JP2011167716A - Resistance welding control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform resistance welding in such a manner that one welding condition is selected from among the plurality of welding conditions by the simple operation of one starting switch. <P>SOLUTION: There is provided a resistance welding control method for prestoring a first welding condition including a first welding current value Iw1 and a first welding time Tw1, and a second welding condition including a second welding current value Iw2 and a second welding time Tw2 into welding equipment, selecting one welding condition from among these welding conditions and performing resistance welding. In the method, an on period Th as a period in which a starting switch Sw is in an on state is measured, and when this on periods Th1 and Th2 are less than a reference time Tt, the first welding condition is selected and resistance welding is performed under the condition of the first welding current value Iw1 and the first welding time Tw1, and when the on periods Th3 and Th4 are a reference time Tt or more, the second welding condition is selected, and the resistance welding is performed under the condition of the second welding current value Iw2 and the second welding time Tw2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a resistance welding control method for performing resistance welding by selecting one from a plurality of welding conditions stored in advance.

  In resistance welding, welding is performed by pressing and energizing a plurality of workpieces with a pair of electrodes. As welding conditions at this time, there are a welding current value, a welding time, a pressing force, and the like. These welding conditions are set to appropriate values according to the welded material conditions such as the material to be welded, the plate thickness, the number of stacked sheets, and welding is performed. In the stationary resistance welding apparatus, an operator sets these welding conditions, sets a material to be welded, and turns on a start switch to perform resistance welding. In a stationary resistance welding apparatus, the applied pressure is often performed by adjusting the pressure of air. For this reason, welding is performed with the applied pressure remaining at a constant value when the welded material condition changes within a predetermined range without finely changing the applied pressure for each welded material condition. Therefore, the main welding conditions in resistance welding are the above-described welding current value and welding time. Further, as the start switch, a foot switch, a push button switch, a photoelectric proximity switch, or the like is used. In particular, since the material to be welded is often set with both hands, a foot switch is often used. The photoelectric proximity switch generates a start switch signal by manually blocking between the light projecting unit and the light receiving unit.

  In many cases, the resistance welding apparatus is provided with a memory function for presetting and storing a plurality of welding conditions using the welding current value, the welding time, and the like as parameters. In this memory function, for example, the first welding current value and the first welding time are stored as one set as the first welding condition, and the second welding current value and the second welding time are stored as one set as the second welding condition. ing. Here, it is assumed that a part to be welded under the first welding condition and a part to be welded under the second welding condition are mixed as the material to be welded. In such a case, the operator calls the first welding condition from the memory function before welding the first welding point, turns on the start switch, and performs welding under the first welding condition. Next, the operator calls the second welding condition before welding the second welding point, turns on the start switch, and performs welding under the second welding condition. For the third and subsequent welding locations, welding is performed by calling the welding conditions corresponding to the respective locations. The same applies to the case of producing a small variety of products with different welding conditions. Thus, it is a common case to perform welding while switching between two welding conditions.

  As described above, performing welding while frequently calling and switching the two welding conditions on the panel of the resistance welding apparatus is complicated and the work efficiency is poor. Therefore, conventionally, when two start switches are connected to the resistance welding apparatus and the first start switch is turned on, the first welding condition is automatically called and welding is performed, and the second start switch is turned on. Then, the second welding condition is automatically called to perform welding. This multiple activation switch system improves the complexity of switching welding conditions. However, since an operator often performs welding while setting a material to be welded with both hands, a foot switch is often used as a start switch. In this case, it is not easy to perform welding by switching the first foot switch and the second foot switch for each welding point. Furthermore, there is also a problem that poor welding is likely to occur due to a stepping error.

