JPH05146919A - Electrode feeding device for electric discharge machining - Google Patents

Abstract

PURPOSE:To provide a small electrode feeding device for electric discharge machining capable of delivering only an electrode, allowing a stable fixed- quantity feed, and allowing the continuous use of the electrode based on the estimated electrode abrasion. CONSTITUTION:The first piezoelectric elements 7, 27 expandable in the axial direction of an electrode 4 and the second radial piezoelectric elements 12, 32 and the third radial piezoelectric elements 20, 40 expandable in the radial direction of the electrode 4 are provided. When the first piezoelectric elements 7, 27 are expanded or shrunk, the second radial piezoelectric elements 12, 32 stored in a case 8 are expanded or shrunk in the radial direction of the electrode 4. When the radial piezoelectric elements 12, 32 and the third radial piezoelectric elements 20, 40 are expanded or shrunk, the electrode 4 is fitted or removed via electric insulators 14, 22 and exciting electrodes 41, 42, 43, 44. The 'feed' and 'return' of the electrode 4 are electrically operated by time switching of the expanding action and the shrinking action of these piezoelectric elements, thus the fixed-quantity feed and the fixed-quantity return of only the electrode 4 can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode-feeding device for electric discharge machining, and more particularly to an electrode-feeding device having a function of feeding only electrodes.

[0002]

2. Description of the Related Art Conventionally, as an electrode feeding device for an electric discharge machine, as shown in Japanese Patent Application Laid-Open No. 3-79237, the electrode is moved by utilizing expansion and contraction of a piezoelectric element to bring the electrode close to a work. It is known that electrical discharge machining is performed.

[0003]

However, in the electric discharge machine disclosed in Japanese Patent Application Laid-Open No. 3-79237, the moving body fixed to one end of the piezoelectric element holds the electrode. Electrode replacement work becomes complicated at the time of wear, and since the moving body is slidably supported on the peripheral wall of the cylinder, the feed amount of the electrode is limited by sliding resistance. Since the friction coefficient changes due to oil adhesion and the like, there is a problem that the feed amount of the electrode tends to be indefinite.

Further, the one disclosed in Japanese Patent Laid-Open No. 2-186204 is an electrode device capable of sending out only an electrode, but this one uses the change of the inner diameter of an annular piezoelectric element to perform the pressure bonding operation of the electrode ( Since a closing operation) and a detaching operation (opening operation) are performed, when feeding a shaft having a diameter of 1 mm or less, the feeding accuracy is low due to the small inner diameter contraction allowance during the operation of the piezoelectric element, and the piezoelectric elements are laminated. Since it is not a body but a monolayer body, there is a problem that the inner diameter shrinkage allowance of the piezoelectric element is relatively small and the feeding accuracy is low.

The present invention has been made in order to solve such a problem, and it is possible to feed only the electrode, to perform stable fixed amount feeding, and to continuously use the electrode assuming electrode wear. It is an object of the present invention to provide a small-sized electrode-feeding device for electric discharge machining.

[0006]

In order to solve the above-mentioned problems, the first aspect of the present invention provides an electrode-feeding device for electric discharge machining, which is of a laminated type housed in a housing and provided so as to be capable of expanding and contracting in parallel with the axial direction of the electrodes. A first axial piezoelectric element, a case fixed to the free end of the first axial piezoelectric element and movable in the axial direction of the electrode with respect to the housing, and housed in the case and expandable and contractible in the radial direction of the electrode. A second laminated piezoelectric element and a first radial contact element that abuts on a free end of the second radial piezoelectric element and crimps and separates electrodes in accordance with expansion and contraction operations of the second radial piezoelectric element. An electric insulator, a stacked third radial piezoelectric element housed in a housing and expandable / contractible in the radial direction of the electrode, and abutting on a free end of the third radial piezoelectric element, the third radial piezoelectric element Depending on the extension and contraction movements of the Characterized in that a second electrical insulator crimping and extracting.

In addition to the structure of the first aspect of the present invention, the electrode-feeding device for electric discharge machining according to the second aspect of the invention is electrically insulated from other parts by the first electrical insulator, and the extension of the second radial piezoelectric element. In operation, it has a first power feeding electrode for connecting a processing power source to the electrode. In addition to the configuration of the first or second aspect of the invention, the electrode-feeding device for electric discharge machining according to a third aspect of the invention is electrically insulated from other parts by the second electrical insulator, and the extension of the third radial piezoelectric element. In operation, it has a 2nd electric power feeding electrode which connects a processing power supply to the said electrode.

