DE112018007560B4 - Wire EDM machine and straightness calculation method - Google Patents

Abstract

Wire erosion machine (100), which applies a voltage between a wire electrode (1) and the workpiece (W) to process a workpiece (W), the wire erosion machine (100) having: a wire adjustment unit (102) to adjust the alignment of the wire electrode (1 ) to change in relation to the workpiece (W); anda contact detection unit (103) for detecting whether the wire electrode (1) and the workpiece (W) are in contact with each other; characterized by a straightness measuring unit (106) to measure a straightness (ΔD) of a machined surface (Ws) of the workpiece (W) based on the orientation of the wire electrode (1) with respect to the workpiece (W) upon detecting a contact between the wire electrode (1 ) and the workpiece (W) through the contact detection unit (103).

Description

Area

The present invention relates to a wire EDM machine in which a voltage is applied between a wire electrode and the workpiece to machine a workpiece, and a straightness calculation method.

background

A wire EDM machine uses electric energy from a discharge phenomenon that occurs when a wire electrode is placed near a workpiece while a machining voltage is applied between the wire electrode and the workpiece, thereby machining the workpiece. Since the machining accuracy depends on the machining conditions including the machining voltage, the machining conditions are set so that the determined machining accuracy corresponds to the desired machining accuracy. An example of a criterion for evaluating machining accuracy is the straightness of the machined surface. Straightness reflects the degree of deviation from the correct position of the machined surface. An example of a method for measuring straightness is using a micrometer. However, using a micrometer requires that the workpiece be removed from the wire EDM machine. However, considering that machining accuracy is often determined repeatedly, it would be desirable to be able to measure the straightness of a machined surface while the workpiece is attached to the wire EDM machine.

In the JP S60- 85 829 A A wire EDM machine is disclosed which includes a measuring device with a stylus. At the in the JP S60- 85 829 A In the disclosed wire EDM machine, to measure the straightness of the machined surface, the tip of the stylus is brought into contact with the machined surface while the workpiece is attached to the wire EDM machine.

Features of the preamble of claim 1 are from the document DE 42 28 329 A1 and the document DE 11 2015 001 760 T5 known.

Short description

Technical problem

However, in the conventional method described above, a special stylus, which is not used in electrical discharge machining, is used to measure the straightness of the machined surface. For this purpose, the wire EDM machine must have a measuring device with a stylus and a drive unit for moving the stylus. This presents a problem in that the use of a stylus increases the size and cost of the apparatus and, if the machined surface to be measured is in a slot, a stylus with a width greater than the width of the slot does not can be inserted into the slot, making measurement impossible.

The present invention arose in view of the above, and an object of the present invention is to provide a wire EDM machine in which an increase in the size of the device and an increase in the cost are reduced or eliminated and furthermore the straightness of a machined surface can also be measured , if the end surface to be measured lies in a slot.

Solution to the problem

To solve the above-mentioned problem and to fulfill the task, a wire EDM machine according to one aspect of the present invention is a wire EDM machine in which a voltage is applied between a wire electrode and the workpiece to machine a workpiece. The wire EDM machine includes: a wire adjusting unit for changing the orientation of the wire electrode with respect to the workpiece; a contact detection unit for detecting whether the wire electrode and the workpiece are in contact with each other; and a straightness measuring unit for obtaining the straightness of a machined surface of the workpiece based on an orientation of the wire electrode with respect to the workpiece upon detecting a contact between the wire electrode and the workpiece using the contact detection unit.

Advantageous effects of the invention

A wire EDM machine according to the present invention offers the advantage that a wire EDM machine can be specified in which an increase in the size of the apparatus and an increase in costs can be reduced or prevented and the straightness of a machined surface can be measured even if the end surface to be measured is in one slot is located.

Short description of the characters

• 1 Fig. 2 is a diagram illustrating a configuration of a wire EDM machine according to an embodiment of the present invention.
• 2 shows a diagram to illustrate an example of a hardware configuration of the in 1 control device shown.
• 3 shows a representation to illustrate the functional configuration of the in 1 shown wire EDM machine.
• 4 shows an illustrative representation of specification values for input into the in 3 shown specifications input unit.
• 5 1 is a diagram illustrating a procedure for changing the relative position of the wire electrode with respect to the workpiece, which is shown in FIG 1 shown wire EDM machine is carried out.
• 6 shows a representation to illustrate the wire electrode with one of the in 3 angle adjustment unit shown.
• 7 shows a diagram to illustrate a procedure for adjusting the degree of bending of the wire electrode, which is provided by the in 1 shown wire EDM machine is carried out.
• 8th 1 is a diagram illustrating a procedure for adjusting the degree of bending of the wire electrode by adjusting the tension of the wire electrode, which is determined by the in 3 shown bend adjustment unit is carried out.
• 9 is a diagram illustrating a procedure for adjusting the degree of bending of the wire electrode by applying a voltage between the wire electrode and the workpiece, which is determined by the in 3 shown bend adjustment unit is carried out.
• 10 shows a diagram to illustrate a procedure for adjusting the degree of bending of the wire electrode by mechanically shaking the wire electrode, which is carried out by the in 3 shown bend adjustment unit is carried out.
• 11 shows a flowchart illustrating a procedure for creating a machining condition using the in 1 shown wire EDM machine.
• 12 shows a flowchart illustrating the details of step S103 of 11 .
• 13 shows a diagram to illustrate the position of the machined surface when the machined surface has a concave shape.
• 14 shows a diagram to illustrate the position of the machined surface when the machined surface has a convex shape.
• 15 shows a representation to illustrate the step S202 of 12 measured position if the machined surface has a concave shape.
• 16 shows a representation to illustrate the step S202 of 12 measured position if the machined surface has a convex shape.
• 17 shows a representation to describe the functionality of the in 3 straightness measurement unit shown.
• 18 shows an enlarged view of area B of 17 .
• 19 shows an illustrative representation of one of the in 1 wire EDM machine shown to maintain the straightness in the case where the machined surface has a concave shape.

