JP2007210006A - Inverter type dc resistance spot welding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inverter type DC resistance spot welding machine capable of performing the welding of high quality by forming the welding current waveform most suitable for a material and a shape of a work. <P>SOLUTION: The spot welding machine has a rewritable welding condition storage unit 131 for dividing the total conduction period per unit spot welding into a plurality of continuous parts, and storing the current value and the time for each part, and a welding condition input operation unit 132A for optionally setting/changing the current value and the time of all parts or a part thereof for each part. The current value and the time for each part input by the welding condition input operation unit 132A are stored in the welding condition storage unit 131, and electrode moving mechanisms 112, 140 and an inverter type DC conduction circuit 150 are operated based on the current value and the time of each part stored in the welding condition storage unit 131. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a spot welder, and more particularly to an inverter type DC resistance spot welder provided with a programmable controller.

  A resistance spot welder equipped with a programmable controller selects, for example, a four-step sequence or an eight-step sequence energization mode or sequence step, squeeze time in this sequence step, welding The welding condition is determined by inputting four time elements such as energization time, holding time, and opening time. Of the four time elements of the sequence step, the squeeze time is a time for taking a time delay from when the electrode starts moving until the welding material is further touched and the applied pressure is sufficiently increased. Also, the welding energization time is literally the time during which welding current is energized and welded under a sufficient applied pressure. The holding time is a time during which pressurization is continued even after the welding energization is completed in order to cool the welded portion. The rest time is also referred to as an open time or an off time, and is a time from when the electrode is instructed to open until the electrode is released to move to the next spot position and the next spot welding pressure command is given. In addition to these time factors, there are some which can set conditions such as whether or not auxiliary energization is performed, whether or not preheating energization is performed, and whether or not postheating energization is performed. Auxiliary energization is used when welding a single spot with only one energization of the welding current when welding mild steel or the like. The preheating energization is performed for the purpose of making the contact resistance uniform and familiar in order to prevent cracking of the curable material. Post-heat energization is performed for the purpose of preventing cracking due to rapid cooling and relaxing the hardening zone. Furthermore, in order to take temper control in welding of air-cooled hardened steel, etc., it is possible to input a control program for re-energizing after a pause time, or for pulsation welding that repeats energization-pause for the same current. There is also known one capable of setting and inputting a control program. (See Patent Document 1)

In addition, in an automatic welding machine that automatically performs a series of multiple times of welding, multiple types of welding schedules are preset in the programmable controller, and the welding condition setting input for each welding schedule is made at the factory where welding is performed. There are types that can do. In this type of welding machine, for example, on the operation screen of the programmable controller, a schedule number (No.) is input, and welding condition setting values (squeeze time, welding energization time, welding current, etc.) are input, The conditions for each welding schedule can be set arbitrarily. (See Patent Document 2)
JP 2004-1036 A Japanese Patent Laid-Open No. 9-19774

  As described above, a welding machine capable of setting various welding conditions in accordance with an object to be welded, use conditions, and the like is already known.

  However, with a conventional welding machine, the welding current that flows during one spot welding cannot be optimized according to the shape and material of the workpiece. Inverter type DC resistance spot welder can obtain stable welding current with less ripple than AC type and capacitor type, and high output energy density, so high quality welding can be done in a short time. However, in order to further improve these advantages and realize better quality welding, the welding current waveform of one spot welding is optimal according to the shape and material of the work piece It is necessary to make it.

  The problem to be solved by the present invention is an inverter type direct current resistance spot welding which can perform high quality welding by optimizing the welding current flowing in one spot welding according to the shape and material of the workpiece. Is to provide a machine.

  In order to solve the above-described problems, the present invention provides an inverter type DC resistance spot welding machine that performs welding by energizing a welding current while applying pressure to an overlapped portion of materials to be welded. The total energization period is divided into a plurality of continuous parts (time elements), and the current value and time of all or some of the parts can be arbitrarily set for each part.

  More specifically, a pair of electrodes coaxially arranged opposite to each other, an electrode moving mechanism that moves both electrodes relative to each other in the axial direction to move them closer to each other, and a welding current is passed between the electrodes. An inverter type DC energization circuit and a control device are provided, and the electrode moving mechanism and the inverter type DC energization circuit are operated under the control of the control device, so that the overlapped portion of the material to be welded is sandwiched between both electrodes and pressurized. In an inverter type direct current resistance spot welding machine that conducts welding by applying welding current to both electrodes, the control device divides the total energization period per spot welding into a plurality of continuous parts (time elements). A rewritable welding condition storage unit that stores the current value and time of each part, and a welding condition input operation for arbitrarily setting and changing the current value and time of all or part of each part. And storing the current value and time of each part input using the welding condition input operation unit in the welding condition storage unit and the current value and time of each part stored in the welding condition storage unit Based on the above, the electrode moving mechanism and the inverter type DC energization circuit are operated.

  It is desirable that the welding condition storage unit divides the total energization period per spot welding into at least three parts and stores the current value and time of each part.

  The inverter type DC resistance spot welding machine of the present invention divides the total energization period per spot welding into a plurality of continuous parts, and the current value and time of each part can be arbitrarily set. High quality welding can be performed by creating a welding current waveform most suitable for the material and shape of the weldment.

  Embodiments of the present invention will be described below.

  FIG. 1 is a block diagram showing a configuration of an inverter type DC resistance spot welder (hereinafter simply referred to as a spot welder) according to the present invention.

  The spot welder 100 includes a handheld welding gun 110 and a welder main body 120. The handheld welding gun 110 and the welding machine main body 120 are connected to each other by a signal line, a power cable, and a pneumatic supply tube (not shown).

  The welding gun 110 includes a pair of electrodes 111A and 111B that are coaxially opposed to each other, an air cylinder 112 that moves the electrodes 111A and 111B relative to each other in the axial direction, and moves them toward and away from each other. 111A and a gun arm 113 holding an air cylinder 112. The other electrode 111B is held by the piston rod 112a of the air cylinder 112. A handheld grip 114 is fixed to the gun arm 113, and a remote switch 115 is provided on the grip 114.

  The welding machine main body 120 includes a control device (programmable controller) 130, an air cylinder driving device 140, and an inverter type DC energization circuit 150. In this example, the electrode moving mechanism in the claims is configured by an air cylinder 112 and an air cylinder driving device 140.

  The control device 130 includes a rewritable welding condition storage unit 131 that stores the current value and time of each part by dividing the total energization period per spot welding into at least three consecutive parts, and the current of each part. An operation panel 132 including a welding condition input operation unit 132A for arbitrarily setting / changing values (I1, I2, I3) and time (T1, T2, T3) and a welding condition input operation unit 132 are used for input. The current value and time of each part are stored in the welding condition storage unit 131, and the current value (I1, I2, I3) and time (T1, T2, T3) of each part stored in the welding condition storage unit 131 are stored. ) Based on the electrode moving mechanism (air cylinder 112, air cylinder driving device 140) and CPU (Central Processing Unit) 133 that operates the inverter type DC energization circuit 150. The welding condition storage unit 131 stores a plurality of types of welding conditions as will be described later.

  The air cylinder driving device 140 is configured to include an air compressor, an accumulator, various valve mechanisms, and the like, and supplies air pressurized to a predetermined pressure to the welding gun 110 through a pneumatic supply tube.

  The inverter type DC energization circuit 150 includes a rectifier circuit that converts alternating current from a three-phase commercial power source into direct current, an inverter that converts direct current into alternating current, a transformer that steps down the output of the inverter to a voltage suitable for spot welding, and the like. The DC power output from the transformer is supplied to the welding gun 110 through the power cable.

  The spot welder 100 can use not only the air pressurizing welding gun 110 illustrated in FIG. 1 but also a manual pressurizing welding gun (not shown) or a welding gun for single-sided welding. That is, instead of the welding gun 110, a manual pressurizing welding gun or a welding gun for single-sided welding can be attached as necessary. These welding guns are also provided with a remote switch.

  FIG. 2 is a plan view showing an example of the operation panel 132. The operation panel 132 is provided on the front surface of the upper end portion of the welding machine main body 120. The operation panel 132 includes a power lamp 161 that is turned on when the main power is turned on, an alarm button 162 that is pressed when an abnormality occurs such as when the welding operation is forcibly terminated, an alarm lamp 163 that is turned on when the alarm button 162 is pressed, Liquid crystal display for displaying first to third work mode selection buttons 163A to 163C for selecting work contents, the current state of the welding machine (normal / abnormal, work mode, etc.), welding condition selection / adjustment screen, etc. 164, a memory number (No.) selection button 165 for specifying (selecting) a desired welding condition from among a plurality of types of welding conditions stored in the welding condition storage unit 131, a caution note, and the like are displayed. A comment button 166 for causing the welding condition storage unit 131 to store (save) the set value, and a welding condition selection / adjustment screen. Cursor button 168 for moving the upper cursor, time adjustment dial 169 for adjusting (increasing / decreasing) the welding time of the part designated by the cursor, and adjusting (increasing / decreasing) the welding current value of the part designated by the cursor An output adjustment dial 170 is provided for this purpose.

