JPH10138323A - Manufacture of skinned plastic hollow member and hollow mold used therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and certainly demold a skin-clad plastic hollow member while removing the burr on the outer periphery of the hollow member at a time of demolding in the production of the skinned plastic hollow member. SOLUTION: A hollow mold of a three-split structure is used and pinch-off line forming parts 14 are provided in a middle mold 13 and the split surface side of one split mold 12 and ejector pins 15 are provided in one split mold 12 so as to be freely accessible with respect to a cavity C and, at a time of mold opening after a hollow member is molded, the middle mold and the other split mold 11 are opened while the parison and skin of the outer periphery of the hollow member are held between the middle mold and one split mold 12 and, subsequently, the hollow member is pushed by the ejector pin and the hollow member is separated from the parison and skin on the outer periphery of the hollow member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a plastic hollow body with a skin and a hollow mold preferably used for the production.

[0002]

2. Description of the Related Art For interior parts for automobiles and the like, a plastic hollow body made of blow molding or the like and the surface of which is covered with a skin made of nonwoven fabric or fabric is often used. An example of such a plastic hollow body with a skin (hereinafter simply referred to as a hollow body) is shown in FIGS. 10 and 11.
In the drawing, reference numeral 50 denotes a plastic hollow body with a skin, 51 denotes a skin, and 52 denotes a plastic hollow body. The skin 51
As shown in the figure, the edge 53 is not peeled off or seen from the outside so as not to impair the appearance of the hollow body.
The edge 53 is wrapped up to the back side of the plastic hollow body 51 and is integrally attached to the plastic hollow body 51.

[0003] An example of a method for producing a plastic hollow body having a skin having such a shape and an example of a hollow molding die used for the method are disclosed in Japanese Patent Application Laid-Open No. 3-290227.
According to this method and the mold, as shown in FIG. 12 and FIG. 13 showing a cross section of the mold at the time of molding, the cavity having the undercut U is formed by forming the mold 60 into a three-part structure including at least the middle mold 63. First, the skin 51 is set in the cavity 64 having the undercut U. Reference numerals 61 and 62 denote split dies combined with the split surface of the middle die 63, and reference numeral 65 denotes a drive device for moving the middle die 63 forward and backward with respect to the split die 62.

[0004] The skin 51 and a split mold 62 on one side are provided.
The parison P is disposed between the mold 51 and the dies, and the skin 51 and the parison P are sandwiched by the cavity edge 66 of the split surface of the middle die 63 and the split die 62.
4 and positioned securely. Next, air is blown into the parison to perform blow molding (blow molding), and then, as shown in FIG. 14, first, between the middle mold 63 and the split mold 62 on one side, and then, as shown in FIG. The molds between the split molds 61 on the other side are opened in order, and the plastic hollow body with the skin is removed.

According to the manufacturing method and the hollow mold,
At the undercut U portion of the middle size 63 shown in FIG.
Since 1 is wound around the back surface of the hollow body, the appearance of the hollow body can be improved.

However, in this manufacturing method and the hollow molding die, as shown in FIGS. 14 and 15, the plastic hollow body 50 with the skin is formed by opening the middle die 63 and the split dies 61 and 62. And the non-undercut side of the middle mold 63 (the side where no undercut is formed when the molded product is removed).
From the split surface 63a side. At this time, a split surface 63b on the undercut side of the middle die 63 (a side on which an undercut is formed with respect to demolding of a molded product) is provided.
Since the extra skin 51a (not necessary for the molded product) and the parison Pa sandwiched between the middle mold 63 and the split mold 62 at the time of the hollow molding are connected to the outer peripheral surface of the hollow body 50 and exist as burrs, Split surface 63 on the undercut side
There was a problem that the removal of the hollow body 50 from “a” was hindered and it was difficult to remove the mold. The surplus skin 51a and the parison Pa constituting the burr are usually separated at the cavity edge 66 when the hollow body 50 is released from the middle die 63. Depending on the thickness or the like, there were cases where separation was not easy.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of the above problems, and the removal of the mold is simple and reliable, and the burrs on the outer periphery of the hollow body are surely removed together with the removal of the hollow body. An object of the present invention is to provide a method of manufacturing a plastic hollow body with a skin that can be removed and a hollow mold for suitably performing the manufacturing method.

[0008]

That is, according to the method of manufacturing a plastic hollow body with a skin of the present invention, a three-part structure having a cavity in which an undercut is formed for removal from one side of the middle mold. Using a hollow molding die, open the middle die and one of the split dies combined with the undercut side split surface, set a skin on the middle die side, and place a parison between the skin and one of the split dies. Then, the mold is closed, the parison and the skin around the cavity are sandwiched between one of the split molds and the middle mold, and gas is blown into the parison to form a cavity-shaped hollow body, and at the same time, a skin is formed on the surface of the hollow body. A method of manufacturing a plastic hollow body with a skin, comprising unifying and then releasing said hollow mold by opening said molding die, comprising: A pinch offline forming part is provided on one of the divided molds to be combined, and a protruding pin is provided on the one of the divided molds so as to be able to enter and exit the cavity. With the extra parison and outer skin on the outer periphery of the hollow body held between the middle mold and one of the split molds, the middle mold and the other split mold are opened, and then the hollow body is pushed by the protruding pin to thereby cause the excess parison and the outer skin on the outer periphery of the hollow body. And separating the hollow body from the mold.

The hollow mold used in the present invention is a hollow mold having a three-part structure having a cavity for forming an undercut for removal from one side of the middle mold. A pinch offline forming portion is provided on one of the split dies combined with the side split surface, and a protruding pin is provided on the one of the split dies so as to be able to enter and exit the cavity. The structure is characterized in that the space between the split dies is opened, and then the projecting pin projects into the cavity.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing one example of the hollow mold of the present invention. 2 to 9 are diagrams schematically showing a method of manufacturing a plastic hollow body with a skin using the hollow mold, wherein FIG. 2 is a cross-sectional view of a mold open state, and FIG. FIG. 4 is a cross-sectional view showing a state in which a parison is extruded in between, FIG. 4 is a cross-sectional view showing a mold closed, FIG. 5 is a cross-sectional view showing a mold opening when the mold is released, and FIG. 7 is an enlarged sectional view of FIG. 4, FIG. 8 is an enlarged sectional view of FIG. 5, and FIG. 9 is an enlarged sectional view of FIG.

The production method of the present invention and the hollow mold used therefor can be used to improve the appearance of a plastic hollow body with a skin as described above, in which the end of the skin goes around the back side of the hollow body and is integrally formed. And it is for obtaining efficiently. As shown in FIGS. 1 and 2, the hollow mold 10 used in the manufacturing method of the present invention has a three-part structure having a cavity C in which an undercut U is formed on one side of the middle mold 13. Undercut side split surface 13 of
a, that is, one split mold 12 combined with a split surface 13a on the side that forms an undercut for demolding,
A projecting pin 15 is provided so as to be able to freely enter and exit the cavity C, and when the plastic hollow body with the skin is released from the mold, the middle mold 13 and the other split mold 11 open, and then the projecting pin 15 projects into the cavity C. It is characterized by having a structure.

Cavities C1, C2 and C3 are formed in the split dies 11 and 12 and the middle die 13, respectively, and the cavities C1, C2 and C3 are formed in the mold 10 by closing the mold. Is formed. The split dies 11 and 12 are configured to be united and separated from each other via the middle die 13 by a suitable driving device (not shown). In addition, the middle mold 13 is the split mold 1
It is configured so that both 1 and 12 are united and separated from each other. Reference numeral 18 denotes a driving device for bringing the middle die 13 into and out of the one split die 12, and in this example, a known cylinder device was used.

The cavity C1 of the split mold 11 has a shape forming the front side of the plastic hollow body with the skin, and the cavity C2 of the other split mold 12 has a shape forming the back side of the hollow body. Further, the cavity C3 of the middle mold 13 has a shape that constitutes at least a side surface of the hollow body and a part of a back surface continuous from the side surface. Make up the cut. The undercut U portion of the cavity C3 of the middle mold 13 wraps the end portion of the skin on the back surface of the molded product and adheres the same at the time of manufacturing the plastic hollow body with the skin, thereby improving the appearance of the plastic hollow body with the skin. It is to make.

A pinch-offline forming section 14 is provided on the split surface of the middle mold 13 and the split mold 12 which are combined with each other. When the mold is closed, the pinch off-line forming section 14 forms a cavity C3 that abuts the parison and the skin by intermingling the middle mold 13 and the split mold 12.
And the edge of C2. And, by the contact, the parison and the skin are accurately held with respect to the cavity C,
The molding can be performed reliably and efficiently, and at the time of demolding, the parison and the burr portion of the skin are sandwiched to facilitate cutting from the hollow body. In this embodiment, the medium 13
And cavities C2 and C in which
The entire circumference becomes a pinch offline forming section.

The split die 12 is provided with a protruding pin 1.
5 are provided. The protruding pins 15 are used to reliably and promptly remove the hollow body hollow-formed into the shape of the cavity C from the split mold and the middle mold, and enter and exit the cavity C by an appropriate driving device (not shown). It is provided freely. An appropriate number of the protruding pins 15 are provided at appropriate positions on the surface of the cavity C2 of the split mold 12, depending on the shape and size of the molded plastic hollow body with a skin.

A method for producing a plastic hollow body with a skin according to the present invention using the hollow mold 10 having such a configuration will be described. First, as shown in FIG. 2, the space between the split mold 12 and the middle mold 13 constituting the back surface of the plastic hollow body with the skin is opened, and the skin 20 is set on the middle mold 13 side. The skin 20 is made of soft vinyl, fabric, or the like, and may be formed in a predetermined skin shape in advance by vacuum molding or the like, if desired. In the present embodiment, a holding pin 16 for holding the skin 20 protrudes from a split surface on the outer periphery of the cavity C3 of the middle mold 13.

Subsequently, as shown in FIG.
The parison P is extruded between the epidermis 20 and the split mold 12 set in the above, and the split molds 11 and 12 are united via the middle mold 13. The skin 20 and the parison P are sandwiched by the pinch off-line forming section 14 to form the cavity C.
Is held within. Thereafter, as shown in FIGS. 4 and 7, a blowing nozzle (not shown) is inserted into the parison P and a suitable gas is blown into the parison P to bring the parison P into close contact with the skin 20 and integrate the same. It is hollow molded into a shape. At this time, the cavity C3 of the middle mold 13 is used.
Is formed in an undercut shape in which the end of the skin 20 is wound around the back of the hollow body, so that the end of the skin 20 covers the side of the hollow body and is welded to the back.

After cooling the hollow body in the mold, the mold is opened. First, as shown in FIGS. 5 and 8, the space between the split mold 11 and the middle mold 13 in which the pinch offline forming section 14 is not provided is opened first. Then, the other split mold 12
With the middle mold 13 closed and the protruding pin 1 of the split mold 12
5 is projected into the cavity C. Thereby,
The plastic hollow body 30 with the skin held by the split mold 12 and the middle mold 13 is extruded as shown in FIGS. 6 and 9. At this time, since the split mold 12 and the middle mold 13 remain united and the pinch-offline forming portion 14 sandwiches the surplus portions (ie, burr portions) 20a and Pa of the parison and the parison, the hollow body 30 is pushed out and the The surplus portions (burrs) 20a and Pa of the parison are cut and separated from the plastic hollow body with the skin.

Therefore, not only the excess portion (burr portion) of the skin and the parison does not hinder the removal of the hollow body 30, but also the outer surface of the removed plastic hollow body 30 with the skin has already been deburred. State
No separate deburring operation is required. In addition, since the hollow body 30 is pushed out by the protruding pin 15, the removal of the plastic hollow body 30 with the skin is quick and reliable, and the workability is good. Therefore, although illustration is omitted, even if there is a rib or unevenness on the surface of the hollow body, the hollow body closely adheres to the cavity surface of the hollow mold, and the hollow body has a shape that makes it difficult to remove the mold. be able to.

[0020]

As shown and described above, according to the method for manufacturing a plastic hollow body with a skin according to the present invention, a pinch offline forming section composed of a middle mold and a split mold is used when opening and removing the mold. Is closed and the pinch-offline forming section forms an excess portion of the epidermis and parison (burr).
The plastic hollow body with the skin is pushed out from the undercut side of the medium-sized body to the opposite side with a pin while the pinch is sandwiched, so that the skin is not disturbed by the undercut or the extra skin around the hollow body and the parison (burr). The plastic hollow body can be easily removed from the mold. In addition, since the unnecessary portion (burr) of the skin and the parison has been already removed from the removed hollow plastic hollow body with the skin, a product can be obtained without any separate deburring operation. Further, the hollow molding die of the present invention has an effect that a plastic hollow body with a skin can be easily manufactured with good appearance.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a hollow mold of the present invention.

FIG. 2 is a view schematically showing a method for manufacturing a plastic hollow body with a skin using the hollow molding die, and is a cross-sectional view in a mold open state.

FIG. 3 is a cross-sectional view showing a state where a parison is extruded between the opened molds.

FIG. 4 is a sectional view showing mold closing.

FIG. 5 is a sectional view showing a mold opening.

FIG. 6 is a cross-sectional view showing a state in which the hollow body is removed from a molding die.

FIG. 7 is an enlarged sectional view of FIG. 4;

FIG. 8 is an enlarged sectional view of FIG. 5;

FIG. 9 is an enlarged sectional view of FIG. 6;

FIG. 10 is a perspective view of a general plastic hollow body with a skin.

FIG. 11 is a sectional view thereof.

FIG. 12 is a perspective view showing an example of a conventional molding die for molding the hollow body.

FIG. 13 is a sectional view showing a mold closed state.

FIG. 14 is a cross-sectional view showing a mold open state.

FIG. 15 is a cross-sectional view showing a state where a molded product is released from a molding die.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Hollow forming mold 11 Split mold 12 Split mold 13 Medium 13a Medium undercut side split surface 14 Pinch offline forming part 15 Protruding pin 20 Skin P Parison

Claims (2)

[Claims] 1. A hollow mold having a three-part structure having a cavity therein for forming an undercut for demolding from one side split surface of a middle die, which is combined with the middle die and its undercut side split surface. Open between one of the split molds, set a skin on the middle mold side, place a parison between the skin and one of the split molds, close the mold and close the outer periphery of the cavity between the one split mold and the middle mold. A gas is blown into the parison with the parison and the skin in between to form a hollow body having a cavity shape, and at the same time, the skin is integrated with the surface of the hollow body, and then the mold is opened to release the hollow body. In the method for manufacturing a plastic hollow body with a skin, while providing a pinch offline forming portion in the middle mold and one of the split molds combined with the undercut side split surface, In one of the split molds, a protruding pin is provided so as to be able to freely enter and exit the cavity, and when the mold is opened after the molding of the hollow body, an excess parison of the outer periphery of the hollow body between the middle mold and one of the split molds and Opening between the middle mold and the other split mold while holding the skin, and then pushing the hollow body with the protruding pins to separate the hollow body from the excess parison and the skin on the outer periphery of the hollow body, and to remove the skin. Of manufacturing a plastic hollow body with a hole. 2. A hollow mold having a three-part structure having a cavity therein for forming an undercut for demolding from a one-side split surface of a middle die. A pinch offline forming part is provided in the split mold and the one split mold is provided with a protruding pin so as to be able to enter and exit the cavity, and when the hollow body is released, the middle mold and the other split mold are opened, and then, A hollow molding die used for manufacturing a plastic hollow body with a skin, wherein the projecting pin projects into a cavity.