JPS5953859B2 - Gear molding method on board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gear molding method that allows an intermittent rotation mechanism of two or more gears whose pitch circles are in contact with each other to be resin molded by simultaneous molding on a metal substrate.

Conventionally, moving parts such as gears and cams were placed on metal substrates.

Although resin molding as a single item has been practiced, it has been impossible to simultaneously mold two or more gears whose pitch circles touch each other, that is, to mesh, because the meshing parts would be integrally connected. For this reason, conventionally the gears were assembled by inserting each gear into a shaft that was caulked onto a metal base plate and using washers to prevent them from coming off, but this made assembly complicated and required a large number of parts, resulting in high costs. It was getting up. Furthermore, because the shaft to be planted was not fixed as specified, the meshing between the gears was insufficient, and rotational transmission could not be achieved satisfactorily. The present invention aims to solve the above-mentioned problems, and provides a method for molding gears on a substrate, which allows two or more gears to be meshed with high accuracy and can be molded with resin without an assembly process. The present invention will now be described by way of illustrated embodiments.

FIG. 1 is a plan view of an intermittent rotation mechanism using gears manufactured by the molding method of the present invention, and this mechanism is used, for example, as part of an auto-return mechanism for a tone arm in a record player.

In the figure, 1 is a metal substrate, 2 is a gold toothed gear having teeth around the entire circumference, and 3 is a partly toothed gear having a toothless recess 3a in a part of the entire circumference. are distributed on the metal substrate 1 so that their pitch circles are in contact with each other, 3b is a toothed portion of the partially toothed gear 3, and 4 is a cam integrally molded on the upper surface of the partially toothed gear 3. Here, the gold toothed gear 2 and toothless gear 3 are mounted on a metal substrate 1, respectively, as shown in No. 3.
Through the circular holes 5 and 6 formed in the metal substrate 1, the gears 2 and 3 are integrated with locking parts 7 and 8 formed on the back surface thereof, so that the gears 2 and 3 can freely rotate with respect to the metal substrate 1. is attached to. Therefore, the gold gear 2, which is constantly rotating,
On the other hand, as shown in FIG. 1, when the toothless recesses 3a of the toothless gear 3 correspond, the toothless gear 3 stops,
When it engages with the toothed portion 3b, it rotates once in a predetermined direction and returns to the toothless recess 3a again, causing an intermittent rotational movement, which causes the tone arm to auto-return in the illustrated embodiment.

Next, a method of simultaneously molding the gold gear 2 and the partially toothed gear 3 onto the metal substrate 1 as described above will be described with reference to FIG. 4. First, in the upper mold 9, a recess 10 for forming the gold gear 2 and a hollow recess 11 for forming the partially toothed gear 3 are respectively formed.
0 and 11 are formed so that the toothless gear 3 faces the gold gear 2 at its toothless recess 3a, and the non-meshing portion 12 between them allows the above-mentioned Both recesses 10 and ]1 are formed discontinuously.

13 is a recess for the cam 4 formed in the upper part of the recess 11, and 14 and 15 are runners for injecting resin into the recesses 10 and 11 respectively.After molding, the runners 14 and 1
The runners formed by 5 are removed.

On the other hand, the lower mold 16 has locking portions 7 with a diameter larger than the diameters of the circular holes 5 and 6 in the metal substrate 1 at positions corresponding to the circular holes 5 and 6.
8 are formed, respectively. Therefore, after pressing the upper and lower molds 9 and 16 on the front and back surfaces of the metal substrate 1,
If the molten synthetic resin material is simultaneously injected from the runners 14 and 15, the synthetic resin material of the runner 14 will fill the recesses 11 and 13.
The synthetic resin material of the runner 15 is filled from the recess 10 through the circular hole 6 into the recess 17, and from the recess 10 through the circular hole 6 into the recess 18, respectively.

After the synthetic resin material solidifies, the upper and lower molds 9 and 1 are
6 is removed, the full-toothed gear 2 and partially toothed gear 3 are formed on the metal substrate 1 in the state shown in FIG.
Both gears 2 and 3 are rotatable through circular holes 5 and 6. As described above, the present invention includes a fully toothed gear 2 arranged on a metal substrate 1 so that pitch circles are in contact with each other, and a partially toothed recess 3a.
Since the partially toothed gear 3 having the above-described fully toothed gear 2 is molded with the partially toothed gear 3 facing the partially toothed gear 3, both gears 2 and 3 can be molded at the same time. This makes it possible to improve the meshing accuracy.

Furthermore, simultaneous molding can reduce molding costs and eliminate the need for assembly steps. It goes without saying that the number of gears can be two or more if the molding conditions for the full-toothed gear 2 and the partly-toothed gear 3 are satisfied as described above. .

[Brief explanation of drawings]

FIG. 1 is a plan view immediately after molding of an intermittent rotation mechanism using gears manufactured by the molding method according to the present invention, FIG. 2 is a plan view showing the meshing state of the mechanism, and FIG. 11
4 shows a cross-sectional view of a molding die and a metal substrate. ]... Metal substrate, 2... Full gear, 3... Missing gear, 3a... Missing tooth recess.

Claims (1)

[Claims] 1. A full-tooth gear and a partially toothed gear, which are arranged on a metal substrate so that their pitch circles mesh with each other, and a partly partially toothed gear having a partially toothed recess.
A method for molding a gear on a substrate, characterized in that the gear is molded with the toothless recess of the partly toothed gear facing the full toothed gear.