Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
1996-08-19
2004-01-13
Lee, Edmund H. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C264S267000, C264S318000, C411S303000, C411S430000
Reexamination Certificate
active
06676874
ABSTRACT:
The present invention relates to a method of forming in place a female fastener bore opening and the fastener which, in the disclosed embodiment, is a a hat-shaped nut fastener sealed at the opposed bore openings.
BACKGROUND OF THE INVENTION
Hitherto hat-like fastener elements are known, e.g. in the form of cap or dome nuts, with an inner passage or bore which is provided with a fastening means, such as a thread or a bajonet socket and is closed at one end by means of a transverse wall. It is also entirely possible, and indeed preferred, for the fastener element to also have a rivet section at one end which can be inserted into a premanufactured aperture in a metal part and deformed by a riveting process in order to obtain a form-fitted connection between the fastener element and the sheet metal part.
Such hat-like fastener elements are known per se and are also of advantage when one is concerned with closing-off the thread of the fastener element or a bayonet connection at one end so that contamination can not penetrate into the thread.
As the fastening means, normally in the form of a thread, is normally located on the one side of the sheet metal part, while the mating screw is screwed into the nut element from the other side of the sheet metal, the riveted connection does not have to bear special forces in the assembled state of the fastener element, but rather, as a result of the threaded connection, an annular ring shoulder of the nut element on the same side of the sheet metal as the thread of the nut element is pressed by the clamping force of the screw against the sheet metal, with the riveted connection itself being largely relieved. Such cap nuts are thus also suitable for use in highly loaded screw connections.
A problem is however encountered when the sheet metal part with the attached hat-like fastener element has to be treated by further process steps before final assembly. Such further treatments include, for example, sand blasting, painting- in particular immersion painting and also the application of other protective layers. Through all these further treatment steps, the danger exists that the thread or the fastener means in the interior of the hat-like fastener element can be blocked or damaged so that it must either be freed from blockages or deposits in time consuming manual labor, or must indeed be scrapped.
It is known in the art to protect hollow cavities in critical components by plastic plugs which can be inserted and removed again. An example for this is a metal brake cylinder, the fluid supply opening of which is provided with a thread and is frequently also closed by a hat-shaped plastic plug. A problem with this solution is, however, not only that the closure plugs can be lost, but rather also that, with mass production, a large number of plastic plugs are required which must then be disposed of.
The present invention is based on the object of providing a fastener element or a sheet metal part with an attached fastener element which is so designed that an effective protection is achieved against blockage of or damage to the fastening means and also against deposits in the fastening means, without the parts which ensure protection being easily lost and leading to disposal problems, and with the fastener element being inexpensive to manufacture, for which purpose a special manufacturing process and a tool for the manufacturing of the fastener element should likewise be provided in accordance with the invention.
SUMMARY OF THE INVENTION
The method of sealing a fastener bore opening of this invention includes supporting a heat softenable plastically deformable sealing element in the bore opening having a diameter which is less than the bore opening, heating the sealing element to its softened plastically deformable temperature, then deforming the sealing element radially outwardly into mechanical interlocking engagement with the bore opening, which seals the bore opening when the sealing element cools. In the preferred method, the sealing element is deformed radially as described by a ram which is reciprocated through the bore opening into engagement with the sealing element. In the most preferred method of this invention, the sealing element is supported on a die member in the bore opening and the ram, which in the most preferred embodiment is heated, deforms the sealing element in the die member into mechanically interlocking relation with the female fastening element in the bore opening. As described, the female fastening element may be a threaded portion in the bore or a bayonet connection. Where the ram is heated, the ram simutaneously heats and radially deforms the sealing element in the fastener bore, as described.
The sealing element or closure plug is so deformed that it enters into a form-fitted connection with the fastener element and thus can not be easily lost, and together with the transverse wall protects the interior of the fastener element with the fastening means, i.e. with the thread or the bayonet socket, against the penetration of undesired media such as paint, rubber, plastic or underseal. Since the plastic closure plug which has been deformed to a type of disc can be pressed inwardly, the path to the thread or to the bayonet socket is first exposed by displacement of the closure plug on insertion of the screw. The closure plug is then preferably received in a receiving chamber formed at the end of the fastener means adjacent the transverse wall and thus remains within its completed fastening. In this manner, the disposal of the closure plugs in the factory where the sheet metal part is manufactured is not necessary at all. On scrapping the article, for example a motor car, the few closure plugs which are built into the car are disposed of through the melting down of the metal.
The closure plugs could indeed consist of a soft metal for example a lead alloy or aluminum, however preferred are closure plugs of thermo-plastic polymeric material, such as polyethylene, since these are usually deformable with a low expenditure of force on simultaneous heating, but readopt a solid form again after deformation and are thus protected against loss.
In a fastener element with the form of a nut with an inner thread, the closure plug is preferably retained by a form-locked fit with the thread at the entry to the thread. In this way the thread serves a double purpose in that it functions on the one hand as a fastening means, and on the other hand, however, also forms the desired form-fitted seat for the deformed closure plug. It is accordingly not necessary to provide a special seat for the deformed closure plug, for example in the form of a special undercut, so that the constructional length of the fastener element is not unnecessarily increased and the manufacturing costs are reduced.
In this design the closure plug preferably projects, in at least substantially sealed manner into at least one thread turn, preferably to approximately two and a half thread turns, but should not however completely fill these out, but rather should have a spacing from the root of the thread turns and be at least substantially rounded, and preferably approximately semicircularly rounded, at its side facing the root of the thread turns. This design of the closure plug in the deformed state ensures on the one hand the sealing of the thread, and also ensures that the closure plug cannot be easily lost. On the other hand this design also facilitates the pressing of the closure plug into the thread or into a receiving chamber at the far end of the thread.
It is particularly favorable when the closure plug has a cup-shaped recess at the side facing the interior of the hat-like element, preferably a recess with a slightly concavely rounded base. Furthermore, the closure plug should have a slightly convexly curved surface at the outer side which extends at least substantially parallel to the slightly concavely extending base of the cup-shaped or pot-like recess. Through this design the pressure forces which are exerted during a sand blasting treatment or during an immers
Howard & Howard
Lee Edmund H.
Profil-Verbindungstechnik GmbH & Co. KG
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