Rotary friction welding machine and method of operating a rotary friction welding machine

Abstract

Rotary friction welding machine comprising a rotation device (100) comprising a motor (2) and a spindle (6) driven by the motor (2) and adapted to rotate a first workpiece (A), and a forging device (200) adapted to move a second workpiece (B) and to press it against the first workpiece (A) until the two workpieces (A, B) are welded. The shaft (7) of the spindle (6) is coupled by at least one bearing (10) to an intermediate support (25) which is coupled by at least one other bearing (11) to a main support (20) of the rotation device (100) so that, in a first mode of operation of the machine (1), the shaft (7) rotates with respect to the intermediate support (25) and the main support (20) and, in a second mode of operation, the intermediate support (25) rotates together with the shaft (7). The invention also relates to the method of operating the machine.

Description

[0001] DESCRIPTION

[0002] “Rotary friction welding machine, and operating procedure of a rotary friction welding machine”

[0003] TECHNICAL SECTOR

[0004] The present invention relates to a rotary friction welding machine and a method of operating the rotary friction welding machine.

[0005] PRIOR STATE OF THE ART

[0006] Friction welding of two workpieces is a process known in the art by which two workpieces are joined together using pressure and heat. One of the workpieces rotates around its longitudinal axis, driven by a motor, while the other workpiece moves toward the workpiece rotated by the motor, exerting pressure such that the contact area softens. The motor is then decelerated, and greater pressure is applied to the workpieces, melting the materials in the contact area. Finally, the contact area cools, solidifying the weld.

[0007] US 2018 / 0036834 A1 discloses a friction welding machine as defined in the preamble of claim 1.

[0008] EXPOSURE OF THE INVENTION

[0009] The object of the invention is to provide a rotary friction welding machine adapted to weld two workpieces, and a method for welding two workpieces by rotary friction as defined in the claims.

[0010] A first aspect of the invention relates to a rotary friction welding machine comprising a rotation device configured to rotate a first workpiece, the rotation device comprising a motor and a spindle with an axis driven by the motor and adapted to rotate the first workpiece, and a forging device configured to move a second workpiece until it comes into contact with the first workpiece and to press the second workpiece against the first workpiece until both workpieces are partially melted and welded.

[0011] The spindle shaft is coupled to an intermediate support via at least one bearing. The intermediate support is, in turn, coupled to a main support of the rotating device via at least one bearing, such that, in a first operating mode of the machine, the spindle shaft rotates relative to the intermediate support and the main support, and in a second operating mode of the machine, the intermediate support rotates together with the spindle shaft.

[0012] Thus, when the rotary friction welding machine is in the first operating mode, only the bearing coupled to the shaft comes into operation while the bearing coupled to the main support is blocked, while when the rotary friction welding machine is in the second operating mode, only the bearing coupled to the main support comes into operation, with the intermediate support and the shaft rotating in an integral manner, without the possibility of relative rotation between them, and therefore, the operation of the bearing coupled to the shaft is blocked.

[0013] Another aspect of the invention relates to a method for operating a rotary friction welding machine in which, depending on the type of workpiece to be welded, either the first or second operating mode of the machine is selected. That is, depending on the geometry, dimensions, and material of the workpieces, for rotary friction welding to be carried out, the machine must operate within specific rotational speeds and forging pressures. Depending on the required rotational speeds and pressures, the machine will determine which bearings to operate with.

[0014] This machine has the great advantage that it allows welding of small and large sections of the same type of part on the same machine, that is, it allows working with parts with a much wider range of dimensions than state-of-the-art machines, which are limited to working with parts with a narrow range of dimensions. DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 shows a sectional perspective view of an embodiment of a rotary friction welding machine according to the invention.

[0016] Figure 2 shows a longitudinal section of the rotary friction welding machine according to the invention.

[0017] Figure 3 shows a detail C of a spindle of the welding machine shown in Figure 2 in a first operating mode.

[0018] Figure 4 shows a front view of the welding machine spindle shown in Figure 1 in the first operating mode.

[0019] Figure 5 shows another partial sectional view of the welding machine spindle shown in Figure 1 in the first operating mode, in which some elements have been hidden to facilitate understanding.