According to the electrode feed control method of the fourth invention, not only the on / off voltage applied to the element but also the analog voltage can be applied to the first piezoelectric element in the axial direction which determines the displacement amount per step of the electrode. It is characterized by comprising a control circuit for controlling. In addition to the electrode driving method of the fourth aspect of the invention, the driving method and device for controlling the electrode feed of the fifth aspect of the invention are such that the driving frequency of the piezoelectric element is the break frequency of the system (cutoff frequency)
It is characterized in that the feed of the electrode is controlled by matching with the higher resonance frequency in the region exceeding.

In addition to the electrode driving method of the fourth or fifth aspect of the invention, the driving method and device for controlling the feed of the electrode according to the sixth aspect of the present invention include a control signal for the fluctuation of the gap voltage between the electrode and the work. It is characterized in that the feed of the electrodes is controlled by reversing the phase. In addition to the configuration of the first aspect of the invention, the electrode gripping shape of the seventh aspect of the invention is such that the electrode is stably fed to the electrode gripping portion fixed to the tip end of the radial direction piezoelectric element and the electrode can be inserted when exchanging the electrode. It is characterized by having a shape intended for simplification.

[0010]

According to the electrode-feeding device for electric discharge machining of the present invention, the first piezoelectric element capable of expanding / contracting in the axial direction of the electrode, the second radial direction piezoelectric element capable of expanding / contracting in the radial direction of the electrode, and the third radial direction piezoelectric element. By switching between the expansion operation and contraction operation of these piezoelectric element groups, the "feed" and "return" of the electrodes are electrically operated, so that it is possible to perform fixed-quantity feeding and fixed-quantity returning of only the electrodes. ..

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show a first embodiment in which the present invention is applied to an electrode feeding device of a hole electric discharge machine. Electrode feeding device 1
As shown in FIG. 1, the electrode 4 is inserted into the electrode insertion hole 3 of the housing 2. In FIG. 1, the hole 3 is symmetrical with respect to the center, so for convenience of description, the structure of the right half of the hole 3 will be described first. A cylindrical piezoelectric element mounting hole 5 is formed in the housing 2 in parallel to the axial direction of the electrode 4, one end of the first axial piezoelectric element 7 is fixed to the hole bottom 5a, and the first piezoelectric element 7 is attached to the inner peripheral wall 5b. The axial piezoelectric element 7 is housed slidably in the axial direction, and the other end 7b is fixed to the case 8. The first axial piezoelectric element 7 is formed by stacking disk-shaped piezoelectric elements in the plate thickness direction.

The case 8 has a top surface 8a as shown in FIG.
The bottom surface 8b is accommodated in the housing 2 so as to be slidable in the axial direction of the electrode 4. The cylindrical hole 10 of the case 8 has a hole bottom 10a at which one end 1 of the second radial direction piezoelectric element 12 is formed.
2a is fixed. The pair of electric insulators 14 and 15 and the feeding electrode 43 housed in the case 8 are provided above and below the electrode 4 in between. The power supply electrode 43 is fitted in the bottom surface recess of the bottom surface 15 of the upper electric insulator 15. The bottom surface 14a of the lower electrical insulator 14 has the second radial piezoelectric element 1
2 is fixed to the other end 12b. The top surface 15 a of the upper electric insulator 15 is fixed to the case 8. On the top surface of the electric insulator 14 and the bottom surface of the power feeding electrode 43, arcuate recesses 14b and recesses 43b are formed so that the electrode 4 can be sandwiched therebetween.

As shown in FIG. 1, the end surface 2 of the housing 2
The housing 18 fixed to a accommodates the third radial piezoelectric element 20 in a cylindrical hole 21 formed in the radial direction of the electrode 4, and has one end of the third radial piezoelectric element 20 at the hole bottom 21a. It is fixed. The other end of the third radial piezoelectric element 20 is fixed to the electrical insulator 22. The electrical insulator 22 and the feeding electrode 44 are the same as the electrical insulator 14 and the feeding electrode 43 described above.
With the same structure as above, the electrodes 4 are provided on the top surface and the bottom surface, respectively.
It has an arcuate concave portion that can be gripped. The end face of the housing 18 has a guide hole 2 through which the electrode 4 can be inserted.
The electrode guide 25 with 5a is fixed.

The second radial piezoelectric element 12 and the third radial piezoelectric element 20 are laminated, respectively, and extend in the laminating direction when energized to raise the electric insulator 14 and the electric insulator 22, respectively, and supply power. The electrode 4 is sandwiched between the electrode 43 and the feeding electrode 44. Electrical insulator 14, electrical insulator 22
As shown in FIG. 9, the groove portion 14 into which the electrode 4 is fitted is inserted.
b and 22b are formed, and both ends of the groove portions 14b and 22b are widened so that the electrode 4 can be easily inserted.

Although the configuration of the electrode feeding device on the right half of FIG. 1 has been described above, the configuration of the left half of FIG. 1 is the same as the configuration of the right half, and therefore substantially the same components are designated by the same reference numerals. However, the description is omitted. The first axial piezoelectric element 27, the second radial piezoelectric element 32, the third radial piezoelectric element 40, and the feeding electrodes 41 and 42 shown in the left half configuration are respectively the first axial piezoelectric element 7 and the second axial piezoelectric element 27. It corresponds to the radial direction piezoelectric element 12, the third radial direction piezoelectric element 20, and the feeding electrodes 44 and 43.

In the first embodiment, the first axial piezoelectric elements 7 and 27, the second radial piezoelectric elements 12 and 32, and the third radial piezoelectric elements 20 and 40 are paired on the right side and the left side, for a total of two sets. This piezoelectric element group is provided so that the first set of piezoelectric element groups on the right side performs the feeding operation and the second set of piezoelectric element groups on the left side performs the returning operation, thus sharing the feeding function and the returning function. Is. This is because by applying only a tensile force to the electrode 4 when the electrode is fed and returned.
This is to prevent slack and to perform fixed-quantity feeding accurately. Also, the first set and the second set are each only in one direction,
In other words, by having only the feeding function or the returning function only in one direction which is opposite to each other, the accuracy of the fixed amount electrode feeding when the piezoelectric element is energized is improved.

In the first embodiment, two sets of piezoelectric element groups are provided, but it goes without saying that the present invention can achieve the above-mentioned object even with one set of piezoelectric element groups. Next, the operation of the first embodiment will be described with reference to FIGS. As shown in FIG. 3, in the initial state of the electrode feeding device 1, the first axial piezoelectric elements 7, 2
7, the second radial piezoelectric elements 12 and 32, and the third radial piezoelectric elements 20 and 40 are all in the off state. Then, the second radial piezoelectric element 12 is turned on, and the electric insulator 14 and the power feeding electrode 43 shown in FIG. 1 are closed (a). Next, the first axial piezoelectric element 7 is turned on (b). Then, the case 8 shown in FIG. 1 moves rightward in FIG. 1 due to the extension of the first axial piezoelectric element 7, and the electrode 4 moves in the sending direction (rightward) together with the electrical insulator 14 and the power feeding electrode 43. Next, the third radial piezoelectric element 20 is turned on (c), and the second radial piezoelectric element 12 is turned off (d). Next, the first axial piezoelectric element 7 is turned off (e). Then, with the electrode 4 held in that position, the electrical insulator 14 and the power feeding electrode 43 are opened, and the case 8 is contracted by the contraction of the first axial piezoelectric element 7.
Returns to the initial state shown in FIG. By repeating a series of operations from (a) to (e), the required amount of electrode 4 is sent out.

Next, the fine adjustment of the feed amount of the electrode 4 is performed by referring to FIG.
As shown in (b), the second radial direction piezoelectric element 12 is turned on from the initial state, and then, as shown in (b), by turning on the analog voltage to the first axial direction piezoelectric element 7, the first axial direction piezoelectric element is adjusted by this voltage adjustment. The extension amount of the element 7 is finely adjusted, and accordingly, the feed amount of the electrode 4 is finally finely adjusted. In addition, the discharge voltage is applied to the electrode 4 in order to perform the electric discharge between the electrode 4 and the work (not shown) and to perform the drilling by the electric discharge machining.
As shown in FIG. 5, this is performed when the second radial direction piezoelectric element 12 or the third radial direction piezoelectric element 20 is turned on. The supply voltage generated by the original power source (not shown) is applied to the electrode 4 via the power supply electrodes 43, 44 by a switching circuit (not shown). Further, as shown in FIG. 3, the application of voltage from the switching circuit to the power supply electrodes 43 and 44 is turned on and off as shown in FIG.
3 or the feeding electrode 44 is surely in contact with the electrode 4, the feeding electrode 43 or the feeding electrode 44 and the electrode 4
It suppresses a poor electrical continuity that causes a discharge or the like.

After the boring process, the electrode 4 is returned by the operation of the second set of the first axial piezoelectric element 27, the second radial piezoelectric element 32 and the third radial piezoelectric element 40. When the electrode 4 is returned, the first set of the first axial piezoelectric element 7, the second radial piezoelectric element 12 and the third radial piezoelectric element 20 in the right half shown in FIG. 1 are turned off. The return operation by the second set of the left half shown in FIG. 1 is the required return amount by repeating the series of operations (e) from the initial state as shown in FIG. 3 with the piezoelectric elements 27, 32 and 40 of the second set. Only these series of operations are repeated. This completes the one-hole machining on the work.

According to the first embodiment, it is possible to feed the piezoelectric element 7 in the right direction in FIG. 1 by the extension amount of the piezoelectric element 7 by the combined operation of turning on and off the three piezoelectric elements 7, 12, 20.
By repeating this, the required amount can be sent out. The accuracy of the position adjustment of the electrode 4 can be improved by analogly controlling the voltage applied to the piezoelectric element 7 during the energization processing.

When the electrode is attached or detached, the electrode 4 is crimped or separated by axial expansion or contraction, not by radial expansion or contraction of the piezoelectric element, so that a large amount of expansion or contraction can be secured in the axial direction, so that an electrode with a small diameter can be accurately applied. You can grab and release. Moreover, since the electrodes are pressure-bonded or separated by the axial expansion / contraction operation of the laminated piezoelectric elements, it is possible to accurately grasp and separate the electrodes having a small diameter.

When the electrodes are fed, a large amount of expansion or contraction can be secured in the axial direction of the laminated piezoelectric elements, so that the electrodes can be fed accurately. By repeating the feeding operation, the feeding amount of the electrode can be adjusted appropriately. Also, the piezoelectric element groups 7, 12, 20 and 27, 32, 4 which are separate at the time of feeding and at the time of returning
With 0, individual control at the time of feeding and returning is possible, and precise control of the feeding amount and the returning amount is possible. Further, during analog control of the piezoelectric element in the axial direction, it becomes unnecessary to re-hold the electrodes by the two radial piezoelectric elements, so that the dead time can be reduced and the responsiveness of the electrode can be improved.

Further, as an electrode feed drive system using this apparatus, the drive frequency is in a region other than a general control region, in which the drive frequency is matched with a higher-order resonance frequency exceeding the break point frequency (cutoff frequency) of the system. It is possible to control the feed of the electrodes. Therefore, in the electrode feeding when the resonance frequency of the first-axis method high piezoelectric element is used, the displacement amount per one step of the electrode becomes large, and high-frequency vibration can be applied to the electrode. At the resonance frequency, control has generally been impossible because a phase delay occurs with respect to the control signal. However, in the case of this device, since the response delay (-90 °) of the piezoelectric element is added to the delay (-90 °) of the secondary system at the resonance frequency, the delay of the system is delayed by -180 ° as a whole. Therefore, the phase of the control signal with respect to the fluctuation of the gap voltage between the electrode and the work is set to −18.
By reversing 0 °, the same control as the conventional one is possible.

Further, since the electrode 4 is linear, the electrode is continuously replenished and fed even if the electrode is worn, so that the frequency of replacement work when the electrode is worn out can be reduced, and frequent replacement work of the electrode is possible. Is unnecessary and maintenance and inspection work is easy. Next, a second embodiment of the present invention is shown in FIGS. The second embodiment is the power supply electrode 41 shown in the first embodiment,
This is an example in which a machining power source is externally supplied to the electrode 4 in place of 42, 43, and 44.

In the electrode feeding device 1, as shown in FIG. 5, the electrode 4 is inserted through the electrode insertion hole 3 of the housing 2. In FIG. 5, the hole 3 is symmetrical with respect to the center, so for convenience of description, first, the structure of the right half of the hole 3 will be described. A cylindrical piezoelectric element mounting hole 5 is formed in the housing 2 in parallel to the axial direction of the electrode 4, one end of the first axial piezoelectric element 7 is fixed to the hole bottom 5a, and the first piezoelectric element 7 is attached to the inner peripheral wall 5b. The axial piezoelectric element 7 is housed slidably in the axial direction, and the other end 7b is fixed to the case 8. First
The axial piezoelectric element 7 is formed by laminating disk-shaped piezoelectric elements in the plate thickness direction.

The case 8 has a top surface 8a as shown in FIG.
The bottom surface 8b is accommodated in the housing 2 so as to be slidable in the axial direction of the electrode 4. The cylindrical hole 10 of the case 8 has a hole bottom 10a at which one end 1 of the second radial direction piezoelectric element 12 is formed.
2a is fixed. The pair of electric insulators 14 and 15 housed in the case 8 are provided above and below with the electrode 4 interposed therebetween. The bottom surface 14a of the lower electrical insulator 14 is fixed to the other end 12b of the second radial piezoelectric element 12. The top surface 15 a of the upper electric insulator 15 is fixed to the case 8. On the top surface of the electric insulator 14 and the bottom surface of the electric insulator 15,
Arc-shaped recesses 14b and 15b are formed so that the electrode 4 can be sandwiched therebetween.

As shown in FIG. 5, the end surface 2 of the housing 2 is
The housing 18 fixed to a accommodates the third radial piezoelectric element 20 in a cylindrical hole 21 formed in the radial direction of the electrode 4, and has one end of the third radial piezoelectric element 20 at the hole bottom 21a. It is fixed. The other end of the third radial piezoelectric element 20 is fixed to the electrical insulator 22. The electric insulator 22 and the electric insulator 23 have the same configuration as the electric insulator 14 and the electric insulator 15 described above, and have arc-shaped concave portions on the top and bottom surfaces thereof, respectively, into which the electrodes 4 can be gripped. There is. Further, an electrode guide 25 having a guide hole 25a through which the electrode 4 can be inserted is fixed to the end surface of the housing 18.

The second radial direction piezoelectric element 12 and the third radial direction piezoelectric element 20 are laminated, respectively, and extend in the laminating direction when energized to raise the electric insulator 14 and the electric insulator 22, respectively. The electrode 4 is sandwiched between the insulator 15 and the electrical insulator 23. Although the configuration of the electrode feeding device on the right half in FIG. 5 has been described above, the configuration of the left half of FIG. 5 is similar to the configuration of the right half, and therefore, substantially the same components are denoted by the same reference numerals and will not be described. Is omitted. The first axial piezoelectric element 2 shown in the left half configuration
7, the second radial piezoelectric element 32, and the third radial piezoelectric element 40 correspond to the first axial piezoelectric element 7, the second radial piezoelectric element 12, and the third radial piezoelectric element 20, respectively.

Next, the operation of the second embodiment will be described with reference to FIGS. 7 and 8. As shown in FIG. 7, in the initial state of the electrode feeding device 1, the first axial piezoelectric elements 7, 27,
The second radial piezoelectric elements 12 and 32 and the third radial piezoelectric elements 20 and 40 are all in the off state. Then, the second radial direction piezoelectric element 12 is turned on, and the electric insulator 1 shown in FIG.
4 and 15 are closed (a). Next, the first axial piezoelectric element 7 is turned on (b). Then, the case 8 shown in FIG. 1 moves to the right in FIG. 5 due to the extension of the first axial piezoelectric element 7, and the electrode 4 moves in the feed direction (to the right) together with the electrical insulators 14 and 15. Then, the third radial piezoelectric element 2
0 is turned on (c), and the second radial piezoelectric element 12 is turned off (d). Next, the first axial piezoelectric element 7 is turned off (e). Then, with the electrode 4 held at that position, the electrical insulators 14 and 15 are opened, and the case 8 returns to the initial state shown in FIG. 5 due to the contraction of the first axial piezoelectric element 7. By repeating a series of operations from (a) to (e), the required amount of electrode 4 is sent out.

Next, the fine adjustment of the feed amount of the electrode 4 is performed with reference to FIG.
As shown in (b), the second radial direction piezoelectric element 12 is turned on from the initial state, and then, as shown in (b), by turning on the analog voltage to the first axial direction piezoelectric element 7, the first axial direction piezoelectric element is adjusted by this voltage adjustment. The extension amount of the element 7 is finely adjusted, and accordingly, the feed amount of the electrode 4 is finally finely adjusted. Then, by applying a discharge voltage from a slip ring (not shown) to the electrode 4, a discharge is generated between the electrode and a work (not shown), and drilling is performed by electric discharge machining.

After completion of the boring process, the electrode 4 is returned by the operation of the second set of the first axial piezoelectric element 27, the second radial piezoelectric element 32 and the third radial piezoelectric element 40. When the electrode 4 is returned, the first set of the first axial piezoelectric element 7, the second radial piezoelectric element 12 and the third radial piezoelectric element 20 in the right half shown in FIG. 5 are turned off. The return operation by the second set of the left half shown in FIG. 5 is the required return amount by repeating the series of operations (e) from the initial state as shown in FIG. 7 with the piezoelectric elements 27, 32 and 40 of the second set. Only these series of operations are repeated. This completes the one-hole machining on the work.

According to the second embodiment, it is possible to feed the piezoelectric element 7 in the right direction in FIG. 5 by the extension amount of the piezoelectric element 7 by the on / off combination operation of the three piezoelectric elements 7, 12, 20.
By repeating this, the required amount can be sent out. The accuracy of the position adjustment of the electrode 4 can be improved by analogly controlling the voltage applied to the piezoelectric element 7 during the energization processing. Also, during analog control, the dead time due to electrode re-grabbing can be shortened, so the responsiveness of the electrodes is improved.

Further, as an electrode feed drive method using this apparatus, the drive frequency is in a region other than a general control region, in which the drive frequency is matched with a higher-order resonance frequency exceeding the break point frequency (cutoff frequency) of the system. It is possible to control the feed of the electrodes. Therefore, in the electrode feeding when the resonance frequency of the first-axis method high piezoelectric element is used, the displacement amount per one step of the electrode becomes large, and high-frequency vibration can be applied to the electrode. At the resonance frequency, control has generally been impossible because a phase delay occurs with respect to the control signal. However, in the case of this device, since the response delay (-90 °) of the piezoelectric element is added to the delay (-90 °) of the secondary system at the resonance frequency, the system delay is delayed by -180 ° as a whole. .. Therefore, the phase of the control signal with respect to the variation of the gap voltage between the electrode and the work is -1.
By reversing by 80 °, the same control as the conventional one becomes possible.

When the electrode is attached or detached, the electrode 4 is crimped or released by axial expansion or contraction instead of radial expansion or contraction of the piezoelectric element, so that a large expansion or contraction amount can be secured in the axial direction, so that an electrode with a small diameter can be accurately applied. You can grab and release. Moreover, since the electrodes are pressure-bonded or separated by the axial expansion / contraction operation of the laminated piezoelectric elements, it is possible to accurately grasp and separate the electrodes having a small diameter.

When the electrodes are fed, a large amount of expansion or contraction can be secured in the axial direction of the laminated piezoelectric elements, so that the electrodes can be fed accurately. By repeating the feeding operation, the feeding amount of the electrode can be adjusted appropriately. In the above-described first and second embodiments, an example using two sets of piezoelectric element groups is shown.
It goes without saying that the present invention can be realized only by the piezoelectric element group of the set.

[0036]

As described above, according to the electrode-feeding device for electric discharge machining of the present invention, it is possible to feed out only the electrode. Also, by sending out only the electrodes, the inertial mass of the drive unit is reduced and the responsiveness of the main shaft of the processing machine is improved, and a large amount of expansion or contraction can be secured by the axial extension of the laminated piezoelectric element. The effect is that various controls are possible.

