METHOD FOR CONTROLLING TENSILE STRESS OF A SHANK, SUCH AS A SCREW OR DOWEL PIN, AND DEVICE FOR CARRYING OUT SAID METHOD
First Claim
1. A method for controlling tensile stress of a rod, such as a screw or pin, by the axial extension of said rod and the positioning of at least one retaining member, before the rod is released, such that the rod is blocked at the two ends of the useful clamping length with a residual clamping tensile force, characterized in that measurements are made which represent the elongation of the rod in the stretched state under a measured extension force and of the rod after release in relation to the rod before extension, by comparing values supplied by at least one sensor during extension and after release with a reference value supplied by this sensor before extension, and, on the basis of these data, a residual clamping force in the useful clamping length of the released rod after extension is calculated.
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Abstract
In a method for controlling tensile stress of a clamping rod, such as a screw or pin, by the axial extension of the rod and the positioning of at least one retaining member, before the rod is released, such that the latter is blocked at the two ends of the useful clamping length with a residual clamping tensile force, measurements are made which represent the elongation of the rod in the stretched state under a measured extension force and of the rod after release in relation to the rod before extension, by comparing values supplied by at least one sensor during extension and after release with a reference value supplied by this sensor before extension, and, on the basis of these data, a residual clamping force in the useful clamping length of the released rod after extension is calculated.
49 Citations
15 Claims
- 1. A method for controlling tensile stress of a rod, such as a screw or pin, by the axial extension of said rod and the positioning of at least one retaining member, before the rod is released, such that the rod is blocked at the two ends of the useful clamping length with a residual clamping tensile force, characterized in that measurements are made which represent the elongation of the rod in the stretched state under a measured extension force and of the rod after release in relation to the rod before extension, by comparing values supplied by at least one sensor during extension and after release with a reference value supplied by this sensor before extension, and, on the basis of these data, a residual clamping force in the useful clamping length of the released rod after extension is calculated.
- 12. A device for carrying out a method for controlling the tension of a clamping rod, comprising an actuator, a force sensor and a rod elongation sensor, characterized in that it comprises a calculation unit capable of receiving an output signal from the elongation sensor and an output signal from the force sensor, the unit comprising a module capable of calculating a data item representing the elongation of the useful clamping length of the rod in a stretched state and after release, by comparing values supplied by the elongation sensor during extension and after release with a reference value supplied by this sensor for the rod in the state of rest, the module being capable, furthermore, of deducing from said calculations a residual clamping force (FO) in a useful clamping length of the rod.
Specification