JPS624843B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic coil bobbin for a coil for small electric equipment such as an electromagnet.
In this type of plastic coil bobbin, as shown in FIGS. 4 to 6, the surface of the winding core 2 and the inner surface of the flanges 3a and 3b provided at both ends of the winding core, which are in contact with the coil conductor 8, are provided with a molding material. Separation line P of mold 4.
Since L is located in a direction perpendicular to the conductor winding direction, when the mold 4 is used many times, the separation line P of the coil bobbin 1 will become distorted due to the corner sagging of the mold separation surface.
A burr 6 was generated at the location where L was located, and as a result, the enamel film of the conductor was peeled off when the enamel conductor 8 was wound, resulting in an interlayer short circuit.

Conventionally, as a simple means to remove the burrs 6, the coil bobbin after forming is stirred with a walnut shot, that is, in a container containing light, hard, uneven pieces such as walnuts, to remove the burrs 6.
However, it is difficult to completely remove the burr 6 with this method alone, and
The base of the burr 6 remains at a certain height. Therefore, in order to completely remove it, it must be scraped off using a tool such as a file, which requires a large amount of man-hours.

In view of this point, the present invention is designed to allow use without any problem even if some burrs remain by simply removing them with a walnut shot.

That is, the present invention is characterized in that a groove is formed in the inner surface of the coil bobbin where the separation line of the mold is located, so that burrs generated on the bottom surface of the groove are accommodated within the groove. be.

Next, details of the present invention will be explained with reference to the embodiments shown in the figures. In Figures 1 to 3, 1 is a hollow winding core 2.
A coil bobbin made of phenolic resin or the like that has flanges 3a and 3b at both ends, and the separation line PL of the molding die 4 (only the slide core is shown) is located on the surface of the winding core 2 and the inner surface of the flanges 3a and 3b. 0.5 where
A groove 5 having a narrow width t of about 1 mm is provided, and its depth h is determined by the burr 6 formed on the bottom surface of the groove 5.
For example, it is set to about 0.2 mm so that it is deeper than the remaining height that could not be removed by rough cutting with a walnut shot or the like, that is, about 5/100 mm. To achieve this, protrusions 7 are provided at the corners of the separation surface of the mold 4.

This will result in an undercut with respect to the operating direction when the mold is released, but this is because the protrusion dimension of the protrusion 7 is very small, and when the mold is released, the rigidity of the plastic molded product is small, causing elastic deformation. Therefore, the coil bobbin will not be cut or cracked due to undercut.

In order to minimize the resistance caused by the undercut, a large radius of approximately 0.5 mm is provided on both side edges of the groove 5.

Since the present invention is configured as described above, a small burr that fits in the groove 5 can be left as is, and even a large burr can be simply removed using a walnut shot, etc., so that the tip of the burr can be connected to the coil conductor of the coil bobbin. It is possible to reliably prevent protrusion from contacting surfaces, eliminate the troublesome deburring work and reduce work man-hours, and eliminate the short-circuiting of the coil due to incomplete deburring, which improves reliability. can be improved. In particular, as in the embodiment, since the potential difference between the layers is large at the end face of the coil in contact with the inner surface of the collar of the coil bobbin, short-circuiting of the coil in this area can be effectively prevented.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a coil bobbin embodying the present invention, Fig. 2 is a sectional view of the burr-generating part of the coil bobbin collar, and Fig. 3 is a perspective view showing the relative position between the slide core of the mold and the molded product. , shows one slide core open. FIGS. 4, 5, and 6 are drawings showing conventional devices corresponding to FIGS. 1, 2, and 3, respectively. 1: Coil bobbin, 2: Winding core, 3a, 3b:
Tsuba, 4: mold, 5: groove, 6: burr, 7: protrusion, 8: coil conductor.

Claims (1)

[Claims] 1 The inner surface of the coil bobbin molded from resin etc.
A coil bobbin for electrical equipment, characterized in that a part of a molding die where a separation line is located is formed into a groove so that burrs generated on the bottom surface of the groove are accommodated in the groove.