SU722714A1 - Substrate - Google Patents

Description

I

The invention relates to semi-automatic and automatic welding of butt joints and can be used in the manufacture of welded thin-walled flat and spatial structures of various shapes and dimensions, in relation to products in the shipbuilding, automotive and other industries.

The strength and structural characteristics of a welded butt joint obtained by one-sided welding largely depend on the quality of the formation of the weld metal (first of all, its root).

Famous water-cooled metal lining with forming groove 1

The lining must fit snugly to the edges to be welded using powerful clamping devices based on hydraulic or pneumatic jacks, magnets, etc. But in practice this requirement is difficult to implement (especially for long joints of complex shape). As a result, inevitable and unstable formation of schv due to metal leakage into the gap are inevitable. Along with significant capital expenditures for the manufacture of assembly and welding stands, this method of welding has the following disadvantages: the difficulty of combining the joint of the welded sheets with the axis of the groove on the lining; non-universality of the lining in terms of its applicability for various dimensions, parameters and shapes of butt joints of sheet structures (it is practically used only for simple joints of small length).

The closest in technical essence and the achieved result to the proposed is a lining made in the form of a tape with an adhesive composition 2 applied to its surface.

The use of an adhesive tape consisting of a non-combustible base and a flexible strip containing inorganic substances allows welding of long and complex joints without the use of clamping snap-ins. However, the adhesive layer by which the tape is attached to the sheets to be welded is located along the edges of the lining and must be as far as possible from the welding heating zone, otherwise its adhesive properties will be lost. In this connection, strips must be applied, which inevitably leads to disruption.

the stability of the seam formation due to the inconsistency of the gap between the weld joint and the lining. In addition, such a system is insensitive to the temporal mobility of the edges being welded under conditions of welding heating. All this leads to the flow of molten metal into the gaps between the lining and the product. During the welding process, it is necessary to adjust the amount of filler material supplied, and, consequently, to change the process modes. The form of penetration while unsatisfactory. The disposable lining is applicable only for manual welding of joints of small thickness, welded at low modes (otherwise the lining element is burned). It is difficult to use this method for curvilinear joints. It does not allow any gaps in the joint that is difficult to implement).

The aim of the invention is to improve the quality of welding by intensifying the cooling of the root, the expansion of the range of products to be welded by welding joints with different curvature of the root, and repeated use.

This goal is achieved by using heat-absorbing paste based on evaporating liquid applied along the longitudinal edges of the tape on both sides of the adhesive, and the tape itself is made of a gas-tight material with a microcapillary structure.

FIG. 1 a, b shows a cross-section of a butt joint assembled and welded (16) by the one-sided welding method on a heat-absorbing soft lining; in fig. 2 a, b is an example of two thin sections of welded butt joints.

A thin layer of 2 paste is applied to the surface of the lining in the form of a tape 1 from above along the edges, with which the lining is then glued to the interface of the welded sheets 3 from below. After that, tape 1 is covered with a second layer 4 of the same paste, leaving the middle section open (both above and below).

As the material of the lining 1 choose a tape fabric of inorganic fibers, such as asbestos or fiberglass (the use of another material is not excluded), wetted by a liquid paste base. The presence of structural gaps (or pores) between the fibers of the fabric provides, on the one hand, a microcapillary system (wick), and on the other hand, good gas permeability through the thickness of the lining. The main component of the paste used is a liquid with a high specific heat of vaporization (water is most suitable for this purpose). To create the necessary structural and mechanical properties (density and viscosity) of a microcapillary structure and sufficient adhesion

PROPERTIES entered into the paste other necessary components.

The principle of operation of the heat absorbing soft lining is as follows.

Welding bath 5, having sunk down and entering into heat exchange with the lining tape 1, the impregnated paste liquid and the vapor of the evaporated liquid, is rapidly cooled, which causes a rapid crystallization of the bottom surface of the weld root, preventing any significant sagging of the molten metal. The wick mechanism of the evaporating liquid (for example, water) to be evaporated by the lining material provides the required cooling of the metal in various modes without burning through the tape, thereby allowing the tape to be used repeatedly. At the same time, the effect of welding temperatures is not able to degrade the adhesive properties of the thin layer 2 of paste, since the loss of the liquid base (during evaporation) is compensated by the liquid from the second layer 4 of paste entering through the lining tape 1 into the top layer 2 of paste. heated steam

 areas. The decisive role in this belongs to the microcapillary system: paste 2 - lining fabric 1 - paste 4. Part of the steam that came out of the volume of the top layer 2 paste may accumulate in the cavity between

0 lining and brewed joint and provide “back pressure on the liquid bath, thereby worsening the formation of schv. But this does not occur, since the lining material is gas-permeable in thickness, and the middle part of the tape is not covered with paste. therefore

 the resulting steam freely leaves through the lining 1 to the outside, while cooling additionally the root of the seam, and the central part of the lining.

e If the position of the glued edges of the tape during welding is invariably relative to the product, then its middle part (due to the slight stiffness of the ribbon fabric) has the ability to bend under the action of the weight of the molten weld pool metal, thus forming the weld root in the required manner (size and shape of the melt). This "soft lining provides some freedom in the relative movement of its glued edges,

JJ that does not allow the tearing off of any part or edge of the tape in the conditions of the temporary mobility of the edges being welded (during heating). The proposed method was tested by manual semi-automatic and automatic argon-arc welding.

non-melting electrode of both experimental samples and factory products from aluminum alloys (AMgb, D20, AMg61, etc.). The length of the welded joints ranged from 0.5 m (samples) to 16 m (deck superstructure of the vessel), and thickness from 1 to 6 mm. In this case, a fiberglass ribbon cloth with a width of 30 mm, a thickness of 0.15 - 0.2 mm, and a heat absorbing water-based paste of the following composition were used: weight. %:

Water80 - 88

Palygorskit9 - 14

Fluffed asbestos3 - 6.

This paste has a high heat absorption capacity due to the evaporation of water, sufficient adhesive properties and a microcapillary structure.

Example. FIG. 2 shows two sections of cross-sections of welded butt joints with a thickness of 4 mm and a length of 600 mm from AMgb alloy, made according to factory technology without a lining (“by weight) and using the proposed method. Welding is manual, argon-arc, by surfacing electrode. Welding current 200 - 205 A. Cutting edges absent. The pre-assembly of the joint is on tacks with a pitch of 150–200 mm (gap no more than 1.0 mm).

A 30 mm wide glass tape, 0.15 - 0.2 mm thick, is glued with edges (10 mm wide sections) in the joint zone from the bottom. The second layer of paste thickness of 3 to 5 mm covers the same areas of the back side of the tape. Neither the gland nor any supporting means or devices are used. The welded joint obtained by the proposed method b improves the formation of the root of the seam and reduces the amount of molten metal. At the same time, a narrowing of the welding heating zones, an improvement in the conditions of the welding process (due to the greater stability of the weld pool), a decrease in warp deformations by 2 to 3 times were noted. The complexity of the operation to remove excess fusion, which is 1-3 minutes per 1 running. m seam, practically reduced to zero. Radiocontrol of welded joints gave a positive assessment.

Similar data were obtained when welding joints with a thickness of 1 to 6 mm from aluminum alloys. Big performance

The method is manifested in the manufacture of thin-sheet (up to 3 mm) welded structures. The proposed method is applicable to the joints of any curvature and curvature as at. small, and with their great length. At the same time, good formation is ensured even under the condition of initial (thickness variation of edges) or temporary (during heating) displacement of the edges being welded. The refusal to use any kind of pressing devices, on the one hand, sharply reduces the cost and laboriousness of assembly-welding works and tooling, and on the other hand, improves the manufacturability of the one-way welding method and expands its field of application. Changing the welding mode, the thickness of the metal being welded or its thermal conductivity requires only a change in the number of layers of the lining tape (usually 1–3) and the volume of the second layer of paste. All this makes the proposed method versatile with high workability. Moreover, the economic costs of welding consumables when performing 1 per seam here are also minimal (compared to the known ones) and do not exceed 0.02-0.06 rubles / m.

Claims (2)

1. USSR author's certificate number 452464, cl. 23 K 37/06, 1972. 2. The patent of Germany No. 1552626, cl. At 23 K 37/06, published 1966 (prototype).