Calculation formula of screw thread

Diameter calculation and tolerance (national standard 197/196 GB) A. of the 60 degree of the diameter of the external thread diameter calculation: the basic size of the diameter of the thread: the diameter of the diameter of the thread.
Formula: d/D-P * 0.6495 cases of: M8 screw with external thread in calculating the diameter of 8-1.25 * 0.6495=8-0.8119 PRG 7.188b. commonly used 6h thread diameter tolerance which is based on the pitch.
The upper limit value is "0""
The lower limit of the P1.00-0.112 P1.25-0.118P1.5-0.132 P1.75-0.150 P2.0-0.16P2.5-0.17 P0.8-0.095 upper limit formula that is the basic size, the lower limit of the formula d2-hes-Td2 that is the basic size of the diameter deviation - tolerance.
6h level of M8 in the tolerance value: upper limit of 7.188 lower value: 7.188-0.118=7.07.
6G commonly used in the C. level of the basic deviation of the diameter of the basic deviation: (with a pitch as the benchmark).
Values of P 0.80-0.024 1.00-0.026 P1.25-0.028 P1.5-0.032P1.75-0.034 P2-0.038 P2.5-0.042 limit calculation formula d2-ges namely basic size deviation limit value calculation formula d2-ges-Td2 namely basic size deviation tolerance with M8 6G grade diameter tolerance value: upper limit lower limit of 7.188-0.028=7.16 values: 7.188-0.028-0.118=7.042.
Note: more thread tolerance is to coarse thread, the fine tooth thread tolerance some changes, but are only tolerance becomes larger, so according to this control will not exceed the specification limits, so in the above not marked out one by one.
Threaded rod billet size according to the design requirements of precision and thread processing equipment of extrusion pressure and their than designing all kinds of screw thread size increase between 0.04, 0.08, threaded rod billet diameter and cases of our company the M8 threaded 6G thread rod blank size really 7.08 - 7.13 is this range in actual production.
Taking into account the needs of the production process of the external thread in the actual production of heat treatment and surface treatment of the lower limit should be kept at the 6h level as the standard.
60, two degree internal diameter calculation and tolerance (GB 197 /196) 6H A. grade thread diameter tolerance (with a pitch as the basis).
Upper limit value:
The lower limit value of P1.00+0.150 P1.25+0.16 P1.5+0.180P1.25+0.00 P2.0+0.212 P2.5+0.224 P0.8+0.125 is "0", and the upper limit value is calculated with the formula 2+TD2, which is the basic dimension and tolerance.
In the case of M8-6H, the diameter of the inner thread is: 7.188+0.160=7.348 upper limit value: 7.188 is the lower limit value.
The calculation formula of the basic size of the middle diameter of the B. thread is the same as that of the external thread, i.e., D2=D-P * 0.6495, which is the large diameter and pitch of the internal thread.
6G C. thread middle diameter deviation E1 (based on the pitch as the benchmark).
M8 6G grade internal threads in the upper size limit P0.8+0.024 P1.00+0.026 P1.25+0.028 P1.5+0.032P1.75+0.034 P1.00+0.026 P2.5+0.042 cases value: 7.188+0.026+0.16=7.374 limit: the maximum 7.188+0.026=7.214 value formula 2+GE1+TD2 in diameter basic size deviation + + tolerance limit value formula 2+GE1 in diameter size deviation + 3 and 6h of calculation and tolerance of large diameter of the outer screw (GB) 197/196 a. external thread large size upper limit value is thread diameter values with M8 is Phi 800 limit values of tolerance to "0". Metal processing WeChat, the content is good, it is worth attention.
Tolerance of the lower limit value of the 6h level of the external thread of the B. (based on the pitch).
P1.00-0.18 P1.25-0.212 P1.5-0.236 P1.75-0.265P2.0-0.28 P0.8-0.15 P2.5-0.335 the lower limit of the calculation formula: d-Td that is the basic size of the thread diameter - tolerance.
For example: M8 6h large diameter thread: the upper limit is Phi 8, Phi 8-0.212= phi 7.788c. 6G large diameter thread calculation and tolerances.
Computing 6G external thread standard deviation (which is based on the pitch) P0.8-0.024 P1.00-0.026 P1.25-0.028 P1.5-0.032 P1.25-0.024 P1.75 - 0.034P2.0-0.038 P2.5-0.042 limit formula d-ges that thread large diameter basic dimensions - Reference deviation from the lower bound calculation formula d-ges - TD that thread large diameter basic dimensions - reference bias - tolerance cases: M8 threaded 6G class size upper limit Phi Phi 8-0.028= 7.972.
Lower limit value of 776 note Phi Phi 8-0.028-0.212=: thread diameter is by the threaded rod billet diameter and thread plate / roll type wire wheel tooth wear to determine the extent of, and the numerical on the same blank and thread machining tool based and thread size into inverse appeared in size small, big size, whereas in large diameter is small size. Metal processing WeChat, the content is good, it is worth attention.
II to be for heat treatment and surface treatment, such as processing parts, considering the machining process of the relationship between the actual production should be large diameter thread control in 6h level threshold value above plus 0.04mm, such as the external thread of the M8 in rubbing rolling wire diameter should be guaranteed in pHi 7.83% and 7.95 following the appropriate.
Four, the calculation of internal thread diameter and the tolerance of A. thread diameter of the basic size calculation (D1).
= basic dimensions of the pitch diameter of the thread, thread size - pitch * coefficient cases: internal screw M8 path basic dimensions 8-1.25 * 1.0825=6.646875 PRG 6.647b. in thread 6h level path tolerances (to pitch as a benchmark) and path calculation.
+0. P0.8 2 +0. P1.0 236 P1.25 +0.265 P1.5 P1.75 +0.3 +0.335P2.0 +0.375 P2.5 +0.48 6H internal thread level deviation formula D1+HE1 that is the basic size of the internal thread diameter + deviation.
Note: the lower partial value of the 6H level is "0""
The upper bound of the 6H level of the internal screw thread is calculated by the formula =D1+HE1+TD1, which is the basic size of the internal thread path and the deviation + tolerance.
Example: M8 grade in the upper limit of 6H grade 6.647+0=6.6476H grade M8 inside the thread diameter of the lower limit value 6.647+0+0.265=6.912c. internal thread 6G level of the basic deviation (with the pitch as the reference) and the calculation of the path value.
+0.024 P1.0 +0.026 P1.25 +0.028 P1.5 P0.8 +0.032 P1.75 +0.034P2.0 +0.038 P2.5 +0.042 internal thread 6G level of the lower limit value formula