JP6073434B1 - Small hole electric discharge machine - Google Patents

Abstract

A small hole electric discharge machine that can be easily inserted into a seal member and attached to an electrode holder without damaging a small diameter pipe electrode. A thin hole electric discharge machine that discharges between a pipe electrode and a workpiece while processing a machining fluid through the pipe electrode and cuts a small hole in the workpiece. A seal member 20 having an electrode holder 10 that is relatively moved, a through hole 26 through which the pipe electrode 30 passes, and a tapered portion 24 that engages with the electrode holder 30, and a slit 24 a formed in the tapered portion 24; A collet 16 that holds the pipe electrode 30 and a nut 18 that presses the seal member 20 are provided. [Selection] Figure 2

Description

  The present invention relates to a fine hole electric discharge machine in which a small diameter pipe electrode can be easily attached to and detached from an electrode holder.

  As a typical example of the fine hole electric discharge machining, there is a case where a cooling hole for flowing cooling air for cooling the surface of the turbine blade is formed on the surface of the turbine blade. In such a small hole electric discharge machining, a hollow pipe electrode is used, and a machining is performed while discharging a high-pressure machining fluid from the tip of the hollow pipe electrode and discharging between the pipe electrode and the workpiece. At this time, in order to prevent leakage of the high-pressure machining fluid, the pipe electrode is held by an electrode holder provided at the tip of the main shaft of the electric discharge machine through a seal member having an electrode insertion hole. In order to enhance the sealing effect, the inner diameter of the electrode insertion hole is prepared for each outer diameter of the pipe electrode, and is only slightly larger than the outer diameter of each pipe electrode. When the outer diameter of the pipe electrode is 1 mm or more, since the rigidity of the pipe electrode is high, the pipe electrode can be passed through the electrode insertion hole of the seal member relatively easily. On the other hand, when the outer diameter of the pipe electrode is smaller than 1 mm, the rigidity of the pipe electrode is remarkably reduced, so that the pipe electrode may be damaged when the seal member is inserted into the electrode insertion hole.

  In Patent Document 1, a large electrode insertion hole is formed in the seal member, and the electrode insertion hole is reduced in diameter by utilizing the high pressure of the processing liquid, and the electrode electrode is inserted into the electrode insertion hole while maintaining the sealing performance of the seal member. A small hole electric discharge machine that makes it easy to pass through is described.

Japanese Patent Laid-Open No. 03-060930

In the invention of Patent Document 1, since the seal member is deformed by the pressure of the machining fluid, the range in which the diameter of the electrode insertion hole can be reduced is small. Therefore, many seal members in which electrode insertion holes that match the outer diameter of the pipe electrode are formed must be prepared in advance. Further, in the diameter reducing action due to the pressure of the machining fluid, it is difficult to completely remove the gap between the pipe electrode and the electrode insertion hole, and there is a problem that the sealing performance is deteriorated.

  The present invention has a technical problem to solve such problems of the prior art, and provides a small-hole electric discharge machine that can be easily inserted into a seal member and attached to an electrode holder without damaging a small-diameter pipe electrode. The purpose is to do.

In order to achieve the above-described object, according to the present invention, a machining liquid is circulated in a pipe electrode attached to the tip of a main shaft, and a discharge is generated between the pipe electrode and the workpiece, thereby machining a narrow hole in the workpiece. The fine hole electric discharge machine has an electrode holder that is provided at the tip of the main shaft and grips the pipe electrode, a through hole through which the pipe electrode passes, and a tapered portion that engages with the electrode holder, A seal member formed with a slit in the portion, and a nut that is screw-engaged with the electrode holder and holds the pipe electrode together with a nut that presses the seal member toward the rear of the main shaft, and has an outer diameter of the pipe electrode The through hole has a larger inner diameter, and when the nut is screwed and tightened, the through hole is reduced in diameter in the region of the tapered portion, and the inner peripheral surface of the through hole is the pipe electrode Outside Small hole electric discharge machine in close contact with the surface is provided.

  According to the present invention, by tightening the nut and mechanically pressing the seal member together with the collet that grips the pipe electrode, the seal member is improved in sealing performance, and the slit is provided in the seal member. It is easily deformed, the through hole is reduced in diameter and the outer surface of the pipe electrode is brought into close contact with the inner surface of the through hole, and the sealing performance between the pipe electrode and the through hole can be improved. Thereby, it becomes possible to deal with pipe electrodes having various outer diameters with one kind of sealing member having a large electrode insertion hole.

It is a front view which shows roughly the principal part structure of the electric discharge machine by preferable embodiment of this invention. 1 is a schematic cross-sectional view of an electrode holder according to a preferred embodiment of the present invention. It is a perspective view of the electrode holder assembled | attached to the electrode guide. It is a perspective view of the electrode holder separated from the electrode guide. It is a top view of a sealing member. It is a side view of a sealing member. It is sectional drawing of the sealing member which follows the arrow VII-VII of FIG.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
FIG. 1 is a front view schematically showing a main configuration of an electric discharge machine 100 to which the present invention is applied. In the following, for convenience, the three orthogonal directions (X-axis direction, Y-axis direction, and Z-axis direction) are defined as the left-right direction, the front-rear direction, and the up-down direction, respectively, as shown in the figure. explain.

  In FIG. 1, a column 104 is erected on the rear part of a bed 102 serving as a base. An X slider 106 is supported on the upper surface of the column 104 so as to be movable in the X-axis direction (left-right direction). A ram 108 is supported on the upper surface of the X slider 106 so as to be movable in the Y-axis direction (front-rear direction, direction perpendicular to the paper surface). A spindle head 110 is supported on the front surface of the ram 108 so as to be movable in the Z-axis direction (vertical direction). A rotating spindle 112 is supported on the spindle head 110 so as to be rotatable about the axis CL0. The electrode holder 10 is attached to the tip of the rotating spindle 112 protruding from the bottom surface of the spindle head 110.

  A W-axis guide assembly 140 is attached to the side surface of the ram 108. The W-axis guide assembly 140 has a guide arm 142 supported by a bracket 136 provided on the right side surface of the ram 108 so as to be movable in the vertical direction. The vertical movement axis of the guide arm 142 is defined as the W axis. The W axis is parallel to the Z axis. A lower end portion 142a of the guide arm 142 is inclined obliquely inward with respect to the W axis or the Z axis, and a W axis chuck 144 is provided at a distal end portion of the lower end portion 142a. The W-axis chuck 144 holds the electrode guide 40. More specifically, the electrode guide 40 is held at the tip of the guide arm 142 by the W-axis chuck 144 so that the center of the upper end thereof coincides with the axis CL0.

  Between the electrode holder 10 and the electrode guide 40, the pipe electrode 30 extends along the axis line CL0, and the upper end portion thereof is held by the electrode holder 10. When the rotation main shaft 112 rotates about the axis line CL0, the pipe electrode 30 rotates about the axis line CL0 together with the electrode holder 10.

  In addition, a machining liquid such as water is pipe electrode through a machining liquid supply pipe (not shown) provided in the main shaft 112 and a through hole 12a (FIG. 2) as a machining liquid supply passage of the electrode holder 10. 30 is supplied to the inside of the pipe electrode 30 and the processing liquid is sprayed from the tip (lower end) of the pipe electrode 30. In addition, you may use oil as a processing liquid.

  A table 118 is disposed on the upper surface of the bed 102 in front of the column 104. An inclined rotation table device 120 is mounted on the upper surface of the table 118. The tilt rotary table device 120 includes a pair of front and rear support members 122 projecting upward from the upper surface of the table 118 and a swivel axis CLb extending in the Y-axis direction between the front and rear support members 122 as a B axis. The tilting member 124 is supported so as to be pivotable in the direction, and the rotary table 126 is supported on the left end surface of the tilting member 124 so as to be rotatable in the A-axis direction about a rotation axis CLa perpendicular to the pivoting axis CLb. A chuck 128 is provided on the rotary table 126, and a work 130 is attached to the chuck 128. The workpiece 130 is, for example, a turbine blade or a vane used in a gas turbine, and a cooling hole for flowing cooling air for cooling the surface of the turbine blade is processed on the surface of the turbine blade.

  A processing tank 132 is provided around the table 118 so as to be movable up and down so as to surround the entire table 118 and the inclined rotary table device 120. 1 is a machining state in which the machining tank 132 is raised, and the machining tank 132 is lowered as shown by a solid line in a non-machining state such as during a setup operation.