  Patent Document 1 discloses a technique for arc welding, but discloses control for switching welding conditions only by operating a start switch. In the technique described in Patent Document 1, “a torch switch provided in a welding torch in a welding condition selection control method for performing welding by selecting one of a plurality of welding conditions stored in advance in a welding power source ( When the start switch) is double-clicked, the welding power source is shifted to the welding condition selection mode. During this welding condition selection mode, one of the plurality of welding conditions is selected by operating the torch switch, and the welding condition is selected. When the torch switch is double-clicked during the selection mode, the welding power source is shifted to the welding mode, and welding is performed under the selected welding conditions by the operation of the torch switch. In this technique, welding can be performed by calling a plurality of welding conditions with one start switch, for example, a foot switch. However, since the operation of the start switch is complicated, it takes time to switch the welding conditions. Furthermore, operability is poor when a foot switch is double-clicked.

JP 2007-38290 A

  When resistance welding is performed while frequently switching between the first welding condition and the second welding condition, as described above, it is not easy to perform welding by switching the first foot switch and the second foot switch. . Furthermore, poor welding is likely to occur due to a mistake in stepping.

  Further, in the method of selecting the welding condition by shifting to the welding condition selection mode by double-clicking a start switch such as a foot switch, the operation of the start switch is complicated, so that it takes time to switch the welding condition. Furthermore, operability is poor when a foot switch is double-clicked.

  Therefore, in the present invention, when resistance welding is performed by switching between the first welding condition and the second welding condition, one welding condition can be selected in a short time without switching errors by simply operating one start switch. An object of the present invention is to provide a resistance welding control method that can be performed.

In order to solve the above-mentioned problem, the invention of claim 1 includes a first welding condition including a first welding current value and a first welding time, and a second welding condition including a second welding current value and a second welding time. Is stored in advance in the welding apparatus, and one of these welding conditions is selected and resistance welding is performed for resistance welding.
Measure the on period, which is the period when the start switch is on,
When the ON period is less than the reference time, the first welding condition is selected, resistance welding is performed under the conditions of the first welding current value and the first welding time,
When the ON period is equal to or longer than the reference time, the second welding condition is selected, and resistance welding is performed under the condition of the second welding current value and the second welding time.
This is a resistance welding control method.

In the invention of claim 2, the first welding condition further includes a first welding number and a first starting cycle, and the second welding condition further includes a second welding number and a second starting cycle,
When the ON period is less than the reference time, the first welding condition is selected, and the first welding current value and the first welding time condition until the first welding frequency is reached for each first start cycle. Repeatedly, resistance welding is performed,
When the ON period is equal to or longer than the reference time, the second welding condition is selected, and the second welding current value and the second welding time condition until the second welding frequency is reached for each second start cycle. Repeatedly, resistance welding is performed.
The resistance welding control method according to claim 1, wherein:

  According to the first aspect of the invention, the first welding condition is selected when the length of the period during which the start switch is on is less than the reference time, and the second welding condition is selected when the length of the start switch is longer than the reference time. Selected. For this reason, it is possible to select one welding condition in a short time and without switching errors by simply operating one start switch.

  According to the invention of the second aspect, in addition to the effect of the invention of the first aspect, in the case of performing resistance welding a plurality of times continuously in the first welding condition and the second welding condition, respectively, On the other hand, resistance welding can be performed continuously by the set number of weldings only by turning on the start switch once. For this reason, the operability of the start switch is further improved, and the productivity is improved.

It is a block diagram of the welding apparatus for enforcing the resistance welding control method which concerns on Embodiment 1 of this invention. It is a timing chart of each signal in the welding apparatus of FIG. It is a block diagram of the welding apparatus for enforcing the resistance welding control method which concerns on Embodiment 2 of this invention. It is a timing chart of each signal in the welding apparatus of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
FIG. 1 is a block diagram of a welding apparatus for carrying out a resistance welding control method according to Embodiment 1 of the present invention. This figure shows the case of an inverter control type resistance welding apparatus, and the welding current Iw is a direct current. Hereinafter, each block will be described with reference to FIG.

  The inverter circuit INV receives the commercial AC power supply AC, performs inverter control according to a drive signal Dv described later, and outputs high-frequency AC. Although not shown, the inverter circuit INV includes a primary rectifier circuit that rectifies the commercial AC power supply AC, a smoothing capacitor that smoothes the rectified direct current, and a plurality of switching elements that convert the smoothed direct current into high-frequency alternating current. Consists of a bridge circuit. The high frequency transformer TR steps down the high frequency alternating current to a voltage value suitable for resistance welding. The secondary rectifier circuit DR rectifies the stepped-down high-frequency alternating current into direct current. The pair of electrodes 1a and 1b pressurize a plurality of materials to be welded 2, and a welding current Iw is passed through the electrodes and a welding voltage Vw is applied.

  The start switch SW outputs a start switch signal Sw that is at a high level when in an on state (closed state) and at a low level when in an off state (open state). As described above, the start switch SW corresponds to a foot switch, a push button switch, a photoelectric proximity switch, or the like. The welding condition selection circuit WS receives the start switch signal Sw, selects one from the first welding condition and the second welding condition stored in advance, and receives a welding current setting signal Ir and a start signal On corresponding thereto. Output. Here, the first welding condition is formed from the first welding current value Iw1 and the first welding time Tw1, and the second welding condition is formed from the second welding current value Iw2 and the second welding time Tw2. . In the above-described welding condition selection circuit WS, selection of the welding conditions is performed as follows. The period (on period) during which the start switch signal Sw is at a high level is measured. When the on period is less than the reference time, the first welding condition is selected, and the value of the welding current setting signal Ir is the first welding current. The value Iw1 is set, and the activation signal On is at a high level only during the first welding time Tw1. When the ON period is equal to or longer than the reference time, the second welding condition is selected, the value of the welding current setting signal Ir becomes the second welding current value Iw2, and the activation signal On is set to the high level only for the second welding time Tw2. Become.

  The current detection circuit ID detects the welding current Iw and outputs a current detection signal Id. The current error amplification circuit EI amplifies an error between the welding current setting signal Ir and the current detection signal Id, and outputs a current error amplification signal Ei. The drive circuit DV receives the current error amplification signal Ei and the activation signal On, and performs pulse width modulation control based on the current error amplification signal Ei while the activation signal On is at a high level. A drive signal Dv for driving the circuit INV is output.

  FIG. 2 is a timing chart of each signal in the welding apparatus of FIG. FIG. 4A shows the start switch signal Sw, FIG. 4B shows the welding current setting signal Ir, FIG. 4C shows the start signal On, and FIG. 4D shows the welding current Iw. . Hereinafter, each signal will be described with reference to FIG.

  As shown in FIG. 6A, when the start switch SW is turned on at time t10, the start switch signal Sw becomes High level. At time t11, when the start switch SW is turned off, the start switch signal Sw becomes low level. A period (time t10 to t11) in which the activation switch signal Sw is at the high level is an on period Th1. As shown in the figure, the period of time t10 to t12 is a predetermined reference time Tt. Here, since the ON period Th1 is less than the reference time Tt, the first welding condition is selected. Therefore, as shown in FIG. 5B, the welding current setting signal Ir changes from 0 to the first welding current value Iw1 at time t12 and maintains that value. Further, as shown in FIG. 5C, the activation signal On becomes a high level at time t12, and becomes a low level at time t13 after the first welding time Tw1 has elapsed. The period from time t12 to t13 is the first welding time Tw1. The timing when the activation signal On becomes the High level is the time t12 because the welding condition is selected when the reference time Tt has elapsed. As a result, as shown in FIG. 4D, resistance welding is performed by applying the welding current Iw between times t12 and t13. The value of the welding current Iw at this time is the first welding current value Iw1.

  The next ON period Th2 is also less than the reference time Tt. As shown in FIG. 5A, when the start switch SW is turned on at time t20, the start switch signal Sw becomes High level. At time t21, when the start switch SW is turned off, the start switch signal Sw becomes low level. The period (time t20 to t21) during which the start switch signal Sw is at the high level is the on period Th2. As shown in the figure, the period from time t20 to t22 is the reference time Tt. Here, since the ON period Th2 is less than the reference time Tt, the first welding condition is selected again. Therefore, as shown in FIG. 5B, the welding current setting signal Ir remains at the first welding current value Iw1 even after time t22. In addition, as shown in FIG. 5C, the activation signal On becomes the High level at time t22, and becomes the Low level at time t23 after the first welding time Tw1 has elapsed. The period from time t22 to t23 is the first welding time Tw1. As a result, as shown in FIG. 4D, during the time t22 to t23, the welding current Iw is applied and resistance welding is performed. The value of the welding current Iw at this time is the first welding current value Iw1.

