Machine tool manufacturers are doing their best to ensure the accuracy of guide rail installation. Before the guide rail is processed, the guide rail and working parts have been aged to eliminate internal stress. In order to ensure the accuracy of the guide rail and extend its service life, scraping is a common process method.
1. Linear guide rail
The new guide rail system allows the machine tool to achieve rapid feed speed. When the spindle speed is the same, rapid feed is a characteristic of linear guide rails. Linear guides, like plane guides, have two basic components; one is a fixed component that serves as a guide, and the other is a moving component. In order to ensure the accuracy of the machine tool, a small amount of scraping on the bed or column is essential. Under normal circumstances, the installation is relatively simple. There is no intermediate medium between the moving element and the fixed element of the linear guide, but rolling steel balls. Because the rolling steel ball is suitable for high-speed movement, has a small friction coefficient and high sensitivity, it can meet the working requirements of moving parts, such as the tool holder of the machine tool, the carriage, etc.
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If the working time is too long, the steel ball begins to wear, and the preload acting on the steel ball begins to weaken, resulting in a reduction in the movement accuracy of the machine tool's working parts. If you want to maintain the initial accuracy, you must replace the guide rail bracket or even replace the guide rail. If the guide rail system has a preload effect. System accuracy has been lost and the only recourse is to replace the rolling elements.
2. Linear roller guide
The linear roller guide system is a combination of plane guide rails and linear roller guide rails. Rollers are installed on parallel guide rails, and rollers are used instead of steel balls to carry the moving parts of the machine tool. The advantages are large contact area, large load carrying capacity and high sensitivity. Viewed from the rear of the machine bed, the bracket and rollers are placed on the top and side surfaces of the flat guide rails. In order to achieve high precision, a wedge plate is set between the working parts of the machine tool and the inner surface of the bracket to allow the preload to act on the side of the bracket.
The working principle of a wedge plate is similar to that of an inclined iron, with the weight of the working part acting on the top surface of the bracket. Since the preload acting on the guide rail system is adjustable, the loss of the wedge plate is compensated for this. This feature is widely used in medium or large machine tools, because it responds sensitively to CNC commands, can withstand large loads, and is linear. The roller guide system can withstand high-speed operation and improve the performance of the machine tool than the traditional plane guide.
3. Inlaid steel guide rails
The most commonly used guide rail form on machine tools is the steel-inlaid guide rail, which has a long history of use. Steel-inlaid guide rails are fixed elements of the guide rail system and have a rectangular cross-section. It can be installed horizontally on the bed of the machine tool, or it can be cast into one piece with the bed, which are called steel-inlaid type or integral type respectively. Steel-inlay guides are made of steel that is hardened and ground.
The hardness is above 60 degrees on the Rockwell hardness scale. Use screws or adhesive (epoxy resin) to attach the steel-inlaid guide rail to the machine bed or the scraped mating surface of the column to ensure the best flatness of the guide rail. In this form, maintenance and replacement are convenient and simple, and it is very popular among maintenance workers.
4. Sliding guide rail
The development of traditional guide rails is first reflected in the form of sliding components and guide rails. The characteristic of sliding guide rails is the use of media between the guide rails and sliding parts. The difference in form lies in the selection of different media. Hydraulics are widely used in many rail systems.
Hydrostatic guide rail is one of them. Under the action of pressure, hydraulic oil enters the groove of the sliding element, forming an oil film between the guide rail and the sliding element, separating the guide rail and the moving element, thus greatly reducing the friction of the moving element. Hydrostatic guide rails are extremely effective for large loads and have a compensating effect on eccentric loads.
Another form of guide rail that uses oil as a medium is the dynamic pressure guide rail. The difference between the dynamic pressure guide rail and the static pressure guide rail is that the oil does not act under pressure. It uses the viscosity of the oil to avoid friction between the moving component and the guide rail. Direct contact has the advantage of saving hydraulic oil pump.
Air can also be used as the medium between the moving element and the guide rail. It also has two forms, pneumatic static pressure guide rail and pneumatic dynamic pressure guide rail. The working principle is the same as the hydraulic guide rail.
Post time: Feb-27-2024
