Working principle of linear guide:
It can be understood as a rolling guide, which is an infinite rolling cycle of steel balls between the slider and the guide rail, so that the load platform can easily move along the guide rail with high precision and linearity, and reduce the friction coefficient to the usual traditional sliding guide. One fiftieth, can easily achieve high positioning accuracy. The design of the final unit between the slider and the guide rail allows the linear guide rail to withstand the loads of up, down, left, right and other directions at the same time. The patented recirculation system and the simplified structure design make HIWIN's linear guide rail have smoother and lower noise movement.
Slider-Changes the motion from a curve to a straight line. The new guide rail system enables the machine tool to obtain fast feed speed. In the case of the same spindle speed, fast feed is the characteristic of linear guide rails. Linear guides, like flat guides, have two basic components; one is a fixed component and the other is a moving component. Since linear guides are standard components, for machine tool manufacturers. The only thing to do is to machine the plane of the mounting rail and the parallelism of the adjusting rail. Of course, in order to ensure the accuracy of the machine tool, a small amount of scraping on the bed or column is essential. In most cases, the installation is relatively simple. The guide rail used as the guide is hardened steel, which is placed on the installation plane after fine grinding. Compared with the plane guide, the geometry of the linear guide cross-section is more complicated than that of the plane guide. The reason for the complexity is that grooves need to be machined on the guide to facilitate the movement of the sliding element. The shape and number of grooves depends on the machine tool to be completed Function. For example, a rail system that bears both linear force and subversive torque is compared with a rail system that only bears linear force. The design is very different.
The basic function of the fixed element (rail) of the linear guide system is like a bearing ring, a bracket for mounting a steel ball, and the shape is "v". The bracket wraps the top and sides of the rail. In order to support the working parts of the machine tool, a set of linear guides has at least four brackets. For supporting 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 extending the service life of the linear guide. In order to eliminate the gap between the bracket and the guide rail, pre-loading can improve the stability of the rail system and obtain pre-loading. An oversized steel ball is installed between the guide rail and the bracket. The tolerance of the steel ball diameter is ± 20 microns. In 0.5 micron increments, the steel balls are screened and sorted and installed on the guide rails respectively. The size of the pre-load depends on the force acting on the steel ball. If the force acting on the steel ball is too large and the pre-loading time is too long, resulting in increased support resistance of the bracket, a problem of balance action will occur; in order to improve the sensitivity of the system and reduce the motion resistance, the pre-load must be reduced accordingly In order to improve the motion accuracy and accuracy retention, it is necessary to have enough pre-plus negative numbers, which are two contradictory aspects.
When the working time is too long, the steel balls begin to wear, and the preload applied to the steel balls begins to weaken, resulting in a reduction 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 already has pre-loading 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, which not only can improve the load-bearing capacity of the system, but also can withstand the impact force generated by intermittent cutting or gravity cutting, widely spread the force, and expand the bearing The area of force. In order to achieve this, the groove shape of the guide rail system is various, and there are two representative ones. One is called Gothic (pointed arch), the shape is a semicircular extension, and the contact point is the vertex; the other The shape is circular arc, which can also play the same role. No matter what kind of structure, the purpose is only one, and strive to make more rolling steel ball radius contact with the guide rail (fixed element). The factors that determine the performance characteristics of the system are: how the rolling elements contact the guide rail is the key to the problem.