JPS60199622A - Manufacture of resin platen roll - Google Patents

Abstract

PURPOSE:To prevent void in a product and sink of the surface thereof by a method wherein a central layer is formed by the first injection molding with a shaft as insert and then, the second injection molding is done using the said molding as insert to form a surface layer. CONSTITUTION:A metal shaft 2 is set into a mold 5 as insert and a central layer 3 comprising a crystalline resin such as polyethylene or polypropyrene is injection molded around the shaft 2. Said molding is set into a die 6 as insert and a surface layer 4 comprising a crystalline resin such as polyethylene or polypropyrene is injection molded around the central layer 3. The use of two injection moldings allow the formation of a relatively thin molding by the first injection molding thereby preventing void in a product and sink of the surface thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a resin platen roll for a dot printer.

(Description of Prior Art) Platen rolls for dot printers are conventionally made of styrene-butadiene rubber, which has a Shore 8 type hardness of about 98°.

Rolls or resin rolls made of polyethylene, polypropylene, etc. are mainly used.

The former gofu roll is made by press molding of rubber by inserting a metal shaft, and the latter resin roll is made by extruding resin into a tip bar shape and then inserting a metal shaft through secondary processing. Manufactured by cutting or polishing.

However, the former method of press molding of rubber requires many pre-processes such as kneading and parting, and the material is expensive, and the latter method of manufacturing resin rolls requires the insertion of a metal shaft. Drilling the hole and inserting the shaft is not easy,
The shaft is easily deformed when it is inserted, which may reduce product precision, and the extrusion bar is expensive. Regardless of the manufacturing method, the work is complicated and quality control is difficult. An increase in product costs was inevitable.

(Object of the Invention) The present invention has been made in view of the above points, and proposes a method for rationally manufacturing a high-precision, high-quality, and inexpensive platen roll.

(Structure of the Invention) In the production of a resin platen roll for a dot printer, the present invention includes (a) using a shaft as an insert and injection molding a center layer around the shaft using a crystalline resin; Thereafter, the molded body is used as an insert, and a surface layer is injection molded around the center layer using a crystalline resin.

FIG. 1 is a partially cutaway perspective view of a resin platen roll 1 obtained by carrying out the present invention. This platen roll 1 includes a metal shaft 2 with a diameter of 8N11 for mounting on a printer, a center layer 6 with a wall thickness of 7 mm formed around the shaft 2, and a center layer 6 with a wall thickness of 7 mm formed around the center layer 6. The core layer 6 and the surface layer 4 are made of crystalline resin exclusively for polyethylene and polypropylene, and have a surface hardness of 98±1° (Shore A type). .

Hereinafter, the present invention will be explained in order of steps using the accompanying drawings.

(B) Formation of the center layer (Fig. 2) A metal shaft 2 is set in a mold 5 as an insert, and a center layer 3 made of a crystalline resin such as polyethylene or polypropylene is injection molded around the shaft 2. . Note that 6a is a well that prevents uneven flow of the resin flowing in from the gate 6b, and 30 is a constriction portion that prevents deflection and deformation of the shaft 2 during injection.

(b) Shape of the surface layer g (Fig. 6) Using the molded body as an insert, a surface layer 4 made of Ceritone and a crystalline resin such as polyethylene or polypropylene is injection-molded into a mold 6 around the center layer 6. . In the figure, 4a is a well, and 4'b is a gate. Note that the mold 6 may also be used as the gold W5 used when forming the center layer.
In this case, it is necessary to use nests or the like to change the shape of the cavity of the mold to suit each process.

Thereafter, the surface and ends of the molded body thus obtained are cut or polished to obtain a final product.

(Effects of the Invention) As described above, the present invention forms the center layer by the first injection molding using the shaft as an insert, and then forms the surface layer by the second injection molding using the molded body as the insert. It is something. Therefore, there is no need to insert the shaft by secondary processing, which simplifies the process and prevents the shaft from deforming. In addition, when obtaining a thick-walled molded product by injection molding, internal voids and surface sink marks are likely to occur, but in the present invention, since two injection moldings are performed, one Depending on injection molding, it is only necessary to form a relatively thin-walled molded product, and there will be no voids inside the product or sink marks on the surface.Furthermore, inexpensive general-purpose crystalline resin such as polyethylene or polypropylene is used as the raw material resin. Therefore, the products become cheaper.

As described above, the present invention makes it possible to rationally manufacture a resin platen roll, and the resulting platen roll is not only inexpensive due to the simple manufacturing method and inexpensive raw materials, but also has high precision and high quality. It will be of high quality.

As described above, the present invention is industrially useful.

[Brief explanation of the drawing]

The drawings relate to the present invention; FIG. 1 is a partially cutaway perspective view of a resin platen roll obtained by carrying out the present invention, and FIGS. FIG. 3 is a cross-sectional view of the mold.

Claims (1)

[Claims] In the production of a platen roll, the shaft is used as an insert and a center layer is injection molded around the shaft using a crystalline resin (b), and then the molded body is used as an insert and a crystalline resin is injection molded around the shaft. A method for manufacturing a resin platen roll, comprising injection molding a surface layer around the center layer using resin.