GB2096926A - Chucks - Google Patents

Abstract

A chuck for use in the internal and external finishing of pipe ends on a lathe has two sets of axially spaced jaws (2, 3). One set (2) is operative to clamp a pipe (4) at a section spaced from its end while the external surface at the end is finished. The other set (3) is used after the first finishing operation to clamp the finished external surface while the internal end finishing operation is carried out. Both operations can thus be carried out without relocation of the pipe (4) in the chuck (1) being necessary. <IMAGE>

Description

SPECIFICATION A chuck for clamping pipe ends This invention relates to a chuck for clamping a pipe end during finishing operations. Particularly it relates to the provision of a chuck which will maximize stability during such finishing operations.

Elongate workpieces, such as pipes, are commonly clamped on lathes for finishing the ends, normally with a front end chuck and a rear end chuck. Where pipes must be provided with a precise internal thread, e.g. for oil field pipes, particularly accurate and stable clamping is needed. Heretofore, this requirement could only be met, if, after the external surface at the end is finished, the pipe is re-chucked, usually in a second lathe, with the finished surface being clamped in the chuck. The internal finishing, e.g.

the cutting of a thread, was then completed while the pipe is stably held.

The present invention seeks to provide a chuck enabling finishing operations to be carried out, both internally and externally, without the need for the workpiece to be re-clamped. According to the invention, a chuck has two sets of radially adjustable chuck jaws for clamping a pipe end, one set being adapted to extend axially beyond the other, for engaging a section of a said pipe axially spaced from that to be engaged by the other set.

In the use of a chuck according to the invention on a pipe end, the one set of jaws are first withdrawn and the external surface at the end of the pipe finished while the pipe is clamped by the other set. Then, the one set of jaws are applied to clamp the finished external surface, and the internal finishing operation is carried out. In this way, an accurate and precise finishing of a pipe end and of a thread therein is made possible without the pipe having to be re-chucked onto a second lathe. Faults, which may result from dual clamping, are avoided, and the processing time can be considerably shortened.

An embodiment of the invention will now be described by way of example and with reference to the accompanying diagrammatic drawing wherein:~ Figure 1 is a front view of the chuck; and Figure 2 is a side view, partly in section, in the direction "A" on Figure 1.

As shown in the drawing, interior chuck jaws 2 are arranged in a manner known per se in chuck body 1. At least two exterior chuck jaws 3 are arranged staggered thereto, such that they jut out beyond the interior chuck jaws 2 parallel to the axis of the chuck body 1.

In the use of the chuck illustrated, the pipe 4 (Figure 2) is clamped with a front end chuck and a rear end chuck in the lathe. With this clamping the pipe end is finished externally over the desired length. Without re-chucking, the outer chuck jaws 3 are then applied to engage the finished surface.

This means the outer chuck jaws 3 must project axially beyond the inner chuck jaws 2, so far that an efficient engagement of the chuck jaws on the finished surface is ensured. In the subsequent finishing of the front face and of the interior of the pipe, e.g. thread cutting, the pipe end is free from vibrations by virtue of the additional clamping at the end, so that a precise finishing can take place in one clamping. The pipe does not have to be released, and neither does the chuck have to be shifted axially relative thereto. It will be appreciated that the outer chuck jaws 3 may be fully removable from the chuck body 1, enabling complete access to the pipe end during the external finishing operation.

1. A chuck having two sets of radially adjustable chuck jaws for clamping a pipe end, one set being adapted to extend axially beyond the other, for engaging a section of a said pipe axially spaced from that to be engaged by the other set.

2. A chuck according to Claim 1 wherein said one set of jaws comprises at least two collectively adjustable jaws, and wherein said other set comprises three collectively adjustable jaws.

3. A chuck for clamping a pipe end substantially as described herein with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A chuck for clamping pipe ends This invention relates to a chuck for clamping a pipe end during finishing operations. Particularly it relates to the provision of a chuck which will maximize stability during such finishing operations. Elongate workpieces, such as pipes, are commonly clamped on lathes for finishing the ends, normally with a front end chuck and a rear end chuck. Where pipes must be provided with a precise internal thread, e.g. for oil field pipes, particularly accurate and stable clamping is needed. Heretofore, this requirement could only be met, if, after the external surface at the end is finished, the pipe is re-chucked, usually in a second lathe, with the finished surface being clamped in the chuck. The internal finishing, e.g. the cutting of a thread, was then completed while the pipe is stably held. The present invention seeks to provide a chuck enabling finishing operations to be carried out, both internally and externally, without the need for the workpiece to be re-clamped. According to the invention, a chuck has two sets of radially adjustable chuck jaws for clamping a pipe end, one set being adapted to extend axially beyond the other, for engaging a section of a said pipe axially spaced from that to be engaged by the other set. In the use of a chuck according to the invention on a pipe end, the one set of jaws are first withdrawn and the external surface at the end of the pipe finished while the pipe is clamped by the other set. Then, the one set of jaws are applied to clamp the finished external surface, and the internal finishing operation is carried out. In this way, an accurate and precise finishing of a pipe end and of a thread therein is made possible without the pipe having to be re-chucked onto a second lathe. Faults, which may result from dual clamping, are avoided, and the processing time can be considerably shortened. An embodiment of the invention will now be described by way of example and with reference to the accompanying diagrammatic drawing wherein:~ Figure 1 is a front view of the chuck; and Figure 2 is a side view, partly in section, in the direction "A" on Figure 1. As shown in the drawing, interior chuck jaws 2 are arranged in a manner known per se in chuck body 1. At least two exterior chuck jaws 3 are arranged staggered thereto, such that they jut out beyond the interior chuck jaws 2 parallel to the axis of the chuck body 1. In the use of the chuck illustrated, the pipe 4 (Figure 2) is clamped with a front end chuck and a rear end chuck in the lathe. With this clamping the pipe end is finished externally over the desired length. Without re-chucking, the outer chuck jaws 3 are then applied to engage the finished surface. This means the outer chuck jaws 3 must project axially beyond the inner chuck jaws 2, so far that an efficient engagement of the chuck jaws on the finished surface is ensured. In the subsequent finishing of the front face and of the interior of the pipe, e.g. thread cutting, the pipe end is free from vibrations by virtue of the additional clamping at the end, so that a precise finishing can take place in one clamping. The pipe does not have to be released, and neither does the chuck have to be shifted axially relative thereto. It will be appreciated that the outer chuck jaws 3 may be fully removable from the chuck body 1, enabling complete access to the pipe end during the external finishing operation. CLAIMS

1. A chuck having two sets of radially adjustable chuck jaws for clamping a pipe end, one set being adapted to extend axially beyond the other, for engaging a section of a said pipe axially spaced from that to be engaged by the other set.

2. A chuck according to Claim 1 wherein said one set of jaws comprises at least two collectively adjustable jaws, and wherein said other set comprises three collectively adjustable jaws.

3. A chuck for clamping a pipe end substantially as described herein with reference to the accompanying drawing.