The trend of modern machine tool LM linear rolling guide technology

THK LM linear rolling guide system products have been honored to win the honor of the top ten brands with satisfaction in the first "rolling function component survey" results conference and industry forum held in Shanghai. We believe that this is the long-time favor and recognition of the high-precision, high-rigidity, high-speed THK products of the Chinese customers, and it is also a spur and encouragement.

In order to meet the diversified needs of customers in the right and timely manner, THK has vigorously implemented the most suitable production plan for on-site production overseas, especially in China. Since 1996, Dalian THK, which manufactures ball screw pairs, has been established, THK Wuxi, which manufactures LM rolling guides, and THK Liaoning, which manufactures LM rolling guides. In addition to THK Shanghai, in addition to THK Shanghai, it has set up THK Beijing; THK Chengdu; THK Guangzhou; THK Shenyang and other 20 branches to deal with the vast Chinese customers. The pulse of THK China is in harmony with the rhythm of the development of the Chinese market. All practitioners are committed to making greater contributions to the development of China's mechanical products with a high degree of originality and excellent spirit of struggle.


1. Technical trends of modern CNC machine tools
LM linear rolling guide system products have many excellent features, which have many advantages for machine manufacturers and final users. Therefore, they are used in industrial machinery such as industrial robots, semiconductor manufacturing equipment, and liquid crystal manufacturing equipment, or in super high-rise buildings. The vibration-free devices, high-speed pendulum trains, buses, automatic doors, kitchen lift cabinets, subway station safety tips, and other consumer livelihoods are widely used as mechanical linear motion guides. It goes without saying that the LM linear scrolling guidance system has become one of the most important rolling features of modern machine tools (Fig. 1).

In the 21st century, modern machine tools have also evolved with each passing day due to the needs of society and increasingly fierce competition. It can be seen from the world's three major international machine tool exhibitions that the market demands high-precision, high-speed, high-effort, high-efficiency machine tools. Another time the clamping can meet the requirements of processing very complex shapes, and the energy saving, low environmental load and space saving requirements considering the global environmental factors are also increasing. At the same time, enterprises are facing increasingly fierce competition, rapidly developing their own technologies and products, and reluctantly leading their own competitiveness to the world. Therefore, the technology of modern machine tools has developed in the following three major directions:

1. High-speed, high-precision evolution to improve production efficiency.
2. The evolution of compounding and complex shape processing has improved the high performance of electronic and optical parts.
3. Earth environment problems, environmentally friendly mechanical products are energy-saving, labor-saving, design, installation and maintenance.
The above three major external factors lead the machine tool enterprises to develop modern CNC machine tools from the following aspects;
A. Environmental protection, energy saving * Semi-dry processing, dry processing (chip suction, Magnesium processing, low chip grinding)
* Save space (compact machinery, etc.)
*No lubrication, no oil pressure (saving energy, self-lubricating, etc.)
B. Compounding, multi-functionalization, engineering intensification * Grinding + turning, turning + milling, multi-face + multi-axis machining
C. High-speed technology* Shorten machining time and non-machining time (linear high-speed feed guidance, high-speed spindle, indexing table, etc.)
D.IT application technology* Remote control diagnosis and processing response, etc. Intelligent production control center, etc.
E. Ultra-precision machining machinery * nano-machining technology

In summary, the technical trends, as an indispensable LM linear rolling guidance system for modern machine tools, continue to carry out research and development according to market demand, and get a technical evolution. THK also developed the latest LM linear rolling guide pair, one of the most important rolling features of modern machine tools, according to the evolution of modern machine tools.


2-1 Basic Technology In the past, the basic technical requirements for the LM linear guide rail pair for the linear guide surface of the machine tool were high rigidity, high load capacity, high productivity, compactness, etc., and all of these conditions were reasonably balanced. Machine tools are extremely important technical factors. With the evolution of the machine tool, the LM linear rolling guide has been continuously researching and developing in accordance with the requirements of the times or the requirements of the leading era. As a LM linear guide rail pair applied to modern machine tools, it satisfies the reasonable balance of the linear guide surface of the machine tool, and it can be said that the epoch-making linear guide technology position has been established (Fig. 2). The evolution of machine tools is still going on in the future, but the basic part of a well-balanced linear-oriented technology will not be fundamentally improved. With the evolution of the elements of the LM linear rolling guide pair and the optimal shape for the overall balance, it is still necessary to continuously research and develop to improve its performance.

