GB1595251A

GB1595251A - Conduits

Info

Publication number: GB1595251A
Application number: GB2345/78A
Authority: GB
Original assignee: American Chain and Cable Co Inc
Current assignee: FKI Industries Inc
Priority date: 1977-01-21
Filing date: 1978-01-20
Publication date: 1981-08-12
Also published as: FR2378124B1; BR7800351A; FR2378124A1; PT67559B; MX145525A; CA1098421A; JPS53108157A; ES466213A1; PT67559A; DE2802127C2; DE2802127A1; JPS6117645B2

Description

(54) IMPROVEMENTS IN OR RELATING TO CONDUITS (71) We, AMERICAN CHAIN & CABLE COMPANY, INC., a corporation organised under the laws of the State of New York, of 929 Connecticut Avenue, Bridgeport, Connecticut 06602, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- Cables such as are widely used in the actuation of automotive parking brakes and clutches, and have other applications in industrial, marine and aircraft contexts, commonly have a central core that can reciprocate axially within a conduit. The conduit may be formed from spirally wound wire, or a spirally wound wire may form the outer of several concentric layers. If such a conduit is cut from a continuous length, then there is the risk that the wire will become unwound in the region of the cut. This, in itself, can be unsatisfactory but if it is then necessary to provide that conduit with a termination member, there is the additional problem of capturing the "frayed" wire or wires within the termination member. The present invention arose from a consideration of this problem.

According to the present invention, there is provided a method of forming a unit comprising a conduit formed from spirally wound wire, or from two or more layers of which the outer is formed from spirally wound wire, and a termination member fix ed~around an end portion of the conduit and holding the parts of the spirally wound wire that lie between the ends of the termination member in position relatively to each other, in which method the end portion, and an extension of the conduit to which the end portion is integrally connected is held within a mould, thermoplastic material is injected into the mould to form the termination member, and, after the thermoplastic material has set, a cut is made to separate the conduit from the integral extension.

Thus, the parts of the wire are held in position by the termination member without the provision of additional means for the purpose.

The moulding operation may form only a single termination member, but it may be arranged that two are formed simultaneously by the single moulding operation, and the two are then separated by the cut that separates the conduit from its extension, the extension being included with the second termination member in another unit.

The spirally wound wire may provide widely spaced convolutions overlying another layer of more closely spaced convolutions, and the termination may serve to hold turns of both layers in position relatively to each other. By the moulding process, the thermoplastic material may be forced closely into the spaces between adjacent convolutions, and so provide a seal between them.

The termination member may have a length and flexibility that serve to distribute vibration and bending stresses; in particular, it may be so designed that when it is intended to mate within another fitting, the stresses are not concentrated at the entry point to the fitting.

By way of example, an embodiment of the present invention will now be described with reference to the accompanying drawings in: Figures 1A and 1B are side and end views of a unit comprising a conduit and a termination member fixed around and end portion of the conduit; Figure 2 is a schematic view in axial section of moulding apparatus by which the termination member may be formed; and Figure 3 is a view in side elevation of the product that is yielded by the moulded apparatus illustrated in Figure 2.

The unit illustrated in Figures 1A and 1B includes a helical wire flexible conduit, of which a part is indicated at 10, and a cylindrical plastic termination member 11 moulded on to the end portion of the conduit 10. The conduit 10 comprises an inner, helically wound, core 12 of flat wire, an intermediate layer 13 of helically wound contiguous wires coiled with a relatively long pitch, and an outer layer 14 of helically wound turns which act to retain the wires of the intermediate layer 13 in position. The conduit 10 may act as the sleeve through which runs an inner element by which tensile compressive forces may be transmitted to a location remote from an operator. The conduit and inner element thus form a cable such as is commonly used in the actuation of automatic parking brakes and clutches. The moulded plastic termination member 11 has a cylindrical outer surface and in internal surface which intimately conforms to the exposed surface of the part of conduit 10 that lies between the ends of the termination member 11. The plastic not only circumscribes, and holds in position relatively to each other, the widely spaced turns of the outer layer 14 but also penetrates into the interstices between adjacent turns of intermediate helix 13. This not only positions the turns of helix 13 but provides enhanced resistance to the passage of water or other corrosive liquids between the ends of the turns. Conduit 10 may be composed of galvanised steel wire, and member 11 can be moulded from such flexible thermoplastic materials as nylon, acetal resin, or polyethylene.

The length of termination member 11 is more than twice its diameter and is such that the member will extend about a quarter of an inch beyond the end of a fitting into which it is to be inserted to act as a connection for the conduit. Such a length tends to distribute vibration stresses along the part of the conduit that is covered by the termination member and thereby relieve the concentration of stresses at the exit end of the member.

The unit that has been described is formed by use of the moulding apparatus that is shown in Figure 2, which provides a die 20, by which a pair of cylindrical plastic termination members may be moulded simultaneously one on the end of one conduit and the other on the adjacent end of another conduit that, initially, forms an integral extension of the first conduit. The die comprises two mating halves 21 and 22 defining a cylindrical cavity 23A, 23B, and 23C. The termination member on the end of one conduit is formed within 23A and part of 23B whilst the termination member on the other conduit is formed within 23C and part of 23B, a cut being made through the part 23B to separate the termination members from each other. The ends 24 and 25 of the die are open to permit the two integral conduits to extend through the mould, and, when the conduits are in position, the ends of the cavity are closed by sealing collars 27.

One of the halves 21 contains an aperture 28 through which fluid thermoplastic material may be injected into the cavity. A particular suitable material is a nylon copolymer that may be moulded at a temperature of 460 -500 F. and at a maximum pressure of about 215 pounds per square inch. Injection time for such material is about three seconds, and cycle time is about ten seconds.

To use the apparatus 20 the halves 21 and 22 are separated and the two integrally connected conduits are brought into position, with the sealing collars 27 lying at the ends of the mould. The mould is then closed around the conduits with the resilient end members simultaneously sealing the ends and serving to centre the ends of the conduits. A conventional injection head (not shown) is inserted into apertures 28, and fluid plastic is injected into the cavity 23A, 23B, 23C into intimate contact with the exposed surface of the outer and intermediate layers 14 and 13 and with the surfaces of the cylindrical cavities 23A, 23B and 23C.

After the plastic has cooled from the fluid state, the halves of the die are separated and the conduits, still integrally connected to each other, with the moulding formed around them are removed. A cut is then made through the moulding to separate the conduits from each other to result in two units each comprising a conduit having a termination member fixed around its end portion.

The immediate product of the moulding operation is illustrated in Figure 3 which shows the structure 30 moulded around the end portion of the conduits 10 that are still integrally connected to each other. The structure 30 includes cylindrical portions 31A, 31B, and 31C corresponding to the parts 23A, 23B and 23C of the cavity of the mould die 20. This structure is conveniently cut into two at the reduced diameter portion 31B using a cut-off wheel, leaving two conduit ends terminated by termination members 11A and 11C, as shown in Figure 1.

Since the cut is made through a section of reduced diameter, the bar resulting from the abrasive cut-off is small.

It will be noticed that during and throughout the moulding operation, the two conduits are integrally connected together so that one forms an integral extension of the other. Thus, each is effective to hold the strands of the other in their desired relative position. The conduits are not separated from each other until the moulding has set and becomes effective to hold the turns in position relatively to each other. In the embodiment described, each terminating member is effective to hold in position not only the turn of the outer layer 14 but also the turn of the next inner layer 13.

In typical use of a unit formed as described, the termination member is inserted into a fitting, such as a screw machine or stamped bushing which is crimped down onto the termination member. The crimping operation further enhances the liquid seal by forcefully biasing the resilient plastic material into intimate contact with the wires of intermediate helix 13.

WHAT WE CLAIM IS: 1. A method of forming a unit comprising a conduit formed from spirally wound wire, or from two or more layers of which the outer is formed from spirally wound wire, and a termination member fixed around an end portion of the conduit and holding the parts of the spirally wound wire that lie between the ends of the termination member in position relatively to each other, in which method the end portion, and an extension of the conduit to which the end portion is integrally connected, is held within a mould, thermoplastic material is injected into the mould to form the termination member, and, after the thermoplastic material has set, a cut is made to separate the conduit from the integral extension.

2. A method as claimed in Claim 1 in which, simultaneously with the formation of the termination member, there is formed an integral extension of the termination member that embraces the integral extension of the conduit, and the cut that separates the conduit from its integral extension also separates the termination member from its integral extension.

3. A method as claimed in Claim 2 in which the integral extension of the termination member forms another termination member, and the integral extension of the conduit forms another conduit that, with the other termination member, forms another unit as defined in Claim 1.

4. A method as claimed in either of claims 2 and 3 in which, immediately on each side of the cut, the thermoplastic material has a diameter less than that over the major part of its length.

5. A method as claimed in any of the preceding claims in which the wire forms and outer layer, the convolutions of the outer layer are widely spaced, the layer on which that layer is wound is formed from wire wound in closely spaced convolutions, and the or each termination member holds in position the parts of the spirally wound wire of both layers that lie between the ends of the termination member.

6. A method as claimed in any of the preceding claims in which the, or each, termination member has a maximum diameter that is less than half its length.

7. A unit comprising a conduit and a termination member produced by a method as claimed in any of claims 1 to 6.

8. A method of producing a unit comprising a conduit and a termination member substantially as described with reference to, and as illustrated by, the Figures of the accompanying drawing.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. crimped down onto the termination member. The crimping operation further enhances the liquid seal by forcefully biasing the resilient plastic material into intimate contact with the wires of intermediate helix 13. WHAT WE CLAIM IS:

1. A method of forming a unit comprising a conduit formed from spirally wound wire, or from two or more layers of which the outer is formed from spirally wound wire, and a termination member fixed around an end portion of the conduit and holding the parts of the spirally wound wire that lie between the ends of the termination member in position relatively to each other, in which method the end portion, and an extension of the conduit to which the end portion is integrally connected, is held within a mould, thermoplastic material is injected into the mould to form the termination member, and, after the thermoplastic material has set, a cut is made to separate the conduit from the integral extension.