JPH0584771A - Method and mold for producting hollow object - Google Patents

Abstract

PURPOSE:To certainly prevent the generation of flash in the bonded part of a surface member by a method wherein an inclined surface is formed to the outer peripheral part of the rear member of a mold pressing the rear member at the time of mold registering for secondary injection and the outer peripheral wall of a surface member is pressed to a female mold by the inclined surface at the time of secondary mold clamping to perform secondary injection. CONSTITUTION:A surface member important in its appearance and a rear member not relatively important in its appearance are superposed one upon another to be molded into a hollow object by a die slide injection method. At this time, an inclined surface 430 is formed to the outer peripheral part of the rear member of a mold pressing the rear member at the time of mold registering for secondary injection and the outer peripheral wall of the surface member is pressed to a female mold at the time of secondary mold clamping by the inclined surface to perform secondary injection and the generation of the flash of a bonded part in the surface member important in its appearance is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a mold for producing a plastic hollow body by joining the abutting portions of the peripheral edge of a half-divided body obtained by dividing the product by secondary injection.

[0002]

2. Description of the Related Art When manufacturing hollow products made of plastic, such as spoilers, console lids, and glove lids for automobiles, a half-molded product obtained by splitting the product into upper and lower parts is subjected to primary injection molding to form a molding die. A die slide injection method has been proposed in which both half halves are slid against each other and the abutted portions are joined by secondary injection of a molten resin (see, for example, JP-A-62-87315).

In general, the injection molding method has a higher productivity than the blow molding method, and a molded product having a good appearance can be obtained. Therefore, the molding of the above-mentioned primary molded body and the joining of the two are performed by a molding die. By performing by slide and injection molding method,
It is possible to efficiently produce a hollow product that is lightweight and has good appearance.

[0004]

However, in the above-mentioned conventional method for manufacturing a plastic hollow body, both halves are butted against each other in the mold, and the outer circumference of the butted portion is joined by the secondary injection. Therefore, if the halves are not accurately positioned with respect to each other, burrs may occur at the joints of the product, and it is not preferable that the burrs at the joints particularly give importance to the appearance of the product.

Therefore, in a subsequent process, if the joining portion burr is removed by a mechanical method such as a grinder,
Not only a great deal of labor and effort is required, but also the finishing work after removing the burrs is difficult and the appearance is likely to be impaired.

In view of the above problems, the present invention is a method for manufacturing a hollow body, which is capable of reliably preventing a burr at a joint portion from being generated on a surface of which importance is placed on the appearance when the product halves are joined by secondary injection. And its type.

[0007]

Therefore, the method of manufacturing a hollow body according to the present invention uses a die slide injection method in which "a front side member whose appearance is important and a back side member whose appearance is relatively negligible are superposed on each other. In the method of molding a hollow body, a bevel is formed on the outer peripheral portion of the back member of the die that holds the back member at the time of die matching for the secondary injection, and the outer wall of the front member is directed toward the female die by the bevel by the die clamping. The secondary injection is performed while pressing it. "

Further, the mold for the hollow body according to the present invention is
"In a mold for molding a hollow body by a die slide injection method by superimposing a front side member that should emphasize appearance and a back side member that can be relatively neglected in appearance, the hollow body is more than the maximum contour part in the mold opening projection direction. A mold splitting surface is formed on the back side member side, and a slope is formed on the outer peripheral portion of the back side member of the mold that holds the back side member at the time of matching for secondary injection, and the slope is formed by the mold clamping during secondary injection. The outer peripheral wall of is pressed against the female mold. "

[0009]

According to the present invention, the mold for pressing the back side member is formed with the inclined surface, and the secondary injection is performed while pressing the outer peripheral wall of the front side member toward the female mold by the inclined surface when the secondary mold is clamped. At the time of the secondary injection, the front side member is closely attached to the inner surface of the female mold without a gap, the joining resin does not go around to the side of the front side member where appearance should be emphasized, and no burr is formed on the front side member.

Further, in the present invention, since the outer peripheral surface of the back side member of the mold for pressing the back side member is formed with the inclined surface and the front side member is pressed against the female mold during the secondary injection, the resin shrinkage of the front side member is large. Also in this case, the front side member and the back side member are accurately joined by the correction of the slope, and the mold for the resin shrinkage can be easily corrected.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the specific examples shown in the drawings. 1 to 7 show a method of manufacturing a hollow body and a mold thereof according to an embodiment of the present invention, which is an example applied to molding an automobile spoiler. In the figure,
The molding die 1 to which the present method is applied is configured by disposing a slide die 4 between a fixed die 2 and a movable die 3. The movable die 3 can be opened and closed in the left-right direction in the drawing, and the slide die 4 is illustrated. It is provided so that it can be slid vertically.

