DE29700159U1 - Internal clamping device for mutual alignment and clamping of the ends of a pair of pipes to be welded together - Google Patents

Description

GMoi/97
O4.oi.i997

Internal clamping device for mutual alignment and clamping of the ends of a pipe pair to be welded together

The innovation relates to an internal clamping device for mutually aligning and clamping the ends of a pair of pipes to be connected to one another, in particular for connecting two straight pipes or a straight pipe and a pipe fitting or two pipe fittings to one another, according to the preamble of claim 1.

For the prefabrication of pipe connections, there are already clamping devices that center, clamp and round the ends of a pipe pair that are to be welded together (company brochure, Schweißtechnik Nord GmbH, 22885 Barsbüttel-Stemwarde, "The Panther informs", equipment range "Panther" and "Panther Junior"). This equipment range, with its internal clamping devices, improves other known clamping devices, such as those described in the publication G 85 07 558.8 or G 90 05 893.3. The latter cannot adequately eliminate any ovality that may exist in the pipe ends that are to be connected to one another and, moreover, cannot ensure satisfactory coaxiality of the pipe ends in every case.

When assembling pipes, so-called divisible welding tongs or divisible, closed cassette welding heads are used to align and clamp the ends of a pair of pipes that are to be welded together. Cassette welding heads are, however, not able to align and clamp the pipe ends that are to be connected with the same quality as is possible with devices from the aforementioned ^' Panther range'. This results from the fact that the latter, which use the mechanism of wedge- or cone-shaped clamping devices, can provide relatively large clamping, adjustment and joining forces. The closed

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Cassette welding heads also have the disadvantage that they are subject to very high thermal stress and therefore have a number of disadvantages in terms of their handling and the quality of the weld.
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The aim of the present innovation is to create an internal clamping device of the type mentioned at the beginning, with which, particularly during pipeline assembly, a coaxial alignment of the ends of a pipe pair to be welded together and their round and secure clamping is possible, which can be easily introduced into the pipe parts to be connected to one another to the greatest possible axial depth and which can also bend up to a curvature radii of R = 1.5D (D = nominal pipe diameter).

This object is achieved by the features of claim 1. Advantageous embodiments of the internal clamping device are the subject of the subordinate claims.

The proposed internal clamping device is, apart from the supply lines for the energy supply of the actuators and the supply of the forming gas, a clamping system that is freely movable relative to the environment, which in particular does not require any support relative to its environment in order to carry out its clamping movements, as is the case, for example, with so-called flying double collet mandrels with and without engagement and disengagement devices. The coaxial alignment of the ends of the pipe pair to be connected is achieved by a holding body having a basic shape that is axially symmetrical and whose longitudinal axis coincides with the pipe axis or at least partially touches it, and by it having two groups of clamping elements designed as clamping jaws, which are each arranged in a ring around the longitudinal axis, namely on a supply side and a front side of the internal clamping device. The

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sufficiently large clamping forces, which, among other things, effectively eliminate the ovality of the pipe ends to be connected, are achieved by wedge- or conical sliding surfaces that are assigned to each group of clamping jaws and that, viewed in the radial direction, have an ascending course from the inside to the outside from the respective long end of the holding body. In addition, each group of clamping jaws can be moved relative to the holding body and are driven independently in both axial directions by an actuator arranged in the holding body. Round and safe clamping is achieved by the fact that the precision with which the holding body and the wedge or conical surfaces integrated in it can be manufactured is directly transferred to the pipe ends to be connected by the clamping jaw guide. In this context, safe clamping is also ensured by the fact that the movement of the clamping jaws on each side of the internal clamping device (supply and front side) can be controlled separately in both directions. The actuator assigned to each clamping jaw ring is responsible for the clamping movement.

Uniform and symmetrical clamping of the ends of the pipe pair to be connected is ensured by the fact that the sliding surfaces on one side are arranged symmetrically to those on the other side, with respect to a cross-sectional plane perpendicular to the longitudinal axis of the holding body.

Coaxial alignment and uniform clamping are facilitated by the fact that the sliding surfaces of each side of the internal clamping device are arranged radially symmetrically to each other. Circular clamping is also particularly ensured by the fact that the sliding surfaces of one

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On each side of the internal clamping device there are two diametrically opposite each other.

Perfect and trouble-free clamping and unclamping of the internal clamping device as well as high operational reliability are further achieved by the fact that the actuating movement of the respective actuator is transferred to the respective assigned group of clamping jaws via a positive drive connection. The proposed advantageous designs in detail, but especially through their combination with one another, ensure the desired radial and axial symmetrical clamping of the ends of a pipe pair to be welded together.

For the purpose of forced axial and at the same time radial guidance of the clamping jaws on the wedge- or conical sliding surfaces, dovetail or T-slots are provided, via which the forces during clamping and unclamping of the internal clamping device can be safely controlled.

As an actuator for* the respective group of clamping jaws, a pressure medium-operated piston drive that can be actuated from two sides is preferably provided. This robust and reliable drive transfers the pressure medium-controlled propulsion movement of each piston via the intended form fit, which allows both an axial and radial relative movement between the holding body on the one hand and the clamping jaws on the other hand, to the assigned group of clamping jaws on each side of the holding body. A compressible medium, for example compressed air, or an incompressible medium, for example hydraulic oil or even water, can be used as the pressure medium. Actuation in the axial direction from the respective front side of the internal clamping device (supply or front side) inwards results, now viewed in the radial direction, in the clamping movement directed from the inside to the outside.

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The respective opposite loading, axially from the inside to the outside, then leads, seen in the radial direction, to the forced execution of the relaxation movement from the outside to the inside.
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In a first embodiment, a separate pressure medium chamber is assigned to each of the two pistons for the purpose of relaxing the internal clamping device, whereby the two pressure medium chambers are controlled independently of one another, either simultaneously or one after the other. By controlling the existing pressure medium chambers separately, it is therefore possible to first clamp one side and then or simultaneously also the other side of the pipe pair. The relaxation then takes place in the same way, whereby the order can be chosen as desired.

In a second embodiment, the separation of the two pressure medium chambers for relaxing the internal clamping device is eliminated and the pressure medium is applied to the two pistons for the respective actuating movement for relaxing each of the two groups of clamping jaws from a common pressure medium chamber.

In terms of its design, the internal clamping device is suitable for generating very large clamping forces, for transposing these clamping forces point-symmetrically in all directions and for remaining dimensionally stable under these clamping forces. Since the pressure medium provided during pipeline assembly, particularly on construction sites, such as compressed air, is limited in its maximum operating pressure by the operating conditions of the compressors usually used, it represents a limiting factor in terms of achieving very large clamping forces, which are particularly required when it is also necessary to eliminate ovality in the ends of a pipe pair that are to be welded together.

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In order to achieve very high clamping forces, it is proposed in this context to provide the pressure medium from a pressure amplifier connected upstream of the internal clamping device.
5

For large and very large pipe diameters, the proposed device offers the spatial conditions to implement the actuator for the respective group of clamping jaws as an electric motor or electromagnetic drive. In this case, the supply lines for the actuator are reduced to those electrical lines that are necessary for its control and for reversing its direction of action.

In addition, it is proposed that the application of forming gas to the weld seam be provided via a large number of outlet openings, which are distributed in the peripheral area of the holding body between the two groups of clamping jaws. This arrangement of the outlet openings strictly limits the volume of the space for the forming gas in the area of the weld seam and the forming gas is applied and made available directly where it is required.

The easy insertion of the internal clamping device into pipe systems at the greatest possible axial depth is achieved by the extremely compact and extremely short design of the proposed internal clamping device, which, if its outer contour were to be covered in a surface, would have an egg-shaped or similar shape. These can be rotational bodies that are formed by rotation around the axis of symmetry of a generating surface, for example an elliptical or basket-shaped surface. The external shape in conjunction with ball rollers that are distributed over the circumference in exposed places means that the possibility of tilting and thus the risk of tilting is excluded. The possible axial depth is limited only by

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by the length of the available transport rod or a pulling rope to which the internal clamping device can be connected and the length of the existing supply hoses for pressure medium and forming gas. In any case, the internal clamping device can be easily and simply inserted over a length that corresponds to the usual standard pipe lengths.

It simplifies the connection of the supply lines for drive energy and forming gas and increases operational safety if the supply lines are connected, as proposed, to a hose manifold at the supply-side end of the internal clamping device and if these supply lines are continued together in a strain-relieved protective hose.

The proposed internal clamping device is a clamping system that is subject to high stress, particularly in rough assembly operations, in which the necessary operational reliability and high availability as well as sufficient wear resistance are ensured by the fact that the holding body and the actuators are made of high-strength steel or, for weight reduction, of aluminum and the clamping jaws are made of bronze or materials with comparable sliding properties or, also for weight reduction reasons, of titanium.

The special shape of the internal clamping device means that it can be easily inserted into pipe bends that can be greater than 90 degrees. The pipe run can also be curved alternately, whereby the positioning of the internal clamping device at turning points of the curved contour is easily possible.

