The working principle of linear guide

2021-10-07 14:49
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It can be understood as a kind of rolling guide, in which the steel ball rolls infinitely between the slider and the guide rail, so that the load platform can easily move with high precision along the guide rail and reduce the friction coefficient to the usual traditional sliding guide. One-fiftieth, high positioning accuracy can be easily achieved. The design of the terminal unit between the slider and the guide rail makes the linear guide rail bear the load in all directions, such as up, down, left, and right at the same time. The patented recirculation system and simplified structural design make the linear guide more smooth and low-noise movement.


Slider-the movement is transformed from a curve to a straight line. The new guide rail system enables the machine tool to obtain rapid feed speed. In the case of the same spindle speed, rapid feed is a characteristic of linear guides. Linear guides, like flat guides, have two basic elements; one as a guide is a fixed element, and the other is a moving element. Since the linear guide is a standard component, it is a machine tool manufacturer. The only thing to do is to process the plane of a mounting rail and adjust the parallelism of the rail. Of course, in order to ensure the accuracy of the machine tool, a small amount of scraping of the bed or column is essential. In most cases, the installation is relatively simple. The guide rail as a guide is hardened steel, which is placed on the installation plane after fine grinding. Compared with flat guide rails, the cross-sectional geometry of linear guide rails is more complicated than that of flat guide rails. The reason for the complexity is that grooves need to be machined on the guide rails to facilitate the movement of sliding elements. The shape and number of grooves depend on the machine tool to complete. Function. For example: a guide rail system that bears both linear force and subversive moment is compared with a guide rail that only bears linear force. The design is very different.


The basic function of the fixed element (guide rail) of the linear guide system is like a bearing ring, and the bracket for mounting the steel ball is shaped like a "v". The bracket wraps the top and both sides of the rail. In order to support the working parts of the machine tool, a set of linear guide has at least four supports. Used to support large working parts, the number of brackets can be more than four.


When the working parts of the machine tool move, the steel balls circulate in the groove of the bracket, and the wear of the bracket is distributed to each steel ball, thereby prolonging the service life of the linear guide. In order to eliminate the gap between the bracket and the guide rail, the preload can improve the stability of the guide rail system and the preload can be obtained. It is to install an oversized steel ball between the guide rail and the bracket. The diameter tolerance of the steel ball is ±20 microns, with 0.5 micron increments. The steel balls are screened and classified and installed on the guide rails respectively. The size of the preload depends on the force acting on the steel balls. If the force acting on the steel ball is too large and the preload time is too long, resulting in increased stent movement resistance, there will be a balance problem; in order to improve the sensitivity of the system and reduce the movement resistance, the preload should be reduced accordingly , And in order to improve the accuracy of the motion and the retention of the accuracy, it is required to have enough pre-adding negative numbers, which are two contradictory aspects.


If the working time is too long, the steel ball begins to wear, and the preload on the steel ball begins to weaken, resulting in a decrease in the movement accuracy of the working parts of the machine tool. If you want to maintain the initial accuracy, you must replace the rail bracket, or even replace the rail. If the rail system has a preload effect. The accuracy of the system has been lost, and the only way is to replace the rolling elements.


The design of the guide rail system strives to have the largest contact area between the fixed element and the moving element. This not only improves the carrying capacity of the system, but also the system can withstand the impact force generated by intermittent cutting or gravity cutting, spread the force widely, and expand the bearing capacity. The area of force. In order to achieve this, there are various groove shapes of the guide rail system. There are two representative ones, one is called Gothic (pointed arch), the shape is the extension of a semicircle, and the contact point is the apex; the other The species is arc-shaped and can also play the same role. No matter what kind of structure, there is only one purpose, and strive to have more rolling steel ball radius contact with the guide rail (fixed element). The factor that determines the performance characteristics of the system is: how the rolling elements contact the guide rail, which is the key to the problem.