Clamp and mounting electric heater with a cable

Abstract

A band or strip heater including novel means to join shielded leads to the heater and to resist separation of or damaging the leads connected therewith; and to the novel construction and mounting of a cable clamp for electric heaters.

Description

The invention relates to improvements in band or strip heaters and to the novel construction and manner of mounting a cable clamp on an electric heater. Cable clamps are used for mechanically securing electrical cables or cords to electrical devices such as a band or strip heater. Such clamps generally comprise two generally arched clamping portions mounted in opposed relationship to one another and secured tightly clamped over the cable or its covering sheath by means of screws extending through complemental radial ears provided on each clamp portion.

The cable clamp of the present invention embodies novel means to slidably attach the clamping portions to the outside surface of a band heater or similar heating device. Novel means is provided on the band or strip heater to receive the clamping portions securely therein without materially increasing the thickness of the strip or band heater in the area of the cable clamp, as well as to conveniently and quickly secure the sheathed leads to the heater. Such clamping means insures against breakage of the electrical connection due to impact or shock, particularly useful where the heater is utilized in a mechanism subject to vibration or in a movable device, such as a die, mold or the like.

It is therefore an object of the invention to provide an assembly of the character referred to.

Another object is to provide a novel cable clamp for an electric heater.

Another object is to provide novel means to mount a cable on an electrical device such as a heater.

Another object is to provide one wall of an electrical device such as a heater with novel means to receive a cable clamp and secure the cable to the device.

Another object is to provide an assembly of the character referred to which permits quick and easy connection of a heater and its supply leads and resists shock causing unintended disconnection, but which is not expensive or difficult to manufacture and which is simple and economical to use.

Other objects and advantages of the invention will become apparent with reference to the following description and accompanying drawings. In the drawings:

FIG. 1 is a perspective view of a band heater having the novel clamp mounted thereon;

FIG. 2 is a fragmentary front elevational view of the band heater in the area of the cable clamp;

FIG. 3 is a vertical sectional view of the band heater, taken substantially on line 3 -- 3 of FIG. 2, showing the wire enclosing armored cable in place; and

FIG. 4 is a view similar to FIG. 2, showing the assembly in another position on the heater.

Referring to the exemplary embodiment of the invention shown in the accompanying drawings, the band heater 11 illustrated is provided with an integrally connected cable clamp 12 on its outside surface. This clamp may be arranged to extend laterally as shown in FIG. 2 or it may be disposed longitudinally as shown in FIG. 4 (so it may also be used on flat heaters or the like). Specifically, heater 11 is comprised of inner metallic wall 13 and outside metallic wall 14. Arranged between these two walls is an electric heating element 15 that is suitably insulated from the walls by layers 16 of dielectric material such as a plastic sheet. Terminal wires 17 and 18 are connected to the heating element 15 in a conventional manner, which wires emerge in the form of cable 19 from the band heater assembly through an opening 21 provided in the outer wall 14.

Preferably, an apertured metallic plate 20 is laid over the outer insulation layer 16 to protect the wires emerging through aperture 21, and an armored, or other protective, sheath 22 is telescoped over the cable.

The cable clamp comprises a pair of clamp elements 23 connected to the outer wall 14 in such manner that they are free to move toward and away from one another for the purpose of receiving the armored sheath 22 and clamping it firmly to resist its removal. Each of these elements 23 is formed with a generally arched clamping portion 24 that embraces the sheath 22. Each arched portion includes radial ears 25 which receive tightening screws 26 to securely clamp the portions 24 tightly about the armored sheath 22.

Each clamp portion 24 terminates at one end (i.e. the end attached to wall 14) in a foot portion 27 that is inserted beneath an embossment 28 formed in the outer wall 14. This anchors the clamping portions firmly to the wall so as to resist their being separated therefrom, but at the same time allows the clamp portions to be carried toward each other to clamp the armored sheath tightly between them. The structure is also sufficiently versatile to accommodate armored sheaths which may be out-of-round or of varying thicknesses or sizes.

In assembly, the clamp foot portions 27 are laid in the embossments 28 before the heater band is assembled, whereupon the cable 19 is threaded between them. The outer wall is next fitted snuggly over the inner wall with the heater element arranged between them. The margins 29 of the inner wall are then rolled over the margins of the outer wall to integrally secure the assembly together.

The assembly is such that the elements carrying electric current to the heater are totally insulated from the walls of the heater and the cable 19 is protected against damage by the armored sheath that is held firmly against removal. The structure described hereinabove is substantially similar for connecting a strip heater; the said strip heater being flat instead of curved like a band heater.

Although I have described a preferred embodiment of my invention in considerable detail, it will be understood that the description thereof is intended to be illustrative rather than restrictive, as details of the structure may be modified or changed without departing from the spirit or scope of the invention. Accordingly, I do not desire to be restricted to the exact construction shown and described.

Claims

I claim:

1. An electric heater including an inside metallic wall and an outside metallic wall, an electric heating element between said walls, means insulating said heating element from said walls, an aperture in the outer wall, an embossment in said outside wall extending across and opening into said aperture, a cable extending through said aperture and electrically connected to said heating element, a clamp surrounding said cable adjacent said aperture, said cable being electrically insulated from said walls and said clamp, said clamp having securing means for engaging said cable, and a foot portion on said clamp nested and limitedly slideably movable in said embossment for resiliently connecting said electric cable to said heating element.

2. The device recited in claim 1, wherein the clamp member is comprised of two like arched clamping portions.

3. The heater recited in claim 1, wherein the foot portion extends radially from the clamp member.

4. The heater recited in claim 1, wherein said clamp securing means has radially extending ears to receive therein clamp screws.

5. The heater recited in claim 1, wherein an apertured metallic plate overlies the insulation in the area of the wall aperture beneath said foot portion.

6. The heater recited in claim 1, wherein the margins of one wall overlie the margins of the other wall to secure the two walls together.

7. The heater recited in claim 1, wherein the heater comprises a band heater and the walls are curved.