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Examples of the proposed internal clamping device according to the innovation are shown in the drawing and are described below. They show

Figure 1 shows a meridian section through the proposed internal clamping device according to a section line A-B marked in Figures 2 and 2a;

Figure 2 is a view of the holding body of the internal clamping device according to Figure 1 from the supply side V;

Figure 2a a view of the holding body of the internal clamping device according to Figure 1 from the front side D opposite the supply side and 15

Figure 3 shows a second embodiment of the proposed internal clamping device in a so-called half-section, with the meridian section being shown in the upper part of the illustration and the view of the internal clamping device being shown in the lower part.

An internal clamping device 1 (Figure 1) has in its interior a holding body 2, which consists of a pot-shaped housing body 2a and a cover 2b that closes it. A first and a second adjusting piston 8 are received in a cylindrical recess 2c of the housing body 2a in such a sealing manner that they form a third pressure medium chamber III between them, and that the first adjusting piston 5, on the other hand, forms a first pressure medium chamber I between itself and the cover 2b and the second adjusting piston 8 forms a second pressure medium chamber II between itself and the front boundary of the housing body 2a. The first adjusting piston 5 is firmly connected to a first connecting rod 4, which is guided centrally through the cover 2b to the outside and is firmly connected there to a cross member 3.

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The second piston 8 is firmly connected in the same way to a second connecting rod 7, which is guided centrally outwards over the frontal boundary of the housing body 2a and has a fixed connection there with a second cross member 6.

On the outer surface of the housing body 2a, which is preferably formed from the surface of two truncated cones, the associated cone tips of which lie on the longitudinal axis of the housing body 2a and face away from one another, several groove-shaped recesses 20 are provided, preferably evenly distributed over the circumference, the respective groove base of which forms a surface 21 or 22 inclined to the longitudinal axis of the housing body 2a (see also Figures 2 and 2a). The wedge-shaped surfaces 21 and 22 are preferably designed as flat sliding surfaces (any other surface shape possible in terms of production technology is also suitable), with a dovetail-shaped recess 23 or 24 being provided in each surface 21, 22 in the direction of their axial longitudinal extension (alternatively, a T-slot is also useful, for example). Two of the wedge surfaces 21 and 22 are preferably arranged diametrically opposite one another, so that they form a symmetrical wedge that widens from the respective end to the middle in relation to the longitudinal axis of the housing body 2a. An internal clamping device 1 for the nominal pipe diameter DN 100 is, for example, preferably provided on each side, the supply side V and the front side D, with six wedge surfaces 21 and 22 arranged in equal divisions around the circumference. Clamping jaws 9a and 9b slide on these, on the side of which facing the respective wedge surface 21 and 22 a counterpart corresponding to the dovetail-shaped groove 23 and 24 is formed.

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Corresponding to the division of the groove-shaped recesses 20 for forming the wedge surfaces 21, 22, in the first and second cross members 3 and 6, respectively, star-shaped and perpendicular to the axis of the internal clamping device 1 grooves are provided, which are not designated in more detail, in each of which a guide block 10a or 10b is positively received, and which on the other hand, also positively engages in a corresponding recess at the respective end of the clamping jaws 9a or 9b. This positive, radially displaceable engagement between the clamping jaws 9a, 9b and the cross members 3 and 6 ensures a synchronized displacement movement of all clamping jaws 9a on the supply side V and all clamping jaws 9b on the front side D of the internal clamping device 1. Since the wedge surfaces 21 and 22 are arranged absolutely symmetrically to one another with respect to a cross-sectional plane perpendicular to the longitudinal axis of the housing body 2a, the forced sliding movement of the clamping jaws 9a and 9b on the respective associated wedge surface 21 or 22 on the one hand and their likewise forced radial compensation movement in connection with the respective cross member 3 or 6 ensure the coaxial alignment movement of the internal clamping device 1 as required for the task as well as round and secure clamping in the respective associated end of the pipe pair to be connected to one another.

The clamping jaws 9a and 9b are contoured on their clamping side in such a way that in straight pipe ends Kl they rest against the enveloping pipe in their area adjacent to the weld seam and that in curved pipe ends K they also contact the enveloping pipe contour in their area adjacent to the weld seam.

