A brief introduction to the linear guide

Linear guides are also known as line rails, slide rails, linear guides, and linear slide rails.

For linear reciprocating movement, it has a higher rated load than a linear bearing, and can also bear a certain torque, and can achieve high precision straight line motion in high load conditions.

The linear motion guide is used to support and guide the moving parts, and to do reciprocal linear motion in a given direction. According to the nature of friction, the linear motion guide can be divided into sliding friction guide, rolling friction guide, elastic friction guide, fluid friction guide and so on.

Linear bearings are mainly used in automatic machinery, such as German imported machine tools, paper bowls, laser welding machines, etc., of course, linear bearings and linear axes are used.

Slider - the motion is transformed from a curve to a straight line. The new guideway system enables the machine tool to obtain fast feed speed. When the spindle speed is the same, fast feed is the characteristic of linear guide rail. The linear guide has two basic components, like a plane guide, one is fixed as a guide, and the other is a moving element. Since the linear guide is a standard part, the only thing for a machine tool manufacturer is to process the plane of a guide rail and the parallelism of the alignment guide. Of course, in order to ensure the accuracy of machine tools, a small amount of scraping is necessary. In most cases, installation is relatively simple.

The guide rail is hardened steel, which is placed on the installation plane after fine grinding. Compared with the plane guide, the geometric shape of the cross section of the linear guide is more complex than the plane guide. The reason is that the grooves need to be processed on the guide rail to facilitate the movement of the sliding elements. The shape and quantity of the grooves depend on the functions to be completed by the machine tools. For example, a guideway system, which bears both the linear force and the subversive torque, is very different from the guide rail which only bears the linear force.

The moving elements and the fixed elements of the linear guide rail do not use the intermediate medium while the rolling steel ball is used. Because rolling steel balls are suitable for high-speed movement, small friction coefficient and high sensitivity, and satisfy the working requirements of moving parts, such as tool rest and trailing board of machine tools. The basic function of the fixed element (guide rail) of the linear guide system is like the bearing ring, and the bracket that installs the steel ball has the shape of "V". The bracket is wrapped in the top and two sides of the guide rail. In order to support the working parts of the machine tool, a linear guide has at least four supports. To support large working parts, the number of supports can be more than four.

When the working parts of the machine tool move, the steel ball is circulated in the groove of the bracket, and the wear of the support is spread on the steel balls, thus prolonging the service life of the linear guide. In order to eliminate the gap between the support and the guide rail, the preload can improve the stability of the guide system, and the preload is obtained. The super size steel ball is installed between the guide and the support. The diameter tolerance of the steel ball is 20 microns and the increment is 0.5 microns. The steel ball is screened and classified and installed on the guide rail respectively. The size of the pre load depends on the action on the steel ball. If the force acting on the steel ball is too large, the load of the steel ball is too long, which will lead to the increase of the movement resistance of the bracket. There is a problem of equilibrium here; in order to improve the sensitivity of the system and reduce the motion resistance, the preload should be reduced accordingly. In order to improve the retention of motion precision and precision, the two aspects of the contradiction are required.

The working time is too long, the steel ball starts to wear, and the pre load on the steel ball begins to weaken, which leads to the reduction of the movement accuracy of the working parts of the machine tool. If you want to maintain initial accuracy, you must replace the guide bracket and even replace the guideway. If the guide system has a pre load effect. The accuracy of the system has been lost. The only way is to replace the rolling element.

The design of the guide system makes the maximum contact area between the fixed element and the moving element, which not only improves the bearing capacity of the system, but also can bear the impact force produced by intermittent cutting or gravity cutting, and spread the force widely and expand the area of the bearing capacity. In order to achieve this, the groove shape of the guide system is varied and representative of two kinds. One is called the Columbia (tip arch), the shape is the extension of the semicircle, the contact point is the vertex; the other is a circular arc, which can also play the same role. No matter which structural form, the purpose is only one, striving for more rolling steel ball radius and guide rail contact (fixed element). The factors determining the performance characteristics of the system are: how to contact the rolling element with the guide way, which is the key to the problem.