JP4575419B2 - Electrode insertion method and apparatus for electrode guide - Google Patents

Description

  The present invention relates to a fine hole electric discharge machining method and apparatus, and an electrode insertion method and apparatus for an electrode guide.

  In an electric discharge machining apparatus for narrow hole machining, a rod-like or pipe-like elongated electrode is generally rotatably supported on a spindle, and the spindle is moved up and down by a feed screw rotated by a spindle feed motor. The narrow hole is perforated by causing the lower end portion to approach the work and generating a discharge. The lower end of the electrode is guided by the electrode guide in order to guide it to an accurate position.

  Also, as a means of inserting a rod-shaped (or pipe-shaped) elongated electrode into the electrode guide that guides the lower end of the electrode, a water jet is jetted from the upper part of the rod-shaped electrode so as to surround the rod-shaped electrode and is fed to the electrode guide To be done.

  In fine fine hole processing using a rod-shaped electrode, processing is performed in a state where a workpiece is placed in a processing tank filled with a processing liquid (usually water or pure water) in order to prevent fusing due to discharge of the electrode.

  However, in the conventional fine hole electric discharge machining method and apparatus as described above, the sewage from the machining portion enters the electrode guide and the electrode guide is clogged, and stable electrode feeding for a long time cannot be performed. The continuous processing or continuous processing of about 1,000 holes was the limit. Furthermore, there is a problem that metal ions in the working fluid are reduced and adhere to the electrode guide, and the hole of the electrode guide becomes gradually smaller, making it impossible to feed the electrode stably for a long time.

  Further, when the electrode is inserted into the electrode guide as fine as about 0.01 mm to 0.03 mm in diameter, the electrode guide may buckle and the insertion may fail.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide an electrode insertion method and apparatus for ensuring the electrode insertion of the fine rod-shaped electrode into the electrode guide, and a working liquid. Narrow hole electrical discharge machining that prevents intrusion of dirt generated in the electrode guide and prevents metal ions in the machining fluid from being reduced and attached to the electrode guide, enabling stable electrode feed and improving machining accuracy It is to provide a method and apparatus.

  An electrode insertion method for an electrode guide according to claim 1 as means for solving the above-mentioned problems, comprising electrode holder means for holding the upper part of the rod-shaped electrode, and electrode guide means for guiding the lower part of the rod-shaped electrode, In the thin hole electric discharge machining apparatus for feeding the workpiece while rotating the rod-shaped electrode by the electrode holder means, the lower part of the electrode guide means is engaged with a detachable vacuum suction head, and the vacuum suction head The gist is to insert the electrode guide means while sucking the rod-shaped electrode.

  An electrode insertion device for an electrode guide according to claim 2, comprising electrode holder means for holding an upper portion of the rod-shaped electrode, and electrode guide means for guiding a lower portion of the rod-shaped electrode, wherein the rod-shaped electrode is formed by the electrode holder means. In a thin hole electric discharge machining apparatus that feeds the workpiece while rotating it, a detachable vacuum suction head is provided below the electrode guide means, and it is detected that the rod-shaped electrode has penetrated the electrode guide means The gist of the invention is to provide an electrode penetration detecting means.

  The electrode insertion device with respect to the electrode guide according to claim 3 is the electrode insertion device with respect to the electrode guide according to claim 2, wherein the vacuum suction head is a recessed portion opened upward so as to be engageable with a lower portion of the electrode guide means. And an exhaust means for exhausting air in a sealed space formed by engagement of the lower part of the electrode guide means and the recess, and the electrode penetration detecting means is provided on the vacuum suction head with the rod-like electrode. A detection electrode that can be contacted at the lower end of the rod and detecting electrical continuity between the rod-shaped electrode and the detection electrode in an electric circuit formed by contact between the detection electrode and the lower end of the rod-shaped electrode The gist is to provide a vessel.

  According to the first, second, and third aspects of the present invention, the rod-shaped electrode is fed to the electrode guide while being pulled downward by the suction operation by the vacuum suction head, so that the electrode diameter is as small as about 0.01 mm to 0.03 mm. Even a thing can be reliably inserted without buckling.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 and 2 are a front view and a side view of a small hole electric discharge machining apparatus according to the present invention. A work table 5 for fixing the workpiece W is provided on the base 3 of the small hole electric discharge machining apparatus 1, and a machining tank 7 for accommodating the workpiece W is provided on the work table 5. A column 9 (a, b) extending upward from the work table 5 is provided behind the work table 5 (right side in FIG. 2).

