GB2284775A

GB2284775A - Pipe holding device

Info

Publication number: GB2284775A
Application number: GB9424144A
Authority: GB
Inventors: Heinz Ehrle; Johann Mejzlik
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1993-12-17
Filing date: 1994-11-30
Publication date: 1995-06-21
Anticipated expiration: 2014-11-30
Also published as: GB2284775B; GB9424144D0; ES1029559Y; IT234288Y1; FR2714139B3; ES1029559U; FR2714139A3; ITMI940826V0; DE9319410U1; ITMI940826U1

Abstract

A device for holding pipes during the forming of pipe flanges or sockets comprises two holding jaws 120, 122 which are movable towards one another and have recesses 124, 126 for receiving the pipe. The recesses have a dentiform profile, with bottom 134, 136 lands which are greater than or equal to the pipe outside diameter whose teeth 138, 140 leave free a recess 124, 126 with an inside radius which is smaller by a small amount "x" than half the pipe outside diameter and whose tooth flanks 142, 144 extend along the pipe periphery. Shifting of the pipe during machining is avoided except for a slight determinable slip. <IMAGE>

Description

Device for holding pipes under axially occurring forces Background art The invention relates to a device for holding pipes under axially occurring forces.

When manufacturing, for example, pipes with flanges or flared regions, the pipes are clamped in a friction-locked manner and are also acted upon by forces in an axial direction.

Depending on the material and/or the surface finish, the pipe shifts inside the holding device during machining, making an increased amount of finishing unavoidable.

It is also known to accommodate the pipes, if they are of a bent shape, in a form-fit manner in accordance with the shape but this calls for a plurality of purpose-made holding jaws.

Advantages of the invention By means of the pipe holding device according to the invention it is possible substantially to reduce the required number of holding jaws, which was hitherto dependent on the pipe diameter and the pipe shape, since only one pair of holding jaws per pipe diameter is required. Furthermore, by virtue of the refinement of the holding jaws the effect is achieved whereby the pipe, during forming of the flanges and/or during pressing in of a profiled mandrel, settles only by a predeterminable slip inside the holding jaws. As a result, it is possible for the pipe in its unmachined length to be so dimensioned that after machining subsequent work, in particular cutting to length, is unnecessary and a reduction in cost and waste is achieved.

When the holding jaws comprise a plurality of teeth with steep, in particular vertical tooth flanks, the result is a plurality of small edges against which the pipe may be supported in the course of subsequent machining.

Preferably, the teeth of one holding jaw lie opposite the bottom lands of the other holding jaw, and/or the teeth of the holding jaws mesh one into the other. As a result, on the sides of the pipe wall lying opposite the teeth, small bulges are formed which enable an improved form closure between holding jaws and pipe. The formation of said bulges is promoted by corresponding clearances between the teeth of a holding jaw.

Drawings A holding device for pipes is illustrated in the drawings and explained in greater detail in the following description.

Figures la to ld and Figure 2 shows a first holding device and Figures 3a, 3b and Figure 4 show a second holding device.

Description of the embodiment There follows a description of two preferred forms of construction of the holding jaws used in a device for manufacturing the pipes for pipe joints. When manufacturing pipe flanges or sockets, it is necessary to clamp the pipe 128 non-displaceably by means of the first holding device.

According to Figure 1, the holding jaws 120 or 122 have on one side a downwardly open, semicircular opening 124 or 126, into which a pipe 128 may be inserted and secured.

The openings 124 and 126 extend along the longitudinal axis of the holding jaws 120 and 122 and have a dentiform profile 130 and 132 on their inner periphery. The bottom lands 134 and 136 have a radius corresponding to half the outside diameter of the pipe 128. The teeth 138 and 140 are raised relative to the bottom lands 134, 136 by a small amount "x", i.e. the inside radius of the teeth 138, 140 is smaller by "x" than that of the bottom lands 134, 136. The tooth flanks 142, 144 thereby produced extend along the surface of the recess 124, 126 or along the outer periphery of the clamped pipe 128.

To clamp the pipe 128, it is inserted into the opening 126 which, for said purpose, has a bevel 146. The holding jaw 120 is then pressed with its opening 124 onto the pipe 128 until the holding jaws 120 and 122 lie one on the other and the bottom lands 134 and 136 rest against the outside diameter of the pipe. In the process, the teeth 138 and 140 are impressed into the outside diameter of the pipe, the material of which is displaced. Sharply delimited shoulders are therefore produced on the pipe outside diameter at the tooth flanks 142 and 144, thereby guaranteeing a non-slip hold between the holding jaws 120, 122 and the pipe 128. Upon the occurrence of an axial force 148, the pipe 128 is no longer able to slide axially relative to the jaws 120, 122. Only a slight minimal slip occurs, which is material- and surface-dependent and is also attributable to tolerances within the tool. Said slip is, however, determinable and constant.

To enable improved pressing of the holding jaws 120 and 122 one onto the other when a pipe has been inserted, the jaw 120 also has a bevel 150.

The displacement of material at the pipe outside diameter continues as far as into the pipe inside diameter, which may lead to a slight reduction in the clear width of the pipe. To keep said effect to a minimum, the teeth 138 of the jaw 120 are disposed opposite the bottom lands 136 of the jaw 122 and vice versa. In said manner, a reduction at one side alternates with a reduction at another side inside the pipe, thereby limiting the narrowing of the clear width of the. pipe 128 to an acceptable dimension.

The amount "x" should be kept low in order to guarantee that the clear width is affected as little as possible. The greater the number of teeth 138, 140 and tooth flanks 142, 144 which may be formed, the smaller the amount "x" may be to achieve the full effect. The transfer of force is then spread out over a plurality of small surfaces corresponding to the number of tooth flanks. Advantageously, the amount "x" is smaller than the wall thickness of a pipe.

In order further to reduce impairment of the clear width of the pipe 128, according to Figures 3 and 4 clearances 152 may be formed between the teeth 154 in such a way that the radius of the bottom lands 156 is much greater than half the pipe outside diameter. Moreover, according to Figure 13 the bottom lands 156 may be left laterally fully open and the teeth 154 may be lengthened to such an extent that they mesh one into the other when the holding jaws 158 are pressed together.

In said case also, a pipe to be clamped is inserted as far as possible into a recess 124, the jaws 158 are pressed one onto the other and the pipe 128 is arrested. The teeth 154, which again have an inside radius which is smaller by x" than the pipe outside diameter, impress a dentiform profile onto the outside diameter of the pipe 128, as a result of which a nonslip retaining bond arises at the tooth flanks and, except for a slight slip, axial forces may be absorbed.

As a result of said arrangement, the clear width of the pipe 128 is not impaired because, for each indentation formed by material displacement in the pipe inside diameter, there is a corresponding bulge on the opposite side.

The described holding jaws need only be supplied for each pipe outside diameter to be machined and are independent of the further shape of the pipes 128. The axial force is absorbed directly through the form closure of the tooth flanks with the impressed profile and need not be effected by a form closure which is predetermined by the further shape of the pipe.

Claims

1. Device for holding pipes under axially occurring forces, in particular during the forming of pipe flanges or sockets, characterized by two holding jaws (120, 122, 158), which are movable towards one another and have openings (124, 126) for receiving the pipe (128), said openings having a dentiform profile (130), a) whose deeper-lying bottom lands (134, 136) are greater than or equal to the pipe outside diameter, b) whose teeth (138, 140, 154) leave free a recess (124, 126) with an inside radius which is smaller by a small amount "x" than half the pipe outside diameter and c) whose tooth flanks (142, 144) extend along the pipe periphery.

2. Device according to claim 1, characterized in that the amount "x" is smaller than the wall thickness of the pipe (128)

3. Device according to claim 1 or 2, characterized in that the recesses (124, 126) comprise a plurality of teeth (138, 140, 154) with steep, in particular vertical tooth flanks (142, 144).

4. Device according to one of claims 1 to 3, characterized in that the teeth (138, 154) of the one holding jaw (120, 158) lie opposite the bottom lands (134) of the other holding jaw (120, 158).

5. Device according to one of claims 1 to 4, characterized in that the teeth (154) of the one holding jaw (158) mesh into the teeth (154) of the other holding jaw (158).

6. Device according to one of claims 1 to 5, characterized in that clearances (152) are formed between the teeth (154) of a holding jaw (158).

7. A holding device substantially as herein described with reference to Figures la to ld and Figure 2, or Figures 3a, 3b and 4, of the accompanying drawings.