JPH09174637A - Injection molding machine and its metering condition setting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To monitor and contemplate by using a measured graphic data of a screw torque so as to control optimally by detecting a torque of an electric servo motor used as a rotation drive source of a screw and displaying a measured torque in a metering process by a graphic. SOLUTION: A molding process control section 13 of a microcomputer 1 controls a metering process at a metering process control section 13a based on a molding process control program and a drive condition value stored in a molding condition setting memory section 12. By measured information from a motor torque sensor 2a, a measured value of torque of a servo motor 21 for screw rotation is fetched by a measured value memory section 14 and stored in a motor torque measured value storing section 14a. A display processing section 15 extracts a data to be used for display of a display mode screen from the information stored in the molding condition setting memory section 12 and the measured value memory section 14 by a calling command of a display screen by a key input device 4, which is sent out to a display device 5 and displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-line screw type injection molding machine and a method for setting its measuring conditions.

[0002]

2. Description of the Related Art As is well known, in an in-line screw type injection molding machine, during a measuring process (kneading, plasticizing,
During the measuring process), the screw in the heating cylinder is rotated to transfer the resin material to the tip side of the screw while kneading and plasticizing the resin material, and the screw is accumulated as the molten resin accumulates on the tip side of the screw. The back pressure is controlled and retreated by the reaction force from the resin, and the screw rotation is stopped when a predetermined amount of the molten resin is stored on the tip side of the screw.

By the way, recent injection molding machines are equipped with a microcomputer (hereinafter referred to as a microcomputer).
This microcomputer captures the operation data (operating condition actual measurement value) during the continuous molding operation, and can graphically display the operating condition actual measurement value of various strokes on a display device such as a color CRT display. The screw rotation speed, screw retreat speed, and back pressure can also be displayed graphically in the measuring process (see, for example, Japanese Patent Laid-Open Publication No. Hei-No.
We have realized an injection molding machine with excellent visibility.

[0004]

As described above, there are three items of screw speed, screw retreat speed, and back pressure as items that can be graphically displayed in the conventional injection molding machine. No consideration was given to displaying the torque graphically.

However, the load applied to the screw during the metering process changes depending on the type and condition of the resin, and the torque at the time of starting the screw also changes depending on the set temperature of each part of the heating cylinder. It is considered to be an important monitoring factor in grasping the plasticized state of the resin, but in the conventional injection molding machine, the screw torque is actually measured and not displayed graphically, so the measured screw torque graphic data Could not be considered.

Further, in the conventional in-line screw type injection molding machine, no consideration is given to the optimum control of the screw torque in the measuring process, and the limit torque of the electric servomotor for screw rotation drive is not taken into consideration. Set the value (allowable upper limit torque value) to a value that has sufficient margin, and set the electric servomotor speed (that is, the number of revolutions)
It was common to use the technique of feedback control.

However, when the above-mentioned control is performed, for example, when the screw torque becomes excessive with respect to the screw strength immediately after the screw is started due to the sticking of the resin, the screw is broken. I was afraid. In addition, in order to prevent such screw breakage, if safety is fully taken into consideration and control is performed such that the torque is gradually increased at the time of starting the screw, it becomes a factor that inhibits shortening of cycle time. It was Furthermore, the screw torque rises after the screw is started and then falls, but in the region where the screw torque is normal if the screw torque is normal (the region where the screw torque may be low if normal), In addition, if the limit torque value of the electric servomotor is too large, the limit torque value will have too much margin when the screw is overloaded in an unexpected situation. There was a problem in that the screw would be broken due to torque, which would lead to breakage of the screw.

The present invention has been made in view of the above points,
The purpose thereof is to enable monitoring and consideration using actually measured graphic data of the screw torque, and to enable optimum control of the screw torque.

