Electrical discharge machine and method for producing a machined object using the same

Abstract

In an electrical discharge machine, which applies a voltage between an electrode and a workpiece to generate an electrical discharge, an electrode holder supports the electrode. An ultrasonic motor has a fingertip that comes into contact with the electrode holder and moves the electrode holder in a ring-shaped pattern at an ultrasonic frequency in one direction. A rolling bearing guides the movement of the electrode holder in the direction of travel. A control circuit regulates the position of the electrode in the direction of travel by driving the ultrasonic motor and moving the electrode holder based on an anomaly or...Irregularity which occurs in the resistance to the movement of the electrode holder in the drive direction, such that the electrode holder is moved through a distance of movement which is equivalent to when the largest rolling element from the majority of rolling elements of the rolling bearing rolls and rotates once without sliding or longer.

Description

Background [Technical Field]

[0001] The present invention relates to an electric discharge machine and a method for producing a machined object using the electric discharge machine. [State of the art]

[0002] An ultrasonic motor is well known (for example, reference to JP-A-2011-104735). The ultrasonic motor is used in an electrical discharge machine to move an electrode holder, which holds or carries an electrode. The ultrasonic motor has a fingertip that comes into contact with the electrode holder. The ultrasonic motor drives the electrode holder by moving the fingertip in a ring-shaped pattern at an ultrasonic frequency.

[0003] When an ultrasonic motor like this one is used, the movement of the electrode holder can be controlled to such an extent that it is within a very short distance or unit of travel (for example, 1 μm or less). However, according to experiments conducted by the inventors, problems can arise when a rolling bearing is used as an element to guide the movement of the electrode holder in a drive direction. In the rolling bearing, a plurality of rolling elements are inserted between a motion block and a rail.

[0004] In particular, when the electrode holder is moved over a long period with a very short distance, the sliding resistance of the rolling bearing increases. The movement speed of the electrode holder decreases. Consequently, it is very likely that the time required for machining will increase.

[0005] The reason for this phenomenon is that dust or abrasion is generated between the rolling elements and the surrounding path. When the electrode holder is moved repeatedly over a very short distance, the majority of the rolling elements within the bearing move due to minute vibrations without rotating. Consequently, dust or abrasion is generated by the rubbing between the rolling elements and the surrounding path. Summary

[0006] It is therefore required to provide an electric discharge machine which drives an electrode holder using an ultrasonic motor and guides the electrode holder using a rolling bearing, in which an increase in the time required for machining due to an increase in the sliding resistance in the rolling bearing is less likely.

[0007] One exemplary embodiment provides an electric discharge machine that applies a voltage between an electrode and a workpiece, thereby generating an electric discharge. The workpiece is melted and processed by the electric discharge. The electric discharge machine comprises: an electrode holder that supports the electrode; an ultrasonic motor with a fingertip that comes into contact with the electrode holder and moves the electrode holder in a ring-shaped manner at an ultrasonic frequency in a drive direction; a rolling bearing that guides the movement of the electrode holder in the drive direction; and a control circuit that controls the position of the electrode in the drive direction by driving the ultrasonic motor.The rolling bearing comprises: motion blocks attached to the electrode holder; a rail that supports and guides the motion blocks; and a plurality of rolling elements inserted between the motion blocks and the rail. The control circuit moves the electrode holder based on an anomaly or unevenness that occurs in the resistance to the electrode holder's movement in the drive direction. The electrode holder is moved through a distance equivalent to that achieved when the largest rolling element among the plurality of rolling elements completes one rotation without slippage, or longer.

[0008] If the sliding resistance between the rail and the motion blocks becomes greater than it would be under normal conditions, the resistance to the electrode holder's movement in the drive direction is no longer normal. Therefore, based on an anomaly or irregularity occurring in the resistance to the electrode holder's movement in the drive direction, a process is carried out to resolve or eliminate the increase in sliding resistance. Consequently, the increase in sliding resistance can be appropriately suppressed. Additionally, as the electrode holder moves through a travel distance, when the largest rolling element among the multiple rolling elements rolls and rotates without sliding, or for a longer period, even if abrasion is generated, the abrasion can be distributed. Therefore, the increase in sliding resistance can be suppressed.

[0009] The reference numerals in parentheses within the scope of the claims indicate corresponding relationships between the expressions mentioned within the scope of the claims and specific components which exemplify the expressions described according to the embodiments described below and the like. Brief description of the illustrations

[0010] The attached illustrations show:

[0011] Fig. 1 a configuration diagram of an electrical discharge machine 1 according to one embodiment of the present disclosure;

[0012] Fig. 2 a cross-sectional view of a mechanical unit;

[0013] Fig. 3 a representation of a relationship between an elliptical movement of a fingertip and an ascending or upward movement of a holder main body;

[0014] Fig. 4 a diagram of a relationship between an elliptical movement of the fingertip and a descending or lowering movement of the holder's main body;

[0015] Fig. 5 a configuration map of a linear guide;

[0016] Fig. 6 a cross-sectional view of an unlimited circulation path in linear guidance along an extension direction of the unlimited circulation path;

[0017] Fig. 7 a flowchart of a position control process;

[0018] Fig. 8 a time diagram showing the changes over time in an electrode drive signal, an electrode position, a discharge state and the like when a single injection hole is processed by the electrical discharge;

[0019] Fig. 9 a graph of an example of the transition over time of a discharge state;

[0020] Fig. 10 a graph of an example of changes in the position of an electrode holder when a plurality of injection holes are machined;

[0021] Fig. 11 a flowchart of a guide irregularity detection process according to a first embodiment;

[0022] Fig. 12 a representation of a state in which balls are unequally arranged on the unlimited circulation path; and

[0023] Fig. 13 a flowchart of the guidance irregularity detection process according to a second embodiment. Description of embodiments (First embodiment)

[0024] A first embodiment of the present disclosure is described below. An electrical discharge machine. 1 (see Fig. 1) According to the present embodiment, a device which generates an electrical discharge by applying a voltage between an electrode and a workpiece (an object to be processed). The workpiece is melted by the electrical discharge and thereby processed.

[0025] As in Fig. Figure 1 shows the electrical discharge machine. 1 a mechanical unit 2 , a discharge power supply 3 , a discharge state detection circuit 4 , a position detection circuit 5 , a motor amplifier 6 and a control circuit 7 The mechanical unit 2 corresponds to a section within the electrical discharge machine 1 , which performs mechanical processes. The mechanical unit 2 contains an ultrasonic motor 21 , an electrode holder 22, an electrode 23 and the like. A workpiece 24 is on the mechanical unit 2 furnished.

[0026] The ultrasonic motor 21 moves the electrode holder 22 in a drive direction (in particular an upward / downward direction and a feed direction of the electrode) 23 The electrode holder 22 holds or carries the electrode 23 The electrode 23 It is a wire-shaped electrode with a narrow or small diameter (such as a diameter of 0.2 mm or less). The electrode 23 For example, it is configured by a thin, hollow (or continuous or solid) rounded rod made of copper, tungsten, or the like. If the electrode holder 22 through the ultrasonic motor 21 When the electrode is moved in the direction of travel, it moves. 23in the same way in the direction of travel.

[0027] The discharge power supply 3 is a device which is located between the electrode 23 and the workpiece 24 a predetermined voltage is applied repeatedly in a pulsating manner. The repetition cycle corresponds, for example, to several ten-thousandths of a second up to several ten-millionths of a second. When the electrode 23 from the workpiece 24 is separated by a suitable distance and the voltage between the electrode 23 and the workpiece 24 The material is applied between the electrode. 23 and the workpiece 24 An electrical discharge is generated. Machining is performed by cutting a section of the workpiece. 24 executed, which is then melted.

[0028] The discharge state detection circuit 4detects a discharge state of the discharge power supply 3 (in other words, the discharge state between the electrode 23 and the workpiece 24 ) at any time. The discharge state detection circuit 4 The system then outputs the detected discharge state as a discharge state signal to the control circuit. 7 The detected discharge state can be the one between the electrode. 23 and the workpiece 24 applied discharge voltage, the voltage between the electrode 23 and the workpiece 24 corresponding to a flowing discharge current or the like.

[0029] The position detection circuit 5 is a well-known circuit which determines the position of the electrode holder 22 Position detection circuitry is used in the direction of travel. 5 The detected position is then sent to the control circuit.7 out of.

[0030] The motor amplifier 6 corresponds to a circuit which powers the ultrasonic motor 21 based on one of the control circuits 7 The received electrode drive signal drives the motor. In particular, it actuates or operates the motor amplifier. 6 the ultrasonic motor 21 only during a phase in which the following electrode drive signal is received from the control circuit 7 is received. The electrode drive signal during this phase has a voltage level at which the absolute value exceeds a predetermined value (in particular, zero). The motor amplifier 6 operates the ultrasonic motor 21 at a higher speed, while the absolute value of the voltage level of the received electrode drive signal increases, thereby the electrode holder 22is moved at high speed. Hereinafter, the reception of an electrode drive signal, which has a voltage level whose absolute value exceeds the predetermined value (in particular zero), is simply referred to as the reception of an electrode drive signal.

