Joints and connections – Interfitted members – Clamped members
Reexamination Certificate
2002-09-09
2004-08-24
Sandy, Robert J. (Department: 3677)
Joints and connections
Interfitted members
Clamped members
C403S373000, C403S374100, C403S374300, C403S374400, C403S367000, C285S420000
Reexamination Certificate
active
06779944
ABSTRACT:
The invention relates to a clamping device for aligning and clamping two pipe ends with clamping plates which are arranged axially distanced, with clamping wedges extending in axial direction and which on a first side in radial direction are movably mounted on the clamping plates, and on a second side have a contact surface for acting on the pipe ends, with a guide for guiding the clamping wedges on the clamping plates and with an actuation means for moving the clamping wedges. The invention extends further to a clamping device set with several sets of exchangeable clamping wedges which have differing distances from the inner to the outer side.
For welding tubes it is necessary for the bordering ends of the tubes to be welded to be aligned to one another in a certain manner and held in this position. An ovality of the tubes which is often present would at the same time be alleviated as much as possible. In order to simplify the alignment and firm holding of the pipe ends in the desired position, there are basically two possibilities. The one possibility is to use clamping devices which on the inside or outside are attached to the pipe ends to be welded and which may be rigidly clamped to the ends of the tubes by moved clamping elements. Various embodiments of such clamping devices are known, which either in each case clamp only one pipe end so that two clamping devices are required, or which clamp both pipe ends.
The second, more oftenly used possibility is to hold the pipe ends after alignment in the desired position not by a special clamping device but by binding the two pipe ends to one another by a certain number of welding points and thus by fixing their mutual alignment. This possibility which is largely carried out by hand is above all applied when the ends of the pipe are to be welded to one another with a particularly high accuracy, and this is further effected under unfavourable conditions, such as in the offshore field. The disadvantage of this is that the quality fluctuates greatly. Often one achieves only very poor welding results. Clamping tools with clamping plates and clamping wedges are furthermore also known from the field of metal machining. Such clamping tools are for example used with milling for machining tubes. The miller is anchored in the pipe by way of the clamping tool inserted at one end of the tube. Similar clamping tools are also known with lathes. Common to all these is the fact that they are only designed for clamping one pipe end, and not for clamping and mutual alignment of two pipe ends, as is required when welding two pipe ends.
The disadvantage of the known clamping devices is the fact that the known clamping devices do not permit the achievement of the demanded accuracy. The manual alignment and clamping of the pipe ends by way of weld-binding is time consuming and expensive, in particular given poor environmental conditions.
It is therefore the object of the invention to provide a clamping device of the initially mentioned type, which permits a more simple and accurate clamping of two pipe ends.
The solution according to the invention lies in a welding device with the features of claim
1
as well as a clamping device set with the features of claim
15
. Advantageous further formations are specified in the dependent claims.
Firstly some used terms are to be explained once:
A clamping device is to be understood as a device which serves for mutually aligning and holding two pipe ends in position with or without associated fittings or shape parts. As a rule the device at the same time is designed to align the pipe ends coaxially; however also other alignment types are conceivable, e.g. at a certain angular displacement to the respective middle axis of the two tubes.
Clamping plates are to be understood essentially as disk-shaped or annular elements which serve for mounting and for guiding the clamping wedges. With a clamping device which is designed for clamping on the pipe inner surface, the clamping plates are designed such that they may be introduced into the pipe ends; with a clamping device which is designed for clamping on a pipe outer surface, the clamping plates are designed such that they may be pushed over the pipe ends. The clamping plates although having usually a round shape, may also have a shaping which is dependent on the shape of the pipe ends which are to be welded to one another. Thus for example with clamping devices for welding square tubes it may be designed rectangular or square.
Elastic holding means is to be understood as a means which comprises at least one elastic element which may exert forces onto another component. With the elastic element it may be the case of such an element which obtains its elasticity essentially from its shaping, for example a spiral spring, or which obtains its elasticity from its material properties, such as for example rubber.
According to the invention with a clamping device of the initially mentioned type it is also envisaged to provide the guide with an elastic holding means for holding the clamping wedges on the clamping plates. By way of the elastic holding means it is achieved that with the clamping device according to the invention the pipe ends to be welded to one another may also be clamped with the required accuracy and security when the clamping device is not exactly aligned on the pipe ends but assumes an incorrect position, for example is arranged slightly tilted. The elastic holding element gives the clamping wedges within the guide a certain movability with respect to the clamping plates, so that the clamping wedges inspite of the incorrect position of the clamping device bear securely on the pipe ends and then finally allows these to be aligned and clamped. Thanks to it elasticity, although the holding means attempts to keep the clamping wedges in their normal position with respect to the clamping plates, it however when appropriate allows the clamping wedges to assume a position deviating from the normal position in order thus to compensate errors which result from a tilted arrangement of the clamping device in the pipe ends or resulting from other inaccuracies. A further advantage of the elastic holding means according to the invention is the fact that it has a loss-preventing effect. The loss-preventing effect is based on the fact that the elastic holding means attempts to hold the clamping wedges in their normal position to the clamping plates. It therefore counteracts undesired movements of the clamping wedges with respect to the clamping plates and thus holds the clamping wedges on the clamping plates.
It is surprising that on the one hand with the elastic holding means according to the invention the clamping wedges may be given a certain degree of freedom with respect to the clamping plates for compensating alignment errors, such as for example tiltings, without worsening the security and accuracy of the guiding of the clamping wedges on the clamping plates.
Preferably the elastic holding means comprises a spring-loaded ball, which is arranged on one of the two, the clamping plate or the clamping wedges in order to cooperate with the other of the two, the clamping wedges or the clamping plate. The ball impinged by a spring with force exerts a holding force by way of which the clamping wedge is held on the clamping plates. This force is usefully dimensioned such that on the one hand it is sufficiently high to hold the clamping wedges on the clamping plates, but on the other hand with the occurrence of greater forces, as occur when clamping the clamping device in the tilted position, is overcome and thus permits a movement of the clamping wedges out of their normal position.
Often it is the case that the spring-loaded ball is arranged on the clamping plates and acts on a surface of the clamping wedge; one may however also reversely envisage for the spring-loaded ball to be arranged on the clamping wedges and to act on the surface of the clamping plate.
Usefully the elastic holding means comprises a deepening which is arranged on the one of the two, the clamping wedg
Lugo Carlos
Morrison & Foerster / LLP
Sandy Robert J.
Schnorrer Walter
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