Factors Affecting the Positioning Accuracy of Injection Molding Machine Manipulator
Now many machinery manufacturers use injection molding machine manipulators as the main production method. However, the use of automated manipulators in production can improve product production efficiency and product quality and reduce product production costs.
In production, whether the manipulator of the injection molding machine can work accurately is actually a three-dimensional space positioning problem. And this is a combination of several linear and angular positioning.
In many simpler cases, a single magnitude may be dominant. The factors affecting the positioning error of a single line or angle are as follows:
1. Positioning method
Different positioning methods have different influencing factors. For example, when the mechanical stopper is positioned, the positioning accuracy is related to factors such as the rigidity of the stopper and the speed when the stopper is touched.
2. Positioning speed
The positioning speed has a great influence on the positioning accuracy. This is because the energy of the moving parts that must be dissipated varies with the positioning speed.
Usually, in order to reduce the positioning error, the positioning speed should be reasonably controlled. For example, to improve the buffer performance and buffer efficiency of the buffer device, or control the drive system to decelerate the moving parts in a timely manner.
The manufacturing accuracy and installation speed regulation accuracy of the manipulator have a direct impact on the positioning accuracy.
When the structural rigidity and contact rigidity of the manipulator itself are low, the positioning accuracy is generally low because it is prone to vibration.
5. Weight of moving parts
The weight of the moving parts includes the weight of the manipulator itself and the weight of the object being caught. Changes in the weight of moving parts have a greater impact on positioning accuracy.
In general, positioning accuracy decreases as the weight of the moving part increases. Therefore, it is not only necessary to reduce the weight of the moving parts themselves during design, but also to consider the influence of weight changes during work.
6. Drive source
The pressure fluctuation of hydraulic pressure and air pressure and the fluctuation of voltage, oil temperature and air temperature will affect the repeat positioning accuracy of the manipulator. Therefore, take the necessary measures to stabilize the voltage and adjust the oil temperature. For example，
- Stabilize oil pressure with an accumulator.
- Control oil temperature with heater or cooler.
- At low speed, it is controlled by temperature and pressure compensation flow control valve.
7. Control system
The position control accuracy of switch control, electro-hydraulic proportional control and servo control is different. This is not only because the accuracy and sensitivity of various control components are different, but also related to the presence or absence of position feedback devices.