JPH07185826A - Clamping device and spot welding machine using the device - Google Patents

Abstract

PURPOSE:To provide a spot welding machine capable of freely controlling the welding pressure during the welding with high responsiveness so that sparks such as sputter may be difficult to scatter. CONSTITUTION:An air cylinder 112 which separates the function to largely stroke and electrode to hold a work to be welded from the function to apply pressure to the electrode in energizing the welding current, and strokes one electrode 120 toward the welding position, and an air cylinder 122 to apply welding pressure to the other electrode 138 thereafter are provided. When the electrodes are simply moved, a small force may be sufficient, and the cylinder area of the cylinder 112 for stroke may be small, contributing to the air-saving. The stroke and the volume of the cylinder for applying pressure may be remarkably small, and extremely large responsive speed can be obtained, controlling the energized current value during the spot welding and the welding pressure to be applied by the lower cylinder 122 in an on-line and real time manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clamp device and a spot welding machine using the device.

[0002]

2. Description of the Related Art When performing spot welding, it is said that the three main factors that have a great influence on the welding are the energizing current value, energizing time and pressure. Since the stroke of the pneumatic actuator used to pressurize the welding electrode is large and the response speed is extremely slow, it is difficult to freely control the applied pressure during energization. Is maintained, and two values of the energizing current value and the energizing time are freely controlled. Therefore, since the pressing force during energization is almost constant, sparks such as spatter easily scatter, and when a pneumatic cylinder is used as an actuator,
Since the pneumatic cylinder with a large stroke drives the electrode to generate the necessary pressing force, a certain level of high supply pressure is required, and the actual situation is that the air consumption increases corresponding to that stroke. .

[0003]

DISCLOSURE OF THE INVENTION According to the present invention, when the welding pressure is increased and the welded object is pressed (the clamp is strengthened) during energization of spot welding, sparks such as spatter are less likely to occur. When the pressure is adjusted, the contact resistance value can be adjusted within a certain range, which is more efficient in terms of electricity consumption. Also, a small force is sufficient when making a large stroke of the welding electrode, while welding that is paired It was made paying attention to the fact that it is preferable to apply a large pressing force between the welding electrodes when the electrodes sandwich a welded object and perform welding.

Further, according to the present invention, when the fluid pressure actuator is applied to the pressurizing mechanism of the spot welding machine, the response speed (natural frequency) of the guide valve, the cylinder or the like which is a constituent element of the fluid pressure actuator.
Is inversely proportional to the square root of the cylinder volume, so if the cylinder stroke is significantly reduced and the cylinder volume is significantly reduced, an extremely large response speed can be obtained. What can be done in time and the amount of fluid required to produce the same pressure change in the cylinder chamber (cylinder force change) is proportional to the cylinder volume, so if the cylinder volume is significantly reduced the amount of working fluid (air This is based on the consideration that when used, the air consumption amount) will be significantly reduced, and the working fluid amount required for pressurizing force control can be significantly reduced.

The present invention has been made in view of the above as a technical problem, and includes a pair of elements that can be closely opposed to each other, and uses a pneumatic actuator to relatively move them to a position where they are closely opposed to each other and are clamped. In a device, it aims at reducing the air consumption of a clamp device.

Another object of the present invention is to provide a spot welding machine capable of controlling the pressure force during welding so that sparks such as spatters are less likely to be scattered, with high responsiveness and precision. To do.

[0007]

To this end, the clamp device according to the present invention is capable of closely facing each other, and at least one of a pair of elements for clamping an object in the closely facing state,
First driving means in the form of a pneumatic actuator that moves toward a predetermined position that closely faces them, and blocking means that blocks displacement of the pair of elements in a direction opposite to the moving direction when the pair of elements closely faces each other. And a force larger than a force for moving at least one of the pair of elements at the predetermined position by the first driving means,
Second drive means for urging in the direction of pressurizing toward the other;
It is characterized by having.

Further, according to the present invention, in the clamp device, one of the pair of elements is an element driven by the first drive means, and the displacement of the element from the predetermined position is prevented and The other of the pair of elements is driven by the second driving means.

Alternatively, according to the present invention, one of the pair of elements is an element driven by the first drive means and the other is a fixed element to prevent the displacement from the predetermined position, At a given point, the one element is coupled to the second drive means.

Furthermore, the present invention resides in the above apparatus,
The second drive means is composed of a pneumatic actuator having a pneumatic cylinder.

Further, the spot welding machine of the present invention comprises the clamp device of any one of the above-mentioned forms, wherein the object is an object to be welded, and the pair of elements are electrodes for passing a welding current. Characterize.

[0012]

According to the present invention, a pair of elements that can be closely opposed to each other are provided, and strokes are made at a position where they are clamped in close proximity to each other by using a clamp device, and an operation of pressurizing each other at the time of close proximity is required. In the clamping device, by separating the function to make the element stroke larger and the function to pressurize it, a small force is required when simply moving the element, so it is possible to significantly reduce the cylinder area of the pneumatic cylinder making the stroke. Therefore, it is possible to contribute to air saving.

Further, in the spot welding machine to which the clamp device is applied, it is possible to press the welded article by increasing the pressing force during energization of the spot welding, and it is difficult for sparks such as spatter to scatter. In addition, the applied pressure can be adjusted to adjust the value of the contact resistance within a certain range, and the power consumption can be reduced.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

(Embodiment 1) First, as a first embodiment of the present invention, the pair of elements are a pair of welding electrodes, and one of them is an electrode driven by the first driving means, and the predetermined electrode of the electrodes is used. An embodiment in which the displacement from the position is prevented and the other electrode of the pair of elements, that is, the other electrode is driven by the second drive means will be specifically described.

FIG. 1 is a side view showing a schematic structure of the spot welding machine of the embodiment, FIG. 2 is a schematic view showing a sectional structure of a clamp device which is a main part thereof, and FIG. 3 is a side of a second driving means thereof. It is a typical sectional view which expands and shows the principal part.

First, the schematic construction of the apparatus of this embodiment will be described with reference to FIG.
The upper beam 108 has a relatively large stroke in order to relatively separate the pair of electrodes at a position that does not hinder the interposition of the object to be welded and to make the pair of electrodes closely face each other after the setting. A cylinder 112 as a first drive means is fixed. At the tip of the rod, an upper cooling block is provided which is supplied with a welding current from the transformer 104 through the secondary conductor 105a and is cooled with an appropriate cooling medium (cooling water or the like).
Reference numeral 116 is an upper arm attached to the block 114, and holds the upper electrode holder 118 so that the upper electrode holder 118 can be appropriately positioned. Reference numeral 120 is an upper electrode tip attached to the holder 118 as one element. Also, 1
Reference numeral 06 is a control device, and the main part of FIG. 4 can be provided.

On the other hand, on the lower beam 110 of the main body 100, the cylinder 122 presses the other element upward (toward the electrode tip 120) with a force larger than the force for moving the upper electrode tip 120. A cylinder portion 122 as a second driving means for urging is fixed. The lower cooling block 134 is attached to the movable portion of the cylinder portion 122.

The lower cooling block 134 holds a lower electrode holder 136 facing the upper electrode holder 118. 138 is a lower electrode tip attached to the holder 136 as the other element. It should be noted that the lower cooling block 134 is provided with an appropriate cooling medium passage (for example, a liquid passage for flowing cooling water), which is not shown, and the welding current supplied from the transformer 104 via the secondary conductor 105b is passed. It is possible to cool the heat generated by.

Next, the detailed structure of each of the above parts will be described with reference to FIGS. First, in FIG. 2, the inside of the cylinder 112 is divided into cylinder chambers 152 and 154 by a piston 158, and the piston 158 is provided with a rod 166 extending in the axial direction (stroke direction) of the cylinder 166. A brake shoe 162 as a displacement prevention means is provided around the rod 166 that is out of the cylinder chamber 154, and the brake chamber 1 outside the seal 160 provided around the brake shoe 162 is provided.
It displaces in the radial direction according to the action of the compressed air introduced into 56, and prevents displacement of the rod 166.

Reference numeral 152 denotes a solenoid valve type directional control valve,
The block a or c is switched according to the input of the pilot signal which is an electric signal, and the compressed air supply port 146 is communicated with the cylinder chamber 152, while the cylinder chamber 154 is opened to the atmosphere communication port 150, or the compressed air supply port 146.
While communicating with the cylinder chamber 154,
4 is opened to the atmosphere communication port 150. Further, when these pilot signals are not input, they are held at the position b by which the paths of the respective parts are blocked by the action of the spring. 144 is a directional control valve in the form of a solenoid valve, which switches to block e in response to the input of a pilot signal which is an electric signal, and the compressed air supply port 14
8 to the brake chamber 156, and when the pilot signal is not input, the brake chamber 156 is connected to the atmosphere communication port 1
Open to 50a. Note that these directional control valves may be of the air operated type that operates in response to the supply of pilot air. This also applies to each embodiment described later.

On the other hand, the cylinder 122 includes a cylinder head 124 fixed to the lower beam 110 and an electrode tip 120.
It has a head 126 provided on the side facing to, a diaphragm 128 clamped and fixed to these heads, and a piston disk 130 attached to the diaphragm 128. Further, the lower cooling block 134 is attached to the lower rod 130a integrally fixed to the disk 130.
Is attached. And the lower cooling block 13
4 is held by an Eden spring 140 supported by jigs 140a to 140c, its displacement is restricted only in the vertical direction in the figure, and it can move up and down without friction.

Further, from the pneumatic control valve 168 to the passage 17
A small amount of working air is introduced / exhausted into / from the cylinder chamber 174 having an extremely small volume via 2, 172a, 172b and 172c, so that the air pressure in the cylinder chamber 174 can be quickly changed, and the piston disc 1
The force acting on 30 can be changed quickly, and thus the force holding the object to be welded can be changed quickly and freely.
Further, since the diaphragm 128 has a large pressure receiving area, it is possible to urge the electrode tip 138 upward in the drawing with a force larger than that of the upper cylinder 112.

In addition, a short rod 130c is provided at the center of the piston disc 130 on the pressure receiving surface side, and a substantially spherical centering ball 130b is provided at the tip thereof. Further, a hole 180b is provided in the center of the upper surface of the member 180 forming the air passages 172a to 172c and the cylinder chamber 174, and the centering ball 13 is provided therein.
0b sits down. This allows the piston disc 13 when the lower cylinder portion 122 is assembled.
The centering of 0 becomes easy. Short rod 130c
By making the tip spherical, insertion into the hole 130b becomes easy, and even if the piston disc 130 is tilted when it is displaced, this can be allowed and smooth movement can be ensured.

FIG. 4 shows a structural example of a control system of the spot welding machine having the above structure. Here, 1 is a CP as a control means
U, which controls each unit in accordance with a processing procedure described later with reference to FIG. A ROM 3 stores programs and other fixed data corresponding to the processing procedure. 5 is CP
The RAM is provided with a work area used by U1 for work in the control process and an area used for temporary storage of various data. 7 indicates various operating conditions for the CPU 1,
For example, it is a console for setting the air pressure of each part, the current value during welding, and other necessary conditions.

Reference numeral 11 denotes a pinching sensor for detecting that the upper cylinder operates and the upper and lower electrode tips 120, 138 pinch the object to be welded. The pinch state is detected by detecting the pressure inside the cylinder chamber 152. Can be done. In addition, an optical sensor arranged at an appropriate part,
A mechanical contact sensor and other suitable forms are also possible. Further, the pinching may be detected by generating a minute voltage in the transformer 104 and detecting a minute current flowing when the electrode tips 120 and 138 contact the object to be welded. Reference numeral 13 is a lock sensor for detecting the displacement prevention state of the rod 166 by the brake shoe 162, that is, the lock state, and the lock state can be detected by detecting the pressure inside the brake chamber 156. In addition, piezoelectric elements and other suitable forms are also possible. Further, it may be a timer that generates a signal after a predetermined time from the introduction of compressed air into the brake chamber 156 until the lock is secured.

Reference numeral 21 is a transfer device for setting or removing an object to be welded at a position between electrode tips for a spot welding machine which is a stationary type in this example, and 23 is a driver thereof. However, if the operator manually performs the operation, those arrangements are unnecessary. Reference numerals 25 and 27 are drivers for sending pilot signals to the directional control valves 142 and 144 to switch the valve positions. Reference numerals 31, 33 and 168 denote cylinder chambers 152, 154 of the upper cylinder 112 and the brake chamber 1, respectively.
56 is a pressure adjusting unit for adjusting the pressure of the compressed air supplied to the cylinder chamber 174 of the lower cylinder 122 in accordance with an electric signal, and may be in the form of a pneumatic control valve. A driver 35 controls the transformer 104 to adjust the welding current value and frequency.

FIG. 5 shows an example of a welding procedure with the above-mentioned structure, and this procedure is carried out in the next step. S1: First, the object to be welded is positioned between the electrode tips 120 and 138 that are sufficiently separated by using the transfer device 21 or manually, and the welding location is set to the lower electrode tip 138.
Install on top. S2: Next, the direction control valve 142 is moved from the valve position c to the valve position a.
When switched to, the supply pressure port 146 communicates with the stroke cylinder upper chamber 152 through the valve port, while the stroke cylinder lower chamber 154 communicates with the atmospheric pressure port 150.
As a result, the piston 158 of the stroke cylinder 112 is
Receives downward force and moves downward, and both rods 16
The upper and lower electrode tips 120 and 138 attached to the tips of 6 and 130a sandwich the workpiece. S3: The sandwiching sensor detects that the upper and lower electrode chips 120 and 138 sandwich the workpiece, and outputs a signal. S4: The position of the solenoid valve 144 is changed from d to e by this signal.
, The brake chamber 156 is connected to the supply pressure port 148, the air pressure in the brake chamber rises, and the brake shoe 162 locks the rod 166 of the stroke cylinder (the upper electrode is immobile). S5: The lock sensor detects the completion of the locked state and outputs a lock signal. S6: The lock signal causes the electropneumatic pressure control valve 168 (electropneumatic proportional valve, electropneumatic servo valve, etc.) to start operating, and the working air flows into the lower cylinder chamber 174 through the passages 172, 172a, 172b, and 172c. The room pressure is controlled, and the pressure applied to the lower electrode tip 138 is started by the pressure acting on the surfaces of the diaphragm 128 and the piston disc 130 and the centering ball 130b.

With the above operation, the energization is possible. S7: A welding current is made to flow and the current value and the pressing force are freely controlled during the energization. S8: Stop energizing. S9: After the energization is stopped, the pressure is released from the lower cylinder chamber 174, and at the same time, the valve position of the solenoid valve 144 is switched from e to d to release the internal pressure of the brake chamber 156, and the brake shoe presses the rod 166 of the stroke cylinder. And unlock rod 166. S10: The valve position of the solenoid valve 142 is switched from a to c, and the piston 158 of the stroke cylinder is returned to the original position.

This completes one cycle of spot welding.

According to the above embodiments, the functions required for the spot welding machine, that is, the function of making a large stroke of the electrode so as to interpose the object to be welded between the electrodes, and the function of pressurizing the electrode when a welding current is applied are provided. By separating and, since a small force is required to simply move the welding electrode, the cylinder area of the upper cylinder 112 can be significantly reduced as compared with the conventional pneumatic cylinder for the same supply pressure. Therefore, it can contribute to air saving. Further, when the cylinder stroke is remarkably shortened and the cylinder volume is remarkably reduced, an extremely large response speed can be obtained. Therefore, the pressure applied by the lower cylinder 122 can be controlled online and in real time at the same time as the current value during spot welding. Further, since the amount of air required to generate the same pressure change in the cylinder chamber (change in cylinder force) is proportional to the cylinder volume, significantly reducing the lower cylinder volume also significantly reduces air consumption. It is possible to significantly reduce the amount of air required for pressure control.

Further, the welding force can be suppressed by increasing the pressing force during energization of the spot welding, and the scattering of sparks such as spatter is less likely to occur, and the pressing force can be adjusted to adjust the contact resistance value. It becomes possible to adjust within a certain range, and it is possible to reduce the electricity consumption. Further, by disposing the stroke mechanism and the pressure mechanism separately and dispersively, the structure of both of them, that is, the structure of the spot welding machine is simplified, which can contribute to cost reduction. Also, the cylinder with the lock mechanism can be realized by selecting from ready-made products and manufacturing only the pressurizing cylinder which is easy to process.

In the above embodiment, the pressurizing mechanism is composed of a pneumatic cylinder having a diaphragm.
You may comprise using a hydraulic cylinder, an electric actuator, etc. This also applies to the examples described below.

Further, the electrode holder may be configured to be movable in the left and right directions in the drawing, and thus may be adapted to objects to be welded having various dimensions. In this case, with respect to the upper electrode holder 116 side, the upper arm may be slidably held with respect to the upper cooling block. Alternatively, the upper beam 108 can be moved in the horizontal direction with respect to the main body 102, or a member supported by the upper beam (which can be said in the present example), as is usually performed by a machine tool or a coordinate measuring device. For example, the cylinder 112) may be supported by the upper beam 108 so as to be movable in the horizontal direction. On the other hand, for the lower electrode holder 136 side, for example, a configuration as shown in FIG. 6 can be adopted.

In the structure shown in FIG. 6, a cross spring support 133 is fixed to the lower beam 110, and one end of each of the cross springs 133a and 133b is pressed by the cross spring support 133d.
Fixed by. Each other end of the cross spring is fixed to a spring retainer 130d of a cross spring support 133c which is paired with the cross spring support 133. The lower cooling block 134 is fixed to the cross spring support 133c so that it can rotate around the intersection of the cross springs.
On the other hand, a lower arm 137 is inserted into and fixed to the lower cooling block 134, and the left and right positions thereof can be adjusted. Further, an electrode holder 136 is provided on the lower arm 137, and an electrode tip 138 is attached to the electrode holder 136.

