GB2110976A

GB2110976A - Clamping a pipe internally

Info

Publication number: GB2110976A
Application number: GB08232003A
Authority: GB
Inventors: Eduard Edmeier; Heinz Schott
Original assignee: MAN Maschinenfabrik Augsburg Nuernberg AG
Current assignee: MAN AG
Priority date: 1981-12-02
Filing date: 1982-11-09
Publication date: 1983-06-29
Also published as: DE3147688A1; GB2110976B; ATA365982A; AT380414B; IT1148688B; IT8249603A0; FR2517225A1

Abstract

A quick release device has a collet 3 for insertion in the end of the pipe and expandable by means of a tapered mandrel 5 which is movable in a bore of the collet when a holder 2 for the collet and a thrust body 1 to which the mandrel is attached are moved toward each other against a biasing force. The end of the collet has circumferentially spaced longitudinal slots communicating with the bore to facilitate expansion of the collet. The device has a particular advantage when used in pipe bending apparatus since by virtue of clamping the pipe internally a bend may be formed such closer to the end of the pipe than would otherwise be possible. <IMAGE>

Description

SPECIFICATION Quick release pipe clamping device This invention relates to a quick-release device for clamping a pipe internally, more particularly such a device in or for pipe bending apparatus.

With conventional clamping devices the pipe end is clamped externally, and a bend can be produced neither over the actual clamping section nor over an additional section, which varies with the minimum distance of the clamping device from the bending roller, so that it remains straight and generally requires cutting off after the bending process. This causes a loss in terms of material and labour.

The present invention aims to provide a clamping device in which the length of pipe lost as a result of the bending is notably reduced as compared with conventional arrangements, if not eliminated altogether.

According to the present invention, we propose a quick-release device for clamping a pipe internally and more particularly, though not exclusively, such a device in or for pipe bending apparatus, comprising a holder carrying an expandable collet or plug for insertion in the end of the pipe and a thrust body carrying a mandrel received within a bore in the collet or plug, the holder and the body being relatively movable preferably against a biasing force, such that the mandrel moves within the bore, and the shape of the mandrel and the bore being such as to cause expansion of the plug or collet thereby clamping the pipe, as the mandrel moves in the bore.

When, as is preferred, the plug or collet is formed of a relatively stiff material, circumferentially spaced longitudinal slots are formed in the free end of the mandrel to enable the collet to expand sufficiently to clamp the pipe.

In a preferred embodiment, both the mandrel and the bore preferably taper toward the free end of the expandable collet or plug, the holder and the thrust body being relatively axially movable toward each other against the biasing force which is preferably provided by a spring.

Also in the preferred embodiment, the expandable collet or plug is stepped diametrally to provide an abutment for the end of the pipe to be bent.

Further, the expanding collet is screwed at its inner end into the holder and is secured by means of a screw, and the expanding mandrel is screwed into the thrust body and secured by means of a check nut. The thrust body optionally carries several projecting pins slideably engaging in axial holes in the holder. The invention also includes pipe bending apparatus comprising a quick release device according to the above proposal.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings of which: Figure 'illustrates a conventional quick-release clamping device in pipe bending apparatus; Figure 2 illustrates a quick-release clamping device of the present invention; and Figure 3 is a cross-section of the device shown in Figure 2.

With reference now to Figure 1, one end 9a of the pipe 9 to be bent is externally clamped over a section 11 in a clamping device 10. The bending radius of the pipe is here determined by a bending roller 11.

Between this roller and the clamping device the pipe bending facility is a minimum distance 12. The total length of pipe that cannot be bent, therefore, is 11+12.

With reference to Figure 2 the pipe end is internally clamped over the same length 11 by means of a clamping device 10' according to the present invention. Between the device and the bending roller 11, the minimum distance 12' is here substantially reduced, as compared with the conventional device of Figure 1.

As shown in Figure 3, the clamping device includes a bolt-shaped expanding collet 3 having several circumferentially spaced longitudinal slots 3a at its free end. This end carries a diametrally stepped abutment surface 3c seated over which is one end of the pipe to be bent. The expanding collet is screwed at its inner end into a holder 2 and secured by means of a screw 8. A thrust body 1 is arranged within the pipe bending facility for axial movement towards the holder against the pressure of an intervening spring 6, where several axially projecting pins 7 slideably engage in axial holes 2a in the holder. Screwed into the thrust body and secured by a check nut 4 is an expanding mandrel 5.

The expanding mandrel has a conically tapering end and is slideably supported in a suitably shaped central hole 3b of the collet.

Axial movement of the thrust body, therefore, causes the outer end of the expanding member to be expanded and the pipe end, thus to be clamped.

1. A quick release device for clamping a pipe internally, comprising a holder carrying an expandable collet or plug for insertion in the end of the pipe and a thrust body carrying a mandrel received within a bore in the collet or plug, the holder and the body being relatively movable such that the mandrel moves within the bore, and the shape of the mandrel and the bore being such as to cause expansion of the plug or collet thereby clamping the pipe, as the mandrel moves in the bore.

2. A device according to claim 1 wherein both the mandrel and the bore taper toward the free end of the collet.

3. A device according to claim 1 or claim 2 wherein the holder and the thrust body are relatively movable toward each other against a biasing force.

4. A device according to any one of the preceding claims wherein the expandable collet or plug has at its free end, circumferentially spaced slots communicating with the bore.

5. A quick release device for clamping a pipe internally comprising a holder carrying an expandable collet for insertion in the end of the pipe and having at its free end circumferentially spaced slots,

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Quick release pipe clamping device This invention relates to a quick-release device for clamping a pipe internally, more particularly such a device in or for pipe bending apparatus. With conventional clamping devices the pipe end is clamped externally, and a bend can be produced neither over the actual clamping section nor over an additional section, which varies with the minimum distance of the clamping device from the bending roller, so that it remains straight and generally requires cutting off after the bending process. This causes a loss in terms of material and labour. The present invention aims to provide a clamping device in which the length of pipe lost as a result of the bending is notably reduced as compared with conventional arrangements, if not eliminated altogether. According to the present invention, we propose a quick-release device for clamping a pipe internally and more particularly, though not exclusively, such a device in or for pipe bending apparatus, comprising a holder carrying an expandable collet or plug for insertion in the end of the pipe and a thrust body carrying a mandrel received within a bore in the collet or plug, the holder and the body being relatively movable preferably against a biasing force, such that the mandrel moves within the bore, and the shape of the mandrel and the bore being such as to cause expansion of the plug or collet thereby clamping the pipe, as the mandrel moves in the bore. When, as is preferred, the plug or collet is formed of a relatively stiff material, circumferentially spaced longitudinal slots are formed in the free end of the mandrel to enable the collet to expand sufficiently to clamp the pipe. In a preferred embodiment, both the mandrel and the bore preferably taper toward the free end of the expandable collet or plug, the holder and the thrust body being relatively axially movable toward each other against the biasing force which is preferably provided by a spring. Also in the preferred embodiment, the expandable collet or plug is stepped diametrally to provide an abutment for the end of the pipe to be bent. Further, the expanding collet is screwed at its inner end into the holder and is secured by means of a screw, and the expanding mandrel is screwed into the thrust body and secured by means of a check nut. The thrust body optionally carries several projecting pins slideably engaging in axial holes in the holder. The invention also includes pipe bending apparatus comprising a quick release device according to the above proposal. An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings of which: Figure 'illustrates a conventional quick-release clamping device in pipe bending apparatus; Figure 2 illustrates a quick-release clamping device of the present invention; and Figure 3 is a cross-section of the device shown in Figure 2. With reference now to Figure 1, one end 9a of the pipe 9 to be bent is externally clamped over a section 11 in a clamping device 10. The bending radius of the pipe is here determined by a bending roller 11. Between this roller and the clamping device the pipe bending facility is a minimum distance 12. The total length of pipe that cannot be bent, therefore, is 11+12. With reference to Figure 2 the pipe end is internally clamped over the same length 11 by means of a clamping device 10' according to the present invention. Between the device and the bending roller 11, the minimum distance 12' is here substantially reduced, as compared with the conventional device of Figure 1. As shown in Figure 3, the clamping device includes a bolt-shaped expanding collet 3 having several circumferentially spaced longitudinal slots 3a at its free end. This end carries a diametrally stepped abutment surface 3c seated over which is one end of the pipe to be bent. The expanding collet is screwed at its inner end into a holder 2 and secured by means of a screw 8. A thrust body 1 is arranged within the pipe bending facility for axial movement towards the holder against the pressure of an intervening spring 6, where several axially projecting pins 7 slideably engage in axial holes 2a in the holder. Screwed into the thrust body and secured by a check nut 4 is an expanding mandrel 5. The expanding mandrel has a conically tapering end and is slideably supported in a suitably shaped central hole 3b of the collet. Axial movement of the thrust body, therefore, causes the outer end of the expanding member to be expanded and the pipe end, thus to be clamped. CLAIMS

5. A quick release device for clamping a pipe internally comprising a holder carrying an expandable collet for insertion in the end of the pipe and having at its free end circumferentially spaced slots, a thrust body carrying a mandrel having a tapered surface and received within a tapered bore in the collet, the holder and the thrust body being relatively axially movable against a biasing force such that the mandrel moves within the bore causing expansion of the collet, so as in use to clamp the pipe.

6. A device according to any one of the preceding claims, wherein the expandable collet or plug is stepped to provide an abutment for the end of the pipe.

7. A device according to any one of the preceding claims, wherein the expanding collet is screwed at its inner end into the holder and is secured using a screw.

8. A device according to any one of the preceding claims wherein the expanding mandrel is screwed into the thrust body and is secured by means of a check nut.

9. A device according to any one of the preceding claims wherein the thrust body carries several axially projecting pins slideably engaging in axial holes in the holder.

10. A quick release device for clamping a pipe internally constructed and arranged substantially as hereinbefore described with reference to and as illustrated in Figures 2 and 3 of the accompanying drawings.

11. Pipe bending apparatus comprising a quick release clamping device according to any one of the preceding claims.