JPH04237580A - Resistance welding machine - Google Patents

Abstract

PURPOSE:To prevent the generation of expulsion and surface flash and to obtain the satisfactory welding quality by carrying out pressurization control and energizing start control at high speed with high accuracy. CONSTITUTION:An upper welding electrode is fitted to the lower end side of a slide shaft 38 for pressurizing and a pressurizing cylinder 14 is provided on the same axis via an urethane spring 46, etc., at the upper end side of the slide shaft 38 for pressurizing. When a piston rod 56 of the pressurizing cylinder 14 advances in a state With the upper welding electrode abutted on materials to be welded, the urethane spring 46 is compressed and deformed and the elastic pressurizing force (stress) due to the compression and deformation is applied to the materials to be welded via the slide shaft 38 for pressurizing and the welding electrode. A load cell (pressure sensor) 52 arranged between the urethane spring 46 and the pressurizing cylinder 14 outputs a sensor signal to show a value of the pressurizing force applied to the materials to be welded in real time.

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, and more particularly to a resistance welding machine suitable for can-seal welding of small precision parts.

0002

[Prior Art] Figs. 7 and 8 show Can Seal (C
An example of welding is shown below. As shown in FIG. 7, a cap-shaped lid 206 is placed over the substrate 204 to which the element 200 and lead wires 202 and 203 are attached, and the annular flange 206a of the lid 206 and the peripheral edge 204a of the substrate 204 are welded. By doing so, a can-seal package for electronic components is formed.

[0003] This can seal welding will be explained in detail with reference to FIG. Since the flange 206a of the lid 206 extends obliquely downward from the lid body, the upper welding electrode 208 and the lid flange 206a, and the lid flange 206a and the substrate peripheral edge 204a partially contact each other before welding starts. are doing. In this way, by reducing the contact area of the welding part, it is possible to increase the density of the welding current at the start of welding, efficiently generate Joule heat, and lighten the load on the power supply circuit. When welding starts, first, an initial pressure is applied between the upper welding electrode 208 and the lower welding electrode 210 by a pressure mechanism (not shown), and after a certain period of time, the initial pressure is changed to the original (regular) welding pressure. The pressure is switched to the power supply circuit (
(not shown) outputs welding voltage. Then, the upper welding electrode 208 → the lid flange 206a → the substrate periphery 204
Welding current flows through the path a→lower welding electrode 210, and the lid flange 206a and the substrate peripheral edge 204a are welded together due to resistance heat generation.

[0004] Conventional resistance welding machines of this type have used either a plate spring or a coil spring as the spring means in the pressure mechanism. Further, the time at which a predetermined welding force is expected to be reached is determined from the time at which the welding force is to be switched to the regular welding force and the rising speed of the regular welding force, and energization is started at the determined estimated time.

[0005]

[Problem to be Solved by the Invention] In can-seal welding of small electronic components as described above, if dust occurs, there is a risk of damaging the main body of the electronic component within the package, so it is necessary to prevent dust from occurring as much as possible. High-speed and highly accurate pressurization control and energization start control are required.

However, in conventional resistance welding machines, a plate spring or a coil spring is used as the spring means of the pressurizing mechanism, so it is difficult to quickly transmit the pressurizing force generated by the air cylinder to the welding electrode. The rate of pressure rise was insufficient. In addition, in the method of obtaining the timing of starting energization from the time of switching to the regular welding force and the rate of rise of the normal welding force, it is affected by fluctuations and variations in the rate of rise of the force, so energization starts at the appropriate timing. was difficult to do.

The present invention has been made in view of these problems, and it is an object of the present invention to provide a resistance welding machine that performs high-speed and high-precision pressurization control and energization start control to prevent the generation of dust. purpose.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the resistance welding machine of the present invention includes a pressurizing slide shaft to which a welding electrode is attached to one end and a pressurizing cylinder coaxially disposed, A resin spring is disposed between the other end of the pressurizing slide shaft and the pressurizing cylinder. Furthermore, in order to perform high-speed and highly accurate pressurization control, a pressure sensor was arranged between the pressurizing cylinder and the welding electrode. Further, in order to start energization at an appropriate timing, the structure includes means for receiving an output signal from a pressure sensor and starting energization for resistance welding when the sensor output signal reaches a preset value.

[0009]

[Operation] When the pressure cylinder operates and its piston rod moves forward, the resin spring, pressure slide shaft, and welding electrode also move in the same direction, and the welding electrode eventually comes into contact with the material to be welded. When the piston rod further moves forward, the resin spring is compressed and deformed, and the elastic pressurizing force obtained by the compressive deformation is applied to the material to be welded via the pressurizing slide shaft and the welding electrode. The resin spring is
Because it has a much larger spring coefficient than leaf springs, coil springs, etc., a small amount of compressive deformation can cause large pressure (
stress). Therefore, it is possible to rapidly increase the pressure applied to the welded material to a desired value.

Furthermore, when a pressure sensor is further disposed between the pressure cylinder and the welding electrode, a signal representing the value of the pressure applied to the material to be welded in real time can be obtained from the pressure sensor. Accurate pressurization control or energization control can be performed based on this sensor output signal.

In particular, even when the pressure increases rapidly as described above, the output signal of the pressure sensor provides a real-time detection value of the pressure, so as soon as the pressure reaches a predetermined value, the resistance welding can be energized immediately. You can start.

0012

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6. 1 and 2 are a partially sectional front view and a side view showing the detailed configuration of the head section of a can-seal welding machine according to an embodiment of the present invention, and FIG. 3 is an overall view of the can-seal welding machine. FIG. 2 is a schematic perspective view showing the structure.

First, in FIG. 3, 10 is a fixed base, 12
14 is an air cylinder, and 16 is a welding transformer. Output terminals 18 and 20 of the welding transformer 16 are connected to an upper electrode mounting block 30 and a lower electrode mounting block 32 via secondary conductors 22 and 24 and secondary conductor connection blocks 26 and 28, respectively. An upper welding electrode 208 and a lower welding electrode 210 as shown in FIG. 8 are attached to the upper electrode attachment block 30 and the lower electrode attachment block 32, respectively. The upper electrode mounting block 30 is coupled to a pressurizing slide shaft 38 via an upper platen receiver 34 and a shaft receiver 36. The pressurizing slide shaft 38 is connected to the piston rod of the air cylinder 14 within the head portion 12 via a urethane spring and a load cell, which will be described later. As a result, the vertically downward pressurizing force generated by the air cylinder 14 is applied to the upper welding electrode attached to the upper electrode mounting block 30 and the workpiece to be welded (not shown) via the pressurizing slide shaft 38. It is now possible to

In FIGS. 1 and 2, the pressurizing slide shaft 38 is a hollow shaft and is attached to the bearing holder 4.
is supported by a stroke bearing 42 supported at 0,
It can be moved vertically. The upper end of the pressurizing slide shaft 38 has a ball bearing flange 44,
It is connected to the lower end of a piston rod 56 via a urethane spring 46, a spring receiver 48, a load cell receiver 50, a load cell 52, and a floating joint 54.

A ball slide shaft 58 is embedded in the urethane spring 46, and the lower end of the shaft 58, which projects downward, is slidable within the pressurizing slide shaft 38 via a linear bush 60. As a result, when the urethane spring 46 is elastically compressed by the pressure from the air cylinder 14, the shaft 58 acts as a support for the urethane spring 46, and the urethane spring 46 is compressed and deformed in the vertical direction without twisting. Thereby, the pressurizing force from the air cylinder 14 can be correctly transmitted to the pressurizing slide shaft 38.

A floating base plate 64 is horizontally attached to the ball bearing flange 44 via a vertical flange 62, and this base plate 64 functions as an upward stop for the floating joint 54. Further, as shown in FIG. 2, a detent guide plate 66 is provided vertically on the base plate 64, and a detent pin 68 fixed to the spring receiver 48 is attached to the guide plate 66.
It is guided in the vertical direction within a vertical notch 66a formed in the vertical direction. This allows the urethane spring 46 to move only in the vertical direction. 70 is a base plate. Further, as shown in FIG. 1, a linear shaft 72 is vertically installed on the platen receiver 34 adjacent to the lower end of the pressurizing slide shaft 38, and this linear shaft 72 is attached to a vertical metal holder on the fixed base 10 side. 74 is guided to a bush 76 installed therein. As a result, the pressurizing slide shaft 38, the platen receiver 34 coupled thereto, the upper electrode mounting block 30, etc. are movable only in the vertical direction and are not rotationally movable. Note that an insulator 78 is interposed between the secondary conductor connection block 26 and the platen receiver 34.

