Method of and apparatus for wire-cutting a workpiece by electroerosion

Claim 2

In a method of wire-cutting a workpiece by electroerosion wherein a continuous wire electrode is axially transported from a supply means to a collection means along a predetermined wire guiding path to traverse the workpiece linearly between a pair of wire guide members disposed at opposite sides of the workpiece in the path and adapted to position the wire electrode therebetween in a machining relationship with the workpiece; and an electrical machining current is passed between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece while the workpiece is displaced transversely and relative to the wire electrode along a prescribed feed path to form a desired cut in the workpiece, the improvement which comprises the preliminary steps of: (a) forming a straight through-hole in the workpiece at a preselected location thereof representing a start point of said prescribed feed path; (b) inserting through said through-hole a detached wire element constituting a slender guide element and being straight at least along the length of said through-hole; (c) securely holding said detached wire element on said workpiece while leaving it inserted in said through-hole against dropping out; (d) positioning a wire electrode having a broken, free end portion extending continuously from the supply means through a first of said wire guide members disposed at an inlet side of said workpiece to locate said broken, free end portion ahead of said workpiece; (e) positioning said workpiece to locate said broken, free end portion projecting from said first wire guide member, ahead of and coaxially with said through-hole; (f) connecting an end of said detached wire element projecting from said through-hole at said inlet side with said broken, free end portion of the wire electrode; (g) withdrawing said detached wire element from said through-hole through a second of said wire guide members disposed at an outlet side of said workpiece and continuingly displacing said element to advance said wire electrode through said second wire guide member onto said collection means; and subsequently (h) proceeding to the wire-cutting of said workpiece by electroerosion.

Claim 3

The improvement defined in claim 3 wherein in step (a) a plurality of such through-holes as mentioned are formed in the workpiece at such preselected locations as mentioned in order to produce a corresponding number of desired cuts therein by electroerosion and wherein step (b) comprises inserting respective ones of a plurality of such detached wire elements as mentioned through the respective ones of said through-holes, step (c) comprises securely holding said detached wire elements on said workpiece while leaving them inserted in their respective through-holes against dropping out and the combination of steps (d) through (h) is carried out repetitively for successive machining operation starting at said through-holes in turn.

Claim 4

In a method of wire-cutting a workpiece by electroerosion wherein a continuous wire electrode is axially transported from a supply means to a collection means along a predetermined wire guiding path to traverse the workpiece linearly between a pair of wire guide members disposed at opposite sides of the workpiece in the path and adapted to position the wire electrode therebetween in a machining relationship with the workpiece; and an electrical machining current is passed between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece while the workpiece is disposed transversely and relative to the wire electrode along a prescribed feed path to form a desired cut in the workpiece, the improvement which comprises the preliminary steps of: (a) determining a preselected start point of said prescribed feed path at a location on said workpiece; (b) positioning said workpiece to locate said location to fall in a straight line path defined between said wire guide members; (c) positioning a said wire electrode having a broken, free end portion extending continuously from said supply means through a first of said wire guide members disposed at an inlet side of said workpiece to locate said broken, free end portion to lie between said first wire guide member and said location on said positioned workpiece; (d) forming a straight starting through-hole in said workpiece by introducing a straight slender tool electrode constituting a slender guide element to juxtapose it with said positioned workpiece at an outlet side thereof opposite to said inlet side and coaxially with said straight line path and electroerosively machining said through-hole in said workpiece with said slender tool electrode while advancing said slender tool electrode along said straight line path from said outlet side to advance a free end of said slender tool electrode into, through and out of said workpiece into said inlet side; (e) connecting said free end of said slender tool electrode projecting from said formed through-hole at said inlet side with said broken, free end portion of the wire electrode; (f) withdrawing said slender tool electrode connected to said wire electrode from said through-hole and through said outlet side and continuingly displacing said slender tool electrode to advance said wire electrode through said second machining guide member onto said collection means; and subsequently (g) proceeding to the wire-cutting of said workpiece by electroerosion.

