JPS6253326B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder base for a videotape recorder, and more particularly, to a cylinder base for a videotape recorder, in particular, a cylinder base for a videotape recorder having a locally provided inclined surface on which a cylinder base for a videotape recorder, which is a separate part, is mounted in an inclined state on a plastic base. This invention relates to a cylinder base for a video tape recorder.

Conventionally, for example, in a video tape recorder, a video tape recorder cylinder (hereinafter simply referred to as a cylinder) is not attached directly to the chassis, but is attached to a subchassis fixed to the chassis; It was attached to the base. Since the sub-chassis requires strict dimensional accuracy and strength, a metal plate is used that has been press-formed with a hole through which the cylinder's bearing fixing part passes and a band-shaped hole for the tape guide. Made of aluminum die-cast finished product,
This cylinder base was fixed to the sub-chassis by screws or the like.

Such a sub-chassis has the drawback that it takes time to finish the cylinder base and screw the cylinder base to the sub-chassis, and since it is made of metal, there is a limit to how much weight it can be reduced.

For this reason, the applicant proposed a method of integrally molding the cylinder base and sub-chassis using plastic. However, the cylinder base is inclined with respect to the subchassis, and furthermore, requires a projection for positioning the cylinder thereon.

However, when a positioning protrusion whose side surfaces are perpendicular to each other is provided on the inclined surface of a plastic molded product, it is difficult to form the protrusion accurately by integral molding.

FIG. 1 shows a cross section of an example of a plastic base having positioning protrusions on an inclined surface, which the inventor investigated in the process of arriving at the present invention.
1 is plastic base, 2 is plastic base 1
3 is a sloping surface provided on a part of the sloping surface 2, and 3 is a positioning protrusion for positioning in a hole provided at the bottom of another component fixed on the sloping surface 2. It is. To mold this cylinder base for a videotape recorder, the second
A mold as shown in the figure is used. In this figure, the same parts as in Figure 1 are given the same reference numerals, 41 and 42.
5 is a mold body, and 5 is a slide core movable in the axial direction of the positioning projection 3 so that the undercut portion 6 (see FIG. 1) of the positioning projection 3 is not damaged. If such a mold is used, the mold body 41
When opening the mold bodies 41 and 42, first move the slide core 5 in the direction of arrow A, and then open the mold bodies 41 and 4.
2, it is possible to avoid damage to the undercut portion 6 of the positioning projection 3.

However, in this method, since the mold body 42 and the slide core 5 are designed to slide, a gap exists between them, and the accuracy of the positioning protrusion 3 deteriorates by this amount. Further, since both sliding surfaces are worn out, there is a problem that the accuracy of the positioning protrusion 3 gradually decreases. Furthermore, the mold body 42
Resin may flow into the gap between the slide core 5 and the mold opening/closing operation. others,
Since it is necessary to install the slide core 5 and its drive mechanism, the mold structure becomes complicated, and adjustment during use takes time, the mold processing process becomes longer, and the cost required for mold production increases. There are problems such as high prices. The molding cycle time also becomes longer due to the addition of the slide core drive time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cylinder base for a videotape recorder made of plastic that can easily achieve highly accurate cylinder positioning and avoid damage to the positioning projections.

The present invention provides a cylinder base for a video tape recorder in which an inclined surface on which a cylinder for a video tape recorder, which is a separate part, is mounted is formed as a part of a plastic base, and the separate part is mounted on the plastic base in an inclined state. , a protrusion that engages with a hole at the bottom of another component to position the other component is provided protruding from an inclined surface, and the side surface of the protrusion and the side surface of the hole are partially in line or surface contact to perform the above-mentioned engagement function. (i.e., the engagement part is the surface of the higher line of the slope for the protrusion), and the line or surface contact part is perpendicular to the slope (i.e., this contact part is the surface of the slope) The sides of the protrusion other than this contact point are at obtuse angles to the horizontal plane of the plastic base (i.e. the lower base surface of the slope). It is characterized by having a draft angle.

The present invention has been developed by considering the shape of the positioning protrusion,
This objective is achieved by creating a shape that can be molded with a normal mold that does not require a slide core, without reducing the positioning accuracy of the separate parts that are positioned on the inclined surface by the positioning protrusions. It is something to do.

