JPH0639119B2 - 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.

[Conventional technology]

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 condition (resin amount, resin temperature, fluidity, etc.) in the heating cylinder to the optimum condition 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.

For example, if the amount of resin, which is one of the factors of the resin state, is too large, the vent hole is clogged, so-called vent up occurs, and the function of the vent hole is lost, such as the discharge of steam and gas components is not normally performed. At the same time, it adversely affects the plasticization of the resin.

For this reason, conventionally, as a means for controlling the amount of resin, a material supply mechanism is attached to the material supply mechanism to adjust the material supply quantity.

[Problems to be Solved by the Invention]

However, it is actually difficult to accurately grasp the amount of resin in the heating cylinder transferred by the screw based on numerical values, etc. In the past, the operator (operator) used experience and The material supply amount was adjusted by intuition.

Therefore, not only can the optimum amount of material supply be set by the conventional method, but also a great deal of time and labor is spent, and it is difficult to maintain the resin state in an optimum state only by setting the amount of material supply. There was a problem.

The present invention has solved the problems existing in such conventional techniques, and provides a method for controlling a vent-type injection molding machine capable of easily and reliably setting an optimum amount of resin in a heating cylinder, and further an optimum resin state. It is intended to be provided.

[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 portion of the heating cylinder 3 having the screw 2 built therein, the inside of the vent hole 4 is controlled. While the image is taken from the outside by the image pickup device 5, the resin state inside the vent hole 4, for example, the size of the resin area and the expansion state of the resin when the screw is stopped are numerically detected by image processing, and the detected resin state is detected. Based on the above, control elements that affect the resin state, such as the material supply amount in the material supply mechanism 6, the heating temperature in the heating cylinder 3, the heating temperature in the material supply mechanism 6, the rotation speed and / or back pressure of the screw 2 and the like. Is variably controlled. In this case, it is possible to set priorities for a plurality of control elements and control them sequentially according to the priorities.

[Work]

According to the method for controlling the vent type injection molding machine 1 according to the present invention, the vent hole 4 provided in the heating cylinder 3 is externally provided with the imaging device 5.
To image the resin state appearing in the vent hole 4.

Then, the obtained image is subjected to image processing, for example, binarization so that the resin region can be discriminated, and thereby, the size of the resin area in the vent hole 4, the expansion state of the resin when the screw is stopped, etc. are digitized and detected. .

The digitized resin state is compared with, for example, a preset reference value, and based on this comparison deviation, a control element that influences the resin state, for example, the material supply amount in the material supply mechanism 6, the heating temperature in the heating cylinder 3, The heating temperature in the material supply mechanism 6, the number of revolutions of the screw 2, and / or the back pressure are varied, and the respective control elements are sequentially controlled in accordance with a preset priority order so that the optimum resin state is achieved.

〔Example〕

Hereinafter, preferred embodiments according to 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 and melted by the rotation of the screw 2 are discharged to the outside. Furthermore, band heaters 13a, 13b, 13c, ... Which heat the heating cylinder 3 are attached to the outer periphery of the heating cylinder 3 for each heating zone, and a material supply mechanism 6 is provided at the rear part 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 1 that communicates with the supply pipe 14.
5 and a transfer screw 1 provided below the hopper 15.
6a and a material supply control device 16 including a transfer screw drive unit 16b for controlling the rotation of the screw 16a, and band heaters 17a, 17b, ... For heating the supply pipe 14 are provided on the outer periphery of the supply pipe 14.

An image pickup device (video camera) is provided near the vent hole 4.
5 is installed so that the resin inside the vent hole 4 can be imaged from the outside. In this case, in consideration of securing the installation place of the image pickup device 5, protection, etc., as shown in FIG. 3, a reflecting mirror 18 is provided above the vent hole 4 in the axial direction.
An image reflected by 8 may be captured.

Then, the imaging device 5 is connected to the image processing unit 21, the image processing unit 21 is connected to the arithmetic unit 22, and the arithmetic unit 22 is connected to the controller 23.

On the other hand, temperature sensors 24a, 24b, 24c ... Which detect the heating temperature of each heating zone are attached to a predetermined position of the heating cylinder 3, and the output side thereof is connected to the controller 23. Further, the controller 23 includes the band heater 13
.., 17a .., the screw drive mechanism unit 12, and the transfer screw drive unit 16b are also connected.

Next, a control method of the vent type injection molding machine 1 according to the present invention will be described with reference to FIG. 1, FIG. 2, FIG. 4 and FIG.

First, at the end of the weighing process or the weighing, the inside of the vent hole 4 is imaged by the imaging device 5. FIGS. 4 (a) and 5 (a) are examples of images obtained from the imaging device 5. FIG. 4 (a) shows a normal state, and FIG. 5 (a) shows an excessive resin state. At the same time, the lattice pattern part F is screw 2,
The white portion W indicates resin. 4 (b) and 5 (b) show vertical cross sections near the vent hole 4 in the heating cylinder 3 corresponding to FIGS. 4 (a) and 5 (a), respectively.

On the other hand, the image is sent to the image processing unit 21 and subjected to image processing. In this case, as the image location, for example, the image is binarized by a threshold value, a predetermined window is set, and the number of pixels of white dots (resin) in the window is counted to quantify the resin amount, Alternatively, the windows are set at a plurality of different positions, and the amount of resin in each window is similarly quantified, and the change over time when the screw is stopped is detected to determine the expansion state of the resin, that is, the expansion direction (moving direction). ) And the amount of expansion.

The arithmetic unit 22 gives the resin state such as the amount of resin and the expanded state of the resin which are digitized by the image processing. The calculation unit 22 compares a preset reference value or a reference shape pattern with a digitized resin state, and based on the obtained comparison deviation, a predetermined control element, that is, the heating temperature of the heating cylinder 3, the material supply mechanism. Control information for the material supply amount 6 and 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 the band heaters 13a, 13b of the heating cylinder 3, the material supply control device 16 in the material supply mechanism 6, and the band heater 1 based on the control information.
7a ..., 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, comparing the digitized resin state with a reference value or the like, "the resin amount is small", "the resin amount varies",
"A large amount of resin", "The resin expands from the front", "
When the resin expands from the rear side, correspondingly, "a heating cylinder (rear side) temperature is raised", "b heating cylinder (front side) temperature is raised", "c" is increased. "Increasing the screw rotation speed for metering, etc.", "d Decreasing the screw rotation speed during measurement", "e increasing the back pressure", "f decreasing the back pressure", "g"
Controlling "increasing the material supply amount", "h decreasing the material supply amount", "i decreasing the material supply temperature", and "j increasing the material supply temperature" according to the connection line and priority in the figure. The control information for doing so is added to the controller 23. The "resin expands" is a phenomenon that occurs when the resin contains a gas component that is not released when the screw 2 is stopped. Thus, for example, in the case of an excessive resin state (“the amount of resin is large”) as shown in FIGS. 5A and 5B, first, the temperature of the heating cylinder 3 is controlled to be lowered (priority order). 1). Further, if there is a large amount of resin without being improved by this control, next, control is performed so as to reduce the material supply amount (priority order 2). Such control is sequentially performed according to the priority order until it 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 resin state in the heating cylinder 3 is accurately detected by the image processing, and is controlled to be the optimum state by the arithmetic processing. In addition, in the calculation unit 22, if necessary, A
It is also possible to perform I control or the like.

Although the embodiments have been described in detail above, the present invention is not limited to such embodiments. For example, the resin state to be detected can include modes other than those illustrated, and the control element can also include various control elements other than those illustrated. Further, at the time of control, the detection result of the resin state may be displayed, and the control element may be manually operated according to the result. 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〕

As described above, the control method of the vent-type injection molding machine according to the present invention captures an image of the inside of the vent hole from the outside by the image pickup device 5 and detects the resin state inside the vent hole by digitizing the image by image processing, Since the control element that influences the resin state is variably controlled based on the detected resin state, the following remarkable effects are achieved.

Since the resin state in the heating cylinder can be detected accurately and promptly, the optimum resin state can be set easily and surely, exhaust failure from the vent hole can be prevented, and 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. Schematic diagram showing an installation example of the image pickup device used in the control method, FIGS. 4 (a), (b), FIG. 5 (a), and (b): Corresponding to an image diagram inside the vent hole obtained from the image pickup device The longitudinal cross-sectional view of a heating cylinder. In the drawings, 1: injection molding machine, 2: screw 3: heating cylinder, 4: vent hole 5: imaging device, 6: material supply mechanism

Claims (8)

[Claims] 1. A method of controlling a vent-type injection molding machine, comprising a heating cylinder containing a screw and a vent hole provided in an intermediate portion of the heating cylinder.
In addition, the vent-type injection molding machine is characterized in that the resin state inside the vent hole is digitized and detected by image processing, and based on the detected resin state, control elements that affect the resin state are variably controlled. Control method. 2. The method for controlling a vent type injection molding machine according to claim 1, wherein the resin state is the size of the resin area. 3. The method of controlling an injection molding machine according to claim 1, wherein the resin state is an expanded state of the resin when the screw is stopped. 4. The control method for an injection molding machine according to claim 1, wherein priorities are set for a plurality of control elements, and the control is sequentially performed according to the priorities. 5. The method of controlling an injection molding machine according to claim 1, wherein the control element is a material supply amount in the material supply mechanism. 6. The method of controlling an injection molding machine according to claim 1, wherein the control element is a heating temperature in the heating cylinder. 7. The method of controlling an injection molding machine according to claim 1, wherein the control element is a heating temperature in the material supply mechanism. 8. The control method for an injection molding machine according to claim 1, wherein the control element is a screw rotation speed and / or back pressure.