JPH0698638B2 - Outsert molding method - Google Patents

Description

The present invention relates to a so-called outsert molding method in which a core metal mold is used to form a functional portion made of synthetic resin on a hard substrate.

[Conventional technology]

Synthetic resin parts are widely used as mechanical parts such as tape recorders and watches. Conventional mechanical parts are mainly made of metal plates made by press work, and functional parts such as gears, pulleys, cams and levers are incorporated through various shafts and bearings assembled by screwing and caulking. It was As materials for these functional parts, synthetic resins centered on so-called engineering plastics are widely used.

However, in recent years, a so-called outsert molding method in which a resin is embedded in a hard substrate by injection molding has been used in the manufacture of the above mechanical parts. According to this outsert molding method, various functional parts are fixed to the substrate, and functional parts such as gears, cams, levers and motors are assembled to these functional parts to form one mechanical part. This molding method is 1
Since a large number of various functional parts are fixed to the substrate at one time by one-time injection molding, the process and man-hours are drastically reduced, which contributes to rationalization, labor saving, cost reduction, and downsizing. It is also useful for weight reduction.

The outsert molding method is a method in which a processed hard substrate is attached to a mold and a synthetic resin is injection-molded in this mold, and various measures have been made by interposing the substrate. For example, when resin functional parts are connected and fixed to multiple points on the board by runners, the length of the runner must be long to prevent deformation of the board, cutting of the runner, or collapse of the functional parts caused by molding shrinkage of the runner. Restriction (Japanese Patent Publication Sho 55
-6496) and a runner in the notch of the board (Japanese Patent Publication No.
8-56508) Proposals have been made. Also, a method of providing rotating parts (JP-A-53-34053, JP-B-57-14304) and slide parts (JP-B-57-20486) on the substrate, and further, the contraction direction of the resin functional part fixed by a plurality of places Proposal to absorb the molding shrinkage by providing a hollow part at the fixed part toward
59-379) has also been done.

On the other hand, parts that are undercut in the mold opening / closing direction are widely used in order to set snap fit properties and various parts as a functional part fixed to a hard substrate.

For example, in the case where the resin function part 2 is fixed to the substrate 1 as shown in FIG. 9 (perspective view), the undercut part formed by the substrate 1 and the function part 2 is manufactured by EE in FIG.
As shown in FIG. 10 which is a sectional view taken along the line, a substrate 1 sandwiched between an upper mold plate 3 and a lower mold plate 4 and a cavity corresponding to a functional portion 2 filled with resin are slid in an arrow direction. This is possible with a mold having a structure having a moving slide core (I).

However, this method may damage the core of a normally used substrate during sliding, and requires high accuracy in the thickness and flatness of the substrate in order for the core and the substrate to slide smoothly. The material of the substrate is also limited, which is disadvantageous in manufacturing the substrate. Further, this method cannot be applied when there is another functional portion in the sliding direction of the core. Therefore, in outsert molding, which is characterized in that a large number of functional parts are formed on a substrate by a single injection molding, it is practically not worth applying this method.

In order to solve such a drawback, there is a method of using a substrate having a cutout hole and forming an undercut portion by a core penetrating the hole. The functional part shown in FIG. 9 obtained by this method is obtained as shown in FIG. 11 (perspective view),
The mold structure in the mold clamping state is as shown in FIG. 12 which is a sectional view taken along the line FF of FIG. 11 and FIG. 13 which is a sectional view taken along the line GG. In the figure, the core (II) is provided on the lower mold plate 4, and moves in the mold opening / closing direction simultaneously with the mold opening / closing, and penetrates into the notch hole of the substrate 1. The functional portion 2 having the undercut portion is formed by filling the space formed by the core (II) and the upper mold plate 3 with resin. The cavity (b) part in FIG. 13 helps prevent the functional part 2 from falling off the substrate 1, and the part (b) in FIGS. 12 and 13 is used when the core (II) penetrates into the substrate 1. Is a space filled with resin provided for the purpose of preventing the core (II) from being damaged by the substrate 1.

The advantage of this method is that the notch hole provided in the substrate is used as the passage and the core that moves in the mold opening and closing direction does not limit the movement of the core unlike the slide core method, and many undercut-shaped functional parts are used. This is because they are formed at the same time, and the substrate does not require high precision.

However, according to this method, the resin (a) filled in the peripheral portion of the cutout hole of the substrate does not act as a bonding force for fixing the functional portion to the substrate, and the molding shrinkage of the functional portion in the portion of Fig. 13 (b) is caused. Since it depends only on the tightening force due to, it is insufficient as a force for fixing the functional part.

As a method of solving the above-mentioned drawbacks, that is, a method of further increasing the bonding force of the functional part to the substrate, as shown in FIG. 14 (perspective view) and FIG. As described above, there has been proposed a method of covering the peripheral portion of the notch hole of the substrate with a U-shaped resin as shown in FIG. 16 (a sectional view of the portion (c) of FIG. 14) (Japanese Patent Publication No. 59-59- 49180). FIG. 17 is a sectional view taken along the line HH in FIG. 14 and FIG. 18 is a sectional view taken along the line I-I in FIG. In the figure, the core (II) is provided on the lower template 4 and is in a state of being penetrated into the substrate 1.
The space formed by the upper mold plate 3 and the lower mold plate 4 is filled with resin, and the whole or part of the peripheral portion of the cutout hole for increasing the fixed coupling force of the functional portion 2 and the functional portion to the substrate functions. A U-shaped portion (C) connected to the portion is formed. Usually 16th
By appropriately selecting the thickness t and the width w of the resin layer in the figure, it is possible to obtain a sufficient bonding force for fixing the functional portion to the substrate.

However, according to this method, the resin layer on the peripheral portion of the cutout portion causes the following defects due to the molding shrinkage of the resin. That is, in the peripheral portion of the cutout hole, the resin layer in which the voids of the core and the cutout hole are filled and the resin layers on both sides of the substrate are integrated and connected to the functional portion, so that the molding shrinkage of the resin does not occur. It works in the circumferential direction and the direction sandwiching the substrate. As a result, the size of the core filled in the peripheral portion of the notch hole, that is, the size of the hole is smaller than the core size, and it is difficult to obtain the size when the size accuracy is required for the hole, and the direction of pinching the substrate. Since the resin shrinks, residual stress is generated at the corners of the resin, which may cause damage during long-term use. This is schematically shown in FIGS. 19 and 20.

[Problems to be solved by the invention]

The present invention is made in view of the above circumstances, by using a core mold that penetrates the notched hole formed in the hard substrate, in a method of molding and imparting an undercut-shaped synthetic resin functional portion to the hard substrate. It is an object of the present invention to provide an improved method for coupling and fixing functional parts.

[Means for Solving the Problems] The method of the present invention is a synthetic resin having an undercut shape with respect to the mold opening / closing direction by a core mold that penetrates one notch hole formed in a hard substrate. In the method of molding and imparting the functional part to the hard substrate, when the synthetic resin functional part is coupled and fixed to the peripheral portion of the cutout hole, there is a gap of 0.2 mm or more between the core and the cutout hole, The resin is filled in the voids, and the resin is connected to the resin layer in the voids and bonded and fixed to one surface or the opposite surface of the substrate with a resin layer having a thickness of 0.2 to 5 mm and a width of 0.2 to 10 mm, and one surface of these substrates or The resin layers bonded and fixed to the opposite surface are alternately arranged in the peripheral portion of the cutout hole with respect to the cross section of the substrate.