A flat hole 131 at the right end of the lower arm 137 in the figure
The rod pin 131 is fitted to the a without any rattling in the vertical direction, so that the two can smoothly move relative to each other in the horizontal direction. The rod pin 131 is fixed to the lower piston rod 130a, and when a force corresponding to the pressure of the cylinder chamber 174 acts on the pressure cylinder disk (piston), the lower arm 137 is rotated by the lower cylinder rod 130a and the rod pin 131. Is given,
The lower electrode holder 136 and the lower electrode tip 138 at the left end are urged upward to apply pressure.

The pressurizing cylinder has the same structure as that shown in FIG. 3 and therefore its explanation is omitted. However, the structure shown in the figure is for the purpose of explanation only, and the other parts are the same as those shown in the figure. The dimensional relationship is not defined.

Although each structure is arranged on the upper surface side of the lower beam 110 in the above example, it may be arranged on the lower surface side. According to this, the upper surface of the lower beam 110 can be simplified. Further, in this case, the secondary conductor 140 may be arranged on the upper surface side if it is effective in preventing heat generation. (Embodiment 2) Next, as a second embodiment of the present invention, the pair of elements is a pair of welding electrodes, one of which is an electrode driven by the first driving means, and the other of which is a fixed electrode. An embodiment in which the displacement from the predetermined position is prevented and the one electrode is coupled to the second drive means will be specifically described.

FIG. 7 is a side view showing a schematic structure of the spot welding machine of the present embodiment, FIG. 8 is a schematic view showing a cross-sectional structure of a clamp device which is a main part thereof, and FIG. 9 is a detailed view of a lock mechanism thereof. FIG.

A stroke / pressurizing integrated cylinder 312 is fixed to the upper beam 308 of the main body 302 which is a stationary spot welding machine. At the tip of the rod, there is provided an upper cooling block which is supplied with welding current from the transformer 304 through the secondary conductor 305a and which is cooled with an appropriate cooling medium (cooling water or the like).
An upper arm 316 is attached to the block 314, and holds the upper electrode holder 318 so that the upper electrode holder 318 can be appropriately positioned. Reference numeral 320 denotes an upper electrode tip as one element attached to the holder 318. Also, 3
Reference numeral 06 is a control device.

On the other hand, a lower cooling block 134 is fixed to the lower beam 310 of the main body 302. The lower cooling block 334 holds a lower electrode holder 336 facing the upper electrode holder 318. 338 is a lower electrode tip attached to the holder 336 as the other element. It should be noted that the lower cooling block 334 is provided with an appropriate cooling medium passage (for example, a liquid passage for flowing cooling water), which is not shown, so that the welding current supplied from the transformer 304 via the secondary conductor 305b is supplied. It is possible to cool the heat generated by.

In this example, unlike the first example, the first and second driving means are provided for the upper electrode tip 320, that is, the stroke mechanism and the pressurizing mechanism are integrated in relation to the cylinder 312. As the control system, a control system similar to that shown in FIG. 4 can be adopted, and the welding process can be executed in substantially the same procedure as that shown in FIG. Hereinafter, the spot welding process in this embodiment will be described with reference to FIGS. 7 to 9 while referring to the detailed configurations of the respective parts that can be configured differently from or equivalent to those in the first embodiment.

This processing can be carried out in the following steps. 1: First, the object to be welded is positioned between the electrode tips 320 and 338 that are sufficiently separated by using a transfer device or manually, and the welding location is set on the lower electrode tip 328. 2: Next, the solenoid valve 342 is switched from the valve position c to the valve position a. As a result, the supply pressure port 346 and the stroke cylinder upper chamber 352 communicate with each other through the valve port, while the stroke cylinder lower chamber 354 and the atmospheric pressure port 350 communicate with each other, so that the piston 358 of the stroke cylinder 312 exerts a downward force. Receiving and moving downward, piston rod 36
The upper electrode tip 320 and the lower electrode tip 338 attached to the tip of 6 sandwich the welding object. 3: The sandwiching sensor detects that the upper and lower electrode tips 320 and 338 sandwich the workpiece, and outputs a signal. 4: The spring 362a is located between the spacer 362c and the shoe pushing disc 362b (a component that regulates the radial movement of the shoe), and pushes up the shoe pushing disc, the brake shoe, and the pressure piston to raise the electropneumatic pressure. When the valve 368 continues to be in the position f, the cylinder chamber 374 is at atmospheric pressure 350a, so the piston 361 of the pressurizing cylinder has reached the top. 5: In this state, the position of the solenoid valve 344 is switched from d to e by the sandwiching detection signal, the brake chamber 356 communicates with the supply pressure port 348, and the air pressure in the brake chamber rises.
The brake shoe 362 is pressed against the piston rod 366 via the seal 360, and the brake shoe and the piston rod are integrated (locked state). The lock sensor detects this locked state and outputs a lock signal. 6: The lock signal causes the electropneumatic pressure control valve 368 (electropneumatic pressure proportional valve, electropneumatic pressure servo valve, etc.) to start operating, and the passage 3
The working air flows into the cylinder chamber 374 through 74a,
The room pressure is controlled, and the pressure applied to the piston 361 starts the pressure control to the lower electrode tip 338 via the brake shoe 362 and the piston rod 366.
At this point in time, the pressurizing cylinder piston 361 has gone all the way up, so the downwardly movable amount is maximum.
At the time of stroke, it is usually set to a weak pressure,
Since a high pressing force must be generated during welding, the pressurizing cylinder piston 361 needs to be displaced downward in the case of the present embodiment, and this pressurizing cylinder can do this. If the pressurizing cylinder does not operate due to a failure, etc., the high supply pressure 34
6 should be introduced.

With the above operation, the current can be supplied. 7: A welding current is passed and the current value and the pressing force are freely controlled during the current application. 8: Stop energizing. 9: After de-energization, the pressure is released from the pressurizing cylinder chamber 374, and at the same time, the valve position of the solenoid valve 344 is switched from e to d, the internal pressure of the brake chamber 356 is released, and the brake shoe presses the piston rod 366. And unlock rod 366.

The brake shoes 362, which are segments (four in FIG. 9), receive a force in a direction away from the piston rod 366 by a shoe repulsion spring 362a set between the adjacent brake shoes 362, and the brake shoes 362 are separated from each other. There is a gap between them, so that when the piston 358 simply moves without being pressurized, unnecessary wear is avoided and sliding friction is reduced. This gap is regulated by the shoe pushing disk 362b and remains a minute amount. In the case of FIG. 8, each brake shoe 362 is separated from the piston rod 366 by utilizing the elasticity of the O-ring 362b. The lock mechanism of this example can also be adopted in the first embodiment and the third embodiment described later. 10: Switching the valve position of the solenoid valve 342 from a to c,
Return the piston 358 to its original position.

This completes one cycle of spot welding. Also, according to this embodiment, it is possible to achieve substantially the same effect as that of the first embodiment. Further, in this example, by integrating the stroke mechanism and the pressure mechanism, the device can be downsized and the rattling of the mechanism can be reduced. (Embodiment 3) Next, as a third embodiment of the present invention, a portable spot welding machine of the type having the pair of elements as a pair of welding electrodes or attached to a robot arm will be described.

FIG. 10 is a side view showing a schematic structure of the spot welding machine of the embodiment, and FIG. 11 is a schematic view showing a sectional structure of a clamp device which is a main part thereof.

A stroke between the upper arm 508 and the lower arm 510 is made by an upper pin 507 and a lower pin 507a.
A pressurizing cylinder 512 is rotatably supported around each pin, and a kickless cable having a built-in electric wire, a separator, a water cooling cavity, etc. is provided at both right ends of the upper arm 508 and the lower arm 510 in the figure. Mounting brackets 505a and 505
b is provided so that current or the like is supplied from a transformer or the like (not shown). Further, upper cooling blocks 514 and 534, to which a welding current flows and which is cooled by cooling water or the like, are attached to both left ends of the upper arm 508 and the lower arm 510 in the figure, and each block is an upper portion. Through the electrode holder (electrode rod) 518 and the lower electrode holder 536, the upper electrode tip 5
20 and the lower electrode tip 538 are held.

Here, the upper arm 508 and the lower arm 510 are connected by a pin 509, and the pin 509.
It is possible to rotate about a relative finite angle.

The pressurizing cylinder portion 522 has substantially the same structure as the cylinder 122 used in the first embodiment, and has a diaphragm 528 and a piston disc 530 attached to the diaphragm 528. Then, from the direction control valve 568 to the passages 572, 572a and 572c.
A small amount of working air is introduced / exhausted into / from the cylinder chamber 574 having an extremely small volume via the, so that the air pressure in the cylinder chamber 574 can be quickly changed, and the force acting on the piston disc 530 can be quickly changed. Therefore, the force for holding the object to be welded can be changed quickly and freely. Further, since the diaphragm 528 has a large pressure receiving area, it is possible to urge the electrode tip 538 upward in FIG. 10 with a force larger than that of the stroke cylinder portion in the lower part of the figure.

