JPH0957458A - Supply of welding parts and spot welding system therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a cycle time of a work assembling work by lapping (synchronizing) each operation of work carry-in/carry-out, supplying of a welding parts and welding. SOLUTION: In a supporting device 6 for parts supplied to the welding position between electrodes by holding welding parts at the tip part of a spindle from a supplying position for parts intersected with a reciprocating way of the spindle by advancing the spindle from a driving source 14, to join both parts by supplying the electric power under pressurizing, an electric motor is used as the driving source 14 and the rotating movement of the electric motor is converted into a straight line movement and a stroke and a moving speed of the spindle are made to be changable in stepless. By this system, the movements by each device of a work carrying robot 1, supplying device 6 for the parts and spot welder 4 are lapped and the shortening of the work assembling tact is realized and the supplying miss of the parts can be detected and the detective welding is prevented and the noise of exhaust gas from the driving source caused by the supplying of the parts is eliminated and the maintenance of working environment is established.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to welding for supplying and joining to a work welding position between upper and lower electrodes of a spot welding machine by using a spindle for advancing small welding parts such as welding nuts and welding bolts. Regarding the system.

[0002]

2. Description of the Related Art Conventionally, as a method of assembling an automobile part, there are two typical methods of assembling by spot welding and welding by welding a welding nut to a panel and tightening a nut / bolt. With regard to the former spot welding, welding guns by robots are becoming electric.

However, in the latter method of assembling a welding nut, an air cylinder is used to drive the electrodes of a stationary spot welding machine and to drive a spindle of a component supply unit called a nut feeder. Therefore, in the sequence of movement of the work by the work transfer robot, operation of supplying the welding nut to the work, and electrode pressing operation of the welding machine, each device must move within the operation time before moving to the next operation. However, it is difficult to significantly reduce the cycle time by synchronizing and wrapping the operation of each device.

The details of the prior art will be described by using the system conceptual diagram of the present invention of FIG. 1 and the component supply unit configuration diagram of the present invention of FIG. 2 together. When the work transfer robot 1 is automatically operated, it is attached to its wrist shaft. The panel 3 (hereinafter, referred to as a work) held by the work gripping tool 2 thus obtained is set and held on the lower electrode 5 of the stationary spot welding machine 4. in this case,
A guide pin, which is internally provided so as to be retractable from the electrode, is inserted into the positioning hole of the work and positioned.

Subsequently, the welding nut 9 is attached by the spindle 8 (see FIG. 2) of the component supply unit 7 of the component supply device 6.
(Welding part) is supplied onto the work 3 above the lower electrode 5.

Simultaneously with the completion of the component supply, only the spindle 8 of the component supply unit 7 immediately retreats to the original position to prepare for the next supply.

Next, the pressure unit 1 of the spot welding machine 4
At 0, the upper electrode 11 pressurizes the welding nut 9 and the work 3 to energize them for welding.

When the welding is completed, the upper electrode 11 is opened, and the work transfer robot 1 removes the work 3 from the lower electrode 5 upward, transfers it to the next welding position, and sets it on the lower electrode 5. The above process is one cycle.

The welding nut 9 is attached to the parts feeder 12 (see FIG. 1).
(See) and feed through the shooter rail A. A locking plate 13 is provided at the terminal end a of the shooter rail A so as to be openable and closable, and is always biased by a spring in a closing direction. The welding nut sent to the end portion of the shooter rail stands by on the locking plate 13 at the end portion a.

Conventionally, a pneumatic cylinder is connected to the end of the rail as a drive source 14 of the supply unit, and a spindle 8 is connected to its piston rod. A nose pin 15 is provided at the tip of the spindle 8. The nose pin 15 is inserted into the nut diameter by advancing the spindle 8 by the cylinder, and the welding nut 9 is inserted from the terminal end a of the shooter rail A to the opening / closing plate 13. Press to open and supply to the lower electrode 5 as it is.

In this case, the spindle 8 is magnetized by the magnet 16, the welding nut 9 is attracted to the tip surface of the spindle 8 and the position is held by the nose pin 15. And at the position where the welding nut 9 has advanced to just before the lower electrode 5,
The excitation of the magnet 16 is cut off, the magnetic attraction force of the spindle 8 is lost, and the welding nut is removed from the tip of the magnet 8 and inserted into the guide pin of the lower electrode 5 and set on the work.

