MindMap Gallery Mechanical Design
Regarding the mechanical design mind map, it includes connection design, basic knowledge, transmission design, shafts, etc. Hope this mind map helps you!
Edited at 2023-12-24 19:37:59One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
Project management is the process of applying specialized knowledge, skills, tools, and methods to project activities so that the project can achieve or exceed the set needs and expectations within the constraints of limited resources. This diagram provides a comprehensive overview of the 8 components of the project management process and can be used as a generic template for direct application.
One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
Project management is the process of applying specialized knowledge, skills, tools, and methods to project activities so that the project can achieve or exceed the set needs and expectations within the constraints of limited resources. This diagram provides a comprehensive overview of the 8 components of the project management process and can be used as a generic template for direct application.
Mechanical Design
Join design
6: Thread Page 73
Types and parameters
Threaded connection
bolt
studs
screws
Set screw
Spiral connection (transmission)
Slide (cast tin bronze)
scroll
static pressure
Performance level
Bolt Stud Screw (3.6)
Nut (4 04) medium carbon steel
Tighten (M12 variable load)
Anti-loosening (preventing the thread pair from rotating)
Friction (Spring Washer)
Direct locking (head pin, stop washer, series wire)
Destroy the thread pair (weld)
Invalid
Static load (plastic deformation and fracture of threads)
Variable load (fatigue fracture of bolt rod 65 20 15)
Horizontal (shearing and crushing)
Strength calculation
be pulled
Lateral force plus preload
Working load plus preload
variable load
Shear (shear stress and compressive stress)
Bolt group design
Axial symmetry, even number, avoid bending load, small stress in the middle, fewer bolts
Axial
Horizontal
be pulled
to be sheared
Rotating torque
be pulled
to be sheared
Turning moment
Improve bolt connection strength (improve fatigue strength)
Reduce stress amplitude
Reduce bolt stiffness (increase, reduce diameter, hollow)
Increase the stiffness of the connected parts (seal ring, gasket with high stiffness)
Uniform stress on thread teeth (due to the different deformation properties of bolts and nuts, the threads below the nut are stressed)
Suspension nut (consistent deformation)
Internally inclined nut (reduces the force on the bottom)
Ring groove nut (deformable)
wire nut
Reduce additional stress and stress concentration
Avoid bending stress
Increase the fillet radius at the tooth root
Proper preload
Rectangular transmission has the highest efficiency
Hub(60)
key connection
Flat key
ordinary
ABC Week
Guide flat key, feather key, peripheral➕shaft➕dynamic connection
Semicircle (tapered, greatly weakened)
wedge bond
120° tangential direction, large torque transmission
Large transmission torque: flat➕cut Centering accuracy: flat Dynamic: guide and slide keys, others are static Axial direction: wedge cut Shaft end: semicircular flat key C
The area depends on the diameter and the length depends on the hub.
Failure: crushing, wear and tear
Strength calculation formula
Double bond requirements and calculation formulas
spline
Three centering methods for rectangular splines
Involute tooth centering 30 45
advantage
strength formula
Pin connection, safe positioning, cylindrical conical groove
Transmission design
Belt drive (122)
Advantages and Disadvantages
Classification
flat belt
V-belt (40°)
The pulley should be less than 40° (the tension wedge angle of the belt should be reduced ➕ and should be tightened)
Force analysis
formula for two forces
Stress distribution diagram
Concepts of elastic sliding and slipping Consequences Differences
Failure (slip and fatigue damage)
Ultimate speed and optimal speed
Ways to improve work ability
Increase the friction coefficient (v with good equivalent friction coefficient)
Increasing the wrap angle (reduce the transmission ratio, increase the center distance, tensioning device) can increase the effective pressure
Optimum rotation speed High-strength materials
Coefficient selection
Minimum diameter (fatigue damage due to bending stress)
The wrap angle is not less than 120° and the transmission ratio is not more than 7
If the center distance is too large, it will vibrate; if it is too small, it will cause fatigue damage and the wrap angle will be small.
If the tension is too small, the friction will be small and it will slip easily; if the tension is too large, the service life will be short.
The number of V-band roots is less than 12➕Formula
The model depends on the calculated power and small pulley speed.
tensioning device
Regularly (the tensioner is installed inside the loose edge)
automatic tensioning
Gear transmission (147)
Advantages and Disadvantages
coefficient
Tooth profile angle 20°, tooth top height m, working tooth height 2m, top clearance 0.2m
12 levels of accuracy, level 1 is the highest (movement accuracy, smooth transmission, uniform load)
Pitch circle pressure angle, pitch circle diameter, center distance, tooth addendum height, tooth root height, pitch circle pitch, base circle pitch
The fundamental purpose of the displacement coefficient is that as the gear changes, the shape of the gear teeth also changes, so that different parts of the involute line can be used as working tooth profiles (divided into height displacement and angle displacement)
Failure (gear failure) Increase hardness, reduce roughness and add lubrication
Broken gear teeth
Caused by fatigue or overload
Surface strengthening increases stiffness
Tooth surface pitting/contact fatigue wear (closed transmission)
Where and why it happened
No open type
Tooth surface bonding (high speed and heavy load)
Tooth surface abrasive wear
Two kinds
measure
Plastic flow on tooth surface (low speed, heavy load, frequent starts)
Closure considers pitting, breaking, gluing Consider breakage and abrasive wear
Gear material (small tooth surface with high hardness)
Forged steel Cast steel Cast iron Non-metallic materials
Heat treatment method
Force analysis
three forces
Axial force is used on the driving wheel. For right-hand rotation, use your right hand: hold the axis, four fingers in the direction of rotation, and thumb in the direction of axial force. Opposite driven wheel
Circumferential force is the same as the direction of rotation.
Radial force, refers to the center of the circle
It must be a left-hand rotation and a right-hand rotation.
Method for judging left and right rotation (four-finger axis, thumb is the tilt direction)
subtopic
Calculate load analysis and four coefficients
Spur gear strength calculation
Tooth surface contact fatigue strength calculation (two formulas)
Calculation of tooth root bending fatigue strength (two formulas, selection of the number of pinion teeth, different open and closed calculation methods)
Helical gear (better meshing but produces axial force) strength calculation: the formula is similar to the above, multi-helix angle β
Spur gear precision requires low noise, large vibration, and large peripheral speed
lubricating
effect
Open manual periodic
Closed oil immersion and oil injection (reason) The amount of oil depends on the power transmitted by the gear. The viscosity of the lubricating oil is selected according to the peripheral speed.
Transmission efficiency (three losses)
Worm drive (197)
Advantages and Disadvantages
Failure (pitting corrosion, tooth root fracture, tooth surface gluing, abrasive wear, the latter two are the main forms)
The main turbine gear failed and a small number of worm rods had insufficient stiffness.
closed type
Open type
Material
Require
Worm alloy steel carbon steel
Four types of worm gears
Integral type (cast iron material or small diameter) and assembled type of worm gear
parameter
Modulus pressure angles are equal
Pitch circle diameter of worm (look up table) and diameter coefficient (stiffness)
Different ways to determine the number of worm heads and the minimum number of worm gear teeth
Lead angle formula and too large or too small
Transmission ratio (not equal to diameter ratio)
Standard center distance (integer)
The purpose of transmission displacement
Worm gear remains unchanged Worm gear changes
different and same
Force analysis
Radial force refers to the axis center
The circumferential force and the rotational speed direction are the same as the master and the slave.
Right-hand rule for axial force of worm gear, reaction force of worm gear
If the worm rotates right, the worm gear must also rotate right.
Efficiency is the same as gear ➕ meshing efficiency formula
Strength calculation (only look at worm gear)
Contact fatigue formula
Bending fatigue formula
Worm stiffness formula (maximum deflection)
Lubrication: closed type is divided into three types according to speed, open type has higher viscosity
Thermal equilibrium
reason
formula
Measures to improve heat dissipation capacity
4 measures to improve transmission performance (increasing lubrication and reducing wear)
Chain Drive(226)
Advantages and Disadvantages
Three categories of chains
Transmission chain structure
The number of multi-row chains should not exceed 4. Multiple three-row chains can be used to transfer large loads.
If the number of links in a chain is an even number, a connecting link will be used, and if the number is odd, a transition link will be added (rarely used but can be used in heavy load impact situations)
Marking of roller chain Chain number - number of rows x number of sections
Tooth chain (tooth wedge angle 60 or 70°) three forms
Large sprocket cast iron Small sprocket steel (more meshing times and harder)
unevenness
average chain speed formula
Average gear ratio and instantaneous gear ratio formulas
Three causes and influencing factors of dynamic load
Force analysis (tighten up and loosen down)
Six formulas for forces
6 failure modes
parameter
The consequence of too few teeth (4) or too many (1) is an even number of chain links and a prime number for the sprocket.
Transmission ratio is about 3
power
The consequences of too large or too small number of chain links
Center distance too large or too small
How are the two sprockets distributed? The tight side is on top.
Purpose and method of tensioning The tensioning device is placed on the loose edge of the driving wheel, and the diameter is close to the small sprocket.
Lubricant and loosen edges
axis
Shaft(247)
Classification
Spindle spindle transmission bearing
Material
Three selection factors
Two notes
structural design
Dimensions and functions of fillet at shaft shoulder
Each keyway on a shaft should be on the same busbar. The mating diameter of the shaft is rounded to a standard value to facilitate assembly.
The diameter of the shaft is related to the size of the load. The length should be as compact as possible.
Strength design to prevent shaft breakage
Twist the two formulas ➕ compensate for the keyway
Bending and twisting into a formula
Safety factor
Three formulas under fatigue strength
Three formulas under static strength
4 measures to increase strength
Stiffness to prevent excessive elastic deformation High-speed shafts need to prevent resonance
Sliding bearings (274)
The location and function of oil holes and oil grooves
Material (Bearing Bush, Bearing Lining)
Three failure modes of bearing bushes and their material requirements
Three commonly used materials and properties
Bearing seats are often cast iron
lubricating
Principles for lubricating oil selection Viscosity
Lubrication method
Oil lubrication (intermittent and continuous)
Grease lubrication intermittent
Lubrication method determination formula
Bearing calculations
non-liquid lubrication
Three formulas and reasons for calculating radial conditionality
Two formulas for thrust
hydrodynamic pressure
Formation principle (viscosity, sliding speed, convergence gap, oil supply amount)
As the speed increases and the load decreases, the eccentricity increases
Calculation process (4 formulas)
coefficient
Width to diameter ratio B′/d Small means it takes up less space, has strong pressure, and has high stability. If it is large, the oil leakage from the bearing end will be small (d is small), the load-bearing capacity will be high (B is large), and the temperature rise will be high (more inflow and less outflow, and the temperature cannot be brought out)
The relative gap ψ is selected according to the load and speed. The higher the speed, the larger the ψ, which can reduce heat generation. The larger the load, the smaller the ψ, which can improve the carrying capacity.
A large average pressure can reduce the bearing size and run smoothly. If it is too large, it will be easily damaged.
The greater the viscosity, the thicker the oil will be. If it is too high, it will easily generate heat.
hydrostatic pressure
Features: The lubrication state has little relationship with oil pressure and speed. There is an oil film even at low speeds. Increasing the oil pressure can improve the load-bearing capacity. The speed is not high, so the bearing friction coefficient is small.
rolling bearing
Advantages and Disadvantages
type
Centripetal (radial load) Thrust bearing (axial load) Centripetal thrust
Aligning ball bearing 1 (the structure code is the type code
Tapered roller bearings 3
Thrust ball bearing 5
Deep groove ball bearings 6 most commonly used
Angular contact ball bearings 7
Roller bearing N
The larger the contact angle, the stronger the load-bearing capacity
Codename = prefixed codename basic codename suffixed codename For example, 7310C/P5
The prefix code is as above
Basic code = type code size (width/height ➕ diameter width is 0 can be omitted) inner diameter code (when the inner diameter code is 04-96, the real nominal diameter is the code ✖️5 unit㎜ when the inner diameter is 22 28 35 and greater than 500, etc. When adding /) before the inner diameter code
suffix code
Internal structure code: The letters C AB B represent the contact angles of 15, 25 and 40° respectively.
Tolerance grade code letter P number combination 0 is the lowest grade
The clearance code C and the number represent accuracy
Configuration code /DB back-to-back DF face-to-face DT series
choose
The roller load capacity is greater than the ball High-speed ball selection (small point contact friction) Corners or deep grooves can replace thrust Cylindrical rollers and needles are most sensitive to deflection Balls are cheaper than rollers
Work analysis
Carrying area actual and expansion
two formulas
Failure: Fatigue pitting (normal speed) Plastic deformation (low speed) wear gluing
life calculation When it comes to longevity, reliability must be included
The meaning of basic quota life
Meaning of basic rated dynamic load C
Cr Ca 90%
4 calculation formulas
Four cases of equivalent dynamic load P
Angular contact ball bearings and tapered roller bearings
After being subjected to radial load, a derived axial force Fs is generated (the direction is from the small mouth to the large mouth) Small mouth to small mouth, that is, back to back, reverse installation Size: C AB B corresponds to Fs equal to (e 0.68 1.14) Fr
Calculation: First write down the external radial and axial forces, the radial load obtained by balancing the bearing force, and the derived axial force obtained by the above formula. All forces are added up to get the total force direction (moving in the direction of the force) Bearings that move in the same direction as the derived axial force are relaxed, and bearings that move in the opposite direction are tightened. The axial load of a relaxed bearing is equal to its own derived axial force, and the compressed bearing is equal to the relaxed derived axial force ➕external axial force
First calculate the force of each bearing according to the above According to the formula and table, the XY index is obtained and the equivalent load is obtained Take the maximum equivalent load and bring it into the life calculation formula to calculate the time.
Static load three C's and three formulas
The preload of the bearing generates a certain axial force to eliminate the axial clearance, and generates elastic pre-deformation at the contact point between the roller and the raceway to improve accuracy.
Lubrication depends on dn value
Cooperate
Inner ring and journal base hole system
The outer ring and bearing seat base shaft system have one-way negative deviation.
It is important to tighten the rotating ferrule, it is important to work hard, and it is important to loosen it when it is removed frequently.
basic knowledge
introduction
Three parts make up the machine
What requirements does the machine meet?
Three design methods
Mechanical design steps
Mechanical parts design steps
Five calculation methods
Standardized design and advantages
Strength of parts (8)
Main reason for failure
load
static change
Nominal calculation (taking into account unevenness)
Load factors depend on working machine and prime mover performance
stress
static three changes
five parameters
strength criterion
two formulas
Life Criteria Three Factors
reliability criteria
Invalid
4 forms
5 ways to increase strength
Three surface strength formulas
Stiffness and flexibility
3 ways to improve stiffness
Vibration Avoid resonance
4 ways to reduce
Impact strength formula
4 types of relief
Fatigue design of parts (20)
Three characteristics and causes of fatigue section Two processes
Fatigue limit definition
Material fatigue curve
formula
Four districts
Effect of Cyclic Characteristics
life coefficient
Fatigue limit stress diagram of materials
The difference between plastic and brittle
Three point coordinates
image
Three coefficients and comprehensive formula of fatigue strength of parts
Fatigue limit stress diagram of parts
Part fatigue safety factor calculation
Stress Amplitude Calculation Fatigue Zone
Static strength plastic zone
fatigue accumulation hypothesis
The total work is equal
Total damage rate formula
Equivalent stress Equivalent maximum times Equivalent times
Friction and wear lubrication (37)
friction
Classification
Changes in friction coefficient
adhesion theory
Three Boundary Films (Operating Temperature)
wear and tear
three stages
4 classifications and mitigation methods
lubricating
Five functions
lubricating oil
viscosity
power
sports
condition
Viscosity-temperature characteristics: large index, small change
sticky pressure
Lubricity Extreme pressure Flash point Freezing point Oxidation stability
Four types of grease and their characteristics
Cone penetration depth
Dropping point (determines the operating temperature below the dropping point)
Three functions of additives
Lubrication type three film thickness ratio
Sealing function and classification
static seal
direct contact
Non-contact such as washers
move
rotate
Contact such as oil seal
Non-contact gap seal
back and forth