JP2002028790A - Resistance welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease defects of quality of welded products and to improve the yield of welding process. SOLUTION: In the resistance welding equipment 1, a control part 7 allows a first measurement current Ix, smaller than a welding current Iz necessary for the resistance welding, to be supplied to a member 2 to be welded and allows a voltage Vx between electrodes to be measured prior to the welding every time when a pair of members 2 to be welded combined in a state that the faces to be joined are in contact with each other are fitted to the electrodes 3A and 3B. A conduction resistance Rx of the whole members to be welded prior to the welding is derived on the basis of the measured voltage Vx and the first measurement current Ix, the resistance welding of members 2 to be welded is performed while controlling a welding power source 4 and a pressurizing source 5 in accordance with a regulated welding condition on the basis of the conduction resistance Rx before the welding. After performing, the controlling part 7 allows the second measurement current Iy smaller than the welding current Iz to be supplied to the welded members 2 and allows the voltage Vy between the electrodes to be measured, and the quality of the welded product is evaluated on the basis of the conductive resistance Ry of the whole welded members derived after the welding on the basis of the measured voltage Vy and the second measurement current Iy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding machine for mutually welding a plurality of workpieces using a resistance welding method.

[0002]

2. Description of the Related Art Resistance welding, which is one of the pressure welding methods, is a method of welding a plurality of workpieces formed of a metal material or the like by utilizing heat generated by the resistance of the workpieces themselves. In lap resistance welding, which is one method of resistance welding, the materials to be welded are sandwiched between a pair of electrodes while the surfaces to be welded are in contact with each other, and the materials to be welded are perpendicular to the surface to be welded. A current flowing perpendicularly to the surface to be joined is supplied from the welding power source to the workpiece through the electrode while pressing. As a result, Joule heat due to the resistance heat is generated in the material to be welded, and the Joule heat melts and diffuses the joint surface of the material to be welded, so that the materials to be welded are joined.

As shown in FIG. 6, a resistance welding machine for performing lap resistance welding employs a vertical pressurizing type in which the materials to be welded are pressed in a direction parallel to the gravity, as shown in FIG. There are a resistance welding machine and a right-and-left pressure type resistance welding machine that presses materials to be welded in a direction perpendicular to gravity as shown in FIG. As shown in FIG. 8, a resistance welding machine that performs lap resistance welding is a capacitor-type resistance welding machine that supplies a large current to the material to be welded in a pulsed form immediately after the current is applied, according to the method of applying electricity to the material to be welded. Welding machine, single-phase AC resistance welding machine that continues to supply current of one phase of three-phase AC current to workpiece after starting current supply, and inverter that supplies DC current within a predetermined period after starting current supply There is a resistance welding machine of the type. 2. Description of the Related Art In recent years, when a resistance welding machine is used for welding electronic components, an inverter-type resistance welding machine that has a flat and stable current change and that can perform fine control has been adopted.

Japanese Patent Application Laid-Open No. 8-109359 discloses a resistance melting method.
Metal body bonding method using spot welding which is one method of welding
Is disclosed. In the metal body bonding method, the volume resistivity is
10 ⁰Ω · cm-10^TenΩ · cm and thickness 5μ
m to 200 μm of conductive structural adhesive
Energizing between the two metal bodies while interposed between the bodies,
The structural adhesive is hardened by the heat generated by the metal body when energized
Let it. Japanese Patent Application Laid-Open No. Hei 7-284956 discloses a coated electric wire and the like.
A control device for resistance welding is disclosed. Said system
The control device is used to connect the insulated wire,
2 To sandwich the material to be welded and the conductive material during resistance welding
The amount of displacement of the two electrodes and the time
Has been measured. Until the amount of electrode displacement reaches a predetermined amount,
Depending on the result of comparison between the charging time and the predetermined target energizing time,
The welding current supplied to the pole is feedback-controlled.
Resistance welding method disclosed in JP-A-5-169272
Is caused by the expansion of the members to be joined in the non-molten state
Estimate the amount of deformation by extrapolation, and
Measure the amount of deformation and estimate the amount of deformation and the measured
Welding conditions, especially through
Electricity time is controlled.

In the pressure welding method disclosed in Japanese Patent Application Laid-Open No. Hei 5-57459, the relationship between a predetermined minimum energy required for pressure welding a workpiece to be welded and welding conditions is set in advance. The welding conditions include an energizing time, a welding voltage, and a welding current. Prior to the start of welding, the resistance between two electrodes sandwiching the material to be welded is measured, and the actual welding voltage between the electrodes is determined based on the relationship between the minimum energy and the measured resistance between the electrodes. , Energizing time and welding current are set. At the time of measuring the resistance between the electrodes while the workpiece is being clamped, the current flowing through the electrodes is measured under the condition that a predetermined voltage is applied between the electrodes, and the current between the electrodes is determined based on the measured current and the applied voltage. The resistance value is determined.

[0006]

In resistance welding, the energy Q for welding a material to be welded is, as shown in Equation 1, the square of the welding current Iz (t) and the total of a set of materials to be welded. It is represented by the time integral of the product with the conduction resistance Rx (t) before welding. Welding current Iz (t) and conduction resistance Rx (t)
Are variables each having time as a parameter. The conduction resistance Rx (t) of the entire set of materials to be welded before welding is the conduction resistance of the entire set of materials to be welded in a state where surfaces to be joined are brought into contact with each other and combined. And the state of the parts where the materials to be welded are in contact with each other. Q = ∫Iz (t) ² · Rx (t) dt (1)

The welding current Iz (t) and the time t can be reproduced with relatively high accuracy based on the control result of the welding power source. However, the conduction resistance Rx (t) of the entire material to be welded before welding greatly changes according to variations in the shape and characteristics of the material to be welded and variations in the pressing force Pz. For example, in a set of materials to be welded, at least one of a material of each material to be welded, such as specific resistance, a width of each material to be welded, and a thickness of each material to be welded is changed. Conduction resistance Rx of the entire set of materials to be welded before welding.
(T) changes. Further, for example, if the plurality of materials to be welded at the contact location are shifted from each other or a gap is formed at the contact location of the plurality of workpieces in accordance with the variation of the pressing force Pz, the shape and characteristics of the material to be welded change. However, the conduction resistance Rx (t) of the entire workpiece before welding increases.

If the conduction resistance Rx (t) of the entire set of materials to be welded before welding is extremely lower than the standard, the energy required for welding cannot be obtained at the contact point.
The strength of the welded part is likely to be insufficient. If the conduction resistance Rx (t) before welding is much higher than the standard, the energy generated at the contact location is much larger than the energy required for welding, so that spatter, a so-called explosion, occurs. As described above, the variation in the conduction resistance Rx (t) before welding may cause an increase in quality defects of one set of materials to be welded after welding is completed, that is, a possibility of deteriorating the yield of the resistance welding process. There is.

In particular, in a factory, a welding current Iz, a conduction time Wz, and a pressing force Pz, which are welding conditions for resistance welding, are set in advance in accordance with a conduction resistance Rx before welding which is predicted in advance. At the time of actual welding, set welding conditions selected according to the conduction resistance Rx before welding expected from the shape and material of the material to be welded are always used.
When mass-producing welding products of the same standard, for example, when performing resistance welding of a large number of sets of materials to be welded having the same expected conduction resistance Rx before welding, for each set of materials to be welded, Since the state such as the displacement or the state of the gap between the materials to be welded is different, there is a high possibility that the actual conduction resistance Rx varies for each set of the materials to be welded. In this case, if the set welding conditions selected according to the conduction resistance Rx before welding expected from the shape and the material are always used, the welding conditions cannot correspond to the actual variation in the conduction resistance Rx before welding. It becomes difficult to suppress poor welding and the occurrence of explosion.

[0010] JP-A-8-109359, JP-A-7-109
In the various resistance welding methods disclosed in Japanese Patent No. 284956 and Japanese Patent Application Laid-Open No. 5-169272, since the variation in the conduction resistance Rx before welding of the entire set of materials to be welded is not considered, the conduction resistance Rx It is difficult to suppress poor welding and explosion due to blasting. Further, in the pressure welding method disclosed in Japanese Patent Application Laid-Open No. 5-57459, since only the welding voltage, the welding current, and the conduction time are determined as the welding conditions, it is difficult to eliminate the displacement and the gap between the assembled workpieces.

It is an object of the present invention to provide an actual conduction resistance R before welding.
An object of the present invention is to provide a resistance welding machine capable of suppressing a welding defect or an explosion due to a variation in x.

[0012]

SUMMARY OF THE INVENTION According to the present invention, there is provided a resistance welding machine for welding a plurality of materials to be welded, wherein the materials to be welded are assembled in such a manner that surfaces to be joined are brought into contact with each other. A set of electrodes, a welding power source for supplying a current flowing perpendicularly to a surface to be joined of the workpieces to the combined set of workpieces via the electrodes, and a welding power source for joining the workpieces; A pressure source for applying a pressing force Pz acting perpendicularly to a power plane to a set of materials to be welded, a voltmeter for measuring a voltage between a pair of electrodes, a welding power source and a pressure source. Control means for controlling, each time an electrode is attached to a new material to be welded, before the execution of welding, the first measurement smaller than the welding current Iz required for resistance welding of one set of materials to be welded. An electric current Ix is supplied to a set of workpieces through electrodes. , A voltage Vx between the electrodes is measured by a voltmeter, and based on the measured voltage Vx and the first measured current Ix, the conduction resistance Rx of the entire combined workpiece before welding is determined. The welding conditions are adjusted based on the conduction resistance Rx before welding, and the resistance welding of the material to be welded is performed while controlling the welding power source and the pressure source based on the adjusted welding conditions. It is a resistance welding machine.

According to the present invention, in a resistance welding machine, prior to welding, the conduction resistance Rx before welding of a plurality of materials to be welded combined in a state where the surfaces to be joined are in contact with each other is determined. Resistance welding of the material to be welded is performed based on the welding conditions adjusted based on the conduction resistance Rx before the welding. If the voltage between the electrodes is measured while supplying a constant current to the material to be welded between a pair of electrodes, the conduction resistance of the entire combined material to be welded can be accurately calculated. Further, every time the material to be welded is attached to the electrode, that is, every time the material to be welded is replaced, the conduction resistance Rx before welding of the entire material to be welded is determined, and based on the conduction resistance Rx before welding. Resistance welding is performed in accordance with the adjusted welding conditions, so that occurrence of welding failure due to individual variations in the conduction resistance Rx before the welding is suppressed. As a result, the success rate of resistance welding is improved, so that it is possible to reduce the inconvenience of the welded product and to improve the yield of the welding process.

The resistance welding machine according to the present invention is characterized in that a predetermined initial welding condition and a continuity resistance Rx before welding obtained when welding is successful when resistance welding of a material to be welded is performed based on the initial welding condition. A management range, which is a range, further includes a storage unit that stores in advance the control unit calculates the conduction resistance Rx before welding and a predetermined management range every time the conduction resistance Rx before welding is calculated. In comparison, if the conduction resistance Rx before the welding is within the management range, the initial welding condition is adopted as the current welding condition.

According to the present invention, in the resistance welding machine, the resistance welding based on the initial welding conditions is performed only when the conduction resistance Rx of the entire material to be welded before welding is within a predetermined management range. This prevents the occurrence of poor welding caused by the conduction resistance Rx before welding. This also makes it possible to fine-tune the welding conditions manually or automatically in advance when resistance welding based on the preset initial welding conditions is expected to fail.

