Current pickup indexing apparatus

An improved apparatus for placing current on a moving wire electrode traveling between two points and over a conductive member in the form of a rod. The rod is at an acute angle with respect to the normal straight line of wire travel and its circular outer surface is in contact with the moving wire. The improved apparatus provides a mechanism whereby the conductive member is turned about its longitudinal axis thereby exposing a plurality of different contact surfaces to the wire. An index mechanism is provided for stopping the conductive member at a plurality of positions. An indicator mechanism is also provided for indicating to an operator which contact surface is currently being used. The conductive member is loaded onto the support body from the working end.

 

What is claimed is:

1. In an apparatus for transferring electrical current to and from a moving electrically conductive wire travelling between two points, the apparatus including an electrically conductive member having a longitudinal axis, the member having a circular outer surface with respect to the longitudinal axis and located with the longitudinal axis at an angle from a straight line defined by the two points and with the circular outer surface in contact with the moving wire, the wire contacting the circular outer contact surface along a curvilinear path, the improvement comprising: means for turning the electrically conductive member about its longitudinal axis for exposing a plurality of contact surfaces on the member outer surface to the wire.

2. The apparatus of claim 1 wherein said turning means comprises gear teeth on the member meshing with a driving gear, said driving gear adapted for selective turning thereof.

3. The apparatus of claim 2 further comprising index means for selectively stopping the electrically conductive member at each of said plurality of positions for exposing said plurality of contact surfaces.

4. The apparatus of claim 2 wherein the electrically conductive member is continuously turned about its longitudinal axis while the wire is caused to slide over the electrically conductive member outer surface.

5. The apparatus of claim 2 wherein said driving gear is a ring gear on a flush cup, said flush cup having an orifice wherethrough the wire and a fluid are caused to pass.

6. The apparatus of claim 5 wherein said flush cup is detachably attached in a position for said meshing between said member gear teeth and said ring gear.

7. The apparatus of claim 5 further comprising index means for selectively stopping the electrically conductive member at each of said plurality of positions for exposing said plurality of contact surfaces.

8. The apparatus of claim 2 wherein said driving gear is a ring gear on an annular member, said annular member having a longitudinal axis and adapted to be rotated thereabout.

9. The apparatus of claim 8 wherein said annular member is detachably attached in a position for said meshing between said member gear teeth and said ring gear.

10. The apparatus of claim 8 further comprising index means for selectively stopping the electrically conductive member at each of said plurality of positions for exposing said plurality of contact surfaces.

11. The apparatus of claim 8 further comprising a flush cup detachably attached to said annular member, said flush cup having an orifice wherethrough the wire and a fluid are caused to pass.

12. The apparatus of claim 2 wherein said driving gear is a bevel gear adapted for turning about an axis of rotation, said bevel gear axis of rotation being at an acute angle from the conductive member longitudinal axis.

13. The apparatus of claim 12 wherein said bevel gear is on an end of a shaft, said shaft having a central longitudinal axis being colinear with said bevel gear axis of rotation and wherein said shaft is adapted for selective rotation about said axis of rotation.

14. The apparatus of claim 13 further comprising means for selectively stopping the electrically conductive member at a plurality of positions for providing said plurality of contact surfaces.

15. The apparatus of claim 12 further comprising a second bevel gear meshing with said first bevel gear, said second bevel gear adapted for selective rotation.

16. The apparatus of claim 15 further comprising index means for selectively stopping the electrically conductive member at each of said plurality of positions for exposing said plurality of contact surfaces.

17. The apparatus of claim 2 wherein said driving gear is a worm gear adapted for turning about an axis of rotation, said worm gear having a longitudinal axis situated generally perpendicular to said conductive member longitudinal axis.

18. The apparatus of claim 17 wherein said worm gear is on an end of a shaft, said shaft having a central longitudinal axis and wherein said shaft is adapted for selective rotation about said central longitudinal axis of rotation.

19. The apparatus of claim 18 further comprising index means for selectively stopping the electrically conductive member at each of said plurality of positions for exposing said plurality of contact surfaces.

20. The apparatus of claim 1 wherein said turning means comprises gear teeth on the member and toggle means for selectively contacting at least one of said member gear teeth, partially turning said conductive member about its longitudinal axis and retracting in a position for selectively repeating said contacting and partial turning.

21. The apparatus of claim 20 wherein when said toggle means is in said retracted position, rotation of said conductive member is prevented.

22. The apparatus of claim 1 further comprising tool receiving means on said conductive member for cooperating with a tool adapted for rotation, whereby rotation of the tool causes said conductive member to turn about its longitudinal axis.

23. The apparatus of claim 22 further comprising index means for selectively stopping the electrically conductive member at each of said plurality of positions for exposing said plurality of contact surfaces.

24. The apparatus of claim 22 wherein said tool receiving means includes a hexagonal-shaped recess at a longitudinal end of said conductive member, said hexagonal recess adapted for receiving a hexagonal ball tool end.

25. The apparatus of claim 1 further comprising index means for selectively stopping the electrically conductive member at each of said plurality of positions for exposing said plurality of contact surfaces.

26. The apparatus of claim 25 further comprising indicator means cooperating with said turning means for displaying one of a plurality of indications, each of said indications corresponding to a conductive member contact surface.

27. The apparatus of claim 1 wherein the electrically conductive member is continuously turned about its longitudinal axis while the wire is caused to slide over the electrically conductive member outer surface.

28. The apparatus of claim 1 further comprising indicator means cooperating with said turning means for displaying one of a plurality of indications, each of said indications corresponding to a conductive member contact surface.

29. The apparatus of claim 1 wherein said turning means includes toggle means for causing the turning of the electrically conductive member about its longitudinal axis by a pushing force which is generally parallel to the longitudinal axis of said conductive member.

30. An apparatus for transferring electrical current to and from a moving electrically conductive wire, said apparatus comprising:

an electrically conductive member in sliding contact with the wire and transferring electrical current to and from the wire;

means for supporting said electrically-conductive member;

said support means having a working end for facing towards a workpiece; and,

wherein the electrically-conductive member is selectively placed on and removed from said support means through said working end of said support means.

31. The apparatus of claim 30 wherein said support means includes a support body having a bore therethrough, a hole on said working end communicating with said bore, and wherein the electrically conductive member is selectively inserted in and removed from said bore through said hole.

32. The apparatus of claim 31 further comprising means for selectively retaining said member in said bore.

33. The apparatus of claim 32 wherein said retaining means includes a snap ring received through said hole and selectively affixed in said bore.

34. The apparatus of claim 30 wherein said support means includes a support body having a bore therethrough for receiving said conductive member therein, said support body being detachably attached to said support means and wherein access to said bore for selectively inserting and removing said conductive member therefrom is provided by detaching said support body from said support means.

TECHNICAL FIELD

The present invention relates to an improvement to an apparatus for conveying electrical current between an electric current member and an electrically conductive wire or cable which moves relative to the current transfer member. More specifically, the present invention relates to an improved apparatus for turning the electric current transfer member about its longitudinal axis for exposing a plurality of contact surfaces on the member outer surface to the moving wire. The present invention has a wide range of potential applications including electrical discharge machines and welders.

BACKGROUND OF THE INVENTION

The placing of electrical current on a moving wire is currently required and is being done in at least the electrical discharge machine (EDM) industries and welding industries. This is currently normally accomplished by providing various shaped current pickups which are electrically charged. The moving wire slides or rubs against the electrically charged surface of the current pickup thus transferring electrical current therethrough to and from the moving wire. One common pickup is generally cylindrically shaped with a bore therethrough. The wire is received through the pickup bore and, because the current pickup bore is offset from the straight line of wire travel, the moving wire electrode rubs against the interior surface of the bore making the necessary electrical contact for transferring current to the moving wire. Other current pickup devices are made with various shaped contact surfaces and are pushed toward the taut moving wire electrode or placed in the normal straight line of wire travel causing the wire to rub against the current pickup contact surface thereby making the necessary electrical contact. Current pickups such as those described hereinabove are, for example, disclosed in U.S. Pat. No. 4,896,013 and U.S. Pat. No. 4,539,459.

However, the current pickups which are presently known and used have substantial shortcomings and drawbacks. Like all current pickups, as the moving wire slides against the pickup contact surface, the current pickup tends to wear and the wire causes a groove to be formed in the pickup through the original contact surface. Once the groove becomes sufficiently large in depth, the wire tends to bind therein causing wire breakage and requiring the stopping of, for example, the EDM operation and re-threading of the wire. As the groove is formed, the wire also tends to get closer to the normal straight line of wire travel (straighter) and even though the wire remains taut, there is insufficient contact between the wire and the new contact surface at the bottom of the groove for efficient current transfer. In view of this, after a particular contact surface has worn by a predetermined amount, the current pickup position is changed so as to provide a new contact surface or the entire current pickup itself is replaced.