2-2 High-speed, grease-maintaining technology At this stage, in order to meet the requirements of high-speed and grease-preserving technology at the same time, it is a linear guide technology in which a spacer is inserted between the rolling elements of a steel ball or a roller. Rolling element spacer retainer technology Humans have been used in rolling bearings for rotating mechanisms at the end of the 19th century. They have been used by technicians to date, and their rolling element spacer retainer technology has been fully verified and recognized. However, the rolling element spacer retaining technique is employed in the LM linear rolling guide pair of the linear guide surface, and there are many technical problems to be solved, such as the complexity of rolling infinite rolling of the rolling element and the high durability of the cage connecting portion. Therefore, the practical use of this technology has taken a long process of research and development (Figure 3). THK took the lead in developing the retainer-type LM linear rolling guide pair in the world and put it on the market. It was unexpectedly adopted by machine tools and industrial machinery in a short period of time and produced many features. For example, the adjacent rolling elements and the retainer and the curved spacer that controls the rotation of the rolling elements form a grease storage bag shape, which achieves the long-term residual effect of the grease, and realizes a structure that can be maintenance-free for a long period of time (Fig. 4). . In addition, the spacers between the rolling elements are integrally formed by the joints on both sides of the bank to form a retainer chain, so that the phenomenon that the rolling elements lose the number of revolutions generated when the rolling elements enter the unloaded area is eliminated. It can achieve sensitive response even with slight linear motion, improve tracking performance, greatly reduce the quadrant protrusion generated during arc compensation, and achieve high-precision contour processing. For the same reason, the ability to feed at high speed can be fully utilized. Ultra-high-speed motion of 300m/min (5m/s) has been successfully achieved on the high-speed endurance tester.

2-3 Minimum amount of lubrication technology The lubrication of the rolling elements is basically the formation of an oil film by residual lubrication at the metal contact. Therefore, in order to achieve the purpose of lubrication, it is necessary to inject grease into the inner space of the rolling block of the LM linear rolling guide pair, and it is proved by the test that the injected grease actually forms an oil film at the contact portion, and only accounts for about 30% to 50%. Therefore, the LM linear guide rail pair without the spacer retainer requires periodic injection of grease or a thin oil PUMP for intermittent fuel supply system design. However, the intermittent supply of oil or the periodic injection of grease is as described above, resulting in more than half of the waste, especially the wasted oil flowing out of the machine periphery, while polluting the environment. For this reason, the next-generation mechanical products have become an urgent issue for solving environmental protection problems and solving non-lubrication and maintenance-free maintenance. THK developed a technology to solve the above lubrication problems and developed a self-lubricating device (Fig. 5).

The self-lubricating device is internally filled with a high-oil-filled mesh, and the interior is filled with a special grease having a relatively high viscosity. The internal space oil control panel is divided into two, and the high oil-containing mesh network forms the property of coating grease when it is in contact with the raceway. The grease filled in the high oil-filled mesh is controlled by the oil quantity control panel, and the amount of oil required to coat the raceway with the slider is applied. To this end, the oil lubrication technology is directly applied within the closest distance of the metal contact portion of the rolling element, which solves the problem of wasting grease and greatly reduces the production cost. Applying the minimum amount of oil required to the raceway, raising environmental awareness, long-term maintenance-free maintenance, reducing the cost of production, and its self-lubricating technology is increasingly favored by the market.

2-4 dustproof technology
The LM linear rolling guide pair is a steel ball or a roller as a rolling element. It is necessary to prevent external factors such as foreign matter from entering the rolling element contact portion of the slider to avoid affecting the rolling performance. In particular, when used in machine tools, there are many external disturbances such as chips generated during cutting, grinding debris generated during grinding, sand grains and coolant, and so on. environment of. In order to achieve the high speed and high precision that modern machine tools are pursuing, it is necessary to prevent foreign factors such as foreign objects from entering the inside of the slider.

In the past, two or three layers of dust-proof rubber side sealing plates were used, and various metal side sealing plates were used. However, due to the material quality problem of the rubber and the sealing contact structure of the steel ball returning ball guiding portion and the track reinforcing thickness, the sliding resistance of the LM linear rolling guide pair is added, which is easy to produce poor problems such as lowering the positioning accuracy and losing the amount of crawling. So that Jingyuan uses its products.

To this end, the newly developed oil-containing low-resistance resin material has a self-lubricating function, and the frictional resistance is greatly reduced when it is in contact with the rail, which is a laminated contact seal of a three-layer laminated structure for the LM linear rolling guide. Device. This latest dust-proof device is made of oil-containing low-resistance resin material and can be completely in contact with the outer diameter of the rail, achieving high dust resistance and minimal control of frictional resistance. In addition, due to the three-layer laminated structure, the dustproof performance is also exponentially improved (Fig. 6).

2-5 High-precision technology In the high-precision field where ultra-precision machining is considered, the LM linear guide rail pair uses a rolling structure in which the rolling elements are infinitely circulated, and the vibration of the table or the like is generated to cause the surface of the machined surface. The reason for the poor texture is that there is a tendency to be respected.

For this reason, a linear guide system in which the LM linear rolling guide pair is assembled into a table is taken as an example. It is necessary to first understand the rolling element load, the 変 shape and the contact angle of all the rolling element contact portions inside the LM linear rolling guide pair, and to clearly understand the amount of table clamping caused by the external force and moment of the linear guiding system. This makes it clear that the force and moment reconciliation relations in the linear guidance system can determine the load distribution theory. When the table moves, the position of the rolling element is scrolled, and the load distribution state is degraded, and it can be analyzed that the table is in a subtle posture degeneration state in continuity. In other words, when the rolling element is circulated, the cause of the vibration of the table generated in the moving state can be analyzed, so that the design inside the linear guiding system that minimizes the vibration amplitude can be established to obtain the best performance result.

In order to confirm the technical performance as described above, THK has specially manufactured measurement accuracy using a one-axis table for analysis. The device is designed for high-precision measurement, and uses an electrostatic capacity type non-contact measuring instrument and a one-axis intelligent workbench that is not affected by the swaying device. The measuring speed is measured by a load cell, and the measuring speed is extremely low at 1 mm/s ( Figure 7).

A standard linear guide system and a special linear guide system with a design value inside the linear guide system that minimizes the vibration amplitude after analysis. Both linear guide systems are operated under the same mechanical and the same test conditions. Measurement of vibration amplitude of the table. The measurement results can be clearly seen at a glance by the vertical line segments of the same type of linear guide system (Fig. 8) and the special type linear guide system (Fig. 9) shown in the drawing. It goes without saying that the measurement results obtained by the two figures are very similar.

This measurement negates the previous part that the vibration amplitude of the LM linear rolling guide pair is generally best to achieve an acceptable value of 0.1 μm, and it is also confirmed that the flying precision of 0.01 μm to 0.001 μm is improved. The above measurement results show that even in the field of high-precision machining, the understanding of the LM linear rolling guide pair is more and more accepted by the market.

2-5 High-reliability technology uses LM linear rolling guides for general performance such as linear accuracy, low table vibration, rigidity, and longevity. Especially for the accuracy and other aspects, there is a popular saying that "do not need to know." However, it can now be solved by theoretical analysis, and it can also be verified by countless experimental data, and the results of high reliability theory analysis can be obtained. Nowadays, such theoretical analysis is also rapidly evolving. With the development of the ever-changing linear guidance system technology in the world, it will be selected in the best form according to the design needs of the user, and the human will reach a low level. Waste, efficient design techniques.

THK hopes that the manufacturing companies of machine tools and industrial machinery will raise various issues for improvement, which is the beginning of the development of THK new products. In the future, we will continue to research and develop from the aspects of environmental protection, compactness and miniaturization, ultra-high precision, and intelligentization of various components, and continue to provide the market with a new generation of LM linear rolling guidance systems that meet these requirements.


