Method and Device for Detecting Crack Formation in a Hoisting Member

• US 20130241736A1
• Filed: 10/17/2011
• Published: 09/19/2013
• Est. Priority Date: 10/16/2010
• Status: Active Grant

• Current Assignee: Stinis Beheer B.V.
• Original Assignee: Stinis Beheer B.V.
• Inventors: Stinis, Cornelis
• Granted Patent: US 9,257,031 B2
• Time in Patent Office: Days
• US Class Current: 340/665
• CPC Class Codes: G01L 1/246 using integrated gratings, e.g. Bragg gratings
• CPC Class Codes: G01L 5/101 using sensors inserted into the flexible member
• CPC Class Codes: G01L 5/105 using electro-optical means
• CPC Class Codes: G01M 11/086 Details about the embedment of the optical fiber within the DUT
• CPC Class Codes: G01M 5/0041 by determining deflection or stress
• CPC Class Codes: G08B 21/182 Level alarms, e.g. alarms responsive to variables exceeding a threshold

Abstract

The invention relates to a method for detecting crack formation in a hoisting member, comprising the steps of measuring a stress under load at two points of the hoisting member, comparing the measured stresses and generating a warning signal when the measured stresses differ too much from each other.

The invention also relates to a device for detecting crack formation in a hoisting member, comprising means arranged at two points of the hoisting member for measuring a stress under load, means connected to the measuring means for comparing the measured stresses, and means connected to the comparing means for generating a warning signal when the measured stresses differ too much from each other.

Finally, the invention relates to a hoisting frame, comprising a number of hoisting members which are mounted thereon close to its corners, and crack detection devices connected thereto.

Claims

1. A method for detecting crack formation in a hoisting member, comprising the steps of:

measuring a stress under load at least at two points of the hoisting member,

comparing the measured stresses, and

generating a warning signal when the measured stresses differ too much from each other.

2. The method for detecting crack formation in a hoisting member as claimed in claim 1, characterized in that the stress at each point is measured by measuring a corresponding deformation at that point.

3. The method for detecting crack formation in a hoisting member as claimed in claim 2, characterized in that a first deformation is measured at a relatively lightly loaded point of the hoisting member and a second deformation is measured at a relatively heavily loaded point of the hoisting member.

4. The method for detecting crack formation in a hoisting member as claimed in claim 3, characterized in that the first deformation is measured in a shaft of the hoisting member and the second deformation is measured close to an outer end of the hoisting member attached to a hoisting frame.

5. The method for detecting crack formation in a hoisting member as claimed in claim 4, characterized in that the hoisting member is mounted on the hoisting frame by means of a screw connection and the second deformation is measured close to a relatively heavily loaded screw thread.

6. The method for detecting crack formation in a hoisting member as claimed in claim 4, characterized in that the hoisting member is mounted on the hoisting frame by means of a collar and the second deformation is measured close to the collar.

7. The method for detecting crack formation in a hoisting member as claimed in claim 4, characterized in that the hoisting member is mounted on the hoisting frame by means of a double collar, the second deformation is measured close to one of the collars and a third deformation is measured close to the other collar, which third deformation is likewise compared to the first deformation.

8. The method for detecting crack formation in a hoisting member as claimed claim 2, characterized in that the deformations are measured optically.

9. A crack detection device for detecting crack formation in a hoisting member, comprising:

measuring means arranged at least at two points of the hoisting member for measuring a stress under load,

comparing means connected to the measuring means for comparing the measured stresses, and

warning signal-generating means connected to the comparing means for generating a warning signal when the measured stresses differ too much from each other.

10. The crack detection device as claimed in claim 9, characterized in that the measuring means are adapted to measure a deformation corresponding to the stress.

11. The crack detection device as claimed in claim 9, characterized in that the measuring means comprises first measuring means arranged at a relatively lightly loaded point of the hoisting member and second measuring means arranged at a relatively heavily loaded point of the hoisting member.

12. The crack detection device as claimed in claim 11, characterized in that the first measuring means are arranged in a shaft of the hoisting member and the second measuring means are arranged close to an outer end of the hoisting member attached to a hoisting frame.

13. The crack detection device as claimed in claim 11, characterized in that the hoisting member is mounted on the hoisting frame by means of a screw connection and the second measuring means are arranged close to a relatively heavily loaded screw thread.

14. The crack detection device as claimed in claim 11, characterized in that the hoisting member is mounted on the hoisting frame by means of a collar and the second measuring means are arranged close to the collar.

15. The crack detection device as claimed in claim 11, characterized in that the hoisting member is mounted on the hoisting frame by means of a double collar, the second measuring means are arranged close to one of the collars and a third measuring means are arranged close to the other collar, wherein the comparing means are adapted to compare a measurement of the third measuring means to a measurement of the first measuring means.

16. The crack detection device as claimed in claim 10, characterized in that the measuring means comprise optical measuring members.

17. The crack detection device as claimed in claim 16, characterized in that the measuring means comprise an optical fibre which is connected to the hoisting member and the deformation of which can be measured optically.

18. The crack detection device as claimed in claim 17 characterized in that the different measuring means comprise a shared optical fibre extending along the relevant measuring points.

19. The crack detection device as claimed in claim 17 characterized in that the optical fibre has in the vicinity of the measuring points processed parts which generate a specific light reflection.

20. The crack detection device as claimed in claim 17, characterized in that the optical fibre is received in a bore in the hoisting member.

21. The crack detection device as claimed in claim 20, characterized in that the bore is formed in the vicinity of a central axis of the hoisting member.

22. The crack detection device as claimed in claim 9, characterized in that the warning signal-generating means are arranged on a hoisting frame on which the hoisting member is mounted.

23. A hoisting frame assembly, comprising:

a hoisting frame having corners,

a plurality of hoisting members which are mounted on the hoisting frame close to the corners of the hoisting frame, and

crack detection devices connected to the hoisting members for detecting crack formation in the hoisting members, each crack detection device comprising;

measuring means arranged at least at two points of one of the hoisting members for measuring a stress under load at each of the two points,

comparing means connected to the measuring means for comparing the measured stresses, and

means connected to the comparing means for generating a warning signal when the measured stresses differ too much from each other.