Of

John D. Davis For

DUAL ACTUATED JACKSCREW NUT AND/OR BOLT HEAD WITH INTERLOCKED LOAD WASHER AND JACKSCREW ACTUATED LOCK

WASHER STACK

PRIORITY CLAIM

The present invention claims priority to and from US Patent Applications 13/898,674 titled "Dual Actuated Jackscrew Nut And/Or Bolt Head" filed May/21 /2013, 13/898,689 titled "Nut And/Or Bolt Head With Jackscrew Actuated Lock Washer Stack" filed on May/21 /2013 and 14/283,198 titled "Dual Actuated Nut And/Or Bolt Head With Reversed Thinned Jackscrews And Washer/Nut Castle Interlock" filed May/20/2014, all of the same above inventor.

FIELD OF INVENTION

The present invention relates to jackscrew nuts and bolt heads and their assemblies with jackscrew actuated position locking.

BACKGROUND OF INVENTION

Jackscrew nuts and bolt heads circumvent the need for high power torque wrenches, especially with larger bolt diameters. Instead of having to tighten one nut or bolt head with high torque and big tool to bring the respective central thread connection to the required load, a number of circular arrayed jackscrews that are screwed in the nut and/or bolt head are sequentially tightened with comparatively low torques requiring only comparatively small tools.

The actuation of Prior Art nut and/or bolt head via jackscrews alone requires their extensive repetitive actuation. Since a substantial portion of the overall loading requires only relatively low tightening torque, a dual actuation via the nut and/or bolt head directly for low loading and via the jackscrews for final loading is desire able. The present invention addresses this need.

During final tightening of Prior Art jackscrews, contact pressures of the jackscrew bottom cause galing, which increases friction in the interface. The jackscrews are also forced out of their natural assembly direction due to thread tolerances and elastic deformations. This causes edge contact of the jackscrew bottom, which increases local peak stresses and galing even more. Prior Art jackscrew bottoms may be spherical against edge contacting but are pressing against a planar surface, which causes again high peak stresses and galing. Therefore, there exists a need for a nut and/or bolt head jackscrew assembly incorporating a bottom washer with spherical faces that are held in alignment with spherical jackscrew bottoms. The present invention addresses also this need.

It is a common need to secure a nut and/or bolt against inadvertent loosening. This also applies for jackscrew nuts and bolts, which require special consideration on one hand because of the stress concentrations induced by jackscrew bottoms. On the other hand and in the case of the present invention, dual actuated jackscrew nuts and bolts provide for separated primary and secondary tightening and loosening actuation via the main body and via the jackscrews, which may be advantageously utilized to selectively lock and unlock washers. Therefore, there exists a need for a jackscrew nut and/or bolt tightening assembly including a correspondingly configured lock washer and/or lock washer stack. The present invention addresses also this need. SUMMARY

A jackscrew nut and/or bolt head assembly includes a circumferentially and radial interlocked load washer at the bottom of the assembly. Spherical faces at the washer top are thereby held in alignment with corresponding spherical jackscrew bottoms. The spherical-to-spherical jackscrew-washer interface assures evenly distributed contact pressures during out of angle elastic jackscrew displacement and minimizes galing.

The circumferential and radial interlocked load washer provides further for a transfer of a primary torque exerted onto the main body of the nut and/or bolt head via an assembly torque access, which may be a standardized outside spline such as well known triple square, twelve spline or may be a number of axially extending interlock pins that partially extend radial beyond a circumference and below the bottom of the main body.

The assembly torque access may be incorporated at the top and/or circumference of the nut and/or bolt head. In case it is incorporated at the circumference, the assembly torque access may also be incorporated into the load washer in a fashion such that the load washer and nut and/or bolt head may have the primary torque concurrently applied. The washer interlock may be provided by mating splines, and/or the interlock pins and/or via jackscrew shafts that extend into recesses of the load washer.

