“M10”表示公称直径为10 mm、螺距1.5 mm的单线粗牙普通螺纹。
公差带代号为 6g 或 6H(公称直径≥ 1.6mm)时不标注。
Type of thread
According to the tooth type can be divided into triangle, trapezoid, rectangle, serrated and arc thread;
According to the direction of the thread can be divided into left and right rotation;
According to the number of spiral lines can be divided into single-line and multi-line;
It can be divided into cylinder and cone according to the shape of thread matrix.
Ii. Elements of thread
Threads consist of five elements: tooth type, nominal diameter, number of threads, pitch (or lead), and direction of rotation.
1. The tooth type
In the section area passing through the thread axis, the profile shape of the thread is called the tooth type. There are triangle, trapezoid, serrated, circular and rectangular teeth.
Thread type comparison: want to learn machining center programming plus Q1373929409 free access to learning materials and courses.
Diameter of 2.
Threads have large diameters (d, d), medium diameters (d2, d2), and small diameters (d1, d1). The nominal diameter is the diameter of the size of the thread.
The nominal diameter of common thread is the large diameter.
Male (left) female (right)
3. The line number
Threads formed along a helix are called single-thread threads, and threads formed along two or more helix threads evenly distributed along the axis are called multi-thread threads.
Single thread (left) double thread (right)
4. Pitch and lead
Pitch (p) is the axial distance between two adjacent teeth on the middiameter line.
Lead (ph) is the axial distance between two adjacent teeth on the same helix and two corresponding points on the middiameter line.
For single thread, lead = pitch; For multi-thread threads, lead = pitch × number of threads.
The thread that is screwed in when clockwise is called the right thread;
The thread that is screwed in when counterclockwise is called the left-hand thread.
Left hand thread right hand thread
Marking of threads
(1) ordinary thread
Common thread is the most widely used, screw fasteners (bolts, studs, screws, nuts and other parts) are generally common thread threads.
Common thread can be divided into coarse thread and fine thread. Fine tooth common thread is used in precision parts and thin - walled parts.
In the marking of threads, the pitch of fine tooth common thread must be injected, while that of coarse tooth common thread is generally not marked.
The marking of ordinary threads consists of five parts:
1) feature code
M (for common thread)
2) size code
Size code: nominal diameter × pitch (lead and pitch of multi-thread threads should be noted, common thread pitch of single-thread coarse teeth is not marked).
"M10" represents the single-thread coarse tooth common thread with nominal diameter of 10 mm and pitch of 1.5 mm.
"M10×1" represents the single-thread fine tooth common thread with nominal diameter of 10mm and pitch of 1mm.
2) tolerance zone code for common thread
Made up of tolerance grade (Numbers) and base deviation (outer thread in lowercase letters, inner thread in uppercase letters), e.g. 5g6g, 6g, 6H, 7H.
If the middle diameter tolerance zone and the top diameter tolerance zone have different codes, please note them separately, such as m10-5g 6g
The middle diameter and the top diameter tolerance zone code are the same, only a code, such as: M10× 1-7h
If the tolerance zone code is 6g or 6H(nominal diameter ≥ 1.6mm), it will not be marked.
3) the screwing length of ordinary threads
There are long, medium and short, respectively with the code L, N, S.
M10-5g6g-s is a thread of short screwing length
M10-7h-l are threads of long screwing length
When the thread is of medium length, code N is not marked.
For special needs, the value of the rotational length may be indicated.
M20 x 2-5 g6g - 40
4) rotation code
LH is marked on the left, but not on the right.
M10-7h-l-lh is a left-hand thread
M10-7h-l is a right hand thread
(2) pipe thread
Pipe threads are generally used in connection with pipes (water pipes, tubing, gas pipes, etc.). The marking of pipe threads shall be indicated in the manner of a guide line to the large diameter of the thread.
Marking of pipe threads:
It is composed of thread characteristic code, dimension code and rotation direction. The size code is not the size of the thread diameter, but the size of the pipe diameter (inch). The ones not marked with rotation are all right-handed.