GB2105226A

GB2105226A - Apparatus for clamping workpieces of circular cross section

Info

Publication number: GB2105226A
Application number: GB08225120A
Authority: GB
Inventors: Roland Kistler
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-09-08
Filing date: 1982-09-03
Publication date: 1983-03-23
Also published as: FR2512371A1; DE3135472A1; DE3135472C2

Abstract

An apparatus for rotatably clamping a workpiece 7 of generally circular circumference, includes first, second and third rollers 1, 5, 6 with their axes arranged parallel the axis of workpiece 7. The apparatus further includes an adjusting device 15 for moving and setting the first roller 1 in a direction transverse to a line perpendicular to a plane through the axes of the second and third rollers. Each roller includes a circumferential guide groove 2 and clamping groove 3 of V-shaped cross section for use in locating the rollers on flanges of the workpieces. Groove 2 can also be used for depositing a weld lead. <IMAGE>

Description

SPECIFICATION Apparatus for clamping workpieces of circular cross section This invention relates to an apparatus for a clamped support of workpieces of generally circular cumference. The apparatus includes at least three workpiece-supporting rollers arranged radially spaced and axially parallel to one another. One or more of the rollers may be motor driven. At least one of the rollers is shiftable by means of a clamping (adjusting) device transversely to the line connecting the centre of the other two rollers. In such an apparatus the rollers clamp and hold the workpiece, thus providing a clamped support which allows rotation ofthe workpiece with respectto the apparatus or a rotation ofthe apparatus about the workpiece. Such apparatus conventionally serves as a welding aid in pipeline constructions.For example, for welding a straight pipe piece to a bend piece, the apparatus may impart a continuous, unison rotation to the two pipe components. Such arrangement permits the provision of a clean weld. The circumferential speed generated by virtue of the frictional drive between the rollers and the workpiece is advantageously dependent from the workpiece cross section.

In a known apparatus of the above-outlined type the rollers have a circumferential groove of rectangular cross section. The groove serves for receiving and clamping the pipe flange and to rotate it together with an attached bend. In this prior art apparatus, however, the workpiece is guided accurately only in case the thickness of the flange equals the width of the circumferential groove. In case the flange is thicker or thinner, the workpiece wobbles and in most cases cannot be clamped at all.

It is an object of the invention to provide an improved apparatus of the above outlined type which ensures a superior clamping and guiding of pipes or pipe flanges of widely varying thickness dimensions.

This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the rollers of the apparatus each have at least one circumferential clamping groove which has an outwardly widening, generally V-shaped cross section. The clamping groove or at least the groove bottom thus has the shape oftwo end-to-end arranged frustoconical surfaces that taper towards one another. The effect of this arrangement is that the pipe flanges of any customary thickness can be clamped and axially guided in a trouble-free manner because they are centred automatically in the groove middle. It is to be understood that the rollers in the apparatus frame are so arranged that a single radial plane constitutes a common symmetry plane for the V-shaped clamping grooves.The clamping grooves may have planar or curved side walls.

A further difficulty involved in apparatus of the conventional type has been that clamped workpieces of cylindrical outer face could axially shift during rotation. Such an occurrence must be avoided by all means particularly in automatic welding, autogenous cutting or sawing of a pipe. In case of an axial load which is generated, for example, when a chamfer is milled on the end face of a pipe, the risks of an axial shift are even further increased. Accordingly, it is a further feature of the invention to provide mutually aligned guide grooves in each roller and to further provide a hoop fastened around the workpiece such that the hoop engages into the guide groove of the rollers and thus the workpiece is circumferentially guided by the engagement of the side faces of the hoop with the side walls of the guide grooves.For each customary pipe diameter a separate set of hoops may be held in readiness.

The guide grooves in the rollers are of such a depth that the enlarged hoop ends through which tightening screws pass for clamping the hoop about the workpiece, can be received by the guide grooves in their full radial height. The groove side walls or the hoop side faces may be planar, slightly conical or spherical. The hoop width is so dimensioned with regard to its associated guide groove that no axial play will occur. The guide grooves may further serve - as an alternative to a co-operation with a hoop - to accommodate, in the course of welding two pipe pieces to one another, the weld bead projecting circumferentially from the cylindrical outer pipe surface.

Due to weight considerations, when two adjoining workpieces are to be supported bythe apparatus, the attached pipe pieces have to be clamped in such a manner that the rollers of the apparatus are associated with both workpieces. Therefore, the guide groove should advantageously be situated in the middle of the axial length of each roller. It is further expedient to locate the clamping groove as close to the free end of the roller as possible to ensure an unhindered welding even of tight bends. Thus, according to a further feature of the invention, each roller is provided with two axially spaced grooves, that is, a guide groove situated approximately in the middle of the axial length of the roller and a clamping groove ofcross-sectionally V-shape which is situated close to the free axial end of the respective roller.

Occasionally the workpieces to be clamped by the apparatus are not precisely circular. In order to ensure a uniform satisfactory frictional connection between such out-of-round workpiece and the rollers, at least one of the rollers, preferably the roller which may be adjusted by the clamping (adjusting) device, is spring-biased in the clamping direction. Spring discs have been found to be advantageous for this purpose. By means of the springs, the roller bearing may yield or advance, respectively, as the workpiece, during rotation, presents a greater or smaller diameter to the roller.

In case of very large and heavy workpieces it may be expedient to rotate the apparatus about the stationarily supported workpiece. In such an arrangement the apparatus on which the appropriate machining tools or welding tools may be mounted is circumferentially guided by means of the hoops clamped about the workpiece.

In the accompanying drawings Figure 1 is a side elevational view, partially in section, of a roller forming part of a preferred embodiment of the invention, Figure 2 is a schematic front elevational view of a clamping and rotating apparatus incorporating the invention.

Figure3 is an enlarged view taken along line Ill-Ill of Figure 2, Figure 4 is a side elevational view of a part of the preferred embodiment clamping a workpiece by its flange, Figure 5 is a side elevational view of the preferred embodiment of the invention, and Figure 6 is a fragmentary sectional view taken along line VI-VI of Figure 5.

Turning first to Figure 1, there is illustrated a roller 1 of a workpiece clamping apparatus according to the invention. At approximately the middle of the axial length of the roller 1 there is provided a circumferential guide groove 2 having a rectangular cross section.

Further, at the right-hand end of the roller 1 there is provided a circumferential clamping groove 3 which has short transitional outside walls that continue in a V-shaped symmetrical configuration. Thus, the inner face of the groove is formed of end-to-end arranged frustoconical surfaces 4a and 4b which converge to one another.

Turning now to Figure 2, there are shown three rollers 1, 5 and 6 engaging a tubular workpiece 7. The two rollers 5 and 6 which are structured identically to the roller 1 are supported in a stand parallel to one another and at the same height level. The roller 1 is situated above the rollers Sand 6. All three rollers 1, 5 and 6 are axially parallel to one another and have radial end faces which lie in a single radial plane. The roller 1 is, by means of a conventional adjusting device 15 movable vertically as indicated by the double-headed arrow, along a symmetry plane halving the distance between the two rollers 5 and 6. To accommodate workpieces of relatively small diameter, the rollers 5 and 6 which serve as a cradle for the workpiece may be brought closer to one another or forworkpieces of particularly large diameterthey can be moved away from one another.By pressing down the upper roller 1-for example, by means ofapprop riately setting the adjusting device 15-the workpiece 7 is rotatably supported by being clamped between the three rollers 1, 5 and 6. At least one of the rollers may be connected to a motor drive (not shown). In order to to maintain a slip-free driving connection between the drive roller and the workpiece despite the relatively large imbalance of the workpiece, the work faces (engagement faces) of the drive roller are preferably tempered and knurled. The adjusting (clamping) device 15 forth roller 1 includes a stack of spring discs 16 to resiliently urge the roller 1 against the surface of the workpiece 7.

Figure 3 shows the rollers 1 and 5 of the clamping apparatus as they engage a straight portion of a workpiece having several bends. The workpiece is so clamped that a welding apparatus (not shown) pro vides a weld 8 in the single radial plane passing through the groove 2 of each roller. As the welding operation progresses and the workpiece and the clamping apparatus rotate relative to one another, the generated weld bead is received in the guide groove 2 of the three rollers 1, 5 and 6.

Turning nowto Figure 4, the clamping apparatus is shown to engage a flange 9 to which a bend 10 isto be welded. The flange 9 sets itself automatically symmetrically with respect to the clamping groove 3 so that, as a result, such a workpiece too, can be rotated about the flange axis uniformly and in a tumble-free manner.

Turning now to Figure 5, at the end face of a workpiece 11 a milling tool 12 is provided for machining a chamfer. In order to support the workpiece against the axial loads generated by such a machining, around the workpiece 11 a hoop 13 is circumferentially clamped which extends into the respective guide groove 2 of the clamping rollers. A set of hoops corresponding to customary pipe diameters may be kept in readiness. As illustrated in Figure 6, each guide groove 2 has such a depth that the clamping terminals 14 of the hoop 13 may be fully accommodated therein.

It will be understood that the above description of the present invention is susceptible to various mod ifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

Claims

1. An apparatus for clamping a workpiece of generally circular circumference, comprising first, second and third rollers each having a rotary axis; said rollers being arranged axially parallel and spaced from one another; and adjusting device for moving and setting said first roller in a direction transverse to a line perpendicular to the axes of said second and third rollers, whereby the workpiece is relatively rotatably clamped between and by said rollers; the improvement wherein each said roller includes a circumferential clamping groove of V-shaped cross section.

2. An apparatus as defined in claim 1, wherein the clamping grooves in said rollers lie in a single radial plane.

3. An apparatus as defined in claim 1, further wherein each said roller includes a circumferential guide groove axially spaced from the respective said clamping groove.

4. An apparatus as defined in claim 3, wherein each said roller has an axial length and further wherein each said guide groove is situated approximately in the middle of said axial length and each said clamping groove is situated adjacent an end of the respective said roller.

5. An apparatus as defined in claim 3, wherein the guide grooves in said rollers lie in a single radial plane.

6. An apparatus as defined in claim 5, further comprising a hoop adapted to be circumferentially affixed to the workpiece, said hoop, when the workpiece is clamped by said rollers, extending into each said guide groove for circumferentially guiding the workpiece.

7. An apparatus as defined in claim 1, further comprising spring means for resiliently urging at least one of said rollers in the direction of clamping the workpiece.

8. An apparatus as defined in claim 7, wherein said spring means is included in said adjusting device.

9. An apparatus for clamping a workpiece of generally circular circumference substantially as described with reference to the accompanying drawings.