JP2007253494A - In-mold coating molding method, in-mold coating molding device and in-mold coating molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a shrink liable to occur of a molded product and leakage of coating from a mold, in performing in-mold coating molding wherein the mold clamping force exerted at a resin cooling time, when the shape of a resin molded product is decided, is made equal to the mold clamping force at a coating curing time, for controlling the deformation of the mold occurring when molded to uniformize the thickness of the coating. <P>SOLUTION: During a coating curing process (fourth process), the initial mold clamping force is increased in multi-stages at least two steps or more to be the final mold clamping force, and during a resin molding process (second process), the initial mold clamping force is decreased to be the final mold clamping force. In this invention, during the coating curing process when the mold clamping force is increased, the viscosity of the coating within the mold is increased to cause the coating hard to flow, preventing the leakage of the coating flowing out of the mold and also the shrink of the molded product occurring even during the resin molding process. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, after the resin is molded in the mold, a coating agent (sometimes referred to as a paint) is injected between the resin molded product and the mold cavity surface and cured, whereby the surface is coated with the coating agent. In-mold coating method for coating (sometimes referred to as coating film), and particularly suitable for molding a molded product having a uniform coating thickness and good appearance, and in-mold coating The present invention relates to a molding apparatus and an in-mold coated molded product.

  Conventionally, decorating by a coating method is often used as a method for enhancing the decorativeness of a resin molded product molded from a thermoplastic resin.

  In a conventional coating method, after a molded product injection-molded in a mold is taken out from the mold, a paint is generally applied by a spray method or a dipping method. The applied paint is then dried to form a strong coating film that covers, decorates and protects the surface of the molded product.

  However, in recent years, an in-mold coating method (sometimes referred to as an in-mold coating method) in which the resin is molded and coated in the same mold has been proposed for the purpose of omitting the process by the coating method. Has been.

  Examples of the in-mold coating forming method are shown in Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4.

Japanese Patent Laid-Open No. 11-277577 JP 2000-141407 A JP 2000-334800 A JP 2001-38737 A

  According to the in-mold coating molding method, since the molding and coating of the thermoplastic resin are performed in the same mold, the cost can be reduced by omitting the process, and the floating dust before curing is cured. Since it hardly adheres to the coating (sometimes referred to as a coating film) and becomes defective, a high quality coated product can be obtained.

  For this reason, use of the in-mold coating forming method is being studied for automobile parts that require high quality in appearance, such as bumpers, doors, door mirror covers, and fenders.

By the way, the conventional in-mold coating molding method has a problem that the thickness of the coating is not uniform due to the deformation of the mold during molding.
This is because the mold used for the in-mold coating forming method generally has high rigidity, but when the mold is clamped by a mold clamping device, it is deformed on the order of several μm to several tens of μm.
In ordinary resin molding, this degree of deformation is hardly a problem, but in the in-mold coating molding method, a coating agent may be applied to the surface of the resin molded product with a thickness of about several tens of μm. A change in the shape of the mold cavity due to the deformation is one of the causes that the thickness of the coating agent is not uniform.

As a method for solving this problem, Patent Document 5 discloses an in-mold coating molding technique that approximates the mold deformation in the resin molding process and the mold deformation in the paint curing process.
International Publication No. 2004/048067 Pamphlet

The technique of in-mold coating molding disclosed in Patent Document 5 focuses on the reason that the thickness of the coating agent is not uniform is due to mold deformation during molding, as conceptually illustrated in FIG. The mold cavity deformation mode and the amount of deformation when the resin is cooled can be determined by making the mold clamping force during resin cooling, which determines the shape of the resin molded product, the same as the mold clamping force during paint curing. And the process at the time of curing the paint.

In other words, even if the shape of the mold cavity is somewhat deformed by the clamping force during resin cooling, which determines the shape of the resin molded product, the shape of the mold cavity is also similarly deformed when the paint is cured. The thickness becomes uniform.
The technique disclosed in Patent Document 5 makes the thickness of the coating uniform by approximating the deformation mode and deformation amount of the mold cavity in the process of cooling the resin and curing the paint based on the above-described theory.

