Analytical derivation of thread profile in internal thread milling process

Thread milling is a new machining process as compared to thread tapping. As a thread making process in use for a long time, thread tapping did not have any alternative processes except the thread turning for limited cases until computer numerical control (CNC) technology had enabled the three axes synchronized motion. Therefore, investigations about the thread milling process are less as compared to other machining processes. In this work, the thread profile in the internal thread milling process was derived analytically. Experimental work was also performed to verify the performance of the analytical model. It was revealed that the thread profile produced by the cutting edge of the tool is not a straight line but a curve, and the average slope through the thread profile is less than the slope of the cutting edge of the tool. Besides, the effective thread profile enlarges along the vertical axis and constricts laterally as the ratio of thread mill diameter to thread diameter increases.

Optimization of Tool Geometric Parameters For a Small Fluteless Forming Tap (FFT)

A small blind internal thread (SBIT) is used to firmly fasten some functional components to the cover of 3C electronic products. The small internal thread is made in a blind hole using a fluteless forming tap (FFT) that does not produce chips. However, the four geometric parameters (tool width (W), tooth root diameter (D2), front-end diameter (Df) and tooth angle (θ)) for the FFT affect the thread filling rate (f) and the minimum torque (T) for the tapping process. This study reports a Box-Behnken design (BBD) using DEFORM-3D (finite element model) and MINITAB (regression analysis) software to tap 7075-T6 aluminum alloy using a small FFT to achieve a repeatable thread filling rate and minimum torque. The experimental results show that the BBD accurately predicts and simulate the thread filling rate for tapping 7075-T6 aluminum alloy. The modelling software and the experimental design for this study can be used to optimize the design of tools that are used in industrial production.

The Influence of the Bottom Hole of Cold Extruding Internal Thread on Thread Quality

The diameter of the threaded bottom hole determines whether the extrusion can proceed smoothly and the fullness of the tooth shape after extrusion. The tooth height rate is an important indicator of the strength of the threaded connection. In order to establish the relationship between the diameter of the bottom hole and the tooth height of the extruded internal thread, this paper takes the aluminum alloy M8×1.25 mm internal thread as an example, and uses a method of combining numerical simulation and process test. Obtained the changing law of internal thread profile and tooth height rate of extruded workpieces with different bottom hole diameters. Using MATLAB to fit the numerical simulation results, the relationship between the tooth height of the internal thread and the diameter of the prefabricated bottom hole of the workpiece was obtained. The reliability of the numerical simulation results and the feasibility of the fitting formula are verified through experiments. The results show that the diameter of the prefabricated bottom hole of the workpiece is controlled within 7.33~7.39 mm when the M8×1.25 mm internal thread is processed by the cold extrusion process. The high rate of the internal thread after extrusion meets the requirements of thread connection strength, and the internal thread has high forming quality and good surface quality.

Mecanismos de seguridad en las estrategias de gestión documental en el proceso de envío y recepción de documentos oficiales

Hoy en día la información que se maneja en las distintas dependencias de la Administración Pública es susceptible de optimización que reduzca los riesgos de amenaza. El presente artículo describe los procesos de gestión documental usada en las dependencias del Gobierno del Estado de Tabasco y la necesidad de hacerlos más eficientes. Se describe el modelo metodológico que se utiliza para la obtención de los resultados, los cuales, en su sección inmediata, se enlistan los mecanismos de seguridad recomendados ad hoc para la dependencia de gobierno estudiada, los cuales incluyen desde el almacenamiento de la información, hasta la transmisión de la misma. Organizational communication trough documents between public administration offices, may be compromised in case of external or internal thread. This article presents advances of research on the processes of governmental document management applied at offices in Tabasco’s State Government. It also describes the methodology used, and the security strategies recommended ad hoc, including information storage and transmission.

Hob cutter shaping for internal straight thread

Резьба используется во многих механизмах и достаточно часто для разъемных соединений деталей судовых машин. Для повышения долговечности внутренней цилиндрической резьбы и производительности процесса ее нарезания предлагается новая методика «профилирования червячной фрезы для нарезания внутренней цилиндрической резьбы методом огибания. В данной статье приведено аналитическое определение сопряженных профилей цилиндрической внутренней резьбы и инструмента. Рассматривается метод профильных нормалей для профилирования червячной фрезы при нарезании внутренней резьбы способом огибания, основанный на применении теории матриц. Червячная фреза в осевом сечении имеет конкретный криволинейный профиль, для его получения необходимо знать расчетные зависимости торцового профиля резьбы, и уравнения ее винтовой поверхности и осевого профиля. Для возможности образования витков резьбы необходимы определенные зависимости скорости резанья фрезы и резьбы, а для формирования внутренней резьбы - ее поверхность должна набегать на зубья червячной фрезы. Эти задачи решены с помощью разработанной системы уравнений для изготовления фрез при нарезании внутренней цилиндрической резьбы способом огибания методом профильных нормалей. Расчетный механизм профилирования инструмента - фрезы для нарезания цилиндрических внутренних резьб – может применяться для формообразования конических внутренних резьб. Threads are used in many mechanisms and frequently in detached connections of marine engines elements. The new technique of hob cutter shaping for internal straight thread is proposed in order to increase durability of the internal cylindrical thread and to improve its cutting performance process. The article gives analytical definition of conjugate profiles of internal straight thread and of a tool. It also deals with the method of profile normals for shaping hob cutter whilst cutting the internal thread by enveloping. The method applies the matrix theory. There is some curved profile in the hob cutter axial section. In order to obtain that profile, it is necessary to know the calculated dependence of a thread transverse profile and its helical surface and axial profile equation. Special dependences of thread speed range and cutting are required to produce turns of the thread. To form internal thread – its surface is to slide on cutter teeth. All the mentioned tasks can be solved by the system of equations for cutters manufacture with cutting internal straight thread applying enveloping with the method of profiles normals. The calculation mechanism for shaping the tool – the hob cutter for internal straight threads – can be used for making internal taper threads.

Development of pre-molded internal thread on composite tubes

Premolded internal threads on composite tubes were developed. The composite tubes with threads on both ends were made using a mandrel with a male thread. The threads can be applied to struts with adjustable end fits and composite pressure vessels with threaded caps that enable disassembly for inspection and repair. Carbon fiber-reinforced plastic (CFRP) prepregs were laid up on a mandrel, wrapped with shrink tape, and cured in an oven. The threads were built-in, without using machine cutting, and the fibers on the thread were continuous through the thread and tubes for high strength. The thread was alternately rounded, convex, and concave in shape to enable CFRP prepregs to be laid up. Two types of specimen were made and tested. The layup sequence of specimen A was [0/h/90/h/0/h(1/2)]s, and that of specimen B was [0/h/90/h/90/h/0/h/90/h/90/h/90/h/90/h/0/h/90/90/0], where “h” denotes a helical layer along the concave part of the threads. The relation between load and strain is nonlinear because of the rounded shape of the threads; however, a simple and closed form analytical model was able to predict the strength of the threads and design of the threads. The model was compared with the experimental results. In addition, an application of threads for the pressure vessel of the hybrid rocket motor is also reported. The combustion test proceeded without failure. Visual inspection after the test indicated that the threads and tubes were not damaged, and thus, they can be applied to high-pressure and high-temperature rocket motors.

Multi-component measurement of grinding force during high speed internal thread grinding

Experiments of internal thread grinding and flat groove grinding show that grinding efficiency and quality can be significantly improved by increasing the wheel speed. According to the characteristics of internal thread grinding and flat groove grinding, the grinding force measurement experiment is designed. The equivalent substitution method is used to compare with the Grinding Force per Unit Area in surface grinding test under the same conditions. The experimental results show that the measurement error of Grinding Force per Unit Area is less than 25 %.

Technological support of thread quality with single methods

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.