EDM machine moves a wire electrode relative to a workpiece according to a predetermined machining program, and applies a voltage between the wire electrode and the workpiece, thereby performing electrical discharge machining on the workpiece. Its features are, The control method comprises the following steps: The minimal program block determination step determines whether the length of the path defined by two consecutive program blocks is less than or equal to the diameter of the line electrode. In the path shape determination step, when it is determined that the length of the path defined by the two consecutive program blocks is less than the diameter of the line electrode, the path shape defined by the two consecutive program blocks is determined based on the coordinates of three points determined by the start and end points of the two consecutive program blocks. The determination is made as to whether the path shape defined by the two consecutive program blocks is a right corner that bends to the right in the direction of travel of the line electrode or a left corner that bends to the left in the direction of travel. The offset direction acquisition step involves obtaining the offset direction from two consecutive program blocks in the machining program; The inner and outer corner determination step involves determining whether an inner or outer corner is determined based on the offset direction if the path shape is determined to be a left corner or a right corner. as well as The electrical discharge machining control step controls the electrical discharge machining based on the determination results in the inner and outer corner determination step.

7. The control method for a wire electrical discharge machining machine according to claim 6, characterized in that, In the path shape determination step, the path shape is determined by the cross product of the vector from the starting point to the ending point of one of the two consecutive program blocks and the vector from the starting point to the ending point of the other of the two consecutive program blocks.

8. The control method for a wire electrical discharge machining machine according to claim 6, characterized in that, In the path shape determination step, the path shape is determined based on the curvature obtained from the following function, which represents a line passing through three points determined by the start and end points of two consecutive program blocks, and has a coefficient of three or less.

9. The control method for a wire electrical discharge machining machine according to claim 8, characterized in that, The function is a function that can be differentiated twice.

10. The control method for a wire electrical discharge machining machine according to claim 6, characterized in that, In the path shape determination step, the path shape is determined based on the coefficients of the formula representing the perpendicular bisector of the line segment connecting the start and end points of one of the two consecutive program blocks, and the coefficients of the formula representing the perpendicular bisector of the line segment connecting the start and end points of the other of the two consecutive program blocks.

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