DE7114650U - Functional welding machine - Google Patents

Description

■■■■■ · ■■ '· "? - ι I Q

Patent attorney

Kari A. Brose

Dpg

D-8023 Monks - Pulla *
* 2.T.Bä _t 7? 33570.7i3i7S2

vln / au Munich-Pullach, April 15, 1971

AI WELDERS LIMITED, 98 Academy Street, Inverness , Scotland, UK

Friktiohs-Schi ^ ßgerät »

The invention relates to a friction welding device.

The friction welding is to rub the surfaces of two to each other to be welded workpieces under pressure to each other, whereby the material of the workpieces at this fleeing up to a plastic state heated ^gr is then the applied pressure is maintained, and the workpieces are pressed against one another after the relative movement has ceased to produce the frictional effect, thereby causing merging and establishing the bond between these workpieces.

The axial force which is applied to the surfaces Toggle ί each push, may be constant during the whole welding process or may be varied so that either the pressure during the Erwärmabschnittes the process BMBT constant and then to provide the definitive \ * ύ is changed depending on the binding, or the pressure is kept at a value during an initial heating process, |

during a middle stage then echanged and to the I.

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Achieving the final bond is changed. ff

It is an object of the present invention to provide a means for making the final bond with an increased Shape pressure.

In the previously known friction welding processes, the axial force usually provided by the direct application of a fluid pressure or an air pressure and this Force was therefore limited by the properties of the fluid or air pressure system that was used "If a higher axial pressure or force to generate the preceding described effect is required and if a Fluid pressure system is used then the size of the pressure generating cylinder or cylinders and the Size of the pump or! »Umpen be sufficient for the for the Forging operation to provide required axial pressure, and if a pneumatic system is used, being compressed Air from a normal supply system with a

? pressure of 5,600 g / cm (80 p.s.i.; / then the axial Force-generating cylinder be very large compared to other components of the welding machine.

The present invention provides a friction welding device for performing a friction welding with a heating phase and a forging phase, and this device consists of a first workpiece-holding device, a second workpiece-holding device and a device for moving one of the tool-holding devices forward to the other during the heating phase of the welding process, In order to bring the workpieces held in the workpiece-holding devices into contact with one another, a device is also provided: for turning one of the workpiece-holding devices during the heating phase, as well as a device,

which comes into action during the forging process to block the feed mechanism, another one device for storing kinetic energy which is generated during said rotation, and means which during of the forging organ ^ s comes into action to the stored to convert kinetic energy into an axially acting "force", whereby one of the workpiece-holding devices

. is pressed against each other, so that a larger axial force is generated between the workpieces than the force exerted by the feed device when moving forward the one workpiece-holding device is provided during the heating phase.

The device for storing the kinetic energy can consist of a di'ehbaren arrangement, and the means for converting the stored kinetic energy into the axial thrust from two interlocking screw thread components or a cam mechanism ".

The feed device for moving the one workpiece-holding Device to the other during the Erwännphase can from a mechanical lever system or from at least one by means of a fluid pressure actuated piston-and-cylinder device exist,

Further advantages and details of the invention emerge from the description of an exemplary embodiment which now follows referring to the drawing. In this show:

s Figure 1 is a side view in section of an Attsführung-

shape of the friction welding device according to the

f lying invention;

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- 4 - figure 2 is a partial view of a somewhat modified
th embodiment of Figure 1; figure 3 is a side view partly in section
another embodiment of the inven-
appropriate friction welding device; figure 4 a partial representation in elneza larger
Scale than that of Figure 3 * and that of
some components), which are shown in FIG
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illustrative are} and "; ■ figure 5 is a side view in section of a still
further embodiment of the invention;
according to the friction welding machine. Frlktions-welding devices are known in which the workpieces
for performing a weld with their axes vertical
are held in alignment, and there are other friction

Welding devices are known in which the workpieces for performing the welding are aligned with their axes horizontally. In each of these cases, a workpiece is rotated while the other stationary is held, to generate a friction, ao that the contacting ends of the workpieces are heated, and in some devices is rotary value unit, or in snderen Gerüt & does not n is rotating workpiece, held in an axially movable sapport in order to be able to move this workpiece relative to the other and to be able to press it against this.

