JP2012161922A - Resin molding apparatus and resin molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a molded article simply, surely and economically by penetrating a decorative sheet along a first mold and discharging a molten resin.SOLUTION: A resin molding apparatus includes: the first mold T2 provided with a valve gate G2 capable of switching the opening and closing of a resin discharge gate Ga by the in and out state of a valve pin 3; a second mold U for forming a cavity C for molding the resin between the first mold T2 and the second mold U; and a sheet sending device for arranging the decorative sheet 6, forming a decorative layer 2 on the surface of a resin molded article to be molded, along the cavity surface of the first mold T2; wherein the valve pin 3 has a front end part 3a formed to be projected into the inside of the cavity C from the cavity surface of the first mold T2 in a state where the resin discharge gate Ga is closed and a holding mechanism H for holding the decorative sheet 6 so that the front end part 3a penetrates the decorative sheet 6 is provided.

Description

  The present invention relates to a resin molding apparatus that sends a decorative sheet into an injection mold, molds a resin molded product and decorates the surface of the resin molded product, and resin molding using the resin molding apparatus Regarding the method.

In this type of resin molding technology, in order to discharge the molten resin into the cavity with the decorative sheet disposed along the surface of the fixed mold provided with the valve gate, the decorative sheet portion that covers the valve gate In addition, it is necessary to form a through hole through which the molten resin can pass.
As a first resin molding technique for forming a through hole in a decorative sheet and performing resin molding, a through hole is formed in a corresponding portion of the decorative sheet in advance by a process different from the resin molding process, and the sheet is fed. A device equipped with a positioning mechanism that determines the delivery position of the decorative sheet so that the through hole covers the valve gate when the decorative sheet is arranged along the fixed mold in the apparatus (see, for example, Patent Document 1) was there.

  Moreover, as a 2nd resin molding technique, there exists what was equipped with the punching apparatus which forms a through-hole in a decorating sheet in the position before arrange | positioning a decorating sheet to a fixed mold (for example, refer patent document 2). After the through hole is formed in the decorative sheet by the punching device, the decorative sheet is slid on the surface of the fixed mold, and the position of the decorative sheet is determined by the positioning mechanism so that the through hole covers the valve gate. It is configured.

  Further, as a third resin molding technique, the discharge pressure of the molten resin discharged from the hot tip is set high, the temperature at the tip of the hot tip is increased, and the corresponding part of the decorative sheet is heated and pressed. It is also conceivable to form through-holes.

JP-A-3-253317 (FIGS. 3 and 6) JP 59-194848 (FIG. 7)

According to the first conventional resin molding technique described above, a through-hole must be provided in the decorative sheet separately from the resin molding step, and it is necessary to install a perforation device therefor and use the perforation device. This takes time and effort to form a through hole.
In addition, if the decorative sheet with through holes is not positioned so that the through holes are correctly covered on the valve gate, it will be an obstacle to filling the cavity with molten resin. High sheet positioning accuracy is required.
Therefore, according to the first resin molding technique, there is a problem that both the initial cost and the running cost are likely to be high.
In addition, if the decorative sheet is provided with a through hole in advance, for example, when suction is performed and the decorative sheet is placed along the cavity surface to fix the position, air is passed from the through hole to the cavity surface side of the decorative sheet. However, there is a risk that the suction action cannot be fully exerted, and the position fixing of the decorative sheet tends to be incomplete.

According to the above-described conventional second resin molding technique, the perforating device is provided adjacent to the fixed mold, so that the entire resin molding device becomes large and the device cost increases.
Furthermore, the process of drilling the decorative sheet and the process of positioning the through hole with respect to the valve gate are required, so the resin molding work efficiency tends to be low, and the initial resin cost can be reduced by the second resin molding technology. In addition, there is a problem that both the running cost tends to be high.
In addition, as in the first resin molding technique, there is a risk that the through hole becomes an obstacle to suction of the decorative sheet, and there is a problem that the position fixing of the decorative sheet is likely to be incomplete.

  According to the third resin molding technique described above, the through hole is formed in the decorative sheet by controlling the discharge pressure of the molten resin and the temperature of the tip of the hot chip. In order to reliably form the through hole, It is conceivable to make the molten resin at a high pressure and the hot tip end to a high temperature. However, for this purpose, the decorative sheet should not be wrinkled or deformed, so there are limitations on the pressure and temperature, and the control tends to be complicated. Further, depending on the physical properties of the decorative sheet, the formation of the through hole may be uncertain.

  Therefore, the object of the present invention is to solve the above-mentioned problems, and to easily and surely and economically form a molded product by penetrating a decorative sheet along a fixed mold and discharging a molten resin. It is in the place of providing a resin molding technique that can be performed automatically.

  According to a first characteristic configuration of the present invention, a resin molding cavity is provided between a first molding die having a valve gate capable of switching opening and closing of a resin discharge gate by the withdrawal and withdrawal of a valve pin, and the first molding die. A second forming die to be formed; and a sheet feeding device that arranges a decorative sheet for forming a decorative layer on the surface of the molded resin molded product along the cavity surface of the first forming die, and The valve pin is formed such that its tip end protrudes into the cavity from the cavity surface of the first mold when the resin discharge gate is closed, and the tip end penetrates the decorative sheet. A holding mechanism for holding the decorative sheet is provided.

According to the first characteristic configuration of the present invention, in a state where the resin discharge gate is closed by the valve pin, the tip end portion of the valve pin protrudes into the cavity from the cavity surface of the first mold, and in this state By holding the decorative sheet by the holding mechanism, the through hole can be formed by penetrating the tip of the valve pin through the decorative sheet.
Therefore, it is not necessary to form a through hole in the decorative sheet in advance or to adjust the decorative sheet on which the through hole is formed to the position of the valve gate in another process. There is no need to prepare. As a result, the operation of forming the through hole in the decorative sheet can be carried out easily, reliably and economically in a series of resin molding steps.

  According to a second characteristic configuration of the present invention, the holding mechanism includes a pressing portion that presses the decorative sheet against the first mold at a position near the valve pin.

According to the second characteristic configuration of the present invention, the position near the valve pin of the decorative sheet can be pressed against the first mold by the pressing part, and accordingly, the tip of the valve pin on the decorative sheet The biting is promoted and the through hole can be formed more reliably.
Moreover, since the state which pressed the decorating sheet to the 1st shaping | molding die by the holding | suppressing part can be maintained after drilling, the position shift of a decorating sheet can be prevented also at the time of discharge of the molten resin from a valve gate.
As a result, the quality of the resin molded product can be improved.

  According to a third characteristic configuration of the present invention, the pressing portion is provided in a part of a primary molded product held in the second mold.

According to the third characteristic configuration of the present invention, the decorative sheet is pressed against the first mold by the pressing portion of the primary molded product held by the second mold without providing a complicated mechanism. Thus, the economic efficiency of the apparatus can be improved.
Furthermore, the pressing portion itself is integrated with the post-molded molten resin by two-color molding, and it is difficult for a trace to remain on the resin molded product.

  The 4th characteristic structure of this invention exists in the place with which the said holding | suppressing part is provided in a part of said 2nd shaping | molding die.

  According to the 4th characteristic structure of this invention, even if it does not provide a complicated mechanism, a decorating sheet can be pressed to a 1st shaping | molding die with the holding | suppressing part with which a part of 2nd shaping | molding die was provided, Economic efficiency as a device can be improved.

  According to a fifth characteristic configuration of the present invention, the pressing portions are dispersedly arranged at a plurality of locations around the valve pin.

  According to the fifth characteristic configuration of the present invention, the decorative sheet can be pressed evenly and uniformly on the first mold by the pressing portions distributed and arranged at a plurality of locations around the valve pin, It is possible to prevent the displacement of the through hole and more reliably perform drilling.

  According to a sixth characteristic configuration of the present invention, the pressing portion is formed in an elongated shape along the radiation centered on the valve pin.

According to the sixth characteristic configuration of the present invention, when the molten resin discharged from the valve gate enters the cavity after completing the drilling in the decorative sheet, the pressing portion becomes an obstacle to the movement. Can be prevented, and the molten resin can be spread smoothly.
Furthermore, since a large contact area of the pressing part with respect to the decorative sheet can be secured, the decorative sheet can be held in a more stable state.
As a result, the quality of the resin molded product can be improved.

  According to a seventh characteristic configuration of the present invention, a resin molding cavity is provided between a first molding die having a valve gate capable of switching opening and closing of a resin discharge gate by the withdrawal and withdrawal of a valve pin, and the first molding die. Resin provided with the 2nd shaping | molding die to form, and the sheet feeding apparatus which arrange | positions the decorating sheet which forms a decoration layer in the surface of the resin molding product shape | molded along the cavity surface of the said 1st shaping | molding die A resin molding method for forming a resin molded product by a molding device, wherein the decorative sheet is arranged along the cavity surface of the first molding die by the sheet feeding device, and the tip of the valve pin is While the resin discharge gate is in a closed state, it protrudes into the cavity from the cavity surface of the first mold, penetrates the decorative sheet, and after the mold is clamped, the valve pin is retracted Open the resin discharge gate Te, from the valve gate through a through hole formed in said decorative sheet in place to form a resin molded article by ejecting molten resin into the cavity.

According to the seventh characteristic configuration of the present invention, a through hole is formed in the decorative sheet in advance in a step different from the resin molding, or the decorative sheet in which the through hole is formed is aligned with the position of the valve gate. And the need to prepare another punching device is eliminated. As a result, the operation of forming the through hole in the decorative sheet can be carried out easily, reliably and economically in a series of resin molding steps.
In addition, for example, even when the decorative sheet is arranged along the cavity surface of the first mold and the position is fixed by suction, a through hole is formed in the decorative sheet in advance. Since it is not done, air does not turn from the through hole to the cavity surface side of the decorative sheet, and positioning can be performed more accurately.

Schematic cross section showing resin molding equipment An exploded perspective view showing a resin molded product Schematic cross section showing resin molding equipment Schematic cross section showing resin molding equipment Schematic cross section showing resin molding equipment Schematic cross section showing resin molding equipment Sectional view showing the valve gate Sectional drawing which shows the holding | suppressing part of the resin molding apparatus of another embodiment Plan view showing placement of holding part The perspective view which shows the front-end | tip part of the bubble pin of another embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

1 and 3 to 6 show an embodiment of the resin molding apparatus of the present invention. As shown in FIG. 2, the resin molding apparatus M corresponds to a primary molded resin layer (corresponding to a primary molded product). ) A two-color molded product (an example of a resin molded product) 1 in which 1A and a secondary molded resin layer 1B are laminated is formed.
A decorative layer 2 is provided on the surface of the secondary molded resin layer 1 </ b> B in the two-color molded product 1.

The mold for forming the two-color molded product 1 includes a fixed mold having a valve gate G capable of switching the resin discharge gate Ga by opening and closing of the valve pin 3 (see FIG. 1), and the fixed mold. And a movable mold U for forming a resin molding cavity C (see FIG. 4).
In this embodiment, the fixed mold T2 constitutes a first mold and the movable mold U constitutes a second mold.

As shown in FIG. 6, the fixed mold includes a fixed mold T1 for forming a primary molded resin layer 1A with the movable mold U, and a primary molded resin layer 1A held by the movable mold U. And a fixed mold T2 for integrally molding the secondary molded resin layer 1B.
These fixed molds T1 and T2 are installed in a state where they are adjacent to the fixed mold base T0.
The fixed mold T1 is provided with a first valve gate G1 for feeding the first resin P1 (see FIG. 5) forming the primary molded resin layer 1A. However, the gate type of the fixed type T1 is the first valve gate G1 as an example, and for example, an open gate type may be adopted.
On the other hand, the fixed mold T2 is provided with a second valve gate G2 for feeding the second resin P2 forming the secondary molded resin layer 1B.
A decoration sheet feeding device (not shown) for feeding the transfer sheet 6 (an example of a decoration sheet) into the mold is attached to the fixed mold T2. This decorating sheet feeding device unwinds the roll-shaped transfer sheet 6 from above the fixed mold T2 along the parting surface of the fixed mold T2 as shown by the broken line in FIG. This is a device for winding the transferred sheet 6 under the fixed mold T2. The fixed mold T2 includes a clamp member 7a that presses the fed transfer sheet 6 against the parting surface of the fixed mold T2. The clamp member 7a has a rectangular frame shape as viewed from the mold clamping direction so as to surround the outer periphery of the cavity surface of the fixed mold T2, and operates in the mold clamping direction by an air cylinder or the like. Further, the fixed mold T2 is provided with a suction mechanism S that moves the transfer sheet 6 pressed against the parting surface by the clamp member 7a along the cavity surface. The suction mechanism S sucks the transfer sheet 6 from the cavity surface side.

As shown in FIG. 7, the valve gate G includes a molten resin flow path 8 formed inside in a state of being opened at a substantially central portion of a fixed cavity surface. The valve pin 3 is inserted so as to be slidable along the axis X. The front end opening 8a side of the molten resin flow path 8 is formed in a reduced diameter shape. When the valve pin 3 is slid to the front end side, the front end portion 3a of the valve pin 3 is fitted into the front end opening 8a and the valve gate G is fitted. Can be closed. On the other hand, when the valve pin 3 is slid to the proximal end side, the distal end portion 3a of the valve pin 3 is retracted from the distal end opening 8a, and the valve gate G can be opened.
The tip 3a of the valve pin 3 of the first valve gate G1 is configured as a flat surface (see FIG. 1). With the valve gate G closed, the tip of the valve pin 3 is connected to the cavity surface of the fixed mold T1. It is installed to be flush with each other.
As shown in FIG. 7, the valve pin 3 of the second valve gate G2 has a conical shape as shown in FIG. 7. With the valve gate G closed, the tip 3a of the valve pin 3 is a cavity of the fixed mold T1. It is formed so as to protrude into the cavity C from the surface.

  As a mechanism for holding the transfer sheet 6 against the fixed mold T2, a suction mechanism S in which pores are opened on the cavity surface of the fixed mold T2 is provided (see FIGS. 1 and 3). The suction mechanism S can suck the transfer sheet 6 to the fixed mold T2 by suction, and presses the transfer sheet 6 against the tip 3a of the valve pin 3 of the second valve gate G2 along with the suction. Can do. Therefore, the tip portion 3a may penetrate the transfer sheet 6 by this pressing action, and a through hole 6a (see FIG. 7) through which the molten resin discharged in the subsequent process can pass is formed in that portion. It becomes possible. The suction mechanism S is an example of a holding mechanism H according to the present invention.

As shown in FIG. 6, the movable mold U is in a state in which a pair of identical shapes so as to correspond to the fixed mold T1 and the fixed mold T2 are adjacent to the movable base U0. is set up.
The movable base U0 is supported by the rotating shaft 4 and is configured to be able to reverse the corresponding position with respect to both the fixed molds T1 and T2 by rotating 180 degrees around the axis J.
Accordingly, when one movable mold U corresponds to the fixed mold T1 and the other movable mold U corresponds to the fixed mold T2, the movable substrate U0 is rotated 180 degrees around the axis J, The movable mold is changed to a fixed mold T2 and the other movable mold is opposed to the fixed mold T1.
In addition, the movable mold U is configured to hold the molded primary molded resin layer 1A as it is when rotating around the axis J.

The two-color molded product 1 described in the present embodiment is formed such that the primary molded resin layer 1A is positioned on the lower surface of the product shown in FIG. 2B and the secondary molded resin layer 1B is positioned on the upper surface of the product. The decorative layer 2 is provided on the surface of the secondary molded resin layer 1B.
Further, as shown in FIG. 2C, the central portion of the two-color molded product 1 is finally cut out and formed as a product that does not leave a gate mark.
In addition, the primary molded resin layer 1A was dispersed at three locations around the valve pin 3 as shown in FIG. 2A in a state of protruding to the surface on the secondary molded resin layer 1B side. The rib 9A is integrally provided.
As shown in FIG. 7, these ribs 9 </ b> A are such that when the mold is clamped with the fixed mold T <b> 2 while the primary molding resin layer 1 </ b> A is held on the movable mold U, the rib tip portion is the cavity surface of the fixed mold T <b> 2. It is formed in a height dimension that reaches According to this configuration, when clamping is performed with the transfer sheet 6 disposed along the fixed mold T2, the vicinity of the valve pin 3 in the transfer sheet 6 can be pressed to the fixed mold T2 side by the ribs 9A. The tip 3a of the valve pin 3 bites into the transfer sheet 6, and the through hole 6a can be easily and reliably formed in that portion. The rib 9A corresponds to the pressing portion 9 according to the present invention, and is provided as an example of the holding mechanism H in the same manner as the suction mechanism S.
Further, the rib 9A is arranged in a state in which the length direction thereof is in a radial shape with the valve pin 3 as the center (see FIG. 9A), and when the second resin P2 is discharged into the cavity C, Consideration is made so as not to obstruct filling of the molten resin.

