Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Composite article making
Reexamination Certificate
1999-04-22
2001-02-06
Kuhns, Allan R. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Composite article making
C264S138000, C264S250000, C264S266000, C264S321000, C264S328700
Reexamination Certificate
active
06183674
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method for manufacturing diaphragms for use in such electroacoustic transducers as loudspeakers, microphones and the like or, more specifically, to such manufacturing method in which an edge of a cell structure is simultaneously joined with a diaphragm body upon molding the diaphragm body through in injection.
DESCRIPTION OF RELATED ART
Technical conditions desired for the diaphragm for use in such electroacoustic transducers as the loudspeakers and the like will be that the diaphragm comprises a diaphragm body which is light in weight and having a proper internal loss property showing a high elasticity and an edge which is light in weight and high in the internal loss to show an optimum linearity, and that the diaphragm is excellent in the durability, easy to manufacture, consistent in the quality of products, and still inexpensive. In recent years, further, the waterproofness has become one of important characteristics of the diaphragms mainly for use on vehicles.
In order to realize the foregoing technical conditions, there have been suggested and utilized various types of free-edge diaphragms. In particular, a diaphragm structure obtained by simultaneously molding and joining the diaphragm body and edge with the injection molding utilized has been suggested in various types in view that the structure is capable of retaining excellent properties of synthetic resin diaphragms and of being provided economically, whereas almost none of them could realize the foregoing technical conditions at satisfiable level.
In Japanese Patent Laid-Open Publication No. 63-42300, for example, there has been suggested a diaphragm in which an edge which is trimming-processed into a predetermined shape is preliminarily inserted in a pair of molds for injection-molding and is joined simultaneously with the injection molding of the diaphragm body to be integralized therewith. In the case of such diaphragm shown specifically in this publication, the edge is joined with the diaphragm body by causing an inner periphery of the edge to enter substantially in the center of the thickness of the diaphragm body. Since in this joining structure the position of joining part of the edge cannot be always constant as it depends on the conditions of the injection, so as to cause many problems to arise, such that the edge is broken within molding cavity in the worst case, and that such broken piece is caused to be simultaneously molded and joined, and the diaphragm of this publication has been far from being realized.
In Japanese Patent Laid-Open Publication No. 2-239799, there has been suggested an improvement in the foregoing problems of Publication 63-42300. Because this improvement employs as the edge material a woven fabric of cotton, silk or the like of a chemical fiber having the heat resistance, however, there has been still left a problem in respect of the excellent linearity to be obtained with the optimum internal loss as well as the waterproofness to be attained.
Further, there has been suggested a simultaneous injection molding and joining of an edge of solid elastomer (not-foamed yet) with the diaphragm body which is preliminarily molded into a predetermined shape and disposed in the molds. In this case, however, a residual stress applied to the edge due mainly to the constriction after the molding cannot be well relieved, so as to cause such a problem that a remarkable deformation occurs. In the event when the solid material (not-foamed yet) is used as the edge, further, there arises a problem that a specific tone occurs due to such material and an abnormal sound is generated, in particular, upon receiving a large input.
In order to remove the problem of the deformation of edge, a simultaneous joining of the edge in the form of a foam rubber with the molding of diaphragm body has been suggested in Japanese Patent Laid-Open Publication No. 9-102998 which is assigned to the same assignee as the present case and to which U.S. Pat. No. 5,705,108 corresponds. In this simultaneous molding and joining, it is essential that the diaphragm body has a sufficient heat resistance with respect to a molding temperature of the edge. In an event where such synthetic resin as polypropylene or the like which is relatively low in the thermal deformation temperature is employed for the diaphragm body, therefore, it becomes necessary to set the molding temperature of the edge to be lower, and there arises a problem that the manufacture is time-consuming so as to result in an increment of costs.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a manufacturing method which can eliminate the foregoing problems, and is capable of obtaining a diaphragm which is light in weight, high in the elasticity, excellent in the linearity, causing no abnormal sound to be induced even upon the large input, less deformable and still inexpensive.
According to the present invention, the above object can be realized by a manufacturing method of the diaphragm which is manufactured through an injection molding, characterized in that an edge of a cell structure, preliminarily molded and cut into a predetermined shape is preliminarily disposed on one of a pair of mating molds for injection molding, the other mold is disposed thereon with a predetermined gap provided therebetween, and thereafter the edge and diaphragm body are simultaneously joined with an injection-molding of the diaphragm body. In this event, it is preferable that open cells of the cell structure are included in joining surface of the edge with respect to the diaphragm body.
Other objects and advantages of the present invention shall become clear as the description of the invention advances as detailed with reference to working aspects of the invention as shown in accompanying drawings.
REFERENCES:
patent: 5650105 (1997-07-01), Yocum
patent: 5705108 (1998-01-01), Nonogaki
patent: 5793002 (1998-08-01), Sato et al.
patent: 63-42300 (1988-02-01), None
patent: 2-239799 (1990-09-01), None
patent: 9-102998 (1997-04-01), None
Foster Electric Co. Ltd.
Kuhns Allan R.
Lynn & Lynn
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