How to measure the nominal diameter of the thread and how to measure the diameter of the rebar?

The surface shape and size allowable deviation of ribbed steel bar design principle of ribbed steel bar cross rib should comply with the following provisions: the angle between the cross rib and the axis of the steel bar should not be less than 45 degrees, when the angle is not more than 70 degrees, the direction of the cross rib on both sides of the steel bar relative to the two sides should be opposite; The nominal spacing of the transverse rib l shall not be greater than the multiple of the nominal diameter of the reinforcement; The angle between the cross rib side and the steel bar surface shall not be less than 45 degrees; The sum of the gaps between the ends of the transverse ribs on the two adjacent sides of the reinforcement (including the width of the longitudinal ribs) should not be greater than 20% of the nominal circumference of the reinforcement; When the nominal diameter of the reinforcement is not more than 12mm, the relative rib area should not be less than; When the nominal diameter is 14mm and 16mm, the relative rib area should not be less than; When the nominal diameter is greater than 16mm, the relative rib area should not be less. Refer to Appendix C for the calculation of the relative rib area.

Ribbed steel bars usually have longitudinal ribs or not; Since the diameter of the rebar is obtained by analogy with the weight of the same diameter of the round bar. Therefore, it is better to use the weight index to investigate the radial specifications of rebar.

The nominal diameter of the thread is the maximum diameter of the thread The internal thread is the same as the external thread, for example, the nominal diameter of M24 is 24mm, the nominal diameter of the external thread is the crest line, the nominal diameter of the thick solid thread is the base line, and the thin solid line is 17

The nominal diameter of the thread is a theoretical diameter.

Count the ribs, with the ribs on one side.

The following simple measurement methods are also commonly used at construction sites:

1. In the past, the old standard used the weight method to calculate the area

Area = Length * Weight ; That is, the weight of the steel bar per unit length weighed is divided by the bulk density of the steel to obtain the cross-sectional area, and then the "diameter" is converted.

Area(s) = Pi (radius (r) squared.

Diameter = Radius * 2

2. Vernier calipers are also commonly used in the field to directly measure the diameter: one side of the rib, one side of the smooth surface, measure the average diameter of the three sections, and reduce it by 5%.

3. Use calipers to directly measure the inner diameter (excluding ribs), and compare the inner diameter size of the corresponding steel bar in the hardware manual. According to the regulations, the inner diameter of the steel bar d1 should be measured, and the size of the rib cannot be measured.

Such as the nominal diameter, its inner diameter d1 respectively, allowable deviation. For example, the nominal diameter is d1, respectively, and the allowable deviation is .

The diameter of the rebar can be measured using vernier calipers and weight

When measuring with vernier calipers, one side is stuck on the rib and one side is stuck on the smooth surface, and the diameter can be calculated by measuring three sections, and it also needs to be reduced by 5%, and the result is more accurate

The gravimetric method can be used to calculate its diameter, first calculate the cross-sectional area, and then convert its diameter.

Rebar standard diameter:The nominal diameter of the rebar ranges from 6 to 50mm, and the standard recommended rebar nominal diameter is mm. When the nominal diameter of the reinforcement is not more than 12mm, the relative rib area should not be less than;

When the nominal diameter is 14mm and 16mm, the relative rib area should not be less than; When the nominal diameter is greater than 16mm, the relative rib area should not be less.

The diameter of the rebar refers to the diameter of the base circle of its cylinder, and the diameter of the unstriped section can be measured with a caliper. The size of the longitudinal and transverse ribs of the exterior is specified separately.

The nominal diameter of the thread refers to the large diameter of the thread.

Nominal diameter English name: nominaldiameter, definition: the diameter that represents the thread size, usually refers to the basic size of the thread diameter.

The nominal diameter is also known as the mean outside diameter. Refers to the standardized standard diameter, the nominal diameter is expressed in DN, the unit is mm, for example, the nominal diameter of a container with an inner diameter of 1200mm is marked as DN1200.

In the actual machining, the large diameter of the thread will generally be smaller than the nominal diameter, the common processing calculation formula is: the large diameter of the thread = the nominal diameter of the thread - (, this difference is formed when the tool cuts the material, and this difference is the tolerance.

Calculation of the large diameter of the thread:

The upper limit calculation formula d-ges is the basic size of the thread with a large diameter - 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 trails:

The basic size of the thread diameter = the basic size of the internal thread - the pitch factor.

Precautions for calculating the large diameter of the thread:

1. The large diameter of the thread is determined by the diameter of the thread smooth rod blank and the tooth wear degree of the thread rolling wheel of 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 small middle diameter is large and the diameter is large, and the large diameter is small on the contrary.

2. For the parts that need to be processed by heat treatment and surface treatment, considering the relationship between the processing process, the large diameter of the thread should be controlled at the lower limit of 6H level during the actual production, such as the large diameter of the external thread of M8 in the rolling (rolling) wire should be guaranteed to be above and below.

Notes on the calculation of the diameter of the thread:

1. The tooth height of the internal thread is directly related to the size of the bearing moment of the internal thread, so it should be within the upper limit of 6h level as far as possible in the production of blanks.

2. In the process of internal thread processing, the smaller the diameter of the internal thread, the more effective the use of the tool-tap. From the point of view of use, the smaller the trail, the better, but when considering comprehensively, the trail is generally between the middle limit and the upper limit, and if it is cast iron or aluminum, the lower and middle limit of the trail should be used.

3. The diameter of the 6G grade of the internal thread can be implemented according to the 6H level in the production of the blank, and its accuracy grade mainly considers the plating of the middle diameter of the thread, so only the middle diameter size of the tap is considered in the thread processing and the diameter of the light aperture is not considered.

How to measure the thread length pro! Hello, happy to answer your <>. Pro-1

Measuring with Threaded Ring Gauge and Clamp PlateFor general standard threads, threaded ring gauge or plug gauge are used to measure. When measuring the external thread, if the thread"Through-end"The ring gauge is just screwed in, and the "stop" ring gauge is not screwed, which means that the processed thread meets the requirements, otherwise it is unqualified. When measuring internal threads, a thread plug gauge is used and the measurement is done in the same way.

Thread Measurement Method 2Measuring thread micrometer with thread micrometer is used to measure the middle diameter of the thread, generally used to measure the triangular thread, its structure and use method is the same as the outer diameter micrometer, there are two contacts with the same tooth angle of the thread, one is conical, and the other is grooved. A range of measuring contacts are available for different tooth angles and pitches.

When measuring, the two contacts of the thread micrometer are stuck exactly on the tooth face of the thread, and the reading obtained is the actual size of the middle diameter of the thread. 3.Measuring tooth thickness with tooth thickness vernier calipers is composed of high calipers and tooth thickness calipers perpendicular to each other, which are used to measure the diameter tooth thickness of trapezoidal threads and the tooth thickness of worm node diameter.

When measuring, adjust the tooth height caliper reading to the tooth top height (trapezoidal thread is equal to pitch t, worm is equal to modulus), and then make the tooth thickness caliper and worm axis roughly intersect into a thread rise angle b, and make a small amount of oscillation. The smallest dimension measured in this case is the normal tooth thickness of the worm axis pitch. Thread measurement method 4 The method of measuring the middle diameter of the thread with a measuring needle is called the three-needle measuring method, when measuring, three measuring needles with the same diameter d are placed in the thread groove, and then the size of the size m is measured with an appropriate measuring tool (such as a micrometer, etc.) to verify whether the middle diameter of the thread processed is correct.

5 Double-needle measurement method The use of double-needle measurement method is more extensive than that of three-needle measurement method, such as threads with few thread turns, and threads with large pitch (the pitch is larger than it is inconvenient to use the three-needle measurement method, and the measurement with the double-needle measurement method is simple and feasible, for the ordinary thread tooth shape angle a=60 I hope mine can help you <>

Do you have any other questions?

The nominal diameter of the thread, except for the pipe thread with the inner diameter of the pipe as the nominal diameter, the nominal diameter of other threads is the nominal diameter of the outer thread. Main geometric parameters of cylindrical threads:

1. Outer diameter (large diameter), the diameter of the imaginary cylinder that coincides with the top of the external thread or the bottom of the internal thread. The nominal diameter of the thread is the large diameter.

2. Inner diameter (small diameter), the diameter of the imaginary cylinder that coincides with the external thread base or the internal thread tooth top.

3. The middle diameter, the diameter of the imaginary cylinder with the same width of the bub and groove on the tooth profile.

4. Pitch, the axial distance between two points of adjacent teeth on the middle diameter line.

5. Lead, the axial distance between two points on the middle diameter line of adjacent teeth on the same helix line.

The nominal diameter of the ordinary thread refers to which diameter, selling bolts, screws and nuts Yu Wenlong believes that the nominal diameter of the ordinary thread refers to the outer diameter of the thread, that is, the largest part of the thread. Yu Wenlong, a fastener consultant, believes that it is best to check the relevant information by yourself, and it is always fake on the Internet.

What is the nominal diameter of the thread referring to the rest of the sock?

The nominal diameter of the thread is the maximum diameter of the thread The internal thread is the same as the external thread, for example, the nominal diameter of M24 is 24mm

The nominal diameter of the external thread is the crest line, thick solid line.

The nominal diameter of the internal thread is the bottom line of the tooth, a thin solid line.

How to measure the nominal diameter of the thread.

Measure threads (holes) with calipers and pitch gauges.

Measuring the diameter of a threaded hole with a caliper can estimate the nominal diameter of the threaded hole; The pitch gauge can be used to measure the pitch of the thread. The measured data can be compared with the thread parameter table to know the value of the measured screw hole. In the future, if you are proficient, you don't need to check the table for comparison.

Another way to measure the screw hole is to measure the size of the screw that can be screwed into the screw hole, and the large diameter of the screw is the nominal diameter of the thread (the measured value is about smaller).

Is the outer diameter of the lower thread nominal?

Yes. Please see the attached drawing.

d— The basic large diameter of the internal thread (nominal diameter);

d— The basic large diameter of the external thread (nominal diameter);

d2— the basic middle diameter of the internal thread;

d,— the basic middle diameter of the external thread;

d— The basic diameter of the internal thread;

d,— the basic trail of the external thread;

h— the height of the original triangle;

Cadaver — pitch.