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Robot development -- lead screw and guide rail

2022-07-28 03:24:00 【worthsen】

1 Introduce

1.1 Screw

The lead screw is a transmission pair part that turns rotary motion into linear motion , On the machine tool , It is an important component used to complete the feeding movement . The machine tool lead screw should not only be able to accurately transmit motion , And it should be able to transmit certain power . So it's in accuracy 、 Strength and wear resistance , They all have certain requirements .
Lead screw is a kind of part with high precision , It can accurately determine the coordinate position of the workbench , Convert rotary motion into linear motion , But also to transmit a certain amount of power , So in accuracy 、 There are high requirements for strength and wear resistance . therefore , The processing of the lead screw should be carefully considered from the blank to the finished product , To improve its machining accuracy .

1.2 Guide （ Slide track ）

Guide （VAVguide） It is a groove or ridge made of metal or other materials , affordable 、 Fix 、 A device that guides a moving device or device and reduces its friction . Guide rail is also called slide rail 、 Linear guide 、 Linear slide , For linear reciprocating motion , It has a higher rated load than linear bearings , At the same time, it can bear a certain torque , It can realize high-precision linear motion under high load . Longitudinal groove or ridge on the surface of guide rail , For guiding 、 Fix machine parts 、 Special equipment 、 Instruments, etc .

2 classification

2.1 Classification of lead screws

1 Sliding screw （ Trapezoidal screw ）

Due to the simple structure of the sliding lead screw , Easy to manufacture , So it is widely used in machine tools .
The tooth type of sliding lead screw is trapezoid . This type of tooth is more effective than triangle tooth , Good transmission performance , High precision , Convenient processing and other advantages .
The friction of sliding lead screw is large , Low transmission efficiency , It's usually 26%~46%, Wear fast , Creeping occurs in low speed and fine adjustment transmission , Self locking , Poor positioning accuracy and axial stiffness .
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2 Rolling screw

Rolling screw is divided into ball screw and roller screw . Compared with roller screw, ball screw , Little friction , High transmission efficiency , High precision , Therefore, it is commonly used , But its manufacturing process is more complex .

2.1 Ball screw

Ball screws are generally made of screws 、 Nut 、 steel ball 、 Prepress tablet 、 Reverser 、 Dust catcher composition , Because the steel ball is placed between the nut and the lead screw, the sliding friction is replaced by rolling friction , It has very little frictional resistance , It is difficult to stick and slip ; High transmission efficiency , Generally can achieve 90% To 96%, For trapezoidal screw 2~4 times ; At the same time, it also improves the poor positioning and easy damage of the sliding lead screw , Its Good wear resistance , Long life , High precision , By preloading the ball moderately , Higher rigidity can be obtained . Therefore, it is widely used in all kinds of CNC machine tools and other electromechanical integration equipment , Its manufacturing process is more complex than sliding screw , But the interchangeability of products is good .
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2.2 Roller screw

Planetary roller screw with its high load , Impact resistance , Small volume , high velocity , Low noise , High precision , Long life and other outstanding advantages , Get more and more attention . This kind of planetary roller lead screw is used in the landing gear of some aircraft , The machining accuracy is very high , But at present, China can't produce superior .
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3 Static pressure lead screw

Hydrostatic screw has many advantages , It is often used in the feed mechanism of precision machine tools and CNC machine tools . Its thread profile is the same as that of standard trapezoidal thread . But the tooth shape is higher than the standard thread of the same specification 1.5～2 times , The purpose is to obtain a good oil seal and improve the bearing capacity . But the adjustment is troublesome , And you need a hydraulic system , Process complex , The high cost .

The design of static pressure lead screw uses the principle of static pressure support , According to different supporting fluids, it is divided into hydrostatic screw and aerostatic screw .

The oil chamber of the hydrostatic lead screw is located on the nut , The hydrostatic oil film is located between the hydrostatic nut and the precision lead screw , The hydrostatic nut and the screw itself do not contact , So there is no wear . The friction of the static pressure lead screw is proportional to the speed , At low speed, it is almost zero . Its excellent shock absorption performance completely eliminates the vibration and noise of the ball screw . Where high feed thrust and frequent vibration load are required , The feed transmission system is required to have high passive stiffness , And good shock absorption , Static pressure screw is the best choice . When positioning accuracy and universality are important , Or when the vertical axis is applied , Static pressure screw is also particularly suitable .

However, the hydrostatic screw device is larger , There must be an oil pump 、 Accumulator 、 Liquid circulation device 、 Many auxiliary devices such as cooling device and filter device , And its hydrostatic oil chamber is difficult to process , And there are environmental pollution problems . Located in gepingen, Germany （Göppingen） Of Hydrostatik Schönfeld This small company is currently the only supplier , And it's expensive , So at present, the high-end linear drive market is occupied by some famous linear motor manufacturers .

Aerostatic screw and hydrostatic screw belong to the field of fluid lubrication , Compared with hydrostatic screw , The gas film plays a supporting and lubricating role in the aerostatic screw , Due to the strong compressibility of air , The air film thickness is smaller than the oil film in the hydrostatic screw , Therefore, the positioning accuracy is higher , But at the same time, the stiffness and bearing capacity are also reduced . The aerostatic screw device is simple , There is no reflux device , There is no environmental pollution , These are the advantages of aerostatic screw , Another disadvantage of it is that it requires high accuracy , Processing is very difficult . So at present, in terms of aerostatic screw , China has not yet entered the practical stage . And compared with foreign countries , The aerostatic screw studied in China differs greatly in both structure and performance .
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2.2 Classification of guide rails

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The guide rail is usually made by machining or cold drawing , Its bearing strength should generally be 370～520MPa. According to its transverse section shape, it mainly includes ：T V-shaped guide rail 、L（ Or triangle ） V-shaped guide rail 、U V-shaped guide rail 、O V-shaped guide rail 、 Hollow guide rail, etc . The common guide rail section shape is shown in the figure .
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3 Introduction to top ten brands

Taiwan Shangyin HIWIN

Taiwan Shangyin HIWIN The brand is a world-famous linear guideway brand , Its products include ： linear guide rail 、 Ball screw 、 Linear module 、 Linear motor, etc , Linear slide rails and ball screws are on the market ,HIWIN Occupy a part of the market , Products are widely used in CNC machine tools , Woodworking machinery , Carry 、 Conveying machinery , Precision measuring instruments, etc , All fields requiring precise linear transmission and positioning .

Taiwan High Technology GAOJ-K

GAOJ-K Since its establishment 20 Over the years , We are always committed to the R & D and manufacturing of precision transmission components , And obtained dozens of related patents from the mainland and Taiwan , Products include linear slide rails 、 Ball screw 、 Ball spline 、 Single axis robot 、 Cross roller guide , Screw support and other precision transmission components , Up to styles 200 More than , Senior's products have fully replaced other brands of transmission accessories , Products are widely used in semiconductor industry , New energy , The Internet of things , Hundreds of industries such as industrial equipment , To meet the needs of our customers , On 2018 In, it established the Asia Pacific General Distribution and set up production bases in many places around the world , The brand always sticks to “ Three high and one skill ” The product concept of , That is, high quality , High cost performance , High standard of service , Technology stability enables intelligent manufacturing , Its business covers dozens of countries and regions around the world , And has branches and offices , Product pass ISO 9001 International quality certification and ISO14001 Environmental certification .

Japan THK

THK Our creative ideas and unique technology have made the company a global developer of linear motion (LM) The pioneer of guideway mechanism . Now ,THK Of LM Guideway equipment has become an indispensable component in mechanical and electronic systems in various industries .THK Many other unique mechanical components have also been developed , Including ball spline 、 Ball screw and connecting rod ball .

Taiwan ABBA

ABBA linear guide rail (ABBALinear) It is produced by Taiwan Guobiao Linear Technology Co., Ltd . Founded on 1999 Since its establishment in , It is the first professional linear guideway manufacturer in Taiwan with four row bead self lubrication patents and actually introduced into mass production .

Japan NSK

NSK Numerous new bearings have been developed , Meet the needs of users all over the world , And has made great contributions to industrial development and technological progress . meanwhile NSK With its technical advantages in precision machining , Continuously develop energy-saving and efficient bearings for household appliance motors 、 Dental medical bearings 、 Car parts 、 Precision mechanical components 、 And other sophisticated products , Actively carry out diversified operations in electronic applications and other fields .