JPH08309620A - Diesinking electric discharge machine - Google Patents

Abstract

PURPOSE: To provide a diesinking electric discharge machine having high working accuracy and high reliability. CONSTITUTION: A diesinking electric discharge machine, in which electrodes are arranged opposite to each other through a work W and a discharge space, performs a desirable-shaped discharge to the work W in response to the electrode shape with the relative feeding between the work W and the electrodes. Linear motors 20, 26, 34 are incorporated in a feeding mechanism for giving the relative feeding between the work W and the electrodes, and the relative feeding is performed by the direct drive of the linear motors 20, 26, 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die sinking electric discharge machine, and more particularly to a die sinking electric discharge machine using a linear motor as a feed drive source.

[0002]

2. Description of the Related Art A die-sinking electric discharge machine mounts a work to be processed on a work table mounted on a base (bed), and, on the other hand, a stationary machine such as a column standing upright from the base with respect to this work. Holds on the frame and approaches the work,
An embossing electrode removably held on an electrode holder composed of a spindle at the tip of a spindle head (head) that can be separated from each other is brought close to the workpiece while maintaining a predetermined discharge gap. Pulsed discharge pressure is applied between the engraving electrode and the work to be processed into a shape having a correspondence relationship with the shape of the electrode by the discharge energy. At this time, a relative feed movement is performed between the work and the electrode according to the progress of the electric discharge machining so as to maintain the above-mentioned predetermined discharge, but this feed movement is generally performed by the head or the work. Three orthogonal axes (X axis, Y axis)
(Z axis, Z axis) feeding mechanism is provided.

[0003] Typically, a Z-axis feed for vertically moving a head having a main shaft for electrode mounting, and an X-axis for moving a work table on which a work is mounted in two axial directions of an X-axis and a Y-axis. Feeding, Y-axis feeding, or a system with a tri-axis feeding mechanism, or the work table is kept stationary, and the head is mounted along with the Z-axis feeding by inserting the ram mechanism into a column that is erected on the bed. A method in which the head is moved in both directions of the X-axis and the Y-axis, and the head is mounted on the ram mechanism, so that the head is finally fed in the three-axis directions of the X-axis, the Y-axis, and the Z-axis. Has been taken.

In the conventional shaft feed mechanism of a die-sinking electric discharge machine, a drive source is formed by a servomotor, a ball screw shaft is connected to an output shaft of the servomotor, and a nut element screwed to the ball screw is a head. It is provided integrally with a driven body such as a work table, a ram mechanism, etc., so that the driven body undergoes rotation-linear motion conversion in accordance with the control rotation of the servo motor, and the driven body has a predetermined axis such as the X axis, Y axis, Z axis or the like. It is configured to provide directional feed movement.

[0005]

According to the above-mentioned conventional shaft feed mechanism, the shaft joint, the ball screw shaft, the shaft joint, the ball screw shaft, and the like are inevitably provided between the servo motor and the head, work table, ram mechanism, etc. forming the driven body. Since various movable elements such as nut elements and nut holders involved in the rotation-linear motion conversion are interposed, the number of parts is large and there is a trouble that assembly and adjustment are required.

Further, the interposition of various movable elements associated with the rotation-linear motion conversion causes each element to elastically deform during operation, for example, the ball screw shaft elastically deforms by meshing with the nut element. As a result, a large number of non-negligible spring constant elements intervene in the motion system of the shaft feed mechanism, and the gain of the motion system cannot be increased so much, which causes a slow response. As described above, the slow response of the motion system including the servomotor makes it difficult to control the minute discharge gap between the workpiece and the electrode in the die-sinking EDM machine, and thus the EDM performance is improved. This will be one of the causes of the decrease.

Further, these parts are subject to wear when they are used for a long period of time, and it is impossible to avoid the occurrence of a lead error on the ball screw shaft. It was. Therefore, an object of the present invention is to provide a die-sinking electric discharge machine in which, in order to solve such a problem, a linear motor, which has recently been remarkably improved in practicality, is adopted as a drive source of a shaft feed mechanism. It is a thing.

[0008]

According to the present invention, electrodes are opposed to a work through a discharge gap, and the work is provided with a desired shape corresponding to the shape of the electrode according to relative feed between the work and the electrode. In a die-sinking electric discharge machine that performs electric discharge machining,
A die-sinking electric discharge machine is provided in which a feed mechanism for providing relative feed between the work and the electrode incorporates a linear motor, and the relative feed is obtained by direct drive by the linear motor.

It is preferable that the feeding mechanism is constituted by an axial feeding mechanism in three orthogonal directions (X axis, Y axis, Z axis).
Each of the shaft feed mechanisms uses a linear motor as a drive source and obtains a smooth linear feed movement via a linear guide device.

