In the gear system, according to different mechanisms, the noise can be divided into acceleration noise and natural vibration noise. On the one hand, when the gear teeth are engaged, the gear will generate a large acceleration due to the impact, which will cause the disturbance of the surrounding medium. The acoustic radiation produced by this disturbance is called gear acceleration noise. On the other hand, under the action of the dynamic meshing force of the gears, various parts of the system will vibrate. The acoustic radiation produced by these vibrations is called self-ringing noise. There will be some noise during the operation of the rack and pinion, such as the manipulator industry. So how do these noises come about, and what are the ways to reduce the noise of the manipulator rack?
The gear has a large load-bearing capacity, high transmission accuracy, up to 0.01 mm, can be extended infinitely, and the transmission speed can be very high. Disadvantages: If the processing and installation accuracy is poor, the transmission noise is large and the wear is large. Uses: Layout steel plate, glass CNC cutting machine, building construction lift up to 30 storeys high. The synchronous belt has a large carrying capacity, if the load is large, the belt should be widened. The transmission accuracy is high, and the transmission length should not be too large. Otherwise, large elastic deformation and vibration should be considered, and the large transmission distance is especially not suitable for precise positioning and continuous motion control, such as the large XY axis of CNC equipment layout, but it can be used from servo motor to transmission gear or from servo Short distance transmission from motor to screw. Advantages: short-distance transmission speed can be high, low noise. Typical use: small CNC equipment.
Analysis of the influence of gear processing factors on noise
Effect of gear type on noise: Different types of gears will have different forms of meshing process due to their different geometric features. For example: under the same load and speed, the noise of helical gears is 3-10 decibels lower than that of spur gears;
Effect of pressure angle on gear noise: In order to transmit a certain power, F must maintain a constant value. If the pressure angle α increases, the normal force Fn on the tooth surface will inevitably increase, which will increase the pitch impulse and meshing impulse on the actual friction tooth surface, resulting in an increase in vibration and noise levels.
Although the center distance error of gear machining does not affect the accurate meshing of the involute tooth profile, its variation will cause periodic changes in the pressure angle of the working environment.
Method for reducing noise of manipulator rack
1. Improve gear lubrication method
For gear lubrication to reduce noise, we should not only start with the choice of lubricant, but also innovate the method of gear lubrication, save lubricant usage, improve gear efficiency and reduce noise, although studies have shown that centrifugal lubrication is effective The most effective way to reduce gear noise is to check the gear box within the specified time range and replace the gears that are seriously damaged or deteriorated in time. On this basis, a small hole is drilled at the bottom of the gear, and the centrifugal force The lubricant is injected through the small hole, and the used lubricant waste is also removed at the same time. This method can effectively make effective friction between the gears and avoid gear transmission noise caused by poor lubrication.
2. Tooth profile correction method
Due to the error of the tooth shape, the teeth of the gears are meshed, and the meshing accuracy is crossed. In order to improve the meshing accuracy, we use the tooth shape correction method to eliminate the noise of the gears. Use assortment to correct the meshing points of the gears, so that the meshing points of the gears are distributed near the pitch circle as much as possible, and the meshing accuracy of the gears is improved.
Factors Affecting the Noise of Manipulator Rack
1) Accuracy level: What kind of accuracy level to choose means how accurate the operation of the manipulator is, especially the positioning accuracy and repeat positioning accuracy are greatly improved.
2) Material: The choice of material has a great relationship with the force of the rack, and of course it has a lot to do with the service life of the rack. My suggestion is to choose conservatively as much as possible. It is better to waste a little on some parameters. In the end, the shortcomings are better, especially the design of the automatic line, because they are all customized designs, and there is little talk about batches, so in order to minimize the after-sales cost, we must try to improve the safety system a little, otherwise the subsequent maintenance and repair costs It will make your life worse than death.
3) Tooth shape: There are usually two tooth shapes to choose from, one is straight teeth and the other is helical teeth. Let me talk about the difference between these two tooth shapes here.
① Spur gears, which are simple in design, easy to manufacture, easy to inspect and operate, and relatively easy to assemble. Because this type of rack has small meshing degree, high noise, and small transmitted load, it is generally used to transmit medium and low loads. , Medium and low speed running occasions.
② Helical gears are more complicated in design, manufacture, inspection and assembly than straight gears. Because of their higher degree of engagement, lower noise, and higher transmission loads, they are more suitable for medium-low speed and high-torque transmission. If you choose this type of rack, you must pay attention to one thing. The matching gear will generate axial force during operation, so there must be a corresponding design plan for the axial fixation of the gear during design.
4) There are usually two types of tooth surface treatment: fine milling and fine grinding, and the specific difference is also reflected in the accuracy.
5) Hardness treatment can confirm the hardness of the rack according to your use environment, load and service life requirements, and you can choose accordingly.