JPH0259037B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a projection welding machine, and more particularly to a projection welding machine suitable for welding a nut to a panel without a nut pilot hole.

[Background of the invention]

Conventionally, as a projection welding machine for welding a nut onto a panel, the one disclosed in Japanese Utility Model Application Publication No. 56-6580 is known. This is done by installing magnetic adsorption means on the upper electrode that moves up and down, and lowering the upper electrode while adsorbing the nut to a desired position on the panel installed on the lower electrode side, thereby simultaneously positioning and welding the nut. It is something.

However, with the conventional welding machine described above, deviations tend to occur in the suction position between the nut and the upper electrode, making it impossible to accurately align the position with respect to the panel on the lower electrode, resulting in poor welding positioning accuracy. Ta. In this regard, it may be possible to provide a guide means for nut positioning on the nut suction side electrode, but
A problem arises in that the welding current is diverted through the guide means during welding, resulting in a reduction in welding quality. Furthermore, conventional welding machines cannot accurately position nuts unless the panel has a nut pilot hole, and it is therefore extremely difficult to weld a nut to a panel without a nut pilot hole.

[Purpose of the invention]

An object of the present invention is to perform projection welding with high nut welding positioning accuracy and excellent welding quality, and to simultaneously perform drilling work corresponding to the threaded hole of the nut after welding. Our goal is to provide a projection welding machine that can.

[Summary of the invention]

In order to achieve the above object, the projection welding machine according to the present invention is provided with a guide pin that can enter and exit the screw hole of the nut to be welded, which is supplied to a predetermined position, on one of the welding electrodes. A control means is provided for causing the guide pin to both protrude and retract during welding and drilling work, and the other welding electrode is provided with a punching means for punching into the plate material (panel) to which the nut is welded, and this punching means A scrap discharge passage is formed, and the scrap can be pushed out into the discharge passage by the guide pin.

With the above configuration, even if a pilot hole for the nut is not formed in the panel, the positioning of the nut and the upper electrode is performed accurately by the guide pin, there is no current splitting during welding, and the screw of the nut can be adjusted after welding. Since the holes can be drilled at corresponding positions and the scrap can be discharged at the same time, accuracy and quality can be improved, as well as work efficiency.

[Embodiments of the invention]

Embodiments of the projection welding machine according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view of the main parts of a projection welding machine. As shown in this figure, this welding machine has an upper electrode 1 and a lower electrode 2, and by butting them together, a nut 3 and a panel 4 to be welded are welded.
I try to weld it. The upper electrode 1 is configured to be movable up and down relative to the lower electrode 2 which is in a fixed position, and for this purpose the upper electrode is attached to the lower end of a supply head rod 6 held in the welding machine body 5. The supply head rod 6 is a pressure cylinder 7 installed at the upper part of the welding machine main body 5 (see Fig. 5).
It is possible to push it out vertically downward. The upper electrode 1 is attached by inserting the lower end of the supply head rod 6, and welding current is supplied by a cable terminal 8 and a welding cable 9 connected thereto. The tip of the upper electrode 1 is a truncated cone, and the nut 3 to be welded is attracted to the tip surface and transferred to the lower electrode 2. The suction action of the nut 3 is based on the suction coil 3 attached to the supply head rod 6.
This is done by energizing (excitation) 8.

Further, the supply head rod 6 and the upper electrode 1 are integrated to constitute a supply head body, and a guide pin 10 that can be moved in and out from the tip end face of the upper electrode 1 is arranged in the head body. This guide pin 10 is composed of a piston part 11 and a pin rod part 12 having a smaller diameter cross section. It is made to penetrate through the section and protrude from the end surface thereof. For this purpose, the piston part 11 is reciprocated within the cylinder chamber 13, but this is configured as an air cylinder mechanism, and the cylinder chambers at both ends that sandwich the piston part 11 are pneumatic chambers, which communicate with the upper and lower pneumatic chambers. An air supply/discharge port 14A is connected to the supply head rod 6 and the upper electrode 1 as shown in FIG.
14B is formed. Here, the pin rod portion 12 of the guide pin 10 is fitted into the screw hole 3A of the nut 3 supplied during the protruding operation, and is positioned, and after welding, the portion of the panel 4 corresponding to the screw hole 3A is drilled. It also has the effect of discharging the scraps that result from this process.

Next, a nut 3 to be welded is continuously fed to the tip of the upper electrode 1 by a nut feeding device 15, as shown in FIG. Mechanism 1
6 is provided on the welding machine main body 5. This specific mechanism is shown in FIGS. 2 and 3. That is, the nut catcher mechanism 16 has a catch arm 18 attached to a support shaft 17 at both sides of the upper electrode 1, and a nut feeding guide 19 and a nut receiving part 20 are formed at the tip of the arm 18. I have to. Therefore, a guide 19 and a half-piece receiving part 20 are integrally provided at the tip of each arm 18, and when both arms 18 are closed by the action of a spring 21, the nut 3 is moved to the tip surface position of the upper electrode 1. The upper electrode 1 is guided so as not to become an obstacle to the downward movement of the upper electrode 1 due to the arm opening operation. In order to carry out the opening operation, a cam plate 22 is particularly attached to the supply rod head 6, and its downward movement rotates both arms 18 in the opening direction against the force of the spring 21. The nut feeding guide 19 is connected to the chute of the nut feeding device 15, forming a nut passage.

Next, the peripheral structure of the lower electrode 2 will be explained based on FIG. 1. The lower electrode 2 is attached to the top of an electrode support casing 23 erected on the welding machine main body 5, and is fixedly installed at a fixed position on the main body 5. A cylindrical space is formed inside the casing 23, into which a punch attachment rod 24 is inserted. A punch 2 is attached to the upper end of this rod 24 for punching holes in the panel 4.
5 is installed. The punch 25 is the lower electrode 2
It is attached so as to penetrate through the center of the lower electrode 2, and the perforated portion at the tip can protrude from the upper surface of the lower electrode 2. This punch 25 is normally retracted from the lower electrode 2, and for this purpose the punch attachment rod 24 is capable of vertical and reciprocating movement by a hydraulic cylinder 26 attached to the welding machine main body 5. Here, the punch 25 and the rod 24 to which it is attached are disposed on the same axis and connected, and a scrap passage 27 is formed inside so as to pass through them. This scrap passage 27 opens at the upper end surface of the punch 25, and
It opens into a scrap outlet pipe 28 formed at the proximal end of the cylinder 26. Also,
The scrap passage 27 has a cross section larger than the scrap size from the middle, and a small diameter passage 27A corresponding to the scrap size is formed only in a small range from the upper end of the punch 25. Therefore, after the punch 25 performs the drilling operation, the formed scrap passes through the small diameter passage 27A and can be easily discharged through the scrap passage 27. FIG. 4 shows how the scrap 25 is discharged. That is, after welding the nut 3 and the panel 4, the punch 25 is moved upward to perform a drilling operation on the panel 4, but since the scrap 29 formed by this is initially present in the small diameter passage 27A, this was not described above. By further moving the guide pin 10 downward, it is pushed out to the scrap passage 27 having a large cross section and is discharged.

Next, the drive mechanism of the above device is shown in FIG. The drive mechanism moves the guide pin 10 in and out, drives the air circuit 30 that pressurizes (advances) and releases (retreats) the upper electrode 1, and the hydraulic cylinder 26 that performs the drilling operation, and also drives the upper electrode 1 during drilling. It has a hydraulic circuit 32 for driving an electrode lock cylinder 31 that is held in a fixed state. The air circuit 30 can move the guide pin 10 in and out and move the upper electrode 1 up and down by switching the electromagnetic switching valves 33 and 34. Further, the hydraulic circuit 32 includes each hydraulic cylinder 26,
Electromagnetic switching valves 35 and 36 arranged in the hydraulic passage of 31
Drilling work can be performed by switching between the two. A time chart for operating each driving device is constructed as shown in FIG. 7, and a sequence control circuit for implementing this is constructed as shown in FIG. 8. In particular, in this control means, the operation of moving the guide pin 10 in and out of the upper electrode 1 is performed when the welding current is applied, and the guide pin 10 is controlled to be retracted during welding, and made to protrude after the welding current has ended. ing. After this welding, the panel 4 is punched by operating the electrode lock cylinder 31 and the punching cylinder 26, and the formed scrap 29 is pushed out into the scrap passage 27 using the protruding action of the guide pin 10. This is what we are trying to do to get rid of it. Specifically, the panel 4 detects that the nut has been carried into the lower electrode 2, issues a start command, feeds the nut, and activates the a contact CR5 of the adsorption coil energization circuit to place the nut in the upper electrode 1. Let it absorb. Since the guide pin 10 is in a protruding state when the nut is attracted, accurate positioning is achieved by fitting the two together. At the same time, the a contact CR5 of the drive circuit that lowers the upper electrode 1 is activated, so the electromagnetic switching valve 34 is switched to the pressurizing side, and the upper electrode 1 is directed toward the panel 4 set on the lower electrode 2 with the nut attracted. Then it is lowered. When the lowering end is reached, limit switch LS-2 set at that position is turned on.
This turns off the power to the attraction coil, activates the b contact of the circuit that operates the driving electromagnetic switching valve 33 of the guide pin 10, and causes the pin to retract. At the same time, the timer TR1 is activated, and the timer switch TR1 in the welding current energization circuit is activated to energize for a set time to perform welding. Then, at the same time as the application of the welding current is finished, the guide pin 10 is returned to its original state, that is, the electromagnetic switching valve 33 is returned to its original state, and the pin is placed in the protruding state to begin the next drilling operation. The drilling work begins with the electrode lock cylinder 3.
Give a start signal to the electromagnetic switching valve 36 corresponding to 1,
The cylinder 31 is lowered to fix and hold the upper electrode 1 at the welding position. When the completion of this operation is detected, a start signal is given to the electromagnetic switching valve 35 corresponding to the hydraulic cylinder 26 for punching, and the punch 25 is moved upward via the hydraulic cylinder 26 to punch the panel 4. Since the formed scrap 29 is pressed against the guide pin 10 in advance, the scrap 29 is pushed into the scrap passage 27 at the same time as punching, and the pushing operation continues until the small diameter passage 27A is removed. Then, the scrap 29 that has passed through the small diameter passage 27A is discharged to the outside through the scrap passage 27 by gravity, and the work is completed.

According to the projection welding machine having the above-described configuration, when the nut 3 to be welded is attracted to the upper electrode 1, the positioning of both can be performed reliably using the guide pin 10. 10 is drawn into the upper electrode 1 during welding work, so the positioning between the nut 3 and the panel 4 is performed with high precision, and no shunt flow occurs through the guide pin 10, so welding quality is significantly improved. Become. In addition, with this device, the punch 25 performs the drilling operation at precisely positioned locations after welding is completed, so even if the nut pilot hole is not formed in the panel 4 in advance, it can be performed with high precision. It becomes possible to drill a hole corresponding to the screw hole 3A.
In addition, scrap 2 generated during drilling work
Since the scrap 9 is discharged downward through the center of the lower electrode 2, there is no problem associated with the generation of the scrap 29.

In the above embodiment, the guide pin 10 is attached to the upper electrode 1, but this is formed on the lower electrode 2 on the fixed side, and a discharge passage for the scrap 29 is formed on the side where the upper electrode is located. Good too.
Furthermore, it is also possible to have the control circuit using the sequence circuit perform processing by a microcomputer.

〔Effect of the invention〕

As described above, according to the projection welding machine according to the present invention, it is possible to improve welding positioning accuracy and welding quality, and even when a nut pilot hole is not formed in advance in a panel, it is possible to improve welding positioning accuracy and welding quality. Accurate drilling work is possible, and the scrap formed can be easily discharged.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main parts of the projection welding machine according to the embodiment, Fig. 2 is a front view of the upper electrode section, Fig. 3 is a side view of Fig. 2, and Fig. 4 is the state during drilling work. 5 is a perspective view of a projection welding machine including a nut supply device, FIG. 6 is a configuration diagram of an air circuit and a hydraulic circuit, FIG. 7 is a time chart of welding work, and FIG. 8 is a sequence circuit diagram. 1... Upper electrode, 2... Lower electrode, 3... Nut, 4... Panel, 5... Welding machine main body, 10...
Guide pin, 15... Nut supply device, 16...
Nut catcher mechanism, 24... Punch attachment rod, 25... Punch, 27... Scrap passage, 29... Scrap, 30... Air circuit,
32...Hydraulic circuit, 38...Adsorption coil.

Claims (1)

[Claims] 1 One welding electrode is provided with a guide pin that can be moved in and out of the screw hole of the nut to be welded that is supplied to a predetermined position, and a control means is provided that retracts the guide pin during welding work, and the other welding electrode is The projector is characterized in that a punch means for punching a hole into a plate material to which a nut is welded is provided, and a scrap discharge passage is formed in the punch means, and the scrap can be pushed out into the discharge passage by the guide pin. Yon welding machine.