Heat treatment furnace, heating device, manufacturing method of wire electrode and heat diffusion treatment method

Abstract

The disclosure is a heat treatment furnace which heats an element wire for a wire electrode to perform a heat diffusion treatment and includes: first, second and third rotary electrodes to which a voltage is applied; a motor that rotationally drives the rotary electrodes; and a control device. The first, second and third rotary electrodes are arranged in a manner that the element wire is laid in a V-shape or an I-shape in an order of the second rotary electrode, the first rotary electrode and the third rotary electrode from the upstream side in a travel direction of the element wire. The element wire is caused to travel, a voltage is applied to the first, second and third rotary electrodes, and a current flows through and heats the element wire which travels in a first heating section and a second heating section.

Claims

1. A heat treatment furnace, which moves an element wire having been zinc-galvanized at a predetermined speed and heats the element wire to perform a heat diffusion treatment, comprising: a first rotary electrode, a second rotary electrode and a third rotary electrode to which a voltage is applied; a motor that rotationally drives the first rotary electrode, the second rotary electrode and the third rotary electrode; and a control device; wherein the first rotary electrode, the second rotary electrode and the third rotary electrode are arranged in a manner that the element wire is laid in a V-shape or an I-shape in an order of the second rotary electrode, the first rotary electrode and the third rotary electrode from the upstream side in a travel direction of the element wire; wherein the motor is driven according to a command from the control device to cause the element wire to travel, a voltage is applied to the first rotary electrode, and a voltage having a sign opposite to that of the first rotary electrode is applied to the second rotary electrode and the third rotary electrode; and wherein a current flows through and heats the element wire which travels in a first heating section between the second rotary electrode and the first rotary electrode and in a second heating section between the third rotary electrode and the first rotary electrode, wherein the heat treatment furnace further comprises cooling covers arranged on peripheries of the first rotary electrode, the second rotary electrode and the third rotary electrode, respectively, wherein each of the cooling covers comprises a pipeline for circulating a cooling medium, the control device circulating the cooling medium in the pipeline by a cooling pump and cooling the first rotary electrode, the second rotary electrode and the third rotary electrode and during cooling medium circulation, the heat treatment furnace is configured to not directly cool the element wire, wherein the heat treatment furnace further comprises a first temperature sensor and a second temperature sensor, the first temperature sensor being arranged in a vicinity of the first heating section or the second heating section of a travel path of the element wire and detecting a temperature of the element wire, the second temperature sensor being attached to the first rotary electrode, the second rotary electrode or the third rotary electrode and detects a temperature of the first rotary electrode, the second rotary electrode or the third rotary electrode, wherein the control device controls an application voltage applied to the first rotary electrode, the second rotary electrode, and the third rotary electrode by the temperatures detected by the first temperature sensor and the second temperature sensor.

2. The heat treatment furnace according to claim 1, wherein a dancer roller device is arranged on the travel path of the element wire, and the control device detects the position of the dancer roller device and controls the rotation of the motor.

3. The heat treatment furnace according to claim 1, wherein a heat insulation cover is arranged in the first heating section and the second heating section.

4. A heating device, comprising: the heat treatment furnace according to claim 1, a delivery device for delivering the element wire to the heat treatment furnace, and a winding device for winding a heat treatment wire discharged from the heat treatment furnace.

5. A manufacturing method of a wire electrode, in which an element wire used for a wire electrode is heated and subjected to a heat diffusion treatment, wherein the element wire travels on a V-shaped or an I-shaped path formed by laying in an order of a second rotary electrode, a first rotary electrode and a third rotary electrode, and the element wire is heated and subjected to the heat diffusion treatment by causing a current to flow through the element wire in a first heating section between the second rotary electrode and the first rotary electrode and in a second heating section between the third rotary electrode and the first rotary electrode while cooling the first rotary electrode, the second rotary electrode and the third rotary electrode and not direct cooling the element wire, wherein the first rotary electrode, the second rotary electrode and the third rotary electrode are cooled by cooling covers arranged on peripheries of the first rotary electrode, the second rotary electrode and the third rotary electrode, respectively, wherein each of the cooling covers comprises a pipeline for circulating a cooling medium, the control device circulating the cooling medium in the pipeline by a cooling pump and cooling the first rotary electrode, the second rotary electrode and the third rotary electrode, and wherein a temperature of the element wire and a temperature of the first rotary electrode, the second rotary electrode or the third rotary electrode are detected by a first temperature sensor and a second temperature sensor, and an application voltage applied to the first rotary electrode, the second rotary electrode, and the third rotary electrode is controlled.

6. A heat diffusion treatment method, in which an element wire used for a wire electrode is heated and subjected to a heat diffusion treatment, wherein the element wire travels on a V-shaped or an I-shaped path formed by laying in an order of a second rotary electrode, a first rotary electrode and a third rotary electrode, and the element wire is heated and subjected to the heat diffusion treatment by causing a current to flow through the element wire in a first heating section between the second rotary electrode and the first rotary electrode and in a second heating section between the third rotary electrode and the first rotary electrode while cooling the first rotary electrode, the second rotary electrode and the third rotary electrode and not direct cooling the element wire, wherein the first rotary electrode, the second rotary electrode and the third rotary electrode are cooled by cooling covers arranged on peripheries of the first rotary electrode, the second rotary electrode and the third rotary electrode, respectively, wherein each of the cooling covers comprises a pipeline for circulating a cooling medium, the control device circulating the cooling medium in the pipeline by a cooling pump and cooling the first rotary electrode, the second rotary electrode and the third rotary electrode, and wherein a temperature of the element wire and a temperature of the first rotary electrode, the second rotary electrode or the third rotary electrode are detected by a first temperature sensor and a second temperature sensor, and an application voltage applied to the first rotary electrode, the second rotary electrode, and the third rotary electrode is controlled.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view showing an outline of a heating device 100 of the disclosure.

(2) FIG. 2 is a side schematic view showing an outline of a heat treatment furnace 10 of the disclosure.

(3) FIG. 3 is side schematic view showing an outline of a dancer roller device 4 of the above embodiment.

(4) FIG. 4 is a block diagram showing the configuration of the heat treatment furnace 10 of the above embodiment.

(5) FIG. 5 is a side schematic view showing another arrangement configuration of rotary electrodes 1A, 1B and 1C of the above embodiment.

(6) FIG. 6 is a flowchart showing a process in a manufacturing method of a wire electrode of the above embodiment.

DESCRIPTION OF THE EMBODIMENTS

(7) FIG. 1 is a schematic view showing an outline of a heating device 100 of the disclosure, and FIG. 2 is a side schematic view showing an outline of a heat treatment furnace 10 of the disclosure. FIG. 4 is a block diagram showing the configuration of the heat treatment furnace 10 of the above embodiment.

(8) The heating device 100 of the disclosure is a device for heating an element wire 21 by passing a current through the element wire 21 having been zinc-galvanized to perform a heat diffusion treatment, and includes the heat treatment furnace 10 of the disclosure, a delivery device 20, and a winding device 30.

(9) In the heating device 100, the zinc-galvanized element wire 21 sent from the delivery device 20 is introduced into the heat treatment furnace 10 and is caused to travel at a predetermined travel speed, and a heat diffusion treatment is performed on the element wire 21 by a resistance heating method. After that, the element wire 21 is wound around the winding device 30 as a heat treatment wire 22.

(10) The heat treatment furnace 10 is a heat treatment furnace for applying a voltage between electrodes to heat the element wire 21, and includes: a rotary electrode 1A (second rotary electrode); a rotary electrode 1B (third rotary electrode); a rotary electrode 1C (first rotary electrode); a motor 11 for rotating the rotary electrode; a plurality of rollers 3, 3 . . . for transporting the element wire 21; a dancer roller device 4; a cooling pump 5; a temperature sensor 61 that detects the temperature of the element wire 21; a temperature sensor 62 that detects the temperature of the rotary electrode; a control device 7; a regulated DC power supply 8; heat insulation covers 91, 91 that cover heating sections; cooling covers 93 that cover the rotary electrodes 1A, 1B and 1C; and a housing 92 for arranging various members.

(11) FIG. 5 is a side schematic view showing another arrangement configuration of the rotary electrodes 1A, 1B and 1C of the above embodiment.

(12) The rotary electrodes 1A, 1B and 1C are columnar energizing rollers, the rotary electrodes 1A and 1B are arranged on the upper part inside the housing 92, and the rotary electrode 1C is arranged on the lower part inside the housing 92 between the rotary electrode 1A and the rotary electrode 1B. The peripheries of the rotary electrodes 1A, 1B and 1C are respectively covered with the cooling cover 93.

(13) The element wire 21 is wound around the outer peripheral surfaces of the rotary electrodes 1A, 1B and 1C, and is stretched therebetween. The rotary electrodes 1A, 1B and 1C are driven to rotate by the motors 11 respectively arranged on the rotary electrodes 1A, 1B and 1C, and the element wire 21 travels in the heat treatment furnace 10 at a predetermined speed due to the rotation of the rotary electrodes 1A, 1B and 1C. Specifically, the element wire 21 is inserted from a carry-in port arranged in the housing 92 and travels upward via the roller 3, and then changes the travel direction by the rotation of the rotary electrode 1A to travel downward. After that, by the rotation of the rotary electrode 1C, the element wire 21 travels upward, and then the element wire 21 is wound around the rotary electrode 1B and discharged from a carry-out port.

(14) As for the arrangement of the rotary electrodes 1A, 1B and 1C, when the element wire is laid in an order of the rotary electrode 1A, the rotary electrode 1C and the rotary electrode 1B, the element wire between the rotary electrode 1A and the rotary electrode 1C and the element wire between the rotary electrode 1B and the rotary electrode 1C may be parallel to each other to form an I shape as shown in FIG. 2, or may be separated from each other at an angle to form a V shape as shown in FIG. 5.

(15) A negative voltage is applied to the rotary electrodes 1A and 1B by the regulated DC power supply 8, and a positive voltage is applied to the rotary electrode 1C. Therefore, a current flows through the element wire 21 stretched over a first heating section K1 between the rotary electrode 1A and the rotary electrode 1C and a second heating section K2 between the rotary electrode 1C and the rotary electrode 1B, and then the element wire 21 generates heat due to the resistance of the element wire 21 itself. Specifically, a current flows from the rotary electrode 1C to the rotary electrode 1A through the element wire 21, and similarly flows from the rotary electrode 1C to the rotary electrode 1B through the element wire 21. Along with the current, heat diffusion occurs on the surface of the element wire 21, and a high-quality diffusion layer is formed. The element wire 21 is heated in the first heating section K1 and further heated in the second heating section K2, and thereby the diffusion treatment proceeds rapidly, the diffusion layer on the outer surface of the element wire 21 becomes zinc-rich brass and is discharged to the outside as the heat treatment wire 22.

(16) Here, a negative voltage is applied to the rotary electrodes 1A and 1B, and a positive voltage is applied to the rotary electrode 1C, but a positive voltage may be applied to the rotary electrodes 1A and 1B, and a negative voltage may be applied to the rotary electrode 1C.

(17) The motor 11 is a member arranged respectively for rotating the rotary electrodes 1A, 1B and 1C, and specifically, a servomotor is used. The motor 11 controls the rotation of the rotary electrodes 1A, 1B and 1C according to a command signal from the control device 7.

(18) The rollers 3, 3 . . . are arranged in the housing 92 for transporting the element wire 21, and are arranged at intervals in a manner of not loosening the element wire 21 so that the element wire 21 travels smoothly.

(19) FIG. 3 is a side schematic view showing an outline of the dancer roller device 4 of the above embodiment.

(20) The dancer roller device 4 is a member for maintaining a state in which a constant tension is applied to the element wire 21, and includes: a dancer roller 41 for winding the element wire 21; a dancer arm 42 that pivotally supports the dancer roller 41 at the front end; a potentiometer 43 attached to a rotation axis of the dancer arm 42 and detecting the angle of the dancer arm 42; and a dancer weight 44 for imparting tension. By adjusting the size and the position of the dancer weight 44, the tension imparted to the element wire 21 is adjusted.

(21) The cooling pump 5 is a cooling device for cooling the rotary electrodes 1A, 1B and 1C. A pipeline for circulating a liquid cooling medium is attached to the cooling cover 93, the cooling medium in the pipeline is circulated by the cooling pump 5, and the rotary electrodes 1A, 1B and 1C in the cooling cover 93 are forcibly cooled.

(22) The temperature sensor 61 is a detector that detects the temperature of the element wire 21. For example, an infrared sensor that is a non-contact temperature sensor is used as the temperature sensor 61. The temperature sensor 61 is arranged in the vicinity of the travel path of the element wire 21 and in the vicinity of the first heating section K1 or the second heating section K2.

(23) The temperature sensor 62 is a detector that detects the temperature of the rotary electrodes 1A, 1B and 1C, particularly the temperature of a rotary connector attached to the rotary electrodes 1A, 1B and 1C. For example, an infrared sensor that is a non-contact temperature sensor is used as the temperature sensor 62. The temperature sensor 62 may be attached to all of the rotary electrodes 1A, 1B and 1C, or may be attached only to the rotary electrode 1B having a high load.

(24) The control device 7 is a device that controls the entire heating device 100, and includes a control unit 71 and an operation unit 72.

(25) The control unit 71 controls the entire heating device 100. For example, the control unit 71 controls the drive of the motor 11, controls an application voltage applied to the rotary electrodes 1A, 1B and 1C, and detects an abnormality by the temperature sensors 61 and 62.

(26) As for the drive control of the motor 11, the control unit 71 detects the angle of the dancer arm 42 by the potentiometer 43 attached to the dancer arm 42, gives a command to the motor 11 according to the value of the angle, and controls the rotation speeds of the rotary electrodes 1A, 1B and 1C. Specifically, when the dancer arm 42 is in a horizontal equilibrium position, the rotation speeds of the rotary electrodes 1A, 1B and 1C are maintained as they are, and when the dancer arm 42 moves upward, the rotation speeds of the rotary electrodes 1A, 1B and 1C are gradually reduced. Further, when the dancer arm 42 moves downward, the rotation speeds of the rotary electrodes 1A, 1B and 1C are gradually accelerated.

(27) In this way, because the rotation speeds of the rotary electrodes 1A, 1B and 1C are changed depending on the position of the dancer arm 42, it is possible to consistently send the element wire 21 with a constant tension.

(28) Further, when the temperature of the element wire 21 or the temperature of the rotary electrodes 1A, 1B and 1C detected by the temperature sensors 61 and 62 is an abnormal value, the control unit 71 stops applying the voltage to the rotary electrodes 1A, 1B and 1C.

(29) The operation unit 72 makes various settings for the heating device 100, such as a setting of the value of the application voltage, and is preferably a touch panel integrated with a display unit for example. In addition, the operation unit 72 is not limited to the touch panel, and may be equipped with a display unit and use an input device such as a mouse, a joystick, a touch pen and the like, or a command input device such as a keyboard and the like.

(30) The delivery device 20 is a device that drives a roller 26 from a payoff reel 27 around which the zinc-galvanized element wire 21 is wound and carries the element wire 21 to the heat treatment furnace 10.

(31) The winding device 30 is a device that winds the heat treatment wire 22 discharged from the heat treatment furnace 10 after the heat diffusion treatment is completed onto a spool 37 by driving the roller 36.

(32) (Flow of Manufacturing Method of Wire Electrode)

(33) FIG. 6 is a flowchart showing a process of the embodiment in the manufacturing method of the wire electrode. Hereinafter, specifically, a preferred embodiment of the disclosure is described by taking a process of manufacturing a brass composite wire electrode as an example, the brass composite wire electrode having a wire diameter of 90.2 mm and having a core made of brass which is composed of 65% by weight of copper and 35% by weight of zinc and a surface layer of a diffusion layer.

(34) A first step in the process of manufacturing the wire electrode is a brass producing step in which raw materials of copper and zinc are put into a melting furnace at a predetermined ratio to be melted and mixed in order to produce a brass bus. Specifically, in order that the concentration of copper or zinc put into the melting furnace is measured and the mixing ratio of molten copper and zinc finally becomes a desired weight ratio in the core of the wire electrode, a copper plate or copper ingot and zinc powder are selectively put into the melting furnace. In the example, the weight ratio of copper to zinc is adjusted to 65/35.

(35) A second step is a bus casting step for casting a bus. The bus is generated by continuously pouring the brass that has been mixed and melted at a desired mixing ratio in a linear manner and cooling the brass. The wire diameter of the bus is set to a size as close as possible to the wire diameter of a core wire in a subsequent zinc galvanizing step within a range in which the bus can be formed by casting.

(36) A third step is a core wire forming step in which the bus is sequentially passed through a wire drawing die and gradually reduced in diameter by wire drawing processing to form a core wire used in a zinc galvanizing step. Because the bus to be casted has bamboo-like knots and small irregularities on the surface that are generated during manufacturing, the bus is gradually reduced in diameter and the wire diameter of the formed core wire is made constant at the same time by at least two times of wire drawing processing.

(37) A fourth step is a zinc galvanizing step in which the core wire obtained in the core wire forming step is zinc-galvanized by an electro-galvanizing method. In the zinc galvanizing step, the core wire is stretched with a predetermined constant tension across a galvanizing bathtub, and the core wire is caused to travel at a constant travel speed by detecting the travel speed and adjusting the winding speed. The surface coating of the core wire is removed in an alkaline electrolytic linear bathtub, alkaline cleaning liquid remaining on the surface is washed away by a water cleaning device, and then the core wire is introduced into an acidic electro-galvanizing bathtub. The zinc-galvanized surface of the element wire led out from the galvanizing bathtub is sufficiently dried by a warm air heater, and then the element wire is wound on the spool by the winding device.

(38) A fifth step is a heat diffusion treatment step in which the element wire having been zinc-galvanized with the electro-galvanizing method is continuously heated and diffused by the heating device 100 of the disclosure. Specifically, the element wire 21 having the zinc coating layer formed by electro-galvanizing is wound around the payoff reel 27, drives the roller 26, leaves the delivery device 20, and then is inserted to the heat treatment furnace 10 from the carry-in port arranged in the housing 92 of the heat treatment furnace 10. The element wire 21 passes through the first heating section K1 from the rotary electrode 1A to the rotary electrode 1C by the rotation of the rotary electrodes 1A, 1B and 1C, and then passes through the second heating section K2 from the rotary electrode 1C to the rotary electrode 1B. When the element wire 21 is traveling, a voltage is applied to the rotary electrodes 1A, 1B and 1C, a current flows through the element wire 21 in the first heating section K1 and the second heating section K2, and heat diffusion occurs and the diffusion layer is formed on the surface of the element wire 21. The element wire 21 is heated in the first heating section K1 and further heated in the second heating section K2, and thereby the diffusion treatment proceeds rapidly, the diffusion layer on the outer surface of the element wire 21 becomes zinc-rich brass and is discharged to the outside as the heat treatment wire 22.

(39) When the entire area of the zinc coating layer, in other words, the entire outer peripheral surface uniformly becomes zinc-rich brass, the element wire 21 is sequentially led out to the outside of the heat treatment furnace 10. Then, the element wire 21 led out from the heat treatment furnace 10 is exposed to air at room temperature to be cooled naturally, and thereafter, the diffusion is stopped and the coating layer is fixed.

(40) The heat treatment wire 22 discharged from the heat treatment furnace 10 after the heat diffusion treatment is completed is wound on the spool 37 by the roller 36 of the winding device 30.

(41) A sixth step is an element wire drawing step in which the element wire is passed through the wire drawing die to generate a wire electrode having an arbitrary desired wire diameter. A brass composite wire electrode line can be manufactured.

(42) The heat treatment furnace, the heating device, the manufacturing method of the wire electrode and the heat diffusion treatment method of the disclosure described above should not be limited to specific embodiments, and can be modified and carried out within a range that does not deviate from technical ideas of the disclosure.

INDUSTRIAL APPLICABILITY

(43) The disclosure can be used in the technical field of metal processing. In particular, the disclosure is applied to a wire-cut for cutting metal with high precision to manufacture dies or parts. The disclosure provides an improved tool electrode having excellent processing precision and improved processing speed in a wire-cut at a lower cost. The disclosure contributes to the development of the technical field of metal processing.