JPS61195866A - Molding platen roller - Google Patents

Abstract

PURPOSE:To eliminate the need for machining and simplify manufacture, by covering the outer periphery of a roller shaft with a thermoplastic elastomer having a specified hardness by injection molding. CONSTITUTION:An aluminum pipe with an axis size is set in a cavity of a metallic mold for injection molding finished to a predetermined dimensional accuracy and having a polished surface. A molding resin is a polyester resin called 'Hytrel,' and is injection molded under the conditions of a resin temperature of 250 deg.C and an injection pressure of 1,500kg/cm<2> to cover the roller shaft 23 with an elastomer resin. The thermoplastic elastomer 22 has a Shore hardness (D-scale) of 40-70. Accordingly, an elastomer 22 most suitable for a platen roller in a dot impact type printer is molded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of forming a platen roller for an impact dot type printing printer.

Such a printing printer is equipped with an electromagnetic drive type printing head having a 7 x 5 dot matrix array, for example.

Printing is performed line by line on the paper surface to which the platen is attached via an ink ribbon. During printing, the printing platen is made of an elastic material (also called elastomer) with an appropriate hardness because it is subjected to the instantaneous impact action of the dot wire from the print head side.
It is also required to have excellent weather resistance and durability.

[Conventional technology]

The main components of a conventional print head and platen will be explained with reference to a schematic side view of FIG.

In the figure, 10 is a print head, 11 is a dot wire that is electromagnetically driven, 20 is a platen roller whose axis is centered around a rotating shaft 21, and a thick elastomer is coated around the outer periphery of the rotating shaft 21, and 19 is a platen roller that is wrapped around the platen roller 20. It is printed paper. Printing is performed on the surface of the paper 19 on the roller 20 side by the impact movement of the dot wire 11 via the ink ribbon 18 in the direction of the arrow 12 shown in the figure.

Conventionally, the printing platen roller 20 has a metal shaft 21 whose outer peripheral surface is made of a suitably vulcanized hard material with a thickness of, for example, 5III.
A styrene-butadiene elastomer body of No. I was adhered thereto, and the surface hardness of the elastomer body was 80 as determined by a Shimisaki D-type tester.

[Problem that the invention seeks to solve]

However, the elastic body 22 covering the roller shaft 2 in FIG.
The elastic wall thickness and surface hardness are required to appropriately absorb the instantaneous impact movement of the dot wire 11, and when the roller 20 is attached to a mounting shaft (not shown), the roller circumferential surface is required to have high dimensional accuracy. from.

(11 Grinding or polishing the roller surface by machining.

(2) The conventional elastic body 22 has poor weather resistance such as ozone resistance, and is prone to cracking due to deterioration, resulting in deterioration of print quality.

(3) Polishing the roller surface by the mechanical processing requires manufacturing man-hours.

There are other problems.

[Means for solving problems] In the method for manufacturing the impact type platen roller.

This involves applying a thermoplastic resin using an injection molding method while the roller shaft is inserted into a mold. However, the molded resin elastomer around the roller is an elastomer resin with a surface hardness of 4° to 70 as determined by a Share hardness tester (D-type model).

[For production]

The elastomer resin obtained by the injection molding method according to the present invention is applied to the roller shaft core at a predetermined thickness in the mold, so the machining process is not required, making manufacturing simple and inexpensive. Roller molding is done.

The hardness of the elastomer resin to be adhered to is less than 40, the printing impact force of the dot wire will cause the wire to wear down on the platen roller 20, creating holes in the printing paper 19, and the hardness will be 7.
If it is larger than 0, the surface becomes too hard and the dot wire 11 will not be deformed or broken. In connection with this, the problem of noise during dot printing is also eliminated.

〔Example〕

A molding example of the impact type platen roller of the present invention will be described in detail with reference to the sectional view of the roller in FIG.

The platen roller shaft 23 is an aluminum pipe with an outer diameter of 25 mm and a thickness of 211111 mm. and a length of 2505 m.

The thickness of the deposited elastomer 22 shown is 511I1
1.

The elastomer is manufactured using an injection mold that has been finished to a predetermined dimensional accuracy and has a surface polished finish, and an aluminum pipe with the above-mentioned shaft dimensions is set in the mold cavity before injection of the molten resin. It has become.

The molding resin is Hytrel (Hytrel 5557).
A polyester resin called "Dupont" was used at a resin temperature of 250℃ and an injection pressure of 1500Kg/c-.
Injection of elastomer resin under certain molding conditions.

Ection) is formed. However, the mold temperature was 40°C.

Thermoplastic elastomer 22 molded onto the roller shaft 23
An elastomer 22 is formed which has a hardness of 40 to 70 according to a Shore tester and is most suitable for the platen roller of this type of dot impact printer.

Metal pipe (aluminum) explained in the above example
The roller shaft core is not limited to this, but is also made of plastic pipe,
For example, use glass fiber as a reinforcement material.

It is also possible to use a resin pipe with a plastic matrix, and the shaft core of such a pipe structure is lighter than the conventional metal iron, which has the effect of reducing the load on the roller drive motor. .

The polyester elastomer resin has superior weather resistance and durability compared to conventional butadiene hard rubber elastomers, and a roller having a shore D hardness of 40 to 70 on the resin surface can be easily realized.

FIG. 1 After installing rotating shafts on the apparatus side at both ends of the platen roller, a printing dot life test was conducted, and the results confirmed that the roller function was extremely stable and had a long service life.

〔Effect of the invention〕

As explained above, in the platen roller molding method, the manufacturing method is significantly simplified by using the injection molding method, and the molded elastomer has an optimum surface hardness. It also has excellent weather resistance, so the printing quality on dot wires is stable over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a platen roller for explaining the present invention in detail. FIG. 2 is a schematic side view of the main components of a conventional printing platen. In the figure, 20 is a platen roller. 22 is an elastomer (elastic body), and 21 and 23 are platen roller shafts or shaft cores. Next day 22 Figure 1! ? Part 2 concave

Claims (2)

[Claims] (1) In the impact type printing platen, the outer periphery of the roller shaft is made with a Shore D hardness of 4 using the injection molding method.
A method for forming a platen roller, characterized in that a thermoplastic elastomer of 0 to 70 is applied. (2) The method for molding a platen roller according to claim 1, wherein the axis of the platen roller shaft is a plastic pipe.