Examples will be described below.

FIG. 3 shows a cross section of one embodiment, showing a state in which separate parts are positioned. 1 is a plastic base; 2 is an inclined surface provided on the plastic base 1 for mounting the separate component 7; 31 and 32 are holes provided on the inclined surface 2 and provided at the bottom of the separate component 7; This is a positioning protrusion for positioning the separate component 7 by engaging with the positioning hole of the separate component (hereinafter referred to as a positioning hole of the separate component). One side of each of the positioning protrusions 31 and 32 is perpendicular to the inclined surface 2, and the remaining portion of the side surface is provided with a draft angle. Therefore, a portion of the side surface of the positioning hole of the separate component 7 and a portion of the side surface of the positioning protrusions 31 and 32 come into contact with each other as shown by B in FIG. 3, so that the mounting position of the separate component 7 can be accurately determined. can be determined.

Figure 4 shows a method for forming a cylinder base for a videotape recorder having such a shape.
41 and 42 are molds, and the molds are opened and closed in the direction of arrow C. In this case, since draft angles are provided on the side surfaces of the positioning projections 31 and 32, even if the molds 41 and 42 are opened in the direction of arrow C, the undercut portions of the positioning projections 31 and 32 will not be damaged. . Therefore, there is no need to use a slide core as in the conventional technology, and molding can be performed by simply opening and closing the mold in a fixed direction, which eliminates the reduction in accuracy, wear of the mold, and complication of the mold structure due to the installation of the slide core. It can be avoided. Furthermore, compared to the conventional technology using a slide core, the mold processing process is shorter and the manufacturing cost thereof is lower. Furthermore, since there is no need to drive the slide core, the molding cycle time can be shortened.

5 and 6 show other embodiments, in which a is a sectional view and b is a plan view showing the engagement relationship between the positioning protrusion and the positioning hole of a separate component. In these figures, the same reference numerals are given to the parts corresponding to those in Fig. 3 (also in the following figures, the same reference numerals are given to the corresponding parts in each figure). The differences from the embodiment in Figure 3 are as follows:
In the embodiment shown in FIG. 5, the cross-sections of the positioning protrusions 31 and 32 are elliptical, and in the embodiment shown in FIG. 6, the cross-sections of the positioning protrusions 31 and 32 are semicircular. Since two positioning protrusions are provided, the positioning holes 81 and 82 of the separate component 7 and part of the side surfaces of the positioning protrusions 31 and 32 come into contact with each other at two places, allowing for accurate positioning. In this case, since the side surfaces of the positioning protrusions 31, 32 and the positioning holes 81, 82 are in a state close to line contact, at least two positioning protrusions are required for accurate positioning.

7 and 8 show still another embodiment, in which a is a sectional view and b is a plan view showing the engagement relationship between the positioning protrusion and the positioning hole of another part, and this embodiment However, Figures 3, 5 and 6
The difference from the illustrated embodiment is that the positioning protrusion 31
Since the cross-sectional shape of is rectangular, as shown in Fig. 7,
When the cross-sectional shape of the positioning hole 81 of the separate part 7 is circular, the rectangular corner of the positioning projection 31 contacts the positioning hole 81 at two places, and as shown in FIG. 8, the cross-sectional shape of the positioning hole 81 is rectangular. In some cases, there is surface contact at the contact surface D. Therefore, when a positioning protrusion having such a shape is provided, positioning can be performed with high accuracy by providing at least one positioning protrusion.

FIG. 9 shows yet another embodiment in which the positioning projections are formed using metal inserts instead of being integrally molded with the plastic base, and 91 and 92 indicate the metal inserts. A similar effect can be obtained by forming the metal inserts 91, 92 to have the same shape as the positioning protrusion described above.