  An X-axis carriage 11 that can be moved and positioned in the X direction (left-right direction in FIG. 1) is provided above the column 9 (a, b). A Y-axis carriage 13 that can be moved and positioned in the orthogonal Y direction is provided.

  Referring to FIG. 3, a slide base 17 is engaged with the front end (left end portion in FIG. 2) of the Y-axis carriage 13 so as to be movable up and down. On this slide base 17, a Z-axis slide 19 is engaged with a guide (not shown) so as to be movable up and down.

  A Z-axis feed screw 21 extending in the Z direction is rotatably supported on the slide base 17, and the Z-axis feed screw 21 is rotationally driven at an upper end portion of the Z-axis feed screw 21. A servo motor 23 is provided. A nut 24 attached to the Z-axis slide 19 is screwed into the Z-axis feed 21.

  Therefore, the Z-axis slide 19 can be moved to a desired position in the Z direction by appropriately rotating and driving the Z-axis feed screw 21 by the servo motor 23 under the control of a control device (not shown). .

  An electrode holder means 27 including a one-touch coupler 25 is rotatably provided below the Z-axis slide 19 described above. The electrode holder means 27 is fixed with a hollow rotating shaft 29 extending above the Z-axis slide 19 via a one-touch coupler 25, and the upper end portion of the rotating shaft 29 is for driving the rotating shaft. A pulley 31 such as a timing pulley is provided. The upper end of the hollow rotary shaft 29 is connected to a water supply device (not shown) via a pipe 35 via a rotary joint 33. The pulley 31 is connected to a driving pulley (not shown) provided in an electrode motor 37 for rotating the electrode via a driving belt (not shown).

  Therefore, the water supplied from the water supply device is supplied to the electrode holder means 27 through the hollow portion of the hollow rotating shaft 29. The electrode holder means 27 can be driven to rotate by an electrode motor 37 for rotating the electrode.

  Below the electrode holder means 27, an electrode guide means 41 for guiding the tip of the rod-shaped electrode 39 is provided. The electrode guide means 41 is fixed to a support plate 43 provided integrally with the lower end portion of the slide base 17 by a fastening member 45 such as a bolt.

  As shown in FIG. 4, the electrode holder means 27 includes a collet 47 that holds the end portion of the fine rod-shaped electrode 39. The collet 47 is provided below a collet holder 49 that holds the collet 47. The collet holding hole 51 that opens is detachably inserted. The collet holding hole 51 is provided with a water channel 53 that communicates with the hollow hole of the rotary shaft 29.

An annular spacer 55 having the same diameter as that of the collet 47 is inserted between the upper portion of the collet holding hole 51 and the collet 47, and a storage chamber 57 for storing water from the water channel 53 is formed inside the annular spacer. It is formed.
As shown in FIGS. 4 and 5, on the outer periphery of the collet 47, four water channel grooves 59 communicating from the storage chamber 57 to the tip portion 47 h of the collet 47 are provided.

  The tip 47h of the collet 47 is provided with a cross-shaped split groove 63 that reaches the chuck hole 61 of the collet 47 so that the tip 47h can be easily elastically deformed. Further, a collar-like locking portion 65 that abuts on the lower end portion of the one-touch coupler 25 is provided on the outer periphery of the lower portion of the collet holder 49.

  At the lower end of the collet holder 49, a collet fixing member 67 that engages with the tapered portion at the tip of the collet 47 and fastens the collet 47 is provided. The collet fixing member 67 includes a female screw 71 that is screwed into a male screw 69 at the lower end of the collet holder 49. By rotating the collet fixing member 67, the collet 47 can be opened or fixed. .

  Further, the above-described collet fixing member 67 is provided with a jet nozzle 73 that causes water flowing out from the four water channel grooves 59 of the collet 47 to be jetted so as to surround the rod-shaped electrode 39 as a water jet WJ. .

