Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
A GAS PIPE FOR A VACUUM DRY PUMP AND A METHOD OF MAKING SAME
Document Type and Number:
WIPO Patent Application WO/2013/178983
Kind Code:
A1
Abstract:
A method of forming a pair of spaced raised seal retaining abutments (23, 24) on a tubular metal pipe (22) comprising holding the pipe (22) and applying an axial force to the pipe (22) to simultaneously or sequentially deform the pipe (22) at two axially spaced locations to form said pair of spaced raised seal retaining abutments (23, 24). A metal pipe (22) thus formed is also described, comprising a pair of axially spaced seal retaining abutments (23, 24) formed thereon by deformation of the pipe material.

Inventors:
MANSON DAVID PAUL (GB)
Application Number:
PCT/GB2013/051228
Publication Date:
December 05, 2013
Filing Date:
May 13, 2013
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
EDWARDS LTD (GB)
International Classes:
B21D17/02
Foreign References:
US5890287A1999-04-06
DE4004008C11990-11-29
US5211046A1993-05-18
Attorney, Agent or Firm:
CLARK, Charles Robert (Manor RoyalCrawley, Sussex RH10 9LW, GB)
Download PDF:
Claims:
Claims:

1. A method of forming a pair of spaced raised seal retaining abutments on a tubular metal pipe comprising holding the pipe and applying an axial force to the pipe to simultaneously or sequentially deform the pipe at two axially spaced locations to form said pair of spaced raised seal retaining abutments.

2. A method as claimed in claim 1 comprising applying a circumferential restraining force to the pipe at a prescribed position to allow deformation to occur at a desired axial position.

3. A method as claimed in claim 1 or 2 comprising the steps of applying a first axial force to form a first seal retaining abutment and applying a second axial force to form a second seal retaining abutment axially spaced from the first seal retaining abutment.

4. A method as claimed in claim 3 when dependant on claim 2 comprising re- locating the position of application of the circumferential restraining force between application of the first and second axial forces.

5. A method as claimed in claim 2 in which the circumferential restraining force is effective to form the first and second seal retaining abutments simultaneously on application of the axial force.

6. A tubular metal pipe for a vacuum dry pump formed with a pair of axially spaced raised seal retaining abutments according to the method of any one of claims 1 to 5. A metal pipe for a vacuum dry pump having a pair of axially spaced raised seal retaining abutments formed thereon by deformation of the pipe material.

A method of forming a metal pipe for a vacuum dry pump with a pair of axially spaced raised seal retaining abutments substantially as hereinbefore described with reference to the accompanying drawing of figure 2.

A metal pipe for a vacuum dry pump having a pair of axially spaced raised seal retaining abutments constructed an arranged substantially as hereinbefore described, with reference to, and as illustrated in, Figure 2 of the accompanying drawings.

Description:
A GAS PIPE FOR A VACUUM DRY PUMP AND A METHOD OF MAKING SAME Description:

This invention relates to a gas pipe for a vacuum dry pump and a method of making same.

Nitrogen purge is recommended for many vacuum pum ps used in the flat panel and semiconductor industry for reasons of safety, reliability and performance. The purge is norma lly distributed into the vacuum pump from a gas manifold by means of metal pipes. The or each metal pipe is provided with a machined turret to receive an O-ring seal to provide a quick and leak free method of sealing the pipe or pipes to the gas manifold. The O-ring seal seats in a groove machined in the turret after the machi ned turret has been welded to the meta l piping. The O-ring seal provides the seal between the pipe and a housing for the turret in the manifold. The walls of the groove prevent the O-ring from moving axially along the pipe when it is pushed into, or pulled out of, the manifold housing.

The welding of the turret onto the pipe increases the cost of a pipe assembly and is also a potential leak source should the welding not be of good quality.

A known, automotive derived, quick tube connection consists of a moulded female plastic com ponent into which a formed metal tube is inserted. The ma le metal tube consists of a formed shoulder or bead which is cold formed from the tube material. This formed shoulder acts against a clip within the female plastic coupling to prevent the tube from being removed inadvertently. In this connection an O-ring seal is received in a recess formed in the female plastic part and is engaged by a part of the male metal tube that projects beyond the formed shoulder.