Description of an embodiment

A wire EDM machine and a straightness calculation method according to an embodiment of the present invention will be described in detail below with reference to the figures. It should be noted that the exemplary embodiments are not intended to limit the scope of this invention.

Embodiment

1 12 shows a diagram illustrating the configuration of a wire EDM machine 100 according to an embodiment of the present invention. The wire EDM machine 100 can apply a machining voltage between a wire electrode 1 and a workpiece W for machining a workpiece W. The wire EDM machine 100 can further measure the straightness ΔD of a machined surface Ws using the wire electrode 1 and adjust the machining conditions using the measured straightness ΔD. The straightness ΔD represents the degree of deviation from an intended position of the machined surface Ws.

The wire EDM machine 100 includes a table 11 for holding the workpiece W, an upper machining head 12 and a lower machining head 13 for holding the wire electrode 1, a power supply 14 for applying a machining voltage between the wire electrode 1 and the workpiece W, and a contact detection scarf device 15, which detects contact between the wire electrode 1 and the workpiece W.

The table 11 is made of an electrically conductive material and has an opening formed in the central part of the table 11. The wire electrode 1 disposed between the upper processing head 12 and the lower processing head 13 passes through the opening of the table 11, and the wire electrode 1 can move in the area where the opening is formed. The workpiece W is placed on the surface of the table 11. The surface of the table 11 for placing the workpiece W is hereinafter referred to as the table surface 11a.

The power supply 14 is electrically connected to the table 11 and the upper processing head 12, and a voltage can be applied between the table 11 and the upper processing head 12, whereby a voltage can be applied between the workpiece W and the wire electrode 1. The contact detection circuit 15 is electrically connected to the wire electrode 1 extending inside the upper processing head 12 and to the table 11.

By applying a voltage using the power supply 14 while the work W is on the table 11, a voltage is applied between the wire electrode 1 and the work W.

The contact detection circuit 15 can detect a contact between the wire electrode 1 and the workpiece W by short-circuiting the voltage between the wire electrode 1 and the workpiece W when the wire electrode 1 comes into contact with the workpiece W. More specifically, the contact detection circuit 15 applies a potential difference between the wire electrode 1 and the workpiece W and measures the potential difference between the wire electrode 1 and the workpiece W. The potential difference applied between the wire electrode 1 and the workpiece W is so small that no electric discharge occurs between the wire electrode 1 and the workpiece W Wire electrode 1 and the workpiece W is caused. The contact detection circuit 15 detects a change in the potential difference between the wire electrode 1 and the workpiece W and can thereby detect a change in the potential difference, i.e. H. detect an electrical contact of the wire electrode 1 with the workpiece W.

The wire EDM machine 100 further includes an -Motor (not shown in each case) to move the upper processing head 12. The movement of the upper machining head 12 by the U-axis motor and the V-axis motor causes a change in the inclination of the wire electrode 1 between the upper machining head 12 and the lower machining head 13. The wire EDM machine 100 further includes one above the upper machining head 12 Main tension roller 20 and a main tension motor 21 which rotates the main tension roller 20. The rotation of the main tension roller 20 by the main tension motor 21 causes the wire electrode 1 to unwind, which allows the tension of the wire electrode 1 to be adjusted.

The wire EDM machine 100 includes a control device 22. The control device 22 is a device that controls the wire EDM machine 100, also referred to as a numerical control device. It is noted that 1 only the connection between the control device 22 and the contact detection circuit 15 is illustrated, but the control device 22 each gives an instruction to the power supply 14, the contact detection circuit 15, the X-axis motor, the Y-axis motor, the U-axis motor, the V-axis motor and the main tension motor 21 can give. In this way, the control device 22 can control the Reference to the table 11 is changed for inclined machining.

The control device 22 can cause the wire EDM machine 100 to perform a spark erosion process through various instructions. If the wire electrode 1 is placed near the workpiece W while the machining voltage is applied between the wire electrode 1 and the workpiece W, an electric flashover occurs and an electric discharge occurs. The occurrence of an electric discharge creates an arc column between the wire electrode 1 and the workpiece W, which then causes a high density arc current to flow. The temperature of the workpiece W thereby rises, causing the workpiece W to melt, which in turn causes an evaporation explosion of surrounding water. This results in the melted portion being blown off. The wire EDM machine 100 processes the workpiece W taking advantage of this phenomenon.

The magnitude of an arc current flowing between the wire electrode 1 and the workpiece W affects the processing speed, the surface roughness and the machining accuracy. A higher arc current generally leads to a higher machining speed, but also to greater surface roughness and lower machining accuracy. Therefore, electrical discharge machining with the wire EDM machine 100 is generally performed in the form of multiple machining processes, where the level of the arc current is adjusted by changing electrical parameters such as the machining voltage. The processing types can be divided into three groups: pre-processing, semi-finished processing and finished processing. Pre-machining is a process of producing a rough shape of the workpiece using a relatively high current. Semi-finishing is a process of increasing the accuracy of the shape formed in pre-processing, using a current lower than the current in pre-processing. Semi-finished machining requires a balance between low surface roughness and high machining speed. Finishing is a process for obtaining a low surface roughness of the machined surface Ws using a current lower than the current in semi-finishing. Lower surface roughness is important in finishing. The electrical discharge machining with the wire EDM machine 100 is often carried out in such a way that the pre-machining and the semi-finished machining are each carried out once before the final machining is repeated until a desired surface roughness is achieved. It is noted that the number of times the pre-processing, semi-finished processing and final processing are performed is not limited to the times mentioned in the above example but depends on the user's requirements.

In addition, the wire EDM machine 100 monitors the detection result of the contact detection circuit 15 while changing the orientation of the wire electrode 1 with respect to the workpiece W, thereby detecting the orientation of the wire electrode 1 with respect to the workpiece W upon contact of the wire electrode 1 with the workpiece W can. The wire EDM machine 100 measures the straightness ΔD of the machined surface Ws based on the orientation of the wire electrode 1 with respect to the workpiece W when the wire electrode 1 comes into contact with the workpiece W.

2 shows a diagram to illustrate an example of a hardware configuration of the in 1 control device 22 shown. The control device 22 comprises a processor 31, a memory 32, an input device 33 and an output device 34. The processor 31 is a central processing unit (CPU), which is also called a central processing unit, processing unit, computing unit, microprocessor, Microcomputer, digital signal processor (DSP) and the like. The memory 32 is, for example, a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read-only memory (ROM), a flash memory, an erasable programmable ROM (EPROM), and an electrically erasable programmable ROM (EEPROM) (registered trademark); a magnetic disk, a floppy disk, an optical disk, a compact disk, a MiniDisc, a digital versatile disc (DVD), or the like.

The input device 33 is a touch panel, a keyboard, a mouse, a trackball or combinations thereof. The output device 34 is a display that displays a display image or the like.

3 shows a representation to illustrate the functional configuration of the in 1 shown wire EDM machine 100. The wire EDM machine 100 includes a specifications input unit 101, a wire adjusting unit 102, a contact detection unit 103, a position detection unit 104 and a calculation control unit 105. The calculation control unit 105 includes a straightness measuring unit 106 and a machining condition setting unit 107. It is noted that 3 Components necessary for describing features of the invention according to the present embodiment and functional components of the wire EDM machine 100 are illustrated, with the description of functions for performing electrical discharge machining being omitted here.

The wire EDM machine 100 has a straightness measuring function for measuring the straightness ΔD of the machined surface Ws by monitoring a contact between the wire electrode 1 and the workpiece W while changing the orientation of the wire electrode 1 with respect to the workpiece W. The wire EDM processing can occur due to a vibration of the Wire electrode 1, a high processing speed and/or the like produce a concave shape that is concave in a central region relative to a peripheral region of the machined surface Ws, or a convex shape that is concave in a central region relative to a peripheral region of the machined surface Ws is convex. In these cases, the machined surface Ws deviates from the intended surface, thereby reducing the machining accuracy.

Conventionally, the machining conditions are set, and the workpiece W is then removed from the wire EDM machine to manually measure the straightness ΔD with a micrometer every time the electrical discharge machining has been performed with the set machining conditions. In addition, if there is a measuring device that measures the straightness ΔD with a stylus, the straightness ΔD of the machined surface Ws can be measured while the workpiece W is attached to the wire EDM machine; however, this increases the size of the apparatus and the cost, and moreover, the machined area Ws in a slot may lead to a situation in which the stylus cannot be inserted into the slot, so that measurement of the straightness ΔD is not possible. In contrast, the wire EDM machine 100 according to the present embodiment uses the straightness measurement function to repeatedly set the machining conditions, perform the electrical discharge machining process using the set machining conditions, and measure the straightness ΔD. In this way, automatic determination of the machining conditions for forming the machined surface Ws with a desired straightness ΔD can be carried out without manual operation. The straightness measurement function can also be used to adjust the machining conditions during the repetition of electrical discharge machining.

The specification input unit 101 receives input of specification values required for applying the proposed straightness measurement function. The specification input unit 101 is implemented in the processor 31 of the control device 22 by reading and executing a computer program stored in the memory 32 using the input device 33 and the output device 34. The specification input unit 101 causes the output device 34 to display an input display image for inputting various specification values, and stores the input specification values when the user inputs the specification values on the input display image using the input device 33.

4 shows an illustrative representation of specification values for input into the in 3 shown specification input unit 101. The specification values to be input into the specification input unit 101 include a thickness Hw of the workpiece W; a distance Zd1 along the Z-axis direction between an upper surface Wa of the workpiece W and a holding unit 41 that holds the wire electrode 1; and a distance Zd2 along the Z-axis direction between a lower surface Wb of the workpiece W and a holding unit 42 that also holds the wire electrode 1. The thickness Hw is a dimension of the plate-shaped workpiece W in the thickness direction. As in 1 and 4 As shown, the Z axis is perpendicular to the into the wire EDM machine 100.

The wire adjusting unit 102 is controlled by the calculation control unit 105 to change the orientation of the wire electrode 1 with respect to the workpiece W. Changing the orientation of the wire electrode 1 with respect to the workpiece W means, as the term is used herein, adjusting at least one of the following quantities: the relative position of the wire electrode 1 with respect to the workpiece W, the angle of the wire electrode 1 with respect to on the workpiece W and the bending degree of the wire electrode 1. The wire adjusting unit 102 further includes an angle adjusting unit 102a that tilts the wire electrode 1 with respect to the direction perpendicular to the table surface 11a, and a bending adjusting unit 102b that changes the bending degree of the wire electrode 1.