By the way, in the case of carrying out the in-mold coating molding method by the method of Patent Document 5, the mold clamping force at the time of resin molding and the mold clamping force at the time of curing the paint are made substantially the same in consideration of deformation of the mold. A case is assumed.
However, generally speaking, in many cases, the mold clamping force used during resin molding is higher than the mold clamping force used during paint curing. For this reason, when the mold clamping force in the two steps is made to be the same to reduce the mold clamping force during resin molding, there is a possibility that defects such as sink marks may occur in the molded product. Further, when the mold clamping force of the two processes is combined to increase the mold clamping force at the time of curing the paint, there is a possibility that the paint leaks out of the mold.

  Therefore, when the mold clamping force during resin molding is the same as the mold clamping force during paint curing, the mold clamping force during resin molding is slightly reduced and the mold clamping force during paint curing is adjusted slightly higher. Therefore, adjustment is made so that the two mold clamping forces are combined within the range in which the above-mentioned defects do not occur. However, the possibility of occurrence of the defects is affected by the type of paint and the shape of the product. In the case where it could not be exhausted, there was a possibility that sink marks or paint leakage would occur in the molded product.

If the mold clamping pressure cannot be adjusted as described above, it is necessary to remodel the mold to change the product shape of the part where sink marks are likely to occur, or to strengthen the mold leakage prevention. However, mold remodeling is expensive and time consuming and inefficient.
Therefore, there is a need for in-mold coating with a wide range of application that does not require modification of the mold, etc., even if the type of paint or the shape of the product changes, or can minimize the modification of the mold. It was.

The present invention has been made in view of the above problems, and is an in-mold coating molding method, an in-mold coating molding apparatus, and an in-mold coating suitable for molding a molded article having a uniform coating thickness and a good appearance. A molded article is provided.

In order to solve the above problems, the in-mold coating molding method according to the present invention is:
(1) Using a mold having a mold cavity formed by a male mold and a female mold, molding a resin molded product in the mold cavity and coating the surface of the resin molded product In the molding method, a first step of filling the mold cavity with a molten resin, and after filling the mold cavity with a molten resin, the volume of the mold cavity is reduced while melting in accordance with the thermal shrinkage of the molten resin. A second step of forming a resin molded product by shaping the resin, and slightly opening the mold when the resin molded product is solidified to withstand the injection pressure and flow pressure of the coating A third step of forming a gap for injecting the coating agent between the resin molded product and the mold cavity surface; and a fourth step of injecting the coating agent into the gap and clamping the mold again. In the fourth step, the initial mold The clamping force is increased so that the final clamping force in the fourth step is substantially the same as the final clamping force in the second step.

(2) In the in-mold coating forming method according to (1), in the fourth step, the initial mold clamping force is increased in multiple stages of at least two stages to obtain a final mold clamping force. .

(3) In the in-mold coating forming method according to (1) or (2), in the second step, the initial mold clamping force is reduced to obtain the final mold clamping force.

(4) The in-mold coating forming method according to any one of (1) to (3), wherein a resin is injected and filled into a mold whose clamping force is controlled in the first step. In this case, the final mold clamping force in the second step is reduced to be smaller than the mold clamping force in the first step.

In order to solve the above-mentioned problem, an in-mold coating molding apparatus according to the present invention includes:
(5) In-mold coating that uses a mold having a mold cavity formed by a male mold and a female mold to mold a resin molded product and coat the surface of the resin molded product in the mold cavity In the molding apparatus, a first step of filling the mold cavity with the molten resin, and after filling the mold cavity with the molten resin, the volume of the mold cavity is reduced while matching the thermal shrinkage of the molten resin. A second step of forming a resin molded product by shaping the resin, and slightly opening the mold when the resin molded product is solidified to withstand the injection pressure and flow pressure of the coating agent, A third step of forming a gap for injecting the coating agent between the mold cavity surface and a fourth step of injecting the coating agent into the gap and clamping the mold again are sequentially performed. In the fourth step, the initial clamping force is reduced. The final mold clamping force is made substantially the same as the final mold clamping force in the second step by increasing the pressure in at least two stages.

Further, the in-mold coated molded product according to the present invention is:
(6) Molded by the in-mold coating molding method described in any one of (1) to (4).

According to the in-mold coating molding method or apparatus of the present invention, in order to make the coating thickness uniform, in order to control the deformation of the mold during molding, the mold at the time of resin cooling in which the shape of the resin molded product is determined. In the case where the clamping force is made the same as the mold clamping force when the paint is cured, the mold clamping force when the paint is cured is gradually increased.
As a result, in the molding stage where the mold clamping force is increased, the paint in the mold is in a state where the viscosity becomes high and it is difficult for the paint to flow.
Therefore, since a high mold clamping force can be finally applied even in the paint curing process of the in-mold coating, the product is difficult to sink during molding, and the possibility of the paint leaking out can be reduced.

