JP4765225B2 - In-mold transfer molding method and mold used therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to in-mold transfer molding performed by continuously supplying a transfer film from a roll to a mold having a wide gate.
[0002]
[Prior art]
FIG. 1 schematically shows the entire screw-in-line injection molding apparatus. A mold is arranged at the tip of the screw type extruder, and after the injection molding is completed, the movable mold is moved backward to the left in the figure, and the product is taken out. Molds used for injection molding include those having a wide gate and those having a pin gate.
[0003]
Mold with Pin Gate This is used for injection molding using a material with low viscosity and easy flow, such as polypropylene or polystyrene. In this type of mold, since the gate is pin-shaped, the gate portion is naturally cut when the mold is opened. Therefore, when the product is taken out from the mold, unnecessary gate portions are removed from the molded product at that time.
[0004]
Mold with wide gate <br/> When injection molding is performed using a material with high viscosity and poor flow, such as acrylic or polycarbonate, when the pin gate mold is used, the gate part is thin and strain stress is generated in the molded product. However, it is not suitable for optical parts. Therefore, it is necessary to use a mold having a wide gate in which the resin has good fluidity and no strain stress is generated. In this type of mold, since the gate width is wide, an unnecessary runner portion cannot be removed from the molded product simply by opening the mold. For this reason, it is necessary to remove the runner part after taking out the molded product from the mold. However, when removing the runner part, it is difficult to cut at the gate part of the product, and the appearance is deteriorated. There is a problem.
Therefore, in order to solve this, a technique is known in which the gate part is cut using a gate cut pin before opening the mold, thereby removing unnecessary burrs from the molded product at the same time as opening the mold. .
[0005]
On the other hand, the transfer film is continuously supplied from the roll between the fixed mold and the movable mold, and then the mold is clamped to transfer the film transfer layer to the molded product simultaneously with the injection molding in the mold cavity. A method called in-mold transfer molding is known. In this in-mold transfer molding, gate cut using a gate cut pin could not be performed. The reason will be described with reference to FIG. FIG. 2 is a schematic view showing an enlarged cavity portion of the mold.
[0006]
In FIG. 2, the transfer film is continuously supplied from the upper side and wound up to the lower side. Here, as can be seen with reference to FIG. 1, since the molding material is supplied from the fixed side of the mold, the transfer film needs to be disposed on the movable side of the mold. On the other hand, an extruder exists on the fixed side of the mold, and the gate cut pin needs to be arranged on the movable side in order to interlock with the movement of the ejector rod that performs the protruding operation from the movable side.
[0007]
In the arrangement shown in FIG. 2, when the gate portion is to be cut by the gate cut pin, the gate cut pin first hits the transfer film in the gate portion, and the resin portion existing on the other side of the film from above the transfer film. Will be cut. In other words, the transfer film is in the way and the gate part cannot be cut well, and if it is forcibly cut, the molding resin will be cut before solidification, so the transfer part will be wrinkled and printed. The problem that a part shifts arises.
[0008]
In FIG. 2, for ease of understanding, the transfer film is drawn in a state slightly separated from the movable side recess and the parting line. It is arranged in contact with
[0009]
[Problems to be solved by the invention]
Therefore, the technical problem to be solved by the present invention is to perform gate cut in a cavity using a gate cut pin in performing in-mold transfer molding using a transfer film continuously supplied from a roll. Is to realize.
[0010]
[Means / Actions / Effects to Solve Problems]
The present invention has been made in order to effectively solve the above-described problems, and provides an in-mold transfer molding method and a mold having the following features.
[0011]
The in-mold transfer molding method of the present invention includes a “film supply step of supplying a transfer film between a fixed mold and a movable mold in a mold open state” and “the transfer film is sucked and the transfer film is placed on the surface of the fixed mold "Suction process for extending along the concave portion constituting the cavity of" and "Material introduction process for guiding the molding material supplied from the fixed mold side to the movable mold side beyond the transfer film in the mold clamping state" and " After the molding material is introduced (before the molding material is completely solidified), the gate cut process of cutting the gate part by protruding the gate cut pin from the movable mold side and the mold opening process of opening the mold and taking out the molded product "including.