A sprue 20 and a hot runner 21 are formed on the fixed mold 2, a heating means (not shown) such as a heater is arranged on the outer periphery of the hot runner 21, and the outer end side of the hot runner 21. An on-off valve 23 that opens and closes the valve is installed in the. Further, the slide mold 4 is provided with the primary injection sprues 40 and 41 and the secondary injection sprue 42.
Of the sprue 40, 41, 42 is opened at the split surface of the slide die 4.

On the mold-splitting surface of the movable mold 3, the female mold portion 30 for molding the outer surface of the upper half-split body 6 and the lower half-split body 7 when the spoiler 5 which is a hollow product is vertically divided into two parts. A male part 31 for molding the inner surface is formed, and a step part is formed on the outer peripheral part of the female part 30. The step part is for forming an arc-shaped side surface of the spoiler 5, that is, an undercut part. The partial slide die 32 is provided so as to be slidable toward the outside of the parting surface. On the other hand, a female mold part 43 for molding the outer surface of the lower half-split body 7 of the spoiler 5 and a male mold part 44 for molding the inner surface of the upper half-split body 6 are formed on the mold split surface of the slide mold 4. The mold parts 43, 44 of the male and female mold parts 31 on the movable mold 3 side are
The upper and lower divided body cavities are configured by being matched with 30.

Here, the movable mold 3 and the slide mold 4 are set on the mold dividing surface a on the lower half-divided body 7 side of the maximum contour portion b of the spoiler 5 projected in the mold opening direction (see FIG. 8). Also,
An inclined surface 320 is provided at the inner peripheral end of the partial slide die 32, and an outer wall 62 of the upper half-split body 6 is provided at the outer periphery of the male die portion 44 of the slide die 4.
An inclined surface 440 is formed to shape the lower end portion into an inclined surface, and the outer wall 62 is pressed against the outer wall 62 of the upper half portion 6 on the outer periphery of the female die portion 43 of the slide die 4 during the secondary die clamping. An inclined surface 430 to be pressed against the female die portion 30 of the movable die 3 and a concave portion 310 into which the inclined surface 430 can be fitted are formed on the male die portion 31 of the movable die 3, and thus the female die portion 30 of the slide die 4 is clamped by the secondary die clamping. Secondary injection is performed while the inclined surface 430 on the outer periphery of the mold part 43 presses the outer peripheral wall 62 of the upper half-divided body 6 toward the female mold 30 of the movable mold 3.

Further, the molding die 1 is provided with a slide mechanism 9 for holding the partial slide die 32 in the non-slide position during the primary injection molding and sliding the partial slide die 32 into the sliding position where the molded product is projected during the secondary injection molding. In this slide mechanism 9, cams 90, 91, 92 for holding the partial slide mold 32 in the non-sliding position at the time of primary and secondary injection molding are formed in the slide mold 4, and the movable mold 3 has partial slide molds. Cam grooves 93, 94 into which cams 90, 91, 92 are fitted are formed behind 32, and an accommodating recess 95 for accommodating the cam part 47 at the time of primary injection molding is formed in the upper end portion of the movable die 3 in the figure. Has been formed. Further, a spring member 96 for urging the partial slide die 32 to a non-sliding position when the primary die is opened is disposed in the cam grooves 93 and 94, and the partial slide die 32 is moved to the slide position. An operation lever 97 for sliding is provided, and the operation lever 97 is provided at the upper end of the slide mold 4 when the secondary mold is opened.
A hook member 98 is provided which engages with and operates the. The partial slide dies 32 are mutually linked by a cam mechanism, a lever mechanism, or the like so that each of the partial slide dies 32 slides to the slide position by the operation of the operation lever 97. Instead of the cam type slide mechanism 9, a hydraulic cylinder type slide mechanism may be used.

FIGS. 8 and 9 show an automobile spoiler which is a hollow plastic product manufactured by this method. In the figure, the spoiler 5 is configured by joining an upper half-divided body 6 and a lower half-divided body 7 which are formed by dividing the upper and lower halves with each other with a joining resin 8, and the upper half-divided body 6 emphasizes the appearance. The front side member and the lower half-split body 7 are the back side member whose appearance can be comparatively neglected. Positioning projections 60 and 61 for positioning the lower half-divided body 7 in the mold clamping direction and the direction perpendicular thereto are formed on the outer edge side and the center of the inner surface of the upper half-divided body 6, and the inner surface of the lower half-divided body 7 is formed. A leg portion 71 that engages with the central protrusion 61 of the upper half-split body 6 is formed in the center of the. In addition, the inner surface of the outer wall 62 of the upper half-split body 6 and the outer wall 72 of the lower half-split body 7
The outer surface of is formed substantially parallel to the die cutting direction, and the bonding resin 8 is injected and solidified in the gap formed by both surfaces. Support legs 73 are formed on the spoiler 5, and nuts 74 for fixing the support legs 73 to the vehicle body are fitted on the bottom surfaces of the support legs 73.

Next, a method for manufacturing the spoiler of this embodiment will be described.

When molding the spoiler 5, first, as shown in FIG. 1, the slide mold 4 is set to the first mold clamping position,
The movable mold 3 is moved forward to perform the primary mold matching, and the cavity of the upper half-divided body 6 shape in which the spoiler 5 is divided into two by the male and female mold parts 30 and 44 of the movable mold 3 and the slide mold 4,
The male and female mold parts 31 and 43 form a lower half-shaped body 7 shaped cavity of the spoiler 5. In that state, when the injection nozzle is connected to the sprue-20 of the fixed mold 2 and the molten resin is primary-injected, the molten resin is sprue 20, hot runner 2
The upper and lower halves 6 are injected through the first and primary injection sprues 40 into the cavity on the upper half-divided body side, and through the sprue 20, the hot runner 21 and the primary injection sprue 41 into the cavity on the lower half-divided body side. , 7 are primarily molded.

At this time, the cams 90, 91 on the slide die 4 side
Is fitted into the cam grooves 93, 94 on the movable die 3 side, and the partial slide die 32 is positioned at the non-sliding position with respect to the female die portion 30 of the movable die 3. Therefore, as shown in FIG. The sloped surface 440 of the mold 4 is in close contact with the sloped surface 320 of the inner peripheral end of the partial slide mold 32, and the outer wall 62 of the upper half-split body 6 is
The lower end is formed into an inclined surface. As shown in FIG. 6, the slant surface 430 of the slide die 4 is the recess 310 of the movable die 3.
Since it is fitted inside, the slope 430 of the slide die 4 does not hinder the die matching.

Further, the outer surface of the outer wall 62 of the upper half-split body 6 is formed by the female die 30 up to the maximum contour portion and the undercut portion by the partial slide die 32, respectively, and is formed into an arc shape as a whole. Since the cam 92 on the slide die 4 side is stored in the storage recess 95 on the movable die 3 side,
The cam 92 does not hinder the mold matching.

Furthermore, since the outer peripheral edge of the male die portion 44 of the slide die 4 is formed substantially perpendicular to the die cutting direction, the inner surface of the outer wall 62 of the upper half-split body 6 is substantially parallel to the die cutting direction. It is formed. Further, since the male die portion 44 of the slide die 4 is formed with the concave portions on the outer peripheral side and the central portion, the positioning projections 60, 6 are formed on the outer edge side and the central portion of the inner surface of the upper half-split body 6.
1 is formed.

Further, a vertical groove portion is formed on the outer peripheral side of the male die portion 31 of the movable die 3 so as to be substantially parallel to the die cutting direction corresponding to the concave portion for positioning the movable die 3, and a vertical groove portion is formed in the central portion. Therefore, the outer wall 72 of the lower half-split body 7 is formed in such a size that the outer wall 72 can be fitted into the positioning protrusion 60 of the upper half-split body 6, and the outer surface of the outer half wall 72 is substantially parallel to the die cutting direction. And a leg 71 is formed at the center of the inner surface of the lower half-split body 7.

When the injection molding resin is cooled and solidified after a lapse of a predetermined time after the completion of the primary molding, the injection nozzle is retracted and the movable mold 3 is retracted. Then, as shown in FIG. 2, since the partial slide die 32 is urged to the non-sliding position by the urging force of the spring member 96, the primary-molded upper half body 6 is the female die of the movable die 3. The lower half body 7 is securely held in the portion 30, and the lower half-split body 7 is held in the female die portion 43 of the slide die 4 by the primary injection sprue resin portion, and thus the movable die 3 and the slide die 4 are the primary die. Be opened. Further, since the primary injection sprue resin portion 64 of the upper half-divided body 6 which is the paddle portion comes out from the primary injection sprue 40 of the slide die 4, this is manually cut or cut by using a robot. To do.

When the primary molding is completed in this way, the slide mold 4 is slid from the first mold clamping position to the second mold clamping position on the lower side of FIG. 3, and the movable mold 3 is advanced to move the movable mold 3 to the movable mold 3. The slide mold 4 and the slide mold 4 are matched as shown in FIG.
The upper and lower split bodies 6, 7 in 43 are butted against each other.

Then, the cam 90 on the slide die 4 side is positioned in the space below the movable die 3, while the cams 91, 92 on the slide die 4 side are fitted in the cam grooves 93, 94 on the movable die 3 side. The partial slide die 32 is positioned in a non-sliding position with respect to the female die portion 30 of the movable die 3.

Further, as shown in FIG. 7, the sloped surface 430 of the slide mold 4 is a sloped surface 320 at the inner peripheral end of the partial slide mold 32.
And push up the inclined surface of the outer wall 62 of the upper half body 6,
As a result of pressing the outer wall 62 against the movable female die 30, the upper half body 6 is accurately positioned in the female die 30 without any gap.

Further, the tip portion of the side wall 72 of the lower half-split body 7 is fitted to the positioning projection 60 on the outer edge side of the inner surface of the upper half-split body 6,
Further, the tip of the leg portion 71 at the center of the lower half-split body 7 is fitted to the positioning protrusion 61 at the center of the inner surface of the upper half-split body 6, and the upper and lower half-split bodies 6,
7 are positioned relative to each other in the mold clamping direction and the direction perpendicular thereto.

At the same time, a predetermined gap is formed between the inner surface of the side wall 62 of the upper half-split body 6 and the outer surface of the side wall 72 of the lower half-split body 7 which extend in the die-cutting direction.

At this time, the primary injection sprues 40 and 41 of the slide die 4 are separated from the hot runner 21 of the fixed die 2 and the secondary injection sprue 42 is communicated with the hot runner 21 of the fixed die 2. Since one end side of the hot runner 21 of the fixed die 2 is opened in the space above the slide die 4, the open / close valve 23 is closed.

When the secondary mold clamping is completed in this way and the molten resin is injected from the injection nozzle, the molten resin is sprued,
It is injected into the gap between the outer walls 62, 72 of the upper and lower halves 6, 7 through the hot runner 21 and the secondary injection sprue 42, and the upper and lower halves 6, 7 are joined together.

When the injected resin 8 is cooled and solidified after a lapse of a predetermined time and the movable die 3 is retracted, the hook member 98 engages with the operating lever 97 to swing the operating lever 97, and the partial slide die 32 is moved. Since the molded product 5 is released from the slide position and the holding of the molded product 5 is released, when the molded product 5 is ejected by the eject mechanism (not shown), the product 5 having the sprue resin portion on the slide die 4 side is obtained. Cut these sloppy parts and attach the nut 74,
The spoiler 5 shown in FIG. 5 can be manufactured.

In the molding method and mold of the present embodiment as described above, the slant surface 430 is formed on the outer periphery of the female mold portion 43 of the slide mold 4, and the upper half-split body 6 is formed by the slant surface 430 when the secondary mold is clamped. Since the outer peripheral wall 62 is pressed toward the female mold 30, the upper half-divided body 6 can be closely adhered to the female mold 30 without any gap during the secondary injection, and the bonding resin 8 should emphasize the appearance. It is possible to reliably prevent wraparound to the 6 side and prevent occurrence of a burr at the joint portion.

Moreover, the upper half-split body 6 substantially parallel to the die-cutting direction
Since the joining resin 8 is injected into the gap between the inner surface of the side wall 62 of the above and the outer surface of the side wall 72 of the lower half-split body 7 to join,
The joining portion can be set on the lower half-split body 7 side where the appearance of the spoiler 5 can be relatively neglected, and the appearance of the spoiler 5 can also be guaranteed by this.

Further, in the molding method and mold of this embodiment, the inclined surface 430 is formed on the outer periphery of the female mold portion 43 of the slide mold 4, and
Since the upper half-split body 6 is pressed against the female mold 30 at the time of the next injection, when the relatively large resin shrinkage occurs in the upper half-split body 6, the upper half-split body 6 is accurately positioned by correcting the slope 430. Therefore, the mold shrinkage of the resin can be easily corrected.

Further, in the molding method and mold of this embodiment,
When the upper and lower half halves 6 and 7 are abutted against each other in the mold, the positioning projections 60 and 61 on the inner surface of the upper half halve 6 and the side wall 72 and the leg 71 of the lower half halve 7 are fitted to each other. Upper and lower halves 6 and 7 are positioned relative to each other in the mold clamping direction and the direction perpendicular thereto, and between the inner surface of the side wall 62 of the upper half body 6 and the outer surface of the side wall 72 of the lower half body 7. Since it was made to join with resin 8,
Since the upper and lower halves 6 and 7 can be positioned in the mold clamping direction and the direction perpendicular thereto, and can be joined in a wide area, the upper and lower halves can be joined as compared with the conventional case where the outer peripheral edge of the abutting portion is simply joined. The halves 6 and 7 can be joined with high strength.

[0036]

As described above, according to the hollow body manufacturing method and mold of the present invention, the die slide is made by superposing the front side member, which should be emphasized in appearance, and the back side member, in which the appearance is relatively neglected. When molding a hollow body by the injection method, an inclined surface is formed on the outer peripheral portion of the back side member of the mold that holds the back side member at the time of die matching for secondary injection, and the outer peripheral wall of the front side member is formed by the inclined surface when the secondary die is clamped. Since it is pressed toward the female mold and the secondary injection is performed in this state, it is possible to reliably prevent the formation of a joint burr on the front side member, and it is possible to easily correct the mold due to the resin shrinkage.

[Brief description of drawings]

FIG. 1 is a schematic view showing a step of primary injection molding and a mold structure thereof in a method for manufacturing a hollow body according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a mold open state and its mold structure after primary injection molding in the above molding method.

FIG. 3 is a schematic view showing a secondary injection molding step and its mold structure in the above manufacturing method.

FIG. 4 is a schematic view showing a mold opening state and a mold structure after the secondary injection molding step in the above manufacturing method.

FIG. 5 is a partial cross-sectional view showing the primary injection molding step of the upper half-split body and the main part of its mold structure in the above manufacturing method.

FIG. 6 is a partial cross-sectional view showing a primary injection molding step of the lower half-split body and a main part of its mold structure in the above manufacturing method.

FIG. 7 is a partial cross-sectional view showing a secondary injection molding process of upper and lower halves and a main part of its mold structure in the above manufacturing method.

FIG. 8 is a cross-sectional view of an essential part showing an automobile spoiler molded by the above manufacturing method.

FIG. 9 is a bottom view of an essential part showing the automobile spoiler.

[Explanation of symbols]

3 Movable type 30 Female type part 4 Sliding type 44 Female type part 440 Slope 5 Automotive spoiler 6 Upper half body 7 Lower half body 8 Resin for bonding

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Shinji Kasami Shinji Kasami, Higashi-Hiroshima City, Hiroshima Prefecture, 175-1 Oohara, Honhonmatsu-cho Daikyo Co., Ltd. (72) Inventor Shozo Nishida 1 Funakoshi-minami, Aki-ku, Hiroshima-shi, Hiroshima Prefecture No. 6-7 Japan Steel Works, Ltd. Hiroshima Works

Claims (2)

[Claims] 1. A method of molding a hollow body by a die slide injection method by superposing a front side member, which should be emphasized in appearance, and a back side member, which can be relatively neglected in appearance, at the time of mold matching for secondary injection. A method for manufacturing a hollow body, characterized in that an inclined surface is formed on the outer peripheral portion of the back side member of the mold for pressing the back side member, and the secondary injection is performed while pressing the outer peripheral wall of the front side member toward the female mold by the inclined surface by clamping the mold. .. 2. A mold for forming a hollow body by a die slide injection method by superimposing a front side member, which should be emphasized in appearance, and a back side member, which can be relatively neglected in appearance, in a die opening projection direction of the hollow body. A mold splitting surface is formed on the back side member side with respect to the contour portion, and a slope is formed on the back side member outer peripheral portion of the mold that presses the back side member at the time of mold matching for the secondary injection. A hollow body forming die, wherein the sloped surface presses the outer peripheral wall of the front side member toward the female die.