The 4 solution

Because the former security door, security door, after the sudden stop, the level of security safety pedal different, restricted to each failure occurs when the action is different, so the four functional restrictions to signal after four safety relays confirmation.

The use of safety protection in vertical injection molding machine has the former security door, security door, after the emergency stop switch, safety pedal etc.. The specific measures are as follows.

The current security gate signal and safety before the first threshold signal effectively, a reset signal is 1 effective, can allow the controller to switch mode forward signal, locking forward signal, Radio Taiwan forward signal, injection signal and melt signal output, otherwise prohibited. When the safety door, after the signal after safety threshold signal, emergency stop signal, safety pedal signal effectively reset signal first, 1 and 2 after the reset signal to allow the controller effectively, the motor starting signal output, otherwise prohibited.

The current security gate signal or before the safety threshold of signal when an exception occurs, immediately stop switch mode controller forward signal, locking forward signal, Radio Taiwan forward signal, injection signal and melt signal output, abnormal after the treatment, to press the reset button 1, can allow the controller switch mode forward signal, locking the forward signal radio station, forward signal, injecting signal and melt signal output. When the safety door, after the signal after safety threshold signal, emergency stop signal, safety pedal signal an arbitrary when an exception occurs, immediately stop controller of motor start signal output, abnormal after the treatment, to press the reset button reset button 1, 2, the controller to motor start signal output.

The above circuit improvement has to comply with safety standards. But there are some disadvantages in practical application: complex wiring, re design in line to each vertical injection molding machine; the cost is higher, the market price of the safety relay from hundreds to thousands of unequal, and a machine to be adding 4 security module; versatility, each control I/O controller supporting different, eventually receiving signals or by the I/O module is transferred to the PLC.

5 research and development ideas

(1) the control scheme

Aiming at the defects of the existing circuit design. The safety relay module function implementation to achieve the control effect on the I/O board.

In the I/O plate on the existing. Joined the reset signal, the reset signal 1 2 the two DI, combined with existing safety before the gate signal, before the safety threshold signal, after the safety door, safety threshold signal after signal and emergency stop signal, the signal of the six road safety pedal DI, constitute the safety relay module function input.

(2) control flow introduction

The system is powered on instant, will put two pieces of logic processing circuit output control signal, the control signal of 1 -- 2 reset, so as to turn off the switch tube TR1 and a switch tube TR2, preventing the system malfunction.

The normal system startup, before the safety door switch and a former security threshold on efficient, effective and safe threshold switch after security door switch and after the emergency stop switch closed, safety pedal switch is closed, at this time, respectively, to press the reset button reset button 1, 2, the 8 signals were sent into the logic processing circuit at the same time, because of various signal normally, a switch tube TR1 conduction, TR2 switch tube conduction. Allow the controller to switch mode forward signal and mode locking forward signal, Radio Taiwan forward signal, injection signal and melt signal output, allowing the controller to the motor starting signal output.

The current security door switch, before the safety threshold switch to an arbitrary invalid, logic gate immediately make the switch tube TR1 is turned off, the prohibition of switch mode controller forward signal and mode locking forward signal, Radio Taiwan forward signal, injection signal and melt signal output, and the corresponding trigger is cleared. When the external exception handling is completed, namely the front gate and before the safety threshold switch is in the normal mode, closed at this time, must press the reset button 1, only allows the controller to swap mode forward signal and mode locking forward signal, Radio Taiwan forward signal, injection signal and melt signal output.

Similarly, when after the security door switch, after the safety threshold switch, emergency stop any switch, safety pedal switch in a is in abnormal state, the logic gate immediately that the switch tube TR2 is disconnected, prohibit the controller for the motor start signal output so as to stop the motor work, at the same time, the corresponding flip-flop is reset. When the external exception handling is completed, that is, after the security door switch and the safety switch is in the normal state threshold after closing, the emergency stop switch is closed, the safety pedal switch is closed, at this time, must press the reset switch is respectively 1, reset switch 2, allowed the controller of motor start signal output.

6 Conclusion

Controller types on the market used in vertical injection molding machine is various, for each section of the controller in different programming languages, signal on the I/O module has different processing mode. Because the software system is not stable as safety accident is inevitable, so the safety circuit optimization module in the I/O module, is economical played a role of double insurance.