SU1281318A1 - Moulding and welding unit for high-frequency lap welding mill for helical welded tubes - Google Patents

Abstract

The invention relates to a form-welding device and can be used in mills. High-frequency welding of thin-walled spiral-welded pipes with a joint with overlap. The aim of the invention is to create optimal conditions for uniform heating of the edges by forming a strip with permissible gaps and a rational angle of convergence of the edges. The web of rollers of the feeding machine is pushed between the upper 3 and lower 4 heads of the wiring into the molding device 5, where it is rolled into a tubular billet. Before the zone of heating the edges for welding, the edge of the coil strip with the help of a wedge-shaped shoe 10 smoothly rises upwards, which allows an increase in the angle of convergence of the shank determined by the specific conditions of molding and welding. When the angle of convergence increases, the zone of close contact of the edges is reduced, where the edges can spontaneously touch, which causes them to overheat and burn out, and the area from the contact point to the pick-up rollers 6, 7 is disconnected from the electrical circuit and underheated. 4 il. g (/) S 00

Description

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The invention relates to the processing of metals by pressure and welding, more precisely to forming-welding devices when welding pipes and can be used in high-frequency mills of thin-walled cutting-edge pipes with overlapping edges.

The purpose of the invention is to create optimal conditions for uniform heating of the edges in front of the shoveling rollers for forming the strip with permissible gaps and a rational angle of convergence of the edges.

FIG. 1 shows a molding-welding unit, a view to the airframe in FIG. 2, section A-A in FIG. 1J on .fig. 3 - section bb pa fig. 2; in fig. 4 - section b-B in FIG.

The forming and welding unit of the mill consists of a rotary frame 1 on which the feeding machine 2 upper 3 and lower 4 slabs of the front guide wire are mounted. A mounting device 5 is installed behind the wiring, on which the upper 6 and lower HHi f 7 securing rollers are fixed. In front of the rollers in the wiring windows, a contact current lead system of the welding device 8 is installed, and a wedge shoe 10 is fastened to the bottom wiring plate in its front part with screws 9.

In order for the coil strip to flow into the wedge 66p ci3Hbui shoe 10 without scoring, the bottom plitovina-A wiring smoothly mates with it.

Before the heating zone of the edges for welding, at the installation site of a tokopodvodon, the guide surface of the shoe protrudes above the bottom slab plane by an amount whose value is determined from specific molding parameters (pipe diameter, roll width, molding angle) and the condition of the welding gap between edges in optimal limits.

It has been established by practice of pipe welding production that this gap should be within 8–12 mm when installing the current leads at a distance of 65–70 mm from the vertical axis of the roller bearers.

The distance h (Fig. 2) with current-carrying contacts in the vertical plane is equal to the welding gap between the plates at the place of their mouth.

new at once:

and is determined as follows: h h. + a,

., -, (О where Vi is the distance between the contacts under the natural conditions of the convergence of the edges; and is the magnitude of the rise of the wedge-shaped shoe at the place of installation of the current-carrying contacts.

The value of h is determined by a mathematical relationship from the following relationship:

h, .V-, (2)

D

ittP20

25

,;

thirty

where i

ot is the distance from the vertical axis of the pinch rollers to the current-carrying contacts; the angle of installation of the front guide wiring is equal to the angle of forming the coiled strip B, the spiral pipe, the diameter of the forming device, the same diameter of the pipe being made. Substituting the value of h, from the formula (2) into the formula (1), determine

(3)

D

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. 1Gy sin V

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ChSTR.

Thus, with the provision of 5

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No optimal welding gap. An equation is derived for determining the amount of strip edge lifting using a shoe, depending on the specific molding and welding parameters.

Molding-welding unit works as follows.

The coil strip with the thickness S of the rollers of the feeding machine 2 is pushed through the slot formed by the upper 3 and the lower 4 plates of the front wiring and the molding machine 5, where the strip is coiled into a pipe billet.

The installation angle of the front guide wiring oL can be adjusted by rotating the frame 1 around a vertical axis passing through the zenith of the pipe at the installation site of the end shank rollers 6 and 7, the angle value being determined by the dependence

D- l

soz

where B is the width of the roll strip,

d - the amount of overlap of the edges of the strip of pipe;

312

 - diameter produced

pipes, 1 3.14.

In front of the heating zone for welding, the edge of the coil strip, with the aid of a wedge-shaped shoe 10, rises smoothly upwards, which allows increasing the angle of convergence of the edges to the values determined by specific conditions of molding and welding.

With an increase in the convergence angle, the zone of close adjoining edges in front of the shunting rollers is reduced, in which the edges can spontaneously contact each other at different distances from the axis of the rollers and thereby cause an instantaneous change in their temperature heating mode. they are overheated or burned out, and the area from the point of contact of the edges to the pick-up rollers, disconnected from the electrical circuit, is underheated and remains unwelded. With certain values of the angle of convergence of edges, the point of their meeting is at a constant distance from the axis of the pick-up rollers, which allows to obtain stable conditions for the heating mode.

At the same time, the maximum angle of convergence of the edges should not exceed the limits of permissible, allowing maximum use of the positive properties of high frequency currents, such as the surface effect and the proximity effect.

The edges of the strip and the first spiral-formed pipe coil, heated to the welding temperature by high-frequency currents, which are summed up by the contact system of the welding device 8, are pushed between the idle guide rollers, compressed and form an overlap weld.

Thus, the proposed design of the molding-welding unit allows creating optimal ways of heating the edges for welding for pipes in a wide range of diameters.

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by rational setting of the angle of convergence, as well as reducing the power consumption for heating by working at the minimum allowable welding gaps.

As a result, it becomes possible to improve the mill's productivity and the quality of welding of the pipes produced.

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Claims (1)

Invention Formula A molding unit of a mill for high-frequency welding of spiral-seam overlapping pipes, containing a feeding machine, guide wiring with upper and lower slabs, a molding device with ball-bearing rollers and contact welding device, characterized in that in order to create optimal conditions for uniform heating of edges in front of the shafts by forming a strip with permissible gaps and a rational convergence angle, it is equipped with a guide wiring mounted on the bottom slab butt-shaped shoe, the working surface of which has an angle of elevation facing the grooved rollers, protrudes above the bottom slab from the side of the crimping rollers by about. determined from the expression hr l ffo. - - 2-sinc . e h is the distance between the current-carrying contacts in the direction perpendicular to the working planes of the plates,  - the distance from the grooving rollers to the current-carrying contacts; d - front mounting angle guide wiring; - diameter of the molding device, from the opposite side, a smoothly spawning wife with a lower slab .. . Editor N. Tupitsa fpuz. Compiled by E. Vetrova Tehred L, 0 Lane (Figure 1 Proofreader M. Maksimishinets