圈上大峰 Roller Screws(滚柱螺旋) Nut Housing- rinm Thrust Bearing Wiper Seal- 圈上大峰 Other Applicationsl 12
11 Roller Screws（滚柱螺旋） 12 Other Applications1
上濟大学 Objective of This Lecture Learn to analyze power screws and to specify suitable sizes for a given application Describe the operation of a power screw and the general form of square threads,Acme threads,and buttress threads锯齿螺纹)as they are applied to power screws. Compute the torque that must be applied to a power screw to raise or lower a load Compute the efficiency of power screws Compute the power required to drive a power screw Analyze the failure modes 13 圈上我大峰 -Mawe diamete Basic Terminology3 ·Pitch,p(螺距) >Distance between adjacent thread forms measured parallel to the thread axis. ·Major Diameter,d(大径) >Largest diameter of a screw thread. ·Minor Diameter,d,(小径) >Smallest diameter of a screw thread ·Pitch Diameter,,dp(中径) >The effective diameter of the screw >Sometimes called the mean diameter,dm 14
13 Objective of This Lecture Describe the operation of a power screw and the general form of square threads, Acme threads, and buttress threads（锯齿螺纹） as they are applied to power screws. Compute the torque that must be applied to a power screw to raise or lower a load Compute the efficiency of power screws Compute the power required to drive a power screw Analyze the failure modes Learn to analyze power screws and to specify suitable sizes for a given application 14 Basic Terminology3 • Pitch, p（螺距） Distance between adjacent thread forms measured parallel to the thread axis. • Major Diameter, d（大径） Largest diameter of a screw thread. • Minor Diameter, dr （小径） Smallest diameter of a screw thread • Pitch Diameter, dp（中径） The effective diameter of the screw Sometimes called the mean diameter, dm
圈上清式廷大生 Basic Terminology3 Angle of thread Flank Slope→ -0.5p Axis -e!p yoild Crest- Pitch Root- Depth of thread- External thread Internal thread 外螺纹 内螺纹 15 圈上我大峰 Basic Terminology3 ·Lead,l(导程) >Distance the nut moves parallel to the screw axis when the nut is given one turn ·Lead Angle,(导程角、升角) >Angle between the perpendicular of the screw axis and the rise of the thread ·Helix Angle,Ψ（螺旋角） >Angle between the screw axis and the rise of the thread ·Thread Angle,.2a(牙型角2a、牙侧角a) >a:Angle between the perpendicular to the screw axis and the crest of the thread. 16
15 Basic Terminology3 External thread 外螺纹 Internal thread 内螺纹 16 Basic Terminology3 • Lead, l（导程） Distance the nut moves parallel to the screw axis when the nut is given one turn • Lead Angle, （导程角、升角） Angle between the perpendicular of the screw axis and the rise of the thread • Helix Angle, （螺旋角） Angle between the screw axis and the rise of the thread • Thread Angle, 2 （牙型角2 、牙侧角 ） ：Angle between the perpendicular to the screw axis and the crest of the thread
圈上大峰 Basic Terminology3 ·External Threads(外螺纹) >the threads on a screw ·Internal Threads(内螺纹) >the threads on a nut ·Engagement Length,L。(旋合长度) >length over which the nut and the screw are engaged. 圈上大峰 Multiple Screw Threads2(多线螺纹) .Screws can be multiple-threaded by having two or more threads cut beside each other Double-threaded screw(双线螺纹) >lead is equal to twice the pitch,/=2p ,Triple-threaded screw(三线螺纹) >lead is equal to 3 times the pitch,/=3p .Advantage of multiple threads:They have >Smaller thread height >Increased lead for fast advancement of nut. .Standardized products all have single thread 18
17 Basic Terminology3 • External Threads（外螺纹） the threads on a screw • Internal Threads（内螺纹） the threads on a nut • Engagement Length, Le （旋合长度） length over which the nut and the screw are engaged. 18 Multiple Screw Threads2（多线螺纹） •Screws can be multiple-threaded by having two or more threads cut beside each other •Double-threaded screw（双线螺纹） lead is equal to twice the pitch，l=2p •Triple-threaded screw （三线螺纹） lead is equal to 3 times the pitch, l=3p •Advantage of multiple threads: They have Smaller thread height Increased lead for fast advancement of nut. •Standardized products all have single thread
圈 上文大学 Multiple Screw Threads2 I=n *p,nnumber of threads 1 tan入=- 圈上我大峰 Direction of helical groove Screw in Right hand Left hand 20
19 Multiple Screw Threads2 l=n p, n—number of threads dm l tan 20 Direction of helical groove