GB2118583A

GB2118583A - Connecting cable ends

Info

Publication number: GB2118583A
Application number: GB08308001A
Authority: GB
Inventors: Gustaaf Stipdonk
Original assignee: CA MINISTER ENERGY; Hudson Bay Oil & Gas Co; Petro Canada Exploration Inc; Esso Resources Canada Ltd; Pancanadian Petroleum Ltd; Alberta Energy Co Ltd; Hudsons Bay Oil and Gas Co Ltd; Gulf Canada Ltd; Canada Cities Service Ltd; Petrofina Canada Inc
Current assignee: CA MINISTER ENERGY; Hudson Bay Oil & Gas Co; Petro Canada Exploration Inc; Hudsons Bay Oil and Gas Co Ltd; Gulf Canada Ltd; Canada Cities Service Ltd; Imperial Oil Resources Ltd; Petro Canada Enterprises Inc; Ovintiv Canada ULC
Priority date: 1982-03-23
Filing date: 1983-03-23
Publication date: 1983-11-02
Also published as: AU545939B2; GB8308001D0; CA1190030A; JPS58203213A; GB2118583B; AU1264083A; DE3310224C2; DE3310224A1

Abstract

A steel connector 1 for joining the steel cable ends 2 of a conveyor belt comprises a pair of tubular sleeves one of which is slipped onto each cable end 2. Each sleeve 4 has a bore 5 having an inner section 5a of reduced diameter relative to the outer section 5b. The cable end 2 is expanded radially, by driving a cone 6 into its end, and then the expanded end 2 is wedged tightly into the inner section 5a of the sleeve to fix them together. Bridging means 9 are threaded into the outer sections of the two sleeves 4 to hold them together in lineal alignment. The bridging 9 means is operative to permit the sleeves to flex relative to each other, and to pull the sleeves together to adjust cable tension. <IMAGE>

Description

SPECIFICATION Connecting cable ends This invention relates to the connecting of cable ends, and is concerned particularly although not exclusively with connecting cable ends in a conveyor belt.

The invention has been developed in connection with very large conveyor belts used in Alberta, Canada, to transport tar sand from a mine to a bitumen recovery plant. Therefore, the invention and the problems which it seeks to alleviate are described below with respect to this particular application; however, it is to be understood that the invention is not limited to said application.

The tar sand conveyor belts are large and operate in demanding conditions. They commonly have a width of 60 inches and may stretch in length over a distance of several hundred feet or several miles, depending on their role in the system. In use, a stream of tar sand is continuously dropped onto the endless belt at the loading point, to form a furrow about 55 inches in width and 1 2 inches in height. The stream usually includes large boulders and, in winter, chunks of frozen tar sand. Some of these pieces weigh hundreds or thousand or pounds and, in some cases, they are dropped onto the belt from a height of several feet. As a result, the belts frequently experience deep cuts and impact stress. In addition, the hydrocarbons present in the tar sand tend to permeate the material of the belt and cause deterioration.

In structure, each belt comprises a bottom layer of rubber, a series of steel cables laid lengthwise in parallel, closely spaced arrangement on top of the bottom layer, and a top layer of rubber laid over the cables. The three components are bonded together by a middle layer of vulcanised tie-gum rubber.

Each conveyor is formed of one or more supported lengths of belt. In the case of a conveyor made using only a single length of belt, the ends of the length are joined to form an endless belt running on idlers and around two end rolls. In the case of a longer conveyor, the ends of several lengths are joined in sequence in end to end relation to form the endless belt. Furthermore, when a belt fails, it is usual to cut out a short length at the failure point and splice in a substitute length of new material. So each belt includes one or more joints or splices along its length.

As previously mentioned, the belts are subjected to stress and chemical attack-thus they periodically fail. These failures commonly occur at the splices.

Heretofore the conventional preactice for joining the belt ends involved the following.

The top layer of rubber would be cut away at the splice zone to expose the cable ends.

These ends would be scrupulously cleaned.

An end portion of the bottom layer would be cut away. Then the bottom layer ends would be brought into abutment and the cable ends laid in side-by-side overlapping relation. Tiegum would then be applied to cover the splice zone, a section of top rubber would be laid on, and the whole would be vulvanized.

It will be perceived from the foregoing that the connection means between the steel cable ends in a joint of this kind is only the tie-gum rubber, supported by the top and bottom layers of rubber. As mentioned, this is where failure occurs.

The cost is high for repairing such a failure.

The failure point is frequently high off the ground. The weather is often cold. Thus it is frequently necessary to first build a heated shelter high off the ground over the splice area. The splicing procedure itself is slow going and labour intensive. But most important, the belt is out of operation for 2 or 3 days. In the case of a 125,000 BOPD synthetic crude plant, the shutdown of a belt can reduce the volume of feed to the plant by 25%, which translates into a loss of many thousands of dollare per day.

One solution to this problem would be to develop a mechanical connector to join the cable ends. Such a connector preferably should have the following characteristics: (1) a high order of strength; (2) compactness, as the closely spaced cables each will include such a connec tor at the splice and they must all fit without problem within a limited area; (3) a limited degree of flexibility, to enable the connector to negotiate the passage over the end rolls without serious prob lems; and (4) lengthwise adjustability to permit the cables to be pre-tensioned to about the same extent.

In one aspect, the invention provides, in combination: a pair of cable ends to be interconnected; and connector means interconnecting said cable ends, said connector means comprising: a pair of sleeves, each such sleeve forming a bore extending therethrough, said bore having an outer section and an inner section of reduced cross-sectional area relative to the outer section, each such sleeve being slipped on one of the cable ends; a wedge member embedded in each cable end so as to expand its cross-sectional area, whereby said expanded end is small enough to enter said outer section of bore but is too large to pass through said inner section of bore; each said expanded cable end being drawn tightly into said inner section of the sleeve so as to fix together each cable end and its associated sleeve; and bridging means, associated with the outer ends of the sleeves, for interconnecting said sleeves, said bridging means being operative to hold said sleeves together in substantially aligned lineal relation while permitting of limited movement of one sleeve relative to the other whereby the connector means may flex when passing around a conveyor drum.

In another aspect, the invention provides a method for connecting two ends of steel cable. the method comprising the steps of slipping a tubular sleeve over each cable end, said sleeve having a bore which has an inner section of reduced cross-sectional area relative to its outer section; expanding the cross-sectional area of each such cable end; drawing each such sleeve outwardly on its associated cable end. to tightly wedge the expanded cable end into the inner section of the sleeve; and joining the sleeves with bridging means for holding the sleeves together in substantially linear alignment.

For a better understanding of the of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figures la, ib and ic are top plan views showing the two ends of a conveyor belt with a top rubber layer removed and a bottom rubber layer not shown, and pairs of cable ends to be spliced are shown: in staggered spaced-apart arrangment in Fig. 1a, with sleeves in place in Fig. 1 b, and with bridging means in place in Fig. 1 c; Figure 2 is a perspective exploded view showing the connector; and Figure 3 is a side sectional view showing a connector joining two cable ends.

A connector 1 is shown in the Figures connecting a pair of cable ends 2, which form part of a conveyor belt 3.

The connector 1 comprises a pair of tubular sleeves 4, each sleeve 4 being associated with one of the cable ends 2. Each such sleeve 4 has a longitudinal bore 5 extending therethrough. The bore 5 consists of an inner section 5a and an outer section 5b. The inner section 5a is of reduced cross-sectional area relative to the outer section 5b. More particularly, the inner section 5a is tapered in configuration, while the non-reduced outer section 5b is cylindrical. The diameter of the inner section 5a is of sufficient size so that the sleeve 4 slips easily onto the cable end 2.

A wedge member, specifically a cone 6, is embedded in each cable end 2 to expand it, so that said expanded cable end is too large to pass through the tapered inner section 5a of the bore 5 but is still capable of passing through the non-reduced section 5b.

The cable end 2 is drawn into its associated sleeve 4 to wedge the sxpand,il cable end 2 tightly into the tapered inner section 5a of the bore 5. Each sleeve 4 is thus fixed on its cable end 2.

The outer end 7 of each sleeve 4 is inter nally threaded. An externally threaded lock screw 8 is screwed deep into the outer section 5b of the bore 5 to abut the cone 6 and prevent it being extruded from the cable end.

