JP2002361701A - Method and apparatus for controlling temperature of injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance control accuracy, attachment properties and the uniformity of a heating surface and to easily optimize temperature distribution characteristics even after a weighing completion position or the like is altered. SOLUTION: A plurality of heaters 3a, etc., and a plurality of temperature detectors 4a, etc., are provided to the outer periphery of a heating cylinder 2 and, when temperature is controlled so that the heating cylinder 2 becomes predetermined temperature distribution characteristics Ks, the temperature detectors 4a, etc., are arranged at a position where the heaters 3a, etc., including the space among the heaters 3a, etc., and 3b, etc., do not exist. A temperature at an arbitrary position, for example, at an arbitrary position Xb is calculated as a virtual temperature Tdb by operationally processing the temperature gradient between the detection temperatures Tb and Tc of two points, which are obtained from the temperature detectors 4b and 4c arranged in the vicinity of the arbitrary position Xb, and the virtual temperature Tdb is set as the detected temperature Tdb at the arbitrary position Xb to control temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling the temperature of an injection molding machine for controlling the temperature of a heating cylinder so as to have a predetermined temperature distribution characteristic.

[0002]

2. Description of the Related Art In general, an injection device provided in an injection molding machine includes a heating cylinder having an injection nozzle at a tip, and a plurality of sets of heaters and temperature detectors (thermocouples) are provided in the injection nozzle and the heating cylinder. The temperature control is performed so as to have a predetermined temperature distribution characteristic from the injection nozzle to the rear part of the heating cylinder by being provided (for example, Japanese Patent Publication No. 5-565).
No. 1).

In this case, the heating cylinder usually has three control areas, a front part corresponding to the metering zone, an intermediate part corresponding to the compression zone, and a rear part corresponding to the feed zone. And a temperature control system for controlling the temperature. Further, at the time of temperature control, an operator sets target temperatures (target values) for each control region in accordance with the type of resin to be used and the like so that a predetermined temperature distribution characteristic is obtained in advance. Feedback control is performed on the heating temperature based on the detected temperature (detected value) obtained from the temperature detector.

[0004]

However, the above-mentioned conventional temperature control method has the following problems.

First, since each temperature detector has a property of detecting the heating temperature of the heater in each control area to be attached, heat transfer from an adjacent control area becomes a disturbance, which causes a reduction in control accuracy. Becomes

Second, it is necessary to set the temperature distribution characteristic of the heating cylinder in accordance with the screw position. However, since the temperature detected from each temperature detector is directly used, for example, the measurement end position Is changed, it is not easy to optimize the temperature distribution characteristics after the change.

[0007] Third, since the temperature detector is provided substantially at the center of the heater, the heater is required to be drilled, which deteriorates the assemblability and hinders uniformity of the heating surface.

The present invention has solved the problems existing in such prior art, and can improve control accuracy, assemblability, and uniformity of a heating surface.
It is an object of the present invention to provide a temperature control method and apparatus for an injection molding machine that can easily optimize a changed temperature distribution characteristic even when a measurement end position or the like is changed.

[0009]

A temperature control method for an injection molding machine M according to the present invention is provided with a plurality of heaters 3a and a plurality of temperature detectors 4a on the outer periphery of a heating cylinder 2. When the temperature of the heating cylinder 2 is controlled so as to have a predetermined temperature distribution characteristic Ks, the temperature detectors 4a.
Are disposed at positions where the heaters 3a... Do not exist between the heaters 3a.
Temperature detectors 4b and 4c arranged before and after the arbitrary position Xb
From the temperature gradient between the two detected temperatures Tb and Tc obtained as a virtual temperature Tdb by an arithmetic process, and this virtual temperature Tdb is detected as a detected temperature Td at an arbitrary position Xb.
The temperature is controlled as b.

In this case, according to a preferred embodiment, a plurality of detection positions Xa, Xb, Xc corresponding to predetermined screw positions, for example, weighing end positions P, are set, and the temperatures at the detection positions Xa,. Is calculated as a virtual temperature (Tdb ...), and the virtual temperature (Tdb
db ...) is the target temperature (Tsb ...) on the temperature distribution characteristic Ks.
The temperature can be controlled so that

In the temperature control device 1 according to the present invention, a plurality of heaters 3a and a plurality of temperature detectors 4a are provided on the outer periphery of the heating cylinder 2 so that the heating cylinder 2 has a predetermined temperature distribution characteristic K.
s, a plurality of temperature detectors 4a... disposed at positions where the heaters 3a... including the heaters 3a and 3b. An arithmetic processing unit 5 that obtains a temperature at the position Xb as a virtual temperature Tdb by arithmetic processing from two detected temperatures Tb and Tc obtained from the temperature detectors 4b and 4c arranged before and after the arbitrary position Xb; This virtual temperature Tdb is set to a detected temperature Td at an arbitrary position Xb.
It is characterized by including a control unit 6 for performing temperature control as b.

[0012]

Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, the configuration of the temperature control device 1 according to the present embodiment will be described with reference to FIG.

In FIG. 2, M indicates an injection molding machine, particularly an injection device Mi provided in the injection molding machine M. The injection device Mi has an injection nozzle 7 at the tip and a heating cylinder 2 having a hopper 8 at the rear, and a screw 9 is built in the heating cylinder 2. Further, three heaters 3a, 3b, 3c using a band heater or the like are sequentially provided on the outer peripheral portion of the heating cylinder 2 along the axial direction. In this case, the heater 3a is provided at a front portion of the heating tube 2 corresponding to the metering zone, the heater 3b is provided at an intermediate portion of the heating tube 2 corresponding to the compression zone, and the heater 3c is provided at a rear portion of the heating tube 2 corresponding to the feed zone. In each case. Further, on the outer peripheral portion of the injection nozzle 7,
A heater 3f using a band heater or the like is additionally provided. Thereby, four heating areas of the injection nozzle 7, the front part of the heating cylinder 2, the middle part of the heating cylinder 2 and the rear part of the heating cylinder 2 are provided.

The heating cylinder 2 is provided with a plurality of temperature detectors (thermocouples) 4a. In this case, each temperature detector 4a
Are arranged at positions where there is no heater 3a, including between the heaters 3a and 3b. That is, the temperature detector 4a is disposed in front of the heater 3a, the temperature detector 4b is disposed between the heaters 3a and 3b, the temperature detector 4c is disposed between the heaters 3b and 3c, and the temperature detector 4d is disposed behind the heater 3c. Set up. As described above, since the temperature detectors 4a are arranged so as to avoid the heaters 3a, drilling of the heaters 3a is not required, so that the assemblability is improved and the uniformity of the heating surface is hindered. The troubles that occur are also avoided.

On the other hand, each heater 3f, 3a, 3b, 3c and each temperature detector 4a, 4b, 4c, 4d are connected to a molding machine controller 11 having a computer function. Therefore, the molding machine controller 11 includes the arithmetic processing unit 5 based on a computer function. Reference numeral 12 denotes a position detector for detecting a screw position. The position detector 12 is connected to the molding machine controller 11 and
Reference numeral 13 denotes a setting unit (input unit) attached to the molding machine controller 11. The molding machine controller 11 constitutes the control unit 6.

Next, the operation of the temperature control device 1 including the temperature control method according to the present embodiment will be described with reference to FIGS. 2 and 3 and the flowchart shown in FIG.

In FIG. 3, P represents a measuring stroke of Vm.
And Po indicates the metering end position of the screw 9 at which the measuring stroke is Vs.
Now, it is assumed that the weighing end position for the screw 9 is set to P.

First, the molding machine controller 11 has a plurality of detection positions Xa, Xb,
Set Xc. The embodiment shows a case where the detection positions Xa, Xb, Xc are set corresponding to the front part, the middle part, and the rear part of the screw 9. Further, the molding machine controller 11 includes:
An optimum temperature distribution characteristic Ks corresponding to the measurement end position P is set. FIG. 3 shows an example of the temperature distribution characteristic Ks. In the embodiment, the temperature distribution characteristics Ks are shown continuously for easy understanding.
It may be set as individual target temperatures (target values) corresponding to b and Xc. In FIG. 3, Tsb is the detection position Xb.
Shows the target temperature at.

At the time of temperature control, each heater 3a,
3b and 3c are energized to heat the heating cylinder 2 and the temperature of the heating cylinder 2 is determined by the temperature detectors 4a, 4b and 4
c and 4d (step S1). The position of the screw 9 at the weighing end position P is determined by the position detector 1.
2 and is provided to the molding machine controller 11 (step S2).

As a result, the molding machine controller 11
The detection positions Xa, Xb, and Xc on the heating cylinder 2 are obtained, and the temperatures at the respective detection positions Xa, Xb, and Xc are obtained by the arithmetic processing by the arithmetic processing unit 5 (step S3). In this case, since the entire length of the screw 9 is known, the screw position (weighing end position P) detected by the position detector 12 determines the detection positions Xa, Xa, on the heating cylinder 2 corresponding to the screw 9 at the metering end position P. Xb, Xc
Can be requested.

On the other hand, the temperatures at the respective detection positions Xa, Xb, Xc are obtained as virtual temperatures by arithmetic processing. As an example, the virtual temperature T at the detection position (arbitrary position) Xb
A case where db is obtained will be described. First, the arithmetic processing unit 5 receives two detected temperatures Tb and Tc obtained from the temperature detectors 4b and 4c arranged before and after the detection position Xb. In FIG. 3, Kd indicates a part of the actual temperature distribution in the heating cylinder 2. Further, since the detection position Xb on the heating cylinder 2 is determined, the arithmetic processing unit 5 determines the distance Lx between the temperature detector 4b and the detection position Xb and the temperature detector 4c.
And the distance Ly between the detection position Xb. Since a temperature gradient (including flatness) is generated between the temperature detectors 4b and 4c based on the detected temperatures Tb and Tc, the temperature of the detection position Xb located in the middle is calculated by using a function. Ask by Specifically, when the temperature gradient between the detected temperatures Tb and Tc is a linear function, the virtual temperature Tdb at the detected position Xb is Tdb = (Tb−Tc) · ｛Ly / (L
x + Ly)｝ + Tc. Thus, the obtained virtual temperature Tdb is used as the detected temperature (detected value) Tdb at the detected position (arbitrary position) Xb.

On the other hand, the molding machine controller 11 compares the obtained detected temperature (virtual temperature) Tdb with a preset target temperature Tsb on the temperature distribution characteristic Ks, and adjusts each heater 3a so as to correct the deviation. , 3b, 3c (steps S4 to S8). The temperatures at the other detection positions Xa and Xc can be obtained by the same arithmetic processing, and the obtained virtual temperature is used as the detected temperature, so that similar feedback is performed based on the detected temperature and the corresponding target temperature. Control can be performed.

Therefore, according to the temperature control method and the temperature control device 1 according to the present embodiment, the temperature detectors 4a.
Are arranged at positions where the heaters 3a are not present, including between the heaters 3a and 3b, and the temperatures at the arbitrary positions Xb are obtained from the temperature detectors 4b and 4c arranged before and after the arbitrary positions Xb. A virtual temperature Tdb is obtained by calculation from a temperature gradient between the detected temperatures Tb and Tc at the point, and this virtual temperature Tdb is detected at an arbitrary position Xb.
, The detected temperature Tdb is set to each heater 3
.. are less susceptible to disturbances (heat transfer) caused by interfering with each other, and control accuracy can be improved as compared with a conventional case where an independent control system is configured for each heater unit. .

Since the virtual temperature at an arbitrary position obtained by the arithmetic processing is used, unlike the conventional method in which the detected temperatures Ta obtained from the temperature detectors 4a are directly used, the measurement end position is changed. Even so, the temperature distribution characteristics after the change can be easily optimized. That is, when the weighing end position P is changed to another weighing end position Po shown in FIG. 3, the weighing end position Po is located ahead of the weighing end position P. The temperature distribution characteristic is different from the temperature distribution characteristic Ks corresponding to the measurement end position P. Therefore, in this case, since the temperature distribution characteristic Ks also needs to be changed, the detection position Xa is set to Xao, and the detection position Xb is set to Xbo, as shown in FIG.
In addition, it is necessary to change the detection position Xc to Xco. The temperature corresponding to the arbitrary position after the change, for example, the virtual temperature Tdbo at the detection position Xbo is Tdbo =
(Tb-Tc) · {Lyo / (Lxo + Lyo)} + T
c, the temperature distribution characteristics after the change can be optimized using the virtual temperature Tdbo.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
The detailed configuration, method, and the like can be arbitrarily changed, added, or deleted without departing from the gist of the present invention. For example, in the embodiment, three detection positions Xa, Xb, and Xc are illustrated, but the selection and number of these positions are arbitrary. Also,
The virtual temperature is obtained by calculating the temperature gradient between the two detected temperatures Tb, Tc... As a linear function, but correction may be performed or another function may be used if necessary. Furthermore, the case where the screw position is applied to the weighing end position P... Has been illustrated, but other screw positions may be used.

[0027]

As described above, according to the temperature control method (temperature control device) for an injection molding machine according to the present invention, the temperature detector is disposed at a position where there is no heater including heaters, and the temperature at any position is determined. Is calculated as a virtual temperature from a temperature gradient between two detected temperatures obtained from the temperature detectors disposed before and after the arbitrary position, and the virtual temperature is controlled as the detected temperature at the arbitrary position. It has a remarkable effect like

(1) Since each of the temperature detectors is disposed so as to avoid the heater, it is not necessary to perform a drilling operation on the heater, so that the assemblability can be improved and the uniformity of the heating surface is hindered. Can be avoided.

(2) Since each detected temperature is hardly affected by disturbance (heat transfer) generated by each heater interfering with each other, an independent control system is configured for each heater as in the related art. Control accuracy can be improved as compared with the case.

(3) Since the virtual temperature at an arbitrary position obtained by the arithmetic processing is used, unlike the conventional method in which the detected temperature obtained from each temperature detector is directly used, even if the measurement end position or the like is changed, it is changed. The subsequent temperature distribution characteristics can be easily optimized.

[Brief description of the drawings]

FIG. 1 is a flowchart for explaining a processing procedure of a temperature control method according to a preferred embodiment of the present invention;

FIG. 2 is a block diagram of a temperature control device according to a preferred embodiment of the present invention;

FIG. 3 is an explanatory diagram of the operation of the temperature control method and the temperature control device;

[Explanation of symbols]

 M Injection molding machine 1 Temperature control device 2 Heating cylinder 3a Heater 4a Temperature detector 5 Arithmetic processing unit 6 Control unit Ks Temperature distribution characteristic Xb Detection position (arbitrary position) Tb Detection temperature Tdb Detection temperature (virtual temperature) P … Measuring end position (screw position) Tsb Target temperature

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G05D 23/19 G05D 23/19 G (72) Inventor Takashi Terashima 2110 Nanjo Nanjo, Sakijo-cho, Hishina-gun, Nagano Prefecture F term (reference) 4F206 AP051 AR061 AR07 JA07 JD03 JL02 JM01 JN43 JP11 JP13 JQ41 JQ46 5H323 AA40 CA08 CB02 CB42 DA01 EE01 EE13 FF04 FF10 HH02 HH03 KK05 MM06

Claims (4)

[Claims] 1. A temperature control method for an injection molding machine, wherein a plurality of heaters and a plurality of temperature detectors are attached to an outer peripheral portion of a heating cylinder, and the temperature of the heating cylinder is controlled to have a predetermined temperature distribution characteristic. The temperature detector is disposed at a position where no heater is present, including between the heaters, and a temperature at an arbitrary position is obtained from a temperature gradient between two detected temperatures obtained from temperature detectors disposed before and after the arbitrary position. A temperature control method for an injection molding machine, wherein the temperature is obtained as a virtual temperature by arithmetic processing, and the virtual temperature is controlled as a detected temperature at the arbitrary position. 2. A plurality of detection positions corresponding to predetermined screw positions are set, and a temperature at the detection position is obtained as a virtual temperature by the arithmetic processing, and the virtual temperature becomes a target temperature on the temperature distribution characteristic. The temperature control method for an injection molding machine according to claim 1, wherein the temperature is controlled in such a manner. 3. The temperature control method for an injection molding machine according to claim 2, wherein the screw position is a metering end position. 4. A temperature control device for an injection molding machine, wherein a plurality of heaters and a plurality of temperature detectors are attached to an outer peripheral portion of a heating cylinder, and the temperature of the heating cylinder is controlled to have a predetermined temperature distribution characteristic. A plurality of temperature detectors disposed at positions where no heaters are included, including between the heaters, and a temperature at an arbitrary position, from a temperature gradient between two detected temperatures obtained from temperature detectors disposed before and after the arbitrary position. A temperature control device for an injection molding machine, comprising: a calculation processing unit that obtains a virtual temperature by a calculation process; and a control unit that performs temperature control using the virtual temperature as a detected temperature at the arbitrary position.