JPH0299311A - Method and device for mold temperature adjusting - Google Patents

Abstract

PURPOSE:To shorten time and enhance efficiency by inputting the molding condition into a control device, controlling the temperature of a refrigerant and converging the mold temperature to the desired equilibrium temperature. CONSTITUTION:For instance, the last mold temperature TM' when a chiller 3 is computed from the molding condition input in a microcomputer control device 5 which is to an injection molding machine. The anticipated temperature rise DELTATM=TM'-TM of a mold 2 is computed from the equilibrium mold temperature TM' when the computed chiller 3 is not used, and the chiller refrigerant equilibrium temperature Tc and DELTATc as the function of DELTATM, ...t1, the time delay from the temperature rise of the refrigerant returning to the chiller 3 to making the action of the refrigerant of the chiller 3 on, and ...t2, the time for lowering the temperature of refrigerant DELTATc, respectively input in the form of a table in RAM of the injection molding machine 1, are called, and the refrigerant temperature of the chiller 3 from the control device 5 of the injection molding machine 1 is controlled, and equilibrium temperature TM of the mold 2 is realized in the shortest time without any trouble such as overrun or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to the temperature adjustment of molds used in injection molding, etc., and particularly to the temperature control of molds equipped with refrigerators! This invention relates to a method and device for controlling optimal mold temperature adjustment from the injection molding machine side when using a Pl adjustment machine.

(Prior art and its problems) During injection molding, the temperature of the mold rises due to the amount of heat brought in by the molten resin injected into the mold, so it is necessary to circulate a cooling medium at an appropriate temperature in the mold. The mold is adjusted to an optimum temperature so that the molded product can be released optimally and the cooling time can be as short as possible.

However, depending on requirements such as the type of raw material resin, the shape of forming bacteria, and cycle time, the amount of heat brought into the mold by the melting temperature may be greater than the amount of heat removed from the mold by the cooling medium, and the amount of heat returned from the mold may be greater than the amount of heat removed from the mold by the cooling medium. Since the temperature of the cooling medium that comes in will only increase, the temperature of the mold with a well-known refrigerator! Using a chiller (hereinafter simply referred to as a chiller) For example, a chiller is often used when molding thick-walled products using resins with relatively high specific heat, such as PE or PR, at a high cycle speed.

(Problems to be Solved by the Invention) However, if this chiller is not used properly, not only will it not exhibit the advantage of shortening the cycle, but it will also cause problems such as repeated molding defects.

A common example of this is that the chiller is used too early and starts molding with too much cooling of the mold, resulting in the flow of molten resin being injected into the mold cavity. Problems such as deterioration and an increase in molding defects are raised.

In particular, when a hot runner or hot tip nozzle is used, strict temperature control is required at the gate, so special temperature control is required at the start of molding when a chiller is used.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention aims to: ■ Before starting molding, the molding conditions based on the mounting mold (2), the resin used and the molding operation, and the continuous molding input the desired equilibrium mold temperature at the desired equilibrium temperature into the control device (5), then control the temperature of the refrigerant circulating through the mold (2) with the control device (5), and adjust the mold temperature to the desired equilibrium temperature. to converge.

In Section 2, we have adopted the following technical means: ■Before starting molding, we need to determine the molding conditions based on the installed mold (2) and the resin used, the setting conditions for operation, and during continuous molding. Input the desired equilibrium mold temperature into the sub-197 device 5). Next, molding is performed while circulating the refrigerant between the chiller (3) attached to the molding machine and the mold (2), and the refrigerant rises. The chiller (
The control device (5) performs on/off control of the refrigerator (3) to remove heat from the refrigerant and converge the mold temperature to the desired equilibrium temperature.

We have adopted the technical means of
In the method for adjusting the temperature of a mold (2) in Section 2 or Section 2, the control device (5) is a control device attached to a molding machine.

In Section 4, we adopt the technical means of
> temperature control device; ■Mold (2) mounted on molding machine (1) and molding machine (1)
) and the chiller (3) attached to it.

■Refrigerant circulating between the chiller (3) and the mold (2),
■ A circulating refrigerant temperature sensor (25) that detects the temperature of the refrigerant returning from the mold (2) to the chiller (3);
) and molding conditions based on the resin used, setting conditions for molding operations such as one cycle time, data such as desired equilibrium mold temperature during continuous molding, and input from the circulating refrigerant temperature sensor (25). It consists of a control device (5) that receives the data and controls the chiller (3) on and off to converge the mold temperature to the desired equilibrium temperature.

We have adopted the technical means of
In the temperature control device for the mold (2) in section 2, the control device W (5
) as a control device attached to a molding machine.

; is adopted as a technical means.

(Sakukawa) ■Before starting molding, check the installed gold 7 (¥ (2)), the resin used, and the microcomputer control system W that comes with the injection molding machine (of course, it goes without saying that an external control device can also be used). From the molding conditions input and set in (5), the chiller (
3) Calculate the final mold temperature (TM') when not in use.

(2) Next, without starting the chiller (3), only the water pump for the refrigerant is started to circulate the refrigerant at room temperature (Tea) to the mold (2) and start molding.

■Mold (2) by temperature sensor (25) for circulating refrigerant
After detecting the start of temperature rise of the refrigerant returning to the chiller (3),
After a certain period of time (tl) has elapsed, the chiller (3) is started.

■ Calculate the expected temperature rise (ΔTM = TM' - TM) of the mold (2) from the equilibrium mold temperature (TM') when the chiller (3) is not used, calculated in step (2) above, As a function of (Δ1°H); O Required equilibrium temperature of chiller refrigerant... (Tc) and (ΔTc) ) time delay before turning on the refrigerator,
......(tl) Temperature drop of O refrigerant (ΔT
The time for performing e)...(t2); is input in advance in the RAM of the injection molding machine (1) in the form of a table, and is called up. ■ Control of the injection molding machine (]) From the device (5) to the chiller (
3) by controlling the refrigerant temperature to maintain the equilibrium temperature (TN) of the mold (2).
) can be realized in the shortest time by traps such as overruns.

(The following is a blank space) <Example> An example of the present invention will be described below with reference to the drawings. 1st
The figure is an explanatory diagram of an apparatus in which the present invention is applied to an injection molding machine. (1) is an injection molding machine, (2) is a mold, (3) is a chiller, (4) is a control device for the chiller, and (5) is a control device for the injection molding machine. The injection molding machine (1) has a fixed plate (1
1), moving plate (12), cylinder plate (13)
), a mold opening/closing device consisting of a mold opening/closing cylinder (14), a toggle device (15), and a tie bar (not shown), a heating cylinder (16), an injection cylinder (17), and a screw drive hydraulic motor (18). It is composed of an injection device and opens and closes the fixed mold (21) and the movable mold (22) mounted and attached to the fixed and movable plates (11) and (12).

The chiller (3) includes a cooling tank (31) that stores a refrigerant (usually water containing a rust preventive agent), and a coil (32) in the tank (31) that contains a refrigerant gas such as Freon. It consists of a heat pump (33) that sends water, a refrigerant temperature sensor (34) of a cooling tank (31), etc., and the cooled refrigerant is sent to the mold (2) by a water pump (35).

(36) and (37) are the water inlet of the chiller (3), respectively;
This is a stop valve installed at the water return port, and (38) is a manual control valve that adjusts the amount of water fed. The cooling water inlet (23) and cooling water outlet (24) of the movable mold (22) and the chiller (
3), connect the water supply port (36) and water return port (37) with a conduit made of an insulating material such as a rubber hose, and connect the mold outlet (24) to the chiller ( 3) A circulating refrigerant temperature sensor (25) is installed to measure the temperature of the returned refrigerant, and the temperature signal is input to the control device (5) of the injection molding machine (1). Control device(
5) is a microcomputer system, originally an injection molding machine (
1) CPU, ROM, and RA in charge of arithmetic control and process control
M, input interface (all not shown) and numeric keypad for setting input values! ! , (51), a CRT (52) that outputs a control screen, and a keyboard (53) that switches the control screen and moves the cursor, and in this embodiment, the above-mentioned components are used. However, it goes without saying that it is not limited to this. In this case, the calculation procedure for calculating ΔTN' and the value of ΔTM' will be explained in order to control the temperature of the chiller (3) explained in section ■■. In order to input a table in advance for selecting ΔTc, ([, ), and (t2) from , it is necessary to increase the number of memories in the ROM and RAM of the control device attached to the molding machine (5). Chiller (3) Ill! l control bag fi! (4) is for turning on/off the refrigerant water pump (35) and controlling the temperature of the refrigerant, but in order to control the temperature of the refrigerant, the refrigerant temperature sensor ( The temperature signal from the refrigerant gas heat pump (34) is received and compared with the refrigerant set temperature from the molding machine attached control device (5), and the temperature signal from the refrigerant gas heat pump (34) is compared until the two values match.
There is a temperature control bag W (41) that turns on 3) and turns it off when they match.

The operation of the embodiment of the present invention having the above configuration will be described in detail. The mold (2) is replaced with a new one, the molding conditions corresponding to the resin used are set using the keyboard (53) and digital key (51) of the control device (5), and the molding work is started manually. Initially, it would be fine to leave the refrigerant in the mold (2) without circulating it, but once a stable molded product can be obtained, switch to automatic molding and at the same time install a heat pump (33) for the refrigerant gas.
) remains off, and the water pump (35) is turned on to begin cooling the mold. Stop valves (36) and (37) are fully open, water flow control valve (38) is fully closed, and water supply bong 7 (35) is opened.
The cooling tank (31
) → Stop valve on chiller water supply side (36) → Mold inlet (2
3) The heat of the resin injected into the mold cavity is circulated in the order of → mold cooling water passage → mold outlet (24) → stop valve on the chiller return side (37) → cooling tank (31). The mold (2) is cooled with room temperature water (Tco) while being replaced. At this time, the circulating refrigerant temperature sensor (25) and the refrigerant temperature sensor (34) of the cooling tank (31) are at almost the same temperature. It shows. At this time, the refrigerator (3) of the chiller (3)
3) The resin material and mold (2) are left unused.
Mold (2) for continuous molding under the molding conditions set by
) can be calculated as follows.

The amount of heat flowing from the molten resin into the mold per unit time Q[
keal/h] is; where I: Injection amount [g] t: 1 cycle time [sec] TH: Temperature of the resin used at the exit of the heating cylinder nozzle ['Cl 7M': Equilibrium mold temperature when no chiller is used ['
C] Cp: Specific heat of the resin used [:keal/kg-''C On the other hand, the temperature of the mold (2) rises in response to this amount of heat Q, but at that time; Q=W ・ (TM'-TMo) ・Theory C...
・・・・・・・・・・・・・・・・・・・・・(2), where, W: Weight of the mold used [kg] TMo: Mold temperature at the start of molding [ 'C] C-: Specific heat of mold material [keal/kg ・'CI (1)
From formula (2), (3,6I÷t)・(TI-TM')・Cp=W・(
TM' - TMo)・C@・・・・・・・・・・・・
(3) For simplicity here; = (3,61÷t)・Cp K t = W−
According to C theory, equation (3) becomes K + (Tll TM'
)=K z (TM' TH6).

,', TM' = (K,・TllKt・TM)÷
(K + + K t)・・・・・・・・・(4) As mentioned above, the equilibrium mold temperature when no chiller is used (
TM') is the injection molding machine (1) and mold (1) before the start of molding.
Calculations can be made from the state of 2). That is, ■ injection Ma
r) from the set value of the charge stroke; ■Resin temperature (Tll> from the temperature set value of the heating cylinder (16) and nozzle part; ■Mold weight (W) when the mold (2) is mounted. ■The specific heat (Cp) of the resin is determined from the table written in the RAM in the control device (5) according to the code settings of the resin used. ■One cycle time (1) can be calculated by multiplying appropriate coefficients from the actual values set or by a timer, so (TM') can be calculated at the initial stage of molding using equation (4).

On the other hand, when using the chiller (3), the desired flat finger mold temperature TN is when the refrigerant temperature (Tc) #mold temperature (TM) is reached by the on/off temperature control function of the chiller (3). The mold temperature (TM) must be the lowest temperature at which the molded product can be released smoothly and at the same time does not become too cold and cause dew droplets to form on the surface of the mold cavity. Desirably, this information is input to the control device (5) when setting the conditions at the beginning of molding.

The above calculation process is summarized in the flowchart of FIG. 2, and steps 1 (abbreviated as Sl, hereinafter the same) to 83 correspond to the above explanation. (Above, 81
~3) ★S4; The mold equilibrium temperature (TM') when the chiller (3) is not used, calculated in S3, and the proper use of a certain chiller (3), which was set in advance from the keyboard (53) ΔTM = TM″
- Calculate TI4 ★S5; In order to suppress the mold temperature which rises to (TM') to (TM) when the chiller is not used, the following (Te), (T2) which is the goal of the present invention
, (tl).