[0010]

According to the above-mentioned structure, various movable elements intervening in each system of the shaft feed mechanism of the die-sinking electric discharge machine are swept away, and the linear motor of the driving force generating source and the driven body are separated. As a result of establishing a one-to-one mechanical relationship between them, it is possible to solve the above-mentioned various problems of the related art, and to reduce the weight and cost.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a front view showing one embodiment of the die-sinking electric discharge machine according to the present invention applied to ram-shaped die-sinking EDM, and FIG. 2 is a Z provided on the same spindle head (head).
FIG. 4 is a schematic partial perspective view showing the structure of the shaft feeding mechanism in detail, and FIG. 3 is a schematic partial perspective view showing the shaft feeding mechanism that imparts a feed movement in the Y-axis direction to the ram mechanism of the embodiment. is there. Further, FIG. 4 is a front view showing an embodiment applied to table-shaped die-sinking electric discharge machining of the die-sinking electric discharge machine according to the present invention.

Referring to FIG. 1, a ram-shaped carving electric discharge machine is provided at a lower bottom portion for storing a machining fluid supplied to the electric discharge machining section, and a machining fluid storage tank 12 from which the machining fluid is circulated. Is provided. This processing liquid storage tank 12
A bed 114 in the form of a plate is provided above the bed.
A work table 16 is disposed in a machining tank 15 in a substantially half region of the work table 4 in the same manner.
A work W, which is a workpiece, is mounted and held on the workpiece 6.

On the other hand, a column 18 is erected in the rear half region of the work table 16, and a column motor 18 and a linear guide mechanism 22 are provided at the top end of the column 18 in a uniaxial direction (for example, the X-axis). A saddle 24 which is movable in the direction) is provided. This saddle 24 has the uniaxial direction (X
The ram 3 is provided so as to be capable of feeding and moving in the axial direction), and the ram 3 is provided on the top in the direction of another axis (Y axis direction) orthogonal to the above-mentioned one axis direction.
It is provided with a linear motor means 26 constituting a shaft feed mechanism for giving a feed movement to 0 and a linear guide mechanism not shown in the drawing.

A head column 32 is provided upright in the front end region of the ram 30 and has a vertical surface on a front surface 32a. A linear motor means 34 is provided on the front surface 32a of the head column 32.
And a head 36 through a linear guide mechanism (not shown).
Is provided so as to be movable in the Z-axis direction orthogonal to the above-mentioned X-axis and Y-axis, and at the lower end of the head 36, an electrode holder 38 holding a stamped electrode (not shown) is also rotatable about the vertical axis. Is provided and forms the main axis. In this way, the saddle 24, the ram 30, and the head 36 are driven by linear drive using the linear motor means 20, 26, and 34 as driving sources in the directions of the three orthogonal axes, and therefore, the ball screw shaft, the nut element, and the nut. It has a structure capable of cleaning away movable elements such as a holder, which are conventionally required.

A counterbalance means 40 is always provided for the movement of the head 36 in the Z-axis direction, and the counterbalance means 40 can also stop the head 36 at a predetermined position in the Z-axis direction. Further, a stop plate 42 is provided on the upper end of the head column 32, and defines the upper limit of movement of the head 36. Here, each of the linear motor means 20, 26, 34, etc. has an N pole, an S pole
A stationary body formed by sequentially arranging a plurality of fixed magnets having pole faces in a linear direction, and a built-in exciting coil that electromagnetically interacts with each fixed magnet of the stationary body. A traveling rail that is composed of a movable coil body that is provided so as to move in a predetermined linear direction that coincides with the extending direction, and that extends along the traveling direction of such a linear motor, and slides on the traveling rail. A linear motor having such a structure is designed to linearly move each driven body such as the saddle 24, the ram 30, the head 36, and the like according to the guide of a linear guide device including a dynamically engaged sliding foot. For example, it is more specifically disclosed in Japanese Patent Application No. 7-30731 filed by the applicant.

The electrode holder 38 at the lower end of the head 36 is driven by the above-mentioned axial feed mechanism in the three axial directions of the X-axis, the Y-axis and the Z-axis.
The shape engraving electrode attached to the workpiece W is brought close to the work W,
Further, by applying a pulsed discharge voltage to both the work W and the electrode from a discharge source (not shown) through a predetermined minute discharge gap, the die-sinking discharge machining proceeds.

FIG. 2 shows in detail an example of the Z-axis feed mechanism using the linear motor means 34 as a drive source in the above-mentioned three-axis direction feed mechanism. The front face 32 of the head column 32 is shown in FIG.
The stationary body 50 of the linear motor 34 is provided in a, and on the other hand, it is installed on the back side of the head 36 with the fixed magnet group of the stationary body 50 with a small gap, and moves linearly by electromagnetic interaction. The movable coil body 52 is provided, and the head 36
It is fixed together with. The movable coil body 52 can be supplied with an exciting current from an exciting power source (not shown) through an appropriate wiring circuit.

