GB2216829A

GB2216829A - Mineral insulated cable bending tool

Info

Publication number: GB2216829A
Application number: GB8905915A
Authority: GB
Inventors: Leon Fletcher Widdison; Michael Andrew Beard
Original assignee: BICC PLC
Current assignee: Balfour Beatty PLC
Priority date: 1988-03-15
Filing date: 1989-03-15
Publication date: 1989-10-18
Anticipated expiration: 2009-03-15
Also published as: GB2216829B; GB8806150D0; GB8905915D0

Abstract

The tool, for bending a mineral insulated cable into a smooth curve, comprises a table 1 having a flat surface and, mounted on the flat surface, two anvils 2, 5 each of which has a smoothly curved upstanding surface having centres of curvature lying on a line upstanding from the table and which are so spaced apart that the upstanding surfaces of the anvils bound between them a passage 10 which at the narrowest part of its width is equal to the external diameter of a mineral insulated cable which is to be bent. The radii of the smoothly curved upstanding surfaces differ from one another and are greater than or are equal to the minimum radius of a smoothly curved surface around which a mineral insulated cable of said external diameter can be bent without risk of damage to the cable. The anvil 5 has two differing curved surfaces and is replaceably located 9 in a bracket 8 to provide two different width passages 10. <IMAGE>

Description

AN IMPROVED MINERAL INSULATED CABLE BENDING TOOL This invention relates to mineral insulated electric cables, that is to say cables of the kind comprising at least one conductor insulated from a surrounding metal sheath, and where there is more than one conductor from the other conductor or conductors, by compacted mineral insulating powder, usually but not necessarily magnesium oxide.

During installation of mineral insulated electric cable it is frequently required to secure a length of such cable to the substantially flat surface of a wall or to another substantially flat surface in such a way that the cable follows a smooth curve of a diameter such that no damage to the cable is caused.

It is an object of the present invention to provide a simple and inexpensive tool by means of which a length of mineral insulated electric cable can be bent into a smooth curve for attachment to a substantially flat surface.

According to the invention, the bending tool comprises a table having a substantially flat surface and, mounted on said flat surface of the table, two anvils each having a surface upstanding from said table, the upstanding surface of at least one of the anvils being smoothly curved and having centres of curvature lying on a line upstanding from said table, which anvils are so transversely spaced apart that said upstanding surfaces of the anvils bound between them a passage which at the narrowest part of its width is substantially equal to the external diameter of a mineral insulated electric cable which is to be bent, the radii of the smoothly curved upstanding surface of the or each anvil being greater than or equal to the minimum radius of a smoothly curved surface around which a mineral insulated electric cable of said external diameter can be bent without risk of damage to the cable.

In use, a length of mineral insulated electric cable is introduced into the passage between the upstanding surfaces of the anvils so that it is supported on the substantially flat surface of the table and the length of cable is bent around the smoothly curved upstanding surface or around one of the smoothly curved upstanding surfaces to form said length of cable into a smooth curve. The operation can be repeated for one or more adjoining lengths of the cable until the total required length of cable has been bent into the required smooth curve.

Since the passage bounded by the upstanding surfaces of the anvils is open at each of its ends, a length of mineral insulated electric cable can be introduced into one or other of the ends of the passage and so the tool is suitable for use by either a right handed or left handed person.

Preferably, the upstanding surface of each of the anvils is smoothly curved, the radii of these smoothly curved upstanding surfaces differing from one another.

At least one of the anvils may be adjustably mounted with respect to the table and may have at least two smoothly curved upstanding surfaces each having centres of curvature lying on a line upstanding from the table, the radius of each smoothly curved surface of the anvil differing from that of the or each other smoothly curved surface of the anvil and the anvil being so adjustably mounted on the table that each of its smoothly curved surfaces can be arranged to bound with the or an upstanding surface of the other anvil a passage which, at the narrowest part of its width, is of a width differing from that obtained when using the other smoothly curved surface or each of the other smoothly curved surfaces of the adjustable anvil so that, by selection of a smoothly curved surface having an appropriate radius, the tool is suitable for use with a mineral insulated electric cable selected from mineral insulated electric cables having at least two external diameters differing from one another.

The bending tool may be a component of a kit of parts which also includes, for adjustably mounting on the table of the tool, at least one supplementary anvil, separately formed with respect to the tool and having at least two smoothly curved surfaces each having centres of curvature lying on a line which will upstand from the table when the supplementary anvil is adjustably mounted thereon, the radius of each smoothly curved surface of the supplementary anvil differing from that of the or each other smoothly curved surface of the supplementary anvil and of the or each smoothly curved surface of the or each anvil of the tool.

In a preferred embodiment, the or each adjustable anvil in plan view has a shape approximating to that of an ellipse with the smoothly curved surface on one major side of the ellipse having a radius of curvature differing from that of the smoothly curved surface on the other side of the ellipse. Preferably, the or each adjustable anvil is rotatably mounted on a stud which upstands from the table and means is provided for locking the adjustable anvil with respect to the table and to the other anvil in any desired position.

The or each upstanding surface of each anvil may have extending along the length of the surface and remote from the flat surface of the table a protruding flange or lip which serves to retain a length of mineral insulated cable, whilst it is being bent, in contact with the flat surface of the table.

Preferably, each anvil is made of a resilient material, e.g. a resilient plastics material, but in some cases each anvil may be made of a metal or metal alloy.

The table preferably has an elongate handle which extends from the table in a direction substantially normal to the longitudinal axis of the passage bounded by the upstanding surfaces of the anvils; the elongate handle may have a transverse cross-section of approximately oval shape.

The invention is further illustrated by a description, by way of example, of a preferred mineral insulated cable bending tool with reference to the accompanying drawing, in which: Figure 1 is a perspective view of the preferred bending tools and Figure 2 is a fragmental plan view of the bending tool.

Referring to the drawing, the preferred bending tool comprises a table 1 having a flat surface and, mounted on the flat surface of the table, a fixed anvil 2 and an adjustable anvil 5. The fixed anvil 2 has a smoothly curved surface 3 upstanding from the table and having centres of curvature lying on a line upstanding from the table. The adjustable anvil 5 is rotatably mounted on a stud which upstands from the table 1 and passes through an arm of a bracket 8, which arm is integral with the table and overlies the adjustable anvil. The adjustable anvil 5 has a shape approximating to that of an ellipse with a smoothly curved upstanding surface 6 on one major side of the ellipse having a radius of curvature differing from that of a smoothly curved upstanding surface 7 on the other side of the ellipse.By means of a screw 9, the adjustable anvil 5 can be locked in a position with either of its smoothly curved upstanding surfaces 6 and 7 positioned opposite the smoothly curved surface 3 of the fixed anvil 2 to define between them a passage 10. Around its uppermost edge the adjustable anvil 5 has a peripherally continuous protruding flange 11 which serves to retain a length of mineral insulated cable extending through the passage 10 , whilst it is being bent, in contact with the flat surface of the table 1. An elongate handle 12 extends from the table 1 in a direction normal to the longitudinal axis of the passage 10 bounded by the upstanding surfaces of the anvils.

In use, a length of mineral insulated electric cable is introduced into the passage 10 so that it is supported on the flat surface of the table 1 and a length of the cable is bent around the smoothly curved upstanding surface 6 of the adjustable anvil 5 to form the length of cable into a smooth curve. This operation can be repeated for one or more adjoining lengths of the cable until the total required length of cable has been bent into the required smooth curve.

Claims

Claims:

1. A tool for bending a length of mineral insulated electric cable into a smooth curve comprising a table having a substantially flat surface and, mounted on said flat surface of the table, two anvils each having a surface upstanding from said table, the upstanding surface of at least one of the anvils being smoothly curved and having centres of curvature lying on a line upstanding from said table, which anvils are so transversely spaced apart that said upstanding surfaces of the anvils bound between them a passage which at the narrowest part of its width is substantially equal to the external diameter of a mineral insulated electric cable which is to be bent, the radii of the smoothly curved upstanding surface of the or each anvil being greater than or equal to the minimum radius of a smoothly curved surface around which a mineral insulated electric cable of said external diameter can be bent without risk of damage to the cable.

2. A bending tool as claimed in Claim 1, wherein the upstanding surface of each of the anvils is smoothly curved, the radii of these smoothly curved upstanding surfaces differing from one another.

3. A bending tool as claimed in Claim 1 or 2, wherein at least one of the anvils is adjustably mounted with respect to the table and has at least two smoothly curved upstanding surfaces each having centres of curvature lying on a line upstanding from the table, the radius of each smoothly curved surface of the anvil differing from that of the or each other smoothly curved surface of the anvil and the anvil being so adjustably mounted on the table that each of its smoothly curved surfaces can be arranged to bound with the or an upstanding surface of the other anvil a passage which, at the narrowest part of its width, is of a width differing from that obtained when using the other smoothly curved surface or each of the other smoothly curved surfaces of the adjustable anvil.

4. A bending tool as claimed in Claim 3, wherein the or each adjustable anvil in plan view has a shape approximating to that of an ellipse with the smoothly curved surface on one major side of the ellipse having a radius of curvature differing from that of the smoothly curved surface on the other side of the ellipse.

5. A bending tool as claimed in Claim 4, wherein the or each adjustable anvil is rotatably mounted on a stud which upstands from the table and means is provided for locking the adjustable anvil with respect to the table and to the other anvil in any desired position.

6. A bending tool as claimed in any one of the preceding Claims, wherein the or each upstanding surface of each anvil has extending along the length of the surface and remote from the flat surface of the table a protruding flange or lip which serves to retain a length of mineral insulated cable, whilst it is being bent, in contact with the flat surface of the table.

7. A bending tool as claimed in any one of the preceding Claims, wherein each anvil is made of a resilient material.

8. A bending tool as claimed in any one of the preceding Claims, wherein the table has an elongate handle which extends from the table in a direction substantially normal to the longitudinal axis of the passage bounded by the upstanding surfaces of the anvils.

9. A kit of parts for assembling a tool for bending a length of mineral insulated electric cable into a smooth curve comprising a bending tool as claimed in any one of the preceding Claims and, for adjustably mounting on the table of the tool, at least one supplementary anvil separately formed with respect to the tool and having at least two smoothly curved surfaces, each having centres of curvature lying on a line or lines which will upstand from the table when the supplementary anvil is adjustably mounted thereon, each smoothly curved surface of the supplementary anvil differing from the or each other smoothly curved surface of the supplementary anvil and from the or each smoothly curved surface of said at least one anvil and of the other anvil of the tool.

9. A tool for bending a length of mineral insulated cable into a smooth curve substantially as hereinbefore described with reference to and as -shown in the accompanying drawing.

10. A kit of parts for assembling a tool for bending a length of mineral insulated electric cable into a smooth curve comprising a bending tool as claimed in any one of the preceding Claims and, for adjustably mounting on the table of the tool, at least one supplementary anvil, separately formed with respect to the tool and having at least two smoothly curved surfaces each having centres of curvature lying on a line which will upstand from the table when the supplementary anvil is adjustably mounted thereon, the radius of each smoothly curved surface of the supplementary anvil differing from that of the or each other smoothly curved surface of the supplementary anvil and of the or each smoothly curved surface of the or each anvil of the tool.

Amendments to the claims have been filed as follows 1. A tool for bending a length of mineral insulated electric cable into a smooth curve comprising a table having a substantially flat surface and, mounted on the said flat surface of the table, two anvils, each having a surface upstanding from said table, the upstanding surface of at least one of the anvils being smoothly curved and having centres of curvature lying on a line or lines upstanding from said table, which anvils are so transversely spaced apart that said upstanding surfaces of the anvils bound between them a passage which at the narrowest part of its width is substantially equal to the external diameter of a mineral insulated electric cable which is to be bent, the radii of the smoothly curved upstanding surface of the or each anvil being greater than or equal to the minimum radius of a smoothly curved surface around which a mineral insulated electric cable of said external diameter can be bent without risk of damage to the cable, wherein said anvil is adjustably mounted with respect to the table and has at least two smoothly curved upstanding surfaces each having centres of curvature lying on a line or lines upstanding from the table, each smoothly curved surface of the anvil differing from the or each other smoothly curved surface of the anvil and the anvil being so adjustably mounted on the table that each of its smoothly curved surfaces can be arranged to bound with the upstanding surface of the other anvil a passage which, at the narrowest part of its width, is of a width differing from that obtained when using the other smoothly curved surface or each of the other smoothly curved surfaces of the adjustable anvil.

2. A bending tool as claimed in Claim 1, wherein the adjustable anvil in plan view has a shape approximating to that of an ellipse with the smoothly curved surface on one major side of the ellipse differing from the smoothly curved surface on the other major side of the ellipse.

3. A bending tool as claimed in Claim 2, wherein the adjustable anvil is rotatably mounted on a stud which upstands from the table and means is provided for locking the adjustable and rotatable anvil with respect to the table and to the other anvil in any desired position.

4. A bending tool as claimed in any one of the preceding Claims, wherein the upstanding surface of the other of the two anvils is smoothly curved, the smoothly curved upstanding surface of said other anvil differing from the or each smoothly curved upstanding surface of said at least one anvil.

5. A bending tool as claimed in any one of the preceding Claims, wherein the or each upstanding surface of each anvil has extending along the length of the surface and remote from the flat surface of the table a protruding flange or lip which serves to retain a length of mineral insulated cable, whilst it is being bent, in contact with the flat surface of the table.

6. A bending tool as claimed in any one of the preceding Claims, wherein each anvil is made of a resilient material.

7. A bending tool as claimed in any one of the preceding Claims, wherein the table has an elongate handle which extends from the table in a direction substantially normal to the longitudinal axis of the passage bounded by the upstanding surfaces of the anvils.

8. A tool for bending a length of mineral insulated cable into a smooth curve substantially as hereinbefore described with reference to and as shown in the accompanying drawing.