UA69459C2 - Method and device for friction welding by rotating disk - Google Patents

Abstract

The method for friction welding by rotating disk and device for its realization can be used in different branches of machine building for execution of joint and T-welds of large length in the sheet and shell structures of aluminum, titanium or other alloys, and at welding of thermoplastic polymers. Friction welding of the butt-joint sheet parts is performed by means of the rotating disk and slider, which are displaced progressively in the direction of welding together in such a manner that the slider is located behind the disk on the surface of parts, and the disk through the slider slot is submerged into the joint of parts. The material of joint is heated by disk to the plasticized condition as a result of work of frictional forces, it is transferred into the area behind the disk, where it is forcedly removed from the disk and is pressed out. The filler material is forcedly introduced into the front area of the welding zone, this is forced against the generatrix of the disk surface and with the help of the reception chamber located in the front section of the slider, is accumulated in plasticized condition. In the area behind the disk the material of joint is formed with strengthening under conditions of pressing, to this end the generating surface of slider is executed with a groove being converged. For developing the joint, a flange is made on the disk. It provides the possibility of alloying the material of joint, formation of required radius passages of corner and joints of different thickness or strengthening of the butt joints and decrease of the joint width. Weld quality as a result of the best uniformity and density of structure is also increased, the speed of welding is increase for 2-3 times, requirements for quality of the groove preparation of the welded parts are reduced, and the range of thicknesses of parts being subjected to welding is increased.

Description

Description of the invention

Field of application: Friction welding with the help of a rotating disk can be used in 2 shipbuilding, rocket-building, aircraft-building industry and other branches of mechanical engineering to make long-length butt and fillet welds in sheet and shell structures made of aluminum, titanium and other alloys. It can also be used when welding thermoplastic polymers.

Analogues: In the well-known method of friction welding, the parts to be welded are first heated by mutual friction against each other at the point of contact, and then compressed and fixed during cooling. This 70 process is relatively simple to implement when connecting cylindrical parts. For parts of other shapes, the use of complex devices is required, which create mutual back-and-forth displacement of parts with a high frequency. For example, in the US patent Мо346732 (method of butt welding of sheets), high precision of fit and straightness of the joint are required to obtain high-quality connections. Friction welding of long sheet parts of small thickness has not found application in industry. 12 A known method of friction welding (AS USSR Mo1586879 dated 31.10.88), during which the ends of the parts to be joined are heated with the help of a rotating disk made of temperature-resistant material, and after that the connection is forged. The disadvantage of this method is that it is necessary to heat the large width of the edges to a high temperature. When welding large thicknesses, such heating is ineffective. In addition, the method can be applied only to materials that can be welded by forging.

A known method of friction welding using a rotating disk (З01655725А, В23К20/12, 15/06/1961), in which a groove is made on the surface of the parts at the joint, along which the disk moves forward in the direction of welding. To implement the welding process, the creative surface of the disc has a symmetrical groove in such a way that the side parts of the disc have a larger diameter and are more deeply immersed in the parts during welding. Due to the shape of the groove, the plasticized edges are brought together and the process of connecting them due to compression occurs. The most significant drawback of this method is the unsatisfactory quality of the connection along the edge closure line. Gee)

Departmental original method of welding, protected by the pioneering patent of IRM: МУ095/1035 dated 10.06.93;

IRS V2Zh 20/12, B29C 65/06 and specified by patent UU095/26254 dated 05.10.95 under the name friction welding with stirring (Rgisiop eig U/eidipuo, EBMU).

The essence of the method is that for welding the parts assembled in a joint and pressed to each other by the edges to be welded, an intermediate working tool is used in the form of a rotating rod made of a material that is more heat resistant than that of the parts, which sinks in during welding into the body of the parts, rotates and moves relative to them, while creating a plasticized zone in the connection as a result of heating by friction, and in the zone of plasticization, the material of the connection undergoes movement with mixing. To implement the process, the rod is structurally designed in such a way, which has, first, a flattened part of the end, which frictionally touches the surface of the parts to be welded, and, second, a central part of a smaller diameter, which protrudes from the end in the shape of a finger. During welding, the protrusion is immersed in the metal for almost its entire length thickness and mixes it during rotation. To form a joint, conditions are created for pressing the material in the rear mixing zone. In the known methods for this are enslaved from the sides with auxiliary clamps, and with the end of the rod, the welding zone is pressed against the substrate, and to improve the mode of pressing, the rod is deflected back at some angle. What is fundamentally new in this method, unlike other methods of friction welding, is that here the material of the parts is removed at the edges and moved with mixing and pressing, and intercrystalline bonds in the weld material are first broken, followed by their immediate renewal in the new structure.

The main disadvantages of the method are the large width of the seam, low welding speed, the impossibility of feeding the bonding wire and the need to create inflows on the parts to strengthen the connection. (se) Prototype. The closest in essence to the proposed method is the method of KO2173619 SI, V2ZK 20/12, in which a device - a slider with a slot is installed on the parts assembled at the joint and clamped from the sides, the parts are pressed with this device to the substrate, then a disc is inserted into the slot , which rotates at a high speed and plunge sl 20 into the edges of the parts, the material of which is plasticized, heating up due to the work of frictional forces, and then the disk is progressively moved along with the slider along the joint in the direction of welding. At the same time, the material of the parts removed from the edges is transferred with a disk from the front zone to the rear, where it is pressed with the help of a slider.

The most characteristic processes that occur during welding by a known method are the following: heating, plastification and removal of the main material from the edges of the parts with the breaking of intercrystalline bonds; 29 movement of the seam material from the front zone to the rear zone with grinding, mixing and instant

HF) restoration of intercrystalline bonds; formation in the back zone of an inseparable connection under the conditions of limiting the volume of the plasticized material. o Criticism of the prototype. 1. When welding by a known method, the seam formation process is accompanied by inevitable losses of material removed from the edges of the parts. The main reason is that not all 60 transferred material is removed from the disk by the secondary device. A layer of material of some thickness remains on the disc after the slider, which continues rotation in the front zone, where it meets the resistance of hard, not yet sufficiently heated edges. Here, part of the residual layer is removed from the disk and accumulates in the form of a loose mass. This mass, cooling, hardens and is forced to move in front together with the disk and slider. In addition, the material is naturally dispersed on the sides of the disc. As a result, we get not enough material under the slider to form a tight connection (especially the beginning and end), the seam contains a large number of cavities that look like elongated pores. In the known method, the parts to be joined must be very well fitted, without gaps at the joint, otherwise this also leads to a shortage of weld material. Even a slight difference in the thickness of the welded parts or their deviation from flatness also leads to a deterioration in the tightness of the joint. It is clear that the shortage of material for pressing the seam is especially noticeable when welding thin joints. 2. The mechanical properties of the joint obtained by the known method are lower than those of the base metal (this is especially true of high-strength alloys), since undesirable structural changes occur during the mixing process.

In general, this problem can be solved by the formation of the necessary reinforcement of the weld seam, the introduction of alloying elements into 7/0 and the use of shielding gases. Accumulation of solid loose mass in front of the disc prevents the introduction of planting material by obvious methods.

C. The significant resistance of the hard front zone of the parts determines the large thickness of the disk and the low speed of welding in a known way, and the process of forming the seam is critical, which is explained by the mechanism of transformation of the seam material. Particles of metal are transferred from the front zone to the rear due to their movement, similar to the hydraulic current, which is initiated by the generating surface of the disk. Mixing takes place mainly in the rear zone, where the particles that are closer to the center of the joint are subjected to the braking effect of the particles that are closer to the periphery.

On the one hand, it is difficult to ensure the mode of formation of the connection at small thicknesses due to the fact that the main amount of the seam material flows through the narrow gap between the bottom of the disc and the substrate. The greater the flow width, the worse the homogeneity of mixing. Seams made on thin plates are of low quality mainly due to a non-uniform structure with remnants of the contact trace (uncrushed oxide films and unjoined grains) in the center and a sharp change in grain size in the fusion zone. With a relatively small thickness of parts welded by a known method (for AI-alloys less than Zmm), when little heat needs to be introduced (otherwise the samples lose their hardness in a wide area and the crimping conditions are violated), and the gap below the disc is too thin for the passage of low-plastic material, seam formation does not occur.

On the other hand, it is difficult to ensure the formation of a connection at large thicknesses due to overheating of the material i) above the solidus temperature. Increasing the thickness of the workpieces for welding requires an increase in the amount of material (flow rate) and a simultaneous increase in the amount of heat (recovery) that is spent on propagation. These parameters change proportionally with the change in the linear speed of the disk. But with Ge! with an increase in temperature, the thickness (depth) of the flow decreases due to the increase in plasticity in the material layer. With a relatively large thickness of the samples welded by the known method (for AI-alloys above Ohm), a regime occurs when the heat does not have time to spread from the disk, then the material of the flow is overheated to such an extent that it becomes too thin, and the filling of the seam does not occur ( a significant amount of material passes through the gap between the disk and the slider). Seams made by a known method on thick plates are of low quality (me)

Зз5 is mainly due to a loose structure with the presence of a large number of voids in volume and overheated inclusions with the loss of alloying elements. 4. The creative surface of the slider moving along the joint is flat; When making corner joints in a known way, it is necessary to create appropriate inflows in the parts to be welded, which would create a flattened strip near the seam of a slightly larger width than the thickness of the disk. The same inflows must be created when welding parts of different thicknesses and for the formation of weld reinforcement when welding alloys that strengthen during welding.

Thus, the most significant disadvantages of the known method are: 1. low quality of the connection; 2. impossibility of alloying the seam material;

C. impossibility of obtaining reinforcement of butt joints or radius transitions of corner joints, or

Ge» connections of different thicknesses without previously creating shaped tides on the parts. 4. increased requirements for the adjustment of the gap in the joint, for the flatness of the surface of the parts to be welded, and for se) deviations in their thickness; their 5. low welding speed; 6. excessive width of the weld; o 7. the permissible thickness of parts for welding is limited (above and below).

Ge) The new method and device for friction welding is aimed at solving the problem of improving the quality of the welded joint, ensuring the possibility of alloying the seam or forming thickenings on butt seams, or forming the necessary radius transitions in corner and joints of different thicknesses, increasing the speed

Welding, reducing the width of the weld seam, expanding the range of thicknesses to be welded, reducing the requirements for the quality of the preparation of the edges of the parts to be welded.

F) The essence of the new method and device of rotary friction welding, in which the assembled sheet parts are pressed to the substrate with an auxiliary tool in the form of a slider with a slot, and the main tool in the form of a disk is inserted into the slot, rotated around its axis and immersed in the material of the parts in at the point of contact, they are moved together with the slider in the direction of welding, while the welding is formed due to the plasticization of the seam material from the work of frictional forces, its movement from the front welding zone to the rear, mixing and crimping in the latter, consists in the fact that in the gap between the parts and the disk in the front zone, the setting material is fed in the form of a tape or wire with the adjustment of the force of pressing against the forming surface of the disk, and the volume of the plasticized material formed in the gap, 65 is limited by the receiving chamber, consists in the fact that the edges of the parts are developed in the front zone welding, for which the forming surface of the disc in the center of the thickness has a flange, the height of which corresponds to the thickness of the parts, consists in the fact that the sliding forming surface in the rear zone has a forming groove with a narrowing that corresponds to the shape of the seam reinforcement, and in the front zone - a receiving groove to limit the volume of the plasticized additive material, consists in the fact that the creative surface of the disk has periodically located

Protrusions and depressions, made, for example, as a double bevel gear, is that the main tool consists of three disks, the central one of which acts as a flange, and each component or only the central one is made of separate petals, for example, like a brush-needle cutter. The structural scheme of the new method is shown in Fig. 1, where: 1 - grafting material; 2 - reception chamber; C - parts to be welded; 4 - rotating disc; 5 - plasticized material; 6 - rib; 7 - joint; 8 - seam; 9 - a sliding die;. 10 - slider. 70 The device for friction stir welding according to the new method consists of a rotating disk, a slider that slides behind the disk on the surface of the parts to be welded, and a receiving chamber for feeding the filler material.

The receiving chamber is located in the front area and can be made integral with the slider, as a groove facing the surface of the parts. Here, as a result of heating, the volume of plasticized material accumulates in /5 Narrow gap between the disk and the parts. Additive material in the form of, for example, a tape, is forcibly introduced into the chamber with the force of ER. By adjusting the forces, the material in the gap volume is forced to plasticize and create conditions under which the plasticity of the material in the chamber is higher than that of the residual layer (it was discussed earlier). The force E causes the movement of the material in the chamber in the direction of the forming surface of the disc and is pressed against it.

The walls of the chamber prevent the material from being pushed to the sides and direct it to the creative surface of the disk. The rotating disc initiates the movement "under itself" of the plasticized material in the chamber. At the same time, it becomes possible to slightly increase the welding speed due to the additional heating of the edges of the parts by the material of the camera.

The slider in a new way serves to form reinforcement under the conditions of pressing the seam metal. For this, a groove of variable cross-section is made in the slider - starting from the slot in the shape of a disk, it has the shape of a spinneret, which narrows and ends with the initial cross-section in the shape of the reinforcement of the welded joint (Fig. 2, where: i) 1 - details , which connect; 2 - joint; Z - seam; 4 - slider; 5 - slit of the slider for the rim of the disk; 6 - sliding surface facing the side parts of the disc; 7 - die. For crimping, the parts are fixed on the sides from the run-up with an auxiliary tool and pressed with a slider to the substrate with a certain effort to prevent bending from flatness.

The die profile together with the substrate creates a shape similar to those used in press profile machines, and the physical process that takes place in the die is similar to the pressing process. "Mr

Pressing pressure in the die is created, firstly, due to the injection of the material into the flow by the rotating disk, and secondly, by the forced stretching of the material relative to the die during the movement of the slider along the joint, which, as it cools, hardens. In the presence of pressing using a new method, the density of the seam material is higher. "at

The most rational design of the disc consists of three parts: two side parts, which during welding with their cylindrical surfaces frictionally touch the parts to be welded, in the zone near the seam, and the central part, which protrudes from the side parts as a flange and during welding is immersed in the parts for almost their entire length thickness Such a disk is the initiator of more effective mixing and injection of the material due to the fact that the 70 edge is introduced into the volume of the die. in s The amount of heat generated by friction depends on the size of the contact edge of the rotating disk. In the device using a new method, we have the opportunity to increase the width of the side parts of the disk to increase;" intensity of the process without changing the thickness of the flange. The process in a new way originates from the operation of developing the joint with the front edge of the rib. This is evidenced by the remains of the mechanical cutting of the material at the beginning of the trace from the disk when the welding process is especially suddenly stopped. A thin rib trims the edges

Ge" of parts in a cold state, which ensures the symmetry of further heating and mixing, even in the case of deviations of the joint or the thickness of the gap. Here, a tight fitting of the joint is not necessary, on the contrary, the presence of gaps reduces the resistance of the rib. As a result, according to the new method, the welding speed significantly increases compared to the known one.

The thickness of the rib is small (0.5-2.5 mm), so the width of the seam made by the new method is several times smaller than in the known method. A smaller volume of metal is subject to stirring during long movement,

Ge) as a result of which it is more intense. Thanks to the increased current, the metal particles captured by the disc undergo greater grinding. We obtain the recombination of bonds with greater saturation, grinding and homogeneity than in the known method.

According to the new method, in the presence of an appropriate amount of grafting material, a high-quality adjustment of the surface of the joining parts is not required, and it is possible to form a seam with sufficient reinforcement, which will

F) to correspond to the initial cross-section of the slider groove. In addition, it is possible to form a reinforcement at the root of the seam, for which you need to make a suitable groove in the lining.

The quality of the seam, which is made by the new method, is better due to a more uniform and fine-grained structure. because the filling of the seam is dense, without defects such as cracks and disjoints along the grain boundary. Thanks to the introduction of alloying elements and the formation of reinforcement, the value of the strength of the welded joint according to the new method is increased to the level of the base metal.

For the new method, it is not necessary to create additional inflows when welding corner seams or sheets of different thicknesses. In this case, it is enough to make the side parts of the disk either conical or of different 65 diameter (Fig. 3, where: 1 - diagram of friction welding with stirring using a disk of parts of different thickness; 2 - diagram of friction welding using a T-joint disk). It should be noted that this significantly improves the practical use of the method when welding T-joints, since smooth radius transitions are necessary in them.

The forming surface of the disk, especially the flange, can be made structurally of both a constant section and

It can be equipped with protrusions and depressions located periodically along the rim. In the latter case, the mixing will be more homogeneous. The configuration of the disc rim can be, for example, like a gear with double bevel teeth (in the form of an all-terrain wheel tread). In any case, it should be rational, based on the stability, resource and performance of the disk and the quality of material mixing.

But, all things being equal, a continuous rib is the initiator of the flow of the seam material in a predominantly longitudinal direction, which does not contribute to the homogeneity of the seam structure. In addition, during translational movement, such a rib is opposed by the resistance of the insufficiently heated front zone of the joint metal. These shortcomings can be eliminated if the central part of the disc is made of separate petals arranged along the diameter, which can flex elastically, for example, in the form of a brush-needle cutter (Fig. 4, des 1 - central part of the disc (brush needle-cutter); 2 - the side part of the disk; C - slider; 4 - parts to be welded; 5 - plasticization zone). Such petals together work as a flange (in the part that protrudes), and each one separately is a miniature spatula that removes small portions of metal from the front welding zone and transfers them to the rear, moreover, due to the fact that the petal has the ability to bend from a solid support, removal will take place exclusively from the soft plasticized zone. As a result, the speed of welding and homogeneity of mixing increases.

The side parts of the disk can also be made as a metal brush. Compared to the solid version, this design has two advantages: firstly, there is a longer section of the joint in front of the disc under the frictional contact; secondly - particles of material that the rib tries to push out from the center of the joint to both sides are forced into the die with such a brush.

An example of a specific implementation

Fig. 5 shows a photo of a laboratory device for welding samples from aluminum alloys according to the new technical method. Where: 1 - rotating disc; 2 - sample to be welded; C - sample movement mechanism; 4 - reception chamber; 5 - slider support. and)

Samples of butt and corner joints of aluminum alloy plates were obtained on the laboratory device

ADZ1 thickness 0.5-3mm, Dib thickness 2O0mm, Amgb1 thickness bmm, AmgbNN thickness 1bmm, AbO13 thickness 21Zmm. With high-quality filling of the seam, reinforcement up to 5 mm in height was obtained. Gee! zo Fig. b shows photos of the front (1) and back (2) side of the samples of the welded butt joint made of ADZ1 alloy with a thickness of 1.5 mm, obtained on a laboratory device. at

List of figures. "Mr

Fig. 1 - Scheme of friction welding with stirring using a rotating disc.

Fig. 2 - Sketch of the design of the slider. me)

Fig. 3 - Scheme of friction welding with mixing of branded and different thickness joints.

Fig. 4 - Sketch of the design of the central part of the disk, consisting of separate petals.

Fig. 5 - Laboratory equipment for friction stir welding using a rotating disc.

Fig. 6 - Samples of ADZ1 alloy welded by a new method. " - with ;" (22) se) sh» s 50 3e)

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Claims (6)

The formula of the invention, and - 1. The method of friction welding with a rotating disk of sheet parts assembled in a joint using the main tool in the form of a disk, which is rotated around its axis, perpendicular to the plane of the ends of the edges of the parts, moved forward in the plane of rotation along the joint immersed in the joint with heating of the material of the edges of the parts to the plasticized of the state due to the work of frictional forces and moving it to the area behind /o0 of the disc, and an auxiliary tool in the form of a slider with a slot, which is moved along the surface of the parts compatible with the disc, while the disc is in the slot of the slider, with the seam material being pressed in the area behind the disc, by limiting the volume of this zone, which is distinguished by the fact that the filler material is fed into contact with the forming surface of the disk and the parts in the front part of the welding zone, and the volume into which the filler material is fed is limited by the receiving chamber, and it is fed in a compact form as a tape in We wire or several tapes or wires are forcibly adjusted their efforts. 2. The method according to claim 1, which differs in that the edges of the parts are developed in the welding zone, for which a rib is made on the forming surface of the disc. 3. A device for friction welding with a rotating disc, which consists of a main tool in the form of a rotating disc and an auxiliary tool in the form of a slider, which has a slot in which the disc is placed, which is distinguished by the fact that the slider has a receiving chamber in its front part for accumulating plasticized of the volume of the grafting material and forcing it to be directed to the forming surface of the disk, and the forming surface is sliding in the back part with a narrowing groove and has a cross-section at the exit corresponding to the shape of the seam reinforcement. 4. The device according to claim 3, which is characterized by the fact that the forming surface of the disc is made with a projection as a rib in the central part, the height of which corresponds to the thickness of the parts to be welded. 5. The device according to claim 4, which is characterized by the fact that the generating surface of the disk has periodically arranged protrusions and (o) depressions, designed, for example, as a double bevel gear. 6. The device according to claim 4, which differs in that the main tool consists of three coaxial discs, and the central one of the discs is made of a larger diameter and protrudes from the other two lateral ones as a rib, and each of the discs or only the central one is made like a brush-needle cutter . IF) Official Bulletin "Industrial Property". Book 1 "Inventions, useful models, topographies of integrated microcircuits", 2004, M 9, 15.09.2004. State Department of Intellectual Property of the Ministry of Education and Science of Ukraine. (is) (Se) - . and? (o) se) sh» 1 iChe) ime) 60 b5