Safety of yingtu injection machine 1. Mechanical protection: when the injection machine acts abnormally, the safety protection can be carried out through the timely and effective block of mechanical device. Under normal circumstances, the front safety door is closed, and the mechanical lock baffle is pressed by the safety door to leave the blocking position, so that the machine can effectively lock the mold. In case of any abnormality, if the current safety door fails to be effectively closed, the mechanical lock baffle will be in the blocking position to block the abnormal mode locking action.
However, in practical application, there are the following hidden dangers: the block is stuck and there is no entry barrier; the block is lost; when the block rod is half tooth type (as shown in Figure 1), when the block rod rotates abnormally, the effective block area will become smaller and lead to protection failure; when the block rod is full tooth type, when the mold is opened in place, the block will fall on the top of the block rod or the toothless part and lead to protection failure; the block rod is toothless When the smooth rod (most early injection molding machines adopt this method), when the mold is opened in place, the baffle falls on the smooth rod or the baffle is too far away from the baffle position, resulting in protection failure (after each mold change, the effective length of the baffle rod needs to be adjusted to ensure that the baffle and the baffle rod form an effective barrier, so it is time-consuming and laborious, with poor practicability). These hidden dangers can lead to mechanical lock failure in use.
Safety of yingtu injection machine 2. Hydraulic protection: add a hydraulic oil valve in the hydraulic oil circuit to play the role of switch. When the original hydraulic oil valve fails to open effectively, the hydraulic circuit will be interrupted, and the increased hydraulic on-off valve can reduce the probability of abnormal conduction (oil valve stuck, oil valve internal leakage) of the oil circuit in the mold locking action, thus improving the protection coefficient.
In the actual control, there are two modes of hydraulic protection: mechanical hydraulic protection and electrical hydraulic protection.
Mechanical hydraulic linkage protection: when the safety door is closed, the mechanical force of the safety door directly acts or the mechanical force is applied to the hydraulic on-off valve through the transmission rod to open and close the hydraulic circuit. Electric hydraulic linkage protection: when the mold locking conditions are met, the computer first outputs the mold locking hydraulic on-off valve signal, which is connected in series with the contact (safety door closed, contact connected) of the travel switch specially set for the front safety door, and then outputs to the hydraulic on-off valve, and then the hydraulic on-off valve acts, triggers the valve core displacement detection switch, and outputs a switch electrical signal to the computer. When the computer detects this signal within the set time, it will output the mode locking signal, thus improving the guarantee coefficient of the electric hydraulic protection.
But in practical application, there are the following hidden dangers: the transmission rod of the mechanical hydraulic linkage protection device is loose, stuck or the hydraulic on-off valve is stuck, which leads to abnormal conduction, thus the protection fails; the hydraulic on-off valve of the electrical hydraulic linkage protection device is stuck, the on-off valve is abnormal due to the abnormal on-off valve displacement check switch or the external circuit short circuit, thus the protection fails.
The electric hydraulic linkage protection device controls the hydraulic on-off valve through the electrical signal. The reliability of the hydraulic system is not as good as the on-off control of the on-off valve through the mechanical force, but it improves the guarantee of the electrical control. Considering the inconvenient installation and cost, most of the injection molding machines in China are not equipped with hydraulic safety devices.
Safety of yingtu injection machine 3. Electrical protection: when the mold locking electrical conditions are not met, the electrical control system of the injection machine will not output the mold locking signal. Specifically, when the front and rear safety doors are closed and the previous action of the injection molding machine is effectively reset, the injection molding machine starts to lock the mold, and the electrical control system of the injection molding machine outputs the mold locking and action signals. If the effective signal of safety door closing is interrupted, the control system has no mode locking output.
However, in practical application, there are the following hidden dangers: the switch is stuck, the contact is poor or the circuit input circuit is short circuited to trigger the mode locking signal; the installation of the safety door is not stable, the shaking causes the abnormal triggering of the mode locking switch signal; the external signal interference, the computer board is abnormal (such as the dust humidity causes the circuit triggering) or the program failure triggers the mode locking signal. Nowadays, most injection molding machine manufacturers attach great importance to these problems and have introduced improved versions.