Linear guide rail can be understood as a type of rolling guide, which is an infinite rolling cycle of steel balls between the slider and the guide rail, allowing the load platform to easily move in high-precision linear motion along the guide rail, and reducing the friction coefficient to one-fiftieth of that of traditional sliding guide rail, which can easily achieve high positioning accuracy. The final unit design between the slider and the guide rail allows the linear guide rail to simultaneously withstand loads in various directions, such as up, down, left, right, etc. The patented reflux system and refined simplified structural design allow HIWIN's linear guide rail to have smoother and lower noise movement.
Slider - Transforms motion from a curve to a straight line. The new guide rail system enables the machine tool to achieve rapid feed speed, which is a characteristic of linear guides when the spindle speed is the same. A linear guide rail, like a planar guide rail, has two basic components; One serves as a fixed component for guidance, and the other is a moving component. As the linear guide rail is a standard component, the only thing that machine tool manufacturers need to do is to process a plane for installing the guide rail and adjust the parallelism of the guide rail. Of course, in order to ensure the accuracy of the machine tool, a small amount of scraping and grinding on the bed or column is essential, and in most cases, installation is relatively simple.
The guide rail used as a guide is hardened steel, which is finely ground and placed on the installation surface. Compared with planar guides, the geometric shape of the cross-section of a linear guide is more complex than that of a planar guide. The reason for this complexity is that grooves need to be machined on the guide to facilitate the movement of sliding components. The shape and number of grooves depend on the functions that the machine tool is supposed to perform. For example, a guide rail system that can withstand both linear forces and overturning moments has a significant difference in design compared to a guide rail that only supports linear forces.
The basic function of the fixed component (guide rail) of the linear guide rail system is like a bearing ring, a bracket for installing steel balls, with a shape of "v". The bracket wraps around the top and two sides of the guide rail. In order to support the working components of the machine tool, a set of linear guides has at least four brackets. Used to support large working components, the number of brackets can be more than four.
When the working components of the machine tool move, the steel balls circulate in the groove of the bracket, distributing the wear of the bracket to each steel ball, thereby extending the service life of the linear guide rail. In order to eliminate the gap between the bracket and the guide rail, pre loading can improve the stability of the guide rail system. The pre loading is achieved by installing oversized steel balls between the guide rail and the bracket. The diameter tolerance of the steel ball is ± 20 microns, with increments of 0.5 microns. The steel balls are sorted and installed on the guide rails, and the size of the pre applied 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 an increase in the resistance of the bracket movement, there will be a problem of balance effect; In order to improve the sensitivity of the system and reduce motion resistance, it is necessary to reduce the preload accordingly. However, in order to improve motion accuracy and accuracy retention, sufficient preload negatives are required, which are two contradictory aspects.
If the working time is too long, the steel ball begins to wear out, and the pre applied load on the steel ball begins to weaken, leading to a decrease in the movement accuracy of the machine tool's working components. If you want to maintain initial accuracy, you must replace the guide rail bracket, or even replace the guide rail. If the guide rail system already has a preload effect. The system accuracy has been lost, and the only way is to replace the rolling element.
The design of the guide rail system aims to maximize the contact area between fixed and moving components. This not only improves the system's load-bearing capacity, but also allows the system to withstand the impact force generated by intermittent or gravity cutting, spreading the force widely and expanding the load-bearing area. To achieve this, there are various groove shapes in the guide rail system, with two representative ones. One is called the Gothic (pointed arch) shape, which is an extension of a semicircle and the contact point is the vertex; The other type is a circular arc shape, which can also play the same role. Regardless of the structural form, there is only one purpose, striving for more rolling steel ball radius to contact the guide rail (fixed components). The factor that determines the performance characteristics of the system is how the rolling element contacts the guide rail, which is the key to the problem.
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