JP3108745B2 - Insulated shaft with flat surface for rotating electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating shaft with a flat surface used for a rotary electronic component.

[0002]

2. Description of the Related Art Generally, a rotary electronic component rotatably supports an insulating shaft between a substrate provided with a desired ring-shaped sliding contact pattern (resistor pattern or switch pattern) and a case. A slider attached to one end is brought into sliding contact with a sliding contact pattern, and a knob is attached to a tip of an insulating shaft protruding from the case.

FIG. 5 is a view showing an example of a conventional insulating shaft of this type. FIG. 5A is a perspective view, and FIG. 5B is a sectional view taken along line aa of FIG. (However, the description of the slider mounting portion 83 is omitted). As shown in the figure, a conventional insulating shaft 80 has a substantially disk-shaped slider mounting portion 83 for mounting a slider of a rotary electronic component at one end of a cylindrical shaft main body 81, The other end of the main body 81 is provided with a flat surface 85 whose outer peripheral side is cut over a predetermined length to form a knob mounting portion 87. The insulating shaft 1 is integrally formed of a synthetic resin.

The slider mounting portion 8 of the insulating shaft 80
A metal slider (not shown) is attached to the lower surface of the bracket 3, and a knob (not shown) is fitted to the knob mounting portion 87.

The flat surface 85 serves to prevent the fitted knob from rotating in the rotation direction. Therefore, the flat surface 85 is required to be as flat as possible. The shaft body 81 is cylindrical,
Since the knob is fitted on the outer periphery, it is required that the outer peripheral surface be as close as possible to a perfect circle in order to smoothly insert the knob.

[0006]

However, when the above-mentioned conventional insulating shaft 80 is molded, there are the following problems.

[0007] A portion which is located at the center of the flat surface 85 and is directed toward the rotation center axis (the dotted hatched portion 85 shown in FIG.
As shown in FIG. 5B, the portion (a) is slightly recessed.

When such a depression 85a is generated, when the knob is fitted to the knob mounting portion 87 of the insulating shaft 80 and the knob is turned, the torque is concentrated on both ends 91, 91 of the flat surface 85. It is not preferable.

The reason why the recess 85a occurs is considered as follows. That is, the insulating shaft 80 is manufactured by filling the mold resin with the heat-melted mold resin. When the filled mold resin cools and gradually solidifies, its volume shrinks slightly. Then, the insulating shaft 80 is reduced by the volume to be contracted.
Surface shrinks (so-called "sink" occurs).
In particular, sinkage is most likely to occur on the flat surface 85 due to the difference in shape and non-uniformity of solidification of the resin, as compared with other arc-shaped portions.

In particular, the root portion 93 of the flat surface 85 (FIG. 5)
(See (a)) The sink marks in the vicinity are large, but this is due to the portion 95 of the shaft body 81 where the flat surface 85 is not formed.
This is because the influence of sink marks due to volume shrinkage of the (true columnar portion) appears in this portion.

On the other hand, in order to prevent the recess 85a from being formed on the flat surface 85, the cooling time of the mold resin filled in the mold may be increased. As a result, the volume contraction due to the cooling is performed not gradually but gradually, so that the recess 85a of the flat surface 85 can be reduced to some extent.

However, if the cooling time is lengthened, the manufacturing efficiency is reduced. For example, if the insulating shaft 80 having the shape shown in FIG. 5 and having a diameter of the shaft body 81 of 6 mm is to be molded so that the flat surface 85 does not have the dent 85a, the cooling time is about 14 seconds or more. Required. On the other hand, when an insulating shaft having the same shape and dimensions but no flat surface 85 is molded, even if the cooling time is set to about 6 seconds, no dent due to sink occurs on the surface. In addition, even if the cooling time is lengthened in this way, the unevenness between the products is large and the dent 85a may still occur depending on the product, and it is difficult to prevent the occurrence of the dent 85a by changing the molding conditions. Was.

According to the above conventional example, the shaft main body 81
The roundness of the axis of the outer peripheral surface is not good. That is, an error between the diameter X in the vertical direction and the diameter Y in the horizontal direction of the shaft main body 81 shown in FIG.

More specifically, when the design dimension of the diameter of the shaft main body 81 is 6 mm, the dimension X is smaller than the dimension Y, and an error of 0.02 mm or more occurs between the two dimensions. At this time, the thickness Z of the portion where the flat surface 85 was provided also had a large error (0.04 mm or more) from the design dimension.