The load washer may be part of a lock washer stack in which an additional lock washer is positioned below the load washer. In that case, only the load washer is in an interlock with the main body. The load washer may have a larger central hole diameter than the lock washer and a rim of the main body may extend through the central load washer hole and access a smooth bearing face at the lock washer top. During initial tightening via the main body and with loose jackscrews, the rim may slide on the bearing face and transfer the initial tightening load directly onto the load washer with low friction. During final tightening, the jackscrews are pressed against the load washer and force it to engage with the lock washer via a ratchet interface between them. The final set load is then transferred from the main body across the jackscrews onto the load washer and across the ratchet interface onto the lock washer thereby effectively locking the jackscrew nut and/or bolt. The ratchet interface may include a helical interface that has an interface pitch substantially larger than a thread pitch of the central thread and that has an interface pitch direction that is the same as thread pitch direction of the central thread. The helical interface may thereby effectively provide a rotational wedge lock against the main body becoming loose.

To unlock the jackscrew nut and/or bolt, the jackscrews may be initially loosened. In case of only a load washer employed, the preload is sufficiently reduced for the serrations to loose their bite. In case of a lock washer stack with ratchet interface and main body rim employed, the ratchet interface disengages and the main body rim comes again into contact with the lock washer bearing face. In case of the helical interface, sufficient clearance is established between jackscrews and load washer such that during a following loosening of the main body, sufficient axial suspension is established for the helical interface to slide unrestricted in wedging direction.

BRIEF DESCRIPTION OF THE FIGURES Fig. 1 is a front perspective view of a first embodiment in a nut configuration. Fig. 2 is a partial cut view of Fig. 1.

Fig. 3 is a bottom perspective view of a partial assembly of Fig. 1.

Fig. 4 is a front perspective view of a second embodiment as a nut.

Fig. 5 is a front perspective partial cut view of a third embodiment of the invention in a bolt head configuration.

Fig. 6A is a front perspective cut view of a fourth embodiment as a nut.

Fig. 6B is a jackscrew of Fig. 6A.

Fig. 7A is a front perspective cut view of a fifth embodiment as a nut.

Fig. 7B is a top down perspective view of a load washer of Figs. 7A.

Fig. 7C is a bottom up perspective view of Fig. 7B.

Fig. 8A is a front perspective cut view of a sixth embodiment as a nut.

Fig. 8B is a top down perspective exploded view of a load washer stack of Fig. 8A.

Fig. 8C is a bottom up perspective exploded view of Fig. 8B. Fig. 9A is a front perspective cut view of a seventh embodiment as a nut. Fig. 9B is a top down perspective exploded view of a load washer stack of Fig. 9A.

Fig. 9C is a bottom up perspective exploded view of Fig. 9B.

DETAILED DESCRIPTION

A jackscrew tightening assembly 1000 may feature a central thread 1002 with a thread axis 1005. In case of the jackscrew tightening assembly 1000 being a nut, the central thread 1002 may be an internal thread. In case of the jackscrew tightening assembly 1000 being a bolt head, the central thread 1002 may be an external thread as shown in Fig. 5. Parts of the jackscrew tightening assembly 1000 are a main body 1008, jackscrews 1026, a load washer 1035 and a washer interlock 1044. The main body 1008 is extending radial outward with respect to the central thread 1002 as is well known for jackscrew nuts and/or bolts. The main body 1008 has a main top 1011 , a main bottom 1014 that is opposite the main top 1011 in axial direction with respect to the central thread axis 1005, through holes 1017 with a through hole axis 1020 that is in an offset to the central thread axis 1005, and a secondary thread 1023 at least along a portion of the through hole 1017. The jackscrews 1026 are extending through respective through holes 1017, and engaging via their jackscrew threads 1027 with the respective secondary threads 1023. The jackscrews 1026 have jackscrew heads 1029 facing away from the main bottom 1014 and spherical bottoms 1032 facing away from the main top 1011. The jackscrews 1026 are preferably arrayed in a number around the central thread 1002 such that upon even tightening of all jackscrews 1026 the axial sum of all their individually exerted axial loads is transferred onto the central thread 1002 in a balanced fashion via the main body 1008 as may be well appreciated by anyone skilled in the art.

The load washer 1035 is adjacent the main bottom 1014 and surrounding the central thread 1002. The load washer 1035 has a washer top 1038 that is facing the main bottom 1014 and a number of spherical faces 1041 that are formed into the washer top 1038. The spherical faces 1041 are matching their respective spherical bottoms 1032 and are in substantial axial alignment with them and rotationally symmetric with respect to the central thread axis 1005. The load washer 1035 is at least circumferentially but preferably also radial held with the main body 1008 via a washer interlock 1044. In the first, second and third embodiments of Figs. 1 - 5, the washer interlock 1044 includes a first interlock feature 1047 provided by the load washer 1035 and a second interlock feature 1050 that is at least circumferentially but preferably also radial mating the first interlock feature 1047 and that is part of the main body 1008 such that the spherical faces 1041 are held in alignment with respective spherical bottoms 1032. The first interlock feature 1047 may be an internal spline that is axially extending through a central through hole 1039 of the load washer 1035. The second interlock feature 1050 may be an external spline axially extending from the main bottom 1014. According to Figs 1 , 2, the second interlock feature 1050 may be a body contour 1062 axially extending from the main bottom 1014 towards the main top 1011 and the first interlock feature may be one or more protrusions axially extending above the washer top 1038.

Further part of the jackscrew tightening assembly 1000 may be an assembly torque access 1053 via which a primary torque may be externally applied to the jackscrew tightening assembly 1000. In the first, second, third, fifth, sixth and seventh embodiments, the assembly torque access 1053 may be part of at least one of the main body 1008 and the load washer 1035 such that the primary torque that is applied to at least one of the main body 1008 and the load washer 1035 is also applied via the washer interlock 1044 to one other of the main body 1008 and the load washer 1035 while the spherical bottoms 1032 remain in substantial axial alignment with their respective spherical faces 1041. The assembly torque access 1053 may be a body outside contour 1063 that at least in part corresponds to a well known twelve spline, triple square standard or the like. The body outside contour may also serve as the second interlock feature 1050. Part of the assembly torque access 1053 may also be a load washer contour 1065 that is axially substantially collinear with the body outside contour 1063 such that the primary torque may be concurrently applied to both the main body 1008 and the load washer 1035 with the same tool as may well appreciated by anyone skilled in the art.

According to Fig. 3, the assembly torque access 1053 may be a body top spline 1068 protruding from the main top 1011. The body top spline 1068 may have jackscrew access recesses 1071 that are radial recessed into it such that the jackscrew heads 1029 are accessible while the body top spline 1068 radial extends in between the jackscrew heads 1029.

Referring to Fig. 5, the main body 1008 and the load washer 1035 may be circumferentially and radial held together via bottom shafts 1074 of the jackscrews 1026 engaging with receptacles 1077 formed into the load washer 1035. Receptacle disks 1080 featuring the spherical faces 1041 may be placed inside and preferably at the bottom of the receptacles 1077. Their small size provides for a cost effective fabrication of them with superior hardness of at least their spherical faces 1041 , which may further reduce risk of galing in the interface as may be well appreciated by anyone skilled in the art. At the same time, the load washer 1035 may be fabricated from a less hard and brittle material making it less susceptible to cracking due to out of balance peak loading from the jackscrews 1026 as may also be well appreciated by anyone skilled in the art.

The bottom shafts 1074 may be accessed via the axial gap between the main body 1008 and the load washer 1035 by a hook tool 700 having a hook 702 corresponding to the diameter of the bottom shafts 1074. By use of the hook tool, the primary torque may be applied for initially tightening the main body 1008. The hook tool 700 provides torque transfer with only partial circumferential access to the main body 1008, which may be advantages in tight locations.

At least one of the jackscrews 1026, the load washer 1035, the main body and the receptacle disks 1080 may be permanently magnetic to assist in keeping the jackscrew tightening assembly 1000 together during its installation and handling. The through hole axes 1020 may be in an angle to the central thread axis 1005 such that the jackscrew heads 1029 are closer to the central thread axis 1005 than the spherical bottoms 1032. This may advantageously provide for a more centralized access to the jackscrew heads 1029 with a tightening tool, while at the same time keeping the most outward diameter of the main body 1008 to a minimum.

In case the load washer 1035 is configured as a well known lock washer with one directional serrations on its bottom or other features preventing the load washer 1035 from being rotated in loosening direction of the main body 1008, the jackscrews 1026 may be loosened to the extent that the bottom shafts 1074 disengage from the receptacles 1077 and the main body 1035 rests directly on the washer top 1038 prior to loosening the main body 1008. That way, the locking load washer 1035 may remain stationary while the main body 1035 slides on the washer top 1038. To provide still a gap for hook tool 700 access, the main body 1008 may have a central circular rim extending downward from the main bottom 1014.

Referring to Figs. 6A, 6B and a fourth embodiment of the invention, the main body 1008 features top guide holes 1022 that are extending from the main top 1011 concentric with respect to their through hole axes 1020. The secondary threads 1023 are adjacent and below the top guide holes 1022 and concentric with respect to their respective top guide hole 1022. Recessed into the main bottom 1014 are a number of castle recesses 1058 and preferably circumferentially evenly arrayed. Bottom guide holes 1024 are extending from the main bottom 1014 and are also concentric with their respective top guide holes 1022. The jackscrews of the fourth embodiment have preferably each a top guide shaft 1072 in addition to the bottom guide shaft 1074. Each top guide shaft 1072 is adjacent the jackscrew head 1029 and in between the jackscrew head 1029 and the spherical bottom 1032. The top guide shafts 1072 are guided in respective top guide holes 1022.

In the fourth embodiment, the first interlock feature 1047 includes a number of castle extensions 1057 that extend by the castle height CLH above the washer top 1038. The second interlock feature 1050 includes correspondingly shaped castle recesses 1058 that recessed into the main bottom 1014. Castle guide holes 1078 are recessed into the castle extensions 1057 and have spherical faces 1041 formed at their bottom preferably horizontally leveled with those spherical faces 1041 that are formed into the washer top 1038. While the load washer 1035 is in mating contact with the main body 1008, the castle extensions 1057 are interlocking with the castle recesses 1058 axially with respect to the central thread axis 1005. The bottom guide shafts 1074 are preferably guided circumferentially alternating in either the bottom guide holes 1024 or the castle guide holes 1078. The bottom guide shaft 1074 has a bottom diameter BD that is preferably larger than the jackscrew thread 1027 diameter THD. The top guide shaft 1072 has a top diameter TD that is smaller than the jackscrew thread 1027 diameter THD.

In the fourth embodiment, the assembly torque access 1053 may be provided by the jackscrew heads 1029. For that purpose, the jackscrew heads 1029 may have circumferentially continuous circle portions that are circumferentially interposed with a radial torque access recess. This provides on one hand torque access to individual jackscrews 1026 with correspondingly shaped nuts as is well known in the art. On the other hand, the jackscrew heads 1029 may be concurrently accessed with a jackscrew assembly tightening tool 800 that has an array of jackscrew head access holes 802 on its tool bottom 803. The jackscrew head access holes 802 are preferably circumferentially arrayed and are matching the jackscrew head 1029 pattern above the main top 1011. The jackscrew head access holes 802 are close to an outer tool diameter TOD that is preferably smaller than an outer main body diameter BOD. This greatly improves access clearance especially in tight situations. It is facilitated by the even load transfer over a large number of jackscrew heads 1029 and their top guide shafts 1072 that hold the jackscrew heads 1029 rigid against out of axis bending as may be well appreciated by anyone skilled in the art. A tool access 801 on the tool top 804 may be a square hole for coupling with a hydraulic torque wrench as is well known in the art.

