JPH05337744A - Wire electrodischarge machining unit - Google Patents

Abstract

PURPOSE:To keep off any deterioration in form accuracy and profile precision due to uneven consumption in a wire electrode by installing a mechanism feeding a wire in the axial direction and another mechanism for rotating this wire around the axis, respectively. CONSTITUTION:During operation for electrodischarge machining, since a wire 41 travels on a workpiece 40 from top to bottom as rotating, the wire 41 comes to be opposed to the workpiece 40 in the longitudinal direction and over the whole area of its cylindrical peripheral surface in consequence. Therefore, consumption by electric discharge at the side of the wire 41 is dispersed over an overall peripheral surface of the wire 41, so uneven consumption will in no case occur at all. In addition, chips are floated by a dielectric fluid flowing into a discharge gap between the wire 41 and the workpiece 40, thus they are quickly removed from the discharge spot as adding such a wire motion running from top to bottom. In this case, as the wire 41 rotates in itself, the dielectric fluid in contact with the cylindrical peripheral surface turns to a rotating flow, through which the chips are discharged out to the sidepiece and the backside of the wire 41.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire feeding mechanism for a wire electric discharge machine.

[0002]

2. Description of the Related Art In a wire electric discharge machine, a wire runs in its axial direction while maintaining an electric discharge between a wire as one electrode and a work piece as the other electrode, and the wire and the work piece are relatively opposed to each other. The desired cutting process. In this case, the wire is also consumed due to the discharge phenomenon.

Generally, in electrical discharge machining, the problem of electrode wear becomes a problem, but especially in wire electrical discharge machining, the surface of the wire in the machining progress direction (the direction orthogonal to the wire running direction) is heavily worn. The side surface is consumed, and the back side of the wire is not consumed. That is, the wire has not been uniformly worn in the past in the circumferential direction. In addition, the processing dust generated between the electrodes at the discharge points is eliminated by the jet of the working fluid supplied from the vertical direction (axial direction of the wire), but the vertical direction is the main and the circumferential direction of the wire However, there is a delay in the removal of processing scraps.

Discharge due to the unevenly consumed electrode in this manner leads to deterioration of surface accuracy due to transfer of discharge marks on the surface of the consumed electrode, deterioration of shape accuracy due to uneven reduction of wire diameter, and wire cutting. It may cause (break). Further, the machining waste is difficult to be smoothly removed from the discharge gap in combination with the simple machining liquid supply direction as described above and the fitting and movement resistance to the rough surface roughened by the wear of the wire, It causes concentrated discharge. When the concentrated discharge occurs, not only the surface accuracy of the cut surface of the workpiece decreases but also a large discharge mark is left to make the product defective. The current electric discharge machine has a system that automatically stops electric discharge machining when a wire breakage or concentrated electric discharge is detected. May decrease.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to an electric discharge machining apparatus capable of uniformly distributing the wear of the wire over the entire cylindrical surface of the wire and quickly discharging machining scraps at the electric discharge machining location. The challenge is to provide.

[0006]

In a wire electric discharge machine, in addition to a mechanism for feeding a wire in the axial direction, a mechanism for rotating the wire around the axis is provided.

[0007]

The rotation of the wire causes the wire to function as an electrode having a rotating cylindrical surface. The rotation of the wire swiftly eliminates the machining waste attached to the wire and staying at the electric discharge machining point.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 3, a wire electric discharge machining apparatus 1 comprises a control section 2, a mechanical section 3 and auxiliary equipment such as a machining fluid adjusting apparatus (not shown). The control unit 2 is the same as that in the conventional wire electric discharge machining apparatus, and has a machine sequence control function, a machining program processing / execution function, and various necessary data input / storage functions. Machine part 3
A column 5 is erected vertically on the base 4, and the column 5
The upper arm 6 and the lower arm 7 are horizontally projected in the same direction in the upper part and in the lower part, respectively. The base 4 comprises an xy table (not visible in the figure), on which the work table 8 is provided. The wall of the workpiece table 8 on the column 5 side is formed in a gate shape so that the lower arm 7 can pass therethrough and can be relatively moved to the left and right (x direction). These configurations are not different from the structure of the conventional wire electric discharge machine.

An upper wire guide device 9 is attached to the tip end of the upper arm 6, and a lower wire guide device 10 is attached to the tip end of the lower arm 7, with their axes aligned in the Z direction. The upper wire guide device 9 (FIG. 1) includes a wire supply reel 11, a rotating cylinder 12, a sliding cylinder 13, and an upper nozzle 14. The wire supply reel 11 is the rotary cylinder 1.
It is rotatably supported by the upper end of 2 via a stay 15, and a brake side servomotor M1 is attached to its rotating shaft 16. A driven pulley 17 is fixed to the center of the rotary cylinder 12 in the longitudinal direction, and a female spline 18 is axially formed on the inner surface of the cylinder. The rotary cylinder 12 is rotatably attached to the tip of the upper arm 6 via a bearing 19 with its axis line vertical. Both thrust and radial bearings are used.

