SU1748978A1 - Method of welding metals by friction - Google Patents

Abstract

Use: when welding by friction of various parts to reduce the initial moment of friction. SUMMARY OF THE INVENTION: At the end of one of the welded blanks, an annular groove is made with predetermined dimensions. When welding blanks of dissimilar metals, the bore is made at the end of the blank of a less ductile material. 1 hp f-ly, 3 silt, 1 tab. “

Description

The invention relates to friction welding and can be used in friction welding of combine parts.

During the friction welding process, the electric motor and the running gear of the machine are subjected to heavy loads due to a sharp increase in resistance to rotational forces in the initial welding period. Moreover, the closer the diameter of the workpieces to the maximum allowable diameter of the workpieces welded on this equipment, the greater the load. This leads to a sharp decrease in the rotation speed of the machine spindle and rapid equipment wear. To increase the reliability of the equipment, it is necessary to reduce the magnitude of the maximum torque at the beginning of the welding process at the stage of dry friction and active metal deformations. The reduction of the torque is carried out in several ways.

A known welding method, and which applies the imposition of ultrasonic vibrations, reducing the coefficient of friction and the yield strength of the metal, which in turn leads to a decrease in torque.

The disadvantage of this method is that it is difficult to impose ultrasonic vibrations on the contacting surfaces of the welded blanks, since it is necessary to use a high-power ultrasonic transducer.

A known method of friction welding, in which, as the torque increases, the pressure on the shaft of the machine spindle is automatically regulated by a special centrifugal regulator connected to the motor shaft.

 R --ChE

sj 00

The disadvantage of this method is the difficulty of modifying a conventional machine with such a regulator, as well as large peak loads on the undercarriage of the machine at the initial moment of welding.

The closest to the invention is a friction welding method in which the reduction of the initial friction moment is carried out by special preparation of the end surfaces of the welds being welded. This goal is achieved by reducing the initial contact surface of welded workpieces of the same diameter by performing metal samples on both workpieces. In this case, we consider welding workpieces of critical structural elements as well as elements operating under dynamic load conditions, which determines the uniformity of the geometric dimensions of the end surfaces of the workpieces.

In the known method, several options are proposed for reducing the contacting surfaces of the welded blanks. In the form of chamfering at an angle of 2-5 °, with a diameter of DI (0.5-0.8) 0, depth, 8, and in the form of drilling holes in the end surfaces of both blanks. depth bi, where D is the diameter of the workpieces, is the draft of one workpiece. It is known that the average over the cross section coefficient of friction changes as well as the moment of friction and is a function of many variables. It depends on the temperature on the friction surface, pressure, speed of relative motion at the point of this surface, and the farther from the center of rotation the point is separated, the smaller the coefficient of friction in this part of the workpiece. Therefore, the degree of reduction of the initial moment of friction proposed by the first option These chamfers on the outer diameter are ineffective. In the second variant, firstly, the diameters of the holes are not indicated, which is an essential parameter for the weld, and secondly, the indicated depth of the holes will weaken the bearing capacity of the welded joint, since its area will be determined by the size of the initially hit areas Croed billets, a common disadvantage of the proposed options is the need to prepare the end surfaces of both billets, and using at least two transitions (trimming - chamfering m 2-5 °, trimming - dent- ing - drilling), which increases the welding efficiency.

The aim of the invention is to increase the reliability of equipment operation.

The goal is achieved by the fact that the joined cylindrical billets with

the samples are brought into contact with the application of compression force while their relative movement, while the speed of the relative movement is constant, but the sample is

annular groove in one of the blanks with the ratio of the diameters Di2 2 (D22 - Oz2}, where Di is the diameter of the preform; D2 is the larger diameter of the groove made in the range 0, 85Di; Oz is the smaller diameter of the groove, and the depth of the groove is b 1/31 where I is the length of the deformable part of the workpiece. When welding workpieces from different steel compositions, the sample is made in a workpiece of a less ductile material.

