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What is a linear guide?

August 24,2022

Linear guideway, also known as line rail, slide rail, linear guideway, linear slide rail, is used in linear reciprocating motion. It has higher rated load than linear bearing, and can bear certain torque at the same time, which can realize high-precision linear motion under high load. In mainland China, it is called linear guideway; in Taiwan Province, it is generally calledlinear guidewayand linear slide rail.

principle of operation

It can be understood as a kind of rolling guide, in which steel balls roll endlessly between the slide block and the guide rail, so that the load platform can easily move linearly with high precision along the guide rail, and the friction coefficient can be reduced to one-fiftieth of that of the conventional sliding guide, which can easily achieve high positioning accuracy. The final unit design between the slider and the guide rail makes the linear guide rail bear the loads in all directions, such as up, down, left and right, etc. The patented reflux system and simplified structure design make the linear guide rail of HIWIN move more smoothly and with low noise.

Slider-Change the motion from curve to straight line.

 The new guideway system enables the machine tool to obtain fast feed speed, which is the characteristic of linear guideway when the spindle speed is the same. Linear guideway, like planar guideway, has two basic elements; One as a guide is a fixed element, and the other is a moving element. As the linear guide rail is a standard component, the only thing for machine tool manufacturers 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 of the lathe bed or column is essential. In most cases, the installation is relatively simple. The guide rail as a guide is hardened steel, which is put on the installation plane after fine grinding. Compared with the plane guide rail, the geometric shape of the cross section of the straight guide rail is more complicated than that of the plane guide rail. The reason for the complexity is that grooves need to be machined on the guide rail to facilitate the movement of the sliding elements. The shape and number of grooves depend on the functions to be completed by the machine tool. For example, the design of a guide rail system which bears both linear force and overturning moment is quite different from that of a guide rail which only bears linear force.

The basic function of the fixed element (guide rail) of the linear guide rail system is like a bearing ring, and the bracket on which the steel ball is mounted is V-shaped.

The bracket wraps the top and both sides of the guide rail. In order to support the working parts of the machine tool, a set of linear guide rails has at least four supports. For supporting large working parts, the number of brackets can be more than four.

When the working parts of the machine tool move, the steel balls circulate in the groove of the support, and the wear of the support is distributed to each steel ball, thus prolonging the service life of the linear guide rail. In order to eliminate the gap between the support and the guide rail, preload can improve the stability of the guide rail system, and the preload is obtained by installing oversized steel balls between the guide rail and the support. The diameter tolerance of steel balls is 20 microns, and the steel balls are screened and classified in increments of 0.5 microns, and loaded on the guide rails respectively. The magnitude of preload depends on the force acting on the steel balls. If the force acting on the steel ball is too large, and the pre-load time is too long, resulting in the increased resistance of the support movement, there will be the problem of balancing action; In order to improve the sensitivity of the system and reduce the movement resistance, the preload should be correspondingly reduced, while in order to improve the movement accuracy and the retention of the accuracy, it is required to have enough negative preload, which are two contradictory aspects.

When 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 the reduction of the motion accuracy of the machine tool parts.

 If you want to maintain the initial accuracy, you must replace the guide rail bracket or even the guide rail. If the guide rail system has been preloaded. The accuracy of the system has been lost, and the only way is to replace the rolling elements.

The guide rail system is designed to maximize the contact area between the fixed element and the moving element, which can not only improve the bearing capacity of the system, but also bear the impact force generated by intermittent cutting or gravity cutting, so as to spread the force widely and expand the bearing area. In order to realize this, there are various shapes of grooves in the guide rail system, and there are two representative ones, one is called Godet type (pointed arch type), the shape is an extension of a semicircle, and the contact point is the vertex; The other is circular arc, which can also play the same role. No matter which structural form, there is only one purpose, and more rolling steel ball radius should contact with the guide rail (fixing element). The key to the problem is how the rolling elements contact the guide rail.We have other guides, such as the cross roller guide.

NINGBO SIMTACH AUTO TECH CO.,LTD devotes to provide precision linear products since 2012, such as linear guide,ball screw,stepper motor,linear module,which is the critical components of Machine Tool, Food Machines,Medical Machines,Automatic industry and etc.To maximize satisfied with customer needs,SIMTACH keep improving the world class products.If you need our products, please contact our manufacturer