GB2104359A

GB2104359A - Induction heating ring

Info

Publication number: GB2104359A
Application number: GB08217183A
Authority: GB
Inventors: Robert J Hart
Original assignee: Commercial Resins Co
Current assignee: Commercial Resins Co
Priority date: 1981-08-24
Filing date: 1982-06-14
Publication date: 1983-03-02
Also published as: GB2104359B; JPS5835891A; AU8173582A; CA1177542A

Abstract

The induction ring (10) is adapted for removably surrounding a pipe and is provided with two arcuate frames (14, 16) hingedly connected in end to end circumferential relationship, these frames having a pair of connected free ends adapted to be opened for placing the frames around the pipe. A plurality of electrically conducting wires (32) (Fig. 2) are carried upon the frames across the axial width thereof and extend cicumferentially between the free ends. An electrical coupling assembly comprises a male connector (60) including two projections (74) adapted to be received in two corresponding holes (88) (Fig. 5) in the female connector (62), each connector being provided with a plurality of coil contacts (76, 90) each connected to an end of a wire, each of the coil contacts of one connector being received in a recess containing a resilient O-ring (93) whereby, when the male and the female connectors are placed in an interfitting relationship, the coil contacts of the male connector are held resiliently against the coil contacts of the female connector to provide electrical continuity for the thus-connected wires. <IMAGE>

Description

SPECIFICATION Induction heating ring The present invention relates to an induction heating ring having hinged frames for permitting mounting of the ring to surround a pipe.

Various induction heating means which circumferentially engage tubing or the like during a welding process are common in the prior art. One prior art patent U.S. Patent No.

3,311,732 to Stein et al, discloses a device which applies heat by means of electrical induction in precise predetermined amounts for in-place brazing of steel tubing. Other prior art references disclose various devices for the butt welding of the ends of metal tubes through the employment of high frequency electrical induction to heat the tube end metal to welding temperature.

In many processes, in the fabrication and construction of pipes or pipelines, or in the application of coating and the like to such pipes, it is frequently desirable to preheat the pipe in the predetermind area or zone to be treated such as in welding, pipe coating and similar processes. Such zonal heating has been effected in the past, for example, by applying a torch flame to the area to produce the desired heat. However, the heating effects produced by a torch flame are highly localized, and are not suitable for many processes which require a uniform heat application, for instance, around the circumference of the pipe.

For example, in field performed processes in which a coating of epoxy or the like is sprayed onto a previously welded pipe joint, the entire area of the joint to be coated should be uniformly and evenly preheated to a suffici ently high temperature prior to the application of the coating material to enable a desired uniform epoxy coat to be deposited. Such coating processes are used, for instance, in applications in which pipes are provided with a protective epoxy coat, except for its ends at which welding to adjacent pipe sections in the tield is effected. After the welding process, the uncoated joint is coated with epoxy to thereby effect a pipe coated along the entire length of the pipe, including the welded junction, for resisting corrosion and other destructive influences to which the pipe may be subjected.Uneven heat, such as by torch preheating, may produce uneven or unreliable coating, which may result in areas of the pipe being undesirably exposed to the elements, resulting in premature pipeline failures. The torch preheating also is slow to perform, usually done manually, and requires carrying the torch and its accessories from each joint to the next.

The present invention provides an induction heating ring adapted for removable mounting to surround a pipe, the ring having at least two arcuate frames hingely connected in end to end circumferential relationship and having a pair of free ends connected together and openable to place the frames around the pipe, and a plurality of electrically conducting wires carried upon the frames across the axial width thereof and extending circumferentially between the free ends; an electrical coupling assembly comprising a male contactor box mounted on one free end and a female contactor box mounted on the other free end, said male contactor box including at least two projections receivable in corresponding holes in the female contactor box, each contactor box being provided with a plurality of coil contacts each connected to an end of one of said wires, each of the coil contacts of one contactor box being received in a recess containing a resilient means, whereby when said male contactor box and said female contactor box are placed in an interfitting relationship, the coil contacts of same male contactor box are held resiliently against the coil contacts of same female contactor box.