The described embodiments according to the present invention do not include several of the arrangements mentioned above and it should be emphasized that the invention also applies to other arrangements of welding equipment which are not specific

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have been described.

According to Figure 1, a friction welding device is shown at which the workpieces are held with their axes aligned horizontally for welding, with a ήβΡιί— piece is both rotated and moved towards the other workpiece during the heating phase of the welding process, which is held against axial movement and against rotation.

The device consists of a rigid frame 10 to which a headstock 11 that can be moved in a straight line is attached is, on which a shaft 12 is rotatably arranged and moves in a straight line with the headstock, the arrangement is made so that this shaft by means of an electric motor 13 via a fluid pressure transmission system, consisting of a pump 14 and a motor 15, driven is, measures are taken to disengage the transmission so that the shaft 12 can rotate freely. Of the Motor 15 driven by fluid pressure is I with the help of a belt drive 16 and a flywheel 17, which> | is mounted on the shaft 12, and the mass of this flywheel 17 can be added by adding or by Ent- I be varied remotely by disks 18, these disks I can be stored on a fixed shaft 19 if j they are not needed. This flywheel is used to j

Spoke "of the kinetic energy during the rotation of the \ shaft 12. The spindle head 11 can be using the WIR j effect of Flüssigkeitsdackes in one or more of the pressure piston-cylinder devices 21, which are supplied with liquid under pressure and that from a suitable source of to move on a straight path. Said source includes; a pump, which is indicated schematically at 22 and this pump is connected via a valve 23 which the

71 146 50 7/22 - 71 y

Ends of the cylinder or cylinders of the plunger-cylinder device or devices 21 can be selectively connected to the pump 22 or to a liquid container 24.

iras Tentii ip Can irgsnaexn nersvniinntnes f «iwi otrxri,« rcxches is able to confine the liquid in the cylinder or cylinders of the plunger-cylinder devices 21, a release valve is provided to prevent the headstock from moving in a straight line, to remove liquid from the named device or device *! to be released when excessive axial thrust occurs by means of the headstock 11. It can but also a mechanical locking device (not shown) can be provided, which in a suitable manner the headstock against his straight 3 * movement.

A tailstock 25 is fixedly arranged on the rigid frame 10.

A first workpiece-holding device 26 is fixedly arranged on the shaft 12, including a workpiece WR. for axial movement with the headstock 11 and can rotate with the shaft 12. A second workpiece-holding device 27 holds a second workpiece WPp in a suitable manner, so that this workpiece is held against both an axial movement and a rotational movement. This device is attached to the shaft 28, which is provided with a thread at 29, and the said thread can be screwed into a corresponding thread in a hub 30 of the tailstock 25. The shaft 28 is provided with a keyway to form a key receiving toothed hub 31, which carries a brake disc 52, which cooperates ait a brake Tastlenreanordnung 33 to the shaft hold 28 ge gene rotation in the tailstock 25th

7114S50217.7!

When performing a Friktionsschweißung with the device shown in Figure 1, the workpieces WP ₁ and FTE ₂ are respectively fastened in the work holding devices 26 and 27, the brake 32, 33 is tightened to the work holding

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The holding device 26 is rotated with the aid of the electric motor 13, being moved to the workpiece holding device 27 with the aid of the action of the fluid pressure in the pressure piston-cylinder device or devices 21 to the workpiece holding device 27. The forward movement of the workpiece holding device 26 brings the workpieces WP ₁ and WP2 into contact with one another and due to the rotation of the workpiece WP-. the workpieces are rubbed against one another, this friction generating heat so that the metal on the contact surface of the workpieces becomes plastic. During this frictional contact, a certain end load is exerted on the workpieces by means of the plunger-cylinder device or devices 21, this being the maximum load which must be applied by these devices 21.