More specifically, the wire adjusting unit 102 can horizontally move the upper processing head 12 and the lower processing head 13 together to change the relative position of the wire electrode 1 with respect to the workpiece W. In this case, the wire alignment unit 102 is configured using the X-axis motor and the Y-axis motor. 5 Fig. 12 is a diagram illustrating the procedure for changing the relative position of the wire electrode with respect to the workpiece, which is shown in Fig 1 shown wire EDM machine 100 is carried out. The wire adjusting unit 102 can move the table 11 horizontally until the wire electrode 1 comes into contact with the machined surface Ws of the workpiece W, with the wire electrode 1 being held perpendicular to the table surface 11a.

The angle adjusting unit 102a of the wire adjusting unit 102 can also move the upper processing head 12 horizontally to change an angle θ of the wire electrode 1 with respect to the table surface 11a. In this case, the wire alignment unit 102 is configured with the U-axis motor and/or the V-axis motor. 6 shows a representation to illustrate the wire electrode 1 with one of the in 3 shown angle adjustment unit 102a set angle θ. When the angle θ has not been adjusted by the angle adjusting unit 102a, the angle θ is 90 degrees and the wire electrode 1 is perpendicular to the table surface 11a, which is the surface for placing the workpiece W. Therefore, when the angle θ has been set, the wire electrode 1 is inclined with respect to the direction perpendicular to the table surface 11a, which is the surface for placing the workpiece W, that is, the angle θ is not equal to 0 or 90. 6 illustrates a situation in which the angle adjustment unit 102a has moved the upper processing head 12 in the direction of the U-axis by a travel distance Lu. Due to the translational movement of the upper processing head 12 caused by the angle adjustment unit 102a, the distance Hz in the direction of the Z axis between the holder unit 41 and the holder unit 42 is kept constant, whereas the length of the wire electrode 1 between the holder unit 41 and the holder unit 42 is changed.

In addition, the bend adjusting unit 102b of the wire adjusting unit 102 can cause a bend in the middle part of the wire electrode 1 between the holding units 41 and 42 and also adjust the bending degree L. 7 shows a representation to illustrate the procedure for setting the degree of bending L of the wire electrode 1, which is from the in 1 shown wire EDM machine 100 is carried out. When the machined surface Ws of the workpiece W has a concave shape, by adjusting the bending degree L and detecting a contact position between the wire electrode 1 and the workpiece W, the straightness ΔD can be obtained. The bend adjusting unit 102b can adjust the bending degree L of the wire electrode 1 by one of three methods. The three methods described below include vibrating the wire electrode 1 to control the bending degree L, in which case the vibration width of the wire electrode 1 corresponds to the bending degree L.

A first method for adjusting the bending degree L is to adjust the tension of the wire electrode 1. In this case, the bend adjusting unit 102b is configured with the main tension motor 21 and the main tension roller 20. 8th shows a diagram to illustrate the procedure for adjusting the degree of bending L of the wire electrode 1 by adjusting the tension of the wire electrode 1 using the in 3 shown bend adjustment unit 102b. The wire EDM machine 100 includes a roller for unwinding the wire electrode 1, wherein the wire electrode 1 can be kept in motion by continuously unwinding the wire electrode 1. The bend adjusting unit 102b of the wire EDM machine 100 adjusts the bending degree L while the wire electrode 1 is moved further. During the movement of the wire electrode 1, displacement due to the rotation of the roller for unwinding the wire electrode 1 or displacement due to other disturbances produces vibration of the wire electrode 1. Actual measurement with a laser displacement meter has shown that the wire electrode 1, although depending on the condition of the Wire EDM machine 100, with a width of a few tens of micrometers oscillates. It was also confirmed that the oscillation width, that is, the bending degree L, changes with each adjustment of the tension of the wire electrode 1. The relationship between the tension and the degree of bending L depends on the type of wire EDM machine 100, the length of the wire electrode 1, the thickness of the wire electrode 1 and the like. Therefore, measurement data must be obtained in advance. The bend adjusting unit 102b adjusts the tension of the wire electrode 1 based on the measurement data to reduce the tension during measurement compared to the tension during the machining process, thereby allowing the wire electrode 1 to come into contact with the central part of the machined surface Ws.

A second method for adjusting the bending degree L is to apply a voltage between the wire electrode 1 and the workpiece W. In this case, the bending adjustment unit 102b is configured using a power supply included in the contact detection circuit 15. 9 1 shows a diagram illustrating the procedure for adjusting the bending degree L of the wire electrode by applying a voltage between the wire electrode 1 and the workpiece W, which is determined by the in 3 shown bend adjustment unit 102b is carried out. 9 illustrates a case where a pulse voltage is applied between the wire electrode 1 and the workpiece W to control the electrostatic attraction and thereby cause the wire electrode 1 to vibrate. However, the present embodiment is not limited to this example; instead, a DC voltage may be applied between the wire electrode 1 and the workpiece W to cause the wire electrode 1 to bend. It is noted that the voltage used in this operation is lower than the machining voltage for use in the electrical discharge machining performed by the wire EDM machine 100.

A third method for adjusting the degree of bending L is to mechanically shake the wire electrode 1 to cause the wire electrode 1 to vibrate. In this case, the bend adjustment unit 102b is configured using the X-axis motor and/or Y-axis motor to move the upper processing head 12 and the lower processing head 13 together. 10 shows a diagram to illustrate the procedure for adjusting the Bie straight L of the wire electrode 1 by mechanically shaking the wire electrode 1 using the in 3 shown bend adjustment unit 102b. Driving the X-axis motor and/or Y-axis motor causes the holding units 41 and 42 of the wire electrode 1 to move, whereby the wire electrode 1 can be shaken. The above three methods can be used in combination. Using the three methods in combination can result in an oscillation width that is greater than the oscillation width achieved using just one of the methods. Note that the vibration width is the bending degree L when vibration of the wire electrode 1 is caused.

