JPS6154531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrode support and rotation device for an electric discharge machining apparatus, and more particularly to an electrode support and rotation device that rotates a machining electrode while detachably holding it.

Generally, the electrode support and rotation device used in numerically controlled electrical discharge machining equipment is capable of simultaneous two-axis control of the direction of movement (hereinafter referred to as the Z-axis) and the rotation angle (hereinafter referred to as the C-axis), such as thread cutting and spiral gear machining. Items that require arbitrary angle indexing of the electrode and simultaneous 2-axis or simultaneous 3-axis control of the C-axis and It is currently used to equalize electrode consumption. However, this type of electrode support and rotation device has various problems. One of these is the problem unique to electric discharge machining, which is that when machining with a full-form electrode, it is necessary to always maintain a precise coupling relationship between the electrode and the main spindle of the rotation support device, and to ensure high precision reproducibility when attaching and detaching the electrode. need to be retained. This is a basic condition that is absolutely necessary when machining is performed using two or several electrodes, such as rough finishing electrodes and finishing electrodes.

In the conventional electrode support rotation device, as shown in FIG. 1, electrode holders (shanks) 14 are mounted at equal intervals on the shaft end of the rotating spindle 12 of the electrode support rotation device 10, as a means of connecting the electrode and the support rotation device. A pull stud pulling device (not shown) is provided with four V cross concave surfaces 18 that engage with four V cross convex surfaces 16 provided in By pulling up the V-cross convex surface 16 and the V-cross concave surface 18 by pulling up the V-cross convex surface 16 and the V-cross concave surface 18 as shown in FIG.
Normally, the positional relationship between the reference plane of the electrode 22 and the angular origin of the rotating spindle 12 is strictly regulated and fixed on the rotating spindle 12.

However, with this type of V-cross surface coupling method, there are a total of eight contact surfaces for positioning, so it is nearly impossible due to manufacturing technology to precisely engage each surface without any gaps, and even if it is possible, it is extremely difficult. It becomes expensive,
Moreover, since the angles forming the V-cross surfaces 16 and 18 each include manufacturing errors, the V-cross convex surface 16 and the
Even when the cross concave surfaces 18 are engaged, the state of each engagement surface becomes an averaged semi-contact form, and errors in the angle and surface smoothness forming each V cross surface are averaged but unstable. Positioning is done on the basis of perfect balance.

Therefore, as shown in Figure 2B, the pull stud 20
The engagement state changes depending on the magnitude of the pulling force of
This results in a state where the electrode has a certain angle θ, and the accuracy of electrode attachment decreases.

Furthermore, as described above, since positioning is performed in an average contact state, the engagement state gradually changes due to minute wear on each engagement surface with each repeated use, making it impossible to maintain high positioning accuracy.

Furthermore, it is extremely difficult to align the virtual central axes of the V-cross convex surface 16 and the V-cross concave surface 18 with the rotation center axis of the spindle 12 with high precision due to manufacturing errors, and as shown in FIG. The central axis of No. 12 is installed with an eccentricity e, and if the electrode is rotated and processed in this state, the outer diameter of the electrode will be equivalent to processing with an electrode that has a virtual outer diameter larger by 2e. Therefore, it is extremely difficult to obtain the desired processed shape or accuracy.

Furthermore, because of the connection by the uneven surface of the V cross, it is difficult to pass the machining liquid through the electrode 22 from the support rotation device 10 side, which makes the gap between the electrodes unstable during machining, lowers the machining efficiency, and causes the unevenness of the V cross. Since the engaging portion of the surface serves as a discharge current path for machining, if the uneven surface of the V cross is in an average contact state, the contact resistance will be large and the resistance loss of the current will be large.