Prior current pickups, however, provide relatively few contact surface positions whereat a new contact surface can be exposed to the moving wire. Typically, the cylinder-shaped pickups have a bore diameter only slightly larger than the wire diameter and, therefore, the maximum number of contact surfaces is four. Each of the contact surfaces for these current pickups are located on the current pickup bore surface at 90 degrees from each other with respect to the bore longitudinal axis. After these four contact surfaces have been exposed and worn, the current pickup is no longer useful and is replaced. Exposing the four different contact surfaces of the cylinder-type pickups, however, normally requires the disassembly of the various guide arm assembly components so as to gain access to the current pickup located therein and so that a tool or other means can be used for turning the current pickup about its longitudinal axis and exposing the new contact surface. An example of this is disclosed in U.S. Pat. No. 5,089,680. As can be appreciated, although this is generally acceptable, the disassembly of the entire guide arm to gain access to the current pickup can be cumbersome, time-consuming and, thus, costly. In addition, although other devices such as those disclosed in U.S. Pat. No. 4,994,643 have been devised for tilting and/or turning the cylindrical-type current pickup without disassembly of the entire guide arm, such devices of the past are somewhat complex and costly. Furthermore, even with such devices, the replacement of the current pickup, once all bore contact surfaces have been diminished still requires complete disassembly of the guide arm for gaining access to the current pickup and replacing the same. Again, this is somewhat cumbersome, time-consuming and costly.

Accordingly, a need exists for a current pickup apparatus that conveys electrical current to and from a moving wire and which overcomes the above-discussed disadvantages associated with prior current pickup assemblies and which further provides a substantial number of different contact surfaces on the pickup and which allows easy removing and replacing the pickup without disassembly of the guide arm assembly housing the pickup. In addition, a need exists for such apparatus which is both reliable and generally inexpensive to manufacture, assemble and operate.

SUMMARY OF THE INVENTION

It is the principal object of the present invention to overcome the above-discussed disadvantages associated with prior current pickups.

The present invention overcomes the above-mentioned and other disadvantages associated with prior current pickups by providing an apparatus which improves applicant's current pickup disclosed in applicant's parent U.S. application filed on Dec. 23, 1992, Ser. No. 995,887. In that parent application, there was provided a rod-shaped or cylindrical pickup at an acute angle with respect to the axis of the wire defined by two points. This axis or normal straight line of travel of the wire is offset so as to intersect the outer surface of the rod and cause the wire to rub thereagainst in a helical or elliptic contact pattern. Accordingly, although the rod diameter is circular and generally small, the contact surface appears elliptical to the wire along its contact length.

More specifically, the electrically conductive rod has a circular outer surface with respect to its longitudinal axis and is received within a bore of a rod support or holder body. The rod holder body includes a wire-receiving hole therethrough at an acute angle from the rod and bore longitudinal axes. The wire-receiving hole surface and the bore surface intersect and thereby define a generally straight elongate passage therebetween. The electrically-conductive wire to which electrical current is transferred is received through the wire hole and is guided therethrough with two guide members which are preferably the orifice-type, one on each side of the wire hole. The passage between the wire hole and the bore is generally parallel to a straight line defined between the guide member bores. This straight line also intersects the electrically-conductive rod circular outer surface so that when wire traveling through the two guide bores is made taut, the wire contacts the rod circular outer contact surface along a curvilinear path or, more specifically, along a path defined by a segment of an ellipse.

So as to provide a plurality of contact surfaces, according to the present invention, as one curvilinear path contact surface of the conductive member or rod is worn, another similar curvilinear contact surface is provided by turning the rod about its longitudinal axis to expose a new unworn portion of the rod outer surface. The total theoretical available different contact surfaces is equal to the circumference of the rod diameter divided by the diameter of the wire being used. For example, a 0.375 inch diameter rod used in conjunction with a 0.002 diameter wire can provided a total of 589 different contact surfaces. However, to prevent the wire from falling back into a previously created groove and, further, because the wire tends to vibrate and cause a groove somewhat larger than its own diameter, the actual number of contact surfaces is less than theoretical.

Various different assemblies are provided for turning the conductive member rod about its longitudinal axis. One assembly includes a tool receiving opening on one longitudinal end of the rod and adapted for cooperating with a tool which is rotated and which causes the conductive member to turn about its longitudinal axis.

Another assembly for turning the conductive member rod about its axis includes gear teeth around the circumferential surface of the conductive member at one longitudinal end. A driving gear is provided meshing with the conductive member rod gear teeth and is selectively turned for causing the conductive member to turn about its longitudinal axis. In a preferred assembly, the ring gear is on an annular member having a longitudinal axis and surrounding the conductive member rod. The annular member is adapted for rotational movement, thus causing the conductive member to be turned about its axis. An index pin mechanism is provided on the annular member for selectively stopping the annular member at each of the plurality of positions and thus providing a plurality of contact surfaces corresponding to each stopping position. The annular member is provided with indications such as numerals corresponding to a stopping position and a contact surface, so that the operator can know which contact surface is currently being used and the number of contact surfaces remaining unworn.

In another embodiment, the ring gear is on a flush cup which is detachably attached to the guide arm assembly. The flush cup is adapted for rotational movement and, thus, causing the turning of the conductive member.

In another embodiment, the driving gear is a bevel gear located on the end of a shaft which is itself adapted for rotational movement about the shaft longitudinal axis. In a similar embodiment, a driving bevel gear is provided and adapted for rotation about an axis which is at an acute angle from the conductive member longitudinal axis. A second bevel gear is adapted for meshing with the first driving bevel gear and, thus, the turning of the second bevel gear causes selective turning of the conductive member rod.

In another embodiment, the driving gear is a worm gear on the end of a shaft which is itself adapted for rotation about the shaft axis thereby causing the conductive member rod to selectively turn about its longitudinal axis.

In all of the foregoing embodiments, there are provided devices for both indexing to discrete positions corresponding to contact surfaces on the conductive member and, also, indicating devices for telling the operator which of the plurality of contact surfaces is currently being used.

In yet another embodiment, there is provided a toggle mechanism for selectively contacting the member gear teeth and partially turning the conductive member about its longitudinal axis and, thereafter, retracting in a position for selectively repeating the contacting and partial turning. When in the retracted position, the toggle mechanism cooperates with the member gear teeth for preventing rotational movement of the conductive member. As with the preferred embodiment here, each toggle provides a new contact surface on the conductive member and indications are provided for indicating to the operator which of the plurality of contact surfaces is presently being used.

The conductive member rod is retained in a bore of a holding or supporting body. The conductive member is loaded into its holding bore by detaching the flush cup and removing and replacing the conductive member from the working end of the support arm assembly and holding body. In one embodiment, the removal of the flush cup exposes the conductive member bore in the supporting body and by removing a retaining clip, the conductive member can be removed and replaced. In another embodiment, the support body is detached from the support arm thus exposing one end of the conductive member holding bore and allowing the replacement of the conductive member.

In one form thereof, the present invention is directed to an apparatus for transferring electrical current to and from a moving electrically conductive wire travelling between two points. The apparatus includes an electrically conductive member having a longitudinal axis. The conductive member has a circular outer surface with respect to the longitudinal axis and is located with the longitudinal axis at an angle from a straight line defined by two points and with the circular outer surface in contact with the moving wire. The wire contacts the circular outer surface along a curvilinear path. The apparatus is improved by providing a mechanism for turning the electrically-conductive member about its longitudinal axis for exposing a plurality of contact surfaces on the member outer surface to the wire.

In one form thereof, the present invention is directed to an apparatus for transferring electrical current to and from a moving electrically conductive wire. The apparatus includes an electrically conductive member in sliding contact with the wire. A mechanism is provided for supporting the electrically-conductive member. The supporting mechanism has a working end for facing towards a work piece. The electrically-conductive member is selectively placed on and removed from the support mechanism through the working end of the support mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and objects of this invention and the manner of obtaining them will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings wherein:

FIG. 1 is a cross-sectional view of an electrical discharge machine support arm assembly and guides for guiding the wire and incorporating an improved apparatus according to the present invention;

FIG. 2 is a cross-sectional view of the apparatus shown in FIG. 1 taken along line 2--2;

FIG. 3 is a cross-sectional view of the apparatus shown in FIG. 1 taken along line 3--3;

FIG. 4 is a cross-sectional view of the apparatus shown in FIG. 1 taken along line 4--4;

FIG. 5 is a partial cross-sectional view showing another improved apparatus according to the present invention;

FIG. 6 is a partial cross-sectional view of another improved apparatus according to the present invention;

FIG. 7 is a partial cross-sectional view of another improved apparatus according to the present invention;

FIG. 8 is a partial cross-sectional view of another improved apparatus according to the present invention;

FIG. 9 is a partial cross-sectional view of another improved apparatus according to the present invention;

FIG. 10 is a partial cross-sectional view of another improved apparatus according to the present invention;

FIG. 11 is a partial view taken along line 11--11 of FIG. 10 and showing part of the toggle mechanism;

FIG. 12 is a partial cross-sectional view showing yet another improved apparatus according to the present invention; and,

FIG. 13 is a blown-up diagrammatic view of a toggle mechanism incorporated in the improved apparatus of FIG. 12; and,

FIG. 14 is partial diagrammatic view of the mechanism shown in FIG. 13.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

The exemplifications set out herein illustrated preferred embodiments of the invention in one form thereof and such exemplifications are not to be construed as limiting the scope of the disclosure or the scope of the invention in any manner.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring initially to FIG. 1, the general operation of an electrical discharge machine is diagrammatically shown. The discharge machine includes a supply spool of wire 10 providing wire 12 through an upper support assembly and guiding arm 14, a workpiece 16, a lower support assembly and guiding arm 18 and, finally, unloading the wire 12 into container 20. Each of the support guiding assemblies 14 and 18 have a working end designated by the numeral 22 for facing in the direction of workpiece 16 when workpiece 16 is being cut.

Assemblies 14 and 18 each include a support arm 24 selectively movable in a known and customary manner for moving the support and guiding assemblies 14 and 20 during the cutting operations. The support and guiding assemblies include a barrel 26 having an inner tapered surface 28 and an upper left-handed threaded bore 30. A T-member 32 having an elongate portion 34 and a disk portion 36 is provided at the upper end of barrel 26. T-member 32 includes a bore 38 wherethrough wire 12 is received. An orifice-type guide member 40 made of diamond or other suitable material is provided and is mounted via sintered metal 42 or by other suitable means within bore 38. The elongate portion 34 of T-member 32 has left-handed threads 44 adapted for threadingly engaging and being received within left-handed threaded bore 30 and securing T-member 32 as shown. The circumferential side of disc portion 36 of T-member 32 is threaded with right-handed threads 46.

A support or holder body 48 is provided for partially being received within tapered bore 28 and includes a threaded bore 50 adapted for engaging right-handed threads 46 of disc portion 36. Thus, support body 48 can be drawn up into tapered bore 28 and tightly secured in position as shown. Support body 48 includes a wire hole 52 wherethrough wire 12 is caused to travel and come in contact with a contact surface 53 over conductive member or rod 54 received within conductive member bore 56. As shown in FIG. 1, conductive member bore 56 and, thus, conductive member 54 have colinear longitudinal axes which are at an acute angle with respect to the normal straight line of wire travel as diagrammatically depicted by wire 12 in FIG. 1. At the end of wire hole 52 closest to workpiece 16, there is provided a guiding member 58 being of the orifice type and being made of diamond or other suitable material. The guiding member 58 is mounted within wire hole 52 with a sintered metal nib 60 or other suitable material in a known and customary manner. Thus, the normal straight line of wire travel is better defined by a line directly between the orifice openings of guide members 40 and 58.

It is noted that the outer surface of support body 48 is adapted for contacting engagement of tapered bore 28. In addition, a plurality of grooves 62 are provided circumferentially around support body 48 and communicating with fluid intake opening 64. A dielectric fluid is, thus, provided under pressure through intake opening 64 as indicated by arrows A through grooves 62 and ring gear 66 into flush cup 68 and out through the flush cup central opening 70 toward workpiece 16.

As shown in FIG. 1, conductive member 54, at its lower end thereof towards the workpiece, includes a plurality of gear teeth 72. Gear teeth 72 are provided circumferentially around the outer surface at the longitudinal lower end of conductive member 54 and, further, are provided at a slight tapered angle with respect to the conductive member longitudinal axis. Teeth 72 terminate at an annular flat 74 which is adapted to engage an annular edge 76 formed at the lower end toward workpiece 16 of bore 56. Thus, conductive member 54 can only be loaded within support body 48 through the upper end 78 of bore 56. At the lower end of member 54, gear teeth 72 are exposed outside of support body 48 and mesh with the teeth of ring gear 66. At the upper end 78 of bore 56, conductive member 54 is provided with a conical indentation 80 supporting a ball bearing 82. An annular disc 84 is provided thereover along with a ring spring 86. Both annular disc 84 and ring spring 86 are received within threaded bore 46 and are sandwiched between T-member 32 and support body 48 in a manner whereby a constant biasing force is provided onto ball bearing 82. This force is transferred downwardly keeping conductive member 54 in position and with annular flat 74 against edge 76. As can be appreciated, the biasing force and the various frictional forces by the assembly are taken into consideration for manufacturing and assembly so as to allow the turning of conductive member 54 about its longitudinal axis with relative ease.

