JPH03104609A - Plastic mold assembly - Google Patents

Abstract

PURPOSE:To realize the rapid cooling and solidification of the molten resin in a cavity at cooling process by cooling liquid flowing in a cooling liquid passage by a method wherein a heaters are energized in order to heat a runner and the cavity until the proper time in filling process arrives and deenergized at said proper time in filling process. CONSTITUTION:When filling process starts after mold closing process, high temperature molten resin is injected from a nozzle 6, passed through a runner 7 and fed into a cavity 5. In this case, since the runner 7, a recessed part 2a and a projected part 4a, of both of which the cavity 5 is composed, are heated up to a proper high temperature with heaters 10 and 11, the fluidity of the molten resin is not apt to be impaired. In addition, when cooling process arrives through the following dwelling process after the deenergizing of the heaters 10 and 11 and the finish of filling process, cooling liquid is circulated through cooling liquid passages 8 and 9, resulting in rapidly cooling and solidifying the molten resin in the cavity 5.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a plastic molding device in which a mold is provided with a heater.

(Prior Art) In conventional plastic molding equipment, in order to maintain good fluidity of the molten resin so that the molten resin completely fills the cavity of the mold, and to ensure that the molten resin is filled into the cavity. In order to quickly cool and solidify the molten resin, water or oil is passed through the mold to maintain the mold at an appropriate temperature.

(Problem to be solved by the invention) However, in order to maintain the fluidity of the molten resin, it is necessary to keep the temperature of the mold as high as possible, and in order to solidify the molten resin quickly, the temperature of the mold must be kept as high as possible. It needs to be as low as possible. In this way, maintaining the fluidity of the molten resin and quickly solidifying the molten resin are contradictory requirements for the temperature of the mold, so conventionally, the temperature at which the mold is held using water or oil has been was set as a compromise between both requirements. However, this means that the mold temperature is low from the viewpoint of the fluidity of the molten resin, and that the mold temperature is high [1] from the viewpoint of rapid solidification. Therefore, a decrease in the fluidity of the molten resin is unavoidable,
If the cavity gap is narrow (the product has a thin wall thickness), it will be difficult to completely pour the molten resin into the cavity, and the time required to cool and solidify the resin will likely be longer. there were.

Therefore, an object of the present invention is to raise the mold temperature to maintain good fluidity of the molten resin when filling the cavity with molten resin, and to quickly cool the molten resin when cooling the molten resin. An object of the present invention is to provide a plastic molding device that can lower the mold temperature as much as possible.

[Structure of the Invention] (Means for Solving the Problems) The plastic molding device of the present invention includes a mold provided with a coolant passage and a heater for heating a cavity in which a product is formed. The heater is energized at an appropriate time from the start of the mold opening process through the product removal process to the end of the mold opening process, and then molten resin is supplied to the cavity from the nozzle of the certain molding machine. The heater is cut off at an appropriate time during the filling process.

(Function) The heater is energized to heat the runner and cavity until an appropriate time in the filling process. Therefore, the molten resin injected from the nozzle of a certain molding machine is supplied into the cavity through the runner while maintaining good fluidity, and is filled into the cavity.

Since the heater is powered off at an appropriate time during the filling process, in the cooling process for solidifying the molten resin, the molten resin in the cavity is rapidly cooled and solidified by the coolant flowing through the coolant passage.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

First, as shown in Fig. 1, the mold consists of a fixed mold 2 attached to a fixed plate 1 of the molding machine and a movable mold 4 attached to a movable plate 3 of the molding machine. ing. A cavity 5 for a certain shape is formed on the abutting surfaces of these two molds 2 and 4 by a recess 2a on the fixed mold 2 side and a convex portion 4a on the movable mold 4 side. A runner 7 is formed in the stationary mold 2 to guide the molten resin injected from the nozzle 6 of the molding machine into the cavity 5.

Coolant passages 8 and 9 are formed in the stationary mold 2 and the movable mold 4, and are located closer to the cavity 5 than the coolant passages 8 and 9. Heaters 10 and 11 that heat the cavity 5 and the runner 7
is provided.