Claim 5

In a method of wire-cutting a workpiece by electroerosion wherein a continuous wire electrode is axially transported from a supply means to a collection means along a predetermined wire guiding path to traverse the workpiece linearly between a pair of wire guide members disposed at opposite sides of the workpiece in the path and adapted to position the wire electrode therebetween in a machining relationship with the workpiece; and an electrical machining current is passed between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece while the workpiece is disposed transversely and relative to the wire electrode along a prescribed feed path to form a desired cut in the workpiece, the improvement which comprises the preliminary steps of: (a) determining a preselected start point of said prescribed feed path at a location on said workpiece; (b) positioning said workpiece to locate said location to fall in a straight line path defined between said wire guide members; (c) positioning a said wire electrode having a broken, free end portion extending continuously from said supply means through a first of said wire guide members disposed at an inlet side of said workpiece to locate said broken, free end portion to lie between said first wire guide member and said location on said positioned workpiece; (d) forming a straight starting through-hole in said workpiece by introducing a straight slender tool electrode constituting a slender guide element to juxtapose it with said positioned workpiece at an outlet side thereof opposite to said inlet side and coaxially with said straight line path and electroerosively machining said through-hole in said workpiece with said slender tool electrode while advancing said slender tool electrode along said straight line path from said outlet side to advance a free end of said slender tool electrode into, through and out of said workpiece into said inlet side; (e) connecting said free end of said slender tool electrode projecting from said formed through-hole at said inlet side with said broken, free end portion of the wire electrode; (f) withdrawing said slender tool electrode connected to said wire electrode from said through-hole and through said outlet side and continuingly displacing said slender tool electrode to advance said wire electrode through said second machining guide member onto said collection means; and subsequently (g) proceeding to the wire-cutting of said workpiece by electroerosion.

Claim 6

The improvement defined in claim 3, further comprising the step of imparting a sonic or ultrasonic vibration to said slender tool electrode during the electroerosive machining of said through-hole in said workpiece in step (d).

Claim 7

The improvement defined in claim 3 wherein said slender tool element is a wire electrode having a broken, free end portion and extending continuously to said collection means and constituting the counterpart of the first-mentioned wire electrode having said broken, free end portion to form said continuous wire electrode.

Claim 8

The improvement defined in claim 1 or claim 3 wherein said end of the slender guide element projecting from said through-hole is connected with said free end portion of the wire electrode at said inlet side by fusion-joining them together.

Claim 9

In a method of wire-cutting a workpiece by electroerosion wherein a continuous wire electrode is axially transported from a supply means to a collection means along a predetermined wire guiding path to traverse the workpiece linearly between a pair of wire guide members disposed at opposite sides of the workpiece in the path and adapted to position the wire electrode therebetween in a machining relationship with the workpiece; and an electrical machining current is passed between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece while the workpiece is displaced transversely and relative to the wire electrode along a prescribed feed path to form a desired cut in the workpiece, the improvement which comprises the preliminary steps of: (a) forming a straight through-hole in a workpiece at a preselected location thereof representing a start point of said prescribed feed path; (b) providing a wire electrode having a straightened broken, free end portion and extending continuously from the supply means through a first of said guide members by: (b1) holding a continuous electrode wire extending continuously between said supply means and said collection means through a previously machined cut, (b2) heating said continuous electrode wire at least along a part thereof located in one of said opposite sides between said previous cut and the corresponding wire guide member to a temperature sufficient to thermally soften at least said part while drawing said electrode wire at least in said one side under a tension sufficient to elongate and slenderize said softened part, (b3) applying a stress onto said elongated part sufficient to break there said electrode wire to produce a first broken half constituting said wire electrode and having said straightened broken, free end portion and a second broken half extending continuously to said collection means through a second of said wire guide members, and (b4) displacing said second broken half through said second wire guide member to collect into said collection means; (c) displacing said previous cut and positioning said wire electrode to locate said straightened broken, free end portion thereof, ahead of said workpiece; (d) positioning said workpiece to locate said through-hole therein coaxially with and ahead of said straightened broken, free end portion of, said wire electrode; (e) advancing said wire electrode to displace said straightened broken, free end portion into, through and out of said through-hole and through said second guide member; and subsequently (f) proceeding to the wire-cutting of said workpiece by electroerosion.

