JP2006224258A - Diesinking electric discharge machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To drive a tool electrode having a wide width size by a comparatively small-sized linear motor and drive the tool electrode even by a rotary servo motor as needed. <P>SOLUTION: The diesinking electric discharge machine is provided with a quill 3 mounting the tool electrode so as to relatively move by the linear motor in a Z axis direction with respect to a ram 1F, and to allow a slider 6 to move in the Z axis direction by rotating a ball screw by the rotary servo motor 5 fixed to the ram 1F. The connection and separation of the slider 6 and the quill 3 are made by a hydraulic cylinder 81 of a connection/separation device 8. The quill 3 is driven by the linear motor during separation, and driven by the rotary servo motor 5 during connection. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a die-sinking electric discharge machine that performs electric discharge machining of a workpiece on a table with a tool electrode. More specifically, the present invention has a control axis for moving the tool electrode or the workpiece in the vertical direction. The present invention relates to a die-sinking electric discharge machine in which a driving system for driving a moving body to which a tool electrode or a workpiece is attached is switched in accordance with the weight or size of the workpiece.

  A tool electrode is disposed at a position opposite to the workpiece, and a predetermined machining voltage is applied to the machining gap formed between the workpiece and the tool electrode to intermittently generate a discharge. A sculpture electric discharge machine is widely used for processing a slab into a desired hole shape.

  In contrast to cutting in general machine tools, a sculpture electric discharge machine performs a so-called servo operation that relatively moves a tool electrode or a workpiece so as to maintain a machining gap at a predetermined distance. There is a need. Further, in order to efficiently discharge the chips staying in the machining gap, it is necessary to perform a so-called jump operation in which the tool electrode is reciprocated at least a predetermined distance in the vertical direction with respect to the workpiece. The servo operation and jump operation are required to be performed at a higher speed and with higher responsiveness.

  In order to satisfy this requirement, in Patent Document 1, a small spindle independent from the spindle head is provided in addition to the spindle head. For example, when electric discharge machining is performed using a small tool electrode such as rib groove machining, There is disclosed a die-sinking electric discharge machine that performs machining with a small spindle having a small diameter. Also, in order to perform servo operation and jump operation at high speed, high response, and high acceleration, the drive method using a linear motor compared to the drive method using a combination of a rotary servo motor, ball screw and nut (rotary servo motor drive method) ( Linear motor drive system) is considered advantageous, and Patent Document 2 discloses a die-sinking electric discharge machine capable of performing servo operation and jump operation using a linear motor drive system.

  Patent Documents 3 and 4 describe that in the linear motor drive system, it is advantageous that the quill is a mover of the linear motor.

By the way, in the linear motor drive system, when the weight of the tool electrode is increased, the mass of the entire moving part is increased. It is necessary to increase the thrust of the linear motor. However, as the thrust of the linear motor is increased, a dilemma occurs in which the mover becomes larger and the entire moving part becomes heavier. In addition, when the size (area) of the tool electrode is large, for example, in EDM using the machining fluid as the processing medium, the tool electrode may be pulled up like a jump motion or lowered so as to return to the original position. In this case, the positive pressure and the negative pressure are increased, so that the state of impossibility of movement occurs due to momentary or continuous thrust shortage. Therefore, as disclosed in Patent Document 5, a configuration in which a linear motor drive system is basically used regardless of the size of the tool electrode or the workpiece has been proposed.
Japanese Patent No. 3427172 JP-A-5-104332 Japanese Patent No. 3542508 Japanese Patent No. 3315945 JP 2000-225527 A

  The die-sinking electric discharge machine disclosed in Patent Document 1 is a parallel 2 that uses separate moving bodies for a tool electrode that can be machined by a linear motor drive system and a tool electrode that is difficult to machine by a linear motor drive system. Since the shaft structure is adopted, it can be processed by a linear motor drive method only with a small tool electrode. Temporarily, a linear motor drive type small spindle head is enlarged, and a linear motor with a thrust suitable for it is mounted, and a normal size tool electrode, for example, a tool electrode with a mass of 5 kg or more including an electrode holder is attached. If it is possible, it is difficult to balance the entire machine, and it is easy to lose straightness and parallelism, or to easily fall and yaw. As a result, the required processing accuracy may not be obtained. In particular, in the case of a configuration in which a small moving body is provided on the side surface of a large moving body, there is a problem that stability is significantly impaired.

