JPS6366669B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing type wheels used in typewriters and the like.

[Prior art] Conventionally, in the case of a type wheel that is attached to a type selection mechanism in a typewriter or the like and prints desired characters, symbols, etc. on printing paper, the outer periphery of the disk-shaped portion of the resin-molded type wheel body The type part is integrally molded with a resin different from that of the upper type wheel body at the tips of a large number of arms formed radially. As shown in FIG. 5A, due to the collision of the resin against the tip of the arm, the resin tends to be filled from the bottom of the mold space forming the type part, which has the disadvantage that filling defects in the character part of the type part are likely to occur. Ta.

In addition, as shown in Figure 5B, the bending of the arm tip caused by the resin injection pressure causes resin to fill the above space while creating turbulent flow, resulting in poor filling due to volatile gas generated from the resin. In addition, the quality of the type part deteriorates due to uneven resin curing, and the adhesion strength of the type part to the tip of the arm cannot be obtained sufficiently.

[Objective] In view of the above-mentioned conventional drawbacks, the object of the present invention is to prevent resin turbulence and ensure resin filling when integrally molding a type part at the tip of an arm using a simple structure. It is an object of the present invention to provide a method for manufacturing a type wheel that can improve the quality of the type part and the adhesion strength of the type part to the tip of the arm.

[Example] The present invention will be described below with reference to Examples.

FIG. 1 is a schematic front view schematically showing a type wheel according to the present invention, FIG. 2A is a front view showing an enlarged tip of the arm, B is a side view of FIG. 2A, and FIG. A is a front view showing an enlarged view of the arm and type section, and B is a sectional view taken along line B-B of FIG. It consists of a disc-shaped part 2 on which an attached boss part 2a is formed, and a large number of arms 3 extending radially around the outer periphery of the disc-shaped part 2, and is made of polyamide-based material such as nylon, which has a high bending modulus. It is resin-molded using a thermoplastic resin composite material consisting of resin and glass fiber.

The tip end 3a of the arm 3 is formed into a stepped planar shape, and the tip end 3a has a tapered part 3 that improves the flow of the resin injected when molding the type part 4.
b is formed.

The above-mentioned type part 4 has a character part 4a on which characters, symbols, etc. are embossed on the front side, and a type part 4a on the back side.
It consists of a convex day tent portion 4b for positioning with respect to a hammer (not shown) that strikes the arm 3, and has impact resistance, abrasion resistance,
It is integrally molded from a thermosetting resin composite material that has compression resistance and is made of, for example, a phenolic resin and short glass fibers.

Next, the operation of this embodiment will be explained with reference to FIG. 4, which shows the molded state of the type part 4 on the tip end 3a of the arm 3.

The type wheel main body 1, which has been resin-molded in advance in a previous step, is tapered between a pair of molds 5 and 6 in a space 7 in which the tip portion 3a is filled with the thermosetting resin composite material forming the type portion 4. The portion 3b is inserted so as to be located on the opposite side of the gate 8.

When the thermosetting resin composite material is injected into the space 7 from the gate 8 in the above state, the thermosetting resin composite material first forms the character part 4a along the tapered surface of the tapered part 3b as shown by the arrow in the figure. After flowing into the upper part of the space 7 shown in the figure and forming the character part 4a,
It flows into the space 7 forming the detent part 4b in the downward direction in the figure, and the type part 4
molded into one piece.

Therefore, in this embodiment, when the type part 4 is integrally molded on the tip part 3a of the arm 3, the thermosetting resin composite material is sequentially filled from the upper part to the lower part of the space 7 forming the character part 4a. The generation of volatile gas is suppressed, it is possible to prevent filling failure of the thermosetting resin composite material in the character part 4a, and it is possible to reliably bring the character part 4 into close contact with the tip part 3a.

[Effects] As explained above, the type wheel according to the present invention has a tapered portion at the tip of each arm, and has a simple configuration that improves the flow of resin during molding of type portions, thereby reducing the turbulent flow phenomenon of resin. It is possible to prevent this, ensure resin filling, and improve the quality of the type part and the adhesion strength of the type part to the tip of the arm.

[Brief explanation of drawings]

FIG. 1 is a schematic front view schematically showing a type wheel according to the present invention, FIG. 2A is a partial front view showing an enlarged tip of the arm, B is a side view of FIG. 2A, and FIG. Figure A is an enlarged front view of the arm and the type part, B is a sectional view taken along the line B-B in Figure 3A, and Figure 4 is an explanatory diagram showing the state of molding of the type part with respect to the arm tip. FIGS. 5A and 5B are explanatory diagrams showing the conventional molding state of the type part with respect to the tip part, in which 1 is the type wheel body, 2 is the disk-shaped part, and 3
is an arm, 3a is a tip, 3b is a tapered portion, and 4 is a type portion.

Claims (1)

[Claims] 1. Tip portions 3 of each of a number of arms 3 extending in the outer circumferential direction from the disc-shaped portion 2 of the type wheel body 1
In the manufacturing method of integrally molding the type part 4 on the arm 3, the steps include: providing a tapered part 3b at the tip end 3a of the arm 3 and molding the type wheel body 1 with resin; and after molding the type wheel body 1, performing each of the above steps. A method for manufacturing a type wheel, comprising: integrally molding the type part 4 by injecting resin from the tip side of the arm 3 toward the tapered part 3b.