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The technical trend of rolling linear guide pair

The technical trend of rolling linear guide pair

2020-06-04

Diversification of new linear rolling guide pair

1. Development of high speed, high acceleration and deceleration rolling linear guide pair

In recent years, the high-speed development of the feeding speed of CNC machine tools, robots, electronic machinery devices and other machinery has been increased by 2 ~ 3 times, and the high-speed requirements of rolling linear guide pair used in these machinery are higher.The rolling linear guide pair realizes the basic requirements of high speed and high acceleration and deceleration: (1) no contact between rolling objects;(2) Improved lubrication performance, and long-term maintenance characteristics;(3) Smooth movement of the whole rolling body;The impact force is small circulation mechanism. 

Based on the above requirements, Japan THK company developed SSR guide pair, which adopted the following technologies:

(1) A rolling body holder is adopted in the guide pair to make the rolling body evenly arranged and carry out cycling motion smoothly.As a result, SSR guide pair is characterized by low noise, maintenance free and long service life, and can carry out ultra-high-speed linear motion at 300m/min.The noise of the guide pair is less than 50dB at 100m/min motion speed, and the friction fluctuation range is reduced to 1/5 of the previous products.In addition, a load - free test running 2800km with a grease addition of 2ml was passed. 

(2) Self-lubricating maintenance-free device.In order to make the rolling parts can work long-term stability and maintain its function, lubrication and maintenance requirements are very important, for this reason, Japan NSK company developed a linear rolling guide vice materials used resin containing lubricating oil "solid form oil" "KI series lubrication device, device seal contains the weight ratio of 70% in the lubricating oil, lubricating oil slowly overflow and maintain long-term lubrication ability. 

2. Development trend of roller linear guide pair

Roller rolling linear guide pair has the main characteristics of long life, high rigidity and low noise.It is divided into O type and X type, X type for the German INA company developed new products. 

The development trend of roller linear guide pair is mainly lubrication problem.Regular oiling is necessary, but the installation is complex and costly.To this end, Japan Memuson company independently developed a capillary lubricating body installed in the slider body, which can achieve a journey of 5 years or 20,000 km without maintenance.The QZ lubricator developed by Japan THK company contains an oil pool with fiber net and seals, which also makes the lubrication of guide pair meet the technical requirement of long-term maintenance free. 

3. Rolling linear guide pair with magnetic gate measuring system

Schneeberger developed a rolling linear guide pair called "Monorail", which combines the guiding function of linear motion with the displacement detection function of magnetic grating and digital display.The magnetized steel strip is attached to the side of the guide, and the head picking up the signal is fixed with the slider of the guide pair and moves synchronously with it.The minimum resolution of the magnetic gate measurement system is 0.001, the accuracy is 0.005, and the maximum movement speed is 3m/min.The maximum length of guide rail is 3000mm with a reference point for every 50mm."Monorail" rolling linear guide pair has the following characteristics: (1) compact structure, easy to install, small space;(2) Because the measuring system is installed in the guide rail body, significantly reduce the error, improve the accuracy of length measurement;(3) the magnetic gate sealed in the guide rail body, so as to increase the anti-interference ability of the measurement system. 

4. Development of miniature guide rail pairs

For medical treatment, semiconductor manufacturing and metering devices, THK has developed three standard products (length 100mm) with guide width of 1mm, 2mm and 4mm respectively. They have the following characteristics:

(1) Ultra-small: LM guide subseries section size of the smallest, high reliability of ultra-micro products.It meets the requirements of light weight and space saving.Low rolling resistance;Capable of bearing loads in all directions;(4) excellent corrosion resistance: LM guide and ball are used martensitic stainless steel, excellent corrosion resistance, the most suitable for use in medical equipment and cleaning workshop. 

More personalized research and development

1. Development of high-precision technology

(1) Optimization design of "transition curve". 

Japanese scholars found through experiments that the design of the ball circulation loop of the rolling linear guide directly affects the high-frequency vibration and the change of dynamic friction in the feeding motion, and the change of dynamic friction frequency is related to the diameter of the steel ball, indicating that the steel ball has impact friction in the running raceway. 

The paper discusses the transition curve form of the circulation loop of the auxiliary slider of the rolling linear guide rail. With the method of given clearance, the circular concave cylindrical groove is adopted for the circulation loop of the steel ball, and the center line of each cylinder (namely the central track line of the grinding wheel) is adopted multi-section single and double circular spline curve, and it is optimized.Thus, the impact is reduced and the high-frequency vibration amplitude of the dynamic friction is reduced, which is of great significance for improving the precision of linear feed. 

(2) The influence of pitch of screw hole and counterbore depth of screw hole on the accuracy of lower groove of guide. 

In order to adapt to the impact of various machine tools on the guide rail, meet the needs of stable work, improve the shock absorption, reasonable design guide pair installation connection bolt fatigue strength is necessary.According to the test of NSK Company in Japan, under the condition of different screw hole mounting pitch and counterbore depth of screw hole, the deformation of groove under guide rail was measured. 

It can be seen that the pitch of screw holes and the countersunk depth of threaded holes have a great influence on the accuracy of the lower groove of the guide, so it is very important to select the proper pitch of screw holes and countersunk depth of threaded holes to improve the precision of rolling linear guide pair. 

(3) Research on ultra-precision positioning device.Through experimental research, the feed device consisting of rolling linear guide pair and linear motor has realized 1nm ultra-precision transmission.At the same time, the theoretical analysis of the nonlinear characteristics of rolling linear guide pair in the case of small displacement provides a basis for the design of the precise transmission device composed of rolling linear guide pair. 

2. Linear motion unit

The linear motion unit realizes the modularization and standardization of the linear motion platform, and users can choose the appropriate type and stroke according to the needs of the job content to form different structures.Linear motion units are used in automation and precision measurement, such as XYZ multi-axis platforms, automatic assembly and delivery systems, semiconductor manufacturing equipment and photoelectric products. 

The ambient temperature of continuous use of the linear motion unit can be up to 80℃, and the short-time operation temperature can be up to 100℃.If all forces and torques are within the maximum value of the linear motion element, it may in principle be installed in any position.The maximum feeding speed of the linear motion unit is 60~90m/min, the acceleration is 0.6~2.0g, and the positioning accuracy is 20~25.In the future, the linear motor can replace the linear motor driven by straight line, and its feeding speed can reach 80~200m/min, acceleration of 1~10g and above, and positioning accuracy can reach 0.5~0.005 (or even higher).In this way, higher requirements are put forward for the rolling linear guide pair which is used together. 

3. Interchangeable guide rail series

In order to meet customer delivery time, accelerate the capital turnover cost reduction, interchangeability of production is the best way, that is to say, but will guide rail and slide block manufacturing, inventory, respectively corresponding to the order contract may group assembly do short-term delivery from inventory standard, in addition, the replacement product to the customer maintenance replacement is also very convenient.In order to meet the requirements of interchangeability, it is necessary to accurately process and measure the slot position size, improve the processing precision of guide rail and slider, and strengthen the inventory management of semi-finished products, and build a full computer management system. 

The green design that incline to environmental protection more

1. The noise problem of rolling linear guide pair is well solved

Yamata et al. proved that the main cause of the noise of rolling linear guide pair was the collision between the rolling body, the end cover and the racetrack.For sound pressure levels in the range of 100 ~ 20 000HZ, they can be reduced by loading a lighter ceramic ball (Si5 N4).When the motion velocity is within the range of 0.3~1.17m/s, the rolling noise of the steel ball is 60.0 ~ 76.9dB, while the noise of the ceramic ball is 55 ~ 71dB, and the average noise reduction is 4.5dB. 

2. Facing the requirements of green environmental protection

Semiconductor and LIQUID crystal manufacturing equipment have very high requirements for green environment. Under such environment, the rolling linear guide pair USES vacuum fluorin lubricant, because the amount of dust produced by fluorin lubricant is very small.However, the durability and rust resistance of fluorin lubricants are not high, and the resistance increases when running at high speed. Due to the above reasons, the use of low-dust lubricants and KI series of sealing lubricants can obtain the same characteristics of vacuum lubricants. 

In order to achieve the requirements of green and environmental protection and a variety of use requirements, anti-rust ability is very important to improve.For example, stainless steel guide pair, using markov system stainless steel materials, with the same standard guide pair rated load and other functions.The guide pair must be surfacing to prevent rust and light reflection.Based on rust prevention function, durability and cost, electrolytic rust prevention black film surface treatment technology with chrome plating is recommended.Also can use the fluorinated low temperature spray coating with a layer of fluorin resin coating, so that the rust performance is further improved, in medicine, food machinery can be widely used.


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