SU1206119A1 - Method of automatic control for volume batching of melt in injection moulding of plastic articles - Google Patents

Description

The invention relates to mechanical engineering, mainly chemical, in particular, to the processing of plastics by injection molding.

The purpose of the invention is to improve the accuracy of the geometric dimensions of molded products by increasing the accuracy of dosing of the amount of plasticizable melt.

The drawing shows a block diagram of a device that implements a generic method for automatically regulating the volume dose of the melt during injection molding of plastic products.

The device contains a plasticizing-: worm to 1, committed at the injection stage. The axial movement inside the plasticization jsdhdpa 2 towards the form 3. At the stage of plasticization, the worm to 1 rotates, moves in the opposite direction, accumulates the plasticized melt in the front part of the plasticization cylinder 2. 1, the output of which is associated with the first inputs of two blocks 5 and 6 of the comparison. The second input of the comparison unit -5 is connected via key 7 to the setting device 8 of the pillow size and to the first output of the arithmetic logic unit (ALU) 9. The third input of the comparison unit 5 is connected to the second output of the ALU 9. Via the fourth output ALU 9. The fourth the input of the comparison unit 5 is connected with the first output of the cycle control unit 11. The output of the unit 5 is connected to the first input of the ALU 9, the second input of which is connected to the second output of the unit 11. The third output of the ALU 9 is connected to the second input of the comparison unit 6, the output of which is connected to the input of the control unit 11. The third output, control unit 11 connected to the executive mechanisms of the injection molding machine (not shown).

The proposed method of automatically controlling the volume dose of the melt is implemented in the device as follows.

At the time of the end of the injection, the cycle control unit 11 issues a command to the comparison unit 5 to compare the values of the actual and given coordinates of the screw 1 (cushion values). Information on the value of

five

61

About 5

0 5 0 5

0

s

192

the actual coordinate of the screw 1 enters the comparison block 5 from the sensor D, and about the preset one through the key 7 from the setting unit 8. The block 5 generates the error signal of the compared values, which goes to the ALU 9.

During the first ten cycles, information about the magnitudes of the mismatches is accumulated in the ALU 9. After the signal from the control unit 11 arrives at the end of the first ten cycles of the ALU 9, it calculates the average arithmetic deviation of the mismatches. The signal about the performed calculations goes to the keys 7 and 10. In this case, the key 7 disconnects the setting device 8 from the comparison unit 5, and the key 10 connects to the comparison unit 5 the second output of the ALU 9, generating a signal proportional to the specified pillow value corrected by the calculated average value arithmetic deviation mismatch. Thus, starting from the eleventh cycle, the comparison unit 5 compares the actual value of the pillow, measured by the sensor 4, not with the value specified by the setting device 8, but with the corrected ALU 9.

ALU 9, in addition to the correction of the specified value of the pillow, performs the calculation of the path that the worm 1 needs to undergo when kneading the required dose of the melt. This is done as follows. The path of the screw during melt injection, measured by sensor 4, is summed algebraically with the corrected (taking into account the arithmetic mean deviation of the mismatches) the specified value of the pillow. The signal proportional to the calculated amount is fed to the input of the comparison unit 6, where during the process of kneading it is compared with the current path traveled by the worm 1 coming from sensor 4. When the signals arriving at the inputs of the comparison unit 6 coincide, the latter outputs the corresponding signal to control unit 11 which produces a command by the actuator to stop the kneading.

The implementation of the proposed method of automatic control of the volume dose of the melt compared to

known allows the technologist to save from the need to specify the exact value of the pillow at the time of the end of the shower, i.e. remove the increased requirements for the pre-set pillow size, since

in the process of cyclic operation, this value is automatically corrected, approaching the optimal one, which ensures the accuracy of the geometric dimensions of the molded products.

Compiled by A. Kudrov Editor A. Szabo Tehred O. Vashchishina Proofreader T. Kolb

8623/17

Circulation 640 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch PPP Patent, Uzhgorod, st. Project, 4

Claims (1)

METHOD OF AUTOMATIC CONTROL OF VOLUME DOSE OF MELT WHEN MOLDING UNDER PRESSURE OF PRODUCTS FROM PLASTICS, which consists in measuring the path traveled by the worm during injection of the melt into the mold cavity, determining the actual coordinate of the worm at the time of the end of the injection, comparing it with the predetermined sign, determining and by comparing values, calculating the algebraic sum of the mismatch with the measured path traveled by the worm during injection of the melt into the mold cavity, determining by value the not calculated sum of the worm path during melt plasticization for injection in the next casting cycle, characterized in that, in order to increase the accuracy of the geometric dimensions of the molded products by increasing the metering volume of the plasticized melt, the standard deviation of the mismatch values determined in previous casting cycles is calculated, correct for the value of the calculated deviation of the predefined coordinate of the worm at the time of the end of the injection and determine in subsequent cycles the value and mismatch by comparing the actual coordinates of the worm at the time of fuel injection with the corrected closure predetermined value. * 1206119