Method and apparatus for improved measurement of tension and compression in a wireline

• US 6,343,515 B1
• Filed: 01/03/2000
• Issued: 02/05/2002
• Est. Priority Date: 07/02/1998
• Status: Expired due to Term

• Current Assignee: Varco International Inc. (NOV, Inc.)
• Original Assignee: Martin-Decker Totco
• Inventors: Dodson, Steve W.
• Primary Examiner(s): NOORI, MAX H
• Application Number:
  US09/476,861
• Time in Patent Office: 764 Days
• Field of Search: 738/26, 738/28, 738/31, 738/624.51, 738/624.53, 738/624.6, 738/624.71, 738/624.73, 738/624.74
• US Class Current: 73/831
• CPC Class Codes: G01L 5/10 using electrical means
• CPC Class Codes: G01L 5/107 for measuring a reaction force applied on an element disposed between two supports, e.g. on a plurality of rollers or gliders
• CPC Class Codes: G01N 3/08 by applying steady tensile or compressive forces G01N3/28 takes precedence

Abstract

A tension measuring device including an elongated body having two ends and a deflection block secured to each end of the elongated body for holding a line spaced apart from the elongated body. The deflection blocks are positioned equidistant from a center of the elongated body. A clamping mechanism between the deflection blocks clamps the line to the elongated body wherein increased tension in the line will bend the elongated body. A strain gage element is connected to the elongated body for producing an output signal proportional to the bending of the elongated body. The strain gage element is positioned on the elongated body and is applied directly to the bending of the elongated body. A linearizing signal device is connected to the strain gage element for processing the output signal and for providing a readable output representative of the tension on the line. The linearizing signal device provides for linearization of the output signal from the strain gage element and is, for example, a capacitive circuit or a linear signal processor. A line tension readout device is adapted to receive and display the readable output representative of the tension of the line.

Claims

1. A tension measuring device comprising:

(a) an elongated body having two ends, said elongated body further comprising a hollow interior comprising a first interior wall and a second interior wall, wherein the first interior wall and the second interior wall oppose each other;

(b) a deflection block secured to each end of the elongated body for holding a line spaced apart from the elongated body;

(c) a clamping mechanism between the deflection blocks from clamping the line to the elongated body wherein increased tension in the line will bend the elongated body;

(d) a first strain gauge element attached to the first interior wall and a second strain gauge element attached to the second interior wall, wherein the first strain gauge produces an output signal proportional to the bending tension of the first interior wall of the elongated body and the second strain gauge produces an output signal proportional to the compression of the second interior wall; and

(e) a linearizing signal device connected to the first and second strain gauge elements for processing the output signal and for providing a readable output representative of the tension on the line.

2. A tension measuring device as recited in claim 1, wherein the linearizing signal device is a capacitive circuit.

3. A tension measuring device, as recited in claim 1, wherein the linearizing signal device is a linear signal processor.

4. A tension measuring device, as recited in claim 1, wherein the elongated body comprises a beam having a hollow cross-section.

5. A tension measuring device, as recited in claim 4, wherein the strain gauge bridge further comprises another strain gauge mounted on a second inside wall of the elongated further comprises another strain gauge mounted on a second inside wall of the elongated housing, the second inside wall being opposite the fist inside wall of the elongated housing.

6. A tension measuring device, as recited in claim 5, wherein the strain gauge bridge measures tension and compression.

7. A tension measuring device, as recited in claim 1, wherein the strain gauge bridge measures both tension and compression of the elongated body caused by tension on the line.

8. A tension measuring device, as recited in claim 7, wherein the strain gage bridge comprises a pair of strain gages positioned on an inner surface of the elongated body and wherein the strain gage is applied directly to bending of the elongated body.

9. A tension measuring device, as recited in claim 7, wherein the linearizing signal device is positioned within the hollow cross-section of the elongated body.

10. A tension measuring device, as recited in claim 1, wherein the strain gauges are positioned equidistant from a center of the elongated body.

13. A system, as recited in claim 1, wherein the linearizing signal device is a linear signal processor.

22. The system of claim 9 wherein the strain gauge elements are temperature compensated.

25. A tension measuring device, as recited in claim 1, wherein the strain gauge elements are temperature compensating.

11. A system for measuring tension on a wireline comprising:

(a) tension measuring device mounted on the wireline between the wireline load and anchor ends including;

(i) an elongated body having two ends, said elongated body further comprising a hollow interior comprising a first interior wall and a second interior wall, wherein the first interior wall and the second interior wall oppose each other;

(ii) a deflection block secured to each end of the elongated body for holding the wireline spaced apart from the elongated body;

(iii) a clamping mechanism between the deflection blocks for clamping the wireline to the elongated body wherein increased tension in the wireline will bend the elongated body; and

(iv) a first strain gauge element attached to the first interior wall and a second strain gauge element attached to the second interior wall, wherein the first strain gauge produces an output signal proportional to the bending tension of the elongated body and the second strain gauge element produces an output signal proportional to the compression of the second interior wall;

(b) a linearizing signal device connected to the first and second strain gauge elements for processing the output signal and for providing a readable output representative of the tension on the wireline; and

(c) a wireline tension readout device adapted to receive and display the readable output representative of the tension on the wireline.

12. A system, as recited in claim 11, wherein the linearizing signal device is a capacitive circuit.

14. A system, as recited in claim 11, wherein the elongated body is a beam having a center bore.

15. A system, as recited in claim 14, wherein the strain gage is positioned on an inner surface of the elongated body and wherein the strain gage element is applied directly to the bending of the elongated body.

16. A system, as recited in claim 11, wherein the linearizing signal device is positioned within the hollow cross-section the elongated body.

17. A system, as recited in claim 11, wherein the deflection blocks are positioned equidistant from a center of the elongated body.

23. The system of claim 16 wherein the strain gauge elements are temperature compensated.

18. A tension measuring device for providing an indication of tension in a wireline comprising:

(a) a beam having two ends and a hollow cross-section;

(b) a deflection block secured to each end of the beam and positioned equidistant from a center of the beam for holding the wireline spaced apart from the beam;

(c) a clamping mechanism between the deflection blocks for clamping the wireline to the bean wherein increased tension in the wireline will bend the beam;

(d) a strain gauge bridge applied directly to the bending of the beam and positioned on opposing inner surfaces of the beam for producing output signals proportional to the bending tension and compression of the beam; and

(e) a capacitive circuit positioned within the hollow cross-section of the beam and connected to the strain gauge bridge for processing the output signals and for providing a linearized readable output representative of the tension on the wireline.

19. A tension measuring device, as recited in claim 18, further comprising:

(a) a readout device adapted to receive and display the linearized readable output.

24. The system of claim 18 wherein the strain gauge elements are temperature compensated.

20. A tension measuring device for providing an indication of tension in a wireline comprising:

(a) a beam having two ends and a hollow cross-section;

(b) a deflection block secured to each end of the beam and positioned equidistant from a center of the beam for holding the wireline spaced apart from the beam;

(c) a clamping mechanism between the deflection blocks for clamping the wireline to the beam wherein increased tension in the wireline will bend the beam;

(d) a strain gauge bridge applied directly to the bending of the beam and positioned on opposing inner surfaces of the beam for producing output signals proportional to the bending tension and compression of the inner surfaces of the beam; and

(e) a linear signal processor positioned within the hollow cross-section of the beam and connected to the strain gauge bridge for processing the output signals and for providing a linearized readable output representative of the tension on the wireline.

21. A tension measuring device, as recited in claim 20, further comprising:

(a) a readout device adapted to receive and display the linearized readable output.