At a certain point in welding cycle ¹ , which can be determined by a clock or clock, this clock being put into operation when the workpieces come into contact, or this point by the approach of the headstock up to a certain distance from the tailstock can be bestinffirfc, the brake 32, 33 is released, whereby the workpiece WPp together with the workpiece-holding device 27 and the shaft 28 is given the opportunity to rotate due to the frictional effect between the workpieces When the brake 32, 33 is released, the drive is separated from the shaft 12 and the headstock 11 is controlled in its straight-line movement. However, the shaft 12 continues to rotate and

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f due to the kinetic stored in the flywheel 17 Energy and kinetic energy stored in the rest of the rotating parts, but these parts become

f. gradually slower and possibly stop when the

kinetic energy is consumed.

The rotation given to the workpiece WP ₂ after the brake 32, 33 has been released is transmitted to the shaft 28, whereby the threaded portion thereof is rotated into the threaded portion of the hub 30 and the workpiece WP ₂ is pressed towards the workpiece WPj with a very high force, so that these workpieces are forged together.

In this way the high axial force is maintained during the forging phase of the welding process generated mechanically and

ι using the saved during the heating phase

kinetic energy and therefore the liquid

I _I pressure-actuated pressure piston-cylinder device or --- Vorrichr \ i obligations no greater thrust or power generating, as the

Requirements during the heating phase.

With the slightly modified one. Embodiment according to FIG. 2, which can be applied to the welding device according to FIG. 1, shows part of the device, the headstock 11 and part of the rice stick 25. The workpiece-holding devices are designated with 26 and 27 and the workpieces with WP ₁ and WP ₂ . The part 28 which carries the workpiece holding device 27 is in threaded engagement with the retainer at 29. The disc brake 32, 33 is omitted and a band brake 3 which acts on a cylindrical circumferential surface of the workpiece holding device 27 is provided around this To hold the workpiece against a rotation.

The mode of operation of this modified embodiment corresponds completely to the embodiment already described in accordance with FIG. 1.

In the following, the embodiments according to FIG for 3 and 4 are included * The friction welding device after. Figure 5 is of the type, bsi άζτ di © workpieces for! fine welding process with their axes aligned vertically * whereby a workpiece is rotated during the heating phase of the welding process, but is held against an axial movement, and the other Y / piece, which is held against rotation during the mentioned phase * * including the rotated workpiece is moved there *

3, the welding device consists of a rigid upright frame 36, on one side of which a fixed headstock 27 is attached to the upper end of the frame, which rotatably accommodates a shaft 38 which is held against axial movement and is driven via a belt drive 39 with the aid of an electric motor 41 which is fastened to the frame 36. The housing 42 extends laterally from the frame 36 and zvar below the headstock. Guiding ^p rods 43 are attached to one end of the headstock 37 and GNDE to housing 42 at the other, so that a support is provided on which a tailstock 44 can slide off to the headstock toward and wherein said tailstock against rotation by the guide rods43 is held in place. \

S Movement of tailstock 44 to the headstock 37 toward and away from I is effected by a crank lever 45 of the housing 42 is arranged rotatably on a shaft 46 and by a Verbindungsstariger 47 to the tailstock 44 | is coupled is * a tfijskelbewegung of the Kttrbelh & bels uira ver || by means of a fluid pressure operated rotating device 48

711465022.7.71 I.

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causes "or by a reversible electric motor or by a manually operated device, such as an external lever, which acts directly or via a transmission device, so that a mechanical thrust on the Shaft 46 is provided.

A disk brake 49 is provided "to hold the headstock or" headstock shaft 38 against rotation and, as can be clearly seen from FIG. 4, "a workpiece-holding device 51 is rotatably arranged on the shaft 38, and engaging cam surfaces 52" 53 are provided on the shaft 38 " together with radial stop surfaces 54 and 55 which engage "when the shaft 38 is rotated by means of the electric motor 41 in accordance with the direction of rotation during a welding process in order to positively transfer this rotation to the workpiece-holding device 51" when the stop surfaces 54 and 55 engage, then the relationship of the cam surfaces 52 and 53 is such that the workpiece holding device 51 is in its axial position in close proximity to the headstock 38, the rotation of the device 51 relative to the shaft 38 in the aforesaid direction causing the workpiece holding device The device moves axially from the locker elstock moved away due to the interaction of the cam surfaces.

