MindMap Gallery Mechanical-Interchangeability and Technical Measurement Chapter 4 Mind Map
A mind map on Chapter 4 of Mechanical Interchangeability and Technical Measurement, including basic terminology and evaluation of surface roughness, Selection of surface roughness and its labeling, etc.
Edited at 2023-12-05 01:01:17One 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.
Chapter 4 Surface Roughness Measurement
Overview
The concept of surface roughness
After surface processing of parts, tiny peaks and valleys will be produced. The height and spacing of these peaks and valleys are called surface roughness. It is a microscopic geometric shape error, also known as microscopic roughness
Effect of surface roughness on parts performance
friction and wear
Matching properties
corrosive
fatigue strength
Joint surface sealing
Basic terminology and evaluation of surface roughness
Basic terms and definitions
surface profile
The intersection of a specified plane and the actual plane Profile, refers to the transverse surface profile⊥processing texture
Sampling length lr
A reference length specified for measuring and evaluating surface roughness
Evaluation length ln
A length necessary to evaluate the surface structure requirements on the drawing2
Contour filter
An instrument that separates surface profiles into long and short waves
conveyor belt
A wavelength range obtained by separating two filters with different cutoff wavelengths
Contour center line
A reference line for evaluating the numerical value of surface roughness
Surface profile geometry parameters
contour peak
silhouette valley
Profile peak height Zp
Contour valley depth Zv
Contour unit
Profile wish height Zt
Contour unit width xs
Surface roughness evaluation parameters and their values
Contour arithmetic mean deviation Ra
Maximum profile height Rz
Average width of contour unit Rsm
Profile support length ratio Rcr (c)
Rules for comparing measured values with limit values
16% principle
When the number of all measured parameter values exceeding the given limit value does not exceed 16% of the total number, the surface is qualified.
maximum rule
All measured parameter values should not exceed the given limit values
Selection and marking of surface roughness
Selection of surface roughness assessment parameters
In general, choose from the height parameters Ra and Rz
When Ra is 0.025-6.3μm, the Ra value is preferred (because Ra can fully reflect the characteristics of the surface profile of the part, the measurement method is simple, and the measurement efficiency is high)
When Ra>6.3μm or Ra<0.025 μm, Rz can be selected (because this range facilitates the selection of instruments for measuring Rz)
When the part material is soft, Ra is usually measured with a stylus.
Selection of parameter values for surface roughness assessment
On the premise of meeting the functional requirements, a larger roughness value should be used as much as possible
On the same part, the roughness value of the working surface is smaller than the roughness value of the non-working surface
The friction surface has a smaller roughness value than the non-friction surface; rolling friction table The roughness value of the surface is smaller than that of the sliding friction surface
Surfaces with high moving speeds, heavy loads, and important parts subject to alternating loads should have smaller surface roughness values for fillets and grooves.
The precision of joint surfaces, dimensional tolerances and geometric tolerances that require high matching accuracy For surfaces with high requirements, choose a small value for roughness.
For parts with the same tolerance level, the surface roughness of small sizes and shafts is smaller than that of large sizes and holes.
The surface roughness value that requires anti-corrosion, good sealing performance, or beautiful appearance should be small.
Where relevant standards have stipulated surface roughness requirements (such as journals and housing holes that cooperate with rolling bearings, keyways, gear working surfaces, etc.), the surface roughness value should be determined according to the corresponding standards.
Marking of surface roughness symbols and codes on drawings
Graphical symbol for surface roughness
Marking of surface roughness
How to mark surface roughness requirements on drawings
Marking position of surface roughness requirements on the drawing
Simplified injection method for surface roughness requirements
The same surface injection method obtained by two or more processes
Measurement of surface roughness
comparative method
Assess surface roughness by comparing the measured surface to a roughness template
Needle drawing
It is a contact method for measuring surface roughness. Commonly used measuring instruments are electric profilometers
light section method
Use the "light section principle" to measure surface roughness. The commonly used instrument is a light section microscope to measure the Rz value, 0.5-60μm