GB2375151A

GB2375151A - Jaws for compressing a coupling device onto a metal tube

Info

Publication number: GB2375151A
Application number: GB0208824A
Authority: GB
Inventors: Martin Dowling
Original assignee: IMI Yorkshire Fittings Ltd
Current assignee: Aalberts Integrated Piping Systems Ltd
Priority date: 2001-04-18
Filing date: 2002-04-18
Publication date: 2002-11-06
Anticipated expiration: 2022-04-18
Also published as: GB0109469D0; DE10217360A1; GB0208824D0; GB2375151B; DE20206135U1

Abstract

Jaws for compressing a coupling device onto a metal tube comprise two or more arcuate segments 11 arranged to form a substantially circular profile. Adjacent ends of the segments are pivotally connected with one pair of adjacent segment ends 15 being free. A projection 23 is formed on one free end and a complementary recess 24 in the second adjacent free end. In order to prevent radial (and axial) misalignment of the jaws, on application of the operating tool, projections 23 and recess 24 interengage. Pivot pins 16, may be located radially outwardly of the projection 23 and recess 24 to provide abutment points for the application of a jaws operating tool (not shown).

Description

JAWS FOR COMPRESSING TUBE COUPLING DEVICES This invention relates to jaws for compressing a coupling device onto a metal tube to form a fluid-tight joint between the coupling device and the tube.

, Such coupling devices are commonly known as press fittings, and comprise a body housing a sealing member, such as an 0-ring. When the body is compressed round an inserted tube, the O-ring is adapted to seal between the body and the external surface of the tube. Such press fittings are typically used with copper tube in plumbing applications, where the body is also of copper.

The fitting is compressed by jaws of appropriate size for the fitting, which in turn is determined by the outside diameter of the tube. The jaws comprise two or more arcuate segments arranged substantially on a circle open at one circumferential point. Thus, the adjacent ends of the segments are pivotally connected, except for one pair which is left free to allow the jaws to be put around and removed from the fitting. Once round the fitting, the free ends are brought together, closing the circle and compressing the fitting evenly round the tube. The jaws are mounted in a tool for the compression operation. The tool may be manually or power-operated, and acts by levers on appropriate segments to ensure that the correct force is applied.

The term'jaws'as used in this specification, is intended to embrace constructions of two or more arcuate segments pivotally connected as described above, including those for larger tube sizes (over 50mm outside diameter), which are also known in the art as slings.

It can be a problem that the free ends of the jaws move out of alignment radially (and possibly axially) of the tube during the compression operation. Radial misalignment appears to be a particular problem of copper fittings, partly due to the relative softness of the metal, and especially with larger sizes, where the tube is over 50mm outside

diameter, because of the larger forces involved. Radial misalignment of , the free jaw ends means that the compression force is not applied evenly round the circumference of the fitting, so that the joint is not made properly. An imperfect joint may require the tube to be re-cut, and then a new fitting applied. This is extremely inconvenient for the user.

One known compressing tool, shown in US 6 044 681, comprises a plurality of press elements connected to form a substantially circular pressing die. The pressing die is open at one circumferential point where the free ends are adapted so that one end has a wedge-shaped projection and the other free end a complementary wedge-shaped cutout. This arrangement prevents axial misalignment but not radial misalignment.

According to the present invention, jaws for compressing a coupling device onto a metal tube to form a fluid-tight joint between the coupling device and the tube comprise at least two arcuate segments, adjacent ends of the segments being pivotally connected so as to form a substantially circular profile open at one circumferential point where the segments have adjacent free ends, the free ends being adapted to be brought together to compress the coupling device, the segments, at their respective free ends being adapted to interengage so as to keep them in radial alignment when the free ends are brought together.

The interengagement of the free ends ensures that the free ends are guided together and aligned radially (and axially) during compression, so that the joint is made correctly.

Preferably one of the free ends has a projection, and the other has a complementary recess adapted to receive the projection when the free ends are brought together.

The projection may be a circular finger or dowel, and then the recess is a circular bore. However, the projection may be of any appropriate shape, provided that the recess is complementary. For example, the projection may be an extension of the free end of the segment, so that the segments in effect overlap during compression.

Where the projection is a finger or dowel, it is preferably near the inner periphery of the segment, as this provides better guiding when the free ends are brought together.

Where the jaws are mounted in a tool for operation, the tool usually applies the force for compression by a lever system. For larger sizes of the jaws for larger coupling devices, the lever system is preferably a pair of intermediate jaws acting on abutment points at the free ends to bring these together. The abutment points are preferably arranged radially outwardly of the projection where this is a dowel or finger.

An embodiment of the invention is illustrated, by way of example only, in the accompanying drawings, in which: Figure 1 is a longitudinal cross-section through a metal tube and coupling device; Figure 2 is an end view of conventional jaws for compressing the coupling device of Figure 1; and

Figure 3 shows how the jaws of Figure 2 can be radially misaligned in use; and Figure 4 is an end view of jaws according to the invention.

Figure 1 shows a longitudinal section through part of a coupling device 1 adapted to be compressed onto a metal tube 2 to form a fluid-tight joint.

The coupling device 1 comprises a metal body 3 of tubular stepped outline. The outer end 4 of the body 3 is enlarged, and has an annular groove 5 receiving an annular sealing member in the form of an O-ring 6.

A cylindrical intermediate part 7 of the body 3 terminates in a step 8 forming an abutment 9 for the end 2'of the tube 2. The remainder of the coupling device 1 is not shown, but may be a straight connector, a Tconnector or an elbow, and each end will have a similar groove 5 and 0ring 6 to form a joint as required. The tube 2 and the body 3 are each made of copper, and are for use in plumbing and the like installations.

The joint between the coupling device 1 and the tube 2 is made by compressing the enlarged end 4 round the tube 2, so that the O-ring 6 seals between the body 3 and the external surface of the tube 2. The compression operation is performed by jaws 10 as shown in Figure 2 to 4, the jaws 10 being mounted in a tool (not shown) for the purpose.

Figure 2 shows conventional jaws 10, comprising five members; four arcuate segments 11 and a straight member 12, arranged to form a circle open at one circumferential point. The arcuate segments 11 are arranged in pairs, with the straight member 12 between the two pairs at one end, and the open point being opposite the straight member 12, at the other ends. Adjacent ends of the members 11,12 overlap, and are pivotally

connected by pivot pins 13 passing through bores 14 in the members 11, 12.

At the open point, the ends 15 of the adjacent segments 1 are left free. The members 11,12 can therefore pivot to open the jaws 10, allowing a

coupling device 1 and tube 2 to be inserted, and can then be brought , together to complete the circle, and compress the coupling device 1 round the tube 2. The free ends 15 of the segments 11 each have a pivot pin 16, on which a respective arm 17 of an intermediate jaw 18 acts. The arms 17 of the intermediate jaw 18 are pivoted to a cross-member 19, and each has a shorter portion 20 with a recess 21 in which the pivot pin 16 is received, and a longer portion 22 on which the tool (not shown) acts.

The action of the tool moves the longer portions 22 away from each other, thus bringing the shorter portions 20, and the segments 11, towards each other.

It will be appreciated that the radially inner surface of the segments 11 and member 12 is contoured to fit the enlarged outer end 4 of the body 3.

It will also be appreciated that when the tool is operated to bring the free ends 15 towards each other, those ends 15 need to stay aligned, both radially and along the axis of the tube 2, so that the joint is made properly continuously round the circumference of the coupling device 1.

However, in the conventional jaws of Figure 2, there is nothing to prevent misalignment. Radial misalignment is shown in Figure 3. The tube 2 and the body 3 will be compressed more by the right hand segment 11 with the free end than the left hand segment, thus deforming both the tube 2 and the body 3 unevenly so that the joint is not made properly.

The jaws 10 of Figure 4, in accordance with the invention, are designed to stop the misalignment, by interengagement of the free ends 15.

The jaws 10 of Figure 4 are a modification of those of Figure 2, and corresponding reference numerals have been applied to corresponding parts.

In Figure 4, the modification is to the free ends 15 of the segments 11, , where one free end 15 has a circumferentially projecting circular dowel 23, while the other free end 15 has a complementary recess 24, in which the dowel 23 is adapted to be received as the free ends 15 are brought together. It will be noted that the dowel 23 and recess 24 are near the inner peripheral surface of the segments 11, to ensure that the segments 11 are aligned radially (and axially) at the earliest possible moment as the free ends 15 move towards each other. This ensures ease of operation.

The shape of the projection 23 and recess 24 may be modified, for example, in one modification (not shown), the free ends 15 of the segments 11 may be extended, so that they overlap when they are brought together. The projection would then extend along the whole radial surface of the end 15, with a complementary recess in the other segment.

In Figure 4 the jaws 10 are actuated by the intermediate jaw 18, as in Figure 2.

This actuation is particularly appropriate for larger size jaws, that is, those for coupling devices 1 over 50mm outside diameter. For smaller sizes of jaws 10, the intermediate jaw 18 is omitted, and the tool has a lever system acting directly on the segments 11 with the free ends 15, to bring them together. Clearly, the projection and recess according to the invention can be used on jaws actuated in this way as well.

Claims

CLAIMS 1. Jaws for compressing a coupling device onto a metal tube to form a fluid-tight joint between the coupling device and the tube comprise at least two arcuate segments, adjacent ends of the segments being pivotally

connected so as to form a substantially circular profile open at one , circumferential point where the segments have adjacent free ends, the free ends being adapted to be brought together to compress the coupling device, the segments, at their respective free ends, being adapted to interengage so as to keep them in radial alignment when the free ends are brought together.
2. Jaws as claimed in Claim 1, in which the free ends are adapted to interengage in order to keep them in axial alignment when the free ends are brought together.
3. Jaws as claimed in Claim 1, in which one of the free ends has a projection, and the other has a complementary recess adapted to receive the projection when the free ends are brought together.
4. Jaws as claimed in Claim 3, in which the projection is a circular finger, and the recess is a circular bore.
5. Jaws as claimed in Claim 3, in which the projection is an extension of the free end of the segment.
6. Jaws as claimed in Claim 4, in which the finger is near the inner periphery of the segment.

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7. Jaws as claimed in Claim 4 or Claim 6, in which abutment points on which a jaws operating tool is adapted to act are arranged radially outwardly of the finger.
8. Jaws for compressing a coupling device onto a metal tube

substantially as described herein with reference to and as illustrated in i Figure 4 of the accompanying drawings.