JPH08267527A - Injection mold - Google Patents

Abstract

PURPOSE: To provide an injection mold capable of obtaining a molded product good in the transfer properties of a mold using a mold simple in structure and a usual molding machine. CONSTITUTION: A injection mold forming a cavity 6 by fixed molds 1, 2, 4 and movable molds 3, 5 is equipped with a heating and cooling means 9 provided so as to surround the cavity 6, a means 8 controlling the temp. of the resin passages 7, 10 between the cavity 6 and the nozzle of a molding machine and a mechanism 11 cutting off the resin passage 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die for molding a thick molded product with high accuracy.

[0002]

2. Description of the Related Art When a thick molded product is injection-molded, a molding defect such as a sink is likely to occur. As a means for solving this, the technique disclosed in Japanese Examined Patent Publication No. 61-59220 has been disclosed. As shown in FIG. 9, the mold used in this molding method was filled even when there was a slight opening margin δ between the fixed-side mold plate 101 and the movable-side mold plate 102 that form the mold. In order to prevent liquid leakage of the synthetic resin, a cavity block 103 which is slidably fitted in the cavity recess 101a of the stationary mold plate 101 is attached to the movable mold 102. In the molding method, the cavity 106 formed by the cavity block 103 and the cavity recess 101a is slightly opened to expand the cavity volume, and the cavity wall is made to have a temperature not lower than the product extraction temperature and not higher than the solidification temperature of the synthetic resin. After the temperature of the synthetic resin filled in the cavity 106 becomes lower than the solidification temperature of the synthetic resin at the center of the thick portion of the product, the gate of the mold is mechanically or cooled and sealed. , The synthetic resin surface of the cavity 106 is rapidly heated until the surface layer of the synthetic resin can flow, and the synthetic resin is reheated, and the slightly open cavity 106 is closed to remove the synthetic resin of the surface layer. Flow along the cavity wall and then rapidly cool the entire cavity wall with the cavity 106 closed to increase mold temperature. Goods taken out by lowering the temperature below those that formed in a predetermined product shape.

[0003]

However, in the above-mentioned prior art, since a mold having a mechanism for moving the cavity block of the mold forward and backward is used, the mold processing becomes complicated and the molding is performed during compression during molding. Since the machine platen is moved forward, there is a problem that it is difficult to carry out with a normal molding machine such as a toggle type mold clamping mechanism.

The present invention has been made in view of the above conventional problems, and an object of the invention according to claim 1, 2 or 3 is to use a mold having a simple structure and an ordinary molding machine. An object of the present invention is to provide an injection-molding die capable of obtaining a molded product having a good mold transfer property.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1, 2 or 3 encloses a cavity in an injection molding die in which the cavity is formed by a fixed die and a movable die. It is characterized in that it is provided with heating / cooling means provided as above, means for controlling the temperature of the resin flow path between the cavity and the molding machine nozzle, and a mechanism for blocking the resin flow path.

[0006]

In the operation of the invention according to claim 1, 2 or 3,
After injecting the resin into the cavity, the resin flow path is blocked and the interior of the molded product is cooled until it solidifies. Next, the surface of the molded product is reheated and re-melted by the heating / cooling means surrounding the cavity. When the resin on the surface of the molded product is allowed to flow, the resin flow path is unblocked, and the shortage of resin is poured into the molded product from the injection unit of the molding machine.
The resin flow path is shut off again. Thereafter, the temperature of the heating / cooling means is gradually lowered to gradually cool the molded article, and the molded article is taken out in a state where the temperature of the heating / cooling means is lowered to the temperature for taking out the molded article. There is no sink mark in the molded product by replenishing the shortage of resin.
In the operation of the invention according to claim 2, in addition to the above operation, even if the cavity side is blocked by changing the thickness of the resin channel by dividing it into three, the resin channel on the sprue side communicates with the blocking portion. Therefore, the resin of the blocking portion is solidified by being integrated with the resin of the sprue side. In the operation of the invention according to claim 3, since the hot runner is used for the means for controlling the temperature of the resin passage between the cavity and the molding machine nozzle and the mechanism for shutting off the resin passage, the sprue and the runner are prevented. It becomes unnecessary.

