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二级减速器课程设计说明书，全英文书写
《Machine Parts Design》
Design Specification
Topic Designation of Reducer
College College of Mechanical and Electrical Engineering
Major Mechanical Engineering
Class 16机械工程3（国际化）
No. of team Team 1
ID/Name 陈旭颖 16211452104
方 琢 16211452105
李成雍 16211452106
Instructor Zhang Yi
Date submitted 2019.01.11
Contents
Abstract 1
Chapter 1 Course Design Task Book 3
1.1 Purpose 3
1.2 Description of design project 3
1.3 Design Data 4
Chapter 2 Integral Design Scheme of Transmission Device 4
2.1 Transmission Scheme 4
2.2 Advantages and Disadvantages of this Scheme 4
Chapter 3 Selection of Motor 5
3.1 Motor Type Selection 5
3.2 Determination of the Efficiency of the Transmission 5
3.3 Selection of the motor capacity 5
3.4 Determination of the total transmission ratio and distribution transmission ratio of the transmission device 7
Chapter 4 Calculation of Dynamic Parameters 8
Chapter 5 Designation and calculation of high speed gear 11
5.1 Selection of gear type, accuracy grade, material and number of teeth 11
5.2 Design according to tooth surface contact fatigue strength 11
5.3 Determination of the sizes of transmission 15
5.4 Check the bending fatigue strength of tooth root 15
5.5 Calculations of other geometric dimensions of gear transmission 19
5.6 Summary of gear parameters and geometric dimensions 20
Chapter 6 Calculation of low-speed gear 21
6.1 Selection of gear type, accuracy grade, material and number of teeth 21
6.2 Designation according to tooth surface contact fatigue strength 22
6.3 Determination of the sizes of transmission 25
6.4 Check the bending fatigue strength of tooth root 26
6.5 Calculations of other geometric dimensions of gear transmission 30
6.6 Summary of gear parameters and geometric dimensions 30
Chapter 7 The designation of the shaft 32
7.1 Calculateion of High-speed shaft design 32
7.2 Calculation of jack shaft design 39
7.3 Calculation of low speed shaft 47
Chapter 8 Rolling bearing life check 53
8.1 Bearing check on high speed shaft 53
8.2 Bearing check on the jack shaft 55
8.3 Bearing check on the low speed shaft 57
Chapter 9 Key connection design calculation 58
9.1 Calculation check of coupling key connection 58
9.2 Calculation check of low speed pinion’s key connection 59
9.3 Calculation check of high speed main gear’s key connection 59
9.4 Calculation check of low speed main gear’s key connection 59
Chapter 10 Coupling selection 60
10.1 Coupling on the high speed shaft 60
10.2 Coupling on the low speed shaft 60
Chapter 11 Seal and lubricate the reducer 61
11.1 Selection of sealing 61
11.2 Gear lubrication 61
11.3 Bearing lubrication 62
Chapter 12 Reducer accessory 63
12.1 Oil level indicator 63
12.2 Ventilator 63
12.3 Drain plug 64
12.4 Peephole cover 65
12.5 Positioning pin 66
12.6 Cover screw 67
12.7 Lifting device 68
Chapter 13 Main structural dimensions of reducer housing 70
Chapter 14 Drawing of structure analysis of reduce 72
14.1 Drawing of assembly 72
14.2 Housing 73
14.3 Drawing of gears 74
14.4 Drawing of shafts 78
Chapter 15 Conclusion 81
15.1 Summary 81
15.2 Job description of team members 82
Reference 83
Attachment 84
Abstract
Belt conveyor is a kind of friction driven to transport materials in a continuous way machinery. It Is mainly composed of irame conveyor belt, supporting roller, roller, tensioning device and belt conveyor motor device. It can put the material on a certain conveying line and form a conveying process of material from the initial feeding point to the final unloading point. It can not only carry out the transport of broken bulk materials, but also the transport of finished articles. In addition to the pure material transport, it can also cooperate with the requirements of the technological process in the production process of various industrial enterprises to form a rhythmic assembly line.
Belt conveyor is widely used in metallurgy, coal, transportation, water and electricity, chemical and other departments, because it has a large amount of transport, simple structure, convenient maintenance, low cost, strong versatility and other advantages. Belt conveyor is also used in building materials, power, light industry, food, ports, ships and other departments.
Main contents of this manual is for the design of belt conveyor drive system, the V belt transmission and twoestage cylindrical gear reducer, used in the design and calculation to the "machine design foundation", "mechanical drawing" "tolerance and interchangeability", “theoretical mechanics" courses, such as knowledge, and use AutoCAD software to carry on the drawing, so the comprehensive practice is a very important link, is also a comprehensive, standardized training in practice. Through this training, so that we have been in many aspects of training and training. It is mainly reflected in the following aspects.
(1) we have cultivated the design idea of combining theory with practice, trained our ability to comprehensively apply the basic theory of mechanical design course and other related courses, analyze and solve practical engineering problems in combination with production practice, and consolidated, deepened and expanded the knowledge of relevant mechanical design.
(2) through the standard mechanical parts. common mechanical transmission or simple mechanical design, so that we master the general mechanical design procedures and methods. establish a correct engineering desrgn Ideas. cultivate independence. comprehensive.
Scientific engineering design ability and innovation ability.
(3) in addition, it cultivates our ability to consult and use manuals, atlas and other relevant technical data, as well as the ability in calculation, drawing data processing and computer, aided design.
(4) enhanced our understanding and application of the functions of Word and AutoCAD in office software.
Keywords: reducer, transmission device, design, calculation, CAD
Chapter 1 Course Design Task Book
1.1 Purpose
According to the diagam of the belt conveyor system:
(1) Plan and analysis of transmission device;
(2) Selection of motor and calculation of kinematic and dynamic parameters in conveyor system;
(3) Design of transmission parts (e.g. gear, worm or belt, etc.);
(4) Design of shaft;
(5) Design of bearing and its assemblies;
(6) Selection and confirmation of key and coupling;
(7) Design of lubrication;
(8) Housing, framework and accessories;
(9) Drawing of assembly and its components;
(10) Design specification
1.2 Description of design project
(a) running on two shifts per day in one-direction continuously;
(b) stable loading;
(c) starting with idling;
(d) indoor setting with dust;
(e) usage period: 10 years, minor overhaul period: 1 year, and overhaul period: 3 years;
(f) power source is alternating three-phase voltage;
(g) small-batch production in medium scale machinery plant;
(h) allowed tolerance of conveyor speed is ± 5%.
Working hours per day: 16 hours, working life: 10 years, working days per year: 300 days, equipped with three-phase AC power supply, voltage 380/220 V.
1.3 Design Data
Working force of conveyor, F 2900N
Speed of conveyor, v 1.5m/s
Diameter, D 410mm
Chapter 2 Integral Design Scheme of Transmission Device
2.1 Transmission Scheme
Analysis of transmission scheme v-belt transmission is adopted .
Considering the requirements of the project , I chose this scheme . Its transmission diagram is shown in figure 1-1.
The transmission scheme has been given, and the reducer is a two-stage cylindrical gear reducer.
2.2 Advantages and Disadvantages of this Scheme
The extemal outline size of this scheme is large, with good shock absorption capacity, low manufacturing, stability accuracy with low cost, and overload protection.
But because the gear relative to the bearing of the two-stage cylindrical gear reducer is arranged asymmetrically, the load distribution along the tooth direction is uneven, and the shaft stiffness is required.
Chapter 3 Selection of Motor
3.1 Motor Type Selection
According to the use of the Y-series general purpose fully closed self-cooled three-phase asynchronous motor.
3.2 Determination of the Efficiency of the Transmission
According to table 2-1, we got：
The Efficiency of coupling：η1=0.99
The Efficiency of rolling bearing：η2=0.99
The Efficiency of closed cylindrical gears：η3=0.98
The Efficiency of Working Machine：ηw=0.97
Total efficiency from motor to machine：
ηa=η1×η24×η32×ηw=0.877
3.3 Selection of the motor capacity
The power required by the working machine Pw:
Rated power required by motor Pd:
Work speed of transmission belt wheels nw：
According to the recommended reasonable transmission ratio range in table 2-2, the transmission ratio range of the expanded two-stage gear reducer ia=8 ~ 40, the transmission ratio range of v-belt transmission is ib=2~4, so the theoretical transmission ratio range is=16~160.
The optional speed range of the motor : nd=is*nw=(16 ~ 160) 69.91=559--2796r/min.
After comprehensive consideration of price, weight, transmission ratio and other factors, the selected three-phase asynchronous motor model : Y132M2-6 . Rated power Pen=5.5kW，Full load speed nm=960r/min，Synchronous speed nt=1000r/min。
Serial Number Motor Type Synchronous Speed/(r/min) Rated Power/kW Full Speed/(r/min)
1 Y160M2-8 750 5.5 720
2 Y132M2-6 1000 5.5 960
3 Y132S-4 1500 5.5 1440
4 Y132S1-2 3000 5.5 2900
Figure 3-1 main size parameters of the motor
Height of Center Dimensionof overall Dimensionof base mounting Diameter of anchor bolt hole Size of Axis stretch Size of key
H L×HD A×B K D×E F×G
132 515×315 216×178 12 38×80 10×33
3.4 Determination of the total transmission ratio and distribution transmission ratio of the transmission device
（1）Calculation of total transmission ratio
According to the selected fullload speed of the motor nm and the drive shaft speed of the motor nw，we can calculate the total transmission ratio of the transmission device ia：
（2）Allocate transmission ratio
High speed stage transmission ratio i1
Then the transmission ratio of low-speed stage i2
Total transmission ratio of reducer ib
Chapter 4 Calculation of Dynamic Parameters
（1）The speed of each shaft：
High speed shaft :
Jack shaft ：
Low speed shaft ：
The working machine shaft :
（2）Input power of each shaft：
High speed shaft :
Jack shaft ：
Low speed shaft ：
The working machine shaft :
Then the output power of each shaft：
High speed shaft :
Jack shaft ：
Low speed shaft ：
The working machine shaft :
（3）Input torque of each shaft：
Motor shaft :
High speed shaft :
Jack shaft ：
Low speed shaft ：
The working machine shaft :
Then the torque of each shaft：
High speed shaft :
Jack shaft ：
Low speed shaft ：
The working machine shaft :
The rotational speed, power and torque of each shaft are listed in the following table
name of the shaft rotating speed n /(r/min) power P/kW torque T/(N•m)
Motor shaft 960 4.96 49.34
High speed shaft 960 4.91 48.84
Jack shaft 222.74 4.76 204.09
Low speed shaft 69.82 4.62 631.92
The working machine shaft 69.82 4.35 594.99
Chapter 5 Designation and calculation of high speed gear
5.1 Selection of gear type, accuracy grade, material and number of teeth
1. According to the transmission scheme, helical cylindrical gear transmission is selected，Pressure angle α=20°，Primary spiral Angle β=12°。
2. Refer to table 10-6 for level 7 accuracy.
3. Material selection : According to table 10-1, Pinion chosen: 40Cr (quenched and tempered), hardness: 280HBS; Main gear: 45 (quenched and tempered), hardness: 240HBS.
4. Number of pinion teeth: z1=24，number of main gear teeth: z2=z1×i=24×4.31=103.
5.2 Design according to tooth surface contact fatigue strength
1. The diameter of the dividing circle of the pinion is calculated by formula (10-24)，that is:
(1) Determine the values of each parameter in the formula
(1) Choose KHt=1.3
(2) Calculate the torque T transmitted by the pinion:
(3) According to table 10-7, the tooth width coefficient: φd=1
(4) According to figure 10-20, regional coefficient: ZH=2.47
(5) According to table 10-5, the elastic influence coefficient of the material: ZE=189.8√MPa.
(6)The contact fatigue strength Zε is calculated by formula (10-9).
(7) The spiral Angle coefficient Zβ can be obtained from the formula.
(8) Calculate the allowable contact fatigue stress[σH]
According to figure 10-25d, the contact fatigue limit of pinion and large gear is respectively
The stress cycle number is calculated from equation (10-15):
Contact fatigue coefficients were obtained from FIG. 10-23
If the failure probability is 1% and the safety coefficient S=1,then:
Take the smaller one of [σH]1 and [σH]2as the contact fatigue allowable stress of the gear pair, that is:
(2) Calculate the diameter of the dividing circle of the pinion
2. Adjust the diameter of the dividing circle of the pinion
(1) Data preparation before calculating actual load coefficient.
(1) Circumferential velocity ν
(2) Tooth width b
(2) Calculate the actual load coefficient KH
(1) According to table 10-2, KA=1
(2) According to v=1.827m/s and the accuracy of level 7, the dynamic load coefficient can be obtained from figure 10-8, Kv=1.035
(3) The circular force of a gear.
In table 10-3, the load distribution coefficient between teeth was KH =1.4
When the accuracy of level 7 and the relative support of pinion are arranged asymmetrically by interpolation method, according to table 10-4, the distribution coefficient of load in tooth direction KHβ=1.417
Thus, the actual load coefficient KH is obtained
(3) According to equation (10-12) and the actual load coefficient, the diameter of the dividing circle d1 can be obtained
(4) Determine the modulus of
5.3 Determination of the sizes of transmission
1. Computing center distance a
2. The helix Angle is corrected according to the center distance after rounding
β=12°19'58"
3. Calculate the dividing circle diameter d1 ,d2of small and big gear
4. Calculate the tooth width b
Take B1=55mm, B2=50mm
5.4 Check the bending fatigue strength of tooth root
The fatigue strength condition of tooth root bending:
(1)T、mn and d1 are like the previous
Tooth width: b=b2=50
Tooth shape coefficient YFa and stress correction coefficient YSa, the equivalent number of teeth:
The equivalent number of teeth of pinion Zv1:
Equivalent number of teeth of main gear Zv2:
The tooth shape coefficient is obtained from FIG. 10-17
The stress correction coefficient is obtained from FIG. 10-18
(1) Choose load factor KFt=1.3
(2) From equation (10-18), the coincidence coefficient of bending fatigue strength Yε can be calculated
Have a type:
(3) From equation (10-19), obtain the spiral Angle coefficient of bending fatigue strength Yβ
(2) Circumferential velocity
(3) Aspect ratio b/h
According to v=2.47m/s, level 7 accuracy, dynamic load coefficient can be found from figure 10-8, Kv=1.047
According to table 10-3 , load distribution coefficients between teeth KFα=1.4
According to table 10-4, KH =1.42 and b/h=50/4.5=11.111. According to figure 10-13, KF =1.079.
Then the load coefficient is:
According to FIG. 10-24c, the tooth root bending fatigue limit of pinion and big gear is respectively
The bending fatigue coefficient KFN1 ,KFN2 was obtained from FIG. 10-22
The bending fatigue safety factor S=1.25, from equation (10-14)
Check the bending fatigue strength of tooth root
The bending fatigue strength of tooth root meets the requirement, and the ability of pinion to resist bending fatigue damage is greater than that of large gear.
(4) The circular velocity of a gear
Level 7 accuracy is appropriate.
5.5 Calculations of other geometric dimensions of gear transmission
（1）Calculate the height of addendum tooth, dedendum tooth and total tooth
（2）Calculate the addendum circle diameters of small and large gears
（3）Calculate the diameter of dedendum circle of small and large gears
5.6 Summary of gear parameters and geometric dimensions
Code name Calculated formula Pinion Main gear
Modulus m 2 2
Spiral Angle β left-handed 12°19'58" right-handed 12°19'58"
Coefficient of addendum height ha* 1.0 1.0
Tip clearance coefficient c* 0.25 0.25
Number of teeth z 24 103
Width of teeth B 55 50
Height of addendum teeth ha m×ha* 2 2
Height of dedendum teeth hf m×(ha*+c*) 2.5 2.5
Diameter of the dividing circle d 49.134 210.866
Addendum circle diameter da d+2×ha 53.134 214.866
Dedendum circle diameter df d-2×hf 44.134 205.866
Figure 5-1 structure diagram of high-speed main gear
Chapter 6 Calculation of low-speed gear
6.1 Selection of gear type, accuracy grade, material and number of teeth
1. According to the transmission scheme, choose helical cylindrical gears，The pressure off for alpha = 20 °, primary spiral Angle beta = 12 °.
2. Refer to table 10-6 , choose level 7 accuracy.
3. Material selection According to table 10-1, choose pinion 40Cr (quenching and tempering), and the hardness was 280HBS; choose main gear 45 (quenching and tempering), and the hardness was 240HBS
4. Select the number of pinion teeth z1=25, then the number of large gear teethz2=z1×i=25×3.19=81.
6.2 Designation according to tooth surface contact fatigue strength
1. From formula (10-24), the diameter of the dividing circle of the pinion is calculated, i.e
(1) Determine the values of each parameter in the formula
(1) Choose KHt=1.3
(2) Calculate the torque transmitted by the pinion:
(3) From table 10-7, the tooth width coefficient is φd=1
(4) From figure 10-20, Regional coefficient ZH=2.47
(5) From table 10-5, the elastic influence coefficient of the material ZE=189.8√MPa。
(6) From equation (10-9), the coincidence coefficient is used to calculate the contact fatigue strength Zε.
(7) From the formula, the spiral Angle coefficient Zβ.
(8) Calculate the allowable contact fatigue stress[σH]
According to figure 10-25d, the contact fatigue limit of pinion and big gear is respectively
From equation (10-15) , the number of stress cycles can be calculated :
From figure10-23, check the contact fatigue coefficient
If the failure probability is 1% and the safety coefficient S=1, then
Take the smaller one of [σH]1 and [σH]2as the contact fatigue allowable stress of the gear pair, that is:
(2) Calculate the diameter of the dividing circle of the pinion
2.Adjust the diameter of the dividing circle of the pinion
(1) Data preparation before calculating actual load coefficient.
(1) Circumferential velocity ν
(2) Tooth width b
(2) Calculate the actual load coefficient KH
(1) According to table 10-2, KA=1
(2) According to v=0.666m/s and the accuracy of level 7, the dynamic load coefficient can be obtained from figure 10-8, Kv=1.013
(3) The circular force of a gear.
In table 10-3, the load distribution coefficient between teeth was KH =1.2
When the accuracy of level 7 and the relative support of pinion are arranged asymmetrically by interpolation method, according to table 10-4, the distribution coefficient of load in tooth direction KHβ=1.421
Thus, the actual load coefficient KH is obtained
(3) According to equation (10-12) and the actual load coefficient, the diameter of the dividing circle d1 can be obtained
(4) Determine the modulus of
6.3 Determination of the sizes of transmission
1. Computing center distance a
2.The helix Angle is corrected according to the center distance after rounding
β=12°43'9"
3. Calculate the dividing circle diameter d1 ,d2of small and big gear
4. Calculate the tooth width b
Take B1=85mm B2=80mm
6.4 Check the bending fatigue strength of tooth root
The fatigue strength condition of tooth root bending:
(1)T、mn and d1 are like the previous
Tooth width: b=b2=80
Tooth shape coefficient YFa and stress correction coefficient YSa, the equivalent number of teeth:
Equivalent number of teeth of pinion Zv1:
Equivalent number of teeth of main gear Zv2:
The tooth shape coefficient is obtained from FIG. 10-17
The stress correction coefficient is obtained from FIG. 10-18
(1) Choose load factor KFt=1.3
(2) From equation (10-18), the coincidence coefficient of bending fatigue strength Yε can be calculated
Have a type:
(3) From equation (10-19), obtain the spiral Angle coefficient of bending fatigue strength Yβ
(2) Circumferential velocity
(3) Aspect ratio b/h
According to v=0.9m/s, level 7 accuracy, dynamic load coefficient can be found from figure 10-8, Kv=1.017
According to table 10-3 , load distribution coefficients between teeth KFα=1.4
According to table 10-4, KHβ =1.427 and b/h=80/6.75=11.852. According to figure 10-13, KF =1.08.
Then the load coefficient is:
According to FIG. 10-24c, the tooth root bending fatigue limit of pinion and big gear is respectively
The bending fatigue coefficient KFN1 ,KFN2 was obtained from FIG. 10-22
The bending fatigue safety factor S=1.25, from equation (10-14)
Check the bending fatigue strength of tooth root
The bending fatigue strength of tooth root meets the requirement, and the ability of pinion to resist bending fatigue damage is greater than that of large gear.
(4) The circular velocity of a gear
Level 7 accuracy is appropriate.
6.5 Calculations of other geometric dimensions of gear transmission
（1）Calculate the height of addendum tooth, dedendum tooth and total tooth
（2）Calculate the addendum circle diameters of small and large gears
（3）Calculate the diameter of dedendum circle of small and large gears
6.6 Summary of gear parameters and geometric dimensions
Code name Calculated formula Pinion Main gear
Modulus m 3 3
Spiral Angle β left-handed 12°43'9" right-handed 12°43'9"
Coefficient of addendum height ha* 1.0 1.0
Tip clearance coefficient c* 0.25 0.25
Number of teeth z 25 81
Width of teeth B 85 80
Height of addendum teeth ha m×ha* 3 3
Height of dedendum teeth hf m×(ha*+c*) 3.75 3.75
Diameter of the dividing circle d 76.887 249.113
Addendum circle diameter da d+2×ha 82.887 255.113
Dedendum circle diameter df d-2×hf 69.387 241.613
Figure 6-1 Low speed large gear structure drawing
Chapter 7 The designation of the shaft
7.1 Calculateion of High-speed shaft design
1. Select the material on the shaft and determine the allowable stress
Because the reducer is a general machine, there is no special requirement, so 40Cr (quenched and tempered) is selected, the hardness is 280HBS, check the table15-1,take σb=735MPa, σ-1b=60MPa
2. The minimum diameter of the shaft estimated according to the initial torsion strength
Check table 15-3, take A0=112，so
Shaft ends have 1 keyway, therefore, the axle diameter should be increased by 5%
According to the table, the diameter of the standard axle hole is 22mm, so d=22
Figure 7-1 Schematic diagram of high-speed shaft
(1) The minimum diameter of the input shaft is obviously d12, where the coupling is mounted. In order to adapt the selected shaft diameter d12 to the coupling aperture, the type of coupling should be selected. The calculated torque of the coupling Tca = KA×T, according to the table, thinking about the stability, we choose KA = 1.3, then:
According to the condition that the torque Tca of the coupling should be less than the nominal torque of the coupling, refer to standard GB t4323-2002 or design manual, choose LX3 type coupling. The aperture of the semi-coupling is 22mm, the hub hole length of the semi-coupling and the shaft is 52mm. Choose ordinary flat keys,A type keys, b×h = 6×6mm(GB T 1096-2003), bond length L=40mm。
(2) Initial selection of rolling bearing. Since the bearing is subject to both radial and axial forces, angular contact bearing is selected. Referring to the work requirements and according to d23 = 27mm, select 7206AC angular contact bearing from bearing product catalog, its size: d×D×B = 30×62×16mm, so d34 = d78 = 30 mm.
The positioning shaft shoulder height of 7206AC type bearing is found in the manual, h = 3 mm，then choose d45 = d67 = 36 mm.
(3)Because the diameter of the gear is small, in order to ensure the strength of the gear wheel body, the gear and the shaft should be made into one and become the gear shaft. So l56 = 55 mm, d56 = 53.134 mm.
(4) Thickness of bearing end covere=10, thickness of the gasketΔt=2. According to the bearing end cover for easy assembly and disassembly, ensure that the outer end face of the bearing end cover has a certain distance from the end face of the coupling, K=24; Screw C1=22mm, C2=20mm, thickness of box seat wall δ=8mm, then:
(5) Take small spacing distance of enclosure wall Δ1 = 10 mm, the distance between high speed main gear and low speed pinion Δ3 = 15 mm distance. Considering about the housing casting error, when determining the position of rolling bearing, a distance Δ from inner wall of box should be taken, take Δ = 10 mm, the width of low speed pinion b3=85mm, then:
At this point, the diameter and length of each section of the shaft have been preliminarily determined.
Shaft section 1 2 3 4 5 6 7
Diameter / mm 22 27 30 36 53.134 36 30
Length/ mm 52 65 28 105.5 55 8 28
3. Stress analysis of the shaft
The circumferential force on a high speed pinion Ft1 (d1 is the diameter of the indexing circle of the high-speed pinion)
Radial force on a high speed pinion Fr1
Axial force on a high speed pinion Fa1
According to 7206AC angular contact manual, pressure center a=18.7mm
Distance between the center point of the first shaft and the bearing pressure center l1:
Distance from bearing pressure center to gear fulcrum l2:
Distance between gear midpoint and bearing pressure center l3:
(1) Calculate the supporting reaction of the shaft
Horizontal support reaction:
Vertical support reaction:
(2) Calculate the bending moment of the shaft, and draw the bending moment diagram
The horizontal bending moment at section C:
The vertical bending moment at section C:
Bending moment diagram of horizontal plane (fig.b) and vertical plane (fig.c).
The resultant bending moment at section C:
(3) Make composite bending moment diagram (figure d)
Make torque diagram (figure e)
Figure 7-2 High - speed shaft force and bending moment diagram
4. Check the strength of the shaft
Because the bending moment on the left side of C is large and the action has torque, the left side of C is the dangerous section.
The bending section coefficient W:
The torsion cross section coefficient WT:
The maximum bending stress:
The shear stress:
Check and calculate according to the strength of bending and torsion. For the shaft of one-way drive, torque is processed according to pulsating cycle. Therefore, the reduced coefficient is adopted α=0.6, then the equivalent stress is
(10) Check the table, get 40Cr(tempering and tempering) treatment, and the limit of tensile strength σB=735MPa; Then the allowable bending stress of the axis [σ-1b]=60MPa, σca<[σ-1b], so the strength is good.
7.2 Calculation of jack shaft design
1. Select the material on the shaft, and determine the allowable stress
Because the reducer is a general machine, there is no special requirements, so choose 45 (quenched and tempered), the hardness: 240HBS. Referring table 15-1, take σb=640MPa, σ-1b=60MPa
2. According to the initial torsion strength, the minimum diameter of the shaft estimated
Refer to table 15-3, take A0=112, then:
Since the minimum diameter of the shaft section is all rolling bearings, the standard diameter d=35mm is selected.
Figure 7-3 Diagram of intermediate shaft
(1) Initial selection of rolling bearing. The minimum diameters of the intermediate shaft are d12 and d56 for mounting the rolling bearing. Because the bearing is subject to both radial and axial forces, angular contact bearing is chosen. Referring to the requirement of working and according to dmin = 31.08 mm, from the bearing catalogue, selsct angular contact bearing 7207AC, its size: d×D×B = 35×72×17mm, so d12 = d56 = 35 mm.
(2) At the installation of the big gear, take the diameter of the shaft section d45 = 38mm; Positioning by oil baffle ring is taken between the right end of the gear and the right bearing. It is known that the width of the hub of the high-speed large gear wheel b2 = 50mm, in order to press gears reliably, this section should be slightly shorter than the width of the hub, then take l45 = 48 mm. Shaft shoulder positioning is adopted in the left end of the gear, the height of shaft shoulder h = (2~3)R. Refer to the table with trunnion d45 = 38 mm, take h = 5 mm, then the diameter of Collar point d34 = 48 mm. Collar width b≥1.4h, take l34 = 15 mm.
(3) Left end rolling bearing adopts oil baffle ring for axial positioning.
(4) Considering about material and machining economy, low speed pinion and shaft should be designed and manufactured separately. It is known that the hub width of the low-speed pinion is b3= 85mm, in order to make the end face of oil retaining ring press the gear reliably, this section should be slightly shorter than the width of the hub, so take l23 = 83 mm，d23=38mm。
(5) Take the distance between the low-speed pinion and the inner wall of the boxΔ1 =10 mm, the distance between the high speed big gear and the inner wall of the box Δ2 =12.5 mm, the distance between high speed main gear and low speed pinionΔ3=15mm. Consider housing casting error, when determining the position of rolling bearing, should be from a distance Δ casing wall, take Δ = 10 mm, then:
At this point, the diameter and length of each section of the shaft have been preliminarily determined.
Shaft section 1 2 3 4 5
Diameter/ mm 35 38 48 38 35
Length/ mm 39 83 15 48 41.5
3. Force analysis of the shaft
The circumferential force on a high speed pinion Ft2 (d2 is the diameter of the indexing circle of the high-speed pinion)
Radial force on a high speed pinion Fr2
Axial force on a high speed pinion Fa2
Circumferential force on the low-speed pinion Ft3 (d3 is the dividing circle diameter of the low-speed pinion)
Radial force on a low speed pinion
The axial force on a low speed pinion
According to 7207AC angular contact manual, pressure center a=21mm
Distance from bearing pressure center to middle point of low-speed pinion:
Distance from the midpoint of the low-speed pinion to that of the high-speed large gear:
Distance from the middle point of the high-speed large gear to the bearing pressure center:
(1) Calculate the reaction force of the shaft
Horizontal support reaction
Vertical support reaction
(2) Calculate the bending moment of the shaft and draw the bending moment diagram
The horizontal bending moment at section B
The horizontal bending moment at section C
The vertical bending moment at section C
The vertical bending moment at section B
Draw the bending moment diagram of horizontal plane (fig.b) and vertical plane (fig.c)
The resultant bending moment at section B
The synthetic bending moment of section C:
Make composite bending moment diagram (figure d)
Make torque diagram (figure e)
Figure 7-4 force and bending moment of jack shaft
4. Check the strength of the shaft
Because the bending moment on the left side of B is large and the action has torque, the left side of B is the dangerous section.
Its bending section coefficient:
Its torsion cross section coefficient:
The maximum bending stress:
Its shear stress:
Check and calculate according to the strength of bending and torsion. For the shaft of one-way drive, torque is processed according to pulsating cycle. Therefore, the reduced coefficient is adopted α=0.6, then the equivalent stress is
Check the table, get 40Cr(tempering and tempering) treatment, and the limit of tensile strength σB=640MPa; Then the allowable bending stress of the axis [σ-1b]=60MPa, σca<[σ-1b], so the strength is good.
7.3 Calculation of low speed shaft
1. Select the material on the shaft, and determine the allowable stress
Because the reducer is a general machine, there is no special requirements, so choose 45 (quenched and tempered), the hardness: 240HBS. Referring table 15-1, take σb=640MPa, σ-1b=60MPa
2. According to the initial torsion strength, the minimum diameter of the shaft estimated
Refer to table 15-3, take A0=112, then:
Shaft end has 1 keyway, so increase shaft diameter by 7%
According to the table, the diameter of the standard axle hole is 50mm, so d=50
Figure 7-5 Schematic diagram of low-speed shaft
(1) The minimum diameter of the output shaft is obviously the diameter d1 of the shaft where the coupling is mounted. In order to make the selected shaft diameter d1 match the coupling aperture, it is necessary to select the type of coupling.The calculated torque of the coupling Tca = KA×T, refer to the table, consider about stability, then take KA = 1.3，thus:
According to the condition that the torque Tca of the coupling should be less than the nominal torque of the coupling, check the standard GB t4323-2002 or the design manual, choose LX4 type coupling. The aperture of the semi-coupling is 50mm, the hub hole length of fitness of the semi-coupling and the shaft is 112mm. Choose ordinary flat bond, A type bond, b×h = 14×9mm(GB T 1096-2003), length of bond L=100mm.
(2) Initial selection of rolling bearing. Because the bearing is subject to both radial and axial forces, angular contact bearing is chosen. According to work requirements and d23 = 55mm, angular contact bearing 7212AC is selected from the bearing product catalog, its size: d×D×B = 60×110×22mm, so d34 = d78 = 60 mm.
Positioning of bearing oil retaining ring. According to the manual, the positioning shaft shoulder height of type 7212AC bearing is h = 4.5mm, so d45 = 69mm
(3) Take the diameter of the shaft section where the gear is mounted d67 = 63 mm；The width of the low-speed large gear hub is known as b4 = 80 mm，in order to make the end face of the oil retaining ring press the gear reliably, this shaft segment should be slightly shorter than the width of the hub, so l67 = 78mm. The left end of the gear is fixed by the shaft shoulder. The height of shaft shoulder h = (2~3)R，The diameter of the shaft d67 = 63 mm, so take h = 10 mm, then the diameter at the collar d56 = 83 mm, take l56=10mm.
(4) Thickness of bearing end cover e=10, the thickness of the gasket Δt=2. According to the ease of mounting and dismounting of the bearing end cover, ensure that the outer end face of the bearing end cover has a certain distance from the end face of the coupling K=24, screw C1=22mm, C2=20mm, box seat wall thickness δ=8mm, then:
(5) Assume the distance between low level main gear and inner box wall Δ 2 = 12.5 mm, the distance between high speed main gear and low speed pinion Δ 3 = 15 mm distance. Consider housing casting error, when determining the position of rolling bearing, should be from a distance Δ casing wall, assume Δ = 10 mm, then:
At this point, the diameter and length of each section of the shaft have been preliminarily determined.
Shaft section 1 2 3 4 5 6 7
Diameter 50 55 60 69 83 63 60
Length 112 59 44.5 57.5 10 78 46.5
3. Force analysis of the shaft
Circumferential force on the low-speed big gear (d4 is the dividing circle diameter of the low-speed big gear)
The radial force on a large low speed gear
The axial force exerted on a large low-speed gear
Refer to the manual with 7212AC angular contaction, know pressure center a=30.8mm
(1)Calculate the supporting reaction of the shaft
Horizontal support reaction
Vertical support reaction
(2) Calculate the bending moment of the shaft and draw the bending moment diagram
The horizontal bending moment at section C
The vertical bending moment at section C
Draw the bending moment diagram of horizontal plane (fig.b) and vertical plane (fig.c)
The resultant bending moment at section C
(3) Make composite bending moment diagram (figure d)
Make torque diagram (figure e)
Figure 7-6 Diagram of force and bending moment of low speed shaft
4. Check the strength of the shaft
Because the bending moment on the left side of C is large and the action has torque, the left side of C is the dangerous section
Its bending section coefficient:
Its torsion cross section coefficient:
The maximum bending stress:
Its shear stress:
Check and calculate according to the strength of bending and torsion. For the shaft of one-way drive, torque is processed according to pulsating cycle. So the reduced coefficient =0.6, then the equivalent stress:
Refer to the the table, get 45(tempering) treatment, tensile strength limitσB=640MPa，then the allowable bending stress of the axis[σ-1b]=60MPa, σca<[σ-1b], so the strength is good.
Chapter 8 Rolling bearing life check
8.1 Bearing check on high speed shaft
Bearing code d(mm) D(mm) B(mm) Cr(kN) C0r(kN)
7206AC 30 62 16 22 14.2
Adopt 7206AC angular contact ball bearing, inner diameter d=30mm, outer diameter D=62mm, width B=16mm, Basic dynamic load rating Cr=22kN，Rated static load C0r=14.2kN.
Life expectancy is Lh=48000h.
According to the horizontal and vertical bearing reaction calculated previously, we can calculate the resultant bearing reaction：
Axial force Fae=435N
According to the calculations, bearing 1 is "pressed", while bearing 2 is “relaxing”.
Refer to the table, X1=0.41，Y1=0.87，X2=1，Y2=0
Refer to the table, ft=1，fp=1
Then, take the bigger one into
Bearing life is sufficient.
8.2 Bearing check on the jack shaft
Bearing code d(mm) D(mm) B(mm) Cr(kN) C0r(kN)
7207AC 35 72 17 29 19.2
Adopt 7207AC angular contact ball bearing, inner diameter d=35mm, outer diameter D=72mm, width B=17mm, Basic dynamic load ratingCr=29kN, Rated static load C0r=19.2kN
Life expectancy is Lh=48000h.
According to the horizontal and vertical bearing reaction calculated previously, we can calculate the resultant bearing reaction：
Axial force Fae=775N
According to the calculations, bearing 1 is "pressed", while bearing 2 is “relaxing”.
Refer to the table, X1=0.41，Y1=0.87，X2=1，Y2=0
Refer to the table, ft=1，fp=1
Then, take the bigger one into
Bearing life is sufficient.
8.3 Bearing check on the low speed shaft
Bearring code d(mm) D(mm) B(mm) Cr(kN) C0r(kN)
7212AC 60 110 22 58.2 46.2
Adopt 7212AC angular contact ball bearing, inner diameter d=60mm, outer diameter D=110mm, width B=22mm, Basic dynamic load rating Cr=58.2kN，Rated static load C0r=46.2kN
Life expectancy is Lh=48000h。
According to the horizontal and vertical bearing reaction calculated previously, we can calculate the resultant bearing reaction：
Axial force Fae=1145N
According to the calculations, bearing 1 is "pressed", while bearing 2 is “relaxing”.
Refer to the table, X1=0.41，Y1=0.87，X2=1，Y2=0
Refer to the table, ft=1，fp=1
Then, take the bigger one into
Bearing life is sufficient.
Chapter 9 Key connection design calculation
9.1 Calculation check of coupling key connection
The chosen type of key is A-type: 6×6（GB/T 1096-2003）
Working length of key: l=L-b=40-6=34mm
Contact height of the hub keyway: k=h/2=3mm
According to the material of the coupling which is 45 and the stability of loading, we can get [σp]=120MPa, then it’s compression strength is
It meets the strength requirement.
9.2 Calculation check of low speed pinion’s key connection
The chosen type of key is A-type: 10×8（GB/T 1096-2003）
Working length of key: l=L-b=70-10=60mm
Contact height of the hub keyway: k=h/2=4mm
According to the material of the low speed pinion which is 40Cr and the stability of loading, we can get [σp]=120MPa, then it’s compression strength is
It meets the strength requirement.
9.3 Calculation check of high speed main gear’s key connection
The chosen type of key is A-type: 10×8（GB/T 1096-2003）
Working length of key: l=L-b=36-10=26mm
Contact height of the hub keyway: k=h/2=4mm
According to the material of the high speed main gear which is 45 and the stability of loading, we can get [σp]=120MPa, then it’s compression strength is
It meets the strength requirement.
9.4 Calculation check of low speed main gear’s key connection
The chosen type of key is A-type: 18×11（GB/T 1096-2003）
Working length of key: l=L-b=63-18=45mm
Contact height of the hub keyway: k=h/2=5.5mm
According to the material of the low speed main gear which is 45 and the stability of loading, we can get [σp]=120MPa, then it’s compression strength is
It meets the strength requirement.
Chapter 10 Coupling selection
10.1 Coupling on the high speed shaft
（1）Calculate the load on the coupling
Refer to the table, the load coefficient of the coupling is KA=1.3
Then calculate the torque is Tc=KA×T=1.3×48.84=63.5N•m
（2）Select the type of coupling
Primary coupling model is LX3 elastic pin coupling (GB/ t4323-2002). Refer to the table, Nominal torque Tn=1250N•m, Allowable speed[n]=4700r/min, thus:
Tc=63.5N•m1.2δ 12mm
Distance between gear face and inner box wall △2 >δ 12.5mm
Case cover and seat rib thickness m1、m m1≈0.85×δ1、m≈0.85×δ 8mm、8mm
Outer diameter of high speed bearing end cap D1 D+(5～5.5)d3；D--bearing outer diameter 102mm
Outer diameter of end cover of jack bearing D2 D+(5～5.5)d3；D--bearing outer diameter 112mm
Outer diameter of low speed bearing end cap D3 D+(5～5.5)d3；D--bearing outer diameter 150mm
Chapter 14 Drawing of structure analysis of reduce
14.1 Drawing of assembly
14.2 Housing
14.3 Drawing of gears
High speed main gear
Low speed pinion
14.4 Drawing of shafts
High speed shaft
Jack speed shaft
Low speed shaft
Chapter 15 Conclusion
15.1 Summary
After hard work, I finally finished the mechanical design course. In the process of this operation, I encountered many difficulties. The repeated calculation and the design scheme modification exposed my lack of knowledge and experience in this aspect in the early stage, and I learned the lesson of blind calculation. As for drawing assembly drawing and part drawing, due to sufficient preliminary calculation, the whole process took less than three days. During this period, I also received a lot of help from my classmates and teachers. Here I would like to express my most sincere thanks to them.
Although the time of this assignment is long and the process is tortuous, for me, the biggest gain is the method and ability. The ability to analyze and solve problems. In the whole process, I found that what students like us most lack is experience, no perceptual knowledge, empty theoretical knowledge, and some things may be out of touch with the reality.
In general, I think doing this type of homework is of great help to us. It requires us to systematically connect the relevant knowledge we have learned, expose our shortcomings and make improvements. Sometimes a person's power is limited, the wisdom of all people, I believe our work will be more perfect!
Due to the limited time, there are many shortcomings in this design, such as the huge box structure and large weight. The gear calculation is not accurate enough and other defects, I believe, through this practice, I can avoid a lot of unnecessary work in the future design, have the ability to design a more compact structure, transmission more stable and accurate equipment.
15.2 Job description of team members
Team leader: 陈旭颖
Finish the designation and calculation of transmission device, motor, dynamic parameters, rolling bearings, keys and couplings.
Draw the CAD of assembly drawing and reducer housing drawing.
Write the design specification.
Team members: 方琢
Finish the designation and calculation of high speed gear, jack gear and low speed gear.
Draw the CAD of high speed gear, jack gear and low speed gear.
李成雍
Finish the designation and calculation of high speed shaft, intermediate shaft and low speed shaft.
Draw the CAD of high speed shaft, intermediate shaft and low speed shaft.
Reference
[1] Kunwoo Lee, Principles of CAD/CAM/CAE Systems, Pearson, Jan., 1999.
[2] Chris McMahon and Jimmie Browne, CAD/CAM Principles, Practices and Manufacturing
Management (2/e), Prentice Hall, July, 1999.
[3] Andrew D. Dimarogonas, Machine Design - A CAD Approach, John Wiley & Sons, Dec. 2000.
[4] E. Paul Degarmo, J. T. Black and Ronald A. Kohser, Materials and Processes in Manufacturing
(11th edition), Wiley, Dec. 2011.
[5] 李育锡. 机械设计课程设计（第⼆版）. 北京：⾼等教育出版社. in Chinese
[6] 陈秀宁. 机械设计课程设计(第四版). 杭州：浙江⼤学出版社. 2010. in Chinese
[7] 吴宗泽. 机械设计课程设计. 北京：⾼等教育出版社. 2007. in Chinese
[8] 闻邦椿. 机械设计⼿册 1-6 卷(第五版). 北京：机械⼯业出版社. 2011. in Chinese
Attachment
1.The drawing of assembly;
2.The drawing of reducer housing;
3.The drawing of pinion;
4.The drawing of main gear;
5.The drawing of low speed shaft;
6.The drawing of jack shaft;
7.The drawing of high speed shaft;
2022-07-07 09:50:27
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