Machine tool builders are most concerned with the accuracy, rigidity and service life of the machine tool, and pay little attention to the rail system. However, the guide rails provide a reliable basis for the realization of machine tool functions. Various types of machine tool working parts use the control shaft to move on the specified guide rail. The machine tool designer selects various different types of rail system according to the type and purpose of the machine tool. The following three types are widely used; A rolling element guide rail composed of a guide rail, a linear rolling guide, and a combination of a recirculating roller and a flat guide rail.
I. Functions of the guide rails <br> Although the form of the guide rail system is various, the work is the same, and the machine tool components move on the designated rail system, just like the train travels along the rail in the specified direction. It mainly reflects the following three basic functions:
(1) guiding the movement of the carrier;
(2) providing a smooth moving surface for the carrier;
(3) Transfer the force generated by the cutting of the machine tool to the foundation or the bed to reduce the impact of the impact on the passively machined parts. The movement along the rail system is mostly linear and a few are arc motions. Many techniques for linear guides can directly apply curved guides.
Second, the classification of the rails <br> Machine tool manufacturers are doing their best to ensure the accuracy of the rail installation. Prior to the machining of the guide rails, the guide rails and working components have been aged to eliminate internal stresses. In order to ensure the accuracy of the guide rail and prolong the service life, scraping is a common process.
1, linear guide
The new rail system allows the machine to achieve fast traverse speeds. At the same spindle speed, rapid traverse is a linear guide. Linear guides, like flat guides, have two basic components; one for the fixed component and the other for the moving component. In order to ensure the accuracy of the machine tool, a small amount of scraping of the bed or column is essential. In general, the installation is relatively simple.
Instead of an intermediate medium between the moving element and the fixed element of the linear guide, a rolling steel ball is used. Because the rolling steel ball is suitable for high-speed movement, small friction coefficient and high sensitivity, it can meet the working requirements of moving parts, such as tool holders and carriages of machine tools.
When the working time is too long, the steel ball begins to wear, and the preload applied to the steel ball begins to weaken, resulting in a decrease in the movement accuracy of the working parts of the machine tool. If you want to maintain the initial accuracy, you must replace the rail brackets or even replace the rails. If the rail system is preloaded. The system accuracy has been lost, the only way is to replace the rolling elements.
2, linear roller guide
The linear roller guide system is a combination of a flat guide rail and a linear roller guide rail. The roller is mounted on the parallel guide rail, and the roller is used to carry the moving parts of the machine. The utility model has the advantages of large contact area, large carrying load and high sensitivity. From the tail of the bed, the bracket and the roller are placed on the top and side of the plane rail. In order to obtain high precision, a wedge plate is arranged between the working part of the machine tool and the inner surface of the bracket, so that the preload is applied to the side of the bracket. The working principle of the wedge plate is similar to that of the inclined iron, and the weight of the working part acts on the top surface of the bracket. Since the preload applied to the rail system is adjustable, the loss of the wedge is compensated for. This feature is widely used on medium or large machine tools because it is sensitive to CNC commands and bears large loads. The roller guide system can withstand high speeds and improve machine performance over conventional flat guides.
3, inlaid steel rail
The most common form of guide rails on machine tools is steel-inlaid rails, which have a long history of use. The inlaid steel rail is a fixed component of the rail system and has a rectangular cross section. It can be mounted horizontally on the machine bed or integrated into the bed, known as steel or monolithic. The inlaid steel guide rails are made of steel and are hardened and ground. Hardness is more than 60 degrees Rockwell hardness, and the steel guide rail is attached to the machine bed or the scraped column mating surface with screws or adhesive (epoxy resin) to ensure the best flatness of the guide rail. This form is convenient and simple to repair and replace, and is very popular with maintenance workers.
4, sliding rail
The development of conventional guide rails is first manifested in the form of sliding elements and guide rails. The characteristics of the sliding guide rails are that the medium is used between the guide rails and the slide members, and the difference in form is to select different media.
