Plastic and nonmetallic article shaping or treating: processes – With step of making mold or mold shaping – per se – Utilizing surface to be reproduced as an impression pattern
Reexamination Certificate
1999-12-01
2001-09-18
Ball, Michael W. (Department: 1733)
Plastic and nonmetallic article shaping or treating: processes
With step of making mold or mold shaping, per se
Utilizing surface to be reproduced as an impression pattern
C156S245000
Reexamination Certificate
active
06290890
ABSTRACT:
FIELD
The present invention relates to a process and apparatus for fabricating laminate articles having thermoplastic inner and outer shells.
BACKGROUND
The fabrication of multi-layered plastic articles in which the layers are bonded together produces a stiff article of a greater rigidity than can be achieved with a single sheet. However, any deficiency in the bond between the layers or shells results in a loss of strength in the laminate article. Thus, it is important to have shells which mate perfectly at their interface so that the bonding can be across the entire interface. In fabricating male and female moulds extreme accuracy is, therefore, required to match the mould surfaces. For parts having complex surfaces such accuracy is difficult to achieve. Elaborate jigs and measurement techniques are required when the moulds are to be fabricated manually. If computer controlled machines are used then the cost of these machines represents a significant expense.
Accordingly, it is an object of the invention to provide an improved method of fabricating thermoformed plastic articles. It is a further object of the invention to provide a method of producing male and female moulds with interface surfaces formed with a high degree of accuracy.
SUMMARY OF THE INVENTION
According to the invention there is provided a process for making moulds used to produce laminate articles. The process includes making a mirror image mould from one of a female mould and male mould so as to produce a production male and female mould. The use of a mirror image ensures the required accuracy in fitting together parts made from the production male and female moulds.
The process may further include making an inner shell from the female mould and an outer shell made from the male mould. The inner shell may be bonded to the outer shell to form a laminate article.
The outer surface of the inner shell may be bonded with an inner surface of the outer shell. The bonding step may employ an adhesive that is free of non-recyclable contaminants and material of the inner and outer shells may, preferably, be recyclable. This allows the finished product to be ground up and reused in making further laminate articles.
The inner and outer shells may be made of co-extruded thermoplastic sheet while the co-extruded thermoplastic sheet may have a substrate layer of recycled material and a cap layer of protective material.
The method may further include fabricating a prototype article having an article interface surface, forming a female mould from the prototype article, and forming a male mould from the female mould. An inner shell is made from the female mould while an outer shell is made from the male mould. The inner shell is bonded to the outer shell to form a laminate article.
The co-extruded thermoplastic sheet may have a substrate layer of recycled material and a cap layer of protective material.
The bonding step may employ an adhesive that is free of non-recyclable contaminants and material of said inner and outer shells is recyclable.
Features such as reinforcing, mounting brackets, and edge details may be affixed to a visible surface of the outer mould and a visible surface of the inner mould.
REFERENCES:
patent: 3582424 (1971-06-01), Norvaisa
patent: 3619446 (1971-11-01), Nauta
patent: 4601867 (1986-07-01), Martell et al.
patent: 5070668 (1991-12-01), Lieberman
patent: 5225133 (1993-07-01), Ihara et al.
patent: 5435959 (1995-07-01), Williamson et al.
Ball Michael W.
Hall Priddy Myers & Vande Sande
Musser Barbara J.
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