圈上海夫通大华 西+口 LECTURE 9 ME371/ME337 DESIGN AND MANUFACTURING Threaded Fasteners Covered: 8 in Mechanical Engineering Design SHAN 圆上海文通大学 Lectures Power/Energy Conversion (Electrical Motors) Power/Energy Transmission (Gears,Cam,Linkage, Belt Drives, Power Screws) Transmission Joints (Fasteners, Support Connectors) (Bearings) Structural Support (Frames) Tools Statics,Dynamics, Stress Analysis,etc. 1
1 Threaded Fasteners LECTURE 9 Covered: 8 in Mechanical Engineering Design ME371/ME337 DESIGN AND MANUFACTURING 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)
圆上泽文大学 OUTLINE © Threaded Fasteners introduction ©Stiffness Analysis ©Strength Analysis ©Fatigue Analysis 圈上泽夫道大学 Classification by intended use Bolt:when it is intended to be used with a nut to clamp an assembly together.The bolt remains stationary while nut is torqued. Screw:when it is threaded into a tapped hole rather than used with a nut.Screw is torqued into place. 2
2 Threaded Fasteners introduction Stiffness Analysis Strength Analysis Fatigue Analysis OUTLINE Classification by intended use Bolt : when it is intended to be used with a nut to clamp an assembly together. The bolt remains stationary while nut is torqued. Screw: when it is threaded into a tapped hole rather than used with a nut. Screw is torqued into place
圈上海文通大华 Types of Threaded Fastener ▣Bolt(螺栓)：Threaded fastener designed to pass through holes in the mating members and to be secured by tightening a nut from the end opposite the head of the bolt. (a) (b) 圆上泽夫通大学 Types of Threaded Fastener 口Screws(螺钉)：Threaded fastener designed to be inserted through a hole in one member to be joined and into a threaded hole in a mating member. 3
3 Types of Threaded Fastener Bolt(螺栓): Threaded fastener designed to pass through holes in the mating members and to be secured by tightening a nut from the end opposite the head of the bolt. Screws(螺钉): Threaded fastener designed to be inserted through a hole in one member to be joined and into a threaded hole in a mating member. Types of Threaded Fastener
圈上泽文通大华 Types of Threaded Fastener 口Stud螺柱)：Fastener similar to a bolt.It is attached permanently to a part of one member to be joined.The mating member is then placed over the stud and a nut is tightened to clamp members 圆上清支大华 Types of Threaded Fastener 口Set Screws(定位螺钉)：Headless fasteners designed to bear directly on mating part locking it into place.Depends on compression. (a) (b) 4
4 Stud(螺柱): Fastener similar to a bolt. It is attached permanently to a part of one member to be joined. The mating member is then placed over the stud and a nut is tightened to clamp members Types of Threaded Fastener Set Screws(定位螺钉): Headless fasteners designed to bear directly on mating part locking it into place. Depends on compression. Types of Threaded Fastener
圈上泽文通大华 Types of Threaded Fastener 口Set Screws(定位螺钉)：Example of set screws with different head and point styles applied to hold a collar(齿轮颈)ona shaft. ⊕ Figure 18-12 Set Screws with Different Head and Point Styles Applied to Hold a Collar on a Shaft (R.P.Hoelscher,et al..Graphics for Engi .New York: lohn Wiley Sons,1968) Set © 上海充廷大学 Questions for discussion What is the advantage and disadvantage of the Bolt, Screws,the Stud and Set Screws in different working condition？ What is the functional difference between them? Can you please list some examples for the above questions？ 5
5 Set Screws(定位螺钉):Example of set screws with different head and point styles applied to hold a collar (齿轮颈) on a shaft. Types of Threaded Fastener Questions for discussion What is the advantage and disadvantage of the Bolt , Screws，the Stud and Set Screws in different working condition? What is the functional difference between them? Can you please list some examples for the above questions?