The resistance welding machine according to the present invention further includes a notifying unit for notifying, and each time the control unit calculates the conducting resistance Rx before the welding, the notifying unit reports the conducting resistance Rx before the welding. The feature is to inform.

According to the present invention, in the resistance welding machine, the conduction resistance Rx is notified each time the conduction resistance Rx before welding of the plurality of combined workpieces is obtained. This allows the operator of the resistance welding machine to recognize the conduction resistance Rx before welding of the entire workpiece to be welded every time welding is performed, so that the operator sets welding conditions in advance according to the conduction resistance Rx before welding. It becomes possible to adjust manually.

[0018] The resistance welding machine of the present invention provides an informing means for informing, and a continuity resistance Rx before welding when resistance welding of a material to be welded is successfully performed based on predetermined initial welding conditions. Storage means for storing in advance a management range, which is a range, wherein the control means calculates the conduction resistance Rx before welding each time the conduction resistance Rx before welding is calculated.
Is compared with a predetermined control range, and if the conduction resistance Rx before the welding is out of the control range, a warning is issued using a notification unit.

According to the present invention, in the resistance welding machine, a warning is issued if the conduction resistance Rx of all of the combined workpieces before welding is out of a predetermined management range. As a result, every time welding is performed, the operator of the resistance welding machine can reliably recognize whether or not the conduction resistance Rx of the entire workpiece to be welded is out of the management range. This makes it possible for the operator to manually fine-adjust the welding conditions in advance when resistance welding based on the preset initial welding conditions is expected to fail. Becomes easier.

[0020] In the resistance welding machine according to the present invention, the control means may include:
Each time the conduction resistance Rx before welding is calculated, the welding condition is automatically adjusted based on the conduction resistance Rx before welding.

According to the present invention, in the resistance welding machine, the welding conditions based on the conduction resistance Rx of the entire assembled workpiece before welding are automatically adjusted, and the resistance welding is performed based on the welding conditions. . This further facilitates control of the resistance welder.

[0022] In the resistance welding machine of the present invention, the welding conditions may be as follows:
Including the magnitude of the welding current Iz, the welding current Iz is adjusted so as to decrease as the conduction resistance Rx before the welding increases.

According to the present invention, in the resistance welding machine, each time welding is performed, the conduction resistance R before welding obtained before execution is determined.
The welding current Iz is adjusted according to x. Welding current Iz
Is easily controlled automatically by the control means, so that the welding condition adjustment based on the conduction resistance Rx before welding can be easily automated.

[0024] In the resistance welding machine of the present invention, the welding conditions may be as follows:
The method is characterized in that it includes the conduction time Wz of the welding current Iz, and is adjusted such that the conduction time Rz becomes shorter as the conduction resistance Rx before the welding becomes larger.

According to the present invention, in the resistance welding machine, each time welding is performed, the conduction resistance R before welding determined before execution is determined.
The energization time Wz of the welding current Iz is adjusted according to x. Since the power supply time Wz is easily controlled automatically by the control means, it is easy to automate the welding condition adjustment based on the conduction resistance Rx before welding.

[0026] In the resistance welding machine of the present invention, the welding conditions may be as follows:
Including the magnitude of the pressing force Pz, the conduction resistance Rx before the welding
It is characterized in that the pressure Pz is adjusted so as to increase as the value of.

According to the present invention, in the resistance welding machine, the pressure Pz applied to the material to be welded is adjusted each time welding is performed in accordance with the conduction resistance Rx before welding, which is obtained before execution. Fine adjustment of the pressing force Pz is most effective because the cause of the variation in the conduction resistance Rx before welding is basically eliminated.

[0028] In the resistance welding machine according to the present invention, the welding conditions include:
It includes at least two parameters among the magnitude of the welding current Iz, the energization time Wz of the welding current Iz, and the magnitude of the pressing force Pz, and includes the conduction resistance Rx before the welding.
Is larger, the welding current Iz becomes smaller, the conduction time Wz becomes shorter as the conduction resistance Rx before welding becomes larger, and the pressure Pz becomes larger as the conduction resistance Rx before welding becomes larger. It is characterized by the following.

According to the present invention, in the resistance welding machine, each time welding is performed, the welding current Iz, the energizing time Wz, and the pressing force Pz are determined according to the conduction resistance Rx before welding, which is obtained before execution. At least two of the parameters are adjusted. As a result, the current welding conditions can be more accurately adjusted, and the success rate of resistance welding is further improved.

[0030] In the resistance welding machine according to the present invention, the control means includes:
After the resistance welding is performed, the second measuring current Iy lower than the welding current Iz is supplied to the entire welded material after welding via the pair of electrodes, and the voltage Vy between the pair of electrodes is measured by the voltmeter. And the measured voltage Vy and the second measured current Iy
Based on the above, the conduction resistance Ry after welding of the whole material to be welded is obtained.

According to the present invention, in the resistance welding machine, after the welding is performed, the voltage Vy between the electrodes is supplied while supplying a predetermined measurement current Iy to the welded workpiece through a set of electrodes.
Is measured, and based on the measured voltage Vy and the measured current Iy, the conduction resistance after welding of the entire material to be welded, that is, the conduction resistance Ry of the welded product having the welded portion is calculated. 1
If the voltage between the electrodes is measured while supplying a constant current to the welding product through a set of electrodes, the conduction resistance Ry of the welding product
Can be calculated accurately. Further, since the conduction resistance Ry is measured and calculated after the execution of the welding, it is possible to check the quality of the welded portion of the welded product. This makes it possible to reliably suppress the shipment of poor quality welding products.

[0032]

FIG. 1 is a diagram showing a configuration of a resistance welding machine 1 according to an embodiment of the present invention. Resistance welding machine 1
Uses a resistance welding method to mutually weld a plurality of workpieces 2 to obtain a welded product. In the example of FIG.
Is a left-right pressurizing type and employs an inverter energization method, and welds two workpieces 2. FIG.
In FIG. 2, a part of the material 2 to be welded after the completion of welding is cut away to show the welded portion 22.

The resistance welding machine 1 includes a set of electrodes 3A, 3B,
It includes at least a welding power source 4, a pressure source 5, a voltmeter 6, and a control unit 7, an inspection power source 11, a storage unit 12, a notification unit 13,
And an input unit 14. Control unit 7 is realized by, for example, a computer. The storage unit 12 is realized by a device that combines a device that reads data from a recording medium and the recording medium, or a device that includes a storage element that is a semiconductor device. The input unit 14 is realized by, for example, a combination of a mouse and a display device or a keyboard. Notification unit 13
Includes at least one of a display unit 16 including a liquid crystal display element or a cathode ray tube, a speaker 17, a warning light, and the like. In the example of FIG. 1, since the resistance welding machine 1 employs the inverter energization method, the welding power source 4 and the inspection power source 1 are used.
1 is realized by a DC power supply, and the voltmeter 6 is realized by a DC voltmeter.

The control unit 7 controls the entire resistance welding machine 1, in particular, the welding power source 4 and the pressure source 5. The notification unit 13
It is used for notification of various data in the control unit 7 and for warning from the control unit 7. The input unit 14 is used to input an instruction from the operator of the resistance welding machine 1 to the control unit 7.
The storage unit 12 stores various setting data used by the control unit 7.

Prior to welding, a set of materials to be welded 2 are combined such that surfaces 21 to be joined are in contact with each other. One set of materials 2 to be welded is attached to one set of electrodes 3A and 3B. One electrode 3 of one set of electrodes
A, one set of the material to be welded 2 already assembled, the other electrode 3B of the one set of electrodes, and the welding power source 4 are sequentially connected in series in this order, and form a closed circuit. I have. The voltmeter 6 is connected to the welding power source 4 in parallel, and both terminals are connected to a pair of electrodes 3A and 3B. Inspection power supply 1
1 is also connected in parallel to the welding power source 4 and the voltmeter 6 and has both terminals connected to one set of electrodes 3A and 3B and the voltmeter 6.
Are connected to both terminals.

In response to the control of the control unit 7, the welding power source 4 applies a current flowing perpendicularly to the surface 21 to be joined of the workpiece 2 to the pair of assembled workpieces 2 and the electrodes 3A, Supply via 3B. The pressure source 5 responds to the control of the control unit 7 to apply a pressing force Pz acting vertically to the surface 21 to be joined of the workpiece 2 to the set of workpieces 2 already assembled. The voltmeter 6 measures the voltage between a pair of electrodes 3A and 3B. The inspection power supply 11 is, like the welding power supply 4, a control unit 7.
In response to the above control, a current flowing perpendicular to the surface 21 to be joined of the workpiece 2 is supplied to the combined set of workpieces 2 via the electrodes 3A and 3B.

The resistance welding machine 1 according to the present embodiment
Is characterized by the control of the entire welding process. Schematically,
The control unit 7 applies the electrodes 3A,
Each time 3B is attached, one set of welded materials 2
The conduction resistance Rx before the entire welding is obtained prior to the execution of welding, the welding conditions are adjusted based on the conduction resistance Rx before the welding, and the welding power source 4 and the pressure source 5 are controlled and combined based on the welding conditions. The resistance welding of the completed set of workpieces 2 is performed. The conduction resistance Rx of the entire set of welded materials 2 before welding depends on the shape and characteristics of each of the materials 2 to be welded and the state of the places where the materials 2 are in mutual contact with each other. In FIG. 1, the conduction resistance Rx of the entire set of welded materials 2 before welding corresponds to the resistance between the pair of electrodes 3A and 3B in a state where the assembled welded material 2 is sandwiched. are doing.

As described above, in the resistance welding machine 1 shown in FIG. 1, every time a pair of assembled workpieces 2 is attached to the electrodes 3A and 3B, that is, resistance welding to a new set of workpieces 2 is performed. Each time it is started, the conduction resistance Rx of the entire workpiece 2 before welding is determined, and the conduction resistance Rx before welding is determined.
Resistance welding is executed in accordance with the welding conditions adjusted based on. As a result, occurrence of welding failure due to variation in the conduction resistance Rx before welding is suppressed. by this,
Since the success rate of resistance welding is improved, it is possible to reduce the quality defects of the welded product and improve the yield of the welding process.

In order to determine the conduction resistance Rx before welding, prior to the execution of resistance welding, a first measurement for inspection is performed on a combined set of workpieces 2 via a pair of electrodes 3A and 3B. The voltage Vx between the pair of electrodes 3A and 3B is measured by the voltmeter 6 while supplying the current Ix. Based on the measured voltage Vx and the first measurement current Ix, the conduction resistance Rx before welding as shown in Expression 2 is calculated. JP-A-5-5
One set of electrodes 3A, 3
Rather than measuring a current flowing between the electrodes 3A and 3B while applying a constant voltage between B and B, a set of electrodes 3
By measuring the voltage between the electrodes 3A and 3B while supplying a constant current to the workpiece 2 between A and 3B, the conduction resistance Rx of the combined workpiece 2 can be accurately calculated. Rx = Vx / Ix (2)

FIG. 2 is a graph showing an energization pattern to the workpiece 2 in the resistance welding machine 1 of FIG. In one welding process, after the start of the process, the first DC current
The measurement current Ix is supplied for a predetermined energization time Wx, and the first
After a predetermined time interval from the completion of the application of the measurement current Ix, the welding current Iz, which is a DC current, changes to the predetermined conduction time W
Only z is supplied. The welding current Iz is selected, for example, to a value within a range of 50 A or more and 100 A or less.