It is now noted that the conductive member 54 can be replaced from the working end 22 by removing the flush cup 68 as more fully discussed hereinbelow, unscrewing support member 48 from T-member 32, removing the support member 48 from within tapered bore 28 and then pulling the conductive member 54 out of bore 56 and replacing with a new conductive member and then again reinserting and attaching the support member 48 in the position as shown. As can be appreciated, this eliminates the need for disassembly of the entire support assemblies 14, 18 for replacing the guide member as was required by the prior art.

So as to maximize performance and provide a maximum number of conductive contact surfaces for wire 12, conductive member 54 is selectively turned about its longitudinal axis for exposing new contact surfaces along the exterior surface 53 of conductive member 54. More specifically, ring gear 66, in the embodiment shown in FIG. 1, acts as the driving gear meshing with gear teeth 72 in a manner whereby the rotational movement of ring gear 66 causes the turning of conductive member 54. In this regard, ring gear 66 is attached to annular ring member 88 which is rotatably affixed to the lower end of barrel 26. O-ring 90 is provided in the annular groove 92 and between annular ring 88 and barrel 26 to provide a hermetic seal thereat. An annular race 94 is provided on the outer surface of barrel 26 for partially receiving ball bearings 96. Thus, annular ring 88 is fixed with respect to the longitudinal but can be selectively rotated thereabout around barrel 26.

Ball bearings 96 are retained in place via L-shaped ring 98 which circumscribes and is affixed to annular ring 88 via set screws 100. Accordingly, to remove annular ring member 88, set screws 100 are loosened thereby removing L-shaped ring 98 and releasing ball bearings 96 out of annular race 94 and allowing annular ring member 88 to be pulled away from barrel 26. However, when L-shaped ring 98 is in place as shown in FIG. 1, the operator need only grasp the L-shaped ring 98 and turn the same about the longitudinal axis causing ring gear 66 to turn conductive member 54 and, thereby, place the conductive member 54 in another one of the plurality of positions and selectively exposing another unworn contact surface.

In view of the large number of contact surfaces along the outer surface of conductive member 54, there is provided an index mechanism whereby conductive member 54 can be selectively stopped at a plurality of discreet positions and, thus, providing the plurality of different contact surfaces. The index mechanism shown in FIG. 1 includes a detent pin 102 being biased toward L-shaped ring member 98 via spring 104 received within bore 106. Detent pin 102 is selectively received within the detents 108 along the outer circumferential surface of L-shaped ring 98. The force of spring 104, the shape of detent pin 102 and the shape of the L-shaped ring portions 110 inbetween detents 108 are made such that the operator must place a greater force for the detent pin to travel over portions 110 and into the next detent 108. In addition, the number of detents placed on the L-shaped ring 98 is mathematically calculated and set so that each of the plurality of detents 108 corresponds with a specific curvilinear contact surface on the outer surface of conductive member 54. In this fashion, the operator is also assured that rotation of L-shaped ring 98 into the next succeeding detent or notch will cause a new unworn contact surface to be exposed to wire 12.

A plurality of indicators, such as numerals 109, are also provided on the L-shaped ring corresponding to each of the plurality of detents 108 for displaying to the operator and providing an indication as to which of the plurality of contact surfaces is currently being used. An arrow 112 diagrammatically shown in FIG. 3, can also be printed on, for example, barrel 26 to provide a reference point to the operator. In this fashion, the operator will also know how many of the plurality of contact surfaces have already been used and will know when to get ready to replace the conductive member 54 due to a completely worn outer surface 53.

It is also noted that it is contemplated for L-shaped ring 98 and/or other driving mechanisms, as will be described hereinbelow, to be used in a continually driving fashion while wire 12 is caused to travel over conductive member 94 and, in a manner whereby the entire outer surface of conductive member 54 is caused to wear evenly and not at discreet locations.

Advantageously, the preferred embodiment of FIG. 1 further includes a detachably attachable flush cup 68. Flush cup 68 includes a cylindrical wall 114 provided with tangential bores 116 whereat there are received ball bearings 118. Ball bearings 118 extend radially inwardly and engage annular edge 120 of annular ring 88 for retaining flush cup 68 mounted thereon. In addition, ball bearings 118 allow flush cup 68 to freely slide longitudinally in a manner whereby the pressure of the fluid therein will push the flush cup 68 toward workpiece 16 and cause the flush cup lowermost surface 122 to be forced against workpiece 16.

For detaching flush cup 68 from assembly 14, a cylindrical member 124 is provided circumscribing cylindrical wall 114 of flush cup 68. Cylindrical member 124 is provided with an annular groove 126. A spring 128 is also provided inbetween wall 114 and member 124 urging member 124 in the position as shown in FIG. 1 for retaining ball bearings 118 in tangential bore 116. For removing the flush cup 68, the operator need only grasp cylindrical member 124 moving the same longitudinally away from assembly 114 and causing annular groove 126 to be aligned with tangential bore 116 and thereby allowing ball bearings 118 to be moved radially outwardly and within annular groove 126. Accordingly, annular edge 120 can now be avoided and flush cup 68 can be detached from annular ring 88. It is noted that replacement of flush cup 68 merely requires the reverse operation for allowing ball bearings to slip over edge 120 and thereafter be forced against the outer surface of annular ring 88 and against edge 120 for retaining flush cup 168 in the shown position. It is also noted that an O-ring 130 is provided inbetween flush cup cylindrical wall 114 and annular ring 88 for providing a hermetic seal thereat and allowing the dielectric fluid to only travel outwardly from flush cup 68 through flush cup central opening 70.

As can be appreciated from the foregoing, the improved apparatus as shown in FIGS. 1-4 not only provides a plurality of different contact surfaces to the wire, but also allows for easily replacing the conductive member 54 from the working end 22.

In another embodiment, as shown in FIG. 5, the driving gear 66 is also a ring gear, however, is now mounted directly to the flush cup 68. Flush cup 68 is adapted for rotational movement about the longitudinal and, in this regard, is diagrammatically shown as having ball bearings 132. Similar to the flush cup shown in FIG. 1, the flush cup of FIG. 5 can also be detachably attached, however, in a position for preventing longitudinal movement and keeping ring gear 66 and teeth 72 in meshing alignment. An index mechanism in the form of a spring 104 and detent pin 102 is also provided similar to the embodiment of FIG. 1. However, in this embodiment, detent pin 102 cooperates with detents located on the flush cup surface 134. Further yet, indicating numerals or other symbols (not shown) are provided on outer surface 136 of flush cup 68 for indicating the discrete position corresponding to a contact surface being used by the conductive member 54.

It is noted that in the embodiment of FIG. 5, a prior art type of support assembly 14 has been modified for receiving the present improved apparatus and that conductive member 54 must be mounted by disassembling assembly 14 and placement of support body 48 and conductive member 54 from the top or the non-working end. Here, the support body 48 is forced against the tapered bore 138 of barrel 26. It is, however, contemplated that the support assembly 14 of FIG. 5 could be modified in a manner similar to FIG. 1 whereby loading of the conductive member 54 can be accomplished by removing flush cup 68 and loading the conductive member 54 from the working end 22.

FIGS. 6-12 diagrammatically show some additional contemplated embodiments according to the present invention. In each of these embodiments, a prior art type of flush cup 140 is shown affixed to the support assembly 14 via threads 142. In the embodiments of FIGS. 8 and 9, the driving gear is a bevel type gear 144 meshing with teeth 72 of conductive member 54. These bevel gears 144 have an axis of rotation which will always be at an acute angle from the conductive member longitudinal axis. In the embodiment shown in FIG. 8, bevel gear 144 is on the end of a shaft 146 which itself has a central longitudinal axis which is colinear with the bevel gear axis of rotation. At the other end of shaft 146, there is provided a knob 148 adapted for grasping and turning. Thus, by turning shaft 146 about its longitudinal axis, conductive member 54 is caused to turn about its axis for exposing the plurality of contact surfaces to wire 12. Similarly, an index mechanism such as a spring and ball detent is provided for stopping at discreet positions corresponding with contact surfaces. Further yet, symbols or other indicators (not shown) can be placed on the knob 148 or some other mechanically equivalent indication mechanism can be incorporated for showing the operator the contact surface currently being used.

In the embodiment of FIG. 8, similar to that of FIG. 1, the conductive member 54 is loaded from the working end 22. Here, a bore 56 for conductive member 54 is provided in supporting body 48. An annular edge 76 is not provided in bore 56 of this embodiment and, thus, conductive member 54 is inserted and removed from bore 56 from bore opening 150. An annular groove 152 is, however, provided on the inside surface of bore 56 and is adapted for receiving snap ring 154 thereat. Snap ring 154 extends into bore 56 and acts to retain conductive member 54 therein. Thus, conductive member 54 is selectively removed from bore 56 by first removing flush cup 140 and snap ring 154 and withdrawing conductive member 54 from bore 56. After a new conductive member is inserted within bore 56, the snap ring 154 is replaced and the new conductive member is ready for operation.

In the embodiment of FIG. 9, conductive member 54 is shown as being loaded from the top or the non-working end 22. It is noted, however, that both bevel gear 144 and second bevel gear 154 can be located closer to the workpiece in a manner whereby conductive member 54 can be loaded from the working end 22 similar to the embodiment of FIG. 8 described hereinabove. In the embodiment of FIG. 9, the second bevel gear 154 meshes with bevel driving gear 144 and a radial surface 156 is provided with second bevel gear 154 in a manner whereby the operator can cause the turning of bevel gear 154. In this fashion, bevel gear 154 which has an axis of rotation being parallel to the axis of rotation of bevel gear 144 causes bevel gear 144 to turn about its axis of rotation and, thus, also causing conductive member 54 to turn about its longitudinal axis and exposing its plurality of contact surfaces to wire 12. Similar to the embodiment of FIG. 8, a spring and ball detent mechanism is provided for selective stopping at discreet positions corresponding to specific contact surfaces and symbols or other indications are provided on radial surface 156 for indicating the specific contact surface being used.

Referring now to FIG. 7, a worm gear 158 is provided on the end of shaft 160. The worm gear and shaft 160 are situated generally perpendicular to conductive member 54. Here, worm gear 158 acts as the driving gear. At the other end of shaft 160 there is provided a knob 162 adapted for grasping and turning by the operator. Accordingly, turning of knob 162 causes driving worm gear 158 to turn and mesh with teeth 72 thereby causing conductive member 54 to turn about its longitudinal axis. Similar to the embodiment of FIG. 8, an index mechanism and an indication means is provided with this embodiment. Furthermore, conductive member 54 is loaded from the working end 22 through the use of snap ring 154.

Referring now to FIG. 6, conductive member 54 is again loaded from the working end 22 by removing the flush cup 140 and snap ring 154. In this embodiment however, there is provided a tool receiving means shown in the form of a hexagonally-shaped recess 164. Hexagonally-shaped recess 164 is provided at the longitudinal end of conductive member 54 and is adapted for receiving therein and cooperating with a tool shown in FIG. 6 in the form of a hexagonal ball 166 on the end of a rod 168. Thus, by inserting hexagonal ball 166 in recess 164 and turning rod 168, conductive member 54 is caused to turn about its longitudinal axis. An index mechanism is also provided with this embodiment similar to the index mechanisms shown and discussed hereinabove for stopping conductive member 54 at discreet positions. Here, however, the plurality of detents 108 are provided on the upper end of conductive member 54. Further yet, for speeding up the turning of conductive member 54 to the next indexed contact surface, a selectively openable and closable hole 170 is provided in flush cup 140. Thus, when turning is required, hole 170 is opened allowing the insertion of hexagonal ball 166 and rod 168 and, after conductive member 54 is turned to its next successive position, the tool is retracted therefrom and hole 170 is closed with an appropriate cap (not shown).

In the embodiments shown in FIGS. 10-12, there are shown toggle mechanisms adapted for selectively contacting at least one gear tooth 72 at a time and partially turning conductive member 54 about its longitudinal axis and, thereafter, retracting in a position for selectively repeating the contacting and partial turning. In the embodiment of FIG. 10, the toggle mechanism includes a flexible elongate shaft 172 received within a bore 174 and adapted for longitudinal movement therein. A push button 176 is provided at one end of shaft 172 whereas the other end 178 is in contact with gear teeth 72. A spring 180 biases shaft 172 in the position shown in FIGS. 10 and 11.

In operation, push button 176 is depressed causing end 178 of shaft 172 to be forced against one of a surface 182 of gear teeth 72 (shaped differently in this embodiment than previously discussed embodiments) and thus causing conductive member 54 to be tu