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ISO 724
A screw thread, often shortened to ''thread'', is a helical structure used to convert between rotational and linear movement or force. A screw thread is an inclined plane wrapped around a cylinder or cone in the form of a helix, with the former being called a ''straight'' thread and the latter called a ''tapered'' thread. More screw threads are produced each year than any other machine element.. Threads are generally produced according to one of the many standards of thread systems. Standards Development Organizations such as the American National Standards Institute, American Society of Mechanical Engineers, SAE International, International Organization for Standardization, Deutsches Institut für Normung (German Institute for Standardization), British Association and others produce these standards for manufacturers to follow when producing threaded components. Currently used thread standards Obsolete thread standards See also *ISO metric screw thread * "History of standard ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Screw Thread
A screw thread is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a ''straight'' thread and the latter called a ''tapered'' thread. A screw thread is the essential feature of the screw as a simple machine and also as a threaded fastener. The mechanical advantage of a screw thread depends on its ''lead'', which is the linear distance the screw travels in one revolution. In most applications, the lead of a screw thread is chosen so that friction is sufficient to prevent linear motion being converted to rotary, that is so the screw does not slip even when linear force is applied, as long as no external rotational force is present. This characteristic is essential to the vast majority of its uses. The tightening of a fastener's screw thread is comparable to driving a wedge into a gap until it sticks fast through friction and slight ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acme Thread
Trapezoidal thread forms are screw thread profiles with trapezoidal outlines. They are the most common forms used for leadscrews (power screws). They offer high strength and ease of manufacture. They are typically found where large loads are required, as in a vise or the leadscrew of a lathe. Standardized variations include multiple-start threads, left-hand threads, and self-centering threads (which are less likely to bind under lateral forces). The original trapezoidal thread form, and still probably the one most commonly encountered worldwide, with a 29° thread angle, is the Acme thread form ( ). The Acme thread was developed in 1894 as a profile well suited to power screws that has various advantages over the square thread,See: * Simpson, John and Proffitt, Michael, ed.s, "acme", ''Oxford English Dictionary: Additions Series'', vol. 3 (Oxford, England: Oxford University Press, 1997)p. 10.* The Acme thread was proposed by Albert Man Powell, then president of the Powell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lists Of Standards
A list is a set of discrete items of information collected and set forth in some format for utility, entertainment, or other purposes. A list may be memorialized in any number of ways, including existing only in the mind of the list-maker, but lists are frequently written down on paper, or maintained electronically. Lists are "most frequently a tool", and "one does not ''read'' but only ''uses'' a list: one looks up the relevant information in it, but usually does not need to deal with it as a whole".Lucie Doležalová,The Potential and Limitations of Studying Lists, in Lucie Doležalová, ed., ''The Charm of a List: From the Sumerians to Computerised Data Processing'' (2009). Purpose It has been observed that, with a few exceptions, "the scholarship on lists remains fragmented". David Wallechinsky, a co-author of ''The Book of Lists'', described the attraction of lists as being "because we live in an era of overstimulation, especially in terms of information, and lists help us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Pipe Thread
American National Standard Pipe Thread standards, often called national pipe thread standards for short, are United States national technical standards for screw threads used on threaded pipes and pipe fittings. They include both tapered and straight thread series for various purposes, including rigidity, pressure-tight sealing, or both. The types are named with a full name and an abbreviation, such as NPT, NPS, NPTF, or NPSC. MIP is an abbreviation for male iron pipe, and FIP is an abbreviation for female iron pipe. Outside North America, some US pipe thread sizes are widely used, as well as many British Standard Pipe threads and ISO 7–1, 7–2, 228–1, and 228-2 threads. Types The various types are each named with an abbreviation and a full name, as follows: Uses Threaded pipes can provide an effective seal for pipes transporting liquids, gases, steam, and hydraulic fluid. These threads are now used in materials other than steel and brass, including PTFE, PV ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Screw Thread
A screw thread is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a ''straight'' thread and the latter called a ''tapered'' thread. A screw thread is the essential feature of the screw as a simple machine and also as a threaded fastener. The mechanical advantage of a screw thread depends on its ''lead'', which is the linear distance the screw travels in one revolution. In most applications, the lead of a screw thread is chosen so that friction is sufficient to prevent linear motion being converted to rotary, that is so the screw does not slip even when linear force is applied, as long as no external rotational force is present. This characteristic is essential to the vast majority of its uses. The tightening of a fastener's screw thread is comparable to driving a wedge into a gap until it sticks fast through friction and slight ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Association Screw Threads
