JPH05169493A - Molding method of sandwich molded piece - Google Patents

Abstract

PURPOSE:To prevent a skin material from leaking into a spool of a mold through a nozzle during the period between the completion of raw material metering and the start of skin material injection. CONSTITUTION:After completion of infection of both materials and dwelling of a core (at the time D), a shut-off Pin 14 on a core channel 120 is closed (S3). The shut-off pin 14 is opened after the completion of the next metering (S4). An injection cylinder is sucked back after the completion of the metering. When the next mold closing signal is inputted (at the time A), the shut-off pin 14 is closed. When a core material is injected (at the time C), the shut-off pin 14 is opened. Thus, as the shut-off pin 14 remains opened during the period between the completion of metering and the receipt of the mold closing signal (S4) to connect a skin channel 110 and the core channel 120, the skin material is prevented from leaking into a spool.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a sandwich molded article composed of a skin material and a core material, and more particularly to a method for opening and closing a shutoff pin in the molding apparatus.

[0002]

2. Description of the Related Art A sandwich molded article is a two-layer molded article of synthetic resin in which the surface of a core material is covered with a skin material. In molding such a sandwich molded article, as shown in FIG. 4, the skin material is injected into the cavity 80 of the molding die 8 and concurrently with this, the core material is injected into the skin material. As shown in FIG. 4, the molding device for molding the sandwich molded product is configured so that the skin flow channel 110, the core flow channel 120, and the softened synthetic resin sent from both flow channels are introduced into the cavity 80. And a common nozzle hole 130 for injecting.

Further, there is a shut-off pin 14 for opening and closing an outlet 125 which is fed into the core flow passage 120 so as to be able to move forward and backward and communicates with the nozzle hole 130 from the core flow passage 120. It should be noted that the skin flow path 110 is the connection path 111.
Is connected to a skin material injection device (see FIG. 2) for measuring and injecting the skin material. Further, the core flow path 120 is connected via a connection path 121 to a core material injection device (see FIG. 2) for measuring and injecting the core material.

The shutoff pin 14 is connected to a hydraulic cylinder. The molding apparatus has a controller that receives signals such as a mold closing signal indicating completion of mold closing of the molding die 8 and a measurement completion signal from the skin material injection device and the core material injection device to control each department. The shutoff pin 14 is operated by a command from the controller. In FIG. 4, reference numeral 13 is a nozzle body.

Next, when performing sandwich molding using the above-mentioned molding apparatus, first, the outlet 125 of the core flow path 120 is closed by the shut-off pin 14. Then, the skin material injection device injects the softened synthetic resin of the skin material into the cavity 80 from the nozzle hole 130 through the connecting path 111 and the skin flow path 110.
Then, slightly after the start of injection of the skin material,
The shutoff pin 14 is retracted to open the outlet 125 of the core channel 120. As a result, the core material is injected from the core material injection device into the nozzle hole 130 through the connecting path 121, the core flow path 120, and the outlet 125. And
This core material is injected into the skin material injected into the cavity 80.

After the completion of injection of the skin material and the core material, the core pressure is maintained for a few hours (several seconds) with the shut-off pin 14 left open. After the core holding pressure is completed, shut off the shutoff pin. As a result, a sandwich molded product is molded in the cavity 80. Then, the molding die 8 is opened and the sandwich molded product is taken out from the cavity 80. Next, the mold 8 is closed for the next molding. After closing the core pressure and closing the shut-off pin 14, the skin material and the core material are weighed in the skin material injection device and the core material injection device, respectively, to prepare for the next injection. ing.

The state of opening and closing of the shut-off pin during the above molding process is as shown in FIG. That is, first, when the core holding pressure in the previous molding is completed as described above, the shut-off pin is
It is in a closed state as shown in S1. Then, after the time point A when the mold closing signal is input from the molding die, the skin material injection device operates at the time point B to operate the nozzle holes 130 as described above.
Through which the skin material is injected into the cavity 80, and at time C, the shutoff pin 14 is opened (S
2), the core material is injected.

After the injection of the skin material and the core material, the shut-off pin 14 is opened for a while as described above to maintain the core pressure. After the core pressure is completed (time D), the shutoff pin 14 is closed (S3). Then, as described above, the sandwich molded product is taken out from the cavity. Further, while the shut-off pin 14 is closed, the skin material and the core material injecting device measure the skin material and the core material, respectively, and a measurement completion signal is transmitted at time E. Then, after the next mold closing signal (time A) is input as described above (S1), the skin material is injected again (time B) as described above, and then the shutoff pin is opened (time C) to make the sandwich. Molding is performed.

[0009]

[Problems to be Solved] However, the conventional molding method has the following problems. That is, in the above-mentioned conventional method, during the injection of the core material and the core holding pressure (S2
(Section), the shutoff pin is opened, but during other periods (sections S1 and S3 in FIG. 3) it is closed.

In the skin material injection device and the core material injection device, after measuring the skin material and the core material, the measurement pressure is applied to the skin flow passage 110 and the core flow passage 120. Therefore, if the pressure load state is left as it is for 5 to 10 minutes due to, for example, a short break time or a device trouble, the skin material is gradually injected from the nozzle hole 130 into the sprue 85 of the mold 8.
Core material leaks out. Then, the skin material and the core material are solidified in the sprue 85.

When such a state occurs, it is necessary to separate the mold and clean the inside of the sprue prior to the next sandwich molding. Therefore, in order to avoid such leakage, a “suck back operation” has conventionally been performed in which after the above-mentioned weighing, the injection cylinder for weighing and injecting the skin material injection device is forcibly retracted slightly.
However, even if such suck back is performed, a check valve (see FIG. 1) is provided between the skin material injection device and the skin flow channel 110.
No. 114) is interposed, the pressure load still remains in the direction of the nozzle hole 130 in front of the check valve.

Therefore, it is still impossible to solve the problem that the skin material leaks into the sprue from the nozzle hole after the completion of the measurement and before the injection. In view of the above conventional problems, the present invention aims to provide a method for molding a sandwich molded article in which the skin material does not leak into the sprue from the nozzle hole before the injection of the skin material after the completion of the above measurement. Is.

[0013]

According to the present invention, there is provided a skin flow passage for feeding a weighed skin material, a core flow passage for feeding a weighed core material, and a cavity of a molding die formed from both of the flow passages. A molding device having a common nozzle hole for injecting the softened synthetic resin into the inside and a shut-off pin for opening and closing the outlet of the core channel is used, and the shut-off pin is closed in the above After the skin material and the core material are weighed, the measurement completion signal is input, and after the mold closing signal is input, the skin material is injected into the cavity, and then the shutoff pin is opened to open the skin material. In the method for forming a sandwich molded article, in which the core material is injected into the inside of the core and the shutoff pin is closed after the core pressure is completed, the shutoff pin includes at least the skin material and the core. It is in the molding method of a sandwich molded product, characterized in that opening when the injection cylinder for injecting a charge performs suck-back.

What is most noticeable in the present invention is that suck back of the injection cylinder is performed from the completion of the measurement to the injection time of the skin material and the core material, and
At least to do the suckback, open the shutoff pin.

The injection cylinder is used to measure and inject the skin material and the core material, respectively, and is provided in the skin material injection device and the core material injection device, respectively. The shutoff pin is opened or closed by an actuator such as a hydraulic cylinder or pneumatic cylinder. These actuators are controlled by the controller. These can be conventional ones. Further, the suck back means that after the respective materials are weighed in the skin material injection device and the core material injection device, the injection cylinder thereof is slightly retracted.

[0016]

In the present invention, as described above, the shut-off pin is opened at least when suck back is performed after the measurement is completed. Therefore, some pressure applied to the skin flow path during measurement of the skin material passes through the core flow path where the shut-off pin is opened,
Escape to the injection cylinder for the core material being sucked back. Therefore, a small amount of the skin material in the skin flow channel will flow into the core flow channel.

Therefore, after the above-mentioned measurement is completed and before the skin material is injected, no pressure is applied to the skin material in the skin channel as in the conventional case. That is, in the skin flow passage, the injection cylinder is sucked back and communicates with the inside of the core flow passage, which is slightly depressurized. Therefore, the skin material does not leak into the sprue of the molding die even if the time until the skin material is injected after the completion of the measurement becomes long due to the above-mentioned breaks, troubles and the like. Therefore, unlike the conventional method, the work of removing the synthetic resin solidified in the sprue is not required.
As described above, according to the present invention, it is possible to provide a method for molding a sandwich molded article in which the skin material does not leak from the nozzle holes into the sprue between the completion of the measurement and the injection of the skin material.

[0018]

EXAMPLE A method for forming a sandwich molded article according to an example of the present invention will be described with reference to FIGS. First, as shown in FIG. 2, the molding device used in this example is a skin material injection device 11 and a core material injection device 12
And a common nozzle hole 130 for injecting the softened synthetic resin into the cavity 8 from both injection devices 11 and 12.
The core material injection device 12 and the shutoff pin 14 that is fed into the core flow passage 120 so as to be able to move forward and backward to open and close the outlet 125 of the core flow passage 120.

The skin material injection device 11 also has an injection cylinder 115 for measuring and injecting the skin material. Further, the core material injection device 12 has an injection cylinder 125 for measuring and injecting the core material. Further, a hydraulic cylinder 15 for advancing and retracting the shutoff pin 14, and a hydraulic circuit 16 connected to the hydraulic cylinder 15
Have and. The hydraulic circuit 16 is connected to the hydraulic device 161. The hydraulic device 161 is connected to a controller 162 for controlling the entire molding device.