Returning to the description of 3 The contact detection unit 103 detects a contact between the wire electrode 1 and the workpiece W. The contact detection unit 103 is configured using the contact detection circuit 15. Upon detecting a contact between the wire electrode 1 and the workpiece W, the contact detection unit 103 outputs a detection signal indicating detection of a contact to the calculation control unit 105. The contact detection unit 103 is configured using the contact detection circuit 15. The detection signal output from the contact detection unit 103 is input to the position detection unit 104 via the calculation control unit 105.

The position detection unit 104 is configured using the contact detection circuit 15 and detects the position of the holding unit(s) 41 and/or 42 upon contact of the wire electrode 1 with the workpiece W. More specifically, the position detection unit 104 may detect the position of the holding unit(s) 41 and/or 42 on the For example, when the wire adjusting unit 102 has horizontally moved the upper processing head 12 and the lower processing head 13 together, the position detection unit 104 can determine the position of the holder unit(s) 41 and/or 42 based on the control amounts of the X-axis motor and the Y-axis -Determine the motor that is provided until the wire electrode 1 comes into contact with the workpiece W.

When the angle adjusting unit 102a has set the angle θ, the position detecting unit 104 can obtain the position of the holder unit(s) 41 and/or 42 based on the control amounts of the U-axis motor and the V-axis motor provided until the wire electrode 1 comes into contact with the workpiece W. When the bend adjusting unit 102b has adjusted the bending degree L of the wire electrode 1, the position of the holding unit(s) 41 and/or 42 can be obtained depending on the method of adjusting the bending degree L based on the control amount. When the bend adjusting unit 102b adjusts the bending degree L of the wire electrode 1 by adjusting the tension of the wire electrode 1, the control amount includes the control amount of the main tension motor 21. When the bend adjusting unit 102b adjusts the bending degree L of the wire electrode 1 by applying a voltage between the wire electrode 1 and the workpiece W sets, the control amount includes the characteristic of the voltage applied between the wire electrode 1 and the workpiece W. When the bend adjusting unit 102b adjusts the bending degree L of the wire electrode 1 by mechanically shaking the wire electrode 1, the control amount includes the control amounts of the X-axis motor and the Y-axis motor. The position detection unit 104 outputs the detected position to the calculation control unit 105.

The calculation control unit 105 controls the wire EDM machine 100. The calculation control unit 105 is operated using the processor 31 and the memory 32 of the in 2 control device 22 shown is configured. The straightness measuring unit 106 can measure the straightness ΔD of the machined surface Ws of the workpiece W based on the specification values input from the specification input unit 101, the amount or amounts of control performed by the wire adjusting unit 102, the detection signal output from the contact detection unit 103, and that from the position detection unit 104 calculate the recorded position output.

The machining condition setting unit 107 sets the machining condition for the process to be executed next based on the straightness ΔD calculated by the straightness measuring unit 106. There are different options for the method of setting the machining condition. When the straightness ΔD is greater than or equal to a threshold value, for example, greater than or equal to 10 μm, the machining condition setting unit 107 can reduce an offset. Alternatively, if the straightness ΔD is less than a threshold value, an electrical parameter may be reduced. For example, one possible method is to learn the method of setting the machining condition for each range of straightness ΔD using machine learning methods and let the machining condition setting unit 107 set the machining condition based on the straightness ΔD using the learning result.

11 shows a flowchart illustrating the procedure for creating a machining condition using the in 1 shown wire EDM machine 100. In the following description, a case in which three-stage electrical discharge machining is performed will be described, but the present embodiment is not limited to such an example.

The calculation control unit 105 first sets a candidate for a first processing condition (step S101). The calculation control unit 105 then controls the wire EDM machine 100 using the first machining condition to perform the electrical discharge machining (step S102). After the electrical discharge machining, the calculation control unit 105 performs a measuring process for measuring the machining accuracy (step S103). The measuring process includes the calculation of the straightness ΔD, which is carried out by the straightness measuring unit 106. After the measurement process, the calculation control unit 105 determines whether the measurement result meets a criterion (step S104). If the measurement result does not meet the criterion (step S104: No), the machining condition setting unit 107 of the calculation control unit 105 changes the first machining condition based on the measurement result (step S105). After changing the first processing condition, the calculation control unit 105 returns to step S102 of the procedure.

If the measurement result meets the criterion (step S104: Yes), the calculation control unit 105 sets a candidate for a second processing condition (step S106). The calculation control unit 105 then controls the wire EDM machine 100 using the second machining condition to perform the electrical discharge machining (step S107). After the electrical discharge machining, the calculation control unit 105 performs the measuring process for measuring the machining accuracy (step S103). After the measurement process, the calculation control unit 105 determines whether the measurement result meets a criterion (step S108). If the measurement result does not meet the criterion (step S108: No), the machining condition setting unit 107 of the calculation control unit 105 changes the second machining condition based on the measurement result (step S109). After changing the second processing condition, the calculation control unit 105 returns to step S107 of the procedure.

If the measurement result meets the criterion (step S108: Yes), the calculation control unit 105 sets a candidate for a third processing condition (step S110). The calculation control unit 105 then controls the wire EDM machine 100 using the third machining condition to perform the electrical discharge machining (step S111). After the electrical discharge machining, the calculation control unit 105 performs the measuring process for measuring the machining accuracy (step S103). After the measurement process, the calculation control unit 105 determines whether the measurement result meets a criterion (step S112). If the measurement result does not meet the criterion (step S112: No), the machining condition setting unit 107 of the calculation control unit 105 changes the third machining condition based on the measurement result (step S113). After changing the third processing condition, the calculation control unit 105 returns to step S111 of the procedure. If the measurement result meets the criterion (step S112: Yes), the calculation control unit 105 ends the procedure.

12 shows a flowchart illustrating the details of step S103 of 11 . The straightness measuring unit 106 first moves the table 11 horizontally while holding the wire electrode 1 perpendicular to the table surface 11a, which is the surface for placing the workpiece W, and measures a position X1 of the machined surface, which is the position in which the wire electrode 1 is in contact with the workpiece W (step S201). 13 Fig. 12 is a diagram showing the position X1 of the machined surface when the machined surface Ws has a concave shape. When the machined surface Ws has a concave shape, the wire electrode 1 is in contact with areas that meet the upper surface Wa and the lower surface Wb of the workpiece W. 14 Fig. 12 is a diagram showing the position X1 of the machined surface when the machined surface Ws has a convex shape. When the machined surface Ws has a convex shape, the wire electrode 1 is in contact with the thickness-direction central portion of the workpiece W.

To get back on 12 to come, the straightness measuring unit 106 then changes the angle θ using the angle adjusting unit 102a and measures the position of the holding unit(s) 41 and/or 42 when the wire electrode 1 comes into contact with either the area in which the machined surface Ws of the workpiece W is on the upper surface Wa meets, or with the area where the machined surface Ws of the workpiece W meets the lower surface Wb (step S202). 15 shows a representation to illustrate the step S202 of 12 measured position X2 when the machined surface Ws has a concave shape. Measuring the position X2 of the holding unit 42 enables the calculation of a contact position X3, in which the wire electrode 1 and the workpiece W are in contact with each other, based on a calculation described later. When the machined surface Ws has a concave shape, the calculated contact position X3 coincides with the machined surface position X1. 16 shows a representation to illustrate the step S202 of 12 measured position X2 if the machined surface Ws has a convex shape. The measurement of the position X2 of the holder unit 42 enables calculation of the contact position When the machined surface Ws has a convex shape, the calculated contact position X3 does not coincide with the machined surface position X1. Accordingly, the relationship between the contact position X3 and the machined surface position X1 depends on the kind of shape of the machined surface Ws, so the shape of the machined surface Ws can be classified based on this relationship.

To get back on 12 , the straightness measuring unit 106 then changes the bending degree L using the bending adjusting unit 102b and measures the bending degree L when the wire electrode 1 comes into contact with the workpiece W (step S203).

$$\mathrm{\theta }={\text{tan}}^{-1}\left(\text{Hz}/\text{Lu}\right)$$

After the procedures of steps S201 to S203, the straightness measuring unit 106 classifies the shape of the machined surface Ws based on the position X1 of the machined surface, which is the measurement result of step S201, and the position X2 of the holding unit 42, which is is the measurement result of step S202 (step S204). 17 shows a representation to describe the functionality of the in 3 straightness measuring unit 106 shown. To classify the shape of the machined surface Ws, when the wire electrode 1 touches the workpiece W, the straightness measuring unit 106 first calculates the angle θ in step S202. The travel distance Lu is known based on the control amount of the holder unit 42, and the distance Hz in the Z-axis direction, which is constant, can be calculated using equation (1) below. Therefore, the angle θ can be obtained using equation (2) below. $$\text{Hz}=\text{Hw}+\text{<figure-callout id="1" label="Zd" filenames="DE112018007560B4\_0011.png,DE112018007560B4\_0012.png" state="{{state}}">Zd</figure-callout>}1+\text{Zd}2$$

$$\mathrm{\theta }={\text{tan}}^{-1}\left(\text{Hz}/\text{Lu}\right)$$

$$\text{b}=\text{Zd}2/\text{sin}\mathrm{\theta }$$

$$\text{a}=\text{bcos}\mathrm{\theta }$$

$$\text{a}=\text{Zd}2\cdot \text{cos}\mathrm{\theta }/\text{sin}\mathrm{\theta }$$

18 shows an enlarged view of area B of 17 . Since an unknown quantity b and the distance Zd2 satisfy equation (3) below, equation (3) can be expressed in the form of equation (4). Using the relationship of equation (5) satisfied by an unknown quantity a and by the unknown quantity b, the unknown quantity a can be expressed as equation (6) by substituting equation (4) into equation (5). . $$\text{Zd}2=\text{bsin}\mathrm{\theta }$$

$$\text{b}=\text{Zd}2/\text{sin}\mathrm{\theta }$$

$$\text{a}=\text{bcos}\mathrm{\theta }$$

$$\text{a}=\text{Zd}2\cdot \text{cos}\mathrm{\theta }/\text{sin}\mathrm{\theta }$$

Therefore, since the distance Zd2 is known, if the angle θ is obtained using the above formula (2), the unknown quantity a can be obtained. By obtaining the unknown quantity a, the contact position X3 can be determined. The straightness measuring unit 106 compares the contact position X3 with the position X1 of the machined surface. In this procedure, when the contact position X3 coincides with the position When the contact position X3 does not match the position X1 of the machined surface, the straightness measuring unit 106 may classify the machined surface Ws as convex.

The straightness measuring unit 106 then calculates the straightness ΔD based on the classification of the shape of the machined surface (step S205). The straightness measuring unit 106 can obtain the straightness ΔD depending on the classification of the shape of the machined surface using an applicable method of the defined calculation methods. Specifically, when the machined surface Ws has a convex shape, the straightness measuring unit 106 can calculate the straightness ΔD based on the measurement results of steps S201 and S202. 18 also illustrates the position of the machined surface X1 and the straightness ΔD. The straightness ΔD can be expressed by the following equation (7). The unknown quantity a can be obtained by the method described above, and the straightness ΔD can thus be obtained using the position X1 of the machined surface and the position X2 of the holding unit 42, which are the measurement results. $$\mathrm{\Delta }\text{D}=\left|\text{<figure-callout id="1" label="X" filenames="DE112018007560B4\_0011.png,DE112018007560B4\_0012.png" state="{{state}}">X</figure-callout>}1-\text{X}2\right|-\text{a}$$

Further, in the case that the machined surface Ws has a concave shape or is a flat surface, the straightness measuring unit 106 can obtain the straightness ΔD using the measurement results of steps S201 to S203. 19 shows an illustrative representation of one of the in 1 Wire EDM machine 100 shown to obtain the straightness in the case where the machined surface Ws has a concave shape. The straightness measuring unit 106 can obtain, as measurement results of step S203, the bending degree L and a position X4 of the support units 41 and 42 upon obtaining the bending degree L. The straightness ΔD is expressed in the form of equation (8) below using the bending degree L and the position X4 of the support units 41 and 42. $$\mathrm{\Delta }\text{D}=\text{L}-\left|\text{<figure-callout id="1" label="X" filenames="DE112018007560B4\_0011.png,DE112018007560B4\_0012.png" state="{{state}}">X</figure-callout>}1-\text{X}4\right|$$

As described above, according to the embodiment of the present invention, a wire EDM machine 100 in which voltage is applied between a wire electrode 1 and the workpiece W to machine a workpiece changes the orientation of the wire electrode 1, maintaining a straightness ΔD of a machined surface Ws Basis of the alignment of the wire electrode 1 is obtained upon contact between the wire electrode 1 and the workpiece W. The wire EDM machine 100 uses the wire electrode 1, which is a component used in machining the workpiece W, eliminating the need to add an additional component for measuring the straightness ΔD. This allows the straightness ΔD to be measured while the workpiece W is attached to the wire EDM machine 100, while reducing or preventing an increase in the size of the apparatus and the cost. Furthermore, the machined surface Ws may not be exposed to the outside but may be in a slot depending on the machined shape. In such a case, a measuring device using a stylus may face a situation where the slot is too narrow to allow the stylus to be inserted. In contrast, in the wire EDM machine 100, the slot is formed by the wire electrode 1, and therefore the slot has a width larger than the thickness of the wire electrode 1. Therefore, even if the machined surface is in the slot, the straightness can be maintained ΔD of the machined surface Ws can be measured.

As described above, the wire EDM machine 100 is capable of measuring the straightness ΔD of the machined surface Ws while the workpiece W is attached to the wire EDM machine 100. In this way the in 11 The workflow shown can be automated, in which the spark erosion machining, the measuring process and the setting of the machining status are repeated several times. This automation can eliminate the labor for generating the machining condition for electrical discharge machining and further enables appropriate setting of the machining condition regardless of the skill of the person operating the wire EDM machine 100.

Examples of methods for changing the orientation of the wire electrode 1 include changing the angle of the wire electrode 1 with respect to the workpiece W. When the machined surface Ws has a convex shape, the angle of the wire electrode 1 with respect to the workpiece W is changed, whereupon the position at which the machined surface Ws of the workpiece W is in contact with the upper surface Wa or with the lower surface Wb is measured. In this way, the straightness ΔD of the machined surface Ws can be measured.

Examples of methods for changing the orientation of the wire electrode 1 include changing the degree of bending L of the wire electrode 1. For example, if the wire electrode 1 is vibrated, this may result in a bending of the wire electrode 1. When the machined surface Ws has a concave shape, by bending the wire electrode 1, it is possible to measure the position X4 in contact with the central portion of the machined surface Ws which is concave with respect to the upper surface Wa and the lower surface Wb. The straightness ΔD of the machined surface Ws can be obtained using the position X4.

The configurations described in the above embodiment merely represent examples of various aspects of the present invention. The configurations may be combined with other known technologies, and some of the configurations may be omitted and/or modified without departing from the spirit of the present invention.

The above embodiment has been described along with the configuration of the wire EDM machine 100; however, the control device 22 included in the wire EDM machine 100 can provide the technology of the present embodiment alone. In addition, the technology of the present embodiment can also be implemented as a method for controlling the wire EDM machine 100, a computer program for controlling the wire EDM machine 100, and a storage medium for storing the controlling computer program.

Although an embodiment in which the wire EDM machine 100 moves the upper machining head 12 to adjust the angle of the wire electrode 1 with respect to the workpiece W has been described above, the present embodiment is not limited to this example. Instead, the lower processing head 13 can be moved to adjust the angle of the wire electrode 1 with respect to the workpiece W. Alternatively, both the upper processing head 12 and the lower processing head 13 can be moved to adjust the angle of the wire electrode 1 with respect to the workpiece W.

Although an embodiment in which the wire EDM machine 100 has an X-axis motor and a Y-axis motor for horizontally moving the upper machining head 12 and the lower machining head 13 together has been described above, the present embodiment is not based on this example limited. There may be an X-axis motor and a Y-axis motor for horizontal movement of the table 11. It is noted that in the case where the X-axis motor and the Y-axis motor move the table 11 horizontally, the bending adjustment unit 102b is unable to adjust the bending degree L according to the third method described above .

Although an embodiment has been described above in which the specification input unit 101 and the calculation control unit 105 mentioned in 3 are shown providing the functionality of the control device 22, the present embodiment is not limited to such an example. The functionality of the specification input unit 101 and the calculation control unit 105 may be implemented by a combination of a processor and memory different from the controller 22, and may also be implemented in a specialized processing circuit.

Reference symbol list

1

wire electrode;

11

Table;

11a

table surface;

12

upper processing head;

13

lower processing head;

14

power supply;

15

contact detection circuit;

20

main tension pulley;

21

main tension motor;

22

control device;

31

Processor;

32

Storage;

33

input device;

34

dispensing device;

41, 42

mounting unit;

100

wire EDM machine;

101

Specifications input unit;

102

wire adjustment unit;

102a

angle adjustment unit;

102b

bend adjustment unit;

103

contact detection unit;

104

position detection unit;

105

calculation control unit;

106

straightness measurement unit;

107

machining condition setting unit;

ΔD

straightness;

L

degree of bending;

W

Workpiece;

Wha

upper surface;

Wb

lower surface;

Ws

processed area.

Claims (13)

Wire erosion machine (100), which applies a voltage between a wire electrode (1) and the workpiece (W) to process a workpiece (W), the wire erosion machine (100) having: a wire adjustment unit (102) to adjust the alignment of the wire electrode (1 ) to change in relation to the workpiece (W); and a contact detection unit (103) for detecting whether the wire electrode (1) and the workpiece (W) are in contact with each other; characterized by a straightness measuring unit (106) for measuring a straightness (ΔD) of a machined surface (Ws) of the workpiece (W) based on the orientation of the wire electrode (1) with respect to the workpiece (W) when detecting a contact between the wire electrode ( 1) and the workpiece (W) through the contact detection unit (103). Wire EDM machine (100). Claim 1 , wherein the wire adjusting unit (102) comprises an angle adjusting unit (102a) for adjusting an angle of the wire electrode (1) with respect to the workpiece (W). Wire EDM machine (100). Claim 2 , wherein the angle adjusting unit (102a) adjusts the angle by changing a position of a holding unit (41, 42) that holds the wire electrode (1). Wire EDM machine (100). Claim 2 or 3 , wherein the straightness measuring unit (106) determines a shape of the machined surface (Ws) based on a position of the machined surface (Ws) which is measured when the wire electrode (1) is arranged perpendicular to a surface for placing the workpiece (W), and a position at which the wire electrode (1) is in contact with the workpiece (W) and which is measured after the angle is adjusted and the straightness (ΔD) is obtained using a calculation method defined for each classification. Wire EDM machine (100) according to one of the Claims 1 until 4 , wherein the wire adjustment unit (102) comprises a bend adjustment unit (102b) for adjusting a degree of bending (L) of the wire electrode (1). Wire EDM machine (100). Claim 5 , in which the bend adjusting unit (102b) adjusts the bending degree (L), which is the oscillation width of the wire electrode (1), by changing the voltage of the oscillating wire electrode (1). Wire EDM machine (100). Claim 5 or 6 , in which the bend adjusting unit (102b) adjusts the bending degree (L) by changing the voltage applied between the wire electrode (1) and the workpiece (W). Wire EDM machine (100). Claim 7 , in which the bending adjustment unit (102b) adjusts the degree of bending (L), which is the oscillation width of the wire electrode (1), by repeatedly applying a pulse voltage between the wire electrode (1) and the workpiece (W) to the wire electrode ( 1) to let it oscillate. Wire EDM machine (100). Claim 7 , in which the bend adjusting unit (102b) adjusts the degree of bending (L) by applying a DC voltage between the wire electrode (1) and the workpiece (W) to cause the wire electrode (1) to bend and adjusting the value of the applied DC voltage . Wire EDM machine (100) according to one of the Claims 5 until 9 , in which the bending adjustment unit (102b) adjusts the bending degree (L), which is the oscillation width of the wire electrode (1), by moving the holder unit (41, 42) that holds the wire electrode (1) to the wire electrode ( 1) to let it oscillate. Wire EDM machine (100) according to one of the Claims 1 until 10 , further comprising: a machining condition setting unit (107) for setting a machining condition based on the straightness (ΔD) calculated by the straightness measuring unit (106). Straightness calculation method for calculating the straightness (ΔD) of a machined surface (Ws) of a workpiece (W) using a wire EDM machine (100) which applies a voltage between a wire electrode (1) and the workpiece (W) to machine the workpiece (W). , where the straightness calculation method includes: a first measuring step for measuring a position in which the wire electrode (1) is in contact with the workpiece (W) when the wire electrode (1) is arranged perpendicular to a surface for placing the workpiece (W); a second measuring step of measuring a position where the wire electrode (1) is in contact with the workpiece (W) in a situation where the orientation of the wire electrode (1) with respect to the workpiece (W) has been changed; a classification step of classifying a shape of the machined surface (Ws) based on the measurement results of the first measurement step and the second measurement step; and a straightness calculation step for determining the straightness (ΔD) of the machined surface (Ws) based on the measurement results and the classification result. straightness calculation method Claim 12 , wherein the second measuring step is a step of measuring a position in which the Wire electrode (1) contacts the workpiece (W), and includes a step in which, in a situation in which the orientation is changed by changing the degree of bending (L) of the wire electrode (1), a position in which the wire electrode (1) is measured (1) the workpiece (W) is contacted.

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