Furthermore, due to the constraints on the structure of the pulling device and pull stud, it is impossible to increase the pulling force of the pull stud, and the length of the uneven surface of the V cross cannot be increased, so if an external force is applied to the electrode, it cannot resist it. It has many drawbacks, such as not only the V-cross being tilted, but also the state of engagement of the uneven surface of the V-cross changes when subjected to external force, and there is no restorability.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to facilitate the attachment and detachment of processing electrodes, and to reliably position the support rotation device and the electrodes held therein with high precision. It is an object of the present invention to provide a novel electrode support and rotation device for an electric discharge machining apparatus that can omit phase adjustment for centering the electrode when replacing the electrode during electric discharge machining or the like.

In order to achieve the above object, the present invention provides an electrode support and rotation device for an electric discharge machining apparatus that rotates a machining electrode while detachably holding it, and includes a cylindrical rotating spindle supported on a non-rotating part, and a cylindrical electrode holding sleeve that is fitted with working fluid passages formed in at least two locations in the axial direction on the inner circumferential surface of the electrode and whose upper end face is closed; and a slidable electrode that faces the electrode holding sleeve via the working fluid. a fluid pressing piston, an operating punch which normally presses the fluid pressing piston with a compression spring and is connected to a pressing force release mechanism disposed in the non-rotating part, and an operating punch disposed in the non-rotating part. a positioning clamp having a rotation mechanism for rotating the rotary spindle provided therein, a positioning pin protruding from a position near the open end of the electrode holding sleeve, and a pressing elastic body disposed with a gap therebetween; A mechanism for holding the processing electrode within the electrode holding sleeve, and a positioning pin formed therein being held by the positioning holding mechanism and held by working fluid pressure. shall be.

Hereinafter, preferred embodiments of the present invention will be described based on FIGS. 3 to 6.

FIG. 3 shows a longitudinal sectional view of the device of the present invention, and 2
6 is the main shaft of the numerically controlled electrical discharge machining device, which is servo-fed in the vertical direction by a suitable operating mechanism (not shown), and its moving position is detected by a position detector (not shown), and the numerical control device Feedback will be sent to you.

28 is a cylindrical rotating spindle, and a thrust needle bearing 3 is installed in a cylindrical case 30 fixed to the main shaft 26 of the electrode support rotating device 10.
2. It is rotatably supported via a radial ball bearing 34. 36 is the rotating spindle 2
It is firmly attached to the rotary spindle 28 by press fitting or the like with a positioning pin protruding from the end face of the holder 8 near the center opening.

At the position of the positioning pin 36, as shown in FIG. 4, a positioning pin 42, which is formed in the center of a mounting shank 40 integrally formed with the electrode 38 and protrudes in a direction perpendicular to the axial direction, is clamped. A rod-shaped spring 44 is fixed with a bolt 48 in a space 46 provided on the end face of the rotating spindle 28, and the positioning pin 36 and spring 44 constitute a positioning clamping mechanism. A guide portion that curves outward is provided at the lower end of the spring 44 to facilitate insertion of the positioning pin 42. Reference numeral 49 denotes a liquid passage hole bored through the electrode 38 and the shank 40 in the axial direction thereof.

Reference numeral 50 denotes a cylindrical electrode holding sleeve with an upper end closed, which is coaxially and firmly press-fitted into the lower inner peripheral surface of the rotating spindle 28, and whose inner diameter is a number smaller than the outer diameter of the shank 40 of the electrode 38. It is made approximately 10μm larger and has annular grooves 5 at two locations on the top and bottom of the outer periphery.
2 and 54 are bored, and these annular grooves and the sleeve upper end space 56 are communicated by a passage 58. Furthermore, the annular grooves 52 and 54 and the space 56
The passage 58 is filled with a working fluid 60 such as oil.

Reference numeral 62 denotes a fluid-pressing piston 6 having an O-ring 64 inserted through the upper inner circumferential surface of the rotating spindle 28 so as to face each other through the sleeve 50 and the working fluid 60.
Reference numeral 6 denotes a metal bearing fitted on the inner peripheral surface of the upper end of the rotating spindle 28, and reference numeral 68 denotes a peripheral collar 7 extending inward at the upper end, which is screwed onto the outer peripheral surface of the upper end of the rotating spindle 28.
A cylindrical body 72 having a diameter of 0 is a mantle integrally attached to the main shaft 26 surrounding the cylindrical body 68 by bolts 73, and a piston 74 is disposed on the inner circumferential surface of the upper end of the mantle 72. .

Reference numeral 76 is an operating punch that is vertically slidably disposed at the axis of the cylindrical body 68 and the mantle 72, and has a lower end facing the piston 62 and an upper end that is connected to the piston 74 by a nut 78. connected together,
Further, a cylindrical body 82 having a circumferential flange 80 extending outwardly at the lower end is attached to the outer circumferential surface at a position inside the cylindrical body 68, and is inserted between the circumferential flange 80 of this cylindrical body 82 and the circumferential flange 70 of the cylindrical body 68. A compression coil spring 84 normally presses the piston 62 downward.

86 is an oil passage bored in the mantle 72;
8 is a solenoid valve connected to the oil passage 86 via piping 90, 92 is an oil pump connected to the solenoid valve 88, and 94 is an oil tank.

The rotating spindle 28 is then rotationally driven by a rotational drive mechanism which will be described below with reference to FIG. That is, 96 is a spacer that is fitted into the upper part of the rotating spindle 28 and comes into contact with the thrust bearing 32, and 98 is a worm wheel that is also precisely positioned and attached to the rotating spindle 28, both of which are secured by a nut 100. It is firmly attached. 102 is the case body 30 and the mantle 72
It is a rotating plate that is precisely inserted into the space 104 between the parts, and is connected to the fifth
It is rotatably arranged as shown by the arrow in the figure. 10
A worm shaft 8 is rotatably supported on the rotating plate 102 by an angular contact bearing 110 and precisely meshes with the worm wheel 98;
Numerals 12 and 114 are engagement pins that are provided through both ends of the worm shaft 108, respectively, and are precisely engaged in U-shaped grooves 120 and 122 formed in coupling rings 116 and 118 made of insulating material, respectively. ,
The coupling rings 116 and 118 are connected to the drive motor 1.
24 and the rotating shaft of the angle detector 126 are firmly attached by set screws 128 and 130. The drive motor 124 and the angle detector 126 are attached to the rotating plate 102 via flanges 132 and 134 and insulating plates 136 and 138, respectively, and the inner end surfaces of the flanges 132 and 134 are connected to the outer ring of the angular contact bearing 110, respectively. The movement of the worm shaft 108 in the thrust direction is restricted by the contact. Furthermore, the drive motor 124
The purpose of electrically insulating the angle detector 126 from the support and rotation device 10 is to improve noise resistance during electrical discharge machining, and is separated from the pulse current path supplied to the discharge electrode.

The angle detector 126 is also equipped with an origin signal oscillation circuit (not shown) so that when the rotational direction position of the rotating spindle 28 shown in FIG. 4 is set as the angle origin, a specific origin signal is obtained at this position. ing. In this case, since a reduction mechanism using a worm gear is inserted, the origin signal of the angle detector 126 is determined by the reduction ratio N during one revolution of the spindle.
In order to eliminate this inconvenience, a magnetic switch consisting of a magnet 140 provided on the outer cylinder of the power supply case 160 and a magnetic detector 142 fixed to the plate 164 with a gap between the magnet 140 and the magnetic detector 142, which will be described later, is used. The angular origin of the rotating spindle 28 is defined by detecting that the output signal and the angular origin signal obtained from the angle detector 126 match or are within a certain phase difference.

The rotating plate 102 has a pin 1 protruding therefrom.
44 and a metal fitting 146 disposed on the mantle 72, the worm shaft 108 is rotated counterclockwise as viewed in FIG. 5 so as to mesh with the worm wheel 98. , the biasing force thereof is adjusted by the adjustment bolt 150, and therefore it is possible to reduce the backlash of the worm wheel 98 and the worm shaft 108 to zero, and to prevent rattling due to wear of the toothing surfaces.

152 is an oil seal that comes into contact with the outer peripheral surface of the rotating spindle 28 and is fixed to the case body 30; 154;
156 is a fluid passage extending from the oil seal 152 into the sleeve 50, and 156 is a fluid passage extending from the oil seal 152 to a port 158 on the outer circumferential surface of the case body 30, and the port 158 has a hose connected to a machining fluid supply source. etc. are connected to supply machining fluid.

Reference numeral 160 denotes a power supply case fixed to the lower end of the rotating spindle 28 and covering the lower end surface of the case body 30;
2 is a power supply brush attached to a plate 164 fixed to the case body 30, and 166 is a feeder that supplies machining current.

The configuration of the embodiment of the present invention has been described above, and its operation will now be described. Assuming that the solenoid valve 88 is now on and the oil pump 92 is being driven, oil in the oil tank 94 is supplied to the space below the piston 74 through the piping 90 and the passage 86, as shown in FIG. The working punch 76 then assumes a raised position against the force of the compression spring 84, and in this state, the piston 62 is in a floating state, so the pressure of the working fluid 60 is approximately zero.
Since the inner diameter of the sleeve 50 is several tens of micrometers larger than the outer diameter of the shank 40 for attaching the electrode, the shank 40 can be easily inserted into the sleeve 50.

In this state, the drive motor 124 is rotated to position the rotating spindle 28 at the angular origin position. In this case, the angular origin is defined based on the origin signal of the angle detector 126 and the output signal of the magnetic switch.

Next, the shank 40 of the electrode 38 is inserted into the sleeve 50, and the positioning pin 40 is inserted as shown in FIG.
is held between positioning pins 36 and springs 44. In this case, the positioning pin 42 is pressed toward the positioning pin 36 side by the spring 44 and at the same time is also pressed against the end surface 168 of the sleeve 50, so that it is held without easily coming off. Therefore, the shank 40 is positioned with respect to the angular origin of the rotating spindle 28, and the electrode 38 is positioned with respect to the positioning pin 42 of the shank 40, so that the dimensions of the electrode 38 on the X, Y, Z, and C axes are are all related to the origin of the rotating spindle. In other words, the mounting position of the electrode 38 is X, Y, Z with respect to the positioning pin 42 of the shank 40.
By relating the dimensions of the rotation spindle 28 and the C-axis, it is possible to automatically read the positional relationship of the rotating spindle 28 with respect to the origin, and to maintain a fixed positional relationship at all times.

Next, when the solenoid valve 88 is turned off and the oil pump 92 is stopped, the piston 74 and therefore the operating punch 76 are lowered by the return force of the compression spring 84, and the lower end of the operating punch 76 comes into contact with the piston 62 and pushes it downward. to press. At this time, the oil filled in the lower part of the piston 74 is drained through the passage 86 and piping 90 and further through the tank port of the solenoid valve 88, so the back pressure of the operating punch 76 becomes zero and the compression spring 8
It does not interfere with the return power of 4.

In this state, the working fluid 60 flows into the piston 6.
2, the pressure increases rapidly and a pressure proportional to the pressing force is obtained, so that static pressure is applied to the sleeve 50 at the annular grooves 52 and 54 toward the center. At this time, static pressure also acts in the direction of pushing the sleeve 50 downward, but since the sleeve 50 is firmly fitted into the rotary spindle 28 by a fixing means such as press fitting, there is no fear that the sleeve 50 will come off. When static pressure is applied to the sleeve 50, the thin sleeve inner surfaces 170 and 172 at the annular grooves 52 and 54 bulge toward the center.
Since this displacement occurs evenly over the entire circumference of the inner surfaces 170 and 172 of the sleeves, the outer circumferential surface of the shank 40 is pressed evenly over the entire circumference, and a self-aligning effect inevitably occurs, causing the rotating spindle to 28
The axial center of the shank 40 and the axial center of the shank 40 match extremely precisely and with high precision, and are clamped without any deviation, so that the electrode 38 is aligned with the rotating spindle 28 with the X, Y, Z, and C axes at predetermined positions. They will be installed in a certain positional relationship.

FIG. 6 shows an example of the electrodes positioned and mounted on the support and rotation device 10 in this manner. In FIG. 6, reference numeral 174 is a spiral gear electrode fixed to the shank 40, which has an angular torsion recess, and has X, Y, Z, and C points relative to the positioning pin 42.
Each dimension and angle of the axis is set. When machining the workpiece 176 using this electrode, if the surface of the workpiece 176 is the machining starting point Z ₀ , then this
Below the Z ₀ position, it is necessary to rotate the rotary spindle 28 of the support rotation device 10 by the helix angle in accordance with the amount of descent of the main shaft 26 . In this way Z and C
The concave surface of the spiral gear electrode 174 is precisely electrical discharge machined on the workpiece 176 by controlling two axes at the same time using movement command signals from the numerical control device.

Furthermore, in electrical discharge machining, servo feeding is performed according to the gap between the electrode and the workpiece, so servo feeding is precisely performed on a trajectory controlled by two simultaneous axes, the Z and C axes. In other words, servo feed is performed along a trajectory that is simultaneously controlled in two axes, Z and C, both when moving in the direction of machining progress and when the electrode rapidly regresses when the electrode and workpiece are short-circuited. It can be done.

Furthermore, when the spiral gear electrode 174 is used for rough machining, finishing machining, etc., all electrodes are attached to the shank 40 using the positioning pin 42.
If the dimensional relationships are precisely the same, then when moving to finishing after rough machining, all you need to do is turn on the solenoid valve 88, operate the oil pump 92, and replace the rough machining electrode with the finishing electrode.・There is no need to fine-tune the positional relationship of the C-axis with respect to the finishing electrode for positioning.

In addition, it is possible to perform complex machining using combinations of Z/X, Z/Y, Z/X/Y axes, etc., in addition to machining that simultaneously controls two axes of Z and C, and it is also possible to perform complex machining using combinations of Z/X, Z/Y, Z/X/Y axes, etc. This can also be done without requiring any phase adjustment.

Furthermore, the sludge generated during electrical discharge machining can be easily removed because machining fluid can be supplied from the passage provided inside the shank 40 and the electrode 38, and the cleanliness between the machining parts is always maintained at a high level. Therefore, electrical discharge machining can be performed stably, short circuits can be reduced, and machining efficiency can be improved.

As described above, according to the device of the present invention, by inserting the shank integrally attached to the machining electrode into the sleeve, it is possible to attach the processing electrode to the electrode support rotation device with high precision and force, and the electrode is The reproducibility during installation is extremely high, and the electrodes are held evenly by the static pressure of the working fluid, which bulges and displaces the sleeve toward the center axis over its entire circumference, making it easy to shank. Even if the outer circumferential surface of the sleeve wears, the center of the electrode will not deviate from the center of the rotating spindle due to its self-aligning property, and since it is a cylindrical contact, the surface pressure will be equal and uneven contact will not occur. It has the advantage of extremely little wear, allowing high precision to be maintained even after long-term use, and sufficient strength against external forces.

Furthermore, since the positioning of the rotary spindle and the electrode in the rotational direction is performed accurately and with high precision by the positioning clamping mechanism, the attachment relationship of the electrode with respect to the angular origin of the rotary spindle can be maintained constant with high precision. If the electrode is always installed in the same position relative to the positioning pin of the shank, you can omit the troublesome work of phase adjustment for centering the electrode when replacing the electrode during electrical discharge machining, increasing machining efficiency. It has characteristics that can be improved.

Furthermore, since the electrode only needs to have a shank part that is inserted into the electrode holding sleeve and no other complicated processing is required, manufacturing is extremely easy, reducing manufacturing costs and manufacturing time. have

Furthermore, since the machining fluid can be supplied through the electrode, the machining fluid can be supplied from the electrode side even during rotation, which has the effect of improving machining efficiency.

