Application protection and precautions of the hott

Application protection and precautions of ball screw

the screw shaft will be extended and displaced due to heat, which will lead to the deterioration of positioning accuracy. The amount of thermal change can be calculated by the following formula

△= α· T · L (mm)

△: direction displacement of screw shaft (mm)

t: temperature rise of screw shaft (DEG)

l: effective length of screw part (mm)

α： Coefficient of linear expansion (11. Many choices faced by youth 7 × Deg-1)

that is, every 1 ℃ temperature rise, there will be 12 on the 1m long screw shaft μ The elongation of M occurs. Therefore, even if the lead of the ball screw is processed with high precision, it will not meet the requirements of high-precision positioning due to the displacement caused by temperature rise. In addition, when the service conditions of the ball screw require high speed, the relative calorific value will also increase, and the influence of temperature rise will also increase

the temperature rise Countermeasures of the ball screw are as follows:

(1) control the calorific value

· the calorific value of the ball and the preload of the support bearing should be correct and appropriate

· correct selection and proper supply of lubricants

· increase the lead of the ball screw and reduce the number of turns

(2) forced cooling

· the screw shaft is dug into a hollow and filled with coolant

· the outer edge of the screw shaft is cooled with lubricating oil or air

(3) avoid the influence of temperature rise

turn the machine up at high speed to the temperature

· stable state before use

· pre tension is applied to the screw shaft during installation

· the target value of the cumulative lead is taken as a negative value in advance

· closed loop positioning when using the market classification details of the testing machine

use protection of ball screw:

1. Lubrication

when using ball screw, it must play a prominent role in improving product performance, reducing cost, environmental protection and energy conservation. It must have sufficient lubrication. If the lubrication is not enough, it will contact with metal, resulting in friction and grinding. 2: the interface on the plug-in controller must be closed. The increase of power consumption of the controller will cause failure or shorten its service life. When the speed reaches m/min, lubricating oil is the best

2. Dust prevention

like rolling bearings, when there is mixture or moisture, the wear will increase, sometimes leading to damage. For example, due to the working environment, the working machinery may be mixed with cutting or cutting oil, so when there is foreign matter mixed outside, the screw shaft should be completely covered with folded cloth (snake belly type) or sleeve telescopic tube

3. Partial load

when the partial load phenomenon occurs, it will directly affect the service life and noise of the screw, and most of it will follow the hand feeling of poor operation. If the smoothness of the screw when idling is different from that after assembly, in addition to paying attention to the accuracy of the screw itself, most of them are caused by poor assembly accuracy. (end)