h 上海充通大学 Shanghai Jiao Tong University Mechanical Design and Manufacturing II Power/Energy Transmission: Power Screws(传动螺旋)
1 Power/Energy Transmission: Power Screws（传动螺旋） Mechanical Design and Manufacturing II
上潘充通大学 Shanghai Jiao Tong University Lectures Power/Energy Conversion Power/Energy (Electrical Motors) Transmission Gears,Cam,Linkage, Belt Drives, Power Screws) Transmission Joints (Fasteners, Support Structural Connectors) (Bearings) Support (Frames) Tools Statics,Dynamics, Stress Analysis,etc. 2
2 Lectures Power/Energy Conversion (Electrical Motors) Transmission Support (Bearings) Joints (Fasteners, Connectors) Structural Support (Frames) Tools Statics, Dynamics, Stress Analysis, etc. Power/Energy Transmission (Gears, Cam, Linkage, Belt Drives, Power Screws)
上海充通大学 Shanghai Jiao Tong University Power Screw Principlesl >The screw thread is one of the most important inventions ever made >Power screw using the principle of a screw thread and its mating nut >Used to convert rotation to linear motion >in actuators,production machines (Lead screws)and jacks,etc. >Transmit power,exert the necessary force to move a machine element along a desired path. >Capable of very large mechanical advantages, can lift or move large loads,the speed is often slows
3 The screw thread is one of the most important inventions ever made Power screw using the principle of a screw thread and its mating nut Used to convert rotation to linear motion in actuators, production machines (Lead screws) and jacks, etc. Transmit power, exert the necessary force to move a machine element along a desired path. Capable of very large mechanical advantages, can lift or move large loads, the speed is often slow. Power Screw Principles1
上海充通大学 Shanghai Jiao Tong University Power Screw Applicationsl .Power screws >Either screw can move,as in a jack or >Nut can move,as in a positioning device. servomotor nut brg coupling screw lead screw nut base
4 Power Screw Applications 1 •Power screws Either screw can move, as in a jack or Nut can move, as in a positioning device
上海充通大学 Shanghai Jiao Tong University Lead Screw and Ball Screw Lead screw(传导螺轩 Lead screws are essentially accurate screws used to move a nut attached to a load,and they have been used for centuries to convert rotary motion into linear motion -Lead screws are commonly used on manual economy machine tools -Efficiency in a lead screw system may be 30-50%
5 Lead Screw and Ball Screw Lead screw(传导螺杆) • Lead screws are essentially accurate screws used to move a nut attached to a load, and they have been used for centuries to convert rotary motion into linear motion – Lead screws are commonly used on manual economy machine tools – Efficiency in a lead screw system may be 30-50%
上海充通大学 Shanghai Jiao Tong University Ball Screws(滚珠螺旋) >Ball screw is similar in function to Return tube lead screw Ball screw >Sliding contact between the screw and nut is replaced by rolling contact using recirculating spherical balls,reduce the thread friction,do not suffer from the Ball nut stick-slip characteristics of sliding joints >Leads to higher efficiency,may have 95%efficiency >However,not self-locking. >Have a more limited fatigue life >But have very high load capacity 6
6 Ball screw is similar in function to lead screw Sliding contact between the screw and nut is replaced by rolling contact using recirculating spherical balls, reduce the thread friction, do not suffer from the stick-slip characteristics of sliding joints Leads to higher efficiency, may have 95% efficiency However, not self-locking. Have a more limited fatigue life But have very high load capacity Ball Screws（滚珠螺旋）
上海充通大学 Shanghai Jiao Tong University Ball Screws (滚珠螺旋) >Modern machine tools,automation equipment,and actuators on aircraft use ball screws for high precision, high efficiency,fast response,and smooth operation. Carriage Rotary Encoder XX ☒☒Ⅻ ☒X AC Brushless Motor Flexible Coupling Rearing Housing Ballscrew Ballnut Support Bearings 7
7 Ball Screws（滚珠螺旋） Modern machine tools, automation equipment, and actuators on aircraft use ball screws for high precision, high efficiency, fast response, and smooth operation
上海充通大学 Shanghai Jiao Tong University Roller Screws(滚子螺旋) >Friction is higher than a ball screw and thus a roller screw is less efficient; >Perform between power screws and ball screws. >however,can support greater axial load because of greater contact area per un length of nut
8 Friction is higher than a ball screw and thus a roller screw is less efficient; Perform between power screws and ball screws. however, can support greater axial load because of greater contact area per unit length of nut. Roller Screws（滚子螺旋）
上游克通大学 Shanghai Jiao Tong Univers Figure 6.7.2 Recirculating roller screw(top)and planetary roller screw design.Source:SKF Com- ponent Systems Co.,Allentown,PA
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上海充通大学 Shanghai Jiao Tong University Other Applicationsl ES03· DEINNd 10
10 Other Applications 1