  On the other hand, as shown in FIG. 6, the electrode guide means 41 includes an electrode guide sleeve 77 provided with an electrode guide 75 for guiding the lower end portion of the rod-shaped electrode 39 attached to the electrode holder means 27 perpendicularly to the workpiece. Is provided.

  More specifically, the lower portion of the electrode guide sleeve 77 is formed with a small-diameter portion 77a having a smaller diameter than the body portion of the electrode guide sleeve 77, and a ceramic electrode guide 75 is press-fitted into the small-diameter portion 77a. The electrode guide sleeve 77 is integrated. This is because the ceramic electrode guide 75 is brittle but has high wear resistance, so that the ceramic electrode guide 75 is protected by an electrode guide sleeve 77 made of a tough material (for example, metal).

  On the support plate 43 provided at the lower end portion of the slide base 17, an electrode holder 79 having an upper portion 78 is fixed by a fastening member (not shown) such as a bolt. The electrode holder 79 is provided with a mounting hole 81 opened upward for mounting the electrode guide sleeve 77 and the like. A small hole 83 having a smaller diameter than the mounting hole 81 is provided at the bottom of the mounting hole 81.

  The electrode guide sleeve 77 is attached to the electrode holder 79 so that the stepped portion of the electrode guide sleeve 77 is brought into contact with the bottom of the electrode holder 79 and the small diameter portion 77a protrudes from the small hole 83 in the bottom.

  An inner sleeve 85 coaxial with the electrode guide 75 is fitted to the axial center portion of the electrode guide sleeve 77. An electrode guide hole 87 that is slightly larger than the diameter of the electrode guide hole of the electrode guide 75 is provided in the axial center of the inner sleeve 85. The upper end surface of the inner sleeve 85 is at the same level as the upper surface of the electrode guide sleeve 77, and the funnel-shaped fluid that converges from the upper end surface of the inner sleeve 85 to the electrode guide hole 87 on the upper end surface of the inner sleeve 85. A guide part 89 is formed. The outer periphery of the upper end surface of the electrode guide sleeve 77 is slightly chamfered.

  A spacer 91 is provided on the electrode guide sleeve 77. On the lower surface of the spacer 91, a recessed countersink hole 96 is provided below and engages with the chamfering of the upper surface of the electrode guide sleeve 77, and an upwardly protruding convex portion 98 is formed on the upper surface.

  In the spacer 91, a ceramic upper electrode guide 101 is mounted coaxially with the electrode guide 75 in a mounting hole 92 provided in the lower surface of the spacer 91.

  When the countersink hole 96 of the spacer 91 is engaged with the chamfered portion of the electrode guide sleeve 77, the upper electrode is placed on the spacer 91 so that the lower end surface of the upper electrode guide 101 coincides with the upper end surface of the inner sleeve 85. The guide 101 is fitted and held.

  In addition, an outer annular groove 93 is provided on the outer peripheral portion of the spacer 91, and an inner annular groove 95 that opens toward the lower end of the spacer 91 is provided around the upper electrode guide 91 in the center. The two annular grooves (93, 95) communicate with each other through four flow paths 97 (a, b, c, d). A gas supply port 103 that communicates with the outer annular groove 93 is provided in the flange portion 78 of the electrode holder 79.

  In addition, an opening 94 that opens to the top of the spacer 91 is provided above the mounting hole 92 in which the upper electrode guide 101 is mounted.

  Therefore, the gas supplied from the gas supply source (not shown) to the gas supply port 103 passes through the outer annular groove 93, the flow path 97 (a, b, c, d), and the inner annular groove 95, and the inner sleeve. 85 fluid guides 89 are supplied.

  The gas supplied to the fluid guide 89 is supplied to the electrode guide 75 through the electrode guide hole 87 of the inner sleeve 85. The clearance between the electrode passing through the electrode guide 75 and the electrode guide 75 is about 0.001 to 0.002 mm, and during the electric discharge machining, gas is passed through the clearance into the machining liquid (usually tap water or pure water). Released.

  Further, a female screw is formed in the mounting hole 81 in the upper part of the spacer 91, and a fixing member 105 having a male screw is screwed into the female screw part. A concave portion 100 corresponding to the convex portion 98 on the upper surface of the spacer 91 is formed on the lower surface of the fixing member 105.