As described above, when a large error occurs in the X, Y, and Z dimensions and the roundness of the shaft is impaired, when the knob is attached to the knob attaching portion 87, play occurs between the knob and the knob attaching portion 87. Or the knob does not enter the knob mounting portion 87.

This phenomenon is caused by the concentration of sink marks on the flat surface 85 of the shaft body 81, and the vertical dimension Z or X
Is considered to be caused because the thickness becomes relatively thinner than the horizontal dimension Y.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object the purpose of making it difficult for the flat surface of the shaft body to be dented, and to shorten the cooling time during molding to improve the production efficiency. It is an object of the present invention to provide an insulating shaft with a flat surface of a rotary electronic component which can improve the roundness of the shaft.

[0018]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a method of cutting an outer peripheral surface of a substantially cylindrical shaft main body over a predetermined length parallel to a rotation center axis of the shaft main body at one end side thereof. In the insulating shaft with a flat surface of a rotary electronic component integrally formed of synthetic resin, a flat surface is provided and a knob mounting portion is provided. It was configured with a groove extending toward it.

[0019]

According to the present invention, since a groove is provided in advance in a portion where the surface of the flat surface is likely to be dent during molding, the surface of the flat surface other than the portion provided with the groove is sinker. It becomes difficult. If a concave groove is provided in the flat surface, the area of the flat surface is reduced correspondingly, but the remaining flat surface can be reliably flattened.

The provision of the concave groove makes it difficult to cause sink marks on the flat surface, so that the dimension in the direction perpendicular to the flat surface is hardly reduced, so that the roundness of the shaft on the outer peripheral surface of the shaft main body is improved.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a view showing an insulating shaft 1 with a flat surface according to one embodiment of the present invention. FIG. 1 (a) is a perspective view, and FIG. 1 (b) is a sectional view taken along line AA of FIG. 1 (a). However, the description of the slider mounting portion 13 is omitted).

As shown in FIG. 1, the insulating shaft 1 is formed by integrally molding a synthetic resin, and its structure is such that a substantially disk-shaped slider is attached to one end of a substantially cylindrical shaft body 11. Forming a portion 13, and a rotation center axis L of the shaft body 11 on the other end side of the shaft body 11.
By providing a flat surface 15 whose outer peripheral side surface is cut over a predetermined length in parallel with the
Is formed.

In the present invention, the center of the flat surface 15 is placed on the shaft surface 11 on the flat surface 15.
The groove 19 extending in the direction of the rotation center axis L is provided. The concave groove 19 is provided over the entire length of the flat surface 15.

The concave groove 19 is used to make the surface of the flat surface 15 less prone to sink marks by preliminarily denting a portion where the concave portion 85a may be formed in the conventional example, and to make the surface flat. Things.

As described above, the grooves 19 are formed in the flat surface 15.
Is provided, the area of the flat surface 15 is reduced accordingly, but the remaining flat surface 15 can be reliably flattened, so that the recess 85a does not occur on the flat surface 85 over a wide area unlike the conventional example. All the planes other than the concave groove 19 of the flat surface 15 are in contact with the inner surface of the hole of the knob (not shown) fitted to the knob mounting portion 17. Therefore, the mechanical strength at the time of turning the knob is improved.

The provision of the concave groove 19 makes it difficult to cause sink marks on the surface of the flat surface 15, so that the vertical dimension Z or X is hardly reduced. Therefore, it is almost the same as the lateral dimension Y, and the roundness of the shaft on the outer peripheral surface of the shaft main body 11 is improved.

FIG. 2 is a view showing the results of measurement of the dimensions of each part when the same dimensions of the flat-surfaced insulating shaft 1 shown in FIG. 1 and the flat-surfaced insulating shaft 80 shown in FIG. 5 are molded. It is.

As shown in the drawing, the product of the present invention is within the standard dimensions in all of the X dimension, the Y dimension, the roundness of the shaft, and the Z dimension. As described in connection with the problem to be solved by the invention, the X dimension is smaller than the Y dimension, and the Z dimension is also reduced due to the sink mark.

In contrast, in the case of the product of the present invention, a concave portion caused by sink marks could not be visually confirmed on the flat surface 15, whereas in the case of the conventional product, a concave portion could be visually confirmed on the flat surface 85.