A second workpiece holding device 56 is fixedly attached to the tailstock 44 so that it is held against rotation is and moves with the tailstock in the axial direction.

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ale workpieces WP ₁ and WP ₂ are gets into the werkstückhal-

trending devices 51 and 56 mounted and under approval the brake is applied to the shaft 38 with the help of the electric motor

41 pressed a rotation. The shaft 46 is rotated in order to move the tailstock 44 to the headstock 37, for example from the position shown in FIG. 3 in which the crank lever 4? then "is called crank lever 45 ₁ when the contact between η is imminent the workpieces straight * not yet occurred" from the shaft 46 projects away from the tailstock and the ^ according takes the position of Figure 4 a 'i where ei · to mim tailstock extends towards and runs in a line with the connecting rod 47. A continued win |

angular movement of the crank lever 45 presses the workpieces against each other, so that there is friction between them and the resulting heat affects the metal on the workpiece contact surface allowed to become plastic and pressed until the crank lever 45 and the connecting rod 47 »the one shown in FIG 3 have reached the position illustrated,.! N which the workpiece holding device 56 rigidly from the lever and the connecting rod set against retraction will"

At the end of the heating phase of the welding process, the drive of the shaft 38 by the electric motor 41 is interrupted and the brake 49 is actuated in order to stop the shaft 38. The workpiece holding device 51, however, tends to continue its rotation due to the kinetic energy stored in it and the cam surface 53 therefore moves along on the cam surface 52, whereby a very large axial force is provided between the workpieces so that they are forged together.

When a welded component has been removed and a new one The welding process is started, the workpiece-holding reverses

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Vorrichtvmg 51 automatically relative to its initial angular position back to the headstock 37, in which the stop surfaces 53 and 54 are in contact, which is due to the Rotation of the attack of the workpieces results.

The combination of the cam surfaces, referring to

4 can be replaced by threads or another suitable cam profile or arrangement «

It should be emphasized that the arrangement described with reference to Figures 3 and 4 is an entirely mechanical force system for applying an axial force or an axial thrust on the workpieces during the Welding process creates.

The friction welding device illustrated in FIG. 5 is required only a conventional three-way power supply for his operation. The device consists of a solid base 58 from which two vertically extend upwards Guide rods extend, one indicated at 59, with a headstock 61 fixed to the upper ends of the guide rods is appropriate. A housing 62, which is arranged in the headstock 61, supports a spindle 63 rotatably about a vertical axis, which is rotated by means of an electric motor 64 via a belt drive 65, the spindle 63 at its lower end as a workpiece holder 66 carries to a first workpiece WP. to record. A spring assembly (not shown) contained in its housing 67 which is carried by the spindle 63, operates a workpiece chuck in the holder 66 and the Spring device can be operated so that the clamping device is released by means of a lever 68, wherein the lever at 69 on the headstock 61 is pivotable and

is moved to exert a pressure on the spring means, so that thereby the workpiece clamping device by means of a manually operated lever 72 operated articulated linkage 71 is released. According to FIG. 5, the articulated linkage 71 is in the release position of the clamping device with the toggle rods being moved from a collapsed position in which the articulation point is located on the right hand side of a line connecting its end connection points these articulated rods are easily moved beyond a straight position to a position in which the links or rods are at the Pivot point touch a stop 73 so that the joint is blocked and the workpiece clamping device in the releasing position is held. |

A tailstock 7 ^ is arranged displaceably on guide rods 59 and equipped with a diaper hole 75 which is aligned with the headstock 63 which has a threaded shaft 76 having a second workpiece-holding device 77 in order to receive a second workpiece WPp. It is one electromagnetic brake 78 is provided to hold the workpiece holding device 77 against rotation.

