JPS6235824A - Temperature controlling of injection molder - Google Patents

Abstract

PURPOSE:To develop no deterioration of quality such as the change of properties, decomposition even in abnormality and, in addition, to shorten the heat-up time after the completion of restoration from abnormality by a method wherein, under normal conditions, an injection molder is controlled at normal temperature, and under abnormal conditions detects abnormality and is controlled at temperature lower than the normal temperatures. CONSTITUTION:Temperatures, at each of which no used material solidifies, changes its properties and decomposes even after the stagnation in an injection cylinder 5 for a long time, or which ar lower than normal temperature, are for respective zones Z1-Z4 by means of low temperature setters t1-t4. When abnormality generates, a central controller 21 sends an abnormality signal to a temperature controller 20 which automatically changes-over the controlling of temperature from by molding temperature setters T1-T4 to by the low temperature setters t1-t4. As a result, when anbormality generates, a molder is controlled at temperatures, which are set by means of the low temperature setters t1-t4 and lower than the normal temperatures. In other words, heaters H1-H4 are feed-back controlled by turning ON and OFF so as to bring the temperature detected by temperature ensors S1-S4 to a certain fixed value at all times by comparing the detection data sent from the temperature sensors S1-S4 with the set data sent from the setters t1-t4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an injection molding machine, and more particularly to a method of controlling temperature in an injection cylinder containing a synthetic resin material.

(Prior Art) An injection molding machine, for example, an in-line screw type injection molding machine, includes an injection cylinder, and a screw is inserted into the injection cylinder. Further, the injection cylinder is equipped with a heater, and the injection cylinder is heated and controlled to a predetermined temperature. As a result, the synthetic resin molding material (hereinafter simply referred to as "material") is transferred forward in the injection cylinder by the rotational action of the screw, and is weighed, and the material is melted together with the heating action of the injection cylinder.

The temperature of such an injection cylinder is set at an optimum temperature that does not cause deterioration of the material and is appropriate for the type of material.

By the way, when an abnormality occurs during molding, conventionally the molding cycle is interrupted and recovery is performed manually.

In this case, abnormalities during each process are automatically detected using sensors, etc.
Stop operation of the injection molding machine. On the other hand, the injection cylinder also turns off the heater circuit, etc. at the same time as the operation stops.
Measures are taken to either prevent the material from being heated more than necessary, or to continue heating the material so that it can be used immediately after the abnormality has been recovered.

(Problems to be Solved by the Invention) However, the conventional injection cylinder temperature control method described above has the following problems.

That is, if an abnormality occurs and it takes a long time to repair, the heater circuit etc. are turned to 0FFL and heating of the injection cylinder is interrupted, but in this case, the longer the time, the lower the temperature of the injection cylinder becomes.

Therefore, even after the repair is completed and the operation of the injection molding machine is restarted, it takes time for the injection cylinder to return to its normal temperature, and this time loss greatly reduces work efficiency.

On the other hand, even if an abnormality occurs, if the heating of the injection cylinder is continued, the above-mentioned disadvantages can be eliminated, but on the other hand, the deterioration of the material progresses. In other words, as mentioned above, the temperature of the injection cylinder is set at the optimum temperature so that the material does not change in quality, but even if the temperature is within this permissible temperature, a considerable amount of change in quality occurs, which is caused by the inside of the injection cylinder. The longer the residence time of the material, the more it progresses and may eventually cause decomposition of the material.

(Means for Solving the Problems) The present invention solves the above-mentioned conventional problems, and can be achieved by the temperature control method for an injection molding machine described below.

That is, when controlling the temperature of an injection cylinder in an injection molding machine, the temperature control method according to the present invention first controls the temperature to a normal temperature suitable for the molding material during normal times. On the other hand, when an abnormality occurs, the occurrence of the abnormality is detected, and the temperature is controlled to be lower than the normal temperature based on the detection.

(effect) Next, the operation of the present invention will be explained.

In the temperature control method according to the present invention, when there is an abnormality, that is, when the material remains in a molten state for a long time in the injection cylinder, the abnormality is detected and the temperature is lower than the normal temperature under normal conditions, for example, when molding is attempted. Set the temperature at which the material does not solidify and is unlikely to undergo deterioration or decomposition. As a result, the injection cylinder is preheated, and the temperature is quickly returned to the normal temperature even when restarting the operation.

(Example) Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a cross-sectional side view showing an example of an injection molding machine implementing the temperature control method according to the present invention.

First, the schematic structure of an injection molding machine will be explained with reference to FIG. The figure shows an in-line screw type injection molding machine M. The molding machine M consists of an injection device 2 and a mold bag W4 including a mold 3 disposed in front of the injection device 2. The injection device 2 includes an injection cylinder 5 including a heating cylinder and a screw 6 inserted into the injection cylinder 5. An injection nozzle 7 is provided at the front end of the injection cylinder 5, and a hopper 8 for supplying the material W into the injection cylinder 5 is provided at the upper part near the rear end. On the other hand, the rear end of the screw 6 is equipped with an oil motor 9 that rotates the screw 6.
The screw 6 is connected to a hydraulic cylinder 10 that moves the screw 6 forward and backward.

Next, the configuration of main parts will be explained in detail with reference to FIG.

This figure is a block diagram of a temperature control device that implements the temperature control method according to the present invention.

First, the injection cylinder 5 has a nozzle part Z1, as shown in FIG.
It can be divided into four zones: front Z2, middle Z3, and rear Z4.

Each zone constitutes a heating zone, and a second
As shown in the figure, band heaters H1, H2, H3, and H4 are provided. In addition, temperature sensors S1, S2, and S are provided for each zone.
3 and S4 are arranged, and the temperature is controlled independently for each zone.

Each band heater H1... and temperature sensor S1...
is connected to the temperature controller 20. On the other hand, the controller 20 has molding temperature setting devices Tl, T2, T3, T4, for setting the molding temperature for each zone Z1...
and low temperature setting devices t1, t2, t3, t that are switched in case of abnormality.
Connect 4. Furthermore, the controller 20 includes a central controller 2 that controls and monitors the operation of the injection molding machine M.
Connect 1. Note that the numbers attached to the symbols indicating the band heater, temperature sensor, and each setting device match the numbers of the symbols indicating each zone.

Next, a temperature control method according to the present invention will be explained.

First, the molding temperature at which the material to be used is passed through most, that is, the normal temperature at normal times, is set in advance for each zone Z1 using the molding temperature setting device T1. Also,
A low temperature setting device t1... sets a temperature at which the material to be used will not solidify, change or decompose even if it is allowed to stay in the injection cylinder 5 for a long time, that is, a temperature lower than the above-mentioned normal temperature, for each zone Z1... Set each time. This temperature can be determined experimentally.

Now, assume that the injection molding machine M is operating normally. In this case, the temperature controller 20 controls the former heaters to the molding temperature set by the molding temperature setter T1. In other words, temperature sensor S1...
To ensure that the temperature is always constant by comparing the setting data from
Feedback control is performed by turning off the heater H1.

On the other hand, assume that an abnormality occurs in the injection molding machine M and the operation of the injection molding machine M is stopped. Note that the abnormality in this case requires a certain amount of time to repair, but the heater H1
This refers to cases where it is not necessary to use F for ..., for example: ■ When a screw or torpedo is broken or damaged, resulting in an abnormality in measuring, injection position, or time; ■ When a molded product remains in the cavity mold due to a short shot. Examples include when an abnormality occurs at the injection advance limit position, and (2) when the material hardens at the material supply port (hopper) and the material is not supplied, resulting in a metering error. In the case of (2), the screw and 1-peed must be removed from the injection cylinder and replaced, so they cannot be removed once the material solidifies. Moreover, if it is disassembled, cleaning becomes difficult. In the case of ■, it is necessary to remove the molded product remaining in the cavity, taking care not to damage the mold.In the case of ■, remove the hopper and remove the hardened material, or
I need to peck it out.

If such an abnormality occurs, the central controller 21
An abnormal signal is sent from the temperature controller 20, and the temperature controller 20 automatically switches from the molding temperature setter T1 to the low temperature setter t1 based on the abnormal signal.

As a result, when an abnormality occurs, the temperature is controlled to be lower than the normal temperature set by the low temperature setting device t1. In other words, the detection data from the temperature sensor S1... and the setting device t
1. Compare the setting data from . . . and perform feedback control by turning off the heater H1 . . . so that the temperature is always constant.

When the repair is completed, for example, by pressing an abnormality release switch (not shown) on the control panel, the low temperature setting device t1 is reset.
. . . to switch again to the molding temperature setting device T1. As a result, the temperature of the injection cylinder is raised to the normal temperature in a short time, and molding can be continued in the normal state thereafter.

Although the embodiments have been described in detail above, the present invention is not limited to these embodiments.

For example, although the setting of the low temperature at abnormal times is individually set by the low@ setting device, the circuit may be configured to decrease the temperature at a fixed ratio with respect to the molding temperature (normal temperature). Further, the type of abnormality for which temperature switching is performed is not limited to the above-mentioned example, and may be any abnormality that can be detected, and can be appropriately selected and determined.

Furthermore, a circuit may be provided that automatically turns off the heater if the abnormality release switch is not input even after a predetermined period of time has elapsed after switching to the low temperature when an abnormality occurs.

Further, any heating means can be used as the heater, and although four zones are illustrated in the example, the heating zone may be a single zone or an arbitrary number of zones. Further, although an in-line screw type injection molding machine is illustrated, the present invention can be applied to any other injection molding machine such as a plunger type injection molding machine.

In addition, the detailed structure, conditions, etc. may be arbitrarily changed without departing from the spirit of the present invention.

(Effects of the Invention) As described above, the temperature control method for an injection molding machine according to the present invention controls the temperature of the injection cylinder in the injection molding machine to a normal temperature suitable for the molding material during normal times, and when abnormal We detected an abnormality and controlled the temperature to be lower than the normal temperature based on the detection.
Even if an abnormality occurs in the injection molding equipment and the material remains in the injection cylinder for a long time during repair, quality deterioration such as material deterioration or decomposition will not occur (in addition, after the repair is completed, the material will remain in the injection cylinder for a long time). Operational efficiency is improved by significantly shortening heating time.
Productivity can be improved. Moreover, since it can be implemented simply by software, it can be implemented at extremely low cost without requiring any structural changes.

[Brief explanation of drawings]

FIG. 1 is a longitudinal side view showing an example of an injection molding machine that implements the temperature control method according to the present invention, and FIG. 2 is a block diagram of a temperature control device that implements the temperature control method according to the present invention. In the drawings, 5... Injection cylinder, 20... Temperature controller, 21... Central controller, Hl, H2, H3, H4... Band heater, Sl, 3
2,33.34...Temperature sensor, Tl, T2. T3.
T4... Molding temperature setter, tl, t2. t3. tt・
...Low temperature setting device. Figure 2

Claims (1)

[Claims] 1. When controlling the temperature of the injection cylinder in an injection molding machine, during normal times the temperature is controlled to a normal temperature that is suitable for the molding material, and when abnormalities occur, the occurrence of an abnormality is detected and the temperature is controlled to be lower than the normal temperature based on the detection. A temperature control method for an injection molding machine characterized by: