First of all 、 Two chapters —— Introduction to mechanical design 、 General

Of mechanical parts “ Three ways ” It refers to the standardization of parts 、 Component generalization 、 Product serialization

The basic components of a machine are mechanical parts

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2.1 The composition of the machine

Machines are usually made up of prime mover parts 、 The transmission part 、 Executive part 、 Auxiliary system 、 Composition of measurement and control system

1. The prime mover part is the power source that drives the whole machine to complete the predetermined function
2. The executive part is a part used to complete the predetermined functions of the machine
3. The transmission part is used to complete the form of motion 、 Transformation of motion and dynamic parameters

2.3 The main requirements for the machine

Functional requirements for use
Economic requirements
Labor protection and environmental protection requirements
Life and reliability requirements
Other special requirements

2.4 The main failure forms of mechanical parts

1. Integral fracture
2. Excessive residual deformation
3. Surface damage of parts
4. Failure caused by destruction of normal working conditions

2.5 Basic requirements to be met when designing mechanical parts
One ） Requirements to avoid failure within the predetermined service life

1. Strength
2. stiffness
3. life

When calculating mechanical parts , Use σ＜ [σ] That is, check and calculate according to the criterion that the working stress is less than the allowable stress , The calculation uses Strength Rules
When designing and calculating mechanical parts , Use y＜ [y] That is, check and calculate when the working deflection is less than the allowable deflection , The calculation uses stiffness Rules

The failure of mechanical parts refers to the failure within the expected life , Loss of normal working capacity of mechanical parts , Or fail to meet the performance required by the design

Two ） Structural and technological requirements
3、 ... and ） Economic requirements
Four ） Requirements for small quality
5、 ... and ） Reliability requirements

2.6 Design criteria for mechanical parts
Strength criterion
Stiffness criterion
Life criterion
Vibration stability criterion
Reliability criteria

The design methods of mechanical parts are : ( theoretical design 、 Empirical design 、 Model experiment design ）

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The third chapter —— Strength of mechanical parts

The main factors affecting the fatigue strength of mechanical parts , Mainly stress concentration 、 Part size 、 Surface condition and reinforcement

For parts subjected to cyclic variable stress , The main influencing factors of fatigue failure are cyclic characteristics and stress amplitude

3.1.1 Classification of loads and stresses

A normally functioning circular shaft , Subject to radial load , The cyclic characteristic of the bending stress on the outer surface of the shaft can be regarded as symmetry Cyclic variable stress
A normally functioning circular shaft , Subject to radial load , The cyclic characteristic of the bending stress on the outer surface of the shaft can be regarded as Asymmetric Cyclic variable stress
A circular shaft that rotates in one direction , Under the action of torque , The torsional shear stress on the outer surface of the shaft can be regarded as pulsation Cyclic variable stress

3.1.2 Strength of mechanical parts under static stress

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3.3 Fatigue curve of material

Under each stress , Parts will cause certain fatigue damage , When fatigue damage accumulates to a certain extent , Fatigue failure occurs , This is it. fatigue damage Linear accumulation hypothesis

3.4 Equal life fatigue curve of material （ Limit stress diagram ）

3.6

The fifth chapter —— Threaded connection

5.2 Basic types of threaded connections

5.3 Pre tightening of threaded connection

5.5 Stress analysis and strength calculation of single bolt connection

5.7 Stress analysis of threaded group connection

Four 、 Bolt group connection subject to overturning torque

Chapter viii. —— Belt drive

##8.3 Force analysis of belt drive

#8.4 The stress analysis and sliding of belt drive

The belt retreats at the driving wheel , Extend forward at the driven wheel

##5. V Belt drive

Chapter ten —— Gear drive

10.2 Stress analysis of gear transmission

Chapter 11 —— Worm drive

In standard worm drive , If the number of worm heads z1 And modulus m A certain , If the worm diameter coefficient is increased q, Then the lead angle γ Reduce

In the following drives , Worm drive Heat balance calculation must be carried out

The power loss of worm drive generally does not include Heat dissipation loss

Worm drive , The steering of the worm gear is related to the axial force direction of the worm contrary

In addition to strength calculation, worm drive , Still need to do Heat balance Calculation , Its fundamental purpose is Prevent gluing

In closed worm drive , The common form of failure is Gluing or pitting of worm gear tooth surface

Worm drive has self-locking property , So the requirement is Active parts

Compared with gear transmission , Worm drive has High transmission ratio 、 Smooth transmission And other outstanding advantages

The material of high-speed important worm drive worm gear should be Tin bronze

In standard worm drive , When other conditions are the same , Increase the number of worm heads z1, Relative sliding speed vs take Bigger

In order to improve the efficiency of worm drive , Should be selected Multi head worm

Standard worm drive center distance a, modulus m, Worm indexing circle diameter d1, Worm diameter coefficient q=d1/m

To meet the self-locking requirements , Number of worm heads z1 = 1

Worm gear ring is often made of bronze , Because bronze has good antifriction

The main failure form of closed worm drive is Pitting and gluing of tooth surface

The main disadvantage of worm drive is the difference between tooth surfaces Relative sliding speed It's big , Therefore, the efficiency of transmission is low 、 Higher temperature rise

Worm drive design , To carry out turbine Calculation of tooth contact fatigue strength

Heat balance calculation of closed worm drive , Its main purpose is to Prevent the lubricating oil temperature from being too high to worsen the lubricating conditions

In standard worm drive , If the number of worm heads z1 And modulus m A certain , If the worm diameter coefficient is increased q, Then the transmission efficiency Reduce

（ Worm drive 、 Gear drive 、V Belt drive 、 Chain drive ） The worm drive has the largest transmission ratio

Worm and turbine drive , Lord 、 The circumferential component force on the driven wheel is not a pair of forces and reactions

For the worm drive that transmits power , In order to improve efficiency , Within certain limits Increase the lead angle of the worm

Chapter 12 —— shafting

12.2 Shafting design

There are gaskets directly between the bearing cover and the base

Chapter 13 —— Rolling bearing