Fixing member with a recess at the end of its threaded shank, a male element, a handling tool and a gauge comprising such a male element

1. A fixing member extending along an axis of symmetry comprising a threaded end, one end face of which contains a recess, said recess comprising a peripheral edge in the form of a multilobed continuous curved line, characterised in that the cross-section of each lobe is defined by a continuous series of three arcs of a circle, i.e. a first convex arc of a circle with a first radius, on either side of which a second concave arc of a circle with a second radius are positioned, and in that each lobe is connected to the adjacent lobe via a third convex arc of a circle with a third radius larger than the first radius.

2. A fixing member according to claim 1 , characterised in that the peripheral edge of the recess is inscribed in a circle centred around the axis of symmetry and in that the ratio between the diameter of the thread base of the threaded end and the diameter (D 1 ) of the circle of inscription is between approximately 1.32 and approximately 1.72.

3. A fixing member according to claim 2 , characterised in that the recess comprises a central cylindrical hollow the diameter (D 3 , D3 u ) of which is equal to twice the third radius and in that the ratio between the diameter (D 3 , D 3u ) of the central cylindrical hollow and the diameter of the circle of inscription is between approximately 0.63 and approximately 0.88.

4. A fixing member according to claim 3 , characterised in that the first radius (R 1 ) is defined by the formula:

R 1 =½×( D 1 +D 3,3u )×λ,

D 1 being the diameter of the circle of inscription,

D 3,3u being the diameter of the central cylindrical hollow

λ being a coefficient between approximately 0.06 and approximately 0.26.

5. A fixing member according to claim 4 , characterised in that the ratio between the second radius and the first radius (R 1 ) is between approximately 0.66 and approximately 1.06.

6. A fixing member according to claim 1 , characterised in that the peripheral edge of the recess comprises 3 to 7 lobes.

7. A testing gauge capable of testing at least one dimension of a recess of a fixing member according to claim 1 , characterised in that it comprises a grippable body with at least two ends, and in that a first end is fitted with a male element capable of being inserted into a recess, complementary in shape, of a fixing member, with a raised shape comprising a peripheral edge in the form of a multilobed continuous curved line, characterised in that the cross-section of each lobe is defined by a continuous series of three arcs of a circle, i.e. a first convex arc of a circle with a first radius on either side of which a second concave arc of a circle with a second radius are positioned, and in that each lobe is connected to the adjacent lobe via a third convex arc of a circle with a third radius larger than the first radius.

8. A testing gauge according to claim 7 , characterised in that it comprises a second male element at another end, with a circular cross-section chosen so as to have a radius larger than the third radius of the recess.

9. A testing gauge according to claim 7 , characterised in that it comprises a third multilobed male element at another end, the cross-section of each lobe peak being formed by a convex arc of a circle with a radius larger than the first radius of the recess being checked, the third male element being inscribed in a circle with a larger diameter than the circle of inscription of the recess.

10. A testing gauge according to claim 7 , characterised in that it comprises a fourth multilobed male element at another end, the cross-section of each lobe peak being formed by a convex arc of a circle with a radius smaller than the first radius of the recess being checked, the fourth male element being inscribed in a circle with the same diameter as the circle of inscription of the recess.

11. A testing gauge according to claim 7 , characterised in that it comprises at least one conformity or non-conformity indicator for the recess being checked, positioned near to the first or another end.

12. A male element capable of being inserted into a recess, complementary in shape, of a fixing member, with a raised shape comprising a peripheral edge in the form of a multilobed continuous curved line, characterised in that the cross-section of each lobe is defined by a continuous series of three arcs of a circle, i.e. a first convex arc of a circle with a first radius (R 38 ), on either side of which a second concave arc of a circle with a second radius (R 40 ) are positioned, and in that each lobe is connected to the adjacent lobe via a third convex arc of a circle with a third radius (R 42 ) larger than the first radius (R 38 ).

13. A male element according to claim 12 , characterised in that it comprises a central cylindrical section with a diameter (D 42 ) equal to twice the third radius (R 42 ), and in that it is inscribed in a circle tangent to the lobes and with a predefined diameter (D 44 ) so that the ratio between the diameter (D 42 ) of the central cylindrical section and the predefined diameter (D 44 ) of the circle of inscription is between approximately 0.63 and approximately 0.88.

14. A male element according to claim 13 , characterised in that the first radius (R 38 ) is defined by the formula:

R 38 =½×( D 42 +D 44 )×λ,

D 44 being the predefined diameter of the circle of inscription,

D 42 being the diameter of the central cylindrical hollow,

λ being a coefficient of between approximately 0.06 and approximately 0.26.

15. A male element according to claim 14 , characterised in that the ratio between the second radius (R 40 ) and the first radius (R 38 ) is between approximately 0.66 and approximately 1.06.

16. A male element according to claim 12 , characterised in that the peripheral edge of the raised form comprises 3 to 7 lobes.

17. A handling tool comprising a tip capable of being inserted into a recess of a fixing member, characterised in that the tip has an end comprising a male element according to one of claims 12 to 15 .