JP2008105230A - Sheet shaping method, sheet shaping die and container manufactured by sheet shaping method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve die reproducibility in a technique for shaping a plastic sheet material to shape a shaped product having an undercut part provided to its inner peripheral surface. <P>SOLUTION: The sheet shaping die 10 is constituted of a female die 12 and a male die 14, and the male die 14 has: a core main body 16 having a shape corresponding to a part of the inner peripheral surface shape of the shaped product; and a slide core 18 having a shape corresponding to the undercut part of the shaped product and movable in a die open-close direction and a diametric direction with respect to the core main body 16. Cam surfaces 16a and 18a brought into contact with each other are respectively formed to the core main body 16 and the slide core 18, and become inclined surfaces toward an outer diametric direction as going toward the female mold 12. After a sheet material is inserted in the gap between the female mold 12 and the male mold 14, the dies are closed to allow the core main body 16, the slide core 18 and the female mold 12 to approach mutually, and the slide core 18 is moved in an outer diametric direction with respect to the core main body 16 by utilizing the cam surfaces 16a and 18a to shape the undercut part by the slide core 18. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet molding method, a sheet molding die, and a container manufactured by a sheet molding method for molding a plastic sheet material by press molding and molding a molded product having an undercut portion on an inner peripheral surface.

  As a conventional sheet molding method and mold of this type, for example, the one described in Patent Document 1 is known.

  In the mold described in Patent Document 1, a knockout mold that is movable in the axial direction, a mold cavity body that is radially outward of the knockout mold, and a predetermined mold cavity are formed together with the mold cavity body. A mold cavity auxiliary member, and has a protrusion that the mold cavity main body bites inward in the central direction, and an upper edge that the mold cavity auxiliary member bites inward in the central direction. An air vent passage is formed in the parting line of each part. Thus, the mold is a female mold, and a molded product having a double reverse tapered portion is formed by vacuum forming.

JP 54-93046 A

  However, in such conventional vacuum forming, there is a problem that it cannot be said that the mold reproducibility of the undercut portion is necessarily satisfied. For example, when the sheet material of the material of the molded product is a material that is relatively easily stretched, the molded product can be sufficiently stretched according to the mold, so that relatively good mold reproducibility can be obtained. However, in the case of a material that is difficult to stretch, there is a problem that the mold reproducibility is poor and it is impossible to form a sharp undercut shape as desired even if evacuation is performed.

  The present invention has been made in view of such a problem, and in the technology of molding a plastic sheet material to form a molded product having an undercut portion on the inner peripheral surface, sheet molding that can improve mold reproducibility. It is an object of the present invention to provide a container manufactured by a method, a sheet molding die, and a sheet molding method.

In order to achieve the above object, the invention according to claim 1 is a sheet molding method for molding a molded product having an undercut portion on an inner peripheral surface using a mold composed of a female mold and a male mold,
A core body having a shape corresponding to a part of the shape of the inner peripheral surface of the molded product, and a shape corresponding to the undercut portion of the molded product, and a mold opening / closing direction and a radial direction with respect to the core body And a slide core that can move relative to each other in a predetermined range.
After inserting the sheet material between the open male mold and female mold, and then closing the mold to bring the core body and slide core close to the female mold and sandwiching the sheet material between the core body and female mold The slide core is moved in the outer diameter direction with respect to the core body using the cam surface, and an undercut portion is formed by the slide core.

  The invention according to claim 2 is characterized in that the sheet material according to claim 1 is a foamed resin sheet.

  The invention described in claim 3 is characterized in that the foamed resin sheet according to claim 2 has a foaming ratio of 3% or more.

Invention of Claim 4 consists of a female mold and a male mold, and is a sheet molding die for molding a molded product having an undercut portion on the inner peripheral surface from a sheet material,
The male mold has a core main body having a shape corresponding to a part of the inner peripheral surface shape of the molded product, and has a shape corresponding to the undercut portion of the molded product, and a mold opening / closing direction with respect to the core main body. A slide core that is relatively movable in a predetermined range in the radial direction, and the slide core and the core body each have cam surfaces that are inclined toward the outer diameter direction toward the female mold. It is formed so that contact is possible.

  The invention according to claim 5 is characterized in that a plurality of the slide cores according to claim 4 are provided along the periphery of the core body.

  The invention described in claim 6 is characterized in that biasing means for constantly biasing the slide core according to claim 4 or 5 in the inner diameter direction is further provided.

  The invention according to claim 7 is characterized in that the sheet material according to any one of claims 4 to 6 is a foamed resin sheet.

  The invention according to claim 8 is characterized in that the foamed resin sheet according to claim 7 has a foaming ratio of 3% or more.

  The invention according to claim 9 is characterized by a container having an undercut portion formed by the sheet forming method according to any one of claims 1 to 3 on an inner peripheral surface.

  According to the present invention, when the mold is closed and the male mold and the female mold are brought close to each other, the force in the mold opening / closing direction is converted into the force in the outer diameter direction of the slide core using the cam surface. The undercut portion can be shaped by this force. Therefore, the shaping force of the undercut portion can be sufficiently secured, and the mold reproducibility can be improved. Thus, the undercut portion can be formed into a desired sharp shape.