  Hereinafter, an example of a preferred embodiment of an in-mold coating molding method and an in-mold coating molding apparatus according to the present invention will be described with reference to the drawings.

1 to 8 relate to the embodiment of the present invention, and FIGS. 1 and 2 are diagrams for explaining the steps of the in-mold coating forming method according to the present embodiment. FIG. 3 is an overall configuration diagram illustrating the overall configuration of the in-mold coating molding apparatus used in the present embodiment, and FIG. 4 is a diagram illustrating the configuration of the in-mold coating molding die used in the present embodiment. It is sectional drawing which showed the outline structure.
5-8 is a figure explaining the process of the in-mold coating formation method in connection with other embodiment by this invention. 9-11 is a figure for demonstrating the process of the in-mold coating method by the conventional method as a comparison.

  First, a preferred example of the in-mold coating molding die apparatus 10 (also referred to as the mold 10) used in this embodiment will be briefly described with reference to FIG.

  The mold 10 according to the present invention includes a movable mold 14, a fixed mold 12, and a paint injector 50. In the embodiment shown in FIG. 4, the movable mold 14 is a female mold, and the fixed mold 12 is a male mold. The shape of the mold cavity 15 of the mold 10 includes a side wall portion extending along the mold opening / closing direction and a bottom surface portion on the outer periphery of the mold cavity 15, so-called a box having an opening. It is a type.

  In the mold 10, a fixed mold 12 that is a male mold and a movable mold 14 that is a female mold are fitted together at a fitting portion of a shear edge structure (sometimes referred to as a “squeezing structure”). A mold cavity 15 is formed inside, and a fitting portion (sometimes referred to as a squeezed portion) of the shear edge structure is formed over the entire circumference of the mold cavity 15. The mold 10 has a structure that prevents the resin, paint, and the like filled in the mold cavity 15 at the fitting portion from leaking out of the mold 10.

Next, the paint injector 50 will be briefly described. The coating material injection machine 50 in the present embodiment is attached to the movable mold 14 so that the coating material can be injected into the mold cavity 15 from the coating material injection port 51 provided on the mold cavity surface of the movable mold 14. It is configured.
In addition, a valve (not shown) is attached to the coating material injection port 51 of the coating material injection machine 50. When the resin used as the base material is injection-molded, the valve is closed, so The resin injected into the cavity 15 is prevented from entering the paint injector 50 from the paint inlet 51.

  The coating material injection machine 50 in the present embodiment is driven by a driving device (not shown), and the coating material supplied into the coating material injection machine 50 is accurately applied from the mold cavity surface of the movable mold 14 by a desired amount. It is configured to be able to be injected into the mold cavity 15.

  Although the coating material injection machine 50 in the present embodiment is configured to inject the coating material from the mold cavity surface of the movable mold 14 as described above, the present invention is not limited to this, and in the mold cavity 15 described later. What is necessary is just to comprise so that a coating material can be inject | poured into the clearance gap produced between the molded resin molded product and a mold cavity surface, and if the conditions are satisfy | filled, the coating material injection | pouring machine 50 will be attached to the fixed mold | type 12, etc. Also good.

Next, the configuration of a preferable example of the in-mold coating forming apparatus 100 according to the present embodiment will be briefly described with reference to FIG.
3 includes an injection device 30 and a mold clamping device 20. The injection device 30 includes an injection cylinder 40, a hopper 38, a barrel 32, a screw 34, and the like. This is an injection unit provided with a so-called in-line injection mechanism.
The mold clamping device 20 includes a fixed plate 29, a movable plate 28, an end plate 25, a mold clamping cylinder 22, a toggle type mold clamping mechanism 23, and the like.
3 includes a control device 60 including a mold clamping control device 61 and an injection control device 63, and a paint injection control device 52, each of which transmits a signal to each other. Send and receive to synchronize.
In the present embodiment, the so-called in-mold coating molding apparatus 100 including the so-called hydraulic injection apparatus 30 and the mold clamping apparatus 20 is used. However, the present invention is not limited to this. Needless to say, it may be an electric in-mold coating forming apparatus 100 equipped with an electric servo motor, a ball screw, and the like, and may be changed without departing from the scope of the present invention.

