RU2697548C1 - Method of friction welding with mixing - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention can be used in production of welded structures and semi-finished products, including from aluminum alloys, by friction welding with mixing. One-sided thickening of parts being welded is performed by simultaneous cold deposition. Thickness and width of the thickening of the edges are selected to make the bearing capacity of the welded joint not less than that of the base metal. Width of bulge of each edge is not less than half of diameter of support collar of welding tool, and deepening of support collar into thickened edges of parts is performed by 0.1–0.2 mm.

EFFECT: possibility of welding without preliminary heating to produce a welded joint, which is not inferior in terms of bearing capacity to base metal.

3 cl, 5 dwg

Description

The invention relates to the field of welding production, in particular to a method of friction stir welding (STP) of butt joints, including aluminum alloys, and can be used in the manufacture of welded structures and semi-finished products, including from aluminum alloys in shipbuilding, aviation , engineering and other industries.

Known methods for welding butt joints by friction with stirring of aluminum alloys, including additional heat treatment or reinforcing deformation, to increase the strength of welded joints (see V. Muravyov. On the relevance of the study of friction stir mixing welding of structures made of high-strength aluminum alloys / V.I. Muravyov , P.V. Bakhmatov, K.A. Melkostupov // Komsomolsk-on-Amur, State Technical University, Scientific Notes No. 11-1 (2). - P. 110-125. And see Poklyatsky A.G. Welding friction with stirring –eff tive way to increase the performance of structures / AG POKLYATSKY etc. .// Automatic welding -.. 2010. -№4 45-50 C)..

However, when welding high-strength aluminum alloys, tensile strength is 85-90% of the strength of the main metal.

Known methods of welding, providing for a preliminary increase in the thickness of the metal in places of welds (thickening of the edges) by thinning the base metal by mechanical or chemical milling, with the exception of the zone where the connection is made by welding (see Chemical milling (contour etching) [Electronic resource]. Access mode : ttp: //megaobuchalka.ru/6/52594.html. Date of circulation 01.12.2017 and see Karachenkov E.M. Improving the quality of hull parts for rocket and space technology: abstract of the dissertation ... of the candidate of technical sciences / E.M Karachenkov; wasps cosmic scientific and derivatives Center of MV Khrunichev -..... Moscow -. 2000).

Such methods can increase the strength of the compounds. However, these operations lead to a decrease in the utilization of the material to 0.5-0.7 and, naturally, to an increase in the cost of the structure. In addition, these processes are very laborious.

A known method of welding butt joints, including preliminary thickening of the edge by uniform heating of the part along the entire length of the edge, followed by its deformation under pressure (see SU No. 174741 A1, B23K11 / 02, B23K11 / 05, publ. 1965).

The disadvantage of this method is carrying out pre-heating, which leads to softening of the workpiece material.

The technical result is a preliminary thickening of the edges of the welded parts before welding without using heat.

The technical result is achieved by conducting a preliminary one-sided thickening of the edges by an amount that compensates for the missing bearing capacity of the welded joint by simultaneously precipitating the ends of the parts to be welded, followed by friction welding with stirring by deepening the tool support collar into the edge thickening.

Thickening of the edges of the welded parts by upsetting their ends is preferably carried out by cold rolling.

The height of the thickening of the edges (h = HS, where H is the thickness of the edges at the site of thickening, S is the thickness of the metal) that compensates for the missing bearing capacity (breaking load under static loading of samples with the same cross-sectional area of the base metal) of the joint, taking into account the thickness of the edges in the place of the thickening, which is preferably not less than the product of the ratio of the load-bearing capacity of the base metal Rum and the welded joint Rcc (Rum / Rcc) by the thickness of the base metal. That is, the value of H is determined by the formula

,

,

where P _ohm is the bearing capacity of the base metal,

R _ss - bearing capacity of the welded joint.

Friction welding with stirring is carried out by immersing the tool support collar in the thickened edges, preferably to a depth of 0.1 ... 0.2 mm, to ensure its friction against the surface of the thickened edges.

The total width of the thickening of the edges 2b is preferably not less than the diameter of the tool shoulder for STF (2b ≥ d, mm, where d is the diameter of the tool shoulder), which is associated with the need to ensure friction of the entire supporting collar of the welding tool on the surface of the thickened edges.

In FIG. 1 shows the geometry of the thickened edges, where S is the thickness of the metal; h is the height of the thickening of the edges; b is the width of the thickening of the edges; H is the thickness of the edges at the site of thickening.

 The difference of the proposed method from the prototype is that

* edge thickening is carried out without preliminary heating of the upsetting edge,

* Thickening of the edges is carried out on the one hand by an amount that provides compensation for the missing load-bearing capacity of the joint, by simultaneously sinking the ends of both welded parts.

In FIG. 2 shows a setup diagram for a one-sided thickening of the edges of two parts to be welded simultaneously, where a is the general view of the setup, b is a diagram of the thickening of the edges, R is the outer radius of the roller, R _d is the radius of the deforming surface of the roller, C is the width of the roller.

The apparatus for thickening the edges to be welded consists of a universal milling machine 1, on the rolling pin 2 of which a deforming roller 3 is installed. A vice 5 is placed on the machine table, in which two workpieces 4 are fixed, the edges of which are subjected to thickening. Installation works as follows. Thickened workpieces are installed along the creek of the deforming roller. By lifting the table create a predetermined amount of upsetting edges Δ. Include moving the table along the creek of the roller. In this case, the weld edges are upset by Δ along the entire length of the workpieces. The dimensions used are preferably as follows:

- the radius of the deformation roller R _d ≥70 mm to facilitate the deformation of the edges of the parts,

- outer radius of the roller R ≥ R _d + 1,5b mm for guaranteed placement of thickened edges in the creek of the roller,

- the width of the roller C ≥ 6S, mm to prevent deformation of the roller.

- the width of the brook (groove) of the roller 2S + 2h.

The following is an example embodiment of the invention.

Used workpieces from aluminum alloy AMg6 thickness S = 4mm.

The height of the thickening is determined as follows.

The load-bearing capacity of the base metal, Rum = 1810 kg and of the welded joint without thickening, Rss = 1630 kg, was experimentally determined.

In this case, to obtain the bearing capacity of the welded joint not less than the same characteristics of the base metal, the thickness of the edges to be welded must be increased in (1810/1630) 1,11.

Thus, the thickness of the edges at the site of thickening should be at least H = 1.11x4 = 4.44mm. Accepted the required height of the thickening of the edges h = H-S = 0.5 mm.

To ensure the quality of the joint obtained by STF, the width of the thickening of each edge b should be greater than d / 2, where d is the diameter of the tool shoulder. A welding tool with the following main dimensions has been selected. The diameter of the tool shoulder d = 15mm; the working shaft of the tool is made in the form of a truncated cone, the diameter of which at the base is 4 mm, with a vertex of 2 mm, height 4 mm. The width of the thickening of each edge (b ≥ d / 2) is selected in the range of 8.0 ... 8.7 mm.

The welded workpieces were combined with side surfaces and fixed in a vice, and the end thickened surfaces of the workpieces with a thickness of S = 4 mm were installed along the stream deformation roller of the installation for one-sided thickening, achieving their deviation in the horizontal and vertical planes of not more than 0.2 mm over the entire length of the workpieces.

The geometric dimensions of the deformation roller are as follows:

- the radius of the deforming roller R _d = 70 mm;

- the outer radius of the roller R = R _d + 1,5b = 70 + 12 = 82 mm;

- roller width C = 6S = 24 mm

- the width of the brook (groove) of the roller 2H = 2S + 2h = 2x4 = 9.0 mm.

Raised the machine table until the bottom of the groove of the roller touches the beginning of the workpieces, and then lifted the machine table by Δ = 0.5 mm at each pass, to achieve the edge Δ that is necessary to fill the entire width of the groove and the width of the thickening of each edge (b ≥ d / 2) within 8.0 ... 8.7 mm. Horizontal movement of the table was turned on and a roller was rolled along the entire length of the thickened workpieces. Thus there was a thickening of the edges. In three passes, an edge draft of 1.5 mm was obtained. This turned out to be sufficient for the metal to fill the entire width of the groove 2H = 2S + 2h = 9.0 mm, and to create thickenings of the edges with a width of b = 8.3 mm.

The geometry of the thickened edges obtained is shown in FIG. 3, where the height of the thickening of the edges h = 0.5 m, and the width of the thickening of each edge b = 8.3 mm

Welding was carried out on a vertical milling machine in the following sequence:

- the workpieces were laid on the lining with a thickening upwards, so that the center of the working rod of the tool passed along the line formed by the joined edges, in this position the welded workpieces were fixed;

- carried out welding in the mode:

* the angle of inclination of the tool 1,5-2 ^about ;

* tool rotation speed of 15 s ^-1 ;

* table movement speed (welding speed) 14 m / h;

* immersion of the support collar of a rotating tool in the thickened edges by 0.1-0.2 mm;

* included a longitudinal table feed and carried out the welding process;

* at the end of the seam, the movement of the product relative to the tool was turned off, the tool was removed from the resulting connection;

- thin sections were cut out from the obtained welded joints and the thickness of the welded joint was measured in various sections using a measuring instrument microscope DIP 6.

The appearance of the samples welded along the thickened edges is shown in FIG. 4. The fracture pattern of the welded joints shown in FIG. 5, indicate that the bearing capacity of the welded joints is not inferior to the bearing capacity of the base metal (rupture occurs in the base metal, and not in the welded joint).

Thus, the execution before welding, the operation of thickening the edges by an amount that provides compensation for the missing bearing capacity, allows you to obtain welded joints that are not inferior in bearing capacity to the base metal. Preheating during edge thickening is not used.

Claims (5)

1. A method of friction welding with stirring, including deepening the tool shoulder in the welded edges of the parts, characterized in that they preliminarily carry out a one-sided thickening of the welded edges of the parts by simultaneous cold upsetting, while the thickness and thickness of the thickening of the edges are selected from the condition of obtaining the bearing capacity of the welded joint not less than the bearing capacity of the base metal, and the width of the thickening of each edge is at least half the diameter of the supporting shoulder of the welding tool, and the deepening of the support collar in the thickened edges of the parts is carried out by 0.1-0.2 mm 2. The method according to p. 1, characterized in that the height of the thickening of each edge is not less than the product of the ratio of the bearing capacity of the base metal and the welded joint to the thickness of the base metal minus the thickness of the base metal. 3. The method according to p. 1, characterized in that the cold precipitate is carried out by rolling.

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