SU841859A1 - Method of contact spot welding - Google Patents

Description

(54) CONTACT METHOD OF SPOT WELDING

one

The invention relates to mechanical engineering and can be used to obtain permanent joints of metal parts.

Known methods of contact spot welding using a peripheral reduction of the welded point. These methods are widely used in welding of heat-resistant steels l.

The disadvantages of these methods are that the process of forming a compound with peripheral compression proceeds similarly to the process without peripheral compression, but using large-diameter electrodes, which leads to a significant increase in power consumption and reduction of the outburst suppression effect.

There is a known method of resistance spot welding, by which the welding of tt Ie parts is clamped between the electrodes, creating an additional peripheral force simultaneously with the electrode, and the welding current li is passed.

However, the use of this method in welding light alloys leads to an intense extrusion of metal from under the ferrule, and in welding of heat-resistant steels to

: burning of electrodes. In both cases, the efficiency of the heating process is reduced due to an increase in the area of the initial contact, the detail and a decrease in the current density, all of which lead to an increase in the spreading rate. the course of electricity, as well as the constant compression of the periphery reduces the effectiveness of the suppression of the final

0 splashes, especially when steel is welded by electrodes with a flat working surface due to an increase in the initial melting area of the metal.

The purpose of the invention is to increase the quality of welded joints.

The goal is achieved by the fact that the initial force on the electrodes is exceeded by the amount of force on the electrodes when welding parts without peripheral reduction, from the moment the welding current is switched on, the force on the electrodes is reduced, at the same time the peripheral force increases. switching off the welding current, the peripheral force is reduced, and the force on the electrodes is increased to the initial value. The initial peripheral force is taken equal to 5-10% of the force applied to

0

electrodes, and the force on the electrodes is 10% higher than the force on the electrodes when welding parts without peripheral reduction.

Peripheral force varies according to the following relationship:.

+ (pc - y).

mon

F,

the current value of perigde effort; initial and final

-PC

 values, peripheral force;

the time of passage of the swirl current; . current time coordinate;

n is an exponent. The drawing shows a sequence diagram of the welding process according to the proposed method.

Obtaining a dependency arises from the very essence of the invention, namely, to eliminate splashes and increase Thermal efficiency, in spot welding, compression of the peripheral zone of the weld point, changing during the welding process according to any law, is used. This may be a linear dependence, parabolic, logarithmic, etc. The choice of this law depends on the mechanical and physical properties of the metal being welded, taking into account that the resistance and strain rate change with the passage of welding time. Experimental studies have determined the index. Its values must satisfy the above criteria for process efficiency. All experimental values that satisfy the developed welding method are given in the implementation example of the proposed method.

Investigation of the process of contact spot welding is carried out on a contact machine of alternating current MTPU-300 with a flat surface of electrodes made of BrH-07 alloy, on samples of steel 12Х18Н9Т.

Samples of steel 12X18H9T with a thickness of 0.5 mm, type in a package of 1.0 layers. Welding is performed as follows.

A packaged bag is placed on the lower electrode, the upper electrode is lowered and a force of 720 kgf is created on the electrodes, the peripheral force is 5% of the force on the electrodes and is 36 kgf. Since the start of the welding current, the peripheral force changes according to

),

- F 1 L- + (F

mon

P.

PC

vi is the current value of peri-,

where is the filial effort; initial and final

Mon UK Peripheral Values | rb effort; I

t is the time of passage of the welding current; t - current coordinate

time;

. p, - exponent equal to 0.5-1 when welding heat-resistant steels. The main parameters of the mode:

force on the drive 750 kg;

force on the electrodes 720 kg;

initial peripheral amplifier 36 kgf

W

final peripheral - effort 500 kgf exponent 0.8;

n welding time 0,22 s

tee welding current 7 100 A.

se Using the proposed: contact spot welding method, the quality of welded joints is improved by reducing the force on the electrodes, which in turn leads to an increase in temperature in the area of contact of parts and the depth of their penetration, eliminating initial and final outbursts due to stabilization of contacts the gap (does not exceed 0.25-0.5 mm and the consumption of consumed electricity decreases.

Claims (3)

1. A resistance spot welding method in which the parts to be welded are clamped between the electrodes, creating an additional peripheral force at the same time as the electrode and passing the welding current due to the fact that, in order to improve the quality of the welded joint, the initial force of the electrodes is taken exceeding the magnitude of the force on the electrodes when welding parts without peripheral reduction, from the moment the welding current is switched on, the force on the electrodes is reduced, at the same time by however, the peripheral force is increased, after turning off the welding current, the peripheral force is reduced, and the force on the electrodes is increased to its original value. 2. The method according to Clause 1, about. And l and ay with the fact that the initial peripheral force is taken equal to 5-10% of the force on the electrodes, and the force on the electrodes is 5-10% higher than force on the electrodes when welding parts without peripheral reduction. . . 3. The method according to claim, 1, about tl and h and yu and the fact that the peripheral force varies according to the following relationship:,. . „ (Rpgs - F.v,) - ()  pctn P de the current value of the peripheral force effort;  initial and final mn the value of the peripheral force t is the time of passage of the welding current; t is the current time coordinate; n is an exponent. 418596 Sources of information taken into account in the examination i - -, 1.Orlov B, D. and others. Technologists and equipment for resistance welding. with M., Mechanical Engineering, 1975, p. 152153. 2. USSR author's certificate number 223959, cl. 23 K 11/10, 1966.