Reference is now made to the accompanying drawings, wherein: Figure 1 is a front elevational view of an induction heating ring constructed in accordance with the present invention, shown in a closed position around a pipe which is indicated in cross-section; Figure 2 is a side elevational view of the induction heating ring; Figure 3 is a plan view of the male contactor box assembly of the present invention; Figure 4 is an elevational view of the male contactor box assembly shown in Fig. 3; Figure 5 is an elevational view of the female contactor box assembly of the present invention; Figure 6 is a cross-sectional view taken along section line 6-6 of Fig. 5; Figure 7 is a cross-sectional view taken along section line 7-7 of Fig. 4; and Figure 8 is a cross-sectional view taken along section 8-8 of Fig. 4.

There is shown in Figs. 1 and 2, a hinged circular collar or ring 10 which is adapted to be placed round a pipe 1 2 for heating the welded joints by induction heating. The heating ring 10 extends over the pipe 1 2 both circumferentially and axially (parallel to the axis of the pipe). The ring 10 is comprised of a plurality of arcuate shaped sections, such as the two semi-circular frames 1 4 and 1 6 (as shown in Fig. 1), which are hinged together at the top. The two frames 14 and 1 6 are substantially identical with the exception of their interconnecting lower ends (to be described hereinafter).

Each frame, for example 14, is formed by a pair of semi-circular plates 1 8 and 20 which are interconnected and held in spaced parallel relationship by means of a plurality of outer side spacer bars 22 which are bolted to plates 18 and 20 by means of bolts 23. Frame 16 is formed by a pair of semi-circular plates 24 and 26 (only plate 24 is shown in the drawings) which are connected and held in spaced parallel relationship by means of a plurality of outer side spacer bars (not shown) which are identical to the side spacer bars 22 and which are bolted to the plates 24 and 26 by means of bolts 28.

Each frame 1 4 and 1 6 is provided with a pair of circularly arranged and parallel rows of cable spacer bars 30 which are bolted onto the semi-circular plates 1 8 and 20, and 24 and 26 by means of bolts 31. A plurality of electrically conducting wires or coils 32 are wound on the frames 1 4 and 1 6 between the two rows of cable spacer bars 30. As best shown in the lower portion of Fig. 2, the radial outermost spacer bar 30 is provided with circular cut-outs to receive the cables between the mating pairs of bars 30. The heating ring 10 is also provided with an asbestos cloth 34 which overlies and is held in place by means of a plurality of cloth retainers 36.

The hinged connection between the serni- circular frames 14 and 1 6, comprises a hinge frame or bonnet 38 which includes a pair of triangular plates 40 and 42 disposed outside the frames 1 4 and 1 6 and interconnected by means of a securing rod or lifting bar 44 which is bolted to the triangular plates 40 and 42 by means of bolts 45. The triangular plate 40 is connected to the semi-circular plates 1 8 and 24 by means of bolts 46 and 48, respectively, which form forward pivot points 46 and 48, respectively. Likewise, triangular plate 42 is connected to semi-circular plates 20 and 26 (only plate 20 is shown in the drawings) by means of bolts 50 and 52, respectively (only bolt 50 is shown in the drawings).Bolts 50 and 52 form the rear pivot points 50 and 52, respectively. Each of the bolts, 46, 48, 50 and 52, is provided with a pivot bushing 54 (only two of which are shown).

As previously described, the heating ring 10 is provided with a plurality of wires 32 which are carried on the frame between the pairs of cable spacer bars 30 and cover substantially the entire axial width of the ring as shown in Fig. 2. The inner wires extend for the full circumference of ring 10 from a male contactor box 60 to a female contactor box 62. The two contactor boxes 60 and 62 are mounted on the lower ends of the frames 1 4 and 16, respectively so as to be opposed to the hinge frame 38 (see Fig. 1). The two axial outer or end wires 32 are each provided with pigtail wires 64, as shown in Fig. 2, which are employed as terminals.

Referring to the details in Figs. 3, 4, 7 and 8, the male contactor box 60 comprises a front insulator plate 66, a middle plate 68 and a back insulator plate 70, which are joined together by means of a plurality of bolts 72. The male contactor box 60 also includes a pair of projections 74 which are employed as plugs or guide pins. Box 60 is provided with a plurality of coil contacts 76 which are aligned in a row. The coil contact or button 76 is disposed in a recess which includes a compression lug 78 (see Fig. 7).

Each of the buttons 76 is provided with a threaded shank 77 which is adapted to be received in the end of a wire 32 (not shown in this figure) so that each button is electrically connected to a corresponding wire 32. More particularly, the compression lug 78 is adapted to be received over the end of a wire or cable 32 (not shown in Fig. 7); in this regard, it must be understood that the conductor inside the cables 32 is not a solid conductor but made of strands of wire. Therefore each compression lug firmly surrounds the strands and permits a close grouping thereof so that the shank 77 of the button 76 can be screwed into the tight grouping of strands as thus provided by the compression lug 78.

Referring to Figs. 5 and 6, the structure of the female contactor box 62 is essentially the same as the male contactor box 60 just described except that the female contactor box is provided with two recesses 88 adapted to receive the prongs or projections 74 of the male box when the ring 10 is placed in the closed position as shown in Fig. 1. Otherwise, the female box is provided with plates 80, 82 and 84 which correspond with plates 66, 68 and 70, respectively; button 90, prong 91 and compression lug 92 correspond exactly with button 76, prong 77 and compression lug 78, respectively, previously described.

One other difference, however, exists between the female contactor box 62 and the male contactor box 60; that is, an O-ring 93 is provided in a circumferential groove in the recess behind each button 90. These O-rings 93 are compressed somewhat when the heating ring 10 is placed in the closed position shown in Fig. 1. Therefore, it is the O-rings 93 that provide the resilient urging of the buttons of one contactor box against the buttons of the other contactor box.

When the heating ring 10 is placed upon and around a pipe 12 as shown in Fig. 1, a set of top rollers 96 will support ring 10 on the pipe 1 2 and will also permit the ring to be rolled along the length of the pipe for a limited distance. The top rollers 96 are each mounted on a top wheel mount 98, the latter mounts being bolted to a portion of the triangular plates 40 and 42 (see Fig. 2). A set of side rollers 100 are mounted each on a side wheel mount 102 affixed to a portion of the side plates 18 and 22, and 24 and 26. The side rollers 100 do not necessarily contact the side of the pipe 12, but serve to keep the ring 10 generally centrally disposed around the pipe and prevent scraping of the sides of the ring against the sides of the pipe.

In operation, the male contactor box 60 and the female contactor box 62 are placed in the interfitting relationship described above.

This coupling arrangement provides electrical continuity through the wires 32 by means of the resilient contact between the buttons 76 on box 60 and the buttons 90 on box 62.

Claims

1. An induction heating ring adapted for removable mounting to surround a pipe, the ring having at least two arcuate frames hingely connected in end to end circumferential relationship and having a pair of free ends connected together and openable to place the frames around the pipe, and a plurality of electrically conducting wires carried upon the frame across the axial width thereof and extending circumferentially between the free ends; an electrical coupling assembly comprising a male contactor box mounted on one free end and a female contactor box mounted on the other free end, said male contactor box including at least two projections receivable in corresponding holes in the female contactor box, each contactor box being provided with a plurality of coil contacts each connected to an end of one of said wires, each of the coil contacts of one contactor box being received in a recess containing a resilient means, whereby when said male contactor box and said female contactor box are placed in an interfitting relationship, the coil contacts of said male contactor box are held resiliently against the coil contacts of said female contactor box.

2. An induction heating ring according to Claim 1, wherein the resilient means comprises an O-ring disposed in each recess behind the coil contact.

3. An induction heating ring according to claim 1 or 2, in which the coil contacts are button shaped and aligned axially on the male contactor box and on the female contactor box.

4. An induction heating ring according to Claim 1, wherein the coupling assembly is constructed substantially as herein described with reference to Figs. 3 to 8 of the accompanying drawings.