Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: Apparatus for measuring the amount of previously applied torque to a fastener. A transducer is utilized to sense the amount of a subsequently applied torque to the fastener and provides an output signal representative of the applied torque. The torque is applied until further motion or breakaway of the fastener is obtained. Typically, the signal from the transducer increases until breakaway of the fastener is obtained and then the signal decreases momentarily to a valley before it again increases with further applied torque. A positive peak detector senses the maximum positive output of the transducer before the signal begins to decrease. A negative peak detector senses the minimum negative output of the transducer before the signal again increases. The negative peak detector is energized by a switching network upon detection of a negatively sloped signal from the transducer.

Abstract: A method and apparatus for controlling final tension on a fastener being run up and set. An efficiency factor is developed and utilized for attaining predetermined final tension on a fastener, or a group of similar fasteners, being operated upon. The efficiency factor is a ratio between work on a theoretical fastener, i.e., one wherein friction load is absent in work calculations, and work on an actual fastener. Having obtained the efficiency factor, the actual torque load on a fastener to attain predetermined tension value, can be established by use of the efficiency factor.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: A hand operated tightening system for tightening a fastener assembly to its yield point is disclosed. The system includes a wrench for applying torque to a threaded fastener and means for mechanically differentiating the magnitude of torque applied with respect to the degree of rotation of the fastener. This differential represents the slope of the torque-rotation curve of the particular fastener assembly being tightened and is a constant while in the elastic range. Means are provided to signal a change in the magnitude of the differential so as to indicate when the yield point of the assembly has been reached. In one embodiment, the differentiating means emits an audible signal which is used to indicate that the yield point has been reached.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by different tightening strategy.

Abstract: A mine warning device which comprises tensioned arms that abut the roof of an underground mine. The arms support a cone shaped shaft which is attached to a warning indicator. The indicator remains invisible within the body of the device when the rocks forming the roof are stable. Upon a shifting of the mine roof, which applies pressure to the arms of the device, the shaft is released and the warning cylinder falls into view. Preferably, the device attaches to bolts that hold plates to the mine roof and the warning indicator is fluorescent.

Abstract: The preferred embodiment of the invention disclosed in this application includes a wrench, for example an operator powered wrench, for tightening a fastener assembly by the incremental application of tightening force. Also included is a control circuit for detecting a phenomena indicating that the joint assembly in which the fastener assembly is installed has been tightened to its yield point. The control circuit further includes checking means for determining that the fastener assembly is being tightened to assure that when the phenomena is detected, the joint assembly has been tightened to the yield point.

Abstract: An apparatus is provided for making threaded joints, such as pipe joints, including means for storing and indicating values of the actual torque applied to one of the members being rotated with respect to the other member and values of actual turns made by the one member and a d.c. power supply for powering the storage and indicating means. The power supply is connected to a first source of power such as an a.c.-to-d.c. converter for normal operation. The power supply generates a predetermined magnitude voltage and has means responsive to the predetermined magnitude value for switching to a second source of power, such as a battery, when the first source of power fails. The power supply also includes a d.c.-to-d.c. inverter having transistor switching means connected between a transformer and a power source. The transistor switching means are switched on and off to induce current flow in the transformer secondary to generate the power to the storage and indicating means.

Abstract: An apparatus for measuring and controlling a force such as torque, pull or weight. One example is an apparatus for making up two members having mating threaded connections, such as pipe joints, head bolts and all types of threaded fasteners for insuring that a specified torque has been applied. A comparator compares the measured torque with a desired torque value and disengages the making up of the joint when the measured torque exceeds the selected torque. A testing circuit is provided for applying a test value for testing the operation of the apparatus in the absence of actual measured torque. An adjustment circuit adjusts the output to conform with a known test value. An adjustment is provided to compensate for the length of the torque arm at which the torque measurement is made.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: The integrity of attachment of bolts in a substrate such as a wall of a mine is tested by introducing vibratory energy into an exposed end portion of the bolt and ascertaining the vibratory energy absorbed by the bolt and its attachment.

Abstract: Apparatus for measuring the pre-tension of a threaded bolt which is elongated by means of a tensioning unit and a screwed-in tensioning bolt; a measuring rod is inserted into a central hole in the threaded bolt and the difference in length is determined by means of a length measuring device.The measuring rod is guided in the housing of the tensioning unit, secured against rotation, and is threaded to engage a threaded bushing. The threaded bushing is longitudinally movable and secured against rotation in a bushing having external teeth. Rotation of the tensioning bolt is transmitted via gears to the threads on the measuring rod and converted into an up or down movement. The measurement may be made when the measuring rod comes to rest at the lowest point of the central hole.

Abstract: An apparatus for measuring the pre-tension of a threaded bolt by means of a two part measuring rod introduced into a central hole of the threaded bolt and of a length measuring device.The measuring rod includes an upper rod threaded to a lower tube which is secured against rotation. Rotation of the threaded rod by a motor moves the end of the measuring rod in or out of the central hole.

Abstract: An arrangement for measuring the pre-tension of a threaded bolt having a central drill hole. A part is fastened to the lowest point of the drill hole and the difference in length of the part relative to the threaded bolt is determined via a length measuring device. An electric holding magnet, introduced into the hole, is fastened to a cable running from a cable drum and carrying an electromagnet, which, when excited, adheres to the closed hole at its lowest point; the cable is tightened and its length is held constant by a ratchet. The cable drum is movably supported on a tube connected to the threaded bolt in such a manner that, when the cable is loose, its carrier is pushed by a spring surrounding the tube against an upper flange on the tube; a length measuring device borne on the carrier contacts a surface of the tube. The measurement is performed with the cable tightened and its length held constant by the ratchet.

Abstract: A method for attaining a predetermined compressive stress is achieved by a device in the form of a washer, coating, or plug which as a function of pressure does not yield significantly, but when a predetermined pressure is reached, a sudden change in structure takes place which effects detonation of an explosive mixture which detonation is indicated by a sound, a puff of smoke, a change of appearance, a sudden release of heat, or an instantaneous increase in friction. The device includes a porous brittle body in which an explosive substance has been absorbed, and also preferably hard particles that aid in effecting detonation when the porous body goes through a physical change. The detonation can also join contact surfaces together, serve as an indication of desired prestress or torque applied to a fastener, to indicate a load limit, and the like.

Abstract: There is disclosed a technique for tightening threaded fasteners in which values of offset torque, initial tension rate relative to angle, final tension rate relative to angle and other joint related factors are empirically determined by instrumenting a plurality of fasteners of the type ultimately to be tightened. In one embodiment, torque and angle are monitored during tightening. Calculations are conducted, while tightening, to determine the tension prevailing in the bolt at a particular angle of advance. By using the calculated tension value and the particular angle of advance, an instantaneous position of threading advance on the tension-angle curve of the fastener is established. From this instantaneous position, it is determined how much greater angle of advance or how much torque is required to tighten the fasteners to a final desired tension value. The same technique may also be used merely to monitor tightening which is terminated by a different tightening strategy.

Abstract: An indicator for sensing the degree of tension in a tensile member. An indicator element defined by a deformable elastomeric member is positioned within a translucent containment wall. Upon application of a tensile force to the tensile member the indicator element is caused to be compressed and expanded radially outwardly into contact with the containment wall. The degree of contact of the indicator element and the containment wall varies as a function of the amount of tension applied to the tensile member. As a consequence the appearance of the indicator element as viewed through the translucent containment wall will vary as a function of the tension applied to the tensile member.The invention also has application in compression systems. One particular application disclosed is an indicator for sensing the appropriate degree of compression as applied to glass curtain walls used in dry pressure glazing systems.

Abstract: A tightening and control system is disclosed for automatically tightening a blind fastener assembly to a desired tightened condition in a workpiece, where the assembly is of the type which exhibits more than one installation region on a graph of two tightening characteristics during a complete tightening cycle. Typical of such assemblies are the types which first form an outwardly flared bulb adjacent the blindside surface of a workpiece and thereafter are tightened against the blindside surface to a predetermined clamp load condition. Such fasteners typically exhibit a curve of two related input tightening characteristics, such as torque and rotation, torque and time, or force and stroke. Each curve has a bulb forming region characterized by a generally linear portion followed by a marked drop off in the slope, an intermediate region, and a tightening region having a somewhat similar shape to the bulb forming region.

Abstract: A tightening and control system is disclosed for automatically tightening a fastener to a predetermined tightened condition in a workpiece, where the fastener is of the type which exhibits more than one installation region on a graph of two tightening characteristics during a complete tightening cycle. Typical of such fasteners are thread tapping fasteners, such as thread-cutting or thread forming types, which first generate a mating thread in a workpiece material and thereafter are tightened in the workpiece to a predetermined load condition. Such fasteners typically exhibit a curve of two related input tightening characteristics, such as torque and rotation, having a thread forming region characterized by a generally linear portion followed by a marked drop off in the slope, an intermediate region having several possible characteristic shapes, and a tightening region having a somewhat similar shape to the thread forming region.

Abstract: Apparatus and method for determining the tensile load on a mine roof bolt, which is indicative of the support provided by the bolt. The device comprises a hammer for striking a roof bolt to produce a sound pulse, a microphone for picking up the sound pulse, and a sound comparator having a recorded sound or sounds whereby an operator can match the induced sound pulse with a recorded sound pulse to provide an indication of the tensile load on the roof bolt. The comparator may include a range of sounds, or may incorporate a variable speed function whereby the pitch of the recorded sound may be varied until the induced sound is matched. Comparison of the induced sound with the recorded sound provides an indication of the tensile load on the roof bolt.

Abstract: An indicator to check whether a screw connection has been properly tightened, comprising a housing to be penetrated by the screw bolt, and having a bottom at one end and a slide-fit disc at the other end, compression springs housed within the housing and being compressed by the tightening force, the relative position of the disc within the housing being representative of said force, and visible or tangible for check of proper tension.

Abstract: An improved method for creating built-in overload protection against further yielding in a bolt which previously has been tightened to its yield point, the method comprising rotating the bolt head or nut in the direction opposite from tightening while measuring the wrenching torque required for this rotation and stopping the rotation when the magnitude of the wrenching torque indicates that the torque acting in the bolt shank is fifty percent or less of the value existing at the end of tightening; and, a pulsed air motor wrench which at the end of tightening a bolt to its yield point automatically shifts to an untightening mode of operation and stops untightening when the untightening wrenching torque becomes equal to or exceeds the value CT.sub.WY wherein C is a numerical constant determined theoretically or experimentally and T.sub.WY is the wrenching torque acting at the end of tighening.

Abstract: An inductance-capacitance loop defines a resonant circuit and is arranged in a member subject to stress. Strains resulting from the stress vary the inductance or capacitance of the circuit, and its resonant frequency. A dip meter is used to detect the resonant frequency and thus provides a reading indicative of the stress in the member.