  In addition, in the case of the parallel biaxial structure disclosed in Patent Document 1, the rigidity of the uniaxial structure is weakened, so the size of the tool electrode that can be moved by the linear motor must be made smaller. In order to obtain the rigidity that can withstand the use of a large size tool electrode, the structure will become larger if the structure is made stronger and more durable, which causes the contradiction that the linear motor must also have a larger thrust. It also has the problem of becoming.

  Furthermore, in the case of a structure in which a small moving body is built in a relatively large moving body, a large linear motor is required due to problems such as a space where a linear motor member such as a coil can be installed and a cooling structure for cooling a heat generating coil. Can not be installed, and only a linear motor with relatively small thrust can be installed due to its structure. As a result, there is a problem that the linear motor driving method can be adopted only for extremely small tool electrodes.

  An object of the present invention is to provide a die-sinking electric discharge machine capable of solving the above-mentioned problems in the prior art.

  Another object of the present invention is to provide a sculpting electric discharge machine having a stable structure that can use a wide range of tool electrodes and has excellent balance performance.

  Another object of the present invention is to provide a die-sinking electric discharge machine having a structure that can reduce the size of the linear motor relative to the size of the tool electrode and that does not sacrifice the rigidity of the structure as much as possible.

  Another object of the present invention is to provide a die-sinking electric discharge machine having a structure capable of mounting a linear motor having a large thrust.

  In order to solve the above problems, according to the present invention, a member for attaching a tool electrode or a workpiece to the lower end surface is provided so as to be movable in a given uniaxial direction with respect to a ram or a column. A movable body, a linear motor for moving the movable body in the uniaxial direction, a rotary servo motor attached to the ram or column, and a rotary servo motor disposed along the uniaxial direction and rotated by the rotary servo motor An electric discharge machining apparatus comprising: a ball screw to be moved; a slider that moves in the uniaxial direction in accordance with rotation of the ball screw; and a coupling / separating device for coupling and separating the movable body and the slider. Proposed.

  The primary side member and the secondary side member constituting the linear motor can be appropriately provided on the moving body and the ram or column. That is, the primary side member may be provided on the moving body and disposed so as to face the secondary side member, or the secondary side member is provided on the moving body, and the primary side member is primary on either the ram or the column. You may arrange | position so that a side member may be opposed.

  According to the present invention, a wide range of tool electrodes can be driven by a relatively small linear motor, and if necessary, the tool electrodes can also be driven by a rotary servo motor.

  Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing an overall configuration of an example of an embodiment of an electric discharge machine according to the present invention. In the sculpture electric discharge machine 1 shown in FIG. 1, 1A is a bed, 1B is a column erected on the rear side or upper surface of the bed 1A, and 1C is a horizontal axis (Y 1D is a table provided on the saddle 1C so as to be movable in the direction of another horizontal axis (X axis), and 1E is provided on the front side of the “table 1D” of the “column 1B”. It is a processing tank.

  The processing tank 1E is provided with a surface plate (not shown) for disposing a workpiece (not shown) in a state of being immersed in the processing liquid and facing the tool electrode E. And the ram 1F is being fixed to the upper end part of the column 1B, and the process head part 2 is provided in the front-end | tip part 1Fa of the ram 1F. Here, MX is an X-axis servo motor, MY is a Y-axis servo motor, and the processing tank 1E is moved and positioned in the X-axis and Y-axis directions on the bed 1A by these servo motors. It has become.

  The processing head unit 2 includes a quill 3, and the quill 3 is guided by a guide rail 22 formed on a quill base 21 provided at the tip 1 </ b> Fa of the ram 1 </ b> F and is perpendicular to the upper surface of the bed 1 </ b> A (Z It is provided so as to be movable in the axial direction. A plurality of bearing units 4 are attached to the quill 3, and the quill 3 is guided to the guide rail 22 by these bearing units 4, and the quill 3 is a linear motor provided in the machining head portion 2 as described later. 9 (see FIG. 2). FIG. 3 shows in detail how the bearing unit 4 is attached to the quill 3.

  Reference numeral 5 denotes a rotary servo motor fixed to the quill base 21. A slider 6 is provided so that the quill 3 can be driven by the guide of the guide rail 22 also by the rotary servo motor 5. Yes.

  Thus, the machining head portion 2 is eventually provided with a moving body (quill 3) so as to be movable in a given uniaxial direction (here, the Z-axis direction) with respect to the column 1B or the ram 1F. The moving body can be moved in the Z-axis direction by the linear motor 9 or the rotary servo motor 5. The machining head unit 2 further includes a ball screw 7 that is disposed along a given uniaxial direction and is rotationally driven by a rotary servomotor 5. The ball screw 7 cooperates with the slider 6 and is configured to move the slider 6 in a uniaxial direction according to the rotation of the ball screw 7.

  The processing head unit 2 includes a coupling / separating device 8 for coupling and separating the quill 3 and the ball screw 7. When the quill 3 is separated from the slider 6 by the coupling / separating device 8, only the slider 6 moves in one axial direction even when the rotary servo motor 5 rotates. On the other hand, when the quill 3 and the slider 6 are in an integrated state by the coupling / separating device 8, when the rotary servomotor 5 rotates and the slider 6 moves in the uniaxial direction, the quill 3 is separated from the slider 6. By moving together, the quill 3 can be moved in one axial direction by the rotary servomotor 5.

  Next, the configuration of the machining head unit 2 will be described in detail with reference to FIGS.

  First, the linear motor 9 will be described. As described above, the quill 3 is configured to be guided along the guide rail 22 by the bearing unit 4 and move in the Z-axis direction (see FIG. 3). In order to move the quill 3 along the guide rail 22 in the Z-axis direction, the quill base 21 is provided with an exciting coil 91 constituting a primary stator of the linear motor 9 using a mounting frame 93 ( 4), the quill 3 is provided with a magnet plate 92 that constitutes a secondary side mover of the linear motor 9 so as to face the excitation coil 91, and includes the excitation coil 91 and the magnet plate 92. A linear motor 9 is configured. In the present embodiment, the excitation coil 91 is attached to the quill base 21 and the magnet plate 92 is attached to the quill 3. However, the excitation coil 91 is attached to the quill 3 and the magnet plate 92 is attached to the quill base 21. Good.

  In the linear motor, heat generation on the primary side (coil side) becomes a problem. The efficiency may decrease due to the heat loss of the primary side heat generation, and the rated thrust cannot be obtained. Therefore, in the case of a relatively large linear motor used for a machine, a cooling mechanism for cooling the coil may be required. For cooling, a cooling medium such as water is used, and a cooling pipe is provided. As described above, since the primary side requires wiring and heat generation occurs, and cooling piping is required. Therefore, the primary side stator is attached to the quill base 21 as in the present embodiment. Is advantageous. One of the primary side stator and the secondary side mover needs to be long enough to move the moving body (so-called movement stroke). Since it is disadvantageous to arrange the coils for the moving stroke, the permanent magnets are arranged in this embodiment. The cooling pipe can use a known configuration as disclosed in Patent Document 3, and illustration and detailed description thereof are omitted.

  Therefore, the quill 3 can be moved along the Z-axis direction by supplying a driving current to the exciting coil 91 from a driving power supply unit (not shown). At this time, the position of the quill 3 that is moving or stopped can be detected by the linear scale 23 (see FIG. 3). Regardless of the drive system, in other words, the electric discharge machine of the present invention only needs to be provided with one position detector (linear scale) regardless of the size of the tool electrode used.

  Reference numerals 31 and 32 denote a pair of air cylinders fixed to the slider 6, and serve as a balancer when the linear motor 9 is used to drive the quill 3. The quill base 21 is provided with a brake device 33, which is used to give a required braking action to the quill 3 when the linear motor 9 is used. For more detailed configurations and operations of the air cylinders 31 and 32 and the brake device 33, refer to Patent Document 4.

  At the lower end of the quill 3, an automatic clamping chuck 34 that can position and attach the tool electrode attached to the electrode holder is provided. The face plate 35 is provided so as to cover the automatic clamping chuck 34, and a relatively large tool electrode can be attached thereto. Therefore, when processing using a relatively small tool electrode, the tool electrode is attached to the electrode holder, the face plate 35 is removed, and the electrode holder is attached to the automatic clamping chuck 34. Thus, by moving the quill 3 in the Z-axis direction by the linear motor 9, the tool electrode attached to the lower end of the quill 3 can be moved relative to the workpiece for electric discharge machining. .

  Next, a configuration for moving the quill 3 in the Z-axis direction using the rotary servomotor 5 will be described. The ball screw 7 is connected to the rotary shaft 51 of the rotary servomotor 5 at one end on the rotary servomotor 5 side by a coupling 52, and the screw portion 71 of the ball screw 7 is a nut fixed to the slider 6. 61 is screwed.

  As shown in FIG. 5, the bearing unit 4 is also attached to the slider 6, and the slider 6 is guided along the guide rail 22 by the bearing unit 4 in the same manner as in the case of the quill 3. ing. Here, 6A is a through hole for penetrating the brake shaft of the brake device 33, 6B is a mounting hole for mounting the nut 61, and 6C is a mounting plate for mounting a hydraulic cylinder 81 to be described later.

  Therefore, when the rotary servo motor 5 is actuated by receiving electric power from a driving power supply unit (not shown) and the rotary shaft 51 rotates, the ball screw 7 also rotates and is guided to the guide rail 22 by the bearing unit 4. The slider 6 is configured to move upward or downward according to the rotation direction of the rotary shaft 51. The position of the slider 6 shown in FIG. 3 is an upper limit position, and the slider 6 can be fixed to the upper limit position by a stopper mechanism 62 as will be described later.

  Next, the coupling / separating device 8 will be described. The coupling / separating device 8 includes a hydraulic cylinder 81 fixed to the slider 6, and a piston rod tip portion 82 </ b> A of the piston 82 of the hydraulic cylinder 81 extends into the hollow portion 3 </ b> A of the quill 3. The piston rod tip portion 82A is provided with a clamp portion 83 so that the piston 82 cannot escape from the hole 3B through which the piston 82 is inserted into the hollow portion 3A of the quill 3. Basically, clamping is performed by the hydraulic force of the hydraulic cylinder 81, but a lock mechanism 84 is provided near the hole 3B for safety.

  The lock mechanism 84 will be described in detail with reference to FIGS. The lock mechanism 84 includes an actuator 84A that is mainly an air cylinder fixed to the back of the quill 3, a lock pin 84B that slides with the actuator 84A, and a lock member 84C that is provided on the lock pin 84A and supports the clamp portion 83 from below. It consists of. When the rotary servomotor 5 is used, the lock pin 84B is moved forward with the piston 82 pulled up, and the lock member 84C supports the clamp portion 83 from below, so that the hydraulic cylinder 81 can be used in the event of an emergency. It is configured to lock so that the clamp does not come off.

  In a state where the hydraulic cylinder 81 is operated and the piston 82 is pulled up (the state shown in FIG. 6), the quill 3 is pressed against the slider 6 by the clamp portion 83 that cannot come out of the hole 3B. Are integrated (combined state). Therefore, in this case, when the slider 6 is driven by the rotary servo motor 5, the quill 3 moves in the Z-axis direction together with the slider 6. At this time, the stopper mechanism 62 operates an actuator 62A composed of a cylinder operated by hydraulic pressure or compressed air to retract the stopper pin 62B, and pulls out the stopper pin 62B from a retaining hole 62C provided on the back surface of the slider 6. The slider 6 can be moved.

