AU2006200183A1 - A washer, a fastener provided with the washer, and method of and a tool for fastening with the use of the washer - Google Patents

Description

AUSTRALIA

Patents Act 1990 UNEX CORPORATION COMPLETE SPECIFICATION STANDARD PATENT Invention Title: A washer, a fastener provided with the washer, and method of and a tool for fastening with the use of the washer The following statement is a full description of this invention including the best method of performing it known to us:- BACKGROUND OF THE INVENTION Mq The present invention relates to a washer, a fastener provided 00 with a washer, and a method of and tool for fastening with the use of the c 5 washer.

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It is known to fasten objects with one another with a fastener which has a multi-part replacement nut, for example including an inner sleeve, an outer sleeve, and a washer. Such a replacement nut is disclosed for example in our U.S. patent no. 5,341,560. Another replacement nut is disclosed in our U.S. patent no. 6,254,323, in which a bolt has a spline underneath its upper thread, to which a washer is non-rotatably connected, and the bolt also has engaging means for applying a reaction force, while an active force of the same tool turns the nut on the bolt thread and the washer face, In the fastener disclosed in both above mentioned patents, the common features are the use of action and reaction force of one tool, the elimination of reaction arms on torque power tools, the conversion of torque to torsion-free bolt stretching and obtaining for the first time the desired -2o residual bolt load as compared to torque, which estimates are based on calculated frictions rather than actual friction or hydraulic tension, which is Sbased on estimated bolt relaxation when the force is transmitted from elongated bolt to the hand-tight nut.

00 O With the fastener disclosed in U.S. patent no. 5,341,560 the nut In 5 has to be made with two sleeves whose outside diameter has to meet the Soutside diameter of a regular nut, both sleeves have less material than the regular nut. This requires the use of high strength materials. In the fastener disclosed in the U.S. patent no. 6,254,323 the bolt needs to be altered, which is not only costly but also not easily acceptable by the industry.

lO In order to eliminate the above mentioned disadvantage a new washer was developed, as well as a fastener provided with a washer and also a method of and a tool for fastening with the use of the new washer, as disclosed in our U.S. patent no. 6,609,868 and also in our U.S. patent applications 10/112,101; 10/427,103; 10/655,182. This new washer which is applied between a nut screwable on a bolt, and an object into which the bolt is introduced, has a first bearing face surface adapted to cooperate with the nut and having a facial friction with the nut, an opposite second bearing face surface adapted to cooperate with the object and having a facial friction .0 with the object, and a turning resistant surface located inside the washer and engageable with the bolt to resist its turning, so that a radially inner part of the washer which engages with the bolt can not rotate freely inside a radially outer part of the washer during tightening, but is displaced axially relative to n the radially outer part of the washer upon bolt elongation. When the nut is 00oo a turned with a given force in one direction and the washer receives S simultaneously the given force in an opposite direction, only the nut turns to 0elongate the bolt and the body of the washer remains rotation frictionally, while the bolt does not turn but only elongates or relaxes in an axial direction.

When the washer and the fastener are designed in accordance with these inventions, and also when the method is performed and the tool is designed in accordance with these inventions, regular nuts can be used.

The customer can use whatever he has adding merely a new washer. As a result, the product is much less expensive, the customer uses his approved Sbolts and nuts, and instead of reacting on a part of the nut directly or indirectly, the reaction force is solely absorbed by the washer. At the same time, this solution maintains the advantages of the solution disclosed in the previous patents in particular a torsion-free elongation of the free portion of the bolt, a known coefficient of friction between the nut face and the washer .o face and thus known bolt load precision, a reaction-arm free torque tool use.

The washer disclosed in our U.S. patent 6,609,868 and U.S.

patent application serial no. 10/427,103 is composed of two separate parts Swhich are provided with means for their interaction, so that the radially inner 00 0 part can not rotate relative to the radially outer part, but instead displaces 6 axially. Thus, two individual parts must be produced and assembled with one another. The washer disclosed in our U.S. patent applications serial no.

10/112,101 and 10/655,182 is initiallyformed as a single-part integral washer which, however, in response to elongation of the bolt in an axial direction with application of an axial force, breaks a portion of the washer to allow said Io portion to be pulled axially when the bolt elongates. Thus, in this washer is necessary to exactly calculate the breaking point of thi washer. It is believed that these solutions can be further improved.

