RU2460617C1 - Combined friction welding method - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: after workpieces are prepared and fixed, rotating disc tool is submerged into the butt joint between workpieces and moved at welding speed along the weld. Welding is performed in two passes. The first pass is performed with disc tool with its being submerged to the depth providing the formation in lower part of butt joint of weld with height of 1-2 mm, and with formation in upper part of butt joint of the slot equal to thickness of disc tool. After that, additive for example in the form of T-section with rib thickness equal to slot thickness is put into the slot. The second pass is performed by friction welding and using rotating bar tool with its submersion into additive to the slot depth overlapping the root weld.

EFFECT: method allows obtaining quality connections of long structures from materials with thickness of more than 4 mm, which are not welded by fusion.

2 cl, 6 dwg

Description

Technical field

The invention relates to welding processes, and more particularly to the field of friction welding (friction welding), and can be used in various fields of mechanical engineering and construction for connecting joints of long lengths mainly of sheet elements and structural units made of aluminum, magnesium alloys and other structural materials, including including materials not fusion welded.

State of the art

A known method of friction welding (USSR author's certificate No. 195846 of 1967, International Patent WO 93/10935 of 1993), in which a tool having a rod shape is rotated about its axis and immersed in the joint between the ends of the workpieces to be joined, and then move it along the junction line. In this case, the work of friction forces plasticizes the material to be welded and it is transferred to the area that is released behind the tool, where a weld is formed. The disadvantage of this welding method is the asymmetry of the weld, high demands on the accuracy of assembly for welding, thinning of the cross-section at the weld site (which leads to a decrease in joint strength) and the difficulty of ensuring stable formation of the root of the weld.

A known method of friction welding (RF patent No. 2173619 C1 of 2001) by which a disk tool, rotating around its axis, is immersed through the slot of the squeezing seam of the additional device in the joint of the parts to be joined is a prototype. When the rotating tool (disk) is rubbed against the workpiece material, the latter is plasticized and transferred to the area behind the tool, where the weld is formed. When welding according to this method, the weld metal fills the groove left by the moving disk with a width equal to the thickness of the disk, only by a small height due to material deficiency caused by the fact that when the rotating disk moves, the heated plastic material of the joined edges is pressed and thickened, and also that part of the material is carried out by a rotating disk to the surface of the edges. With increasing thickness of the connected parts, the complexity of filling the groove increases.

Also known is a method and device for friction welding (Ukrainian patent No. 69459 C2 of 2004), according to which filler material in the form of a tape or wire is fed into the welding zone, and the workpieces are pressed to the lining with an additional device in the form of a slider. The disadvantages of this method are the difficulty of ensuring the stability of the feed of the tape or wire under the rotating disk and their processing, as well as the complexity of the equipment.

SUMMARY OF THE INVENTION

The objective of the present invention is to develop a method of friction welding, which allows to obtain high-quality joints of long structures from fusion-weldable materials with a thickness of more than 4 mm.

The problem is solved in that in the method of combined friction welding, mainly long sheet metal parts, including preparing and fixing the workpieces, immersing the rotating disk tool in the joint between the workpieces and moving it at a welding speed along the seam, welding is performed in two passes, with the first pass carry out a disk tool with immersion to a depth that ensures the formation of a root weld with a height of 1-2 mm in the lower part of the joint and a groove equal to the thickness of the disk instrument, the top of the seam, whereupon the groove lay additive, e.g., in the form of T-sections with an edge thickness equal to the groove width, and the second pass is carried out friction welding rod rotating tool with its immersion in the additive on the groove depth.

Thus, the problem of material shortage in the seam is solved and a high-quality seam is formed, since the root of the seam is formed by disc welding, which, in this case, is insensitive to the deviation of the gap between the joined edges, and a second seam by friction welding to form a full-length seam.

List of figures in the drawings

The proposed method is illustrated by drawings, in which:

figure 1 shows the execution of the first pass with a rotating disk tool 3;

figure 2 shows a cross section of the connection after the first pass; the groove and the formed root of the seam 2 are visible in the drawing;

figure 3 is an additive in the form of a T-profile 4 embedded in a groove;

figure 4 shows a working rod 5 of a tool 6 immersed in a joint with an additive embedded in a groove (shown by a dotted line);

figure 5 shows the implementation of the second pass by friction welding with a rotating rod tool 5;

figure 6 shows a cross section of the seam 7.

Designations in the drawings:

ω _d - the direction of rotation of the disk tool;

ω _with - the direction of rotation of the core tool;

V _d - vector of the speed of welding by a rotating disk;

V _with - the vector of the welding speed by a rotating rod tool;

1 and 1 'are connected elements;

2 - disk tool;

3 - the root of the weld formed by a rotating disk;

4 - mortgage additive (for example, in the form of a T-profile);

5 - working rod of the tool for friction welding;

6 - tool for friction welding;

7 - a weld formed by the second pass by friction welding with a rotating rod tool;

h _d - the immersion depth of the rotating disk tool;

s is the thickness of the disk tool;

k is the height of the root of the weld formed by a disk tool;

h _with - the immersion depth of the rotating working rod of the tool.

The implementation of the invention

The invention is implemented as follows.

The combined friction welding method is intended primarily for welding long sheet metal parts with a thickness of more than 4 mm. The method includes preparing and fixing blanks. After that, a rotating disk tool is immersed in the joint between the workpieces and moved with a welding speed along the seam. In this case, welding is carried out in two passes. The first pass is carried out with a disk tool with immersion to a depth that ensures the formation of a root weld with a height of 1-2 mm in the lower part of the joint and a groove equal to the thickness of the disk tool in the upper part of the joint. After that, an additive is laid in the groove, for example, in the form of a T-profile with an edge thickness equal to the width of the groove, and a second pass is carried out by friction welding with a rotating rod tool with immersion in the additive to the depth of the groove.

Billets 1 and 1 ', mostly more than 4 mm thick, (Fig. 1) are assembled for welding either directly on the machine carriage and pressed against it with standard hammer bolts or in an assembly-welding device with clamping bars rigidly fixed to the machine carriage. The welded joint between the workpieces immersed to a depth h _d rotating at ω _d (200 ÷ 1500 rev / min) Disk tool 3. The tool 3, continuing to rotate, is moved at a speed V _d (100 ÷ 2000 mm / min) along the line the junction of the welded workpieces and form the root 2 of the weld with a height k and a groove of depth h _d and a width s equal to the thickness of the disk tool 3 (Fig.1, 2). In this case, a higher rotation speed ω _d , lower welding speed V _d are used for welding materials with a relatively high plasticization temperature, and vice versa. The immersion depth h _{d is} chosen so that the distance from the lower surface of the workpieces to the lower point of the disk tool is about 1-2 mm (regardless of the thickness of the materials being welded), while higher values of h _d are selected when welding materials with a relatively high plasticization temperature, and also when welding with high speeds at low speeds of rotation of the tool. After the first pass, an additive is laid in the groove. An additive in the form of a T-profile (FIG. 3), plate, bar or tape may be used.

The second pass is performed by friction welding with a rotating rod tool. The tool 6 with the working rod 5 is rotated at a speed of ω _c (200 ÷ 2000 rpm), immersed in the joint (Fig. 4, 5) with the embedded additive 4 (shown in dotted line in FIG. 4) to a depth of h _c . Next, the tool, without stopping rotation, is moved at a speed of V _s (80 ÷ 800 mm / min) along the joint, forming a weld 7 with overlapping root of the seam 2 (Fig.5, 6). In this case, a higher rotation speed ω _c and a lower welding speed V _c are used for welding materials with a relatively high plasticization temperature, and vice versa. The immersion depth h _c should provide overlapping of the root suture with a suture made by the second passage (h _c , as a rule, is greater than h _d by 0.2-0.5 mm). At the end of welding, without stopping the rotation of the tool 6, it is removed from the junction of the workpieces and the drives of rotation and working movement of the tool relative to the welded assembly are turned off.

The parameters of the welding mode (rotational speed of the disk tool, its immersion depth and welding speed) are determined empirically - by welding control samples and assessing the quality of the root seam according to a number of criteria:

absence of defects, height “k” of the root suture (at least 0.5 groove width), its geometry (absence of sharp surface angles). In particular, high-quality root welds were obtained when welding an aluminum alloy D19 with a thickness of 8 mm by a disc tool with a diameter of 110 mm and a thickness of 2.5 mm at a rotation speed of 200 rpm and a welding speed of 200 mm / min with immersion to a depth of 6 mm. They laid various types of additives: brands, bar, plate and tape from material D19. Friction welding with a rod tool was performed at a rotation speed of 1000 rpm and a welding speed of 125 mm / min with immersion to a depth of 6.2 mm. Combined frictional welding of the samples was carried out on two milling machines: horizontal milling (welding with a root tool by a disk tool) and vertically milling (welding of the second pass to obtain a full-sized seam). Instead of a cutting tool, a disk tool and a core tool were installed, respectively. Milling machines allow the necessary technological movements during welding: transverse movement of the machine carriage - to install the tool on the joint line; longitudinal movement of the carriage - for the working movement of the tool along the junction line and the vertical movement of the carriage - for immersing the tool to a given depth.

Technical appraisal and economic advantages of the proposed welding method

1. The proposed method allows to solve the problem of material shortage during friction welding, allowing to obtain a stable and high-quality weld (without discontinuities and non-fusion) with significant fluctuations in the gap between the welded workpieces (within the thickness of the disk tool), which is especially important when welding long structures.

2. The conditions for the formation of the weld root (increased temperature and pressure in the localized volume of the metal with symmetry of the heating source) are improved and the likelihood of root defects is reduced, thereby improving the quality of the welded joint.

3. It becomes possible to influence the chemical composition of the weld and the properties of the welded joint by selecting the filler material (for example, in the form of a T-profile) of the optimal chemical composition that provides the required properties of the welded joint.

Claims (2)

1. The method of friction welding, mainly long sheet metal parts, including preparing and fixing the workpieces, immersion in the joint between the workpieces of a rotating disk tool and moving it at a welding speed along the seam, characterized in that the welding is carried out in two passes, while the first pass is performed by disk tool with immersion to a depth that provides the formation of a root weld with a height of 1-2 mm in the lower part of the joint and a groove equal to the thickness of the disk tool in the upper part of the joint a, after which an additive is laid in the groove and a second pass is carried out by friction welding with a rotating rod tool with immersion in the additive to the depth of the groove with overlapping root suture. 2. The method according to claim 1, characterized in that they use an additive in the form of a T-profile.

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