Questions and answers on machining process knowledge, essential foundation for qualified engineers

1. What are the three methods of clamping workpieces?
{1. Clamp in the fixture; 2. Find the correct clamp directly; 3. Mark the line and find the correct clamp}
2. What does the process system include?
{machine tools, workpieces, fixtures, tools}
3. What are the components of the mechanical processing process?
{roughing, semi-finishing, finishing, super-finishing}
4. How are benchmarks classified?
{1. Design basis 2. Process basis: process, measurement, assembly, positioning: (original, additional): (coarse basis, fine basis)}
What does processing accuracy include?
{1. Dimensional accuracy 2. Shape accuracy 3. Position accuracy }
5. What does the original error that occurs during the processing include?
{Principle error · Positioning error · Adjustment error · Tool error · Fixture error · Machine tool spindle rotation error · Machine tool guide rail error · Machine tool transmission error · Process system stress deformation · Process system thermal deformation · Tool wear · Measurement error · Workpiece residual stress Error caused by
6. What is the impact of process system stiffness on machining accuracy (machine tool deformation, workpiece deformation)?
{1. Workpiece shape error caused by changes in the position of the cutting force application point 2. Processing errors caused by changes in the size of the cutting force 3. Processing errors caused by clamping force and gravity 4. The impact of transmission force and inertia force on processing accuracy}
7. What does the guidance error of the machine tool guide rail and the spindle rotation error include?
{1. Guide rail mainly includes the relative displacement error between the tool and the workpiece in the error-sensitive direction caused by the guide rail 2. Spindle radial circular runout, axial circular runout, and inclination swing}
8. What is the phenomenon of "error re-image"? What is the error reflection coefficient? What measures are taken to reduce error re-images?
{Due to changes in process system error deformation, the blank error is partially reflected on the workpiece. Measures: increase the number of tool passes, increase the stiffness of the process system, reduce the feed amount, and improve the blank accuracy}
9. Analysis of transmission error of machine tool transmission chain? Measures to reduce transmission chain transmission errors?
{Error analysis: that is, measured by the rotation angle error Δφ of the end element of the transmission chain
Measures: 1. The fewer the number of transmission chain parts, the shorter the transmission chain, the smaller Δφ, and the higher the accuracy. 2. The smaller the transmission ratio I, especially the transmission ratio at the first and last ends. 3. Since the end parts of the transmission parts The error has the greatest impact, so it should be made as accurate as possible 4. Use a correction device }
10. How to classify processing errors? What errors are constant errors? What errors are variable-valued systematic errors? What errors are random errors?
{System error: (constant value system error, variable value system error) random error
Constant system error: processing error caused by processing principle error, manufacturing error of machine tools, tools, fixtures, stress deformation of the process system, etc.
Variable value system error: wear of props; thermal deformation error of tools, fixtures, machine tools, etc. before thermal balance
Random errors: copying of blank errors, positioning errors, tightening errors, errors of multiple adjustments, deformation errors caused by residual stress }