JPH0329577B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for setting molding conditions for an injection molding machine, which is suitable for use in setting molding conditions in a speed control region during a molding cycle.

[Prior art and its problems]

In general, injection molding machines perform molding by repeating a predetermined molding cycle, and at this time, the operating state during the molding cycle is detected for the purpose of checking the operating state, confirming the quality of the molded product, finding the optimal molding conditions, etc. ing.

The conventional detection method detects the speed and pressure at fixed intervals (for example, 20 msec (total injection time: 5.5 sec)), and uses each detected data to inform the injection molding machine of the state that changes over time. The information was displayed graphically on an attached display or recorded using a printer, etc. In other words, the operating state was detected using time as a variable. FIG. 5 shows the change characteristics of injection speed, injection pressure, and mold internal pressure during the injection process detected by the conventional detection method.

However, since such conventional detection methods use time as a variable, there is a problem in that it is not possible to search for optimal molding conditions.

That is, in general, when controlling the injection process,
The injection speed is set low until the resin material passes through the gate of the mold to prevent jetting and flow marks, and the injection speed is set high when filling the mold cavity. However, when trying to set molding conditions based on conventional detection methods, time becomes a variable, so pressure rises (shift position) for a mold with an unknown mold structure.
Even if you try to find it, you can only find out how many seconds after the injection starts. Therefore, in order to set the start-up as the shift position, the shift position must be found by experience and intuition, or by calculation from the injection speed and time, which makes it difficult to obtain an accurate shift position and takes time and effort when setting. There are some problems that make it difficult to use, such as the cost.

[Means for Solving the Problems] The present invention aims to provide a method for setting molding conditions in an injection molding machine that solves the problems existing in the prior art described above. When setting molding conditions in region Zv, operate under certain molding conditions (single set values for speed, pressure, etc.), and set physical quantities related to the operation state using position as a variable, such as speed and/or The present invention is characterized in that the pressure is detected and the change characteristics of the physical quantity with respect to position are obtained, and the molding conditions are set based on the change point determined from the change characteristics.

[Effect]

Next, the operation of the present invention will be explained.

The molding condition setting method according to the present invention is in the speed control region.
In Zv, attention is paid to the fact that the controlled object moves through a predetermined stroke, and an optimal number of detection points are set within the stroke using the position as a variable. Then, it is possible to obtain the change characteristics of the operating state using the position as a variable, and from this change characteristic, the speed change position etc. can be directly read, and by comparing it with the shape pattern of the mold etc., the molding conditions can be set.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings. Fig. 1 is a characteristic diagram of each part corresponding to the screw position for explaining the molding condition setting method according to the present invention; Fig. 2 is a side view of an injection molding machine equipped with an operating state detection device capable of implementing the method of the present invention; FIG. 3 is a characteristic diagram of changes in physical quantities in the injection process, and FIG. 4 is a characteristic diagram of changes in physical quantities in the pressure control region.

First, the schematic configuration of an operating state detection device and an injection molding machine that can carry out the method of the present invention will be described with reference to FIG. 2.

The injection molding machine indicated by reference numeral 1 in the figure is roughly divided into a machine stand 2, a direct pressure mold clamping device 3 installed on this machine stand 2, a movable mold 4a and a fixed mold attached to the mold mounting surface of this mold clamping device 3. 4b, and an in-line screw type injection device 5 installed on a machine stand 2, these constitute a known injection molding machine.
Further, the machine base 2 has a built-in molding machine controller 6 and is equipped with an operating state detection device 20 for implementing the method of the present invention.

Next, the operating state detection device 20 will be explained. First, the mold clamping device 3 is provided with a mold clamping pressure detector 21 for detecting hydraulic pressure during mold clamping, and a movable platen position detector 22 for detecting the position of the movable platen to which the movable mold 4a is attached. The mold 4 also includes an in-mold resin temperature detector 23 that detects the temperature of the resin injected into the mold cavity, an in-mold pressure detector 24 that detects the resin pressure in the mold cavity, and an in-mold resin temperature detector 24 that detects the resin pressure in the mold cavity. A mold temperature detector 25 is attached. Furthermore, the injection device 5 is provided with a heating cylinder temperature detector 26 for detecting the temperature of the heating cylinder, a screw position detector 27 for detecting the screw position, and an injection pressure detector 28 for detecting the hydraulic pressure during injection.

Each of these detectors 21 to 28 is converted, corrected, amplified, and A/D (analog-digital) as necessary.
It is connected to a slave CPU 37 via amplifiers 29 to 36 having functions such as conversion. Also, slave
The CPU 37 is connected to the main CPU 39 via the RAM 38, and the main CPU 39 is further connected to the display device 4.
0, external storage device 41, detection position interval setter 4
2. Connect the detection time interval setting sections 43 and the molding machine controller 6.

Next, a method for setting molding conditions according to the present invention will be explained using an injection process that is a part of a molding cycle as an example. During the injection process, the screw moves forward,
It consists of a speed control area Zv in which the resin material accumulated in front of the mold cavity is filled into the mold cavity, and a pressure control area Zp in which a predetermined holding pressure is applied when the filling is completed and the screw is almost stopped.

First, in the speed control region Zv, the position is set as a variable. In other words, the distance Lo between each detection point
is set by the detection position interval setter 42, and time is set as a variable in the pressure control region. The time To between each detection point is set by the detection time interval setter 43. Each setting device 42, 43
The conditions set in , detection items (injection speed, injection pressure, mold internal pressure), etc. are sent from the main CPU 39 to the RAM 38.
is sent to the slave CPU 37 via.

Now, when an injection start signal is given to the main CPU 39 from the molding machine controller 6, this injection start signal is sent to the slave CPU 37 via the RAM 38, and the slave CPU 37 starts detection. At this time, the timer built into the slave CPU 37 starts measuring time. At the same time, when the screw starts moving forward and the screw moves forward by the distance Lo set in the detection position interval setting device 42, the injection speed, injection pressure, mold internal pressure and time are detected at this detection point and the speed control area is set. Each data in is stored in RAM38. Note that the injection speed is determined by differentiating the screw position with respect to time. Then, as the screw moves forward, it detects data at detection points every distance Lo set by the setting device 42 and writes the data to the RAM 38. RAM
The data written in 38 is sent to the main CPU 39, and after predetermined calculations are performed, it is displayed in real time on the display device 40 in a graph format as shown in FIG. 3 or in a list format using digital values, etc. Is displayed. In addition, Figure 3 shows the injection stroke.
4 molded products of 75mm (80~5mm) and injection time of 5.5 seconds.
This is a graphical representation of the case where molding was performed by speed 3-pressure process control, and the detection points in the speed control area Zv were set every 0.2 mm from the injection start position.

By the way, in the speed control region Zv, since the operating state is detected using the position as a variable, the speed change point when setting the optimum molding conditions can also be easily selected. First, FIG. 1a shows the change characteristics of the injection pressure obtained by molding a mold with unknown molding conditions at a single speed and a single pressure. Note that the characteristics shown in FIG. 1A do not have burrs or shots, but they do have jetting and internal stress. on the other hand,
Assuming that the shapes of the molded product 45 and the runner branch 46 are formed as shown in Figure b, a comparison of Figures a and b shows that the rise in pressure (shift point) exists at points B and C. It will be done. Point B is the point where the resin is squeezed as it passes through the gate and the pressure rises, and point C is the point where the pressure rises because the mold cavity is filled with resin. Therefore,
The process can be controlled as shown in FIG. 3C using point B and point C as switching positions, thereby obtaining optimal molding conditions that can reduce the initial speed and eliminate internal stress due to overfilling. Note that since these points B and C appear as position information of the screw on the change characteristic (a in the same figure), these positions can be used as the set positions as they are. Furthermore, if the shift point is difficult to determine, it can be easily confirmed by first or second order differentiation of the pressure data depending on the position.

On the other hand, the screw position changes from the speed control area Zv set in the molding machine controller 6 to the pressure control area Zp.
When the speed and pressure switching position is reached, the molding machine controller 6 outputs a command signal therefor, and the molding machine moves to the pressure control region Zp. pressure control area
In Zp, the time set in the detection time interval setting device 43
The screw position, time, injection speed, and mold pressure are repeatedly detected every time To elapses, and the detected data is
Store in RAM38. In the pressure control region Zp, the inside of the mold cavity is filled with resin, and the screw hardly moves forward, but some displacement occurs to compensate for cooling shrinkage. Each data in the pressure control area Zp is also displayed on the display device 40 in the same way as in the speed control area Zv (FIG. 3). Note that the detection points in the pressure control region Zp are set every 20 msec from the pressure control switching position (position 5 mm in FIG. 3).

After passing through each of the above regions Zv and Zp, the detection stops when a command signal to complete the injection process is issued from the molding machine controller 6, and the data stored in the RAM 38 is stored in an external storage device 4 such as a floppy disk or a fixed disk.
1 and the RAM 38 is initialized.

On the other hand, in the pressure control region Zp, time is detected as a variable, but pressure may be detected as a variable as shown in FIG. In other words, pressure sensors are usually attached to injection cylinders, mold cavities, etc., but based on the detection results of this pressure sensor, a certain pressure can be determined.
A detection point may be set for each Po, and a physical quantity related to the operating state may be detected at that point. This makes it possible to obtain more accurate and accurate change characteristics.

Although the embodiments have been described in detail above, the present invention is not limited to these embodiments.
For example, although the injection process has been described as an example, the present invention can be applied to any process including a mold clamping process. Moreover, the physical quantity related to the operating state may be mold temperature, resin temperature in the mold, heating cylinder temperature, etc. Other detailed configurations, methods, etc. may be modified as desired without departing from the gist of the present invention.

〔Effect of the invention〕

As described above, the method for setting molding conditions for an injection molding machine according to the present invention, when setting the molding conditions in the speed control region during the molding cycle, causes the operation to be performed under constant molding conditions and sets the operation state using the position as a variable. In addition to detecting the related physical quantities, the change characteristics of the physical quantities with respect to position are obtained, and the molding conditions are set based on the change point determined from the change characteristics, so the operating state of the speed control area can be detected with high accuracy. Exploration of optimal molding conditions,
In particular, it is possible to easily and accurately set change points such as a shift point and a pressure change point. Furthermore, since the necessary and optimal detection points can be set, an appropriate storage capacity is sufficient for the storage device, contributing to miniaturization and cost reduction of the device.

[Brief explanation of the drawing]

Figure 1: Figure 1 is a characteristic diagram of each part corresponding to the screw position to explain the molding condition setting method according to the present invention, Figure 2: Injection molding equipped with an operating state detection device that can implement the method of the present invention Side view of the machine, 3rd
Figure: Characteristic diagram of changes in physical quantities during the injection process, 4th
Figure: Characteristic diagram of changes in physical quantities in the pressure control region,
FIG. 5: A characteristic diagram of changes in physical quantities related to operating states detected by a conventional method. In the drawing, Zv: Speed control area.

Claims (1)

[Claims] 1. When setting molding conditions in a speed control region during a molding cycle, operation is performed under certain molding conditions, physical quantities related to the operating state are detected using position as a variable, and physical quantities related to position are detected. 1. A method for setting molding conditions for an injection molding machine, comprising: obtaining change characteristics, and setting molding conditions based on a change point determined from the change characteristics. 2. A method for setting molding conditions for an injection molding machine according to claim 1, wherein the physical quantities are speed and/or pressure.