JP6487497B2 - Wire electric discharge machine and wire electric discharge machining method - Google Patents

Description

  The present invention relates to a wire electric discharge machine and a wire electric discharge machining method having a core fixing function for fixing a core formed by electric discharge machining to a workpiece.

  2. Description of the Related Art Conventionally, various wire electric discharge machines that perform electric discharge machining on a workpiece by electric discharge generated between a wire electrode and the workpiece have been developed. For example, a so-called core fixing function is known that uses the phenomenon that the components of the wire electrode adhere to the workpiece during this discharge, and fixes the core to be formed to the base material of the workpiece ( Patent Document 1).

  Generally speaking, this core fixing function is extremely effective in processing of forming a large number of cores for one or a plurality of workpieces. This is because [1] roughing of the workpiece, [2] removal of the core, and [3] finishing of the workpiece can be performed collectively on a large number of cores, and the entire work is performed. This is because it is possible to improve the efficiency or automatic operation of the vehicle.

Japanese Patent No. 5426733

  When the fixing portion is formed in the gap of the machining groove using the above-described core fixing function, it is necessary to change the conditions (hereinafter, machining conditions) relating to electric discharge machining at the timing of switching the on / off operation of this function. However, abruptly changing the processing conditions may cause a decrease or disappearance of the discharge repulsive force acting on the wire electrode, and there may be no discharge gap between the wire electrode and the workpiece. As a result, there is a concern that the state in which the wire electrode is in partial and simultaneous contact with the workpiece and the fixed portion, that is, the short state of the wire electrode cannot be released.

  In addition, when the processing conditions are rapidly changed, instantaneous discharge or instantaneous short circuit easily occurs between the wire electrode and the fixed portion, and there is a concern that the wire electrode may be disconnected at a locally heated portion. In particular, when the wire electrode is disconnected, the fixed portion reduces the spatial margin in the machining groove and prevents the wire electrode from being connected or moved, making it difficult to resume electrical discharge machining from the interrupted machining position. Is also envisaged. As described above, there is a sufficient room for improvement regarding the control of the electric discharge machining under the transient state where the core fixing function is switched from on to off.

  The present invention has been made in order to solve the above-described problem, and it is possible to avoid unintentionally falling into a non-resumable state under a transient state in which the core fixing function is switched from on to off, An object of the present invention is to provide a wire electric discharge machine and a wire electric discharge machining method capable of suppressing unintended disconnection of a wire electrode.

  The wire electric discharge machine according to the first aspect of the present invention is configured to process the workpiece by generating an electric discharge between the wire electrode and the workpiece while relatively moving the wire electrode and the workpiece. A core fixing function for fixing the core formed by the electric discharge machining to the base material of the workpiece by applying electric discharge machining along the path and attaching and depositing the wire electrode component generated by the electric discharge machining A machining condition setting unit that sets machining conditions related to the electrical discharge machining in association with a plurality of sections on the machining path, and the machining condition setting unit sets the machining conditions for each section. An electric discharge machining control unit that controls the electric discharge machining according to machining conditions, and the machining condition setting unit can exhibit the core fixing function in the first section on the upstream side as the machining conditions A first machining condition is set, and a second machining condition in which a groove can be formed in the workpiece is set in the second zone on the downstream side, and is between the first zone and the second zone. In the intermediate section, intermediate machining conditions different from both the first machining condition and the second machining condition are set.

  Thus, in the intermediate section between the first section on the upstream side and the second section on the downstream side, intermediate processing conditions different from both the first processing condition and the second processing condition are set. It is possible to shift in a stepwise manner from the first machining condition to the second machining condition. That is, by changing the processing conditions in stages, the influence of the physical action on the wire electrode is reduced, and it is possible to prevent the wire electrode from approaching or coming into contact with the fixing part formed immediately before. Thereby, it is possible to avoid unintentionally falling into a state where the core fixing function cannot be resumed under a transient state where the core fixing function is switched from on to off, and it is possible to suppress unintentional disconnection of the wire electrode.

  In particular, in the case of a wire electric discharge machine having a core fixing function, the space formed in the processing groove is reduced by the formed fixing portion, and the wire electrode connection / movement is hindered. Appears more prominently.

  In the first aspect of the present invention, the start point of the intermediate section is upstream of the end position of the core fixing function, the end point of the intermediate section is at the end position of the core fixing function, The machining condition setting unit may set the intermediate machining condition in which the electric discharge machining is suppressed as compared with the first machining condition.

  Further, with respect to the first aspect of the present invention, the start point of the intermediate section is at the end position of the core fixing function, and the end point of the intermediate section is downstream of the end position of the core fixing function, The machining condition setting unit may set the intermediate machining condition in which the electric discharge machining is suppressed as compared with the second machining condition.

  In the first aspect of the invention, the start point of the intermediate section is upstream of the end position of the core fixing function, and the end point of the intermediate section is downstream of the end position of the core fixing function. The machining condition setting unit sets the intermediate machining condition in which the electric discharge machining is suppressed as compared with the first machining condition between the start point of the intermediate section and the end position of the core fixing function. The intermediate machining condition in which the electric discharge machining is suppressed as compared with the second machining condition may be set between the end position of the core fixing function and the end point of the intermediate section.

  Further, with respect to the first aspect of the present invention, the machining condition setting unit reduces an average discharge energy amount between the wire electrode and the workpiece as compared with the first machining condition, thereby processing the workpiece. Reduce the speed, decrease the fluid pressure of the working fluid, reduce the flow rate of the working fluid, decrease the tension of the wire electrode, increase the discharge gap distance between the wire electrode and the workpiece, or You may set the said intermediate processing conditions combining these.

  In the first aspect of the present invention, the machining condition setting unit narrows a pulse width of a discharge current supplied between the wire electrode and the workpiece as compared with the first machining condition, and The intermediate machining conditions with a relatively small average discharge energy amount may be set by reducing the peak current value of the current, increasing the pause time of the current pulse of the discharge current, or combining them.

