CA1072619A

CA1072619A - Corner connection for three frame members

Info

Publication number: CA1072619A
Application number: CA253,903A
Authority: CA
Inventors: Bernd Rose; Karl H. Rossler
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 1975-06-13
Filing date: 1976-06-02
Publication date: 1980-02-26

Abstract

Abstract of the Disclosure Connecting means are disclosed for establishing an electrical connection between sheet metal elements that are to be connected together by screw means. The elements are per-forated for the passage of the screw means and the perforations are formed in pressed-out conical areas in the sheet metal ele-ments. The conical elements are adapted to mate when secured together, with the outer surface of one conical area mating with the inner surface of the other conical area. One of the outer and inner surfaces is formed with narrow integral radial ribs for engaging the other of the outer and inner surfaces to make electrical connection when the screw is tightened.

Description

`-` lOqZGji9 This invention relates to an electrical connec~ion especially for switchgear cabinets.
According to the present invention there is provided connecting means for establishing an electrical connection -between sheet metal elements that are to be connected together by screw means, said elements being perforated for the passage of the screw means, the perforations being formed in pressed-out conical areas in the sheet metal elements, said conical elements being adapted to mate when sacured together, with the outer surface of one conical area mating with the inner surface of the other conical area, one of the outer and inner surfaces being formed with narrow integral radial ribs for engaging the other of the outer and inner surfaces to make said electrical connection when the screw is tightened.
Both the outer and inner surfaces may advantageously be formed with said ribs.
The cone angles of said conical areas may differ whereby said areas are elastically deformed into contact when the screw means are tightened.
The screw means preferably comprise a nut and bolt.
The present invention may be carried into practice in a number of ways, but some specific embodiments will now be described, by way o example only, with reference to the accompanying drawings, in which:
Figure 1 is a sectional view showing one embodiment o a connection between two frame members;
Figure 2 i5 a sectional view showing another embodi-' - 1 - ~ . '. ' - , . . : : ~

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ment o~ a connection between ~rame members.
The connection as shown in Figures 1 and 2 may comprise a countersunk screw 5 and a nut 6.
The bolted parts 1 and ~ have interfitting funnel-shaped pressed-out regions 7, 8 (Figure 1) or 9, 10 (Figure 2~
so that each pair of interfitting pressed-out re~ions provides a so-called countersink ~or penetration of the head o~ the countersunk screw 5. At least one of the pressed~out regions 7, 8 or 9, 10 may have a cone angle which dif~ers from the cone angle o~ the head o the countersunk screw 5, i.e., which inclines away from the head of the screw 51 and should also be elastically deformable on tightening o~ the screw connection 5, 6. The head of the countersunk screw 5 is, in the arrangements shown in Figures 1 and 2, disposed in the open cone o one pressed-out region 8 or 9. The nut 6 bears against the other pressed-out region 7 or 10.
In order to obtain a smooth outer surface of ~he connection it is arranged that in each case the pressed-out regions 8, 9 of the frame members 1 and 4 engage in the respect-ive pressed-out regions 7 or 10.
The particular advantage of the described arrangement of the bosses 7, 8 and 9, 10 consists in that the countersunk screw 5 is secured in simple manner against unintentional loosening. The safeguard is achieved by the act that when the parts 1 and 4 are bolted to~ether, the coun~ersunk screw 5 is constantly under tension from the pressed-out region which is elastically deformed. The elastically de~ormed pressed out ~ 2 ~

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region th~refore acts as a cup spring and compensates for any elongation o~ the countersunk screw 5. The cone angles of the pressed-out regions 7, 8, 9, 10 may both incline away from the head of the co~mtersunk screw (Figure 1). It is~ however, possible that only the cone angle of one pressed-out region, in Figure 2 the cone angle of the pressed-out region 10, inclines away from the h~ad of the countersunk screw 5.
The cone angles inclining away from the head of the countersunk screw 5 may be smaller or greater than the cone angle o~ the head of the countersunk screw 5.
In order that the cup spring action of the pressed-out regions 7, 8 or 10 inclining away from the cone angle of the head of the countersunk screw 5 cannot be released by excessive extension of the countersunk screw 5, the countersunk screw 5 is preferably made of a high-tensile steel with low expansion.
At least one of the facing surfaces of the pressed-out regions 7, 8; 9, 10 i5 provided with narrow radially-extending ribs. In Figure 1 the region 7 is provided internally with ribs 7a. In Figure 2 the region 10 has ribs lOa. It may also be expedient to provide each pressed-out region 7, 8; 9, 10 with radially-extending ribs both internally and externally.
The ribs may, for example, be ~ormed by pressing the regions 7, B; 9, 10 between a plunger which can be either smooth or pro-vided with radially-extending ribs and a matrix provided with radially-extending ribs. A metallic contact of the interfitting regions 7, 8; 9, 10 is created when they are clamped together ..

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even when they are initially covered with an electrically insulating layer, for example a coat o~ paint or a layer of plastics material applied by a powder coating process. The narrow ribs 7a, lOa of the regions 7, 10 exert a high contact pressure on the opposite region 8, 9 when clamped together and thus penetrate the electrically insulating layer until metallic contact occurs. This metallic contact is therefore achieved on assembly without additional work or additional parts.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Connecting means for establishing an electrical connection between sheet metal elements that are to be connected together by screw means, said elements being perforated for the passage of the screw means, the perforations being formed in pressed-out conical areas in the sheet metal elements, said conical elements being adapted to mate when secured together, with the outer surface of one conical area mating with the inner surface of the other conical area, one of the outer and inner surfaces being formed with narrow integral radial ribs for engaging the other of the outer and inner surfaces to make said electrical connection when the screw is tightened.

2. The connecting means defined in claim 1 wherein both the outer and inner surfaces are formed with said ribs.

3. The connecting means defined in claim 1 or 2 wherein the cone angles of said conical areas differ whereby said areas are elastically deformed into contact when the screw means are tightened.

4. The connecting means defined in claim 1 or 2 wherein the screw means comprise a nut and bolt.