JP2004074619A - Mold temperature control device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold temperature control device capable of preventing the overcooling of the heating region of a mold provided with a mold heating means, and a mold temperature control method. <P>SOLUTION: The mold K is constituted of a fixed mold 12, a movable mold 13 and an insert piece 25. A cartridge heater 20 for heating the heating region 12a is embedded in the fixed mold 12 and a cooling mechanism 32 comprising a cooling pipe 30 and cooling water 31 is embedded in the mold K. The control device 35 controls electric power supplied to the cartridge heater 20 when the molten resin injected in the mold K is cooled so that the temperature of the heating region 12a of the fixed mold 12 is higher than the cooling temperature of cooling water 31 and becomes a solidification temperature lower than the temperature of the molten resin injected in the mold K. Therefore, overcooling of the heating region 12a in the mold K in which the cartridge heater 20 is embedded can be prevented. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mold temperature control device and a mold temperature control method for performing resin molding.
[0002]
[Prior art]
Conventionally, as a method of heating a mold by a mold temperature control device for molding a resin, a general-purpose cartridge heater (a rod-shaped resistance heater) is incorporated in the mold, and the cartridge heater is ON / OFF controlled. In some cases, the mold temperature is controlled.
[0003]
That is, when performing the resin molding process, first, the cartridge heater is controlled to be ON to heat a portion of the mold corresponding to a weld line or a portion of the molded product where hesitation is likely to occur. Then, after heating the above-mentioned part of the mold, the molten resin is injected and filled into the mold, so that the mold transferability and fluidity inside the mold corresponding to the weld line and the portion where the hesitation easily occurs in the molded product. Improve.
[0004]
When cooling the molten resin injected and filled in the mold, the cartridge heater is controlled to be OFF, and the cooling water is returned at a constant temperature by a temperature controller in the cooling pipe embedded in the mold, so that the mold is cooled. At the same time, the molten resin is cooled, and then the molded product is taken out of the mold. As a result, a molded product with good appearance quality with less weld lines and hesitation is formed.
[0005]
[Problems to be solved by the invention]
However, when cooling the molten resin injected and filled into the mold, the mold is cooled by the cooling water while the cartridge heater is controlled to be OFF, so that the temperature of the mold will drop to the temperature of the cooling water. As a result, the mold is cooled more than desired.
[0006]
Therefore, when the mold is heated by the cartridge heater for the next cycle step after removing the molded article from the mold, it takes a long time to heat the mold, and as a result, the molding cycle becomes longer. there were.
[0007]
The present invention has been made in view of the above circumstances, and has as its object to provide a mold temperature control device and a mold capable of preventing overheating of a heated portion in a mold provided with mold heating means. It is to provide a temperature control method.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 includes a mold heating unit that heats a heating portion of a mold by supplying electric power, a cooling unit that cools the mold, and a mold that cools the mold. In a mold temperature control device provided with a control means for controlling an amount of electric power supplied to a mold heating means, the control means, when cooling the molten resin injected and filled in the mold, the temperature of the heated portion The gist is to control the amount of electric power so that the first temperature is higher than the cooling temperature of the cooling means and lower than the temperature of the molten resin to be injected and filled into the mold.
[0009]
According to a second aspect of the present invention, in the mold temperature control apparatus according to the first aspect, the control unit is configured such that when the molten resin is injected and filled into the mold, the temperature of the heating portion is set to the temperature. The gist of the present invention is to control the amount of electric power so that the second temperature is higher than the first temperature and lower than the temperature of the molten resin to be injected and filled into the mold.
[0010]
The invention according to claim 3 is a mold temperature control method comprising: a mold heating unit that heats a heating portion of the mold by supplying power; and a cooling unit that cools the mold. When cooling the molten resin injected and filled in the mold, the mold is set to a first temperature higher than the cooling temperature of the cooling means and lower than the temperature of the molten resin injected and filled in the mold. The gist is to control the amount of electric power supplied to the heating means.
[0011]
According to a fourth aspect of the present invention, in the mold temperature control method according to the third aspect, when the molten resin is injected and filled in the mold, the temperature is higher than the first temperature and injected into the mold. The gist of the present invention is to control the amount of electric power supplied to the mold heating means so that the second temperature becomes lower than the temperature of the molten resin to be filled.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
[0013]
As shown in FIG. 1, the mold device 11 includes a fixed mold 12 and a movable mold 13.