  The next ON period Th3 is the case where the reference time Tt or longer. As shown in FIG. 5A, when the start switch SW is turned on at time t30, the start switch signal Sw becomes High level. When the reference time Tt elapses at time t31 and the start switch SW is turned off at time t32 after that, the start switch signal Sw becomes Low level. The period (time t30 to t32) during which the start switch signal Sw is at the high level is the on period Th3. As shown in the figure, the period from time t30 to t31 is the reference time Tt. Here, since the on period Th3 is equal to or longer than the reference time Tt, the second welding condition is selected. Therefore, as shown in FIG. 5B, the welding current setting signal Ir changes from the first welding current value Iw1 to the second welding current value Iw2 at time t31 and maintains that value. Further, as shown in FIG. 5C, the activation signal On becomes the High level at the time t31, and becomes the Low level at the time t33 after the second welding time Tw2 elapses. The period from time t31 to t33 is the second welding time Tw2. As a result, as shown in FIG. 4D, during the time t31 to t33, the welding current Iw is applied and resistance welding is performed. The value of the welding current Iw at this time is the second welding current value Iw2.

  The next on-period Th4 is also equal to or longer than the reference time Tt. As shown in FIG. 5A, when the start switch SW is turned on at time t40, the start switch signal Sw becomes High level. When the reference time Tt elapses at time t41, and the start switch SW is turned off at time t42 thereafter, the start switch signal Sw becomes low level. The period (time t40 to t42) during which the start switch signal Sw is at the high level is the on period Th4. As shown in the figure, the period from time t40 to t41 is the reference time Tt. Here, since the on period Th4 is equal to or longer than the reference time Tt, the second welding condition is selected again. Therefore, as shown in FIG. 5B, the welding current setting signal Ir remains at the second welding current value Iw2 even after time t41. Further, as shown in FIG. 5C, the activation signal On becomes the High level at time t41, and becomes the Low level at time t43 after the second welding time Tw2 has elapsed. The period from time t41 to t43 is the second welding time Tw2. As a result, as shown in FIG. 4D, during the time t41 to t43, the welding current Iw is applied and resistance welding is performed. The value of the welding current Iw at this time is the second welding current value Iw2.

  The reference time Tt is set to an appropriate value according to the type of start switch, the content of welding work, and the like. For example, the reference time Tt is set to about 0.5 to 1.0 seconds.

  According to the first embodiment described above, the first welding condition is selected when the length of the period during which the start switch is turned on is less than the reference time, and the second welding condition is selected when the length is longer than the reference time. Selected. For this reason, it is possible to select one welding condition in a short time and without switching errors by simply operating one start switch.

[Embodiment 2]
In the second embodiment, when the resistance welding is continuously performed a plurality of times under the first welding condition and then the welding is performed a plurality of times continuously under the second welding condition, the operation of the start switch is performed more than in the first embodiment. It is for further simplicity. For this reason, in the second embodiment, the number of times of welding Nw and the start cycle Tc are added to the welding current value Iw and the welding time Tw in the first embodiment as parameters for forming the welding conditions. That is, the first welding condition is formed from the first welding current value Iw1, the first welding time Tw1, the first number of welding times Nw1, and the first start cycle Tc1. The second welding condition is formed from the second welding current value Iw2, the second welding time Tw2, the second number of times of welding Nw2, and the second starting cycle Tc2. Tw1 <Tc1 and Tw2 <Tc2. Here, for example, it is assumed that Nw1 = 5 and Nw2 = 7. When the first welding condition is selected, the resistance welding for the first welding number Nw1 = 5 is automatically performed every first activation cycle Tc1 by turning on the activation switch once. The welding current at this time is the first welding current value Iw1, and the welding time is the first welding time Tw1. When the second welding condition is selected, resistance welding for the second number of times of welding Nw2 = 7 is automatically performed every second activation period Tc2 only by turning on the activation switch once. The welding current at this time is the second welding current value Iw2, and the welding time is the second welding time Tw2. However, the workpiece is set manually by the operator. Hereinafter, the second embodiment will be described in detail.

