GB2124952A

GB2124952A - Method and apparatus for cold forming the ends of non-ferrous tubes

Info

Publication number: GB2124952A
Application number: GB08222003A
Authority: GB
Inventors: Christopher Robin Iles
Original assignee: Fogg & Young Engineering Limit
Current assignee: Fogg & Young Engineering Limit
Priority date: 1982-07-30
Filing date: 1982-07-30
Publication date: 1984-02-29
Also published as: GB2124952B

Abstract

A closely fitting plug 6 of elastomeric material is inserted into the tube end. Whilst externally confining 3 the tube T over part of the plug 6, an axial compressive force is applied to the plug 6 sufficient to cause controlled deformation of the plug 6 against the unconfined end part of the tube and thereby achieve a complementary formation of the tube end. In a second operation (Figure 4) the formation is made into a flange perpendicular to the tabs axis. <IMAGE>

Description

SPECIFICATION Method and apparatus for cold forming the ends of non-ferrous tubes This invention relates to a method and apparatus for cold forming the ends of non-ferrous metal tubes and more particularly, but not exclusively, for cold forming a radially outward circumferential flange on such a tube.

Tubes provided with such flanges, which are unperforated, can readily be joined together end to end by inserting a sealing gasket between their opposed flanges and drawing them together using perforated clamping rings with coupling bolts and nuts situated radially outwardly of the flanges. It is essential however that the end flanges of the tubes should be in planes accurately perpendicular to the tube axis if satisfactory sealing is to be achieved.

The present invention has thus been devised with the general object of providing an improved, simple and reliable method and machine for flanging or otherwise outwardly deforming the end of a non-ferrous metal tube.

The invention is hereinafter described by reference to the accompanying drawings wherein Figures 1 to 4 are fragmentary axial section views of a cold forming machine showing successive stages in the cold forming of a radially outward circumferential flange at the end of a non-ferrous metal tube.

Referring now to the drawings the main body (not shown) of the machine supports a main hydraulically operated ram comprised of a cylinder 1 and a piston 2 and a pair of semi-annular jaws 3 which are closable as indicated by the arrows A into clamping engagement with a non-ferrous tube Tat a distance dfrom the tube end which is approximately equivalent to the radial width of the intended circumferential flange. The direction of tube feed is indicated by arrow L.

The main ram piston 2 has a central cavity 2a and constitutes the cylinder of a second ram which has a piston 4 of which the head is slidable in the cavity 2a. The ram piston 2 has a die 5 at one end, this die having a central bore and a frusto conical boss 5a. The piston 4 has a piston rod 4a which passes through the central bore of the die 5 and terminates in a frusto-conical head 4,0. Threaded on the piston rod 4a between the die 5 and the head 4b is a plug 6 made of a hard highly resilient elastomeric material such as a cast urethane elastomer.

A suitable elastomeric material is that which is marketed by Avon Polymers Limited underthe name AVOTHANE and has the following properties: Tensile strength 400 lib per sq. in.

Modulus at 300% extension 1000 Ib per sq. in.

Maximum elongation 500% Tear (90 degress die C) 430 Ib per sq. in.

Resilience (Dunlop tripsometer) 68% I.R.H.D. Hardness 84 + 2 Shore D hardness 300 t 3 Compression set (Method A to degress C) 25% Specific gravity 1.15 At the outset of the forming operation (stage 1) the tube T and the various parts of the machine are in the positions shown in Figure 1. Thus the main ram 1,2 is in a pre-set position, the plug 6 is wholly relaxed, the tube T is clamped at the correct distance dfrom its end and the radially outer part of the die 5 engages the end of the tube T.

Figure 2 shows stage 2 of the forming operation. A low hydraulic pressure prevails in the left end of the main ram cylinder 1 and by increasing hydraulic pressure at the right hand end of the cavity 2a a tensile load S applied to the head 4b has caused the resilient plug 6 to be compressed between the head 4b and the die 5 so as to undergo deformation which in turn causes flaring of the end of the tube T.

