JPH0577295A - Judging method for plasticization condition in injection molding machine - Google Patents

Abstract

PURPOSE:To correctly grasp the plasticization condition of resin and decide whether the condition is appropriate or not. CONSTITUTION:The output axis 4a of a rotational drive device 4 is coupled with an injection screw 3 inserted into a heating cylinder 1. A protruding piece 7 is provided on the axis 4a so as to be radially projected therefrom. A sensor 8 is fixed to a casing 4b of the rotational drive device 4. The sensor 8 detects the passage of the piece 7 following the rotation of the axis 4a. A rotation detector 6 comprising the sensor 8 and the piece 7 detects the rotation of the screw 3 from the start of measurement to the end thereof to measure the total number of rotation of the screw 3. Whether the total number is in a reference range between an upper limit value and a lower limit value or not is monitored and if it is in the range, it is decided appropriate and if not, it is decided not appropriate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of judging the plasticization status for judging whether or not a resin is properly plasticized in a heating cylinder of an injection molding machine.

[0002]

2. Description of the Related Art An injection screw inserted into a heating cylinder so as to be rotatable in the circumferential direction and movable in the axial direction is retracted by resin pressure while being rotated in the circumferential direction by a rotary drive device to plasticize the resin. In a conventional injection molding machine configured to measure a predetermined amount before the injection screw, the rotation speed (rpm), back pressure, and time of the injection screw at the time of measurement are measured to know the plasticization status of the resin. I am trying.

[0003]

However, even if the rotation drive device for rotating the injection screw is set to a predetermined rotation speed, the rotation speed changes every moment due to the fluctuation of the load. However, only the instantaneous number of revolutions at that time is known, and the substance of the revolution cannot be grasped as a whole. Although it has been considered to reduce the rotation fluctuation range of the injection screw by feedback control, the same as the above description that only the instantaneous rotation speed is known.

Further, the measuring time also changes depending on the set value of the back pressure and the fluctuation of the back pressure. Therefore, it is not possible to correctly grasp the plasticization situation and to judge whether or not it is appropriate only by measuring the rotation speed and back pressure of the injection screw and the measuring time.

An object of the present invention is to provide a method for judging the plasticization status of an injection molding machine, which can accurately grasp the plasticization status of the resin in the heating cylinder and judge whether or not it is appropriate. And

[0006]

In order to achieve the above object, the present invention relates to an injection screw, which is inserted into a heating cylinder rotatably in the circumferential direction and movably in the axial direction, by a rotary drive device. In the injection molding machine that plasticizes the resin and measures a predetermined amount before the injection screw by rotating the resin backward while rotating in the direction, the total number of rotations of the injection screw from the start to the end of the measurement of the resin is detected. The total number of rotations of the injection screw is compared with a reference value to determine the plasticization status of the resin.

[0007]

[Function] Since the total number of revolutions of the injection screw that actually worked for plasticizing the resin from the start to the end of measurement is measured and compared with the reference value, the revolution number may change every moment. However, regardless of such fluctuation, it is possible to know the plasticization situation as a whole accurately and to judge its suitability appropriately.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a main part of an injection molding machine to which the present invention is applied, and reference numeral 1 is a heating cylinder. A hopper 2 is provided at the right end of the heating cylinder 1 in FIG. 1, and an injection screw 3 is inserted inside. The injection screw 3 is rotated in the circumferential direction by a rotation drive device 4 such as an oil motor, and is moved in the axial direction by an injection cylinder 5.

A rotation detector 6 is attached to the injection screw 3. The rotation detector 6 includes a protrusion 7 and a sensor 8. The projecting piece 7 is attached to the output shaft 4a of the rotary drive device 4 connected to the injection screw 3 by the coupling 9 so as to project in the radial direction of the output shaft 4a. The sensor 8 is fixed to the casing 4b of the rotation driving device 4, and detects the passage of the output shaft 4a, that is, the projection piece 7 accompanying the rotation of the injection screw 3. Another example of the rotation detector 6 will be described later.

FIG. 3 is a block diagram of an electric circuit embodying the present invention. The rotation detector 6 is connected to a counter 11. The counter 11 receives a signal output from the sensor 8 of the rotation detector 6 every time the injection screw 3 makes one revolution, integrates the number of revolutions of the injection screw 3, and displays it as the number of revolutions (finally the total number of revolutions). To do. The setting comparison unit 12 and the controller 13 are connected to the counter 11. In the setting comparison unit 12, the upper limit value and the lower limit value of the total number of rotations of the injection screw 3 rotating from the start to the end of measurement are set as reference values. Injection screw 3 obtained by counter 11
The total number of rotations is output to the setting comparison unit 12 and the controller 13.

The setting comparator 12 receives the output signal of the counter 11 and compares the total number of revolutions of the injection screw 3 with the upper limit value and the lower limit value, and the total number of revolutions of the injection screw 3 is out of the range between the upper limit value and the lower limit value. In this case, the alarm device 14 is operated, and a stop signal is output to the sequence circuit 15 of the injection molding machine to stop the operation of the injection molding machine. Alarm device 14
Is composed of a buzzer, a lamp, and the like.