(1) Ta: Final equilibrium temperature of chiller refrigerant...
['C]ΔTc=Tea-Te: Refrigerant temperature reduction amount - ['
CI Teo here: Chiller refrigerant temperature ['C] (2) tt when the chiller heat pump is not turned on; After turning on the chiller (3) heat pump (33) (Tc
)... [sec] (3) tl; Time from when the chiller refrigerant temperature starts to rise above (Tea) until the chiller heat pump (33) is turned on... [5ecl can be selected from the table written in the RAM in advance. In order to write it to the RAM table, first determine how much ΔTc should be set for 67M, which was found through experiments in many cases. decide. Chiller (3)
If the final equilibrium temperature is set too low, dew condensation will occur on the mold cavity surface, resulting in poor molding.

Therefore, it is necessary to keep the temperature at a level that does not drop to that low.

For (Te) thus selected, (t, ) is selected. Chiller (3) for as small as possible (t,)
I want to quickly lower the chiller water temperature to < (Ta), but if I lower the chiller refrigerant temperature too quickly, the mold temperature will be low (TM
) is not reached. Also, if (tt) is too large, the mold temperature will rise once and then start to fall, resulting in (TN)
convergence is delayed. Therefore, the best point (
There is tt), and we will experiment with tt wheat (tl).
If (1+) is too small (that is, if the heat pump (33) of the chiller (3) starts operating too early), the above (tt
) is small, and conversely, when (E, ) is too large, the shape is similar to that when (tt) is too large.

Therefore, it is set to (1+), which is in the middle.

The best (ΔT
c), (Lx), and (tl) as shown below; if you input 67M, you can find the optimal (ΔTc), (tz), (
tl) can be read.

★S6; Molding progresses and the material resin is heated to the heating cylinder (16
) The temperature of the mold (2) begins to rise due to the amount of heat Q brought into the mold (2) from (1)
When detected by the control device W (5), the control function of the present invention begins to operate.

*S7: At the beginning of M <tl), rm let, still chiller (3) Wait without issuing a command to lower the refrigerant temperature, as shown in the temperature diagram in Figure 3 If the operation is too fast, it will look like the broken line B, and the mold (2)
The time to reach the required equilibrium temperature (TM) of is increased. On the other hand, if the temperature reduction operation of the refrigerant is too slow, the equilibrium temperature (TM) will overrun and rise too much as shown by the broken line C, and then settle to the desired change temperature (TM) after a considerable period of time has passed. Therefore, (t,) selected in said table
After the waiting time, moving to S7 has the highest activity.
xl-(Shinhe mouth 5゜゜★The set temperature of the S8 binary refrigerant is lowered by 1℃ from the current circulating temperature at room temperature. This action is performed by the control device (5) of the molding machine (1). So I went and
It is transmitted to the temperature control device ff <41) of the chiller (3).

The chiller cold tofu temperature is determined by ΔTe[”C] as shown in the bottom of Figure 3.
2[It is selected from the table that it should be lowered by multiplying by 5eel.

As a numerical example, if c = 10 ['c] t 2 = 300 [qec], then 1
0r'C]÷300[sec]=1/30["C#+
ec], so it is actually f&3 that lowers the setting by 1℃.
All you have to do is wait 0 seconds.

★Repeat the operations from S97 until the chiller refrigerant temperature drops to Tc ["C].

★S10; After that, use the normal temperature control function of the chiller (3).
0 or more to maintain c['C], the mold (2) is a moving mold (
22) was explained as a cooling unit using the chiller (3), but if you want to control both fixed and moving molds (21) and (22) at different equilibrium temperatures (Tc, ), (Tex), The above-mentioned equipment is installed in duplicate using a tank two chiller, etc., and controlled as separate systems.

Further, although the present invention has been described as an example of injection molding, it goes without saying that it can be similarly applied to a wide range of plastic moldings such as blow molding and extrusion molding, where a mold that performs cooling with a chiller is used.

(Effects) As mentioned above, the method of the present invention described in item 1 uses a control device to control the molding conditions based on the mounted mold, the resin used, and the molding conditions, as well as the desired equilibrium mold temperature during continuous molding, before starting molding. and enter
Subsequently, the temperature of the refrigerant circulating through the mold is controlled by a control device, and the mold temperature is converged to the desired equilibrium temperature. The molding conditions based on the molding machine and the resin used, the setting conditions for determining the molding operation, and the desired equilibrium temperature during continuous molding are input into the control device, and then the chiller and mold installed separately from the molding machine are input. Molding is performed while circulating a refrigerant between the molds, and after a predetermined period of time has elapsed after detecting a rise in the temperature of the refrigerant, the control device controls the chiller's refrigerator on and off to remove heat from the refrigerant and reduce the mold temperature. The method is to converge to the desired equilibrium temperature, and in order to realize this method, the apparatus of the present invention described in item 4 includes a mold mounted on a molding machine, a chiller installed separately from the molding machine, and a chiller. A temperature sensor that detects the temperature of the refrigerant circulating between the mold and the mold and the refrigerant returning from the mold to the chiller, and settings for molding operations such as molding conditions and 1 cycle time based on the installed mold and resin used. A control device that receives input data such as conditions, desired equilibrium mold temperature during continuous molding, and data from the temperature sensor, controls the chiller on and off, and converges the mold temperature to the desired equilibrium temperature. As a result, the refrigerant temperature can be accurately managed by the computer of the control device attached to the molding machine so that the mold reaches the optimum equilibrium temperature in an appropriate temperature rising state. In other words, ■In molding using a chiller, the temperature of the mold at the start of molding is smoothly controlled, defects at startup are reduced, and the mold is automatically brought to an equilibrium mold that increases efficiency in the shortest amount of time. go.

■Even amateurs will be able to efficiently mold good products using a chiller without making mistakes.

■If it is a microcomputer-controlled molding machine, it can be easily connected and wired to the chiller control device.

There are advantages such as.

In addition, by using the control device attached to the molding machine as described in item 3 or 5, once the table for refrigerant management is entered, it can be unified with other molding conditions. The refrigerant temperature can be controlled from the molding machine side, and as a result,
This has an extremely practical advantage in that advanced mold temperature control can be performed very simply and accurately using the bare artificial port.

[Brief explanation of drawings]

Fig. 1...Schematic plan view of one embodiment of the present invention Fig. 2...
・Flowchart of the present invention Figure 3...Time-mold temperature curve diagram of the present invention Figure 4
Figure... Time-chiller refrigerant temperature curve diagram in the present invention (1)... Injection molding machine (2)... Mold (3)
... Chiller (4) ... Chiller control device 5
)...Injection molding machine control device (11)...Fixed plate (12)...Moving plate (13)...Cylinder plate (14)...
Type rM leap cylinder (15)...Toggle device (16
)...Heating cylinder (17)...Injection cylinder (18)...Hydraulic motor for screw drive (21)
・・Fixed mold (22)・・Movable mold (23)・
...Cooling inlet (24)...Mold outlet (25)...
... Temperature sensor for circulating refrigerant (31) ... Cooling tank (32) ... Coil (
33) Heat pump (34) Refrigerant temperature sensor (35) Water pump (36) (3)
)...Stop valve (38)...Water flow control valve (4
1)...Temperature adjustment device (51)...-r'/key device (52), CR'r' (53)...Keyboard

Claims (5)

[Claims] (1) Before starting molding, input the installed mold, the molding conditions based on the resin used, the molding operation, and the desired equilibrium mold temperature during continuous molding into the control device, and then input the temperature of the refrigerant circulating through the mold. A method for adjusting the temperature of a mold, characterized in that the temperature of the mold is controlled by a control device to converge the temperature of the mold to the desired equilibrium temperature. (2) Before starting molding, enter the molding conditions based on the installed mold and the resin used, the setting conditions for determining the molding operation, and the desired equilibrium mold temperature during continuous molding into the control device, and then proceed with the molding. Molding is performed while circulating a refrigerant between the mold and a mold temperature controller with a refrigerator installed separately from the machine, and after a predetermined period of time has passed after detecting a rise in the temperature of the refrigerant, the chiller's refrigerator is turned on and off.
A method for adjusting the temperature of a mold, characterized in that off control is performed by a control device to remove heat from the refrigerant and converge the mold temperature to the desired equilibrium temperature. (3) The method for adjusting the temperature of a mold according to item 1 or 2, characterized in that the control device is a control device attached to a molding machine. (4) a mold mounted on a molding machine, a mold temperature controller with a refrigerator installed separately from the molding machine, and a refrigerant circulating between the mold temperature controller with a refrigerator and the mold; A temperature sensor that detects the temperature of the refrigerant that returns from the mold to the mold temperature controller with refrigerator, molding conditions based on the installed mold and resin used, setting conditions for molding operations such as 1 cycle time, and continuous In response to input data such as the desired equilibrium mold temperature during molding and data from the temperature sensor, on/off control of the mold temperature controller with refrigerator is performed from the mold to adjust the mold temperature to the desired temperature. A temperature control device for a mold, comprising a control device for converging to an equilibrium temperature. (5) The mold temperature regulating device according to item 4, characterized in that the control device is a control device attached to a molding machine.