In view of the fact that at the initial moment

The area of the contact surfaces is reduced by sampling, in one of the blanks the peak loads on the running gear of the machine are reduced. The welding process

passes without sharp drops in the spindle rotation speed of the machine, which increases the reliability of the equipment

Fig 1 shows the workpiece before welding 1 in Fig 2 - the same after welding on

FIG. 3 - the same, prepared for welding by the proposed method

The essence of the method lies in the fact that in one of the blanks on the end, an annular sample of metal is performed in the ratio of diameters Og 2 (0 a2 - Oz2), where Di is the diameter of the workpiece, 02 is a larger sample diameter, made within 0 75- 0.85 Di, Oz is the smaller sample diameter, determined from the above

formulas. The depth of sampling b for a quality compound, as shown by metallographic studies, is sufficient to choose equal to b 1/3, where is the length of the deformable part of the workpiece.

Since the initial moment

The welding area of the contact surfaces is reduced by sampling in one of the blanks, the peak loads on the undercarriage of the machine are reduced, and the machine's spindle rotates at a constant speed. The results of changing the ratio of the areas of the sample Si to the full surface of the end face of the workpiece S by the relative change in the speed of rotation of the spindle For%

with a depth of sample b 1/31 given in the table.

Laboratory studies and analysis of the data showed that the smallest change in speed, and therefore

The smallest initial torque on the spindle shaft occurs at Si 0.5S, which corresponds to the ratio of diameters Og - 2 (D2 - Oz). From the conditions for obtaining greater efficiency in reducing the moment of friction and better grazing conditions, it is more expedient to perform an annular groove in the region of the average circumference of the end surface of the workpiece, such parameters of the annular groove should be:

Da - the largest diameter of the groove, made in the range of 0.75-0.85Di;

Oz - the smallest diameter of the groove is determined from the above formula.

After preparation of the end of the part for welding, friction welding of two blanks is performed. For this, the workpiece with the groove 1 is rotated and pressed against the smooth end of the workpiece 2 fixedly mounted. The dry friction of the contact ends begins, and the torque and power of the heat release increase. Under the influence of temperature, the metal becomes more plastic, a thin layer of melt of a low-melting eutectic is formed between the rubbing ends. The rate of increase in resistance to rotational forces is significantly reduced. The heated metal is forced into a burr. Gradually, as shrinking, the remaining part of the end surfaces of the blanks comes into contact, preheated by the heat released at this stage.

At the same time, in contrast to the known method, two opposite factors simultaneously act on the welding process, the intensity of one of which decreases as it increases in the other. One factor is the aforementioned decrease in the rate of increase in resistance to rotation. The second factor relates to the phenomena associated with the gradual involvement of the relatively cold areas of the end surfaces of the workpieces in the welding process and, consequently, with an increase in the forces of resistance to rotation and heat generation,

Gradually, the heat generation process stabilizes at a steady state level. Due to these factors, the rotational speed of the spindle varies slightly, the running gear of the machine does not experience shock-growing loads, and when welding dissimilar metals characteristic of friction welding, relatively symmetrical plastic deformation of the workpieces takes place.

As macroscopic studies of the cross section of a sample of welding of opposite metals showed, more uniform plastic deformation is obtained by face sampling from a billet of a less ductile metal due to better heat removal conditions in

a more plastic workpiece in view of its larger section in the initial period of welding,

Experimental party was made on the software Taganrog combine plant by the proposed method of friction welding

gear shaft 54-60860, entering the axle drive wheels self-propelled combine harvester.

After manufacturing the parts according to the proposed method, comparative bench tests were carried out. The research results are positive. The welding of parts according to the proposed method saves 30 thousand rubles by reducing the consumption of the alloyed metal.

Claims (1)

Invention Formula 1 A method of welding metals by friction, in which the ends of the workpieces are preliminarily prepared, while reducing the areas of the contacting surfaces, by that. that, in order to increase the reliability of the equipment by reducing the initial friction torque, reduce the area of the contacting surfaces of the welded blanks, performed on the end of one of the blanks an annular groove, the dimensions of which are chosen from the ratios 40 Di 2 (D22 - Oz2): -2: B-1/31, where DI is the diameter of the workpiece; 02 is the larger diameter of the annular gap, Da (0.75–0.85) 01; 03 is the smaller diameter of the annular gap; b - the depth of the groove; 1 - the length of the deformable part of the workpiece, 2 Method of pop, 1, characterized in that, in the case of welding workpieces with different physicomechanical properties, an annular groove is made at the end behind cooking from less plastic material sh  I / l # L W