JP2006055863A - Flash welding equipment and flash welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flash welding equipment and a flash welding method in which a portion to be welded is heated and joined without retraction by repeating only advancement and stop to repeat the discharge and arc scattering. <P>SOLUTION: In a flush step, a control unit 17 calculates the target position of a moving side welding member 3 in a predetermined period based on the target displacement curve to indicate the position of the moving side welding member 3 with respect to the elapsed time (Step S20), and when it is detected that the position of the moving side welding member 3 measured by a position measurement unit 15 does not reach the target position (Step S21), the moving side welding member 3 is advanced (Step S22). When the position of the moving side welding member 3 measured by the position measurement unit 15 reaches the target position, the moving side welding member 3 is stopped. By repeating the flush step before reaching the final target position, the advance and the stop of the moving side welding member 3 are repeated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flash welding apparatus and a flash welding method for joining two welding members to which a voltage is applied.

Steel piles such as steel pipe piles and H-shaped steel piles are used for deep foundations because they have a high driving penetration force, a reliable construction, and strong bending resistance against horizontal loads. When joining steel pipe piles, as shown in Patent Document 1, a flash welding method is used in which a welded joint with high joint strength is created with high efficiency. In the joining method shown in Patent Document 1, the steel pipe pile to be joined and the inner peripheral surface of the steel pipe pile press-fitted into the ground are each held by a clamping device, and the welding electrode is placed on the outer circumference in the vicinity of the welded part of both steel pipe piles. While attaching and supplying power from the welding transformer to the welding electrode, the steel pipe piles to be joined are moved forward and backward from the top and the welded parts are repeatedly detached and heated to heat the welded parts. Steel pipe piles are joined.
JP 2004-176431-A

  In order to move the steel pipe pile forward and backward at high speed against the gravity as in Patent Document 1, high-performance hydraulic equipment and a control device are required. Also, when the rail material is welded in a horizontal state, vibration occurs when the rail material is moved forward and backward at high speed. Therefore, it is necessary to firmly fix the rail material that is moved forward and backward. Is a big issue.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a flash welding apparatus and a flash welding method that do not require a high-speed forward and backward movement, and that join welding members only by advancing and stopping.

  The flash welding apparatus of the present invention advances and stops so as to follow a target displacement curve indicating the position of the movable welding member with respect to the elapsed time while applying a voltage to the fixed welding member and the movable welding member. By repeating only this, discharge and spark scattering are generated to heat the welded portion, and the heated welded portion is pressed. It is preferable that the target displacement curve represents a position with respect to an elapsed time of a movable welding member that gradually generates a uniform discharge from a partial discharge in the weld and moves so as to keep the generated uniform discharge. It is good to heat in advance until the weld is uniformly discharged.

  The flash welding method of the present invention advances and stops so as to follow a target displacement curve indicating the position of the movable welding member with respect to the elapsed time while applying a voltage to the fixed welding member and the movable welding member. By repeating only this, discharge and spark scattering are generated to heat the welded portion, and the heated welded portion is pressed.

  According to this flash welding apparatus, by repeating only forward and stop, it is possible to repeat the discharge of the welding member and the scattering of the spark without performing the backward movement, and advanced hydraulic equipment and control for performing the forward and backward movement at high speed. Equipment is unnecessary. Freezing is prevented by making the target displacement curve represent the position of a movable weld that moves gradually to generate a uniform discharge from a partial discharge in the weld and keep the generated uniform discharge. Can be joined smoothly. By heating in advance, the unstable operation at the start of discharge can be reduced and bonding can be performed quickly. According to this flash welding method, by repeating only forward and stop, the discharge of the welding member and the scattering of the spark can be repeated without performing the backward operation, and there is no need to perform forward and backward at high speed.