The method of the present invention will be described with reference to the drawings.
It is obtained as shown in FIG. 2 (perspective view) and FIG. 2 (perspective view of FIG. 1 seen from the back side). The cross-sectional views of the mold for obtaining this product drawing are shown in FIG. 1, FIG. 3, FIG. 4, FIG. 5, and FIG. It is shown in FIG.

The core (II) is provided on the lower template 4. The hard substrate is provided with a cutout hole through which the core (II) penetrates. When the hard substrate is set between the upper mold plate 3 and the lower mold plate 4, the resin is filled in the space surrounded by the upper mold plate, the lower mold plate, the core and the substrate. Therefore, the part 2 is a synthetic resin functional part, the part (b) is a part fixing the functional part and the substrate, and t is the core (II).
The air gap size between the notch hole of a board | substrate and a board | substrate is shown. The portion (d) is a resin layer whose cross-sectional shape referred to in the present invention is L-shaped or inverted L-shaped, and in the example shown in FIG. 1, the surface of the substrate on which the resin functional portion is fixedly joined. Consists of four L-shapes formed in the space between the upper mold plate and five inverted L-shapes formed in the space between the opposite surface of the substrate and the lower mold plate. Has been done. The undercut-shaped functional portion is formed by the upper mold plate 3 and the core (II), the core (II) is provided on the lower mold plate, and the core (II) penetrates into the substrate. Since the sufficient cutout holes are provided, it is possible to easily form the undercut-shaped functional portion by the movement in the mold opening / closing direction.

According to the method of the present invention, the resin functional portion and the resin layer at the peripheral portion of the cutout hole are connected by the void portion provided between the core (II) and the cutout hole. The binding force for fixing the functional portion to the substrate is held by the scissor force between the L-shaped portion protruding on the upper surface of the substrate and the inverted L-shaped portion protruding on the lower surface. The advantage of the method of the present invention is that the resin layer on the substrate surface is alternately cut out on the upper surface and the lower surface of the substrate surface as compared with the case where the peripheral portion of the notch hole is covered with a U-shaped resin layer in cross section. That is, the circumferential molding shrinkage force acting on the upper surface and the lower surface is relaxed. The molding shrinkage force in the circumferential direction is the core (I
It acts only on the resin layer in the space between I) and the cutout hole, and the dimensions after the core (II) formed by this resin layer comes off can be easily obtained. Furthermore, when the U-shaped resin layer covers the peripheral edge of the cutout hole, a molding shrinkage force acts in the direction of pinching the substrate, and there is burrs on the peripheral edge of the cutout hole of the substrate, or a sharp cut surface. If it exists, there is a risk of so-called creep destruction that destroys the resin layer due to the notch effect, but in the case of the L-shaped shape according to the present invention, the sandwiching force with the residual stress on the substrate does not work and the creep destruction does not occur.

Further, as an advantage of the present invention, for example, as shown in FIGS. 7 and 8, the shape of the resin layer can be freely changed, and the fixing portion of the functional portion also adopts the fixing method of the peripheral portion of the cutout hole. There is a place where you can. Furthermore, the resin can be saved as compared with the case where the peripheral portion of the cutout hole is covered with a U-shaped cross section.

The combination of the L-shape and the inverted L-shape in the present invention is used in at least one pair. As a practical combination, the die is easy to process, and if the notch hole is rectangular and the functional part is fixed on one side, if an L-shaped part is used on one side that contacts the functional part, It is a method of adopting an inverted L-shape for the other opposite sides. The combination of L-shaped and inverted L-shaped is the size of the notch hole,
The number is selected according to the magnitude of the binding force for fixing the functional part.

Furthermore, in the method of the present invention, since the resin layer on the substrate surface of the peripheral portion of the cutout hole is cut out, even if the resin layer is largely projected on the substrate surface, it is not easily affected by the molding shrinkage of the resin. The layer thickness is 0.2 to 5 mm and the width is 0.2 to 10 mm, and the shape can be variously adopted such as rectangular, semicircular and triangular.

In outsert molding, a hard substrate having a thickness of 0.5 to 5 mm is usually used, and a notch hole is generally processed by pressing. According to the press work, the peripheral edge of the notch hole generally shows a rough surface with burrs and burrs.If the gap between the core and the peripheral edge of the notch hole is insufficient, the core may be damaged or It may not be possible to set.
In the present invention, between the core and the peripheral portion of the cutout hole of the substrate 0.2 ~ 5
A space of mm is provided to prevent accidents such as core damage, and it is practical because it does not require high precision for processing the substrate.

〔The invention's effect〕

As described above, the method of the present invention is particularly useful for molding and imparting a hard substrate with an undercut-shaped functional portion, but it is not limited to the undercut shape, and it is preferable to use a core. It can be widely applied to molding methods.

[Brief description of drawings]

The figures are as follows, respectively. 1 is a perspective view showing an example of a molded product obtained by the present invention. FIG. 2 is a perspective view of the molded product of FIG. 1 seen from the back side. FIG. 3 is a sectional view taken along the line AA of FIG. Fig. 4: Sectional view taken along the line BB of Fig. 1 Fig. 5: Sectional view taken along the line C-C of Fig. 6 Fig. 7: Sectional view taken along the line D-D of Fig. 7 Fig. 8: perspective view of the molded product of Fig. 7 seen from the back side Fig. 9: perspective view of an example of the undercut resin functional part 10 Fig .: E-E line sectional view of Fig. 9 Fig. 11: Perspective view showing one example of a molded product obtained by a conventional method in which a resin layer is provided on the peripheral portion of the cutout hole of the substrate using a core mold FIG. 12: FF line sectional view of FIG. 11 FIG. 13: GG line sectional view of FIG. 11 FIG. 14: U-shape on the periphery of the cutout hole of the substrate using the core mold Example of a molded product obtained by a conventional method in which a mold resin layer is provided Fig. 15: Perspective view of the molded product of Fig. 14 seen from the back side Fig. 16: Cross-sectional perspective view of the portion (c) of Fig. 14 Fig. 17: FF line cross section of Fig. 14 Fig. 18: Cross-sectional view taken along the line GG in Fig. 14 Fig. 19: Schematic plan view showing the situation when forming a U-shaped resin layer Fig. 20: Forming a U-shaped resin layer Schematic plan view showing the situation after the molding is performed. Incidentally, FIGS. 3 to 6, FIG. 10, FIG. 12, FIG. 13, FIG. 17, and FIG. 18 are diagrams for showing the situation at the time of molding. The mold and core not shown in the corresponding perspective view are also shown. The symbols in the figure respectively indicate the following: 1: substrate 2: resin functional part 3: upper mold plate 4: lower mold plate (a): gap between the notch hole of the substrate and the core that penetrates Resin layer (b): Resin layer or cavity provided for fixing the resin functional part to the substrate (c): U-shaped resin layer or cavity in cross section (I): Slide core (II): Core that penetrates the board notch hole t: Void dimension between the board notch hole and the penetrating core t ′: Thickness of resin layer w: Width of resin layer

Claims (1)

[Claims] 1. A core metal mold which penetrates one notch hole formed in a hard substrate to mold and impart a synthetic resin functional part having an undercut shape in the mold opening / closing direction to the hard substrate. In the method, when bonding and fixing the synthetic resin functional portion to the peripheral portion of the cutout hole, there is a gap of 0.2 mm or more between the core and the cutout hole, the portion of the gap is filled with resin, the gap Connected with the resin layer of the part of the substrate is bonded and fixed to one surface or the other surface of the substrate with a resin layer having a thickness of 0.2 to 5 mm and a width of 0.2 to 10 mm, and the resin layer bonded and fixed to one surface or the opposite surface of these substrates is An outsert molding method, characterized in that they are alternately arranged with respect to a cross section of a substrate at a peripheral portion of a notch hole.