[0031] The control circuit 7 A microcomputer is a well-known type of computer that contains a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), flash memory, and the like. The CPU executes programs stored in the ROM. Consequently, the control unit outputs 7 the electrode drive signal based on the discharge state detection circuit 4 received discharge status signal to the motor amplifier 6 off. In general, the control circuit controls 7 the position of the electrode 23in the drive direction by outputting the electrode drive signal to the motor amplifier 6 , so that the distance between the electrode 23 and the workpiece 24 corresponds to a suitable distance.

[0032] Fig. Figure 2 shows a detailed configuration of the mechanical unit. 2 The mechanical unit 2 contains the ultrasonic motor described above 21 , the electrode holder 22 and the electrode 23 Additionally, the mechanical unit contains 2 an XY stage or platform 25 , a backplate 26 , a fixed plate 27 , a linear guide 28 , a side panel 29 , an electrode guide holder 31 and an electrode guide 32 .

[0033] The XY platform 25 corresponds to a platform or object table on which the workpiece 24is arranged. The XY platform 25 is able to determine the position of the workpiece 24 with regard to the electrode 23 by moving the workpiece 24 in one direction of an X-axis of movement 25x and a direction of a Y-axis of movement 25y to change within a horizontal plane. Additionally, the XY platform 25 electrically connected to a ground-side connection of the discharge power supply via a supply line (not shown). 3 tied together.

[0034] The backplate 26 corresponds to a standing wall, which is attached to the XY platform 25 is attached. The fixed plate 27 corresponds to a plate which is connected to the back plate 26 screwed and attached to it, parallel to the back plate 26 to be the ultrasonic motor 21 and the electrode holder 22 are attached to a surface of the fixed plate27 attached, which are opposite the surface on the side of the backplate 26 is located.

[0035] Here is the ultrasonic motor 21 described. The ultrasonic motor 21 drives the electrode 23 on. The ultrasonic motor 21 This corresponds to a motor that is the size of a fingertip. 21aa in a ring-shaped (especially elliptical) manner at an ultrasonic frequency range. The operating speed or rotational speed of the ultrasonic motor. 21 corresponds to the rotational frequency of the elliptical movement of the fingertip 21aa per unit of time. The elliptical movement of the fingertip 21aa corresponds to an elliptical movement in a clockwise or counterclockwise direction on the paper surface of Fig. 2. A micromotor described in JP-A-H07-184382 can be called the ultrasonic motor. 21how this one can be used. The micromotor is widely available under the name HR1 motors from Nanomotion, Ltd.

[0036] In the ultrasonic motor 21 Electrodes are arranged in a checkerboard pattern at four positions on a rectangular piezoelectric ceramic element. Additionally, the ultrasonic motor contains 21 the fingertip 21aa at a central section of one side of the rectangle. A high-frequency voltage of essentially 50 kHz is applied to the electrodes at two positions on a diagonal line from the electrodes at the four positions of the ultrasonic motor. 21 applied. Consequently, the ceramic element expands, contracts, and bends. At the fingertip 21aa An elliptical motion is generated at a rotation frequency of essentially 50 kHz.

[0037] The electrode holder 22 includes a holder main body 22aa , a first retaining element 22b , a first camp 22c , a rotary transmission element 22d , a rotating conductive element or conductive element 22e , a conductive brush 22f , a second camp 22g and a second retaining element 22h .

[0038] The holder's main body 22aa carries the other elements 22b until 22h of the electrode holder 22 Additionally, the main body of the holder is available. 22aa at the tip section of the ultrasonic motor 21 at any time with the fingertip 21aa in contact. A ceramic plate is in the section of the holder's main body. 22a embedded, which can be reached with the fingertip 21aa comes into contact. When the ultrasonic motor 21 is operated and the fingertip 21aa When the fingertip is moved elliptically, the elliptical movement of the fingertip becomes 21aa as a result of a spring which is attached to the piezo ceramic element, to the holder main body 22aa transferred. The holder's main body 22aa It moves linearly in the direction of travel. Additionally, the main body of the holder moves. 22aa and the other elements 22b until 22h of the electrode holder 22 integral in the direction of drive.

[0039] Here is with reference to the Fig. 3 and Fig. 4 the relationship between the elliptical movement of the fingertip 21aa and the movement of the holder's main body 22a described. As in Fig. 3 shown, when the holder's main body 22aa is moved upwards (in other words, in a direction in the direction of travel of the workpiece). 24 away; corresponding to an example of a second direction D2), the fingertip 21aa moved elliptically in one direction counterclockwise on the paper surface. Additionally, as in Fig. 4 shown when the holder main body 22aa is moved downwards (in other words, in a direction closer to the workpiece). 24 in the direction of drive; corresponding to an example of a first direction D1), the fingertip 21aa moved elliptically in one direction, clockwise, on the paper surface.

[0040] The fingertip 21aa and the holder's main body 22aa They are in a state of contact at all times during the counterclockwise elliptical movement. However, the fingertip presses 21aa stronger against the holder's main body 22aa , when the fingertip 21aa starts up, compared to when the fingertip 21aa sinks. This reduces the frictional force of the fingertip. 21aa on the holder's main body 22aa larger when the fingertip 21aa It starts up. Consequently, the main holder body moves 22aa Overall, it's high.

[0041] Additionally, the fingertips are located 21a and the holder's main body 22a During the elliptical clockwise movement, the fingertip remains in contact at all times. However, the fingertip presses against the fingertip. 21a in this case more strongly against the main holder body 22a , when the fingertip 21a sinks, compared to when the fingertip 21a This increases the frictional force of the fingertip. 21a on the holder's main body 22a larger when the fingertip 21a sinks. Consequently, the main body of the holder sinks. 22a viewed as a whole.

[0042] Additionally, if the fingertip 21a The elliptical movement stops, the holder's main body stops. 22aalso due to the friction between the fingertip 21a and the holder's main body 22a , which is caused by contact between the fingertip 21a and the holder's main body 22a is caused.

[0043] The electrode 23 is through the middle sections of the first retaining element 22b , of the rotation transmission element 22d , of the rotation guide element 22e and the second retaining element 22h inserted. The first retaining element 22b , the rotational transmission element 22d , the rotation guide element 22e and the second retaining element 22e hold the electrode 23 , which is inserted through the middle sections.

[0044] The rotational transmission element 22dis rotated by a rotational mechanism (not shown). A contact-type rotational transmission mechanism, such as a gear mechanism, can be used as the rotational mechanism. Alternatively, a non-contact-type rotational transmission mechanism, such as an air spindle mechanism (refer, for example, to JP-A-2011-104735), can be used. If, for example, the gear mechanism is used, the rotational transmission element corresponds to 22d a gear that rotates around an axis (the section through which the electrode 23 (is inserted). The rotation transfer element 22d It engages with another gear (not shown), which in turn receives the transmission of the rotational force from the other gear and rotates.

[0045] The rotational transmission element 22d is configured in such a way that it is integral with the first holding element 22b, the rotation guide element 22e and the second retaining element 22h rotates.

[0046] Additionally, the first retaining element 22b through the holder's main body 22a with the first camp 22c held in between. The first retaining element 22b is able to, in relation to the holder's main body 22a to rotate. Additionally, the second holding element 22h through the holder's main body 22a with the second camp 22f held or carried in between. The second holding element 22h is able to, in relation to the holder's main body 22a to rotate.

[0047] As a result of this configuration, they rotate when the rotation transmission element... 22d with regard to the main holder body 22a rotates, the first holding element 22b , the rotation guide element 22e and the second retaining element 22htogether with the rotation transmission element 22d The electrode rotates along with the rotation. 23 with regard to the main holder body 22a .

[0048] Additionally, the rotation guide element 22e with a non-ground-side connection for the discharge power supply 3 with the conductive brush 22f The area in between is electrically conductive. Consequently, the discharge power supply can be... 3 via the conductive brush 22f a voltage on the electrode 23 apply.

[0049] The electrode guide holder 31 is below the electrode holder 22 on the backplate 26 attached. The electrode guide 32 is through the electrode guide holder 31 worn in order to be able to, in relation to the electrode guide holder 31 to rotate. Additionally, the electrode guide has 32a through-opening through which the electrode 23 is inserted. The electrode 23 extends from the second holding element 22h downwards. Since the electrode 23 the through-hole in the electrode guide 32 The electrode is traversed. 2 positioned.

[0050] The side panel 29 corresponds to a standing wall, which is attached to the XY platform 25 is attached. The linear guide 28 is on the side panel 29 attached.

[0051] The holder's main body 22a is attached to linear motion blocks 28b and 28c the linear guidance 28 attached. The linear motion blocks 28b and 28c stand with a linear rail 28a intervening to avoid deviating from the linear track 28a to solve. The linear motion blocks 28b and 28care able to move freely along the linear rail in the direction of travel 28a to move.

[0052] As in Fig. As shown in 2, the linear guide is included. 28 the linear rail 28a and the linear motion blocks 28b and 28c The linear rail 28a is on the side panel 29 attached. The linear motion blocks 28b and 28c stand with the linear rail 28a in intervention in order to be able to react to the linear rail 28a to move.

[0053] Fig. Figure 5 shows a perspective partial view of the linear guide. 28 In the perspective view, only the linear movement block is visible. 28b the linear motion blocks 28b and 28c shown. However, the linear motion block possesses 28c likewise the same configuration as that of the linear motion block28b .

[0054] The linear motion blocks 28b and 28c are on the linear track 28a fastened to be able to slip in the direction of travel, with numerous spherical balls. 28d in between (corresponding to an example of a rolling element). The linear rail 28a This corresponds to a track or route element. The linear rail 28a This corresponds to a long element whose cross-sectional shape is perpendicular to the longitudinal direction (corresponding to the drive direction). At the corner sections of the linear rail... 28a on the side of the linear motion blocks 28b and 28c are along the entire length of the linear rail 28a four ball roller grooves 28e formed. The four ball rolling grooves 28e serve as pathways when the balls 28d roll off. The ball roller grooves 28eextend linearly in the longitudinal direction.

[0055] In each of the linear motion blocks 28b and 28c There are also four ball roller grooves. 28j formed. The ball rolling grooves 28j each corresponds to the ball rolling grooves 28e The majority of spheres 28d are between the ball rolling grooves 28e in the linear track 28a and the ball roller grooves 28j in the linear motion blocks 28 and 28 recorded. In addition, the linear motion blocks are 28b and 28c four series of return paths 28m trained. The return pathways 28m extend parallel to the ball rolling grooves. 28j The linear motion blocks 28b and 28c They are also designed with turning paths. Each turning path connects to a return path. 28m and a ball roller groove 28j .

[0056] Fig. Figure 6 shows a cross-sectional view of an unlimited circulation path. The unlimited circulation path is defined by a combination of a single ball rolling groove. 28e , a single ball rolling groove 28j , a single return path 28m and two turning paths 28p configured. The two turning paths 28p connect the ball rolling grooves 28e and 28j and the return path 28m .

[0057] Every unlimited circulation path is filled with numerous spheres. 28d loaded. The balls 28d They are arranged in a single row to be able to make contact with and separate from each other. Additionally, the continuous circulation path is filled with a lubricating oil. Generally, each ball rolls 28dthrough the unlimited circulation path, causing it to move and circulate while taking on a load, as the linear motion blocks 28b and 28c relative to the linear rail 28a move. Fig. Figure 5 shows the arrangement of the unlimited circulation path and the spheres. 28d A section of the linear motion block 28b is in Fig. 5 omitted.

[0058] According to the present embodiment, the diameters of the spheres are 28d in linear guidance 28 They are all the same 1 mm in diameter. However, there may be individual differences in the diameter of the balls. 28d are available.

[0059] The following is an operation of the electrical discharge machine configured as described above. 1 and a processing method using the electric discharge machine 1 described.

[0060] First, the workpiece 24 on the XY platform 25 arranged. The workpiece 24 According to the present embodiment, this corresponds to an element that serves as a base for a nozzle body of a fuel injector. The fuel injector injects fuel (such as gasoline or diesel fuel) into a cylinder of a machine. The workpiece 24 corresponds to an element that has the external appearance of a nozzle body. The workpiece 24 However, it can be an element that serves as a basis for another edited object.

[0061] In the electrical discharge, which is carried out using the electrical discharge machine 1 A step is taken to generate an electrical discharge between the electrode. 23 and the workpiece 24 and to form a single injection hole in the workpiece 24The step is performed repeatedly, adjusting the X-axis and Y-axis orientation positions of the XY platform as needed. 25 The injection point is modified at every time a single injection hole is formed. Consequently, multiple injection holes are used to inject fuel at multiple positions within the workpiece. 24 formed. As a result of these formed injection holes, the workpiece 24 to a finished nozzle body. Therefore, the process for machining the workpiece 24 The use of electrical discharge also represents a method for machining a nozzle body (corresponding to an example of a workpiece).

[0062] A worker places the workpiece 24 on the XY platform 25 The worker then activates or operates the discharge power supply. 3 The discharge power supply3 then begins by connecting the electrode 23 and the workpiece 24 to apply a pulse voltage over a predetermined cycle (such as a cycle of several ten millionths of a second).

[0063] Additionally, the worker operates the discharge state detection circuit. 3 , the position detection circuit 5 , the motor amplifier 6 and the control circuit 7 The discharge state detection circuit then begins. 4 so that the discharge status signal can be sent to the control circuit 7 to output. The discharge state signal indicates the discharge state (such as the discharge current or discharge voltage) between the electrode. 23 and the workpiece 24 on. Additionally, the position detection circuit begins. 5 so that the position signal goes to the control circuit 7to output. The position signal indicates the position of the electrode holder. 22 in the direction of travel.

[0064] Additionally, the control circuit 7 started. The control circuit 7 It begins by performing a position control process based on the received discharge status signal. The control circuit 7 performs the position control process to send the electrode drive signal to the motor amplifier. 6 to output, so that the distance between the electrode 23 and the workpiece 24 to a suitable distance for the electrical discharge. The motor amplifier then drives it. 6 the ultrasonic motor 21 based on the control circuit 7 received electrode drive signal.

[0065] Here are, with reference to the Fig. 7 to Fig. 11. The details of the position control process are described, which is carried out by the control circuit. 7 is carried out. Fig. Figure 7 is a flowchart of the position control process, which is carried out by the control circuit. 7 is carried out. Fig. Figure 8 is a time diagram showing the change over time of the electrode drive signal, the electrode position, the discharge state and the discharge state detection time during electrical discharge.

[0066] During the position control process, the control circuit determines 7 First, at step S110, it determines whether the processing of a new, single injection hole is started. The control circuit 7 The investigation is based, for example, on the fact that the worker was at the electrical discharge machine. 1 executes a predetermined start procedure. The control circuit 7The investigation is repeated until processing begins.

[0067] When it is determined that the processing of a new single injection hole is about to begin, the control circuit executes 7 then performs a single-hole machining preparation process (steps S111 to S114). The control circuit 7 proceeds first to step S111. The control circuit 7 The indicator S resets the system to OFF. The indicator S indicates a short circuit between the electrode. 23 and the workpiece 24 The identifier S corresponds to data stored in a memory (such as RAM) of the control circuit. 7 be kept ready.

[0068] The control circuit then starts. 7 At step S112, a lowering control is used to adjust the electrode holder. 22Starting from a predetermined initial position (home position) in the drive direction, the machine is to be lowered downwards (corresponding to the first direction) to a predetermined machining start position. The control circuit 7 It begins in particular with the motor amplifier. 6 the electrode drive signal for lowering the electrode holder 22 to output. The processing start position corresponds to a position preset at which an electrical discharge occurs between the electrode. 23 and the workpiece 24 can be started (especially in a position where the lower end of the electrode is 23 the upper surface of the workpiece 24 (approaches to allow an electrical discharge).

[0069] The motor amplifier 6 , which has received the electrode drive signal, moves the fingertip 21aof the ultrasonic motor 21 elliptical. The motor amplifier 6 moves the fingertip 21a at a speed corresponding to the absolute value of the electrode drive signal level. The direction of the elliptical motion corresponds to the direction for lifting the electrode holder. 22 , if the level of the electrode drive signal is positive (in other words, counterclockwise in Fig. 3) The direction of the elliptical movement corresponds to the direction for lowering the electrode holder. 22 , if the level of the electrode drive signal is negative (in other words, clockwise in Fig. 4) The level of the electrode drive signal, the output of which starts at step S112, corresponds to a negative value. Therefore, the electrode holder begins 22 and the electrode 23 so that it can lower itself along the direction of drive in order to align itself with the workpiece. 24 to approach.

[0070] The control circuit subsequently measures 7 In step S113, the lowering speed Vd (corresponding to an example of a first movement speed) of the electrode holder 22 and the electrode 23 based on the position signal from the position detection circuit 5 The lowering speed Vd is only measured during a predetermined lowering phase. During this lowering phase, the control circuit operates. 7 Furthermore, it continues to send the electrode drive signal to the motor amplifier. 6 to spend, and continues to use the electrode holder 22 and the electrode 23 to lower. The lowering speed Vd can be set to an average value, a maximum value, a minimum value, or a mode value of the electrode holder's movement speed. 22during the predetermined lowering phase. However, the lowering velocity Vd is calculated as a positive value. In other words, the lowering velocity Vd corresponds to a statistical, representative value of the lowering velocity of the electrode holder. 22 during the predetermined lowering phase.

[0071] The predetermined lowering phase corresponds to a phase whose length is set in advance as a phase during which the electrode holder 22 begins to move from its original position and has not yet reached the processing start position. The predetermined lowering phase can, for example, correspond to a phase that is half the amount of time required until the electrode holder reaches its starting position. 22 After the movement starts from the original position, the processing start position is reached.

[0072] The control circuit awaits below. 7 at step S114 based on the position detection circuit 5 output position signal until the electrode holder 22 The processing start position has been reached. When it is detected that the electrode holder 22 Once the processing start position is reached, the control circuit ends. 7 the output of the electrode drive signal (the electrode drive signal to drive the electrode holder) 22 to lower), which terminates the lowering control. Consequently, the electrode holder stops. 22 and the electrode 23 The temporary decline.

[0073] During the phase from the start of the lowering control at step S112 to the end of the lowering control at step S114, the level of the electrode drive signal can be kept constant. Maintaining this constant level reduces the frequency of the elliptical movement of the fingertip. 21a controlled in such a way that this is fixed. Consequently, the lowering speed of the electrode holder is determined. 22 and the electrode 23 It is controlled in such a way that this position is fixed. As a result, there is a slight acceleration or deceleration of the electrode holder during this phase. 22 and the electrode 23 Therefore, the lowering velocity Vd reflects the effects of the sliding resistance in the linear guide. 28more clearly. However, the level of the electrode drive signal can be changed during the phase from the start of the lowering control at step S112 to the end of the lowering control at step S114.

[0074] The control circuit then proceeds. 7 at step S115, the electrode drive signal 51 (see Fig. 8) via a defined phase T1 to the motor amplifier 6 to output. In the first step S115 after the start of the position control process, the level Y of the output electrode drive signal corresponds to a default value Y0 (Y0 corresponds to a negative value), which is stored in the ROM. In the present example, since step S115 corresponds to the first step after the start of the position control process, the electrode drive signal, whose level corresponds to the default value Y0, is sent to the motor amplifier via the defined phase T1. 6issued.

[0075] The motor amplifier 6 The electrode drive signal is received at level Y0, as described above, via the defined phase T1. The motor amplifier 6 moves the fingertip 21a of the ultrasonic motor 21 elliptically, with a velocity corresponding to the absolute value of level Y0. The direction of the elliptical motion changes depending on whether the level of the electrode drive signal is positive or negative, as described above. In this case, level Y0 corresponds to a negative value. Therefore, the position decreases. 52 in the drive direction of the electrode holder 22 and the electrode 23 through a distance essentially corresponding to level Y0 in order to approach the workpiece 24 to approach.

[0076] The discharge power supply 3continues by measuring the impulse voltage between the electrode 23 and the workpiece 24 to be applied repeatedly, even during the output of the electrode drive signal. 51 The interval T0 of the output time of the electrode drive signal 51 is significantly longer than the interval for applying the pulse voltage. The interval T0 corresponds, for example, to 0.5 ms. During the interval T0, the output time of the electrode drive signal... 51 The pulse voltage is applied approximately ten thousand times. At each time the pulse voltage is applied, a value is determined based on the distance from the workpiece. 24 to the electrode 23 or the like in the discharge state 53 an electrical discharge is generated (an electrical discharge cannot be generated depending on the distance or the like).

[0077] When the output of the electrode drive signal51 Once the defined phase T1 is completed, the control circuit is activated. 7 At step S120, the timer value t is reset to zero. The timer value t changes based on the time elapsed. The control circuit then waits. 7 at step S125 until the timer value t T2 is reached (in other words, starting from the time 54a up to that time 54b , during which phase T2 elapses, after the completion of the continuous output of the electrode drive signal 51 When phase T2 is reached, the control circuit proceeds. 7 then to step S130. Also during the control circuit 7 Waiting until the timer value t T2 is reached, the discharge power supply starts. 3 thus continuing, the impulse voltage between the electrode 23 and the workpiece 24 to be applied repeatedly, as during the output of the electrode drive signal.51 .

[0078] Additionally, while the control circuit 7 waits until the timer value t T2 is reached, the electrode drive signal 51 not to the motor amplifier 6 spent. Therefore, the motor amplifier drives 6 the ultrasonic motor 21 not. However, up to this point, the movement speed of the electrode holder will be 22 and the electrode 23 not suddenly zero, due to inertia, and then the electrode holder moves 22 and the electrode 23 continuing to move forward in the same direction, while this is due to friction with the fingertip 21a The movement will be delayed. At this time, the movement speed remains zero, even if phase T2 elapses, in case the movement speed becomes zero before phase T2 elapses.

[0079] At step S130, the control circuit detects 7 the discharge state 53 between the electrode 23 and the workpiece 24 at this current time, in other words, at the time when the electrode's speed of movement 23 has dropped to a certain level. The control circuit 7 detects the discharge state 53 based on the discharge state signal, which is provided by the discharge state detection circuit 4 is received. The discharge state 53 between the electrode 23 and the workpiece 24 At the current time, an amount can be calculated based on one or both values ​​of the discharge voltage Vg and the discharge current, which are determined by the discharge state detection circuit. 4 to be received, correspond.

[0080] Alternatively, the discharge state 53 between the electrode 23and the workpiece 24 At the current time, the value corresponds to an amount based on one or both values ​​of the average value Vg of the discharge voltage or the average value of the discharge current during a phase, starting from the current point and ending at a point a predetermined amount of time in the past. The only requirement for the predetermined time amount is that the time does not return to the time at which the last output of the electrode drive signal occurred. 51 ended (in other words, the time at which the electrode 23 (starts to descend). If the predetermined time value corresponds to, for example, half of phase T2 or less, the predetermined time value is preferred because the electrode's movement speed 23 is considered to be sufficiently reduced.

[0081] The control circuit subsequently determines 7at step S140, whether the electrode 23 and the workpiece 24 are short-circuited and the phase of the continuous short circuit exceeds a reference time Ts, based on the discharge state 53 , which is obtained in the last step S130 and the previously performed step S130.

[0082] Here, the reference time Ts is, for example, 50 ms. If the reference time Ts is 50 ms and the detection interval T0 of the discharge state signal is 0.5 ms, the phase of the ongoing short circuit is determined such that it exceeds the reference time Ts when the number of times a short-circuit discharge state signal is continuously acquired exceeds 100.

[0083] As in Fig. As shown in 9, this corresponds to the discharge state. 53a voltage value based on the discharge voltage Vg, which is measured at any given time by the discharge state detection circuit 4 is received. The discharge state 53 can allow for a larger distance between the electrode 23 and the workpiece 24 specify while the voltage value increases.

[0084] In this case, flow occurs between the electrode 23 and the workpiece 24 No current flows when the voltage reaches its maximum value (8.0 V). In other words, between the electrode... 23 and the workpiece 24 No electrical discharge is generated. When the voltage value reaches a minimum value (0.0 V), the electrode is... 23 and the workpiece 24 in a short-circuit state.

[0085] If it is determined that the electrode 23 and the workpiece 24If the circuits are short-circuited and the phase of the continuous short circuit exceeds the reference time Ts, the control circuit proceeds. 7 to step S145. If a different result is obtained, the control circuit is bypassed. 7 The process completes step S145 and proceeds to step S150. At step S145, the control circuit... 7 The indicator S is set to ON and then proceeds to step S150.

[0086] At step S150, the control circuit determines 7 based on the discharge state detected at step S130, the level Y of the electrode drive signal 51 The level Y is determined, for example, using an equation Y = K(Vg – Vc), as described above. The level Y of the electrode drive signal 51 , which was determined in this way, corresponds to the level of the electrode drive signal. 51, which is subsequently output continuously. A control coefficient K corresponds to a negative value. The control coefficient K represents the proportional relationship between the deviation of the discharge state detected at step S130 from an ideal discharge state and the level Y of the electrode drive signal. 51 based on the deviation. The control coefficient K is determined in advance as a fixed value. Additionally, Vc corresponds to a positive value, which is determined in advance as the voltage level of the discharge state signal according to the ideal discharge state.

[0087] The level Y of the electrode drive signal, which subsequently goes to the motor amplifier 6 The output to be determined is determined using a procedure like this. Therefore, for example, if the distance or distance between the electrode 23 and the workpiece24 Since the distance to the current point is longer or greater than the distance required to update the ideal electrical discharge, the level Vg of the discharge state is higher than the reference level Vc. Therefore, the value of the level Y of the electrode drive signal is calculated as a negative value. Consequently, the control circuit 7 In the next step S115, a control is carried out to adjust the electrode holder. 22 and the electrode 23 to lower.

[0088] Additionally, for example, if the distance between the electrode 23 and the workpiece 24 Since the current point is shorter or smaller than the distance required to update the ideal discharge, the level Vg of the discharge state is lower than the reference level Vc. Therefore, the value of the level Y of the electrode drive signal is calculated as a positive value. Consequently, the control circuit 7In the following step S115, a control is carried out to adjust the electrode holder. 22 and the electrode 23 to raise.

[0089] Especially if the electrode 23 and the workpiece 24 Since the electrodes are short-circuited at the current point, the level Vg of the discharge state becomes zero. Therefore, the value of the level Y of the electrode drive signal is calculated as the maximum value. Consequently, the control circuit executes 7 In the next step S115, a control is carried out to adjust the electrode holder. 22 and the electrode 23 to raise to the maximum height.

[0090] The distance over which the electrode holder 22 The distance moved in the next step S115, based on the level Y determined in step S150, corresponds to a maximum of several micrometers. This distance is significantly shorter than the diameter of the sphere. 28d .

[0091] The control circuit subsequently determines 7 At step S160, it is determined whether the processing of the injection hole, i.e., the current processing object, is complete. For example, if it is determined that the electrode 23 the workpiece 24 has penetrated, based on the discharge state signal from the discharge state detection circuit 4 , can the control circuit 7 Determine that the machining of the injection hole, i.e., the current machining object, is complete. Alternatively, if it is determined that the electrode holder 22 has reached a predetermined machining completion position, based on the position signal from the position detection circuit 5 , can the control circuit 7 Determine that the processing of the injection hole, i.e., the current processing object, is complete.

[0092] If it is determined that the electrode holder22 If the predetermined processing completion position has not been reached, the control circuit executes 7 Then proceed to step S165. If it is determined that the electrode holder 22 Once the predetermined processing completion position has been reached, the control circuit proceeds. 7 to step S170 to the electrode 23 to the original position.

[0093] At step S165 the control unit waits 7 , until the timer value t reaches the time (T0–T1). The time T1 corresponds to the phase over which a single output of the electrode drive signal 51 is maintained. Therefore, the elapsed time (T0–T1) from the end of the previous output of the electrode drive signal indicates 51 the elapse of the output cycle T0 of the electrode drive signal 51 from the start time of the previous output of the electrode drive signal 51on. When the timer value t reaches the time (T0–T1), the control circuit reverses. 7 Return to step S115. The control circuit 7 continues with the electrode drive signal 51 , which has the level Y determined in the last step S150 for the defined phase T1, to the motor amplifier 6 to spend.

[0094] As a result of the subsequent repeated execution of the loop from steps S115 to S165, as described above, the control circuit executes 7 carry out the following processes (A), (B) and (C) in this order, as shown in Fig. 8 shown. (A) The control circuit 7 gives the electrode drive signal 51 at the defined cycle T0, the electrode is driven out. 23 on (step S115). After the output of the electrode drive signal is complete. 51, when the predetermined time T2 has elapsed (step S125), the control circuit detects 7 the discharge state (step S130). (B) Only if the short circuit persists beyond the reference time Ts, based on the detected discharge state (step S140), does the control circuit change 7 the state of the license plate S is set to ON (step S145). (C) The control circuit 7 determines the level Y of the electrode drive signal 51 based on the detected discharge state (step S150) and gives the next electrode drive signal 51 (Step S165) as the electrode drive signal 51 from which the specific level Y is present.

[0095] The cycle time for detecting the discharge state at step S130 is also T0.

[0096] The time required to detect the discharge state, as described above, corresponds to the time at which the ultrasonic motor21 is not in operation, the electrode 23 is not driven and the speed of movement of the electrode 23 due to inertia, it is weakened or reduced. However, as another example, the time required to detect the discharge state can correspond to the time at which the ultrasonic motor 21 is in operation and the electrode 23 is powered.

[0097] Additionally, if it is determined in step S160 that the electrode holder 22 The predetermined machining completion position has been reached, as described above, or in other words, when the machining of a single injection hole is complete, the control circuit proceeds. 7 to step S170. The control circuit operates during steps 170 to 195. 7 performs a single-hole post-processing operation. The control circuit 7In particular, it first performs a ramp-up control at step S170 to load the electrode holder. 22 in the upward drive direction (corresponding to an example of the second direction) starting from the current position (such as the machining completion position) to the original position. The control circuit 7 It begins in particular with the electrode drive signal to lift the electrode holder. 22 to the motor amplifier 6 to spend.

[0098] The motor amplifier 6 , which has received the electrode drive signal, moves the fingertip 21a of the ultrasonic motor 21 elliptical. The motor amplifier 6 moves the fingertip 21aat a speed corresponding to the absolute value of the electrode drive signal level. Since the electrode drive signal level is positive, the direction of the elliptical motion corresponds to the direction for lifting the electrode holder. 22 (in other words, counterclockwise in Fig. 3) Therefore, the electrode holder begins 22 and the electrode 23 to move upwards along the drive direction in order to move away from the workpiece 24 to remove.

[0099] The control circuit subsequently measures 7 at step S175 the ramp-up speed Vu (corresponding to an example of a second movement speed) of the electrode holder 22 and the electrode 23 based on the position signal from the position detection circuit 5The startup speed Vu is only measured during a predetermined startup phase. During this startup phase, the control circuit operates. 7 Furthermore, it continues to send the electrode drive signal to the motor amplifier. 6 to issue and thus continues to the electrode holder 22 and the electrode 23 to increase. The ramp-up speed Vu can be set to an average value, a maximum value, a minimum value, or a mode value of the electrode holder's movement speed. 22 during the predetermined ramp-up phase. However, the ramp-up speed Vu is calculated as a positive value. In other words, the ramp-up speed Vu corresponds to a statistical, representative value of the ramp-up speed of the electrode holder. 22 during the predetermined startup phase.

[0100] The predetermined start-up phase corresponds to a phase whose length is set in advance as a phase during which the electrode holder 22 This begins the process of moving from the original position and before reaching the processing start position. The predetermined ramp-up phase could, for example, correspond to a phase that is half the amount of time required for the electrode holder to reach its starting position. 22 The processing start position is reached after the movement has started from the original position.

[0101] The control circuit awaits below. 7 at step S180 until the electrode holder 22 the original position is reached, based on the position signal from the position detection circuit 5 is output. If it is detected that the electrode holder 22Once the original position has been reached, the control circuit ends. 7 the output of the electrode drive signal (the electrode drive signal to drive the electrode holder) 22 to lift), which terminates the ramp-up control. Consequently, the electrode holder terminates 22 and the electrode 23 temporarily restarting.

[0102] During the phase from the start of the ramp-up control at step S170 to the end of the ramp-up control at step S180, the level of the electrode drive signal can be kept constant. Maintaining this constant level increases the frequency of the elliptical movement of the fingertip. 21a controlled in such a way that this is fixed. Consequently, the acceleration speed of the electrode holder is determined. 22 and the electrode 23It is controlled in such a way that this position is fixed. Therefore, during this phase, there is a slight acceleration or deceleration of the electrode holder. 22 and the electrode 23 Therefore, the acceleration speed Vu reflects the effects of sliding resistance in the linear guide. 28 more clearly reflected. However, the level of the electrode drive signal can be changed during the phase from the start of the ramp-up control at step S170 to the end of the ramp-up control at step S180.

[0103] The control circuit then proceeds 7 At step S185, a guide anomaly or irregularity detection process is carried out. During this guide irregularity detection process, the control circuit determines 7 Whether a guide anomaly or irregularity has occurred. A guide irregularity exists when the sliding resistance in the linear guide is elevated. 28excessively larger than it becomes during a normal state.

[0104] In step S190, the control circuit determines 7 Based on the result of the guide irregularity detection process at step S185, the control circuit determines whether a guide irregularity has occurred. If it is determined that a guide irregularity has occurred, the control circuit executes 7 At step S195, an upper / lower limit stroke control is performed. The control circuit 7 It then returns to step S110 to process the next injection hole. If no guide irregularity is detected, the control circuit bypasses it. 7 Step S195 and returns to step S110 to process the next injection hole. Details of the upper / lower limit stroke control in step S195 are described below.

[0105] As described above, the control circuit 7 the in Fig. The position control process shown in section 7 is carried out when a plurality of injection holes are present in a single workpiece. 24 to be processed or when a plurality of injection holes are present in a plurality of workpieces 24 to be processed. During the position control process, the control circuit performs 7 the single-hole machining preparation process (steps 111 to 114), then the actual machining process (steps 115 to 165) and then the single-hole post-processing process (steps 170 to 195) when each hole is machined (step S110).

[0106] During the single-hole machining preparation process, the control circuit lowers 7 the electrode holder 22 starting from the original position to the processing start position. Additionally, the control circuit detects 7 the movement speed Vd of the electrode holder 22during the predetermined lowering phase described above.

[0107] Additionally, the control circuit generates 7 During the actual machining process, an electrical discharge occurs between the workpiece and the workpiece. 24 and the electrode 23 The control circuit 7 This involves drilling the injection hole in the workpiece. 24 forward, while the workpiece 24 It is melted by the electrical discharge. The control circuit then... 7 During the actual processing operation, the indicator S is set to ON (step S145) when the electrode 23 and the electrode holder 22 and the workpiece 24 are short-circuited for a longer period than the reference time Ts (step S140).

[0108] As described above, if a short circuit occurs only once during the actual processing operation, the control circuit will 7a control through to the electrode holder 22 to move in the direction to the electrode 23 from the workpiece 24 to remove, at step S150 at this point. Therefore, a short-circuit condition is not usually detected multiple times continuously during repetitions of step S130. Frequent continuous detection of the short-circuit condition indicates that the sliding resistance in the linear guide is 28 has increased. The probability is high that the linear motion blocks 28b and 28c a difficulty in moving across the line of the rail 28a own.

[0109] Additionally, the control circuit 7 during the single-hole post-processing procedure, the electrode holder 22 starting from the processing completion position and moving back to the original position. Additionally, the control circuit detects 7the movement speed Vu of the electrode holder 22 during the predetermined startup phase described above. The control circuit 7 Subsequently performs the upper / lower limit lift if an irregularity has occurred, based on the result of the guide irregularity detection process.

[0110] If the electrode holder 22 During one of the single-hole machining preparation processes described above, the actual machining process and the single-hole post-machining process, the linear motion blocks move in the drive direction. 28b and 28c integrally integrated with the electrode holder at all times 22 along the linear track 28a As a result of the movement of the linear motion blocks 28b and 28c along the linear track 28a The linear track 28a the movement of the electrode holder22 in the direction of travel.

[0111] Here is with reference to Fig. 10. An example is described in which the worker makes a plurality of injection holes in a single workpiece. 24 processed, or an example where the worker makes a plurality of injection holes in a plurality of workpieces 24 processed using the electric discharge machine 1 .

[0112] As in Fig. As shown in 10, the worker at time t10 first places the workpiece 24 on the XY platform 25 one, as in Fig. Figure 1 shows the process of machining the first hole. The worker then activates the discharge power supply. 3 , the discharge state detection circuit 4 , the position detection circuit 5 , the motor amplifier 6 and the control circuit 7 .

[0113] The worker then performs a predetermined start operation at the electrical discharge machine at time t11. 1 through. The control circuit 7 The process then proceeds from step 110 to 111 and performs the single-hole machining preparation procedure. The position of the electrode holder then changes. 22 at a fixed speed, which is higher than the speed during the actual machining, starting from the original position towards the machining start position, as in Fig. 10 through a continuous line 60 depicted.

[0114] The control circuit then terminates. 7 the single-hole machining preparation process and starts the actual machining process when the electrode holder 22The processing start position is reached at time t12. The time required from time t11 to time t12 is, for example, 0.5 seconds.

[0115] After time t12, the injection hole in the workpiece 24 through the electrode 23 Drilling proceeded slowly. At time t13, the electrode penetrates. 23 the workpiece 24 At the following time t14, the control circuit determines 7 , that the processing of the current injection hole is completed at step S160. The control circuit 7 This completes the actual processing operation. The time required from t12 to t14 is, for example, 10 to 30 seconds.

[0116] It is assumed here that no short circuit occurred across a phase during the processing of the first injection hole, exceeding the reference time Ts. Therefore, the control circuit bypasses this. 7 During the phase from time t12 to time t14, steps 140 to 145 are executed at each time, and the process progresses to step S150. Therefore, the indicator S remains OFF at time t14.

[0117] After time t14, the control circuit proceeds. 7 It proceeds to step S170 and performs the single-hole post-processing operation. Subsequently, as described above, the position of the electrode holder increases. 22 at a fixed speed, which is higher than the speed during the actual machining, starting from the machining completion position and moving back to the original position, as shown in Fig. 10 through a continuous line 60 specified.

[0118] If the electrode holder 22 When the original position is reached at time t15, the control circuit executes 7 The leadership irregularity investigation is carried out at step S185. As in Fig. As shown in 11, the control circuit determines 7 During the guidance irregularity detection at step S205, the system first checks whether the lowering speed Vd (positive value), measured at the last step S113, is lower than a predetermined lowering reference speed Vd0 (corresponding to an example of a first reference speed). Subsequently, if it is determined that the lowering speed Vd is lower than the lowering reference speed Vd0 (positive value), the control circuit proceeds. 7 to step S225. The control circuit 7 The system has determined that a guidance irregularity has occurred and terminates the guidance irregularity investigation. Additionally, the control circuit proceeds. 7to step S210, if it is determined that the lowering speed Vd is equal to or higher than the lowering reference speed Vd0.

[0119] The balls usually rotate. 28d within the linear guidance 28 , causing them to roll through space when the linear motion blocks move 28b and 28c move. Consequently, the sliding resistance between the linear rail is 28a and the linear motion blocks 28b and 28c reduced. The reduction in sliding resistance is achieved through the resistance-reducing effect of the balls rolling. 28d This reduction in sliding resistance is also achieved through the effect of the lubricating oil moving within the unlimited circulation path in conjunction with the rolling of the balls. 28d (rolling motion) is achieved, which allows the lubricating oil to be distributed evenly over the unlimited circulation path.

[0120] However, as described above, the distance over which the electrode holder extends is 22 at step S115 during the actual processing operation (in other words, the movement path of the linear motion blocks) 28b and 28c ), at most several μm, whereas the diameter of the spheres 28d within the linear guidance 28 The size is approximately 1 mm. Therefore, the balls move 28d , while these vibrate to a very small extent at a high frequency without rolling. Additionally, the variations in the amount of movement of the individual spheres take into account 28d to.

[0121] If this condition persists, as in Fig. As shown in 12, this occurs in the distribution of the balls. 28d within the unlimited circulation path, an uneven positioning occurs. In a section where the spheres 28dWhen the spheres are concentrated, mutual contact occurs between them. 28d Consequently, the sliding resistance between the linear rail increases. 28a and the linear motion blocks 28b and 28c due to the frictional force between the balls 28d to.

[0122] Additionally, it becomes difficult to ensure that the lubricating oil is distributed evenly along the unlimited circulation path, due to the amount of movement of the balls. 28d It is small. Consequently, the balls grip. 28 They overlap or touch each other. Additionally, when the spheres... 28d move while vibrating to a very small extent at a high frequency without rolling, in a condition where the lubricating oil is not evenly distributed, causing abrasion, as the balls 28d and the unlimited circulation path rubs against each other. The resulting downforce interacts with the spheres. 28d, thereby reducing the sliding resistance between the linear rail 28a and the linear motion blocks 28b and 28c is increased. Such a condition corresponds to a state of guide irregularity, in which the sliding resistance becomes excessively greater than it would be under normal conditions.

[0123] If the sliding resistance between the linear rail 28a and the linear motion blocks 28b and 28c in this way increases if the driving force of the electrode holder 22 The same applies to the movement speed of the electrode holder. 22 ab. According to the present embodiment, this decrease in movement speed is used as follows. If the lowering speed Vd of the electrode holder 22If the lowering speed is lower than the predetermined lowering reference speed Vd0 during the predetermined lowering phase (step S205), the control circuit determines 7 that a guidance irregularity has occurred (step S225). The lowering reference speed Vd0 can be predefined as half the prescribed speed at which the electrode holder 22 during a conventional single-hole machining preparation process, it can be determined.

[0124] The control circuit subsequently determines 7 At step S205, the control circuit checks whether the startup speed Vu (positive value) measured at the last step S175 is lower than a predetermined startup reference speed Vu0 (corresponding to an example of a second reference speed). If it is determined that the startup speed Vu is lower than the startup reference speed Vu0 (positive value), the control circuit proceeds.7 The system proceeds to step S225 and detects that a guide irregularity has occurred. If it is determined that the ramp-up speed Vu equals or exceeds the ramp-up reference speed Vu0, the control circuit proceeds. 7 to step S215.

[0125] In other words, as described above, the movement speed of the electrode holder. 22 decreases as the sliding resistance increases. The control circuit 7 This fact is used as follows. If it is determined that the ramp-up speed Vu of the electrode holder 22 If the speed during the predetermined startup phase is lower than the predetermined startup reference speed Vu0 (step S210), the control circuit determines 7that a guidance irregularity has occurred (step S225). The ramp-up reference speed Vu0 can be determined in advance as half the assumed speed at which the electrode holder 22 during a typical single-hole machining preparation process.

[0126] Taking into account the electrode holder 22 and the linear motion blocks 28b and 28c applied gravitational force, when the absolute value of the level of the control circuit 7 Since the output electrode drive signal is the same during both the predetermined lowering phase and the predetermined ramp-up phase, the lowering reference speed Vd0 is set higher than the ramp-up reference speed Vu.

[0127] In this way, the control circuit compares 7the movement speeds Vd and Vu in the drive direction of the electrode holder 22 with the reference velocities Vd0 and Vu0, which determines whether there is resistance to the movement of the electrode holder. 22 is abnormal.

[0128] The movement speed Vd, which is compared with the reference speed Vd0, corresponds to the movement speed of the electrode holder. 22 , if the electrode holder 22 starting from the original position in the direction of the workpiece 24 The movement is performed to initiate the processing of a single injection hole. Additionally, the movement speed Vu, which is compared to the reference speed Vu0, corresponds to the movement speed of the electrode holder. 22 , if the electrode holder 22 is returned to its original position after the processing of the same injection hole is completed.

[0129] The steps for moving the tool before and after starting the processing of a single injection hole correspond to steps typically found in the processing steps themselves. Therefore, when using the movement speed for comparison in these steps, it is unnecessary to include a separate phase for measuring the movement speed. This results in faster processing. Additionally, the steps for moving the tool before and after starting the processing of a single injection hole correspond to a phase during which the electrode holder can be moved in one direction over a long distance, similar to the processing steps for a single hole. Therefore, the movement speed during this phase can be measured with high accuracy.

[0130] Additionally, the control circuit determines 7, that the guidance irregularity has occurred if at least one condition from the condition that the lowering speed Vd is lower than the lowering reference speed Vd0, and the condition that the raising speed Vu is lower than the raising reference speed Vu0, is met, even if the other condition is not met.

[0131] One reason for conducting the investigation in this way is that if the sliding resistance is due to an unequal positioning of the majority of balls 28d increases the movement of the electrode holder 22Movement is not necessarily difficult in either the upward or downward direction. In some circumstances, movement is only difficult in one direction. As described above, by determining that the guide irregularity has occurred when an irregularity is detected in either the lowering speed Vd or the raising speed Vu, situations can be addressed in which the movement of the electrode holder is difficult. 22 It only becomes difficult in one direction.

[0132] At step S215, the control circuit determines 7 The system checks whether the indicator S is set to ON. If it is determined that the indicator S is set to ON, the control circuit proceeds. 7 to step S225. The control circuit 7The system detects that a guidance irregularity has occurred and terminates the guidance irregularity investigation. If it is determined that the indicator S is set to OFF, the control circuit proceeds. 7 to step S220. The control circuit 7 Determines that no management irregularity has occurred and concludes the management irregularity investigation.

[0133] In this way, the control circuit determines 7 , that the resistance to the movement of the electrode holder 22 It is not normal if the indicator S is set to ON, in other words, if the phase during which the electrode 23 and the workpiece 24 are short-circuited, and the reference time Ts is exceeded during the last actual processing operation.

[0134] If the sliding resistance between the linear rail 28a and the linear motion blocks 28b and28c It is abnormal, even if a control is performed to adjust the electrode. 23 from the workpiece 24 to separate during the short circuit of the electrode 23 and the workpiece 24 , can the electrode 23 not from the workpiece 24 Therefore, as described above, the separation can be based on the phase during which the electrode 23 and the workpiece 24 are short-circuited, and it will be determined whether the resistance to the movement of the electrode holder is sufficient. 22 In other words, what is abnormal is whether a leadership irregularity has occurred.

[0135] For example, in the example in Fig. 10. During the single-hole machining preparation process for machining the first hole (t11 to t12), the actual machining process (t12 to t14), and the single-hole post-machining process (t14 to t15), it is assumed that no guide irregularity has occurred. In this case, the electrode holder 22 It moves at normal speed. Even if a short circuit occurs, it is quickly resolved or eliminated. Therefore, the control circuit determines 7 at step S205 in Fig. 11, that the lowering speed Vd is equal to or higher than the lowering reference speed Vd0, and proceeds to step S210.

[0136] The control circuit then determines 7 At step S210, the system detects that the startup speed Vu is higher than the startup reference speed Vu0 and proceeds to step S215. The control circuit 7The system determines at step S215 that the indicator S is set to OFF and proceeds to step S220. The control circuit 7 The control circuit then determines that no irregularity has occurred. Afterward, the control circuit determines... 7 At step S190, no irregularity occurred. The control circuit 7 skips step S195 and returns to step S110.

[0137] After the processing of the first injection hole has been completed, the worker temporarily removes the workpiece during the phase from time t15 to time t16. 24 from the XY platform 25 Alternatively, the control circuit moves 7 automatically the XY platform 25 Consequently, the workpiece 24 moved to a position which affects the movement of the electrode 23 not disabled.

[0138] Then the worker or the control circuit moves 7the workpiece 24 , so that the position at which the second injection hole is located in the workpiece 24 It is to be formed directly below the electrode. 23 is positioned. Subsequently, at time t16, the worker performs the predetermined start operation on the electrical discharge machine. 1 through.

[0139] The control circuit 7 The process then fails from step 110 to 111. The control by the control circuit... 7 and the operation of the electric discharge machine 1 During the subsequent phase, from time t16 to time t17, the control and operation are the same as from time t11 to time t15. As a result of the worker repeatedly performing such processes, the majority of injection holes are created in the workpiece. 24 trained.

[0140] The worker then moves the workpiece 24, so that the position at which the last injection hole is located in the workpiece 24 It is to be formed directly below the electrode. 23 is positioned. At time t18, the worker performs the predetermined start operation of the electrical discharge machine. 1 through the control circuit 7 then proceeds from step S110 to S111.

[0141] Control via the control circuit 7 and the operation of the electric discharge machine 1 During the subsequent phase, from time t18 to time t22, the control and operation are the same as from time t11 to time t15. However, it is assumed that a control irregularity has already occurred at time t18.

[0142] It is then assumed that only one, only any two, or all of the following points (p), (q) and (r) have occurred. (p) The lowering velocity Vd of the electrode holder 22 , which is measured during the single-hole machining preparation process from time t18 to time t19, is lower than the lowering reference speed Vd0. (q) A short circuit occurs for a phase that exceeds the reference time Ts, as in phase T3 in Fig. 9, during the actual processing phase at the time t19 to t21. (r) The acceleration speed Vu of the electrode body 22 , which is measured during the single-hole post-processing operation from time t21 to time t22, is lower than the ramp-up reference speed Vu0.

[0143] The control circuit then proceeds 7During the guide irregularity detection process performed at time t22, if the aforementioned point (p) has occurred, the system proceeds from step 205 to 225 and determines that a guide irregularity has occurred, even if (q) and (r) have not occurred during the guide irregularity detection process performed at time t22. Additionally, if (p) has not occurred and (r) has occurred, the control circuit proceeds 7 from step 210 to 225 and determines that a leading irregularity has occurred, even if (q) has not occurred.

[0144] Furthermore, if neither (p) nor (q) has occurred and (q) has occurred, the control circuit proceeds 7 from step 215 to 225 and determines that a guidance irregularity has occurred. Therefore, the control circuit determines 7 at step S190 in Fig. 7, that a management irregularity has occurred and proceeds to step S195.

[0145] At step S195, the control circuit 7 The upper / lower limit stroke control is carried out. In particular, the control circuit waits for 7 First, for a predetermined waiting period. During the waiting period, the worker temporarily removes the workpiece. 24 from the XY platform 25 Alternatively, the worker moves the XY platform. 25 and moves the workpiece 24 towards a position which restricts the movement of the electrode 23 not obstructed. Subsequently, at time t23, when the waiting period has elapsed, the electrode holder is 22 through a procedure such as this one in Fig. 10, moved.

[0146] In particular, the control circuit 7Starting from time t23, the maximum positive electrode drive signal is sent to the motor amplifier until time t24. 6 to output. Consequently, the motor amplifier uses 6 the ultrasonic motor 21 and continues to examine the electrode holder 22 to lift at the maximum possible acceleration speed.

[0147] The control circuit then detects 7 at time t24, that the electrode holder 22 has reached the upper limit position, which corresponds to the highest possible performance level, based on the position signal from the position detection circuit 5 The control circuit then proceeds. 7 Starting from time t24 to time t25, the lowest negative electrode drive signal is sent to the motor amplifier. 6 to output. Consequently, the motor amplifier uses 6 the ultrasonic motor21 and continues to examine the electrode holder 22 to lower at the maximum lowering speed with regard to performance.

[0148] The control circuit then detects 7 at time t25, that the electrode holder 22 has reached the lower limit position, which corresponds to the lowest possible performance level, based on the position signal from the position detection circuit. 5 The control circuit then proceeds. 7 Starting from time t25 to time t26, the maximum positive electrode drive signal is sent to the motor amplifier. 6 to output. Consequently, the motor amplifier uses 6 the ultrasonic motor 21 and continues to examine the electrode holder 22 to raise the engine to the maximum startup speed with regard to performance.

[0149] The control circuit then detects 7 at time t26, that the electrode holder 22 has reached the original position, based on the position signal from the position detection circuit 5 The control circuit 7 It sets the level of the electrode drive signal to zero. Consequently, the motor amplifier terminates. 6 the operation of the ultrasonic motor 21 and stops the movement of the electrode holder 22 The upper / lower limit stroke control performed in step S195 is as described above. In step S195, the control circuit reverses. 7 Return to step S110.

[0150] In the present example, the upper / lower limit stroke control is performed after the last injection hole has been processed. However, the points (p), (r), and (q) described above can occur during the processing of injection holes other than the last one (such as the first or second injection hole). In this case, the control circuit determines 7 During the single-hole post-processing operation for the hole other than the last injection hole, a guide irregularity has occurred at step S190, and performs the upper / lower limit stroke at step S195 in a similar manner as described above.

[0151] The distance from the original position to the upper limit and the distance from the original position to the lower limit are set to a movement path when the largest ball 28dwith the largest diameter of all those in the linear guide 28 contained spheres 28d rolls off and rotates once without sliding (in other words, the length of the great circle of the largest sphere) 28d ), or longer.

[0152] Consequently, the balls rotate. 28d once or more frequently, starting from time t23 to time t24. The spheres 28d The balls then rotate twice or more frequently, starting from time t24 and ending at time t25. 28d They then rotate once or more frequently, starting from time t25 and ending at time t26. This prevents uneven positioning when arranging the balls. 28d They are dissolved or suppressed. Additionally, the lubricating oil is distributed more easily and evenly because the balls... 28dmove over a long distance simultaneously. Additionally, even if abrasion is generated, it can be distributed. Consequently, the increase in sliding resistance between the linear rail is reduced. 28a and the linear motion blocks 28b and 28c resolved or suppressed.

[0153] The time value from time t23 to time t26 is significantly shorter (such as 3 seconds) than the time value required for the actual processing of a single injection hole.

[0154] In this way, the control circuit moves 7 the electrode holder 22 At high speed, a ball travels a distance equal to the distance traveled when the largest ball rolls and completes one rotation without slipping. Consequently, the sliding resistance increases between the linear rail. 28a and the linear motion blocks 28b and 28creleased or suppressed. Therefore, the movement of the electrode holder is... 22 Calm down. The time required for processing the injection hole can be reduced.

[0155] Additionally, the electrode holder moves 22 in a single upper / lower limit stroke control operation through a distance which is the length of the great circle of the largest sphere 28d This corresponds to, or longer, a continuous upward movement. Additionally, the electrode holder moves. 22 through a distance equal to the length of the great circle of the largest sphere 28d corresponds to, or continuously downwards for a longer period.

[0156] Depending on the unequal positioning of the balls 28d The unequal positioning cannot be explained solely by the electrode holder. 22 to be eliminated, which is moved through a distance equal to the length of the great circle of the largest sphere 28dcorresponds to, or is longer, in only one direction. In such circumstances, the probability of the resolved unequal positioning also increases if the electrode holder 22 is moved in both directions through a distance which is equal to the length of the great circle of the largest sphere 28d is equal to or longer. (Second embodiment)

[0157] A second embodiment of the present disclosure is described below. According to the present embodiment, the content of the control circuit is 7 at step S180 in Fig. The guide irregularity detection process carried out in step 7 is modified from this process according to the first embodiment. The guide irregularity detection process is modified from the process in Fig. 11 towards the process in Fig. 13 changed.

[0158] During the process in Fig. 13. Steps S205 and S210 were removed from the process in Fig. 11 is replaced by step S208. In step S208, the control circuit determines 7 , whether the absolute value of the difference between the lowering speed Vd (positive value) measured at the last step S113 and the raising speed Vu (positive value) measured at the last step S175 is greater than a predetermined reference speed difference VT.

[0159] If it is determined that the absolute value is greater than the reference velocity difference VT, the control circuit proceeds. 7 The system proceeds to step S225 and subsequently determines that a guide irregularity has occurred. If it is determined that the absolute value of the reference velocity difference VT is equal to or less than this value, the control circuit advances. 7 to step S220 and determined that no guidance irregularity occurred.

[0160] As a result of determining whether a guidance irregularity has occurred, based on a comparison of the lowering speed Vd and the raising speed Vu in this way, situations can also be addressed in which the movement of the electrode holder 22 It becomes difficult in only one direction.

[0161] Additionally, if the sliding resistance is increased due to unequal positioning of the balls 28d As the resistance increases, the resistance with respect to downward movement and the resistance with respect to upward movement are not the same. Rather, it is likely that the resistance with respect to downward movement and the resistance with respect to upward movement will differ significantly. Therefore, situations can also be addressed where the movement of the electrode holder... 22 It becomes difficult in both directions. (Other embodiments)

[0162] The present disclosure is not limited to the embodiments described above. Variations are possible in a suitable manner within the scope of protection specified in the claims. Furthermore, the embodiments described above are not unrelated to one another. Except in circumstances where combinations are clearly or obviously not possible, the embodiments can be suitably combined. It is also understood that elements configuring each of the embodiments described above are not necessarily required elements, except in circumstances where the element is clearly and explicitly stated as necessary, circumstances where the element is clearly required based on the principle, and the like.

[0163] Furthermore, in the embodiments described above, in which numerical values ​​such as a quantity, a numerical value, an amount or range of a component of the embodiment are mentioned, the numerical value is not limited to the specific number, except in circumstances where the numerical value is clearly and distinctly indicated as required, circumstances where the numerical value is clearly limited to the specified number based on the principle, and the like.

[0164] Furthermore, in the embodiments described above, where the shape, positional relationship, and the like of components are mentioned, the components are not limited to the shape, positional relationship, and the like, except in circumstances where the component is clearly specified as being limited to the shape, positional relationship, and the like, or in circumstances where the component is limited to a specific shape, positional relationship, and the like based on the principle, and the like. For example, the following variations are permitted. The following variations may be selectively applied to the embodiments described above. In other words, any combination of the following variations may also be applied to the embodiments described above. (First variation example)

[0165] In the embodiments described above, the spheres 28d in the unlimited circulation path of the linear guide 28 They are not connected by a ball holder. The ball holder maintains the distance between the balls. 28d It stands upright over a fixed distance and connects the spheres. 28d together. The balls 28d in the unlimited circulation path of the linear guide 28 However, can bullets 28d These are connected by a ball holder. In this case, the problem of generated abrasion occurs in a similar way to that with the balls. 28d , which in the present disclosure are not connected by a ball holder. This problem is solved by the upper / lower limit stroke control described above. (Second variation example)

[0166] In the embodiments described above, the linear guide 28 configured such that between the linear rail 28a and the linear motion blocks 28b and 28c spherical spheres 28d are inserted. However, instead of the spherical spheres, 28d Circular, column-shaped rollers must be inserted. In other words, it is only necessary that the rollers between the linear rail 28a and the linear motion blocks 28b and 28c The inserted elements represent a plurality of rolling elements. Additionally, the linear guide can 28 The guide that directs linear motion can be replaced by a guide that directs curved motion. In other words, it is only necessary that the guide 28 a rolling bearing. QUOTES INCLUDED IN THE DESCRIPTION

[0167] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0168] JP 2011-104735 A [0002, 0044] JP 07-184382 A

[0035]

Claims

[1] Electrical discharge machine for applying a voltage between an electrode ( 23 ) and a workpiece ( 24 ) to generate an electrical discharge so that the workpiece is melted and processed by the electrical discharge, the electrical discharge machine comprising: an electrode holder ( 22 ), which carries the electrode; an ultrasonic motor ( 21 ), which is a fingertip ( 21a ) possesses a fingertip that comes into contact with the electrode holder and moves the electrode holder in a ring-shaped manner at an ultrasonic frequency in a predetermined driving direction; a rolling bearing ( 28 ), which guides the movement of the electrode holder in the drive direction, wherein the rolling bearing has: Movement blocks ( 28b and 28c ), which are attached to the electrode holder; a rail ( 28a ), which carries the movement blocks and guides the movement of the movement blocks; and a plurality of rolling elements ( 28d ), which are inserted between the movement blocks and the rail; and a control circuit ( 7 ), which controls a position of the electrode in the drive direction by driving the ultrasonic motor, wherein the control circuit is configured to move the electrode holder based on a non-uniformity which occurs in the resistance to the movement of the electrode holder in the drive direction, wherein the electrode holder is moved through a distance of movement which is equivalent to, or longer than, when the largest rolling element from the plurality of rolling elements rolls off and rotates once without sliding. [2] Electrical discharge machine according to claim 1, wherein the control circuit is configured such that it determines, by comparing a movement speed (Vd, Vu) in the movement of the electrode holder in the drive direction with a predetermined reference speed, whether an irregularity occurs in the resistance to the movement of the electrode holder. [3] Electrical discharge machine according to claim 2, wherein The speed of movement compared to the reference speed: corresponds to a movement speed of the electrode holder when the electrode holder moves from a predetermined initial position in a predetermined direction towards the workpiece, thus initiating single-hole machining; or corresponds to a movement speed of the electrode holder when the electrode holder is returned to its original position in the predetermined direction after the single-hole machining is complete. [4] Electrical discharge machine according to claim 1, wherein the control circuit is configured in such a way that it detects that an irregularity occurs in the resistance to the movement of the electrode holder when a first condition and / or a second condition is met, where the first condition corresponds to a condition that a first velocity of movement (Vd) in a first direction in the driving direction of the electrode holder is lower than a first reference velocity (Vd0), where the second condition corresponds to a condition that a second movement velocity (Vu) in a second direction opposite to the first direction in the drive direction of the electrode holder is lower than a second reference velocity (Vu0). [5] Electrical discharge machine according to one of claims 1 to 4, wherein the control circuit is configured such that it determines whether an irregularity occurs in the resistance to the movement of the electrode holder by comparing a first movement speed (Vd) in a first direction along the drive direction of the electrode holder with a second movement speed (Vu) in a second direction opposite to the first direction along the drive direction of the electrode holder. [6] Electronic discharge machine according to any one of claims 1 to 5, further comprising: a discharge state detection circuit which detects a discharge state between the electrode and the workpiece in order to generate a discharge state signal, and outputs the discharge state signal, the control circuit is configured such that: The electrode holder moves in the drive direction based on the discharge state signal output by the discharge state detection circuit, so that when the electrode and the workpiece are short-circuited, the electrode moves away from the workpiece in one direction; and Furthermore, based on this, if a time period during which the electrode and the workpiece are short-circuited exceeds a reference time (Ts), it is determined that an irregularity in the resistance to the movement of the electrode holder occurs. [7] Electronic discharge machine according to one of claims 1 to 6, wherein the control circuit is configured such that it moves the electrode holder based on an irregularity which occurs in the resistance to the movement of the electrode holder both in a first direction and in a second direction opposite to the first direction along the drive direction of the electrode holder, such that the electrode holder is moved through a movement path when the largest rolling element from the plurality of rolling elements rolls off and rotates once without sliding. [8] Method for producing a machined object, comprising: a step for providing a workpiece for the machined object in relation to an electrical discharge machine according to any one of claims 1 to 7; and a step to process the workpiece using the electrical discharge machine.