Relevant calculation formulas used in the production of fasteners:
1. Calculation and tolerance of the outer diameter of the thread pitch of the 60° profile (national standard GB 197/196)
has. Calculation of the basic pitch diameter size: The basic size of the thread pitch diameter = main thread diameter – pitch × coefficient value.
Expression of the formula: d/DP×0.6495
b. Commonly used 6h external thread pitch diameter tolerance (based on pitch).
The upper limit value is “0”
The lower limit value is P0.8-0.095 P1.00-0.112 P1.25-0.118
P1.5-0.132 P1.75-0.150 P2.0-0.16
P2.5-0.17
The upper limit calculation formula is the basic size, and the lower limit calculation formula d2-hes-Td2 is the basic diameter-gap-diameter tolerance.
Tolerance value of grade 6h pitch diameter of M8: upper limit value 7.188 lower limit value: 7.188-0.118 = 7.07.
C. The basic pitch diameter deviation of commonly used 6g grade external threads: (depending on pitch).
P 0.80-0.024 P 1.00-0.026 P1.25-0.028 P1.5-0.032
P1.75-0.034 P2-0.038 P2.5-0.042
The formula for calculating the upper limit value d2-ges is the basic size deviation
The formula for calculating the lower limit value d2-ges-Td2 is the basic tolerance for size deviation
2. Calculation and tolerance of the pitch diameter of the internal thread at 60° (GB 197/196)
has. Tolerance on class 6H thread pitch diameter (based on pitch).
Upper limit value:
P0.8+0.125 P1.00+0.150 P1.25+0.16 P1.5+0.180
P1.25+0.00 P2.0+0.212 P2.5+0.224
The lower limit value is “0” and the calculation formula for the upper limit value is 2+TD2, which is the base size + tolerance.
b. The formula for calculating the basic size of the pitch diameter of the internal thread is the same as that of the external thread, that is, D2 = DP × 0.6495, that is, the pitch diameter of the internal thread, the main diameter. of thread – pitch × coefficient value.
c. The basic deviation of the pitch diameter of the 6G quality thread is E1 (depending on the pitch).
P0.8+0.024 P1.00+0.026 P1.25+0.028 P1.5+0.032
P1.75+0.034 P1.00+0.026 P2.5+0.042
Lower limit value: 7.188+0.026=7.214
The upper limit value formula 2+GE1+TD2 is the basic size of the pitch diameter+gap+tolerance
The formula for the lower limit value 2+GE1 is the size of the pitch diameter + the gap
3. Calculation and tolerance of the major diameter of the external thread (GB 197/196)
has. The upper limit of the main diameter 6h of the external thread, that is, the value of the thread diameter, for example M8 is φ8.00. WeChat on metal processing has good content and is worth paying attention to.
b. The lower limit tolerance of the large diameter of grade 6h for external threads (depending on the pitch).
P0.8-0.15 P1.00-0.18 P1.25-0.212 P1.5-0.236 P1.75-0.265
P2.0-0.28 P2.5-0.335
The calculation formula for the lower limit of the large diameter is: d-Td, which is the basic dimensional tolerance of the large diameter of the thread.
c. Calculation and tolerance of the major diameter of the external thread of quality 6g.
Grade 6g external thread reference gap (based on pitch)
P0.8-0.024 P1.00-0.026 P1.25-0.028 P1.5-0.032 P1.25-0.024 P1.75 –0.034
P2.0-0.038 P2.5-0.042
The formula for calculating the upper limit d-ges is the basic size of the large diameter of the thread – the reference deviation
The formula for calculating the lower limit is d-ges-Td, which is the basic size of the large diameter of the thread – the reference deviation – the tolerance.
Lower limit valueφ8-0.028-0.212=φ7.76
4. Internal thread diameter calculation and tolerance
has. Calculation of basic dimensions of small diameter internal thread (D1).
Basic thread size = internal thread basic size – pitch × coefficient
B. Calculation of small diameter tolerance (based on pitch) and small diameter value of 6H internal thread.
P0.8 +0. 2 P1.0 +0. 236 P1.25 +0.265 P1.5 +0.3 P1.75 +0.335
P2.0 +0.375 P2.5 +0.48
The lower limit gap formula of 6H grade internal thread D1+HE1 is the basic size of small diameter internal thread + gap.
c. Calculation of the basic deviation of the small diameter of the internal thread of grade 6G (depending on the pitch) and the value of the small diameter.
P0.8 +0.024 P1.0 +0.026 P1.25 +0.028 P1.5 +0.032 P1.75 +0.034
P2.0 +0.038 P2.5 +0.042
The formula for the lower limit of the small diameter of the internal thread of grade 6G = D1 + GE1, which is the basic size of the internal thread + gap.
The upper limit value formula of 6G grade M8 internal thread diameter D1+GE1+TD1 is the basic internal thread size + gap + tolerance.
5. Calculation of division head unique indexing method
Formula for calculating the single indexing method: n=40/Z
n: is the number of revolutions that the dividing head must make
Z: equal fraction of the part
40: Fixed number of division heads
6. Calculation of a hexagon inscribed in a circle
official:
① Find the six opposite sides of circle D (surface S)
S = 0.866D corresponds to diameter × 0.866 (coefficient)
② Find the diameter of the circle (D) on the opposite side of the hexagon (surface S)
D=1.1547S is the opposite side × 1.1547 (coefficient)
7. Calculation of six opposite sides and diagonals in the cold heading process
Formula ① Find the opposite side (S) of the outer hexagon to find the opposite angle e
e=1.13s is the opposite side × 1.13
② Find the opposite angle (e) of the interior hexagon from the opposite side(s)
e=1.14s is the opposite side × 1.14 (coefficient)
③ To find the diameter of the head material for the opposite corner (D) on the opposite side of the outer hexagon(s), you need to calculate the diameter of the circle (D) on the opposite side of the surface of the hexagon(s). according to (formula 6.2) and increase its shift center value appropriately, that is, the shift center quantity of D≥1.1547 cannot be estimated.
8. Calculation of a square inscribed in a circle
Formula: ① Find the opposite side of the square (area S) from the circle (D)
S=0.7071D is the diameter×0.7071
② Find the circle (D) of the opposite sides of the four squares (surface S)
D=1.414S is the opposite side×1.414
9. Calculation of four opposite sides and opposite corners in the cold heading process
Formula ① Find the opposite side (S) of the outer square to find the opposite angle (e)
e = 1.4s, i.e. the opposite side parameter (s) × 1.4
② Find the opposite angle (e) of the four interior sides
e=1.45s is the coefficient of the opposite side(s)×1.45
10. Calculation of hexagonal volume
The formula ① s20.866 × H/m/k is the opposite side × opposite side × 0.866 × height or thickness.
11. Calculation of the volume of a truncated cone (cone)
The formula 0.262H (D2+d2+D×d) is 0.262 × height × (large head diameter × large head diameter + small head diameter × small head diameter + large head diameter × small head diameter).
12. Calculation of the volume of the missing spherical body (like the semicircular head)
The formula 3.1416h2(Rh/3) is 3.1416×height×height×(radius-height÷3).
13. Calculation of processing dimensions of taps for internal threads
1. Calculation of the large diameter of the tap D0.
The formula D0=D+(0.866025P/8)×(0.5~1.3) is the basic size of large diameter thread of tap+pitch 0.866025÷8×0.5 to 1.3 .
Note: Selection of 0.5 to 1.3 should be determined based on step size. The larger the step value, the more coefficient should be used. On the contrary, the smaller the step value, the more coefficient should be used. .
2. Calculation of the tapping pitch diameter (D2).
Formula: D2=(3×0.866025P)/8, i.e. thread pitch=3×0.866025×thread pitch÷8
3. Calculation of the tap diameter (D1).
Formula: D1=(5×0.866025P)/8, i.e. tap diameter=5×0.866025×thread pitch÷8
14. Calculation of material length for cold casting of various shapes
Known: The formula for the volume of a circle is diameter × diameter × 0.7854 × length or radius × radius × 3.1416 × length.
Either d2×0.7854×L or R2×3.1416×L
When calculating, the required material volume is X÷diameter÷diameter÷0.7854 or X÷radius÷radius÷3.1416, which is the length of the feed. WeChat on metal processing has good content and is worth paying attention to.
Column formula = X/(3.1416R2) or X/0.7854d2
X in the formula represents the value of the volume of material required.
L represents the actual value of the feed length.
R/d represents the actual radius or diameter of the material being fed.
15. Calculation of the suspended wheel of the rolling machine running gear
has. The fixed spindle number of the roller gear is 24.
b. The calculation of the running gear and the sprung wheel is carried out by decomposing the data, that is, by simultaneously enlarging or reducing their unchanged equal parts. Diagrams B1 and b2 are with compound transmission and diagrams b3 and b4 are with direct transmission.
c. Breakdown of pin 24 parameter.
c1 can be directly decomposed into 2×12=24; 3×8=24;
c2 is decomposed after expansion:
If enlarged 5 times 24×5=120, then 120 can be decomposed into 20×6;
If it is enlarged 8 times 24×8=192, then 192 will be decomposed into 2×91; 48×48;
8×24; 24×8; 32×6; 6×32 When expanding the multiple, the number of teeth of the processed parts should be increased at the same time until it is easy to disassemble;
d. Breakdown of the calculation case.
d.1 Calculation assuming that the machined part has 15 teeth.
Column formula: 24/15 is expanded 10 times at the same time to 240/150; decompose and erase the common multiple 3 at the same time to get (3×80)/(3×50)=80/50. time, you can use diagram b.4 to install an arbitrary intermediate in the middle. The wheel is equipped with an 80-tooth gear at ① and a 50-tooth gear at ②.
d.2 Calculation assuming that the machined part has 77 teeth.
Column formula: 24/77 extended 90 times at the same time to 2160/6930; broken down (40×54)/(70/99) At this point, the assembly gear from schematic diagram b.1 can be used. Account for the convenience of gear assembly, 1 and 3 The numbers can be interchanged at will, 2 and 4 can also be interchanged at will, but the positions of 1 and 2 or 4 and 3 and 2 or 4 cannot not be interchanged. on the contrary, 4 and 1 or 3 and 2 and 1 or 3 cannot be interchanged.
d.3 Calculation assuming that the machined part has 32 teeth.
Column formula: 24/32 is enlarged 5 times to 120/160; broken down into (4×30)/(4×40) and the common multiple of 4 is erased to get 30/40. 3 schematic diagrams can be used to install any intermediate in the middle. The wheel is equipped with 30 gears in ① and 40 gears in 2nd.
d.4 Calculation assuming that the machined part has 13 teeth.
Column formula: 24/13 After being enlarged 100 times at the same time, 2400/1300; decomposition force (30×80)/(20×65) can be assembled using schematic diagram b.2 at this time. Note: why is 2400 broken down. into 3 0×80 can also be broken down into 40×60. At this time, it depends on the fit of the gears after assembly, as long as they fit well, the number of teeth of this gear can also be decomposed into 20×120, which can be assembled according to the principle diagram in 6.4.
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