SU764896A1 - Resistance welding process control method - Google Patents

Description

(54) CONTACT PROCESS REGULATION METHOD The invention relates to contact welding of metals with alternating current and can be used in the manufacture of electronic products and instrument making in welding parts requiring a connection with a minimum heat affected zone, for example, in sealing integrated circuits with seam contact welding. There is a method of controlling the process of resistance welding, in which the regulation of the process is carried out according to the values of the contact resistances of the Cl. The known method has a low response rate in treating disturbances, which is its disadvantage. There is also known a method for adjusting the ININ process of contact welding, based on the use of an increased part, in which the energy control of welding pulses is controlled by changing the frequency of the welding pulse generator 2. However, when implementing this method, a special high-frequency welding pulse generator is required.

WELDING The closest to the proposed method of controlling the process of resistance welding with alternating current, in which the welding current is controlled by changing the switching and switching angles in each half-period 3. The disadvantage of the known control method is the low stability of the generated energy of the welding pulses, which reduces the quality of the welded joints. The purpose of the invention is to improve the quality of welding. This goal is achieved by the fact that the switching angle is adjusted in accordance with the mains voltage fluctuations, and the switching angle is adjusted depending on the rate of change of the welding current. The quality of welding is determined by the stability of the welding process, which is mainly determined by the stabilization of the energy supplied to the welding zone, and the deviations that occur during the welding cycle are compensated by correcting its duration in terms of the rate of change of the welding current.

Obtaining stable dimensions of the welded joint is caused not only by the stabilization of the energy released between the electrodes, but also by its adjustment depending on the state of the parts. This is achieved, for the first time, by adjusting the specified grid switching power, i.e., keeping the value constant at an unstable supply voltage. Secondly, the automatic adjustment of the pre-selected duration of the welding cycle is carried out depending on the rate of change of the welding current, which (When and const corresponds to the rate of change of the total resistance at the contact of the parts to be welded, which is mainly due to the increase in the specific resistance of the metals to be welded by the part and the fall of the transition resistance with increasing However, the stability of the change in the total contact resistance is mainly determined by the deviation The condition of the surface, chemical composition, heat treatment and dimensions of the parts to be welded. The instability of the compression force of the electrodes, etc. Therefore, to maintain a stable connection quality, it is not enough to separate equal portions of energy between the electrodes during each welding pulse. This condition corresponds to the correction of the duration of the welding pulse, which reduces it at a higher rate of change of the welding current and vice versa.

Correction of the switching angle by this value, and not by the absolute value of the welding current, ensures the control of the welding cycle, regardless of the initial voltage values on the electrodes and the contact resistance. Such an adjustment, in addition, provides automatic adjustment of the dynamic parameters of the contact resistance within one half-period, while the initial mode is pre-set by static parameters.

Thus, the method allows controlling the process of contact welding with a duration of less than one half of the supply voltage, which is typical of the welding mode with a minimum heat affected zone. The total duration of the welding pulse tci. equals

to + At

+ At

6CL.

on

where .to is the preselected welding time at the rated voltage of the grid and network rated. For a specific welding process, determined by the switching angles about (on and off of the welding current; correction of the turn on and off of the welding current;

At-- f / AUcern,,,

 incl .. 1

Uceru-HoMMH

 - OFF d G. 8 OFF

where dl / dt is the rate of change of the welding current.

To maintain a constant amount of energy, an automatic control system for thyristor pax with phase control can be used.

Example. The tacking of the bottom and the rim is carried out by spot contact welding when assembling a metal-glass body with a planar

 pin layout for microcircuits

 K401.14-5 (Scheme 74). Weld parts with a thickness of 0.1 mm + 1.5 mmiz alloy 29 NC (Kovar). Welding is carried out with a two-way current lead to electrodes with a diameter of 1 mm through the welded parts.

The reinforced point is formed by welding current pulses into positive and negative half-periods of the supply voltage with a frequency of 50 Hz. Angle

0 the switching on of the current is set to 70 °, and the switching off angle to 130 ° in each voltage half-cycle, with an amplitude value of 700 A,

The welding cycle is corrected in the i-5.5 ° range with no turning off angle. The diameter of the weld point is 0.6, with an average tensile strength of 4.5 kgf.

Regulation of the resistance welding process according to the proposed method increases the stability of the welded joint. Thus, when controlling the process, in the ten percent percentage range from the average force to the connection rupture includes 87% of the samples, while

5 as a matter of no control, only 64%.

PRI mme R 2. Carry out the enclosure sealing K401. 14-5 by seam contact welding. Weldable parts lid and base of alloy 29HK

0 with electroplated coatings of nickel (3 microns) and gold (1-2 microns). Cover thickness 0.1 mm. The welding is carried out according to the scheme with one-sided current lead through taper rollers 12 mm in diameter and the cover. The welding speed is 7.5 mm / s. Compression force 0.8 kgf.

The weld point is formed in the same way as spot welding (example 1). The angle of the current is set to 80, and the angle off - 130 ° at

0 amplitude value of current 1100 A.

A sturdy seal is formed by the SUNNED overlapping points of the ellipse type with a larger side equal to 0.6 mm, alternating with

Claims (3)

5 pause duration of two periods of the supply voltage. In this case, the overlap point ratio was selected at about 40%. Correction of the duration: the welding cycle during weld formation is + 1 ° through the off angle. Determination of the effectiveness of the adjustment is carried out in the process of sealing based on the temperature of the heating of the body rim in the stealth zone between the last but one and the last pin of the microcircuit during welding. When controlling the welding process according to the proposed method, the maximum heating temperature is, while in welding without control, with the same tear strength, the heating temperature is. The temperature is measured with a copper-constantan thermocouple with a diameter of 0.1 mm + S, 1 mm. To obtain a durable weld during welding without controlling the process, the energy input to each weld point in the workshop conditions should be somewhat overestimated to compensate for the instability of factors affecting the quality of welding (supply voltage, surface state of the parts to be welded and working parts of electrodes, and so on d.) In the same mode with the control of the welding process, the angle of corrections takes on negative values of about 90% when forming weld points of the weld under test, which ensures a decrease in heat input with equal strength of the welded joint. The method is applicable to both single-period period and multi-period welding, and is especially effective when creating seams near heat-sensitive elements, as it allows reducing the heat-affected zone. For example, when sealing semiconductor and hybrid microcircuits, piezotechnics products, etc. the percent of an exit of annual products increases. In comparison with the known, the proposed method of controlling seam resistance welding has great speed and due to the automatic correction of the amount of energy deposited in the welded point, it is possible to qualitatively connect parts that have a significant deviation in size, surface condition, composition, etc. controls the welding cycle regardless of the initial values of the voltage on the electrodes and the contact resistance of the parts, adjusting the dynamic parameters, and at the same time more growth cBoeriy technical implementation because it requires only control of the welding current and calculating its variation in time. Claims The method of regulating the process of contact welding on alternating current, in which the welding current is controlled by changing the switching angle and turning off current in each half period, characterized in that, to improve the quality of welding, the switch angle is adjusted in accordance with the fluctuations supply line, and the shutdown angle, depending on the rate of change of the welding current. Sources of information taken into account in the examination 1. USSR author's certificate number 461816, cl. In 23 K 11/24, 1973. 2. USSR author's certificate according to the application 2312893 / 25-27, cl. In 23 K 11/24, 1975. 3.Paton B.Ye., Lebedev V.K. Electrical equipment for resistance welding. M., Mechanical Engineering 1969, p. 81, 85.