[0012]
In the in-mold transfer molding method of the present invention, the transfer film exists in the cavity on the side opposite to the gate cut pin with respect to the resin portion. Therefore, the transfer film does not prevent the gate cut by the gate cut pin. As a result, in-cavity gate cutting, which has been impossible in the conventional in-mold transfer molding, becomes possible.
[0013]
In the above-described material introduction step of the in-mold transfer molding of the present invention, it is possible to guide the molding material from the position where the transfer film is not located to the movable mold side, but the molding material is moved through the opening provided in the transfer film. It is preferable to guide to the side. In this case, a transfer film having an opening in advance may be used, but it is also possible to form the opening in the transfer film by using a punching device arranged on the upstream side of the mold.
[0014]
In the above-described suction step of the in-mold transfer molding of the present invention, the transfer film may be pressed to the fixed mold surface using a frame material, and then the transfer film may be sucked to the fixed mold side using negative pressure. In that case, the mold can be slid between the fixed mold surface and the locking head supported by the frame support pin and "the frame support pin protruding from the surface of the fixed mold and having a locking head at the tip" And a “spring that presses and urges the frame material toward the locking head” are used. When the movable mold moves toward the fixed mold during clamping, the movable mold presses the frame material against the spring against the surface of the fixed mold, and as a result, the transfer supplied between the frame material and the fixed mold surface. The film is pressed against the fixed mold surface.
[0015]
Further, in the above mold opening step of the in-mold transfer molding of the present invention, after the transfer film is peeled off from the molded product, the molded product may be pushed out from the molding die with an ejector pin and taken out by a take-out means. . In that case, a mold having a clamp mechanism at the tip of a cylinder mechanism arranged on the movable mold side is used. As the cylinder mechanism expands and contracts, the clamp mechanism can be configured to “the first clamp position where the transfer film is positioned along the movable mold surface when clamping the mold” and “the transfer film is peeled off from the movable mold surface when the mold opening is started. , "Second clamping position for clamping the transfer film near the surface of the fixed mold" and "when the mold opening is completed, a space necessary for entering the take-out means for taking out the molded product between the movable mold and the transfer film. In order to ensure, it can be selectively positioned at the “third clamp position for clamping the transfer film at a certain interval from the movable surface”.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. 3 to 9 are process diagrams illustrating an in-mold transfer molding method according to an embodiment of the present invention.
[0017]
Film supply process ( Figure 3 )
The mold is composed of a fixed mold 20 and a movable mold 30, and the transfer film 10 is continuously supplied between them. The transfer film 10 is supplied from a roll 11 on the upper side in the figure and wound around a roll 12 on the lower side in the figure. FIG. 3 shows a state in which the transfer film 10 is supplied between the fixed mold 20 and the movable mold 30.
[0018]
Clamping state ( Fig. 4 )
After the transfer film 10 is supplied, the movable mold 30 advances from the state shown in FIG. 3 to the fixed mold 20 side to the right side in the figure, and the concave portion 21 and the concave portion 31 formed on the surfaces of both are combined to cause injection. The molding cavity is configured, but at this time, immediately before the movable mold 30 and the fixed mold 20 are completely closed, the clamp mechanism 38 fixed to the rods of the cylinders 37 arranged on both sides of the movable mold 30 is transferred film 10 is clamped between the movable mold 30 and the transfer film 10 is pressed against the surface of the movable mold 30 (first clamping position). Note that the transfer film 10 may be pressed against the surface of the fixed mold 20 by using another clamping mechanism described later with reference to FIGS.
[0019]
Suction process ( Figure 5 )
From the state of FIG. 4, the transfer film 10 in the injection molding cavity is sucked along the surface of the fixed mold 20 by a negative pressure means (not shown). The negative pressure means sucks the transfer film 10 in the cavity using a negative pressure source communicated with a suction port opened in the recess 21. The negative pressure source may be arranged separately from the mold or attached to the fixed mold 20 itself. A molding die used in the in-mold transfer molding method of the present invention includes a movable die and a fixed die, and is characterized in that negative pressure means is provided on the fixed die side instead of the movable die.
[0020]
Material introduction process ( Fig. 6 )
FIG. 6 shows the material introduction process after mold clamping. After the transfer film 10 is sucked into the fixed mold 20 in the cavity, the molding material is fed from the extruder 15 into the cavity. FIG. 6 shows a state after the molding material is filled in the cavity.