Since the electrode feed can be controlled in the resonance frequency region of the system, the responsiveness of the main shaft of the processing machine becomes very fast, and it becomes possible to give high-order vibration to the electrode. As a result, the machining powder present in the minute gaps between the electrode works is efficiently removed by the pump action, and the machining speed is dramatically improved. Further, since the electrodes can be continuously fed out when the electrodes are consumed, there is no need for frequent replacement work for electrode replacement, and the operation rate can be increased. Further, since the electrode is attached / detached by the expansion / contraction of the piezoelectric element in the axial direction, not in the radial direction, the operation amount during the attachment / detachment operation is large, and the present invention can be applied to electrode feeding of a small diameter.

[Brief description of drawings]

FIG. 1 is a sectional view showing an electrode-feeding device for electric discharge machining according to a first embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view taken along the line AA shown in FIG.

FIG. 3 is an explanatory diagram showing an electrode feeding operation and an on / off state of each piezoelectric element according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a feed amount adjusting operation of the electric-discharge machining electrode feeder according to the first embodiment of the present invention.

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

6 is an enlarged cross-sectional view taken along line BB shown in FIG.

FIG. 7 is an explanatory view showing an electrode feeding operation and an on / off state of each piezoelectric element according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a feed amount adjusting operation of the electric-discharge machining electrode feeding device according to the second embodiment of the present invention.

FIG. 9 is a view showing a shape of a recess that sandwiches an electrode.

[Explanation of symbols]

 2 Housing 4 Electrode 7 First Axial Piezoelectric Element 8 Case 12 Second Radial Piezoelectric Element 14, 15 Electrical Insulator (First Electrical Insulator) 18 Housing 20 Third Radial Piezoelectric Element 22, 23 Electrical Insulator (No. 2 electrical insulator) 27 first axial piezoelectric element 32 second radial piezoelectric element 40 third radial piezoelectric element 42, 43 feeding electrode (first feeding electrode) 41, 44 feeding electrode (second feeding electrode)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takashi Shimizu, 1-1, Showa-cho, Kariya city, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor, Hiromitsu Morita, 1-1, Showa-cho, Kariya city, Aichi prefecture Incorporated (72) Inventor Naotake Mori 2-12-1, Kukata, Tenpaku-ku, Nagoya-shi, Aichi Toyota Institute of Technology

Claims (7)

[Claims] 1. A laminated first axial piezoelectric element housed in a housing and provided so as to be capable of expanding and contracting in parallel with an axial direction of an electrode; and a fixed end of the first axial piezoelectric element fixed to the housing. On the other hand, a case that is movable in the axial direction of the electrode, a stacked second radial piezoelectric element that is housed in the case and that can expand and contract in the radial direction of the electrode, and abuts on the free end of the second radial piezoelectric element. A first electrical insulator that crimps and separates electrodes in accordance with expansion and contraction operations of the second radial piezoelectric element; and a laminated third diameter housed in the housing and expandable and contractible in the radial direction of the electrodes. A directional piezoelectric element and a second electrical insulator that abuts on a free end of the third radial piezoelectric element and crimps and separates electrodes in accordance with expansion and contraction operations of the third radial piezoelectric element. Electric discharge machining characterized by Feeder. 2. A first power supply electrode, which is electrically insulated from other parts by the first electrical insulator, and which connects a processing power source to the electrode during extension operation of the second radial piezoelectric element. The electrode feeding device for electric discharge machining according to claim 1. 3. A second power supply electrode, which is electrically insulated from other parts by the second electrical insulator, and which connects a processing power source to the electrode during extension operation of the third radial piezoelectric element. The electrode-feeding device for electric discharge machining according to claim 1 or 2. 4. The electrode-feeding device for electric discharge machining according to claim 1, wherein the electrode-feeding is controlled by a combination of a stepwise driving method and an analog-driving method. 5. The electrode-feeding device for electric discharge machining according to claim 4, wherein the electrode feeding is controlled by matching the driving frequency with a higher-order resonance frequency in a region exceeding the break point frequency of the system. 6. The electrode-feeding device for electric discharge machining according to claim 5, wherein the feed of the electrode is controlled by inverting the phase of the control signal with respect to the fluctuation of the gap voltage between the electrode and the work. 7. The first electrical insulator and the second electrical insulator have a groove portion into which an electrode is inserted, and both ends of the groove portion are widened. Electrode feed device for electric discharge machining.