Buckles – buttons – clasps – etc. – Including readily dissociable fastener having numerous,... – Having mounting surface and filaments constructed from...
Reexamination Certificate
2000-06-23
2002-03-19
Sandy, Robert J. (Department: 3626)
Buckles, buttons, clasps, etc.
Including readily dissociable fastener having numerous,...
Having mounting surface and filaments constructed from...
C024S450000
Reexamination Certificate
active
06357087
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a molded surface fastener made of thermoplastic synthetic resin material having engaging elements each having a novel shape, which are integrally molded on a surface of a flat substrate independently of each other, the surface fastener having a particular function, and also relates to molding method and molding apparatus therefor. More specifically, it relates to a molded surface fastener which can be molded in various sizes from minute size to normal size, is suitable for various applications owing to its novel shape and function and can be produced continuously with a high efficiency by a single process by a simplified production apparatus, and a molding apparatus and molding method therefor.
2. Description of the Related Art
Conventional molded surface fasteners are manufactured in various methods. One typical manufacturing method is complete batch manufacturing method by injection molding. According to another typical manufacturing method, a die wheel having a plurality of engaging-element-molding cavities on a peripheral face thereof is driven and rotated in one direction and molten resin material is introduced continuously to the peripheral face of the die wheel so as to mold a flat substrate with engaging elements continuously and integrally. According to these methods, engaging elements of various shapes such as palm-like, hook-like or the like can be molded.
According to still another method, a plurality of substantially T-shaped engaging-element-molding extruding ports are provided in an extruding die and a flat substrate molding extruding ports are formed by communicating bottoms of the respective T-shaped extruding ports with each other. By extruding molten resin from the extruding ports at the same time, a plurality of ribs each having a substantially T-shaped cross section on a surface of the flat substrate are molded continuously and the molded molten resin material is hardened. Then, with the flat substrate remained, the aforementioned ribs are cut in a direction perpendicular to an extending direction of the ribs or at an appropriate inclination angle into a predetermined thickness successively, so that substantially T-shaped engaging elements are formed. By extending the flat substrate in a molding direction after the cutting, the cut individual engaging elements are separated with a desired pitch, thus a molded surface fastener is produced.
According to these molding methods, the shapes and dimensions of the engaging elements are limited if productivity thereof is engaged. On the other hand, if the shapes and dimensions of the engaging elements are provided with variety to some extent, it is difficult to mold them continuously or the quantity of production steps is increased, so that productivity decreases. In either case, these methods have both advantages and disadvantages.
Particularly, according to the above-mentioned method in which a drawing process is performed after the ribs of molten resin molding material on the surface of the flat substrate are cut from the extruding die and in which an engaging head portion can have a variety of sectional shapes to some extent, four steps, i.e. extrusion, rib cutting, heat drawing and cooling are required as disclosed in, for example, Japanese Patent Publication No. 53-22889. Of these steps, particularly the rib cutting requires a high processing accuracy, so that a quite large amount of labor and time are consumed for maintenance and control therefor.
The above-mentioned publication discloses a proposal that the aforementioned rib cutting process should be simplified and the heating extension process should be eliminated. According to this proposal, an extrusion-molded product having a plurality of ribs on the surface of the flat substrate is introduced onto a rotating drum and rotated substantially by a half turn in accordance with a rotation of the drum. During this rotation, two cutting blades, which are disposed in parallel to a rotation axis of the drum, of a cutting device are reciprocated in a direction of a chord with respect to the peripheral face of the drum so that the ribs are cut. At this time, a cutting angle when the extruded product is rotated on the peripheral face of the drum is utilized. By cutting twice with a difference of phase of about 80° along the peripheral face of the drum, the ribs is cut into a V shape. Then, engaging elements whose front shape is substantially T shape and side view is substantially isosceles triangle are formed continuously.
However, in not only the aforementioned molded surface fastener produced by the cutting as mentioned above but also the molded surface fastener molded by the conventional molding cavities, a flat surface is necessarily formed on at least one of the side faces or front or rear faces of an engaging element, so that an edge portion is formed between the adjacent flat faces. This edge portion is likely to cut a loop which is a mating engaging element at the time of engagement and gives an uncomfortable feeling when touched.
In a molded surface fastener except the aforementioned extruded fastener, a configuration of a molding cavity needs to be complex if a shape of an engaging element is designed to be complex. However, such a complex molding cavity cannot be produced, so that necessarily only an engaging element of a simple shape can be obtained. On the other hand, in the molded surface fastener produced by extrusion, at least the front shape of each engaging element can be complex. However, because the molded ribs are separated into individual engaging elements by cutting the molded rib, its front and rear end faces of the engaging element are only a combination of the aforementioned flat surfaces. Therefore, a further complex configuration such as the one having curved faces is difficult to produce.
According to not only the manufacturing method of the surface fastener by extrusion and cutting but also the manufacturing method of the surface fastener by a die wheel or molding die, the flat substrate and engaging elements are entirely cooled at the same time. Therefore, the flat substrate and engaging elements of a completed surface fastener are the same in materiality. If they are cooled rapidly after molded, crystallization is not accelerated so that the entire structure becomes flexible. Consequently, the engaging strength and peeling strength may become insufficient. If they are cooled gradually, on the other hand, the crystallization is accelerated so that the entire hardness is increased. Consequently, the engaging strength and peeling strength increase and at the same time, the hardness of the flat substrate is also increased, so that the surface fastener becomes entirely stiff.
Further, in the engaging element of the aforementioned surface fastener produced by extrusion and cutting, a front or rear cross section of the engaging element perpendicular to the extruding direction is always the same. Particularly, it is impossible to mold an protruding end of the engaging element at a sharp angle. Thus, when the engaging element are a male one having equal dimensions, especially if a loop of a mating female engaging element is minute, the male engaging element cannot invade into the loop easily. As a result, the engagement rate drops, so that sufficient engaging strength and peeling strength cannot be secured.
SUMMARY OF THE INVENTION
The present invention has been achieved to solve the above described problems and an object of the invention is to provide a molded surface fastener which ensures an improved engagement rate, sufficient engaging strength and peeling strength although it has engaging elements each having a novel shape that did not exist in a conventional art and is entirely provided with high flexibility, and an effective manufacturing apparatus and method thereof.
The inventors of the present invention have already publicized a molded surface fastener which is a basis of the present invention as well as a molding apparatus and method thereof vi
Murasaki Ryuichi
Takizawa Toshiaki
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Sandy Robert J.
YKK Corporation
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