JP2509613B2 - Method for welding metal plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a projection welding method for a metal plate used for manufacturing an explosion-proof structure of a cathode ray tube, for example.

(Prior Art) Generally, a cathode ray tube is easily implosed by an impact from the outside, and various measures have been conventionally taken to prevent this. Among them, a method of firmly tightening the metal band by shrink fitting on the outer periphery of the side wall of the face plate of the cathode ray tube is widely adopted.

In this method, as shown in FIG. 4, first, an explosion-proof tape 3 is formed on the outer circumference of the side wall of the face plate 2 of the cathode ray tube 1.
Wrap around. Next, the metal ring belts 5 to which the supporting metal fittings (lugs) 4 are fixed at the positions corresponding to the four corners of the panel are heated and expanded, and the face plate 2 is attached to the explosion-proof tape 3
Is inserted so as to come to the position of the metal ring band 5. And the fifth
As shown in the figure, the side wall of the cathode ray tube 1 is clamped by the force of cooling and shrinking of the metal annular zone 5 to manufacture an explosion-proof cathode ray tube. As shown in FIGS. 6 and 7, there is also known a method of winding a metal band 6 around the outer periphery of the side wall of the face plate 2 of the cathode ray tube 1 while sandwiching the lower portion of the lug 4 at the positions corresponding to the four corners of the panel. However, in the shrink fitting method, the tightening force at the four corners of the face plate 2 is more uniform than in the winding method, and the metal ring band 5 to which the lug 4 is fixed in advance is used. It has the advantage of being easy to hold.

And conventionally, as a method for fixing the lug 4 to the metal ring band 5 used in such a shrink fitting method,
The projection welding method is used from the viewpoint of reducing the number of weldings, improving the mounting accuracy, and facilitating automation. In this method, as shown in FIG. 8, a plurality of small projections 7 are formed on the lug 4 side having a large thickness and a large heat generation amount,
As shown in FIG. 9, the small projections 7 are opposed to the metal ring band 5, and the outer welding electrode 8 and the inner welding electrode 9 arranged on the outer side of the small projections 7 are pressed to energize the both electrodes to perform spot welding. Be seen. The outer welding electrode 8 and the inner welding electrode 9
As shown in FIG. 10, each has a gutter-shaped surface that matches the curved surface of the lug 4 and a cylindrical surface that fits into this.

(Problems to be Solved by the Invention) However, in such a conventional method, the lug 4 and the metal annular zone 5 have different thicknesses, and the outer electrode and the inner electrode in contact with these are made of the same metal material. However, since the heat generation amount of the lug 4 is different from that of the metal ring zone 5, there is a problem that good fusion bonding cannot be obtained.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a projection welding method for a metal plate, which has high welding strength and can significantly improve the life of the welding electrode.

[Structure of the Invention] (Means for Solving the Problems) The projection welding method for a metal plate of the present invention comprises a plurality of small projections on a thick metal plate of two metal plates to be welded having different thicknesses. Are provided, the small projections are made to face a thin metal plate and these metal plates are overlapped, and a pair of welding electrodes are arranged with the metal plate to be welded in between, and both metal plates are provided by these welding electrodes. In the method of projection welding while applying pressure, a high resistance refractory metal is arranged on the contact surface of the welding electrode in contact with the thin metal plate in correspondence with the position of the small protrusions of the thick metal plate. Is characterized by.

As the high resistance refractory metal used for the welding electrode in contact with the thin metal plate in the present invention, when the base material forming this electrode and the other electrode is a normal copper alloy, tungsten, molybdenum, or an alloy thereof is used. Can be used.

(Operation) In the present invention, since the metal having a high resistance and a high melting point is arranged in correspondence with the position of the small protrusion of the thick metal plate on the contact surface of the welding electrode in contact with the thin metal plate, This electrode has a higher resistance value than the other welding electrode, and the influence of the plate thickness is offset, and the calorific values of the thick metal plate and the thin metal plate become substantially equal. Therefore, good fusion bonding is performed between them, and a bonded body having high welding strength is obtained.

Further, since the refractory metal is arranged on the electrode on the side of the thin metal plate so as to correspond to the position of the small protrusion where the stress due to the thick metal plate is concentrated, the life of the electrode is significantly improved.

(Example) Hereinafter, the Example of this invention is described based on drawing.

In this example, an explosion-proof structure in which a 2.0 mm-thick lug was projection-welded to a 0.8 mm-thick iron metal ring band by shrink-fitting to a cathode ray tube by the following method was manufactured.

First, as shown in FIG. 1, at the position where the base of the curved inner joint surface of the lug 10 forms each apex of an isosceles triangle that is twice the hypotenuse, three bases with a diameter of 3 mm are arranged so that the base is horizontal. The small protrusions 11 were formed respectively.

Next, with these small protrusions 11 inside, the lug 10 is attached to the metal loop.
The outer peripheral surface of 12 is contacted with, and the outer surface of the lug 10 is contacted with an outer welding electrode 13 made of a copper alloy having a contact surface curved inward with a radius of curvature (26 mm) substantially equal to the radius of curvature, and at the same time, a metal ring band. The outer peripheral surface of the cylindrical inner welding electrode 14 was brought into contact with the inner peripheral surface of 12 to hold the lug 10 and the metal ring band 12.

The inner welding electrode 14, as shown in FIGS. 2 and 3, has a radius (24 mm) approximately equal to the radius of curvature inside the lug 10.
On the surface of the electrode base 15 made of a copper alloy having a diameter of 6 mm,
It is configured by embedding a plurality of tungsten chips 16 having a depth of about 5 mm. Even if the inner electrode 14 as a whole rotates or moves up and down, the tungsten tip 16 is provided on the outer peripheral surface of the electrode so that the small projection 11 of the lug 10 can be easily pressed to the metal ring band 12 at any position. Of isosceles triangles are arranged with a certain order so that they are continuously formed at a pitch of 1/2 of the base.

Then, with the inner welding electrode 14 and the outer welding electrode 13 having such a structure, the tungsten tip 16 is attached to the small protrusion 11 of the lug 10.
So that it abuts the metal ring band 12 at a position corresponding to, sandwiching the metal ring band 12 and the lug 10, energizing between these electrodes while pressing, the lug 10 on the outer peripheral surface of the metal ring band 12. Weld.

In this embodiment, the inner welding electrode 14 in contact with the thinner metal annulus 12 has an electrode base 15 made of a copper alloy.
Since the surface has a structure in which a plurality of tungsten chips 16 having a high electric resistance are embedded, the calorific value of the metal ring zone 12 becomes high, and good fusion bonding is performed.

Also, the stress concentration inside the electrode (inner welding electrode
Since the high melting point tungsten is embedded at the position (14) where the small projection 11 of the lug 10 is pressed against the metal ring 12 via the metal ring band 12, wear of this part is unlikely to occur and it can withstand long-term use. You can

Furthermore, since tungsten, which is expensive, is used only in a small amount, the overall manufacturing cost will not be much higher than in the past.

[Effects of the Invention] As is clear from the above description, according to the method of the present invention, two metal plates to be welded having different thicknesses are firmly projection-welded to have stable characteristics and high reliability. You can get the product. In addition, the life of the welding electrode is greatly improved, and the cost increase is smaller than in the conventional case.

[Brief description of drawings]

FIG. 1 is a partial sectional view for explaining an embodiment of the projection welding method for a metal plate of the present invention, FIG. 2 is a perspective view of an inner welding electrode used in the embodiment, and FIG. 3 is in FIG.
II-II 'cutaway view, FIG. 4 is a perspective view showing a method for shrink-fitting the explosion-proof structure to the cathode ray tube, FIG. 5 is a perspective view of the obtained explosion-proof cathode ray tube, and FIGS. 6 and 7 are Fig. 8 is a front view and a side view, respectively, showing a fastening method of a metal band, Fig. 8 is a perspective view of a lug used in an explosion-proof structure, and Fig. 9 is a front view showing a conventional projection welding method of a metal ring band and a lug. FIG. 10 is a perspective view of an electrode used in the conventional method. 1 …… Cathode ray tube 2 …… Face plate 4,10 …… Lug 5,12 …… Metal ring band 7,11 …… Small protrusion 8,13 …… Outside welding electrode 9,14 …… Inside welding electrode 15 …… Electrode base 16 …… Tungsten tip

Claims (2)

(57) [Claims] 1. A metal plate having a large thickness of two metal plates to be welded having different thicknesses is provided with a plurality of small projections, and these small projections are made to face a thin metal plate and these metal plates are provided. And a pair of welding electrodes are arranged with the metal plates to be welded in between, and in the method of projection welding while pressing both metal plates with these welding electrodes, the welding electrodes contacting the thin metal plate. A projection welding method for a metal plate, wherein a high resistance refractory metal is arranged on the contact surface of the metal plate in correspondence with the position of the small protrusion of the thick metal plate. 2. The metal plate according to claim 1, wherein the welding electrode is a copper alloy, and the high resistance refractory metal is at least one of tungsten, molybdenum and alloys thereof. Projection welding method.