Cavity forming surfaces 14 and 15 are formed on surfaces of the two molds 12 and 13 facing each other, and a cavity C is formed by the two cavity forming surfaces 14 and 15. A runner 16 is formed in the fixed mold 12 so as to penetrate the cavity C from an outer surface thereof (a surface opposite to the surface facing the movable mold 13), and the runner 16 is inserted into the cavity C by the runner 16. It can be filled with molten resin. The temperature of the molten resin is, for example, 230 to 260 ° C.
[0014]
On the cavity forming surface 15 of the movable mold 13, a convex portion 15a is formed. The cavity forming surface 15 is formed such that a gap is formed between the tip of the convex portion 15a and the cavity forming surface 14 when the two dies 12 and 13 abut against each other. Due to the convex portion 15a, a concave portion (thin portion) S1a is formed in a portion corresponding to the convex portion 15a in the molded product S1 formed by injection-filling the molten resin into the cavity C.
[0015]
In the fixed mold 12, a cartridge heater (rod-shaped resistance heater) 20 as mold heating means is embedded near a portion corresponding to the concave portion S1a of the molded product S1.
[0016]
A pair of thermocouples 21 and 22 are embedded in the fixed mold 12 near the cartridge heater 20 so as to sandwich the cartridge heater 20.
[0017]
Further, in the fixed mold 12, a pair of heat transfer suppressing grooves 23 and 24 are formed in the thermocouple 21 in the vicinity of the opposite side of the cartridge heater 20 and in the thermocouple 22 in the vicinity of the opposite side of the cartridge heater 20. . The pair of heat transfer suppressing grooves 23 and 24 are formed along a direction orthogonal to the direction in which the two heat transfer suppressing grooves 23 and 24 face each other.
[0018]
Hereinafter, the “direction in which the two heat transfer suppressing grooves 23 and 24 face each other” is referred to as a first direction. The “direction orthogonal to the direction in which the heat transfer suppressing grooves 23 and 24 face each other” is referred to as a second direction. That is, the first direction and the second direction are directions orthogonal to each other, and the second direction is a direction orthogonal to the plane of FIG.
[0019]
In the fixed mold 12, at a position on the opposite side of the movable mold 13 with respect to the pair of heat transfer suppressing grooves 23 and 24, an entry piece accommodating recess 26 for accommodating the entry piece 25 is provided in the second direction. It is formed along. The entry piece 25 is accommodated in the entry piece accommodation recess 26.
[0020]
Note that the fixed die 12, the movable die 13, and the input piece 25 constitute a die K.
The heat transfer suppressing grooves 23 and 24 are open to the bottom surface 26 a of the input piece receiving recess 26. Further, a heat transfer suppressing recess 27 is formed on a side surface of the input piece 25 corresponding to the bottom surface 26a along the second direction. Both ends of the heat transfer suppression recess 27 in the first direction are positions where the heat transfer suppression groove 23 and the heat transfer suppression groove 24 are formed, respectively.
[0021]
The pair of heat transfer suppressing grooves 23 and 24 and the heat transfer suppressing recess 27 form a heat insulating space 28 as a heating control means having a U-shaped cross section when cut in a direction orthogonal to the second direction. Have been.
[0022]
Hereinafter, in the fixed mold 12, a portion surrounded by the cavity forming surface 14 and the heat insulating space 28 is referred to as a heating portion 12a. The heating portion 12a corresponds to a heating portion region in the mold K. That is, the heated region in the mold K is regulated by the heat insulating space 28.
[0023]
The heat insulation space 28 prevents the heat of the heating part 12 a heated by the cartridge heater 20 from being transmitted to the part other than the heating part 12 a of the fixed mold 12 and the input piece 25 across the heat insulation space 28. are doing.
[0024]
In the two dies 12 and 13, a plurality of cooling pipes 30 are embedded near the cavity forming surfaces 14 and 15, and a cooling water 31 as a cooling medium is circulated in the cooling pipes 30. The cooling water 31 is circulated in the cooling pipe 30 at a constant temperature by a temperature controller (not shown). Two cooling pipes 30 are embedded in the heating part 12a. The molten resin injected and filled into the cavity C is cooled by the cooling water 31 circulating in the plurality of cooling pipes 30.
[0025]
The cooling pipe 32 and the cooling water 31 constitute a cooling mechanism 32 as cooling means. Hereinafter, the temperature of the cooling water 31 is referred to as a cooling temperature. The cooling temperature is, for example, 60 to 80 ° C.
[0026]
A control device 35 as control means is connected to the cartridge heater 20, and a power supply 36 is connected to the control device 35. The control device 35 includes a CPU (central processing unit) 35a and a voltage regulator 35b as a voltage regulator. The voltage regulator 35b controls the amount of power supplied to the cartridge heater 20 by controlling the voltage of the power supplied from the power supply 36. The thermocouples 21 and 22 are connected to the CPU 35a. The control unit 35 has a display unit 37 connected to the CPU 35a. The CPU 35a displays the temperature of the heated portion 12a on the display unit 37 according to the detection signals from the thermocouples 21 and 22.
[0027]
As shown in FIG. 2, the CPU 35a supplies L-level power from the controller 35 to the cartridge heater 20 from the start of cooling to the end of cooling, and from the end of cooling to the end of removal of the molded product S1. Control. That is, the CPU 35a controls the controller 35 so that the L level power is continuously supplied to the cartridge heater 20 from the start of cooling to the end of removal of the molded product S1.
[0028]
When the cartridge heater 20 is supplied (applied) with L-level electric power (in this embodiment, the voltage is at a low level), the first heating portion 12a is heated to a temperature higher than the temperature of the cooling water 31 and lower than the temperature of the molten resin. It heats so that it may become solidification temperature t1 as a temperature. The solidification temperature t1 is, for example, about 110 ° C.
[0029]
Further, the CPU 35a controls the cartridge heater from the controller 35 during the period from the end of removing the molded product S1 to the end of the mold clamping, from the end of the mold clamping to the start of the molten resin filling, and from the start of the molten resin filling to the start of cooling. Control is performed so as to supply (apply) H-level power (voltage is high level in the present embodiment) to 20. That is, the CPU 35a controls the controller 35 so that the H level power is continuously supplied from the controller 35 to the cartridge heater 20 from the end of the removal of the molded product S1 to the start of cooling.
[0030]
The “H-level power” refers to power having a larger amount of power than the “L-level power”.
When the H level electric power is supplied, the cartridge heater 20 heats to a solidification delay temperature t2 as a second temperature higher than the solidification temperature t1 and lower than the temperature of the molten resin. The solidification delay temperature t2 is, for example, about 120 ° C.
[0031]
A mold temperature controller 38 is constituted by the cartridge heater 20, the cooling mechanism 32, and the controller 35.
Next, a molding process of the molded product S1 by the mold apparatus 11 including the mold temperature control device 38 of the present embodiment will be described.
[0032]
While the H level power is being supplied to the cartridge heater 20 under the control of the CPU 35a, the two dies 12, 13 are butted against each other (the mold clamping is completed).
As a result, when the molten resin is injected and filled into the cavity C from the runner 16, the temperature of the heating portion 12a of the fixed mold 12 is set to have already reached the solidification delay temperature t2.
[0033]
Then, the molten resin is injected and filled into the cavity C from the runner 16 (start of filling of the molten resin).
Then, in the molten resin injected and filled into the cavity C, the temperature of the heated portion 12a is the solidification delay temperature t2 in the portion corresponding to the heated portion 12a. The formation of the skin layer is slower than in the case where the temperature is lower. Thus, by slowing down the formation of the skin layer, the mold transferability of the concave portion S1a in the molded product S1 is improved.
[0034]
After filling the cavity C with the molten resin, the power supply from the controller 35 to the cartridge heater 20 is changed from the H level to the L level by the control of the CPU 35a in order to cool the molten resin injected and filled into the cavity C. (Cooling start).
[0035]
Then, in the molten resin injected and filled in the cavity C, the portion corresponding to the heated portion 12a is cooled more slowly than the other portions, so that the mold transfer is performed in comparison with the case where the heated portion 12a is not heated. Properties are improved, and as a result, the appearance quality is improved.
[0036]
Further, at this time, since the heating portion 12a is heated by the cartridge heater 20 so as not to be lower than the solidification temperature t1, the temperature of the heating portion 12a does not drop to the cooling temperature which is the temperature of the cooling water 31.
[0037]
Then, the molded resin S1 is molded by cooling the molten resin in the cavity C (cooling is completed).
After the molded article S1 is molded, the movable mold 13 is separated from the fixed mold 12, and the molded article S1 is taken out from both the molds 12, 13 (the end of taking out the molded article).
[0038]
Next, after removing the molded product S1 from both the dies 12, 13, the power supply from the controller 35 to the cartridge heater 20 is changed from the L level to the H level under the control of the CPU 35a. Then, in order to form the next molded product S1, the two dies 12, 13 are butted (the mold clamping is completed), and the molten resin is injected and filled into the cavity C from the runner 16 (the molten resin filling is started).
[0039]
At this time, the time from “the end of taking out the molded product S1” to “the start of filling of the molten resin” may be the time required for the heating portion 12a of the fixed mold 12 to rise from the solidification temperature t1 to the solidification delay temperature t2. That is, when the cartridge heater 20 heats at the same heating amount, for example, the mold device 11 of the present embodiment is fixed compared with the time required for the heating portion 12a to rise from the cooling temperature to the solidification delay temperature t2. The heating portion 12a of the mold 12 is heated in a short time.