FIG. 4 shows the configuration of a pneumatic circuit for driving the air cylinder 14. In this pneumatic circuit 80, 82 is a compressed air pressure source, 84 is an air filter, 86 is a pressure switch, 88 is an air tank, 90 is a regulator, 92 is a pressure gauge, 94 is a check valve, 96 and 98 are directional control valves, 100, 102 and 104 are speed controllers, 106 is a connector, and 108 is an exhaust cleaner.

The pair of directional switching valves 96 and 98 are provided in order to obtain a large cylinder output and to provide a movement stop function, and the load port port A of the first directional switching valve 96 is connected to the speed controller. The load port B of the second directional switching valve 98 is connected to the rod side of the air cylinder 14 via a speed controller 104 .

When retracting the piston rod 56,
As shown in the figure, the first directional switching valve 96 is switched to the exhaust port R1, and the second directional switching valve 98 is switched to the pressure port P, so that the head side of the air cylinder 14 is opened via the exhaust cleaner 108. The rod side is connected to atmospheric pressure, while the rod side is supplied with compressed air from a regulator 90. When moving the piston rod 56 forward to generate pressurizing force, the first directional control valve 96
is switched to the pressure port P, and the second directional switching valve 98 is switched to the exhaust port R1. Thereby, compressed air from the regulator 90 is supplied to the head side of the air cylinder 14, while the rod side is connected to atmospheric pressure. When stopping the movement of the piston rod 56 during forward movement, the second directional switching valve 98 is switched from the exhaust port R1 to the pressure port P. Such switching control between the forward mode, backward mode, and stop mode is performed by the control section 11, which will be described later.
2.

FIG. 5 shows the configuration of the control system in this welding machine. The setting input section 110 includes a keyboard and the like, and inputs setting values for various welding conditions such as pressurizing force, welding current, and energization time. The control section 112 is composed of a microcomputer, and controls the operations of the pneumatic circuit 80 and the welding power supply circuit 114 according to the set values inputted from the setting input section 112. According to this embodiment, the output signal of the load cell 52 is given to the control unit 112, and when the load cell output signal reaches a predetermined value at the rise of the main welding pressure, the control unit 112 issues a control signal to start energization. The signal is supplied to the power supply circuit 114.

FIG. 6 shows the characteristics of the pressurizing force applied to the material to be welded in the can-seal welding machine of this embodiment. The operation of this welding machine will be explained with reference to this characteristic diagram. When the welding sequence starts, the control section 112 first controls the pneumatic circuit 80.
switch to forward mode. As a result, the piston rod 56 of the air cylinder 14 advances (descends), and the load cell 52, urethane spring 46, pressurizing slide shaft 38, etc. also descend integrally with the piston rod 56.
When the upper welding electrode (not shown) comes into contact with the workpiece (not shown) and the pressurizing force reaches a predetermined value (initial pressurizing force) P0, the control unit 112 responds to the output signal of the load cell 52. switches the pneumatic circuit 80 to the stop mode. In this way, the initial pressing force P0 is applied to the welded material for a certain period of time. During this time, the urethane spring 46 has a pressing force P0
It has been slightly compressed and deformed to correspond to the amount.

Next, at time ts, the control section 112 switches the pneumatic circuit 80 from the stop mode to the forward mode in order to apply the regular welding force P1 to the workpiece. Then, the urethane spring 46 is further compressed and deformed by the pressing force from the piston rod 56, and a pressing force corresponding to the amount of compression is applied to the material to be welded through the pressing slide shaft 38. Since the urethane spring 46 is a resin spring, a large amount of pressure is generated even if it is slightly compressed and deformed. Therefore, the pressure applied to the welding material increases rapidly from the initial pressure P0 to the normal welding pressure P1 in an extremely short period of time. In addition, in response to the compression of the urethane spring 46, the ball slide shaft 48 sinks into the through hole of the pressurizing slide shaft 38.

Now, when the pressurizing force reaches a predetermined value Pk while rising from the initial pressurizing force P0 to the regular welding pressurizing force P1, the control section 112 responds to the output signal of the load cell 52 at this time (time tk). The welding power supply circuit 114 is started to be energized. Then, at time te after a predetermined time, the welding power supply circuit 114 is turned off, and then at time t.
At f, the pneumatic circuit 80 is switched to the reverse mode.

As described above, in the can-seal welding machine of this embodiment, urethane is applied to the pressurizing force from the air cylinder 14.
Since the spring 46 responds quickly and quickly transmits the response to the pressurizing slide shaft 38, an extremely high pressurizing force rise speed can be obtained. Furthermore, the load cell 52 detects the value of the pressurizing force that rises rapidly in this way in real time, and the control unit 112 starts energization based on the load cell output signal, so welding is started immediately when the pressurizing force reaches a predetermined value. Electric current can be supplied to the weld. This enables high-speed and highly accurate pressurizing force control and energization start control, and enables good can-seal welding without the occurrence of burrs.

[0025] In the above-mentioned embodiment, the initial welding force was applied to the workpiece for a certain period of time and then switched to the regular welding force. It is also possible to apply pressure. Further, the present invention is not limited to can-seal welding machines, but is applicable to various types of resistance welding machines that require high-speed and highly accurate pressurizing force control and energization start control.

[0026]

[Effects of the Invention] By having the above-described configuration, the present invention achieves the following effects. According to the resistance welding machine of claim 1, the pressurizing force generated in the pressurizing cylinder is applied to the pressurizing slide shaft, the welding electrode, and finally the workpiece through the resin spring, so that the pressurizing force is applied at high speed and in a short time. can be changed to any value, and high-speed and highly accurate pressurization control can be performed. According to the resistance welding machine of claim 2, a pressure sensor is disposed between the pressurizing cylinder and the welding electrode, and the pressurizing force is detected in real time by this pressure sensor, so that the pressurizing force changes rapidly. High-speed, high-precision pressurization control or energization control can be performed even when According to the resistance welding machine of the third aspect, since energization is started when the output signal of the pressure sensor reaches a preset value, accurate energization start timing can be obtained. In this way, high-speed and highly accurate pressure control and energization control can be performed, thereby preventing the occurrence of burrs and ensuring good welding quality.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing the detailed configuration of a head section of a can-seal welding machine according to an embodiment of the present invention.

FIG. 2 is a schematic side view showing the detailed configuration of the head section of the welding machine according to the embodiment.

FIG. 3 is a schematic perspective view showing the overall structure of a welding machine according to an embodiment.

FIG. 4 is a circuit diagram showing the configuration of a pneumatic circuit for driving a pressurizing air cylinder in the welding machine of the embodiment.

FIG. 5 is a block diagram showing the configuration of a control system in the welding machine of the embodiment.

FIG. 6 is a diagram showing pressure characteristics in the welding machine of the example.

FIG. 7 is a perspective view of an electronic component to show an example of can-seal welding.

FIG. 8 is a sectional view showing the configuration of a welded part in can seal welding.

[Explanation of symbols]

12 Head part 14 Air cylinder 30 Upper electrode mounting block 32 Lower electrode mounting block 38 Pressure slide shaft 46 Urethane spring 52 Load cell 56 Piston rod 80 Pneumatic circuit 90 Regulator 96 Directional switching valve 98 Directional switching valve 110 Setting input section 112 Control section 114 Welding power supply circuit

Claims (3)

[Claims] 1. A pressurizing slide shaft to which a welding electrode is attached to one end and a pressurizing cylinder are arranged coaxially, and a resin spring is provided between the other end of the pressurizing slide shaft and the pressurizing cylinder. A resistance welding machine characterized by being equipped with. 2. The resistance welding machine according to claim 1, further comprising a pressure sensor disposed between the pressure cylinder and the welding electrode. 3. The method according to claim 2, further comprising means for receiving an output signal of the pressure sensor and starting energization for resistance welding when the sensor output signal reaches a preset value. resistance welding machine.