The operation items of injection molding machine
include three aspects: control keyboard operation, electrical control cabinet operation and hydraulic system operation.
The selection of injection process action, feeding action, injection pressure, injection speed and ejection form, the monitoring of temperature, current and voltage of each section of the barrel, the adjustment of injection pressure and back pressure, etc. are respectively carried out.
Generally, injection molding machines can be operated manually, semi-automatically and fully automatically.
Manual operation is in a production cycle, and each action is realized by the operator turning the operation switch. Generally, it is only selected when the machine is adjusted.
During semi-automatic operation, the machine can automatically complete the operation of one working cycle, but after each production cycle is completed, the operator must open the safety door, remove the workpiece, and then close the safety door, so that the machine can continue the production of the next cycle.
When fully automatic operation, the injection molding machine can automatically enter the next working cycle after completing the action of one working cycle.
In the normal continuous working process, there is no need to stop the machine for control and adjustment. However, it should be noted that if automatic work is required, then (1)
Do not open the safety door halfway, otherwise the full-automatic operation will be interrupted; (2)Timely feeding; (3)
If electric eye induction is selected, care should be taken not to close the electric eye.
In fact, in full-automatic operation, it is usually necessary to temporarily stop the machine halfway, such as spraying mold release agent to the machine mold.
During normal production, semi-automatic or fully automatic operation is generally selected.
At the beginning of the operation, the operation mode shall be selected according to the production needs (Manual, semi-automatic or fully automatic)
And toggle the manual, semi-automatic or fully automatic switch accordingly.
The semi-automatic and fully automatic working procedures have been determined by the circuit itself. The operator only needs to change the speed and pressure, the length of time, the number of thimbles, etc. on the electric cabinet surface, the work program will not be confused due to the operator's wrong button.
When each action in a cycle is not adjusted properly, manual operation should be selected first. After confirming that each action is normal, semi-automatic or fully automatic operation should be selected.
According to whether the injection seat recedes before and after pre-plastic feeding, I . e. whether the nozzle leaves the mold, the injection molding machine generally has three options. (1)
Fixed feeding: the nozzle is always attached to the mold before and after pre-plastic, and the injection seat does not move. (2)
Before feeding: the nozzle is placed against the mold for pre-plastic feeding. After pre-plastic is completed, the injection seat is receded and the nozzle leaves the mold.
The purpose of choosing this method is to use the injection hole of the mold against the nozzle during pre-molding to prevent the melt from flowing out of the nozzle when the back pressure is high, after pre-molding, the heat transfer generated by long-term contact between the nozzle and the mold can be avoided, which affects the relative stability of their respective temperatures. (3)
Post-feeding: after the injection is completed, the injection seat is receded, the nozzle leaves the mold and then premolded, and the premolded injection seat moves forward.
This action is suitable for processing plastic with extremely narrow molding temperature. Due to the short contact time between the nozzle and the mold, heat loss is avoided, and solidification of the melt in the nozzle hole is also avoided.
After the injection is finished and the cooling timer is finished, the pre-plastic action begins.
The screw rotates to squeeze the plastic melt to the front of the screw head.
Due to the function of the check valve at the front end of the Screw, molten plastic accumulates in the front end of the barrel, forcing the screw back. When the screw retreats to a predetermined position (
This position is determined by the travel switch, which controls the backward distance of the screw to realize quantitative feeding)The pre-plastic stops and the screw stops rotating.
The following is the reverse contraction action, which means that the screw moves back in a small amount in the axial direction. This action can relieve the pressure of the melt gathered at the nozzle, overcome the 'salivation' phenomenon caused by the imbalance of internal and external pressure of the barrel.
If retraction is not required, the retraction should be stopped and the switch should be adjusted to the appropriate position to stop the pre-molding.
At the same time when the switch is pressed, the inverted stop switch is also pressed.
When the screw moves backward to press the stop switch, the backward stop stops. Then the seat began to retreat.
When the injection seat retreats to press the stop switch, the injection seat stops retreating.
If a fixed feeding method is adopted, attention should be paid to adjusting the position of the travel switch.
Generally, fixed feeding is mostly used in production to save the advance and retreat operation time of the injection seat and speed up the production cycle.
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