As shown in FIG. 2, the conduction resistance Rx before welding is
The magnitude of the first measurement current Ix is smaller than the magnitude of the welding current Iz required for resistance welding in order to prevent one set of workpieces 2 from being welded at the time of the measurement. Preferably, the first measurement current Ix is a lower limit value Iz of the welding current Iz.
smaller than max. Further, the conduction time Wx of the first measurement current Ix is preferably set as short as possible. This is to prevent heating of the workpiece 2 because the conduction resistance measurement becomes unstable when the workpiece 2 is heated by resistance heating. For example, the conduction time Wz of the welding current Iz
Is less than 1 second and the order of the current supply time Wz is close to 1 second, the current supply time Wx of the first measurement current Ix is set to 1 to 9 milliseconds.

The first measurement current Ix may be supplied from the inspection power supply 11 or may be supplied from the welding power supply 4.
If the welding power supply 4 is realized by a constant current source whose supply current does not change, the inspection power supply 1 which is a constant current source
1 to supply the first measurement current from the inspection power supply 11. If the welding power supply 4 is configured so that the magnitude of the supplied current is variable, the first measurement current Ix is supplied from the welding power supply 4. It is possible. If the first measurement current Ix is supplied from the welding power supply 4, the inspection power supply 11 can be omitted from the resistance welding machine 1.

After the resistance welding is performed, the welded workpiece 2
In order to confirm the quality of the welded product, that is, the quality of the welded product, the conduction resistance Ry of the entire workpiece 2 after welding, that is, the conduction resistance Ry of the welded product having the welded portion 22 may be further obtained. For this reason, after performing the resistance welding, the control unit 7 supplies the second measured current Iy to the welded workpiece 2 via the electrodes 3A and 3B, and also controls the voltage V between the electrodes 3A and 3B.
y is measured by the voltmeter 6. Based on the measurement voltage Vy and the second measurement current Iy, the conduction resistance Ry after welding of the entire workpiece 2 as shown in Expression 3 is calculated. Ry = Vy / Iy (3)

Even when the conduction resistance Rx before welding is extremely large, if resistance welding is successful, the conduction resistance Ry after welding is, for example, about 0.1 mΩ. Therefore, the conduction resistance Rx after welding is smaller than the conduction resistance Rx before welding.
If y is sufficiently small, it can be determined that the resistance welding is successful. Rather than measuring a current between the electrodes 3A and 3B while applying a constant voltage between the electrodes 3A and 3B as in the prior art, welding through the set of electrodes 3A and 3B as in the present invention. By measuring the voltage between the electrodes 3A and 3B while supplying a constant current to the product, the conduction resistance Ry of the welded product can be accurately calculated. In addition, since the conduction resistance Ry is measured and calculated after the execution of the welding, it is possible to confirm the quality of the welded portion 22 of the welded product, and thus it is possible to reliably suppress the shipment of poor quality welded products.

More specifically, as shown in FIG. 3, after a predetermined time interval from the completion of the application of the welding current Iz, the second measurement current Iy, which is a DC current, is supplied to the welding power supply 4 or the inspection power supply 11. Is supplied for a predetermined energizing time Wy.
In order to prevent the set of materials to be welded 2 from being further welded during the measurement of the conduction resistance Ry after welding, the magnitude of the second measurement current Iy is larger than the magnitude of the welding current Iz required for resistance welding. Is also small. Preferably, the second measurement current Iy
Is smaller than the lower limit of the welding current Iz. The energization time Wy of the second measurement current Iy is determined by the resistance of the material 2 to be welded.
Is preferably set as short as possible in order to prevent measurement instability due to heating. For example, the welding current I
z is less than 1 second and the energizing time W
If the order of z is close to 1 second, the energization time Wy of the second measurement current Iy is set to 1 to 9 milliseconds.

Preferably, the storage unit 12 stores in advance a predetermined initial welding condition and a predetermined management range. The control range is based on the initial welding conditions.
Is the range of the conduction resistance Rx before welding obtained when welding is successful when resistance welding is performed. For example, the upper limit value Rxmax of the control range is equal to the minimum conduction resistance Rx before welding when explosion occurs when performing resistance welding based on the initial welding conditions, and the lower limit value Rxmim of the control range is based on the initial welding conditions. It is equal to the maximum conduction resistance Rx before welding when the energy Q is too small to perform welding when performing resistance welding.

In a situation where the initial welding conditions and the control range are set in advance, the control unit 7 calculates the conductive resistance Rx before welding and the predetermined control range every time the conductive resistance Rx before welding is calculated. And the conduction resistance R before the welding
If x is included in the management range, the initial welding condition is adopted as the current welding condition. Accordingly, since the initial welding condition is used only when the resistance welding is expected to be successful based on the initial welding condition, the occurrence of poor welding due to the conduction resistance Rx before welding is prevented. This also makes it possible to fine-tune the welding conditions before welding if resistance welding based on the initial welding conditions is expected to fail. Furthermore, this makes it possible to achieve both suppression of poor welding and suppression of the number of fine adjustments of welding conditions.

The welding conditions are not limited to being finely adjusted only when the measured conduction resistance Rx before welding is out of the control range. Each time the conduction resistance Rx before welding is measured, the welding resistance Rx is adjusted. May be fine-tuned to suit. Fine adjustment of the welding conditions may be performed manually or automatically.

For manual adjustment of the welding conditions, preferably, each time the control unit 7 calculates the conduction resistance Rx before welding, the control unit 7 causes the notification unit 13 to report the conduction resistance Rx before welding. For example, the conduction resistance Rx itself before welding is digitized or graphed, and is visually displayed on the display unit 16. As a result, every time welding is performed, the operator can recognize the conduction resistance Rx of the entire workpiece 2 before welding, so that the operator manually adjusts the welding conditions in advance according to the conduction resistance Rx before welding. It becomes possible to do.

For manual adjustment of welding conditions, and preferably, each time the control unit 7 calculates the conduction resistance Rx before welding, the control unit 7 compares the conduction resistance Rx before welding with a predetermined control range. If the conduction resistance Rx before the welding is out of the management range, a warning is issued using the notification unit. As a result,
Each time welding is performed, the operator can reliably recognize whether or not the conduction resistance Rx of the entire workpiece 2 before welding is out of the management range. Thereby, when it is expected that the resistance welding based on the preset initial welding conditions will fail, the operator can finely adjust the welding conditions up to the manual beforehand. Control becomes easy.

At the time of the warning by the notification unit 13, it is preferable to use a presentation method that easily distracts the operator, such as generation of a warning sound from a speaker or blinking of a warning light. Further, when the conduction resistance Rx before welding is out of the management range, it is preferable not only to issue a warning but also to present the conduction resistance Rx itself before welding using the notification unit 13.
This facilitates manual adjustment of the welding conditions after the warning.

When manually fine-adjusting the welding conditions based on the constantly notified conduction resistance Rx before welding, or when manually fine-adjusting the welding conditions in response to a warning, the operator must:
The input unit 14 may be operated to increase or decrease the initial welding condition, or a completely new welding condition may be input from the input unit 14. The control unit 7 may execute resistance welding based on new welding conditions obtained in response to an operation on the input unit 14 by the user or welding conditions after the increase or decrease.

When the welding conditions are automatically adjusted, the control unit 7
Automatically adjusts welding conditions based on the conduction resistance Rx before welding each time the conduction resistance Rx before welding is calculated, and performs resistance welding based on the adjusted welding conditions. For automatic adjustment of welding conditions, a welding condition adjustment formula using welding conduction resistance Rx as a parameter is provided in advance as a welding condition fine adjustment program, and the obtained conduction resistance Rx before welding is adjusted. The welding conditions may be obtained by substituting into the equations. Or, as a fine adjustment program for welding conditions,
A welding condition adjustment table using the pre-weld conduction resistance Rx as a search key is provided in advance, and the welding condition corresponding to the obtained pre-weld conduction resistance Rx may be selected from the adjustment table. Thereby, control of the resistance welding machine 1 is further facilitated.

The welding conditions include at least one parameter of the magnitude of the welding current Iz, the conduction time Wz of the welding current Iz, and the magnitude of the pressing force Pz. When at least one of these three parameters is selected as a welding condition, the remaining unselected parameters are set, for example, as fixed values. As the conduction resistance Rx before welding is larger, the welding current I
z is adjusted to be small. As the conduction resistance Rx before welding is larger, the welding current conduction time Wz is adjusted to be shorter. The larger the conduction resistance Rx before welding, the larger the pressure Pz is adjusted. The control of the welding current Iz and the conduction time Wz
The control is performed by the control unit 7 controlling the welding power source 4 that is configured such that the supplied current value and the energizing time are variable. The control of the pressing force Pz is performed by, for example, a set of electrodes 3A,
If a spring is provided as the pressure source 5 that exerts a force in the direction of attracting the 3B to each other, the control unit 7 controls the spring by changing the length of the spring.

As described above, one of the causes of the variation in the conduction resistance Rx before welding is a deviation and a floating between the combined workpieces 2 to be welded. The larger the applied pressure Pz, the more the displacement and lifting of the workpieces 2 are eliminated, and thus the lower the conduction resistance Rx of the combined workpieces 2 before welding. The fine adjustment of the pressing force Pz is most effective because the cause of the variation in the conduction resistance Rx before welding is basically solved. On the other hand, since the welding current Iz and the conduction time Wz are easily controlled automatically by the control unit 7, when these are set as welding conditions, the welding condition adjustment based on the conduction resistance Rx before welding is automated. It will be easier.
Therefore, in order to reduce welding defects due to variations in the pre-weld conduction resistance Rx, it is preferable to adjust the pressing force Pz preferentially over the welding current Iz and the conduction time Wz.

The welding current Iz, the conduction time Wz and the pressing force Pz
In the case where two or more parameters are set as welding conditions, the current welding conditions can be adjusted more accurately, and the success rate of resistance welding is further improved.
When the welding conditions include two or more parameters, the welding current Iz and the conduction time Wz with respect to the change in the pre-weld conduction resistance Rx
An adjustment map indicating the change between the pressure and the pressing force Pz may be prepared in advance, and a specific value of each parameter corresponding to the determined conduction resistance Rx before welding may be selected from the adjustment map.

Preferably, the parameters of the welding conditions are adjusted to be larger as the conduction resistance Rx before welding is larger. For example, if the conduction resistance Rx before welding is less than a predetermined threshold,
The welding pressure Iz alone and the initial values are adopted as the welding current Iz and the conduction time Wz. If the conduction resistance Rx before welding is equal to or greater than the threshold, not only the welding pressure Iz but also the welding current Iz and the conduction time Wz Also adjust. As a result, the current welding conditions can be adjusted more finely, and the success rate of resistance welding is further improved.

FIG. 4 is a flowchart for explaining the procedure of the welding process when the welding conditions are manually adjusted in the resistance welding machine 1 of FIG. After a new set of materials to be welded 2 is attached to the electrodes 3A and 3B, the process proceeds from step A0 to step A1. In step A1, the control unit 7 applies the electrodes 3A, 3B to the combined workpiece 2 to be welded.
, The voltmeter 6 measures the voltage Vx between the pair of electrodes 3A, 3B while supplying the first measurement current Ix through the voltmeter 6. The control unit 7 calculates the conduction resistance Rx before welding of the entire combined workpiece 2 in step A2, and presents the obtained conduction resistance Rx before welding in step A3 using the notification unit 13.

In step A4, the control unit 7 compares the required conduction resistance Rx before welding with a control range.
When the conduction resistance Rx before welding is less than the lower limit value Rxmin of the control range or equal to or more than the upper limit value Rxmax of the control range,
The control unit 7 sounds an alarm in the notification unit 13 for warning in step A5, and waits for an operation on the input unit 14 by the user in step A6. If the input unit 14 is operated,
The controller 7 adjusts the current welding condition in step A7 according to the operation result. If the conduction resistance Rx before welding is greater than or equal to the lower limit value Rxmim of the control range and less than the upper limit value Rxmax of the control range, the process proceeds from step A4 to step A8, and the preset initial welding condition is used as it is for the current welding condition. To be adopted.