  The flash welding apparatus 1 manufactures a long welded member by joining two welded members by flash welding. In the present embodiment, an H-shaped steel pile embedded in the fixed-side welding member with the longitudinal direction oriented in the vertical direction is used, and an H-shaped steel pile in which the longitudinal direction is directed in the vertical direction is used in the moving-side welding member. The front end portion of the moving side welding member is welded to the rear end portion of the welding member.

  As shown in the front view of FIG. 1A and the side view of FIG. 1B, the flash welding apparatus 1 includes a fixed side clamp 10, a moving side clamp 11, a moving unit 12, a fixed side electrode 13, and a moving side electrode. 14, a position measurement unit 15, a power supply 16, and a control unit 17.

  The fixed side clamp 10 fixes the rear end portion of the fixed side welding member 2, and the moving side clamp 11 is fixed to the leading end portion of the moving side welding member 3. As shown in the functional block diagram of FIG. 2, the moving unit 12 includes a hydraulic cylinder 121, a hydraulic inverter pump 122, a direction switching valve 123, and a pump inverter 124. Oil is sent from the hydraulic inverter pump 122 to the hydraulic cylinder 121 connected between the moving side clamp 11 and the fixed side clamp 10, and the direction switching valve 123 is connected between the hydraulic cylinder 121 and the hydraulic inverter pump 122. By switching the oil flow, the hydraulic cylinder 121 is expanded and contracted to change the position of the moving side welding member 3 relative to the fixed side welding member 2. The oil inverter 124 sends a pulse to the hydraulic inverter pump 122 to control the operation timing and the operation amount of the hydraulic inverter pump 122 to move the moving side welding member 3.

  A fixed side electrode 13 is connected to the rear end portion of the fixed side welding member 2, and a moving side electrode 14 is connected to the tip end portion of the moving side welding member 3. The position measuring unit 15 connected to the fixed-side clamp 10 and the moving-side clamp 11 measures the resistance value of the potentiometer that varies according to the distance between the fixed-side clamp 10 and the moving-side clamp 11, thereby moving-side welding. The position of the member 3 is measured.

  The power supply 16 includes a three-phase AC generator 161, a rectifier 162, an inverter drive circuit 163, a power source inverter 164, a transformer 165, and a diode rectifier 166, and rectifies the AC voltage from the 400V three-phase AC generator 161. The voltage is rectified by 162, converted to a rectangular wave AC voltage by a power source inverter 164 controlled by an inverter drive circuit 163, stepped down by a transformer 165, converted to a DC voltage by a diode rectifier 166, and the DC voltage is converted to a fixed side electrode 13. And the moving-side electrode 14, and applied between the fixed-side welding member 2 and the moving-side welding member 3.

  The control unit 17 controls the inverter drive circuit 163 of the power supply 16 to apply and stop the voltage between the fixed side welding member 2 and the moving side welding member 3 through the fixed side electrode 13 and the moving side electrode 14. And by controlling the pump inverter 124 and the direction switching valve 123 of the moving unit 12, the moving side welding member 3 is moved forward to approach the fixed side welding member 2, or the moving side welding member 3 is fixed to the fixed side. By stopping the welding member 2, as shown in the flowchart of FIG. 3, the flash that heats the rear end portion of the fixed-side welding member 2 serving as a welded portion and the front end portion of the moving-side welding member 2 to an appropriate temperature. A flash welding method including a process (step S10) and an upset process (step S11) for rapidly pressing the heated weld is performed.

  In the flash process, a large current is caused to flow by causing a short circuit between the rear end portion of the fixed-side welding member 2 and the front end portion of the moving-side welding member 3, and the discharged portion is intensively heated and melted. Let When the member in the short-circuited portion that has been heated and melted scatters (flashes) as a spark, the discharge is weakened or discontinued, so that the moving-side welding member 3 is brought closer to the fixed-side welding member 2 and the discharge and sparks are scattered. Need to repeat. The control part 17 advances the movement side welding member 3 so that the target displacement curve showing the position of the movement side welding member 3 with respect to elapsed time may be followed.

  In the flash process, when the moving-side welding member 3 approaches the fixed-side welding member 2, a discharge is generated, and the short-circuited welded portion is intensively heated and melted. When the heated and melted member at the joining point scatters as a spark, the discharge is interrupted, but the discharge is stopped again by moving the moving-side welding member 3 closer to the fixed-side welding member 2, and the discharge and the spark scatter are repeated and welded. The part is heated. For example, as shown in FIG. 4, the current flowing between the moving-side welding member 3 and the fixed-side welding member 2 flows locally due to the roughness of the welded portion at the initial stage of the flash process. Does not flow so much, and by repeating the sparks scattered by the discharge, there are many portions to be discharged, the current gradually increases, and eventually the entire surface of the welded portion is discharged almost uniformly.

A target displacement curve representing the position of the moving side welding member 3 with respect to the elapsed time is obtained by measurement in advance by experiments. In the initial stage of the flash process, the moving side welding member 3 is controlled so as to continuously generate local discharge and spark scattering while slightly moving the moving side welding member 3, and the moving side is moved in a single operation over time. When the distance to which the welding member 3 advances is increased stepwise and the welded portion becomes rough and discharge is uniformly generated, control is performed to advance at a substantially constant speed while maintaining uniformity. . The target displacement curve is obtained by approximating the position y (mm) of the moving-side welding member 3 with respect to the elapsed time t (seconds) measured by moving the moving-side welding member 3 by a linear expression or a quadratic expression. . For example, when welding a steel material having a cross-sectional area of about 8000 mm ² with an average power of 60 kW and a welding time of 170 seconds, when the measurement result is approximated by the least square method, the target displacement curve is expressed by equations 1a to 1 as shown in FIG. A combination of four quadratic formulas of Formula 1d, a combination of five primary formulas of Formula 2a to Formula 2e as shown in FIG. 5B, or a quadratic formula of Formula 3a and a primary formula of Formula 3b It is represented by a combination of

  The control unit 17 that executes the flash welding method controls the inverter drive circuit 163 to apply a voltage between the fixed-side welding member 2 and the moving-side welding member 3, and moves the moving-side welding member to the initial position of the target displacement curve. 3 is arranged, the direction switching valve 123 is switched to the forward direction, and the flush process is first executed.

  In the flash process, as shown in the flowchart of FIG. 6, the control unit 17 determines the elapsed time at a constant minute time period, for example, a 0.1 second period, based on the target displacement curve indicating the position of the moving side welding member 3 with respect to the elapsed time. The target position of the moving-side welding member 3 corresponding to is calculated (step S20). When the target displacement curve is represented by a combination of quadratic equations as shown in FIG. 5A, it is based on Formula 1a when it is about 0 second or more and less than about 90 seconds, and based on Formula 1b when it is about 90 seconds or more and less than about 115 seconds. The target position is calculated based on Formula 1c for about 115 seconds to less than about 134 seconds, and based on Formula 1d for about 134 seconds to less than about 170 seconds. When the target displacement curve is represented by a combination of linear equations as shown in FIG. 5B, it is based on Equation 2a when it is about 0 second or more and less than about 43 seconds, and based on Equation 2b when it is about 43 seconds or more and less than about 87 seconds. The target position is calculated based on Expression 2c when it is about 87 seconds or more and less than about 125 seconds, based on Expression 2d when it is about 125 seconds or more and less than about 143 seconds, and based on Expression 2e when it is about 143 seconds or more and less than about 170 seconds. When the target displacement curve is expressed by a combination of a quadratic expression and a linear expression as in Expression 3a and Expression 3b, if it is about 0 seconds or more and less than about 140 seconds, it is about 140 seconds or more and less than about 170 seconds based on Expression 3a. Then, a target position is calculated based on Formula 3b.

  When it is detected that the position of the moving welding member 3 measured by the position measuring unit 15 has not reached the calculated target position (step S21), the moving welding member 3 is advanced (step S22), and the position measuring unit If the position of the moving welding member 3 measured at 15 has reached the calculated target position, the moving welding member 3 is stopped. Only advance and stop of the moving side welding member 3 are repeated until the final target position is reached.

  When the flash process is finished, the control unit 17 executes the upset process. As shown in the flowchart of FIG. 7, the control unit 17 that executes the upset process suddenly operates the hydraulic inverter pump 122 and presses the moving-side welding member 3 and the fixed-side welding member 2 with a strong pressure. Start (step S30), after the set time has elapsed from the start of upset, the inverter drive circuit 163 is controlled to stop the application of voltage (step S31), and after applying pressure to a predetermined distance, it is held for a predetermined time ( Step S32). By applying the voltage for a while, impurities and heated metal remaining on the boundary surface between the fixed-side welding member 2 and the moving-side welding member 3 can be pushed out and welded with a healthy high-temperature metal. After the upset process is completed, the deburring of the welded portion may be performed by releasing the moving side clamp 11 and advancing the deburring tool as necessary.

  According to the flash welding apparatus 1, by repeating only the advancement and stop of the welding member, it is possible to repeat the discharge of the welding member and the sparks without performing the forward and backward movement at high speed, and to perform the forward and backward movement at high speed. No need for advanced hydraulic equipment. In particular, when welding members are joined vertically, it is possible to prevent the hydraulic equipment from becoming complicated by not performing high-speed forward retreating against gravity. Furthermore, by performing an operation represented by a linear expression or a quadratic expression that approximates the trajectory of the welding member in the power control method, it is possible to prevent freezing even in a large area. In addition, this invention can weld not only H-shaped steel pile but welding members, such as a sheet pile, a steel pipe, and a rail material.

  Note that, for a while after the start of the flashing process, the fixed-side welding member 2 and the moving-side welding member 3 are not sufficiently heated, and it is difficult for sparks to fly. It is desirable that the member 3 is short-circuited, and the weld is heated in advance by resistance so that the sparks can fly easily.

It is the front view and side view of a flash welding apparatus. It is a functional block diagram of an electric system. It is a flowchart of a flash welding method. It is a figure which shows the relationship between an electric current value and time. It is a figure which shows the locus | trajectory of the position of the movement side welding member with respect to elapsed time. It is a flowchart of a flash process. It is a flowchart of an upset process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Flash welding apparatus, 2; Fixed side welding member, 3; Moving side welding member,
10; fixed side clamp, 11; moving side clamp, 12; moving unit,
13; stationary electrode, 14; moving electrode, 15; position measuring unit, 16; power supply,
17; control unit, 121; hydraulic cylinder, 122; hydraulic inverter pump,
123; Direction switching valve, 124; Pump inverter, 161; Three-phase AC generator,
162; rectification unit; 163; inverter drive circuit; 164; inverter for power supply;
165; transformer, 166; diode rectifier.

Claims (4)

  While applying a voltage to the fixed welding member and the movable welding member, the discharge and spark are repeated by repeating only forward and stop so as to follow the target displacement curve indicating the position of the movable welding member with respect to the elapsed time. A flash welding apparatus that heats a welded portion by causing scattering of the heat and presses the heated welded portion.   The said target displacement curve represents the position with respect to the elapsed time of the movable welding member which produces | generates a uniform discharge gradually from the partial discharge in the said welding part, and moves so that the generated uniform discharge may be maintained. The flash welding apparatus according to.   The flash welding apparatus according to claim 1, wherein heating is performed in advance until the welded portion is uniformly discharged. While applying a voltage to the fixed welding member and the movable welding member, the discharge and spark are repeated by repeating only forward and stop so as to follow the target displacement curve indicating the position of the movable welding member with respect to the elapsed time. Heat the weld to generate splashes,
A flash welding method characterized by press-contacting a heated weld.

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