Pipe joints or couplings – Packed – With separable follower
Utility Patent
1998-09-29
2001-01-02
Nicholson, Eric K. (Department: 3627)
Pipe joints or couplings
Packed
With separable follower
C285S354000, C285S334500, C285S339000
Utility Patent
active
06168211
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority upon German application 197 42 917.3 filed Sep. 29, 1997, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to threaded connections for metallic pipes.
EP 0 366 789 A1 describes a threaded connection with a connecting member which, towards the nut, is provided with a recess to receive a sealing ring. First, starting from the through-bore of the nut through which the pipe extends, a conical bore is provided which ends in a radially extending face in the bore of the nut. The radially extending face serves as a stop face. When the nut is fully tightened, said stop face comes into contact with the end face of the connecting member. Due to the sealing ring, only a small supporting face is at the connecting member for the associated contact face of a pipe bulge. The pipe bulge is delimited by two conical faces which abut one another by means of their greatest diameters. The further contact face of the bulge cooperates with the conical bore of the nut. The bulge is produced in a device which comprises resilient elements which partially widen the pipe and bring the pipe into contact with a contour. One of the contours is formed by the conical bore of the nut and the other one by a tool. The problem with the above-described assembly is that the tolerance conditions do not allow the pipe to be securely held. Furthermore, in the case where final tightening causes a deformation in the region of the bulge of the pipe, there is a risk that the connecting member is severely loaded in the radial direction. Thus, movement of the nut has an adverse effect on its inner threads as well as on the outer threads of the connecting member. Without the associated spring disc it is practically impossible to see whether the connection is tightened. The solution according to the state of the art is additionally disadvantageous in that standardized parts can neither be used for the connecting member nor for the nuts.
EP 0 593 325 B1 describes a threaded connection where the pipe has a formation which comprises two conical faces extending at different angles. The publication deals with a threaded-in connection where a member is provided with a bore comprising a conically tapered bore which follows a radially extending end face and changes into a cylindrical bore. Furthermore, the bore comprises a threaded portion which is arranged at a distance from the radially extending end face. Into the bore, it is possible to thread a hollow screw which, towards its end face, is provided with a conical bore. The hollow screw, by means of an annular edge formed between its end face at its end entering the bore and the conical bore, comes to rest against a conical face of the bulge of the pipe. Furthermore, between the end face of the bore and the further conical face, a supporting ring is arranged which is radially received without being guided in the bore. The support ring has a first conical face against which the pipe is supported. The supporting ring has a conically extending bore which complements the conical bore of the receiving member and extends in the opposite direction. Between the two conical bores and the outer face of the pipe, an annular receiving space is formed to receive a sealing ring. The supporting ring and the hollow screw do not come into contact with one another. The disadvantage of this embodiment is that the pipe, in the region of its bulge, is subjected to high loads. Thus, there is a risk of the pipe becoming deformed, because the tightening movement is practically unlimited.
DE 195 41 622 A1 describes a threaded connection having a connecting member, a supporting ring and a nut for a pipe with a bulge. The connecting member has a conical bore which starts and is tapered from an end face. The supporting ring is supported against the end face by a radial face. Furthermore, between the supporting ring and the end face, a first sealing element is accommodated in a recess of the supporting ring. The supporting ring is provided with an inner conical face which starts from the supporting ring end facing away from the radial face. The conical face is tapered towards the connecting member. The nut has a conical bore which extends in the opposite direction. Between the conical bore and the inner conical bore, the formation of the pipe is held by corresponding conical faces.
SUMMARY OF THE INVENTION
It is an object of the present invention to provided a threaded connection which ensures that the metallic pipe is securely held by the components associated with the threaded connection. Furthermore, it is an object to prevent the forces resulting from axial tensioning from overloading the pipe in its clamping region.
In accordance with the invention, a threaded connection for metal pipes has a connecting member with an outer thread and a cylindrical receiving bore into which the pipe projects. A nut is provided with an inner thread which matches the outer thread. The nut includes a through-bore through which the pipe extends through to enter the receiving bore. A conical bore, which widens towards the connecting member, is adjacent the through-bore in the nut. A bulge is formed on the outer wall of the pipe at a distance from its end face extending into the receiving bore. The bulge has a first contact face and a second contact face. The second face adjoins the first face at the greatest diameter of the bulge and extends in the opposite direction to the first contact face. The second contact face is received between two inner conical faces which form an annular receiving space for the bulge. One of the two inner conical faces forms a supporting face which is formed by a part of a separate supporting ring. The other one of the two inner conical faces is formed either by the conical bore of the connecting member or by the conical bore of the nut. The supporting ring includes a conical stop face to support the nut with its conical bore in the tightened condition. A holding face extends radially relative to the longitudinal axis and provides support against an end face of the connecting member. A sealing ring is arranged in an annular receiving space defined between the supporting ring, the pipe and the connecting member or between the pipe and the conical bore.
A special advantage is gained by limiting the tightening movement. When the conical bore of the nut, after the nut has been fully tightened, stops against the stop face of the supporting ring, the receiving space between the conical bore of the nut and the conical bore of the connecting member and the conical supporting face of the supporting ring cannot be reduced any further. In consequence, the bulge of the pipe cannot be overloaded. Even relatively easily deformable pipes, for example those made of an easily deformable material such as copper, or thin-walled pipes, are held in the threaded connection such that a secure and leak-proof connection is achieved. A further advantage exists in that the connection can be replaced in existing equipment/plant because the normally used standardized nuts and connecting members (DIN) can continue to be used. By supporting the nut on the supporting ring, the forces acting in the direction of rotation are either reduced or not transferred to the bulge. Thus, practically no torque is introduced into the pipe when tightening the connection.
It is also advantageous, in one embodiment, that the bulge is supported on the supporting face of the supporting ring in a region remote from the inner thread of the nut and the outer thread of the connecting member. Thus, when radial forces occur, the conditions of movement of the thread are not influenced. As the angles of the conical bore and of the supporting face and stop face are identical, it is possible to achieve balanced conditions during the tightening process. Thus, it is practically impossible for the supporting ring to be expanded in the region axially corresponding to the conical bore of the nut and the supporting face. By providing a separ
Harness & Dickey & Pierce P.L.C.
Nicholson Eric K.
Walterscheid Rohrverbindungstechnik GmbH
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