[0021]
An injection molding material (acrylic, polycarbonate, etc.) is supplied from an extruder 15 existing on the right side in the figure through a sprue in the fixed mold 20. At this time, as will be described later with reference to FIG. 12, the molding material passes through the opening 19 formed in the transfer film 10 and is guided to the movable mold 30 side. That is, in the state of FIG. 6, the injection molding material filled in the cavity presses the transfer film 10 from the movable mold 30 side to the fixed mold 20 side. A predetermined pattern or the like is printed on the transfer film 10, and the pattern or the like is transferred to the surface of the molded product in the cavity simultaneously with the injection molding.
[0022]
Gate cut process ( Figure 7 )
FIG. 7 shows that after injection molding, the ejector rod 39 moves to the right side in the figure, whereby the gate cut pin 32 advances toward the fixed mold 20 side, and the gate part of the molded product in the cavity is cut. It shows the state. At this time, as will be described later with reference to FIG. 14, since the transfer film 10 is present on the fixed mold 20 side, the cutting of the resin portion by the gate cut pins 32 is not hindered.
[0023]
Mold opening process ( Figs. 8 and 9 )
After the gate portion is cut by the gate cut pin 32, the movable mold 30 moves backward to the left in the figure so as to be separated from the fixed mold 20. At this time, in order to peel off the transfer film 10 from the molded product, the clamp mechanism 38 does not move backward together with the movable mold 30, but remains at the position while maintaining the relative position with respect to the fixed mold 20 in the state of FIG. (Second clamp position). To achieve this, when the movable mold 30 is retracted to the left, the first rod 37a of the cylinder 37 is extended (FIG. 8).
Thereafter, when the movable die 30 is further retracted, the ejector rod 39 advances relatively toward the fixed die 20, and as a result, the ejector pin 33 pushes the molded product 35 and the runner portion 36 away from the surface of the movable die 30. At this time, the second rod 37b of the cylinder 37 is extended to increase the space between the movable mold 30 and the film 10 (third clamp position). This is to secure a space for an unillustrated unloader (unloading means) to unload the extruded molded product 35 and the runner portion 36 by air suction or chucking.
In the molding method of the present invention, since the gate is cut in the cavity, the runner portion 36 has already been cut from the molded product 35 when the mold is opened. Thereafter, the next injection molding is performed in the same manner as described above.
[0024]
The clamp mechanism 38 used in the embodiment described above is disposed at the tip of a cylinder mechanism 37 that is independent from the movable mold 30. Therefore, there is an advantage that it can be used universally for the movable mold 30 of any shape.
[0025]
Another example of clamp mechanism ( Figs. 10 to 13)
Another example of the clamping mechanism will be described below with reference to FIGS. In the embodiment described with reference to FIGS. 3 to 9, the clamp mechanism is provided on the cylinder 37 provided on the movable mold 30 side. However, in the example described below, the clamp mechanism is provided on the fixed mold 20 side. It has been. Further, this clamping mechanism is different from the above-described one, and presses the transfer film 10 against the surface of the fixed mold 20.
[0026]
FIGS. 10 and 11 are explanatory views showing a clamping mechanism provided in the fixed mold 20, FIG. 10 shows a mold open state, and FIG. 11 shows a mold clamped state. FIG. 12 is a schematic view showing the surface of the fixed mold 20 as seen from the direction of line 12-12 in FIG. In FIG. 10, the transfer film 10 is sent from above to below via rollers 151 and 152.
[0027]
Four frame support pins 120 protrude from the surface of the fixed mold 20, and each frame support pin 120 has a locking head 121 at its tip. In FIG. 10 and FIG. 11, only two frame support pins appear, but in FIG. 12, four locking heads 121 appear, and it can be seen that there are four frame support pins 120. Each frame support pin 120 is stationary. The frame support pin 120 supports the frame material 130. As shown in FIG. 12, the frame member 130 includes a frame portion 130a that forms four sides of a rectangle, and two frame portions 130b that extend in parallel inside the frame portion 130a. The frame material 130 is slidably supported in the vicinity of the surface of the fixed mold 20 by passing the frame support pins 120 through through holes formed in the four corner portions (see FIG. 10).
