Nowadays, many machinery manufacturers are choosing to use injection molding machine robots as their main production method. However, the use of automated robots in production can greatly improve product production efficiency and product quality as well as reduce product production costs. Whether the injection molding machine robot can work accurately in production is actually a three-dimensional space positioning problem, which is a combination of several linear and angular positioning.
In many simpler cases, a single value may be dominant. Factors that affect the positioning error of a single linear or angular value 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 stiffness of the stopper and the speed when it contacts the stopper.
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 is different when the positioning speed is different. Generally, in order to reduce the positioning error, the positioning speed should be reasonably controlled, such as improving the buffering performance and buffering efficiency of the buffer device, and controlling the drive system to slow down the moving parts in time.
3. Accuracy – the manufacturing accuracy and installation speed regulation accuracy of the manipulator have a direct impact on the positioning accuracy.
4. Rigidity – when the structural stiffness and contact stiffness of the manipulator itself are low, it is easy to generate vibration, and the positioning accuracy is generally low.
5. The weight of the moving part – the weight of the moving part includes the weight of the manipulator itself and the weight of the object being grasped. The change in the weight of the moving part has a great influence on the positioning accuracy. Generally, when the weight of the moving part increases, the positioning accuracy decreases. Therefore, when designing, it is necessary not only to reduce the weight of the moving part itself, but also to consider the influence of the change in the grasping weight during work.
6. The pressure fluctuations of the driving source – hydraulic and air pressure, as well as the fluctuations of voltage, oil temperature and air temperature will affect the repeatability of the manipulator. Therefore, necessary voltage stabilization and oil temperature adjustment measures should be adopted. For example, an accumulator is used to stabilize the oil pressure, a heater or cooler is used to control the oil temperature, and a temperature and pressure compensation flow control valve is used to control the flow at low speed.
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 elements are different, but also related to the presence or absence of position feedback devices.
