WO1991007246A1

WO1991007246A1 - Electrode holder for discharge machining

Info

Publication number: WO1991007246A1
Application number: PCT/JP1990/001511
Authority: WO
Inventors: Shinichi Murayama
Original assignee: Sodick Co., Ltd.
Priority date: 1989-11-22
Filing date: 1990-11-20
Publication date: 1991-05-30

Abstract

An electrode holder for discharge machining for holding a thin rotary shaft for an electrode at the axis of rotation, provided with a plurality of guide means disposed inside a case and coming into sliding contact with the outer periphery of the shaft for centering the shaft; a liquid stored in the case; and means for solidifying this liquid. Since a solid bearing formed by solidifying the liquid guides the rotary shaft, the play between the rotary shaft and the guide means resulting from the limit of mechanical accuracy can be absorbed and a holder with low heat buildup can be obtained.

Description

Description Electrode holding device for electrical discharge machining [Technology]

* The present invention relates to an electrode holder for electric discharge machining, which holds a small-diameter rotary shaft formed as an electric discharge S for electric discharge machining at an axial center position.

[Background technology]

2. Description of the Related Art Conventionally, there has been provided an electric discharge machining apparatus for performing micro hole machining or the like using a small diameter electrode.

Then, when such a small-diameter electrode for electric discharge machining is formed by electric discharge machining, it is necessary to hold the small-diameter rotary shaft, which is a material of the small-diameter electrode, at the center position with high precision. .

Heretofore, as a bearing device for holding this kind of rotating shaft at an axial center position, a rolling bearing and a sliding bearing have been known.

In these bearing devices, a guide member such as a steel ball, a roller, or a metal is mechanically slid on the outer periphery of the rotating shaft to position the rotating shaft.

However, in the above-described conventional technology, since there is a limit in the processing accuracy of each member, it is not possible to completely eliminate the gap between the rotation w and the guide member, and a certain amount of play is provided. This causes a run-out problem. In particular, when the diameter is as small as 1 mm or less as in the case of the above-mentioned rotating shaft for forming the small-diameter electric wire S for electric discharge machining, or when it is desired to perform high-precision centering, the rotating shaft and the guide member are connected to each other. Since the play due to the gap between the parts cannot be ignored, and there have been inconveniences such as the equipment being enlarged in order to obtain high precision, various proposals have been made (Japanese Patent Application Laid-Open No. Sho 61-16). No. 4,731,1 and Japanese Patent Application Laid-Open No. 61-164,425).

In addition, in the above-mentioned conventional technical staff, frictional heat is generated between the rotating shaft and the guide member, which has a drawback that proper processing of the rotating shaft is hindered.

* The invention provides an electrode holder for electric discharge machining that can hold a small-diameter rotary shaft at the axis center position with high accuracy by absorbing the play due to the limitation of mechanical accuracy and the like and simplifying the structure. Its purpose is.

[Disclosure of the Invention]

* The invention is an electrode holding device for electric discharge machining that holds a small-diameter rotary member for an electrode at a center position, and is disposed in a case and slidably contacts an outer periphery of the small-diameter rotary member. It is characterized by having guide means for centering a rotating shaft, liquid stored in a case, and solidifying means for solidifying the liquid.

In the above configuration, the liquid injected into the case is solidified while the small-diameter rotary shaft is rotated at a high speed, so that the small-diameter rotary shaft is adjusted by the resistance of the liquid that gradually solidifies. The centering action is high, and the centering is performed with high accuracy. In addition, the liquid filled between the small-diameter rotary shaft and the guide means gradually hardens to eliminate play, and on the outer peripheral surface of the small-diameter rotary shaft, sliding contact of this portion causes The liquid acts as a lubricant without solidifying, and a smooth sliding state with low friction is obtained.

In addition, the friction at the sliding contact part is small and the heat generation is low.In addition, since the liquid is solidified, the heat at the sliding contact part is cooled, so that the heat generated by the conventional guide is greatly reduced. It can be extinguished, and the cooling effect of the electrode can be expected at the same time, so that the processing accuracy can be further improved.

As a method of solidifying a liquid, when a liquid having a low freezing point, which is in a liquefied state in a normal chamber, is used, a cooling device is provided to gradually solidify the liquid. When a liquid that has a freezing point at room temperature and does not liquefy unless heated is used, once liquefied by a heating device, it is cooled by atmospheric pressure or a cooling device and gradually cooled. Coagulates.

In addition, by using an electrically conductive liquid, it is possible to energize the small-diameter rotary shaft through liquefaction from the case II.

[Schematic description of drawings]

FIG. 1 is a side sectional view showing an electrode holding device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional plan view showing the electric S holding device according to the same example.

Fig. 3 shows the small diameter held by the electronic holding device according to the same example. FIG. 6 is a side view of a main part showing a state where electric discharge machining is performed on the rotation axis. FIG. 4 is a plan view showing an outline of an electric discharge machining apparatus for performing electric discharge machining on a small-diameter rotary shaft held by an electric S holding apparatus according to the embodiment.

FIG. 5 is a side sectional view showing an electrode holder for electric discharge machining according to a second embodiment of the present invention.

FIG. 6 is a sectional view showing an electrode holder for electric discharge machining according to a third embodiment of the present invention.

[Best mode for carrying out the invention]

FIG. 1 is a side sectional view showing an electrode holding device 1 according to a first embodiment of the present invention.

The small-diameter rotary shaft 10 guided by the electrode holding device 1 has a diameter of 100 ^ formed as an electrode to be processed of the electric discharge machine, and has a base end 佣. It is held by the electrode rotation motor 11 and is turned at a speed of, for example, 100,000 rpm. * In the case of Jeongseon, at a speed of 50,000 rpm or less, the liquid could not be rotated due to solidification of the liquid.

The holding device 1 includes a cylindrical guide 3, a thick cylindrical guide 3 disposed in a cylindrical case 2, and an annular guide 4 through which the rotating shaft 10 is inserted through both ends of the case 2. The guides 3 to 5 guide the rotatable shaft 10 so as to be rotatable with a certain straightness.

As shown in FIG. 2, each of the cylindrical guides 3 is fitted into the inner cylindrical portion 2a formed in the case 2 in a dense structure, and each of the cylindrical guides 3 is provided. The rotating shaft 10 is inserted in the gap between the guides 3. That is, since each cylindrical guide 3 is formed to have a large diameter with respect to the rotation 轴 10, each is close enough to be slightly engaged with the outer peripheral surface of the rotation shaft 10. In addition, the cylindrical guides 3 are arranged so as to be in contact with each other and surround the rotation axis 10.

On the other hand, the annular guides 4 and 5 close the case 2 from both ends, and each has a guide hole at the center thereof through which the rotating shaft 10 can be inserted.

Although each of the guides 3 to 5 and the case 2 are mechanically formed with high precision, they have a slight gap due to a fitting error between the rotating sleeve 10 and the like.

A liquid for freezing is injected into the inner circular part 2a of the case 2 and the inner chamber part 2b formed by the annular guides 4 and 5. Preferably, the liquid can be easily coagulated, for example, water can be used, but in this embodiment, the use of mercury 12 in this liquid is more advantageous. The liquid is supplied to the rotating shaft 10 as an electrode from a liquid. Case 2 is provided with a terminal (not shown) for energizing the ice silver 12. Thus, a pulse signal can be sent to the rotating shaft 10, and electric discharge machining of pores and the like can be performed using the tip of the rotating shaft 10 as a rotating electrode.

As described above, in the present embodiment, since the rotating electrode can be energized in the holding device 1, an extremely effective device can be configured as a component of the electric discharge machine.

The annular guide 5 attached to the lower side of case 2 It is necessary to ensure the sealing properties so that the liquid in case 2 does not leak, but in this example, mercury 12 with a high surface tension is used for the liquid. Thus, leakage from a small gap is prevented, and sufficient sealing performance can be ensured.

In the outer chamber 2d formed by the outer wall 2c and the inner cylindrical portion 2a of the case 2, a refrigerant 13 for freezing the mercury 12 passes through the connecting portion 2e, not shown. Supplied from the cooling device. The refrigerant 13 and the cooling device are selected according to the liquid to be used. For example, in this example, a cooling device of 150 ° C for mercury 12 is used.

In the holding device 1 having the above-described configuration, first, when the rotation of the rotating shaft 10 is started in a state where the mercury 12 is injected into the case 2 through the rotating shaft 10 in each of the guides 3 to 5, In both cases, the refrigerant 13 is introduced and the mercury 12 is gradually cooled. Then, initially, due to the gap between guides 3 to 5, high-speed rotation causes rotation of rotating shaft 10 in the outer circumferential direction, but mercury 12 gradually freezes from the outside. As a result, the rotation of the rotary shaft 10 is suppressed, and the rotary shaft 10 is gradually and accurately positioned at the center position, and the runout is 1 or less.

Eventually, if the mercury 12 frozen in the case 2 functions as a sliding bearing, the space between the rotating shaft 10 and the guide 3 is filled to eliminate play. In particular, in the vicinity of the outer peripheral surface of the rotating shaft 10, the outer peripheral surface and the frozen body of mercury 12 are liquefied into a thin film by sliding contact, which acts as a lubricant, and provides good friction with low friction. 機能 The function of receiving is obtained.

In addition, as described above, since the liquid is cooled and frozen to support the rotating shaft 10, the frictional heat at the sliding contact between the rotating shaft 10 and the frozen body is extremely small. In addition, it is possible to effectively prevent a decrease in processing accuracy due to heat generation.

FIG. 3 is a side view showing a main part of the electric discharge machine for performing electric discharge machining on the rotating shaft 10 held by the holding device 1 as described above, and FIG. FIG. 2 is a plan view showing an outline of the electric discharge machining apparatus.

This electric discharge machining apparatus is for electroforming the above-described rotation 轴 10 having a diameter of 100 に into an electric discharge machining electrode having a smaller diameter of 10 tt jtt.

In this electric discharge machine, the wire electrode 31 is sent out from the sending-out reel 32, is passed through the outer periphery of the drum guide 33, and is taken up by the winding reel 34. . The feed reel 32 is tensioned by a hook, a powder clutch or the like, and the take-up reel 34 is rotated by a control motor.

In addition, energizing pieces 35 and 36 for energizing the wire electrode 31 are provided at an entrance portion and an exit portion of the drum guide 33.

The wire electrode 31 is positioned in a guide groove 37 formed on the outer periphery of the drum guide 33, and is fed along the guide groove 37.

As shown in FIG. 3, the rotating shaft 10 held by the holding device 1 has a distal end supplied to the wire electrode S 31 and an outer peripheral portion. The part is removed by electric discharge machining and processed as a fine electrode.

In addition, the shape of the guide groove 37 is such that the wire electrode 31 is exposed largely on the supply side of the rotation 铀 10, so that the effective working width A is increased and the efficiency is improved. The rotary shaft 10 can be machined.

As described above, * According to the actual example, it is possible to obtain an ultrafine electrode with a diameter D = 20 over a machining length L = several 100 CL / D> 5). In addition, the twist at the tip of the electrode at that time is less than the above, and extremely high-precision and stable extremely fine hole processing can be performed.

FIG. 5 is a side sectional view showing a holding device 1 according to a second embodiment of the present invention. In the second example, members that are substantially the same as those in the first example are denoted by the same reference numerals.

In the above first example, mercury 12 was used as the liquid, but in the second example, water 23 was used as the liquid. In this case, since the rotation 通電 10 is energized, the upper layer of the water 23 in the inner chamber 2 b is filled with a liquid for energizing the rotation shaft 10 via the partition 4 24. Then, mercury 22 is stored, and a pulse signal or the like is supplied to the rotation # 10 in the same manner as in the first embodiment.

As a condition for using water 23, good results can be obtained when the electrode rotation speed is about 100,000 rpm and the refrigerant temperature is 125 ° C.

FIG. 6 is a side view showing a holding device 1 according to a third embodiment of the present invention. It is sectional drawing. In the third embodiment, members that are substantially the same as those of the above-described embodiment will be described with the same reference numerals.

In the above real example, the liquid injected into the case was frozen by the refrigerant, but in the third real example, the substance that solidified in the permanent moat was liquefied by heating in the case, and Is gradually cooled by the atmosphere and solidified.

In the third embodiment, as the liquid for guiding the rotating shaft 10, a wax 21 that liquefies at an S degree equal to or greater than Muroton is used.

Mercury 22 is stored in the upper layer of the wax 21 in the inner chamber 2b as a liquid for energizing the rotating shaft 10 via the partition plate 24. In the same manner as in the first embodiment, a pulse signal or the like is supplied to the rotating shaft 10.

On the other hand, a heating wire 20 is buried in the outer wall 2c of the case 2, and the box 21 is heated by re-energizing the heating wire 20 through a not-shown energizing portion. A liquefaction heating device is provided.

Other configurations are the same as those in the first example. In such a holding device 1, the heating sleeve 2 is inserted in advance with the rotating sleeve 10, and the solidified wax 21 is stored in the inner chamber 2 b. Energize 0 and heat wax 21 to liquefy. Then, in this state, energization of the heating wire 20 is stopped, and the cooling device is started up while rotating the rotating shaft 10 in the same manner as in the first embodiment, and the work is started. Is gradually solidifying <o

Finally, the wax 21 solidified in the case 2 exerts a play-absorbing action and a lubricating action between the rotating shaft 10 and the guide 3 to reduce friction. It works as a small good slipper.

The detailed process from the start of cooling of the wax 21 to the solidification thereof is the same as that described in the first embodiment, and will not be described here.

Further, in the third magnificent example, the wax 21 is cooled by using the cooling device. However, a configuration in which the room 21 is naturally cooled by the room may be used instead. This makes it difficult to control the cooling rate and the like, but eliminates the need for a special cooling device, and makes it possible to obtain an inexpensive device.

Further, in order to obtain a sufficient cooling device by the room, the outer periphery of the case 2 may be provided with a heat radiation structure, or a mechanism for providing a blower may be provided.

Further, the invention is not limited to the above examples, and the specific configuration can be variously changed.

For example, in the above example, a case was described in which a thin rotary electrode for electric discharge machining was guided.However, for example, a guide for machining the outer peripheral surface of a rotating drum of a video tape recorder with a bell surface is provided. It can be widely applied.

Further, such a holding device 1 can be applied not only as a bearing but also as a sealing device for a portion supporting the rotating shaft 10. In other words, the above-mentioned liquid is frozen to support the rotating shaft. Since this configuration also provides a high-performance sealing function for the rotating shaft that rotates simultaneously, such a structure is used for the sealing portion of the rotating shaft, and both the seal and the bearing are used. The function can be obtained.

When mercury is not suitable as the liquid, another low melting point alloy may be used instead.

Further, the configuration does not necessarily need to be a configuration in which the rotation shaft 10 is energized via the liquid, and may be a configuration using a known current collector or the like.

Claims

The scope of the claims

(1) A holding device for holding a rotating rotary shaft at a center position,

A plurality of guide means are provided in the case and are in sliding contact with the outer periphery of the rotary shaft to position the rotary shaft, a liquid stored in the case, and a solidifying means for solidifying the liquid. And a holding device.

(2) In claim (1),

A holding device characterized in that the solidifying means is a cooling device for cooling and solidifying the liquid.

C 3) In claim (1),

The consolidating means includes a heating device for obtaining the liquid by heating a predetermined substance having a freezing point in a conventional room, and solidifying the liquid by natural cooling or a cooling device. A holding device that is unique.

(4) In any one of claims (1) to (3), the guide means is formed in a shape of a rotating shaft having a diameter larger than that of the rotating shaft, and is arranged parallel to the rotating shaft. A plurality of guide members, each of which is disposed so as to be close to the outer peripheral surface of the rotating shaft and surround the periphery of the rotating shaft. A holding device characterized in that the liquid material is filled in a gap formed between the liquids.

(5) The liquid according to any one of claims (1) to (4), wherein the liquid has electrical conductivity, and is provided with an electrode provided in the case. A holding device characterized in that electricity is supplied to the rotating shaft via the liquid.