[0012]

The conventional parts supply system using the above pneumatic cylinder has the following problems. Since the drive source 14 of the component supply unit is a pneumatic cylinder, the supply speed by the spindle is limited. Pneumatic cylinders have a constant stroke, and since it is not possible to stop the spindle in the middle, it always takes time. When the work transfer robot and the stationary spot welding machine are linked, the operation with each device cannot be lapped (synchronized), so the cycle time cannot be shortened. Pneumatic cylinders are a cause of work environment destruction due to noise caused by air exhaust. It is difficult to detect abnormalities such as supply errors instantly during the operation of supplying components.

As described above, conventionally, most of the driving sources for supplying small parts such as welding nuts use pneumatic cylinders, so that it is difficult to stop in the middle of the supply stroke. Therefore, the welding nut 9 cannot be brought close to the welding position in advance while being overlapped with the conveying operation of the work 3. Also, there is a limit to the supply speed. It is not possible to expect a significant reduction in tact with the current pneumatic cylinders.
Also, noise is generated due to the exhaust noise of the air switching valve for the pneumatic cylinder and the impact noise of the piston at the stroke end. The present invention is intended to solve many of the problems inherent in these conventional techniques.

[0014]

Therefore, the present invention has taken the following technical means as means for solving the above problems.

That is, firstly, an electrode for advancing and advancing the spindle by a driving source to hold a welded part at the tip of the spindle from a part supply position intersecting with the reciprocating path of the spindle, and pressing and energizing the welded part. In a component supply device for supplying to a welding position between, an electric motor is used as the drive source, and the rotational movement of the electric motor is converted into a linear movement to continuously control the stroke amount and / or the operating speed of the spindle. The feature is that it has been made possible.

The other is a work transfer robot that grips a work via a work support and carries it in or out of a welding position of a spot welding machine, and / or a work point at a work position between electrodes. The electric pressure type spot welder that pressurizes and energizes to join the parts, and the electric motor advances the spindle to hold the welded part at the tip of the spindle from the part supply position that intersects the reciprocating path of the spindle and applies this. The cycle time can be shortened by synchronizing the respective operations of these three parts with the component supply device that supplies pressure and current to the welding position between the electrodes to be joined, and performing the lapping operation.

Still another one is a work transfer robot which grips a work via a work support and carries it in or out of a welding position of a spot welding machine, and presses and energizes the work point position between the poles. And the electric pressure type spot welding machine for joining and welding, the spindle is moved forward by the electric motor and the welding part is held at the tip of the spindle from the part supply position intersecting the reciprocating path of the spindle, and this is pressurized and energized. In a sequence control method of a component supply device that supplies a welding position between electrodes to be joined, the control of the robot, the control of the spot welder, and the control of the component supply device are each control devices, and the control of the component supply device is performed. Select the stroke amount of the spindle by the electric motor from a plurality of stroke amounts preset by an external signal from the robot controller. Characterized in that the so that.

Furthermore, an electric pressure type spot welding machine using an electric motor as a drive source of electrodes, a work transfer robot for loading and unloading a work to and from the welding position of the spot welding machine, and an electric motor for moving a spindle forward. In the sequence control device of the component supply device, which holds the welded component at the tip of the spindle from the component supply position that intersects the reciprocating path of the spindle, and supplies the welded component to the welding position between the electrodes to be pressed and energized for joining, The control of the spot welding machine, the control of the robot, and the control of the electric component supply device are used as respective control devices, and the drive controller of the electric motor of the component supply device and the switch of the welding power source of the welding machine are used. It is characterized in that it is built in the same control device as the welding timer to be controlled.

According to the first to third aspects of the present invention, by using the component supply unit by the electric motor, the intermediate stop of the spindle and the operation speed control can be performed steplessly, and the work loading / unloading operation and the components can be performed. The supply and welding operations can be continuously rubbed with the required minimum distance, and the cycle time can be greatly shortened.

Furthermore, if a parts supply unit using an electric motor is used, exhaustion, noise, etc. can be completely eliminated, and environmental maintenance can be enhanced, and abnormalities such as parts supply errors can be detected from the stroke displacement of the spindle at the time of parts supply. Is automatically enabled, and welding defects can be prevented.

According to claims 4 and 5, by separating the handling of all 6 axes of the work transfer robot from the electrode pressing force of the 7th axis, the positioning operation can be precisely controlled and the welding quality can be improved. Contribute. Further, the stroke amount and speed of component supply can be arbitrarily set by the same controller as a welding timer that sets welding conditions such as welding pressure, welding current value, and energization time.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing the entire work transfer robot, stationary spot welder, and control system equipment for a component supply device according to the present invention. FIG. 2 is a sectional view showing the structure of the component supply unit according to the present invention. FIG.
Shows an entire sequence program of a control system for a work transfer robot, a stationary spot welder, and a component supply device according to the present invention.

An embodiment of the present invention will be described with reference to the above-mentioned attached drawings. The same components as those of the conventional device described above are designated by the same reference numerals.

The system of the present invention is not limited to this embodiment, and may be, for example, a combination of a work transfer robot, a stationary spot welder, and a component supply device.

As can be seen from the conceptual diagram of FIG. 1 and the sequence of FIG. 3, the work transfer robot 1 is automatically operated so that the work 3 held by the work gripping tool 2 attached to the wrist shaft of the work transfer robot 1 is stationary. 4 on the work 3 above the lower electrode 5.

In this case, only the spindle 8 of the component supply unit 7 is immediately retracted to the original position, but when the spindle begins to retract, the spot welding machine 4 synchronizes with the operation of the spindle to the extent that it does not interfere with the spindle 8. The upper electrode 11 is pressurized by the pressure unit 10 and a welding current is applied to weld the welding nut 9 and the work 3.

After the welding is completed, when the upper electrode 11 starts the opening operation, the work 3 is removed from the lower electrode 5 and moved to the next welding position so that the work transfer robot 1 does not interfere immediately. Set on the guide pin. The above is one cycle. By repeating this operation, the spindle 8 starts to move forward while the transfer robot moves the work to the welding position and waits midway while the work is set to the electrode position, and the welding nut 9 is set at the same time as the work setting. When the upper electrode starts to descend while the spindle is retreating and contacts the welding nut 9, pressure energization is performed to perform welding.

The one-cycle indicated by the one-dot chain line of * in FIG. 3 is an example in which an electric motor is used to drive the electrode of the stationary spot welding machine, and the cycle time of the conventional method shown in FIG. A comparison shows that one cycle can be shortened.

FIG. 2 shows the internal structure of the component supply unit 7 of the component supply device 6. Welding nut 9 is parts feeder 1
2 (see FIG. 1), the openable and closable locking plate 13 stands by at the terminal end a of the shooter rail A which is biased by a spring in the closing direction.

Various electric motors 21 are used as the drive source of the component supply unit 7. The hollow electric motor 21 described in this example has the ball nut 2 on the rotor side thereof.
2 is fixed. A ball spline nut 23 is fixed to the fixed side to prevent the ball screw 24 with a spline from rotating. The spindle 8 is connected to the end portion of the ball screw 24 with a spline that penetrates through the both nuts.

Rotation of the electric motor 21 causes rotation / linear motion conversion by the ball nut 22, the ball screw 24 with spline, and the ball spline nut 23, and the welding nut 9 is attached to the shooter rail by the spindle 8 provided with the nose pin 15 at the tip. The locking plate 13 from the end
Push to open and supply to the work welding position of the lower electrode 5 (see Fig. 1).

During the stroke, the spindle 8 is magnetized by the magnet 16, the welding nut 9 is attracted to the end face of the spindle 8 and the position is held by the nose pin 15.

Then, the welding nut 9 is attached to the lower electrode 5 (see FIG.
(See (1)), the magnetizing force of the magnet 16 is cut off at the position where the magnet 16 has advanced, and the nut attracting force becomes ineffective. The welding nut 9 is disengaged from the spindle 8 and set on the guide pin of the lower electrode for positioning the work.

Regarding the control of the component supply unit, the following three items are related to the driving by the electric motor 21.
The street was tried. First, the above control uses the drive control of the seventh axis of the work transfer robot. The second is an independent controller for the component supply unit, which commands the servo controller of the component supply unit by an external signal from the work transfer robot. The third one is the same independent control device as the second one, but the stroke amount of the component supply unit is set in advance to about 15 steps, and it is selected from this by an external signal (the stationary spot welding machine is an electric pressurization type). In this case, this control may also be used).

[0035]

As described above, the welding system according to the present invention has the following effects. By using an electric motor as a drive source for the component supply unit, the intermediate stop of the spindle and / or the supply speed can be controlled steplessly. Therefore, the cycle time can be further shortened in the assembly process by each operation of the work transfer robot, the stationary spot welding machine, and the component supply device. Since there is no exhaust noise of the air pressure switching valve or impact noise of the cylinder piston, a silent effect can be obtained on the assembly line and the work environment can be improved. It becomes possible to automatically detect an abnormality from the displacement of the stroke of the spindle at the time of parts supply. In addition to welding nut supply, it can also be applied to bolt supply and parts feeders for other small parts. Especially in nut welding, the presence or absence of a welding nut, the front and back of the welding nut, the inclination of the supply parts, and the welding nut upset amount are also parts. Can be detected at the same time as supply,
Welding defects can be prevented in advance, which greatly contributes to the improvement of welding quality. For the servo controller of the electric motor of the parts supply unit, by using the 7th axis of the work transfer robot,
It is easy to synchronize each movement of robot movement and parts supply, and lap control becomes easy. Especially, when the component supply unit is controlled independently, it is easy to support any system. By setting about 15 different strokes of the spindle in the independent control unit of the component supply unit, fine sequence control can be performed with the minimum required distance in the work assembly process, and loss time can be dramatically reduced. Further, by incorporating the servo control device into a welding control device (timer device) of a stationary spot welding machine and performing dual axis control, the cost can be significantly reduced and the storage space can be saved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an overall appearance of a work transfer robot, a stationary spot welding machine, and a component supply device of the present invention.

FIG. 2 is a cross-sectional view showing an internal structure of a component supply unit of the component supply device according to the present invention.

FIG. 3 shows a sequence program of a combination system of a work transfer robot, a stationary spot welder, and a component supply device according to the present invention.

[Explanation of symbols]

 1 Work Transfer Robot 2 Work Gripping Tool 3 Work (Panel) 4 Stationary Spot Welder 5 Lower Electrode 6 Component Supply Device 7 Component Supply Unit 8 Spindle 9 Welding Component (Welding Nut) 10 Pressure Unit 11 Upper Electrode 12 Parts Feeder 13 Locking plate 14 Drive source 15 Nose pin 16 Magnet 21 Electric motor 22 Ball nut 23 Ball spline 24 Ball screw with spline A Shooter rail a Terminal part

Claims (5)

[Claims] 1. A welding position between electrodes for holding a welded part at a tip of the spindle from a part supply position where a spindle is moved forward by a drive source and intersecting a reciprocating path of the spindle, and pressing and energizing the welded part. In the component supply device for supplying to the above, an electric motor is used as the drive source, and the rotational movement of the electric motor is converted into a linear movement so that the stroke amount and / or the operating speed of the spindle can be controlled steplessly. An electric parts supply system characterized by. 2. A work is gripped via a work support,
A work transfer robot that carries this in or out of the welding position of the spot welding machine, and / or an electric pressure type spot welding machine that presses and energizes the work point position of the work between the electrodes to join them, and an electric motor Holds the welded part at the tip of the spindle by moving the spindle forward from the part supply position intersecting the reciprocating path of the spindle.
The cycle time is shortened by synchronizing each of these three operations with the component supply device that supplies this to the welding position between the electrodes that are pressed and energized to join them, and perform the lapping operation. Spot welding system for supply parts. 3. A work is gripped via a work support,
A work transfer robot that carries this in or out of the welding position of the spot welding machine, an electric pressure-type spot welding machine that presses and energizes the welding point of the work between the electrodes between the electrodes, and a spindle by an electric motor. A sequence control method of a component supply device that advances a component to hold a welded component at the tip of the spindle from a component supply position that intersects the reciprocating path of the spindle, and supplies the welded component to a welding position between electrodes to be joined by applying pressure and electricity. 2. The spot welding system according to claim 1, wherein the stroke amount and / or operation speed of the spindle by the electric motor of the supply device is controlled steplessly by using the seventh axis of the independent control device of the robot. 4. A work is gripped via a work support,
A work transfer robot that carries this in or out of the welding position of the spot welder, an electric pressure type spot welder that presses and energizes the welding point position of the work between the electrodes, and the spindle is advanced by an electric motor. In the sequence control method of the component supply device, the welded component is held at the tip of the spindle from the component supply position intersecting with the reciprocating path of the spindle, and is supplied to the welding position between the electrodes to be joined by applying pressure and current to the welded component. The control of the robot, the control of the spot welding machine, and the control of the component supply device are used as respective control devices, and the stroke amount of the spindle by the electric motor of the component supply device is preset from an external signal from the control device of the robot. The spot welding system is characterized in that a plurality of stroke amounts are selected. 5. An electric pressure type spot welding machine using an electric motor as a drive source of electrodes, a work transfer robot for loading and unloading a work to and from a welding position of the spot welding machine, and an electric motor for moving a spindle forward. In the sequence control device of the component supply device, the welding component is held at the tip of the spindle from the component supply position that intersects the reciprocating path of the spindle, and the welding component is supplied to the welding position between the electrodes to be pressed and energized for joining. The spot welding machine control, the robot control, and the electric component supply device control are used as respective control devices, and an electric motor drive controller of the component supply device and a welding power source switch of the welding machine are controlled. Spot welding system built in the same control device as the welding timer.