Picture description

1. THK LM linear rolling guide system product group 2. Machining master machine ball retainer type LM guide pair 3. Ball retainer type LM linear rolling guide system 4. The axial section of the ball cage is sectional view 5. Ball holder grease storage bag 6. QZ type self-lubricating device for LM linear rolling guide pair 7. LM linear rolling guide pair with dust-proof LaCS type laminated contact scraper 8. Measuring accuracy with the workbench 9. The vibration amplitude of the table of the standard linear guide system is 10. The vibration amplitude of the table of the special linear guiding system The trend of the modern machine tool LM linear rolling guiding technology
THK LM linear rolling guide system products have recently won the reputation of the top ten brands with good intentions in the first “rolling function component survey” results conference held in Shanghai Minhang. We believe that this is the long-time favor and recognition of the high-precision, high-rigidity and high-speed THK products of the Chinese customers. It is also a spur and encouragement.
THK has been implementing the most suitable production plan for on-site production overseas, especially in China, in order to be close to customers and to meet the diversified needs of customers. Since 1996, Dalian THK, which manufactures ball screw pairs, has been established; THK Wuxi and THK Liaoning, which manufacture LM rolling guides, have been established. In addition to THK Shanghai, the company has established 20 branches in THK Beijing, THK Chengdu, THK Guangzhou and THK Shenyang in a few years to serve the vast Chinese customers. The pulse of THK China is in harmony with the pulse of the development of the Chinese market. All practitioners are committed to making greater contributions to the development of China's mechanical products with a high degree of originality and excellent spirit of struggle.
1. Technical Trends of Modern CNC Gold Cutting Machines
LM linear rolling guide system products have many excellent features, so they are used in industrial machinery such as industrial robots, semiconductor manufacturing equipment, and liquid crystal manufacturing equipment, or in vibration-free installations, high-speed swing trains, buses, and automatic vehicles in super high-rise buildings. Doors, kitchen lift cabinets, safety tips for subway stations, etc. are widely used as mechanical linear motion guides. It goes without saying that the LM linear rolling guide system has become one of the most important rolling features of modern machine tools (Fig. 1).
In the 21st century, modern machine tools have been developed with each passing day. It can be seen from the world's three major international machine tool exhibitions that the market demands high-precision, high-speed, high-effort, high-efficiency machine tools. In addition, the requirements for energy saving, low environmental load, and space saving that meet the requirements of processing very complex shapes and considering the global environmental factors are also increasing. In order to face increasingly fierce competition, companies are rapidly developing their own technologies and products to reinforce their own competitiveness. The technology of modern machine tools is developing in the following three directions:
(1) High speed, high precision and high efficiency.
(2) Processing of composite and complex shapes requires high performance of electronic and optical parts.
(3) In order to protect the global environment, environmentally-friendly mechanical products must be energy-saving, labor-saving, design, installation and maintenance.
The above three major external factors have led machine tool companies to develop modern CNC machine tools from the following aspects:
(1) Environmental protection and energy saving 1 Semi-dry processing/dry processing (chip suction, Magnesium processing, low chip grinding).
2 save space (compact machinery, etc.).
3 No lubrication, no oil pressure (saving energy, self-lubricating, etc.).
(2) Compounding, multi-functionalization, engineering intensive grinding + turning, turning + milling, multi-face + multi-axis machining (3) High-speed technology to shorten machining time and non-machining time (linear high-speed feed guidance, high-speed spindle, indexing table Wait)
(4) IT application technology, remote control diagnosis and processing response, and other intelligent production control centers, etc. (5) Ultra-precision processing machinery, nano-machining technology, technical trends described above, as an indispensable LM linear rolling guide system for modern machine tools, rapid research and development, technology The development is constantly evolving. In order to meet the development needs of modern machine tools, THK has developed one of the most important rolling features in modern machine tools – the latest LM linear rolling guide pair.
2. The latest LM linear rolling guide pair (1) Basic technology Previously, the basic technical requirements for the LM linear rolling guide pair for the linear guide surface of the machine tool were high rigidity, high load capacity, high productivity, compactness, etc., and all these conditions were properly balanced. The combination of ground is an extremely important technical factor for machine tools. With the evolution of the machine tool, the LM linear rolling guide pair has carried out research and development with repeated technical requirements that meet the requirements of the times or the requirements of the leading era. As a LM linear guide rail pair applied to modern machine tools, it has been fully balanced and placed on the linear guide surface of the machine tool. It can be said that the epoch-making linear guide technology position has been established (Fig. 2). The evolution of machine tools is still going on in the future, but the basic part of a well-balanced linear-oriented technology will not be fundamentally improved. With the evolution of the elements of the LM linear rolling guide pair and the optimal shape for the overall balance, it is still necessary to continuously research and develop to improve its performance.
(2) High-speed and grease-retaining technology At this stage, in order to simultaneously satisfy the high-speed and maintain grease technology, a linear guide technology in which a spacer is inserted between rolling elements of a steel ball or a roller is known. The rolling element spacer retainer technology has been applied to rolling bearings for rotating mechanisms at the end of the 19th century, and has been adopted by the skilled person to date. The rolling element spacer retaining technology has been fully verified and recognized. However, the rolling element spacer retaining technique is employed in the LM linear rolling guide pair of the linear guide surface, and there are many technical problems to be solved, such as the complexity of rolling infinite rolling of the rolling element and the high durability of the cage connecting portion. Therefore, the practical use of this technology has taken a long process of research and development (Figure 3). THK took the lead in developing the retainer-type LM linear rolling guide pair in the world and put it on the market. Unexpectedly, it was adopted by machine tools and industrial machinery in a short time and produced many characteristics. For example, the adjacent rolling elements and the retainer and the curved spacer that controls the rotation of the rolling elements form a grease storage bag shape, which achieves the long-term residual effect of the grease, and realizes a structure that can be maintenance-free for a long period of time (Fig. 4). (Figure 5). In addition, the spacers between the rolling elements are integrally formed by the connecting belts on both sides to form a retainer chain, so that the phenomenon that the rolling elements lose the number of revolutions generated when the rolling elements enter the unloaded area is eliminated. It can achieve sensitive response even with slight linear motion, improve tracking performance, greatly reduce the quadrant protrusion generated during arc compensation, and achieve high-precision contour processing. For the same reason, the ability to feed at high speed can be fully utilized. Ultra-high-speed motion of 300m/min (5m/s) has been successfully achieved on the high-speed endurance tester.
(3) The minimum amount of lubrication technology The lubrication of the rolling elements is basically the formation of an oil film by residual lubrication at the metal contact. Therefore, in order to achieve the purpose of lubrication, it is necessary to inject grease into the inner space of the rolling block of the LM linear rolling guide pair, and it is proved by the test that the injected grease actually forms an oil film at the contact portion, and only accounts for about 30% to 50%. Therefore, the LM linear guide rail pair without the spacer retainer requires periodic injection of grease or a thin oil PUMP for intermittent fuel supply system design. However, the intermittent supply of oil or the periodic injection of grease is as described above, resulting in more than half of the waste, especially the wasted oil flowing out of the machine periphery, while polluting the environment. For this reason, the next-generation mechanical products have become an urgent issue for solving environmental protection problems and solving non-lubrication and maintenance-free maintenance. THK developed a technology to solve the above lubrication problems and developed a self-lubricating device (Fig. 6).
The self-lubricating device is filled with a high oil-containing fiber web, and the inside is filled with a special grease having a relatively high viscosity. The internal space oil control panel is divided into two, and the high oil-containing fiber mesh forms the property of coating grease when it is in contact with the raceway. The grease filled in the high oil-containing fiber web is controlled by the oil quantity control panel, and the amount of oil required to coat the raceway is carried out together with the slider. For this reason, the direct oil lubrication technology in the closest distance of the metal contact portion of the rolling element is realized, the problem of wasting grease is solved, and the production cost is greatly reduced. Applying the minimum amount of oil required to the raceway, raising environmental awareness, long-term maintenance-free maintenance, reducing overall production costs, and its self-lubricating technology is increasingly favored by the market.
(4) Dust-proof technology The LM linear guide rail pair is a steel ball or a roller as a rolling element. It is necessary to prevent external factors such as foreign matter from entering the rolling element contact portion of the slider to avoid affecting the rolling performance. In particular, when used in machine tools, there are many external factors such as grinding debris, grinding wheel sand and cutting fluid generated during grinding, which can be regarded as extremely harsh and cruel environment for rolling elements. In order to achieve the high speed and high precision that modern machine tools pursue, it is necessary to prevent these foreign objects from entering the inside of the slider.
In the past, two or three layers of dust-proof rubber side sealing plates were used, and various metal side sealing plates were used. However, due to the material problem of the rubber and the sealing contact structure of the steel ball returning ball guiding position and the track reinforcement thickness, the sliding resistance of the LM linear rolling guide pair is added, which is easy to cause poor positioning accuracy and creeping and creeping problems. Yu Jingyuan uses its products.
To this end, the newly developed oil-containing low-resistance resin material has a self-lubricating function, and the frictional resistance is greatly reduced when it is in contact with the rail, which is a laminated contact seal of a three-layer laminated structure for the LM linear rolling guide. Device. This latest dust-proof device is made of oil-containing low-resistance resin material and can be completely in contact with the outer diameter of the rail, achieving high dust resistance and minimal control of frictional resistance. In addition, due to the three-layer laminated structure, the dustproof performance also increases exponentially (Fig. 7).
(5) High-precision technology In the high-precision field where ultra-precision machining is considered, the LM linear guide rail pair uses a rolling structure in which the rolling elements are infinitely circulated, and the vibration of the table or the like causes the surface of the machined surface to be poor. Because of this, there is a tendency to be respected.
For this reason, a linear guide system in which the LM linear rolling guide pair is assembled into a table is taken as an example. First of all, it is necessary to know the rolling element load, the amount of deformation and the contact angle of all the rolling element contact parts inside the LM linear rolling guide pair, and to clearly understand the table displacement caused by the external force and moment of the linear guiding system. . This makes it clear that the force and moment reconciliation equations in the linear guidance system can be used to determine the load distribution theory. When the table moves, the position of the rolling element is scrolled, and the load distribution state is degraded, and it can be analyzed that the table is in a subtle posture degeneration state in continuity. In other words, when the rolling element is circulated, the cause of the vibration of the table generated in the moving state can be analyzed, so that the design inside the linear guiding system that minimizes the vibration amplitude can be established to obtain the best performance result.
In order to confirm the technical performance as described above, THK has specially manufactured measurement accuracy using a one-axis table for analysis. The device is designed for high-precision measurement, and uses an electrostatic capacity type non-contact measuring instrument and a one-axis intelligent workbench that is not affected by the driving device. The measuring speed is measured by a load cell, and the measuring speed is extremely low at 1 mm/s (Fig. 8).
The standard linear guide system and the special linear guide system designed to minimize the vibration amplitude after analysis. The two linear guide systems are all under the same machine under the same test conditions. Measurement of vibration amplitude of the table. The measurement results can be clearly seen at a glance by the vertical line segments of the same type of linear guide system (Fig. 9) and the special type linear guide system (Fig. 10) shown in the drawing. It goes without saying that the measurement results obtained by the two figures are very similar.
This measurement negates the previous part that the vibration amplitude of the LM linear guide rail pair is generally only 0.1 μm, and the flying precision of 0.01 to 0.001 μm is also confirmed. The above measurement results show that even in the field of high-precision machining, the recognition of the LM linear rolling guide pair is becoming more and more accepted by the market.
(6) High reliability technology When using the LM linear rolling guide pair, the performance is generally pursued, such as low linear accuracy, table vibration, rigidity, and life. Especially for the accuracy and other aspects, there is a popular saying that "do not need to know." However, it can now be solved by theoretical analysis, and it can also be verified by countless experimental data, and the results of high reliability theoretical analysis can be obtained. Nowadays, such theoretical analysis is also rapidly evolving. With the development of the world's new moon-oriented linear guidance system technology, it will be selected in the best form according to the design needs of the user. Achieve low waste, high efficiency design technology.
THK hopes that the manufacturing companies of machine tools and industrial machinery will raise various issues for improvement, which is the beginning of the development of THK new products. In the future, we will continue to research and develop from the aspects of environmental protection, compactness and miniaturization, ultra-high precision, and intelligentization of various components, and continue to provide the market with a new generation of LM linear rolling guide systems that meet these requirements.
Picture description

11. THK LM linear rolling guide system product group 12. Ball holder type LM guide pair for machining machine. Ball retainer type LM linear rolling guide system 14. The axial section of the ball cage is sectional view 15. Ball holder grease storage bag 16. QZ type self-lubricating device for LM linear rolling guide pair. LM linear rolling guide pair with dustproof LaCS type laminated contact scraper 18. Measuring accuracy with a workbench 19. The vibration amplitude of the table of the standard linear guide system is 20. Table vibration amplitude of special linear guiding system

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