The sealing of the first and second adjusting pistons 5 and 8 within the cylindrical recess 2c is achieved by

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known sealing means 13 and 14. The sealing of the first and second connecting rods 4 and 7 is carried out using sealing means 15 and 16, which are also known per se. Supply lines 18 are led into the cover 2b of the holding body 2 via connecting pieces 17. Since each of the pressure medium chambers I, II and III/ can be supplied with pressure medium, preferably compressed air, independently of one another, three supply lines 18 are required for this. Their arrangement can be seen in Figures 2 and 2a. A connection a is provided for the supply of pressure medium for clamping at the supply-side end V of the internal clamping device 1, a connection b is used to supply pressure medium for clamping at the front end D and via a connection c the third pressure medium chamber III is pressurized with pressure medium for relaxation at the supply-side and/or front end V or D. Figure 2a also shows a fourth connection d, which is used to supply forming gas F. The latter flows out of the housing body 2a in the area of the weld seam, here in the area of the largest diameter of the latter (outlet for forming gas F, Figure 1). Channels are used to guide the pressure medium from connections a to d, of which a channel 2d is shown as an example in Figure 1, which serves to supply the pressure medium from connection a to the first pressure medium chamber I, which is arranged between the cover 2b and the first adjusting piston 5. The other channels cannot be shown in the present meridian section (Figure 1). Figures 2 and 2a indicate in dashed lines how these channels 2d can be guided in the holding body 2a as an example.

The holding body 2, consisting of the housing body 2a and the cover 2b, is held together by means of connecting means 11, 12, for example screw connections (Figure 1). In this context, Figures 2 and 2a show three

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evenly distributed through holes 2e for the screw connections 11, 12 used. In addition, the arrangement of the recesses 20 for forming the front wedge surfaces 21, which face the supply side V of the internal clamping device 1, and the rear wedge surfaces 22, which face the front side D, are illustrated. Furthermore, the arrangement and design of the dovetail-shaped grooves 23, 24 are also shown.

In a second embodiment of the internal clamping device (Figure 3), a holding body 200 is divided in the middle by a middle part 200c in a cross-sectional plane oriented perpendicular to the longitudinal axis. This creates two separate pressure medium chambers IHa and IHb on either side of this middle part 200c, each of which can be supplied with pressure medium via a supply bore 230 or 240. These supply bores 230 and 240 are either connected to a common collecting bore 250, or they are supplied separately from one another via a respective collecting bore.

The pressure medium chambers I and II for the clamping movement of the first and second pistons 5 and 8 each have a supply bore 210 and 220, respectively, which, like the supply bores 230 and 240, are arranged in the outer region of the holding body 200, namely in a supply-side housing part 200a and a front-side housing part 200b, which are coaxially centered and connected to one another via the middle part 200c. In the same way, a supply line 18a for the discharge of forming gas F is continued in the holding body 200. The outlet openings 25 can be seen in the lower part of the illustration, which are arranged in a large number distributed over the circumference of the holding body 2 or 200, with a view to Figure 3, over the middle part 200c. For example, 19 denotes ball rollers which are mounted at an exposed location around the circumference of the cross members 3 and 6, preferably evenly distributed.

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They make it easier to insert the internal clamping device 1 into the respective pipe and prevent it from jamming.

In contrast to the embodiment according to Figure 1, in the embodiment according to Figure 3, the positive engagement of the clamping jaws 9a and 9b is ensured by drivers 3a and 6a, which are fixed, preferably materially bonded, to the cross members 3 and 6. The cross member and associated driver 3, 3a and 6, 6a each expediently form a one-piece unit, the design of which simultaneously provides a positive, radially displaceable engagement with the associated clamping jaws 9a and 9b during the axial displacement movements and thus a synchronized displacement movement of all clamping jaws 9a on the supply side V and all clamping jaws 9b on the front side D of the internal clamping device 1.

The supply lines 18 for the actuators 3, 4, 5 and 6, 7, 8 and a supply line 18a for forming gas F are connected to a hose manifold 27 at the supply-side end D of the internal clamping device 1, whereby these lines 18, 18a are continued together in a strain-relieved protective hose 26 to the respective supply sources (not shown). The remaining structure of the second embodiment of the internal clamping device corresponds essentially to that of the first embodiment according to Figure 1. Parts with the same effect are designated in the same way. A further explanation is therefore unnecessary at this point.

Figures 1 and 3 show the respective internal clamping device 1 above its longitudinal axis in its relaxed position and below it in its clamped position (only Figure 1). In addition, the dash-dotted contours K and Kl indicate the shape of the pipe ends to be connected to one another

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in the area of the positioned internal clamping device 1. This is also suitable for use in pipe contours K with a curvature radius R = 1.5D (D = nominal pipe diameter). In addition, clamping of straight pipe ends (contour Kl) is of course also possible without any problem.

The innovation has been described in the context of two preferred embodiments, but it is understood that in practice, experts can also implement design variants without departing from the scope of the innovation and the industrial property rights to which it is entitled. This concerns in particular the various options for synchronized clamping jaw movement, the design of the guide surfaces for the clamping jaws, the positive connection between the clamping jaws and the wedge or conical surface on the one hand and the cross members on the other, the design of the actuators (pressure-operated piston drives, as described by way of example, or electric motor-operated actuators) and the gas flow within the holding body 2 or 200.

Claims (15)

GMOl/97 04.01.97 Protection claims 1. Internal clamping device for mutually aligning and clamping the ends of a pair of pipes to be welded together, in particular for connecting two straight pipes or a straight pipe and a pipe fitting or two pipe fittings to one another, by means of clamping elements guided axially and radially by a holding body, wherein the clamping elements are arranged on wedge- or conical sliding surfaces of the holding body and distributed over its circumference and the relative movement between the holding body and the clamping elements is carried out by an actuator, characterized in that • that the internal clamping device (1) can be freely positioned at the clamping position in question, • that the holding body (2;200) has a basic shape that is axially symmetrical and whose longitudinal axis coincides with the pipe axis or at least touches it, • that it has two groups of clamping members designed as clamping jaws (9a; 9b), each of which is arranged in a ring-shaped distribution around the longitudinal axis, whereby the wedge- or conical sliding surfaces (21; 22) of each group have a course rising from the inside to the outside from the respective longitudinal end of the holding body (2; 200), viewed in the radial direction, and · that each group of clamping jaws (9a; 9b) is displaceable relative to the holding body (2; 200), in both axial directions, each independently driven by an actuator (3, 4, 5; 6, 7, 8) arranged in the holding body (2; 200). 2. Internal clamping device according to claim 1, characterized in that the sliding surfaces (21) of one side to those provided on the other side (22) , with respect to 04.01.97 J I*..* &Idigr; J *i Ii** a cross-sectional plane perpendicular to the longitudinal axis of the holding body (2;200), are arranged symmetrically. 3. Internal clamping device according to claim 1 or 2, characterized characterized in that the sliding surfaces (21; 22) of each side are arranged radially symmetrically to one another. 4. Internal clamping device according to one of claims 1 to 3, characterized in that two of the sliding surfaces (21; 22) on each side are diametrically opposite one another. 5. Internal clamping device according to one of claims 1 to 4, characterized in that the actuating movement of the respective actuator (3,4,5; 6,7,8) is transmitted to the respectively assigned group of clamping jaws (9a; 9b) via a positive driving connection. 6. Internal clamping device according to one of claims 1 to 5, characterized in that the clamping jaws (9a; 9b) are guided on the respective sliding surfaces (21; 22) by means of dovetail or T-grooves (23). 7. Internal clamping device according to one of claims 1 to 6, characterized in that the actuator (3,4,5; 6,7,8) for the respective group of clamping jaws (9a; 9b) is designed as a pressure medium-operated piston drive which can be actuated from two sides. 8. Internal clamping device according to claim 7, characterized in that the pressure medium for the respective adjusting movement for relaxing each of the two groups of clamping jaws (9a; 9b) is applied from a common pressure medium chamber (III). GMOl/97
04.01.97 l! 9. Internal clamping device according to claim 7 or 8, characterized in that the pressure medium is provided from a pressure amplifier connected upstream of the internal clamping device (1). 10. Internal clamping device according to one of claims 1 to 6, characterized in that the actuator for the respective group of clamping jaws (9a; 9b) is designed as an electromotive or electromagnetic drive.
10 11. Internal clamping device according to one of claims 1 to 10, characterized in that the holding body {2;200) in the
The circumferential region between the two groups of clamping jaws (9a; 9b) has a plurality of outlet openings (25) for forming gas distributed over the circumference. 12. Internal clamping device according to one of claims 1 to 11, characterized in that a surface enveloping the internal clamping device as a whole has the shape of a body of revolution which is formed by rotation about the axis of symmetry of a generating surface, for example an egg-shaped, elliptical or basket-shaped surface.
becomes. 13. Internal clamping device according to one of claims 1 to 12, characterized in that supply lines (18) for the actuators (3,4,5; 6,7,8) and a supply line (18a) for forming gas (F) are connected to a hose manifold (27) at the supply-side end (V) of the internal clamping device. device (1) and that the supply lines (18,18a) are connected together in a strain-relieved
Protective hose (26) should be continued. GMOl/97
04.01.97 14.Internal clamping device according to one of claims 1 to 13, characterized in that ball rollers (19) are embedded in exposed surface areas of the internal clamping device (1).
5 15. Internal clamping device according to one of claims 1 to 14, characterized in that the holding body (2; 200) and the actuators (3, 4, 5; 6, 7, 8) are made of high-strength steel or aluminum and the clamping jaws (9a, 9b) are made of bronze or materials with comparable sliding properties or of titanium.