  The electrode guide sleeve 77 and the spacer 91 can be pressed and fixed to a predetermined position of the mounting hole 81 of the electrode holder 79 by appropriately screwing the fixing member 105 into the female screw portion on the electrode holder 79. it can.

  Further, the upper part of the fixing member 105 is in a state of projecting to the outside of the mounting hole 81 of the electrode holder 79, and a funnel-shaped fluid guide part 107 opening upward is formed on the upper part of the fixing member 105. A small hole 109 facing the opening 94 provided in the upper part of the spacer 91 is provided at the bottom of the funnel-shaped fluid guide 107. The opening 94 and the small hole 109 have such a size that the rod-shaped electrode rod 39 and the water jet can pass through.

  When electric discharge machining of a small hole is performed in the thin hole electric discharge machining device having the above-described configuration, if the upper portion of the rod-shaped electrode 39 is mounted on the collet 47 of the electrode holder means 27 and water is supplied from the water supply device to the electrode holder means 27, the electrode holder means 27, a water jet surrounding the periphery of the electrode is ejected from the jet nozzle 73 through the water channel groove on the outer periphery of the collet 47, and a fine rod-shaped electrode 39 of about 0.010 to 0.200 mm is guided from the electrode holder means to the electrode guide. Up to the means 41, it can be fed in a straight line without bending due to a reaction force caused by friction with the electrode guide.

  In addition, since the electrode is wrapped with a water jet, it is possible to suppress the deflection of the electrode (the jumping rope phenomenon) that occurs due to the rotation of the electrode, and it is possible to perform highly accurate fine hole processing.

  Further, by supplying gas to the electrode guide of the electrode guide means during processing, and performing the fine hole electric discharge processing while discharging the gas from the electrode guide into the processing liquid, the electrode is supported by the gas, and the electrode guide and The frictional resistance with the electrode can be made minute.

As the gas supplied to the electrode guide, air that does not normally cost is used, but other gases such as nitrogen, hydrogen, oxygen, argon, helium, and carbon dioxide can be used. . Further, the temperature of the gas to be supplied is better when the temperature is lower, and preferably around 4 ° C. The pressure of the gas to be supplied is preferably about 0.05 to 1.00 (kg / cm ² ) as a gauge pressure at the gas supply port 103 of the electrode guide means.

  As described above, by supplying gas to the electrode guide part being processed, since the sewage from the processed part does not enter the electrode guide, the electrode guide is not clogged, and stable electrode feeding can be performed for a long time. Become.

  Further, since the metal ions in the working fluid are reduced and attached to the electrode guide by the gas, the hole of the electrode guide can be prevented from gradually becoming smaller. As a result, stable electrode feeding for a long time became possible.

  In addition, since the distance between the electrode guide and the workpiece that requires 0.3 to 0.5 mm can be shortened to 0.05 to 0.20 mm, the machining accuracy is improved. Specifically, when the electrode diameter was 0.03 mm, the minimum drilled hole diameter was about 0.060 mm, but in the present invention, it became possible to fall within the range of 0.050 to 0.052 mm.

  In an embodiment of the present invention, a jet nozzle for generating a water jet is provided in the electrode holder means, and the rod-shaped electrode is guided by the water jet and simultaneously fed to the work while rotating with respect to the workpiece. As described above by way of example, it is also known that no water jet is used to guide the rod-shaped electrode to the electrode guide means.

  For example, there are some in which two intermediate guide means for guiding the rod-like electrode are arranged at an appropriate distance in the vertical direction between the electrode holder means and the electrode guide means. The intermediate guide means is provided so as to be retractable in the horizontal direction in order to avoid interference with the electrode holder when the electrode holder is lowered.

  In addition, the present invention is highly effective in narrow hole processing using an electrode having a diameter of 0.2 mm or less and 0.01 mm or less.

  FIG. 7 shows an example in which the electrode insertion device 201 with respect to the electrode guide according to the present invention is applied to the aforementioned fine hole electric discharge machining device 1.

  The electrode insertion device 201 is installed at an appropriate position in the machining tank 7 of the fine hole electric discharge machining device 1. The appropriate position is the vicinity of the machining position where the workpiece W is machined, and it is desirable that the electrode insertion device 201 be installed at a position as close as possible to the machining position.

  The electrode insertion device 201 is provided with a detachable vacuum suction head 205 below the electrode guide means 41. The vacuum suction head 205 is formed with a cylindrical recess 203 that opens upward, and the recess 203 is slidable in the Z-axis direction with the lower portion of the electrode holder 79 constituting the electrode guide means 41. And it is provided so that it can engage in an airtight state.

  As a means for maintaining airtightness, in the embodiment, the seal member 207 is attached to the inner diameter portion of the recess 203, but instead of using the seal member 207, the engagement clearance of the engagement portion may be set small. It is possible to obtain performance that can withstand practical use.

  In order to discharge the air in the sealed space 209 formed between the lower end portion of the electrode holder 79 and the recess 203 by the engagement of the recess 203 of the vacuum suction head 205 and the lower portion of the electrode holder 79, the recess 203 Exhaust means 215 is connected to an exhaust hole 211 provided at the bottom of this through a pipe 213.

  The exhaust means 215 of the embodiment is an aspirator type vacuum suction device that exhausts air in the sealed space 209 via a silencer 219 using air flowing out from the air pressure source 217 at high speed. However, a vacuum pump may be used.

  Next, the structure of the electrode penetration detection means 221 for detecting that the electrode guide means 41 has been penetrated will be described.

  In the state shown in FIG. 7, the electrical conduction detects that the rod-like electrode has penetrated the electrode guide means at the bottom of the recess 203 of the vacuum suction head 205 and almost directly below the electrode guide 75. A detection electrode 223 is disposed.

  The detection electrode 223 is connected to the minus side of the DC power source 227 via a conducting wire 225, and the plus side of the DC power source is slid onto the rod-shaped electrode 39 located above the electrode guide means 41 via the conducting wire 229. It is connected movably. Therefore, an electric circuit in which a current from the DC power source 227 flows through the conducting wire 229, the rod-like electrode 39, and the conducting wire 225 is formed by the lower end portion of the rod-like electrode 39 coming into contact with the detection electrode 223.

  A continuity detector 231 is provided in parallel with the DC power supply 227. The continuity detector 231 detects continuity by detecting a voltage drop due to contact between the rod-shaped electrode 39 and the detection electrode 223.

  The continuity detector 231 may detect the current flowing through the circuit by the contact between the rod-shaped electrode 39 and the detection electrode 223. Further, if the vacuum suction head 205 is made of a conductor and the negative side of the vacuum suction head 205 and the DC power supply 227 is connected via the conductors 233 and 225, the vacuum suction head 205 itself can be used in place of the detection electrode 223. You can also

  Hereinafter, the operation when the rod-shaped electrode 39 is inserted into the electrode guide means 41 using the electrode insertion device 201 having the above-described configuration in the above-described fine hole electric discharge machining apparatus 1 will be described.

  First, the X and Y axes of the slide base 17 are appropriately driven and positioned so that the electrode guide means 41 provided on the slide base 17 comes directly above the electrode insertion device 201.

  Next, the Z-axis slide 19 is lowered and inserted to a position where the lower part of the electrode holder 79 constituting the electrode guide means 41 is engaged with the upper part of the vacuum suction head 205.

  Subsequently, the electrode holder means 27 to which the rod-shaped electrode 39 is attached is placed on the Z axis so that the lower end portion of the rod-shaped electrode 39 is inserted into the upper electrode guide 101 and the lower electrode guide 75 constituting the electrode guide means 41. At the same time as it is lowered while being controlled, the exhaust means 215 is operated to exhaust the air in the vacuum suction head 205 and suck the rod-shaped electrode 39, thereby strongly assisting insertion into the electrode guides (101, 75). .

  As described above, the rod-shaped electrode 39 is fed from above while being pulled downward by the suction operation by the vacuum suction head 205. Therefore, even if the electrode diameter is as small as 0.01 mm to 0.03 mm, the electrode guide ( 101,75) can be inserted.

  Further, if the rod-shaped electrode 39 penetrates the electrode guide 75, the lower end portion reaches and contacts the detection electrode 223, and it is detected by the conduction detector 231 that the electrode guide 75 is penetrated.