The product of the present invention had the above-mentioned molding result in a cooling time of 6 seconds, whereas the conventional product had a molding time of 14 seconds.
The molding result as described above was obtained over a period of seconds.

As described above, the effect of providing the concave groove 19 on the flat surface 15 is great. The reason why the provision of the concave groove 19 makes the flat surface 15 less likely to be affected by sink marks is as follows. This is probably due to the reason.

That is, the portion of the shaft body that is in contact with the mold, that is, gradually cools from the surface toward the inside, whereas the portion of the conventional shaft body 81 provided with the flat surface 85 is shown in FIG. ), The whole is thick, so that a high-temperature portion exists at the center thereof. Since the thickness of the conventional shaft main body 81 where the flat surface 85 is provided is not uniform from the central portion, the influence of the sink is concentrated on the flat surface 85 during cooling.

On the other hand, the portion where the flat surface 15 of the shaft main body 11 of the present invention is provided is provided with the concave groove 19 in advance, so that the thick portion disappears as shown in FIG. The portions are also almost the same thin portions only. Therefore, the high-temperature portion does not concentrate at one place as in the conventional example, but exists thinly in a linear shape (C-shape). Therefore, the heat is uniformly radiated to both the portion where the flat surface 15 is provided and the other arc-shaped portions, and the resin solidifies substantially uniformly as a whole.

Therefore, it is considered that sinks do not concentrate on the flat surface 15 and the influence of sinks does not easily occur on the flat surface 15. Further, since the whole is thin, the cooling time can be shortened.

In the embodiment shown in FIG. 1, the concave groove 19 is provided over the entire length of the flat surface 15, but the present invention is not limited to this. It may be provided over the length. In particular, it is effective to provide it near the root 21 (see FIG. 1A) of the flat surface 15 where the influence of sink marks is most likely to occur.

The shape of the groove 19 is not limited to the shape shown in FIG. 1B, and various modifications are possible, for example, as shown in FIG. 4, a groove 19 'having a U-shaped cross section. It is.

In the above embodiment, the slider mounting portion 13 is provided at one end of the shaft main body 11, but a member to which the slider is mounted is mounted on the end instead of directly mounting the slider. Various modifications are possible, and it is essential only that the end be provided with a sliding contact mechanism.

[0038]

As described above in detail, the insulating shaft with a flat surface of the rotary electronic component according to the present invention has the following excellent effects. The flat surface of the shaft body is less likely to be dented.

The roundness of the shaft of the shaft body is improved.

The cooling time during molding can be shortened, and the productivity can be improved.

By providing the concave grooves, the amount of resin used can be reduced.

[Brief description of the drawings]

FIG. 1 is a view showing an insulating shaft 1 with a flat surface according to one embodiment of the present invention, wherein FIG. 1 (a) is a perspective view, and FIG. 1 (b) is a sectional view taken along line AA of FIG. 1 (a). (However, the description of the slider mounting portion 13 is omitted).

FIG. 2 is a diagram showing the results of measuring the dimensions of each part by molding the same dimensions of the insulating shaft with flat surface 1 shown in FIG. 1 and the insulating shaft with flat surface 80 shown in FIG.

3 (a) and 3 (b) show a difference in wall thickness between a portion of the shaft main body 11 of the present invention where a flat surface 15 is provided and a portion of the conventional shaft main body 81 where a flat surface 85 is provided. FIG.

FIG. 4 is a sectional view showing another embodiment of the concave groove 19 '.

5 (a) is a perspective view, and FIG. 5 (b) is a sectional view taken along line aa of FIG. 5 (a) (where a slider mounting portion is shown). 83 is omitted).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulated shaft with flat surface 11 Shaft main body 13 Slider mounting part 15 Flat surface 17 Knob mounting part 19, 19 'Groove L Rotation center axis

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-51-48120 (JP, A) JP-A 49-16742 (JP, U) JP-A 50-144937 (JP, U) JP-A 50-144 98230 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01C 10/00

Claims (1)

(57) [Claims] 1. A knob mounting portion having a substantially cylindrical shaft body provided with a flat surface at one end side, the outer peripheral surface of which is cut over a predetermined length in parallel with the rotation center axis of the shaft body. An insulating shaft with a flat surface of a rotary electronic component integrally formed of a synthetic resin, wherein the flat surface is provided with a groove extending substantially in the center of the flat surface toward a rotation center axis direction of the shaft body. An insulated shaft with a flat surface for a rotary electronic component, characterized in that: