I m not talented! What is a taper thread, please? What is an inch thread?

The tapered pipe thread is the taper of the large warp, medium warp and small diameter of the thread, which is generally used for pipe joints and has a certain sealing effect. Codename:

The oldest code: k, kg. The old code names Z, ZG. New code names R, RC.

Taper thread, generally referred to as taper pipe thread. Their nominal size is the inner diameter of the tube. It is in the imperial system.

Imperial thread: It is an ordinary thread obtained in imperial units, and its nominal size is the outer diameter of the thread.

G is a 55 degree non-threaded seal pipe thread, which belongs to the Wyeth thread family Marked as G stands for cylindrical thread The national standard can be found in GB T7307-2001

G is the general name of pipe thread (guan), and the division of 55 and 60 degrees belongs to the functional, commonly known as the pipe circle. That is, the thread is machined from a cylindrical surface.

ZG is commonly known as the pipe cone, that is, the thread is processed by a conical surface, and the general water pipe joints are like this, and the old national standard is marked as RC

Metric threads are expressed by pitch, and American and British threads are expressed by the number of threads per inch, which is their biggest difference, the metric thread is 60 degrees equilateral, the imperial thread is isosceles 55 degrees, and the American thread is 60 degrees.

Metric threads are in metric units, and American and British threads are in imperial units.

Pipe threads are mainly used for the connection of pipelines, and the internal and external threads are tightly matched, and there are two kinds of straight pipes and conical pipes. The nominal diameter refers to the diameter of the connected pipe, and obviously the large diameter of the thread is larger than the nominal diameter.

Inch threads. The basic size table is shown below

The imperial thread is marked with the inch system for the thread size, which is divided into two types: cylindrical and conical according to the shape; According to the angle of the tooth type, it is divided into two types. The 8 mark in a thread refers to the diameter of the thread size in inches. One inch is equal to 8 points, 1 4 inches is 2 points, and so on.

The imperial thread is a thread with inches as the unit of length, and the metric thread is a completely different two systems, mainly used in the United Kingdom and the United States, and the others are mainly used in the metric thread.

The following differences exist:

1. The sealing is different.

zg means that the profile angle is 55 degrees, the taper is 1:16, and there is no gap between the internal and external threads.

The inner and outer threads of the G thread are cylindrical pipe threads, and there is no sealing after fitting;

rTightened thread tightening. The top and bottom of the tooth are all rounded, and the taper of the taper thread is 1:16.

2. The role is different.

ZG thread is mostly used in the pipeline connection of high-pressure and high-temperature systems, there is no gap between the internal and external threads, and the connection tightness of the thread pair is ensured without packing and relying on the deformation of the thread punch;

The G thread only plays a connecting role in the pipeline, and can be used for low-pressure pipelines under static load with the help of sealing rings;

There are two kinds of fits for the R thread, one is a cylindrical internal thread and a conical external thread, and the other is a conical internal thread and a conical external thread, which is used for high pressure and impact occasions.

3. The models are different.

ZG refers to the tapered pipe thread with a profile angle of 55 degrees (the profile angle is 55 degrees), G refers to the pipe thread that is not sealed with threads, and R refers to the pipe thread that is sealed with threads.

Inspection system for inch threads:

1. The automatic detection system of thread parameters of the hardware system is based on PC architecture, which is mainly composed of lighting system, CCD camera and optical path imaging system, image acquisition card, image processing system, mechanical detection system and electronic control system.

During the measurement, after being illuminated by the lighting system, the thread image of the fastener is collected by the CCD camera and the optical path imaging system, and then the digital image is transmitted to the computer through the image acquisition card, and the computer processes the digital image according to the corresponding algorithm, calculates the parameters such as the tooth profile, pitch and middle diameter of the thread, and compares it with the standard to calculate the deviation.

2. The software system of automatic detection of thread parameters of the software system mainly includes the system control module, image processing module, etc.

System Control Module: Initialization; Complete the initial configuration of the system image interface card and standard parameters. image manipulation; Collect and save 8-bit gray images, and capture images to memory.

Image processing module: The image processing module includes an image preprocessing algorithm that reduces noise and highlights the edge information of the thread contour, an edge detection and extraction algorithm that detects and extracts the edge information of the contour, a system calibration algorithm that measures the actual size of the digital image, and an algorithm for calculating the thread parameters.

Measurement method for inch threads:

1. Measurement of thread angle.

The thread angle is also called the tooth angle. The measurement of the thread angle can be achieved by measuring the side angle, which is the angle between the side of the thread and the perpendicular face of the thread axis. The approximate contour of the thread teeth is sampled in the straight line segments on both sides of the thread, and the linear least squares fitting is performed on the sampling points.

2. Measurement of pitch.

Pitch is the distance between a point on a thread and the corresponding point on an adjacent thread. The measurement must be parallel to the thread axis.

3. Measurement of the middle diameter of the thread.

The thread diameter is the distance along the center diameter line perpendicular to the axis, and the center diameter line is an imaginary line.

Measurement results of inch threads:

Using machine vision technology, an automatic detection system for thread parameter measurement is designed, and parameters such as thread angle, pitch and middle diameter of standard thread specimens are measured. The measurement results show that the thread parameters are within the specified error range. Due to the high efficiency and reliability of visual inspection, it was considered that it could be used in production practice after further investigation.

On the profile that passes through the axis of the screw thread, the profile shape of the thread is called the tooth profile. The angle between two adjacent flanks is called the tooth angle. The tooth profile of the commonly used common thread is triangular, and the tooth profile angle is 60°.

The imperial thread is the thread in inches as the length unit, and now the main ones in use are the American standard and the British standard, and most of the others are using the metric system of Henghe.

Comparison table of inch threads.

The imperial thread is marked with the inch system for the thread size, which is divided into two types: cylindrical and conical according to the shape; According to the angle of the tooth type, it is divided into two types. The 8 mark in the thread refers to the diameter of the spiral screw splinter dimension in inches. One inch is equal to 8 points, 1 4 inches is 2 points, and so on.