[0007]

Embodiment 1 FIGS. 1 to 4 show Embodiment 1, FIG. 1 is a front view in which a part of an injection molding die is mounted, FIG. 2 is a perspective view of a mechanism for blocking a resin flow path, and FIG. FIG. 4 is an explanatory view of re-melting the molded product in the injection molding die, and FIG. 4 is an explanatory view of the relationship between the molding process and the temperature of the heater.

In FIG. 1, 1 is a fixed side mounting plate, 2 is a fixed side template, and 3 is a movable side template. A cavity 6 is formed by the fixed-side insert 4 embedded in the fixed-side mold plate 2 and the movable-side insert 5 embedded in the movable-side mold plate 3.
A heater 8 is arranged around the sprue 7 communicating with the fixed-side mounting plate 1, the movable-side mold plate 2, and the movable-side mold plate 3, so that the resin flowing through the sprue can be heated and cooled. Further, heaters 9 are respectively provided in the vicinity of the surfaces of the fixed-side insert 4 and the movable-side insert 5 that form the cavity 6, so that the resin in the cavity can be heated and cooled. A runner 10 is provided between the sprue 7 and the cavity 6 so as to have a constant width and depth across the movable-side template 3, the shut plate 11, and the movable-side insert 5.

As shown in FIG. 2, a shut plate 11 in which a part of the runner 10 is recessed is connected to a hydraulic cylinder 12, and the hydraulic cylinder 12 is fixed to a movable side mold plate 3 by a fixed plate 30. There is. The shut plate 11 is driven by the reciprocating rectilinear motion of the hydraulic cylinder 12, and the runner 10 is opened and closed. The pipe 13 of the hydraulic cylinder 12 is connected to the core tiger 14 of the molding machine,
Is electrically connected to a control panel 15 having a built-in timer, and its operation is controlled. Reference numeral 16 in FIG. 1 denotes a molding machine nozzle, which supplies the molten resin to the cavity 6 through the sprue 7 and the runner 10.

Next, the operation of this embodiment will be described. FIG.
Indicates the state immediately after mold clamping during molding. At this time,
The temperature of the heaters 8 and 9 is the temperature at which the molded product is taken out. In this state, the molten resin is injected from the molding machine nozzle 16 into the cavity 6. When the resin is filled,
The shut plate 11 slides and shuts off the runner 10. In this state, while cooling the resin in the cavity 6, the heater 8 is heated to maintain the resin in the runner 10 in front of the sprue 7 and the shut plate 11 in a molten state. The operation of the shut plate 11 is controlled by the control panel 1
The hydraulic cylinder 12 is driven by the signal from the timer 5 in FIG.

In FIG. 3, the molded product 17 in which the resin is solidified in the cavity 6 is cooled to the inside, and then the heater 9 is used.
Is rapidly heated to re-melt its surface, and a fusion zone 18 is formed. When the remelting progresses to some extent and the resin in the melting portion 18 becomes fluid, the shut plate 11
Is slid, and when the runner 10 communicates with the resin, the resin is injected again from the molding machine nozzle 16 by the holding pressure of the injection unit of the molding machine (not shown). After that, slide the shut plate 11 again to run the runner 1.
0 is cut off, and secondary cooling is performed in this state.

In the secondary cooling, the heater 8 is rapidly cooled to the take-out temperature and the sprue 7 is solidified. On the other hand, the heater 9 slowly lowers the temperature and gradually cools the molded product 17. When the heater 9 is cooled to the take-out temperature and the molded product 17 is completely solidified, the molded product 17 is taken out.
This completes a series of operations in the molding process. FIG. 4 shows the relationship between the flow of the molding process and the temperatures of the heaters 8 and 9.