A crank lever 79ι on a pivotable shaft 80 which is supported in bearings of the base 58 is mounted, is venaitxels a connecting rod 81 coupled to the tailstock 74 and can be moved angularly to the tailstock by means of a manually operated lever 82, the is attached to the pivotable shaft 80 to raise and lower. The crank lever 79 and the connecting rod 81 represent an over- curled linkage which can be moved from the position shown in FIG. 5 into a position in which the crank lever 79 engages a fixed stop 83, where

at the lever 79 and the connecting rod 81, just before the Crank lever touches the stop, have passed a dead subordinate position, so that when the crank lever hits the stop the tailstock is blocked against downward movement.

An electrical switch 84 can short of the crank lever 79 be actuated before contact with the stop 83 and this switch controls electrical circuits of the motor 64 and the electromagnetic brake 78 so that their electrical Circles are closed until the crank lever is almost in contact with the stop, and these circles open stay as long as the crank lever ax that in contact Stop remains.

The operation of the device, which was described with reference to Figure 5, is now as follows. Is the tailstock. 74 is retracted downward to a position defined by the contact of the crank lever 79 with a stop pad 85 on the base 58, then the workpiece holding device 66 is opened by the upward movement of the lever 72 to initiate the insertion of the workpiece WP ^ to enable this jig is then closed to hold the workpiece in place. A workpiece WP ₂ is then pushed into the workpiece-holding device 77 and clamped. The electric motor is then started with the aid of a suitable, manually operable control device, the operation of this motor also causing electric current to be supplied to the electromagnetic brake 78 so that the workpiece WP _{1 is} rotated and the factory kick WP _{2 is} held in place will.

The manually operable lever 82 is then moved downwards

7114S 50 22 * 7.71

moves to raise the tailstock 74 and with it the workpiece WP ₂ until contact with the workpiece VZP _{1 is} reached, at which time the crank lever 79 is close to the straight line corresponding to the connecting rod 81 so that a ^ great mechanical Feed is achieved, and sufficient axial force acts between the workpieces to provide friction heating and compression of the plasticized material. During the occurrence of this axial thrust, the crank lever 79 and the connecting rod continue to approach the straight line and finally pass the critical center position to contact the stop 83. At the point in time or around the point in time when the straight line has been reached or taken, the switch 84 is actuated and thereby the power supply to the motor 64 is interrupted and the electromagnetic brake 78 is released. The workpiece WP ^ continues to rotate due to the kinetic energy stored in the shaft 63 and the parts rotating with it and due to the friction between the workpieces, this rotation is also _{transmitted to the workpiece WP 2} and the workpiece-holding device 77 and Because of the screw connection to the tailstock 74 and because of this rotation, a large axial thrust is generated between the workpieces and forging is effected.

After a welding operation is complete, the workpiece holding device 77 can be rotated by hand or some other suitable means to restore them to their initial position.

It should be emphasized that each representation of the friction welding devices is to be understood in a general way and that individual non-essential structural features have been omitted for the sake of clarity. For example , to improve

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the concentric alignment of the workpieces the components between the screw threads or cam surfaces which serve to provide relative axial movement, usually Equipped with linear ball bearings or other precision bearings on both sides of the screw threads or cam surfaces be.

\ A number of modifications can also be made to the

β i described friction welding device are made so

can pass one other suitable form of drive to the location of the belt drive, for example, and it can also be another brake mechanism in place of the electrically operated} actuated braking mechanism described occur.

τ.

It should also be emphasized that the invention is not based on a

limited specific embodiment of a friction welding device is, for example that illustrated in Figures 3 »A or 5 Friction welding systems also have workpiece holding devices that are similar to the workpiece holding devices 26 and 27 of Figures 1 and 2 are.

All technical details recognizable in the description and shown in the drawings are for the Invention of importance.

7114610 * 2.7.71

Claims (1)

Protection claims 1. Friction welding device for performing friction welding with a heating phase and a forging phase _y consisting of a first workpiece-holding device, eleventh, second workpiece-holding device, a device for advancing one of the workpiece-holding devices to the other during the heating phase of a welding process in order to put the workpieces » are supported in the werkzeughaltehdeh devices "to bring into contact, Welter from a means for rotating one of the workpiece holding devices during the heating phase, and eleventh during 6 * r Verschmiedephase actuated means for blocking tes feed» characterized by during the Verschmiedephase a welding operation effective means (29 »30, 25) for converting the kinetic energy generated during the rotation of the one workpiece-holding device during the heating phase into an axial feed force by the one (26) of the plant reticent devices (26, 27} to the other (27) is pressed, so that thereby a greater axial force between, the workpieces (WP,., WP ₂ ) is provided W.rd, as the one by the establishment (21, 25, 28, 29, 30) for advancing the one workpiece-holding device (26) generated during the heating phase. 2. Welding device according to claim 1, characterized in that the one workpiece-holding device by rotation Kinetic energy generated during the heating phase is stored in a rotatable arrangement (17) and that the device to convert the stored kinetic energy into the axial feed force from two interlocking -IS- GewiEideverbindungen (29, 30) consists. 3. Welding device according to claim 1, characterized in that the kinetic energy generated by the rotation of a workpiece-holding device during the heating phase in a rotatable arrangement (51) is stored and that the device fcUffl converting the stored kifcs tables energy into the afciale feed force from a cam mechanism (52, 53, 54, 55) consists » 4 «welding device according to claim 1, characterized in that the feed device for moving the workpieces holding forward The device (56) for the other (51) device holding the workpiece during the heating phase consists of a mechanical lever system (45, 46, 47). 5. Welding device according to claim 1, characterized in that the feed device for moving the one workpiece-holding device forwards Device (26) to the other workpiece-holding device (27) during the heating phase at least A piston-cylinder device operated by means of fluid pressure (21). 6. Welding device according to claim 1, characterized by a frame (10), a headstock (11) which is mounted in the frame (10) for rectilinear movement, by a tailstock (25) which is fixed in the frame (10) is arranged, by a device (21) for generating a feed force on the headstock (11) in order to press it against the tailstock (25), by a white (12) rotatably mounted in the headstock (11), by a drive device ( 13, 14, 15, 1S) for air driving the rotatable shaft (12) _{| F} eiiie device add • * ι «ί f - 19 - Releasing the rotatable shaft (12) for free rotation according to the stored kinetic energy a first tool holding device (26) disposed on the rotatable shaft (12) by a second shaft (2S), which is arranged in the tailstock (25) coaxially aligned with the headstock shaft (12), by a second workpiece-holding device (27) which is arranged on the second shaft (28) by intermeshing Screw thread (29, 30) on the second shaft (28) and the tailstock (25), by a braking device (31, 32, 33), which is operable to hold the tailstock (25) against rotation, by a device (22, 23, 24) for Blocking the straight movement of the headstock (11) away from the tailstock (25), and by a control device (23), in order to cause a successive advance of the spindle stock (11) towards the tailstock (25) during the welding process, wherein the rotatable shaft (12) is free to rotate and the second shaft (28) is restrained from rotation, and the rotatable shaft (12) and the braking device (31, 32, 33) is released when the headstock (11) against a Retraction is blocked so that the second workpiece-holding Device (27) in the axial direction against the first workpiece-holding device (26) by the action of Screw thread (29, 30) is pressed while the shafts (12, 28) according to the kinetic energy contained in them stored, can be rotated. 7. Welding device according to claim 6, characterized in that the braking device consists of a disc brake (32, 33). 