The present invention relates to a method and device for molding articles by injection molding while simultaneously imprinting on or transferring onto the molded articles patterns on a continuous sheet.
A method and device for molding articles by injection molding while simultaneously imprinting or transferring patterns on a continuous sheet on or to the molded articles mean that a sheet bearing patterns is pressed against the cavity surface of a female mold by applying the pressure or by evacuating the cavity of the female mold and a molten plastic compound is injected through a male mold into the cavity defined by the male and female molds which are mated together, whereby the patterns are imprinted or transferred on the surface of molded articles or finished products.
According to the prior art, as described in detail in Japanese Patent Publication No. 19132/1975, an injection molding machine with a male mold and a female mold is used. An operator inserts a sheet bearing patterns between the male and female molds and the air under pressure is blown out through the male mold so that the sheet may be firmly pressed against the cavity surface of the female mold. Thereafter, molten plastic material is injected through the male mold into the cavity defined by the male and female molds which are mated together so that the sheet bearing patterns may be imprinted on the surface of the molded articles and then the finished products are ejected.
It is apparently inefficient that an operator inserts a pattern bearing sheet (to be referred to as "a pattern sheet" in this specification) between the male and female molds every time when the articles are molded. Moreover, the pattern sheet must be inserted correctly between the male and female molds so that the pattern sheet may be correctly registered with the surfaces of molded articles. Furthermore, such operation is cumbersome.