Next, a specific product forming method will be described.
[1] As shown in FIG. 1, the movable mold U is rotationally moved to the position opposed to the fixed mold T2 while holding the primary molded resin layer 1A formed between the fixed mold T1 and the movable mold U.
Further, in the fixed mold T2, the transfer sheet 6 is arranged along the cavity surface by the sheet feeding device 7 in a state where the second valve gate G2 is closed (a state where the tip 3a of the valve pin 3 protrudes), The transfer sheet 6 is pressed against the parting surface by the clamp member 7a.
[2] As shown in FIG. 3, the transfer sheet 6 is drawn to the fixed mold T2 by the suction mechanism S. At this stage, the through hole 6 a may be formed in the transfer sheet 6.
[3] As shown in FIG. 4, the fixed mold and the movable mold U are clamped.
At this stage, each rib 9A of the primary molding resin layer 1A held by the movable mold U presses the position around the valve pin 3 of the transfer sheet 6 to the fixed mold T2 side, and the tip 3a of the valve pin 3 is the transfer sheet. 6, the through hole 6a is reliably formed (see FIG. 7).
[4] As shown in FIG. 5, the first valve gate G1 and the second valve gate G2 are opened, and the molten resin is discharged into the cavity C through the through hole 6a. Then close each gate.
[5] As shown in FIG. 6, when the resin molding is completed, the mold is opened, the two-color molded product 1 facing the fixed mold T2 is removed from the movable mold U, and both movable molds U are rotated 180 degrees. .
Thereafter, each procedure from [1] is repeated.

According to the resin molding technique of the present embodiment, the operation of forming the through hole 6a in the transfer sheet 6 can be easily, reliably and economically performed in a series of resin molding steps.
Further, by pressing the transfer sheet 6 against the fixed mold T2 using the rib 9A of the primary molded resin layer 1A, the through hole can be more reliably formed, and the transfer sheet 6 is stably placed on the fixed mold T2. Since it can fix, the position shift of a decorating sheet can be prevented and the quality improvement of a resin molded product can be aimed at.
In addition, since the rib 9A is formed along the radiation centered on the valve pin 3, the flow of the molten resin in the cavity C is smooth and can be spread quickly to every corner. Can be synergistically improved.

[Another embodiment]
Other embodiments will be described below.

<1> The resin molded product 1 is not limited to the shape and configuration described in the previous embodiment, and can be appropriately changed. For example, in addition to the rectangular shape, any shape such as a shape combining a circular shape or an oval shape, a shape obtained by hollowing out the central portion, or the like can be adopted.
Moreover, it is not limited to a two-color molded product, and may be a one-color molded product or a multi-color molded product having three or more colors.
<2> The resin molding apparatus has been described as a rotary type in the previous embodiment. However, the resin molding apparatus can be a fixed mold (first mold), a movable mold (second mold) that operates in the clamping direction, and a fixed mold. The resin molding apparatus provided with the attached sheet feeding apparatus may be sufficient. The movable mold may further include a sheet feeding device, and may be a resin molding device that decorates both surfaces of the resin molded product.
The primary molded resin layer 1A is a separately formed product, and the primary molded resin layer 1A is fitted into the movable mold U and then clamped, and the resin molded product is discharged by discharging the second resin P2. 1 may be formed.
In the previous embodiment, the sheet feeding apparatus is a roll-to-roll system. However, a sheet feeding system in which transfer sheets are fed one by one may be used.
<3> In the previous embodiment, the decorative layer 2 is formed by using the transfer sheet 6 having the base sheet and the decorative layer, and is peeled from the base sheet and transferred. The layer 2 may be an insert sheet that does not peel off the base sheet. The transfer sheet and the insert sheet are collectively referred to as a decorative sheet.
<4> The holding mechanism H is not limited to the configuration including both the suction mechanism S and the pressing portion 9 described in the previous embodiment, and may be configured by only one of them.
<5> The pressing portion 9 is not limited to that provided in a part of the primary molded product 1A described in the previous embodiment, but is provided in a part of the second molding die U as shown in FIG. It may be a thing.
In the embodiment shown in FIG. 8, the protrusions 9B located at a plurality of positions around the resin discharge gate Ga are formed on the second mold U, and the same function as that of the rib 9A in the previous embodiment. have.
In addition, the shape, number, arrangement, and the like of the pressing portion 9 can be changed as appropriate.
For example, the tip shape of the pressing portion 9 may be a point shape as shown in FIGS. 9B and 9D in addition to the elongated shape described in the previous embodiment.
The number is not limited to being provided at three locations around the gate, but may be provided at two locations or at a plurality of four or more locations as shown in FIGS. 9 (c) and 9 (d).
With respect to the arrangement, when the pressing portion 9 is elongated, the arrangement is such that the side surfaces face each other across the second valve gate G2, as shown in FIG. 9C, instead of the elongated arrangement along the radial shape. May be.
<6> The shape of the tip 3a of the valve pin 3 is not limited to the conical shape described in the previous embodiment, and may be a single character shape, a cross shape, a quadrangular pyramid shape, or the like as shown in FIG. It is preferable that it is formed sharply.

  In addition, as mentioned above, although the code | symbol was written in order to make contrast with drawing convenient, this invention is not limited to the structure of an accompanying drawing by this entry. In addition, it goes without saying that the present invention can be carried out in various modes without departing from the gist of the present invention.

1 Two-color molded product (example of resin molded product)
1A Primary molded resin layer (equivalent to primary molded product)
2 decorative layer 3 valve pin 3a tip 6 transfer sheet (an example of a decorative sheet)
6a Through-hole 7 Sheet feeding device 7a Clamp member 9 Holding part C Cavity Ga Resin discharge gate G2 Second valve gate H Holding mechanism T2 Fixed mold (corresponding to the first mold)
U movable mold (example of second mold)

Claims (7)

A first mold having a valve gate capable of switching opening and closing of the resin discharge gate by the withdrawal and withdrawal of the valve pin;
A second mold that forms a cavity for resin molding with the first mold;
A sheet feeding device that arranges a decorative sheet that forms a decorative layer on the surface of a resin molded product to be molded along the cavity surface of the first mold, and
The valve pin is formed so that a tip portion thereof protrudes from the cavity surface of the first mold into the cavity in a state in which the resin discharge gate is closed,
A resin molding apparatus provided with a holding mechanism for holding the decorative sheet so that the tip portion penetrates the decorative sheet.   2. The resin molding apparatus according to claim 1, wherein the holding mechanism includes a pressing portion that presses the decorative sheet against the first mold at a position in the vicinity of the valve pin.   The resin pressing apparatus according to claim 2, wherein the pressing portion is provided in a part of a primary molded product held by the second molding die.   The resin pressing apparatus according to claim 2, wherein the pressing portion is provided in a part of the second molding die.   The resin pressing device according to any one of claims 2 to 4, wherein the pressing portion is distributedly arranged at a plurality of locations around the valve pin.   The resin pressing apparatus according to claim 2, wherein the pressing portion is formed in an elongated shape along a radiation centered on the valve pin. A first mold having a valve gate capable of switching opening and closing of the resin discharge gate by the withdrawal and withdrawal of the valve pin;
A second mold that forms a cavity for resin molding with the first mold;
The resin molded product is provided by a resin molding device including a sheet feeding device that arranges a decorative sheet for forming a decorative layer on the surface of the molded resin molded product along the cavity surface of the first mold. A resin molding method to be formed,
The decorative sheet is disposed along the cavity surface of the first mold by the sheet feeding device, and the cavity surface of the first mold is closed with the tip portion of the valve pin in a state of closing the resin discharge gate. More protruding into the cavity and penetrating the decorative sheet,
Resin for forming a resin molded product by retreating the valve pin after performing mold clamping, opening the resin discharge gate, and discharging molten resin from the valve gate to the cavity through a through hole formed in the decorative sheet Molding method.

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