British Association screw threads, or BA screw threads, are a set of small screw threads, the largest being 0BA at 6 mm diameter. They were, and to some extent still are, used for miniature instruments and modelling. They are unusual in that they were probably the most "scientific" design of screw, starting with 0BA at 6.0 mm diameter and 1.0 mm pitch and progressing in a geometric sequence where each larger number was 0.9 times the pitch of the last size. They then rounded to 2 significant figures in metric and then converting to inches and rounding to the thousandth of an inch. This anticipated worldwide metrication by about a century. The design was first proposed by the British Association in 1884 with a thread angle and depth based on the Swiss Thury thread, it was adopted by the Association in 1903. The Thury thread was different in that it went both positive and negative all the way up to a size of −20 which was 75.2 mm diameter by 8.23 mm pitch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edison Screw
Edison screw (ES) is a standard lightbulb socket for electric light bulbs. It was developed by Thomas Edison (1847–1931), patented in 1881, and was licensed in 1909 under General Electric's Mazda (light bulb), Mazda trademark. The bulbs have Screw thread#Handedness, right-hand threaded metal bases (caps) which screw into matching threaded sockets (lamp holders). For bulbs powered by Single-phase electric power, AC current, the thread is generally connected to Ground and neutral, neutral and the contact on the bottom tip of the base is connected to the "live" phase. In North America and continental Europe, Edison screws displaced other socket types for general lighting. In the early days of electrification, Edison screws were the only standard connector, and appliances other than light bulbs were connected to AC power via lamp sockets. Today Edison screw sockets comply with international standards. Their types are designated as "Exx", such as "E26", where "xx" indicates the dia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ISO Metric Screw Thread
The ISO metric screw thread is the most commonly used type of general-purpose screw thread worldwide. They were one of the first international standards agreed when the International Organization for Standardization (ISO) was set up in 1947. The "M" designation for metric screws indicates the nominal outer diameter of the screw thread, in millimetres. This is also referred to as the "major" diameter in the information below. It indicates the diameter of smooth-walled hole that an externally threaded component (e.g. on a bolt) will pass through easily to connect to an internally threaded component (e.g. a nut) on the other side. For example, an M6 screw has a nominal outer diameter of 6 millimetres and will therefore be a well-located, co-axial fit in a hole drilled to 6 mm diameter. Basic profile The design principles of ISO general-purpose metric screw threads ("M" series threads) are defined in international standard ISO 68-1. Each thread is characterized by it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
British Standard Whitworth
British Standard Whitworth (BSW) is a screw thread standard that uses imperial-unit, imperial (inch-based) units. It was devised and specified by British engineerJoseph Whitworth in 1841, making it the world’s first national screw thread standard. It became widely adopted across the United Kingdom and its former colonies, influencing engineering practices globally. BSW also laid the foundation for several related thread standards, including British Standard Fine (BSF),British Standard Pipe (BSP), British Standard Conduit (BSCon) and British Standard Copper (BSCopper) threads. Although largely superseded by metric standards in modern engineering, BSW remains in use in restoration, vintage machinery, and certain legacy industries. History The Whitworth thread was the world's first national screw thread standard, devised and specified by Joseph Whitworth in 1841. Until then, the only standardization was what little had been done by individual people and companies, with some com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buttress Thread
Buttress thread forms, also known as sawtooth thread forms or breech-lock thread forms. are screw thread profiles with an asymmetric shape, having one square face and the other slanted. They are most commonly used for leadscrews where the load is principally applied in one direction. The asymmetric thread form allows the thread to have low friction and withstand greater loads than other forms in one direction, but at the cost of higher friction and inferior load bearing in the opposite direction. They are typically easier to manufacture than square thread forms but offer higher load capacity than equivalently sized trapezoidal thread forms. Buttress thread characteristics The buttress thread form is designed to handle axial thrust applied principally in one direction. The load-bearing thread face is perpendicular or at a slight slant (usually no greater than 7°) to the screw axis. The trailing face is slanted, often at 45°. The resulting thread form has the same low frictio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unified Thread Standard
The Unified Thread Standard (UTS) defines a standard thread form and series—along with allowances, tolerances, and designations—for screw threads commonly used in the United States and Canada. It is the main standard for bolts, nuts, and a wide variety of other threaded fasteners used in these countries. It has the same 60° profile as the ISO metric screw thread, but the characteristic dimensions of each UTS thread (outer diameter and pitch) were chosen as an inch fraction rather than a millimeter value. The UTS is currently controlled by American Society of Mechanical Engineers, ASME/American National Standards Institute, ANSI in the United States. Origins Basic profile Each thread in the series is characterized by its major diameter and its pitch, . UTS threads consist of a symmetric V-shaped thread. In any plane containing the thread axis, the flanks of the V have an Thread angle, angle of 60° to each other. The outermost and the innermost of the height of the V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helix
A helix (; ) is a shape like a cylindrical coil spring or the thread of a machine screw. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices. The word ''helix'' comes from the Greek word , "twisted, curved". A "filled-in" helix – for example, a "spiral" (helical) ramp – is a surface called a '' helicoid''. Properties and types The pitch of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two (typically congruent) helices with the same axis, differing by a translation along the axis. A circular helix (i.e. one with constant radius) has constant band curvature and constant torsion. The slope of a circular helix is commonly defined as the ratio of the circumference of the circular cylinder that it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