  When it is detected that the rod-shaped electrode 39 has penetrated the electrode guide means, the electrode guide means 41 can be moved to a machining position to perform electric discharge machining.

  In the insertion of the rod-shaped electrode 39 into the electrode guide means 41 described above, a water jet surrounding the rod-shaped electrode 39 is not used, but it is of course possible to use a water jet together.

The front view of the fine hole electric discharge machining apparatus which concerns on this invention. The right view of the fine hole electric discharge machining apparatus which concerns on this invention. The enlarged view of the Z-axis slide part in FIG. The enlarged explanatory view of the A section in FIG. FIG. 5 is a cross-sectional view of the collet 47 in FIG. 4 along the line CC. The enlarged explanatory view of the B section in FIG. Explanatory drawing of the electrode insertion apparatus with respect to the electrode guide which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thin hole electrical discharge machining apparatus 3 Base 5 Work table 7 Processing tank 9 (a, b) Column 11 X-axis carriage 13 Y-axis carriage 17 Slide base 19 Z-axis slide 21 Z-axis feed screw 23 Servo motor 24 Nut 25 One-touch coupler 27 Electrode holder means 29 Rotating shaft 31 Pulley 33 Rotary joint 35 Pipe line 37 Electrode motor 39 Rod electrode 41 Electrode guide means 43 Support plate 45 Fastening member 47 Collet 49 Collet holder 51 Collet holding hole 53 Water passage 55 Annular spacer 57 Storage chamber 59 Water passage Groove 61 Chuck hole 63 Split groove 65 Locking portion 67 Fixing member 69 Male screw 71 Female screw 73 Jet nozzle 75 Electrode guide 77 Electrode guide sleeve 77a Small diameter portion 79 Electrode holder 81 Mounting hole 83, 109 Small hole 85 Inner sleeve 85 Tube 87 Electrode guide hole 89, 107 Fluid guide part 91 Spacer 92 Mounting hole 93 Outer annular groove 94 Opening 95 Inner annular groove 96 Counter bore 97 Flow path 98 Convex part 100 Concave part 101 Upper electrode guide 103 Gas supply port 105 Fixing member DESCRIPTION OF SYMBOLS 201 Electrode insertion apparatus 205 Vacuum suction head 207 Seal member 209 Sealed space 211 Exhaust hole 215 Exhaust means 217 Air pressure source 219 Silencer 221 Electrode penetration detection means 223 Detection electrode 225, 229 Conductor 227 DC power supply 231 Continuity detector WJ Water jet W Workpiece

Claims (3)

  A narrow hole discharge having electrode holder means for holding the upper portion of the rod-shaped electrode and electrode guide means for guiding the lower portion of the rod-shaped electrode, and feeding the workpiece while rotating the rod-shaped electrode by the electrode holder means In a processing apparatus, the lower part of the electrode guide means is engaged with a detachable vacuum suction head, and the rod-shaped electrode is inserted into the electrode guide means while being sucked by the vacuum suction head. Electrode insertion method.   A narrow hole discharge having electrode holder means for holding the upper portion of the rod-shaped electrode and electrode guide means for guiding the lower portion of the rod-shaped electrode, and feeding the workpiece while rotating the rod-shaped electrode by the electrode holder means In the processing apparatus, an electrode characterized in that a detachable vacuum suction head is provided below the electrode guide means, and electrode penetration detection means for detecting that the rod-shaped electrode has penetrated the electrode guide means. Electrode insertion device for the guide.   3. The electrode insertion device for an electrode guide according to claim 2, wherein the vacuum suction head has a recessed portion opened upward so as to be engageable with a lower portion of the electrode guide means, and the lower portion of the electrode guide means and the recessed portion. An exhaust means for exhausting air in a sealed space formed by engagement, and the electrode penetration detection means is provided with a detection electrode that can contact the lower end of the rod-shaped electrode on the vacuum suction head, and An electrode for an electrode guide, wherein a continuity detector for detecting electrical continuity between the rod-shaped electrode and the detection electrode is provided in an electric circuit formed by contact between the detection electrode and a lower end portion of the rod-shaped electrode. Insertion device.

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