Plastic and nonmetallic article shaping or treating: processes – Forming articles by uniting randomly associated particles – Stratified or layered articles
Patent
1990-04-12
1991-02-26
Theisen, Mary Lynn
Plastic and nonmetallic article shaping or treating: processes
Forming articles by uniting randomly associated particles
Stratified or layered articles
264120, 419 66, 425356, 425412, 425422, B29C 4320, B29C 4314, B32B 110
Patent
active
049960148
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns a method for the manufacture of a rivet for a fixed spike or for a sleeve-mounted spike, respectively, by pressing in a mold.
The invention concerns apparatus for carrying out the method for the manufacture of a rivet for a fixed spike or for a sleeve-mounted spike, respectively, the apparatus comprising a mold provided with a cavity space, pressing equipment, and filling equipment.
The commonest structure in the prior-art fixed spikes and in the rivet parts of sleeve-mounted spikes, respectively, is such that the fixed spike or the rivet part of a sleeve-mounted spike, respectively, is provided with a separate hard-metal tip. Such a spike is usually manufactured in a mould consisting of several parts, so that the mold parts are provided with punches acting in the axial direction of the spike to be manufactured, the spike blank being pressed axially in opposite directions by means of these punches. It is a drawback of such methods of manufacture and apparatuses that they require several separate working steps and, moreover, the construction of the apparatuses and of the molds is complicated.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an improvement over the prior art methods of manufacture and apparatuses. A more specific object of the invention is to provide a method of manufacture and an apparatuses intended for carrying out the method which are intended in particular for the manufacture of such a large-tip spike wherein the wear-resistant layer to be formed in the tip portion of the rivet is formed as an annular part around the tip. Such a spike has been described earlier in the Finnish Patent Application No. 880294.
In view of achieving the objectives stated above and those that will become apparent herein after the method in accordance with the invention comprises the following steps:
the cavity space in the mold, corresponding to the shape of the spike to be manufactured, is filled to the desired extent with a first material to form the body part of the spike,
a first punch, whose diameter is substantially smaller than the diameter of the cavity space in the mold, is fitted into the cavity space concentrically with the cavity space, and the annular space between the first punch and the cavity space is filled with a second material so as to form the wear-resistant surface layer for the spike,
the first punch is removed, and the space remaining after said punch is filled with a third material, and
the spike is pressed to the desired shape and density, whereinafter the spike is removed from the mold.
the apparatus in accordance with the invention comprises two molds so that the counter-faces of the first mold to be placed one against the other, are placed in the widest portion of the cavity space in the mold in the area of the foot widenings of the cavity space and that the press equipment comprises punches, which are fitted to act towards the second mold substantially perpendicularly to the counter-faces.
Compared with the prior-art structure, by means of the invention several advantages are obtained, whereof, e.g., the following may be stated. In the method in accordance with the invention, by pressing from one direction, it is possible to manufacture the hard tip part as well as the round forms in the foot part of the spike, the latter being of essential importance for the conduct of the spike in a tire. In the method and equipment in accordance with the invention, the wear-resistant outer face of the spike tip may be formed of desired thickness. If necessary, this wear-resistant outer face may be composed of several different materials. Since, in the method of the invention, the spike is manufactured in the mold by pressing from one direction, the tip portion of the spike is compressed more densely than the foot part. Since the foot part of the spike remains less dense than the tip, a spike of lower weight and lower consumption of material is obtained. A remarkable advantage of the equipment is simplicity of the m
REFERENCES:
patent: 2357407 (1944-09-01), Kurtz
patent: 2815535 (1957-12-01), Bodine
patent: 3255278 (1966-06-01), Smith
patent: 3255659 (1966-06-01), Venghiattis
patent: 4419413 (1983-12-01), Ebihara
patent: 4472350 (1984-09-01), Urano
Neste Oy
Theisen Mary Lynn
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