In step A9, the control section 7 executes resistance welding based on the current welding conditions adjusted in step A7 or step A8. That is, while applying the pressing force Pz of the magnitude specified in the current welding condition to the combined workpiece 2, the magnitude specified in the current welding condition over the energizing time Wz specified in the current welding condition is applied. The welding current Iz is supplied to the assembled workpiece 2 via the electrodes 3A and 3B. As a result, the portion of the surface of the combined workpieces 2 to be joined is melted and diffused by Joule heat, and the workpieces are joined to each other.

In step A10, the control unit 7 supplies the voltage Vy between the electrodes 3A and 3B while supplying the second measurement current Iy to the welded workpiece 2 via the electrodes 3A and 3B.
Is measured by the voltmeter 6. The controller 7 calculates the conduction resistance Ry of the workpiece 2 after welding in step A11,
The determined conduction resistance Ry after welding is evaluated in step A12. After the evaluation, the welding process is completed in step A13. According to the above procedure, a welding process involving manual adjustment of welding conditions can be executed.

FIG. 5 is a flow chart for explaining the procedure of the welding process when the welding conditions are automatically adjusted in the resistance welding machine 1 of FIG. After a new set of materials to be welded 2 is attached to the electrodes 3A and 3B, the process proceeds from step B0 to step B1. In step B1 and step B2, the control unit 7 executes steps A1, A in FIG.
2, the conduction resistance Rx before welding of the entire set of the welded materials 2 is determined. In step B3, the control unit 7 compares the required conduction resistance Rx before welding with the control range, similarly to step A4 in FIG.
When the conduction resistance Rx before welding is less than the lower limit value Rxmin of the control range or equal to or more than the upper limit value Rxmax of the control range,
The process proceeds from step B3 to step B4, and the control unit 7 automatically adjusts the current welding condition based on the required conduction resistance Rx before welding. When the conduction resistance Rx before welding is equal to or larger than the lower limit value Rxmim of the control range and smaller than the upper limit value Rxmax of the control range, the process proceeds from Step B3 to Step B5, and is set in advance as in Step A8 of FIG. The initial welding conditions are directly used as the current welding conditions.

In step B6, the controller 7 executes step B4 or step B4 in the same manner as step A9 in FIG.
The resistance welding is executed based on the current welding conditions adjusted in step 5. In steps B7 to B9, the control unit 7
Performs the same processing as Steps A10 to A12 in FIG. 4 and obtains and evaluates the conduction resistance Ry of one set of the workpieces 2 after welding. After the evaluation, the welding process is completed in step B10. According to the above procedure, a welding process involving automatic adjustment of welding conditions can be executed.

The resistance welding machine 1 of the present embodiment is an example of the resistance welding machine 1 of the present invention, and can be realized in other various forms as long as the main configuration and operation are the same. Particularly, the detailed configuration and operation of each component in the resistance welding machine 1 are as follows.
If the same effect can be obtained, the present invention is not limited to the above-described configuration and operation, but may be realized by another configuration and operation.
For example, each time a new welding process is started, the resistance welding machine 1 sets the conduction resistance R of the combined workpiece 2 before welding.
x is not limited to the left and right pressurization type and the inverter energization type as long as the resistance welding is performed in accordance with the current welding condition adjusted based on the conduction resistance Rx. You may.

[0065]

As described above, according to the present invention, in the resistance welding machine, prior to welding, the conduction resistance Rx before welding of the entire plurality of workpieces combined in a state where the surfaces to be joined are in contact with each other. Is calculated, and resistance welding of the material to be welded is performed based on welding conditions adjusted based on the conduction resistance Rx before the welding. Thereby, the success rate of the resistance welding is improved, so that it is possible to reduce the quality defect of the welded product and to improve the yield of the welding process. Further, according to the present invention, the resistance welding based on the initial welding conditions is performed only when the conduction resistance Rx of the entire material to be welded before welding is within a predetermined management range. Thereby, the conduction resistance R before welding is obtained.
In the case where the occurrence of poor welding due to x is prevented beforehand and the failure of resistance welding based on the initial welding conditions is expected, it is possible to finely adjust the welding conditions in advance.

Further, according to the present invention, the conduction resistance Rx is reported each time the conduction resistance Rx before welding of the plurality of combined workpieces is obtained. This allows the operator to manually adjust the welding conditions in advance according to the conduction resistance Rx before the welding. Further, according to the present invention, a warning is issued if the conduction resistance Rx before welding of all of the combined plurality of workpieces is out of the predetermined management range. Thereby, when failure of the resistance welding based on the initial welding conditions is expected, the operator can manually fine-adjust the welding conditions in advance. Furthermore, according to the present invention, the conduction resistance R before welding of the entire assembled workpiece is welded.
The welding conditions based on x are automatically adjusted, and resistance welding is performed based on the welding conditions. This further facilitates control of the resistance welder.

Further, according to the present invention, the magnitude of the welding current Iz required for resistance welding and the conduction time Wz of the welding current are determined in accordance with the conduction resistance Rx before welding, which is obtained before execution, every time welding is performed. , And the pressure Pz applied to the material to be welded are adjusted. Since the welding current Iz and the conduction time Wz are easily controlled automatically by the control unit 7, when these are set as welding conditions, it is easy to automate the welding condition adjustment based on the conduction resistance Rx before welding. Fine adjustment of the pressing force Pz is the most effective because the cause of the variation in the conduction resistance Rx before welding is basically eliminated. Further, according to the present invention, at least two parameters of the magnitude of the welding current Iz, the energization time Wz, and the magnitude of the pressing force Pz are adjusted according to the conduction resistance Rx before the welding. This further improves the success rate of resistance welding. Furthermore, according to the present invention, in a resistance welding machine, after the execution of welding, the conduction resistance after welding of the entire material to be welded, that is, the conduction resistance Ry of a welded product having a welded portion is determined. This makes it possible to reliably suppress the shipment of poor quality welding products.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a resistance welding machine 1 according to an embodiment of the present invention.

FIG. 2 is a graph showing a first energization pattern for a workpiece 2 in the resistance welding machine 1 of FIG.

FIG. 3 is a graph showing a second energization pattern to a workpiece 2 in the resistance welding machine 1 of FIG. 1;

FIG. 4 is a flowchart for explaining a welding process including manual adjustment of welding conditions in the resistance welding machine of FIG. 1;

FIG. 5 is a flowchart illustrating a welding process including automatic adjustment of welding conditions in the resistance welding machine of FIG. 1;

FIG. 6 is a diagram showing a configuration of a conventional vertical pressure type resistance welding machine.

FIG. 7 is a view showing a configuration of a conventional right-and-left pressure type resistance welding machine.

FIG. 8 is a view showing a state in which a material to be welded in a resistance welding machine according to the prior art is applied to a workpiece;
It is a graph which shows various energization patterns.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resistance welding machine 2 Workpiece 3A, 3B electrode 4 Welding power supply 5 Pressure source 6 Voltmeter 7 Control part 12 Storage part 13 Notification part 14 Input part Ix First measurement current Rx Before welding of the whole combined workpiece before welding Conduction resistance Iy Second measurement current Ry Conduction resistance of entire welded material after welding Iz Welding current Wz Energizing time of welding current Pz Pressure applied to welded material

Claims (10)

[Claims] 1. A resistance welding machine for welding a plurality of materials to be welded, comprising: a set of electrodes to which the materials to be welded, which are combined with their surfaces to be joined in contact with each other, are attached; A welding power source for supplying an electric current flowing perpendicularly to the surface to be joined to the set of materials to be welded through the electrodes, and a power source acting vertically to the surface to be joined of the material to be welded. Pressure Pz
A pressure source for applying pressure to a set of materials to be combined, a voltmeter for measuring a voltage between a pair of electrodes, and control means for controlling a welding power source and the pressure source. Means that each time an electrode is attached to a new workpiece, one set of a first measurement current Ix, which is smaller than a welding current Iz required for resistance welding of one set of workpieces, is passed through the electrode before performing the welding. The voltage between the electrodes V
x is measured by a voltmeter, and the measured voltage Vx and the first
Based on the measured current Ix, the conduction resistance Rx before welding of the entire combined workpiece is determined, and the welding conditions are adjusted based on the determined conduction resistance Rx before welding. A resistance welding machine for performing resistance welding of a material to be welded while controlling a welding power source and a pressure source based on conditions. 2. A predetermined initial welding condition, and a control range which is a range of a conduction resistance Rx before welding obtained when resistance welding of a material to be welded is performed based on the initial welding condition and the welding is successful. The control means further compares the conduction resistance Rx before welding with a predetermined control range each time the control means calculates the conduction resistance Rx before welding. 2. The resistance welding machine according to claim 1, wherein if the conduction resistance Rx is within the management range, the initial welding condition is adopted as the current welding condition. 3. A notifying unit for notifying, wherein the control unit causes the notifying unit to notify the conducting resistance Rx before welding each time the conducting resistance Rx before welding is calculated. The resistance welding machine according to claim 1 or 2, wherein 4. A notifying means for notifying, and a continuity resistance R before welding when welding is successful when resistance welding of a material to be welded is performed based on predetermined initial welding conditions.
storage means for preliminarily storing a control range which is a range of x, wherein the control means calculates the conductive resistance Rx before welding and the predetermined control range each time the control means calculates the conductive resistance Rx before welding. 4. The resistance according to any one of claims 1 to 3, wherein if the conduction resistance Rx before the welding is out of the control range, a warning is issued using a notification unit. Welding machine. 5. The welding apparatus according to claim 1, wherein the control means automatically adjusts welding conditions based on the conduction resistance Rx before welding each time the conduction resistance Rx before welding is calculated.
The resistance welding machine according to any one of claims 4 to 4. 6. The welding condition includes the magnitude of the welding current Iz, and the larger the conduction resistance Rx before welding, the greater the welding current Iz.
The resistance welding machine according to any one of claims 1 to 5, wherein the resistance is adjusted to be smaller. 7. The welding condition includes an energization time Wz of the welding current Iz, and the energization time Wz is adjusted to be shorter as the conduction resistance Rx before the welding is larger. The resistance welding machine according to any one of claims 1 to 6. 8. The welding condition according to claim 1, wherein the welding condition includes a magnitude of the pressure Pz, and the pressure Pz is adjusted so as to increase as the conduction resistance Rx before the welding increases.
The resistance welding machine according to any one of claims 1 to 7. 9. The welding condition includes at least two parameters of the magnitude of the welding current Iz, the conduction time Wz of the welding current Iz, and the magnitude of the pressing force Pz. The adjustment is made such that the larger the resistance Rx, the smaller the welding current Iz, the larger the conduction resistance Rx before welding, the shorter the energization time Wz, and the larger the conduction resistance Rx before welding, the larger the pressing force Pz. The resistance welding machine according to any one of claims 1 to 5, wherein the resistance welding is performed. 10. The control means, after executing the resistance welding, supplying a second measurement current Iy lower than the welding current Iz to the entire material to be welded through the one set of electrodes through the set of electrodes. The voltage Vy between the electrodes is measured by the voltmeter, and based on the measured voltage Vy and the second measurement current Iy,
The resistance welding machine according to any one of claims 1 to 9, wherein a conduction resistance Ry after welding of the entire material to be welded is obtained.