scholarly journals Technological support of thread quality with single methods

2020 ◽  
Vol 2020 (11) ◽  
pp. 3-7
Author(s):  
Alexander Prokofiev
Keyword(s):  
Internal Thread ◽  
Technological Support ◽  
External Thread ◽  
Thread Formation

The problems in technological support of external and internal thread are considered. There are presented different methods for external and internal thread formation. Particular attention is paid to the methods of internal thread deformation. There are shown investigation results on external thread electro-machining.

A Comparative Study on Mechanical Behavior of Pipe-Socket Threaded Joints With Taper-Taper Threads and Taper-Parallel Threads Combinations by Finite Element Analysis and Experiments

2018 ◽  
Author(s):  
Satoshi Nagata ◽  
Shinichi Fujita ◽  
Toshiyuki Sawa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Service Condition ◽  
Internal Thread ◽  
Element Analysis ◽  
Strain Pattern ◽  
External Thread ◽  
Thread Length ◽  
The Difference

There are two types of combination between external and internal threads used in threaded pipe connections for pressure piping specified in industrial standards like JIS as well as ISO. One is the combination that taper external thread of pipe is engaged with taper internal thread of a fitting. The other is that taper external thread of pipe is engaged with parallel internal thread of a fitting. Taper thread is always used for external thread outside the pipe wall. Both taper thread and parallel one are applicable to internal thread inside the fittings. This paper evaluates the mechanical behaviors of threaded pipe-socket joints (or pipe-coupling joints) and the difference due to the thread type combinations by means of axisymmetric finite element analysis for 3/4” and 3” joints. The analysis shows that the taper-taper threads combination establishes the full-length contact over the engaged threads but the taper-parallel has only a pair of threads in contact at the 1st engaged thread from the end of socket, and the difference results in the different behaviors of the joints. Stress and strain pattern also completely differ due to the difference in the engaged thread length. No significant effect of the size has been found in the present analysis for 3/4”and 3” joints. Experimental tightening tests and pressure leak tests have also been carried out for 3/4” and 3” joints with taper-taper threads combination. The measured experimental stress for 3/4” joints has shown an agreement with the simulated one fairly well. The pressure leak tests have demonstrated that the taper-taper threaded pipe-socket joints can hold internal pressure without leakage without using thread seal tape or jointing compound under low-pressure service condition. The 3/4” joints have started leaking at 1–4MPaG of internal pressure. The 3” joints haven’t shown leakage even at 6MPaG of internal pressure applied.

scholarly journals Elastic-plastic fracture analysis of external thread of drive shaft shell of a positive displacement motor

Mechanika ◽  
2020 ◽  
Vol 26 (5) ◽  
pp. 375-382
Author(s):  
Guanghui ZHAO ◽  
Guipeng LIAO
Keyword(s):  
Crack Depth ◽  
Bending Moment ◽  
Helix Angle ◽  
Drive Shaft ◽  
Internal Thread ◽  
Fe Model ◽  
Elastic Plastic ◽  
Positive Displacement ◽  
Threaded Connection ◽  
External Thread

    For a positive displacement motor (PDM), the threaded joint connecting drive shaft shell (DSS) and universal shaft shell that is close to the bit is inclined to fracture. In this paper, elastic-plastic fracture performance of the threaded connection is simulated under both make-up torque and bending moment. Firstly, an FE model, which includes a cracked external thread of the DSS and an engaging internal thread of the universal shaft shell, is established and validated. Secondly, influences of both plastic deformation and the helix angle on fracture properties of the cracked thread are evaluated quantitatively. Meanwhile interactions between two cracks are also discussed. Finally, under the two kinds of loading conditions, i.e. loaded by pre-load only and loaded by both pre-load and bending moment, explicit relationships between characteristic J-integrals and the crack depth are obtained for the DSS.

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