JPH0351507B2 - - Google Patents

Description

[Detailed description of the invention] <Industrial application field> This invention relates to a multi-point welding robot.

<Conventional technology> Conventional spot welding robots (manipulators)
A spot welding gun is attached to the end of the arm and can be moved up, down, forward, backward, left, right, and rotated in three axes, that is, six axes.The gun can be used to move objects to be welded in front of the robot using teaching, playback methods, etc. Weld each welding position one after another.

<Problems to be solved by the invention> Conventional welding robots operate a single welding gun to weld the welding points one by one, so it takes time to move the gun to an adjacent welding position while welding one product. It is.

This travel time is much greater than the net welding time. To eliminate travel time, a well-known multi-point welding machine can be used. Can weld multiple points at the same time.

However, all multi-point welding machines are made specifically for one type of product (steel plate parts). In order to weld a different product, it is necessary to replace the jig, gun, and lower electrode with the upper electrode gun and lower electrode for that product, and to install a dedicated machine for that product. Of course, when performing multi-point welding on similar products, it is sometimes done by slightly moving or tilting one gun, but this is of course limited to similar products and is slightly different. Shaped products were not covered.

This invention provides each upper electrode gun of a multi-point welding machine with the function of a conventional spot welding robot, that is, the automatic adaptation function of setting the welding gun to the welding position of the product by memory, and cooperates as a group of welding robots. This idea was based on the idea that it would be possible to weld products all at once.

<Means for Solving the Problems> The multi-point welding robot of the present invention has all the lower electrodes necessary for multi-point welding of multiple types of press-formed steel plate products fixed at their respective positions, heights, and orientations. An electrode stand, an upper electrode machine frame installed opposite the lower electrode stand, and a surface of the machine frame facing the lower electrode stand divided into a plurality of sections, each section having at least one set. A welding gun mounting plate with a three-axis drive and guide mechanism, a welding gun with an upper electrode whose base end is fixed to each of the above mounting plates, and each gun can be pressurized and energized, and the product. The present invention is characterized by comprising a comprehensive control device which moves each of the above-mentioned mounting plates to corresponding memorized positions and issues a welding command only to the gun with the upper electrode at the required position when the type of the gun is specified. Preferably, the triaxial drive mechanism is characterized in that the welding pressure direction is driven by fluid pressure, and the other two axial directions are driven by screws.

<Function> Conventional welding robots use X-type guns, C-type guns, etc.
Generally, a type of gun is used that clamps the welded part of the product with both electrodes, and the heavy gun is attached to the end of a long arm and swung around, and the gun can be moved in three axes: up and down, back and forth, left and right, as well as in each axis. Because it also rotates around it, it is large, heavy, and expensive.

On the other hand, the multi-point welding robot of this invention basically uses a single gun with only the upper electrode attached, and the lower electrode is placed on the lower electrode stand below the product introduction path.
Keep everything fixed. Since the lower electrode can be connected directly to the secondary current circuit without being attached to the gun, a simple electrode piece can be used to meet all the needs of the expected product, without having to change its location every time the product changes like the upper electrode. It is sufficient to place it in a certain location. Now the robot is operated by a light single gun, but the upper electrode machine frame is divided into multiple sections, and each section is equipped with a gun mounting plate and its three-axis drive and guide mechanism. Each welding part is divided, and multiple guns with upper electrodes are attached to each gun mounting plate, and welding commands are issued only to the gun in the required position, reducing the movement range of the gun and its mounting plate. , the route of travel has been simplified.

A single gun receives welding pressure reaction force, so it requires a strong support mechanism, but the upper electrode machine frame installed directly above or next to the lower electrode stand is in a position where it can easily receive the pressure reaction force. Therefore, the part that touches the robot arm only needs to transmit force between the gun and the machine frame.

Since the shared space of each gun is small, the guide drive mechanism that moves it is also small, but it still has the necessary control device to function as a single welding robot. Each control device is integrated into a comprehensive control device,
As a whole, each part of the expected product is to be welded, each gun is placed in the welding position, and the welding is carried out all at once.

If the product is box-shaped, the bottom side of the box can be used literally as upper and lower electrodes, but when the side panels of the box are welded horizontally, they are also referred to as upper and lower (more precisely, inner and outer) electrodes. In this case, the upper electrode is attached to a horizontal gun placed on the machine frame right next to the lower electrode stand.

In this way, the bottom of the box is welded with guns installed on the machine casing directly above the lower electrode stand, and the side plates of the box are welded on the machine casing right next to it, making it possible to weld in all directions with a single conventional gun. Unlike when welding, there is no need to change the direction of the gun in a difficult manner, and in most cases, it is sufficient that each gun mounting plate is movable in three axes.

<Embodiment> FIG. 1 is a front view of one embodiment of the present invention, FIG. 2 is a side view of the upper electrode side, and FIG. 3 is a front view of the main part of the drive mechanism. In the figure, 1 is a simplified lower electrode stand, E is a lower electrode, 10 is a machine frame for an upper electrode,
E' is the upper electrode, G is the welding gun, 11 is the gun mounting plate, 12 is its guide and drive mechanism, and this is the machine frame 1.
0 Two dovetail cross-section rails extending to the left and right of the bottom surface 1
3. The three transverse plates 14 are suspended by holding this rail 13 in their mouths and can slide left and right. Both ends of the machine frame 1 are supported between the two rails 13, 13 on the lower surface of the machine frame 10.
0 upper surface, each drive screw 16 turned by each servo motor 15, these screws 16 having a female thread, a passive block 17 of each transverse plate 14,
Also, each vertical movement plate 18 is engaged with the lower edge of the left and right leg plate 14a on the lower surface of the transverse plate 14 with a dovetail cross section and is suspended, and each servo that turns the drive screw 19a to vertically move (back and forth movement) the vertical movement plate 18. It consists of a motor 19, a passive block 20 on the vertical movement plate 18 side having a female screw engaged with the drive screw 19a, and an elevating part 21 hanging down from the lower surface of each vertical movement plate 18, and the above-mentioned gun is attached to the lower part of this elevating part 21. A plate 11 is attached.

The elevating part 21 is shown in FIG. 2 with the cover removed. In this example, guide rods are set up on the left and right sides of the air cylinder 21a, and when the valve is opened, the mounting plate 11 and the gun G fall due to gravity and reach the upper electrode E'. The gun G rests on the welded part of the product and stops, and after stopping, the internal pressure of the cylinder 21a is increased to such an extent that the gun G is not pushed up by the welding pressure reaction force. Moreover, it is also by this cylinder 21a that the gun G is pulled up after welding.

To briefly describe the operation of this embodiment and the function of the integrated control device, first, the product (steel plate member) W is
As shown in the figure, when placed on a predetermined lower electrode E, the welding position will be placed closely on the upper surface of the electrode E. When automatically feeding the product W, a positioning pin and a holding mechanism are added, but these are omitted in the figure.

Product W is one of several types of products stored in advance in the general control device.If the product is to be automatically fed, the automatic detection mechanism is used, otherwise, the type is specified to the general control device manually. As previously taught, each servo motor 15,
19, each of the three gun mounting plates 11 is moved by a required distance vertically and horizontally from the reference position (or current position).

When the gun mounting plate 11 comes directly above the respective predetermined positions, the solenoid valve to the air cylinder 21a of the elevating section is activated to lower the mounting plate 11 and the gun G by their own weight.

Now, as previously designed, the required gun among the three guns G on each mounting plate 11 stops with the upper electrode E' placed on the intended welding position of the product W.

Therefore, after commanding the above-mentioned solenoid valve to generate an internal pressure equivalent to the welding pressure force in the air cylinder 21a of the lifting section, each gun G is ordered to perform welding operation all at once or in stages. welding is completed.

Then, the solenoid valve is switched and the gun G is pulled up to the standby position by the lifting air cylinder 21a to wait for the product to be replaced, or alternatively, the gun position may be changed immediately and another location of the same product may be welded again.

Next, an embodiment in which the upper electrode E' is pressed sideways instead of downward will be described with reference to FIG. The horizontal lower electrode E at the right end of the lower electrode stand 1 in Figure 1 hits the back side of the product, and the upper electrode of the horizontal gun G in Figure 4 is connected thereto.
This means that E' is forced.

This horizontal multi-point welding robot has a lower electrode stand 1.
The guide and drive mechanism 12 for the gun mounting plate 11 are mounted on a machine frame 10' installed right next to the machine frame 10' as a base. The outline of the guide drive mechanism 12 is as follows.
A transverse table 23 that slides on a dovetail rail 22 for preventing floating on the upper surface of 0' and moves in the lateral direction (welding pressure direction), a fluid pressure cylinder 24 that drives this, and an upper and lower horizontal dovetail on the front surface of the transverse table 23. A vertically moving plate 26 that moves horizontally along the rail 25, a servo motor 27 for driving it, and a servo motor 2 that drives the gun mounting plate 11 that moves up and down along the front surface of the vertically moving plate 26.
8. In order to reduce the burden of driving the screw, the gun G
A plurality of sets of balance air cylinders 29 and the like whose mounting portions are slightly pulled up are lined up on the machine frame 10'. Of course, there will only be one transverse platform 23,
between the mounting plate 11 of each vertical movement plate 26 and the gun G
The elevator unit 21 shown in the figure may also intervene.

After the servo motors 27 and 28 adjust and move the gun mounting plate 11 in the horizontal and vertical directions by screw driving,
The fluid pressure cylinder 24 advances the gun mounting plate 11 in the welding pressurizing direction, and when the upper electrode E' at the tip of the gun reaches the position where the product is to be welded and the pressurizing force increases, a welding command is issued to the gun G.

After welding, the gun G is pulled back by the hydraulic cylinder 24.

In both welding from above in Figure 1 and welding from the side in Figure 4, fluid pressure is used instead of screws for positioning in the direction in which the welding pressure reaction force is received. The screw drive mechanism, which is important for precise positioning, is not subjected to pressure reaction force due to the guide mechanism such as a rail that runs along the screw drive mechanism. This embodiment utilizes the characteristic of spot welding in that there is no need for precise positioning in the welding pressure direction, so movement by fluid pressure is sufficient.

However, the guide and drive mechanism for the three-axis movement of the gun mounting plate of the present invention is not limited to the two-axis directions of the above embodiment, which are screws, and the pressurizing direction, which is fluid pressure. Needless to say, it can be designed to In short, any design is sufficient as long as each gun mounting plate can be moved in three axes and there is no risk of reducing positioning accuracy due to welding pressure.

It is also easy from the prior art to add rotational motion to each axis as needed, in addition to simple three-axis movement.

On the other hand, depending on the shape of the product, it is of course possible to omit part of the guide and drive mechanism.

<Effects of the Invention> This invention has significantly changed the concept of spot welding robots, which were traditionally designed to have an X-shaped or G-shaped spot welding gun attached to the end of its arm, weld at one point, and then move. . It consists of a lower electrode stand that holds all the lower electrodes that are applied to the back side of the welding parts of various products, a machine frame for the upper electrode directly above or beside it, and multiple gun mounting plates, guides, and drive mechanisms installed on this. As a result, we have developed a new type of spot welding robot that can be called a collective spot welding robot, in which multiple robot guns work together to pressurize and weld the welded part of a product.

Since the types of products to be welded are limited in mass production, it is possible to tell the welding positions for the types suitable for this new type of robot in advance, so that the integrated control system can adjust the welding positions according to the types of products that are being fed one after another. Since the machine automatically places each gun in the welding position and performs the welding process, the greater the number of guns used, the greater the productivity improvement.

Furthermore, in this invention, the gun mounting plate to which multiple guns with upper electrodes are attached is moved only within the assigned range, and a welding command is issued only to the guns that have arrived at the required position, so that the guide and drive mechanism that corresponds to the robot arm is Since it requires a minimum number of robots, it becomes a well-organized robot assembly.

Furthermore, as a triaxial drive mechanism for the gun mounting plate,
The robot is driven by fluid pressure only in the welding pressure direction and screw-driven in the other direction, which precludes the common sense of using servo motors and screw drive mechanisms in all three axes as a robot.
The drive mechanism is ideal for two-axis directions, which are necessary for precise positioning, and one-axis directions, which do not require precision but must be able to withstand welding pressure reaction force, increasing positioning accuracy and extending life.

[Brief explanation of drawings]

Figure 1 is a front explanatory view of one embodiment of this invention;
Figure 3 is a side view of the main parts, Figure 3 is an enlarged diagram of the guide and drive mechanism shown in Figure 1, and Figure 4 is an illustration of the present invention when the upper electrode machine frame is located right next to the lower electrode stand. FIG. 3 is a front view of the embodiment. In the figure, 1 is a lower electrode stand, 10 is a machine frame for an upper electrode, 11 is a gun mounting plate, 12 is its guide and drive mechanism, E and E' are electrodes, and G is a welding gun.

Claims (1)

[Claims] 1. All the lower electrodes required for multi-point welding of multiple types of press-formed steel plate products at their respective positions,
A lower electrode stand whose height and direction are fixed, an upper electrode machine frame installed opposite to this lower electrode stand, and a surface of this machine frame that faces the lower electrode stand divided into multiple sections, and each A set of welding gun mounting plates with drive and guide mechanisms in at least three axes are arranged in each compartment, and multiple guns are fixed at their base ends to each of the above mounting plates, making it possible to pressurize and energize each gun individually. a welding gun with an upper electrode, and a comprehensive control device that, when the type of product is specified, moves each of the above-mentioned mounting plates to corresponding memorized positions and issues welding commands only to the gun with the upper electrode in the required position. A multi-point welding robot characterized by having the following. 2. The multi-point welding robot according to claim 1, wherein the three-axis drive mechanism is driven by fluid pressure in the welding pressure direction and driven by screws in the other two axes. .