JPH01141013A - Resin product - Google Patents

Abstract

PURPOSE:To strengthen a bonding force between both a primary side molding part and a secondary side molding part, by setting the melting temp. of a secondary side thermoplastic resin to be higher than the melting temp. of a primary side thermoplastic resin and molding projected parts on the bonding face of the primary side molding part to be bonded with the secondary side molding part. CONSTITUTION:After a primary side molding part 3 is inserted in a mold and the mold is clamped, a molten raw material is poured in the mold from the gate part 12. The poured molten raw material enters into a recessed part 10 from a gate part 12, passes through an introducing groove 13 of circular projected parts 11b and respectively enters round between a central projected part 11a and an innermost circular projected part 11b, between both circular projected parts 11b being face to face and between an outermost circular projected part 11b and an inner face of a projected edge 8. In this instance, as the melting temp. of the secondary side thermoplastic resin is set to be higher than the melting temp. of the primary side thermoplastic resin, the surfaces of the central projected part 11a of the primary side molding part 3, the circular projected parts 11b and the inner face of the projected edge 8 are melted again by the heat of the molten raw material and therefore, when these parts are solidified again, the primary side molding part 3 and the secondary side nolding part 5 are fused together.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to the improvement of resin products, such as leg rubbers for instruments, which are formed by double molding different resin materials.

<Prior art> Conventionally, this type of leg rubber was manufactured using the
According to Publication No. 57 and Japanese Utility Model Application Publication No. 59-28350, there is a primary molded part made of hard resin that is attached to the lower surface of the device, and a second molded part made of soft resin that protrudes downward from the lower surface of the primary molded part and contacts the mounting surface. It is well known to have a molded part on the next side.

Then, an annular recess with an open bottom is formed on the lower surface of the primary molded part, and a through hole penetrating vertically is provided in the bottom wall of the annular recess, and the annular recess is filled with a soft resin. At the same time, at that time, the resin was passed through the through hole to the opposite side of the bottom wall, and the secondary molded part was formed into a sandwich structure in which the bottom wall of the primary molded part was sandwiched between the upper and lower sides, and the two parts were connected. .

(Problems to be solved by the invention) However, the conventional double molding method for leg rubber has a sandwich structure, so the structure of the mold, especially the secondary mold, becomes complicated. Not only did the manufacturing cost of the mold become high, but the molding ratio of the molded product by the mold was not large enough, and the molding cost was high.

In addition, since the resin flows around from the through hole of the primary molded part to the opposite side of the bottom wall, a recessed resin sink portion is created on the outer surface of the secondary molded part, causing a deterioration in the appearance of the product.

<Means for solving the problems> Therefore, the present invention solves the above problems, and includes:
The contents will be explained below using examples shown in the drawings.

In the present invention, the financial temperature of the thermoplastic resin on the secondary side is set higher than the financial temperature of the thermoplastic resin on the primary side, and the primary side molded part (3) has the secondary side molded part. (
5) is characterized in that the protrusion (11) to be welded when forming the secondary molded part (5) is pre-molded.

(Function) Therefore, during secondary molding, the protrusion (11
) is partially melted by the heat of forming the secondary molded part (5) and welded to the secondary molded part (5) (Fig. 1).

In addition, as in other embodiments shown in FIG. 5 and subsequent figures, the projection (1
If 1) has a thin rectangular cross-section or an elongated pin shape, it will be plastically deformed due to injection pressure and heat, and the secondary molded part (5) will become caught in the direction of peeling. Can be done.

<Example) The present invention will be explained below based on embodiments shown in the drawings.

1 to 4 show a first embodiment of the present invention, and in the figures, 1 indicates an appliance (not shown) such as an electric appliance or furniture.
As shown in Figure 2.3, this leg rubber is a resin product that is attached to the bottom of the instrument. It is composed of a secondary side molded part 5 made of a soft resin such as rubber, which protrudes downward from the lower surface of the part 3 and comes into contact with the mounting surface 4 .

The primary molded part 3 is molded using a relatively hard thermoplastic resin 1, such as polypropylene having a financial temperature of about 165 degrees.

Next, the external shape of the primary molded part 3 will be explained.
As shown in Figure 3, there is a hollow frame-shaped main body part 6 having a predetermined height and a trapezoidal shape, and a second bottom panel of the instrument that is integrally raised from this main body part 6. It consists of a leg part 7.

As shown in FIG. 4, the main body part 6 has an annular projecting edge 8 that frames the periphery of its lower surface, and the upper surface thereof is covered with a bottom wall 9 inside the projecting edge 8. , forming four circular parts 10 with open bottom surfaces. A protrusion 11 that protrudes downward from the lower surface of the bottom wall 9 is formed in the recess 10 .

The height of the protrusion 11 is set slightly lower than that of the protruding edge 8, and the protrusion 11 has a central protrusion 11a that protrudes in the shape of an acute cone at the center of the recess 1O, and the central protrusion 11a is arranged in an annular shape. Surrounding it, the cross section forms a triangular shape with an acute angle. It consists of five annular protrusions 11b formed at equal intervals.

Further, the projecting edge 8 is provided with a secondary side gate portion 12 formed by partially cutting out a U-shaped portion from the lower end thereof, and each annular projection portion 1 is formed in the radial direction from the gate portion 12.
In the middle of the length of 1b, an introductory groove 13 is formed by cutting out a part of the groove 1b in a U-shape from the lower end thereof with a width roughly equal to the width of the gate part 12. A gas vent hole 14 that vertically penetrates the bottom wall 9 is formed within the space between the annular protrusion 11b on the opposite side to the introduction groove 13.

The mounting leg portion 7 is attached to the bottom wall 9 as shown in FIG. 2.4.
A tapered pin 15 protrudes from the center of the guide pin 15, and a pair of legs protruding oppositely from both sides of the guide pin 15, slightly lower than the guide pin 15, and forming a plate-like vertically elongated rectangular shape. Consists of pieces 1G and 16. In the middle of the length of each of the leg pieces 16, there is a pair of engagement grooves 17, 17 formed by cutting out two shapes from both sides, and the lower edge of this engagement groove 17 is connected to the upper edge of the main body 6 At the same time, the vertical distance is made to match the thickness of the bottom panel 2 of the instrument. or,
The outer surface of the tip of the leg piece 16 is formed with a tapered surface 18 that is inclined diagonally upward and whose thickness gradually decreases toward the tip.

On the other hand, the secondary side molding part 5 is made of a thermoplastic resin which has a higher melting temperature than the primary thermoplastic resin, preferably about 70 degrees, such as an elastomer whose melting temperature is about 270 degrees. Use and shape. To explain its external shape, it fits perfectly into the recess 10 of the main body 6 of the primary molded part 3, and below the lower end of the ridge 8 of the main body 6 is a C-disc-shaped protuberance. The lower surface is horizontal and flat (Fig. 1.3).
.

Next, to explain the molding procedure, first, a mold for injection molding (not shown) for forming the primary molded part 3 having the above configuration is manufactured, and a molten raw material is injected into this mold to form the primary molded part 3. Mold part 3.

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

The injected molten raw material passes through the gate part 12 of the primary molding part 3.
It enters into the recess 10 through the introduction groove 13 of the annular protrusion 11b.
through the central protrusion 11a and the innermost annular protrusion 11.
b, between the opposing re-annular projections 11b, and between the outermost annular projection ub and the inner surface of the flange 8, at which time the secondary thermoplastic resin finance This is because the temperature is set higher than the financial temperature of the thermoplastic resin on the primary side.

The heat of the injected molten raw material melts the central protrusion 11a, the annular protrusion 11b, and the inner surface of the ridge 8 of the primary molded part 3 again, and when they harden again, the primary molded part 3 and the secondary The side molded parts 5 are welded together (FIG. 1).

In particular, since the central protrusion 11a and the annular protrusion 11b have an acute triangular cross section, the thermal conductivity is high and the welding effect is remarkable. Moreover, the welding area is significantly expanded by the central protrusion 11a and the annular protrusion 11b, and the bonding force of the image forming part 3.5 can be strengthened.

Note that the gas vent hole 14 of the primary molding part 3 is also filled with the molten raw material, but this hole 14 is simply for gas venting, and the molten raw material passes through the hole 14 and flows through the bottom wall 9. Make sure it does not go around the top.

Next, to explain how to attach the leg rubber 1 formed in this way to a device, first, as shown in FIG. A pair of mounting holes 2 into which each leg piece 16 is fitted on both sides.
The mounting holes 20 are located slightly inside the opposing distance between the leg pieces 16, so that each leg piece 16 is slightly bent inward. A wide rectangular first opening 20a that passes through, and a bitemperature opening 2.
0a, the second openings 20b are narrower than the first openings 20a into which the engagement grooves 17 of each leg piece 16 fit, and are in communication with the first openings 20a. .

To attach the leg rubber 1, it is sufficient to align the guide bin 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, when the leg rubber l is pushed in until it comes into contact with the lower surface of the bottom panel 2, the one leg piece 16 opens outward from the left and right due to its elastic restoring force, moves from the first opening 20a to the second opening 20b, and moves from the first opening 20a to the second opening 20b. The engagement groove 17 of the leg piece 16 fits into the opening 2Ob and does not come out downward, fixing the leg rubber 1 to the lower surface of the bottom panel 2 of the instrument (FIG. 3).

5 to 8 show a second embodiment of the leg rubber 1, in which the main leg rubber 1 has a primary side molded part 3 similar to the first embodiment.
and a secondary side forming part 5, and the material of the image forming part 3.5 is also the same.

The primary molded part 3 consists of a main body part 6 and a mounting leg part 7, as shown in FIG. 5.6. As shown in FIG. 6, the main body part 6 has an insertion hole 21 in its center that penetrates vertically, and has an inner protrusion 8 on its lower surface that frames the lower edge of the insertion hole 21.
a and an inner protruding edge 8a that frames the periphery of the main body portion 6 are C. An annular outer protruding edge 8b protruding at the same height is provided on the inner side surrounded by the circumferential protruding edges 8a and 8b. An annular recess 10 whose upper surface is closed by a bottom wall 9 and whose lower surface is open is formed. A protrusion 11 that protrudes downward from the lower surface of the bottom wall 9 is formed in the recess 10 .

The protrusions 11 are formed in an annular shape at equal intervals of C within the interval between the circumferential protrusions 8a and 8b, and are formed in triple form here, and the height thereof is set slightly lower than that of the circumferential protrusions 8a and 8b. Each protrusion 11 is formed into a rectangular cross-sectional shape that is thinner than the circumferential protrusions 8a and 8b. Further, in the middle of the length of each protrusion 11, at least in the radial direction from the gate part 12, in this case in all four directions, there is a U-shaped cone having a width equal to C equal to the width of the gate part 12, starting from the lower end thereof. Introductory groove 1 formed with a partial cutout
3... is formed.

Further, as shown in FIG. 5.6, the mounting leg portion 7 is integrally raised from the upper surface of the bottom wall 9, communicates with the insertion hole 21 of the main body portion 6, and has an inner diameter gradually contracting upward. It consists of a hollow part 22 with a large diameter, and four cut pieces 24 surrounding the hollow part 22 and cut into, for example, a cross shape from the upper end by a radial slit 23.

The image forming parts 3 and 5 are formed using the same forming procedure as in the first embodiment.

During secondary molding, the molten raw material enters the recess lO from the gate part 12 of the primary molding part 3, passes through each introduction groove 13 of the protrusion 11, and passes through the outer surface of the inner protrusion 8a and the innermost protrusion. part 11, between the opposing raised parts 11, and between the outermost protrusion 11 and the inner surface of the outer flange date. Since the financial temperature is set higher than the financial temperature of the thermoplastic resin on the primary side, the heat of the injected molten raw material causes the outer surface of the inner protrusion 8a of the primary molded part 3, the protrusion 11, and the outer protrusion. When each surface of the inner surface of the edge 8b is melted again and hardened again, the primary molded part 3 and the secondary molded part 5 are welded to each other (Figures 7 and 8).
.

In particular, since the protrusion 11 is formed into a thin rectangular cross-sectional shape, the thermal conductivity is high and the welding effect is remarkable. Then, the central protrusion 11a and the annular protrusion 11
Since the welding area is significantly expanded by b, the bonding force between the image forming parts 3 and 5 becomes strong.

Further, the tip of the projection 11 is easily melted and plastically deformed into a mushroom shape due to the heat of the injected molten raw material, and this mushroom-shaped deformed portion 11' acts as an anchor, and the image forming portion 3.5 is They become difficult to separate from each other (Figure 8).

Furthermore, in addition to the heat of the injected molten raw material, due to the injection pressure, the protruding part 11 is easily pushed by the pressure of the molten raw material and plastically deformed into an obliquely inclined state, and this inclined deformed part 11
” becomes a catch obliquely intersecting the peeling direction of the secondary molded portion 5, that is, the opening direction of the recess 10 of the primary molded portion 3, making it difficult for the image molded portions 3.5 to peel off from each other.

On the other hand, in the recess lO of the primary forming part 3, the molten raw material is
A narrow flow path between the outer surface of the inner protrusion 8a and the innermost protrusion 11, between the facing protrusion parts 11, and between the outermost protrusion 11 and the inner surface of the outer protrusion 8b. Since the water flows through a narrow flow path, the inflow resistance is large and the protrusion 11 is particularly easily deformed.In addition to flowing through a narrow flow path, the introduction grooves 13 are formed on all sides, so the wave path becomes maze-like. As a result, the molten raw material flows irregularly, and the inflow resistance can be increased.

Next, to explain how to attach the leg rubber 1, first, a circular attachment hole 20 is bored in the bottom panel 2 of the instrument, and extends vertically to the same extent as the outer periphery of the attachment leg 7.

Then, align the mounting leg part 7 of the leg rubber 1 with the mounting hole 20 and insert it from below, and then push the locking pin 25 from the insertion hole 21 of the main body part 6 into the hollow part 22 of the mounting leg part 7. Just put it in.

As a result, since the inner diameter of the hollow portion 22 gradually decreases upward, each cut piece 2 cut by the slit 23
The inner surface of the leg rubber 1 is pushed by the outer circumferential surface of the locking pin 25 that enters, and expands in all directions on the back side of the bottom panel 2, preventing it from coming out downward from the mounting hole 20, and the leg rubber 1 is attached to the bottom surface of the bottom panel 2 of the instrument. (Figure 5).

9 and 10 show other embodiments of the protrusion 11, in which the protrusion 11 protrudes in the shape of an elongated pin. According to this embodiment, the tip part is plastically deformed into a mushroom shape due to the heat of the injected molten raw material and its injection pressure.
It is easy to be plastically deformed into a bent state, and in particular, because it is elongated and pin-shaped, it is easy to deform into a mushroom shape (Fig. 10).

<Effects of the Invention> As explained above, according to the present invention, during secondary molding,
- Since the blow-molded protrusion partially melts due to the heat of forming the secondary molded part and is welded to the secondary molded part, the bonding force between the two molded parts can be strengthened.

[Brief explanation of the drawing]

The drawings show an 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 is a perspective view showing the primary molded part, Figures 5 to 8 show the second embodiment of the leg rubber, Figure 5 is a side view showing its attached state, and Figure 6 shows the primary molded part. FIG. 7 is a perspective view with a part of the leg rubber cut away, FIG. 8 is an enlarged sectional view of the main part, and FIGS. 9 and 10 show a second embodiment of the leg rubber. 1 is a perspective view showing the primary side molding part, and FIG. 1O is a perspective view with a part of the leg rubber cut away. In the figure, 1 is a leg rubber as an example of a resin product, 3 is a primary molded part, 5 is a secondary molded part, and 11 is a protrusion.

Claims (7)

[Claims] (1) A primary molded part that is primarily molded with a thermoplastic resin, and a secondary molded part that is secondarily molded to the primary molded part using a thermoplastic resin that is different in material from the primary thermoplastic resin. In the resin product, the melting temperature of the thermoplastic resin on the secondary side is set higher than the melting temperature of the thermoplastic resin on the primary side, and the A resin product characterized in that a protrusion that is welded when forming a secondary molded part on a joint surface with a molded part is primarily molded. (2) The resin product according to claim 1, wherein the welding protrusion of the primary molded part protrudes in a direction perpendicular to the injection direction of the secondary thermoplastic resin. (3) The resin product according to claim 1 or 2, wherein the welding protrusion of the primary molded part has an acute triangular cross section. (4) The resin product according to claim 1 or 2, wherein the welding protrusion of the primary molded part has a thin rectangular cross section. (5) The resin product according to any one of claims 1 to 4, wherein the welding protrusion of the primary molded part protrudes in an annular shape. (6) Claim 1 or 2, characterized in that the welding protrusion of the primary molded part is in the shape of an elongated pin.
Resin products listed in section. (7) A plurality of welding protrusions of the primary molded part protrude close to each other with a gap through which the thermoplastic resin of the secondary side passes. The resin product described in any one of the items above.