How to Inspect the Load Cell in Injection Molding Machines
A precise load cell has been installed to carry out pressure control of closed-loop. The load cell may lose its correct zero point being affected by load or temperature. After turning on the power of the injection machine, check the zero point of load cell by following the procedure below.
A) Checking the load cell
1) Press [SERVO] of the PREPARATION button to turn off the servomotor.
2) Touch the INJECT screen selector button and the [INJECT] screen change button to display the [INJECT] screen. Then read the value of [INJ PRESS] on the screen. The normal range of pressure is within 1 MPa <10 kgf/cm2>[145 psi].
B) Checking the zero point of load cell
When the displayed value of injection pressure deviates from 1 MPa <10 kgf/cm2>[145 psi] of range, check the zero point of load cell by following the procedure below.
1) Dismount the shaft Stop cover to remove the split collar connecting the screw and shaft S. (Refer to section 5.1.2 Replacing the Screw.)
2) Press [SERVO] of the PREPARATION button to turn on the servomotor.
3) Press MOLD SET-UP of OPERATION button
4) Press [ADVANCE] of the SLOW button to move the screw to the advance limit.
5) When the screw reaches the advance limit, press [RETRACT] of the SLOW button to disconnect the screw and shaft S.
6) Press [SERVO] of the PREPARATION button to turn off the servomotor. Read the display value of [INJ PRESS].
* (Name the read value as [A].)
7) Press [SERVO] of the PREPARATION button again to turn on the servomotor.
8) Press [ADVANCE] of the SLOW button to advance the screw slightly to the extent not to hit the shaft S.
9) Press [SERVO] of the PREPARATION button to turn off the servomotor. Read the display value of [INJ PRESS].
* (Name the read value as [B].)
Zero point adjust is correct when the value of {(A+B) / 2} is within the range of ±0.5 MPa <5 kgf/cm2>[72.5 psi].
C) If the value of {(A+B) / 2} deviates from the range of ±0.5 MPa <5 kgf/cm2>[72.5 psi], conduct automatic calibration of the load cell.
* For automatic calibration of load cell:
Refer to section 5.8.1 Load Cell Automatic Calibration Circuit in OPERATION GUIDEBOOK OF INJECTVISOR-V50 or S51.
* If executing the calibration is often required even after automatic calibration, please contact our service department.
Securely press [SERVO] of the PREPARATION button to turn off the servomotor and turn off the power of the machine before removing the split collar.
By TOSHIBA MACHINE CO.,LTD.