8, welding device according to claim 6-, characterized in that the braking device is ordered from a band brake (34). - 20 - 9, welding device according to claim 1, characterized by a frame (36), a headstock (37) which is fixedly mounted in the frame (36) by a shaft (38) rotatably supported in the headstock (37). by a drive device (39, 41) for driving the rotatable® shaft (33), by a first workpiece-holding device (51) which is attached to the rotatable shaft (38), by a device (54, 55) for transmitting a rotary movement in a positive direction on the workpiece-holding device (51), by a cam device (52, 53) which is effective between the shaft (38) and the workpiece-holding device (51), in such a way that a rotation of the workpiece-holding device ( 51) in front of the shaft (38) in said direction of rotation of the workpiece-holding device (51) given an axial movement, by a brake (49), which holds the shaft (38) against rotation, by a tailstock (44), by a device (43), which holds the tailstock (44) in the sense of a rectilinear movement to and away from the headstock (37), by a second workshop device (56) which is fixedly arranged on the tailstock (44) and by a device ( 45, 46, 47, 48) to move the tailstock (44) towards the headstock (37) to exert an axial thrust force between the workpieces (WP,., WP ₂ ), which are held firmly in the workpiece-holding devices (51, 56) a device (47, 45) for blocking a rearward movement of the tailstock (44) at the end of the approach movement of the same towards the headstock (37), and by means for separating the drive (41) from the rotatable shaft (38) and for actuation the brake (49) for stopping the rotatable shaft (38) at the end of the approach movement, so that a continued rotation of the first workpiece-holding device (51) in accordance with the kinetic energy stored therein will hold the first workpiece causes de device (51) to press against the second workpiece-holding device (56) via the action the cam means (52, 53). tO. SehireiSgerät according to claim 9, characterized in that; that the device 2 for moving the tailstock (44) towards the headstock (37) has a crank lever (45), further one Connecting rod (47) that connects the crank lever (45) to the Connecting the tailstock (44), and that means (48) are provided for rotating the shaft (46) which carries the crank lever (45) is, further a stop device against which the crank lever (45) when reaching an over-centered position hits when the tailstock (44) has been completely moved from the headstock (37). 11. Welding device according to claim 1, characterized by a frame (58), a headstock (61) which is in the frame (58) is arranged to be held fixed against axial movement by a shaft (63) rotatably mounted in the headstock (61), by drive means (64, 65) to rotate the shaft (73) to issue, further through a tailstock (74) which can be moved towards and away from the headstock (61), by a workpiece-holding device arranged on the shaft (63) Device (66), and by a second workpiece-holding device (77) carried on the tailstock (74), this workpiece-holding device The device threadingly engages the tailstock (74), further through a brake (73), which the second holding the workpiece-holding device (77) against a rotational movement, further by means of manually operable lever devices (79, 80, 81, 82) for pushing the tailstock (74) towards the headstock (61) through Mi "cfcel (83, 79) to block the retraction movement of the tailstock (74) at the Eade of a forward-facing Movement towards the headstock (61), and through a 711415021.7.71 Device (83, 84) which, at the end of the forward movement, drives the first workpiece-holding device (66) separates and releases or releases the brake (78) on the second workpiece-holding device, so that · »· by the rotary movement of the workpiece-holding devices (77, 66) in accordance with the stored kinetic energy can be continued, and the rotational movement of the second workpiece-holding device (77) due to the thread engagement an axial feed force with the tailstock (74) experiences, this workpiece-holding device (77) pressed against the first workpiece-holding device (66) will. 12. Welding device according to claim 11, characterized in that the manually operable lever arrangement has a crank lever (49) which is attached to a shaft (80) which is firmly held in bearings, that also a connecting rod (81) connects the crank lever (79) to the tailstock (74) and that an operating lever (82) is attached to the shaft (βθ) is. 13. Welding device according to claim 12, characterized in that that the crank lever (79) and the connecting rod (81) so are arranged that they pass through a reversal point or dead point ad the end of the approach movement of the tailstock (74) go to the headstock (61) and attack a fixed stop (83) to the tailstock (74) against a To block withdrawal movement. 14. Welding device according to claim 13 *, characterized in that that the drive device consists of an electric motor (64), that the brake is an electromagnetic brake (78) » 7114ilO2l, 7.K