C SUMMARY OF THE INVENTION q Accordingly, it is an object of the present invention to provide 00 a washer, a fastener provided with the washer, and a method of and a tool for fastening with the use of the washer, which constitutes further improvements of the existing solutions.

In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a washer to be applied between an object and a nut threadingly connected with a bolt which has an axis and is introduced into the object including at least two parts to be assembled, the washer comprising a body having an axis and provided at one axial side with a first bearing face surface adapted to cooperate with a nut and having a facial friction with the nut, at an opposite axial side with a second bearing face surface adapted to cooperate with the object and having a facial friction with the object, and a third turning resistant surface located inside said body and engageable with the bolt, said body being formed as a one-piece integral body including a radially inner part having said third turning resistant surface d4o engageable with the bolt, and also including a radially outer part, said radially inner part and said radially outer part together forming said one-piece c- integral body and being configured so that said radially inner part can not rotate:freely inside said radially outer part during tightening but is displaced Saxially relative to said radially outer part upon bolt elongation without 00oo completely separating from said radially outer part and with maintaining said 0 0 c 5 one-piece integral body non-destructed, so that when the nut is turned with

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O a given force in one direction and said body of the washer receives simultaneously said given force in an opposite direction, only the nut turns to elongate the bolt and said body of the washer remains rotation stationary, while said bolt does not turn but elongates or relaxes in an axial direction.

Io Another feature of the present invention resides in a fastener which has a bolt having an axis and introducible into an object including at least two parts to be assembled; a nut threadingly connected with a bolt; and a washer to be applied between an object and said nut, wherein said washer comprises a body having an axis and provided at one axial side with a first bearing face surface adapted to cooperate with a nut and having a facial friction with the nut, at an opposite axial side with a second bearing face surface adapted to cooperate with the object and having a facial friction with the object, and a third turning resistant surface located inside said body and O engageable with the bolt, said body being formed as a one-piece integral body including a radially inner part having said third turning resistant surface Sengageable with the bolt, and also including a radially outer part, said radially Sinner part and said radially outer part together forming said one-piece ¢q integral body and being configured so that said radially inner part can not 00 freely inside said radially outer part during tightening but is displaced N 6 axially relative to said radially outer part upon bolt elongation without completely separating from said radially outer part and with maintaining said one-piece integral body non-destructed, so that when the nut is turned with a given force in one direction and said body of the washer receives simultaneously said given force in an opposite direction, only the nut turns to elongate the bolt and said body of the washer remains rotation stationary, while said bolt does not turn but elongates or relaxes in an axial direction.

In accordance with a further feature of the present invention, a method of assembling at least two parts with one another is proposed, 1s which includes the steps of introducing a bolt which has an axis into an object including at least two parts to be assembled; threadingly connecting a nut with the bolt; applying a washer between the object and the nut so that at one axial side a first bearing face surface of the washer cooperates with the nut and has a facial friction with the nut, at an opposite axial side its .o second bearing face surface cooperates with the object and has a facial friction with the object, and a third turning resistant surface located inside the Swasher engages with the bolt, wherein the washer has a one-piece integral body including a radially inner part having the third turning resistant surface engageable with the bolt and also a radially outer part together forming the 00 one-piece integral body such that the radially inner part can not rotate freely inside the radially outer part during tightening but is displaced axially relative 0to the radially outer part upon bolt elongation without separating from the radially outer part; and turning the nut with a given force in one direction and applying simultaneously the given force to the body of the washer in an opposite direction, so that only the nut turns to elongate the bolt and the 1o body of the washer remains rotation stationary, while the bolt does not turn but elongates or relaxes in an axial direction.