国 上海文通大学 Bolt Standardization 口 Metric Mechanical-Property Classes for Steel Bolts,Screws,and Studs Minimum Minimum Size Proof Tensile Yield MPa Material Head Marking 4.6 M5-M36 225 400 240 Low or medium carbon 、46） M1.6-M16 310 420 340 Low or medium carbon 58 M5-M24 380 520 420 Low or medium carbon 8.8 MI6-M36 600 830 Medium carbon,Q&T Table 8-11 周 上海充通大学 Bolt Standardization 口 Dimensions of Square and Hexagonal Bolts Hoad Type Squar Regular Hexagonal y Hexagonal Structural Hexag nal H M5 3.58 3.58 02 Mo 10 4.38 03 M8 13 5.68 04 M10 16 6,85 04 M12 18 7.95 0.6 21 7.95 0.6 M14 9.25 MI6 10.75 0 47 10.75 10.75 0.6 M20 0 13.40 0 1340 M24 15.90 15.90 08 4 15.90 10 M30 46 19.75 10 2355 0 19.75 M36 1.0 23.55 H Table E-29 6
6 Metric Mechanical-Property Classes for Steel Bolts, Screws, and Studs Bolt Standardization Table 8-11 Dimensions of Square and Hexagonal Bolts Bolt Standardization Table E-29
圈上泽文通大华 Nuts Lock Nuts:For preventing spontaneous loosening of nuts due to vibration. >Two nuts jammed together on the bolt or a castle nut with cotter pin both reliably achieve this goal. These threads provide interference with those on the bolt and resist loosening 圈上泽夫道大学 Nuts Nuts are also made with nylon inserts in the threads that deform when forced onto the bolt. >The nylon flows into the thread clearances and grips the bolt. A pin lock nut has a steel pin that allows tightening,but digs into the bolt threads to prevent loosening. ▣Nuts are also made with serrations(锯齿状)on one face that act to dig into the clamped part and resist loosening. 7
7 Nuts Lock Nuts: For preventing spontaneous loosening of nuts due to vibration. Two nuts jammed together on the bolt or a castle nut with cotter pin both reliably achieve this goal. These threads provide interference with those on the bolt and resist loosening. 上螺母 螺 栓 下螺母 上螺母 螺 栓 下螺母 上螺母 螺 栓 下螺母 上螺母 螺 栓 下螺母 Nuts are also made with nylon inserts in the threads that deform when forced onto the bolt. The nylon flows into the thread clearances and grips the bolt. A pin lock nut has a steel pin that allows tightening, but digs into the bolt threads to prevent loosening. Nuts are also made with serrations(锯齿状) on one face that act to dig into the clamped part and resist loosening. Nuts
国 上泽充通大学 Nut Standardization 口 Dimensions of Hexagonal Nuts Height H Nominal Width Regular Thick or Size,in w Hexagonal Slotted JAM M5 8 4.7 51 2.7 M6 10 5.2 5.7 3.2 M8 13 6.8 7.5 4.0 M10 16 8.4 9.3 5.0 M12 10.8 12.0 6.0 M14 21 12.8 14.1 7.0 M16 14.8 16.4 8.0 M20 响 18.0 20.3 10.0 M24 21.5 23.9 12.0 M30 46 25.6 28.6 15.0 M36 5 31.0 34.7 18.0 Table E-31 圆上泽文廷大学 Washers(垫图) Increases area of contact between bolt head or nut and clamped part Washers protect bolt head so that it do not aggravate stress concentrations A washer also prevents marring of part surface by nut when it is tightened. 6 8
8 Dimensions of Hexagonal Nuts Nut Standardization Table E-31 Increases area of contact between bolt head or nut and clamped part Washers protect bolt head so that it do not aggravate stress concentrations A washer also prevents marring of part surface by nut when it is tightened. Washers(垫圈)
圈上海文通大华 Washers ▣Plain washer(普通垫圈)：Flat,doughnut- shaped part ▣Hardened steel(硬化钢)washers:Used where bolt compression load on clamped part needs to be distributed over a larger area than bolt head or nut provides. Soft washer:Yields in bending rather than effectively distribute the load. ▣Non-metallic(非金属)washers:Used when electrical insulation from part is required. 圈上泽夫道大学 Washers ④ (a)Spitockwasher ▣Lock washers(锁紧垫圈) Used to help prevent spontaneous loosening of standard nuts n >Less preferred to lock nuts. tema-toothwasher ▣Split washer(开口垫圈) >Hardened steel that acts like a spring under nut N its sharp corners tend to dig into (Extemal-tooth washer clamped surfaces ▣Toothed washers(锯齿垫圈) >have turned-up teeth that compress when clamped and dig into the nut and d Internal-extemal toeth part surfaces. w 9
9 Washers Plain washer (普通垫圈): Flat, doughnutshaped part Hardened steel(硬化钢) washers : Used where bolt compression load on clamped part needs to be distributed over a larger area than bolt head or nut provides. Soft washer : Yields in bending rather than effectively distribute the load. Non-metallic(非金属) washers : Used when electrical insulation from part is required. Lock washers (锁紧垫圈) Used to help prevent spontaneous loosening of standard nuts Less preferred to lock nuts. Split washer (开口垫圈) Hardened steel that acts like a spring under nut its sharp corners tend to dig into clamped surfaces Toothed washers (锯齿垫圈) have turned-up teeth that compress when clamped and dig into the nut and part surfaces. Washers
图 上海文通大学 Nut Standardization ▣ Dimensions of Metric Plain Washers Washer Minimum Maximum Maximum Size ID OD Thickness ION 10.85 20.00 2.30 10R 10.85 28.00 2.80 10W 10.85 39.00 3.50 12N 13.30 25.40 2.80 12R 13.30 34.00 3.50 12W 13.30 44.00 3.50 14N 15.25 28.00 2.80 14R 15.25 39.00 350 14w 15.25 50.00 4.00 16N 17.25 32.00 3.50 16R 17.25 44.00 4.00 Table E-33 圈上泽夫道大学 OUTLINE Threaded Fasteners introduction ©Stiffness Analysis ©Strength Analysis ©Fatigue Analysis 10
10 Dimensions of Metric Plain Washers Nut Standardization Table E-33 Threaded Fasteners introduction Stiffness Analysis Strength Analysis Fatigue Analysis OUTLINE