Device for mounting an electrospark machining electrode

Abstract: A mounting device for an electrode to be used in an electrospark machine, said mounting device comprising: (a) an electrode holder (130) which is adapted to support an electrode blank (120) to be machined; (b) a machine holder (110) which is adapted to be detachably mounted, both to an electrode forming machine for machining said electrode blank (120) into a shaped blank having a desired shape and to an electrospark machine which is adapted to use said shaped electrode to machine a workpiece, wherein said electrode holder (130) and said machine holder (110) include inclined surfaces (112, 122) which are inclined at a substantially 45° angle with respect to an axis (P) of said machine holder (110), wherein said holders (110, 130) are adapted to engage each other along said inclined surfaces (112, 122), said inclined surfaces (112, 122) being moveable with respect to each other and thereby comprising means for changing the direction in which said electrode blank (120) extends.

Description: The present invention relates to a mounting device for an electrode to be used in an electrospark machine according to the first part of claim 1. Electrospark machines (also known as EDM or electrodischarge machines) are presently widely used, e.g., to manufacture high precision molding dies for injection molding machines; these electrospark machines are used because of their high machining efficiency. In these systems, the shape of a shaped electrode is accurately reproduced on a workpiece to be machined. Generally, a blank from which the electrode is formed is machined by a wire cut electric spark machine, a cutting machine, or other machine tool, in order to provide a shaped electrode having a desired shape. A molding die having a simple profile can be machined, e.g., by a single shaped electrode. However, a molding die having a complex profile cannot be machined by only a single, shaped electrode. Specifically, such a complex molding die can instead only be machined by a composite machining system, using a plurality of shaped electrodes. Generally speaking, the number of shaped electrodes used in a composite machining process can be reduced or decreased if shaped electrodes having three-dimensional complex profiles could be produced and used. However, in practice, an increased plurality of shaped electrodes are needed to produce shaped electrodes having complex three-dimensional profiles, thereby resulting in an apparatus which would be difficult to maintain. During the conventional machining process of a shaped electrode, six faces of a rectangular parallelepipedic electrode blank are ground in order to provide six reference surfaces which are perpendicular to each other. The electrode blanks can be attached to an electrode forming machine, e.g., a wire cut electric spark (hereinafter electrospark) machine, with the assistance of the reference surfaces on the blank. When the electrode blank is subjected to a two- or three-dimensional machining process, the reference surfaces must be changed in order to again attach the blank to the electrode forming machine. In such a conventional machining process, as noted above, it is necessary to adjust the mounting position of the electrode blank, including but not being limited to centering the blank, and/or creating parallelism or perpendicularity between the reference surface or surfaces and the surface being machined at each change of direction during the machining process. The operations needed to make such adjustments are difficult and troublesome. Accordingly, it is practically impossible to obtain a shaped electrode having a three-dimensional complex profile using conventional methods. Accordingly, during an actual machining process, the molding dies are machined by a composite machining device in which a large number of shaped electrodes having simple profiles are used. The above-noted problems also occur during a machining process using an electrospark machine having a shaped electrode attached thereto. Specifically, when the shaped electrode is transferred from the electrode forming machine to the electrospark machine, unless the positional relationship of the electrode with respect to the electrode forming machine is exactly reproduced between the electrode and the electrospark machine, precise and exact machining by the electrospark machine cannot be achieved. In conventional processes, it is extremely difficult to exactly reproduce the identical positional relationship that the electrode had with respect to the electrode forming machine when the electrode is positioned in the electrodespark machine; accordingly, the troublesome and difficult adjusting operations as noted above, e.g., the centering operation, must be effected after the electrode is transferred to the electrospark machine. Further, even after such an adjustment is made, an accurate reproduction of the positional relationship between the electrode and the electrode forming machine, on the electrospark machine, cannot be ensured. One type of shaped electrode is used in which the direction of displacement of the electrode during the course of electrospark machining of a workpiece is perpendicular to the direction of machining of the electrode blank. Using this type of shaped electrode, in conventional processes, the shaped electrode is first machined by the electrode forming machine and removed from the electrode forming machine. Thereafter, the shaped electrode is attached to the electrospark machine after the direction of the electrode is changed by 90°. It is, however, difficult to accurately set the electrode again in the electrospark machine. The failure to accurately position the electrode in the electrospark machine results in a failure to accurately reproduce the shape of the shaped electrode on a workpiece being shaped. An object of the present invention is to provide a mounting device for an electrode which can be advantageously used, particularly when the direction of machining of the electrode blank into a shaped electrode is perpendicular to the direction of electrospark machining of a workpiece using the shaped electrode obtained when the electrode blank was machined. This object is solved by a mounting device according to claim 1. Relative rotation of the machine holder with respect to the electrode holder over the inclined surfaces, by 180°, causes the position of the electrode blank which is secured to the electrode holder to be changed by 90° with respect to the machine holder. In accordance with the mounting device referred to above, only rotation of the electrode holder by 180° with respect to the machine holder will be sufficient to orient the electrode blank, (i.e., the shaped electrode) to agree with the direction of electrospark machining after the electrode blank is machined into the shaped electrode by the electrode forming machine. The inclined surfaces are rotatable with respect to each other and comprise means for changing the direction in which the electrode blank extends by 90° when they are rotated over 180° with respect to each other. The electrode holder and the machine holder are detachably connected to each other. The inclined surfaces are electrode-direction changing, rotational surfaces which are adapted to rotate about an axis inclined at an angle of substantially 45° with respect to the axis of the machine holder. The inclined surfaces have central holes, along their respective axes of rotation, into which a central pin is adapted to be inserted in order to define a common axis about which relative rotation of the holders will occur, the central pin including a central bore into which a fastening bolt is adapted to be inserted in order to secure the holders to each other. At least one of the machine holder and the electrode holder is provided with a positioning plate which is adapted to project towards the holder to which the plate is not attached, the other of the holders being provided with a pair of parallel position restricting surfaces which are adapted to engage the positioning plate when the electrode holder and the machine holder are angularly displaced, from a first position, by 180° with respect to each other. A positioning pin is positioned between the electrode holder and the machine holder which comprises means for selectively restricting angular movement between the holders. The machine holder and the electrode holder include at least one position restricting projection and at least one position restricting recess adapted to receive the projection in fitting engagement, the projection and the recess being positioned on the inclined surfaces such that they intersect an axis of the machine holder. The position restricting projection and the position restricting recess can be rectangularly shaped in cross-section, or the position restricting projection and the position restricting recess can have complementary V-shaped cross-sections. One of the holders includes a positioning plate which projects towards the other of the holders, the other of the holders including a pair of parallel position restricting surfaces which are adapted to engage the positioning plate, dependent upon the relative rotational positions of the two holders. One of the inclined surfaces includes two spaced apart bores and the other of the inclined surfaces includes a single bore, wherein the single bore is adapted to be selectively aligned with each of the spaced apart bores in predetermined positions of the holders, and wherein a fastening member is adapted to be inserted into the aligned bores. One of the holders is provided with a positioning plate which is adapted to be selectively projected towards and retracted from the other of the holders, wherein the other of the holders includes a pair of parallel position restricting surfaces which are adapted to engage the positioning plate when it is projected towards the other holder. The inclined surfaces are repositioned by rotation and thereby rotatably engage each other and are rotatably repostioned with respect to each other. The electrode holder includes a pair of electrode securing surfaces which are perpendicular to each other and which are angled at substantially 45° with respect to the inclined surface of the electrode holder; and the electrode securing surfaces of the electrode holder include a plurality of threaded holes which are adapted to threadably receive a plurality of fastening bolts. The above and other objects, features and advantages of the present invention will be more fully detailed hereinafter with respect to the attached claims and the accompanying drawings, in which like reference numerals are used to describe similar parts throughout the several views, and wherein: Figs. 1A and 1B, respectively, are front elevational views of an electrode mounting device illustrated in an electrode machining position and in an electrospark machining position in accordance with the present invention; Figs. 2A and 2B, respectively, are plan and right-side elevational views of a shaped electrode in a situation in which the direction of machining of the electrode is perpendicular to the direction of electrospark machining; Fig. 3 is a partially sectional and partially front elevational view of an electrode mounting device formed in accordance with the present invention; Fig. 4 is a top plan view taken from the direction indicated by the arrow XIII of Fig. 3; Fig. 5 is an exploded front elevational view of a mounting device for an electrospark machining electrode; Figs. 6 and 7, respectively, are angled plan views taken along the arrows XV and XVI, respectively, of Fig. 5; Fig. 8 is a partially cross-sectional, partially front-elevational, exploded view of an electrode mounting device formed in accordance with the present invention; Fig. 9 is a top plan view taken along the arrow XVIII in Fig. 8; Fig. 10 is a front elevational view of the electrode mounting device of Fig. 8 in assembled form; and Figs. 11A and 11B, respectively, are front elevational views of a holder, first in a position for machining an electrode blank, and in an electrospark machining position in which the shaped electrode produced by the electrode forming machine is used. Figs. 1A and 1B illustrate one example of the mounting of an electrode. The electrode mounting device of the invention essentially includes a machine holder 110 which will be hereinafter referenced as a machine holder, and an electrode holder 130. Machine holder 110 is common to all machine tools, such as ball end mill machines and electrospark machines, and is adapted to be detachably mounted thereto. In the illustrated embodiment, machine holder 110 is of the shaft reference type, in which the holder is inserted in the machine by inserting a detachable shaft 111 into an aperture into a machine. The holder can be replaced by a surface reference type of holder, as described above and as shown in the drawings. An electrode blank 120 (and, later, the formed electrode 121) to be machined by a shaped electrode of an electrospark machine is attached to electrode (blank) holder 130. Machine holder 110 and electrode holder 130 engage each other at rotatable, i.e., direction changing, surfaces 112 and 122, as illustrated in Figs. 1A and 1B; both of these surfaces are inclined at 45° with respect to axis P of machine holder 110. In this fashion, electrode holder 130 will rotate about an axis Q which is precisely perpendicular to inclined surfaces 112 and 122. Electrode blank 120 is thus capable of rotating to change its direction by 90° with respect to axis P, as illustrated in Fig. 1B, when holder 130 has rotated over 180°. Figs. 2A and 2B illustrate one example of forming an electrode 121 in which the direction of machining of electrode blank 120 is perpendicular to the direction of electrospark machining. Shaped electrode 121, as illustrated in Figs. 2A and 2B, thus has a planar body with an arcuate front end 132 and a bottom groove 133 which extends inwardly onto the electrode 121 from the arcuate front end 132 of the electrode. When a shaped electrode 121 is to be machined, electrode holder 130 is attached to machine holder 110 such that the plane of blank 120 will lie perpendicularly to axis P. After this attachment, a cutting tool C of a machine tool, as illustrated in Fig. 1A, e.g., a ball end mill, will move downwardly as illustrated by arrow (a) in Fig. 1A, and will also move laterally to cut a desired groove 133. It is thus also possible to cut the arcuate front end 132 of the electrode with tool C. When shaped blank 121 thus obtained is then subjected to electrospark machining by an electrospark machine, electrode holder 130 will be rotated or turned by 180° with respect to machine holder 110, as illustrated in Fig. 1B, such that shaped electrode 121 will be oriented in a direction (b) which is perpendicular to direction (a) of machining effected by tool C. Accordingly, by merely transferring insertion shaft 111 from an electrode forming machine to the electrospark machine, electrospark machining can be precisely and exactly effected. Specifically, since the distance of the axis P of machine holder 110 and the shaped electrodes 121 (i.e., electrode blanks 120) can be predetermined, only rotation of the electrode holder over 180° needs to occur at the time of the "set change" (taking the known distances into consideration) in order to adequately machine a workpiece. Figs. 3 and 4 illustrate details of a machine holder 210 and an electrode holder 220. Rotational surfaces 212 and 222 are provided with central rotational holes 213 and 223, respectively, into which a central rotational pin 221 is adapted to be inserted, such that holders 210 and 220 can rotate relative to pin 221. Central pin 221 will come into contact at its opposite ends with the bottoms of central holes 213 and 223 in order to restrict or limit the closest distance that machine holder 210 and electrode holder 220 will come to each other. The bottom of central hole 223 is provided with a threaded bore or additional hole 224 into which a fastening bolt 214 is adapted to be inserted through the machine holder side so that it will extend through a central opening 221a in center pin 221. In other words, bolt 214 is screwed into center opening 221a of center pin 221. With such a construction, machine holder 210 and electrode holder 220 can be secured to each other and come into close contact with each other via central pin 223, which also serves to space the holder 220 and holder 210 from each other. Electrode holder 220 includes a pair of positioning holes 225 and 226 which are diametrically opposed to each other with respect to central hole 223; a positioning pin 215 can be selectively inserted into these positioning holes. On the other hand, machine holder 210 includes a positioning hole 216 which is adapted to be selectively aligned with positioning holes 225 and 226 in accordance with rotational movement of the electrode holder 220. As a result, when positioning pin 215 is inserted into positioning hole 216 and one of positioning holes 225 and 226 is registered with positioning hole 216, rotation of the electrode holder 220 relative to the machine holder 210 can be prevented. The two positions in which the positioning pin 215 is inserted in holes 216 and 225 and holes 216 and 226, respectively, correspond to the electrode forming position and the electrospark machining position, respectively, of the holders. A pair of electrode securing surfaces 227 and 228, which are perpendicular to each other and which are inclined at 45° with respect to rotational surface 222, are provided on electrode holder 220. Electrode securing surfaces 227 and 228 are each provided with threaded holes 229 (see Fig. 4) for receiving set bolts in order to secure an electrode blank as desired. The shaped electrode (i.e., a shaped electrode blank) can be secured to either one of electrode securing surfaces 227 and 228, dependent upon the shape of the shaped electrode. The elements referred to above, specifically surfaces 212 and 222, holes or apertures 213, 216, 223, 225, and 226, centering pin 214, and positioning pin 215, should all be formed in a known fashion such that their surfaces will have a high surface flatness, the holes will have good surface regularity and accurate diameters, and the clearances between the holes and the pins will be relatively small. With an arrangement as referred to above, when fastening bolt 214 is disengaged from threaded aperture 224, electrode holder 220 can be detached from machine holder 210. Accordingly, by preparing a required plurality of electrode holders 220 having, e.g., electrode blanks 20 (or shaped electrodes 20) secured thereto, the number of machine holders 210 can be decreased (e.g., only one machine holder 210 will be needed) in order to achieve the object of the present invention. In particular, if a plurality of electrode holders 220 having shaped electrodes are adapted to be detachably mounted to a single machine holder 210, there will be no deviation in the centers of the atached electrodes, as there would otherwise be during composite machining using such electrodes. Further, precise machining results from the use of positioning pin 215, which restricts angular displacement of electrode holder 220. In the embodiment referred to above, rotational surfaces 212 and 222 comprise direction changing surfaces. Alternately, it is possible to provide non-rotational direction changing surfaces, as illustrated in Figs. 5-7. In Figs. 5-7, machine holder 310 includes a direction changing surface 312a which is provided with an elongated position restricting projection 317a which is located at an intersecting point of the surface with the axis P, as shown in Fig. 5. Projection 317a is in the form of a rod having a substantially rectangular cross-section. On the contrary, electrode holder 320 has a direction changing surface 322a which is provided with an elongated aperture 323a which is in the form of a rectangular groove into which projection 317a is adapted to be fitted. In this embodiment, machine holder 310 includes a bolt hole 318 substantially at the center of the length of projection 317a, which bolt hole is positioned perpendicularly with respect to the direction changing surface 312a. Electrode holder 320 includes a threaded hole 324a which is located at the center of the length of the bottom of recess 323a of electrode holder 320; and which is connected to machine holder 310. Fastening bolt 314a is inserted into bolt hole 318 and is threadably screw-engaged in threaded hole 324a of electrode holder 320 in order to secure holders 310 and 320 to each other. A positioning plate 340 is secured to a side face of machine holder 310; this positioning plate projects towards electrode holder 320. Electrode holder 320 includes a pair of parallel position restricting surfaces 341 which are spaced from threaded hole 324a by the same distance, and which are perpendicular with respect to recess 323a. Position restricting surfaces 341 are positioned so as to engage positioning plate 340; and the mounting device referred to above is adapted to separate machine holder 310 from electrode holder 320 when fastening bolt 314a is disengaged. Electrode holder 320 includes electrode securement surfaces 327 and 328, as shown in Figure 7. After the holders are separated from each other, they are relatively rotated or turned by 180°, and projection 317a of machine holder 310 is fitted within recess 323a of electrode holder 320, such that one of position restricting surfaces 341 will come into contact with positioning plate 340. Finally, fastening bolt 314a will be inserted into hole or bore 318 and screwed into threaded hole 324a, again in order to secure electrode holder 320 to machine holder 310, such that the position of an electrode blank (e.g.,120) secured to electrode holder 320 will be reversed, namely rotated over 180°. In the mounting device illustrated in Figs. 5-7, machine holder 310 and electrode holder 320 can be easily and inexpensively manufactured. It should be noted that projection 317a and corresponding recess 323a can be provided with a V-shaped configuration in cross-section, as illustrated by the immaginary lines in Fig. 5, rather than a substantially rectangular cross-section. It should therefore be appreciated that the cross-sectional configurations of projection 317a and the recess 323a need not be limited to a rectangular or V-shape, as noted above, but could be formed from other shapes. The projection and the recess can be formed of any complementary configurations which are symmetrical to each other and with respect to central axis of rotation Q. The position restricting mechanism in which a positioning plate 340 is provided on a machine holder 310, as illustrated in Fig. 5, can also be applied to the first embodiment referred to above if desired. Figs. 8-11 illustrate another embodiment of a mounting device having a positioning plate 440a. Positioning plate 440a is provided on machine holder 410 such that the inner face of positioning plate 440a will engage a pair of positional restricting surfaces 441a provided along the side faces of electrode holder 420. Positioning plate 440a is movable so that it can engage and disengage position restricting surfaces 441a. Specifically, positioning plate 440a includes an elongated bore or hole 442 which extends along the direction of axis P. A fastening screw 443 is inserted into elongated bore 442 and is screwed into threaded hole 444 which is formed in machine holder 410. Accordingly, positioning plate 440a can move over a distance defined by elongated hole 442; the length of the elongated hole extends in the direction of axis P, such that inclined portion 446 of plate 440a, which is parallel to rotational surface 412 of the front end of machine holder 410, will project from rotational surface 412 towards electrode holder 420. Normally, inclined portion 446 is then retracted into rotational surface 412. A pair of position restricting surfaces 441a of electrode holder 420 are parallel to each other and are spaced from axis of rotation Q and from axis P by the same distance, in a similar fashion to the above-noted embodiments. The other portions of the embodiment noted in Figs. 8-11 are essentially identical to those of the first embodiment. The elements illustrated in Figs. 8-11 which correspond to those of the first embodiment have been designated with the same numerals (with the prefix 400) as those of the first embodiment. For example, electrode securing surfaces 427 and 428, electrode bore 424, shaft 411, electrode holder surface 422 and aperture 423, bolt 414, center pin 421, center pin opening 421a, rotational hole 413, and threaded holes 429, are all substantially equivalent to previously described elements having the same last two digits. With the arrangement illustrated in Figs. 8-11, when electrode holder 420 is rotated or turned by 180°, positioning plate 440a slides towards electrode holder 420, so that front inclined portion 446 of positioning plate 440a will come into contact with one of the position restricting surfaces 441a along the inner faces of the inclined portion 446. This prevents relative rotation of electrode holder 420 and machine holder 410. The two restricting positions, in which inclined portion 446 of positioning plate 440a comes into contact with restricting surfaces 441a, correspond to the electrode machining position and the electrospark machining position, respectively. Fig. 11A and 11B illustrate two different positions of an electrode blank 430 (and shaped electrode 431) and substantially correspond to the positions of Figs. 1A and 1B, respectively. In the embodiment illustrated in Figs. 8-11, it is not easy to separate machine holder 410 from electrode holder 420, as compared to the ease of separation which result from use with the previously noted embodiments; and, accordingly, the holders can be treated and handled together, as a unit, thereby resulting in an increased capacity of preventing the holders from becoming lost. Positioning plate 440a, which is slidable in the illustrated embodiment, can be replaced by a plate which rotates about an axis in order to selectively project and retract a projection from rotating surface 412 of electrode holder 420. Although positioning plates 440 and 440a are provided on machine holder 410 in the illustrated embodiments, they can also be supported on electrode holder 420. In such a case, position restricting surfaces will be provided along machine holder 410. Although the present invention has been described with respect to a variety of specific embodiments thereof, it should be clear that it is not limited to the specific embodiments listed herein, and that it equally applies to all embodiments covered by the claims.

Claims: A mounting device for an electrode to be used in an electrospark machine, said mounting device comprising: an electrode holder (130) which is adapted to support an electrode blank (120) to be machined; a machine holder (110) which is adapted to be detachably mounted, both to an electrode forming machine for machining said electrode blank (120) into a shaped electrode having a desired shape and to an electrospark machine which is adapted to use said shaped electrode to machine a workpiece, characterized in that said electrode holder (130) and said machine holder (110) include inclined surfaces (112, 122) which are inclined at a substantially 45° angle with respect to an axis (P) of said machine holder (110), and that said holders (110, 130) are adapted to engage each other along said inclined surfaces (112, 122), said inclined surfaces (112, 122) being moveable with respect to each other for changing the direction in which said electrode blank (120) extends. A mounting device in accordance with claim 1, wherein said inclined surfaces (112, 122) are rotatable with respect to each other and comprise means for changing said direction in which said electrode blank (120) extends by 90° when they are rotated over 180° with respect to each other. A mounting device in accordance with claim 1 or 2, wherein said electrode holder (130) and said machine holder (110) are detachably connected to each other. A mounting device in accordance with one of claims 1 to 3, wherein said inclined surfaces (112, 122) comprise electrode-direction changing, rotational surfaces which are adapted to rotate about an axis (Q) inclined at an angle of substantially 45° with respect to the axis (P) of said machine holder (110). A mounting device in accordance with one of claims 1 to 4, wherein said inclined surfaces (212, 222) have central holes (213, 223) along their respective axes of rotation, into which a central pin (221) is adapted to be inserted in order to define a common axis about which relative rotation of said holders (210, 220) will occur , said central pin (221) including a central bore (221a) into which a fastening bolt (214) is adapted to be inserted in order to secure said holders (210, 220) to each other. A mounting device in accordance with one of claims 1 to 5, wherein at least one of said machine holder (410) and said electrode holder (420) is provided with a positioning plate (440) which is adapted to project towards the holder (420) to which said plate (440) is not attached, the other of said holders (420) being provided with a pair of parallel position restricting surfaces (441a) which are adapted to engage said positioning plate (440) when said electrode holder (420) and said machine holder (410) are angularly displaced, from a first position by 180° with respect to each other. A mounting device in accordance with one of claims 1 to 6, further comprising a positioning pin (215) positioned between said electrode holder (220) and said machine holder (210), which pin (215) comprises means for selectively restricting angular movement between said holders (210, 220). A mounting device in accordance with one of claims 1 to 7, wherein said machine holder (310) and said electrode holder (320) include at least one position restricting projection (317a) and at least one position restricting recess (323a) adapted to receive said projection (317a) in fitting engagement, said projection (317a) and said recess (323a) being positioned on said inclined surfaces (312a, 322a) such that they intersect an axis of said machine holder (310). A mounting device in accordance with claim 8, wherein said position restricting projection (317a) and said position restricting recess (323a) are rectangularly shaped in cross-section. A mounting device in accordance with claim 8, wherein said position restricting projection and said position restricting recess (323a) have complementary V-shaped cross-sections. A mounting device in accordance with one of claims 8 to 10, wherein one of said holders (410, 420) includes a positioning plate (440a) which projects towards the other of said holders (420, 410), the other of said holders (420, 410) including a pair of parallel position restricting surfaces (441a) which are adapted to engage said positioning plate (440a), dependent upon the relative rotational positions of said two holders (410, 420). A mounting device in accordance with one of claims 1 to 11, wherein one of said inclined surfaces (222) includes two spaced apart bores (225, 226) and the other of said inclined surfaces (212) includes a single bore (216), wherein said single bore (216) is adapted to be selectively aligned with each of said spaced apart bores (225, 226) in predetermined positions of said holders (210, 220), and wherein a fastening member (215) is adapted to be inserted into said aligned bores. A mounting device in accordance with one of claims 1 to 12, wherein one of said holders (410) is provided with a positioning plate (440a) which is adapted to be selectively projected towards and retracted from the other of said holders (420), wherein the other of said holders (420) includes a pair of parallel position restricting surfaces (441a) which are adapted to engage said positioning plate (440a) when it is projected towards said other holder (420). A mounting device in accordance with one of claims 1 to 13, wherein said electrode holder (220) includes a pair of electrode securing surfaces (227, 228) which are perpendicular to each other and which are angled at substantially 45° with respect to the inclined surface (222) of said electrode holder (220). A mounting device in accordance with claim 14, wherein said electrode securing surfaces (227, 228) of said electrode holder (220) include a plurality of threaded holes (229) which are adapted to threadably receive a plurality of fastening bolts.

Inventors: KANEDA TOSHIO C O ASAHI KOGAKU, KIMURA HISAO C O ASAHI KOGAKU, UKAJI SHIROH C O ASAHI KOGAKU, URATA KENJI C O ASAHI KOGAKU K, KANEDA,TOSHIO,C/O ASAHI KOGAKU KOGYO K.K., KIMURA,HISAO,C/O ASAHI KOGAKU KOGYO K.K., UKAJI,SHIROH,C/O ASAHI KOGAKU KOGYO K.K., URATA,KENJI,C/O ASAHI KOGAKU KOGYO K.K.
Applicants: ASAHI OPTICAL CO LTD, ASAHI KOGAKU KOGYO KABUSHIKI KAISHA
Application year: 1987
Main classification: B23H7
IPC codes: B23H7, B23H1