[0009]

In order to achieve the above-mentioned object, an in-line screw type injection molding machine according to the present invention uses an electric servomotor as a rotational driving source of a screw and detects the torque of the electric servomotor. And is configured to graphically display the measured torque in the weighing process. Also, set the limit torque value of the electric servo motor at the time of the test shot to a value with a sufficient margin, and measure the actually measured torque of the electric servo motor at the time of the test shot,
Based on the measured torque, the limit torque value of the electric servomotor during the continuous molding operation is set.

The torque of the screw corresponds to the measured torque of the electric servomotor for rotating the screw, and the measured torque of the electric servomotor also corresponds to the motor drive current value. The measured torque of the screw can be displayed graphically by incorporating the measured value of. In this way, if the measured torque can be displayed graphically, it will be possible to analyze the resin behavior during the measuring process by referring to the graphic display of screw rotation speed, screw retreat speed, and back pressure. Be useful.
This is because a complete detailed analysis of the melting mechanism of the resin in the metering process in an in-line screw type injection molding machine is still insufficient, and the more types of monitoring factors to refer to, the more advantageous it is. .

Further, the limit torque value of the electric servo motor at the time of the test shot is set to a value having a sufficient margin, and the actually measured torque of the electric servo motor at the time of the test shot is measured,
For example, the microcomputer automatically sets the limiting torque value of the electric servo motor based on the graphic data of the actual measurement torque when the non-defective molding is performed (when the good resin is kneaded and plasticized). This will prevent the limit torque setting value from becoming larger than necessary,
In addition, since the limit torque setting value can be set in multiple steps, even if an excessive load is applied to the screw due to an unexpected situation, the screw will not be forced to rotate at high torque, and damage to the screw can be prevented. Can be restrained. Furthermore, since the torque at the time of starting the screw is regulated from increasing to the extent that it exceeds the screw strength,
Even if the resin sticks, there is no risk of screw breakage. Therefore, perform control to rapidly increase the torque when starting the screw (that is, motor control by speed feedback control that rapidly increases the screw rotation speed to the set value). Therefore, the cycle time can be shortened.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a simplified block diagram of a control system of an inline screw type injection molding machine according to an embodiment of the present invention (hereinafter referred to as this embodiment).
In FIG. 1, 1 is a microcomputer that controls the operation and display control of the entire machine (injection molding machine), 2 is a sensor group including a large number of sensors provided in each part of the machine, and 3 is each part of the machine. A driver group composed of a large number of driver circuits for driving and controlling a large number of drive sources provided, 4 is a key input device arranged on the front surface of the machine, and 5 is a portion adjacent to the key input device 4. The display device is, for example, a color CRT display or a color LCD that is installed.

In the driver group 3, 3a
Is a servo driver for a motor, which drives and controls a servo motor (electric servo motor) 21 for screw rotation. Further, in the sensor group 2, 2a is a motor torque sensor, which detects the drive torque of the servomotor 21 from the measured value of the motor drive current.

The microcomputer 1 controls the entire molding process such as measuring operation (kneading / plasticizing / measuring operation), injection operation (primary injection operation and pressure holding operation), mold opening / closing operation, ejecting operation, and actual measurement data. Various processing such as calculation / storing processing, non-defective / defective determination processing, abnormality determination processing, or the like, or display control processing of the output image of the display device 5 is executed. This microcomputer 1 actually has various I / O
Although it is configured with an interface, a ROM, a RAM, an MPU, etc., and executes various processes by various programs created in advance, in this example, an input data processing unit 11, a molding condition setting storage unit 12, a molding process The following description will be made assuming that the control unit 13, the measured value storage unit 14, the display processing unit 15 and the like are provided.

In the molding condition setting storage unit 12, reference numeral 12a is a setting data storage unit for the measuring process,
In the molding process control unit 13, 13a is a measurement process control unit, and in the measured value storage unit 14,
14a is a motor torque measured value storage unit.

The input data processing unit 11 appropriately converts various measurement information sent from the sensor group 2 and external input information such as various information input by the key input device 4 as necessary. And supplies it to each part in the microcomputer 1.

In the molding condition setting storage unit 12, various operating condition values input by the key input device 4 or the like are stored in a rewritable form. The operating condition values (operating condition setting data) include, for example, measurement control conditions, injection (primary injection and holding pressure) control conditions, mold closing (mold clamping).
Control condition, mold opening control condition, eject control condition, control condition of automatic product take-out machine, band heater temperature of each part,
Examples include the cooling temperature of each part. Further, in this example, the above-mentioned measurement control conditions correspond to the screw rotation speed corresponding to the screw position during the measurement stroke, the screw retreat speed corresponding to the screw position, the back pressure corresponding to the screw position, and the screw position. A limit torque value (allowable upper limit torque value) of the servo motor 21 is set, and setting data of these measurement control conditions is stored in the setting data storage unit 12a for the measurement process.

The molding process control unit 13 is provided in each part of the machine based on a molding process control program created in advance and operating condition values (operating condition setting data) stored in the molding condition setting storage unit 12. The driver group 3 (while referring to the measured information from the sensor group 2 (position sensor, pressure sensor, rotation speed detection sensor, torque sensor, temperature sensor, etc.) A corresponding drive source is drive-controlled via a motor driver, a hydraulic cylinder driver, a heater driver, etc.) to execute a series of molding steps. The weighing process control unit 13a controls the weighing process.

The measured value storage unit 14 stores all measured data of preset monitor items during continuous automatic operation over a continuous predetermined number of shots. The monitor items to be captured include a time monitor item, a position monitor item, a rotation speed monitor item, a speed monitor item, a pressure monitor item, a temperature monitor item, a power monitor item, and the like, and the important items of the molding operation condition setting items described above. Is almost included. In the present example, the measured torque value of the servo motor 21 for screw rotation is also loaded into the measured value storage unit 14 based on the measurement information from the motor torque sensor 2a, which is stored in the measured motor torque value storage unit. 14a.

The display processing unit 15 displays the display screen data of the designated display mode on the basis of the display image creation / control program created in advance in response to the operator's command to call the display screen of the mode desired by the key input device 4. To create.

That is, when a command for calling a predetermined display screen from the operator arrives, the display processing unit 15 causes the molding condition setting storage unit 12 and the measured value storage unit 1 to operate as necessary.
Data for use in displaying the display mode screen is extracted from the information stored in 4, and is converted into a form corresponding to the display form of the specified display mode screen. For example, when the designated display mode is an injection graphic screen, the extracted data is converted into line drawing processed image data, or the extracted data is converted into numerical image data. Further, the display processing unit 15 extracts fixed data (symbols such as characters) necessary for the screen from a display fixed data storage unit (not shown) according to the designated display mode screen type, and converts it into symbol image data. Processing etc.
Furthermore, the display processing unit 15 generates frame line data and the like required for the screen according to the designated display mode screen type, and applies color paint of a predetermined color to the inside and outside of each generated frame (color Processing). Then, the display processing unit 15 applies predetermined color processing to the above-mentioned line drawing (graphic) image data, numerical image data, symbol image data, etc., in each predetermined area of the created color paint image data, and thereby, Combine and generate screen data for display. And such a display processing unit 1
The screen data generated in 5 is transferred to a frame buffer (not shown) and temporarily stored therein, and the output of this frame buffer is sent to the display device 5 in response to a command from the display processing unit 15 to display the display screen of the display device 5. A screen desired by the operator is displayed on the screen.

Next, the graphic display screen of the measured torque of the servo motor 21 according to the present embodiment and the method of setting the limiting torque value of the servo motor 21 during the continuous molding operation will be described based on the above-mentioned configuration.

FIG. 2 is an explanatory view showing, in a simplified form, a graphic display screen of the actually measured torque in the weighing process at the time of the trial shot, which is called by the operator on the display portion 5a of the display device 5 by appropriately operating the keys. In the graphic display shown in FIG. 2, the horizontal axis represents the screw position (screw retract stroke) from the measurement start position, and the vertical axis represents the torque. Further, 31 is the measured torque data of the servo motor 21 (measured torque graphic data),
Corresponds to the actual measured torque of the screw. Further, (a) of FIG. 2 shows a graphic display screen which displays a limiting torque value at the time of trial shot, and (b) of FIG. 2 shows a graphic display screen which shows a limiting torque value at the time of continuous molding operation. .

As shown in FIG. 2A, at the time of the test shot, the limit torque value of the servomotor 21 is set to a large value (initial limit torque value) T _O with a sufficient margin, The screw rotation speed, screw backward speed,
The metering process is executed according to each set value of the back pressure, and the servo motor 21 is rotationally driven by speed (rotation speed) feedback control. Motor torque (screw torque) rises sharply after the start of metering operation (after screw start),
It decreases after a lapse of a predetermined time (that is, when the screw retracts to a predetermined position). The measured torque data 31 shown in FIG. 2A is obtained when a non-defective product is molded in the test shot (when good resin kneading / plasticization is performed).
The data is shown, and the maximum value of the actually measured torque data 31 is considerably different from the initial limit torque value T _O.

Then, the operator who confirms that the good resin kneading and plasticizing is achieved in the test shot automatically sets the limiting torque value of the servo motor 21 during the continuous molding operation by appropriately operating the keys. By instructing the microcomputer 1, the microcomputer 1 sets the limiting torque value T _A during the continuous molding operation, for example, as shown in FIG. 2B based on the measured torque data 31 in FIG. Set automatically. In the example shown in FIG. 2B, the limiting torque value T _A during the continuous forming operation is set in two stages, and the limiting torque value T _A1 is from the start position of the metering operation to point S1. The limit torque value T _A2 is from the point S1 to the position where the metering operation is completed. Each of the limiting torque values T _A1 and T _A2 is a predetermined margin value M from the torque value in the high torque region and the torque value in the low torque region of the actually measured torque data 31 when good resin kneading / plasticizing is achieved. It is set to the sum of _A1 and M _A2 . That is,
Roughly speaking, the limiting torque value T _A during the continuous molding operation is linearized in two regions by slightly increasing the actually measured torque data 31 when good resin kneading / plasticization is achieved in the test shot. It has become the data. And
The limit torque value T during continuous molding operation set in this way
_A is stored in the setting data storage unit 12a for the weighing process.

In this example, the limiting torque value T _A during the continuous molding operation is automatically set by the microcomputer 1. However, the measured torque when the good kneading / plasticization of the resin is achieved in the test shot. There is no problem even if the operator refers to the data 31 and inputs / sets the limiting torque value T _A during the continuous molding operation by a key operation or the like.

FIG. 3 is an explanatory view showing in simplified form one example of a graphic display screen of the actual measurement torque of the measuring process during the continuous molding operation, which is called by the operator on the display portion 5a of the display device 5 by an appropriate key operation. is there. In FIG. 3, 31-1 and 31-2 are measured torque data (measured torque graphic data) of the servo motor 21, and in the example shown in FIG. 3, measured torque data of two consecutive shots during continuous molding operation are An example of overwriting is shown.
The measured torque data 31-1 and 31-2 are graphic data when good resin kneading and plasticization are achieved. When such measured torque data is displayed, the operator It can be confirmed that the resin is kneaded and plasticized normally (satisfactorily).

FIG. 4 is a simplified illustration of another example of the graphic display screen of the measured torque of the measuring process during the continuous molding operation, which is called by the operator on the display portion 5a of the display device 5 by appropriately operating the keys. It is a figure. In FIG. 4, 31-3 is the measured torque data (measured torque graphic data) of the servo motor 21. This figure 4
In the example shown in, the limit torque value T _A2
In the area where the screw torque may be low under normal conditions, the measured torque data 31-3 is attached to
This indicates that some factor that tried to increase the motor torque (screw torque) worked. In such a case, the kneading / plasticization of the resin is not normal, and the microcomputer 1 determines that the molded product of this shot is defective from the measured torque data 31-3 and the measured data of the screw rotation speed. In addition, in some cases an alarm will be issued and the machine will be brought to an emergency stop. Further, the operator can determine from the display of the measured torque data 31-3 that an abnormality has occurred during the weighing process.

As described above, in this example, the measured torque of the servo motor (screw) can be displayed graphically, so that the screw torque closely related to the plasticized state of the resin can be visually recognized at a glance. I can figure it out. In addition, by referring to the graphic display of the screw rotation speed, screw retreat speed, and back pressure from the past, it is very useful for the analysis of resin behavior in the measuring process. At this time, since the measured torque is graphically displayed in a form corresponding to the screw position, it becomes easy to associate it with other operating conditions (screw rotation speed, screw retreat speed, back pressure) of the measuring stroke, It is also very useful as a judgment material for setting the operating conditions of the weighing process.

Further, the measured torque of the electric servomotor at the time of the test shot is measured, and based on the graphic data of the measured torque when the non-defective molding is performed (when the good resin kneading / plasticization is performed). Since the microcomputer automatically sets the limit torque value of the servo motor, setting of the limit torque value becomes easy and reliable. Moreover, since the limit torque setting value is not set to an unnecessarily large value, and the limit torque setting value can be set in multiple stages, even if an excessive load is applied to the screw in an unexpected situation, it is forcibly forced. Since the screw is not rotated with high torque, screw breakage can be suppressed as much as possible. Furthermore, since the torque at the time of starting the screw is restricted to increase to the extent that it exceeds the strength of the screw, there is no risk of breakage of the screw even if there is sticking of resin, so the torque is suddenly started at the time of starting the screw. The control can be performed, and the cycle time can be shortened.

[0031]

As described above, according to the present invention, it is possible to monitor and consider using measured graphic data of screw torque, and it is possible to perform optimum control of screw torque. It is a molding machine and its value is enormous.

[Brief description of the drawings]

FIG. 1 is a simplified block diagram of a control system of an inline screw type injection molding machine according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing in simplified form an example of a graphic display screen of measured torque in a weighing process in the embodiment of the present invention.

FIG. 3 is an explanatory diagram showing in simplified form an example of a graphic display screen of measured torque in a weighing process in the embodiment of the present invention.

FIG. 4 is an explanatory view showing in simplified form an example of a graphic display screen of measured torque in a weighing process in the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microcomputer 2 Sensor group 2a Motor torque sensor 3 Driver group 3a Motor servo driver 4 Key input device 5 Display device 11 Input data processing unit 12 Molding condition setting storage unit 12a Setting data storage unit for measurement process 13 Molding process control unit 13a Measuring process control unit 14 Measured value storage unit 14a Motor torque measured value storage unit 15 Display processing unit 21 Electric servo motor for screw rotation

Claims (2)

[Claims] 1. A screw in a heating cylinder is rotated to transfer the resin material to the tip side of the screw while kneading and plasticizing the resin material, storing the measured molten resin at the tip side of the screw, and advancing the screw to move the metal. In an in-line screw type injection molding machine that injects and fills molten resin into the mold, an electric servo motor is used as the rotation drive source of the screw, the torque of this electric servo motor is detected, and the measured torque of the measurement process is graphically displayed. An injection molding machine characterized by being displayed. 2. The screw in the heating cylinder is rotated to transfer the resin material to the tip side of the screw while kneading and plasticizing the resin material, storing the measured molten resin at the tip side of the screw, and advancing the screw. In an in-line screw type injection molding machine that injects and fills molten resin into the mold, an electric servomotor is used as the rotation drive source of the screw, and the torque limit value of the electric servomotor at the time of test shot is more than sufficient. It is characterized in that the measured value of the electric servomotor at the time of trial shot is measured by setting the value to have, and the limit torque value of the electric servomotor at the time of continuous molding operation is set based on this measured torque. Setting method of measuring conditions of injection molding machine.