JPS6017688B2 - Synthetic resin shaft molding equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to a synthetic resin shaft molding device.

Conventionally, when molding a minute hand shaft, for example, as shown in FIGS. 1 and 2, molding molds 1 and 2 that move up and down, molding molds 3 that move horizontally and are located at the joint between these two molds, and 4 are combined, and molten synthetic resin is injected into a ball-shaped cavity 5 formed inside to form a minute hand shaft 6 shown in FIGS. 3 and 4.

Therefore, a small diameter bearing portion 7 is formed on the minute hand shaft 6.
Then, on the outer circumferential surface, synthetic resin enters between the joining surfaces of the molds 3 and 4 during molding, so that the deformers 8 and 8 protrude oppositely in all directions of the axis. A shaft hole 10 of a minute hand gear 9 is frictionally coupled to a bearing portion 7 on the minute hand shaft 6, and a slip mechanism is configured between the gear 9 and the shaft 6. However, when attaching the minute hand gear 9 by press-fitting it to the minute hand shaft 6, the burrs 8, 8 protruding from the outer peripheral surface of the bearing portion 7 press against the inner peripheral edge of the eyelet 10 of the minute hand gear. For this reason, there was a drawback that the slip torque between the minute hand shaft 6 and the gear 9 was not constant, and the entire gear was distorted. The present invention provides a synthetic resin shaft that can be supported with equal slip torque as set without the burr formed during molding coming into contact with the inner surface of the hole when the synthetic resin shaft is fitted into the hole. In order to obtain the shaft, it is possible to use a mold that is divided into two along the dividing line along the ball D, and to provide a molding device that can easily mold the shaft.

First, the synthetic resin shaft molded according to the present invention will be explained.

A hollow synthetic resin shaft 11 shown in FIGS. 5 and 6 is used, for example, as a minute needle, and has a large diameter portion 12 and a small diameter portion 13 projecting above and below a bearing portion 14 at its upper end. .

Reference numeral 15 denotes a minute hand gear. Elastic support arms 18, 18 are formed on the surface of this gear to face each other with a through groove 19, and the shaft hole 1 of the minute hand gear is formed in these arms. A space 16 slightly larger than this hole is suitable for the bag hole 17. The small diameter portion 13 of the shaft 11 is passed through the space 16, and the bearing portion 14 is opposed to the shaft hole 17. Furthermore, the minute hand gear 15 is connected to the ratchet 11 by aligning the bearing portion 14 with the shaft hole 17 by moving in the plane direction of the gear. When the bearing part 14 is fitted into the borehole 17, the elastic support arms 18, 18 are slightly bent outward, and after the fitting, elastically support the bearing part 14. Bearing part 1
As shown in FIG. 6, most of the outer circumferential surface located symmetrically with respect to the axis 0 is formed into arcuate surfaces 14a, 14a having a diameter approximately equal to the hole diameter of the ball hole 17, and also located symmetrically with respect to the center of the ball. The remaining portions of the outer circumferential surface located at are surfaces 14b, 14b located inward from the rotation locus of the circular arc surface. In the center portions of the minor warp faces 14b, burrs 20, 20 formed during molding of the shaft run in the direction of the ball. But plane 1
4b, 14b are located inward from the hole diameter of the enemy hole 17, so there is a burr 2 between the hole and these planes 14b, 14b.
Sufficient voids are formed to accommodate 0.0 and 20. Note that the planes 14b, 14b may extend not only to the outer circumferential surface of the bearing portion 14, but also to the entire minute hand shaft 11 including the large arm portion 12 in all directions. 21 is the minute hand kana.

Therefore, for example, the minute hand shaft can be reliably attached without distorting the minute hand gear 15 due to its flat surfaces 14b, 14b, and the slip mechanism constituted by the bearing portion 14 also operates stably.

Therefore, an apparatus for forming the minute hand shaft according to the present invention will be explained. As shown in FIGS. 7 and 8, the molding frame 22
, 23 are opposed to each other with an axis 24 as the center, and are divided into two by a parting line L in a positional relationship symmetrical to this axis along the wisteria direction.

The molding frames 22 and 23 are movable in the left and right directions. Furthermore, cavities 25 are formed on the degree surfaces of the formworks 22 and 23.
, 26 are provided. The cavities 25 and 26 have central inner wall surfaces 25a and 26a in the shape of an arc whose hole diameter is approximately equal to the hole diameter of the shaft hole 17 of the minute hand gear 15, and a central inner wall surface 25a and 26a that is continuous with the central inner wall surface and near the parting line L. Wall surface 25a
, 26a, and planar inner wall surfaces 25b and 26b located inward from the arcuate surfaces of the inner walls 25b and 26a. Of course, the arc-shaped central inner wall surface 25a corresponds to the outer shape of the arcuate surfaces 14a, 14a of the bearing portion 14 of the minute hand shaft 11, and the planar side inner wall surfaces 25b, 26b' correspond to the outer shape of the bearing portion of the minute hand shaft. This corresponds to the outer shape of the planes 14b, 14b. The burr that is formed protruding along the parting line L when forming the shaft is formed by the hole diameter of the central inner wall surfaces 25a, 26a, and the planar side inner wall surfaces 25b that are displaced inwardly from the hole diameter of the central inner wall surface. 26b, so that the tip does not protrude beyond the hole diameter of the central inner wall surfaces 25a, 26a.

Then, by joining the formworks 22 and 23, a cavity 25,
26 are closed to form a ball-shaped hollow part 27 inside. A large diameter recess 28 and a small diameter recess 2 are provided at the upper end of the hollow part 27.
9 are repositioned above and below the bearing recess 30. Reference numeral 31 denotes an injection port for molten synthetic resin provided in the formwork 22, and is suitable for the cavity 25.

Next, the method for forming the minute hand shaft 11 is as follows.

The formworks 22 and 23 are respectively moved and joined with the shaft 24 in between. As a result, a hollow portion 27 is formed inside, and a thermomolten synthetic resin is injected into this hollow portion through an injection port 31. After this synthetic resin has hardened, the formwork 22, 23
By dividing the material along the dividing line L, a synthetic resin dividing shaft 11 shown in FIG. 5 is molded and taken out. In the above example, the minute hand axis was explained, but it is not limited to this type of wisteria.

As described above, when the synthetic resin shaft molded by the device according to the present invention is fitted into the anchor hole, the burr formed during molding does not come into contact with the inner surface of the hole, so the shaft is always supported with the same slip torque. The mold is divided into two along a dividing line along the center of the mold, and only one mold is required, so the structure is simple and molding is easy.

[Brief explanation of drawings]

Figures 1 to 4 show conventional examples, Figure 1 is a sectional view of the formwork showing the state of use, Figure 2 is a sectional view taken along the line 0--B in Figure 1, and Figure 3 shows the relationship between the minute hand shaft and the formwork. FIG. 4 is a front view of the minute hand shaft, FIG. 5 is a partial cross-sectional front view of the shaft formed by the apparatus according to the present invention, and FIG. 7 is a front sectional view showing an embodiment of the present invention, and FIG. 8 is a sectional view taken along the W-skin line in FIG. 7. 14... Bearing portion, 14a... Arc surface, 14b... Plane, 15.
... Minute hand gear, 20... Burr, 22, 23... Formwork, 25, 26... Cavity, 27... Hollow part, L
... Parting line, 25a, 26a... Central inner hair surface, 25b, 26b... Side inner wall surface. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. It has a shaft portion with a substantially oval cross section consisting of opposingly located arcuate surfaces and an opposingly located plane located inward from the rotation locus of the said arcuate surfaces, and this shaft portion rotates in the shaft hole. A molding device for molding synthetic resin shafts that can be fitted together,
The formwork having a cavity corresponding to the outer peripheral shape of the synthetic resin shaft can be divided into two parts in the radial direction, and the parting-in is located at a position facing the inner wall surface of the cavity corresponding to the plane. Molding equipment for synthetic resin shafts.