[0040]
Therefore, according to the mold apparatus 11 including the mold temperature control device 38 of the present embodiment, the following effects can be obtained.
(1) In the present embodiment, when cooling the molten resin injected and filled in the mold K, the control device 35 sets the temperature of the heating portion 12a of the fixed mold 12 higher than the cooling temperature of the cooling mechanism 32 and The amount of power supplied to the cartridge heater 20 was controlled so that the solidification temperature t1 was lower than the temperature of the molten resin injected and filled into the mold K. Accordingly, it is possible to prevent the heating portion 12a of the mold K in which the cartridge heater 20 is embedded from being excessively cooled.
[0041]
(2) In the present embodiment, when injecting and filling the molten resin into the mold K, the control device 35 causes the temperature of the heating portion 12a to be higher than the solidification temperature t1 and injects and fills the mold K. The amount of electric power was controlled so that the solidification delay temperature t2 becomes lower than the temperature of the molten resin. Therefore, in the molten resin injected and filled in the mold K, the portion corresponding to the heated portion 12a is cooled more slowly than the other portions, so that the mold is less heated than when the heated portion 12a is not heated. Transferability and fluidity can be improved.
[0042]
(3) In the present embodiment, the cooling mechanism 32 includes the cooling pipe 30 embedded in the mold K and the cooling water 31 circulating in the cooling pipe 30. Then, the molten resin injected and filled in the mold K can be cooled through the mold K by circulating the cooling water 31 in the cooling pipe 30.
[0043]
(4) In the present embodiment, the heat insulating space 28 is formed in the fixed mold 12 and the input piece 25. Therefore, compared with the case where the heat insulating space 28 is not formed, the heating portion 12a of the fixed mold 12 can be efficiently heated even if the calorific value of the cartridge heater 20 is reduced.
[0044]
(5) In the present embodiment, the CPU 35a displays the temperature of the heated portion 12a on the display unit 37 in accordance with the detection signals from the thermocouples 21 and 22. For this reason, an administrator who manages the state of the mold apparatus 11 can check the temperature of the heating portion 12a by visually checking the display section 37.
[0045]
(2nd Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. The mold device 41 of the second embodiment is a modification of the mold device 11 of the first embodiment, and the same components as those of the first embodiment are denoted by the same reference numerals. Detailed description will be omitted, and only different points will be described.
[0046]
As shown in FIGS. 3 and 4, in the mold device 41 of the present embodiment, a hole forming portion 42 is formed on the cavity forming surface 15 instead of the convex portion 15 a in the mold device 11. The hole forming portion 42 is formed such that the tip of the hole forming portion 42 comes into contact with the cavity forming surface 14 when the two dies 12 and 13 abut against each other.
[0047]
By the hole forming portion 42, a through hole S2a is formed in a portion corresponding to the hole forming portion 42 in the molded product S2 formed by injection-filling the molten resin into the cavity C.
[0048]
In the molded product S2, a portion corresponding to the space on the opposite side to the runner 16 with respect to the hole molded portion 42 in the cavity C is defined as a molten resin merging portion S2b. The molten resin merging portion S2b is a portion where the molten resin injected and filled into the cavity C from the runner 16 is split into two branches at the hole forming portion 42, and then the two branched branches of the molten resin join.
[0049]
In the fixed mold 12 and the insertion piece 25, the heating portion 12a, the cartridge heater 20, the thermocouples 21, 22 and the heat insulating space are provided in the vicinity of a portion corresponding to the molten resin merging portion S2b of the molded product S2. 28 are arranged.
[0050]
Also in the mold apparatus 41, when the molten resin is injected and filled into the cavity C, the formation of the skin layer is delayed as compared with the case where the temperature of the heating portion 12a is lower than the solidification delay temperature t2, and The mold transferability of the molten resin junction S2b is improved. As a result, a molded product S2 having few weld lines and excellent appearance quality is formed at the molten resin junction S2b.
[0051]
Therefore, according to the mold device 41 including the mold temperature control device 38 of the present embodiment, the same effects as the effects (1) to (5) in the first embodiment can be obtained.
(Other embodiments)
The above embodiment may be embodied by being changed to another embodiment as described below.
[0052]
In each of the above embodiments, the temperature of the molten resin charged into the cavity C from the runner 16 is 230 to 260 ° C., the cooling temperature of the cooling mechanism 32 is 60 to 80 ° C., the solidification temperature t1 is about 110 ° C., and the solidification is performed. The delay temperature t2 was set to about 120 ° C. The temperature is not limited thereto, and the respective temperatures may be appropriately changed depending on the type of the molten resin to be filled into the cavity C. That is, the temperature of the molten resin injected and filled into the cavity C is equal to or higher than the glass transition temperature or the heat deformation temperature, and the solidification temperature t1 is lower than the glass transfer temperature or the heat deformation temperature.
[0053]
In each of the above embodiments, the control device 35 includes the voltage regulator 35b and adjusts the voltage of the power supplied from the power supply 36, and as a result, adjusts the amount of power supplied from the control device 35 to the cartridge heater 20. I was However, the present invention is not limited thereto, and the control device 35 may adjust the amount of power supplied from the control device 35 to the cartridge heater 20 by adjusting the current. That is, the control device 35 may include a current variable circuit that can vary the amount of current instead of the voltage regulator 35b. In this case, the current variable circuit corresponds to a current adjusting unit.
[0054]
In the above embodiments, the heat insulating space 28 is formed in the fixed mold 12 and the input piece 25, but the heat insulating space 28 may be omitted.
In the above embodiments, the cooling water 31 is configured to circulate in the cooling pipe 30. However, instead of the cooling water 31, ethylene glycol or the like may be used as a cooling medium.
[0055]
In the above embodiments, the cooling pipe 30 is embedded in the mold K, and the cooling water 31 flows through the cooling pipe 30 to cool the molten resin injected and filled in the mold K. The present invention is not limited to this. The cooling pipe 30 is omitted, and instead, a cooling water reflux hole is formed in a portion where the cooling pipe 30 is buried, and the cooling water 31 is circulated through the cooling water reflux hole. You may. In this case, the cooling means is constituted by the cooling water 31 and the cooling water reflux hole.
[0056]
Next, technical ideas that can be grasped from the above embodiment and other embodiments will be additionally described below.
(B) The cooling means includes a cooling pipe provided in the mold and a cooling medium circulating in the cooling pipe, and the cooling temperature is a temperature of the cooling medium. The mold temperature control device according to claim 1 or 2.
[0057]
(B) The mold is provided with a heating regulating means for regulating a heating portion area in the mold by heating of the mold heating means. The mold temperature control device according to any one of (a) and (d).
[0058]
(C) The control means controls the amount of electric power supplied to the mold heating means by voltage control or current control, wherein the technical idea (A) and the technical idea are controlled. (2) The mold temperature control device according to any one of (1) to (4).
[0059]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to prevent the heating portion in the mold provided with the mold heating means from being excessively cooled.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of a mold device according to a first embodiment.
FIG. 2 is a time chart illustrating a relationship between a molding process and an amount of power supplied from a control device to a cartridge heater in the first embodiment.
FIG. 3 is a schematic explanatory view of a mold apparatus according to a second embodiment.
FIG. 4 is a sectional view taken along line AA in FIG. 3;
[Explanation of symbols]
12a: heating part, 20: cartridge heater as mold heating means,
32: a cooling mechanism as cooling means, 35: a control device as control means,
38: mold temperature controller, K: mold, t1: solidification temperature as first temperature,
t2: Coagulation delay temperature as the second temperature.

Claims (4)

A mold comprising: a mold heating means for heating a heating portion of the mold by supplying electric power; a cooling means for cooling the mold; and a control means for controlling an amount of electric power supplied to the mold heating means. In the mold temperature control device,
The control means, when cooling the molten resin injected and filled in the mold, the temperature of the heating portion is higher than the cooling temperature of the cooling means and the temperature of the molten resin to be injected and filled in the mold. A mold temperature control device for controlling an amount of electric power so as to have a lower first temperature. The control means is configured such that, when the molten resin is injected and filled into the mold, the temperature of the heating portion is higher than the first temperature and lower than the temperature of the molten resin to be injected and filled into the mold. The mold temperature control device according to claim 1, wherein the amount of electric power is controlled so as to be a second temperature. In a mold temperature control method including a mold heating unit that heats a heating portion of a mold by supplying power, and a cooling unit that cools the mold,
When cooling the molten resin injected and filled in the mold, the metal is cooled to a first temperature higher than the cooling temperature of the cooling means and lower than the temperature of the molten resin injected and filled in the mold. A mold temperature control method comprising controlling an amount of electric power supplied to a mold heating means. When injecting and filling the molten resin into the mold, the mold heating means is configured to have a second temperature higher than the first temperature and lower than the temperature of the molten resin to be injected and filled in the mold. The mold temperature control method according to claim 3, wherein the amount of electric power supplied to the mold is controlled.

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