Synthetic resin swivel hook

Details Synthetic resin swivel hook Synthetic resin swivel hook

2000-04-27

2001-11-20

Sandy, Robert J. (Department: 3626)

Buckles, buttons, clasps, etc.

Separable-fastener or required component thereof

Including member having distinct formations and mating...

C024S601200

Reexamination Certificate

active

06317940

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a synthetic resin swivel hook for use in various kinds of bags, knapsack and the like.
2. Description of the Related Art
Recently, instead of a metallic swivel hook, synthetic resin swivel hook has been more often used because the synthetic resin swivel hook is composed of a smaller number of parts than the metallic swivel hook and the synthetic resin swivel hook ensures a better productivity and it is light and cheap. On the contrary, the metallic swivel hook requires a larger number of parts, so that its assembly process is composed of more steps thereby leading to a higher price. Further, because the metallic swivel hook is difficult to paint with durable colors, it lacks of fashion performance so that it is not suitable for traveling bag, shoulder bag or the like. Thus, use of the metallic swivel hook is limited to particular sectors, for example, expensive goods.
An example of the synthetic resin swivel hook has been disclosed in, for example, Japanese Patent Laid-Open Publication No. 9-32839. This synthetic resin swivel hook comprises a hook body protruded from a base portion and a stopper piece which is protruded from the same base portion toward a tip end of the hook body and elastically deformed around a base end thereof. The hook body or stopper piece has a projection projecting from its inner face toward the stopper piece or the hook body provided near the base end and a height of a front end of the projection is set so that it comes into contact with the inner face of the stopper piece or inner face of the hook body within an elastic limit of the base end when the stopper piece is deformed.
In the swivel hook disclosed in this publication, because the hook body and/or the stopper piece has the projection having a desired height directed toward a counterpart on the inner face of the base end portion thereof, even if a strong outside force is applied to the base end portion of the stopper piece, deformation exceeding an elastic limit of the stopper piece is prevented by the aforementioned projection, so that a breaking of the base end portion of the stopper piece, which is the part easiest to be broken is prevented securely. Further, because an existence of the projection prevents a ring, which is attached to an end of a belt and engages the hook body, from moving to between the base ends of the hook body and stopper piece, even if an outside force is applied outward of the hook body by the ring, the ring is moved from the base end of the stopper piece to a front end thereof by the projection, thereby preventing the base end of the stopper piece from being damaged.
However, in the swivel hook disclosed in the above publication, because of the existence of the projection projecting from the inner face of the hook body or the stopper piece, after the same projection comes into contact with the opposing inner face of the stopper piece or hook body, a base end of rotation, when the stopper piece is elastically deformed in the direction to an inner face of the hook body, is moved from a projection end on the base portion to an edge of the projection on the side toward a front end of the hook body, an amount of rotation is reduced extremely. Thus, if it is intended to form an opening space sufficient for engaging the ring attached to the belt to the hook body, the depth and height of the hook body need to be larger than conventionally. As a result, there is produced an adverse effect that the swivel hook itself is enlarged. If an outside force exceeding the aforementioned elastic limit is applied to the stopper piece near the front end of the hook body with respect to the projection, the stopper piece may be broken at the edge of the projection on the side of the front end of the hook body.
As disclosed by U.S. Pat. No. 5,146,657 for example, the conventional synthetic resin swivel hook is formed with the stopper piece slightly off a front end outer surface of the hook body and after the formation, the stopper piece is elastically deformed to fit onto an inside fitting face at a front end of the hook body. Thus, a working amount for it cannot be neglected so that it affects production cost to some extent.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been achieved to solve the above described problems and therefore, an object of the invention is to provide a synthetic resin swivel hook in which a length and depth of a hook body can be set like conventionally, a stopper piece is more easily deformed elastically than conventionally so that there is no fear that the stopper piece may be broken even if a strong outside force is applied thereto and the stopper piece can be formed such that it is in contact with an inner face of the hook body without any special process.
The above object is achieved effectively by the present invention.
According to the present invention, there is provided a synthetic resin swivel hook having a hook body extending from a base portion and a stopper piece extending up to a curved end portion of the hook body from the base portion and elastically deformable at a base end thereof, wherein the stopper piece comprises a base end portion protruded from the base portion; a curved portion formed to be integral with the base end portion and forming substantially C-shape or U-shape protruding toward an inner face of the hook body and being open outward between the base end portion and the hook body; and a tongue piece portion extending from the curved portion up to an inside fitting face of the curved end portion of the hook body.
The base end portion of the stopper piece is not related directly to elastic deformation and so structured that even if a strong outside force is applied, its base end does not get broken. On the other hand, the hook body and belt connecting ring are not different from the conventional though their design, structure and operational effect are different from the conventional.
If an ordinary outside force is applied to the tongue piece portion of the stopper piece, most of the force is consumed for elastic deformation of its curved portion, so that a front end of the tongue piece portion comes into contact with an inner face of the hook body smoothly. If the aforementioned outside force is released, the curved portion is restored to its original shape. With the restoration action, the tongue piece portion returns to its original position so that it comes into contact with the inside fitting face at the curved end portion of the hook body. If a strong outside force is applied to the base end portion of the stopper piece, the base end portion is never elastically deformed and further may not be broken because stiffness and strength thereof are higher than the other portions. Further, the stopper piece has a blocking function for the curved portion, thereby preventing the curved portion and the tongue piece portion from being broken.
The aforementioned structure of the stopper piece of the present invention is effective for manufacturing of the swivel hooks with a high efficiency. Generally, a molded product is contracted when it is taken out from a cavity in a molding die at the time of molding. Particularly in the C-shaped or U-shaped molded product, because a temperature distribution of the molded product is different at the time of molding, the product is contracted such that both opening side ends approach each other. According to the present invention, if the curved portion is constructed as described above, after molding, the curved portion is deformed in a direction that both the open ends approach each other because of contraction, although the cavity is designed such that an end of the tongue piece portion is slightly off a front end fitting face of the hook body. As a result, the end of the tongue piece portion comes into contact with the inside fitting face of the front end of the hook body or approaches it with a gap to an extent not deteriorating the function of the swivel hook.
Conventionally, the swivel hook is mol

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