DE9314035U1 - Folding rule - Google Patents

Description

The invention relates to a folding rule made of wood or wood-based material &ogr;.the like, the links of which are pivotably connected to one another in pairs by means of a joint at the end.

Such rulers have rivet joints with a rivet shaft as a bolt that passes through the two links. The thickened end of the rivet is deformed by being struck wide (rolling or wobble rivets).

This well-known joint formation with mechanically processed rivets requires a relatively long time and does not guarantee an exact clamping length, since the mechanical forces used in rolling or wobble riveting have different effects. In the case of coated rivets, the very thin layer (e.g. brass or similar) can also be easily damaged.

The object of the invention is to improve the holding power (strength) of the rivet in a folding rule of the type mentioned, while maintaining its clamping length precisely, and on the other hand to simplify/accelerate the overall production of the joint and to improve its optionally coated

Office Bielefeld: Telephone (0521) 171072 · Telex 932449 · Fax (0521) 171081 . Office Munich: Telephone (089) 6417071 · Telex5214115 SSWD · Fax (089) 6411468

Bank details/bankers: Sparkasse Bjßlefelfi, ^ontonurnmer 72001563 (bank code 48050161)

Commerzbank AG Bielefeld; Bank number Q8534f3.(Bank code 480 40035)

Postgiroamt Hannover, Kofiionlimfrier:38928.-3©4 (bank code 25010030)

Not to damage the surface.

According to the invention, this object is achieved in a folding rule of the aforementioned type in that the abutting parts of the multi-part rivet are equipped with opposing welding surfaces which are firmly connected to one another by means of electrical pulse welding.

Such a design and manufacture of a joint for a folding rule made of wood etc. has various advantages. For example, pulse welding (using a capacitor pulse welding machine) at high welding energy produces a very short-term, very hot current that firmly welds the metal parts together without damaging the adjacent link material (wood etc.). The manufacture of such joints can be accelerated by a high welding cycle rate compared to conventional mechanical processes.

In a preferred embodiment, on the one hand, a full-surface rivet disk is equipped with a shaft in one piece, the free end of which has an annular end face, which rests against an opposite full-surface rivet disk and is welded there.

In another embodiment, on the one hand, a protruding ring-shaped welding surface can be formed on a separate hollow or solid rivet shaft on each end face, which can be placed against the outer rivet disks, which are also full-surface, and welded to them.

By using rivet shafts of different lengths, the required clamping lengths can be maintained so that each joint provides good clamping for the links it holds.

In a further preferred embodiment of a two-part rivet, a short

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The rivet shaft must be formed in one piece. A hollow or solid, thinner rivet shaft fits into a hollow rivet shaft with a corresponding inner diameter, preferably by means of a snug fit. The cylindrical surfaces that come into contact with each other form welding surfaces that must be firmly connected using pulse welding for a given clamping length.

Welding the individual rivet parts that pass through the links using electrical pulse welding only takes a few milliseconds, so that the welding points are heated sufficiently, but the surrounding material (such as wood) of the links is no longer heated. The metal rivet does not warp and does not tarnish in the area around the welding zone.

Since the storage capacitor of the impulse welding machine is already recharged when the next rivet is inserted into the machine, the production speed is practically determined by the time required to insert the rivet.

Further features emerge from the subclaims.

The protection extends not only to the individual features of the protection claims but also to their combination.

The drawing shows embodiments of the invention. It shows:

Fig. 1 perspective view of a G1 ie derma ß rod with connecting joints,

Fig. 2 an enlarged view (side view with partial section) of a two-part rivet with, on the one hand, a rivet disk equipped with a one-piece rivet shaft and, on the other hand, an opposite welded full-surface rivet disk,

Fig. 3 an enlarged view (side view with partial sections) of a three-part rivet with a welded full-surface rivet disk abutting the rivet shank end faces,

Fig. 4 is an enlarged view of a modified two-part rivet with a rivet disk and interlocking rivet shafts.

A folding rule (10) designed as a block rule has individual sections (11) which are made of wood or similar, for example. A measurement number scale (12) is printed on the broad sides of each of the sections (11).

The individual links (11) are connected to one another at the ends (in pairs) by means of a joint (13) which is equipped with a rivet (14).

The recessed joint plates, which are usually found in folding rules and are held in place by the rivet, are not shown in Fig. 1 etc. for the sake of simplicity.

In Fig. 2, (14) designates a two-part rivet, on one (lower) rivet disk (15) of which a rivet shaft (16) made of solid material is integrally formed during production.

At the free (upper) end of this rivet shaft (16) there is an annular front surface (17) as a welding surface, which rests against another (upper) full-surface rivet disk (18) and is rigidly and firmly connected to it by means of electrical pulse welding.

In the modified embodiment shown in Fig.3, the rivet (19) is made up of three parts, consisting of a separate, solid central rivet shaft (20) to which a full-surface rivet disk (21, 22) is welded rigidly and firmly by means of pulse welding. For this purpose, the two free ends of the rivet shaft (20) are equipped with an annular welding surface (23, 24).

The selectable length of these rivet shafts in Fig.2 (16) or Fig.3 (20) determines the respective clamping length of the rivet (14,19).

In Fig.4, in a further modified embodiment, the rivet (25) is in two parts such that a short rivet shaft (28, 29) is formed on each rivet disk (26, 27). The rivet shaft (28) is hollow and the further, thinner (upper) rivet shaft (29) is completely or partially enclosed in its interior.

The cylindrical surfaces of the two rivet shafts (28, 29) touch each other and are also firmly and rigidly connected to each other by pulse welding. For better centering, the thin rivet shaft (29), which is made of solid material, can be equipped with a protruding cone (30).

By telescopically pushing the two rivet shafts (28,29) into each other, the exact clamping length is determined in relation to the articulated links (11).

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The ring-shaped welding surfaces (17/13,24) protruding from the rivet shafts (16,20) can be designed as a whole ring or as a split ring, depending on the tensile or bending stress of the rivet (14,19^).

Since it is known that surfaces of metal parts that are welded together exhibit improved strength, the rivets according to the invention prevent the welded rivet disks from tearing off.

Claims (1)

Protection claims Folding rule with links which are connected to one another in pairs by means of an end joint with a rivet passing through it (multi-part), characterized in that the abutting parts of the rivet (14, 19, 25) are equipped with opposing welding surfaces (17, 23, 24, 28, 29) which are firmly connected to one another by means of electrical pulse welding. Folding rule according to claim 1, characterized in that at that in a two-part rivet (14) a rivet disk (15) has a rivet shaft (16) formed in one piece, at the free end of which an annular end face as a welding surface (17) rests against a rivet disk (18) as a further welding surface. Folding rule according to claim 1, characterized in that in the case of a three-part rivet (19) ring-shaped welding surfaces (23, 24) protrude from both ends of a separate rivet shaft (20), which are welded to adjacent full-surface rivet disks (21, 22). Folding rule according to claim 1, characterized in that in the case of a two-part rivet (25) a short rivet shaft (28, 29) protrudes from each rivet disk (26, 27), both of which engage one another and whose cylindrical surfaces are welded together. Folding rule according to claim 2 or 3, characterized in that the rivet shaft (16) is hollow. Folding rule according to claim 2 or 3, characterized in that the rivet shaft is solid. Folding rule according to ·*.- . _Claims ^ ^i ₃ 4, thereby ·*. . Claims _{characterized} in that the rivet shaft (28) is hollow . and the rivet shaft (29) enclosed therein are solid. 8. Folding rule according to claims 4 and 7, characterized in that the solid rivet shaft (29) is equipped with a protruding cone (30). 9. Folding rule according to one of claims 1 to 8, characterized in that the protruding welding surfaces (17, 23, 24) are completely or partially ring-shaped. 10. Folding rule according to one of claims 1 to 9, characterized in that the rivet parts are coated.