JPS63242473A - Projection welding method for metal plate - Google Patents

Abstract

PURPOSE:To increase the weld strength and moreover, to remarkably improve the service life of welding electrodes by arranging high-resistance and high-melting point metal on the contact surfaces of welding electrodes in contact with a this metal plate corresponding to the positions of small projections of a thick metal plate. CONSTITUTION:Small projections 11 are formed respectively at the positions forming respective vortexes of an isosceles triangle where the corresponding side of the bent inside joining surface of a lug 10 doubles an oblique line so that the base becomes horizontal. The lug 10 is pressed against the outside peripheral surface of a metallic annulus 12 with the small projections 11 placed at the inside and the outside welding electrode 13 having the bent contact surface at the inside is pressed against the back surface of the lug 10 and at the same time, the outside peripheral surface of the cylindrical inside welding electrode 14 is abutted on the inside peripheral surface of the metallic annulus 12 to hold the lug 10 and the metallic annulus 12. As to the electrode 14, plural tungsten chips 16 are buried in the surface of an electrode base 15 having a radius equal to a radius of curvature of the inside of the lug 10. The annulus 12 and the lug 10 are held between the electrode 14 and the electrode 13 so that the chips 16 abut on the metallic annulus 12 at the positions corresponding to the small projections 11 of the lug 10 and electrified while being pressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method of projection welding of metal plates used, for example, in manufacturing an explosion-proof structure of a cathode ray tube.

(Prior Art) Cathode ray tubes are generally susceptible to melting and shrinking due to external shock, and various measures have been taken to prevent this from occurring. Among these methods, a method in which a metal band is firmly tightened by shrink fitting to the outer periphery of the side wall of the face plate of a cathode ray tube is widely adopted.

In this method, as shown in FIG.
Wrap around. Next, the metal ring bands 5 to which supporting metal fittings (lugs) 4 are fixed to the four corners of the panel are heated and expanded, and the above-mentioned face plate 2 is attached to the explosion-proof Dave 3.
Insert it so that it is aligned with the metal ring band 5. and the fifth
As shown in the figure, the explosion-proof cathode ray tube is manufactured by tightening the side wall of the cathode ray tube 1 by the force of the metal ring 5 cooling and contracting. In addition, as shown in FIGS. 6 and 7, while sandwiching the lower part of the lug 4 at the four corners of the panel,
A metal band 6 is attached to the outer circumference of the side wall of the face plate 2 of the cathode ray tube 1.
However, compared to this wrapping method, the shrink-fitting method applies equal tightening force at the four corners of the face plate 2, and moreover, it uses the metal ring 5 to which the lugs 4 are fixed in advance. Since it is used, it has the advantage that it is easy to hold the position where the metal ring band 5 is fitted.

Conventionally, projection welding has been used as a method of fixing the lug 4 to the metal ring band 5 used in such a shrink-fitting method, from the viewpoint of reducing the number of welds, improving installation accuracy, and facilitating automation. ing. In this method, as shown in FIG. 8, a plurality of small projections 7 are formed on the side of the lug 4, which is thick and generates a large amount of heat, and as shown in FIG. Spot welding is performed by applying current between the outer welding electrode 8 and the inner welding electrode 9 placed on the outside of the band 5 while applying pressure. Note that outer welding electrode 8 J and inner welding electrode 9
As shown in FIG. 10, each of the lugs 4 has a trough-like front that coincides with the curved surface of the lug 4 and a cylindrical surface that fits thereon.

(Problems to be Solved by the Invention) However, in the conventional method J3, the thickness of the lug 4 and the metal ring 5 is small, and the outer electrode and inner electrode that are in contact with them are Since the lug 4 and the metal ring band 5 are made of the same metal material, the calorific value of the lug 4 and the metal ring band 5 are different, and there is a problem that a good fusion bond cannot be obtained.

The present invention was developed in order to solve these problems, and provides a method for projection welding metal plates that has high welding strength and can greatly improve the life of -tJ welding electrodes. The purpose is to provide.

[Structure of the Invention] (Means for Solving the Problems) The projection welding method for metal plates of the present invention provides a method for welding metal plates, in which a plurality of small protrusions are formed on a thicker metal plate of two metal plates having different thicknesses. 6, a pair of welding electrodes are arranged with these metal plates to be welded in between, and these welding electrodes In a method of projection welding while pressurizing both metal plates, the contact surface of the welding electrode in contact with the thin metal plate has a high resistance and high melting point with δ corresponding to the position of the small protrusion of the thick metal plate. It is characterized by the placement of metal.

In the present invention, the high melting point metal used for the welding electrode in contact with the thin metal plate may be tungsten, molybdenum, or At least one of these alloys can be used.

(Function) In the present invention, a high-resistance, high-melting-point metal is placed on the contact surface of the welding electrode that contacts the thin metal plate in correspondence with the position of the small protrusion of the thick metal plate of J7 size. This electrode exhibits a higher resistance value than the other welding electrode, and the influence of the plate thickness is canceled out, so that the calorific value of the thick metal plate and the thin metal plate are approximately equal. Therefore, good fusion bonding is performed between these, and a bonded body with high welding strength is obtained.

Furthermore, since the high melting point metal is placed on the electrode on the side of the thin metal plate in correspondence with the position of the small protrusion where stress is concentrated due to the thick metal plate, the life of the electrode is greatly improved.

(Example) Embodiments of the present invention will be described below based on the drawings.

In this example, 2. An explosion-proof structure was constructed by shrink-fitting a cathode ray tube by welding a thick lug to the cathode ray tube.

First, as shown in FIG. 1, three pieces of diameter 31 are placed at each vertex of a 23-sided triangle in which the base of the curved inner joint surface of the lug 10 is twice the hypotenuse, so that the base is horizontal. Small protrusions 11 were formed respectively.

Next, the lug 1o is placed on the outer peripheral surface of the metal ring band 12 with these small protrusions 11 inside, and a contact surface curved inward with a radius of curvature (26 mm) approximately equal to the radius of curvature of the lug 10 is formed on the back surface of the lug 10. Apply the outer welding electrode 13 made of prepared alloy,
At the same time, the outer peripheral surface of the cylindrical inner welding electrode 14 was brought into contact with the inner peripheral surface of the metal ring 12 to hold the lug 10 and the metal ring 12 together.

The inner welding electrode 14 has a diameter of 6 mm on the surface of an electrode base 15 made of prepared alloy and having a radius (24 mm) approximately equal to the radius of curvature of the inner side of the lug 10, as shown in FIGS. 2 and 3.
It is constructed by embedding a plurality of tungsten chips 16 with a depth of about 5 mm.

Even if the entire inner electrode 14 rotates or moves up and down, the small protrusion 11 of the lug 10 always passes through the metal ring 12.
The isosceles triangle of the lug is placed on the outer peripheral surface of the electrode so that the tungsten tip 16 is easily placed in the position where it is pressed.
They are arranged in a certain order so that they are continuously formed at a pitch of 72.

Next, using the inner welding electrode +4i14 and the outer welding electrode 13 having this similar structure, the tongue temperature knob 16 is attached to the lug 10.
The metal ring 12 and the lug 10 are sandwiched so that they come into contact with the metal ring 12 at the position corresponding to the small protrusion 11 of the metal ring 12, and the metal ring 12 is turned on by applying current between the two electrodes while pressing. A lug 10 is welded to the outer peripheral surface.

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

In addition, the inner welding electrode 1
Since tungsten with a high melting point is embedded in the position where the small protrusion 11 of the lug 10 is pressed against the metal ring 12 on the metal ring 12, this part is unlikely to wear out and can withstand long-term use. be able to.

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

[Effects of the Invention] As is clear from the above explanation, according to the method of the present invention, two metal plates to be welded having different thicknesses can be firmly projection welded, and stable characteristics and high reliability can be achieved. You can get the product. In addition, the life of the welding electrode has been significantly improved, and the cost increase is small compared to conventional methods.

[Brief explanation of drawings]

Fig. 1 is a partial cross-sectional view for explaining an embodiment of the projection welding method for metal plates of the present invention, Fig. 2 is a perspective view of an inner welding electrode used in the embodiment, and Fig. 3 is the same as Fig. 2. [Pull nm' cross-sectional view, Figure 4 is a perspective view showing the method of shrink-fitting the explosion-proof structure to the cathode ray tube, Figure 5 is a perspective view of the resulting anti-nuisance type cathode 14Fll tube, Figure 6 Figure 7 is a front view and side view showing the method of tightening the metal band, respectively.
Figure 9 is a perspective view of a lug used in an explosion-proof structure, Figure 9 is a front view showing a conventional projection welding method for welding a metal ring and a lug, and Figure 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 ... Outer welding electrode 9.14 ... Inner welding electrode 15 ...... Electrode Base 16...Tungsten tip applicant
Toshiba Corporation Representative Patent Attorney Sasa Suyama - Figure 32, :4S3 Figure 4 Figure 5. Figure 7 tll, Figure 8 Figure 9 Figure 10

Claims (2)

[Claims] (1) A plurality of small protrusions are provided on the thicker metal plate of two metal plates to be welded with different thicknesses, and these metal plates are stacked with the small protrusions facing the thinner metal plate. At the same time, a pair of welding electrodes are arranged to sandwich the metal plates to be welded, and in a method of projection welding while pressurizing both metal plates with these welding electrodes, the welding electrode in contact with the thin metal plate is A method for projection welding a metal plate, characterized in that a high-resistance, high-melting-point metal is placed on the contact surface of the metal plate in correspondence with the position of the small protrusion of the thick metal plate. (2) Claim 1, characterized in that the welding electrode is a copper alloy, and the high-resistance, high-melting-point metal is tungsten, molybdenum, or at least one of these alloys.
Projection welding method for metal plates as described in .