[0020] Figure 6 shows a perspective view of a locking element of the welding machine shown in Figure 1.

[0021] Figure 7 shows a sectional view of the locking element of the welding machine shown in Figure 1.

[0022] Figure 8 shows a front view of the welding machine spindle shown in Figure 1 in a second operating mode.

[0023] Figure 9 shows a partial sectional view of the spindle of the welding machine shown in Figure 1 in a second operating mode.

[0024] Figure 10 shows another partial sectional view of the welding machine spindle shown in Figure 1 in the second operating mode.

[0025] Figures 11a and 11b schematically show a drive means for the welding machine shown in Figure 1.

[0026] DETAILED EXPLANATION OF THE INVENTION

[0027] An aspect of the invention relates to a rotary friction welding machine 1 as shown in Figure 1, comprising a rotation device 100 configured to rotate a first workpiece A, the rotation device 100 comprising a motor 2, a spindle 6 coupled to the motor 2, and a chuck 9 coupled to a shaft 7 of the spindle 6 and adapted to grip the first workpiece A, the motor 2 being adapted to rotate the shaft 7 of the spindle 6, in turn rotating the chuck 9.

[0028] The spindle 6 further comprises at least one brake 8 at least partially surrounding the shaft 7. Each brake 8 is configured to decelerate the shaft 7 to a stop during the braking stage of the friction stir welding process. In a preferred embodiment, the brake 8 is a friction brake.

[0029] In an embodiment as shown in Figures 1 and 2, the spindle 6 is coupled to the motor 2 through transmission means 3. The transmission means 3 comprise pulleys 5 coupled respectively to the shaft 7 of the spindle 6 and to a shaft of the motor 2, the pulleys being coupled to each other by means of a belt 4.

[0030] On the other hand, the rotary friction welding machine 1 also comprises a forging device 200 configured to move a second workpiece B into contact with the first workpiece A, and to press the second workpiece B against the first workpiece A until both workpieces A and B are partially melted and welded.

[0031] The rotary friction welding machine 1 also comprises control means 300, schematically represented in Figure 1, configured to control the rotation speed of the spindle 6 and the pressure exerted on the second workpiece B.

[0032] The spindle 6 is supported on a main support 20 of the rotation device 100. The shaft 7 of the spindle 6 is coupled by means of at least one bearing 10 (hereinafter referred to as the first bearing) to an intermediate support 25 which, in turn, is coupled by means of at least one bearing 11 (hereinafter referred to as the second bearing) to the main support 20, so that, in a first operating mode of the machine, the shaft 7 of the spindle 6 rotates relative to the intermediate support 25 and the main support 20, and in a second operating mode of the machine, the intermediate support 25 rotates together with the shaft 7 of the spindle 6.That is to say, when the rotary friction welding machine 1 is in the first operating mode, only the first bearing 10 comes into operation while the second bearing 11 is blocked, while when the rotary friction welding machine 1 is in the second operating mode, only the second bearing 11 comes into operation, with the intermediate support 25 and the shaft 7 rotating in an integral manner, without the possibility of relative rotations, and therefore, the first bearing 10 is blocked.

[0033] In an embodiment as shown in the figures, the shaft 7 of the screw 6 is coupled by a plurality of first bearings 10 to the intermediate support 25, the intermediate support 25 being coupled to the main support 20 through a plurality of second bearings 11, the plurality of second bearings 11 surrounding the plurality of first bearings 10. In a preferred embodiment, the number of second bearings 11 used is less than the number of first bearings 10.

[0034] In an embodiment as shown in the figures, each first bearing 10 or bearing coupled to shaft 7 is a high-speed bearing, and each second bearing 11 or bearing coupled to main support 20 is a low-speed bearing. Preferably, each first bearing 10 is also a high-load capacity bearing, and each second bearing 11 is a low-load capacity bearing.

[0035] “High-speed bearings” refer to bearings that operate at maximum speeds of 3000 rpm.

[0036] “Low speed bearings” refer to bearings that operate at speeds below 1500 rpm.

[0037] By “high load capacity” we mean bearings that can withstand a maximum load of 60 tons of pressure.

[0038] By “low load capacity bearings” we mean bearings that can withstand a maximum load of 20 tons of pressure.

[0039] The friction stir welding machine 1 comprises locking means 30 configured to lock one of the machine's operating modes, allowing the machine 1 to operate in the other operating mode. Thus, the locking means 30 can lock either the first operating mode or the second operating mode of the machine 1, allowing the machine 1 to operate in a non-locked operating mode.

[0040] In an embodiment shown in the figures, the locking means 30 comprise at least one connecting element 31 which, in the first operating mode of the machine 1 shown in Figures 1 to 5, is arranged fixed to the main support 20 (the position of the connecting element 31 being called the first position), the connecting element 31 being held against the intermediate support 25 through a locking element 32. The connecting element 31 is arranged fixed to the main support 20 without the possibility of rotation.In the second operating mode of the machine, shown in figures 8 to 10, the connecting element 31 is fixed to the intermediate support 25 (the position of the connecting element 31 being called the second position), the connecting element 31 being held against the intermediate support 25 and against the axis 7 of the spindle 6 through the locking element 32, so that the axis 7 and the intermediate support 25 are coupled in an integral manner, without the possibility of relative rotation between them.

[0041] In an embodiment as shown in the figures, in the first position of the connecting element 31 shown in figures 3 to 5, said connecting element 31 is fixed (without the possibility of rotation) to the main support 20 through a coupling 21. Preferably, in the first position, the connecting element 31 is screwed 31b, 21b to the coupling 21.

[0042] The connecting element 31 and the coupling 21 comprise a respective recess 31a, 21a which, when the connecting element 31 is positioned in the first position, define a housing 26 in which the locking element 32 is inserted, said locking element 32 projecting with respect to said housing 26 to contact and retain the intermediate support 25 against the coupling 21 without the possibility of rotation.

[0043] In an embodiment as shown in the figures, in the second position of the connecting element 31 shown in Figures 8 to 10, said connecting element 31 is fixed to the intermediate support 25 without the possibility of relative rotation with respect to said intermediate support 25. In particular, the connecting element 31 is screwed 31b, 25b to the intermediate support 25.

[0044] The intermediate support 25 comprises a recess 25a such that, when the connection element 31 is positioned in the second position, the recess 25a of the intermediate support 25 together with the recess 31a of the connection element 31 define a housing 27 in which the locking element 32 is housed inserted, said locking element 32 projecting with respect to said housing 27 such that the locking element 32 retains without the possibility of relative rotation the intermediate support 25 coupled to the shaft 7 of the screw 6. In particular, the intermediate support 25 is fixed to the shaft 7 through a coupling 23, for which the coupling 23 comprises a recess 23a in which the locking element 32 is partially housed retaining the coupling 23 with respect to the intermediate support 25. The coupling 23 is a substantially annular coupling.

[0045] In an embodiment as shown in the figures, the locking element 32 is a key.

[0046] In an embodiment as shown in the figures, the locking means 30 comprise two connecting elements 31, each of them in the form of a sector, which are arranged diametrically opposite each other.

[0047] In an embodiment as shown in the figures, the friction welding machine 1 comprises positioning means 35 configured to detect whether the machine 1 is in the first operating mode or in the second operating mode. The positioning means 35 comprise a sensor arranged so as to detect the presence of the connecting element 31 when it is in the first position. When it does not detect the presence of the connecting element 31, it is because said connecting element 31 is arranged in the second position.

[0048] On the other hand, the forging device 200, shown in Figures 1 and 2, comprises drive means 13 configured to move, in a longitudinal direction X parallel to the spindle 6, the second workpiece B towards the first workpiece A, and to exert pressure on the second workpiece B. The forging device 200 comprises a fixed claw 15 and a movable claw 14 configured to grip the second workpiece B, the movable claw 14 being fixed to a movable support 16 configured to support the second workpiece B and move it under the actuation of the drive means 13 in the longitudinal direction X. The drive means 13 comprise a hydraulic cylinder 19 configured to act on the second workpiece B, and a first pressure switch pack 17 (shown schematically in Figure 11a).By “pressure switch pack” is meant at least one pair of pressure switches adapted to operate in the same pressure / force range as the hydraulic cylinder in the friction and forging stages. The hydraulic cylinder 19, shown schematically in Figures 11a and 11b, comprises two chambers 19a and 19b separated by a piston 28 coupled to a rod 29 adapted to exert pressure on the second workpiece B, a pressure switch of the pressure switch pack 17 being arranged in each chamber 19a and 19b such that, when a predefined pressure is reached in the respective chamber 19a and 19b, the corresponding pressure switch 17 opens or closes an electrical contact of the electrical circuit supplying the hydraulic cylinder 19.