Hereinafter, a preferable example of the in-mold coating forming method according to the present embodiment will be described with reference to FIGS. 1 and 2.
In the in-mold coating molding method according to the present embodiment, the mold cavity 15 is formed by clamping the mold 10 by the mold clamping device 20 as the first step.
The mold cavity 15 formed at this time has a thickness direction (molded product in the mold opening / closing direction) corresponding to the mold opening amount of the mold during resin molding described later with respect to the dimensions of the desired resin molded product. (Thickness) is made smaller.
The mold clamping pressure at this time is such that the mold 10 is slightly opened by the pressure of the molten resin after the molten resin is injected into the mold cavity 15 in the resin injection process described later. It is preferable to use a tightening force.

  This is because a slightly larger amount of molten resin than the volume of the mold cavity 15 is injected into the mold cavity 15, so that shaping is performed at the time of molding a resin molded product (first and second steps described later). This is because by applying pressure to the resin until the end of the mold, the mold deformation pattern at the time of molding the resin molded product is brought close to the mold deformation pattern at the time of injecting the paint that applies pressure to the paint by the clamping force. .

After the mold 10 is clamped with the above-described configuration, the injection device 30 injects a thermoplastic resin as a base material into the mold cavity 15 in a molten state (in this embodiment, the base ABS resin: UT20B manufactured by Ube Saikon Co., Ltd.).
When filling the molten resin, the hydraulic pressure of the clamping cylinder 22 arranged in the toggle type clamping mechanism 23 is adjusted by the clamping control device 61 so that the clamping force of the clamping device 20 is not changed as much as possible. It is preferable to do.

In the present embodiment, when the maximum value of the mold clamping force P is Pmax, the surface pressure Mmax per unit area divided by the projected area S when the shape of the resin molded product is projected from the mold opening / closing direction is It was about 30 MPa (megapascal).
The surface pressure Mmax depends on many factors such as the shape and size of the molded product, the type of resin, the melting temperature, and the like, but some injection compression or injection press called a low pressure molding method. Except for the method, it is generally at least 30 MPa or more.

  Next, after the injection of the molten resin into the mold cavity 15 is completed, the process proceeds to the second step, where the molten resin is cooled and solidified to the extent that it can withstand the injection pressure of the coating agent described later (referred to as a semi-solid state). There is also a process of making it possible.

Here, the volume of the mold cavity 15 is set to the desired dimensional volume of the resin molded product by opening the mold 10 slightly with the pressure of the filled molten resin immediately after the completion of the injection of the molten resin. On the other hand, it is larger by an amount corresponding to the mold opening amount of the mold 10.
When the mold 10 is clamped in this state, the mold 10 is gradually closed in accordance with the thermal contraction of the molten resin in the mold cavity 15, and the volume of the mold cavity is reduced and the mold cavity is reduced. The molten resin can be shaped into a shape. At this time, a slight gap due to thermal contraction is gradually generated in the side wall portion of the resin molded product.

In the present embodiment, in this second step, the mold clamping force is reduced and reduced compared to the first step, and the surface pressure per unit area obtained by dividing the mold clamping force by the projected area S of the resin molded product is obtained. Make it smaller.
In the present embodiment, the surface pressure M2 in the second step is 20 MPa.

  After cooling the resin molded product as the base material, the process proceeds to the third step, the mold clamping device 20 is operated, the movable platen 28 is moved slightly to the anti-mold 10 side, and the mold is slightly opened ( In this embodiment, the movable mold 14 is moved in the mold opening direction by about 2 mm), and the paint is injected between the resin molded product molded in the mold cavity 15 and the mold cavity surface of the movable mold 14. A gap (sometimes referred to as a void) is generated.

  After the gap is generated, a command signal is transmitted to the paint injector 50 by the paint injection controller 52, and 6 ml (milliliter) of paint is injected from the paint inlet 51 into the mold cavity 15 by the paint injector 50. Then, the paint starts to flow into the gap generated by the mold opening and the gap generated in the side wall portion.

In addition, the coating surface area of the molded product shape | molded by this embodiment is 600 cm < ² >, and the thickness of coating | cover becomes about 0.1 mm. The paint used in the present embodiment is Praglas # 8000: white (manufactured by Dainippon Paint Co., Ltd.).

  After injecting the paint, the process proceeds to the fourth step, the movable mold 14 is moved in the direction of the fixed mold 12, the mold 10 is closed again and the mold is clamped, and the paint in the gap is made to flow while being spread, The surface of the resin molded product as a base material is coated with a paint.

  In the present embodiment, the final mold clamping force in the fourth step is controlled to adjust the surface pressure M3 per unit area divided by the projected area S of the resin molded product to about 20 MPa, so that the second step Although the surface pressure M2 and the surface pressure M3 are the same, the pressure is not increased to 20 MPa at once, but the mold clamping force is increased in two steps. First, the surface pressure is set to 10 MPa and held for 3 seconds. Thereafter, the mold clamping control device 60 controls the pressure to 20 MPa.

  Then, the final mold clamping force in the fourth step is held until the paint is cured in the mold, and after the paint is cured to the extent that the product can be taken out, the mold clamping force is released and the mold is enlarged. Open and take out the in-mold coated product. The taken-in-mold coated molded product was a molded product having no sink and good appearance.

Hereinafter, the superiority of the in-mold coating molding according to this embodiment will be described.
As described above, the reason why the thickness of the coating agent does not become uniform at the time of in-mold coating is that the mold is deformed at the time of molding, and the final clamping force in the second step and the final in the fourth step. By making the mold clamping force the same, the deformation mode and deformation amount of the mold cavity 15 can be approximated in the second step and the fourth step.
This is effective if the mold clamping force in the second step and the final mold clamping force in the fourth step are as close as possible, but the effect is improved as they are closer.
Further, in the second step, the initial mold clamping force is stepped down and gradually reduced in a multistage manner, and finally reduced as much as possible, so that the amount of deformation of the mold can be reduced. It is effective and is a preferred form.
Further, as a preferable range, the mold clamping force is adjusted so that the final mold clamping force in the second step and the final mold clamping force in the fourth step are substantially the same, and in the second step and the fourth step. The difference in the surface pressure (the pressure per unit area obtained by dividing the mold clamping force by the projected area S of the resin molded product) is within 10 MPa, and more preferably, the difference in the surface pressure is within 5 MPa. It is preferable that the final clamping force in the second step and the final clamping force in the fourth step be the same.

When considering the shaping of the resin, the required surface pressure is usually 30 MPa or more in many cases.
Therefore, as shown in FIG. 10, when a resin molded product is molded with a high mold clamping force and the mold clamping force at the time of curing the paint is increased to this pressure at once, the flow is not yet cured. The high-quality paint enters the gap in the mold with high pressure, and as a result, the risk of the paint leaking out of the mold becomes extremely high.

On the other hand, as shown in FIG. 9, if a resin molded product is molded with a low clamping force, defects such as sink marks may occur in the resin molded product.

As described above, with the conventional in-mold coating method, it may occur that the mold must be remodeled to deal with this problem, and the remodeling of the mold cannot prevent sink or paint leakage. If there is a situation where it is not possible, the possibility of being unable to be molded cannot be completely discarded.
For example, in the mold 10 that prevents the leakage of the paint at the fitting portion having the shear edge structure, there is a limit in enhancing the leakage prevention effect, and the paint leaks completely from the inside of the mold. Cases that cannot be prevented are also assumed.

In contrast, in the present embodiment, the mold clamping force in the second process is smaller than the mold clamping force in the first process in order to bring the mold clamping force during resin molding close to the mold clamping force during paint curing. In addition, the pressure increase of the mold clamping force in the fourth step is set to two steps, and first, the mold clamping force is first held for 3 to 5 seconds so that the surface pressure becomes 10 MPa. In the state where the curing of the coating is advanced to increase the viscosity, and the viscosity of the coating is increased so that it is difficult to flow through the minute gap, the mold clamping force is increased so that the surface pressure becomes 20 MPa.
The paint having a high viscosity is difficult to leak from the mold 10, and as a result, even when a mold clamping force is applied to the surface pressure of 20 MPa at the time of curing of the paint, the paint is not removed from the mold 10. The possibility of leakage can be reduced.

  In other words, if the mold clamping force at the time of curing of the paint can be increased, it can be said that the mold clamping force in the second step can be increased, and this can also reduce sink marks and the like. It is. Therefore, in the present embodiment, an excellent product without sink can be molded even in a state where the risk of leakage of paint is reduced.

Next, another embodiment according to the present invention will be briefly described with a focus on differences from the above-described embodiment.
The in-mold coating forming method according to the second embodiment of the present invention will be described below with reference to FIG.
First, as a first step, the mold 10 is closed by the mold clamping device 20 to form the mold cavity 15. In this case, the volume of the mold cavity 15 is the same as that of the above-described embodiment.

After the mold cavity 15 is formed, the injection device 30 is used to inject the thermoplastic resin as a base material into the mold cavity 15 in a molten state (in the second embodiment, ABS resin: Ube Saikon as the base material) Manufactured by UT20B).
Also, in the second embodiment, as in the previous embodiment, when the molten resin is filled, the mold clamping is performed so that the volume of the mold cavity 15 is increased by opening the mold 10 by the filling pressure of the molten resin. Control power.

  After the injection of the molten resin into the mold cavity 15 is completed, the process proceeds to a second step, where the molten resin is cooled and solidified to the extent that it can withstand the coating agent injection pressure described later. In the second embodiment, the mold clamping force in the second step is the same as that in the first step, and the surface pressure per unit area divided by the projected area S of the resin molded product is 30 MPa.

  When the mold 10 is clamped in this state, the mold 10 is gradually closed in accordance with the thermal contraction of the molten resin in the mold cavity 15 to shape the molten resin.

  After cooling the resin as the base material, the process proceeds to the third step, where the mold is slightly opened (in the second embodiment, the movable mold 14 is moved in the mold opening direction by about 2 mm), A gap is formed between the resin molded product molded in the mold cavity 15 and the mold cavity surface of the movable mold 14.

After the gap is formed, when 6 ml of the paint is injected into the mold cavity 15 from the paint injection port 51 by the paint injection machine 50, the paint starts to flow into the gap generated by the mold opening.
In addition, the coating surface area of the molded product shape | molded with the metal mold | die used for 2nd Embodiment is 600 cm < ² >, and the thickness of a coating film will be about 0.1 mm. The paint used in the second embodiment is Praglas # 8000: white (manufactured by Dainippon Paint Co., Ltd.).

After injecting the paint, the process proceeds to the fourth step, the movable mold 14 is moved in the direction of the fixed mold 12, the mold 10 is closed again and the mold is clamped, and the paint in the gap is made to flow while being spread, Cover the surface of the molded product with paint.
In the second embodiment, the final clamping force in the fourth step is set to 30 MPa as the surface pressure M3 obtained by dividing the final mold clamping force by the projected area S of the resin molded product, in the second step. Although the surface pressures M2 and M3 are the same, the pressure is not increased as much as 30 MPa as it is, but the mold clamping force is increased in two steps. First, the surface pressure is set to 10 MPa, and then the pressure is increased to 30 MPa. It was.
In the second embodiment, unlike the embodiment described above, a relatively high mold clamping force is applied until the end of the second step, so that a thick in-mold coated molded product that is easy to sink. It is effective when molding.
The removed in-mold coated molded product was a molded product having no sink and good appearance as in the previous embodiment.

  In the fourth step, when the mold clamping force is increased, the pressure may be increased in three steps as shown in FIG. 6, and the number of steps may be increased as necessary. It is within the scope of adaptation of the invention.

In the above-described embodiment, the resin is injected by mold clamping force control in the first step, and the mold cavity 15 is opened by the filling pressure of the molten resin when filling the molten resin. The mold clamping device is controlled so that the volume of the mold increases, and when the resin is injected and filled into the mold controlled in the mold clamping force in the first step, the so-called injection compression molding method is generally used. This is an injection filling method of resin as referred to in (1).
However, the mold clamping control method of the first process applicable to the present invention is not limited to this, and for example, a so-called injection in which resin is filled with the mold 10 slightly opened in advance as shown in FIG. Of course, resin injection filling generally called a press molding method may be used.
Here, FIG. 8 shows an example of a control method of the mold clamping device in the case of performing the molding method of the process shown in FIG. Resin injected into the mold by injecting the resin with the mold slightly opened by position control in the first process and immediately proceeding to mold clamping force control in the second process and closing the mold Is shaped by the clamping force. Also, at this time, until the third step is started, a mold clamping force is applied to the resin filled in the mold so that the mold remains in a slightly opened state even after the mold is clamped. The resin is filled into the mold.

When the mold is opened and the resin is injected, there are many cases where the resin does not reach the end of the mold cavity when the mold is opened immediately after the injection.
In such a case, it is necessary to spread the resin in the mold by the clamping force. For this reason, there is a case where it is necessary to set the initial clamping force in the second step to be larger.
In the method of controlling the mold clamping apparatus shown in FIG. 8, the mold clamping force in the second step is finally reduced by decreasing the initial mold clamping force by reducing the pressure in multiple stages, which affects the product. This is a particularly preferable form in that the deformation of the mold due to the clamping force can be reduced.

It is a figure explaining the process of in-mold coating forming according to the embodiment of the present invention. It is a figure explaining the control method of the mold clamping apparatus according to the embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the structure of the whole mold inner coating molding apparatus concerning embodiment of this invention. It is a schematic sectional drawing explaining the structure of the metal mold | die apparatus used for embodiment of this invention. It is a figure explaining the control method of the mold clamping apparatus concerning 2nd Embodiment by this invention. It is a figure explaining the control method of the mold clamping apparatus concerning 3rd Embodiment by this invention. It is a figure explaining the process of in-mold coating formation concerning other embodiment by this invention. It is a figure explaining the control method of the mold clamping apparatus concerning other embodiment by this invention. It is a figure explaining the control method of the mold clamping apparatus by the conventional in-mold coating forming method. It is a figure explaining the control method of the mold clamping apparatus by the conventional in-mold coating forming method. It is a conceptual diagram explaining the behavior of the resin and the paint in the mold according to the in-mold coating molding method according to the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mold apparatus 12 Fixed mold 14 Movable mold 15 Mold cavity 20 Clamping apparatus 22 Clamping cylinder 25 End plate 28 Movable disk 29 Fixed disk 30 Injection apparatus 32 Barrel 38 Hopper 40 Cylinder 50 Paint injection machine 51 Inlet 52 Paint injection Control device 60 Control device 61 Mold clamping control device 63 Injection control device 100 In-mold coating molding device

Claims (6)

In an in-mold coating molding method in which a mold having a mold cavity formed by a male mold and a female mold is used to mold a resin molded product in the mold cavity and coat the surface of the resin molded product. ,
The first step of filling the mold cavity with the molten resin, and after filling the mold cavity with the molten resin, the molten resin is shaped by reducing the volume of the mold cavity while matching the thermal shrinkage of the molten resin. And a second step of molding the resin molded product, and when the resin molded product is solidified to the extent that it can withstand the injection pressure and flow pressure of the coating agent, the mold is slightly opened to A third step of forming a gap for injecting the coating agent between the mold cavity surface and a fourth step of injecting the coating agent into the gap and re-clamping the mold,
In the fourth step, the initial mold clamping force is increased to make the final mold clamping force in the fourth step substantially the same as the final mold clamping force in the second step. .   The in-mold coating forming method according to claim 1, wherein, in the fourth step, the initial mold clamping force is increased in at least two or more stages to obtain a final mold clamping force.   3. The in-mold coating forming method according to claim 1, wherein, in the second step, the initial mold clamping force is reduced to obtain a final mold clamping force.   In the case of injecting and filling resin into a mold whose mold clamping force is controlled in the first process, the final mold clamping force in the second process is lowered from the mold clamping force in the first process. The in-mold coating forming method according to any one of claims 1 to 3, wherein the method is made smaller. In an in-mold coating molding apparatus that uses a mold having a mold cavity formed by a male mold and a female mold to mold a resin molded product in the mold cavity and coat the surface of the resin molded product ,
The first step of filling the mold cavity with the molten resin, and after filling the mold cavity with the molten resin, the mold cavity is shaped by reducing the volume of the mold cavity while matching the thermal shrinkage of the molten resin. The second step of molding the resin molded product, the mold is slightly opened at the stage where the resin molded product is solidified to withstand the injection pressure and flow pressure of the coating agent, and the resin molded product and the mold cavity surface And a third step of forming a gap for injecting the coating agent between and a fourth step of injecting the coating agent into the gap and re-clamping the mold,
In the fourth process, the initial mold clamping force is increased in at least two or more stages to make the final mold clamping force substantially the same as the final mold clamping force in the second process. Coating molding equipment.   An in-mold coating product molded by the in-mold coating molding method according to any one of claims 1 to 4.

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