Hand operated yield tightening system
AssigneeSPS Technologies, Inc.
InventorRussell J. Hardiman
Life of this patent
Estimating the term…
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.
Claims9
A tightening system for tightening a fastener assembly including a threaded fastener to the yield point thereof, comprising:
- wrench means for applying torque and imparting rotation to the threaded fastener when operably connected thereto;
- mechanical differentiation means connected to said wrench means for differentiating the magnitude of said torque with respect to the degree of said rotation, said differentiation resulting in the generation of discrete, intermittent output parameter signals, the rate of occurrence of successive output parameter signals being substantially directly proportional to the slope of a Torque-Rotation curve which could be generated for the fastener assembly being tightened;
- and
- indicating means adapted to receive said differentiating means output parameter signals for providing an indication signal when a change in the frequency of successive discrete, intermittent output parameter signals occurs indicative of a change in the slope of the curve, thereby indicating when the fastener assembly has been tightened to the yield point thereof.
A tightening system for tightening a fastener assembly including a threaded bolt and a nut adapted to engage the threads of the bolt, the system being adapted to determine the yield point of the fastener assembly, comprising:
- wrench means for applying torque and imparting rotation to one member of the fastener assembly when operably connected thereto;
- mechanical differentiating means connected to said wrench means, including an output member adapted to be in motion when said wrench means is imparting rotation to said one member of the fastener assembly, the speed of said motion being substantially proportional to the slope of a Torque-Rotation curve which could be generated for the fastener assembly being tightened;
- and
- indicating means operatively connected to said output member, said indicating means producing a series of successive discrete output signals, the rate of occurrence of said output signals being substantially proportional to the slope of said Torque-Rotation curve, thereby indicating when the fastener assembly has been tightened to the yield point thereof by the observation of a change in the rate of occurrence of successive ones of said signals.
A method of tightening a fastener assembly comprising the steps of:
- applying torque and imparting rotation to the fastener assembly;
- mechanically differentiating the magnitude of said torque with respect to the degree of said rotation for producing discrete, intermittent output parameter signals, the rate of occurrence of successive output parameter signals being substantially directly proportional to the slope of a torque-rotation curve which could be generated for the fastener assembly being tightened;
- monitoring said discrete, intermittent output parameter signals;
- and
- providing an indication when a change in the frequency of successive discrete, intermittent output parameter signals occurs indicative of a change in the slope of said torque-rotation curve, thereby indicating when the fastener assembly has been tightened to the yield point thereof.
Dependencies are inferred from the claim text.