The comparison result of the setting comparison unit 12 is also output to the controller 13. The controller 13 uses the counter 11
The total number of rotations input from the and the comparison result of the setting comparison unit 12 are stored in the storage unit 13a, and the stored contents are printed by the printer 16 as they are or in response to a command, and displayed on the display 17.

Next, one embodiment of the method for judging the plasticization status according to the present invention will be described with reference to the flow charts of FIGS. The upper limit and the lower limit of the total number of revolutions of the injection screw 3 required from the start of operation to the end of measurement are set in the setting comparison unit 12 (step S1).

When the molding operation is started, it is judged in step 2 whether or not the metering (supply) is being performed. When the metering is being carried out, the counter 11 reads the input from the sensor 8 (step S3), and the value of the injection screw 3 is changed. The number of rotations up to is calculated (step S4), and the number of rotations is displayed as the current value (step S5). In step S6, it is determined again whether or not the measurement is being performed, and the rotation of the injection screw 3 is measured until the measurement is completed.

When the measurement is completed and the injection screw 3 is stopped, the number of rotations up to that point is latched as the total number of rotations (step S7). The above total number of rotations is determined by the setting comparison unit 12
Is compared with the upper limit set in step S8, and when it is smaller than the upper limit, the process proceeds to step S9 and is compared with the lower limit. If the total number of rotations is larger than the lower limit value, it is stored in the storage unit 13a of the controller 13 (step S12),
In step S13, the data is output to the printer 16 and displayed on the display 17, and the process ends.

If the total number of rotations of the injection screw 3 is determined to be equal to or more than the upper limit value in step S8 or less than or equal to the lower limit value in step S9, the alarm device 1
4 operates (step S10), and the machine stops (step S11). The operation of the alarm device 14 and the stoppage of the machine are also stored in the storage unit 13a, output to the printer 16 and displayed on the display 17 (steps S12, 1).
3) Finish. If it is determined in step S2 that weighing is not in progress, the process ends.

Depending on the type of resin and the molded product, in addition to the total number of revolutions of the injection screw 3, back pressure, metering time, etc. may be added to determine the adequacy of the plasticization status.

FIG. 6 shows another example of the protrusion 7 of the rotation detector 6. A large number of protrusions 7 in FIG. 6 are formed in a gear shape at a predetermined pitch. In the case of such a configuration, the rotation angle of the injection screw 3 can be accurately known. As the sensor 8, a sensor such as a photo sensor, a proximity switch, or a micro switch that emits ON / OFF signals is usually used.

FIG. 7 shows another example of the rotation detector 6. The rotation detector 6 includes an encoder 18 and an encoder 18
And pulleys 19 and 20 attached to the output shaft 4a, and a belt 21 wound between the pulleys 19 and 20. In this case, the number of rotations (total number) is calculated by integrating and measuring the pulses of the encoder 18 that rotates in synchronization with the injection screw 3.
Figure out. In the present invention, the structure and type of the rotation detector 6 are not limited to the above and are arbitrary.

[0020]

As described above, according to the method of judging the plasticization state in the injection molding machine of the present invention, the injection screw inserted into the heating cylinder so as to be rotatable in the circumferential direction and movable in the axial direction is rotated. In an injection molding machine that plasticizes the resin and measures a predetermined amount before the injection screw by rotating the drive device in the circumferential direction and retracting with the resin pressure, the total number of rotations of the injection screw from the start to the end of the measurement of the resin Since it is configured to detect and compare the plasticization status of the resin by comparing the total number of rotations of the injection screw with a reference value, it is determined whether the plasticization status of the resin is correctly grasped and whether the plasticization is properly performed. Can be accurately determined.

Further, since the total number of revolutions is accurately and directly measured in each molded product, it is possible to comprehensively check the variation of the molding conditions, that is, the molding quality, from the variation of the total number of revolutions.

[Brief description of drawings]

FIG. 1 is a front view of a main part in which a part of an injection molding machine to which the present invention is applied is cut away.

FIG. 2 is a front view showing an example of a rotation detector.

FIG. 3 is a block diagram of an electrical circuit embodying the present invention.

FIG. 4 is a front part of a flowchart showing an embodiment of the present invention.

FIG. 5 is a latter part of a flowchart showing an embodiment of the present invention.

FIG. 6 is a front view showing another example of the protrusion of the rotation detector.

FIG. 7 is a front view showing another example of the rotation detector.

[Explanation of symbols]

 1 heating cylinder 3 injection screw 4 rotation drive device 6 rotation detector

Claims (1)

[Claims] 1. An injection screw inserted into a heating cylinder so as to be rotatable in the circumferential direction and movable in the axial direction is retracted by a resin pressure while being rotated in the circumferential direction by a rotation drive device, thereby plasticizing the resin. In an injection molding machine that measures a predetermined amount before the injection screw, the total number of rotations of the injection screw from the start to the end of resin measurement is detected, and the total number of rotations of the injection screw is compared with a reference value to determine the plasticization status of the resin. A method for judging the plasticization status in an injection molding machine, which comprises: