JPS6349093Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of a mold for molding a rotor of an electromagnetic converter used in small electronic devices such as quartz watches.

[Conventional technology]

In recent years, there has been a strong demand for small electronic devices, especially quartz electronic watches, to be smaller, thinner, and have a longer lifespan.Therefore, converters are also using high-performance magnets as a means of achieving the above requirements. It is necessary to improve efficiency by reducing inertia. For this reason, the present applicant has, as an example,
-85311, the rotor magnet is insert molded and the rotor pinion, rotor stem, and magnet holding part are formed from a polymer material.
A so-called plastic rotor has been proposed. According to this plastic rotor, the magnet holding part also uses a polymer material with low specific gravity.
Since the inertia of the rotor can be made very small, it is possible to achieve high efficiency as a converter.

In order to mold such a plastic rotor, a so-called insert molding method is used, in which a permanent magnet is fixed in a mold and molten plastic is poured into the mold and solidified. is common.

There are various mold structures that can be used for this insert mold. For example, in order to absorb processing variations in the thickness of the permanent magnet, a storage recess that is deeper than the thickness of the permanent magnet is formed to connect the upper mold and the lower mold. A mold structure for molding an insert-molded rotor is conceivable by configuring the mating surface of the mold to be above the thickness of the permanent magnet.

[Problem that the invention attempts to solve]

However, according to the above configuration, the mold structure is affected in various respects, such as the relationship between the positioning structure of the permanent magnet in the mold and the holding part of the permanent magnet as a rotor, and the relationship between the runner connecting the upper and lower parts. must become complicated. On the other hand, if the mating surfaces of the upper mold and the lower mold are arranged in the middle of the thickness of the permanent magnet, problems such as chipping of the magnet and problems of burrs due to processing variations in the thickness of the permanent magnet will occur. Therefore, there is a need for a mold structure that is simple and easy to manufacture, taking into consideration the characteristics and shape of the rotor, and that can maintain the quality of the finished rotor.

The present invention was developed in view of the above points, and the purpose is to provide a mold structure for forming a plastic rotor that is easy to supply and process, and also allows for easy quality maintenance of the finished rotor. It is something.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1a is a partial sectional view of a molding die according to the present invention, and FIG. 1b is a plan view of the lower molding die viewed from above.

In FIG. 1, reference numeral 1 denotes an upper mold, and the upper mold 1 has a sprue 2, a concave portion 3 in the true shape of the rotor, a positioning portion 4, and a rotor fastening portion shape in which the tip 2a of the sprue 2 is provided. A recessed portion 5, etc., which forms part of the resin flow groove and serves as a resin flow groove, is formed.

Reference numeral 6 denotes a lower mold, and the lower mold 6 has a concave portion 7 in the true shape of the rotor, a concave portion 8 geared in the shape of a rotor pinion, and a rotor fastening portion shape that accommodates a rotor magnet 9, which will be described later. Concave part 1 that also plays a role
0, a knockout pin 11, etc. are provided.

The split surface A where the upper mold 1 and the lower mold 6 are joined coincides with the upper end surface of the rotor magnet 9, that is, the end surface 9b of the rotor magnet 9 on the side without the rotor pinion-shaped recess 8. Furthermore, the sprue 2 is at its tip 2a.
is a recessed portion 5 forming a part of the rotor fastening portion shape described above.
Therefore, there are three locations. That is, the tip 2a of each sprue 2 is attached to the upper mold 1 at a position substantially opposite to the knockout pin 11 shown in each recess 10 in the shape of a rotor fastening portion of the lower mold 6 (see FIG. 1b). It is provided. The above is the structure of the mold for molding a rotor according to the present invention.

Figure 2 shows the rotor molded by the mold shown in Figure 1, Figure 2a is a sectional view,
Figure b is a bottom view.

The manufacturing process of the rotor will be explained below with reference to FIG. 2. As shown in FIG. 1a, the rotor magnet 9 is set in the lower mold 6.

This rotor magnet 9 has protrusions 12, which are radial positioning guide parts, and protrusions 13, which are depth direction guide parts, provided on the lower mold 6 at three locations on the circumferential side surface 9a and both end faces 9b. (see FIG. 1b) and the positioning portion 4 of the upper mold 1 to position and hold the mold in the radial and thickness directions.

After the rotor magnet 9 is set in the lower mold 6 in this way, a softened polymer material, so-called resin, is poured from the sprue 2 to form the rotor 14, that is, the rotor stems 15, 16 and the rotor pinion 17 as shown in FIG. The rotor fastening portion 18 is integrally molded and the rotor magnet 9 is fixed within the rotor fastening portion 18 at the same time.

Next, the resin in the sprue 2 is drawn and the rotor fastening part 18
After cutting with a slight protrusion 19 left on the upper mold 1
is moved upward and the knockout pin 11 is further pushed upward to take out the molded rotor 14.

In this case, since the entire surface of the rotor magnet 9 is a rough surface with fine irregularities, the bonding force with the resin increases, and therefore the rotor magnet 9 itself does not move within the rotor fastening section 18.

By the way, in this application, the two molds are referred to as the upper mold and the lower mold, but it is clear that they do not necessarily have to be placed one above the other and include molds that are tilted horizontally. It is sufficient if the configuration is divided into two parts.

Furthermore, rotor magnets include those with a central hole and those without a central hole.

[Effect of idea]

As explained above, according to the present invention, the dividing surface A of the upper and lower molds is aligned with the end face of the rotor magnet on the opposite side to the rotor pinion, and the rotor magnet is set in the lower mold. Therefore, it is easy to set up the magnet supply, which is particularly effective for automatic supply.

Furthermore, by making the split surface coincide with the surface in the thickness direction of the magnet, it is easy to achieve mold alignment accuracy, and even if burrs occur, the mold can be easily repaired. In addition, the length of the magnet guide can be set sufficiently, and it is possible to stably hold the magnet and prevent the magnet from being broken due to misalignment of the mold when the split surface is provided within the thickness plane.

Furthermore, since the tip of the sprue is formed to match the resin flow groove, the flow of the resin is very good even in the case of a rotor, which is an ultra-small component such as a watch, and there is no need to rotate the sprue here and there as part of the mold. Since there is no such thing, the structure is simple.

By using such a mold, it is possible to mold a rotor with good dimensional accuracy, a small outer diameter size, and extremely low inertia because it is made of a polymer material, thereby increasing the efficiency of the converter. It was possible to achieve great results, such as making electronic equipment smaller, thinner, and longer lasting.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the present invention, Fig. 1a is a partial sectional view of a mold, Fig. 1b is a bottom plan view of Fig. 1a, and Fig. 2 is a mold shown in Fig. 1. FIG. 2a is a cross-sectional view and FIG. 2b is a bottom view. 1... Upper mold, 6... Lower mold, 2... Sprue, A
... split surface, 9 ... rotor magnet, 9a ... peripheral side of rotor magnet 9, 9b ... end face of rotor magnet 9, 15, 16 ... rotor stem, 17 ... rotor pinion, 18 ... rotor fastening section .

Claims (1)

[Scope of utility model registration request] In an insert molding mold structure for a rotor for an electromagnetic converter, in which the permanent magnet holding part and the rotor pinion part for transmitting rotation to the next stage are formed of a polymer material, the mold is an upper mold. a lower mold, the lower mold includes a permanent magnet storage recess having a guide part for positioning the lower surface of the permanent magnet in the axial direction and a guide part for positioning the radial side surface of the permanent magnet; A tooth-shaped dovetail recess for forming the rotor pinion part below the recess, a lower molding recess for forming a lower part below the pinion recess, and a radial guide part of the permanent magnet storage recess. a plurality of holding part molding recesses located further outside and having openings in the permanent magnet storage recesses;
A resin flow groove connecting the holding portion molding recess and the pinion is formed in the upper mold, and an upper mold is formed in the upper mold.
an upper molding recess for molding, and a resin flow groove connecting the holding part molding recess of the lower mold and the upper molding recess, and a resin flow groove connecting the lower mold and the front upper mold. A mold for a rotor for a converter, characterized in that a mating surface substantially coincides with the upper surface of the permanent magnet, and a tip of a sprue for injecting resin is opened in a resin flow groove of the upper mold. structure.