JPH0528967B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an improvement in the leg rubber of an instrument made by double molding different resin materials.

<Conventional technology> Conventionally, this type of leg rubber was developed in 1983.
According to Publication No. 154657 and Publication of Utility Model Application No. 59-28350,
A device is known that consists of a primary molded part made of hard resin that is attached to the lower surface of the device, and a secondary molded part made of soft resin that projects downward from the lower surface of the primary molded part and comes into contact with the mounting surface.

An annular recess with an open bottom surface is formed in the bottom wall surface of the primary molded part, and a continuous hole is provided through the bottom wall vertically, and the annular recess is filled with a soft resin. Then, the resin is passed through the through hole to the opposite side of the bottom wall, and the secondary molded part has a sandwich structure in which the bottom wall of the primary molded part is sandwiched between the upper and lower sides to connect the two parts.

<Problem to be solved by the invention> However, the conventional double molding method for leg rubber has a sandwich structure, which makes the structure of the mold, especially the secondary mold, complicated. Not only does the manufacturing cost of the mold become high, but also the number of parts molded by the mold cannot be increased, resulting in high molding costs.

In addition, because the soft resin is forced to pass through the hole in the primary molded part to the opposite side of the bottom wall, a depressed resin sink area is created on the outer surface of the secondary molded part, which impairs the appearance of the product. .

<Means for Solving the Problems> Therefore, the present invention solves the above problems, and includes a hollow frame-shaped main body having a bottom wall, and a mounting leg that integrally projects upward from the main body. The main body includes an annular protrusion that frames the lower surface of the bottom wall, an annular protrusion with a triangular cross section that is provided downward in multiple layers inside and outside the recess surrounded by the annular protrusion, and a primary molded part molded from a hard resin, having a gate part formed by cutting out a flange of the flange, and an introduction groove communicating with the gate part and extending radially across the annular protrusion; It fills the inside of the recess through the gate part and the introduction groove to bury the annular protrusion part, and is molded with a soft resin having a higher melting temperature than the resin of the primary molding part that protrudes flatly downward from the annular protrusion. The surface of each annular protrusion of the primary molded part and the inner peripheral surface of the annular protrusion are melted with a soft resin when molding the secondary molded part, and the secondary molded part is It is characterized by being welded and integrated with the molded part.

<Embodiment> Figures 1 to 4 show one embodiment of the present invention, and in the figure, 1 indicates a leg rubber that is attached to the bottom of an appliance (not shown) such as an electric appliance or furniture. ,
As shown in FIGS. 2 and 3, these leg rubbers include a primary molded part 3 made of hard resin that is attached to the bottom panel 2 of the instrument, and a downward protrusion from the lower surface of this primary molded part 3, and a mounting surface. 4 and a secondary side molded part 5 made of soft resin such as rubber.

The primary molded portion 3 is molded using a relatively hard thermoplastic resin, such as polypropylene having a melting temperature of about 165 degrees.

Next, to explain the external shape of the primary side molding part 3, as shown in FIGS. Bottom panel 2 of the appliance raised integrally from
It consists of a mounting leg part 7 that can be attached with one touch.

As shown in FIG. 4, the main body portion 6 has an annular protruding edge 8 that frames the periphery of the lower surface of the bottom wall 9,
A circular recess 10 with an open lower surface is formed inside surrounded by this protrusion 8. And this recess 10
A protrusion 11 that protrudes downward from the lower surface of the bottom wall 9 is formed inside.

The protrusion 11 has a height slightly lower than the protrusion 8, and has a triangular central protrusion 11a with an acute angle cross section at the center of the recess 10, and an annular surround around the central protrusion 11a. The annular protrusion 11b has an acute triangular cross section and is formed in four layers on the inner and outer sides at approximately equal intervals.

Further, a secondary side gate part 12 is formed on the projecting edge 8 by partially cutting out a part in a U-shape from the lower end thereof, and a secondary gate part 12 is formed from the lower end thereof, and a gate part 12 extends from the gate part 12 to cross each of the annular protrusions 11a and 11b in the radial direction. , gate part 1
An introduction groove 13 having a width substantially equal to the width of 2 is formed.
Then, the annular protrusion 1 on the opposite side to the introduction groove 13
A gas vent hole 14 vertically penetrating the bottom wall 9 is formed within the interval 1b.

As shown in FIGS. 2 and 4, the mounting leg portion 7 is
A tapered guide pin 15 rises from the center of the bottom wall 9, and a tapered guide pin 15 protrudes from both sides of the guide pin 15 to face each other, is slightly lower than the guide pin 15, and is elongated vertically in a plate shape. It consists of a pair of rectangular leg pieces 16, 16. Each of the leg pieces 16 is provided with a pair of engagement grooves 17, 17 cut out in a U-shape from both sides in the middle of its length, and the lower edge of the engagement groove 17 is attached to the upper edge of the main body 6. At the same time, the vertical interval is made to approximately match the thickness of the bottom panel 2 of the instrument. Further, on the outer surface of the distal end of the leg piece 16, a tapered surface 18 which is inclined diagonally upward is formed by gradually reducing the thickness toward the distal end.

On the other hand, the secondary molded part 5 has a melting temperature higher than that of the primary thermoplastic resin, preferably about
It is molded using a thermoplastic resin that melts at a high temperature of about 70 to 105 degrees, such as an elastomer with a melting temperature of about 270 degrees. To explain its external shape, it fills the inside of the recess 10 of the main body 6 of the primary molded part 3, embeds the annular protrusions 11a and 11b, and extends below the lower end of the protrusion 8 of the main body 6. It is raised in the shape of a disc, and its lower surface is flat and almost horizontal (Figures 1 and 3).

Next, to explain the molding procedure, first, an injection mold (not shown) for forming the primary molded part 3 is manufactured with the above configuration, and a molten raw material of hard resin is injected into this mold. The primary molded part 3 is molded.

On the other hand, an injection mold (not shown) for forming the secondary side molded part 5 is manufactured, and with this mold opened, the primary side molded part 3 previously molded inside the mold is manufactured.
After fitting and closing the mold, a molten raw material of soft resin is injected into the mold from the position of the gate portion 12.

The injected molten raw material of the soft resin enters the recess 10 from the gate part 12 of the primary molding part 3, passes through the introduction groove 13 of the annular projections 11a and 11b, and enters the inside of the central annular projection 11a and the central projection. between the portion 11a and the innermost annular protrusion 11b, between adjacent annular protrusions 11b, and the outermost annular protrusion 11.
b and the inner surface of the ridge 8, respectively. At this time, since the melting temperature of the soft resin on the secondary side is set higher than the melting temperature of the hard resin on the primary side, the heat of the molten raw material of the injected soft resin is used to form the primary molded part 3. Each annular protrusion 11a, 11b and the inner surface of the protrusion 8 are melted, and when hardened again, they are welded to the secondary molded part 5 (FIG. 1).

In particular, since each of the annular protrusions 11a and 11b has an acute triangular cross section, the thermal conductivity is high.
The welding effect is significant. In addition, each annular protrusion 1
The welding area is significantly expanded by 1a and 11b,
The bonding force between both molded parts 3 and 5 can be made strong.

Note that the gas vent hole 14 of the primary molded part 3 is also filled with the molten raw material, but this hole 14 is only for gas venting, and the molten raw material passes through the hole 14 to the bottom wall 9. Make sure it doesn't go around the top.

Next, to explain how to attach the leg rubber 1 formed in this way to a device, first, the bottom panel 2 of the device
As shown in Fig. 2, the central guide pin 15
A circular through hole 19 through which the leg rubber 1 is inserted, and a pair of attachment holes 20 into which each leg piece 16 is fitted are formed on both sides of the hole 19 in correspondence with the attachment position of the leg rubber 1, respectively. The mounting hole 20 is located a little inside the opposing interval between the leg pieces 16, and has a wide rectangular first opening 20a through which each leg piece 16 bends slightly inward and passes through, and both sides of the first openings 20a. The openings 20a are narrower than the first openings 20a into which the engagement grooves 17 of the leg pieces 16 fit,
It consists of a first opening 20a and a rectangular second opening 20b that communicate with each other.

To attach the leg rubber 1, it is sufficient to align the guide pin 15 with the through hole 19 and the leg pieces 16 with each attachment hole 20, respectively, and push them firmly from below.

As a result, the tapered surfaces 18 on the outer surfaces of the tips of both leg pieces 16 come into contact with the outer edges of the first opening 20a, and when pushed in strongly, the distance between the tips of both leg pieces 16 becomes smaller due to the action of the tapered surfaces 18. It narrows inward and passes through the first opening 20a. Then, push the leg rubber 1 until it touches the bottom surface of the bottom panel 2.
Both leg pieces 16 open outward to the left and right due to their elastic restoring force, move from the first opening 20a to the second opening 20b, and the engagement groove 17 of the leg piece 16 fits into the second opening 20b. The leg rubber 1 is fixed to the lower surface of the bottom panel 2 of the instrument (Fig. 3).

<Effects of the Invention> As explained above, according to the present invention, when molding the secondary molded part with a soft resin, the annular protrusion of the primary molded part is partially melted by the heat of the soft resin, and the secondary molded part is melted by the heat of the soft resin. Since it is welded to the side molded part, the bonding force between both molded parts is extremely strong.

Furthermore, since the bottom wall of the primary molding part does not have a through hole, the structure of the mold for molding becomes simple. In addition, since the secondary molding part is molded overlappingly on the bottom wall of the primary molding part, the mold for the secondary molding part can also have a simple structure.

Furthermore, there is no sinkage of the resin on the outer surface of the secondary molded part, and the appearance of the product is not impaired.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a partially cutaway perspective view, FIG. 2 is a perspective view when installed, FIG. 3 is a side view showing the installed state, and FIG. 4 FIG. 2 is a perspective view showing a part of the primary molded part in cross section. 1 is a leg rubber, 3 is a primary side molded part, 5 is a secondary side molded part, 6 is a main body part, 7 is a mounting leg part, 8 is a projecting edge,
9 is a bottom wall, 10 is a recess, and 11a and 11b are annular protrusions.

[Claims]

1. Consists of a fixed mold having a cylindrical pot opening on the mold surface, a plunger slidably held in the pot, and a movable mold clamped to the fixed mold, which is orthogonal to the direction of movement of the plunger. Prepare a mold configured such that when the area of the mold surface of the fixed mold projected onto the reference plane is 100, the area of the opening of the pot portion projected onto the reference plane is 30 or more. A step of arranging a skin on the mold surface of at least one of the fixed mold and the movable mold; Supplying molten resin to the pot portion, and after the mold is clamped, the molten resin is introduced into the cavity by forward driving of the plunger. Skin in-mold molding characterized by sequentially performing a step of injecting and molding the molten resin, and a step of opening the mold after the molten resin is cooled and solidified to release the molded body to which the skin is integrally joined. Method.