FR3100293A1 - Bolt equipped with a rotation locking system providing precise rotational immobilization - Google Patents

Abstract

Bolt equipped with a rotation locking system providing precise immobilization in rotation The invention relates to a bolt comprising: a screw (34) having a threaded rod, a longitudinal axis (A34), an oblong through hole (52) and oriented in the longitudinal direction, a nut (36) having a threaded hole, a tubular extension (54) provided with pairs of helical slots (56), a rotation locking system, configured to immobilize the nut (36) in rotation relative to the threaded rod, having a pin (50) and a locking ring (58), configured to be positioned around the tubular extension (54) in operation, comprising a first end face (72) configured to bear against a stop (66) of the nut (36) in operation and a plurality of notches (74) positioned at different distances from the first end face (72) and configured to immerse the pin (50) in translation in the direction longitu when the end face (72) is in contact with the stop (66) of the nut (36) in operation. This configuration allows to obtain a great precision for the immobilization of the nut relative to the screw. Figure 12

Description

Bolt equipped with a rotation locking system providing precise immobilization in rotation

The present application relates to a bolt equipped with a rotation locking system providing precise immobilization in rotation.

According to one embodiment illustrated by Figures 1 to 3, a bolt 10, used to assemble in a removable manner at least two parts 12.1, 12.2, comprises a screw 14 which has a threaded rod 14.1 and a head 14.2 connected to one end of the threaded rod 14.1 as well as a nut 16 which has a tapped hole 16.1 configured to allow the screwing of the threaded rod 14.1 of the screw 14.

To maintain a given tightening torque in operation, the bolt 10 comprises a rotation locking system. According to one embodiment, the nut 16 is a slotted nut and the rotation locking system comprises a pin 18 as well as a through hole 20 at the level of the threaded rod 14.1 which has a section identical to that of the pin 18. Slotted nut 16 comprises a tubular extension 22 which has longitudinal notches 24 (parallel to the axis of nut 16) delimiting slots 26.

In operation, the pin 18 is housed in two diametrically opposed longitudinal notches 24 and in the through hole 20 of the threaded rod 14.1 to immobilize the nut 16 in rotation relative to the screw 14.

This embodiment is not fully satisfactory because two longitudinal notches 24 are not necessarily arranged in the extension of the through hole 20 of the threaded rod 14.1 when the desired tightening torque is reached. Consequently, to set up the pin 18, it is necessary to pivot the nut 16 and to increase the tightening torque to make two longitudinal notches 24 coincide with the through hole 20. This increase in torque necessarily induces additional stresses on the bolt and/or on the assembled parts 12.1, 12.2.

Such a rotation locking system therefore provides a low level of precision for rotational immobilization. The number of longitudinal notches 24 being generally limited to six for the screw diameters most used in aeronautics, the nut 16 can be immobilized in rotation every 60°.

The present invention aims to remedy all or part of the drawbacks of the prior art.

To this end, the subject of the invention is a bolt comprising a screw having a threaded rod and a longitudinal axis, a nut having a tapped hole and a tubular extension provided with pairs of slots as well as a rotation locking system, configured to immobilize the nut in rotation relative to the threaded rod, having a pin and a through hole in the threaded rod.

According to the invention, the through hole of the threaded rod is oblong and oriented in the longitudinal direction, the slots of the tubular extension being helical, distributed over the entire circumference of the tubular extension, the first and second helical slots of the same pair comprising diametrically opposed portions configured to receive the pin. In addition, the rotation blocking system comprises a blocking ring, configured to be positioned around the tubular extension in operation, comprising a first end face configured to bear against an abutment of the nut in operation and a plurality of notches positioned at different distances from the first end face and configured to house the pin in translation in the longitudinal direction when the end face is in contact with the abutment of the nut in operation.

The spacing in the longitudinal direction between two successive notches being minimal, of the order of a tenth of a millimeter, the locking system provides angular precision, of the order of 5°, to immobilize the nut in rotation with respect to the opinion.

According to another characteristic, the locking ring comprises at least one series of notches, the notches of the same series being angularly offset from each other over at least part of the circumference of the locking ring, the distance between each notch and the first end face gradually increasing from one notch to another in the series.

According to another characteristic, the locking ring comprises two series which extend over the entire circumference of the locking ring, the notches of the two series being arranged so that a first notch of a first series and a second notch of a second series diametrically opposed to the first notch are separated from the first end face by the same distance.

According to another characteristic, the bolt comprises at least one system for locking the locking ring in rotation with respect to the screw and/or the nut in operation.

According to another characteristic, the system for locking the locking ring in rotation comprises the pin and, for each notch, a hollow shape configured to accommodate a section of the pin.

According to another characteristic, the hollow shape is half-cylindrical and has a diameter substantially equal to the diameter of the pin.

According to a first embodiment, the locking ring comprises a second end face, opposite the first end face, which has the plurality of notches.

According to a second embodiment, the locking ring comprises a plurality of passage orifices each having a first edge, closest to the first end face, which forms one of the notches.

Other characteristics and advantages will emerge from the description of the invention which follows, description given by way of example only, with regard to the appended drawings, among which:

is a perspective view of a bolt which illustrates an embodiment of the prior art,

is a perspective view of a castellated nut which illustrates an embodiment of the prior art,

is a perspective view of a screw which illustrates an embodiment of the prior art,

is a perspective view of a screw which illustrates one embodiment of the invention,

is a perspective view of a nut which illustrates one embodiment of the invention,

is a side view of a screw which illustrates one embodiment of the invention,

is a side view of a nut which illustrates one embodiment of the invention,

is a side view of a partially assembled bolt, without a locking ring, which illustrates one embodiment of the invention,

is a perspective view of a locking ring which illustrates a first embodiment of the invention,

is a perspective view of a locking ring which illustrates a second embodiment of the invention,

is a perspective view of the locking ring, visible in Figure 9, mounted on a nut, and

is a side view of a bolt locked with a locking ring which illustrates one embodiment of the invention.

In Figure 12, there is shown a bolt 30 for maintaining at least two parts 32.1, 32.2 assembled. This bolt 30 comprises a screw 34, a nut 36 and a rotation locking system 38.

According to one embodiment visible in particular in Figures 4 and 6, the screw 34 comprises a threaded rod 40 and a head 42 positioned at one end of the threaded rod 40. According to one configuration, the head 42 has a hexagonal section. Of course, the invention is not limited to this configuration. At a minimum, the screw 34 comprises a threaded rod 40, the head 42 being replaced by a nut or the threaded rod 40 which can be screwed directly into one of the parts to be assembled, like a stud. The threaded rod 40 includes an end face 44 from which the nut 36 is screwed.

The screw 34 has a longitudinal axis A34 which corresponds to the axis of the threaded rod 40. For the present application, a longitudinal direction is parallel to the longitudinal axis A34, a longitudinal plane passes through the longitudinal axis A34 and a plane transverse is perpendicular to the longitudinal axis A34.

According to one embodiment visible in Figures 5 and 7, the nut 36 comprises a body 46, delimited by first and second parallel faces 46.1, 46.2, as well as a tapped hole 48, passing through the body 46, having an axis substantially perpendicular to the first and second faces 46.1, 46.2. According to one configuration, the body 46 has a hexagonal section to be able to screw it. Of course, the invention is not limited to this shape for the nut 36.

The rotation locking system 38 is configured to immobilize the nut 36 in rotation with respect to the threaded rod 40 of the screw 34. It comprises a pin 50 (visible in FIGS. 8 and 12), a through hole 52 in the threaded rod 40 of screw 34, a tubular extension 54 integral with nut 36 and having at least a pair of helical slots 56 as well as a locking ring 58.

Pin 50 has a section with a diameter D50. This pin is not further detailed as it may be the same as the prior art.

According to a feature of the invention, the through hole 52 has an oblong shape and extends in the longitudinal direction between first and second ends 52.1, 52.2. Thus, the through hole 52 oblong is positioned in a longitudinal plane and opens via openings 60 diametrically opposed. This oblong through hole 52 has a length L52 (dimension taken in the longitudinal direction) corresponding to the distance separating the first and second ends 52.1, 52.2 as well as a width E52 (dimension taken in a transverse plane) equal to or very slightly greater than the diameter D50 of the pin 50. According to one configuration, the first end 52.1 of the oblong through-hole 52, closest to the end face 44 of the screw 34, is spaced from said end face 44. According to another configuration, the through hole 52 opens at the level of the end face 44 of the screw 34.

The tubular extension 54 has a first end 54.1, connected to the first face 46.1 of the body 46 of the nut 36, and a second free end 54.2. The tubular extension 54 is coaxial with the tapped hole 48 of the nut 36 and has cylindrical inner and outer faces 62, 64, concentric and coaxial with the tapped hole 48 of the nut 36.

The inner face 62 has a diameter equal to or very slightly greater than that of the threaded hole 48 of the nut 36. If the inner face 62 has a diameter equal to that of the threaded hole of the nut 36 then the inner face 62 is threaded . If inner face 62 has a larger diameter than the threaded hole in nut 36 then inner face 62 may be smooth.

The outer face 64 has a diameter such that at least part of the first face 46.1 of the body 46 of the nut 36 projects relative to said outer face 64 so as to form a stop 66 for the locking ring 58 Whatever the embodiment, the nut 36 comprises at least one abutment 66 configured to immobilize the locking abutment 58 in translation in the longitudinal direction. According to the example visible in Figures 8 and 12, the first face 46.1 of the body 46 of the nut 36 provides the stop function 66. Of course, the invention is not limited to this configuration.

When the body 46 has a hexagonal section, the diameter of the outer face 64 is less than or equal to the inscribed circle of the hexagonal section of the body 46 to allow the use of a socket during screwing and unscrewing operations.

The helical slots 56 each have a width E56 equal to or very slightly greater than the diameter D50 of the pin 50. The first and second helical slots 56 of the same pair comprise diametrically opposite portions configured to receive the pin 50 in n' any blocking position.

All the helical slots 56 all have the same length L56, are regularly distributed over the circumference of the tubular extension 54 and form the same angle with a transverse plane.

The helical slots 56 are angled approximately the same as the thread pitch of the threaded rod 40. In one configuration, the helical slots 56 form with a transverse plane an angle slightly greater than that of the thread pitch of the threaded rod 40 .

Each helical slot 56 has a first end 56.1 close to the first end 54.1 of the tubular extension 54 and a second end 56.2 close to the second end 54.2 of the tubular extension 54.

The first ends 56.1 of all the helical slots 56 are all arranged in the same first transverse plane P1 and the second ends 56.2 of all the helical slots 56 are all arranged in the same second transverse plane P2.

The helical slots 56 are distributed over the entire circumference of the tubular extension 54. Thus, at least a portion of a first helical slot 56 is arranged in the same longitudinal plane as a portion of a second helical slot 56' adjacent to the first helical slot 56.

The number of pairs of helical slots 56 may vary from nut to nut. The nut 36 visible in Figure 5 comprises three pairs of helical slots 56.

The length L52 of the oblong through hole 52 of the screw 34 and the length L56 of the helical slots 56 of the nut 36 are adjusted so that in operation, the first transverse plane P1 of the first ends 56.1 and/or the second transverse plane P2 of the second ends 56.2 of the helical slots 56 are positioned between the first and second ends 52.1, 52.2 of the oblong through-hole 52 of the screw 34.

According to the invention, it is always possible to insert the pin 50 in a first helical slot 56 of the nut 36, in the through hole 52 of the screw 34 and in a second helical slot 56 of the nut 56 , whatever the angular position of the nut 36 with respect to the screw 34.

The locking ring 58 is configured to be positioned around the tubular extension 54 and comprises inner and outer faces 68, 70 cylindrical and concentric, a first end face 72 configured to come into abutment in operation against the stop 66 of the nut 36 as well as a plurality of notches 74, offset relative to each other on the circumference of the locking ring 58, positioned at different distances from the first end face 72 and configured to secure the pin 50 in translation in the longitudinal direction . Each notch 74 connects the inner and outer faces 68, 70. It is configured to receive part of the pin 50.

Thus, when the desired tightening torque is reached, the locking ring 58 is positioned so that the first end face 72 is in contact against the abutment 66 of the nut 36 and that the pin 50 is in contact with at least one of the 74 notches.

Given the orientation of the helical slots 56 and the thread pitch of the threaded rod 40, when the nut 36 tends to unscrew, the pin 50 tends to approach the first ends 56.1 of the helical slots 56 and to translate in the longitudinal direction in the direction of the abutment 66 of the nut 36. The pin 50 being immobilized in translation in the longitudinal direction by one of the notches 74 of the locking ring 58, the nut 36 cannot unscrew.

According to one configuration, the locking ring 58 comprises at least one series 76 of notches 74, the notches 74 of the same series being angularly offset from each other over at least part of the circumference of the locking ring 58 , the distance between each notch 74 and the first end face 72 gradually increasing from one notch to another in the series. Thus, the spacing in the longitudinal direction between two successive notches 74 of the same series is substantially constant.

According to a configuration visible in Figures 9 and 10, the locking ring 58 comprises two series 76, 76' of notches. According to one embodiment, the locking ring 58 comprises two series 76, 76' which extend over its entire circumference. In this case, the notches 74 of the two series 76, 76' are arranged so that a first notch 74 of a first series 76 and a second notch 74 of a second series 76', diametrically opposite the first notch 74, are separated from the first end face 72 by the same distance. Thus, the pin 50 is in contact with two notches 74 diametrically opposed.

According to another characteristic, the bolt 30 comprises at least one system for locking the locking ring 58 in rotation with respect to the screw 34 and/or the nut 36 in operation.

According to one configuration, the rotation locking system of the locking ring 58 comprises the pin 50 and, for each notch 74, a hollow shape 78 configured to house a section of the pin 50. According to one embodiment, the hollow shape 78 is semi-cylindrical and has a diameter substantially equal to the diameter D50 of the pin 50.

According to a first embodiment visible in Figures 9 and 11, the locking ring 58 comprises a second end face 80, opposite the first face 72, which has the plurality of notches 74.

According to this first embodiment, the locking ring 58 is positioned around the tubular extension 54. When the desired tightening torque is reached, the locking ring 58, in contact with the stop 66 of the nut 36, is pivoted until 'that two diametrically opposed notches 74 are positioned just below the two overlapping zones, diametrically opposed to the oblong through hole 52 of the screw 34, and the two helical slots 56 of the nut 36. The pin 50 is then inserted into a first helical slot 56 of the nut 36, into the through hole 52 of the screw 34 and into a second helical slot 56 of the nut 36. From then on, the pin 50 is immobilized against two notches 74 diametrically opposed, which immobilize it in translation in the longitudinal direction, and prevent the unscrewing of the nut 36.

According to a second embodiment visible in Figure 10, the locking ring 58 comprises a second end face 80 parallel to the first end face 72 and a plurality of through holes 82, connecting the inner and outer faces 68, 70, having a width E82 substantially equal to or very slightly greater than the diameter D50 of the pin 50. According to this second embodiment, each passage orifice 82 has a first edge, closest to the first end face 72, which forms one of the notches 74. Each passage orifice 82 has an oblong shape, the length of which is equal to the diameter D50 of the pin 50 increased by the spacing in the longitudinal direction between two successive notches 74.

According to this second embodiment, the locking ring 58 is positioned around the tubular extension 54. When the desired tightening torque is reached, the locking ring 58 is pivoted around the tubular extension 54, its first end face 72 being in contact with the stop 66 of the nut 36, until two passage orifices 82, diametrically opposed, coincide with the through orifice 52 of the screw 34 and two helical slots 56 of the nut 36. If several pairs of orifices 82 are possible, the pair which minimizes the distance between the pin 50 and the edge of the passage orifices 82 closest to the first end face 72 is chosen. The pin 50 is then inserted into a first passage hole 82 of the locking ring 58, a first helical slot 56 of the nut 36, the through hole 52 of the screw 34, a second helical slot 56 of the nut 36 and a second passage orifice 82 of the locking ring 58. Consequently, the nut 36 is immobilized in rotation with respect to the screw 34.

Whatever the embodiment, the angular precision of the immobilization rotation depends on the spacing in the longitudinal direction between two successive notches 74. This spacing can be minimal, of the order of a tenth of a millimeter, so that it is possible to obtain an angular precision of the order of 5°, much less than a precision of 60° in the case of a castle nut with six longitudinal notches.

Claims (8)

Bolt comprising a screw (34) having a threaded rod (40) and a longitudinal axis (A34), a nut (36) having a tapped hole (48), a tubular extension (54) provided with pairs of slots (56) as well a rotation locking system, configured to immobilize the nut (36) in rotation relative to the threaded rod (40), having a pin (50) and a through hole (52) in the threaded rod (40) , characterized in that the through hole (52) of the threaded rod (40) is oblong and oriented in the longitudinal direction, in that the slots (56) of the tubular extension (54) are helical and distributed over the entire circumference of the tubular extension (54), the first and second helical slots (56) of the same pair comprising diametrically opposite portions configured to receive the pin (50) and in that the rotation locking system comprises a locking ring (58) configured to be positioned around the tubular extension (54) in operation, comprising a first end face (72) configured to bear against an abutment (66) of the nut (36) in operation and a plurality of notches (74) positioned at different distances from the first end face (72) and configured to immobilize the pin (50) in translation in the longitudinal direction when the end face (72) is in contact with the abutment (66) of the nut (36) in operation. Bolt according to Claim 1, characterized in that the locking ring (58) comprises at least one series (76) of notches (74), the notches (74) of the same series being angularly offset from each other over at least part of the circumference of the locking ring (58), the distance between each notch (74) and the first end face (72) gradually increasing from one notch to another in the series. Bolt according to the preceding claim, characterized in that the locking ring (58) comprises two series (76, 76', 76'') which extend over the entire circumference of the locking ring (58), the notches ( 74) of the two series (76, 76', 76'') being arranged so that a first notch (74) of a first series (76) and a second notch (74) of a second series (76' ), diametrically opposite the first notch (74), are separated from the first end face (72) by the same distance. Bolt according to one of the preceding claims, characterized in that the bolt (30) comprises at least one system for locking the locking ring (58) in rotation with respect to the screw (34) and/or to the nut (36) in operation. Bolt according to the preceding claim, characterized in that the rotation locking system of the locking ring (58) comprises the pin (50) and, for each notch (74), a recessed form (78) configured to house a section of the hairpin (50). Bolt according to the preceding claim, characterized in that the recessed shape (78) is semi-cylindrical and has a diameter substantially equal to the diameter (D50) of the pin (50). Bolt according to one of the preceding claims, characterized in that the locking ring (58) comprises a second end face (80), opposite the first face (72), which has the plurality of notches (74). Bolt according to one of Claims 1 to 6, characterized in that the locking ring (58) comprises a plurality of passage orifices (82) each having a first edge, the closest to the first end face (72) , which forms one of the notches (74).