[0028]
A spring 123 is extrapolated to each frame support pin 120, and this spring 123 presses and urges the frame member 130 to press against the locking head 121 as shown in FIG. Therefore, in the mold open state, a certain space is secured between the surface of the fixed mold 20 and the frame material 130, and the transfer film 10 is passed through this space. The frame material 130 also serves to peel off the transfer film 10 from the molded product when the mold is opened.
[0029]
When the movable mold 30 moves forward from the state of FIG. 10 toward the fixed mold 20, the convex region 131 in which the concave portion 31 on the surface of the movable mold 30 is formed enters between the two frame portions 130b of the frame material 130. At the time of mold clamping, the frame material 130 is pushed by the movable mold 30 and pressed against the surface of the fixed mold 20 against the spring 123. At this time, the spring 123 is accommodated in the spring accommodating recess 126 provided on the surface of the fixed mold 20.
[0030]
In the mold clamping state of FIG. 11, the tip of the frame support pin 120 is accommodated in a hole 133 formed on the surface of the movable mold 30, and the guide pin 132 protruding from the surface of the movable mold 30 is formed on the surface of the fixed mold 20. It is accommodated in the guide hole 125.
[0031]
In the state of FIG. 11, the outlet from the sprue of the fixed mold 20 to the runner is aligned with the opening 19 (see FIG. 12) formed on the surface of the transfer film 10. The opening 19 is formed by the punching device 40 (see FIGS. 3 to 9) after the transfer film 10 is pulled out from the roll 11. The injection molding material extruded from the extruder 15 can move from the fixed mold 20 side to the movable mold 30 side beyond the transfer film 10 by passing through the opening 19.
[0032]
As shown in FIG. 12, a predetermined pattern 10a to be transferred to the molded product is printed on the surface of the transfer film 10. The printing position of the pattern 10a is set so that the pattern 10a is located in the recesses 21 and 31 constituting the cavity in the mold-clamping state of FIG. 10 and FIG. 11 correspond to the AA line cross section in FIG. 12, and FIG. 13 corresponds to the BB line cross section (clamping state) in FIG. It can be seen that the frame material 130 is held and fixed between the fixed mold 20 and the movable mold 30 in the clamped state.
[0033]
Effects of the present invention ( FIG. 14)
As described above, in the cavity after injection molding, the transfer film 10 is positioned on the fixed mold 20 side with respect to the molded product. FIG. 14 is a cross-sectional view schematically showing this and corresponds to FIG. However, in FIG. 14, only the cavity below the gate cut pin is shown. By comparing FIG. 2 with FIG. 14, the difference between the conventional example and the present invention regarding the position of the transfer film in the cavity can be clearly understood. That is, in the conventional example of FIG. 2, the transfer film hinders the resin part from being cut in the gate cut by the gate cut pin. However, in the present invention of FIG. Since it exists on the opposite side to the pin, the gate cut by the gate cut pin is not prevented. In FIG. 14, the transfer film is drawn as if it exists only in the cavity, but in actuality, as described with reference to FIGS. It extends to.
[0034]
In the embodiment described above, the molding material supplied from the fixed mold 20 side is guided to the movable mold 30 side through the opening 19 formed in the transfer film 10. However, in the present invention, the method of guiding the molding material to the movable mold 30 side is not limited to such a method. For example, a plurality of transfer films of two rows or more are arranged in parallel with the movable mold 30. The molding material may be moved from the fixed mold 20 side to the movable mold 30 side through a flow path provided between the fixed mold 20 and each transfer film. When such a configuration is adopted, it is not necessary to provide the opening 19 in the transfer film 10.
[Brief description of the drawings]
FIG. 1 is a schematic view showing the whole of a conventional screw-in-line type injection molding apparatus.
FIG. 2 is a schematic diagram for explaining the reason why gate cut by a gate cut pin is impossible in conventional in-mold transfer molding.
FIG. 3 is a process diagram illustrating a film supply process for in-mold molding according to the present invention.
FIG. 4 is a process diagram showing a state in which a mold is closed from the state of FIG. 3;
FIG. 5 is a process diagram illustrating an in-mold suction step according to the present invention.
FIG. 6 is a process diagram for explaining a material introduction process for in-mold molding according to the present invention.
FIG. 7 is a process diagram illustrating a gate cut process of in-mold molding according to the present invention.
FIG. 8 is a process diagram illustrating a mold opening state after the gate cutting process of FIG. 7;
FIG. 9 is a process diagram for explaining a state in which a mold is opened and a product is taken out in in-mold molding according to the present invention.
FIG. 10 is an explanatory view for explaining a clamping mechanism of the mold according to the present invention.
FIG. 11 is an explanatory view for explaining a clamping mechanism of a mold according to the present invention.
FIG. 12 is an explanatory view for explaining a clamping mechanism of a mold according to the present invention.
FIG. 13 is an explanatory view for explaining a clamping mechanism of a mold according to the present invention.
FIG. 14 is a schematic cross-sectional view illustrating the effect of the present invention in comparison with FIG.
[Explanation of symbols]
10 Transfer film
15 Extruder
19 opening
20 Fixed type
21 recess
30 Movable type
31 recess
32 Gate cut pin
33 Ejector pin
35 Molded products
36 Runner part
37 cylinders
38 Clamp mechanism
39 Ejector rod
40 punching device
120 Frame support pin
121 Locking head
123 Spring
130 Frame material

Claims (8)

In-mold transfer that continuously supplies the transfer film (10) between the fixed mold (20) and the movable mold (30) constituting the mold and simultaneously performs injection molding and transfer in the cavity of the mold A molding method,
A film supply process for supplying the transfer film (10) between the fixed mold (20) and the movable mold (30) in the mold open state;
A suction step of sucking the transfer film (10) and extending the transfer film along the recess (21) constituting the cavity of the fixed mold surface;
A material introduction process for guiding the molding material supplied from the fixed mold side in the mold clamping state to the movable mold side beyond the transfer film;
After material introduction and before mold opening, the gate cut pin (32) protrudes from the movable mold side to cut the gate part, and
A mold opening step of opening the mold and taking out the molded product.   In the suction step, the transfer film is pressed against the surface of the fixed mold using the frame material (130), and then the transfer film is sucked to the fixed mold side using negative pressure. In-mold transfer molding method. In the suction step, after clamping the transfer film between the clamp mechanism and the movable mold (30) with the clamp mechanism provided on the movable mold (30) side,
2. The in-mold transfer molding method according to claim 1, wherein the transfer film is sucked to the fixed mold (20) side by using a negative pressure. In the mold opening step, after the transfer film (10) is peeled from the molded product (35),
The in-mold transfer molding method according to claim 1, characterized in that the molded product (35) is pushed out from the molding die with an ejector pin, and the molded product (35) is taken out by the ejecting means.   2. The in-mold transfer molding method according to claim 1, wherein in the material introduction step, the molding material is guided to the movable mold side through an opening (19) provided in the transfer film (10).   6. The in-mold transfer molding method according to claim 5, wherein the opening (19) of the transfer film (10) is formed by a punching device (40) arranged on the upstream side of the mold. A molding die comprising a fixed die (20) and a movable die (30), and used for the in-mold transfer molding method according to claim 2,
A frame support pin (120) protruding from the surface of the fixed mold (20) and having a locking head (121) at the tip;
A frame material (130) supported by the frame support pin (120) and slidable between the fixed mold surface and the locking head (121);
A spring (123) that presses and urges the frame material (130) toward the locking head,
When the movable mold (30) moves toward the fixed mold (20) during clamping, the movable mold (30) presses the frame material (130) against the spring (123) against the surface of the fixed mold, and As a result, the molding die characterized in that the transfer film (10) supplied between the frame material (130) and the stationary mold surface is pressed against the stationary mold surface. 5. A molding die comprising a fixed die (20) and a movable die (30) and used in the in-mold transfer molding method according to claim 4, wherein a cylinder mechanism (37) disposed on the movable die (30) side Has a clamp mechanism (38) at the tip of
As the cylinder mechanism (37) expands and contracts, the clamp mechanism (38)
A first clamping position for positioning the transfer film along the surface of the movable mold (30) during mold clamping;
A second clamping position for clamping the transfer film in the vicinity of the surface of the fixed mold (20) in order to peel off the transfer film from the surface of the movable mold (30) at the start of mold opening;
When the mold opening is completed, a certain distance from the surface of the movable mold (30) is secured between the movable mold (30) and the transfer film (10) in order to secure a space necessary for the removal means to take out the molded product. And a third clamping position for clamping the transfer film (10), and a molding die.

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