JPH0639120B2 - Control method of vent type injection molding machine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for controlling a vent type injection molding machine in which a vent hole is provided in an intermediate portion of a heating cylinder.

[Prior art and its problems]

A vent type injection molding machine is known in which an exhaust vent hole is provided in the middle of a heating cylinder containing a screw.

In the vent type injection molding machine, the molding material is supplied to the inside of the rear part of the heating cylinder, and the molding material is transferred to the front while being plasticized and melted by heating and rotation of the screw. Then, at this time, vapor and gas components generated from the resin are discharged to the outside through the vent hole.

By the way, it is important to always control the resin state (resin temperature, resin amount, fluidity, etc.) in the heating cylinder to the optimum state in order to improve the molding quality, especially in the case of a vent type injection molding machine. Requires more rigorous control than the non-vent type injection molding machine.

However, since the resin is transferred inside the heating cylinder by the screw, it is not easy to accurately grasp the above-mentioned resin state and control it accurately. For example, the heating zone of the heating cylinder is divided into a plurality of parts in the front-back direction, and different temperatures are set for each heating zone, but since the temperature is detected by the temperature sensor attached to the heating cylinder, the actual resin temperature Is difficult to grasp and the temperature of each heating zone is not uniquely determined, so temperature setting is not easy.

After all, in the past, it was the actual situation that the operator (operator) set the temperature solely by experience and intuition, relying on the overall molding state, etc., not only it is not possible to perform accurate setting, but it takes a lot of time. Since the resin temperature depends on other various control elements such as the material temperature before entering the heating cylinder, the resin amount, and the rotation speed of the screw, the resin temperature,
Further, there is a problem that it is difficult to maintain the resin state in an optimum state.

The present invention solves the problems existing in the prior art as described above, and an object thereof is to provide a control method of a vent type injection molding machine capable of easily and reliably setting an optimum resin state in a heating cylinder. .

[Means for Solving the Problems]

The control method of the vent-type injection molding machine according to the present invention, when controlling the vent-type injection molding machine 1 in which the vent hole 4 is provided in the middle part of the heating cylinder 3 having the screw 2 built therein,
A plurality of control elements that influence the resin state in the heating cylinder 3,
For example, the material supply amount in the material supply mechanism 6, the heating cylinder 3
Temperature of a plurality of heating zones in, material supply mechanism 6
The heating temperature, the rotation speed of the screw 2 and / or the back pressure, etc. are set in the priority order, and the resin temperature in the vent hole 4 during the molding cycle is set, for example, in the vicinity of the vent hole 4. The contact type temperature sensor 5 detects the temperature, and based on the detected resin temperature, a plurality of control elements are variable in order of priority control.

[Work]

According to the control method of the vent type injection molding machine 1 according to the present invention, for example, the heating cylinder 3 using the non-contact temperature sensor 5 or the like.
The resin temperature in the vent hole 4 provided in the above is detected.

Then, the obtained detected temperature is compared with, for example, a preset target temperature, and a control element that affects the resin state based on the comparison deviation, such as a material supply amount in the material supply mechanism 6 and a plurality of heating cylinders 3 The heating temperature of the heating zone, the heating temperature of the material supply mechanism 6, the rotation speed of the screw 2, and / or the back pressure are varied, and each control element is sequentially controlled according to a preset priority order so as to obtain an optimum resin state. .

〔Example〕

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

First, the configuration of a vent type injection molding machine and a control system therefor capable of implementing the control method according to the present invention will be described with reference to FIGS. 1 and 3.

Reference numeral 1 denotes a vent-type injection molding machine, which is an injection device 1s excluding the mold side. The injection device 1s includes a heating cylinder 3 having an injection nozzle 11 at the front end, and the heating cylinder 3 has a screw 2 whose rotation control and forward / backward movement control are performed by a screw drive mechanism portion 12 provided at the rear end thereof. Further, a vent hole 4 is provided at an axially intermediate position of the heating cylinder 3 and above the heating cylinder 3.
The vent hole 4 allows communication between the inside and outside of the heating cylinder 3,
The water vapor and gas components generated from the resin plasticized by the rotation of the screw 2 are discharged to the outside. Furthermore, as shown in FIG. 3, the heating cylinder 3 has a plurality of heating zones divided into front and rear five, that is, from the front to the secondary front side heating zone F2,
A secondary rear heating zone R2, a vent hole heating zone V, a primary front heating zone F1, a primary rear heating zone R1 are provided,
A band heater 1 corresponding to the position of each heating zone F2 to R1 is provided on the outer circumference of the heating cylinder 3 in each heating zone F2 to R1.
Install 3a, 13b, 13c, 13d, 13e. On the other hand, a material supply mechanism 6 is provided at the rear of the heating cylinder 3. The material supply mechanism 6 includes a supply pipe 14 that communicates with the inside of the heating cylinder 3.
And a hopper 15 communicating with the supply pipe 14, a transfer screw 16a provided below the hopper 15, and a transfer screw drive unit 16b for rotationally controlling the screw 16a.
And a band heater 17a for heating the supply pipe 14 are provided on the outer circumference of the supply pipe 14.

In addition, a non-contact type temperature sensor 5 is installed near the vent hole 4 to detect the resin temperature in the vent hole 4.

Then, the temperature sensor 5 is connected to the calculation unit 22, and the calculation unit 22 is further connected to the controller 23.

On the other hand, at the positions corresponding to the heating zones F2 to R1 in the heating cylinder 3, there are temperature sensors 24a, 2a for detecting the heating temperature.
4b, 24c ... Are attached and the output side thereof is connected to the controller 23. Further, the controller 23 is also connected to the band heaters 13a, 17a, 17a, the screw drive mechanism section 12, and the transfer screw drive section 16b.

Next, a control method of the vent type injection molding machine according to the present invention will be described with reference to FIGS. 1 to 3.

First, during a predetermined molding cycle, the resin temperature in the vent hole 4 is detected by the temperature sensor 5, and the detected temperature obtained from this is given to the calculation unit 22. The calculation unit 22 compares the detected temperature with a preset target temperature,
Based on the obtained comparison deviation, a predetermined control element, that is, the heating temperature of each heating zone in the heating cylinder 3, the material supply mechanism 6
The control information for the material supply amount, the heating temperature of the supply pipe 14, the rotation speed of the screw 2 and / or the back pressure is calculated and given to the controller 23. Therefore, the controller 23 sends a predetermined control signal to each of the band heaters 13a, 13b of the heating cylinder 3, the material supply control device 16 and the band heater 17a in the material supply mechanism 6, based on the control information.
Supply to the screw drive mechanism section 12.

By the way, in this case, the calculation unit 22 determines the control element and calculates the control amount according to the control pattern shown in FIG. That is, when the detected temperature obtained from the temperature sensor 5 is compared with the target temperature and the detected temperature is in each of the modes "higher than the target temperature" and "lower than the target temperature", corresponding to this, "a heating Increase temperature of zone RI (further F1) "," b increase temperature of heating zones R1, F1, V "," c decrease temperature of heating zones V, F1 "," d "
"Increase screw rotation speed during measurement", "e Reduce screw rotation speed during measurement", "f Increase back pressure", "Reduce g back pressure", "Increase material supply amount", "i Decrease the material supply amount "," increase the material supply temperature ",
The controller 23 provides control information for executing each control of “lowering the k material supply temperature” in accordance with the connection line and the priority order.
Given to. Thus, for example, when the temperature is “higher than the target temperature”, first, the temperatures of the heating zones V and F1 are controlled to be lowered (priority 1). If the temperature of the resin does not decrease even if this control does not improve, then the heating zone R1 is raised, and if not improved, the heating zone F1
It is controlled so as to raise the value (priority 2). In this case, the reason for raising the temperature is that frictional heat generation is considered. The control is sequentially performed according to the priority until such control is improved. In addition, after the control of all the preset control elements, if the problem does not improve even after a lapse of a predetermined time, abnormality processing, that is, control such as generation of an alarm and stop of operation is performed.

Therefore, the temperature of the resin in the heating cylinder 3 is accurately detected by utilizing the vent hole 4, and is controlled so as to reach the optimum temperature and further the optimum resin state by the arithmetic processing. The arithmetic unit 22 can also perform AI control or the like as necessary.

In addition, in FIG. 1, an imaginary device 31 and an image processing unit 32, which are indicated by imaginary lines, are provided, the inside of the vent hole 4 is imaged from the outside by the imaging device 31, and the vent hole 4 is imaged by the image processing unit 32. Detects the resin state inside, for example, the size of the resin area (resin amount), the expansion state of the resin when the screw is stopped, and so on, and based on the detected resin state, each control that affects the resin state The elements may be similarly variably controlled. Furthermore, the heating cylinder 3 and the material supply mechanism 6 are controlled by the temperature sensor 33 indicated by a virtual line.
It is also possible to detect the temperature state near the communication port, that is, near the material dropping port of the heating cylinder 3, and similarly variably control various control elements that influence the resin state based on the detected temperature state.
If these controls are combined as required, more accurate and accurate control can be performed.

Although the embodiments have been described in detail above, the present invention is not limited to such embodiments. For example, although the aspect of the detected resin temperature is higher or lower than the target temperature, the temperature change, that is, the rate of temperature increase or the rate of temperature decrease per unit time may be detected. Further, as the control element, various control elements other than the illustrated ones can be added. Furthermore, in controlling, the resin temperature may be displayed and the control element may be manually operated in accordance with this. In addition, the detailed configuration, method, and the like can be arbitrarily changed without departing from the scope of the present invention.

〔The invention's effect〕

The control method of the vent-type injection molding machine according to the present invention, when controlling the vent-type injection molding machine in which the vent hole is provided in the middle part of the heating cylinder containing the screw, the resin state in the iron-added cylinder is set in advance. The priority sequence is set for multiple control elements that affect it, and the resin temperature inside the vent hole is detected during the molding cycle, and based on the detected resin temperature, multiple control elements are sequentially variable according to the priority order. As a result, the following remarkable effects are achieved.

Since the resin temperature in the heating cylinder can be detected accurately and promptly, the optimum resin temperature and the optimum resin state can be set easily and surely, and the molding quality can be improved.

Since the optimal resin state is automatically set, labor saving and productivity improvement can be achieved.

[Brief description of drawings]

1 is a block system diagram showing a control system of an injection molding machine capable of implementing the control method according to the present invention; FIG. 2 is a pattern diagram showing an example of a control pattern of a calculation unit in the control system; FIG. FIG. 3 is a schematic view clearly showing a heating zone of a heating cylinder in the injection molding machine. In the drawings, 1: injection molding machine, 2: screw 3: heating tube, 4: vent hole 5: temperature sensor, 6: material supply mechanism

Claims (4)

[Claims] 1. A control method for a vent type injection molding machine comprising a vent hole provided in an intermediate portion of a heating cylinder having a screw built therein, wherein a plurality of control elements that affect the resin state in the heating cylinder are previously set. In addition to setting the priority order, the resin temperature in the vent hole is detected during the molding cycle, and based on the detected resin temperature, multiple control elements are sequentially and variably controlled according to the priority order. Control method. 2. The method for controlling a vent type injection molding machine according to claim 1, wherein the resin temperature is detected by a non-contact type temperature sensor installed near the vent hole. 3. The control element includes two or more of the material supply amount in the material supply mechanism, the heating temperature in the heating cylinder, the heating temperature in the material supply mechanism, the rotation speed of the screw, and / or the back pressure. The method of controlling an injection molding machine according to claim 1. 4. The method for controlling an injection molding machine according to claim 3, wherein a plurality of heating zones in the heating cylinder are set as different control elements.