Basic knowledge of thread gauges
A thread gauge is a gauge used to test whether a thread complies with regulations. Thread plug gauges are used to test internal threads, and thread ring gauges are used to test external threads.
Thread is an important and commonly used structural element. Threads are mainly used in structural connection, sealing connection, transmission, reading and load-bearing and other occasions. From general use conditions to severe conditions (high temperature, high pressure, severe corrosion), from rough level to very quiet, in short, it has a wide range of applications.
1. Ordinary thread (also known as American thread or metric thread) M
2. The American standard unified thread is also UNC, UNF, UNEF, UN, UNS series
3. Non-thread-sealed pipe threads (old nominal cylindrical pipe threads)
4. Trapezoidal thread
5. Other threads
NPSM-American Standard Mechanical Connection Straight Pipe Thread: These internal and external threads are used for free mechanical connection without internal pressure. The product has a straight pipe go-stop ring plug gauge inspection.
NPSL – Straight Pipe Threads for American Standard Lock Nuts: These internal and external threads are used for the mechanical fit of anti-feed threads.
NH – American Standard Fire Hydrant Thread: These internal and external threads are used for fire hydrants, garden water hoses, chemical and elevators, etc.
NPSH-National Standard Hose Coupling Threads: These internal and external threads are used for steam, air, water and other standard pipe connections.
NPSC-American standard pipe connection with straight pipe thread: the pipe joint has the same thread profile as the inner straight pipe thread. When the outer tapered thread NPT is used for the assembly of the sealing packing, it is tightened by a wrench, and usually can form a sealed connection. It is mostly used for low-pressure pipes. road system.
NPSF-National Standard Oil Dry Seal Thread: These internal threads are used for unsealed assembly with NPTF external threads on soft materials or ductile iron castings.
NPSI – American Standard Dry Seal Intermediate Threads: These internal threads are used for assembly of hard or brittle materials with short PTF-SAE external threads, but can also be used for full length assemblies with NPTF external threads.
Taper gauge for gas cylinders
The special taper thread for gas cylinders is used for the connection between cylinders and valves of various steel cylinders (such as oxygen cylinders, gas cylinders, acetylene cylinders, etc.). The reliability of the locking and sealing of threaded connections is the main factor to ensure safety in the process of production and use.
Available for PZ19.2PZ19.8PZ27.8PZ39 taper thread ring gauge, plug gauge, tap
Metric trapezoidal thread Tr
Trapezoidal threads are mainly used in transmission (feed and lift) and position adjustment devices, and are widely used in the machinery industry. The tolerance of metric trapezoidal threads for general purposes adopts the tolerance system of metric common threads, and there is no separate tolerance value for individual parameters such as thread lead (pitch) and sub-measurement angle. Therefore, this trapezoidal thread is not suitable for precision transmission threads that have high requirements for transmission accuracy. The precision transmission trapezoidal thread needs to supplement the tolerance of individual thread parameters on the basis of the general trapezoidal thread standard.
Trapezoidal threads can also be used for fastening connections. ACME thread and metric serrated thread gauges available
American testing system for fastening threads (UN, UNR, UNJ, M and MJ)
Due to many misunderstandings, certain risks and economic requirements in the field of thread detection, it has brought a lot of trouble to the acceptance of thread products and buried many hidden dangers to the quality of mechanical products. In order to fundamentally reverse this passive situation, the United States has conducted a lot of technical research on thread detection, and proposed the fastening thread detection system standard (ASME standard) and the uncertainty data of 60º thread gauge measurement (ASME technical report). The United States leads the world in thread processing and testing technology. In the future, other countries in the world will learn from the experience of the United States and formulate their own national thread testing system standards to improve the quality of their thread products. If the majority of technical personnel in our country can learn and master this set of thread detection system technology as soon as possible, the quality of thread products in our country will be improved rapidly, and we will get rid of the situation of rough thread production.
From the American thread inspection system, you can also learn some advanced thread processing technology in the United States. For example, the use of differential indicator gauge detection technology can improve the adjustment accuracy of machine tools and cutting tools, and process threads close to the theoretically correct size. At the same time, the tool life will be increased.
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Post time: Jun-21-2023
