Plastic article or earthenware shaping or treating: apparatus – Preform severing means – Severing means is perforator
Reexamination Certificate
2001-03-20
2003-10-28
Mackey, James P. (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Preform severing means
Severing means is perforator
C425S289000
Reexamination Certificate
active
06638052
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a drilling apparatus for flexible sheet made of thick thermoplastic material and more particularly to a drilling apparatus applicable for production of ordinary tightening portion made of thermoplastic woven fabric or synthetic leather, bag belt, webbing for animal, shoelace through portion and the like and not requiring any special post-treatment.
2. Description of the Related Art
According to a conventional technology disclosed in, for example, Japanese Patent Application Laid-Open No. 1-193109, in a drilling process for a printed circuit board made of epoxy resin whose substrate is glass fabric, the printed circuit board is sandwiched between a fixed fitting plate and a pressing plate fixed to a pressure foot which ascends or descends in order to reduce occurrence of burr, chipping, deviation and surface damage. Under this condition, it is intended to drill a hole having a desired diameter with using a drill. In this case, a hole is preliminarily formed in each of the fixed fitting plate and the pressing plate such that the hole has a clearance with respect to the drill.
Further, according to, for example, Japanese Patent Application Laid-Open No. 7-308896, a metallic thin plate, water-soluble lubricant soaked sheet or a sheet formed of polymer layer is placed on a multilayered substrate such as multilayered printed circuit wiring board in order to ensure heat removal effect, lubrication effect, dispersion preventing effect, and halo phenomenon preventing effect at the time of drilling a through hole by gimlet, drill or punch. Alternatively, the same substrate is sandwiched by the said sheets and then, through holes are drilled in the same substrate together with the sheets.
In recent years, many kinds of thermoplastic fiber fabrics have been used as webbing products for animal girth or strap instead of natural leather. These products have plural holes formed by drilling or punching in the same way as the drilled hole described in the above publication in order to insert a clasp of a buckle. Usually, eyelets are attached to prevent the configuration of these holes from being collapsed. However, because ordinary webbing products are woven using strict thick fibers, fibers cut on an inside face of each hole are likely to be separated loosely from its woven structure so that the eyelet drops out easily, thereby its availability being lost.
Therefore, in order to stabilize the configuration of a formed hole without attaching the eyelet thereto, a drilling apparatus which fuses an inside face of the hole by heat at the same time of drilling has been developed using thermal plasticity of composition material of the webbing products. A basic method for the drilling is to melt the inside face of the hole by heat using a heating rod or ultrasonic wave at the same time when the hole is drilled and leave the face harden.
Because the drilling apparatus described in the above publication is drilling in a multilayered substrate by rotating a gimlet or drill of 0.2 to 0.50 mm in diameter at high speeds of 50,000 to 100,000 rpm, the hole's diameter is very small and necessarily, the position accuracy and processing accuracy are under unit of micron. Further, despite high-speed rotation and heat generation, a rotation with such speed does not generate a high temperature over a melting point of ordinary thermoplastic resin. Therefore, applying such drilling technology to the webbing products made of thermoplastic material, just as it is, is meaningless and substantially impossible.
On the other hand, if it is intended to drill a hole in the webbing products using the above-mentioned heating rod or ultrasonic wave, its processing speed is decreased and productivity also drops. Further, the inside face of the formed hole is not smooth face but there remains a melting mark and melting chips adhere to a peripheral edge of the hole, so that the peripheral edge of the hole is locally swollen and a beautiful hole's configuration is difficult to secure.
SUMMARY OF THE INVENTION
The invention has been achieved to solve the above described problems and an object of the invention is to provide a drilling apparatus capable of obtaining a beautiful hole's configuration with stability in a sheet, which is made of flexible thermoplastic material being different from a strict material used such as a printed circuit wiring substrate but a thick material, without special post-treatment, and ensuring a high productivity.
A sheet material which is a processing object of the invention is different from a ordinary strict plate having a low viscosity and an excellent workability such as metal and electronic parts. For example, the sheet material is composed of fiber woven fabric, fiber knitted fabric, unwoven fabric or thick thermoplastic resin material, in which thermoplastic resin is soaked, having a flexibility and difficult to machine because its viscosity is increased by a heat generated during machining.
As described above, the drilling apparatus of the invention is demanded to form a hole in the said sheet material so that the configuration of the hole is not collapsed bearing a long term use without any special treatment after drilling is made and an inside face and peripheral portion of the hole are processed beautiful.
As a result of accumulated considerations based on these premises, inventors of this invention recognized that it was necessary to develop technology, in which an inside face of the hole is melted at the same time of drilling and further no melting chips adheres to the periphery of the hole. Basically, drilling with a rotation drill which makes a sliding contact with an inside face of the hole is preferable in view of efficiency and it is preferred that the inside face of the hole can be melted at the same time.
Then, the inventors drilled in synthetic resin (nylon) being composition material of webbing products by rotating a drill of an ordinary vertical drilling machine while heating the material over a melting temperature thereof. Consequently, although an inside face of the formed hole had somewhat smoothness, melting chips adhered to the peripheral edge of the hole on a rear face in the drilling direction and further, the peripheral edge portion on the same rear face was swollen outward. Still further, because the melting resin were hardened to be adhered to blade grooves of the drill and piled, continuous drilling for a long time was disabled. The phenomenon that the melting resin were hardened to be adhered to the blade groove and piled occurred also when drilling in the front and rear faces of a drilling region of the webbing products sandwiched by a fixed fitting plate and a pressing plate as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 1-193109 by means of a heating drill. In this case, melting resin which could not escape adhered to the blade groove, so that the frequency of continuous drilling decreased by contraries.
Therefore, a conclusion that drilling with a heating drill having an ordinary configuration could not attain its practical purpose was reached. As a result of further trial processing, when a rod having a simple circular section was used by removing the blade from the drill and canceling positive heating, and feeding speed and rotation speed were set to appropriate values, the inside face of a hole was formed in equally fused smooth surface. Further, no melting chips adhered to the front and rear faces around a peripheral portion of the hole formed in the webbing tape and the peripheral portion of the hole on the rear face was not swollen. Consequently, a very beautiful hole having a stabilized configuration was obtained by accident.
Accordingly, the invention has been achieved based on the above described finding. Therefore, according to a main aspect of the invention, there is provided a drilling apparatus for flexible sheet made of thick thermoplastic resin material, comprising: a table containing a hole having a predetermined dia
Nozawa Yasutoshi
Yamazaki Makoto
Yokoyama Yutaka
Yunoki Akio
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Heckenberg Donald
Mackey James P.
YKK Corporation
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