GB1587135A

GB1587135A - Methods of connecting objects

Info

Publication number: GB1587135A
Application number: GB37370/77A
Authority: GB
Original assignee: ELPAG AG CHUR
Current assignee: ELPAG AG CHUR
Priority date: 1976-09-08
Filing date: 1977-09-07
Publication date: 1981-04-01
Also published as: SE7709993L; DE2640494A1; DE2640494C3; DE2640494B2; GB1587136A

Description

(54) METHODS OF CONNECTING OBJECTS (71) We, ELPAG AG CHUR, a Swiss company, of Quaderstrasse 11, CH-7001 Chur, Switzerland, 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: This invention relates to methods of.connecting a first, elongate object to a second object.

According to the present invention there is provided a method of connecting a first, elongate object to a second object, wherein a hard metal bar, the shape of which corresponds at least approximately to that of the first object, and a wire structure are pressed against the second object such that the wire structure forms a wire cage having foot loops which are pressed out laterally on both sides of the metal bar, the foot loops becoming anchored in the second object and/ or being welded to the second object, the metal bar is drawn out of the wire cage, and the first object is inserted into the wire cage.

The method enables the first object to be removed and replaced. For instance, if the first object is a tubular heating element, it can be replaced if it becomes burnt out.

The first object can, as just mentioned, be a tubular heating element. It can instead be, for example, some other tubular or rodlike object or an extruded shaped member.

The second object can be another elongate object, e.g. like the first object, a shaped member or a plate, for instance a metal container wall.

The invention will now be further described, by way of illustrative and nonlimiting example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view showing a method embodying the present invention for joining objects; Figure 2 is an enlarged plan view of a portion of the structure shown in Figure 1; and Figure 3 is a cross-sectional view of the structure shown in Figure 2.

Referring to the drawings, a rod 1 shown in phantom in Figure 1 is made of a very hard metal and is inserted into a wire coil 2 the diameter of which is about 1-1/2 times greater than the diameter of the rod 1.

The unit comprising the rod 1 and the coil 2 is then pressed on a plate 3 (e.g. of aluminium) which may be, for example, the wall of a container, in a die press which preferably has a groove corresponding to the rod 1.

In the pressing operation, the excess length of each turn of the wire coil 2 forms a foot loop 4. The foot loops 4 are impressed into the material of the plate 3.

However, at the same time the material of the plate 3 flows into the loops 4 and is anchored in each loop like the head of a rivet. At the same time, the part of each turn of the coil 2 that extends between the rod 1 and the plate 3 is impressed into the plate 3, the aluminium flowing around the circular transverse section of the wire coil 2 and becoming correspondingly anchored.

Since the metal rod 1 is of a very hard material, as mentioned previously, the wire coil 2 is not pressed into the metal rod 1 during the pressing operation. The metal rod 1 can thus be removed from the coil 2 in the direction of the arrow, so that a wire cage is formed, the cage being anchored to the plate 3 by means of the foot loops 4.

A tubular heating element 5 can then be inserted into the wire cage in such a way that it is firmly held, yet may be easily removed for replacement or repair.

The foot loops 4 of the wire coil 2 which extend to the side can be also connected to the plate 3 by welding, in particular by roll-seam welding, for example when the plate 3 is of sheet metal. This is recommended when because of the thinness of the sheet metal, for example a wall of a container, it is not possible to press the loops 4 of the wire coil 2, which extend to the side, into the material without damaging it, or when it is possible to do so only to a certain extent, or when otherwise the joint would not be sufficient for the expected thermal or mechanical requirements. The loops 4 of the wire coil 2, which extend to the side, act in this case as welding studs.

Preferably, at least the surface of the wire coil 2 is of a material which is electronegative with respect to the material of a jacket of the heating element 35, whereby the wire coil 2 forms a protective electrode for the jacket.

A particular favourable design from the standpoint of cost of manufacture can be attained if the jacket of the tubular heating element is made from nonalloyed steel which is left unprotected at the surface, and the wire coil 2 is made from zinc coated (i.e.

galvanised) steel wire. If the sections of the wire are kept correspondingly small, then the tubular heating element is protected against corrosion by the zinc layer which operates as a protective electrode. It is of course, to be understood that combinations made of other metals can be also used, as long as the wire operates as a protective electrode.

WHAT WE CLAIM IS: 1. A method of connecting a first, elongate object to a second object, wherein a hard metal bar, the shape of which corresponds at least approximately to that of the first object, and a wire structure are pressed against the second object such that the wire structure forms a wire cage having foot loops which are pressed out laterally on both sides of the metal bar, the foot loops becoming anchored in the second object andqr being welded to the second object, the metal bar is drawn out of the wire cage, and the first object is inserted into the wire cage.

2. A method according to claim 1, wherein at least the surface of the wire structure is of a material which is electronegative with respect to material forming at least the surface of the first object, whereby the wire structure forms a protective electrode for the first object.

3. A method according to claim 1 or claim 2, wherein the first object comprises unalloyed steel with an unprotected surface and the wire structure is manufactured from galvanised steel wire.

4. A method according to any one of claims 1 to 3, wherein the wire structure comprises a wire coil and the metal bar is inserted into the coil before the bar and coil are pressed against the second object.

5. A method according to any one of the preceding claims, wherein the first object is a tubular heating element.

6. A method according to any one of the preceding claims, wherein the second object is a plate.

7. A method according to claim 6, wherein the plate is a wall of a container.

8. A method of connecting a first, elongate object to a second object, the method being substantially as herein described with reference to the accompanying drawings.

9. The combination of a first and a second object which have been connected by a method according to any one of the pre

Claims

ceding claims.

For the Applicants: