CNC machine Guide rail: a groove or ridge of metal or other material that holds, holds, guides, and reduces friction in a moving device or device.A longitudinal groove or ridge on the surface of a guide, used for guiding and fixing machine parts, special equipment, instruments, etc.The guide rail, also known as sliding rail, linear guide rail, linear sliding rail, is used in linear reciprocating motion. It has a higher rated load than the linear bearing and can bear a certain torque at the same time. It can realize high-precision linear motion under high load.
The guide device in the mechatronics system is usually the guide rail, and the guide rail is composed of moving parts and guide parts.When various machines are running, the guide rail pair ensures the correct movement track of the actuator.And the guide pair also affects the motion characteristics of the actuator.
The guide rail, as a guide device, shall have the following properties:
(1) guiding accuracy mainly guides the accuracy of the trajectory of the orbit.The main factors that affect the guide precision are: the geometric precision and contact precision of the guide, the structure form of the guide, the rigidity and thermal deformation of the guide and its supporting parts, the oil film thickness and its rigidity between the static (dynamic) pressure guide pairs, etc.
(2) accuracy maintenance is mainly determined by the wear resistance of the guide rail.The wear resistance is related to the material of the guide rail, the friction property of the guide rail pair, the pressure on the guide rail and its distribution law.
(3) stiffness includes the guide's own stiffness and contact stiffness.It mainly depends on the shape and size of the guide rail, the connection mode of the supporting parts and the force condition.
(4) when the stationary moving guide rail moves at low speed or is slightly displaced, it is easy to produce frictional self-excited vibration, that is, crawling phenomenon.Crawling will decrease the positioning accuracy or increase the surface roughness value of the workpiece to be processed.
Lubrication and protection of guide rail:
1) function of guide rail lubricant
(1) make the guide track work as close to the liquid friction state as possible, so as to reduce the friction resistance, reduce the driving power and improve the efficiency.
(2) reduce guide rail wear and prevent guide rail corrosion.The flowing oil also washes.
(3) avoid crawling under low speed and heavy load, and reduce vibration.
(4) reduce friction heat at high speed and reduce thermal deformation.
2) selection of lubricating oil for machine tool guide rail
According to experience and data, the following factors should be considered when selecting lubricating oil for machine tool guide rail.
(1) both as a hydraulic medium and guide oil lubricating oil.According to the needs of different types of machine tool guide rail, it can be used as the lubricating oil of hydraulic medium at the same time, which not only meets the requirements of guide rail, but also meets the requirements of hydraulic system.For example, machine tools, such as coordinate boring machine guide rail oil viscosity (50 ℃) should choose high (40 ~ 90 was/s), but like all kinds of grinding machine, often will guide rail lubricating oil supply by hydraulic system, and higher requirements of the hydraulic system, must be satisfied, the guide rail of a hydraulic oil viscosity (50 ℃) elected to lower (20 ~ 40 was/s), namely the viscosity in the hydraulic system.
(2) choose the viscosity according to the sliding speed and average pressure.
(3) according to the actual application of guide rail lubrication of machine tools at home and abroad to choose.When choosing to use guide rail lubricants, you can also refer to the examples of practical application of guide rail lubrication of existing machine tools at home and abroad.
The guide rail of CNC machine tool usually adopts centralized oil supply and automatic drip lubrication.Domestic lubrication equipment XHZ series thin oil centralized lubrication device.The device is composed of a quantitative lubricating pump, an oil filter, a liquid level detector, an oil detector, a pressure relay, a progressive oil distributor and a fuel tank.The oil supply is fixed and fixed on the guide surface.
Solid lubrication is to cover the solid lubricant on the friction surface of the guide rail, forming a bonding type of solid lubrication film, in order to reduce friction, reduce wear.There are many kinds of solid lubricants, which can be divided into metal class, metal compound class, inorganic class and organic class according to the basic raw materials.Solid lubricant powder is added to grease to enhance or improve the bearing capacity, aging performance and high and low temperature performance of grease.
2.Protection of guide rail
The protection of the guide rail can prevent or reduce the auxiliary wear of the guide rail and prolong the life of the guide rail.Protective devices are manufactured by specialized manufacturers and can be purchased externally.
There are many ways to protect the guide rail. The common protective cover is shown in the figure.CNC machine tools.Especially in the central cutting, iron filings, coolant is very much, easy to enter the guide rail, increase the guide rail wear;When the iron filings are large, the table is raised to affect the precision of the guide rail, so usually use steel plate telescoping protective cover.
Guide rail type:
Guide rail is usually made by machining or cold drawing, and its supporting strength should be generally 370 ~ 520MPa.According to the shape of its transverse section, there are: T - shaped guide, L (or triangle) shaped guide, U - shaped guide, O - shaped guide, hollow guide and so on.
Common guide rail:
The working surface of l-shaped guide rail, u-shaped guide rail and o-shaped guide rail is generally not processed, and it is usually used for some elevators with low speed and low requirements for smooth operation, such as debris ladder and construction ladder.The hollow guide rail is mostly used for the heavy guide rail with low speed.T-shaped guide rail has good bending resistance and processing property, and is widely used as elevator guide rail.
Rail naming has four elements:
First element: add "one" after the standard number coexist;
The second element: guide rail shape "T";
The third element: the circular value of the back width of the guide rail.
The fourth element: processing technology, /A for cold drawing processing, /B for mechanical processing, /BE for high quality mechanical processing.