SU1505713A1 - Method of seam resistance welding - Google Patents

Abstract

The invention relates to welding, in particular, to resistance spot welding, and can be used mainly in welding with hermetic seam of thin-sheet structures. The purpose of the invention is to improve the quality of stability and to provide the possibility of obtaining hermetic welding of metal sheets with a thickness of up to 1.2 mm and making seams of unlimited length. The welding is carried out with an electrode with a wavy profile of the contact surface. The step of the profile of the electrodes is in the range 1.2 ... 4.2, and the depth of the waviness is 0.5 ... 1.7 of the thickness of the metal. Additional shear deformation appears in the direction perpendicular to the compressive force of the electrodes. This creates favorable conditions for the setting of metal surfaces without their mutual melting. 1 il.

Description

The invention relates to welding, in particular to resistance seam welding, and can be used mainly in svdrka hermetic seam of thin-sheet structures.

The purpose of the invention is to improve the stability of the quality of welding of thin-sheet structures by hermetic seam and ensuring the possibility of obtaining hermetic seams formed in the solid phase.

The drawing shows a diagram of the welding process according to the proposed method.

Before performing welding on the roller, wave-like reliefs are performed with a step ratio (A) and relief wave depth (B) to the thickness of the thinner welded part 1.2–4.2 and 0.5–1.7, respectively,

the step of 0.6-5.0 mm, suitable for welding of the specified thicknesses, is determined from the conditions of sufficiency of shear deformations to form a joint and stability of the seam (no periodicity of the macrostructure) along its axis; greater than an integer number of times the duration of the welding current cycle, consisting of the time of switching on the current in the pauses, +1. In addition, according to the proposed welding method, an increased ratio of t to t is required to form a monotonous joint along the axis of the seam. For sheets with a thickness of 1.2 mm and a welding speed of 4 m / min, a 5.0 mm profile profile is the limit. With a decrease in thickness

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iMoro metal is necessary in order to avoid periodic interruptions of seam continuity to drop and profile pitch. For a sheet tarpaulin 0.5 mm (and possibly 0.3 mm satisfactorily unsealed by a hermetic seam: the profile pitch should be somewhat larger than 0.6 mm. When reducing the pitch (O, 6 mm), even for this metal band, shear deformations at a depth of ca. 0.6 mm are insufficient for the formation of a solid-phase compound. If the depth of the cavities is increased to -55 2.0 mm, then this profile is not functional due to its low mechanical stability.

The shear strain during welding increases with increasing depth of the valleys. However, the depth of the pits with decreasing pitch must also be reduced to maintain an acceptable profile durability during operation. Therefore, with a reduction in the thickness of the sheets being welded from 1.2 to 0.5-0.3 mm and a corresponding reduction in the profile pitch from 5.0 to 0.6 mm, it is necessary to reduce the depth of the profile hollows from 2.0 to 0.6 mm

During the welding process, the deformation of the heated metal blanks under the electrodes becomes much more intense. In addition to limited deformation in the direction of the compression force of the electrodes, more significant shear deformation appears in the direction of movement of the welded blanks (in the perpendicular direction). This biaxial character of the deformation of the billets heated to a ductile metal state creates favorable conditions for their joining even without forming a zone of mutual melting, i.e. in the solid phase. In addition, the current density in the electrode-part contact decreases, while its density in the welding contact between the parts remains unchanged. The specified features of welding with such an electrode make it possible to obtain hermetic seams of a much wider width than that usually adopted for thin sheets, which increases their stability under the conditions of influence of various types of production disturbances. The mass rejection rate of the tightness of thin-sheet containers during their mass production is significantly reduced.

For the implementation of the method, for example, a welding machine is used, which contains in its design cones and presses its working surface against the contact surface of the roller electrodes. The working surface of the gear teeth with the parameters ensuring normal engagement with the profile of the roller electrode. During the passage of the electrode areas through the welding zone, the wave-like profile of the contact surface is deformed to some extent under the influence of the welding force and heat.

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electrode material. Restoration of the shape of the selected wavy profile of the contact surface before the next entry into the welding zone is carried out by the joint rotation of the rollers with the balls.

Example. The method is used when welding with an airtight seam along the external contour of household oil-filled electric radiators collected by welding from a steel sheet 08PS with a thickness of 0.8 mm. For welding, machine designed and manufactured by the plant by weld welding is used. The roller electrodes are driven by steel cutters of steel 40X, heat treated to the hardness HKSe-54-56. On the clutch surface of the cones, which is the surface mating with the contact surface of the roller, teeth are cut with a step of 1.3 mm and a tooth height of 0.7 mm. After installing the rollers, which at first have a smooth cylindrical contact surface, the profile is rolled by rotating them without welding. Further, in the process of welding, a given profile is maintained by scrolls.

The welding mode for the width of the contact surface of the rollers 8-9 mm (usually recommended 54-0.5 mm) is as follows; compressing force of electrodes 800 daN; welding speed 1.5 m / min; welding current 18 kA; the duration of the welding current pulse is 0.06 s and the duration of the pause between impulses is 0.02 s.

Due to the increased seam width of 8 mm, in terms of mass production of electric radiators, the defect in the absence of tightness of roller seams is almost negligible. In addition, the electric power consumption for welding is reduced and its productivity is increased, it becomes possible to weld seam welding products with high quality that are difficult to weld: seam welding with a guaranteed cast structure in the joint zone requires large compared to solid-phase heat input. At the same time, considerable difficulties in providing stably sealed joints with a cast structure are associated with the fact that, ensuring a minimum amount of melting, it is necessary not to exceed its maximum acceptable level. Otherwise, there is a liquid phase on the surface - burned. At the same time, as the sheet thickness decreases, these difficulties increase.

All of these drawbacks are eliminated in the proposed method.

Claims (1)

Invention Formula The method of resistance seam welding, in which the supply of current, the transfer of force to the parts being welded and their movement are carried out using roller welding electrodes, and the welded joint is performed in the solid phase over the deposited reliefs, characterized in that, in order to increase the quality stability and ensure the possibility of obtaining hermetic welding of sheets up to 1.2 mm thick and making Seams of unlimited length, undulating reliefs are made on the surface of the welding roller electrode, and the ratio of the pitch and depth of the relief wave to the thickness of the thinner part being welded is 1.2-4.2 and 0.5-1.7, respectively.