TORQUE TOOLS a Torque Wrench Is a Precision Instrument Used to Apply Or Predetermine Tension on Bolts, Nuts, Lugs, and Fasteners for Assembled Parts
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TORQUE TOOLS A torque wrench is a precision instrument used to apply or predetermine tension on bolts, nuts, lugs, and fasteners for assembled parts. Torque wrenches are offered in different variations: click or needle mechanism, analog or digital. They are particularly useful in applications where the fastening elements (nuts, screws and bolts) must have a specific tension. They are commonly used in equipment handling liquids and low-pressure gases, control and instrumentation valves, internal combustion engines, air conditioning, bridges and structures, industrial piping, assembly of appliances, electric and electronic equipment, industrial, and many similar applications. There are also specialized torque wrenches, mainly for assembly lines, to fit nuts on electric or electronic component lids where it is necessary to repeat the operation without losing torque accuracy. In the automotive and heavy industries, torque multipliers are also used to apply high torque in reduced spaces, replacing long leverage handles and long wrenches when you need a high degree of precision. The torque wrenches presented in this chapter are called precision wrenches because they are designed, manufactured, and assembled with a high degree of accuracy and with components of the highest quality. URREA Torque Wrenches: • Include a great variety of products with more than 55 torque wrenches. - Torque Multipliers - Torque Gauges - Needle Torque Wrenches - Click Torque Wrenches - Electronic Torque Wrenches - Torque Screwdrivers • SAE and metric calibrated scales. • Great variety of shapes and designs, ratcheting or fixed head, and with comfortable plastic grips. • They are grouped and combined in more than 5 different mechanisms presented in convenient cases for their transport and protection. • The drives are blued and the multipliers come in 1/4”, 3/8”, 1/2”, 3/4”, 1”, and 1 1/2”. • Manufactured with high-quality, micro-alloy steel, precision-machined and thermal-treated to offer the best combination of hardness, tenacity and resistance. • All URREA torque wrenches feature a resistant nickel-chrome coating that prevents corrosion. • They meet national and international, American and European, standards. • The quality image of these products is reinforced by the indelible and permanent mark showing the country of origin. This mark meets ASME / ANSI standards, as well as rules established by the Federal Trade Commission in the United States. The information in this chapter is organized as follows: • Technical Standards. • About Torque. • Quick Selection Guide. • Detailed product specifications. 360 7 TORQUE TOOLS TORQUE MULTIPLIERS 368 TORQUE TORQUE WRENCHES SCREWDRIVERS 370 377 SUPERIOR QUALITY AFFORDABLE TOOLS 361 TECHNICAL STANDARDS Organization for Standardization). It issues the ISO 9000 series, related URREA manufactures its tools to quality systems, although it also issues product technical standards. In following technical standards. the United States there are various associations that issue or used to issue standards, such as GSA/US FEDERAL, ASME, ANSI and SAE. URREA torque wrenches are calibrated and have been certified to attain the required precision and meet international standards. The hand tool standards known as Federal are no longer updated and are being absorbed by ASME. The same is happening to standards issued by ANSI. A product technical standard is a document specifying design and manufacturing guidelines to ensure adequate product performance under Nowadays, ASME standards related to hand tools are initially reviewed by conditions that meet users’ requirements. These standards are issued by committees formed by different tool manufacturers, users, and distributors so private or governmental bodies and associations. they can be approved and issued by ASME. The only body issuing international standards is known as ISO (International APPLICABLE STANDARDS FOR: TORQUE WRENCHES GGG-W-00686c “Wrench Torque” B107.14M, 1998 “Hand Torque Tools” ISO 6789 “Hand Torque Tools” CALIBRATION DESCRIPTION To ensure correct precision in torque wrenches a testing device is used. A force is applied on the torque wrench. When 75% of the desired torque is reached, torque speed must not exceed two angle degrees per second. The torque wrench must be tested three times at three points in its scale; at its lower point (at 20% of maximum capacity), at its intermediate point and at its highest point (maximum torque capacity). The testing device must have a measurement accuracy of ± 1%. CALIBRATION CERTIFICATES URREA Professional Tools certifies the calibration of its torque wrenches based on the norms mentioned above, using calibrated measurement equipment that is approved by the National Institute of Standards and Technology (NIST) in the United States. CALIBRATION RECOMMENDATIONS Calibration of a torque wrench must be performed at an authorized location and by qualified personnel. The following table is a guide for calibration frequency. Frequency of use Recommended calibration frequency Less than 3 hours per week Every 12 months 3 to 5 hours per week Every 6 months 5 to 25 hours per week Every 3 months Used more than 25 hours per week Every month It must also be calibrated each time its maximum torque is exceeded or if it is stricken. 362 ABOUT TORQUE WHAT IS TORQUE? Technically: It is the torsion force on an element exerted by a force on an element that acts at a determined distance, equal to the force multiplied by the perpendicular distance between the force action line and the element’s rotation center. In Practice: Torque is equal to the product of a force times the distance or length of lever. Formula: T = L x F Where: T = Torque L = Distance or length of lever F = Force The most common unit of measurement for distance is: in the SAE system inches (in.) or feet (ft.) and in the Metric System centimeters (cm) or meters (m). The most common unit for force is: in the SAE system ounces-force (oz.) or pounds-force (lb.) and in the Metric System kilograms-force (Kg) or Newtons (N). 7 Therefore the most common units for Torque are: SAE system Metric System TORQUE Pounds-foot (ft-lb) Newton-meter (Nm) Pound-inch (in-lb) Kilogram-meter (Kgm) TOOLS Ounce-inch (in-oz) DeciNewton-meter (dNm) Torque wrenches feature a calibrated scale where it is possible to determine or read the value of the torque applied, depending on the type of torque wrench. When this scale does not coincide with the unit system in which you need your measurement, it is necessary to convert from one system to another. Next we provide some common conversion factors. TORQUE CONVERSION FACTORS Covert Multiply Covert Multiply From: To: By: From: To: By: in-oz in-lb 0.0625 dNm Nm 0.10 in-lb in-oz 16 Nm dNm 10 in-lb ft-lb 0.08333 Nm cmKg 10.2 in-lb cmKg 1.1519 Nm mKg 0.102 in-lb mKg 0.011519 Nm in-lb 8.85 in-lb Nm 0.113 Nm ft-lb 0.7376 in-lb dNm 1.13 cmKg in-lb 0.8681 ft-lb in-lb 12 cmKg Nm 0.09807 ft-lb mKg 0.1382 mKg in-lb 86.81 ft-lb Nm 1.356 mKg ft-lb 7.236 dNm in-lb 0.885 mKg Nm 9.807 FORMULA TO CALCULATE TORQUE WHEN AN ADAPTER IS ADDED TO THE TORQUE WRENCH There are times when it is necessary to use an adapter or extension on the torque wrench. When this happens it is necessary to recalculate the predetermined torque because the total length (from the drive’s center to the handle’s center mark) is altered. The following formula is used for this calculation: TW = TA x L L + A Where: TW = The new value to be set on the torque wrench with the added adapter length. This reading must be less than the designed torque value. TA = Designed torque value for the fastener. L = Torque wrench effective length measured from the drive’s center to the handle’s center mark. A = Adapter length, measured from the adapter’s drive center to the torque wrench’s drive center. SUPERIOR QUALITY AFFORDABLE TOOLS 363 ABOUT TORQUE WHAT IS A TORQUE MULTIPLIER? 25 revolutions A Torque Multiplier is a mechanism that increases torque in situations where a torque wrench may not have the capacity. Input 100 N.m. A multiplier works using a planetary gear system of one or more stages. Since it is required to multiply the torque while keeping the same power, this gearing system reduces speed. = Torque = Speed In planetary gearing systems, torque is applied to the planetary gear carrier (3 or 4 gears) whose teeth are meshed with the outside housing that normally rotates in opposite direction to the gear carrier. A reaction arm prevents the house from rotating, causing the planet gears to orbit around the sun gear. This way, as planetary gears orbit around the Output 2500 N.m. sun gear, the output drive does the same. 0.84 revolutions Without the reaction arm holding the housing, the output drive would not apply any torque. = Torque = Reaction REACTION PRINCIPLE Newton’s law dictates that for each exerted force, an equal and opposite force is produced. In applications requiring relatively low torque that can be applied with a torque wrench, this is not a problem because the reaction is absorbed by the user. However, if the desired torque requires the use of a multiplier, the resulting reaction can be absorbed only by an appropriate absorption mechanism. 0.5 m For this reason torque multipliers are fitted with a reaction system. L A 2,500 Nm torque output will cause a 5,000 N reaction force at a point 0.5 m from the rotating axis, or of 2,500 N at 1 m. F The reaction force value depends on the perpendicular component of the distance between the reaction point and the multiplication axis; in other words, the greater the distance the lesser the force.