The Function of Guide Rails:
Guide rails, also known as slide rails, linear guide rails, or linear slides, are used in applications that require linear reciprocating motion. They have a higher rated load capacity compared to linear bearings and can withstand a certain amount of torque. They enable high-precision linear motion with efficiency and durability, and they are widely used in our daily lives. Examples of specific applications include the sliding tracks of sliding doors and the railway tracks of trains. Guide rails can be used on any machine or equipment that requires sliding motion, such as elevator guide rails and sometimes even curtains.
Types of Guide Rails:
1. Working Nature:
- Main Motion Guide Rails: The guide rail seat is responsible for the main motion, and the relative velocity between the guide rail pairs is high.
- Feed Motion Guide Rails: The guide rail seat performs the feed motion, and the relative velocity between the guide rail pairs is low.
- Positioning Guide Rails: Used only to adjust the relative positions of components, with no relative motion during machining. For example, guide rails used in lathe tailstocks.
2. Friction Nature:
- Sliding Guide Rails: The characteristic of sliding guide rails is that the friction between the working surfaces of the guide rail pairs is sliding friction.
- Sliding Guide Rails: Mixed friction guide rails, boundary friction guide rails, hydrodynamic pressure guide rails, hydrostatic pressure guide rails.
- Rolling Friction: There are rolling elements between the working surfaces of the guide rail pairs, resulting in rolling friction between the two guide rail surfaces.
- Rolling Guide Rails: Ball guide rails, roller guide rails, needle roller guide rails.
3. Force Situation:
- Open Guide Rails: Relies on external loads and the weight of components to maintain contact between the two guide rail surfaces along their entire length.
- Closed Guide Rails: Uses pressure plates as auxiliary guide rail surfaces to ensure contact between the main guide rail surfaces.
4. Motion Trajectory:
- Circular Motion Guide Rails: The relative motion trajectory of the guide rail pairs is a circle, such as the rotary table and base guide rails of a vertical lathe.
- Linear Motion Guide Rails: The relative motion trajectory of the guide rail pairs is a straight line, such as the carriage and bed guide rails of a conventional lathe.
Working Principle:
1. Linear motion is achieved by rolling on V-shaped groove roller bearings on V-shaped guide rail surfaces. With lubrication, the highest linear speed can exceed 10m/s. V-shaped guide rails are processed with precision: The V-shaped guide rail surfaces undergo surface hardening processes, with a surface hardness of HRC58-62. They can be precision ground, achieving a surface roughness of up to N5. As a result, V-shaped guide rails have been widely used in high-speed linear motion applications, providing accurate positioning.
2. The rolling elements in the roller bearings, such as steel balls or tapered rollers, do not come into direct contact with the V-shaped guide rail surfaces. Contaminants on the guide rail and the rolling elements do not have a chance to make direct contact. Additionally, the bearings have good sealing performance, preventing contaminants from entering the internal space of the roller bearings and coming into contact with the rolling elements and lubricating grease.
3. The contact between the V-shaped rollers and the V-shaped guide rail forms two lines that make a 90-degree V-angle. These two lines intersect obliquely with the central axis of the roller and rotate rapidly. The contact between these two lines and the V-shaped guide rail surface is instantaneous. They approach the guide rail surface at high speed, make momentary contact, and then leave at high speed. This way, the "lines" of the V-shaped rollers continuously "scrape" the guide rail surface, effectively ensuring the cleanliness of the guide rail surface. Therefore, V-shaped guide rails have a self-cleaning function.
