1: What are the factors that cause the failure of the chain failure?
Many people know that the chain can play the role of transmission, but the chain often fails, so the chain manufacturer will explain to you what are the factors that cause the chain to fail?
The chain is fatigued and fails
Assuming that the lubrication conditions are better, and it is also a relatively wear-resistant chain, when it fails, it is basically caused by fatigue damage. Since the chain has a tight side and a loose side, the loads that these components are subjected to vary. When the chain rotates, it will be stretched or bent due to the force. The parts in the chain will gradually have cracks due to various external forces. After a long time, the cracks will appear. It will gradually become larger, and fatigue and fracture may occur. Therefore, in the production chain, various measures will be taken to improve the strength of the parts, such as the application of chemical heat treatment to make the parts appear carburized, and there are also methods such as shot peening.
The connection strength is damaged
When using the chain, due to the load, the connection between the outer chain plate and the pin shaft, as well as the inner chain plate and the sleeve may loosen during use, causing the holes of the chain plate to wear , the length of the chain will increase, showing failure. Because the chain plate will fall after the riveted center of the chain pin head is loose, and the chain link may also fall apart after the center of the opening pin is cut, resulting in the failure of the chain .
The chain fails due to wear and tear during use
If the chain material used is not very good, the chain will often fail due to wear and tear. After the chain is worn, the length will increase, and it is very likely that the teeth will be skipped or the chain will be disconnected during use. The wear of the chain is generally in the center of the outer link. If the inside of the pin shaft and the sleeve is worn, the gap between the hinges will increase, and the length of the outer connection will also increase. The distance of the inner chain link is generally affected by the generatrix on the same side between the rollers. Since it is generally not worn, the length of the inner chain link will generally not increase. If the length of the chain increases to a certain range, there may be a case of off-chain, so its wear resistance is very important when producing the chain.
In addition, the chain will be glued, statically broken during use, and frequent starting, braking and other actions will affect its performance, which may lead to chain failure. In order to reduce the occurrence of problems, chain manufacturers must be very careful when producing products to ensure product quality and reduce the probability of failure.
2: The roller chain is used in a relatively high temperature environment
The roller chain enables the actuator to obtain a certain speed and direction of the transmission chain. The inner connection transmission chain is a transmission chain that connects the two unit movements inside the compound movement, or connects the actuators that realize the movement of the two units inside the compound movement. The essential difference between the two is that the movement is composed of a single or multiple movements and an external linkage transmission chain, which is the entire compound movement and the external movement source.
Only determining the speed and direction of the forming motion has no direct influence on the shape of the machined surface, and because the internal linkage transmission chain is linked to the compound motion, the two unit movements that must ensure strict kinematic linkage inside determine the track of the compound motion. Whether its transmission ratio is accurate and whether the relative motion of the two units determined by it is correct will directly affect the shape accuracy of the machined surface and even fail to form the required surface shape.
The suspension chain has double horizontal wheels, which can effectively reduce the load capacity of the horizontal wheel bearings. Its main parts are based on 40 manganese steel and have undergone heat treatment, which can effectively increase the tensile strength of the chain and prolong the service life of the chain. The structure of this chain is reasonable, the cross steering shaft is forged and formed in one piece, and the special rivet joint design. In order to enhance the load capacity of the chain, the horizontal and vertical wheels are designed with higher specifications, and at the same time have the characteristics of flexible steering, strong tensile resistance, and heavy load. Especially suitable for use in environments with relatively high temperatures.
The daily maintenance of the chain is divided into primary maintenance and secondary maintenance. During the normal use of the production line, due to normal or accidental wear and tear, as well as various abnormal phenomena during the operation of the production line, it must be stopped immediately and reported for repair in time to avoid major accidents. Non-professional maintenance personnel or without the permission of professional maintenance personnel are not allowed to repair by themselves.
When repairing the circuit, if necessary, the person in charge of the chain production line can be asked to assign personnel to wait at the electrical box to prevent others from opening the production line, and at the same time, hang up warning signs. At the same time, the power must be turned off to perform maintenance, and live operation is not allowed.
Three: Measures for roller chains to reduce the transmission error of machine tool transmission chains
Roller chain – Summarize some measures to reduce the error of the transmission chain on the machine tool, and further improve the precision and work efficiency of machining.
The transmission chain should be shortened as much as possible, such as the transmission system of a thread grinding machine used in mass production as shown in the figure below. The replaceable female screw of the machine tool and the workpiece to be processed are connected in series on the same axis. The pitch of the female screw is equal to the pitch of the workpiece, and the transmission chain is the shortest, so that relatively high transmission accuracy can be obtained.
Reduce geometric eccentricity when assembling various transmission mechanical components, and improve assembly accuracy.
Improve the manufacturing accuracy of the end elements of the transmission chain. In the general deceleration transmission chain, the error of the end elements has the greatest influence, so the accuracy of the end elements such as the indexing worm gear of the hobbing machine and the female screw of the thread processing machine tool should be the highest. .
In the transmission chain, the transmission ratio allocated to each transmission pair is based on the principle of increasing reduction ratio. The greater the speed reduction ratio of the transmission pair at the end of the transmission chain, the smaller the influence of the errors of the other transmission components of the transmission chain. Therefore, the number of teeth of the indexing worm gear should be more, and the pitch of the female screw should be larger. , which would have exploited drive chain errors.
Using a calibration device, the essence of the calibration device is to artificially add an error in the original transmission chain, whose magnitude is equal to the error of the transmission chain itself but opposite in direction, so that they cancel each other out.
For example, high-precision thread processing machine tools often have Cao Yong mechanical calibration mechanism, as shown in the figure below, according to the measurement of the lead error of the workpiece 1 to be processed, the calibration curve 7 on the calibration ruler 5 is designed, and the calibration ruler 5 is fixed on the machine tool body. When threading, the female lead screw of the machine tool drives the nut 2 and other fixed tool rests and levers 4 to move. At the same time, the calibration error curve 7 on the calibration scale 5 passes through the contact 6, and the lever 4 makes the nut 2 generate an additional transmission, so that the tool holder obtains an additional displacement to compensate for the transmission error.
The mechanical correction device can only correct the static transmission error of the machine tool. If the dynamic transmission error of the machine tool is to be corrected, a computer-controlled transmission error compensation device is required.
Post time: Mar-22-2023