  Although not shown, the electric discharge machine 100 in FIG. 1 has an X-axis drive unit that moves the X slider 106 in the left-right direction, a Y-axis drive unit that moves the ram 108 in the front-rear direction, and a spindle head 110 in the up-down direction. A Z-axis drive unit that is moved to the center, a main-axis drive unit that rotates the rotary main shaft 112 about the axis CL0, a W-axis drive unit that moves the guide arm 142 in the vertical direction, and the inclined member 124 via the pivot axis CLb. Each includes a B-axis drive unit that is inclined and an A-axis drive unit that rotates the rotary table 126 via the rotation axis CLa. The X-axis drive unit, the Y-axis drive unit, the Z-axis drive unit, and the W-axis drive unit are configured by, for example, a servo motor that rotationally drives a ball screw and a ball screw, and the main shaft drive unit is configured by, for example, a spindle motor. The shaft drive unit and the A-axis drive unit are configured by, for example, a DD (direct drive) servo motor. These X-axis drive unit, Y-axis drive unit, Z-axis drive unit, W-axis drive unit, main shaft drive unit, B-axis drive unit and A-axis drive unit are controlled by an NC device (not shown) of the electric discharge machine 100. Is done.

  With the above configuration, the electrode holder 10 and the electrode guide 40 can be moved relative to the workpiece 130 in the X-axis direction, the Y-axis direction, and the Z-axis direction, and can be relatively moved in the B-axis direction and the A-axis direction. Further, the distance between the electrode holder 10 and the electrode guide 40 can be adjusted by raising and lowering the guide arm 142 by the W-axis drive unit, and the machining is always performed during processing regardless of the change in the length of the pipe electrode 30 due to the consumption of the pipe electrode 30. The upper and lower ends of the pipe electrode 30 can be supported by the electrode holder 10 and the electrode guide 40.

  A position detector 134 such as a linear scale for detecting the vertical Z-axis position of the spindle head 110 is provided on the front surface of the ram 108. The position of the electrode holder 10, that is, the position of the upper end portion of the pipe electrode 30 can be detected by a signal from the position detector 134. The bracket 136 of the guide arm 142 is provided with a position detector 138 such as a linear scale for detecting the vertical W-axis position of the guide arm 142 with respect to the ram 108. Since the shape of the guide arm 142 is known in advance, the position of the W-axis chuck 144 can be measured from the values of the X-axis and Y-axis position detectors and the W-axis position detector 138.

  Although illustration is omitted, an electrode magazine is provided on the side of the W-axis guide assembly 140. A plurality of replacement pipe electrodes 30 having a predetermined initial length are held in the electrode magazine 10 while being attached to the electrode holder 10, and are exchanged between the rotating spindle 112 and the tool magazine by an unillustrated exchange means. The pipe electrode 30 can be replaced together with the electrode holder 10. You may make it prepare the pipe electrode 30 of various outer diameters in a tool magazine. Further, the electric discharge machine 100 can include a guide magazine (not shown) for storing the plurality of electrode guides 40.

  2 and 3, the electrode holder 10 has a main body 12 made of a hollow member having a through hole 12a as a machining liquid passage extending in the axial direction. A circumferential groove 12b for mounting an O-ring (not shown) is formed on the inner peripheral surface of the upper end portion of the through hole 12a. A receiving recess 12 c that opens downward is formed at the lower end of the main body 12. The upper end of the receiving recess 12c is connected to the lower end of the through hole 12a, and the receiving recess 12c and the through hole 12a communicate with each other. At the upper end of the receiving recess 12c, a sheet portion 12d made of a conical tapered surface that expands downward is formed.

  In the receiving recess 12 c, an elastic member, particularly a rubber seal member 20, a bush 14, and a collet 16 that fixes the pipe electrode 30 to the main body 12 are arranged and fixed by a nut 18. The nut 18 is screwed into an external screw formed on the outer peripheral surface of the lower end portion of the main body 12. By tightening the nut 18 against the main body 12, the collet 16 is pushed into the receiving recess 12b. As a result, the pipe electrode 30 is fastened to the collet 16.

  5 to 7, the seal member 20 includes a cylindrical portion 22 and a tapered portion 24 provided at one end (upper end) of the cylindrical portion, and the tip of the tapered portion 24 along the central axis. A through hole 26 is formed as an electrode receiving hole extending from the (upper end) surface to the lower end surface of the cylindrical portion 22. The pipe electrode 30 is inserted through the through hole 26. The cylindrical portion 22 forms a straight portion whose outer peripheral surface 22 a extends in parallel to the through hole 26.

  The tapered portion 24 is formed in a truncated cone shape having a tapered surface that can be brought into close contact with the tapered surface of the sheet portion 12d of the receiving recess 12c. The seal member 20 has a slit 28 formed in the tapered portion 24. In the present embodiment, the four slits 28 are arranged radially at equal angular intervals with the through hole 26 as the center. The slit 28 extends in a radial direction from the tapered surface to the through hole 26, and an inner end portion opens on the inner peripheral surface of the through hole 26.

  The slit 28 is cut from the taper surface of the taper portion 24 at a predetermined depth in the axial direction, and the depth is shorter than the length (height) of the taper portion 24 in the axial direction. The cylindrical portion 22 does not extend in the axial direction. As a result, the taper portion 24 is formed with a seal surface 24a made of an intact taper surface extending in a strip shape in the circumferential direction.

  By screwing and tightening the nut 18 to the main body 12, the seal member 20 is pressed and pushed into the receiving recess 12 c of the main body 12 toward the rear of the main shaft 112. As a result, the taper portion 24 comes into close contact with the taper surface of the seat portion 12d of the main body 12, and the space between the main body 12 and the seal member 20 is sealed. As described above, the taper portion 24 of the seal member 20 is formed with the seal surface 24a extending in a belt shape in the circumferential direction, so that the sealing performance is ensured even if the slit 28 is formed.

  By forming the slit 28 in the taper portion 24, the taper portion 24 is easily deformed radially inward, and when the nut 18 is screwed into the body 12 and tightened, the through hole 26 is formed in the region of the taper portion 24. The diameter is reduced, and the inner peripheral surface of the through hole 26 is in close contact with the outer peripheral surface of the pipe electrode 30. Thereby, the space between the pipe electrode 30 and the seal member 20 is sealed. Particularly, the through hole 26 can be contracted very greatly at the tip portion thereof, so that a very thin pipe electrode 30 can be used with respect to the through hole 26. For example, the outer diameter of the conventional pipe electrode 30 is small. The four types of seal members had to be prepared for 0.5 mm, 0.5 to 1.0 mm, 1.0 to 2.0 mm, and 2.0 mm or more. It has come to an end. Even when the pipe electrode 30 having an outer diameter of 0.5 mm was inserted into the sealing member 20 having an inner diameter of the through hole 26 of 2.5 mm, the sealing could be surely performed.

DESCRIPTION OF SYMBOLS 10 Electrode holder 12 Main body 12a Through hole 14 Bush 16 Collet 18 Nut 20 Seal member 22 Cylindrical part 24 Taper part 26 Through hole 28 Slit 30 Pipe electrode

Claims (3)

In the fine hole electric discharge machine that discharges between the pipe electrode and the workpiece while processing the machining liquid in the pipe electrode attached to the tip of the spindle, and cuts a fine hole in the workpiece,
An electrode holder provided at the tip of the main shaft and holding the pipe electrode;
A seal member having a through-hole through which the pipe electrode passes and a tapered portion engaged with the electrode holder, and having a slit formed in the tapered portion;
A nut that is screw-coupled to the electrode holder and presses the seal member toward the rear of the main shaft together with a collet that holds the pipe electrode;
Equipped with,
The inner diameter of the through-hole is formed larger than the outer diameter of the pipe electrode, and when the nut is screwed and tightened, the through-hole is reduced in diameter in the region of the tapered portion, and the inner circumference of the through-hole A fine hole electric discharge machine characterized in that the surface is in close contact with the outer peripheral surface of the pipe electrode .   The seal member has a straight portion extending in parallel with the through hole, the taper portion is provided at one end of the straight portion, and the slit is formed only in a region of the taper portion. Item 2. The fine hole electric discharge machine according to item 1.   The thin hole electric discharge machine according to claim 2, wherein a plurality of the slits are provided radially around the through hole.

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