What should be paid attention to when servo injection manipulator is applied to automobile injection parts?

In the application of servo injection manipulator in the production of automobile injection parts, we must first make clear the particularity of automobile plastic parts. Most of these products belong to the main engine factory accessories, which have strict requirements on dimensional consistency, appearance quality, delivery stability and traceability. Some interior parts and structural parts also have special specifications such as flame retardant, odor and low volatility. As the core automation equipment for picking, putting, burying and cutting gates, the manipulator is used for selection and debugging, tooling design, production process and daily maintenance.

In terms of manipulator selection and servo parameter matching, closed-loop servo drive model is preferred to ensure positioning accuracy and motion repeatability. Many automobile plastic parts contain buckle, thin-walled and long runner structures, and some of them need to be embedded with nuts, copper sleeves and other inserts. The load, stroke and acceleration of the manipulator should be reserved with a safety margin, and it is impossible to run at full load and high speed for a long time. The specifications of servo motor, reducer and guide screw should meet the beat requirements, and the shift of center of gravity is easy to cause jitter when taking and placing large pieces of interior decoration. It is necessary to set servo acceleration and deceleration curves reasonably to avoid scratching and deformation of products caused by start-stop impact and reduce vibration interference to the mold locking structure of injection molding machine. The manipulator and the injection molding machine should do a good job of signal docking, adopt standard communication protocol for linkage, and the safety door, low-voltage protection of the mold, ejection signal and interlock logic of the manipulator must be complete to prevent the manipulator from entering the mold cavity when the mold is not completely opened and ejected, resulting in damage to the mold, products and even equipment.

The design of fixture is the key point of automobile parts production, and the vacuum sucker and pneumatic gripper should be combined and configured according to the product structure. Exterior parts, such as door panels and instrument panel housings, can't directly contact the A surface with hard jaws. Traceless suction cups are preferred, and the arrangement of suction cups should avoid the visible area of appearance. The material of suction cups should be silica gel without precipitation and pollution of plastic parts, so as to prevent printing stains and oil stains from affecting the smell and appearance detection of the whole vehicle. Structural parts and support products can be clamped with soft rubber jaws, and the clamping force is accurate and adjustable to avoid crushing the thin-walled position. If the insert is embedded into the tooling, the precision of the positioning pin should be controlled within a very small tolerance range, and the skew placement of the insert will directly lead to the scrapping of the product and even the die surface crushing. The functions of cooling and blowing dust removal should also be considered in the tooling. Dust, glue wire and release agent residues in the mold cavity are the main causes of poor appearance of automobile parts. After the manipulator takes the parts, it blows air synchronously to clean the mold cavity to reduce subsequent defects.

In terms of production debugging and process linkage control, PPAP and first article inspection system are generally implemented for automobile parts. After the manipulator changes the mold, it must confirm the first article, and check the position of taking the piece, the posture of putting the piece, the embedded depth of the insert and the shearing position of the gate. The servo motion coordinates should be stored in the corresponding mold formula, which can be called with one key when changing molds, so as to reduce the size fluctuation caused by manual debugging. The picking sequence should match the injection cooling and ejection sequence. Thin-walled parts and soft interior parts are easy to rebound and deform after demoulding. The picking posture and lifting support position of the manipulator should be reasonable. If necessary, the predetermined tooling should be carried with the manipulator to keep the shape in the high temperature stage of the product and reduce the deformation defects. The running rhythm can't be raised blindly, and the high-speed servo movement will easily lead to position deviation, air leakage of suction cups and vibration of parts, so the cycle should be optimized on the premise of stable quality. In addition, there are many traceability requirements for automobile plastic parts. The manipulator system can be connected with MES system to record the production time, servo operation status and alarm information of each mold, which is convenient for the traceability investigation of defective parts.

Safety protection and daily maintenance can not be ignored. The environment of automobile injection workshop is complex, and there are release agent, oil gas and plastic dust, which will be attached to servo motor, encoder and guide screw. It is necessary to clean and prevent dust regularly, and do a good job in cable protection to avoid signal packet loss and servo alarm caused by oil pollution corroding lines. Safety grating, area sensor and emergency stop loop shall be inspected in each shift, and isolation fence shall be set in the manipulator operation area to prevent personnel from entering by mistake. Regularly check the origin memory of the servo battery, the lubrication of the reducer and the tightness of the suction cup, and replace the aging suction cup and air pipe in time. Operator training should be in place, it is forbidden to modify servo gain and limit parameters at will, and the first article must be re-verified after parameter changes. When there are abnormalities such as parts dropping, scratching and positioning deviation, it is not only necessary to restart the equipment, but also to investigate the root causes such as servo load change, tooling looseness and mold ejection deviation.

Finally, both incoming materials and supporting auxiliary links should be taken into account. Oil pollution and debris should be strictly controlled for automobile parts, and lubricating oil should be prevented from dripping on the surface of tooling and products during the maintenance of manipulator. For plastic parts that need post-treatment, the feeding position of the manipulator should be adapted to the conveyor belt and fixture to avoid secondary collision and scratch. Stable servo manipulator application combined with standardized control can continuously meet the supporting requirements of high yield, high traceability and low defects in the automobile industry, reduce the risk of customer complaints and improve the efficiency of the whole injection production line.