  FIG. 3 is a table showing examples of welding conditions stored in the welding condition storage unit 131. As illustrated, the welding condition storage unit 131 stores a plurality of welding conditions. The welding conditions are classified into three groups (a) to (c) according to the work contents, and a series of memory numbers (No.) are assigned to each group. Group (a) is a welding condition group suitable for performing double-sided spot welding using an air pressure gun (welding gun 110 in FIG. 1). Group (b) is a group of welding conditions suitable for performing double-sided spot welding using a manual pressure gun. Group (c) is a welding condition group suitable for performing other welding such as single-sided welding or copper drawing welding. The group (a) corresponds to the first work mode selection button 163A, the group (b) corresponds to the second work mode selection button 163B, and the group (c) corresponds to the third work mode selection button 163B. . That is, when the first work mode selection button 163A is pressed, the welding conditions of the group (a) are pressed, and when the second work mode selection button 163B is pressed, the welding conditions of the group (b) are the third work mode selection buttons 163C. When is pressed, the welding conditions of group (c) are displayed on the liquid crystal display unit 164 as the contents of the welding condition selection / adjustment screen, respectively.

  Next, operation | movement of the spot welder 100 of this embodiment is demonstrated.

[Automatic double-side spot welding mode]
When performing double-sided spot welding using an air pressure gun, the operator presses the first work mode selection button 163A. The spot welder 100 enters the automatic double-sided spot welding mode, and the liquid crystal display unit 164 displays the welding condition (time (T1, T2, T3) of the first memory number (No. 1: plate thickness 0.8) of the group (a). ), Current values (I1, I2, I3)) are displayed. The values displayed as current values (I1, I2, I3) indicate what percentage of the maximum output. The operator confirms the plate pressure of the part to be welded and appropriately operates the memory number (No.) selection button 165 to select the memory number of the welding condition that matches the condition. If the contents of the displayed setting conditions are acceptable, the remote switch 115 of the welding gun 110 is operated to start welding.

  When the remote switch 115 is continuously pressed (ON) for a predetermined time (for example, 0.1 second) or longer, the spot welding machine 100 operates the electrode moving mechanism (the air cylinder 112, the air cylinder driving device 140), Pressurization of the workpiece W by both electrodes 111A and 111B is started, and after a predetermined time (for example, 2 seconds) after the start of pressurization, the inverter type DC energizing circuit 150 is operated to apply a weak current between the electrodes 111A and 111B. Check the conductivity. As a result, if conduction is confirmed for 0.5 seconds, a welding current is passed according to the selected welding conditions. However, if the pressing of the remote switch 115 is released (OFF) before the continuity confirmation for 0.5 seconds is taken and the non-pressed state continues for a predetermined time (0.1 seconds) or longer, the continuity check energization and Stop pressurizing immediately.

  As illustrated in FIG. 3, the welding current is energized in four consecutive steps following the energization for continuity check. After the energization is stopped, the pressurization is released (OFF) after a predetermined time (for example, 2 seconds) elapses for cooling. Even after the continuity check (that is, after the time T0 has elapsed), the welding current continues to be energized even after the remote switch 115 is released (OFF). After the energization is stopped and the cooling time has passed, The state is rechecked, and if the pressing of the remote switch 115 is released (OFF), the welding operation is terminated.

  Of the above four steps, the first step (time T0, current I0) is a step provided for gently starting energization of the welding current. During this step, the welding current I0 increases slowly from 0 to I1. The three steps from the second step to the fourth step correspond to the three parts of the selected welding conditions. That is, the welding time and welding current value in the second step are T1 and I1, respectively, the welding time and welding current value in the third step are T2 and I2, respectively, and the welding time and welding current in the fourth step. The values are T3 and I3, respectively.

  According to this spot welder 100, after setting the spot welder 110 to the automatic double-side spot welding mode, selecting the memory number of the welding condition that matches the condition, and then pressing the remote switch 115 of the welding gun 110, Pressurization and double-sided spot welding of the workpiece W are performed according to the selected optimum welding conditions, and after the end of welding, the pressurization is automatically released.

  When changing the welding condition, the welding condition of the memory number to be changed is displayed on the liquid crystal display unit 164, and in that state, the cursor button 168 is operated to specify the part to be changed, and then the time adjustment dial 169 and the output adjustment dial By appropriately operating 170, the welding time and welding current value of the designated part can be adjusted as appropriate. Then, by pressing the save button 167, the changed welding conditions can be saved.

  In this way, the total energization period after soft start per double-sided spot welding is divided into three consecutive parts, and the current value (I1, I2, I3) and time (T1, T2, T3) of each part. Can be arbitrarily set, so that a welding current waveform most suitable for the material and shape of the workpiece W can be created, and high-quality double-side spot welding can be performed.

[Manual double-side spot welding mode]
When performing double-sided spot welding using a manual pressure gun, the operator presses the second operation mode selection button 163B. The spot welder 100 enters the manual double-sided spot welding mode, and the liquid crystal display unit 164 displays the welding condition (time (T1, T2, T3) of the top memory number (No. 1: plate thickness 0.8) of the group (b). ), Current values (I1, I2, I3)) are displayed. The operator confirms the plate pressure of the part to be welded, and appropriately operates the memory number (No.) selection button 165 to select the memory number of the welding condition that matches the condition. And if the content of the displayed setting conditions is acceptable, the location to be welded is pressurized with a manual pressure gun and the remote switch is pressed.

  When the remote switch of the manual pressurizing gun is continuously pressed (ON) for a predetermined time (for example, 0.1 second) or longer, the spot welder 100 operates the inverter type DC energization circuit 150 to cause the electrodes 111A and 111B to operate. Conduct a conductivity check by passing a weak current in between. As a result, if conduction is confirmed for 0.5 seconds, a welding current is passed according to the selected welding conditions. However, if the remote switch is released (OFF) before the continuity check for 0.5 seconds is taken, and the non-pressed state continues for a predetermined time (0.1 seconds), the continuity check is immediately energized. To cancel.

  As in FIG. 3, the welding current is energized in four consecutive steps following energization for continuity check. After the energization is stopped, the pressurization is released (OFF) after a predetermined time (for example, 2 seconds) elapses for cooling. In addition, even after the continuity check (that is, after T0 has elapsed), the welding current continues to be applied even if the remote switch is released (OFF). Is rechecked, and if the pressing of the remote switch 115 is released (OFF), the welding operation is terminated.

  According to the spot welder 100, after the spot welder 110 is set to the manual double-sided spot welding mode and a welding condition suitable for the condition is selected, it is selected only by pressing the remote switch of the manual pressure gun. Further, pressurization and double-sided spot welding of the workpiece W are performed according to the optimum welding conditions.

  When changing the welding condition, the welding condition of the memory number to be changed is displayed on the liquid crystal display unit 164, and in that state, the cursor button 168 is operated to specify the part to be changed, and then the time adjustment dial 169 and the output adjustment dial By appropriately operating 170, the welding time and welding current value of the designated part can be adjusted as appropriate. Then, by pressing the save button 167, the changed welding conditions can be saved.

  In this way, the total energization period after soft start per double-sided spot welding is divided into three consecutive parts, and the current value (I1, I2, I3) and time (T1, T2, T3) of each part. Can be arbitrarily set, so that a welding current waveform most suitable for the material and shape of the workpiece W can be created, and high-quality double-side spot welding can be performed.

[Single-side spot welding mode]
When performing single-side spot welding or copper drawing welding, the operator presses the third operation mode selection button 163C. The spot welder 100 is in a single-sided spot welding mode, and the liquid crystal display unit 164 displays the welding conditions (time (T1, T2, T3), current value of the top memory number (No. 1: single-sided spot) of group (c). (I1, I2, I3)) is displayed. The operator confirms the plate pressure of the part to be welded and appropriately operates the memory number (No.) selection button 165 to select the memory number of the welding condition that matches the condition. Then, if the contents of the displayed set conditions are acceptable, the ground plate is attached to the body side and welding is started by applying a single-sided spot tip to the place to be welded.

  When the welding gun remote switch is continuously pressed (ON) for a predetermined time (for example, 0.1 second) or longer, the spot welder 100 activates the inverter type DC energization circuit 150 and weakens it between the electrodes 111A and 111B. Conduct current check by applying current. As a result, if conduction is confirmed for 0.5 seconds, a welding current is passed according to the selected welding conditions. However, if the remote switch is released (OFF) before continuity is confirmed for 0.5 seconds and is not pressed for more than the specified time (0.1 seconds), the continuity check is turned on and off. Stop the pressure immediately.

  As in FIG. 3, the welding current is energized in four consecutive steps following energization for continuity check.

  According to this spot welder 100, after setting the spot welder 110 to the single-side spot welding mode and selecting a welding condition suitable for the conditions, the single-side spot tip is brought into contact with the place to be welded and the remote switch is pressed. As a result, single-side spot welding or copper drawing welding of the workpiece W is performed according to the selected optimum welding conditions.

  When changing the welding condition, the welding condition of the memory number to be changed is displayed on the liquid crystal display unit 164, and in that state, the cursor button 168 is operated to specify the part to be changed, and then the time adjustment dial 169 and the output adjustment dial By appropriately operating 170, the welding time and welding current value of the designated part can be adjusted as appropriate. Then, by pressing the save button 167, the changed welding conditions can be saved.

  In this way, the total energization period per one-side spot welding or copper drawing welding is divided into three consecutive parts, and the current value (I1, I2, I3) and time (T1, T2, T3) of each part. Since the welding current waveform most suitable for the material and shape of the workpiece W can be created, high-quality one-side spot welding or copper drawing welding can be performed.

  In the above embodiment, the total energization period after the soft start per spot welding is divided into three consecutive parts, and the current value (I1, I2, I3) and time (T1, T2, The case where T3) can be set arbitrarily has been described, but the total energization period after soft start is divided into four or more parts, and the current values of each part (I1, I2, I3, I4, ...) And time (T1, T2, T3, T4,...) May be arbitrarily set.

The block diagram which shows the structure of the inverter type DC resistance spot welding machine concerning this invention. The top view which shows the example of the form of the operation panel of the inverter type DC resistance spot welder concerning this invention. Explanatory drawing which displayed the example of the welding conditions memorize | stored in the welding condition memory | storage part of the inverter type DC resistance spot welding machine concerning this invention. The timing diagram which illustrated the operation timing and welding current waveform of the inverter type direct current resistance spot welding machine concerning the present invention.

Explanation of symbols

100 Inverter Type DC Resistance Spot Welder 110 Welding Gun 111A, 111B Electrode 112 Air Cylinder (Electrode Movement Mechanism)
DESCRIPTION OF SYMBOLS 120 Welding machine main body 130 Control apparatus 131 Welding condition memory | storage part 132 Operation panel 132A Welding contact condition input operation part 133 CPU
140 Air cylinder drive device (electrode movement mechanism)
150 Inverter type DC energization circuit 163A to 163C Work mode selection button 164 Liquid crystal display unit 165 Memory number selection button 167 Save button 168 Cursor button 169 Time adjustment dial 170 Output adjustment dial W Workpiece

Claims (3)

In the inverter type DC resistance spot welding machine that conducts welding by energizing the welding current while applying pressure to the overlapped part of the workpieces,
Inverter type DC, characterized in that the total energization period per spot welding is divided into a plurality of continuous parts, and the current value and time of all or some of the parts can be set arbitrarily for each part. Resistance spot welder. A pair of electrodes coaxially arranged opposite to each other, an electrode moving mechanism that moves both electrodes relative to each other in the axial direction to approach or separate each other, and an inverter type DC energization circuit that energizes a welding current between both electrodes And a control device,
An inverter that performs welding by energizing both electrodes with welding current while pressing the overlapped part of the material to be welded between both electrodes by operating the electrode moving mechanism and inverter type DC energization circuit under the control of the control device In type DC resistance spot welding machine,
The control device
A rewritable welding condition storage unit that stores the current value and time of each part by dividing the total energization period per spot welding into a plurality of continuous parts,
A welding condition input operation unit for arbitrarily setting / changing the current value and time of all or some parts for each part,
The current value and time of each part input using the welding condition input operation unit are stored in the welding condition storage unit, and the electrodes are moved based on the current value and time of each part stored in the welding condition storage unit. An inverter type DC resistance spot welding machine characterized by operating a mechanism and an inverter type DC energization circuit.   The inverter type direct current resistance spot welder according to claim 2, wherein the welding condition storage unit divides the total energization period per spot welding into at least three parts and stores the current value and time of each part.

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