  Further, with respect to the first aspect of the present invention, the machining condition setting unit reduces an average discharge energy amount between the wire electrode and the workpiece as compared with the second machining condition, thereby processing the workpiece. Reduce the speed, decrease the fluid pressure of the working fluid, reduce the flow rate of the working fluid, decrease the tension of the wire electrode, increase the discharge gap distance between the wire electrode and the workpiece, or You may set the said intermediate processing conditions combining these.

  In the first aspect of the present invention, the machining condition setting unit narrows a pulse width of a discharge current supplied between the wire electrode and the workpiece as compared with the second machining condition, and The intermediate machining conditions with a relatively small average discharge energy amount may be set by reducing the peak current value of the current, increasing the pause time of the current pulse of the discharge current, or combining them.

  In the first aspect of the present invention, the processing condition setting unit may set the intermediate processing conditions including execution of dwell processing.

  The wire electric discharge machine according to the second aspect of the present invention is configured to process the workpiece by generating an electric discharge between the wire electrode and the workpiece while relatively moving the wire electrode and the workpiece. A core fixing function for fixing the core formed by the electric discharge machining to the base material of the workpiece by applying electric discharge machining along the path and attaching and depositing the wire electrode component generated by the electric discharge machining A machining condition setting unit that sets machining conditions related to the electrical discharge machining in association with a plurality of sections on the machining path, and the machining condition setting unit sets the machining conditions for each section. An electric discharge machining control unit that controls the electric discharge machining according to machining conditions, and the machining condition setting unit can exhibit the core fixing function in the first section on the upstream side as the machining conditions A first machining condition is set, a second machining condition in which a groove can be formed in the workpiece is set in the second section on the downstream side, and the first machining is performed at the end position of the first section. Set execution of dwell processing according to conditions.

  As described above, since the execution of the dwell processing according to the first processing condition is set at the end position of the first section, the remaining processing region in the processing direction (forward direction) can be removed using this dwell processing. . That is, by increasing the discharge gap distance, it is possible to prevent the wire electrode from approaching or coming into contact with the fixed portion formed in the immediate vicinity. Thereby, it is possible to avoid unintentionally falling into a state where the core fixing function cannot be resumed under a transient state where the core fixing function is switched from on to off, and it is possible to suppress unintentional disconnection of the wire electrode.

  According to a third aspect of the present invention, there is provided a wire electric discharge machining method, in which an electric discharge is generated between the wire electrode and the workpiece while the wire electrode and the workpiece are relatively moved, thereby machining the workpiece. A core fixing function for fixing the core formed by the electric discharge machining to the base material of the workpiece by applying electric discharge machining along the path and attaching and depositing the wire electrode component generated by the electric discharge machining A setting step of setting each of the machining conditions related to the electric discharge machining in association with a plurality of sections on the machining path, and setting for each section in the setting process A control step of controlling the electric discharge machining in accordance with the processed conditions, and in the setting step, the core fixing function can be expressed in the first section on the upstream side as the processing conditions. The first machining condition is set, and in the second section on the downstream side, the second machining condition is set so that a groove can be formed on the workpiece, and the gap between the first section and the second section is set. In a certain intermediate section, an intermediate machining condition different from both the first machining condition and the second machining condition is set.

  According to the wire electric discharge machine and the wire electric discharge machining method according to the present invention, it is possible to avoid unintentionally falling into a non-resumable state under a transient state where the core fixing function is switched from on to off, Unintentional disconnection of the wire electrode can be suppressed.

It is a whole lineblock diagram of the wire electric discharge machine concerning this embodiment. FIG. 2A is a plan view of the workpiece with the core fixed thereto. 2B is a cross-sectional view taken along line IIB-IIB in FIG. 2A. It is a flowchart with which it uses for operation | movement description of the wire electric discharge machine shown in FIG. 4A to 4C are schematic explanatory diagrams relating to a control method of electric discharge machining. It is a time chart which shows the time change of processing conditions for controlling electric discharge processing shown in Drawing 4A. It is a flowchart for performing control of electric discharge machining corresponding to the time chart of FIG. It is a time chart which shows the time change of processing conditions for controlling electric discharge processing shown in Drawing 4B. It is a time chart which shows time change of processing conditions for controlling electric discharge processing shown in Drawing 4C. It is a time chart which shows the time change of processing conditions for controlling electric discharge processing shown in Drawing 4B. 10 is a flowchart for controlling electric discharge machining corresponding to the time chart of FIG. 9. FIG. 11A to FIG. 11C are schematic diagrams for explaining a conventional problem when the core fixing function is used. FIG. 12A to FIG. 12C are schematic diagrams for explaining the conventional problems when the core fixing function is used.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a wire electric discharge machine according to the present invention will be described with reference to the accompanying drawings by giving preferred embodiments in relation to a wire electric discharge machining method.

[Overall configuration of wire electric discharge machine 10]
FIG. 1 is an overall configuration diagram of a wire electric discharge machine 10 according to this embodiment. The wire electric discharge machine 10 is a machine that performs electric discharge machining along the machining path 50 (FIG. 2A) on the workpiece W (FIGS. 2A and 2B) by electric discharge generated between the wire electrode 12 and the workpiece W. It is a machine. The wire electric discharge machine 10 basically includes a machine main body 14, a machining liquid processing device 16, and a control device 18.

  The material of the wire electrode 12 is, for example, a metal material such as tungsten, copper alloy, or brass. On the other hand, the material of the workpiece W is, for example, an iron-based material or a super hard material. Here, the workpiece W is a component in which the core Pc is generated, for example, a punching die plate.

  The processing machine main body 14 includes a processing tank 20 capable of storing a processing liquid (not shown) used in electric discharge machining, and two die guides 22 arranged in positions facing each other in the processing tank 20, 24. Between the die guides 22, 24, a string-like wire electrode 12 extends in the height direction of the processing tank 20 and is connected.

  The processing machine body 14 further includes a supply system 26 that supplies the wire electrode 12 toward the upper die guide 22 and a recovery system 28 that recovers the wire electrode 12 from the lower die guide 24.