Still a furtherfeature of the present invention resides in a power tool for fastening an object, comprising a tool part with a housing provided 1 with a housing element, and a power drive located in said housing and provided with a drive element; and a fastener part including a bolt which has an axis and is introduceable into the object including at least two parts to be assembled, a nut threadingly connected with the bolt, and a washer to be applied between the object and the nut, the washer including a body having ,O an axis and being provided at one axial side with a first bearing face surface adapted to cooperate with a nut and having a facial friction with said nut, at can opposite axial side with a second bearing face surface adapted to cooperate with the object and having a facial friction with the object, and.a Sthird turning resistant surface located inside said body and engageable with 00 said bolt, said body being formed as a one-piece integral body including a c- radially inner part having said third turning resistant surface engageable with said bolt, and also including a radially outer part, said radially inner part and said radially outer part together forming said one-piece integral body and being configured so that said radially inner part can not rotate freely inside said radially outer part during tightening but is displaced axially relative to said radially outer part upon bolt elongation without completely separating from said radially outer part and with maintaining said one-piece integral body non-destructed, so that when said nut is turned by said drive element of said power drive with a given force in one direction and said body of the washer receives simultaneously said given force by said housing element of 1S said housing in an opposite direction, only said nut turns to elongate said bolt and said body of said washer remains rotation stationary, while said bolt, does not turn but elongates or relaxes in an axial direction.

When the washer and the fastener are designed in accordance a0 with the present invention, a method of fastening is performed in accordance with the present invention and a power tool is formed in accordance with the Spresent invention, a single-piece integral washer can be utilized which does not break during the operation, but instead remains integral without separation of radially inner and radially outer parts from one another.

00 0 S The novel features which are considered as characteristic for Sthe present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Mq Figure 1 is a view showing a threaded fastener provided with 00 a washer in accordance with the present invention; Figures 2 and 3 are views showing a cross-section and a plan view of the washer shown in Figure 1; Figure 4 is a view showing across-section of a part of a power o0 tool cooperating of the fastener provided with the washer in accordance with the present invention; Figure 5 is a view substantially corresponding to the view of Figure 4, but showing a different fastener provided with the inventive washer; iS Figure 6 is a view showing a cross-section of the washer in accordance with another embodiment of the present invention; and Figures 7 and 8 are a cross-section and a plan view of a washer in accordance with a further embodiment of the present invention.

-12- DESCRIPTION OF THE PREFERRED EMBODIMENTS Figure 1 shows a threaded fastener which has a bolt identified t'q 00 with reference numeral 1 and introducible into an object which is composed Sfor example of two parts to be assembled with one another as identified with

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Sreference numeral 2. The fastener further has a nut which is identified with reference numeral 3. The nut is provided with an inner thread 4 which is screwed on an outer thread 5 of the bolt 1.

The threaded fastener further has a washer which is identified as a whole with reference numeral 6. The washer 6 has a body identified with reference numeral 7, which is provided with a first upper bearing face surface 8 cooperating with the nut 3, a second lower bearing face surface 9 cooperating with the object 2 or in particular with a surface of one of the part rS of the object to be assembled with one another, and at least one turning resistant surface which is identified with reference numeral 10. The first and second bearing face surfaces are spaced from one another in an axial direction, or in other words in a direction of an axis Al of the washer which coincides with an axis A2 of the bolt. The at least one third turning resistant -o surface 10 is located radially inwardly of the body 7 of the washer 6. The third turning resistant surface 10 is formed so as to engage with or wedge in -13a an outer surface of the bolt 1. In the embodiment shown in Figure 1 the third turning resistant surface 10 engages with or wedges in the thread 5 of the bolt 1, for example by providing a corresponding thread 11 on the turning 00oo resistant surface SAs shown in Figure 1, the body 7 of the washer is composed cI of two parts 7' and 7" which are radially spaced relative to one another, so that the part 7" is located radially inwardly of the part The turning resistant surface 10 with the thread 11 is provided radially inwardly on the part 7".

The part 7' and 7" are connected with one another so as to prevent their turning relative to one another, but to permit a movement relative to one another in an axial direction. For this purpose, the parts 7' IS and 7" are connected with one another by a connecting element so that the radially inner part 7" can not turn relative to the radially outer part but the radially inner part 7" can displace axially relative to the radially outer part Thereby a greater resistance toward movement than the turning force applied by the bolt is created so as to stop the bolt from turning along with .0 the nut and to permit an axial movement of the part 7" relative to the part 7' up by the turning nut. In other words, when a power tool holds the washer Sand turns the nut, the turning resistant surface of the inner part 7" of the washer can not turn and holds the bolt from turning, and when the bolt is Spulled up by the turning nut the inner part 7" of the washer displaces axially 00 together with the bolt relative to the outer part 7' of the washer. 0 N 6 SIn order to allow the radially inner part 7" to move axially relative to the outer part 7' without turning relative to the outer part the connecting element is formed flexible or yieldable in an axial direction, but non-flexible or non-yieldable in a circumferential direction. The flexibility of I the connecting element in the axial direction can be enhanced for example by providing additional weakening points formed for example as circumferential slots 13, which facilitate bending of the connecting element in the axial direction of the washer.

When as shown in Figure 4, a torque power tool 21 is placed on the fastener so as to tighten or loosen the nut 5, a drive portion 22 of the torque power tool 21 is connected to the nut 5 and turns the nut to overcome the thread friction with the bolt 1 and the facial friction with the washer 6 to turn the nut 5. A housing portion 23 of the torque power tool 21 is connected .o to the washer 6 to absorb the reaction force due to the facial friction of the washer 6 with the nut 5, its facial friction with one side of the parts 2, and its turning friction with the bolt 1, so that the washer 6 and the bolt 1 do not turn, but absorb the reaction force of the torque power tool.

00 O It is to be understood that in order to engage the nut 5 by the 5 drive part 22 of the torque power tool 21, the drive part 22 and nut 5 can Chave corresponding connecting means formed, for example such as a polygonal shape, as splines, etc. as identified with reference numeral 12. On the other hand, in order to connect the housing portion 23 of the torque power tool 21 to the washer 6, the housing portion 23 and the washer 6 also O can be provided with connecting means formed for example as a polygonal shape, as splines, etc as identified with reference numeral 13.

In Figure 1 the inner turning resistant surface of the washer 6 engages with the thread 5 of the bolt by its thread 11. In the embodiment shown in Figure 5, the washer is located over a portion of the bolt 1 which is arranged below the threaded portion of the bolt. An inner turning resistant surface 14 of the bolt 6, or more particularly of its radially inner part 7", engages with an outer non-threaded surface of the bolt 1, and also stops the bolt from turning during tightening of the nut.

In accordance with another feature of the present invention, the Swasher is formed so that when upon bolt elongation the radially inner part 7" Sof the washer displaces axially relative to the radially outer part 7' of the 00 washer, a contact between the radially inner part 7" of the washer and the bolt 1 increases. For this purpose for example as shown in Figure 2, the 0 connecting element extends radially downwardly from the inner surface of the radially outer part 7' toward the radially inner part When the radially inner part 7" is displaced axially upwardly in response to the bolt elongation, the left end of the connecting element also displaces axially upwardly together with the radially inner part 7" and tries to assume a horizontal position, thus pushing the radially inner part 7" radially inwardly toward the outer surface of the bolt 1, to increase the contact between the radially inner part 7" and the bolt 1.

It is to be understood that in order for the radially inner part 7" to move radially inwardly toward the outer surface of the bolt 1 and to increase its contact with the radially outer surface of the bolt, it has to be yieldable in a radially inner direction. For this purpose, as shown for example in Figure. 8, the radially inner part 7" can be composed for example ao of segments 15 with gaps 16 therebetween, so that when the radially inner end of the connecting element is displaced axially upwardly in Figure 2, -17it pushes the segments 15 radially inwardly toward the outer surface of the bolt 1.

00 As shown in Figure 7, the radially inner part 7" of the washer Ni 5- 6 can be located, in an initial condition of the washer, downwardly offset relative to the radially outer part so that the lower surface of the radially inner part 7" is located lower than the lower surface of the radially outer part With this construction when the washer is placed between the nut and the object and the nut 3 is turned, the radially inner part 7" is immediately displaced axially upwardly to move into the inner space of the radially outer part and simultaneously the segments 15 are displaced radially inwardly to engage the outer surface of the bolt 1.

The connecting element can be formed in many different '7 ways to allow the axial displacement of the radially inner part 7" relative to the radially outer part under the -action of the bolt elongation.. In one embodiment shown in Figure 6, the connecting element is formed as a wavy or corrugated element with flexible corrugations 17, which can yield relative to one another during the axial displacement of the radially inner part 0 7" relative to the radially outer part 7'.

-18- ~It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions and methods differing from the types described above.

00 c While the invention has been illustrated and described as embodied in a washer, a fastener provided with the washer, and method of and a tool for fastening with the use of the washer, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from IS the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

What is claimed as new and desiredto be protected by Letters Patent is set forth in the appended claims.

Claims (12)

1. A washer to be applied between an object and a nit 00 threadingly connected with a bolt which has an axis and is introduceable into the object including at least two parts to be assembled, the washer INO comprising a body having an axis and provided at one axial side with a first bearing face surface adapted to cooperate with a nut and having a facial friction with the nut, at an opposite axial side with a second bearing face surface adapted to cooperate with the object and having a facial friction with the object, and a third turning resistant surface located inside said body and O engageable with the bolt, said body being formed as a one-piece integral body including a radially inner part having said third turning resistant surface engageable with the bolt, and also including a radially outer part, said radially inner part and said radially outer part together forming said one-piece integral body and being configured so that said radially inner part can not rotate freely inside said radially outer part during tightening but is displaced axially relative to said radially outer part upon bolt elongation without completely separating from said radially outer part and with maintaining said one-piece integral body non-destructed, so that when the nut is turned with a given force in one direction and said body of the washer receives .0 simultaneously said given force in an opposite direction, only the nut turns to elongate the bolt and said body of the washer remains rotation stationary, while said bolt does not turn but elongates or relaxes in an axial direction. 00 O- S2. A washer as defined in claim 1, wherein said radially outer part and said radially inner part are connected with one another so that said radially inner part can not rotate freely inside said radially outer part during tightening but is displaced axially relative to said radially outer part without separating from said radially outer part.

3. A washer as defined in claim 1, wherein said radially outer part and said radially inner part are formed so that when said radially inner part is displaced axially relative to said outer part upon bolt elongation a contact between said radially inner part and the bolt increases. -21-

4. A washer as defined in claim 3, wherein said one-piece integral body includes connecting means which connect said radially outer part with said radially inner part and are of one piece with said parts, said 0_ connecting means being formed so that when during tightening the radially inner part is displaced axially relative to said radially outer part upon bolt IND 0 elongation, the contact between said radially inner part and the bolt increases. IO A washer as defined in claim 1, wherein said radially inner part has a plurality of individual portions which are spaced from.one another in a circumferential direction around said axis of said body with gaps therebetween.

6. A fastener, comprising a bolt which has an axis and is introduceable into an object including at least two parts to be assembled; a nut threading connected with said bolt; and a washer to be-applied between said nut and the object, the washer having a body with an axis and being provided at one axial side with a first bearing face surface adapted to cooperate with said nut and having a facial friction with said nut, at an opposite axial side with a second bearing face surface adapted to cooperate 00 with the object and having a facial friction with the object, and a third turning 0 resistant surface located inside said body and engageable with said bolt, Osaid body being formed as a one-piece integral body including a radially inner part having said third turning resistant surface engageable with said bolt, and also including a radially outer part, said radially inner part and said radially outer part together forming said one-piece integral body and being configured so that said radially inner part can not rotate freely inside said radially outer part during tightening but is displaced axially relative to said radially outer part upon bolt elongation without completely separating from said radially outer part and with maintaining said one-piece integral body non-destructed, so that when said nut is turned with a given force in one direction and said body of the washer receives simultaneously said given force in an opposite direction, only said nut turns to elongate said bolt and said body of said washer remains rotation stationary, while said bolt does not turn but elongates or relaxes in an axial direction. -23- r

7. A fastener as defined in claim 6, wherein said radially outer part and said radially inner part are connected with one another so that said radially inner part can not rotate freely inside said radially outer part during tightening but is displaced axially relative to said radially outer part without separating from said radially outer part.

8. A fastener as defined in claim 6, wherein said radially outer to part and said radially inner part are formed so that when said radially inner part is displaced axially relative to said outer part upon bolt elongation a contact between said radially inner part and said bolt increases. IS

9. A fastener as defined in claim 8, wherein said one-piece integral body includes connecting means which connect said radially outer part with said radially inner part and are of one piece with said parts, said connecting means being formed so that when during tightening the radially Lo inner part is displaced axially relative tosaid radially outer part upon bolt -24- Selongation, the contact between said radially inner part and said bolt increases. 00 \o A fastener as defined in claim 6, wherein said radially inner part has a plurality of individual portions which are spaced from one another in a circumferential direction around said axis of said body with gaps therebetween. 0