  FIG. 3 is a block diagram of a welding apparatus for carrying out the resistance welding control method according to Embodiment 2 of the present invention. This figure corresponds to FIG. 1 described above, and the same reference numerals are given to the same blocks, and their explanations are omitted. In this figure, the welding condition selection circuit WS of FIG. 1 is replaced with a welding condition selection circuit WS2. Hereinafter, this block will be described with reference to FIG.

  The welding condition selection circuit WS2 receives the start switch signal Sw, selects one from the first and second welding conditions stored in advance, and outputs a corresponding welding current setting signal Ir and start signal On. To do. As described above, the first welding condition is formed from the first welding current value Iw1, the first welding time Tw1, the first number of welding times Nw1, and the first starting cycle Tc1. The second welding condition is formed from the second welding current value Iw2, the second welding time Tw2, the second number of welding times Nw2, and the second starting cycle Tc2. In the above welding condition selection circuit WS2, the selection of the welding conditions is performed as follows. The period (on period) during which the start switch signal Sw is at a high level is measured. When the on period is less than the reference time, the first welding condition is selected, and the value of the welding current setting signal Ir is the first welding current. The activation signal On becomes the High level only during the first welding time Tw1 until resistance welding is performed until the value Iw1 is reached and the first number of welding times Nw1 is reached every first activation cycle Tc1. When the ON period is equal to or longer than the reference time, the second welding condition is selected, and the value of the welding current setting signal Ir becomes the second welding current value Iw2, until the second number of welding times Nw2 is reached at every second starting cycle Tc2. The activation signal On becomes High level only during the second welding time Tw2, and resistance welding is performed.

  FIG. 4 is a timing chart of each signal in the welding apparatus of FIG. FIG. 4A shows the start switch signal Sw, FIG. 4B shows the welding current setting signal Ir, FIG. 4C shows the start signal On, and FIG. 4D shows the welding current Iw. . This figure exemplifies a case where both the first welding number Nw1 and the second welding number Nw2 are two. Hereinafter, each signal will be described with reference to FIG.

  As shown in FIG. 6A, when the start switch SW is turned on at time t10, the start switch signal Sw becomes High level. At time t11, when the start switch SW is turned off, the start switch signal Sw becomes low level. A period (time t10 to t11) in which the activation switch signal Sw is at the high level is an on period Th1. As shown in the figure, the period of time t10 to t12 is a predetermined reference time Tt. Here, since the ON period Th1 is less than the reference time Tt, the first welding condition is selected. Therefore, as shown in FIG. 5B, the welding current setting signal Ir changes from 0 to the first welding current value Iw1 at time t12 and maintains that value. Further, as shown in FIG. 5C, the start signal On becomes the first High level in response to one change of the start switch signal Sw at time t12, and after the first welding time Tw1 has elapsed. It becomes Low level at time t13. Further, the activation signal On becomes the second High level in response to one change of the activation switch signal Sw at time t14 when the first activation period Tc1 has elapsed from time t12, and after the first welding time Tw1 has elapsed. At time t15. As a result, as shown in FIG. 4D, the welding current Iw is energized twice in the period from time t12 to t13 and in the period from time t14 to t15, and resistance welding is performed. The value of the welding current Iw at this time is the first welding current value Iw1. The length of the period from time t12 to t13 and the period from time t14 to t15 is the first welding time Tw1. Here, when the first welding number Nw1 = 5, the start signal On changes to the high level five times in response to one change of the start switch signal Sw, and five resistance weldings are performed. Will be done.

  The next on-period Th2 is the case where the reference time Tt or longer. As shown in FIG. 5A, when the start switch SW is turned on at time t20, the start switch signal Sw becomes High level. When the reference time Tt elapses at time t21 and the start switch SW is turned off at time t22 after that, the start switch signal Sw becomes Low level. A period (time t20 to t22) in which the activation switch signal Sw is at the high level is an on period Th2. As shown in the figure, the period from time t20 to t21 is the reference time Tt. Here, since the ON period Th2 is equal to or longer than the reference time Tt, the second welding condition is selected. Therefore, as shown in FIG. 5B, the welding current setting signal Ir changes from the first welding current value Iw1 to the second welding current value Iw2 at time t21 and maintains that value. Further, as shown in FIG. 5C, the activation signal On becomes the first High level at time t21 in response to one change of the activation switch signal Sw, and after the second welding time Tw2 has elapsed. It becomes Low level at time t23. Further, the activation signal On becomes the second High level in response to one change of the activation switch signal Sw at time t24 when the second activation cycle Tc2 has elapsed from time t21, and after the second welding time Tw2 has elapsed. At time t25. As a result, as shown in FIG. 4D, the welding current Iw is energized twice in the period from time t21 to t23 and in the period from time t24 to t25, and resistance welding is performed. The value of the welding current Iw at this time is the second welding current value Iw2. The lengths of the period from time t21 to t23 and the period from time t24 to t25 are the second welding time Tw2. Here, when the second number of times of welding Nw2 = 7, the change of the start signal On to the high level is performed 7 times in response to one change of the start switch signal Sw, and 7 resistance weldings are performed. Will be done.

  According to the second embodiment described above, in addition to the effects of the first embodiment, in the case of performing resistance welding a plurality of times continuously under the first welding condition and the second welding condition, for one welding condition, By simply turning on the start switch once, resistance welding can be performed continuously for the set number of times of welding. For this reason, the operability of the start switch is further improved, and the productivity is improved.

  In the above-described embodiment, a pressing force may be further added as a parameter for forming the welding condition. Moreover, although the case of the inverter control type welding apparatus was illustrated in the above-described embodiment, the same applies to the case of the thyristor phase control type AC resistance welding apparatus.

1a, 1b Electrode 2 Material to be welded DR Secondary rectifier circuit DV Drive circuit Dv Drive signal EI Current error amplification circuit Ei Current error amplification signal ID Current detection circuit Id Current detection signal INV Inverter circuit Ir Welding current setting signal Iw Welding current Iw1 1 welding current value Iw2 second welding current value Nw welding number Nw1 first welding number Nw2 second welding number On start signal SW start switch Sw start switch signal Tc start cycle Tc1 first start cycle Tc2 second start cycle Th1 to Th4 ON Period TR High-frequency transformer Tt Reference time Tw Welding time Tw1 First welding time Tw2 Second welding time Vw Welding voltage WS, WS2 Welding condition selection circuit

Claims (2)

The first welding condition including the first welding current value and the first welding time and the second welding condition including the second welding current value and the second welding time are stored in advance in the welding apparatus, and one of these welding conditions is selected. In the resistance welding control method of selecting one and performing resistance welding,
Measure the on period, which is the period when the start switch is on,
When the ON period is less than the reference time, the first welding condition is selected, resistance welding is performed under the conditions of the first welding current value and the first welding time,
When the ON period is equal to or longer than the reference time, the second welding condition is selected, and resistance welding is performed under the condition of the second welding current value and the second welding time.
The resistance welding control method characterized by the above-mentioned. The first welding condition further includes a first welding number and a first activation cycle, and the second welding condition further includes a second welding number and a second activation cycle,
When the ON period is less than the reference time, the first welding condition is selected, and the first welding current value and the first welding time condition until the first welding frequency is reached for each first start cycle. Repeatedly, resistance welding is performed,
When the ON period is equal to or longer than the reference time, the second welding condition is selected, and the second welding current value and the second welding time condition until the second welding frequency is reached for each second start cycle. Repeatedly, resistance welding is performed.
The resistance welding control method according to claim 1.

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