  According to the present invention, a desired undercut portion can be formed even when a foamed resin sheet that has been difficult to form an undercut portion in the past, particularly a foamed resin sheet having a foaming ratio of 3% or more, is a sheet material. It becomes possible to mold a molded product having the inner peripheral surface. As a result, a container having heat insulation can be formed.

  By providing a plurality of slide cores along the periphery of the core body, it is possible to minimize the occurrence of a portion that is not pressed by the slide core when the slide core moves in the outer diameter direction.

  In addition, by providing an urging means that constantly urges the slide core in the inner diameter direction, when the mold is opened after molding, the slide core can move in the inner diameter direction according to the cam surface. It is possible to move while avoiding the part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are views showing an embodiment of a sheet molding die of the present invention for carrying out the sheet molding method of the present invention. The sheet molding die 10 can be molded into a cylindrical, weight-like or bowl-like shape having an undercut portion on the inner peripheral surface, and specifically, a container as shown in FIG. 40 can be molded.

  The container 40 has an undercut portion 40a at the top of its inner peripheral surface. A lid 42 can be attached to the container 40, and the protrusion 42 a formed on the lid 42 is locked to the undercut portion 40 a of the container 40, thereby sealing the container 40 from the inside of the container 40. As a result, liquid leakage from the container 40 can be prevented. Moreover, the undercut part 40a can also function as a stopper at the time of taking out the contents in the container 40.

  The container 40 is formed from a plastic sheet material. As the plastic sheet material, a non-foamed resin sheet having a foaming rate of less than 3% and a foamed resin sheet having a foaming ratio of 3% or more can be used. In particular, the present invention exhibits superiority in a foamed resin sheet having a foaming rate of 3% or more, which has a heat insulation property, which has been difficult to mold conventionally, and is suitable for manufacturing a container 40 having a heat insulation property.

  Moreover, as a material of a foamed resin sheet, it can be set as PP, PS, PET, and other engineering plastics. Moreover, a film such as an OPP film can be appropriately bonded to the foamed resin sheet.

  Returning to FIGS. 1 and 2, the sheet molding die 10 mainly includes a female die 12 and a male die 14. In this specification, the mold opening and closing direction is the vertical direction. Therefore, the male mold 14 and the female mold 12 are moved relative to each other in a vertical direction with a predetermined pressure by driving means (not shown). The surface 12a of the female die 12 facing the male die 14 has a shape corresponding to the outer peripheral surface shape of the molded product.

  The male mold 14 includes a core body 16, a plurality of slide cores 18 that are movable within a predetermined range in the vertical direction and the radial direction with respect to the core body 16, and a support body that supports the core body 16 and the slide core 18. 20.

  The core body 16 is screwed to the tips of a plurality of pins 22 that penetrate the support body 20 so that the core body 16 can move relative to the support body 20 in the vertical direction within a range in which the pins 22 can slide. It has become. Further, between the core main body 16 and the support body 20, a spring 24 that constantly urges them both in a direction away from each other in the vertical direction is inserted as shown in FIG.

  A plurality of slide cores 18 are provided in the circumferential direction along the outer periphery of the core body 16, and in this example, there are six slide cores 18. If the number of slide cores is too small, the gap formed between adjacent slide cores will increase, so it is preferable that the number of slide cores is such that the gap is acceptable.

  The slide core 18 is supported with play in the radial direction with respect to the support body 20 by pins 26 fixed to the support body 20, and the outer peripheral surface of the slide core 18 projects at the peripheral edge of the support body 20. It can move in the outer diameter direction until it comes into contact with the inner diameter direction protruding portion 20c of the flange portion 20a provided. Further, a spring 28 as an urging means is interposed between the slide core 18 and the flange portion 20a, and the spring 28 constantly urges the slide core 18 in the inner diameter direction.

  Therefore, the slide core 18 can be moved relative to the core body 16 in a predetermined range in the vertical direction and the radial direction. Further, cam surfaces 16 a and 18 a that are inclined with respect to the vertical direction are formed between the core body 16 and the slide core 18, respectively, on the opposing surfaces. The cam surface 16a and the cam surface 18a are inclined in a direction that expands in the outer diameter direction toward the female mold 12, and the cam surfaces 16a and 18a can be in sliding contact with each other.

  The surface 16b of the core body 16 facing the female mold 12, the outer radial protrusion 18b of the slide core 18, and the surface 20b of the flange 20a of the support 20 facing the female mold 12 are the inner circumference of the molded product. It has a shape corresponding to the surface shape. Here, the outer diameter direction protrusion part 18b of the slide core 18 has comprised the shape applicable to the desired undercut part of a molded article.

The operation of the sheet molding die configured as described above will be described.
First, the heated sheet material is continuously or discontinuously sent to the sheet molding die 10 and inserted between the female die 12 and the male die 14 which are separated from each other in the vertical direction and opened ( FIG. 3).