Claim 10

In a method of wire-cutting a workpiece by electroerosion wherein a continuous wire electrode is axially transported from a supply means to a collection means along a predetermined wire guiding path to traverse the workpiece linearly between a pair of wire guide members disposed at opposite sides of the workpiece in the path and adapted to position the wire electrode therebetween in a machining relationship with the workpiece; and an electrical machining current is passed between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece while the workpiece is displaced transversely and relative to the wire electrode along a prescribed feed path to form a desired cut in the workpiece, the improvement which comprises the preliminary steps of: (a) forming a straight through-hole in a workpiece at a preselected location thereof representing a start point of said prescribed feed path; (b) providing a wire electrode having a straightened broken, free end portion and extending continuously from the supply means through a first of said guide members by: (b1) holding a continuous electrode wire extending continuously between said supply means and said collection means through a previously machined cut, (b2) heating said continuous electrode wire at least along a part thereof located in one of said opposite sides between said previous cut and the corresponding wire guide member to a temperature sufficient to thermally soften at least said part while drawing said electrode wire at least in said one side under a tension sufficient to elongate and slenderize said softened part, (b3) applying a stress onto said elongated part sufficient to break there said electrode wire to produce a first broken half constituting said wire electrode and having said straightened broken, free end portion and a second broken half extending continuously to said collection means through a second of said wire guide members, and (b4) displacing said second broken half through said second wire guide member to collect into said collection means; (c) displacing said previous cut and positioning said wire electrode to locate said straightened broken, free end portion thereof, ahead of said workpiece; (d) positioning said workpiece to locate said through-hole therein coaxially with and ahead of said straightened broken, free end portion of, said wire electrode; (e) advancing said wire electrode to displace said straightened broken, free end portion into, through and out of said through-hole and through said second guide member; and subsequently (f) proceeding to the wire-cutting of said workpiece by electroerosion.

Claim 11

The improvement defined in claim 7 wherein said heating is applied to said electrode wire so as to create a predetermined temperature gradient at least in the region of said one side.

Claim 12

In combination with an apparatus for wire-cutting a workpiece by electroerosion having a continuous wire electrode axially transported from a supply means to a collection means along a predetermined wire guiding path; a pair of wire guide members disposed at opposite sides of the workpiece in the path for bridging the axially traveling wire electrode linearly thereacross through the workpiece and positioning it in a machining relationship with the workpiece; power supply means for passing an electrical machining current between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece; and cutting feed means for displacing the workpiece transversely and relative to the axially traveling wire electrode along a prescribed feed path to form a desired electroerosion cut in the workpiece, (a) means for forming a straight through-hole in the workpiece at a preselected location thereof representing a start point of said preselected feed path; (b) a detached wire element constituting a slender guide element being straight at least along the length of said through-hole and adapted to be inserted into said through-hole for anchoring therein against dropping out; (c) means for positioning a wire electrode having a broken, free end portion extending continuously from the supply means through a first of said wire guide members disposed at an inlet side of said workpiece to locate said broken, free end portion ahead of said workpiece; (d) means for positioning said workpiece to locate said broken, free end portion from said first wire guide member, ahead of and coaxially with said through-hole; (e) means for connecting an end of said detached wire element projecting from said through-hole at said inlet side with said broken, free end portion of the wire electrode; and (f) means for withdrawing said detached wire element from said through-hole through a second of said wire guide members disposed at an outlet side of said workpiece and continuingly displacing said wire element to advance said wire electrode through said second guide member onto said collection means.

Claim 13

In combination with an apparatus for wire-cutting a workpiece by electroerosion having a continuous wire electrode axially transported from a supply means to a collection means along a predetermined wire guiding path; a pair of wire guide members disposed at opposite sides of the workpiece in the path for bridging the axially traveling wire electrode linearly thereacross through the workpiece and positioning it in a machining relationship with the workpiece; power supply means for passing an electrical machining current between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece; and cutting feed means for displacing the workpiece transversely and relative to the axially traveling wire electrode along a prescribed feed path to form a desired electroerosion cut in the workpiece, (a) means for forming a straight through-hole in the workpiece at a preselected location thereof representing a start point of said preselected feed path; (b) a detached wire element constituting a slender guide element being straight at least along the length of said through-hole and adapted to be inserted into said through-hole for anchoring therein against dropping out; (c) means for positioning a wire electrode having a broken, free end portion extending continuously from the supply means through a first of said wire guide members disposed at an inlet side of said workpiece to locate said broken, free end portion ahead of said workpiece; (d) means for positioning said workpiece to locate said broken, free end portion from said first wire guide member, ahead of and coaxially with said through-hole; (e) means for connecting an end of said detached wire element projecting from said through-hole at said inlet side with said broken, free end portion of the wire electrode; and (f) means for withdrawing said detached wire element from said through-hole through a second of said wire guide members disposed at an outlet side of said workpiece and continuingly displacing said wire element to advance said wire electrode through said second guide member onto said collection means.

Claim 14

In combination with an apparatus for wire-cutting a workpiece by electroerosion having a continuous wire electrode axially transported from a supply means to a collection means along a predetermined wire guiding path; a pair of wire guide members disposed at opposite sides of the workpiece in the path for bridging the axially traveling wire electrode linearly thereacross through the workpiece and positioning it in a machining relationship with the workpiece; power supply means for passing an electrical machining current between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece; and cutting feed means for displacing the workpiece transversely and relative to the axially traveling wire electrode along a prescribed feed path to form a desired electroerosion cut in the workpiece, (a) means for positioning said workpiece to locate a preselected position representing a start point of said prescribed feed path, to fall in a straight line path defined between said wire guide members; (b) means for positioning a said wire electrode having a broken, free end portion extending continuously from said supply means through a first of said wire guide members disposed at an inlet side of said workpiece to locate said broken, free end portion to lie between said first wire guide member and said positioned workpiece; (c) a straight slender tool electrode constituting a slender guide element; (d) means for positioning said slender tool electrode to juxtapose it with said positioned workpiece at an outlet side thereof opposite to said inlet side and coaxially with said straight line path; (e) a power supply for passing an electroerosion machining current between said slender tool electrode and said workpiece to remove material from the workpiece; (f) a feed unit for advancing said slender tool electrode along said straight line path from said outlet side to advance a free end of said slender tool electrode into, through and out of said workpiece into said inlet side, thereby electroerosively machining said through-hole in said workpiece; (g) means for connecting said free end of said slender tool electrode projecting from said formed through-hole at said inlet side with said broken, free end portion of the wire electrode; and (h) means for withdrawing said slender tool electrode connected to said wire electrode from said through-hole and through said outlet side, thereby leading said wire electrode from said inlet side into said outlet side.

Claim 15

In combination with an apparatus for wire-cutting a workpiece by electroerosion having a continuous wire electrode axially transported from a supply means to a collection means along a predetermined wire guiding path; a pair of wire guide members disposed at opposite sides of the workpiece in the path for bridging the axially traveling wire electrode linearly thereacross through the workpiece and positioning it in a machining relationship with the workpiece; power supply means for passing an electrical machining current between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece; and cutting feed means for displacing the workpiece transversely and relative to the axially traveling wire electrode along a prescribed feed path to form a desired electroerosion cut in the workpiece, (a) means for positioning said workpiece to locate a preselected position representing a start point of said prescribed feed path, to fall in a straight line path defined between said wire guide members; (b) means for positioning a said wire electrode having a broken, free end portion extending continuously from said supply means through a first of said wire guide members disposed at an inlet side of said workpiece to locate said broken, free end portion to lie between said first wire guide member and said positioned workpiece; (c) a straight slender tool electrode constituting a slender guide element; (d) means for positioning said slender tool electrode to juxtapose it with said positioned workpiece at an outlet side thereof opposite to said inlet side and coaxially with said straight line path; (e) a power supply for passing an electroerosion machining current between said slender tool electrode and said workpiece to remove material from the workpiece; (f) a feed unit for advancing said slender tool electrode along said straight line path from said outlet side to advance a free end of said slender tool electrode into, through and out of said workpiece into said inlet side, thereby electroerosively machining said through-hole in said workpiece; (g) means for connecting said free end of said slender tool electrode projecting from said formed through-hole at said inlet side with said broken, free end portion of the wire electrode; and (h) means for withdrawing said slender tool electrode connected to said wire electrode from said through-hole and through said outlet side, thereby leading said wire electrode from said inlet side into said outlet side.

Claim 16

The combination defined in claim 10, further comprising means for imparting a sonic or ultrasonic vibration to said slender tool electrode being advanced along said straight line path by said means (f).

Claim 17

The combination defined in claim 10 wherein said means for connecting comprises a fusion welding means.

Claim 18

In combination with an apparatus for wire-cutting a workpiece by electroerosion having a continuous wire electrode axially transported from a supply means to a collection means along a predetermined wire guiding path; a pair of wire guide members disposed at opposite sides of the workpiece in the path for bridging the axially traveling wire electrode linearly thereacross through the workpiece and positioning it in a machining relationship with the workpiece; power supply means for passing an electrical machining current between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece; and cutting feed means for displacing the workpiece transversely and relative to the axially traveling wire electrode along a prescribed feed path to form a desired electroerosion cut in the workpiece, (a) means for forming a straight through-hole in a workpiece at a preselected location thereof representing a start point of said prescribed feed path; (b) means for providing a said wire electrode with a straightened broken, free end portion and extending continuously from the supply means through a first of said wire guide members, said means (b) comprising: (b1) means for holding a continuous electrode wire extending continuously between said supply means and said collection means through a previously machined cut; (b2) a heater means for heating said continuous electrode wire at least along a part thereof located in one of said opposite sides between said previous cut and the corresponding wire guide member to a temperature sufficient to thermally soften at least said part, (b3) means operable in conjunction with means (b2 ) for drawing said electrode wire being heated, at least in said one side under a tension sufficient to elongate and slenderize said softened part, (b4) means for applying a stress onto said elongated part sufficient to break there said electrode wire to produce a first broken half constituting said wire electrode and having said straightened broken, free end portion and a second broken half extending continuously to said collection means through a second of said wire guide members, and (b5) means for displacing said second broken half through said second wire guide member to collect into said collection (c) means for positioning said wire electrode so as to locate said straightened broken, free end portion thereof ahead of said workpiece, (d) means for positioning said workpiece to locate said through-hole therein coaxially with and ahead of said straightened broken, free end portion of, said wire electrode; and (e) means for advancing said wire electrode to displace said straightened broken, free end portion into, through and out of said through-hole and through said second guide member.

Claim 19

In combination with an apparatus for wire-cutting a workpiece by electroerosion having a continuous wire electrode axially transported from a supply means to a collection means along a predetermined wire guiding path; a pair of wire guide members disposed at opposite sides of the workpiece in the path for bridging the axially traveling wire electrode linearly thereacross through the workpiece and positioning it in a machining relationship with the workpiece; power supply means for passing an electrical machining current between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece; and cutting feed means for displacing the workpiece transversely and relative to the axially traveling wire electrode along a prescribed feed path to form a desired electroerosion cut in the workpiece, (a) means for forming a straight through-hole in a workpiece at a preselected location thereof representing a start point of said prescribed feed path; (b) means for providing a said wire electrode with a straightened broken, free end portion and extending continuously from the supply means through a first of said wire guide members, said means (b) comprising: (b1) means for holding a continuous electrode wire extending continuously between said supply means and said collection means through a previously machined cut; (b2) a heater means for heating said continuous electrode wire at least along a part thereof located in one of said opposite sides between said previous cut and the corresponding wire guide member to a temperature sufficient to thermally soften at least said part, (b3) means operable in conjunction with means (b2 ) for drawing said electrode wire being heated, at least in said one side under a tension sufficient to elongate and slenderize said softened part, (b4) means for applying a stress onto said elongated part sufficient to break there said electrode wire to produce a first broken half constituting said wire electrode and having said straightened broken, free end portion and a second broken half extending continuously to said collection means through a second of said wire guide members, and (b5) means for displacing said second broken half through said second wire guide member to collect into said collection (c) means for positioning said wire electrode so as to locate said straightened broken, free end portion thereof ahead of said workpiece, (d) means for positioning said workpiece to locate said through-hole therein coaxially with and ahead of said straightened broken, free end portion of, said wire electrode; and (e) means for advancing said wire electrode to displace said straightened broken, free end portion into, through and out of said through-hole and through said second guide member.

Claim 20

The combination defined in claim 13 wherein said heater means has a heating surface tapered so as to create a predetermined temperature gradient at least in the region of said one side, convergently in the direction of advance of said wire electrode effected by means. (e).

Claim 21

In a method of wire-cutting a workpiece by electroerosion wherein a continuous wire electrode is axially transported from a supply means to a collection means along a predetermined wire guiding path to traverse the workpiece linearly between a pair of wire guide members disposed at opposite sides of the workpiece in the path and adapted to position the wire electrode therebetween in a machining relationship with the workpiece; and an electrical machining current is passed between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece while the workpiece is displaced transversely and relative to the wire electrode along a prescribed feed path to form a desired cut in the workpiece, the improvement which comprises the preliminary steps of: (a) determining a preselected start point of said prescribed feed path at a location on said workpiece; (b) positioning said workpiece to locate to fall in a straight line path defined between said wire guide members; (c) positioning a said wire electrode having a broken, free end portion extending continously from said supply means through a first of said wire guide members disposed at an inlet side of said workpiece to locate said broken, free end portion projecting from said first guide member to lie coaxially with said straight line path ahead of said location on said workpiece; (d) electroerosively machining said workpiece with said broken, free end portion while advancing said wire electrode along said straight line path to advance said broken, free end portion into through and out of said workpiece and thence through a second of said wire guide members disposed at an outlet side of the workpiece for collection onto said collection means, thereby forming a straight starting through-hole at said location on said workpiece and simultaneously threading said wire electrode through said workpiece; and subsequently (e) proceeding to the wire-cutting of said workpiece by electroerosion.

Claim 22

In a method of wire-cutting a workpiece by electroerosion wherein a continuous wire electrode is axially transported from a supply means to a collection means along a predetermined wire guiding path to traverse the workpiece linearly between a pair of wire guide members disposed at opposite sides of the workpiece in the path and adapted to position the wire electrode therebetween in a machining relationship with the workpiece; and an electrical machining current is passed between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece while the workpiece is displaced transversely and relative to the wire electrode along a prescribed feed path to form a desired cut in the workpiece, the improvement which comprises the preliminary steps of: (a) determining a preselected start point of said prescribed feed path at a location on said workpiece; (b) positioning said workpiece to locate to fall in a straight line path defined between said wire guide members; (c) positioning a said wire electrode having a broken, free end portion extending continously from said supply means through a first of said wire guide members disposed at an inlet side of said workpiece to locate said broken, free end portion projecting from said first guide member to lie coaxially with said straight line path ahead of said location on said workpiece; (d) electroerosively machining said workpiece with said broken, free end portion while advancing said wire electrode along said straight line path to advance said broken, free end portion into through and out of said workpiece and thence through a second of said wire guide members disposed at an outlet side of the workpiece for collection onto said collection means, thereby forming a straight starting through-hole at said location on said workpiece and simultaneously threading said wire electrode through said workpiece; and subsequently (e) proceeding to the wire-cutting of said workpiece by electroerosion.

Claim 23

In a method of wire-cutting a workpiece by electroerosion wherein a continuous wire electrode is axially transported from a supply means to a collection means along a predetermined wire guiding path to traverse the workpiece linearly between a pair of wire guide members disposed at opposite sides of the workpiece in the path and adapted to position the wire electrode therebetween in a machining relationship with the workpiece; and an electrical machining current is passed between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece while the workpiece is displaced transversely and relative to the wire electrode along a prescribed feed path to form a desired cut in the workpiece, the improvement which comprises the preliminary steps of: (a) forming a straight through-hole in a workpiece at a preselected location thereof representing a start point of said prescribed feed path; (b) providing a wire electrode having a straightened broken, free end portion and extending continuously from one of said supply and collection means through a first of said wire guide members by: (b1) holding a continuous electrode wire extending continuously between said supply means and said collection means through a previously machined cut, (b2) heating said continuous electrode wire at least along a part thereof located in one of said opposite sides between said previous cut and the corresponding wire guide member to a temperature sufficient to thermally soften at least said part while drawing said electrode wire at least in said one side under a tension sufficient to elongate and slenderize said softened part, and (b3) applying a stress onto said elongate part sufficient to break there said electrode wire to produce a first broken half having said straightened broken, free end portion and a second broken half extending continuously to the other of said supply and collection means through a second of said wire guide members, and (c) withdrawing one of said first and second broken halves which extends through said previous cut into said one side, from said previous cut whereby the broken end portions of said halves are located ahead of said previous cut in said opposite sides, respectively; (d) displacing said previous cut and positioning said workpiece to locate said straight through-hole therein coaxially with and ahead of said straightened broken, free end portion of, said first broken half; (e) displacing said first broken half along said straight line path to pass said straightened broken free end portion into, through and out of said through-hole until it comes into engagement with the broken, free end portion of said second broken half; (f) connecting together the free end portions of said first and second broken halves brought into engagement; (g) advancing the thus-formed continuous wire electrode from said supply means to said collection means; and subsequently (h) proceeding to the wire-cutting of said workpiece by electroerosion.

Claim 24

In a method of wire-cutting a workpiece by electroerosion wherein a continuous wire electrode is axially transported from a supply means to a collection means along a predetermined wire guiding path to traverse the workpiece linearly between a pair of wire guide members disposed at opposite sides of the workpiece in the path and adapted to position the wire electrode therebetween in a machining relationship with the workpiece; and an electrical machining current is passed between the wire electrode and the workpiece across a machining gap flooded with a machining medium to electroerosively remove material from the workpiece while the workpiece is displaced transversely and relative to the wire electrode along a prescribed feed path to form a desired cut in the workpiece, the improvement which comprises the preliminary steps of: (a) forming a straight through-hole in a workpiece at a preselected location thereof representing a start point of said prescribed feed path; (b) providing a wire electrode having a straightened broken, free end portion and extending continuously from one of said supply and collection means through a first of said wire guide members by: (b1) holding a continuous electrode wire extending continuously between said supply means and said collection means through a previously machined cut, (b2) heating said continuous electrode wire at least along a part thereof located in one of said opposite sides between said previous cut and the corresponding wire guide member to a temperature sufficient to thermally soften at least said part while drawing said electrode wire at least in said one side under a tension sufficient to elongate and slenderize said softened part, and (b3) applying a stress onto said elongate part sufficient to break there said electrode wire to produce a first broken half having said straightened broken, free end portion and a second broken half extending continuously to the other of said supply and collection means through a second of said wire guide members, and (c) withdrawing one of said first and second broken halves which extends through said previous cut into said one side, from said previous cut whereby the broken end portions of said halves are located ahead of said previous cut in said opposite sides, respectively; (d) displacing said previous cut and positioning said workpiece to locate said straight through-hole therein coaxially with and ahead of said straightened broken, free end portion of, said first broken half; (e) displacing said first broken half along said straight line path to pass said straightened broken free end portion into, through and out of said through-hole until it comes into engagement with the broken, free end portion of said second broken half; (f) connecting together the free end portions of said first and second broken halves brought into engagement; (g) advancing the thus-formed continuous wire electrode from said supply means to said collection means; and subsequently (h) proceeding to the wire-cutting of said workpiece by electroerosion.

Claim 25

The improvement defined in claim 16 wherein said heating is applied to said electrode wire so as to create a predetermined temperature gradient at least in the region of said one side.