Performance characteristics and application of the

2022-09-22
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With the continuous development of modern manufacturing technology, great changes have taken place in the traditional manufacturing industry. Numerical control technology, electromechanical integration and industrial robots have been more widely used in production. At the same time, the positioning accuracy, guiding accuracy and feed speed of the mechanical transmission mechanism are constantly improving, which has made great changes to the traditional guiding mechanism. Since its commercialization in 1973, the rolling linear guide rail pair has gradually replaced the traditional sliding linear guide rail with its unique characteristics, and has been widely used in industrial production. It meets the requirements of today's machinery for high precision, high speed, energy conservation and shortening the product development cycle. It has been widely used in various heavy combined machining machines, numerical control machines, high-precision EDM cutting machines, grinders, industrial upper beams, tensile experimental space robots formed by double columns and worktables, and even general industrial machinery

performance characteristics of rolling linear guide rail pair

1 High positioning accuracy

the movement of rolling linear guide rail is realized by rolling steel balls. The friction resistance of guide rail pair is small, and the difference between dynamic and static friction resistance is small. It is not easy to crawl at low speed. With high accuracy of repeated positioning, it is suitable for moving parts with frequent starting or reversing. The positioning accuracy of the machine tool can be set to the super micron level. At the same time, according to the needs, the preload is appropriately increased to ensure that the steel ball does not slide, realize smooth movement, and reduce the impact and vibration of the movement

2. Small wear

for the fluid lubrication of the sliding guide surface, the motion accuracy error caused by the floating oil film is inevitable. In most cases, fluid lubrication is limited to the boundary area, and direct friction caused by metal contact is inevitable. In this friction, a lot of energy is wasted by friction loss. On the contrary, because the friction energy consumption of rolling contact is small, the friction loss of rolling surface is also reduced correspondingly, so the rolling linear guide system can be in a high-precision state for a long time. At the same time, due to the use of little lubricating oil, it is very easy to design, use and maintain the lubrication system of the machine tool

3. Adapt to high-speed movement and greatly reduce the driving power

due to the small friction resistance of the machine tool with rolling linear guide, the required power source and power transmission mechanism can be miniaturized, the driving torque can be greatly reduced, the power required by the machine tool can be reduced by 80%, and the energy-saving effect is obvious. It can realize the high-speed movement of the machine tool and improve the working efficiency of the machine tool by 20-30%

4. Strong bearing capacity

the rolling linear guide rail pair has good bearing performance and can bear forces and torque loads in different directions, such as up, down, left and right, as well as bumping torque, shaking torque and swinging torque. Therefore, it has good load adaptability. Proper preloading in design and manufacture can increase damping, improve vibration resistance, and eliminate high-frequency vibration. The sliding guide rail can bear less lateral load in the direction of parallel contact surface, which is easy to cause poor operation accuracy of the machine tool

5. It is easy to assemble and interchangeable

the traditional sliding guide must scrape and grind the guide surface, which is both time-consuming and time-consuming. Once the accuracy of the machine tool is poor, it must scrape and grind again. The rolling guide rail is interchangeable. As long as the slider or guide rail or the whole rolling guide rail pair is replaced, the machine tool can regain high precision

as mentioned above, the relative motion of the ball between the guide rail and the slider is rolling, which can reduce the friction loss. Generally, the rolling friction coefficient is about 2% of the sliding friction coefficient, so the transmission mechanism using rolling guide rail is far superior to the traditional sliding guide rail

selection method of rolling linear guide rail pair

rolling linear guide rail pair has the characteristics of large bearing capacity, high contact rigidity and high reliability. It is mainly used on the bed, workbench guide rail and column upper and lower lifting guide rail of machine tool. We can choose according to the load size, load direction, impact and vibration size

1. Stress direction

because there are usually 4 rows of arc raceways on the slider and guide rail of the rolling linear guide rail pair, it can bear the load and overturning torque in 4 directions. The bearing capacity of the guide rail increases with the increase of the center distance of the raceway

2. Load size

different specifications of rolling linear guide rail have different bearing capacity, which can be selected according to the load size. In order to make each rolling linear guide have a relatively ideal service life, the rated life and rated hour life can be calculated according to the approximate formula provided by the selected manufacturer, so as to give a reasonable maintenance and replacement cycle. The rolling resistance of each slider shall also be considered after the slider bears the load, and all switches shall be placed in the closed state to calculate the rolling resistance, so as to determine the reasonable driving force

3. Selection of preload

select the appropriate preload value according to the impact, vibration and accuracy requirements of the design structure

current situation of rolling linear guide rail pairs

at present, foreign manufacturers of rolling linear guide rail pairs are mainly concentrated in the United States, Britain, Germany, Japan and other countries. The manufacturing of rolling linear guide rail pair in China is still in the initial stage, and there is still a gap compared with foreign countries, mainly manifested in: less varieties, small output, low service life, high noise, and the processing technology is not as advanced as foreign countries. Domestic enterprises represented by Nanjing craft equipment manufacturing factory and Guangdong Kaite Precision Machinery Co., Ltd. are trying to narrow this gap, and some of their products have reached the international advanced level

development trend of linear rolling guide rail pair

new types and functions of linear rolling guide rail pair are constantly emerging, and are developing towards combination, integration, high speed, low noise and intelligence

1. Rolling linear guide rail pair held by ball

thk company adopts ball cage to form an integral whole with ball to keep the ball moving smoothly and eliminate the mutual friction between balls. It has developed an ultra-high speed linear SSR guide rail pair with low noise, maintenance free, long service life and speed up to 300m/min, and has begun to promote it. The guide rail pair realizes that the noise is less than 50dB at the speed of 100m/min, and the friction fluctuation amplitude is reduced to 1/5 of the previous products. In addition, it passed the test of adding 2cm3 grease once and running for 2800km. In the future, the linear motion guide rail pair with ball cage will gradually become the mainstream of high-end CNC machine tools

2. Linear motor ensures the safety of operators and users and the use of linear guide rail

the slide system using integrated linear motor has the characteristics of compact structure and high power during operation. At the same time, the positioning accuracy of the slide system is also improved. SKF Linear System Co., Ltd. cooperates with pratec linear motor manufacturer, and has begun to promote the integrated linear motor slide system products in 1996

k intelligent drive system

Japan's THK intelligent drive system (intelligent actuato is classified according to different experimental materials of springs), which takes DC servo motor as power, adopts precision ball screw pair and new rolling linear guide rail pair to realize linear motion. It is a very compact combined component. It has rich control functions and convenient operation characteristics, and can be controlled by CNC

4. Hybrid table

Japan has developed a new type of rolling linear guide rail auxiliary table, which has a set of sliding electromagnetic block device, which can be sucked onto the guide rail during positioning processing to increase friction, so as to improve the anti vibration performance of the system, so it is also called hybrid table system

5. Rolling linear guide rail pairs made of new materials

due to the diversity of user requirements and different use environments, rolling linear guide rail pairs made of new materials appear. For example, for products made of stainless steel, the guide shaft, sliding block, steel ball, sealing end and retainer are made of stainless steel, while the reverser is made of synthetic resin, so the corrosion resistance is improved. For high temperature and vacuum applications, the inverter can be made of stainless steel. In addition, the rolling linear guide rail made of ceramic materials will be developed and applied

6. Rolling linear guide rail pair with magnetic grating measurement system

schneeber AG of Switzerland and Heidenhain company jointly developed a rolling linear guide rail pair called "monorail", which combines the guiding function of linear motion with the displacement detection function of magnetic grating digital display. The magnetized steel strip is pasted on the side of the guide rail, and the magnetic head that picks up the signal is fixed with the slider of the guide rail pair and moves synchronously with it

7. Linear transmission combination unit

German Neff company launched the "Wiesel" linear transmission combination unit in the mid-1980s and obtained the German patent. It installs the ball screw pair in the rectangular inner cavity made of aluminum alloy, inlays the rolling guide rail on the upper end of the aluminum alloy frame, the slider on the guide rail is fixed with the nut, and the ball screw pair is equipped with the sliding plate for reciprocating linear motion. The linear transmission device composed of rolling elements has the characteristics of high efficiency and high speed. It is an ideal actuator for industrial robots, automated three-dimensional warehouses, factory automation (FAC), etc

at present, the use of linear guide rail in harsh environments, such as high dust concentration, strong acid, strong alkali and high corrosion, has certain limitations. However, with the improvement of linear guideway technology and its high-speed and controllability, as well as its rich types and functions, it can be expected that this mechanism, as a functional component, will be more and more used in mechanical equipment such as CNC machine tools. (end)

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