  Next, the female mold 12 is driven by driving means (not shown) so as to approach the male mold 14 in order to close the mold. When the core body 16 is in a state where the sheet material is sandwiched between the female mold 12 and the relative movement between the core body 16 and the female mold 12 is stopped, the female mold 12 and the male mold 12 are resisted against the urging force of the spring 24. The mold 14 comes closer (FIG. 4). Then, since relative movement occurs in the vertical direction between the core body 16 and the support body 20, the slide core 18 also moves relative to the core body 16 in the vertical direction (FIG. 5), and the urging force of the spring 28 is increased. The cam surface 18a of the slide core 18 moves along the cam surface 16a of the core body 16 while resisting the above. As a result, the slide core 18 moves in the outer diameter direction until the outer peripheral surface of the slide core 18 abuts on the inner diameter direction protruding portion 20c of the flange portion 20a of the support 20 (FIG. 6). Thus, the outer diameter direction protrusion 18b of the slide core 18 protrudes in the outer diameter direction from the core body 16, and an undercut portion is formed.

  When the cam surface 18a of the slide core 18 moves along the cam surface 16a of the core body 16, the vertical force acting on the male mold 12 is converted into the outer radial force of the slide core 18, and the slide The core 18 applies a pressing force to the undercut portion from the inner diameter direction. A shaping force acts on the undercut portion by the pressing force in the inner diameter direction.

  After the molding is completed, the female mold 12 is separated from the male mold 14 to open the mold by an operation opposite to the previous one. At this time, the cam surface 18a of the slide core 18 is slidably contacted along the cam surface 16a of the cam body 16 by the spring 28. Therefore, the slide core 18 moves up and down while moving in the inner diameter direction. The mold can be opened while avoiding undercut parts.

  As described above, in the present invention, the slide core 18 moves from the inner diameter direction toward the outer diameter direction to form the undercut portion, and at this time, the force that presses the mold in the vertical direction is the cam surface 16a, 18a effectively converts the force into the outer diameter direction of the slide core 18, so that the shaping force to the undercut portion is increased, and the mold reproducibility can be improved. As a result, a molded product having an undercut portion can be molded from a foamed resin sheet that is particularly difficult to stretch.

It is sectional drawing showing embodiment of the sheet molding die of this invention for enforcing the sheet forming method of this invention. It is a male top view, (a) includes a core main body, (b) represents the state which abbreviate | omitted the core main body. It is sectional drawing which shows the effect | action at the time of sheet forming. FIG. 4 is a cross-sectional view illustrating the operation at the time of sheet forming following FIG. 3 (the sheet material is not shown). FIG. 5 is a cross-sectional view illustrating the operation at the time of sheet forming following FIG. 4 (the sheet material is not shown). FIG. 6 is a cross-sectional view illustrating the operation at the time of sheet forming following FIG. 5 (the sheet material is not shown). It is a perspective view of the container which is a molded article, and the lid | cover which seals this container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sheet molding die 12 Female die 14 Male die 16 Core main body 16a Cam surface 18 Slide core 18a Cam surface 28 Spring (biasing means)
40 Container 40a Undercut part

Claims (9)

A sheet molding method for molding a molded product having an undercut portion on the inner peripheral surface using a mold composed of a female mold and a male mold,
A core body having a shape corresponding to a part of the shape of the inner peripheral surface of the molded product, and a shape corresponding to the undercut portion of the molded product, and a mold opening / closing direction and a radial direction with respect to the core body And a slide core that can move relative to each other in a predetermined range.
After inserting the sheet material between the open male mold and female mold, and then closing the mold to bring the core body and slide core close to the female mold and sandwiching the sheet material between the core body and female mold A sheet forming method, wherein the slide core is moved in the outer diameter direction with respect to the core body using the cam surface, and the undercut portion is shaped by the slide core.   The sheet forming method according to claim 1, wherein the sheet material is a foamed resin sheet.   The sheet forming method according to claim 2, wherein the foamed resin sheet has a foaming ratio of 3% or more. It is a sheet molding die that consists of a female mold and a male mold and molds a molded product having an undercut portion on the inner peripheral surface from a sheet material,
The male mold has a core main body having a shape corresponding to a part of the inner peripheral surface shape of the molded product, and has a shape corresponding to the undercut portion of the molded product, and a mold opening / closing direction with respect to the core main body. A slide core that is relatively movable in a predetermined range in the radial direction, and the slide core and the core body each have cam surfaces that are inclined toward the outer diameter direction toward the female mold. A sheet molding die characterized by being formed so as to be able to contact.   The sheet molding die according to claim 4, wherein a plurality of the slide cores are provided along the periphery of the core body.   6. The sheet molding die according to claim 4, further comprising a biasing means for constantly biasing the slide core in the inner diameter direction.   The sheet molding die according to any one of claims 4 to 6, wherein the sheet material is a foamed resin sheet.   The sheet molding die according to claim 7, wherein the foamed resin sheet has a foaming ratio of 3% or more.   The container which has the undercut part shape | molded by the sheet | seat shaping | molding method described in any one of Claim 1 thru | or 3 in an internal peripheral surface.

Images