During tightening of the jackscrews 1029, the main body 1008 may come under load and elastically deflect radial outward at the main bottom 1014. To keep the castle guide holes 1078 radial aligned with top guide holes 1022 in that case, a castle spacing between adjacent castle extensions 1057 may have an outer castle spacing CLO that is less than an inner castle spacing CLI. In that way, the castle recesses 1058 are radial opposed by the castle extensions 1057 while the main bottom 1014 may elastically deform in direction away from the central thread axis 1005. In the fourth embodiment, the jackscrews 1029 are screwed in from the main bottom 1014 and from the castle recesses 1058. The load washer 1035 is then mated with the main body 1008 and the spherical bottoms 1032 brought into contact with spherical faces 1041. Main body 1008 and load washer 1035 are together screwed on and/or in at their assembly location. Then, the pre tightening tool 800 may be coupled with the jackscrew tightening assembly 1000 by mating its jackscrew head access holes 802 with the jackscrew heads 1029. The pre tightening tool 800 may be coupled to a hydraulic torque wrench via its tool access 801 and a pre tightening primary torque conveniently applied to the main body 1008 via the jackscrew heads 1029. The top guide shafts 1072 assist thereby to transfer the pre tightening force onto the main body 1008. After removing the pre tightening tool 800, the individual jackscrew heads 1029 may be accessed to bring the jackscrew tightening assembly 1000 up to final loading. Loosening of it may be performed in reverse as may be clear to anyone skilled in the art.

Referring to Figs. 7A - 9C and fifth, sixth and seventh embodiments of the invention, the load washer 1535 may be at least circumferentially but preferably also radial held with the main body 1008 via interlock pins 1701 that are fitted in respective washer interlocks 1544 provided by the load washer 1535 and body interlocks 1247 provided by the main body 1208. The interlock pins 1701 are preferably partially extending radial beyond a body circumference 1209 of the main body 1208, thereby defining ridges in a circumferential tool access for external tool access of and torque transfer to the main body 1208 around the central thread axis 1105 as may be well appreciated by anyone skilled in the art. The interlock pins 1701 are preferably press fitted into the body interlocks 1247 and axially slide able in the washer interlocks 1544. The load washer 1535 may have at its first washer bottom 1537 a lock feature such as radial serrations 1550. In the single washer configuration of the fifth embodiment, during initial tightening via the main body 1208, the radial serrations slide on the flange top 101. Upon final tightening of the jackscrews 1326, the radial serrations 1550 bite into the flange top 101 such that inadvertent loosening of the central thread 1102 is opposed. Part of a sixth embodiment as in Figs. 8A - 8C and a seventh embodiment as in Figs. 9A - 9C is a lock washer stack 1433 that includes the load washer 1535 and a lock washer 1635. The lock washer stack 1433 is specifically configured to take advantage of the dual actuation for tightening and loosening provided by the tool access feature of the main body 1208 and the jack screws 1326. Thus, the main body 1208 may be locked and unlocked through the tightening and loosening of the jackscrews 1326. In the lock washer stack 1433, the load washer 1538 has is features on its first washer top 1536 such as the spherical faces 1541 and the washer interlocks 1544 as explained under the fifth embodiment.

The lock washer 1635 features on its second bottom 1637 the lock feature(s), which may be in the sixth embodiment a coupling protrusion 1644 and in the seventh embodiment radial serrations 1650. On the first washer bottom 1537 is a first ratchet feature 1542. On a second washer top 1636 of the lock washer 1635 is a second ratchet feature 1642 mating the first ratchet feature 1542 such that upon contact of the first washer bottom 1537 with the second washer top 1636 a circumferentially at least one directional locking in loosening direction of the central thread 1102 is provided between first and second ratchet features 1542, 1642.

In the sixth embodiment, the coupling protrusion 1644 is preferably a bend able and/or bent lip at the circumference of the lock washer 1635. It may engage with a flange lock 105 such as a prefabricated hole, groove or edge as is well known in the art. Nevertheless, the scope of the invention includes any configuration of the coupling protrusion 1644 to provide a form based interlocking with any well known structure on the attachment site such as flange 100 as may be well appreciated by anyone skilled in the art. Due to the form interlock, the lock washer 1635 of the sixth embodiment is rigidly held against rotation as soon as it is positioned at the attachment site. The second ratchet feature 1642 and the first ratchet feature 1542 have a mating ratcheting configuration such that upon unloaded contact between the first washer bottom 1537 and the second washer top 1636, the load washer 1535 is rotationally unrestricted with respect to the lock washer 1636 and such that the load washer 1535 is rotationally restricted with respect to the lock washer 1635 upon loaded contact between the first washer bottom 1537 and the second washer top 1636. The loaded contact is induced via the spherical faces 1541 and via the second washer bottom 1637 resting on the attachment site 100.

As shown in Fig. 8A, the dual actuation may be additionally utilized by employment of a bottom rim 1257 in conjunction with a bearing face 1647 that is inside of the second ratchet feature 1642 as shown in Fig. 8B. A second through hole 1639 is substantially smaller then the first through hole 1539 and just big enough to fit around the central thread 1102. The bottom rim 1257 extends through the first through hole 1539 such that it axially contacts the bearing face 1647 while the jackscrews 1326 are released. Hence and because of the dual actuation, the main body 1208 may initially be tightened with low friction by withholding itself directly on the bearing face 1647 and bypassing the ratchet interface 1542, 1642. The load washer 1535 rotates with the main body 1208 and its spherical faces 1541 aligned with the spherical jackscrew bottoms 1332, but it remains axially loose. Once the initial tightening is completed and a substantial portion of the overall load displacement absorbed by the central thread 1102, secondary tightening of the jackscrews 1326 brings the jackscrew tightening assembly 1000 to full load with relatively little final displacement. The ratchet features 1542, 1642 engage and lock the jackscrew tightening assembly 1000. During loosening of it, initial loosening of the jackscrews 1326 releases the ratchet features 1542, 1642 and brings the bottom rim 1257 again in contact with the bearing face 1647. The central thread 1102 may be then loosened with relatively low friction as may be clear to anyone skilled in the art. Bottom rim 1257 and bearing face 1647 may be employed in the sixth embodiment as depicted in Figs. 8A - 8C and also with the seventh embodiment of the invention.

First and second ratchet features 1542, 1642 may be configured with a one directional circumferential lock as depicted in the Figs. 8A - 8C, which provides a full lock even in the case the jackscrews 1326 becoming slightly loose. The one directional circumferential lock may be particularly advantageous in conjunction with the coupling protrusion 1644 such that a continuous form locking is established between the attachment flange 100 and the main body 1208 across the lock washer 1635 and the load washer 1535. Referring to Figs. 9A - 9C, the first and the second ratchet features 1542, 1642 include a helical interface 1573, 1673 that has an interface pitch substantially larger than a thread pitch of the central thread 1102 and that has an interface pitch direction that is the same as a thread pitch direction of the central thread 1102. That way, once the jackscrews 1326 are finally tightened, a forced thread wedging is established via the rotational coupling of the load washer 1536 with the main body 1208. Any loosening rotation of the main body 1208 around the central thread 1102 would force the load washer 1536 to rotate as well and the helical interface 1573, 1673 to slide and induce an axial displacement that would exceed the axial displacement due to loosening of the central thread 1102. The seventh embodiment may be employed in conjunction with a lock feature such as radial serrations 1650 as shown in Figs. 9A - 9C or in conjunction with a coupling protrusion 1644 as depicted in Figs. 8A - 8C.

At least one of the jackscrews 1326, the main body 1208 or the interlock pins 1701 may be permanently magnetic to have the load washer 1535 lift off the lock washer 1635 once the jackscrews 1326 are loosened. Nevertheless, preferably the jackscrews 1326 may be preferably magnetic with an alternate magnetic polarity such that magnetic loops are established across the load washer 1535 and not the lock washer 1635. Alternately, load and lock washers 1535, 1635 may be permanent magnetic with opposing polarity such that they push each other apart as may be clear to anyone skilled in the art.

Accordingly, the scope of the Figures and the Specification above is set forth by the following claims and their legal equivalent: