Eight Maintenance Points of the Injection Molding Machine Robot
From the perspective of maintaining long-term operation of the injection molding machine robot, always paying attention to some important operating conditions will reduce downtime and reduce costs. Here are a few things to pay attention to.
1. Rails and bearings
The guide rails and bearings at all shafts should be kept clean and well lubricated. If the robot is running in a dusty environment, the guide rails need to be cleaned frequently. If you find any metal fragments or powder, it may indicate poor lubrication. In order to ensure proper lubrication, it is critical to have a proper linear guide system. Most robot have automated lubrication systems and parts that need to be replaced regularly.
2. Robot cycle period
One of the main points to keep the robot running well is to simply observe and listen. It can reveal a lot of information about the overall operation of the robot. The robot works through specific actions. Therefore, when the abnormal sounds appear, such as howling, clicks, etc., it indicates that the bearing cannot rotate normally or some other component is stuck.
The link part of the robot moves along the guide rail equipped with the power cable and the vacuum hose, and it will make a normal ticking sound, but the sound is smooth and stable. Check any observable bearings to make sure they rotate smoothly. Just need to check and listen to some signs of wear or adjustment, which can greatly help to maintain the best operating condition of the robot.
3. Drive system
If the robot is driven by the assembly frame-transmission gear, pay attention to whether there is any hesitation or shaking during operation. Except for smooth movements, all movements can indicate that the drive system is damaged or some foreign objects are registered inside. When the robot pushes down, the method to quickly check the movement or backlash between the assembly beam and the transmission gear is to push and drag the movement arm, and feel abnormal movement (the back and forth movement is different).
However, due to the high tolerance accuracy of normal manufacturers, this test method will be very inaccurate. If you suspect that there may be a problem with the assembly beam and transmission gear, a better way is to use a long-range magnetic stand. After adjusting the backlash according to the manufacturer’s instructions, check the full stroke of the shaft. It’s to ensure that there is no tight place between the assembly beam and the transmission gear.
If the backlash cannot be adjusted, the assembly frame and transmission gear may be worn and need to be replaced. If it is necessary to repair the assembly frame and the transmission gear, it is best to replace both components at the same time to ensure long-term performance. As for the shaft driven by the conveyor belt, pay close attention to the debris from the conveyor belt wear and its own damage. Check the pulleys carefully and watch for signs of dust originating from the conveyor belt material.
Ensure that the conveyor belt and drive pulleys and sheaves are completely aligned in a row. Conveyor belts that deviate from the direction will wear out very quickly. As long as it is a conveyor-driven system, you can check the preload of the conveyor belt itself according to the manufacturer’s instructions. These specifications will tell you: compared to the pulley, the appropriate amount of error in the specific location of the conveyor belt.
4. Pneumatic system
Including multi-axis servo drives, almost all robot will have pneumatic functions as long as they have wrist swivel and vacuum gripping actions. Pay close attention to the suction cup of the filter regulator unit. The accumulation of water in it indicates that the compressed air source passing through the system is too humid. The presence of a small amount of water vapor may be transmitted to the pneumatic valve and actuator, causing oxidation and internal pollution. And it eventually may cause the pressure regulator to stick or the actuator to stick or fail intermittently.
If the suction cup is equipped with an automatic dehumidification system, contamination or discoloration on the suction cup also indicates that moisture is increasing before it is removed. If water accumulates in the suction cup, it can enter the system even for a short time, causing the above-mentioned problems. If you notice any physical damage to the pneumatic hose, there may be a leak in the system.
If the pneumatic circuit is filled with air at normal operating pressure and there is a leak somewhere in the circuit, then you should be more likely to find a noticeable hissing sound, which will help you determine the location of the leak.
5. Check the molding equipment
The standard configuration of the robot is usually installed on the template of the molding equipment. When the equipment is running fast, the vibration from the molding equipment may be transmitted to the robot and may cause damage. Simply observe the operation of the molding equipment to ensure that the mold movement is adjusted to a reasonable state. Also, reduce the number of shaking or vibration can extend the life of the robot. In the case of high-speed operation, the vibration frequency may be very high. So it is best to install the robot on a supporting structure independent of the molding equipment.
6. Pay attention to wiring wear
When inspecting the surface of the robot, if black particles or powder are found, it indicates that the wiring of the robot circuit has signs of wear. However, even if you can’t detect these signs of wear, you can carefully inspect all power, transformers or encoder cables and the inner and outer sides of the wiring path. Because during the production cycle, the wiring of the robot is continuously rubbed or connected to the cable guide. The wiring will eventually wear out and fail. Ensure the safety of wiring ties and the reasonable installation of cables.
7. Check lubrication
The robot uses a spring-loaded lubricating rod. Unless there is evidence that the guide rail is not sufficiently lubricated, it only needs to be replaced once a year. Equipped with an automatic lubrication system, it can be lubricated continuously along the movement of the robot. But if there are some surfaces on which the robot cannot move normally, then manually lubricate these areas, or realize the lubrication by the automatic system lubrication on a regular program-controlled action.
If you find rust spots, corrosion or wear on any moving surface, or just too dry, it indicates that they are insufficiently lubricated. You should refer to the robot manual for proper lubrication of metal parts. The assembly beam-traditional gear system is automatically lubricated through a lubricant storage unit, but it needs to be replaced every year.
8. Vacuum gripper circuit
The vacuum should be formed almost instantaneously, and the appropriate controller input should be equivalent to grabbing the product. If you find that the vacuum is turned on, and the input light source appears, with delay time exceeding 2 seconds, then it indicates that there is a leak or a defect in the vacuum line, or an improper adjustment of the switching device. The main control panel can be easily tested through the plug-in. If the robot is equipped with a digital vacuum switching unit, it can quickly and automatically fine-tune the minimum threshold of vacuum required to grasp the product.
This process can be completed when the robot is running in automatic operation mode. Save the setting parameters of each production cycle in the memory. And that can save time in the next production change. The digital vacuum switching device has two other advantages:
- The electronic filter of the capture threshold signal compensates for the vibration of the product on the vacuum chuck during rapid movement.
- The product release threshold is different from the capture threshold, and can be programmed to ensure proper release under fast production cycle conditions.
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