Machine Tool Guide Rail

Introduction

A part that supports and guides a moving member to move along a certain trajectory is referred to as a guide rail pair, and is also often referred to simply as a guide rail.

The moving trajectory of the moving parts have straight lines, circles or curves. The rolling circular guides can be used to roll the thrust bearings, and the curved guide rails are rarely used in machinery.

The guide rail is a very important part in the machine and is especially important in machine tools.

The machining accuracy of the machine tool is directly related to the accuracy of the guide rail. For the precision machine tools produced in small batches, the machining work of the guide rails accounts for about 40% of the total machining workload of the machine tool.

Moreover, once the rail is damaged, the maintenance will be very difficult.

According to the kinematics principle, the so-called guide rail is a device that constrains the moving member to only one degree of freedom.

The guide rail surface of the guide rail pair disposed on the support member is a guide surface, which is called a static guide rail and it is relatively long; the other guide rail surface is disposed on the moving member, which is called a movable guide rail and it is relatively short.

The moving member with the moving rail is often called the worktable, the sliding table, and the common rail surface has a plane and a circular arc surface.

The circular arc guide surface constitutes a cylindrical guide rail; different flat guide rail faces are combined, and the friction between the rectangular guide rail faces is called a sliding guide rail. The rolling element is placed between the guide rail faces, and the friction is converted into rolling friction is called a rolling rails.

The guide rails are available in closed and open styles. Closed rails can withstand overturning moments, while open rails cannot.

Working principle

1) According to the nature of work, it can be divided into:

Main motion guide

The main motion of the moving rail seat is relatively high, and the relative speed between the rail pairs is high.

Feed motion guide

The moving rail is used for the feed motion, and the relative movement speed between the rail pairs is low.

Displacement rail

It is only used to adjust the relative position between the parts, and there is no relative movement during processing, such as the guide rail for the tailstock of the lathe.

2) According to the nature of friction:

Sliding rail

The characteristic of the sliding guide rail is that the friction property between the auxiliary working faces of the guide rail is sliding friction

Sliding rail

  • Hybrid friction guide
  • Boundary friction guide
  • Hydrodynamic guide
  • Hydrostatic guide
  • Rolling friction: There are rolling bodies between the auxiliary working faces of the guide rails, so that friction between the two rail faces is rolling friction.
  • Rolling guide
  • Roller guide
  • Needle guide

3) According to the force situation:

Open rails—rails that rely on external loads and component weight to keep the two rail faces in length.

Closed guide rail—Use the pressure plate as the auxiliary guide rail to ensure the guide rail of the main guide surface.

4) According to the movement trajectory:

Circular motion guide

The relative movement of the guide rail pair is a circle, such as the faceplate and base rail of the vertical lathe.

Linear motion guide

The relative motion of the guide rail pair is a straight line. Such as the slide of the ordinary lathe and the bed rail.