JPS63209919A - Method for molding of injection molder - Google Patents

Abstract

PURPOSE:To ensure the molding setting conditions, simplify operation and consequently contrive to reduce the molding cost by a method wherein the molding conditions are corrected by detecting the response deviation between measured data and set data by preliminary injection. CONSTITUTION:A preliminary injection is done so as to detect the advancing positions of a screw 2 with a positional sensor. Values, which are detected continuously, are processed as the time variables by the interior timer of an arithmetic processing unit 14. Detected positional and time data are stored in a memory in the arithmetic processing unit 14. When the response lag in the speed with respect to the advancing position of the screw 2 develops as the measured data shown by dotted lines with respect to the set data shown by solid lines, the lag is calculated in the arithmetic processing unit 14 and shown on a display 16 so as to set the optimum molding conditions for a molding. By correcting the position of the screw and injection speed, which are necessary for molding, the correct injection speed is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a molding method for an injection molding machine that can be used for setting molding conditions, etc.

[Conventional technology]

Generally, in a speed control region in a molding process of an injection molding machine, for example, an injection process of an in-line screw type injection molding machine, injection process control is performed by setting the injection speed of a screw (injection plunger) in multiple stages. That is, a plurality of shift points are set in advance in the stroke range of the screw, and different injection speeds are set between each shift point. and,
During molding, the forward position of the screw is detected by a position sensor, and when the speed change point is reached, a control signal is given to the screw drive device to control switching to a predetermined speed.

Incidentally, in an injection molding machine, a necessary response delay occurs due to the presence of an electric circuit of a control system, a hydraulic circuit of a drive system, and an injection mechanism (screw weight, etc.). Therefore, even if accurate molding conditions are set in advance, the actual operation does not match the set conditions, and there is a problem that the forward position of the screw deviates from the normal position.

For this reason, in the past, operators had to rely on their experience and intuition, take into account response delays, and set molding conditions by trial and error while checking the molded product.

[Problem that the invention seeks to solve]

However, with this method of setting molding conditions, it is difficult to find a relationship between the molding conditions and the corresponding molded product.
In addition, it is not possible to perform reliable settings and corrections, and it is also difficult to investigate the cause of molding defects.

Further, the setting work is extremely disadvantageous in terms of time, labor, efficiency, etc., and there are also problems that involve wasted materials and energy consumption.

Furthermore, if the interval between the shift points is short and the speed change is large, the next shift point will be reached before the specified speed is reached due to response delay, and the molded product will not be able to perform the original control. This resulted in defects, and there were limits to methods that relied on the operator's experience.

5. How the actual speed affects the setting conditions can be measured by connecting various measuring instruments (X-Y recorders, etc.), but this is difficult and ultimately makes it difficult to judge. It is difficult to adopt this method in molding factories that mold a wide variety of molded products and must rely on operators.

[Means for solving problems]

The present invention aims to provide a molding method for an injection molding machine that solves the problems existing in the above-mentioned prior art, and is achieved by the molding method shown below.

That is, in the molding method of the injection molding machine according to the present invention, for example, a speed condition having at least one shift point xO is set in the speed control region of the injection molding machine 1, preliminary injection is performed, and actual measurement data based on this preliminary injection is performed. Detecting a response delay from setting data, and equating this response delay to a predetermined function consisting of a constant region and a function change region with respect to time,
This predetermined function is defined as a delay detection function specific to the injection molding machine.
It is characterized in that it is used for correction of molding conditions, etc. Note that the same process can be performed in the pressure control region as well.

[For production]

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

The molding method of the injection molding machine according to the present invention performs preliminary injection using a method that can clearly detect response delay before setting the original molding conditions.

Then, the response delay of the injection molding machine 1 is detected by preliminary injection, and the constant region and function change region for time, which is a predetermined function, are made equal to each other. The response delay is regarded as a delay detection function specific to the injection molding machine, and is used for correction when setting molding conditions, analysis of defective molded products, etc.

〔Example〕

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

Fig. 1 is a relationship diagram of screw position versus injection speed showing setting data and actual measurement data of preliminary injection conditions used in the molding method of the injection molding machine according to the present invention, and Fig. 2 shows an equivalent delay detection function using the same method. Fig. 3 is an explanatory diagram of a method for equalizing response delay using the same method; Fig. 4 is a relational diagram of screw position versus injection speed showing predicted execution data corrected by the same method; FIG. 5 is a block diagram of an injection molding machine suitable for use in the same method.

First, in order to clarify the present invention, the overall schematic configuration of the in-line screw type injection molding machine illustrated in FIG. 5 will be described.

The injection molding machine 1 has a heating cylinder 4 in the front part into which a screw 2 is inserted and has an injection nozzle 3 at the front end of the cylinder.

Further, the rear part is provided with an injection cylinder 6 into which a ram 5 coupled to the rear end of the screw 2 is inserted, and an oil motor 7 for rotating this ram 5.

Next, the configuration of a control system that can implement the method of the present invention will be described. First, the rear side oil chamber 5r of the injection cylinder 5 is connected to a hydraulic pressure source 9 via a control device 8 consisting of an electromagnetic proportional flow valve, an electromagnetic proportional pressure valve, an electromagnetic directional switching valve, and the like. This control device 8 is controlled by a sequence controller 1o to which a predetermined setter group is connected. On the other hand, the rear end of the screw 2 is provided with a protrusion 11 that follows the forward and backward movement of the screw 2,
The position of this moving protrusion 11 is detected by a position sensor 12 using a linear encoder, rotary encoder, potentiometer, or the like. It also includes an arithmetic processing device 14, to which the position sensor 12 is connected via an amplifier 13, and a display device 16 using the sequence controller lO1 preliminary injection speed setting device 15, CRT, plasma display, etc. Connect.

Next, the molding direction of the injection molding machine according to the present invention will be explained.

First, perform preliminary injection. In the preliminary injection, at least one shift point xO is set as shown in FIG. 1, and the preliminary injection conditions for decelerating from the speed V to the speed V by moving the shift point do. Note that the mold is separated from the injection nozzle 3 and injection is performed by blank firing. In this way, when the mold is separated from the injection nozzle 3, versatile basic data can be collected, and on the other hand, when the mold is received by the injection nozzle 3, data including the mold can be collected.

During preliminary injection, the forward position of the screw 2 is determined by the position sensor 1.
2, and is also detected as a time variable by the internal timer of the arithmetic processing unit 14. Then, the detected position data and time data are stored in a memory within the arithmetic processing unit 14, and further, velocity data is obtained by calculation of the position data and time data, and is similarly stored in the memory.

The speed relative to the forward position of the screw 2 is as shown in FIG. 1, and the measured data is shown as a dotted line due to a predetermined response delay compared to the setting data shown as a solid line.

As described above, there is an inherent response delay determined by the injection molding machine 1 from when the speed is changed to the speed change point xO until the speed V is reached. This response delay is caused by the shift point X0 (
A constant region in which the speed v1 before switching is maintained only during the time L (dead time) from tO) to tl, and a constant region in which the speed v1 before switching is maintained only during the time L (dead time) from tO) to tl;
It can be equivalent to a function consisting of a function change region from tl to t2, which reaches .

As a result of experiments with many different speed change differences, it was confirmed that this time period and T are constant for each injection molding machine regardless of the speed change difference, and can be regarded as a delay function inherent to the injection molding machine. It was also confirmed that there is no practical problem in approximating the function change region to the step response of a first-order lag system.

Next, analyze the specific delay function.

Now, the time to when switching the injection speed from vI to v2
If the injection speed t seconds after is V(t), then when t<L, V(t)=V,...
(1) When L≦T, V(t)=L+(Vt−Vυ(1++ e −(t −
L ) / T ) ・,・(2) The screw position X after seconds is x=+: V(t)dt ”I'o Ldt+I”L V(t)dt=VtL
+(Vt-, Vt) ((t-L)-T(1-e-"-
"")"Vl(t-L) = L t+(Vt-L) ((t-L)-T(1-e
−”−” ”)) ・= (3)

Also, equation (2) is V(t)-V.

It can be transformed as 1-e V t -Vt, and equation (4) represents a straight line with time as the horizontal axis, intercept L/T, and slope -1/T.

Therefore, in the arithmetic processing unit 14, time data, speed data, speed setting values, T, and L obtained during preliminary injection are determined.

Once T and L are determined, the injection speed V(t) after an arbitrary time in seconds can be determined from equation (2), and the screw position X can be obtained by integrating the speed over time using equation (3). The injection speed for can be determined by calculation.

Therefore, the shift points x1 to X4 and the sequence controller lO under the setting conditions used for actual molding as shown in FIG.
Injection speed V l set by a setter group connected to
-V s is read into the arithmetic processing unit 14 and arithmetic is performed using the above function to obtain expected execution data for the setting conditions. This can be displayed as a waveform on the display bag device 16 together with the setting data. These calculations can be performed in the same way every time the settings of the speed change point and injection speed are changed, and the waveform display is also changed accordingly, so the operator can check the optimal molding conditions for the molded product while looking at the waveform display. can be set.

On the other hand, by specifying coordinates using a cursor or numeric keypad from the predicted execution data displayed on the display device I6, it is possible to specify the screw position and injection speed necessary for molding. As a result, the original injection speed can be obtained at the specified point, and the speed change point and injection speed can be set corrected by the unique delay detection function.

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

For example, although the equivalent function is expressed as a constant region and a function region of a first-order lag system, if the constant region is extremely short, it may be ignored, or other functions such as a second-order lag system may be used. good. Further, although one shift point is set, more reliable data can be obtained by setting two or more with different conditions if necessary and averaging them. Furthermore, although the injection speed has been described, a unique delay detection function can be detected for the injection pressure in a similar manner, and the present invention can be similarly applied to other injection molding machines such as a plunger type. 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 molding method of the injection molding machine according to the present invention detects the response delay by performing preliminary injection under predetermined conditions, and this result can be used equivalently to an easy-to-handle function. get an effect like

■ There is no variation between operators, and it can be used as objective data in the following ways, contributing to high-quality molding and improved work efficiency.

(a) Accurate if used to correct conditions when setting molding conditions.
In addition, it is possible to perform reliable settings, and the setting work can be performed easily and quickly.

(b) Since the state of response delay can be easily grasped, even if unfeasible molding conditions are set, it can be easily determined, so that the cause of defective molded products can be accurately and easily investigated.

■ Inherent delay conditions can be detected through preliminary injection without actual molding, so there is no wasted material or energy loss.

[Brief explanation of the drawing]

Fig. 1: A diagram showing the relationship between the screw position and injection speed, showing setting data and actual measurement data of preliminary injection conditions used in the molding method of the injection molding machine according to the present invention; Fig. 2: Time showing the equivalent delay detection function by the same method. Figure 3: A diagram showing the relationship between the screw position and the injection speed, Figure 3: An explanatory diagram of the method for equalizing the response delay using the same method, Figure 4: A diagram showing the relationship between the screw position and the injection speed, showing correction of predicted execution data made using the same method, Figure 5: Figure: A configuration diagram of an injection molding machine suitable for use in the same method. In the drawings, 1: Injection molding machine XO: Speed change point patent applicant
Nissei Jushi Kogyo Co., Ltd. Patent Attorney 2 1) Shigeru Figure 1 (to) Figure 2 (XO) Figure 3 Figure 4 Commissioner of the Japan Patent Office Kuro, March 27, 1986 1) Yu Akira 3, amendment Relationship with the case of a person who does It is written from page 9, line 19 to page 10, line 4 of the description of contents [Also, in equation (2)..., time t and J are corrected as follows. “Also, equation (2) is

Claims (1)

[Scope of Claims] [1] Preliminary injection is performed by setting speed conditions and/or pressure conditions having at least one speed change point and/or pressure change point, and response delay is determined based on actual measurement data and set data based on the preliminary injection. An injection molding method for an injection molding machine, characterized in that the response delay is equalized to a predetermined function and used as a delay detection function specific to the injection molding machine. [2] The molding method for an injection molding machine according to claim 1, wherein the predetermined function includes a constant region and a function changing region with respect to time. [3] A molding method for an injection molding machine according to claim 1, wherein molding conditions are corrected using the delay detection function.