10 to 14 show other different embodiments, in which a is a plan view and b is a sectional view. Although the positioning protrusions of the separate parts mounted on the inclined surface are not shown in these figures, the state in which they are attached to the inclined surface is exactly the same as in FIGS. 3 to 9. Figure 5~
In the embodiment shown in Fig. 9, the inclined surface is formed as a continuous surface, whereas in these embodiments, the inclined surface is provided at the tip of a plurality of plate-shaped protrusions or circular cross-section protrusions, and each inclined surface is formed as a continuous surface. The surfaces are included in the same plane, and the slanted surface referred to in the present invention includes such cases. That is, in the embodiment shown in FIG.
11, 212, 213, and 214 (not shown) form an inclined surface on which other parts can be mounted, and in the embodiment shown in FIG. 221 and 222 form an inclined surface. In addition, in the embodiment shown in FIG.
In the embodiment of FIG. 13, the inclined surfaces 241, 242 of the two projections 141, 142 each having a circular cross section form an inclined surface. Furthermore, in the embodiment shown in FIG. 14, the inclined surface 251 of the projection 15 having a circular cross section is
The recess 252 provided in the plastic base 1 forms an inclined surface. In these cases, the positioning protrusion may be installed on the tip inclined surface of any plate-like protrusion or circular cross-section protrusion, and if two or more positioning protrusions are installed, the positioning protrusion may be installed on the tip of the same plate-like protrusion or circular cross-section protrusion. Even if installed on a slope,
They may be provided on separate distal end slopes.

That is, in the cylinder base for a videotape recorder described in the embodiment, the molded product can be taken out by simply opening an ordinary mold in one direction without the need to install a slide core. Therefore, the mold structure is simplified and the time required for adjustment during use of the mold is shortened. Moreover, with the simplification of the mold structure, the mold manufacturing process is simplified and manufacturing costs are reduced. Furthermore, since there is no sliding between the slide core and the mold body, there is no wear on the relevant parts, and the life of the mold is extended. From the perspective of the molded product, when a slide core is used as in the conventional technology, there is a large drop in accuracy and variation due to displacement within the sliding gap between the slide core and the mold body. This drawback is improved. In addition, since a slide core is not used, there is no resin flowing into the gap between the slide core and the mold body.
The occurrence of burrs on the molded product due to the presence of the slide core is eliminated, and troubles during mold operation are eliminated. Further, since only a portion of the side surface contacts the positioning hole of another component mounted on the positioning protrusion, it becomes easier to achieve mold accuracy.

Therefore, even when a cylinder base and a sub-chassis for a video tape recorder are integrated, the problem is eliminated, and it can be widely used when it is necessary to fix separate parts to an inclined surface.

As described above, the cylinder base for a video tape recorder can be molded with high accuracy using a mold that does not require a slide core, and it is possible to provide a cylinder base for a video tape recorder that has a positioning protrusion with good positioning accuracy on the inclined surface. This has great industrial effects.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an example of a plastic base having positioning protrusions on an inclined surface, and FIG. 2 is for explaining a conventional method of forming a cylinder base for a videotape recorder having the structure shown in FIG. 3 is a sectional view of an embodiment of the cylinder base for a videotape recorder of the present invention, and FIG.
Similarly, a cross-sectional view for explaining the formation method, No. 5
6, 7, and 8 similarly show different embodiments. In each figure, a is a sectional view, b is a plan view of the main part of a, and FIG. Similarly, cross-sectional views of other embodiments, FIGS. 10, 11, and 1
2, FIG. 13, and FIG. 14 similarly show different embodiments, and a in each figure is a plan view;
b is a sectional view. 1...Plastic base, 2,211,212,
213, 221, 222, 231, 232, 23
3,241,242,251,252...slanted surface,
31, 32... Positioning protrusion, 7... Separate part, 81,
82... Hole (positioning hole) provided at the bottom of another part, 91, 92... Metal insert.

Claims (1)

[Claims] 1. A cylinder base for a video tape recorder, in which an inclined surface on which a cylinder for a video tape recorder, which is a separate part, is mounted is formed as a part of the plastic base, and the separate part is mounted on the plastic base in an inclined state. A protrusion that engages with a hole at the bottom of the separate component to position the separate component is provided protruding from the inclined surface, and a side surface of the protrusion and a side surface of the hole are partially in line or surface contact to form the engagement. and the line or surface contact portion thereof is perpendicular to the inclined surface, and the side surface of the protrusion other than the contact portion is a cutout that is at an obtuse angle with respect to the plastic base surface on the lower side of the inclined surface. A cylinder base for a video tape recorder, characterized in that it has a slope.