On the other hand, a pair of linear rails 56, 56 in the linear guide device 54 are provided on both sides of the head column 32, and the linear rails 56 are formed integrally with the frame of the head 36 or have appropriate screws such as fixing screws. Sliding feet 58, 58 integrally attached to the frame by fixing means are provided, and the head 3
6 has a configuration for guiding the smooth linear movement of 6. The linear motor means 34 thus has the stationary body 50 and the movable coil body 52 as constituent elements, and has a pair of linear rails 5.
The head 36 can be smoothly fed and moved in the Z-axis direction by a linear guide device 54 formed by 6, 56 and a pair of sliding feet 58, 58.

FIG. 3 shows in detail the structure of the Y-axis feed mechanism provided between the upper surface of the saddle 24 provided at the top of the column 18 and the bottom surface of the ram 30 and using the linear motor means 26 as a drive source. The ram 30 has a stator 60 that forms a stationary body of the linear motor 26 on its bottom surface, and a rotor 62 that forms a movable coil body that obtains a linear driving force by electromagnetic interaction with the stator 60 has an upper surface of the saddle 24. It is fixed to. In this mechanism, the rotor 62 side is kept stationary in the Y-axis direction, and the stator 60 is fed and moved integrally with the ram 30 in the Y-axis direction. The head column 32 is provided so as to move integrally in the Y-axis direction as the ram 30 moves in the Y-axis direction.

At this time, a pair of linear rails 66, 66 of a linear guide device 64 are provided on both sides of the bottom surface of the ram 30, and two front and rear rails 66, 66 are slidably engaged with the linear rails 66, 66. Sliding feet 68, 68 are integrally formed on the upper surface of the saddle 24. Of course, the separately formed sliding feet 68, 68 may be attached and fixed to the top surface of the saddle 24 with a fixing bolt or the like.

The ram 3 equipped with the linear guide device 64 described above.
0 drives the linear motor means 26 as a drive source to move in the Y-axis direction, and moves the head 36 through the head column 32.
It is possible to impart a feed movement in the Y-axis direction to the shaped electrode held by the electrode holder 38 provided at the tip of the. In addition, in the bottom surface region of the saddle 24, an X-axis system axis feed mechanism using a linear motor means 20 for linearly feeding and moving the saddle 24 in the X-axis direction orthogonal to the Y-axis direction and the Z-axis direction is provided. There is.

As described above, the ram-shaped carving electric discharge machine having the feed mechanism in the three axial directions of the X-axis, the Y-axis and the Z-axis driven by the linear motor means 20, 26 and 34 is used. Since it has a structure in which the three linear motor means 20, 26, and 34 are linearly attached to the driven body, unlike the conventional electric discharge machine, the movable elements such as the ball screw mechanism, the nut element, and the nut holder are swept away. Since it can be removed, the spring constant element due to the elastic deformation of each element can be eliminated from the motion system, and therefore there is no fear of causing a problem such as a resonance phenomenon, so that the servo gain can be sufficiently large.
As a result, an agile and precise response can be exhibited to the drive of the driven body and the linear motor, and therefore the discharge gap between the work W and the engraving electrode can be stably maintained at a desired minute amount. As a result, it is possible to improve the conditions for electrical discharge machining and achieve die-sinking electrical discharge machining with high machining accuracy.
Moreover, since the structure of each axis feed mechanism is simplified, the cause of failure occurrence in the electric discharge machining function is reduced, and therefore the electric discharge machine can improve the reliability as a mechanical device. Of course, since the feed movement of each feed axis system can be accelerated by a high gain, it is possible to shorten the electric discharge machining time.

FIG. 4 shows another embodiment of the present invention in which a linear motor means according to the present invention is used as a drive source in a table-shaped carving electric discharge machine. In FIG. 4, the table-shaped carving electric discharge machine has a bed 74 as a bottom element, and a linear guide device 80 and a linear motor 82 are interposed on a front surface 78a in an upper region of a column 78 erected on the bed 74. The head 84 is provided so as to be movable in the Z-axis direction (vertical direction). That is, the head 84 is directly driven by the linear motor 82, and is configured to be able to perform the feed movement in the Z-axis direction according to the smooth guidance of the linear guide device 80. This head 84
An electrode holder 86 holding an engraving electrode (not shown) is provided on the lower bottom portion of the engraving electrode. Therefore, the engraving electrode itself held by the electrode holder 86 is moved in the Z-axis direction with respect to a work W described later. It is configured to receive.

On the other hand, in the upper surface area of the bed 74, a work table 76 is provided so as to be movable in the biaxial directions of the X-axis and the Y-axis, and the working liquid can be stored on the upper surface of the work table 76. The machining tank 75 is provided, and the work W to be subjected to the electric discharge machining is mounted and held in the machining tank 75. The working liquid supplied to the working tank 75 is stored in a working liquid reservoir (tank) 72 provided separately adjacent to the bed 74.

Here, the bed 74 and the work table 76
A feed movement mechanism in the X-axis direction and the Y-axis direction is provided in a layered structure between and, and an X-axis feed mechanism 94 composed of a linear motor 90 and a linear guide device 92 is provided in the upper region and a linear motor. A Y-axis feed mechanism 100 composed of a straight line guide device 98 and a linear guide device 98 is provided in the lower region. The two-axis feed mechanisms 94 and 100 can easily feed and move the work table 76 directly in the two-axis directions orthogonal to each other in the same plane by the driving force of the linear motors 90 and 96 by the cooperation of the two mechanisms. Can understand. It should be noted that the column 78 is provided with a balancer 77 for balancing during the feeding operation of the Z-axis feed mechanism of the head 84.

Also in this table-shaped carving electric discharge machine, an X-axis, Y-axis, and Z-axis three-axis feed mechanism using the above-mentioned three linear motors 82, 90, and 96 as a driving source is used for these linear motors. Since it can be fed and moved by direct drive, the ball screw shaft, the nut element, the nut holder, etc. are the same as in the case of the ram type EDM machine shown in FIGS. Since it is possible to wipe away the conventional movable element of the above, it is possible to eliminate screw lead error, backlash, etc., and to cause the feed movement of each axis under high gain. As a result, a feed movement with good responsiveness can be obtained, so by stably maintaining the electrical discharge machining gap at an appropriate minute amount,
Highly precise and high speed electrical discharge machining can be performed.

[0027]

As is apparent from the above description, according to the present invention, the electrodes are opposed to each other via the discharge gap and the workpiece is shaped into the electrodes according to the relative feed between the workpiece and the electrodes. In a die-sinking EDM machine that performs EDM of a desired shape according to, a feed mechanism that provides relative feed between the workpiece and the die-sinking electrode is equipped with a built-in linear motor. Since the die-sinking EDM machine was designed to obtain the feed, the feed movement of each axis feed mechanism can be performed by direct drive from the linear motor. Therefore, the servo system in EDM is set to a high gain. Therefore, since the responsiveness is good, the electric discharge machining performance can be improved and the machining time can be shortened by the high speed, and the electric discharge machining efficiency can be improved. Further, direct driving by a linear motor can eliminate various movable elements such as a ball screw shaft, a nut element, and a nut holder, which constitute the rotation-linear motion converting means, thereby eliminating the lead error of the screw mechanism and reducing the back error. The rush can be eliminated, and the processing accuracy can be improved in this respect as well. In addition, since it is possible to omit extra movable elements, it is possible to reduce the weight of the electric discharge machine body and simplify the mechanism, which can significantly improve the operational reliability as a mechanical device and reduce the number of mechanical elements. As a result, various effects such as contributing to cost reduction of the die-sinking electric discharge machine can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment applied to ram-shaped carving electric discharge machining of a carving electric discharge machine according to the present invention.

FIG. 2 is a schematic partial perspective view showing the structure of a Z-axis feed mechanism provided on the spindle head (head) in detail.

FIG. 3 is a schematic partial perspective view showing in detail a shaft feed mechanism that imparts a feed movement in the Y-axis direction to the ram mechanism of the embodiment.

FIG. 4 is a front view showing an embodiment applied to table-shaped die-sinking electric discharge machining of the die-sinking electric discharge machine according to the present invention.

[Explanation of symbols]

 12 ... Machining liquid storage tank 14 ... Bed 16 ... Work table 18 ... Column 20, 26, 34 ... Linear motor means 24 ... Saddle 30 ... Ram 36 ... Head 38 ... Electrode holder 54 ... Linear guide device 64 ... Linear guide device 74 ... Bed 78 ... Column 76 ... Work table 82, 90, 96 ... Linear motor 84 ... Head 86 ... Electrode holder W ... Work

Claims (1)

[Claims] 1. A die-sinking electric discharge machine in which an electrode is opposed to a work through an electric discharge gap, and electric discharge machining of a desired shape corresponding to the shape of the electrode is performed on the work according to a relative feed between the work and the electrode. A die-sinking electric discharge machine characterized in that a feed mechanism for providing relative feed between the work and the electrode incorporates a linear motor, and the relative feed is obtained by direct drive by the linear motor. .