Their rollers and the outer wheels are arranged in a right angle intersecting intersecting. They can bear the load from all directions at the same time (such as axial, thrust or momentum hormones, etc.). Because of the linear contact between the roller and the track surface, the possibility of the axis to bear the load and the elastic deformation is very small. This type of bearing is widely used in industrial robots, working machines and medical facilities. It needs high rigidity, high speed and high speed to ensure precise occasions.
In cross roller bearings, cylindrical rollers are perpendicular to each other through spacer retainers on the top, so 1 cross roller bearings can bear all loads of radial load, axial load and torque load. Ring size is the minimum limit of miniaturization, especially very thin type is small size close to the limit, and has high rigidity, so the most suitable for use in industrial robot joint or rotating parts, machining center machine rotary table, hand rotating parts, precision rotary table, medical machine, metering device, IC manufacturing equipment etc.
1. Excellent rotation accuracy
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The inner structure of the Cross Roller Bearing is arranged in 90 degrees perpendicular to each other by the roller.
The roller is equipped with a spacer or isolation block between the rollers to prevent the rolling of the rollers from being examined each other. In addition, the phenomenon of roller contact or locking will not occur. At the same time, because the inner and outer ring is a segmented structure, the clearance can be adjusted, even if the preload is applied, high accuracy rotation motion can also be achieved.
2. Simplification of operation and installation
The outer ring or inner ring, which is divided into 2 parts, is fixed together after loading the roller and the holder, so the operation is very simple.
3. Bear large axial and radial load
The roller is arranged vertically through the spacer retainer on a 90 degree V groove rolling surface.
4. Greatly save the installation space
The size of the inner and outer ring cross Roller Bearing is miniature minimal, especially ultra-thin structure is small size close to the limit, and has high rigidity, so the most suitable for industrial robot joints or rotating parts, machining center of the rotary table, the robot rotating parts, precision rotary table, medical instrument IC, measuring equipment, manufacturing device widely used.
5. high speed ability
6. reducing shaft length and machining cost, thermal expansion leads to a limited change in geometric size.
7. the nylon separator is used, the moment of inertia is low, the starting torque is low, and the angle degree is easy to control.
8. optimization of pretightening force, large rigidity, high precision of guiding roller
9. carbon steel provides excellent impact resistance and surface abrasion resistance
10. simple but fully lubricated
Valve focus on flow coefficient and cavitation coefficient of two parameters
Valve flow coefficient and cavitation coefficient is an important valve parameters, which are generally available in the advanced industrial countries, the valve material, even in the sample also printed. China's production of the valve is basically no information in this area, because access to this information need to do experiments can be made, this is our country and the world's advanced level of the valve one of the important performance gap. 3.1 Flow coefficient of the valve Flow coefficient of the valve is a measure of the flow capacity of the valve. The larger the flow coefficient, the smaller the pressure loss when the fluid flows through the valve. According to KV calculation formula: KV-flow coefficient Q-volume flow m3 / h ΔP-valve pressure loss bar P-fluid density kg / m3 ?? 3.2, the valve cavitation coefficient? Gas Erosion coefficient δ value, to select the control flow, choose what kind of valve structure type. Where: H1 - after the valve (outlet) pressure m? H2 - atmospheric pressure and its temperature corresponding to the difference between the saturated vapor pressure m? ΔP - before and after the valve pressure difference m? Various valves due to different structures, therefore, allowed cavitation The coefficient δ is also different. as the picture shows. If the calculated cavitation coefficient is greater than the allowable cavitation coefficient, then it is available and no cavitation will occur. If the butterfly valve allows a cavitation coefficient of 2.5, then: • If δ> 2.5, cavitation does not occur. When 2.5> δ> 1.5, slight cavitation can occur. When δ <1.5, vibration occurs. δ <0.5 continued to use the case, it will damage the valve and downstream piping. The basic characteristics of the valve and operating characteristics of the valve, the valve cavitation occurs at a time when it is out of sight, not to mention that at that point to reach the operating limit. Through the above calculation is clear at a glance. Therefore, cavitation occurs because the liquid accelerates the flow through a section of the tapered section, the part of the liquid gasification, the resulting bubble followed by the valve after the open section burst, the performance of three :? (1) the occurrence of noise (2) vibration (In severe cases, it can cause the destruction of foundation and related structures, resulting in fatigue fracture.) (3) Material damage (erosion of valve body and pipeline) • From the above calculation, it is easy to see that cavitation and post-pressure H1 There is a great relationship, increased H1 will obviously change the situation, to improve the method:? A. The valve installed in the pipeline lower. b. Install the orifice plate on the pipe behind the valve to increase the resistance. c. Valve outlet is open, direct reservoir, so that the bubble burst space increases, reduced cavitation. ? Comprehensive analysis of the above four aspects, discussion, summed up the gate valve, butterfly valve main features and parameter list easy to use. Two important parameters in the valve operation.