JPH031920A - Method and apparatus for controlling temperature of heating cylinder of injection molding machine - Google Patents

Abstract

PURPOSE:To eliminate the loss of transparency, burning or scorching of a resin due to overheating by preventing the rise of temp. to predetermined temp. or higher by resetting a temp. set value when dissociation is generated between the actually mea sured temp. of the zone nearest to a cooling source and the temp. set value of said zone so that the temp. set value of the zone almost coincides with the actually mea sured value. CONSTITUTION:A heater #1 is arranged to a nozzle part 7 and heaters #2 - #n are arranged to a barrel part 9 (the heaters #2, #n are arranged to the head 8 of the barrel part 9 at the position most approaching a mounting part 10 having cooling grooves 5) and (n) temp. sensors T1, T2... Tn-1, Tn for detecting the temps. of the wall surfaces of the cylinders in zones to be heated are mounted. The actually mea sured temps. from the temp. sensors T2, Tn-1 of zones {#2 - #n-1} are inputted to the second comparator 16 in a CPU 11 and the actually measured temps. from the temp. sensors T1, Tn of zones {#1, #n} are inputted to the first comparator 2 in the CPU and the actually measured values are compared with respective set values and, when dissociation between both of them is large, the set values are reset to numerical values almost equal to the actually measured values.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method and device for controlling the temperature of a heating cylinder of an injection molding machine, and in particular, to a temperature control method and a device for controlling the temperature of a heating cylinder of an injection molding machine. The present invention relates to a method and device for automatically correcting inappropriate temperature locations by displaying them on a screen.

(Prior art and its problems) Appropriate temperature control of the heating cylinder temperature of an injection molding machine is very important to ensure the quality of molded products.

Conventionally, for this purpose, the nozzle part and the barrel part were divided into a plurality of temperature control zones, and a band heater was wound around the outer circumference of the cylinder as a heating means for each zone, or a sheathed heater was inserted into the cylinder body. Temperature sensors such as thermocouples are installed in appropriate tube locations, and the temperature is controlled using an automatic temperature controller so that the actual temperature measured by the sensor is as close as possible to each set temperature. The methods have been put to practical use ranging from normal accuracy using proportional control to high accuracy 6+1 such as PID control (proportional differential integral control).

As mentioned above, for each zone, the actual temperature value from the temperature sensor is compared with the set value entered in advance from the keyboard by the action of the automatic temperature controller, and the temperature is precisely adjusted according to the separation and its changes. Since PID control is used, once an equilibrium state is reached, the okiya can be maintained at almost the same value as the set value.

(Problem to be solved by the invention) However, since a cooling water groove is provided near the material supply port of the actual heating cylinder mounting part to prevent the temperature from rising, the rearmost zone of the heating cylinder is provided with a cooling water groove. Heat is taken away from the product and the temperature rise is delayed. Also, since the nozzle at the tip of the heating cylinder is in contact with the mold at all times or only during injection, the heat radiated from the nozzle is quite large.If we consider the heating cylinder as a heating system model, there are cooling sources at both ends. It can be regarded as a long cylindrical heating body that is heated uniformly except for both ends. If all zones are set at the same temperature, the measured temperature pattern will be as shown in FIG. 4(b).

In other words, the #1 zone on the nozzle side and the #(n) zone on the rear end lose heat to both sides, so the actual temperature cannot rise to the set temperature. Since the temperature of the sensor part does not reach the set value, the ON operation command remains in the state, and #1. #(n)
The zone heater provides continuous heating.

This is like abandoning the temperature control function and is no different from turning on the heater switch all the time.

Result #1. #2 zone middle part and #(n-).

# (o) The middle part of the zone is overheated,
Fourth, the actual measurement pattern is as shown in [311(b)].

Even if advanced devices such as PID control are adopted for the temperature controllers in each zone, when looking at the heating cylinder as a whole, there are areas where the temperature does not rise to the set temperature or overheating cylinders, making it difficult to obtain the desired uniform temperature pattern. First, the resin material transferred while being heated inside the heating cylinder is heated due to the abnormal temperature rise, which may cause loss of transparency, discoloration, scorching, etc., resulting in defective molding.

(Object of the Invention) The present invention has been made in view of the drawbacks of the conventional example, and its purpose is to calculate the actual temperature of the zone closest to the cooling source, such as the mold or the mounting part having the cooling part. An object of the present invention is to provide a method and apparatus for controlling a heating cylinder of an injection molding machine to prevent the temperature of an intermediate portion between adjacent zones from rising too high.

(Means for Solving the Problems) In order to achieve the above object, the first aspect of the present invention is;
A heating cylinder (1) consisting of a barrel part (9) for conveying the resin while melting and kneading it to 7), and a mounting part (10) having a cooling fg5 (5) for keeping the supplied resin at a constant temperature. The nozzle part (7) and barrel part (9) are divided into a plurality of zones, and heaters (#1 to #(n)) are arranged therein, and temperature sensors (T1 to T(n)) are installed in each zone.
In an injection molding machine that controls the temperature of the heaters (#1 to #(n)) by installing When a deviation of more than a certain degree occurs between the actually measured temperature of the zone and the temperature set value of the zone, the temperature set value of the zone is reset so that the temperature set value of the zone almost matches the actually measured value.

At A-T Yul, we have adopted the following technical means;
A heating cylinder (1) consisting of a barrel part (9) for preferential treatment while melting and kneading the resin, and a mounting part (io) having a cooling #1 (5) for keeping the supplied resin at a constant temperature.
The nozzle part (F) and the barrel part (9) are divided into a plurality of zones and heaters are disposed therein, and a temperature sensor is installed in each zone (+-) to determine the temperature of the heater.

In the injection molding machine to be controlled, ■ A first comparison for comparing the actual measured temperature of the zone closest to the cooling source, such as the mold or the mounting section (10) having the cooling section (5), with the temperature setting value of that zone. Vessel (221, 22n)
is disposed on the output side of the first comparator (221, 22n), and when a deviation of more than a certain degree occurs between the measured temperature and the temperature set value of the zone, it changes the temperature set value of the zone. A set value automatic correction unit (231, 23n) that resets the temperature set value so that it almost matches the actual measurement value; A second comparator (
161, 16n) and ■ the second comparator (161J6n)
), the heaters (#1, #
(n))) Heater relay (19t
, 19o).

The Lti- has adopted the following technical means: ■ A nozzle part (7) that approaches and separates from the mold, a barrel part (9) that melts and kneads the resin and conveys it to the nozzle part (7), and a supply It has a heating cylinder (1) consisting of a mounting part (10) having a cooling part (5) for keeping the resin at a constant temperature, and a plurality of nozzle parts (7) and barrel parts (9). The heaters (#1 to # (n)) are divided into zones and a temperature sensor (T1 to T (n)) is provided in each zone to measure the temperature of the heater (T+ to T (n)). In the injection molding machine to be controlled, ■ the average set temperature of the zone closest to the cooling source such as the mold or the mounting section (10) having the cooling section (5), and the zone adjacent to that zone, and the temperature set closest to the cooling source. Comparing the measured temperature of an intermediate portion between a nearby zone and a zone adjacent to the zone, when a certain amount of overlap occurs between the average value of the set temperature and the actual measured temperature of the intermediate portion, The temperature setting value of the zone closest to the cooling source is reset to approximately match the measured value of the zone closest to the cooling source.

In n-, we have adopted the following technical means: ■ A nozzle part (7) that approaches and separates from the mold, a barrel part (9) that melts and kneads the resin and conveys it to the nozzle part (7), and a supply It has a heating cylinder (1) consisting of a mounting part (10) having a cooling part 5) for bringing the heated resin to a constant temperature,
The nozzle part ()) and the barrel part (9) are divided into a plurality of zones, heaters (#1 to #(n)) are provided, and temperature sensors (T, -Tn) are provided in each zone. In an injection molding machine that controls the temperature of the heater (#, ~ # (n)), ■ the set temperature of the zone closest to the cooling source, such as the mold or the mounting section (10) that has the cooling section (5), and that zone. a calculation unit that calculates and outputs the average value of the set temperature of the adjacent zone, and ■ the average value of the set temperature output from the calculation unit, the zone closest to the cooling source, and the zone adjacent to the zone; A temperature sensor (Tf
, Tr) for comparison with the actually measured temperature of
26F, 26R) and ■ the first comparator (26F, 26
When a deviation of more than a certain degree occurs between the average value of the set temperature output from the calculation section and the actual temperature of the temperature sensor at the intermediate location, cooling is disposed on the output side of R). The set value automatic correction section (27F, 27F Rito, a second comparator (161, 18n) that compares the corrected value from the section (27F, 271+) with the actual value of the zone closest to the cooling source;
61), the heater (#1.#
(n))) Heater relay (191, 1
9n).

We are using technical means to do so.

(Function) ■In an injection molding machine that supplies resin to the rear end of the barrel part (9), heats it, and transports it to the nozzle part (7) while melting and mixing, it has a mold and a cooling part (5). Mounting part (10)
In the zone closest to the cooling source, heat is taken away by the cooling source and the temperature cannot be raised to the specified temperature, and the heater (#1, #
(n)) tends to be always on and 9 times off.

■In that case, even if you control the temperature of each zone, the temperature in the middle part between the zone closest to the cooling source and the zone adjacent to it cannot be controlled and rises above a predetermined temperature, causing burnt resin and other problems. It becomes the cause of

(2) Therefore, in the first and second inventions as set forth in claims 1 and 2, when a certain degree of overlapping occurs between the measured temperature of the zone closest to the cooling source and the temperature setting value of the zone, the temperature of the zone By resetting the temperature set value so that the set value almost matches the actual measurement value, it is possible to prevent the temperature of the intermediate portion between the zone closest to the cooling source and the zone adjacent thereto from rising to a predetermined temperature or higher. This prevents accidents such as burning of the resin.

■Also, in the 3.4 invention shown in claim 3.4, the average value of the set temperature of the zone closest to the cooling source and the zone adjacent to the zone, and the average value of the set temperature of the zone closest to the cooling source and the zone adjacent to the zone. The temperature of the zone closest to the cooling source is determined when a certain amount of overlap occurs between the average value of the set temperature and the actual measured temperature of the intermediate portion between the zones. Resetting the set value so that it almost matches the actual value of the zone closest to the cooling source, and the temperature of the intermediate portion between the zone closest to the cooling source and the zone adjacent thereto rises above a predetermined temperature. This prevents accidents such as loss of transparency, burning, and burning of the resin due to overheating.

(Margin below) (Example) Hereinafter, the present invention will be explained according to illustrated embodiments.

In the drawings, FIGS. 1 and 2 show embodiments of the present invention, and FIG.
Figure (a) is a circuit diagram of the first embodiment of the present invention, Figure 3 (b)
is a circuit diagram of the second embodiment of the present invention, FIG. 4(a) is a temperature distribution curve in the present invention, and FIG. 4(b) is a temperature distribution curve in the conventional example. A comparison will be made between the temperature distribution according to the method and the temperature distribution of the conventional example. The vertical axis of the figure is temperature, and the horizontal axis is the location of the temperature sensor on the heating cylinder.

Figure 4 (a) (b) Joint fruit i11! The value is ・, and the setting value is ×
It is illustrated in ζ. FIG. 4(a) makes it easy to understand the correspondence between the heating cylinder and the distribution map.

In this embodiment, the temperature sensors T, , T2...T
(n-) and T(n), those having the same function are given the same subscripts to their numbers and symbols.

In FIG. 1 and FIG. 4(c), <1> is a heating cylinder of an injection molding machine, which is fixed to the headstock (2). (3) is a resin material hopper, (4) is a material input port, (5) is a cooling groove for cooling the vicinity of the material input port, (
6) is a solenoid valve for turning on and off the cooling water, and the actual temperature value from the temperature sensor Tc of the cooling part (5) and the set value (18c) from the setting device (15) are connected to the second comparator for the cooling part. (lee)
The electromagnetic coil (6a) of the electromagnetic valve (6) is controlled by comparison. The heating cylinder (1) consists of a nozzle part (7), a barrel part (9), and a mounting part (10) from the front, and the nozzle part (7) has a heater #1 and a barrel part (9).
Heaters #2 to #(n) (head (8) of barrel part (9)
) is adapted to be attached with heater #2, and heater #(n) is attached to the attachment portion (1) having the cooling groove (5).
0). ) are arranged respectively.

As these heaters, band heaters, sheathed heaters, etc. are used. The heater has (n) temperature sensors (for example, thermocouples) T I , T 2 , T (n
+).

A front temperature sensor Tf is attached between the first and second temperature sensors T + and T t to measure the temperature of the (n-4)th and (n)th temperature sensors T(n). Sensor T (n
+) and T (n), respectively, are provided with rear temperature sensors Tr.

The control unit is a microcomputer type, and the control unit is CP tJ (1
1), temperature measurement circuit (12), heater control circuit (
13) Display devices such as CRT! (14), and a setting device (15) such as a numeric keypad. Regarding the temperature measurement circuit (12) and the heater control circuit (13), a first embodiment of the present invention will be explained with reference to FIG. 3(a). heater#
Zones other than zones 1 and #(n) (#2 to #(n-)
), in this zone (#2 to #(n-1)l, the measured temperature digital signal (
17) is input to the second comparator (16) in the CPU (11), and the other end of the second comparator (IC) is connected to the setting device (
5, where the set temperature signal (18> from 15) is input:
Here, the set value and the measured value are compared, and depending on the size and change of the difference between the two, an on/off signal is sent to the heater control relay (192) (19n=) using pIDltilNtf. , power supply (20) to relay (192)
・・・・・・(19n-,) via #2...
Send heating power to #(n-1).

On the other hand, in the temperature sensor T l, T (n), the temperature sensor T + of this zone (# 1 , # (n))
, The measured temperature digital signal (17) obtained by A/D converting the measured temperature analog signal from T (n) is c P U (
The set temperature signal (181) from the setting device (15) is input to the first ratio device (221), (22n) in the first comparator (221), (22n). (
18n) is input. Here, the set value and the measured value are compared, and if the 'S distance between the two is large, the first comparator (22
1), (22n) are set on the output side, the set value automatic correction unit (231), (23n) resets the value to a value approximately equal to the actual measured value, and then outputs the second ratio device (16).
1), is input to (16n). This second comparator (1
61), the other terminal of (IGn) is connected to the first comparator (
221), the actual measured value input in (22o) is branched and input, and is compared with the reset setting value. Here, the set value and the measured value are compared, and when they become equal, an on/off signal is sent to the heater control relay (191) (19n) by PID control, and the power supply (20 ) to relay (191)...
(19n) to heater #1. Send heating power to #(n). As a result, heater #1. #(o)
does not remain on all the time, and does not draw a temperature distribution state in which zones 1 and 2 and the intermediate part between zones (n, ) and (n) protrude as shown in FIG. 4(a). In the first embodiment, a temperature sensor T f for monitoring is provided in the intermediate portion.
Tr is installed.

This allows the display device! <14) The display shown in FIG. 4(a) is made, and accidents such as loss of transparency, burning, and burnt due to overheating of the resin are eliminated.

Here, when the transition between the measured value and the set value becomes about 10°C, only zones #1 to #(n) are reset.

FIG. 3(b) shows a second embodiment of the present invention, in which the front part is #1.
The average value of the temperature setting value of the #2 zone and the actual temperature value of the temperature sensor Tf are compared.
(n) Average value of temperature setting value of zone and temperature sensor T'
If the difference is large (10 degrees Celsius in this example), the temperature set value of the #1 zone or #(n) zone will be approximately equal to the actual measured value of the temperature sensor T1 or Tn. Reset it like this. Here, (25F) is #1. In the circuit that calculates the average value of the temperature set value of #2 zone (#1.2 average value calculation circuit), the first comparator (28F)
is connected to one input side of the The output of this first comparator (26F) is connected to a set value automatic correction section (27F), and this set value automatic correction section (27F) is connected to the second comparator (26F).
It is designed to be input to one side of the comparator (161).

Similarly to the first embodiment, the relay (191) is controlled on and off.

On the other hand, the same goes for the rear side, where (25R) is #(n-
, ), #(n) This circuit calculates the average value of the temperature setting values of zones, and is connected to one input side of the first ratio regulator (26R). The output of this first comparator (26R) is connected to a set value automatic correction section (27R), and this set value automatic correction section (27R) is inputted to the - side of the second comparator (16n). It looks like this. Then, as in the first embodiment, the relay (19n) is controlled on and off.

(Effects of the present invention) As described above, in an injection molding machine that supplies resin to the rear end of the barrel, heats it, melts and kneads it and conveys it to the nozzle, the attachment part that has a mold and a cooling part is used. In the zones closest to the cooling source, heat is taken away by the cooling source and the temperature cannot be raised to the specified temperature, and the heater tends to be turned on all the time.As a result, the temperature of each zone cannot be controlled. Even if the cooling source is cooled, the temperature in the intermediate area between the zone closest to the cooling source and the zone adjacent thereto cannot be controlled and rises above a predetermined temperature, causing loss of transparency, burning, burning, etc. due to overheating of the resin. It is. Therefore, in claims 1 and 2, which are the first invention method and the second invention apparatus for implementing the method, when a transfer occurs between the measured temperature of the zone closest to the cooling source and the temperature setting value of the zone, By resetting the temperature setting value of the zone so that it almost matches the actual measurement value, the temperature of the intermediate portion between the zone closest to the cooling source and the zone adjacent thereto is equal to or higher than the predetermined temperature. This prevents the resin from rising to a high temperature and eliminates accidents such as loss of transparency, burning, and burning due to overheating of the resin.

Moreover, in the third invention method and fourth invention apparatus shown in claim 3.4, the average value of the set temperature of the zone closest to the cooling source and the set temperature of the zone adjacent to the zone, and the set temperature of the zone closest to the cooling source. The actual temperature of the intermediate portion between the zone and the zone adjacent to the zone is compared, and when a certain degree of separation occurs between the average value of the set temperature and the actual measured temperature of the intermediate portion, cooling is performed. By resetting the temperature set point of the zone closest to the cooling source to approximately match the measured value of the zone closest to the cooling source, the temperature of the intermediate zone between the zone closest to the cooling source and the zone adjacent to it can be adjusted. This solution prevents the temperature from rising above the predetermined temperature of 111 degrees Celsius, thereby eliminating accidents such as loss of transparency, burning, and burning of the resin due to overheating.

[Brief explanation of drawings]

Fig. 1...Schematic front view of one embodiment of the present invention Fig. 2...
・Enlarged partial cross-sectional view showing the mounting state of the temperature sensor in the present invention FIG. 3 (1)...Block circuit diagram of the first embodiment of the present invention No. 3 rf! I(b)...Block circuit of the second embodiment of the present invention FIG. 4(a)...Temperature distribution graph displayed according to the present invention, FIG. 4(b)...Temperature distribution graph displayed according to the conventional example FIG. 4(e) is a schematic front view of the heating cylinder showing the correspondence between the temperature distribution graph and each zone of the heating cylinder. T, ~T(n)...Temperature sensor #1~#(n)...
・Heater Tf...Front temperature sensor T"...Rear temperature sensor Tc...Cooling section temperature sensor (1)...Heating ring (2)...Headstock (3)...Hopper (4)...Material input port (5)...Cooling water groove (6)...Solenoid valve (6a
)...Electromagnetic coil (7)...Nozzle part (9)
... Barrel part (10) ... Mounting part (11)
... Display device [(12) ... Temperature measurement circuit (13)
... Heater control circuit (15) ... Setting device (161)
~(16n), (16o)...Second comparator of Example 1.2 <181) ~(18n), (18e)-
Set temperature signals (191) to (19n)...Heater control relay (20)...Power supply (221), (22n)...First comparator (231), (23n) of the first embodiment . . . Setting value automatic correction unit (25F), (25R) of the first embodiment - #1 of the second embodiment. #(n) Average value calculation circuit for heater

Claims (4)

[Claims] (1) Consists of a nozzle part that comes into contact with and leaves the mold, a barrel part that melts and kneads the resin while conveying it to the nozzle part, and an attachment part that has a cooling part that keeps the supplied resin at a constant temperature. In an injection molding machine that has a heating cylinder, the nozzle part and the barrel part are divided into a plurality of zones, and a heater is arranged, and a temperature sensor is provided in each zone to control the temperature of the heater. When a discrepancy occurs between the measured temperature of the zone closest to the cooling source, such as an attachment part with a A heating cylinder temperature control method for an injection molding machine, which is characterized by resetting the temperature. (2) It consists of a nozzle part that comes into contact with and separates from the mold, a barrel part that melts and kneads the resin and conveys it to the nozzle part, and an attachment part that has a cooling part that keeps the supplied resin at a constant temperature. In an injection molding machine that has a heating cylinder, the nozzle part and the barrel part are divided into a plurality of zones, and a heater is arranged, and a temperature sensor is provided in each zone to control the temperature of the heater. a first comparator for comparing the measured temperature of a zone closest to the cooling source, such as an attachment part, with the temperature setting value of the zone; and a first comparator disposed on the output side of the first comparator, A set value automatic correction unit that resets the temperature set value of the zone so that it almost matches the actual measured value when a deviation occurs between the temperature set value of the zone and the set value automatic correction unit. a second comparator that compares the reset input from the cooling source with an actual measured temperature of the zone closest to the cooling source; and a heater relay that receives the input from the second comparator and controls the temperature of the heater in the zone. A heating cylinder temperature control device for an injection molding machine, characterized by comprising: (3) It consists of a nozzle part that comes into contact with and leaves the mold, a barrel part that melts and kneads the resin while conveying it to the nozzle part, and an attachment part that has a cooling part that keeps the supplied resin at a constant temperature. In an injection molding machine that has a heating cylinder, the nozzle part and the barrel part are divided into a plurality of zones, and a heater is arranged, and a temperature sensor is provided in each zone to control the temperature of the heater. Compare the average set temperature of the zone closest to the cooling source and the zone adjacent to the cooling source, such as an attachment part with a cooling source, with the actual temperature measured at an intermediate location between the zone closest to the cooling source and the zone adjacent to the cooling source. When a discrepancy occurs between the average value of the set temperature and the actual measured temperature of the intermediate region, the temperature set value of the zone closest to the cooling source is set to almost match the actual measured value of the zone closest to the cooling source. A heating cylinder temperature control method for an injection molding machine, characterized in that the heating cylinder temperature is reset to . (4) It consists of a nozzle part that comes into contact with and leaves the mold, a barrel part that melts and kneads the resin while conveying it to the nozzle part, and an attachment part that has a cooling part that keeps the supplied resin at a constant temperature. In an injection molding machine that has a heating cylinder, the nozzle part and the barrel part are divided into a plurality of zones, and a heater is arranged, and a temperature sensor is provided in each zone to control the temperature of the heater. a calculation unit that calculates and outputs the average value of the set temperature of the zone closest to the cooling source, such as the mounting part, and the set temperature of the zone adjacent to the zone; and the set temperature outputted from the calculation unit. a first comparator for comparing the average value of and the actual temperature measured by a temperature sensor disposed at an intermediate location between a zone closest to the cooling source and a zone adjacent to the zone;
Disposed on the output side of the first comparator, when a discrepancy occurs between the output from the calculation unit and the actual temperature measured by the temperature sensor at the intermediate location, the temperature is set in the zone closest to the cooling source. a set value automatic correction unit that resets the temperature set value so that the value almost matches the measured value of the zone closest to the cooling source;
a second comparator that compares the corrected value from the set value automatic correction unit with the actual value of the zone closest to the cooling source; and receives input from the second comparator to control the temperature of the heater in the zone. A heating cylinder temperature control device for an injection molding machine, characterized by comprising a heater relay.