The sliding cylinder 13 has a ball rolling groove formed on its outer surface to form a ball screw, and a male side spline 20 which meshes with the female side spline 18 is formed at an upper end portion thereof. The sliding cylinder 13 is fitted inside the rotating cylinder 12 so as to be vertically slidable by spline fitting, and
It is attached to the rotary cylinder 12 by being screwed into a ball nut 22 which is rotatably attached to the lower end of the bearing by a bearing 21. The ball nut 22 is driven and rotated via a gear 23 by a Z-axis servomotor M2 attached to the rotary cylinder 12. An upper nozzle 14 is fixed to the lower end of the sliding cylinder 13.

The upper nozzle 14 has the same structure as that of the conventional one, is provided with a power feeding roller 24, a pinch roller 25, and a die guide 26, and a processing liquid supply tube (not shown) or the like is connected to this portion. To be done.

The lower wire guide device 10 includes a wire take-up reel 27, a rotary cylinder 28, and a lower nozzle 29. The wire take-up reel 27 is rotatably supported at the lower end of a rotary cylinder 28 via a stay 30, and the rotation shaft 31 is connected to the output shaft of the take-up side servo motor M3. The rotary cylinder 31 is provided with a driven pulley 32 at the center in the longitudinal direction thereof, and is rotatably attached to the tip end of the lower arm 7 via a bearing 33 with its axis line vertical. The lower nozzle 29 does not include a power feeding roller or the like, but has substantially the same structure as the upper nozzle 14.

A connecting shaft 34 is vertically supported at the position of the column 5, and a variable speed motor M arranged at the upper part of the column 5.
It is designed to be driven by four. Drive pulleys 35 and 36 are fixed to the upper and lower portions of the connecting shaft 34. The drive pulley 35 of the upper portion and the driven pulley 17 of the upper wire guide device 9 and the drive pulley 36 of the lower portion and the lower wire guide device 10 are fixed. The driven pulley 32 is interlockingly connected by timing belts 38 and 39, respectively.

The above-mentioned motors M1, M2, M3 and M4 are under the control of the control unit 2, and the output may go through a speed reducer. In FIG. 1, reference numeral 40 indicates a workpiece, and reference numeral 41 indicates a wire.

The wire 41 is pulled out from the wire supply reel 11 and penetrates the inside of the sliding cylinder 13 of the upper wire guide device 9, and penetrates between the power feeding roller 24 and the pinch roller 25 of the upper nozzle 14 and the die guide 26. To reach the position of the workpiece 40, and further, the lower wire guide device 10
The wire winding reel 27 is wound (wired) so as to pass through the rotating cylinder 28 and be wound around the wire winding reel 27. When the workpiece 40 is correctly installed on the workpiece table 8, the wire electric discharge machine 1 is operated.

Then, the machining start position of the workpiece 40 on the xy plane with respect to the wire 41 is determined according to the machine sequence program stored in the control section 2, the machining program and the input data, and further Z The axis servo motor M2 is driven to rotate the ball nut 22,
As a result, the sliding cylinder 13 begins to extend downward, and the upper nozzle 14
Is a processing position close to the upper surface of the workpiece 40. Then, the machining liquid is supplied from the upper nozzle 14 and the lower nozzle 29 to start the electric discharge machining between the wire 41 and the workpiece 40. The direction of the working liquid discharged from the upper and lower nozzles 14 and 29 is the vertical direction as in the conventional case.

The wire 41 is pulled out from the wire supply reel 11 by the winding side servomotor M3 in the lower wire guide device 10 and travels at a set speed along the wire path connected. At this time, the brake side servomotor M1 is driven by the torque for rotating the reel 11 in the direction opposite to the direction in which the wire supply reel 11 is rotated by pulling out the wire 41, so that the wire 41 running The required tension is applied.

That is, the winding side servo motor M3 is speed-controlled so as to attain the set wire traveling speed,
The brake side servomotor M1 is torque-controlled in the direction in which the wire 41 is rewound so that the wire tension becomes a set value. Therefore, while the wire supply reel 11 is driven by the brake side servo motor M1, the wire supply reel 11 is rotated by being dragged by the winding side servo motor M3 in the direction opposite to the rotation direction due to the drive.

During this time, the rotary cylinder 12 of the upper wire guide device 9 and the rotary cylinder 28 of the lower wire guide device 10 are driven by the driven pulleys 17, 32, the timing belts 38, 39, the drive pulleys 35, 36 and the connecting shaft 34. And is rotated at a low speed (for example, 60 rpm). This rotation is synchronized with the upper and lower rotary cylinders 12 and 28, and the wire supply reel 11 and the Z-axis servomotor M2 attached to the rotary cylinder 12 are synchronized.
, And the wire take-up reel 27 attached to the rotary cylinder 28 also rotates in the same direction, so that the workpiece 40 and the wire 41 at the electric discharge machining position also rotate without twisting.

At the electric discharge machining point, electric discharge is continuously performed in a pulse shape between the wire 41 and the workpiece 40 to perform cutting machining. As the machining progresses, the wire 41 advances relative to the workpiece 40 in the xy plane. During the electric discharge machining, the wire 41 travels downward from above with respect to the workpiece 40 while rotating on its own axis as described above.
Is opposed to the work piece 40 over the entire length and the entire circumference of the cylinder, and the pulsed discharge voltage is always applied, so that the wire 41 side is eventually consumed by the discharge. Is distributed over the entire circumference of the, and uneven wear does not occur.

Further, the machining waste generated by the electric discharge is suspended by the machining liquid flowing into the electric discharge gap between the wire 41 and the workpiece 40, and the movement of the wire 41 from the upper side to the lower side is also added, so that the electric discharge point is removed. Promptly removed. Further, since the wire 41 rotates about its own axis, the working fluid in contact with the peripheral surface of the cylinder forms a rotating flow and discharges the processing waste to the side and the back of the wire 41.

As a result, the discharge gap is always
The dimension of the set value is maintained, and the specific resistance of the working fluid in this gap is also maintained at the value initially set, so that normal discharge is maintained. The rotation speed of the wire 41 by the variable speed motor M4 is adjusted mainly in relation to the wire traveling speed, but an appropriate value is selected according to the wire diameter, the material of the wire, the amount of machining waste, and the like.

FIG. 2 shows a second embodiment of the wire 41.
Is pulled out from the wire feeding bucket 42, and the guide rollers 43 to 45, the upper wire guide device 9, and the workpiece 4
It reaches 0 to the lower wire guide device 10, and further passes through guide rollers 46 to 48 and is accommodated in a wire receiving bucket 49.

The wire delivery bucket 42 comprises a vertical shaft 50 which is axially supported by the base 4 of the wire electric discharge machine 1, and the wire 4 is attached to a rotatable bobbin 51 fitted therein.
1 is wound up. The vertical shaft 50 has gears 52, 53.
It is driven by the servomotor M5 via. The first guide roller 43 is also pivotally supported by the vertical shaft 50 also as a brake roller capable of adjusting the braking force, and rotates together with the vertical shaft 50. The wire receiving bucket 49 is provided with a vertical rotating drum 54 pivotally supported by the base 4, and a guide roller 48 at the final bending portion is attached to the top of the rotating drum 54. The wire receiving bucket 49 is driven by a servo motor M5 via a drive pulley 55, a timing belt 56 and a driven pulley 57 fixed integrally. Other guide rollers 4
4 to 47 and the upper and lower wire guide devices 9 and 10 are arranged at fixed positions and do not rotate as a whole.

When the wire electric discharge machining apparatus 1 is operated as described above, the servomotor M5 is driven and the wire feeding bucket 42 and the wire receiving bucket 49 rotate in the same direction with respect to the rotation of the wire 41 and synchronously. To be done. This causes the wire 41 to rotate on its axis. On the other hand, by rotating the wire receiving bucket 49, the wire 41 is sequentially wound around the surface of the rotary drum 54,
Is pulled out from the wire feeding bucket 42. At this time, the required tension is applied to the wire 41 by the braking action of the first guide roller 43.

Also in this embodiment, since the wire 41 rotates at the electric discharge machining position, the wire 41 is not subject to uneven wear as in the case of the first embodiment, and the machining liquid in the electric discharge gap is not consumed. The rotating flow facilitates the discharge of machining chips. The above is an embodiment, and the present invention is not limited to the illustrated specific configuration. For example, in the first embodiment, the brake servomotor M1 for driving the wire supply reel 11 may be a braking device such as an electromagnetic powder brake capable of controlling and adjusting the braking force.

[0027]

With respect to processing accuracy, it is possible to prevent deterioration of shape accuracy and surface accuracy due to uneven consumption of wire electrodes. Wire breakage due to uneven wear of the wire electrode is prevented. As a result, the electric discharge machining is not stopped due to disconnection, and the automatic machining efficiency of the wire electric discharge machine is improved. In addition, the wire traveling speed can be reduced, and the amount of wire used can be reduced. Since processing waste can be quickly eliminated,
It is possible to prevent damage to the wire side and the work piece side due to concentrated discharge and abnormal discharge caused by machining waste.

[Brief description of drawings]

FIG. 1 is a front view mechanically showing (first embodiment).

FIG. 2 is a front view (second embodiment) mechanically shown.

FIG. 3 is an overall perspective view.

[Explanation of symbols]

1 Wire Electric Discharge Machine 9 Upper Wire Guide Device 10 Lower Wire Guide Device 11 Wire Supply Reel 12 Rotating Cylinder 13 Sliding Cylinder 27 Wire Winding Reel 40 Workpiece 41 Wire M1 Brake Side Servo Motor M2 Z Axis Servo Motor M3 Winding Side servo motor M4 variable speed motor

Claims (1)

[Claims] 1. An apparatus for cutting a work piece by an electric discharge phenomenon between a wire as one electrode and a work piece as the other electrode, wherein the wire is axially added to a mechanism for feeding the wire in an axial direction. A wire electric discharge machine comprising a mechanism for rotating around.