  When the slider 6 and the quill 3 move together, the air cylinders 31 and 32 also move and cannot be operated as a balancer. However, the slider 6 is provided with a counterweight balance 63 of a weight type, Even so, a sufficient counterweight is given (see FIG. 2).

  On the other hand, in a state where the hydraulic cylinder 81 is operated and the piston 82 is lowered (the state shown in FIG. 7), the clamp portion 83 is in a free state with respect to the quill 3, and between the quill 3 and the slider 6. Integration is not established and the quill 3 and the slider 6 are in a separated state. Specifically, the actuator 84A is operated to retract the lock pin 84B to release the lock, and the hydraulic cylinder 81 is operated to lower the clamp portion 83 to the back of the hollow portion 3A of the quill 3. Further, the slider 6 is raised to the upper limit position, the actuator 62A of the stopper mechanism 62 is operated to advance the stopper pin 62B, the stopper pin 62B is inserted into the retaining hole 62C of the slider 6, and the slider 6 is inserted into the upper limit position. To ensure that it is fixed securely.

  Therefore, in this case, even if the slider 6 and the cylinder portion of the hydraulic cylinder 81 provided on the slider 6 are not moved, the quill 3 is linearly restrained with respect to the slider 6 and the hydraulic cylinder 81. The motor 9 can move independently of the slider 6. As can be seen from the above description, the coupling / separating device 8 and the slider 6 constitute power switching means for switching the power of the quill 3, in other words, means for switching between the linear motor 9 and the rotary servo motor 5.

  FIG. 8 is a diagram for explaining the operating state of the sculpting electric discharge machine 1. As shown in FIG. 8A, when the piston 82 of the hydraulic cylinder 81 of the coupling / separating device 8 is pushed downward, the quill 3 can move independently of the slider 6. (Separated state). Therefore, in this case, the quill 3 can be driven independently from the slider 6 by the linear motor 9 if the slider 6 is held at the upper limit position shown in the figure. This drive mode is suitable for electric discharge machining using a normal tool electrode. In the case of the electric discharge machine of the embodiment, the maximum mass of the tool electrode that can be machined by the linear motor drive system is 50 kg.

  On the other hand, as shown in FIGS. 8B and 8C, the piston 82 of the hydraulic cylinder 81 of the coupling / separating device 8 is lifted and the quill 3 is pressed against the slider 6 so that both are integrated. If there is, the quill 3 moves together with the slider 6 when the slider 6 is driven via the ball screw 7 by the rotary servo motor 5. Therefore, in this case, the quill 3 can be driven by the rotary servomotor 5 if the power supply to the linear motor 9 is turned off. This drive mode is suitable for electric discharge machining using a relatively large tool electrode. As already described, the position of the quill 3 is detected by the scale 23 in any drive mode. The exciting coil mounting frame 93 is fixed to the quill base 21.

  Since the die-sinking electric discharge machine 1 is configured as described above, it has the following advantages.

  Since the quill 3 can be driven by switching between the linear motor driving method and the rotary servo motor driving method, a wide-sized tool electrode can be used. In addition, since the moving body that moves in the vertical direction is always the quill 3 even when the driving method is switched, the machining head portion 2 can have a balanced structure with the quill 3 as the center, and stable discharge can be achieved. Processing can be realized. In the present embodiment, the air cylinders 31 and 32 cannot be arranged coaxially with the central axis of the quill 3 because of the hydraulic cylinder 81, but are balanced because they are provided in two pairs with the hydraulic cylinder 81 interposed therebetween. It has a structure. Therefore, compared with the conventional parallel biaxial structure, the balance of the whole machine is excellent and the required processing accuracy can be obtained.

  Even if the drive system is switched, the moving body that moves in the vertical direction is the quill 3 in any case, so basically the entire structure of the machining head unit 2 is the same as the linear motor drive system single-axis structure. it can. Therefore, the rigidity does not become weaker than that of the conventional linear motor drive system single shaft structure. And rigidity can be made high compared with the conventional parallel biaxial structure. For this reason, the rigidity of the structure is not sacrificed even if the system switches between the linear motor driving system and the rotary servo motor driving system. In particular, this is an advantageous structure in a die-sinking electric discharge machining apparatus that reciprocates a heavy tool electrode at a high speed and a high acceleration, and it is possible to minimize an adverse effect on accuracy and to secure machining accuracy.

  As is apparent from the above description, the moving body (quill 3) of the machining head unit 2 is not a structure in which a small moving body is built in a relatively large moving body. The installation space of the linear motor can be secured to the same extent as the structure. Therefore, it is possible to install a linear motor having a sufficiently large thrust, and it is possible to install a linear motor having a larger thrust as compared with a conventional structure including a parallel two-axis system, particularly a small moving body.

  In the present embodiment, the coupling / separation device 8 that couples the quill 3 and the slider 6 is configured using the hydraulic cylinder 81. However, the coupling / separation device 8 may have a configuration in which a mechanism for coupling the quill 3 and the slider 6 is separately provided by strongly clamping manually without using a hydraulic cylinder. In this case, the quill 3 and the slider 6 can be more firmly and reliably coupled. However, this does not lose the advantage of the configuration using the hydraulic cylinder as the coupling / separating device, and the configuration of the embodiment can be processed with a maximum of 300 kg of tool electrode, and the tool electrode has several hundred kg. In this range, the coupling / separation apparatus using the hydraulic cylinder capable of automatically switching the driving method is excellent in convenience.

  In the sculpture electric discharge machine 1 according to the present invention, the same quill 3 moves in any of the linear motor drive system and the rotary servo motor drive system. ). Even if separate guide rails are provided for the slider 6 and the quill 3, the effects of the present invention can be obtained. This is one of the advantages of the electric discharge machine 1 according to the embodiment, but this is not essential.

The schematic block diagram which shows the whole structure of the die-sinking electric discharge machine by this invention. FIG. 2 is a front view showing a part of a machining head portion of the electric discharge machine shown in FIG. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 2 is a top view of a machining head portion of the electric discharge machine shown in FIG. 1. The perspective view which shows the principal part of the slider vicinity shown in FIG. The figure for demonstrating the detailed structure of a locking mechanism, and the figure which shows the state in which the quill and the slider were integrated. The figure for demonstrating the detailed structure of a locking mechanism, and the figure which shows the state by which the quill and the slider were isolate | separated. The figure for demonstrating operation | movement of the process head part of the die-sinking electric discharge machine shown in FIG.

Explanation of symbols

2 Processing Head 3 Quill 4 Bearing Unit 5 Rotary Servo Motor 6 Slider 7 Ball Screw 8 Coupling and Separating Device 9 Linear Motor 21 Quill Base 22 Guide Rail 33 Brake Device 34 Automatic Clamping Chuck 35 Face Plate 51 Rotating Shaft 52 Coupling 61 Nut 71 Screw part 81 Hydraulic cylinder 82 Piston 83 Clamp part 84 Lock mechanism 91 Excitation coil 92 Magnet plate 93 Mounting frame

Claims (3)

A movable body having a member for attaching a tool electrode or a workpiece to a lower end surface and provided so as to be movable in a given uniaxial direction with respect to a ram or a column;
A linear motor for moving the movable body in the uniaxial direction;
A rotary servo motor attached to the ram or column;
A ball screw disposed along the uniaxial direction and rotated by the rotary servomotor;
A slider that moves in the uniaxial direction according to the rotation of the ball screw;
A die-sinking electrical discharge machining apparatus comprising a coupling / separating device for coupling and separating the movable body and the slider.   The EDM apparatus according to claim 1, wherein the coupling / separating device includes a hydraulic cylinder and a clamp member.   The electric discharge machining apparatus according to claim 1, wherein the movable body is a mover of the linear motor.

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