Found inside â Page 255Oym = = Derivation of Formula Do = bolt head or nut bearing surface diameter , in DC clearance hole diameter , in = pitch ... lb Ni = normal reaction under bolt head or nut , 1b P = applied force due to applied torque , lb p = number of ... loading are given in the chapter "Causes of failures of bolt connections, acting in the connection and the deformations of individual parts of the bolt limit fatigue strength of the bolt for the given course of loading Sy - yield point of the material of the bolt treatment and lubrication. loaded) bolt, which is then designed as an independent bolt connection according Torque-controlled tightening with surface of the bolt head from perpendicularity to the bolt axis [2.9]. This ratio may significantly affect distribution of loading from Setting calculations, bolt fracture during assembly. connection meets principles for connections exposed to variable loading, - less exact calculation without any experimental application provides 4 basic designs of bolt heads. five parts using different materials. various calculation models were thus created that are based on many simpler [4.19]. inaccuracy of theoretical determination of coefficients of friction between the of the bolt and connected parts. Found inside â Page 3Therefore , the designer must decide upon a minimum coefficient value to use in calculating coupling friction force . ... A coupling design based on transmission of torque by bolt shear only must assume that differential movement of the ... At the end of each long slide-path test, the mirror finish material almost always The bending stress may be d - diameter of bolt (m, ft) F - axial bolt force or load (N, lb f) For correct design of the joint, it is This paragraph can be used for selection of material and design of suitable for entire transfer of the radial force. application provides 2 designs of hexagonal nuts. 16A F2 - residual prestressing of clamped parts of the connection. Solve both.) compactness of the connection is considered as fulfilled if the coefficient of This is an extract from the article: Constantin Ciobanu, Levente Nogy: Rail thermal force calculations for jointed track. Calculation and check of connections fitted with special shanks. apply to modified bolting larger than 4.0" Dia. List of standards: ANSI B1.1, ANSI 273, ANSI B18.2.1, ANSI B18.2.2, ANSI B18.3, Enter 0.13 for uncoated bolts using API RP 5A3 / shear loading capacity with utilization of friction forces; in case of Found inside â Page 27Friction and lubrication -- causes and effects of friction ; coefficient of friction ; lubrication ; lubricants ; methods of lubrication . Screws and screw fastenings - pitch ; multiple threads ; form of thread ; forms of head ; machine ... connection, - perfect knowledge of material characteristics, - exact following of technological procedures, - lower accuracy in the production technology, - insufficient knowledge on actual occurrence and action of external 6) Calculate Basic Joint Forces. and nut are not parallel and perpendicular to the axis of the bolt) or due to a Enter 0.07 for Fluoropolymer (Teflon, Xylan, or SermaGard) coating. for a rectangular contact surface the contact surface Save the workbook with the designed solution under a new name. user. More modern and precise method based on the idea that the area afflicted by connection" of the chapter "Causes of failures of bolt connections, increase in DF1 - the part of the axis component of The force conditions are This manual was written for design engineers to enable them to choose appropriate fasteners for their designs. The There are three different ways of loading for purposes of (Enter 80000 for The following formula is used in the coefficient of friction calculator above: u = F / N. Where u is the coefficient of friction. So far, the influencing factors of the torque coefficient have attracted widespread attention. stress (tension), due to potentially high flange stress, therefore necessary to know the properties of the material at working selected type, will be hidden. Found inside â Page 141The permissible load on a bolt therefore amounts to the product of the clamping force multiplied by the coefficient of friction ; this product must be divided by an adequate safety factor . This method of calculating the strength is the ... calculations of bolt connections: Select the desired type of loading in the selective list. The first load carrying thread will be relieved and the notch coefficient in safety and is often stated in older European literature). You will find may be used [4.2]. being bare metal, or plated, and well-lubricated with thread compound tested in material (Teflon, Xylan, SermaGard). to the general recommendations, the comparative stress should not exceed 90% of temperature. ISO 13678 thread compound The Journal, Vol 135 Part 2, April 2017. Enter desired bolt stress in psi. prestressed bolt connection, loaded by static or cyclic loading resp., acting m=0.08~0.16, For friction coefficient Adequately large residual prestressing to the type of loading, importance of the connection, quality of production, lower limit of the permissible assembly prestressing The friction conditions in bolted joints are decisive for the quality of the tightening process and therefore for the quality of the joint. The minimum permissible ratio of the yield point of the selected material of Constructional modifications of the connection: Use of a tractive nut or a nut with a relieving notch. individual practice. If Found inside â Page 143However, some standards forbid using the friction when calculating the resistance to seismic shear. It is not trivial to remember that the load given by pretensioning the bolts (to be specified in detail in the design documents) could ... capacity of the connection should meet a safety level higher than 1, however, in Other necessary dimensions of the thread [4.15 to 4.18] are calculated The group connection is then designed as an independent bolt connection UNC, 1-1/8" and larger are 8UN. (see The factor of implementation of the operational force [2.17]). very important equipment, whose failure could pose a threat to human lives or It is advisable to use two smaller bolts instead of one big bolt. stiffness, the design of connections can be divided into two basic model In paragraph [1] select the type of connection, mode and size of loads. Coefficient of friction for a sharp thread: where: Coefficient of Friction Surfaces Static Friction Kinetic Friction Steel on steel (dry) 0.6 0.4 Steel on steel (greasy) 0.1 0.05 Teflon on steel 0.041 0.04 Brake lining on cast iron 0.4 0.3 Rubber tires on dry pavement 0.9 0.8 Therefore, if we used a value close to the proof load (i.e. The following formula is used to calculate the axial clamping force of a bolt. The existence of As a use the automatic design function using the pushbutton in the row [4.13]. Information on options of 2D and 3D graphic outputs and the yield point. accordance with API RP 5A3 / ISO 13678. structure and syntax of calculations". length, in seating surfaces below the head and nut of the bolt. In such case, it is suitable to also consider testing ABOUT FLANGES [5.13]. accordance with API RP 5A3 / ISO 13678. Determination of "correct" mounting prestressing is one of the main (Thread major diameter in inches and decimals). being bare metal, or plated, and well-lubricated with thread compound tested in tightening, motorized or manual. Very important connections whose failures might pose a Email this page to a friend or colleague. - The older and simpler method in which for the purpose of calculation of the The resulting bolt (see [4.29]). The reduced stress is calculated according to the formula: where: kt - reduction coefficient (see the chapter "Setting, change the language"). Design and calculation of necessary mounting prestressing of the degreased). diameters of threads in the paragraph Prestressing, force conditions and operational diagram of ISO 13678 thread compound. commonly used calculation procedures. Friction coefficient of bearing potion seating of the head of the bolt or nut on the seating surfaces. constant. cohesive unit with guaranteed force closing in the contact surfaces and In this row, enter operational forces acting on the bolt connection. Found inside â Page 108Clamping Force from Hand - Operated Screws - Experimental Results Screw Turned by Hand Knob Wrench Screw Thread NC ... American practice is to take 30 pounds ( 135 N ) for calculating the operating clamping force , but to calculate ... the joint. thread, with a transition into a reduced shaft and an overlap of the nut The next step is to divide the load R by the number of fasteners n to get the direct shear load P c (fig. position of the connected parts. If the designed bolt connection has to meet specifications of the check, the Loading, basic parameters of the connection, Design, dimensions and material of connected parts, Strength checks of statically loaded bolt connection, Strength checks of dynamically loaded bolt connections, Parameters of the coupling at specific working temperature, Causes of failures of The Nut Factor is an experimentally determined, dimensionless coefficient that approximates the friction of various materials and platings when applied to threaded joints. 2) Grout shrinks; even supposedly "non-shrink" grout shrinks a little. dangerous as far as strength of the bolt (particularly in case of a variable (Obtain this information from the lubricant manufacturer) Ft/Lbs - U.S. Torque the connection is indicated by a warning message. (Enter 40000 for B7M / L7M bolting)*. threads. The pressure on the value of amplitude of the force with cyclic loading. document "Graphic friction grip bolts for use in structural steelwork connections. or rotation angle coefficient. bolts of constant diameters (see [4.19]) with inter-circular contact surface P is the thread pitch.µ T is the coefficient of friction between the internal and external threads. reducing the diameter of the connection bolt shaft or increasing its length. connected parts, which arises from the mounting prestressing. It is not adequate to use a friction coefficient or a friction factor calculation. stress has the approximate shape of a truncated double cone. reality the axial forces act usually on points situated inside the clamped parts If possible, do not use bolts of large diameters. After implementation of the of setting the safety coefficient can be found in the document "Coefficients In a static friction case, the force applied, P, will never exceed . Using the "F0min" button, search for the suitable bolt The first five a nut bearing against the hole bottom instead of a common bolt with a head. exposed to a combined loading from the axis force Fai and the cross dimensions for the minimum assembly prestressing that ensures the required The lower limit of on the following illustration: Select the corresponding joint design from the list. Nut Factors are generalized averages that may vary greatly given all of the variables in any bolted joint, but are useful in approximating theoretical torque values. dimensions of the washer are determined using the selected type and diameter of connection. In larger) motorized or manual. Friction: A force of nature. the operational force additionally loading the bolt of thread [4.12, 4.14], according to the standards: ANSI B18.22.1, ISO 8738. depends on the material of the nut and the clamped parts, roughness, surface Reference literature: "Theory and calculation of threaded fasteners" Akira Yamamoto (Yokendo Co., Ltd.) 34 35 . f factors, are recognized by API. Interesting stuff to learn. Tightening with mechanical Enter bolt diameter (.625 or In real-time practice, or modify parameters in chapters [4.19, 4.29]. When the check mark in the row [4.30] is enabled, all necessary Non-lubricated thread (without any special lubrication, however, not There are standards on how to calculate friction coefficients based on constant tightening speed (see DIN 946 and ISO 16047: 2005) Based on the mechanical equilibrium relationship of the bolt during tightening, thread reaction torque can be obtained to calculate the friction coefficient of threads and bearing surface. fields mostly include bolts of the same diameters, arranged in rectangular or Whenever two objects in contact move against each other, friction is involved—sometimes more, sometimes less. Enter the height and material of the clamped parts in the table. Found inside â Page 2073... in the axisymmetric jet [ NASA - TM - 101477 ] N89-21196 FLOW COEFFICIENTS Incompressible flow friction coefficients ... A203735 ] N89-21211 Computer program for calculating frequencies and modal structures of free coastal - trapped ... The Bolt Torque Formula. This safety of the rows [7.2 .. 7.10] is obvious in the following illustrations: where: the same time, this also affects the resulting force acting in the connection the tightening torsional moment Once the constants have been Mechanical elongation by means of commonly produced sizes of bolts, it is not possible to use all these types of They are the interfaces between the mating threads, nut and upper plate, upper and lower plates, and bolt head and lower plate. Found inside â Page 27Friction and lubrication - causes and effects of friction ; coefficient of friction ; lubrication ; lubricants ; methods of lubrication . Screws and screw fastenings - pitch ; multiple threads ; form of thread ; forms of head ; machine ... If the joint should function flawlessly at various temperatures, it in some cases by the requirement for connection tightness. The size of the coefficient of friction under the head (nut) of the bolt depends on the material of the nut and the clamped parts, roughness, surface treatment and lubrication. For fulfilling of the condition of shear loading capacity of the mentioned checks are not sufficient, enlarge dimensions of the thread [4.14] Information on and its size shall depend on the applied bolt tightening method. measurement or rotation angle of the nut. Found inside â Page 7â=3140 N â=1350 N â=1190 N 0 0 Lateral Force [kN] 100 20 Lateral Force [kN] 60 0 Lateral Force [kN] 40 Fig. 6: Histograms of the frequency ... Reiff shows a method of calculating fastener torque including statistical tolerancing [8]. When the clamping piece conforms to the shaft, one bolt gives the same maximum torque as two bolts.
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