11. A method of assembling at least two parts with one another, comprising the steps of introducing a bolt which has an axis into an object including at least two parts to be assembled; threadingly connecting a nut with the bolt; applying a washer between the object and the nut so that at one axial side a first bearing face surface of the washer cooperates with the nut and has a facial friction with the nut, at an opposite axial side a second bearing face surface of the washer cooperates with the object and has a facial friction with the object, and a third turning resistant surface of the Io washer located inside the washer engages with the bolt, wherein the washer has a one-piece integral body including a radially inner part having the third turning resistant surface engageable with the bolt and also a radially outer part together forming the one-piece integral body such that the radially inner 00 part can not rotate freely inside the radially outer part during tightening but is displaced axially relative to the radially outer part upon bolt elongation 0 without completely separating from the radially outer part; and turning the nut with a given force in one direction and applying simultaneously the given force to the body of the washer in an opposite direction, so that only the nut turns to elongate the bolt and the body of the washer remains rotation IO stationary, while the bolt does not turn but elongates or relaxes in an axial direction. IS

12. A method as defined in claim 11; and further comprising connecting said radially outer part and said radially inner part with one another so that said radially inner part can not rotate freely inside said radially outer part during tightening but is displaced axially relative to said radially outer part without separating from said radially outer part. -26- h 13. A method as defined in claim 11; and further comprising forming said radially outer part and said radially inner part so that when said 00 radially inner part is displaced axially relative to said outer part upon bolt 0 elongation a contact between said radially inner part and the bolt increases. IND \O

14. A method as defined in claim 13; and further comprising providing in said one-piece integral body connecting means which connect said radially outer part with said radially inner part and are of one piece with said parts, such that when during tightening the radially inner part is displaced axially relative to said radially outer part upon bolt elongation, the contact between said radially inner part and the bolt increases. A method as defined in claim 11; and further comprising providing in said radially inner part a plurality of individual portions which are spaced from one another in a circumferential direction around said axis of o said body with gaps therebetween. -27- I N 16. A power tool for fastening an object, comprising a tool part with a housing provided with a housing element, and a power drive located in said housing and provided with a drive element; and a fastener part Sincluding a bolt which has an axis and is introduceable into the object 00 1 including at least two parts to be assembled, a nut threadingly connected (with the bolt, and a washer to be applied between the object and the nut, the IND 0washer including a body having an axis and being provided at one axial side with a first bearing face surface adapted to cooperate with a nut and having a facial friction with said nut, at an opposite axial side with a second bearing o face surface adapted to cooperate with the object and having a facial friction with the object, and a third turning resistant surface located inside said body and engageable with said bolt, said body being formed as'a one-piece integral body including a radially inner part having said third turning resistant surface engageable with said bolt, and also including a radially outer part, said radially inner part and said radially outer part together forming said one- piece integral body and being configured so thatsaid radially inner part can not rotate freely inside said radially outer part during tightening but is displaced axially relative to said radially outer part upon bolt elongation without completely separating from said radially outer part and with to maintaining said one-piece integral body non-destructed, so that when said nut is turned by said drive element of said power drive with a given force in -28- one direction and said body of the washer receives simultaneously said given force by said housing element of said housing in an opposite direction, only said nut turns to elongate said bolt and said body of said washer 00 remains rotation stationary, while said bolt does not turn but elongates or \O C 5 relaxes in an axial direction. IND

17. A power tool as defined in claim 16, wherein said radially outer part and said radially inner part are connected with one another so that said radially inner part can not rotate freely inside said radially outer part during tightening but is displaced axially relative to said radially outer part without separating from said radially outer part.

18. A power tool as defined in claim 16, wherein said radially outer part and said radially inner part are formed so that when said radially inner part is displaced axially relative to said outer part upon bolt elongation ;o a contact between said radially inner part and the bolt increases. -29- S19. A power tool as defined in claim 18, wherein said one- piece integral body includes connecting means which connect said radially outer part with said radially inner part and are of one piece with said parts, 00oo said connecting means being formed so that when during tightening the radially inner part is displaced axially relative to said radially outer part upon INO bolt elongation, the contact between said radially inner part and the bolt increases. A power tool as defined in claim 16, wherein said radially inner part has a plurality of individual portions which are spaced from one another in a circumferential direction around said axis of said body with gaps therebetween. DATED THIS 17th DAY OF JANUARY 2006 UNEX CORPORATION Patent Attorneys for the Applicant:- F.B.RICE CO