The nozzle hole 130 is formed by the nozzle body 13
It is provided at the tip of the. Then, in the nozzle body 13, the skin flow path 110 is communicated with the nozzle hole 130.
A core channel 120 is provided. The skin flow channel 110
Is a flow path for communicating between the nozzle hole 130 and the skin material injection device 11. In addition, the skin flow channel 110
A connection path 111 is provided between the and the skin material injection device 11 via a check valve 114. Also, the core channel 1
A connection path 121 is interposed between the core material injection device 20 and the core material injection device 12. Both flow paths 110 and 120 are nozzle holes 1
They join at 30. The tip of the shutoff pin 14 is arranged to face the outlet 125 of the core flow path 120.

The hydraulic cylinder 15 comprises a cylinder tube 151 and a piston rod 152, and the tip of the piston rod 152 is connected to the shutoff pin 14. Inside the cylinder tube 151, a pressing chamber and a returning chamber are formed. The press chamber and the return chamber are connected to the hydraulic device 161 via the hydraulic circuit 16. Others are the same as in the conventional example.

Next, a method for carrying out sandwich molding using the apparatus will be described. That is, in this example, as shown in FIG. 1, when the shut-off pin is in the closed state (S1), the injection cylinder of the skin material is activated at time B after time A when the mold closing signal is input and the skin material is removed. Cavity 8
It is injected into 0. Then, at time C, the shutoff pin 14 is opened, the core material is injected into the skin material,
The pressure is maintained (S2). Then, after the core pressure holding is completed (time D), the shutoff pin 14 is closed. Up to this point, the process is similar to that of the conventional example.

Next, when the shut-off pin 14 is in the closed state after the core pressure holding is completed (S3), when a signal indicating that the measurement in the skin material injection device and the core material injection device is completed is input at the time E. The shutoff pin 14 is opened (S4). Then, in this state, it waits for the mold closing signal.
Next, at the next time point A, when the mold closing signal for the next injection is input, the shutoff pin 14 is closed (S
1). Then, again at the next time points B and C, the skin material and the core material are injected in the same manner as above.

In addition, the injection cylinders 115 and 125 for injecting the skin material and the core material from the above-mentioned measurement completion signal (time E) to the injection of the skin material and core material (time B and C). Suck back. The shutoff pin 14 is operated by feeding the oil device 161 into the hydraulic cylinder 15. The hydraulic device 161 is controlled by the controller 162. The controller 162 receives the mold closing signal, the core pressure holding completion signal, the metering completion signal, etc., controls the hydraulic device as described above, and injects the skin material and the core material.
It controls the weighing of both materials, suck back of the injection cylinders 115 and 125, and the like. Others are the same as in the conventional example.

In the present example, as described above, the shutoff pin is opened when the measurement completion signal is input after the core pressure holding is completed. After that, the injection cylinder 12 on the core material side
Suck back 5. Therefore, when measuring the skin material, the slight pressure applied in the skin flow channel 110 is
The shut-off pin 14 enters the open core channel.

Therefore, the skin material in the skin flow channel 110 flows into the core flow channel 120, though in a small amount. That is, after the measurement is completed, the injection cylinder 125 for the core material is sucked back inside the skin flow channel 110 and is in communication with the inside of the core flow channel slightly depressurized. Therefore, even if the time until the injection of the skin material is long after the measurement is completed due to the above troubles, the sprue 8 of the molding die 8
The skin material does not leak into the inside. Therefore, unlike the conventional method, the work of removing the synthetic resin solidified in the sprue is not required.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an open / closed state of a shutoff pin in Embodiment 1.

FIG. 2 is a cross-sectional view of a main part of a molding device for sandwich molding in an example.

FIG. 3 is an explanatory diagram of an open / closed state of a shutoff pin in a conventional example.

FIG. 4 is a sectional view of an essential part of a molding device for sandwich molding in a conventional example.

[Explanation of symbols]

 11. ． ． Skin material injection device, 110. ． ． Skin channel, 114. ． ． Check valve, 12. ． ． Core material injection device, 120. ． ． Core channel, 130. ． ． Nozzle hole, 14. ． ． Shut-off pin, 8. ． ． Mold, 80. ． ． Cavity,

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area // B29L 9:00 4F

Claims (1)

[Claims] 1. A skin channel for feeding a weighed skin material, a core channel for feeding a weighed core material, and a softened state from both channels into a cavity of a mold. A molding apparatus having a common nozzle hole for injecting a synthetic resin and a shutoff pin for opening and closing the outlet of the core channel is used, and the skin material and the core material are closed with the shutoff pin closed. After the measurement completion signal is input and the mold closing signal is input, the skin material is injected into the cavity, and then the shutoff pin is opened to insert the core material into the skin material. In the molding method for sandwich molded products, in which the shut-off pin is closed after the core pressure is completed,
The method for forming a sandwich molded article, wherein the shut-off pin is opened when each injection cylinder for injecting at least the skin material and the core material performs suck back.