G refers to the pipe thread without thread seal, R refers to the pipe thread with thread seal, and ZG refers to the conical pipe thread with a tooth profile angle of 55 degrees. The tooth profile angle is 55 degrees.

2. Different sealing performance

G thread internal and external threads are cylindrical pipe threads, which are not sealed after mating; R threads are tightened and then sealed. The top and bottom of the tooth are round, and the taper of the taper thread is1:16; ZG indicates that the tooth profile angle is 55 degrees, the taper is 1: 16, and there is no gap between the internal and external thread tooth profiles. ?

3. Different functions

G thread only plays a connecting role in the pipeline, and can be used for low-pressure pipeline under static load with the help of sealing ring. R thread has two kinds of cooperation, one is cylindrical internal thread/conical external thread, which is used for low-pressure static load, such as water pipe and gas pipe; The other is tapered internal thread/tapered external thread, which is used for high pressure and impact. ZG thread is mainly used for pipeline connection of high pressure and high temperature system. There is no gap between the internal and external thread profiles, and the tightness of the thread pair is ensured by the tooth profile deformation without packing.

Extended data:

A, thread detection system:

1. The thread parameter automatic detection system of hardware system is based on PC architecture, and mainly consists of lighting system, CCD camera and optical 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 imaging system, and then the digital image is transmitted to the computer through the image acquisition card. After the digital image is processed by computer according to the corresponding algorithm, the parameters such as thread profile angle, pitch and pitch diameter are calculated, and the deviation is calculated by comparing with the standard.

2. Software system The software system for automatic detection of thread parameters mainly includes system control module and image processing module.

System control module: initialization; Complete the initialization configuration of the system image interface card and standard parameters. Image operation; Collect and save 8-bit grayscale images, and capture the images into the memory.

Image processing module: The image processing module includes image preprocessing algorithm to reduce noise and highlight thread contour edge information, edge detection and extraction algorithm to detect and extract contour edge information, system calibration algorithm to measure the actual size of digital image, algorithm to calculate thread parameters, etc.

Second, the thread measurement method

1, measurement of thread included angle

Thread angle is also called tooth angle. The measurement of thread included angle can be realized by measuring the side angle, which is the included angle between the thread side and the vertical plane of the thread axis. The approximate profile of the thread teeth is sampled on the straight line segments on both sides of the thread, and the sampling points are fitted by linear least square method.

2, pitch measurement

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

3. Measurement of thread pitch diameter

The pitch diameter of thread is the distance along the axis perpendicular to the pitch diameter line, which is an imaginary line.

Baidu encyclopedia-inch thread

Baidu Encyclopedia-Tapered Thread