In addition, a short rod is provided at the center of the piston disc 530 on the pressure receiving surface side, and a substantially spherical centering ball 530b is provided at the tip of the rod.
Further, a hole is provided in the center of the upper surface of the member forming the air passage and the cylinder chamber 574, and the centering ball 530b is seated therein. As a result, similarly to the first embodiment, the centering of the piston disc 530 when assembling the cylinder portion 522 and the insertion into the hole portion 130b are facilitated, and even if the arm is tilted when it is displaced, this is allowed. And smooth movement can be guaranteed.

Also in this example, the control system may be substantially the same as that shown in FIG. 4, and the welding process may be executed in substantially the same procedure as that shown in FIG. In the following, the spot welding process in this embodiment will be described with reference to FIGS. 10 and 11 while referring to the detailed configuration of each part that can be configured differently from or equivalent to that of the first embodiment.

This processing can be carried out in the following steps. 1: First, a transfer device or the like is used to position the object to be welded between the electrode tips 520 and 538 that are sufficiently separated from each other. If the device of Figure 10 is attached to a robot arm, the transfer device may include the robot arm. 2: Next, the solenoid valve 542 is switched from the valve position c to the valve position a. As a result, the supply pressure port 546 and the stroke cylinder upper chamber 552 communicate with each other through the valve port, while the stroke cylinder lower chamber 554 and the atmospheric pressure port 550 communicate with each other, and the piston 558 of the stroke cylinder receives a downward force, Moving downward, both cylinder rods 530a
And 566 push the upper arm 508 and the lower arm 510, and the upper and lower electrode tips 520 and 538 attached to the tips of both arms.
And sandwich the object to be welded. 3: The sandwiching sensor detects that the upper and lower electrode chips 520 and 538 sandwich the workpiece, and outputs a sandwiching signal. 4: When the piston 558 of the stroke cylinder is generating a downward force, and the electropneumatic pressure control valve 568 continues to take the position of f, the cylinder chamber 574 has the atmospheric pressure 55.
Since it is 0b, the piston 56 of the pressure cylinder
1 goes all the way down. 5: In this state, the position of the solenoid valve 544 is switched from d to e by the sandwiching signal, the brake chamber 556 communicates with the supply pressure port 548, and the air pressure in the brake chamber rises.
The brake shoe 562 presses and locks the rod 566 of the stroke cylinder via the seal 560 (which causes the rod 566 of the stroke cylinder to become immobile). The lock sensor detects this lock and outputs a lock signal. 6: The lock signal causes the electro-pneumatic pressure control valve 568 (electro-pneumatic proportional valve, electro-pneumatic servo valve, etc.) to start operating, and the working air flows into the pressurizing cylinder chamber 574 through the passages 572 and 572a-572c. The pressure is controlled, and the upper and lower arms 508 and 510 are pushed up by the pressure acting on the diaphragm 528 and the piston disc 530.
A pressing force control for generating a rotational force about the pin 509 and pressing the upper and lower electrode chips 520 and 538 is started. Normally, a weak pressure is set during the stroke, but a high pressure must be generated during welding. Therefore, in the case of the configuration of this embodiment, the pressure piston rod 530a needs to be displaced upward. However, this pressurizing cylinder makes this possible. When the pressurizing cylinder does not operate due to a failure or the like, a high supply pressure 546 may be introduced into the stroke cylinder.

With the above operation, the current can be supplied. 7: A welding current is passed, and the current value and the pressure are freely controlled during the current application. 8: Stop energizing. 9: After stopping the energization, the pressure is released from the pressure cylinder chamber 574, and at the same time, the valve position of the solenoid valve 544 is switched from e to d to release the internal pressure of the brake chamber 556, and the brake shoe presses the rod 566 of the stroke cylinder. Unlock the rod 566 with no force applied.

Brake shoes 362, which are segmented as in FIG. 9, have adjacent brake shoes 362.
When the shoe repulsion spring 362a set between the two receives a force in a direction away from the piston rod 566, a gap is created between the two, and when the piston 558 moves only without pressurizing, it reduces unnecessary wear, Moreover, sliding friction is reduced. This gap is for the intermediate head 5
61 and a minute amount which is regulated by the indentation portion of the recess formed in the lower head 561a. In the case of this example, each brake shoe 562 is separated from the piston rod 566 by utilizing the elasticity of the O-ring 562b. 10: Switching the valve position of the solenoid valve 542 from a to c,
The piston 558 of the stroke cylinder is returned to its original position.

This completes one cycle of spot welding. Also, according to this embodiment, it is possible to achieve substantially the same effect as that of the first embodiment. In this example, the stroke mechanism and the pressurizing mechanism are separated and combined, but an integrated structure may be used as in the second embodiment.

Needless to say, the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the basic idea of the present invention. For example, various types of spot welders can be used, and the application target of the clamp device is not limited to the spot welder. For example, the clamp device of the present invention can be applied to a device that clamps and conveys an object, a device that stamps an object, and the like.

[0058]

As described above, according to the present invention,
In a clamping device that includes a pair of elements that can be closely opposed to each other, and uses a clamp device to make a stroke at a position where they are closely opposed to each other and clamp them, and makes a large stroke of the elements in a clamping device that requires an operation to press each other when they are closely opposed to each other. By separating the function and the function of pressurizing, it is possible to significantly reduce the cylinder area of the pneumatic cylinder that makes the stroke, because a small force is required when the element is simply moved, and thus it is possible to contribute to air saving. it can.

Further, in the spot welding machine to which the clamp device is applied, it is possible to press the welded article by increasing the pressing force during energization of the spot welding, so that sparks such as spatter are less likely to be scattered. In addition, the applied pressure can be adjusted to adjust the value of the contact resistance within a certain range, and the power consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of a spot welding machine according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing a cross-sectional configuration and the like of a clamp device which is a main part of FIG.

FIG. 3 is a schematic cross-sectional view showing an enlarged main part on the second drive means side of the first embodiment.

FIG. 4 is a block diagram showing a configuration example of a control system of the spot welding machine of the first embodiment.

FIG. 5 is a flowchart showing an example of a welding processing procedure of the first embodiment.

FIG. 6 is a side view showing a modified example of the configuration of the lower cylinder portion in the first embodiment.

FIG. 7 is a side view showing a schematic configuration of a spot welding machine according to a second embodiment of the present invention.

FIG. 8 is a schematic diagram showing a cross-sectional configuration and the like of a clamp device that is a main part of FIG.

9 is a cross-sectional view showing details of the lock mechanism in FIG.

FIG. 10 is a side view showing a schematic configuration of a spot welding machine according to a third embodiment of the present invention.

11 is a schematic diagram showing a cross-sectional configuration and the like of a clamp device which is a main part of FIG.

[Explanation of symbols]

102, 302 Welder body 104, 304 Welding transformer 105a, 105b, 305a, 305b, 505a,
505b Secondary conductor 106, 306 Control device 108, 308 Upper beam 110, 310 Lower beam 112, 312, 512 Cylinder 114, 134, 314, 334, 514, 534 Cooling block 118, 136, 318, 336, 518, 536 Electrode Holder 120, 138, 320, 338, 520, 538 Electrode tip 122, 522 Pressure cylinder 128, 528 Diaphragm 130, 530 Piston disc 130a Lower rod 130b Centering ball 140, 540 Eden spring 142, 342, 542 Directional control valve (3 Position solenoid valve) 144, 344, 368, 544, 568 Directional control valve (two-position solenoid valve) 146, 148, 346, 348, 546, 548 Supply pressure port 150, 150a, 350, 350a, 550, 55 0
a atmospheric pressure port 152, 352, 552 cylinder upper chamber 154, 354, 554 cylinder lower chamber 156, 356, 556 brake chamber 158, 358, 558 cylinder piston 162, 362, 562 brake shoe 166, 366, 566 piston rod 168 electric Air pressure control valve 172, 172a to 172c, 572, 572a to 57
2c Air passage 174, 574 Lower cylinder chamber 175, 575 Diaphragm holder

Claims (5)

[Claims] 1. A first drive unit in the form of a pneumatic actuator, which is capable of being close to each other, and moves at least one of a pair of elements that clamps an object in the close facing state toward a predetermined position that is close to each other, When a pair of elements are closely opposed to each other, a blocking unit that blocks a displacement of the pair of elements in a direction opposite to the moving direction, and at least one of the pair of elements at the predetermined position are moved by the first driving unit. A clamping device comprising: a second drive means for urging in a direction of pressurizing toward the other side with a force larger than the force for performing. 2. One of the pair of elements is an element driven by the first drive means to prevent the displacement of the element from the predetermined position, and the other of the pair of elements is the second element. The clamp device according to claim 1, wherein the clamp device is driven by a drive means. 3. One of the pair of elements is an element driven by the first drive means, and the other is a fixed element to prevent the displacement from the predetermined position, and to prevent the displacement from occurring at the predetermined position. One element is the second
The clamp device according to claim 1, wherein the clamp device is coupled to a driving means. 4. The clamp device according to claim 1, wherein the second drive means is composed of a pneumatic actuator having a pneumatic cylinder. 5. A clamp device according to any one of claims 1 to 4, wherein the object is an object to be welded, and the pair of elements are electrodes for passing a welding current. Spot welder.