Hydraulics are widely used in many rail systems. The hydrostatic guide rail is one of them. The hydraulic oil enters the groove of the sliding member under pressure and forms an oil film between the guide rail and the sliding member to separate the guide rail from the moving member, thereby greatly reducing the frictional force of the moving member. The hydrostatic guide rail is extremely effective for large loads and compensates for eccentric loads. For example, a large sand box is just at the end of the machine stroke when it is being machined. The load rail can increase the oil pressure and keep the rails in a state of horizontal load. Some horizontal boring and milling machines use this technique to compensate for the drop in spindle speed during deep hole machining.
Another form of rail that uses oil as a medium is a dynamic pressure rail. The difference between a dynamic pressure rail and a hydrostatic rail is that the oil does not act under pressure. It uses the viscosity of the oil to avoid the movement between the moving element and the rail. The direct contact has the advantage of saving the hydraulic pump.
Air can also be used to move the medium between the component and the rail. It is also available in two versions, a pneumatic hydrostatic rail and a pneumatic hydrodynamic guide, which work in the same way as a hydraulic rail.
5, other forms of guide rails
Another type of guide rail commonly used on machine tools is the dovetail guide rail, which is generally used for positioning of moving parts of machine tools. For example: the tailstock of the turning center, the rail system can move the tailstock over it or move it to the desired position to support the part being machined and then quickly clamp it. Many accessories for machine tools, such as positioning table, rotary table or rotating shaft, also use dovetail guide rail as positioning component. Then clamp it to the desired position. If the reciprocating stroke of the machine is long, the V-shaped guide soft is used, such as a surface grinder and a planer. The advantage is that the V-rail system is well guided and can withstand gravity cutting. Some adopt a combination of a V-shaped guide rail and a flat guide rail, a V-shaped guide rail serves as a guide, and a flat guide rail serves as a support body.
In order to ensure the life of the rail system. Maintenance is critical. The guide rail is one of the precision parts of the machine tool. It is impossible to have 100% dust protection and dust pollution. Therefore, users should check and maintain regularly. Linear guides and linear roller guides require regular lubrication. Many steel ball and roller sections of linear guide systems are fitted with grease fittings that are attached to the bracket. Regardless of the type of rail system used, maintaining good lubrication of the rolling elements can reduce wear on the rail system and extend the holding time of the machine.
I. Functions of the guide rails <br> Although the form of the guide rail system is various, the work is the same, and the machine tool components move on the designated rail system, just like the train travels along the rail in the specified direction. It mainly reflects the following three basic functions:
(1) guiding the movement of the carrier;
(2) providing a smooth moving surface for the carrier;
(3) Transfer the force generated by the cutting of the machine tool to the foundation or the bed to reduce the impact of the impact on the passively machined parts. The movement along the rail system is mostly linear and a few are arc motions. Many techniques for linear guides can directly apply curved guides.
Second, the classification of the rails <br> Machine tool manufacturers are doing their best to ensure the accuracy of the rail installation. Prior to the machining of the guide rails, the guide rails and working components have been aged to eliminate internal stresses. In order to ensure the accuracy of the guide rail and prolong the service life, scraping is a common process.
1, linear guide
The new rail system allows the machine to achieve fast traverse speeds. At the same spindle speed, rapid traverse is a linear guide. Linear guides, like flat guides, have two basic components; one for the fixed component and the other for the moving component. In order to ensure the accuracy of the machine tool, a small amount of scraping of the bed or column is essential. In general, the installation is relatively simple.
Instead of an intermediate medium between the moving element and the fixed element of the linear guide, a rolling steel ball is used. Because the rolling steel ball is suitable for high-speed movement, small friction coefficient and high sensitivity, it can meet the working requirements of moving parts, such as tool holders and carriages of machine tools.
When the working time is too long, the steel ball begins to wear, and the preload applied to the steel ball begins to weaken, resulting in a decrease in the movement accuracy of the working parts of the machine tool. If you want to maintain the initial accuracy, you must replace the rail brackets or even replace the rails. If the rail system is preloaded. The system accuracy has been lost, the only way is to replace the rolling elements.
2, linear roller guide
The linear roller guide system is a combination of a flat guide rail and a linear roller guide rail. The roller is mounted on the parallel guide rail, and the roller is used to carry the moving parts of the machine. The utility model has the advantages of large contact area, large carrying load and high sensitivity. From the tail of the bed, the bracket and the roller are placed on the top and side of the plane rail. In order to obtain high precision, a wedge plate is arranged between the working part of the machine tool and the inner surface of the bracket, so that the preload is applied to the side of the bracket. The working principle of the wedge plate is similar to that of the inclined iron, and the weight of the working part acts on the top surface of the bracket. Since the preload applied to the rail system is adjustable, the loss of the wedge is compensated for. This feature is widely used on medium or large machine tools because it is sensitive to CNC commands and bears large loads. The roller guide system can withstand high speeds and improve machine performance over conventional flat guides.
3, inlaid steel rail
The most common form of guide rails on machine tools is steel-inlaid rails, which have a long history of use. The inlaid steel rail is a fixed component of the rail system and has a rectangular cross section. It can be mounted horizontally on the machine bed or integrated into the bed, known as steel or monolithic. The inlaid steel guide rails are made of steel and are hardened and ground. Hardness is more than 60 degrees Rockwell hardness, and the steel guide rail is attached to the machine bed or the scraped column mating surface with screws or adhesive (epoxy resin) to ensure the best flatness of the guide rail. This form is convenient and simple to repair and replace, and is very popular with maintenance workers.
4, sliding rail
The development of conventional guide rails is first manifested in the form of sliding elements and guide rails. The characteristics of the sliding guide rails are that the medium is used between the guide rails and the slide members, and the difference in form is to select different media.
Hydraulics are widely used in many rail systems. The hydrostatic guide rail is one of them. The hydraulic oil enters the groove of the sliding member under pressure and forms an oil film between the guide rail and the sliding member to separate the guide rail from the moving member, thereby greatly reducing the frictional force of the moving member. The hydrostatic guide rail is extremely effective for large loads and compensates for eccentric loads. For example, a large sand box is just at the end of the machine stroke when it is being machined. The load rail can increase the oil pressure and keep the rails in a state of horizontal load. Some horizontal boring and milling machines use this technique to compensate for the drop in spindle speed during deep hole machining.
Another form of rail that uses oil as a medium is a dynamic pressure rail. The difference between a dynamic pressure rail and a hydrostatic rail is that the oil does not act under pressure. It uses the viscosity of the oil to avoid the movement between the moving element and the rail. The direct contact has the advantage of saving the hydraulic pump.
Air can also be used to move the medium between the component and the rail. It is also available in two versions, a pneumatic hydrostatic rail and a pneumatic hydrodynamic guide, which work in the same way as a hydraulic rail.
5, other forms of guide rails
Another type of guide rail commonly used on machine tools is the dovetail guide rail, which is generally used for positioning of moving parts of machine tools. For example: the tailstock of the turning center, the rail system can move the tailstock over it or move it to the desired position to support the part being machined and then quickly clamp it. Many accessories for machine tools, such as positioning table, rotary table or rotating shaft, also use dovetail guide rail as positioning component. Then clamp it to the desired position. If the reciprocating stroke of the machine is long, the V-shaped guide soft is used, such as a surface grinder and a planer. The advantage is that the V-rail system is well guided and can withstand gravity cutting. Some adopt a combination of a V-shaped guide rail and a flat guide rail, a V-shaped guide rail serves as a guide, and a flat guide rail serves as a support body.
In order to ensure the life of the rail system. Maintenance is critical. The guide rail is one of the precision parts of the machine tool. It is impossible to have 100% dust protection and dust pollution. Therefore, users should check and maintain regularly. Linear guides and linear roller guides require regular lubrication. Many steel ball and roller sections of linear guide systems are fitted with grease fittings that are attached to the bracket. Regardless of the type of rail system used, maintaining good lubrication of the rolling elements can reduce wear on the rail system and extend the holding time of the machine.
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