JPS5819030Y2 - Lower electrode for projection welding - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a lower electrode for projection welding, which is used when welding a nut to a steel plate with a hole, aligning the center with the hole.

A conventional example of this type of lower electrode is shown in FIG.

In FIG. 1, an electrode cover 3 is screwed and fixed to a screw 2 provided on the upper outer peripheral surface of an electrode container 1, and a large diameter hole 5 opening at the top of the container 1 and a small diameter hole 6 of the cover 3 communicating therewith are connected to each other.
A guide pin 8 having an outward flange 7 at its lower end is fitted into the guide pin 8 so as to be movable up and down, and the pin 8 is urged upward by a compression coil spring 10 in the large diameter hole 5.

Reference numeral 11 indicates a downwardly opening hole through which cooling water is introduced from below, 12 indicates an upper and lower hole, a partition wall between 5 and 11, and 13 indicates an insulator.

However, in this structure, the flange 7 abuts the inner step of the cover 3, and the amount of upward protrusion of the pin 8 is restricted by the abutting portion.
If the cover 3 is burnt out or worn out and the cover 3 is removed from the body 1 when polishing the electrode surface 14 of the cover 3 or replacing it with a new one,
The guide pin 8 is also pushed by the spring 10 and comes off from the body 1, and when installing a new cover 3, the guide pin 8 has to be refitted. Therefore, replacing the cover 3 is time-consuming, and when replacing it, There was a risk of losing the guide pin 8 and spring 10.

Furthermore, in order to improve the cooling effect of the guide pin 8, it has already been proposed to eliminate the partition wall 12 and introduce cooling water into the large diameter hole 5 at the top, but in that case, when replacing the cover 3, etc. If the guide pin 8 comes off, there is a problem in that cooling water will spout outward from the large diameter hole 5.

The present invention is a lower electrode of the type in which cooling water is introduced into the large diameter hole at the top of the electrode body, and an annular sealing member is fixed to the inner circumferential surface of the large diameter hole, and the sealing member is used to connect the inner circumferential surface of the large diameter hole with the lower electrode. This seal member seals the gap between the guide pin and the guide pin, and the seal member acts as a retainer for the guide pin.

In FIG. 2, the electrode body 20 has a large diameter hole 21 that opens upward.
A threaded portion 22 is formed on the inner peripheral surface of the large diameter hole 21 from the upper end to the middle portion.

A small-diameter screw portion 25 at the bottom of the electrode head 23 is screwed into the upper half of the screw portion 22 .
is detachably fixed to the body 20.

An annular sealing member 26 having a thread on its outer peripheral surface is screwed into the lower half of the threaded portion 22 .

The seal member 26 is made of metal such as brass.

The electrode head 23 has a guide hole 28 on the same layer and with the same diameter as the hole 27 of the sealing member 26, and a series of holes 27 and 28 are provided with stainless steel through O-lungs 30 and 31 (urethane rings) and an insulator 32, respectively. A guide pin 33 is fitted therein so as to be able to move up and down.

A hemispherical tip 34 is integrally provided at the upper end of the guide pin 33, and an outward flange 35 is integrally provided at the end.

A compression coil spring 37 is installed between the lower surface of the flange 35 and the annular bottom surface 36 of the large diameter hole 21.

38 and 39 are insulating plates. A cooling water nozzle 42 opens upward at the bottom of the hole 21, and is connected to a cooling water pump or a water faucet via a hose (not shown) or the like.

40 is a cooling water discharge passage.

When performing welding work, first hold the upper electrode 45 upward as shown in FIG. 2, and insert the guide pin 3 into the hole 47 of the steel plate 46.
Place the steel plate 46 on the head 23 with the upper end of the nut 48 fitted, and fit the hole 49 of the nut 48 into the tip 34 of the guide pin 33 protruding from the hole 47, and tighten both holes 4 as shown in FIG.
7. After aligning the centers of 49, lower the upper electrode 45,
While the steel plate 46 and nut 48 are in the state shown in FIG. 2, pressure is applied by upper and lower electrodes 45, 23 (heads), and a predetermined current is applied in a predetermined cycle to weld the nut 48 and the steel plate 46.