Figure 3 shows stage 3 where the machine parts and the plug 6 have been allowed to resume their stage 1 positions.

Figure 4shows stage 4where an increased hydraulic pressure in the main ram cylinder 1 and resultant movement of the piston 2 has caused the die 5 to engage and highly load the flared end of the tube T whilst the resilient plug 6 is compressed against the die 5 dueto the continuing tensile load applied to the head 4,0.

The plug 6 accordingly holds or stabilises the bore of the tube and applies a radial internal load to support the radial junction between the tube and its flared end part whilst the latter is converted into a radial outward flange in a plane perpendicular to the tube axis.

In a final stage 5 - not illustrated - the hydraulic pressures are lowered so that the resilient plug 6 resumes its normal undeformed shape, the semi-annular jaws 3 are withdrawn and the now flanged tube is removed.

Obviously if a flared tube end only is required stage 4 becomes superfluous.

The most common non-ferrous metal tubes which could be treated by the above-described method are as follows: External Wall Diameter Thickness Approx. Theoretical Weights kglm mm mm YORCALBRO KUNIFER 10 44.5 1.5 1.69 1.81 57 1.5 2.18 2.33 76.1 2.0 3.88 4.15 88.9 2.5 5.66 6.05 108 2.5 6.91 7.39 133 2.5 8.55 9.13 159 2.5 10.25 10.95 193.7 3.0 14.99 16.02 219.1 3.0 16.99 18.15 Yorcalbro (Trade Mark) consists of Cu 76 wt.%, Al 2 wt.%, As 0.04 wt.%, remainder Zn. Kunifer 10 (Trade Mark) consists of Ni 10 wt.%, Fe 1.7 wt.%, Mn 1%, remainder Cu. Copper tubes and Kunifer 30 (Ni 30 wt.%, Fe 0.7 wt.%, Mn 0.8 wt.%, remainder Cu) tubes are also suitable.

Claims

1. A method of cold forming the end of a non-ferrous metal tube which comprises inserting into the tube end a closely fitting plug of elastomeric material and then whilst externally confining the tube over part of the plug applying by means of a die an axial compressive force to the plug sufficient to cause controlled deformation of the plug against the unconfined end part of the tube and thereby achieve a complementary formation of the tube end.

2. A method of cold forming a radially outward circumferential flange on the end of a non-ferrous metal tube which comprises inserting into the tube end a closely fitting plug of elastomeric material and then whilst externally confining the tube over part of the plug, applying as a first step by means of a die an axial compressive force to the plug sufficient to cause controlled outward deformation of the plug and the tube end and thereafter, as a second step, applying direct pressure through the die to the tube end whilst compressing the plug so that the plug gives support to the junction of the thus finally formed flange and the tube.

3. Apparatus for cold forming the end of a non-ferrous metal tube comprising a main frame, means on the main frame for clamping the tube at a predetermined distance from the tube end, a first hydraulic ram mounted on the frame opposite the tube end, a second hydraulic ram co-axially mounted relative to the first ram and a plug of elastomeric material mounted between a die associated with the piston of the first ram and a head at the end of a piston rod of the second ram, the diameter of the plug being such that the plug fits closely within an unsupported end part of the tube and means for controlling the hydraulic pressures in the cylinders of the first and second rams whereby the plug is compressible between the die and the head so as to deform in a radially outward direction under the control of the die against the said unsupported end part of the tube to cause a complementary but permanent deformation thereof.

4. Apparatus as set forth in claim 1 wherein the control means is operable also to cause a radially outward part of the face of the die directly to engage the tube end for the purpose of finally deforming the same whilst the plug supports the interior of the tube end part.

5. A method of cold forming the end of a non-ferrous metal tube substantially as hereinbefore described with reference to the accompanying drawings.

6. Apparatus for cold forming the end of a non-ferrous metal tube and constructed substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.