It is an aim of the present invention to reduce the cost of the gas pipe assembly and to avoid the need to weld one component to another.

Accordingly one aspect of the invention provides a metal pipe for a vacuum dry pump having a pair of axially spaced seal retaining abutments formed thereon by deformation of the pipe material.

Another aspect of the invention provides a method of forming a pa i r of spaced seal retaining abutments on a tubular metal pipe comprising holding the pipe and applying an axial force to the pipe to simultaneously or sequentially deform the pipe at two axially spaced locations to form said pair of spaced seal retaining abutments.

A circumferential restraining force may be applied to the pipe at a prescribed position to allow deformation to occur at a desired axial position. Preferably a first axial force is applied to form a first seal retaining abutment followed by a second axial force to form the second seal retaining abutment axially spaced from the first seal retaining abutment. Application of the second axial force may be preceded by re-location of the position of application of the circumferential restraining force.

The circumferential restraining force may be effective to form the first and second seal retaining abutments simultaneously on application of the axial force. The circumferential restraining force may be provided by a die positioned to surround the pipe at a desired location. The method by which the single abutment is formed in the aforementioned prior art may be ada pted to form the two a butments accordi ng to the present invention.

The present invention will now be described further hereinafter, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a partial sectional view of a prior art male and female pipe connector, and

Figure 2 is a side view of a gas pipe embodying the present invention.

Referring firstly to Figure 1, a prior art coupling comprises a moulded plastic female part 1 to receive a male tubular part 2 made of metal. The female part 1 has a housing 4 which is formed with a groove 3 to receive an O-ring seal 5. The end of the housing is provided with resiliently deformable clip means or fingers 7 defining inner abutment faces 9. The fema le part 1 has a through bore and its other end receives a push-on tube 11.

The male metal tubular part 2, has an abutment 13 formed thereon, by cold forming of the metal, at a location spaced from its end and defining a projecting end part 15. In use the projecting end part is inserted into the female housing and makes sealing engagement with the O-ring seal 5 whilst the abutment face 9 engages with face 17 of the abutment 13 to hold the male part in place.

Referring now to Figure 2, there is illustrated the end of a pipe embodying the invention and comprising a tubular metal pipe 22 which has two axially-spaced seal retaining abutments 23, 24 disposed inset from the end 25 of the pipe. The spacing between the two abutments defines a groove 26 for an O-ring (not shown). The two abutments a re formed from the metal of the pipe by deformation of the meta l to cause it to buckle a nd protrude outwa rdly beyond the ci rcumferential surface 27 of the pipe itself. A cold deformation process may be used.

The two abutments 23, 24 serve to inhibit axial displacement of the O-ring

(not shown) as the pipe 22 is inserted into, or pulled out from, a receiving aperture of an appliance to which the pipe is affixed. Absent the abutment 23 the O-ring (not shown) may slide along the pipe 22 during insertion, with the possibility of not forming a proper seal with the inner bore surface of a receiving aperture in to which it is inserted, or forming a seal at an incorrect axial position. Conversely, upon removal of the pipe 22 from its seat, absent the other abutment 24, the O-ring (not shown) may be pulled towards, or off, the end of the pipe 22, leading to delay and possible contamination or da mage to the housi ng d u ri ng a su bseq uent O-ring removal operation.

It will be noted that the outer diameter of the O-ring will be greater than the outer diameter of the pipe 22, which permits the pipe 22 to pivot slightly about the O-ring when seated in a plain bore receiving aperture. As such, the invention affords the possi bility of a llowing some movement of the pipe relative to its receivi ng aperture, without necessarily breaking the seal thus formed, or for the pipe to be angled slightly with respect to the longitudinal axis of its receiving aperture. These aspects of the invention may be particula rly advantageous where, for exam ple, either the pipe 22 or its receiving aperture are subject to vibration, or where it is impractical to ensure exact axial alignment of the pipe 22 relative to the receiving aperture.

One method of forming the aforesaid seal retaining abutments comprises holding the pipe and applying a first axial force to the pipe to cause the side wall to buckle and form a first one of the said abutments and then to apply a second axial force to the pipe to cause the side wall to buckle a second time at a location spaced from the first abutment. Positioning of the deformation may be controlled by the location of a circumferential restraining force applied to the pipe or by introducing a weakness into the pipe periphery.