The electrical structure for controlling the energization and disconnection of the heaters 10 and 1 is shown in FIG. In FIG. 2, the control circuit 12 is mainly composed of, for example, a microcomputer. When the time-up signal S,1 is input from the first timer 13, this control circuit 12 controls the drive circuit 14.
The heaters 10 and 11 are energized via the second timer 1.
The heaters 10 and 11 are configured to be powered off via the drive circuit 14 when the time-up signal SL12 is manually inputted from the drive circuit 14. When the set signals S1 and S2 are inputted from the molding machine, both the first and second timers 13 and ]5 start timing operation, and when they count the set time, they send time-up signals SlJl and SL12. Output.

Here, set signals S and S are sent to both timers 13 and 15.
2 manually and when both timers 13 and 15 receive the time-up signal Sl. The timing of outputting l1 and SU2 will be explained. That is, one molding cycle of the molding machine includes, as shown in FIG. 3(a), a mold opening step in which the movable mold 4 is butted against the fixed mold 2, and a mold opening step in which molten resin is injected from the nozzle 6. In the filling process, the molten resin filled in the cavity 5 is kept under pressure from the nozzle 6 side, and the cooling liquid passages 8 and 9
A cooling process in which the molten resin in the cavity 5 is cooled and solidified through cooling liquid, a mold opening process in which the movable mold 4 is separated from the fixed mold 2, and a product removal process in which the molded product is taken out from the r+J movable mold. Become. Then, the molding machine starts the first timer 1 at the start of the mold opening process in one molding cycle.
3, and outputs a set signal S2 to the second timer 15 at the end of the mold opening step in the next molding cycle. As shown in FIG. 3(b), the first timer 13 outputs an ε time-up signal SL, at which a preset interval T1 elapses from the manual input point of the set signal S.
I1 is output, and its setting [ll interval T1 is set to be the time from the start of the mold opening process to, for example, the middle of the unloading process [2]. The second timer 15 outputs a time-up signal SU2 when a preset time T2 has elapsed from the input point of the set signal S2, but the set time T2 is from the end of the mold opening process to, for example, near the end of the filling process. The time is set to be . Therefore,
The heaters 10 and 11 are energized during the unloading process, and are cut off near the end of the filling process of the next molding cycle.

Next, the operation of the above configuration will be explained.

When the mold opening process of one molding cycle is started, a set signal S+ is output from the molding machine to the first timer 13. Then, the first timer 13 starts a timing operation, and outputs a time-up signal Sold during the ejecting process of removing the product from the opened movable mold 4. This time-up signal SUI causes the control circuit 12 to energize the heaters 10 and 11, thereby heating the launch 7 of the stationary mold 2 and the concave portion 2a forming the cavity 5, and heating the movable mold 4. The convex portion 48 portion is heated. Then, one molding cycle ends with the completion of the take-out process, and then the next molding cycle starts. This molding cycle is executed from a mold opening step in which the movable mold 4 is butted against the fixed mold 2, and when this mold opening step is completed, the molding machine
A set signal S2 is output to the timer 15. Then,
The second timer 15 starts a timing operation and outputs a time-up signal SL+2 near the end of the filling process following the mold opening process. The control circuit 12 turns off the power to the heaters 10 and 11 in response to the time-up signal SIJ2.

When the filling process is started after the mold opening process, high-temperature molten resin is injected from the nozzle 6, and the molten resin is supplied to the cavity 5 through the runner 7. In this case, the recesses 2a and f forming the runner 7 and the cavity 5
! Since the portion 11 4a is heated by the heaters 10 and 11 to a suitable high temperature state, there is no fear that the fluidity of the molten resin will be impaired. And heaters 10 and 1
After the power is cut off in step 1, the filling process is completed, and when the next pressure holding process begins and the cooling process begins, the cooling liquid is passed through the cooling liquid passages 8 and 9, thereby rapidly cooling the molten resin in the cavity 5. solidified. When this cooling process is completed, a mold opening process is started, and a set signal S, is input from the molding machine to the first timer 13 at the time of opening this mold opening process. Then, in the same way as described above, the heaters 10 and 11 are energized during the second step of taking out the next product, and the cycle similar to that described above is repeated.

In this way, according to this embodiment, the heater 10 is used in the filling process.
Since the cavity 5 and the runner 7 are heated by the runners 1 and 11, there is no risk that the fluidity of the molten resin to be injected from the nozzle 6 and filled into the cavity 5 will be impaired. Therefore, the molten resin can flow smoothly even into a cavity with a small gap, so that it is possible to reduce the thickness of the product. Moreover, since the heaters 10 and 11 are cut off during the cooling process, by passing the coolant through the coolant passages 8 and 9, the molten resin can be quickly cooled and solidified, reducing the time required for one molding cycle. I can do it.

In the above embodiment, the timing for energizing the heaters 1o and 11 was set in the middle of the product removal process;
Taking into account the time delay until the molds 2 and 4 reach a temperature that does not impair the fluidity of the molten resin during energization in step 11, the period from the start of the mold opening process to the end of the mold opening process is It may be determined at an appropriate time during the dry cycle (generally referred to as a dry cycle). Also, when the heaters 1o and 11 are cut off, the molds 2 and 4 are
It may be determined at an appropriate time during the filling process, taking into account the degree of temperature decrease.

4 and 5 show other embodiments of the invention.

First, in Fig. 4, the same parts as in Fig. 1 are given the same reference numerals to explain the different parts.The cavity 16 of this embodiment has a narrow part (thin part of the molded product). First to third heaters 17 to 19 are provided in the stationary mold 2 to heat this small gap portion 16a.

These heaters 17 to 19 are connected to a control circuit 12 shown in FIG.
The timing is as follows. That is, as shown in FIG. 5, when the molding machine outputs the set signal S to the first timer 13 at the time when the mold opening starts, the first timer 13 outputs tl 12 from the time when the set signal S1 is input. %t. As time passes, signals SUII and Sυ are sent to the control circuit 12 each time.
, 2, output SLI13. This signal SU+1, SL
The output times of I+2 and SLI+3 are set to be in the middle of the mold opening process, near the end of the mold opening process, and in the middle of the product removal process, respectively. Then, the control circuit 12 energizes the first heater 17 when the signal SUI1 is inputted, the second heater 18 when the signal SLI12 is input, and the third heater 19 when the signal SUL3 is inputted. do. Moreover, when the set signal S2 is output from the molding machine to the second timer 15 at the start of the filling process, the second timer 15 outputs the set signal S2? From the time of manual labor t4, ,,
Each time t6 time elapses, a signal S [121
3 Outputs 022%SL+21. This signal S 02
1 The output points of the S IJ 22 and S U 23 are set to be in the middle of the filling process, near the end, and at the end, respectively. Then, the control circuit 12 controls S L+
21, the third heater 9 is cut off and the signal SL is turned off.
The second heater 8 is cut off at the given point of +2■ manual power, and the first heater 7 is cut off when the signal S IJ23 is input.

Even with this configuration, it is possible to obtain the same effects as in the above embodiment.

Note that in the above embodiment and other embodiments, the coolant passage 8
, 9 that the cooling liquid is allowed to flow only during the cooling process, but the cooling liquid may be made to flow all the time throughout the entire process.

[Effects of the Invention] As is clear from the above description, according to the present invention, until an appropriate time in the process of filling the cavity with molten resin,
Since the heater is energized to heat the cavity, the molten resin injected from the nozzle of the molding machine is filled into the cavity while maintaining good fluidity. Therefore,
Even in cavities with small gaps, the molten resin flows well and completely fills the holes, making it possible to reduce the thickness of the product.

In addition, when cooling the molten resin filled in the cavity, the heater is turned off and cooling can be done quickly by the coolant passed through the coolant passage, reducing the time required for the molten resin to solidify. This makes it possible to shorten the time required for one molding cycle.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention,
Fig. 1 is a vertical side view of the mold, Fig. 2 is a block diagram for controlling the heater, Fig. 3 is a time chart showing a certain cycle of the molding machine, and Figs. 4 and 5 are the invention of the present invention. FIG. 1 is a diagram corresponding to FIG. 1 and FIG. 3 showing other embodiments of the present invention. In the figure, 2 is a stationary mold, 4 is a movable mold, 5 is a cavity, 6 is a nozzle, 7 is a runner, 8 and 9 are coolant passages, 1
0.11 is the heater, 12 is the control circuit, 13.15 is the first
．． The second timers 17 to 1 are the first to third heaters.

Claims (1)

[Claims] 1. A mold with a coolant passage is provided with a heater that heats the cavity in which the product is molded, and the mold is heated from the start of the mold opening process through the product removal process to the end of the mold opening process. The heater is energized at an appropriate time, and then,
A plastic molding device characterized in that the heater is cut off at an appropriate time during a filling process in which molten resin is supplied from a nozzle of the molding machine to the cavity.