A sleeve interconnecting or bridging assembly 9 is provided to join the two sleeves 4.

The assembly 9 includes a shaft 10 threaded at its ends. Rings 11 are threaded onto the shaft ends to provide enlarged heads. The rear shoulder 1 2 of each shaft ring 11 is arcuately formed, as shown. The shaft 10 extends into each of the outer sections 5b of the sleeve bores 5. An externally threaded sleeve lock ring 1 3 is screwed into each bore outer section 5b to trap the relevant shaft head 11. The inner shoulder 14 of each sleeve lock ring 1 3 is arcuately shaped, so as to mate with the shoulder 1 2 of the head 11.

Since the outside diameter of the shaft 10 is slightly less than the internal diameter of the sleeve lock ring 13, the sleeves 4 may move universally relative to each other. The degree of movement is limited, but is sufficient to ensure that the connector 1 may flex when passing around the conveyor drums.

The illustrated arrangement has several advantages. Firstly, a steel bond between cable ends now replaces the prior art rubber bond, with consequent improvement with respect to strength and resistance to chemical attack.

Secondly, the connector takes up little space, so that a multiplicity of side-by-side pairs of cable ends can be connected within the spatial confines of the belt. Thirdly, the connector has a degree of flexibility in it which allows it to pass around the conveyor drums without cutting into the rubber of the belt. And finally, the connector comprises means for drawing its associated cable ends together to a sufficient extent to enable the cables to be pulled to approximately the same tension.

While one specific embodiment of the invention has been shown in the Figures and described above, the scope of the invention is defined by the following claims.

Claims

1. In combination: a pair of cable ends to be interconnected; and connector means interconnecting said cable ends, said connector means comprising: a pair of sleeves, each such sleeve forming a bore extending therethrough, said bore having an outer section and an inner section of reduced cross-sectional area relative to the outer section, each such sleeve being slipped on one of the cable ends; a wedge member embedded in each cable end so as to expand its cross-sectional area, whereby said expanded end is small enough to enter said outer section of bore but is too large to pass through said inner section of bore; each said expanded cable end being drawn tightly into said inner section of the sleeve so as to fix together each cable end and its associated sleeve; and bridging means, associated with the outer ends of the sleeves, said bridging means being operative to hold said sleeves together in substantially aligned lineal relation while permitting of limited movement of one sleeve relative to the other whereby the connector means may flex when passing around a conveyor drum.

2. A combination according to Claim 1, further comprising a conveyor belt having a plurality of pairs of cable ends interconnected by connector means as aforesaid.

3. A combination according to Claim 1 or 2, wherein: the outer end of each sleeve is internally threaded; and the bridging means comprises: a shaft having an enlarged head at each end, said shaft having one end extending into each of the threaded outer bore sections; an externally threaded ring screwed into each sleeve bore outer section so as to restrain the contained shaft head against outward displacement, whereby one or both rings may be screwed further inwardly to draw the associated cable ends together; each shaft head and associated ring having rounded mating shoulders which permit of said limited movement.

4. A combination according to Claim 1, 2 or 3, wherein the inner section of the bore is tapered and the wedge member is conical in shape.

5. A combination according to Claim 1, 2, 3 or 4, comprising means, associated with each sleeve, for locking the wedge member in place in the cable end.

6. A method for connecting two ends of steel cable comprising: slipping a tubular sleeve over each cable end, said sleeve having a bore which has an inner section of reduced cross-sectional area relative to its outer section; expanding the cross-sectional area of each such cable end; drawing each sleeve outwardly on its associated cable end, to tightly wedge the expanded cable end into the inner section of the sleeve; and joining the sleeves with bridging means for holding the sleeves together in substantially linear alignment.

7. A method according to Claim 6, wherein the two ends of steel cable are in an endless conveyor belt having a plurality of such cable end pairs, and the method includes the step of adjusting said bridging means to pull the sleeves together to obtain a tension generally the same as that obtained in the other cable end pairs.

8. Means for connecting cable ends, substantially as hereinbefore described with reference to the accompanying drawings.

9. A method of connecting cable ends, substantially as hereinbefore described.

1 0. The connector means of Claim 1, 2, 3, 4 or 5.