According to this embodiment, by providing the mold with two heaters and a shut plate, the temperature of the mold is controlled and the runner is opened / closed to solidify the molded product, remelt it, and replenish the resin. It is possible to obtain a molded product having good transferability of.

In this embodiment, the signal from the timer causes
Although the shut plate is opened and closed, instead of this, a temperature sensor may be provided in the mold and the shut plate may be opened and closed by a signal from the temperature sensor.

[0015]

[Embodiment 2] FIGS. 5 to 7 show Embodiment 2, FIG. 5 is a perspective view showing a resin flow path and a blocking mechanism, and FIG. 6 is a plan view showing a resin flow path near the blocking mechanism in a communicating state. 7 is a plan view showing a resin flow path in the vicinity of a blocking mechanism showing a blocking state. In this embodiment, only a part of the resin flow path and the blocking mechanism is different from that of the first embodiment, and therefore, the same members are designated by the same reference numerals, and the drawings and the description thereof are omitted.

In FIG. 5, the flow channel width of the runner 10b provided in the movable side insert 3a is larger than the flow channel width of the runner 10a provided in the movable side insert 5, and the runner 10b provided in the movable plate insert 3a is provided on the shut plate 11. The runner 10c is formed in a tapered shape so as to connect the flow passage width of the runner 10a and the flow passage width of the runner 10b. Other configurations are the same as those in the first embodiment.

The operation of this embodiment will be described. In FIG. 6, the shut plate 11 moves forward, and the runners 10a, 10
The state where b and 10c are in communication is shown. In this state,
The resin passes through the runners 10b and 10a from the runner 10b and is filled in the couchy 6. When the filling is completed, the shut plate 11 retracts, and the runners 10a and 10c are completely shut off as shown in FIG.
c and the runner 10b are connected. After that, the resin in the cavity 6 is solidified, and the melted portion 18 is formed on the surface of the molded article 17 by heat (see FIG. 3). When the resin is supplied again, the shut plate 11 moves forward and Returning to the state, the runners 10a, 10b, 10c communicate with each other. When the replenishment of the resin is completed, the shut plate 11 retracts, and the state shown in FIG. 7 is restored. Cooling proceeds in this state, and when the molded product 17 is taken out, the shut plate 11
The resin of the upper runner 10c is discharged integrally with the resin of the runner 10b and the sprue 7.

According to this embodiment, in addition to the effects of the first embodiment, the resin on the shut plate is discharged integrally with the runner and sprue resin, so that the resin generated in the first embodiment can be removed. Therefore, the man-hours required for the molding can be reduced, the efficiency of the molding work can be improved, and the unmanned molding work can be performed.

In the present embodiment, the runner passage width is made different so that the resin on the shut plate is integrated with the runner and sprue resin and discharged, but there is a difference in the runner passage depth. The same effect can be obtained by providing the shut-out plate in the depth direction of the flow path.

[0020]

[Embodiment 3] FIG. 8 shows Embodiment 3 and is a front view in which a part of an injection molding die is mounted. In FIG. 8, 1 is a fixed side attachment plate, 2 is a fixed side template, and 3 is a movable side template. A cavity 6 is formed by the fixed-side insert 4 embedded in the fixed-side mold plate 2 and the movable-side insert 5 embedded in the movable-side mold plate 3. Heaters 9 are provided in the vicinity of the surfaces of the fixed-side insert 4 and the movable-side insert 5 forming the cavity 6, respectively, so that the resin in the cavity can be heated and cooled. A hot runner 20 is embedded through the fixed-side mounting plate 1, the fixed-side template 2 and the fixed-side insert 4. The resin injected from the molding machine nozzle 16 always stays in the hot runner 20 in a molten state. Further, the hot runner 20 employs a valve gate type in which opening / closing control of the gate 21 is freely performed. The control panel 22 connected to the hot runner 20 controls opening / closing of the gate 21 of the hot runner 20.

The operation of this embodiment will be described. FIG. 8 shows a state immediately after mold clamping during molding. In this state, the molten resin is injected from the molding machine nozzle 16 into the cavity 6. When the cavity 6 is filled with resin, the hot runner 2
The gate 21 of 0 is closed. In this state, the resin in the cavity 6 is solidified to form the molded product 17, and the molded product 1 is further formed.
Cooling is performed until the inside of 7 solidifies.

When the cooling has proceeded to the inside of the molded product 17, the heater 9 is rapidly heated to remelt the surface of the molded product 17 and form the molten portion 18. When the remelting progresses to some extent and the resin in the melting portion 18 is in a fluidized state, the gate 21 of the hot runner 20 is opened and the resin is replenished by the holding pressure of an injection unit of a molding machine (not shown). In this state, the gate 21 of the hot runner 20 is closed again,
Secondary cooling is performed. At this time, the heater 9 slowly lowers the temperature and gradually cools the molded product 17. When the heater 9 reaches the take-out temperature and the molded product 17 is completely solidified, the molded product 17 is taken out. This completes a series of operations in the molding process.

According to the present embodiment, by operating the heater and the hot runner, the molded product is solidified, re-melted and the resin is replenished to obtain a molded product having a good mold transfer property. Further, by using the hot runner, the sprue and runner are unnecessary, and the amount of resin used can be reduced. Furthermore, since a commercially available hot runner can be buried, a sprue heater and a shut plate are not required, so that the structure of the mold can be simplified and manufacturing can be facilitated.

[0024]

According to the first, second or third aspect of the present invention, it is possible to obtain a molded product having a good mold transfer property by using a mold having a simple structure and a general molding machine. . Claim 2
According to the invention of claim 1, in addition to the above effects, the scrap is automatically removed. According to the invention of claim 3,
In addition to the above effects, it is possible to reduce the amount of resin used and facilitate the manufacture of a mold.

[Brief description of drawings]

FIG. 1 is a front view in which a part of an injection molding die of Example 1 is mounted.

FIG. 2 is a perspective view of a mechanism that shuts off a resin flow path according to the first embodiment.

FIG. 3 is an explanatory diagram in which a molded product in the injection mold of Example 1 is remelted.

FIG. 4 is an explanatory diagram of a relationship between a molding process and a heater temperature according to the first embodiment.

FIG. 5 is a perspective view showing a resin flow path and a blocking mechanism according to a second embodiment.

FIG. 6 is a plan view showing a resin flow path in the vicinity of a blocking mechanism in a communication state according to a second embodiment.

FIG. 7 is a plan view showing a resin flow path in the vicinity of a shutoff mechanism showing a shutoff state according to a second embodiment.

FIG. 8 is a front view in which a part of an injection molding die of Example 3 is mounted.

FIG. 9 is a vertical cross-sectional view of a mold used in a conventional molding method.

[Explanation of symbols]

 1 Fixed Side Mounting Plate 2 Fixed Side Mold Plate 3 Movable Side Mold Plate 4 Fixed Side Nest 5 Movable Side Nest 6 Cavity 7 Sprue 8 Heater 9 Heater 10 Runner 11 Shut Plate 16 Molding Machine Nozzle

Claims (3)

[Claims] 1. An injection molding die for forming a cavity by a fixed die and a movable die, wherein temperature control is performed on a heating / cooling means surrounding the cavity and a resin flow path between the cavity and a molding machine nozzle. And a mechanism for cutting off the resin flow path. 2. A resin flow path between the cavity and the molding machine nozzle is divided into a cavity side and a sprue side with a blocking section sandwiched therebetween, and the resin flow path is thicker on the sprue side than on the cavity side and at the blocking section. 2. The injection mold according to claim 1, wherein the resin flow passage is formed by smoothly connecting the resin flow passages on the sprue side and the cavity side. 3. The injection according to claim 1, wherein a means for controlling the temperature of the resin passage between the cavity and the molding machine nozzle and a mechanism for blocking the resin passage use a hot runner. Molding die.