  The supply system 26 includes a wire bobbin 30 around which the wire electrode 12 is wound, a torque motor 31 that can apply torque to the wire bobbin 30, a brake shoe 32 that applies braking force to the wire electrode 12 by friction, A brake motor 33 capable of applying a brake torque to the brake shoe 32, a tension detector 34 for detecting the magnitude of the tension of the wire electrode 12, and an upper guide portion 35 including the above-described die guide 22 are provided.

  The collection system 28 includes a lower guide portion 36 including the above-described die guide 24, a guide roller 37 that guides the wire electrode 12 while changing the direction thereof, a pinch roller 38 and a feed roller 39 that can sandwich the wire electrode 12, A wire collection box 40 for collecting the wire electrode 12 conveyed by the pinch roller 38 and the feed roller 39.

  The workpiece W is placed on a table (not shown) in the processing tank 20. The processing machine body 14 can move the wire electrode 12 and the workpiece W relative to each other by moving at least one of the upper guide part 35 (lower guide part 36) and the table.

  The processing liquid processing apparatus 16 is an apparatus that manages the quality of the processing liquid (for example, water or oil) by removing the processing waste (sludge) generated in the processing tank 20 and adjusting the electrical resistivity and temperature. is there. The processing liquid processing apparatus 16 is configured to be able to adjust the flow pressure or flow rate of the processing liquid and to supply the processing liquid into the processing tank 20. Specifically, the machining fluid whose flow pressure and flow rate are adjusted is sprayed toward the wire electrode 12 in the machining tank 20 from a nozzle (not shown) provided in the upper guide portion 35 or the lower guide portion 36. Is done.

  The control device 18 is a device that controls electric discharge machining by the processing machine main body 14 and the machining liquid processing device 16. Specifically, the control device 18 functions as a machining condition setting unit 42 that sets machining conditions related to electric discharge machining, and an electric discharge machining control unit 44 that controls electric discharge machining.

  This machining condition means a combination of control parameters for specifying the control content of electric discharge machining, including the electrical or physical control condition of the wire electrode 12 and the injection condition of the machining liquid. “Fixed machining conditions” (first machining conditions), which will be described later, are machining conditions under which the fixing portions 56 and 57 (FIG. 2A) can be formed on the workpiece W by expressing the core fixing function. Further, the “normal processing conditions” (second processing conditions) are processing conditions under which the grooves 58 and 59 (FIG. 2A) can be formed in the workpiece W without exhibiting the core fixing function.

  The “core fixing function” means that the core Pc formed (see FIGS. 2A and 2B) is processed by utilizing the phenomenon that the components of the wire electrode 12 adhere to the workpiece W during discharge. It means the function of fixing to the base material Pb (see the figure) of the object W. Here, using the core fixing function of the wire electric discharge machine 10, [1] rough machining of the workpiece W, [2] removal of the core Pc, and [3] finish machining of the workpiece W, Are assumed to be performed sequentially.

[Shape characteristics of workpiece W]
FIG. 2A is a plan view of the workpiece W to which the core Pc is fixed. 2B is a cross-sectional view taken along line IIB-IIB in FIG. 2A.

  As shown in FIG. 2A, while moving the wire electrode 12 relative to the workpiece W so that the wire electrode 12 moves along the machining path 50 (illustrated by a broken line arrow) on the workpiece W, By generating an electric discharge between the wire electrode 12 and the workpiece W, a machining groove 52 having a substantially constant width is formed in the workpiece W. The machining groove 52 has, for example, a shape obtained by combining one line segment having one end point of the machining start hole 54 that is the starting point of the machining path 50 and one rectangle contacting the line segment at the other end point.

  One fixing portion 56, 57 made of an adhering material is formed at the midpoint position of the long side of the rectangle formed by the processing groove 52, respectively. By the fixing portions 56 and 57, the processing groove 52 is divided into two groove portions, more specifically, a substantially E-shaped groove portion 58 and a substantially C-shaped groove portion 59.

  The upstream end point (left end point in the figure) of the fixing portion 56 corresponds to the start position of the core fixing function (hereinafter, the fixing start position 61). The upstream end point (right end point in the figure) of the fixing portion 57 corresponds to the start position of the core fixing function (hereinafter, the fixing start position 62). The downstream end point (right end point in the figure) of the fixing portion 56 corresponds to the end position of the core fixing function (hereinafter, the fixing end position 63). The downstream end point (left end point in the figure) of the fixing portion 57 corresponds to the end position of the core fixing function (hereinafter, the fixing end position 64).

  As shown in FIG. 2B, the fixing portions 56 and 57 are each formed at a position close to the upper surface of the workpiece W. After the rough machining of the workpiece W is completed, the core Pc is formed from the upper side of the workpiece W using a hammer device provided in the upper guide portion 35 (FIG. 1) or a hammer attached to a robot hand (not shown). Knock it down. As described above, since the temporarily fixed core Pc can be easily removed at an arbitrary timing, the efficiency of the entire operation or the automatic operation is expected.

  The shape of the workpiece W is not limited to the example of FIG. 2A, and the shape of the machining path 50, the length, number or position of the fixing portions 56 and 57, or the size, number or position of the core Pc can be freely set. It may be changed.

<Operation of Wire Electric Discharge Machine 10>
The wire electric discharge machine 10 according to this embodiment is configured as described above. Next, the operation of the wire electric discharge machine 10 (mainly the control device 18) will be described with reference to the flowchart of FIG. The wire electric discharge machine 10 starts electric discharge machining on the workpiece W in accordance with execution of the machining program by the control device 18.

  In step S1 of FIG. 3, the machining condition setting unit 42 reads position information regarding a section (hereinafter, the current section) in which electric discharge machining is to be performed, and sets the current section. This position information includes, for example, coordinate values of feature points (start point, end point or relay point), a vector amount connecting two points, or an interpolation shape.

  In step S2, the machining condition setting unit 42 reads the control parameters corresponding to the current section set in step S1, and sets the machining conditions. For example, when the current section is a section in which the core fixing function is developed, “fixed processing condition” is set as the processing condition.

In step S3, the electric discharge machining control unit 44 performs in accordance with the set processing conditions in step S 2, the electric discharge machining control in the current interval set in step S 1. Thereby, the processing machine main body 14 and the machining liquid processing device 16 cooperate in accordance with a control signal from the electric discharge machining control unit 44.

  In step S4, the electric discharge machining control unit 44 determines whether or not the current position on the machining path 50 (hereinafter referred to as the current machining position) has reached the end point of the current section. If it is determined that it has not reached yet (step S4: NO), the process returns to step S3, and the electric discharge machining control unit 44 continues the electric discharge machining control. On the other hand, when it is determined that the end point has been reached (step S4: YES), the process proceeds to the next step (S5).

  In step S5, the electric discharge machining control unit 44 determines whether or not the electric discharge machining control in all the sections has been completed. If it is determined that the process has not been completed yet (step S5: NO), the process returns to step S1 and steps S1 to S4 are sequentially executed. That is, after the next section on the machining path 50 is set, electric discharge machining is controlled in that section.

  On the other hand, when it is determined that all the sections have been completed (step S5: YES), the electric discharge machining control unit 44 ends the electric discharge machining control for the workpiece W.

[Control method in this embodiment]
<Conventional problems>
By the way, when forming the fixing | fixed part 56 and 57 in the clearance gap between the process grooves 52 using a core fixing function, the following problem may arise.

  As shown in FIG. 11A, it is assumed that the workpiece W is subjected to electric discharge machining along the machining path 2 (illustrated by a broken line) with the machining start hole 1 as a starting point. In the example of this figure, it is assumed that the wire electrode 7 (FIG. 11B) has reached the current processing position 5 immediately after forming the substantially C-shaped groove portion 3 and one fixing portion 4.

  As shown in FIG. 11B, the wire electrode 7 is connected between the upper guide portion 6a and the lower guide portion 6b. The thicker the workpiece W is, the larger the amount of bending of the wire electrode 7 is, and the inner wall 8 of the workpiece W tends to bend toward the wire electrode 7 side accordingly. As a result, the discharge gap between the wire electrode 7 and the inner wall 8 and the separation gap between the wire electrode 7 and the fixed portion 4 are reduced.

  When forming the fixing portion 4 using the core fixing function, it is necessary to change the machining conditions at the timing of switching the on / off operation of this function. However, abruptly changing the processing conditions may cause some physical action on the wire electrode 7 (specifically, reduction or disappearance of the discharge repulsive force accompanying the stop of the power supply). The discharge gap that exists between the electrode 7 and the workpiece W may be lost. Therefore, when a short circuit is detected between the wire electrode 7 and the inner wall 8, retraction control may be performed to retract the wire electrode 7 by a predetermined distance in the direction opposite to the processing direction.

  However, in the example of FIG. 11C, when a short is detected at the current processing position 5, the retracted wire electrode 7 newly comes into contact with the fixed portion 4, and the short circuit with the workpiece W cannot be canceled yet. possible. Specifically, when D1 <D2 is satisfied, there is a concern that the state in which the wire electrode 7 is in partial and simultaneous contact with the workpiece W and the fixing portion 4, that is, the short state of the wire electrode 7 cannot be released. Here, the distance from the fixed portion 4 to the inner wall 8 is D1, and the maximum value of the amount of bending at the inner wall 8 is D2.

  As shown in FIG. 12A, it is assumed that the workpiece W is subjected to electric discharge machining along the machining path 2 (illustrated by a broken line) with the machining start hole 1 as a starting point. Since this figure is the same as the state shown in FIG. 11A, description thereof is omitted.

  As shown in FIG. 12B, when forming the fixing portion 4 using the core fixing function, it is necessary to change the machining conditions at the timing of switching the on / off operation of this function. Then, as in FIG. 11B, a short circuit may be detected between the wire electrode 7 and the inner wall 8, and the wire electrode 7 may be retracted by a predetermined distance in the direction opposite to the processing direction. Here, the distance (separation gap) from the wire electrode 7 to the fixed portion 4 at the position retracted until there is no short-circuit is defined as D3.

  As shown in FIG. 12C, when D3 is a small value (non-zero), although the short state of the wire electrode 7 can be released, an instantaneous discharge or an instantaneous short circuit is likely to occur between the wire electrode 7 and the fixed portion 4, There is a concern that the wire electrode 7 may be disconnected at a locally heated location. In particular, when the wire electrode 7 is disconnected, the fixed portion 4 reduces the spatial margin in the vicinity of the current machining position 5 and prevents the wire electrode 7 from being connected or moved, so that the machining position is interrupted (current machining position 5). It is also assumed that it is difficult to restart electric discharge machining.

<Setting example of intermediate section INm>
Therefore, a control method is proposed that can suppress unintended disconnection of the wire electrode 12 under a transient state in which the core fixing function is switched from on to off. Specifically, in a section including the fixed end positions 63 and 64 (hereinafter referred to as an intermediate section INm), a processing condition (hereinafter referred to as an intermediate processing condition) different from both the fixed processing conditions and the normal processing conditions is set. This intermediate machining condition may be a machining condition that is set directly, or may be a machining condition in which either the fixed machining condition or the normal machining condition is changed stepwise and over time.

  In the example of FIG. 4A, the fixing portion 56 (57) is at a position corresponding to the first section IN1 and the intermediate section INm. The groove 59 (58) is at a position corresponding to the second section IN2. As described above, when the start point of the intermediate section INm is located on the upstream side of the fixed end position 63 (64) or the fixed end position 63 (64), the machining condition setting unit 42 is compared with the fixed processing condition in the intermediate section INm. Intermediate machining conditions that suppress electric discharge machining are set. This intermediate processing condition is different from the fixing processing condition and is a processing condition capable of expressing the core fixing function.

  In the example of FIG. 4B, the fixing portion 56 (57) is at a position corresponding to the first section IN1. The groove 59 (58) is at a position corresponding to the intermediate section INm and the second section IN2. As described above, when the end point of the intermediate section INm is on the downstream side of the fixed end position 63 (64) or the fixed end position 63 (64), the machining condition setting unit 42 is compared with the normal processing conditions in the intermediate section INm. Intermediate machining conditions that suppress electric discharge machining are set. This intermediate machining condition is different from the normal machining condition, and is a machining condition capable of forming the groove 59 (58) in the workpiece W.

  In the example of FIG. 4C, the fixing portion 56 (57) is at a position corresponding to a part (A section) of the first section IN1 and the intermediate section INm. The groove 59 (58) is at a position corresponding to a part (B section) of the intermediate section INm and the second section IN2. As described above, FIG. 4A and FIG. 4B may be combined, and the intermediate machining condition in the A section is different from the fixed machining condition and is a machining condition capable of expressing the core fixing function. Further, the intermediate machining conditions in the B section are different from the normal machining conditions, and are machining conditions capable of forming the groove 59 (58) in the workpiece W.

<Setting example of intermediate machining conditions>
The machining condition setting unit 42 may set one or a plurality of intermediate machining conditions for one intermediate section INm. Here, “setting a plurality of intermediate machining conditions” includes changing the control parameters discretely or continuously as time passes.

  For example, regarding FIG. 4A or FIG. 4C, the machining condition setting unit 42 [1] between the wire electrode 12 and the workpiece W in the intermediate section INm (section A in the case of FIG. 4C) as compared with the fixed machining condition. [2] Reduce the machining speed of the workpiece W, [3] Decrease the fluid pressure of the machining fluid, [4] Decrease the flow rate of the machining fluid, and [5] Wire The tension of the electrode 12 may be reduced, [6] the discharge gap distance between the wire electrode 12 and the workpiece W may be increased, or [7] intermediate machining conditions combining these may be set.

  Here, the “machining speed” means a so-called moving speed of the machining axis and corresponds to a relative speed between the wire electrode 12 and the workpiece W. That is, in the above setting example, the moving speed of the machining axis may be relatively slowed by changing the moving speed of the die guides 22 and 24 or the table (not shown).

  4B or 4C, the machining condition setting unit 42 is [1] between the wire electrode 12 and the workpiece W in the intermediate section INm (B section in the case of FIG. 4C) as compared with the normal machining conditions. [2] Reduce the machining speed of the workpiece W, [3] Decrease the fluid pressure of the machining fluid, [4] Decrease the flow rate of the machining fluid, and [5] Wire The tension of the electrode 12 may be reduced, [6] the discharge gap distance between the wire electrode 12 and the workpiece W may be increased, or [7] intermediate machining conditions combining these may be set.

  For example, the effect of reducing the amount of discharge generated between the wire electrode 12 and the workpiece W can be obtained by decreasing the average discharge energy amount or increasing the discharge gap distance. Moreover, the effect which the tension | tensile_strength which acts on the wire electrode 12 is relieve | moderated by weakening the flow pressure of a process liquid or reducing a flow volume is acquired.

  In particular, when the average discharge energy amount is relatively small, the machining condition setting unit 42 is supplied between the wire electrode 12 and the workpiece W as compared with the fixed machining conditions (or normal machining conditions). The discharge current pulse width is narrowed, [2] the peak current value of the discharge current is reduced, [3] the pause time of the current pulse of the discharge current is increased, or [4] intermediate processing conditions by combining these May be set. For example, when the pause time is increased, only the off time of the current pulse may be changed to about 10 to 20 times while the on time of the current pulse is maintained.

  4B or 4C, the machining condition setting unit 42 “dwell machining” in which discharge is continued while the movement of the current machining position is temporarily stopped in the intermediate section INm (B section in the case of FIG. 4C). Intermediate processing conditions including execution of may be set. An effect of increasing the discharge gap distance can be obtained by removing the unprocessed region in the processing direction (forward direction) using this dwell processing. Note that the processing condition setting unit 42 may execute dwell processing in all the intervals in the intermediate interval INm, or may execute dwell processing in only some of the intervals in the intermediate interval INm. It should be noted that when the dwell processing is executed in the entire intermediate section INm, the width of the intermediate section INm is substantially zero.

<First specific example>
FIG. 5 is a time chart showing a change over time in machining conditions for controlling the electric discharge machining shown in FIG. 4A. The horizontal axis of the chart indicates the processing distance (or processing time), and the vertical axis of the chart indicates the average discharge energy amount. Here, it is assumed that the “fixed machining condition” is satisfied by setting the average discharge energy amount to E1, and the “normal machining condition” is satisfied by setting the average discharge energy amount to E2 ( > E1).

  When the machining position is located in the second section IN2, the average discharge energy amount is a constant value (E2). When the current machining position shifts from the second section IN2 to the first section IN1 (when the machining position reaches the fixed start positions 61 and 62), the average discharge energy amount changes from E2 to E1. When the current machining position is in the first section IN1, the average discharge energy amount is a constant value (E1). When the current machining position shifts from the first section IN1 to the intermediate section INm, the average discharge energy amount gradually decreases, and when reaching the fixed end positions 63 and 64, the average discharge energy amount decreases to Em (<E1). When the current machining position shifts from the intermediate section INm to the second section IN2, the average discharge energy amount changes from Em to E2.

  This control is provided with a “weak operation” function that gradually reduces the average discharge energy amount by hardware. Here, by changing the weak operation from “OFF” to “ON” in the intermediate section INm while maintaining the fixed machining condition, the machining condition in which the fixed machining condition is weakened, that is, the intermediate machining condition is obtained. As another means, the control device 18 (machining condition setting unit 42) may set the intermediate section INm and the intermediate machining conditions by directly editing the machining program.

  Next, electric discharge machining control corresponding to the time chart of FIG. 5 will be described with reference to the flowchart of FIG. Here, the operation of the control device 18 during the development of the core fixing function will be described in detail.

  In step S11, the machining condition setting unit 42 reads a control parameter corresponding to the first section IN1, and sets a fixed machining condition. In the example of FIG. 5, the fixed machining condition includes an average discharge energy amount (E1). Thereby, the core fixing function is started. That is, wire electric discharge machining with the core fixing function turned on is started.

  In step S <b> 12, the machining condition setting unit 42 reads the distance from the fixed end positions 63 and 64. In the example of FIG. 4A, since the intermediate section INm and the end points of the fixing portions 56 and 57 coincide, this “distance” is substantially the length of the intermediate section INm (for example, on the order of several hundred μm to several mm). ). The set value of “distance” may be arbitrarily changed according to the thickness of the workpiece W, the diameter of the wire electrode 12, or other control parameters.

  In step S13, the electric discharge machining control unit 44 continues the electric discharge machining control for developing the core fixing function in accordance with the fixing machining conditions read in step S11.

  In step S14, the electric discharge machining control unit 44 determines whether or not the current machining position has reached the distance read in step S12. If not reached yet (step S14: NO), the process returns to step S13, and step S13 is repeated until this distance is reached. That is, when the current machining position is within the first section IN1, the control according to the fixed machining condition is continued. On the other hand, when this distance is reached (step S14: YES), the process proceeds to the next step (S15).

  In step S15, the electric discharge machining control unit 44 continues the electric discharge machining control for exhibiting the core fixing function in accordance with the intermediate machining conditions that weaken the fixing machining conditions.

  In step S <b> 16, the electric discharge machining control unit 44 determines whether or not the current machining position has reached the fixed end positions 63 and 64. If not reached yet (step S16: NO), the process returns to step S15, and step S15 is repeated until the fixed end positions 63 and 64 are reached. That is, when the current machining position is within the intermediate section INm, the control according to the intermediate machining conditions is continued.

  On the other hand, when the fixed end positions 63 and 64 are reached (step S16: YES), this control is ended. Hereinafter, the control device 18 controls electric discharge machining in accordance with the normal machining conditions in the second section IN2.

<Second specific example>
FIG. 7 is a time chart showing changes over time in machining conditions for controlling the electric discharge machining shown in FIG. 4B. The horizontal axis of the chart indicates the processing distance (or processing time), and the vertical axis of the chart indicates the average discharge energy amount. Similarly to the case of FIG. 5, it is assumed that the “fixed machining condition” is satisfied by setting the average discharge energy amount to E1, and the “normal machining condition” is satisfied by setting the average discharge energy amount to E2.

When the current machining position is in the second section IN2, the average discharge energy amount is a constant value (E2). When the current machining position shifts from the second section IN2 to the first section IN1 (when the current machining position reaches the fixed start positions 61 and 62), the average discharge energy amount changes from E2 to E1. When the current machining position is in the first section IN1, the average discharge energy amount is a constant value (E1). When shifting from the first section IN1 to the intermediate section INm (when the current machining position reaches the fixed end positions 63 and 64), the average discharge energy amount gradually increases after changing from E1 to a zero value. Thereafter, the average discharge energy amount increases to Em when the current machining position reaches the end point of the intermediate section INm . When the current machining position shifts from the intermediate section INm to the second section IN2, the average discharge energy amount changes from Em to E2.

  This control is provided with a “weak operation” function that gradually increases the average discharge energy amount by hardware. Here, after shifting to the normal machining conditions at the fixed end positions 63 and 64, the weak operation is changed from “OFF” to “ON” in the intermediate section INm, thereby reducing the normal machining conditions, that is, the intermediate machining. Conditions are obtained.

<Third specific example>
FIG. 8 is a time chart showing the time change of the machining conditions for controlling the electric discharge machining shown in FIG. 4C. The horizontal axis of the chart indicates the processing distance (or processing time), and the vertical axis of the chart indicates the average discharge energy amount. As in the case of FIG. 5 and FIG. 7, the “fixed machining condition” is satisfied by setting the average discharge energy amount to E1, and the “normal machining condition” is satisfied by setting the average discharge energy amount to E2. To do.

When the current machining position is in the second section IN2, the average discharge energy amount is a constant value (E2). When the current machining position shifts from the second section IN2 to the first section IN1 (when the current machining position reaches the fixed start positions 61 and 62), the average discharge energy amount changes from E2 to E1. When the current machining position is in the first section IN1, the average discharge energy amount is a constant value (E1). When the current machining position shifts from the first section IN1 to the A section (the first half of the intermediate section INm), the average discharge energy amount gradually decreases, and when reaching the fixed end positions 63 and 64, the average discharge energy amount is Em. It becomes. When the current machining position shifts from the A section to the B section (the second half of the intermediate section INm), the average discharge energy amount gradually increases, and when the current machining position reaches the end point of the intermediate section INm , the average discharge energy amount is E1. When the current machining position shifts from the intermediate section INm (B section) to the second section IN2, the average discharge energy amount changes from E1 to E2.

  This control is provided with a “weak operation” function that gradually reduces the average discharge energy amount by hardware. Here, while maintaining the fixed machining conditions, the weak operation is changed from “OFF” to “ON” in the A section, thereby obtaining the machining conditions in which the fixed machining conditions are weakened, that is, the intermediate machining conditions in the A section. It is done. In addition, after shifting to the normal machining conditions at the fixed end positions 63 and 64, by maintaining the weak operation “ON” in the B section, the machining conditions in which the normal machining condition is weakened, that is, the intermediate machining in the B section. Conditions are obtained.

<Fourth specific example>
FIG. 9 is a time chart showing changes over time in machining conditions for controlling the electric discharge machining shown in FIG. 4B. The horizontal axis of the chart indicates the processing time, and the vertical axis of the chart indicates the average discharge energy amount. The processing speed of the workpiece W is constant and the average discharge energy amount is set to E1, thereby satisfying the “fixed processing condition”, and the processing speed of the workpiece W is constant and the average discharge energy amount is set to E2. It is assumed that the “normal machining conditions” are satisfied by setting to.

  When the current machining time is in the second section IN2, the average discharge energy amount is a constant value (E2). When the current machining time shifts from the second section IN2 to the first section IN1 (when the current machining position reaches the fixed start positions 61 and 62), the average discharge energy amount changes from E2 to E1. When the current machining time is within the first section IN1, the average discharge energy amount is a constant value (E1).

  When shifting from the first section IN1 to the intermediate section INm (when the current processing position reaches the fixed end positions 63 and 64), the dwell processing is executed with the processing speed temporarily set to zero while maintaining other processing conditions. . As the discharge gap distance increases, the average discharge energy amount gradually decreases, and the average discharge energy amount approaches zero before the dwell time elapses. Thereafter, when the current machining time shifts from the intermediate section INm to the second section IN2, the average discharge energy amount changes from a zero value to E2.

  Next, electric discharge machining control corresponding to the time chart of FIG. 9 will be described with reference to the flowchart of FIG. Here, the operation of the control device 18 during the development of the core fixing function will be described in detail.

  In step S21, the machining condition setting unit 42 reads the control parameters corresponding to the first section IN1, and sets fixed machining conditions. In the example of FIG. 9, the fixed machining conditions include an average discharge energy amount (E1). Thereby, the core fixing function is started. That is, wire electric discharge machining with the core fixing function turned on is started.

  In step S22, the processing condition setting unit 42 reads dwell processing stop time (so-called dwell time). The set value of “stop time” may be arbitrarily changed according to the thickness of the workpiece W, the diameter of the wire electrode 12, or other control parameters.

  In step S23, the electric discharge machining control unit 44 continues the electric discharge machining control for developing the core fixing function in accordance with the fixing machining conditions read in step S21.

  In step S24, the electric discharge machining control unit 44 determines whether or not the current machining position has reached the fixed end positions 63 and 64. If not reached yet (step S24: NO), the process returns to step S23, and step S23 is repeated until the position is reached. That is, when the current machining position is within the first section IN1, the control according to the fixed machining condition is continued. On the other hand, when the fixed end positions 63 and 64 have been reached (step S24: YES), the process proceeds to the next step (S25).

  In step S25, the electric discharge machining control unit 44 stops the axis feed of the table on which the workpiece W is placed while continuing the electric discharge control based on the fixed machining conditions. That is, the electric discharge machining control unit 44 starts and continues dwell machining in the vicinity of the fixing end positions 63 and 64.

  In step S26, the electric discharge machining control unit 44 determines whether or not the stop time read in step S22 has elapsed since the start of dwell machining. If it has not yet elapsed (step S26: NO), the process returns to step S25, and dwell processing (step S25) is performed until this stop time elapses.

  On the other hand, when the stop time has elapsed from the start of dwell processing (step S26: YES), this control is terminated. Hereinafter, the control device 18 controls electric discharge machining in accordance with the normal machining conditions in the second section IN2.

[Effects of this embodiment]
As described above, the wire electric discharge machine 10 generates electric discharge between the wire electrode 12 and the workpiece W while moving the wire electrode 12 and the workpiece W relative to each other. A core for fixing the core Pc formed by the electric discharge machining to the base material Pb of the workpiece W by performing electric discharge machining along the machining path 50 and depositing and depositing the components of the wire electrode 12 generated by the electric discharge machining. This is a processing machine having a fixing function.

  The wire electric discharge machine 10 is set for each [1] section, [1] a machining condition setting unit 42 that sets machining conditions related to electric discharge machining in association with a plurality of sections on the machining path 50. An electric discharge machining control unit 44 that controls electric discharge machining in accordance with the machining conditions. [3] The machining condition setting unit 42 sets (3a) the core fixed in the first section IN1 on the upstream side as the machining conditions. A fixed machining condition (first machining condition) capable of expressing the function is set. (3b) In the second section IN2 on the downstream side, the normal machining conditions (where the grooves 58 and 59 can be formed in the workpiece W ( (3c) In the intermediate section INm between the first section IN1 and the second section IN2, intermediate processing conditions different from both the fixed processing conditions and the normal processing conditions are set.

  Thus, in the intermediate section INm between the first section IN1 on the upstream side and the second section IN2 on the downstream side, intermediate processing conditions different from both the fixed processing conditions and the normal processing conditions are set. In the intermediate section INm, it is possible to shift from the fixed machining condition to the normal machining condition in a stepwise manner. That is, by changing the processing conditions in stages, the influence of the physical action on the wire electrode 12 is reduced, and it is possible to prevent the wire electrode 12 from approaching or coming into contact with the fixing portions 56 and 57 formed most recently. Thereby, it is possible to avoid unintentionally falling into a non-resumable state under a transient state in which the core fixing function is switched from on to off, and it is possible to suppress unintentional disconnection of the wire electrode 12.

  In particular, in the case of the wire electric discharge machine 10 having a core fixing function, the fixed portions 56 and 57 that are formed reduce a spatial margin in the processing groove 52 and prevent the wire electrode 12 from being connected or moved. Thus, the effects of the present invention appear more remarkably.

  Alternatively, [3] The above-described machining condition setting unit 42 may set (3d) execution of dwell machining under the fixed machining conditions at the fixed end positions 63 and 64 of the first section IN1. Using this dwell processing, it becomes possible to remove the remaining processing region in the processing direction (forward direction), and the effect of increasing the discharge gap distance can be obtained. In other words, it becomes possible to prevent the wire electrode 12 from approaching or coming into contact with the fixing portions 56 and 57 that are formed most recently, and cannot be resumed unintentionally under a transient state in which the core fixing function is switched from on to off. It is possible to avoid falling into a state, and it is possible to suppress unintended disconnection of the wire electrode 12.

[Remarks]
In addition, this invention is not limited to embodiment mentioned above, Of course, it can change freely in the range which does not deviate from the main point of this invention. Or you may combine each structure arbitrarily in the range which does not produce technical contradiction.

DESCRIPTION OF SYMBOLS 10 ... Wire electric discharge machine 12 ... Wire electrode 14 ... Processing machine main body 16 ... Processing liquid processing apparatus 18 ... Control apparatus 20 ... Processing tank 22, 24 ... Dice guide 26 ... Supply system 28 ... Collection system 30 ... Wire bobbin 31 ... Torque motor 32 ... Brake shoe 33 ... Brake motor 34 ... Tension detector 35 ... Upper guide part 36 ... Lower guide part 37 ... Guide roller 38 ... Pinch roller 39 ... Feed roller 40 ... Wire collection box 42 ... Processing condition setting part 44 ... Discharge Processing control part 50 ... Processing path 52 ... Processing groove 54 ... Processing start hole 56, 57 ... Fixing part 58, 59 ... Groove part 61, 62 ... Fixing start position 63, 64 ... Fixing end position IN1 ... First section IN2 ... Second Section INm ... Intermediate section Pb ... Base material Pc ... Core W ... Workpiece

Claims (11)

By causing a discharge between the wire electrode and the workpiece while relatively moving the wire electrode and the workpiece, the workpiece is subjected to electric discharge machining along a machining path,
A wire electric discharge machine having a core fixing function for fixing a core formed by the electric discharge machining to a base material of the workpiece by adhering and depositing the wire electrode components generated by the electric discharge machining. And
A machining condition setting unit for setting machining conditions related to the electric discharge machining in association with a plurality of sections on the machining path;
An electric discharge machining control unit for controlling the electric discharge machining in accordance with the machining conditions set for each section by the machining condition setting unit;
With
The processing condition setting unit, as the processing conditions,
In the first section on the upstream side, set the first processing conditions that can express the core fixing function,
In the second section on the downstream side, set a second processing condition that can form a groove in the workpiece,
In the intermediate section between the first section and the second section , execution of the electric discharge machining is set according to an intermediate machining condition that is different from both the first machining condition and the second machining condition. Electric discharge machine. In the wire electric discharge machine according to claim 1,
The start point of the intermediate section is upstream from the end position of the core fixing function,
The end point of the intermediate section is at the end position of the core fixing function,
The wire electric discharge machine, wherein the machining condition setting unit sets the intermediate machining condition in which the electric discharge machining is suppressed as compared with the first machining condition. In the wire electric discharge machine according to claim 1,
The start point of the intermediate section is at the end position of the core fixing function,
The end point of the intermediate section is downstream of the end position of the core fixing function,
The wire electric discharge machine, wherein the machining condition setting unit sets the intermediate machining condition in which the electric discharge machining is suppressed as compared with the second machining condition. In the wire electric discharge machine according to claim 1,
The start point of the intermediate section is upstream from the end position of the core fixing function,
The end point of the intermediate section is downstream of the end position of the core fixing function,
The machining condition setting unit sets the intermediate machining condition in which the electric discharge machining is suppressed as compared with the first machining condition between the start point of the intermediate section and the end position of the core fixing function, and The wire electric discharge machine characterized by setting the intermediate machining condition in which the electric discharge machining is suppressed as compared with the second machining condition between the end position of the child fixing function and the end point of the intermediate section. In the wire electric discharge machine according to claim 2 or 4,
The machining condition setting unit reduces the average discharge energy amount between the wire electrode and the workpiece, slows the machining speed of the workpiece, and reduces the flow of machining fluid compared to the first machining condition. Reducing the pressure, reducing the flow rate of the working fluid, reducing the tension of the wire electrode, increasing the discharge gap distance between the wire electrode and the workpiece, or combining the intermediate processing conditions Wire electric discharge machine characterized by setting. In the wire electric discharge machine according to claim 5,
The machining condition setting unit narrows the pulse width of the discharge current supplied between the wire electrode and the workpiece, and reduces the peak current value of the discharge current, compared to the first machining condition, The wire electric discharge machine is characterized in that the intermediate machining conditions with a relatively small average discharge energy amount are set by extending a pause time of the current pulse of the discharge current or combining them. In the wire electric discharge machine according to claim 3 or 4,
The machining condition setting unit reduces the amount of average discharge energy between the wire electrode and the workpiece, slows the machining speed of the workpiece, and reduces the flow of machining fluid compared to the second machining condition. Reducing the pressure, reducing the flow rate of the working fluid, reducing the tension of the wire electrode, increasing the discharge gap distance between the wire electrode and the workpiece, or combining the intermediate processing conditions Wire electric discharge machine characterized by setting. In the wire electric discharge machine according to claim 7,
The machining condition setting unit narrows the pulse width of the discharge current supplied between the wire electrode and the workpiece, and reduces the peak current value of the discharge current, compared to the second machining condition, The wire electric discharge machine is characterized in that the intermediate machining conditions with a relatively small average discharge energy amount are set by extending a pause time of the current pulse of the discharge current or combining them. In the wire electric discharge machine according to claim 3 or 4,
The wire electric discharge machine, wherein the machining condition setting unit sets the intermediate machining conditions including execution of dwell machining. By causing a discharge between the wire electrode and the workpiece while relatively moving the wire electrode and the workpiece, the workpiece is subjected to electric discharge machining along a machining path,
A wire electric discharge machine having a core fixing function for fixing a core formed by the electric discharge machining to a base material of the workpiece by adhering and depositing the wire electrode components generated by the electric discharge machining. And
A machining condition setting unit for setting machining conditions related to the electric discharge machining in association with a plurality of sections on the machining path;
An electric discharge machining control unit for controlling the electric discharge machining in accordance with the machining conditions set for each section by the machining condition setting unit;
With
The processing condition setting unit, as the processing conditions,
In the first section on the upstream side, set the first processing conditions that can express the core fixing function,
In the second section on the downstream side, set a second processing condition that can form a groove in the workpiece,
At the end position of the first section, execution of dwell machining according to the first machining conditions is set. A wire electric discharge machine. By causing a discharge between the wire electrode and the workpiece while relatively moving the wire electrode and the workpiece, the workpiece is subjected to electric discharge machining along a machining path,
A wire electric discharge machine having a core fixing function for fixing a core formed by the electric discharge machining to a base material of the workpiece by attaching and depositing the components of the wire electrode generated by the electric discharge machining is executed. A wire electric discharge machining method,
A setting step for setting machining conditions related to the electric discharge machining in association with a plurality of sections on the machining path;
A control step of controlling the electric discharge machining according to the machining conditions set for each section in the setting step;
With
In the setting step, as the processing conditions,
In the first section on the upstream side, set the first processing conditions that can express the core fixing function,
In the second section on the downstream side, set a second processing condition that can form a groove in the workpiece,
In the intermediate section between the first section and the second section , execution of the electric discharge machining is set according to an intermediate machining condition that is different from both the first machining condition and the second machining condition. Electric discharge machining method.

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