What is the formula for calculating the diameter of the internal thread, what is the formula for cal

The large diameter of the thread is subtracted by 2 times the tooth height plus one-tenth of the tooth height (because the top of the ordinary triangular thread is turned off by one-eighth of the tooth height, so the bilateral size is added by a quarter of the tooth height).

Definition of the diameter of the internal threadThe diameter of the thread is defined by the formula with respect to the diameter of the thread d, the value of the diameter on the inner thread closest to the axis. The formula for calculating the internal thread can be calculated according to the geometry of the following thread diagram, where the diameter value of d1 and p is the pitch.

h is the height of the tooth profile. Trail value = nominal diameter.

Pitch. <>

Maximum diameter = nominal diameter pitch + basic deviation.

Minimum diameter = nominal diameter pitch + basic deviation + middle diameter tolerance.

d1=d-2*5 8h= p is the pitch.

Simple enough to sprinkle!

Small diameter = large diameter —, p refers to the pitch, suitable for internal and external threads. There are no absolute formulas, otherwise mechanical manuals are useless.

Nominal diameter of thread: Except for the pipe thread, which is based on the inner diameter of the pipe (in inches), the nominal diameter of other threads is the nominal diameter (metric unit) for the large diameter of the outer thread. The above is a theoretical situation.

You can refer to GB T192-2003. In the actual machining, the large diameter will generally be smaller than the nominal diameter, the common processing calculation formula is: large diameter = nominal diameter - (, this difference is formed when the tool cuts the material, and this difference is the tolerance.

Taking the common metric external thread as an example, the profile angle of the ordinary metric thread is 60°

Thread diameter basic size (d1 or d1) = thread basic size (d or d) - pitch (p) coefficient (coefficient =

The working height, the distance between the overlapping parts of the two-phase fitting thread profile perpendicular to the thread axis, etc. The nominal diameter of the thread is the nominal diameter except for the pipe thread, which is the nominal diameter of the inner diameter of the pipe. Threads have been standardized and are available in metric (metric) and imperial systems.

The international standard uses the metric system, and China also uses the metric system.

Pipe threads are used for tight connections of pipe fittings. The rectangular thread has high efficiency, but it is often replaced by trapezoidal thread because it is not easy to grind and it is difficult to screw and center the inner and outer threads. The working edge of the serrated threaded tooth is close to the rectangular straight edge and is mostly used to withstand unidirectional axial forces.

In mechanical drawing, the view of threads and threaded fasteners is more cumbersome. In order to improve the drawing efficiency of the internal and external threads, the prescribed drawing method is usually used (see figure). Both the international standard ISO and the Chinese standard for mechanical drawing stipulate that:

The thread crown is represented by a thick solid line, the base of the thread is represented by a thin solid line, in the view of the projection surface perpendicular to the axis of the thread, the thin solid line representing the base of the tooth is drawn only 3 4 circles, and the end limit of the thread is represented by a thick solid line. The thread profile, diameter, pitch ......etc. are marked with the thread code in the dimension.

In the cross-sectional view of the assembly drawing, it is specified that the threaded fasteners are drawn as uncut, and a simplified drawing method is prescribed for common threaded fasteners, such as a hexagon head bolt, a hexagon nut and a set of fasteners of a washer can be drawn according to the drawing method in the drawing.

Female thread: pitch * tooth height example m33 * 2 radius) * 2

Trail = Diameter - Pitch.

The middle diameter of the M36x2 external thread is, and the small diameter is the large diameter of the internal thread is 36, but these are all ideal values, and the specific value depends on the tolerance grade of your thread and the position of the tolerance zone to determine the conversion of millimeters (mm) and inches (in).

1in=1mm=1: indicates a semicolon).

Large diameter = nominal diameter.

Middle diameter = large diameter.

Trail = Trail.

Profile height = metric triangle 60° p = 2 m24 x 2

Large diameter = metric diameter = 24°

Calculation of the large diameter of the thread: the upper limit calculation formula D-GES is the basic size of the large diameter of the thread - the benchmark deviation; The formula for calculating the lower limit is d-ges td, i.e., the basic size of the thread with a large diameter - reference deviation - tolerance.

Calculation of the small diameter: the basic size of the small diameter of the thread = the basic size of the internal thread - the pitch coefficient.

Precautions for calculating the large diameter of the thread: the large diameter of the thread is determined by the tooth wear degree of the thread rolling wheel of the thread rod blank and the thread rolling plate, and its value is inversely proportional to the middle diameter of the thread on the basis of the same blank and thread processing tools, that is, the middle diameter is small, the large diameter is large, and the large diameter is small.

Calculation formula of thread diameter: basic size of thread diameter (d1 or d1) = basic size of thread (d or d) - pitch (p) coefficient (coefficient =. The diameter of the thread is defined by the formula relative to the diameter of the thread d.

The thread diameter is also the reference value for determining the pre-drilled hole when we process the internal thread, because the thread gauge measures the middle diameter in the actual work, so the diameter size often cannot be used as the measurement object, and the specific diameter tolerance can refer to the relevant standards. Between the major diameter and the small path, suppose there is a cylindrical surface (or conical surface) in which the tooth width and groove width on the plain line are equal in its axial profile, then the diameter of the hypothetical cylinder is called the middle diameter.

The formula for calculating the large diameter and small diameter of the external thread is d-td, that is, the basic size of the large diameter of the thread - tolerance.

The formula for calculating the large diameter and small diameter of the external thread is d-td, that is, the basic size of the large diameter of the thread - tolerance. For example, the upper limit of M8 external thread 6H large diameter size, the upper limit is 8, and the lower limit is the calculation and tolerance of 6G large diameter of external thread.

Difference Between Male and Female Threads:

External threads are threads on the outer surface of a cylinder or cone, which are engraved directly on the outer surface, such as threads on bolts and plugs. The internal threads are distributed on the inner surface of Wu Qi's mother, that is, there are no specific requirements for the shape of the groove at the bottom of the tooth groove, and it is possible to flatten or round, such as the engraved threads on nuts and pipe joints. are all referred to as internal threads.

The letter h is capitalized and indicates an internal thread; The letter g is lowercase, indicating that it is an external thread. <>

The formula for calculating the middle diameter of the thread is as follows:

1. If you want to calculate the middle diameter of the thread, you need to calculate it according to the formula d2=d-p; where d refers to the large diameter of the thread, and p refers to the pitch, as for the specific coefficient value of the thread, generally only need to look at the special coefficient value formula table to know.

2. There are many types of threads on the market, and the thread size will be different if the thread type is different. If it is classified according to the thread size, the thread can also be divided into thread diameter, thread medium diameter, thread large diameter, etc., and these thread calculation formulas are also different.

Screw anti-slip tips

1. Cushion method

When the screw is slippery, you can put some non-woven fabric, double-sided tape and other items into the screwdriver bit, which can enhance the friction at the screwdriver bit, so that the screw can be easily unscrewed.

2. Glue method

When the screw is slippery, you can also inject some 502 glue into the screw hole, and when the glue is completely solidified, then use needle-nose pliers to try to loosen the screw. When twisting the screw, you must not use a screwdriver to twist it, otherwise it is easy to cause the screw to slip again.

3. Firing method

When the screw is slippery, you can also put the head of the screwdriver on the fire to burn, when the head position is burned red, then quickly put the head of the screwdriver on the screw hole, wait for about five seconds, and then try to unscrew the screw.

17835mm。

Inner diameter = outer diameter 10825x pitch. The calculation formula of the inner diameter is: inner diameter = outer diameter 10825x pitch, for example, the inner diameter of the thread of M20*2 = 200825*2 = 17835mm.

Thread profile:

Normal, trapezoidal, rectangular and zigzag threads. Thread thread types mainly include ordinary threads, namely triangular threads, trapezoidal threads, rectangular threads, and creepy zigzag threads.

Meaning of thread large diameter and small path:

The large diameter of the thread refers to the nominal diameter of the product. The thread diameter is the diameter of the base, which means that it refers to the diameter of the base of the external thread.

The thread has large diameter d, d, medium diameter d2, d2, small diameter d1, d1, and the nominal diameter is used when representing the thread, and the nominal diameter is the diameter representing the thread size. The nominal diameter of an ordinary thread is the large diameter.

For example, the large, medium and small diameters of the external thread are represented by d, d1 and d2. The internal threads are represented by d, d1, and d2. The large diameter refers to the imaginary cylinder diameter of the base brigade stool tangent to the crest of the external thread or the base of the internal thread. The underpath is the base of the external thread. <>