JPS5938904B2 - Type head manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a type head using a thin plate insert.

FIG. 1 shows a conventional crown-shaped plastic type wheel (type head) 1.

The type wheel 1 is made up of a type base 3 integrally provided with a boss portion 2, and a number of arms 4 having type characters at the tips thereof integrally formed at equal intervals in the circumferential direction. A metal insert 6 having a semicircular irregularly shaped hole 5 is fitted and fixed in the boss portion 2, and the type wheel 1 is connected to the flat portion T of the insert 6.
It is mounted by fitting the hole 5 into a selection shaft (not shown) having a notch corresponding to the selection shaft, and is positioned in the rotational direction by the flat portion T engaging with the notch of the selection shaft.

The purpose of using the metal insert in this way is to improve the wear resistance of the hole. In this case, in order to improve the positioning accuracy of the type wheel 1 with respect to the selected axis, it was necessary to strictly control the dimensional accuracy of the diameter of the hole 5 and the flat portion T, and the machining thereof was difficult.

This problem is also common to type heads of types other than the crown-type type wheel shown in FIG.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a type head that can improve the accuracy of mounting the type head on a selected shaft and facilitate manufacturing. Next, embodiments of the present invention will be described with reference to FIGS. 2 to 5. FIG. 2 is a perspective view of the insert 11 used in the present invention. The insert 11 is made of a material having spring properties and has a flat plate 12 and a plurality of curved arms 13 integrally formed therein.

The flat plate 12 corresponds to the notch of the selection shaft to which the type head is attached. On the other hand, as shown in FIG. 3, an insert holding pin 15 is fixed to the center of the lower die 14 of the type head mold used in the present invention.

The insert holding pin 15 has the same cross-sectional shape as the selection shaft on which the type head is attached, and is provided with a flat notch 16 as shown in FIG. The type head is molded as follows.

The upper mold IT is removed and, as shown in FIG. As the fitting progresses, each arm 13 engages with the insert holding pin 15. In this state, the upper mold 17 is stacked on the lower mold 14, and a synthetic resin is injected into the mold to form a type head.

During this molding, the insert 11 is strongly pressed against the insert holding pin 15 by the pressure of the resin and is integrally molded with the synthetic resin. In this way, the selection shaft fits into the boss part of the molded type head without play (because the insert holding pin 15 has the same cross-sectional shape as the selection shaft).
An insert 11 is integrally molded, and when the type head is fitted to the selection shaft, this insert 11
The flat plate 12 is in close contact with the notch of the selection shaft, and each arm 13 is in close contact with the peripheral surface of the selection shaft on the opposite side to the notch.

Therefore, these parts that require the most wear resistance come into contact between metals, improving wear resistance. The fitting accuracy of the thus formed tie head with the selection shaft is determined by the accuracy of the insert holding pin 15, so if the insert holding pin 15 is machined with high precision, sufficient fitting accuracy can be obtained. This makes processing easier.

As described above, according to the present invention, it is possible to easily manufacture a type head with excellent attachment accuracy to a selection shaft.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a conventional crown type wheel, Figs. 2 to 5 show an embodiment of the method for manufacturing a type head according to the present invention, and Fig. 2 is a perspective view of an insert.
FIG. 3 is a front sectional view of the mold, FIG. 4 is a sectional view of the insert holding pin, and FIG. 5 is a diagram showing how to fit the insert into the insert holding pin. In the figure, 11 is an insert, 12 is a flat plate, 13 is an arm,
14 is the lower mold, 15 is the insert holding pin, 16 is the notch,
17 is an upper mold.

Claims (1)

[Claims] 1. An insert made of a material having spring properties and having a curved arm integrally provided on a flat plate is pressed onto a notched insert holding pin provided in a type head mold, and the flat plate is pressed against the notch, and the arm is pressed against the notch. A method of manufacturing a type head, comprising: injecting a synthetic resin into the mold to integrally mold the insert after the insert is fitted by engaging with a holding pin.