[0049] In a preferred embodiment, the rotary friction welding machine 1 comprises a second pressure switch pack 18 (schematically represented in Figure 11 b), each arranged in one of the chambers 19a and 19b of the hydraulic cylinder 19. Each pressure switch pack is adapted to operate within specific pressure / force ranges. In this way, the machine 1 can operate with a wide range of forging forces / pressures, minimizing full-scale errors of the pressure switches, i.e., measurement errors that are accentuated when the pressure switch operates with pressures close to the maximum and minimum pressures in the pressure range. Thus, the first pressure switch pack 17 is adapted to operate with low or medium pressures, with low or medium pressures being understood to mean pressures below 160 bar.The second pressure switch package 18 is adapted to operate with medium or high pressures, with medium or high pressures being understood as those pressures up to 315 bar.

[0050] Furthermore, workpieces A and B can be of any type, size, and material that can withstand friction stir welding. Preferably, workpieces A and B are rotating parts, and more preferably, cylindrical parts. Preferably, workpieces A and B are metallic parts, and most preferably, steel. Preferably, both workpieces A and B are made of the same material, although they could also be made of different materials.

[0051] Friction stir welding machine 1 can work with workpieces A and B of a wide range of dimensions, materials, and geometries. Friction stir welding machine 1 can operate at low rotational speeds and high forging forces / pressures, or at high rotational speeds and low forging forces / pressures.

[0052] “High pressure / forging forces” means forces greater than 20 tonnes and up to a maximum of 60 tonnes,

[0053] “Low forging pressures / forces” means forces below 20 Tn.

[0054] Another aspect of the invention is a method of operating the rotary friction welding machine 1 described so far. The method of operating a friction welding machine according to the invention comprises a first step in which, depending on the type of workpieces A and B to be welded, the first operating mode of the machine 1 or the second operating mode of the machine 1 is selected. In particular, the control means 300 check, depending on the workpieces A and B to be welded, whether the locking means 30 are correctly positioned so as to operate the first or first bearings 10 or the second or second bearings 11. To do this, they check the signal received from the positioning means 35. If necessary, the operator will correctly position the locking means 30 to operate the machine 1 in the first operating mode or in the second operating mode.

[0055] The operating procedure of the rotary friction welding machine 1 comprises the following steps:

[0056] • a contact stage in which the second workpiece B is moved by the drive means 13 until it comes into contact with the first workpiece A,

[0057] • a friction stage where the actuating means 13 increase the pressure exerted on the second workpiece B until reaching a friction pressure / force that is maintained for a time such that a softening of the contact area of ​​both workpieces A and B occurs due to the heat generated,

[0058] • a braking stage where the rotation of axis 7 of spindle 6 is braked, and

[0059] • a forging stage in which a forging pressure / force is applied through the drive means 13 to the second workpiece B for a time, melting the materials in the contact area of ​​both pieces A and B, the forging pressure / force being greater than the friction pressure respectively.

[0060] The aspects and features described for machine 1 and not described for the procedure are also valid and applicable to said method. Similarly, the aspects and features described for the procedure and not described for the machine are also valid and applicable to said machine.

Claims

CLAIMS 1. Rotary friction welding machine adapted to weld two workpieces (A,B) comprising: - a rotation device (100) configured to rotate a first workpiece (A), the rotation device (100) comprising a motor (2) and a spindle (6) with an axis (7) driven by the motor (2) and adapted to rotate the first workpiece (A), and - a forging device (200) configured to move a second workpiece (B) into contact with the first workpiece (A) and to press the second workpiece (B) against the first workpiece (A) until both workpieces (A, B) are partially melted and welded, and wherein the shaft (7) of the spindle (6) is coupled by means of at least one bearing (10) to a support, characterized in that the support is an intermediate support (25) coupled by means of at least one bearing (11) to a main support (20) of the rotation device (100), such that, in a first operating mode of the machine (1), the shaft (7) of the spindle (6) rotates with respect to the intermediate support (25) and the main support (20) and, in a second operating mode of the machine (2), the intermediate support (25) rotates together with the shaft (7) of the spindle (6).

2. Rotary friction welding machine according to the preceding claim, wherein the shaft (7) of the spindle (6) is coupled by a plurality of bearings (10) to the intermediate support (25), the intermediate support (25) being coupled to the main support (20) through a plurality of bearings (11), the plurality of bearings (11) that couple the intermediate support (25) to the main support (20) surrounding the plurality of bearings (10) that couple the shaft (7) to the intermediate support (25).

3. Rotary friction welding machine according to the preceding claim, wherein each bearing (10) coupled to the shaft (7) is a high rotation speed bearing, each bearing (11) coupled to the main support (20) being a low rotation speed bearing.

4. Rotating friction welding machine according to any of the preceding claims, comprising locking means (30) configured to lock the first operating mode or the second operating mode of the machine. (1), allowing the machine (1) to operate in the second operating mode or the first operating mode respectively.

5. Rotary friction welding machine according to the preceding claim, wherein the locking means (30) comprise at least one connecting element (31) which, in the first operating mode of the machine, is arranged in a first position fixed to the main support (20), a locking element (32) retaining the connecting element (31) against the intermediate support (25) so that the main support (20) and the intermediate support (25) are coupled, and, in the second operating mode of the machine, the connecting element (31) is arranged in a second position fixed to the intermediate support (25), the locking element (32) retaining the connecting element (31) against the intermediate support (25) and the shaft (7) of the spindle (6), so that the shaft (7) and the intermediate support (25) are coupled.

6. Rotary friction welding machine according to the preceding claim, wherein the connection element (31) and the intermediate support (25) comprise a respective recess (31a, 25a) defining a housing (27) in which the locking element (32) is housed in the second operating mode of the machine, the locking element (32) protruding with respect to said housing (27) so that the locking element (32) retains the intermediate support (25) coupled to the shaft (7) of the spindle (6) without the possibility of relative rotation.

7. Rotary friction welding machine according to the preceding claim, wherein the spindle (6) is coupled to the main support (20) through a coupling (21) fixed to said main support (20), the coupling (21) comprising a recess (21a) which together with the recess (31a) of the connection element (31) define a housing (26) in which the locking element (32) is housed in the first operating mode of the machine, said locking element (32) protruding with respect to the housing (26) to retain the intermediate support (25) against the coupling (21).

8. Rotary friction welding machine according to any of claims 5 to 8. 7, where the locking element (32) is a key.

9. Rotary friction welding machine according to any of claims 5 to 10. 8, wherein the locking means (30) comprise two connecting elements (31), each of them in the form of a sector, arranged diametrically opposite each other.

10. Rotary friction welding machine according to any of claims 5 to 9, comprising positioning means (35) configured to detect whether the machine is operating in the first or second operating mode.

11. Rotary friction welding machine according to the preceding claim, wherein the positioning means (35) comprise at least one sensor positioned so as to detect the positioning of the connection element (31) in the first position.

12. Rotating friction welding machine according to any of the preceding claims, wherein the drive means (13) comprise a hydraulic cylinder (19) with two chambers (19a, 19b) separated by a piston (20), and a first pressure switch pack (17) comprising at least a pair of pressure switches adapted to operate in the same pressure / force range of the hydraulic cylinder (20), each pressure switch (17) of the pressure switch pack being housed in one of the chambers (19a, 19b).

13. Rotary friction welding machine according to the preceding claim, wherein the drive means (13) comprise a second pressure switch pack (18) comprising at least one pair of pressure switches housed respectively in each chamber (19a, 19b), the pressure / force range of the second pressure switch pack (18) being different from the pressure / force range of the first pressure switch pack (17).

14. Operating method of a rotary friction welding machine according to any of the preceding claims, wherein depending on the type of workpieces (A, B) to be welded, the first operating mode of the machine (1) or the second operating mode of the machine (1) is selected.

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