What are the basic knowledge of CNC lathes?

1. The expression method of mechanical drawing parts:


1. Views include: basic view (three attempts), partial view, oblique view.


2. The section view includes: full section view, half section view, partial section view.


3. The cross-sectional view includes: remove the cross-sectional view, and overlap the cross-sectional view.


4. Other expressions: Part drawing: used to know the drawings produced and inspected by workers. Assembly drawing: Know that workers assemble many parts into parts or complete machines. Part drawing---a set of graphics, complete dimensions , Necessary technical requirements, title bar. Assembly drawing---graphics, dimensions, technology, title bar, schedule, part number.


5. Dimensional tolerances include: basic tolerance, upper deviation, lower deviation


6. The fit system includes: over fit, interference fit, clearance fit.


7. Position tolerance Shape tolerance: straightness, flatness, roundness, cylindricity, line profile, surface profile. Position tolerance


8. Surface roughness. Surface roughness sample block unit um 3.2 Obtained by any method _3.2_ Method of removing the surface (method of casting) Method of not removing the material Ra flat method R2 contour microscopic unevenness height Ry Maximum angle of contour


9. The drawing method of the thread: External thread: large diameter thick solid line, small diameter thin solid line, and thick solid line for the stop line to indicate the problem!!!


1.) A pair of standard spur gears. The tangent is (D) A. Addendum circle B. Tooth heel circle C. Index circle D. Pitch circle Note: Pitch circle is tangent. No pitch circle Is the index circle.


2.) The maximum allowable value of the surface Ra obtained by any method is obtained by any method.


3.) Which position is often selected for the front view of bracket parts? (B) A. Measure B. Work C. Processing D. Installation 　　　


4.) The four elements of a complete size in the drawing are the size line, the size number, the size tolerance and the arrow (wrong)　　　　


Note: The size tolerance does not belong to the four elements. For example, the three elements are the size line, the size limit, and the size number.　


5.) The dimensioning requirements in the parts drawing are complete, correct, clear and reasonable. (right)


6.) Tolerance is the difference between the actual size of the processed part and the size of the drawing (wrong)