Method of automatically feeding wire to an electric discharge machine

• US 5,077,457 A
• Filed: 11/24/1989
• Issued: 12/31/1991
• Est. Priority Date: 11/28/1988
• Status: Expired due to Term

• Current Assignee: Seibu Electric & Machinery Co., Ltd.
• Original Assignee: Seibu Electric & Machinery Co., Ltd.
• Inventors: Matsuo, Yoshitada, Onaka, Takemoto
• Primary Examiner(s): Evans, Geoffrey S.
• Application Number:
  US07/440,943
• Time in Patent Office: 767 Days
• Field of Search: 219/69.12, 219/69.17
• US Class Current: 219/69.12
• CPC Class Codes: B23H 7/10 Supporting, winding or electrical connection of wire-electrode

Abstract

A method of automatically feeding wire to an electric discharge machine, wherein when the wire electrode is broken during when the wire electrode is effecting the discharge machining for the work according to a predetermined machining profile, the wire electrode is passed through a worked slit via a feed pipe at a position of the worked slit at the frontmost portion of machining for the work by the wire electrode or at a position which is slightly returned back from the frontmost portion along the machining profile without returning the wire feed pipe to the position of start hole that is perforated in advance in the work, and the discharge machining is executed again by the wire electrode for the work making it possible to greatly improve the machining efficiency. Prior to passing the wire electrode in the worked slit formed in the work, furthermore, an electric current is supplied to the wire electrode to anneal it in order to remove internal stress from the wire electrode and to extent it straight, such that the wire electrode can be inserted in the worked slit of the work easily and quickly.

Claims

1. In an electric discharge machine which develops electric discharge by applying a voltage across a work fastened to a work table and a wire electrode that is successively delivered from a wire feeding port of a wire head via a wire electrode feeding system, in order to machine said work into a predetermined machining profile utilizing the energy of electric discharge, a method of automatically feeding the wire to the electric discharge machine to insert said wire electrode in a start hole that has been perforated in advance in said work via a feed pipe mounted on a holder that reciprocally moves on guide rods provided in the head of said electric discharge machine, comprising:

a step for detecting the breakage of said wire electrode during the electric discharge machining using a breakage sensor that is provided in said wire electrode feeding system and that detects the condition of feeding said wire electrode;

a step for stopping the relative movement of said work table and said wire head in response to the breakage of said wire electrode that is detected by said breakage sensor during the electric discharge machining;

a step for taking up and removing said wire electrode of the broken side;

a step for annealing said wire electrode of the feeding side by causing an electric current to flow therethrough to extend said wire electrode straight by eliminating internal stresses which cause curving and curling;

a step for cutting and removing the tip of said wire electrode annealed in order to trim the tip of said wire electrode by causing the tip to hang down vertically;

a step for moving down the tip of said feed pipe to said wire head and for moving down said annealed wire electrode while feeding said wire electrode thus annealed to meet the descending speed of said feed pipe;

a step for delivering said wire electrode to thread said wire electrode in said worked slit of said work at a point where the wire electrode was broken;

a step for drawing said wire electrode that has passed through said worked slit to extend said wire electrode under the tensed condition;

a step for upwardly moving said feed pipe to return said feed pipe to the initial position; and

a step for developing electric discharge by applying a voltage across said wire electrode and said work in order to discharge-machine said work again into a predetermined machining profile using the energy of electric discharge.

2. A method of automatically feeding wire to an electric discharge machine according to claim 1, wherein in a step for delivering said wire electrode to insert said wire electrode in said worked slit of said work at a point where the wire was broken, said wire electrode is slightly moved back in response to the failure in trying to insert said wire electrode in said worked slit, and said wire electrode is delivered to try again to insert said wire electrode in said worked slit.

3. A method of automatically feeding wire to an electric discharge machine according to claim 1, wherein in a step for delivering said wire electrode to insert said wire electrode in said worked slit of said work at a point where the wire was broken, said wire electrode is slightly moved back and the tip of said wire electrode is cut and is removed in response to the failure in trying to insert said wire electrode in said worked slit, and said wire electrode is delivered to try again to insert said wire electrode in said worked slit.

4. In an electric discharge machine which develops electric discharge by applying a voltage across a work fastened to a work table and a wire electrode that is successively delivered from a wire feeding port of a wire head via a wire electrode feeding system, in order to machine said work into a predetermined machining profile utilizing the energy of electric discharge, a method of automatically feeding the wire to the electric discharge machine to insert said wire electrode in a start hole that has been perforated in advance in said work from said wire feeding port of said wire head via a feed pipe mounted on a holder that reciprocally moves on guide rods provided in the head of said electric discharge machine, comprising:

a step for detecting the breakage of said wire electrode during the electric discharge machining using a breakage sensor that is provided in said wire electrode feeding system and that detects the condition of feeding said wire electrode;

a step for stopping the relative movement of said work table and said wire head in response to the breakage of said wire electrode that is detected by said breakage sensor during the electric discharge machining;

a step for taking up and removing said wire electrode of the broken side;

a step for annealing said wire electrode of the feeding side by causing an electric current to flow therethrough to extend said wire electrode straight by eliminating internal stresses which cause curving and curling;

a step for cutting and removing the tip of said wire electrode annealed in order to trim the tip of said wire electrode by causing the tip to hang down vertically;

a step for moving down the tip of said feed pipe to said wire head and for moving down said annealed wire electrode while feeding said wire electrode thus annealed to meet the descending speed of said feed pipe;

a step for moving back said work table fastening said work relative to said wire feeding port of said wire head so that said wire feeding port of said wire head is moved back from the worked slit at the point where the wire is broken by a small distance along the worked profile;

a step for delivering said wire electrode to thread it in said worked slit at a position moved back from the point of said work where the wire is broken along the worked profile;

a step for drawing said wire electrode that has passed through said worked slit to extend said wire electrode under the tensed condition;

a step for upwardly moving said feed pipe to return said feed pipe to the initial position;

a step for processing said wire electrode to the portion of discharge machining along said worked slit that has been formed already in said work; and

a step for developing electric discharge by applying a voltage across said wire electrode and said work in order to discharge-machine said work again into a predetermined machining profile using the energy of electric discharge.

5. A method of automatically feeding wire to an electric discharge machine according to claim 4, wherein in a step for delivering said wire electrode to insert said wire electrode in said worked slit cf said work at a point where the wire was broken, said wire electrode is slightly moved back in response to the failure in trying to insert said wire electrode in said worked slit, and said wire electrode is delivered to try again to insert said wire electrode in said worked slit.

6. A method of automatically feeding wire to an electric discharge machine according to claim 4, wherein in a step for delivering said wire electrode to insert said wire electrode in said worked slit of said work at a point where the wire was broken, said wire electrode is slightly moved back and the tip of said wire electrode is cut and is removed in response to the failure in trying to insert said wire electrode in said worked slit, and said wire electrode is delivered to try again to insert said wire electrode in said worked slit.

7. In an electric discharge machine which develops electric discharge by applying a voltage across a work fastened to a work table and a wire electrode that is successively delivered from a wire feeding port of a wire head via a wire electrode feeding system, in order to machine said work into a predetermined machining profile utilizing the energy of electric discharge, a method of automatically feeding the wire to the electric discharge machine to insert said wire electrode in a start hole that has been perforated in advance in said work via a feed pipe mounted on a holder that reciprocally moves on guide rods provided in the head of said electric discharge machine, comprising:

a step for detecting the breakage of said wire electrode during the electric discharge machining using a breakage sensor that is provided in said wire electrode feeding system and that detects the condition of feeding said wire electrode;

a step for stopping the relative movement of said work table and said wire head in response to the breakage of said wire electrode that is detected by said breakage sensor during the electric discharge machining;

a step for taking up and removing said wire electrode of the broken side using a lead roller that is provided for said electric discharge machine at a position on the downstream side of said work, for holding said wire electrode of the feeding side by a pair of annealing rollers provided for said holder and by a pair of common rollers which are mounted on a support member provided on said head and which are arranged under said annealing rollers;

a step for annealing said wire electrode by passing an electric current to said wire electrode positioned between said annealing rollers and said common rollers via feeder pins provided for said annealing rollers and said common rollers to extend said wire electrode straight by eliminating internal stresses causing curving and curling;

a step for cutting and removing the tip of said wire electrode thus annealed by actuating a cutter provided on said support member in order to trim the tip of said wire electrode by causing the tip to hang down vertically;

a step for moving down said holder along said guide rods until the tip of said feed pipe reaches said wire rod and for moving down said wire electrode while feeding said wire electrode thus annealed by actuating said annealing rollers to meet the descending speed of said feed pipe;

a step for delivering said wire electrode by actuating said annealing rollers to thread it in said worked slit of said work at a point where the wire was broken;

a step for drawing said wire electrode that has passed through said worked slit by actuating said lead roller to extend said wire electrode under the tensed condition;

a step for upwardly moving said holder along said guide rods to raise said feed pipe until it returns to the initial position; and

a step for developing electric discharge by applying a voltage across said wire electrode and said work in order to discharge-machine said work again into a predetermined machining profile using the energy of electric discharge.

8. A method of automatically feeding wire to an electric discharge machine according to claim 7, wherein in a step for delivering said wire electrode to insert said wire electrode in said worked slit of said work at a point where the wire was broken, said wire electrode is slightly moved back by actuating said annealing rollers in response to the failure in trying to insert said wire electrode in said worked slit, and said wire electrode is delivered by actuating said annealing rollers to try again to insert said wire electrode in said worked slit at said position that is moved back.

9. A method of automatically feeding wire to an electric discharge machine according to claim 7, wherein in a step for delivering said wire electrode to insert said wire electrode in said worked slit of said work at a point where the wire was broken, said wire electrode is slightly moved back by actuating said annealing rollers and the tip of said wire electrode is cut and is removed by actuating said cutter in response to the failure in trying to insert said wire electrode in said worked slit, and said wire electrode is delivered by actuating said annealing rollers to try again to insert said wire electrode in said worked slit at said position that is moved back.

10. In an electric discharge machine which develops electric discharge by applying a voltage across a work fastened to a work table and a wire electrode that is successively delivered from a wire feeding port of a wire head via a wire electrode feeding system, in order to machine said work into a predetermined machining profile utilizing the energy of electric discharge, a method of automatically feeding the wire to the electric discharge machine to insert said wire electrode in a start hole that has been perforated in advance in said work from said wire feeding port of said wire head via a feed pipe mounted on a holder that reciprocally moves on guide rods provided in the head of said electric discharge machine, comprising:

a step for detecting the breakage of said wire electrode during the electric discharge machining using a breakage sensor that is provided in said wire electrode feeding system and that detects the condition of feeding said wire electrode;

a step for stopping the relative movement of said work table and said wire head in response to the breakage of said wire electrode that is detected by said breakage sensor during the electric discharge machining;

a step for taking up and removing said wire electrode of the broken side by actuating a lead roller that is provided for said electric discharge machine at a position on the downstream side of said work, for holding said wire electrode of the feeding side by a pair of annealing rollers provided for said holder and by a pair of common rollers which are mounted on a support member provided on said head and which are arranged under said annealing rollers;

a step for annealing said wire electrode by passing an electric current to said wire electrode positioned between said annealing rollers and said common rollers via feeder pins provided for said annealing rollers and said common rollers to extend said wire electrode straight by eliminating internal stresses causing curving and curling;

a step for cutting and removing the tip of said wire electrode thus annealed by actuating a cutter provided on said support member in order to trim the tip of said wire electrode by causing the tip to hang down vertically;

a step for moving down said holder along said guide rods until the tip of said feed pipe reaches said wire rod and for moving down said wire electrode while feeding said wire electrode thus annealed by actuating said annealing rollers to meet the descending speed of said feed pipe;

a step for moving back said work table fastening said work relative to said wire feeding port of said wire head such that said wire feeding port of said wire head is moved back by a small distance from the worked slit at a point where the wire was broken along the worked profile;

a step for delivering said wire electrode by actuating said annealing rollers to thread said wire electrode in said worked slit of said work at a position moved back from the point where the wire was broken along the worked profile;

a step for drawing said wire electrode that has passed through said worked slit by actuating said lead roller to extend said wire electrode under the tensed condition;

a step for upwardly moving said holder along said guide rods to raise said feed pipe until it returns to the initial position;

a step for forwardly moving said work table to proceed said wire electrode to the discharge machining portion along said worked slit that has been formed already in said work; and

a step for developing electric discharge by applying a voltage across said wire electrode and said work in order to discharge-machine said work again into a predetermined machining profile using the energy of electric discharge.

11. A method of automatically feeding wire to an electric discharge machine according to claim 10, wherein in a step for delivering said wire electrode to insert said wire electrode in said worked slit of said work at a point where the wire was broken, said wire electrode is slightly moved back by actuating said annealing rollers in response to the failure in trying to insert said wire electrode in said worked slit, and said wire electrode is delivered by actuating said annealing rollers to try again to insert said wire electrode in said worked slit.

12. A method of automatically feeding wire to an electric discharge machine according to claim 10, wherein in a step for delivering said wire electrode to insert said wire electrode in said worked slit of said work at a position where the wire was broken, said wire electrode is lightly moved back by actuating said annealing rollers and the tip of said wire electrode is cut and is removed by actuating said cutter in response to the failure in trying to insert said wire electrode in said worked slit, and said wire electrode is delivered by actuating said annealing rollers to try again to insert said wire electrode in said worked slit.