When the electrode surface 24 of the electrode head 23 burns out or wears out by more than a predetermined amount due to repeated welding, the head 23 is turned and removed from the threaded part 22, and a new head 23 is screwed into the threaded part 22.

During the replacement work, the seal member 26 remains fixed to the body 20, so the guide pin 33
It will not deviate from 0 or the cooling water will not spout upwards.

As explained above, according to the present invention, the electrode body 20
The sealing member 26 fixed to the guide pin 33 prevents the guide pin 33 from falling off and cooling water from leaking.
The electrode head 23 can be replaced extremely easily and reliably without paying any attention to water, cooling, or water.

It is also possible to integrate the seal member 26 with the electrode body 20, but in that case, it would be difficult to process the body 20 and attach the guide pin 33. It is better to have it as a separate body.
20 processing etc. become easier.

Although it is conceivable to provide a threaded portion on the outer peripheral surface of the body 20 and fix the electrode head (cover) to the threaded portion as in the structure shown in FIG.
In order to fix the sealing member 26 with screws, it is necessary to provide a threaded portion 22 for attaching the sealing member 26 in the large diameter hole 21, which complicates the structure.

Therefore, as in the present invention, the head 2 is
If you install 3, the threading process for the body 20 will be 1.
This reduces processing costs.

The sealing member 26 can also be fixed with a set screw 51 screwed into a threaded hole in the body 20, as shown by the two-dot chain line in FIG.

The upper O-ring 31 can also be eliminated (Figure 3)
.

The guide pin 33 can also be provided with a groove for fitting the O-ring 30.31.

However, as in the illustrated embodiment, the seal member 26 and head 23
The processing cost is lower if grooves for O-rings 30 and 31 are provided.

Insulator 32 and O'J ring 3 on the inner peripheral surface of seal member 26
0 may be eliminated, and instead of the metal seal member 26, a seal member made of plastic (for example, urethane), which has its own insulation and sealing properties, may be used.

When the nut 48 is held by the upper electrode 45 and descends, the tip 34 is eliminated.

A modification of the present invention will be explained with reference to FIG.

The guide pin 33a in FIG. 3 is made of an insulating material such as ceramic, and therefore no insulating material is interposed between the guide pin 33a and each part (head 23, spring 37, etc.). As a result, the number of parts is reduced and the structure is simplified.

The upper end of the pin 33a has a tapered diameter, which is used to securely hold the nuts 48 when welding various nuts 48 with different inner diameters, and to ensure that the holes 49 of the nuts 48 and the steel plate 46 This is to ensure accurate center alignment with the hole 47.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing a conventional example, and FIGS. 2 and 3 are longitudinal sectional views showing an embodiment and a modified example of the present invention. 20...Lower electrode box-121...
Large diameter hole, 22... Threaded part, 23... Electrode head, 25... Threaded part, 26...
Seal member, 28... Guide hole, 33, 33 a
...Guide pin, 35...Flange, 37, 52...Spring and nozzle (push-up mechanism).

Claims (1)

[Scope of utility model registration request] A large diameter hole that opens upward is provided in the lower electrode body, and the threaded part at the bottom of the electrode tip having a small diameter guide hole is screwed into the threaded part on the upper inner circumferential surface of the large diameter hole, and the threaded part at the bottom of the electrode tip having a small diameter guide hole is screwed and fixed. A guide pin having a flange is fitted into the guide hole so as to be movable up and down, and the upper surface of the outward flange abuts against the inner circumferential surface of the intermediate portion of the large diameter hole to limit the amount of upward protrusion of the guide pin. A lower electrode for projection welding, characterized in that a member is fixed, a push-up mechanism is provided in the lower part of the large diameter hole to push the outward flange upward, and cooling water is introduced into the lower part of the large diameter hole.