RU2302933C1 - Centering device for assembling ends of tubes for welding - Google Patents

Abstract

FIELD: processes for assembling tube ends for welding, namely for electron beam welding in vacuum tubes and tubular articles of chemically active metals such as zirconium, titanium.

SUBSTANCE: centering device is in the form of rod onto which pressure pipe is put. On one end of said rod there is attachment for mounting rod in elongated tube; on other end of rod there is threaded portion with two nuts and detachable elastic flange with large perforated holes for fastening short end part on end of elongated tube. Attachment for mounting rod in elongated tube is in the form three movable parallelograms uniformly secured to rod along circle and used for changing diameter of circle described around them by moving nut and pressure tube. Three pushers are jointly uniformly mounted on end of pressure tube along its outer diameter by their one end portions; other ends of said pushers are jointly coupled with links of parallelograms parallel to axis of rod. Links of parallelograms parallel to rod axis are covered with elastic material.

EFFECT: enlarged functional possibilities of centering device due to using centering device of one type and size for welding tubes in wide range of their diameters.

3 cl, 3 dwg, 1 ex

Description

The invention relates to internal centralizers for assembling and aligning pipes for welding, mainly for welding in chambers with a controlled atmosphere, for example, for electron beam welding in tubes of chemically active metals in vacuum.

In electron beam welding of pipes, especially in welding without filler, especially high demands are placed on the assembly of joints, mainly on the absence of various gaps in the joint assembled for welding.

Known closest to the claimed centralizer, both in technical essence and in the achieved technical result, a device for assembling and aligning a long pipe with a short pipe, for example, with a pipe, adapter, etc., adopted as a prototype (see patent RU No. 2169654 , MKI ⁵ V23K 37/053, 06/27/2001, bull. No. 18).

The main disadvantage of this centralizer is a narrow range of diameters of the joined pipes, which can be joined and centered using one standard size of the centralizer. The permissible variation in pipe diameters that can be assembled and centered using one centralizer is not more than 6-8 mm, because the device for fixing one end of the rod in a long pipe is made on the principle of compression of a set of rings of elastic vacuum rubber, which, when axially compressed, increase their outer diameter by several millimeters and firmly wedge in the pipe.

To assemble and center pipes of a larger or smaller diameter, it is necessary for each pipe size to have a separate copy of the centralizer, which is technologically and economically disadvantageous.

The problem to which the claimed invention is directed, is to create a centralizer design for connecting the ends of the pipes for welding, mainly for pipes with an inner diameter of more than 60 mm, which would ensure the assembly of pipes in a wide range of diameters, while ensuring the complete absence of gaps in the assembled for welding junction.

The technical result consists in the fact that the inventive device allows one type of centralizer to center and tighten the ends of the pipes for welding in a wide range of diameters, as well as to center and assemble long pipes with end parts having an internal passage hole much smaller than for a long pipe.

The specified technical result is achieved by the fact that in the centralizer for connecting the ends of the pipes for welding, containing a rod, on one end of which there is a device for fixing the end of the rod in one of the pipes, and on the other end a thread with two nuts is made, while the rod is pressed a tube moved by one of the nuts to fix the end of the rod in the pipe, and the other nut serves to fix the alignment of the pipes and compress their ends before welding, and the device for fixing the end of the rod in one of the pipes is made in the form of x parallelogram uniformly fixed on the shaft circumferentially, wherein at the end of the push tube uniformly with respect to its outer diameter are hinged at one end three tappet pivotally connected to the second ends of the links of the parallelograms, parallel to the core axis;

- in addition, a compression spring is installed on the rod between the end of the pressure tube and the parallelogram hinge closest to the pressure tube;

- in addition, the links of parallelograms parallel to the rod are covered with elastic material.

A device for fixing one end of the centralizer rod in a long pipe in the form of articulated parallelograms, which, under the influence of the pressure tube and nut, can increase and decrease the diameter of the circle described around the links parallel to the rod, expands the technological capabilities of the centralizer, allowing one type of centralizer to collect and weld pipes in a wide diameter range.

The invention is illustrated by drawings, where Fig. 1 shows a centralizer inoperative when the parallelogram links parallel to the rod are folded under the action of a spring, while in the drawing two parallelogram links are conventionally shown in the same plane, although in a real design they are located around the rod through 120 °.

Figure 2 shows the centralizer in the working position, when the long tube is assembled and centered for welding with a bimetal adapter sleeve, the adapter is shown in thin lines.

Figure 3 shows a view of the centralizer along arrow A.

The centralizer is made in the form of a rod 1, on one end of which there is a device for securing the rod in a long pipe in the form of three hinged parallelograms uniformly around the circumference fixed on the rod 1, and on the other end of the rod there is a push tube 2 moved by a nut 3, as well as thin elastic flange 12 with holes 14, designed to increase the elasticity of the flange, as well as to improve the pumping of air from the pipes being welded if they are assembled for welding in a controlled atmosphere, for example, in vacuum. Using the flange 12, the ends of the pipes are fixed, centered and compressed by moving the nut 13 along the threaded part of the rod 1.

To change the slope of the swinging links 8 of the parallelograms, pushers 5 are used, one ends of which are pivotally mounted on links 6 parallel to the rod 1, and the other ends are pivotally mounted on the end of the pressure tube 2.

Due to the movement of the pressure tube 2, it is possible to change the diameter of the circumference described around the links 6, which makes it easy to insert the centralizer into the pipe and firmly fix it in it.

To simplify the folding of parallelograms between the end of the pressure tube 2 and the hinges closest to the pressure tube on the rod 1, a compression spring 4 is installed.

In order to significantly increase the friction between the links bursting in a long pipe and the inner surface of the pipe, the links are coated with an elastic material, for example, vacuum rubber.

The centralizer works as follows.

First, the centralizer in folded form, as shown in Fig. 1, is inserted into the long pipe from the side of the welded joint 11 and set at such a depth that the length of the rod end with the flange 12 and the nut 13 is sufficient to install the end piece 10 welded to the long pipe 9. After that, the pressure tube 2 is moved by tightening the nut 3 until the links 6 of the parallelograms abut against the wall of the pipe with the force necessary for a slight deformation of their elastic coating 7, which is a condition for strong fastening laziness in the long tube of the rod 1 of the centralizer.

After fixing the rod 1 in the long tube 9 of the rod 1, the nut 13 is unscrewed from it and the elastic flange 12 is removed, then the welded end piece 10 is put on the rod 1. Then the flange 12 is put on the rod 1 and the nut 13 is screwed on. The butt welded end of the end part 10 is manually joined with the end of the long pipe 9 and at the same time tighten the nut 13 so that the compression force of the ends allows them to be centered, and then finally compress using the nut 13 and the elastic flange 12.

Execution example

Using a centralizer, a long tube of zirconium alloy with a length of 8 m and an outer diameter of 88 mm, with a wall thickness of 4 mm, with a zirconium-steel bimetallic adapter, 200 mm long, with an outer diameter of 88 mm and an inner diameter of 75 mm was assembled for vacuum welding. as shown in figure 1 in thin lines.

A pipe with an adapter assembled for welding is a part of the core of a channel nuclear reactor. The end of the assembled pipe with the adapter was placed in the welding vacuum chamber of the cathode-ray unit, having previously vacuum-tightly sealed the butt-free end of a long pipe, for example, using a rubber stopper. A working vacuum was created in the welding chamber (5 · 10 ^-5 mm Hg) and welding was performed. The centralizer reliably ensured the assembly and alignment of 11 welded edges of the long pipe and adapter, which created favorable conditions for the formation of a high-quality welded joint.

Claims (3)

1. The centralizer for connecting the ends of the pipes for welding, containing a rod, on one end of which there is a device for fixing the end of the rod in one of the pipes, and on the other end a thread with two nuts is made, while the rod is equipped with a pressure tube that is moved by one of the nuts for fixing the end of the rod in the pipe, and the other nut is used for fixing, centering the pipes and compressing their ends before welding, characterized in that the device for fixing the end of the rod in one of the pipes is made in the form of three hinged parallelograms equal to numerically mounted on the rod around the circumference, while at the end of the pressure tube uniformly three ends of the pusher pivotally connected at one end with pivotally connected second ends with parallelogram links parallel to the axis of the rod. 2. The centralizer according to claim 1, characterized in that a compression spring is installed on the rod between the end of the pressure tube and the parallelogram hinge closest to the pressure tube. 3. The centralizer according to claim 1, characterized in that the parallelogram links parallel to the rod are coated with elastic material.

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