Furthermore, since the worm shaft is engaged with the worm wheel under pressure by an adjustable spring, it is possible to eliminate bumpiness and also to prevent rattling due to wear of the mating surfaces.

Furthermore, since the drive motor and angle detector are electrically insulated and attached to the support rotation device, noise resistance during electrical discharge machining is improved and malfunctions can be prevented.

Furthermore, current is supplied to the shank via the current-carrying brush and the power supply case so that the electrical path from the power supply is the shortest, and the contact area between the sleeve and shank is large and has sufficient surface pressure, so electrical contact resistance is low. It has great features such as having the effect of reducing resistance loss.

The above description merely shows one embodiment of the device of the present invention, and the fluid pressing piston 62 and the operating punch 7 are
It may be separate from 6 or may be configured integrally.

Further, the pressure release mechanism of the operating punch 76 is not limited to the piston 74, and other mechanical or electrical lifting mechanisms such as a solenoid may be used.

Further, the rotational drive mechanism of the rotary spindle 28 is not limited to the worm wheel 98 and the worm shaft 108, and other rotational drive mechanisms such as gears such as spiral bevel gears and helical bevel gears may be used.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an electrode support and rotation device of a conventional electric discharge machining device, FIGS. 2A, B, and C are schematic cross-sectional views for explaining the conventional device, and FIG. FIG. 4 is an enlarged sectional view showing the positioning clamping mechanism, FIG. 5 is a sectional view taken along line A-A in FIG. 3, and FIG. FIG. 2 is a perspective view showing the inventive device in use. Identical members in each figure are designated by the same reference numerals.
0 is an electrode support rotation device, 26 is a main shaft, 28 is a rotating spindle, 30 is a case body, 36 and 42 are positioning pins, 38 is an electrode, 40 is a mounting shank, 44 is a pressing spring, 50 is an electrode holding sleeve , 52 and 54 are annular grooves, 60 is a working fluid, 62 is a fluid pressing piston, 74 is a piston, 76 is an operating punch, 84 is a compression coil spring, 88
92 is a solenoid valve, 92 is an oil pump, 98 is a worm wheel, 102 is a rotating plate, 108 is a worm shaft, 124 is a drive motor, 126 is an angle detector,
154 and 156 are liquid passage holes, 160 is a power supply case, and 162 is a power supply brush.

Claims (1)

[Scope of Claims] 1. An electrode rotation support device for an electrical discharge machining device that rotates a machining electrode while detachably holding it, comprising: a cylindrical rotating spindle supported on a non-rotating part;
A cylindrical electrode holding sleeve that is fitted into the inner circumferential surface of the rotating spindle with working fluid passages formed in at least two locations in the axial direction and whose upper end face is closed, and facing the electrode holding sleeve via the working fluid. a slidable fluid-pressing piston, an operating punch that normally presses the fluid-pressing piston with a compression spring and is connected to a pressing force release mechanism disposed in the non-rotating part; a rotation mechanism for rotating the rotation spindle disposed in the electrode holding sleeve; a positioning pin protruding from a position near the open end of the electrode holding sleeve; and a pressing elastic body disposed with a gap therebetween. and a positioning clamping mechanism, the mounting part of the processing electrode is held in the electrode holding sleeve by the positioning clamping mechanism, and the positioning pin formed therein is held by the working fluid pressure. An electrode support rotation device for an electrical discharge machining device characterized by: 2. In the device according to claim 1,
An electrode support rotation device for an electrical discharge machining apparatus, in which a rotation mechanism includes a worm wheel fixed to a rotation spindle and a worm shaft meshing with the worm wheel. 3. In the device according to claim 1,
An electrode support rotation device for an electrical discharge machining device, in which the pressing force release mechanism is a piston disposed in a non-rotating part. 4. In the device according to claim 1,
An electrode support rotation device for an electrical discharge machining apparatus, wherein a center opening is formed in a machining electrode, and a machining fluid is supplied through the center opening.