Abstract:
For elongating and relaxing a stud arranged in an object, the stud of a fastener part is engaged by a tool part of a power tool, and the fastener part is operated by a pawl-ratchet mechanism including a pawl provided in the tool part and a ratchet provided in the fastener part and turnable by the pawl in a ratcheting fashion.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a nut for elongating or relaxing studs, bolts, and the like, as well as to a tool for and a method for the same.  
         [0002]     More particularly, the present invention can deal with such a nut which has an outer sleeve, an inner sleeve engaging with the outer sleeve and also engaging with a stud, the bolt and the like, and a washer element connected with the inner sleeve and not connected with the outer sleeve, so that when equal and opposite forces are applied to the washer and to the outer sleeve, the outer sleeve turns, while the inner sleeve moves only in an axial direction to move the stud, the bolt and the like in the axial direction so as to elongate or to relax it.  
         [0003]     Such nuts, as well as power tools and methods are disclosed in my U.S. Pat. Nos. 5,318,397; 5,341,560; 5,539,970; 5,946,789 and 6,461,093. In the above mentioned patents power tools incorporating a complete ratchet-pawl mechanism are utilized. It is believed that the existing nuts as well as the power tools and methods for actuating fasteners provided with the nuts can be further improved.  
       SUMMARY OF THE INVENTION  
       [0004]     Accordingly, it is an object of the present invention to provide a nut for elongating and relaxing a stud, and also a tool and a method for the same.  
         [0005]     In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a nut for elongating and relaxing a stud arranged in an object, comprising a nut member which is formed as a ratchet which is engageable with and turnable in a ratcheting manner by a pawl of a power tool so that said ratchet of the nut and said pawl of the power tool together form a pawl-ratchet mechanism.  
         [0006]     In accordance with the present invention another feature of the present invention resides in a power tool for elongating and relaxing a stud arranged in an object, comprising a tool part with a power drive and a pawl; and a fastening part engageable with the stud for elongating and relaxing the stud and being provided with a ratchet which is engageable with and turnable in a ratcheting manner by said pawl of said tool part, so that said pawl of said tool part and said ratchet of said fastener part together form a pawl-ratchet mechanism.  
         [0007]     Still another feature of the present invention resides in a method of elongating and relaxing a stud arranged in an object, comprising the steps of providing a tool part having a power drive and a pawl; engaging the stud with a fastener part for elongating and relaxing the stud, which fastener part has a ratchet; and engaging said ratchet of said fastener part by said pawl of said tool part and turning said ratchet in a ratcheting manner, so that said pawl of said tool part and said ratchet of said fastener part together form a pawl-ratchet mechanism.  
         [0008]     When the nut and the power tool are designed in accordance with the present invention and a method is performed in accordance with the present invention, the power tool has a simpler and less expensive construction because it does not have a ratchet, while the nut cost is substantially the same because the nut needs engagement means with the tool which in this case is provided by ratchet teeth of the nut member of the nut.  
         [0009]     The novel features which are considered as characteristic for the 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  
       [0010]      FIG. 1  is a view showing a nut screwed on a stud arranged in an object, in accordance with the present invention;  
         [0011]      FIG. 2  is a side view of a power tool with a fastener in accordance with the present invention; and  
         [0012]      FIG. 3  is an end view of the power tool and the fastener shown in  FIG. 2  in accordance with the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]     A nut of a fastener in accordance with an embodiment of the present invention shown in the drawings, has an outer sleeve which is identified with reference numeral  1  and has inner engaging formations  2  formed for example as a thread. The nut further has an inner sleeve  3  which has outer engaging formations formed for example as a thread  4  engaging with the thread  2  of the outer sleeve  1 . The inner sleeve also has inner engaging formations formed as a thread  5  which engages with an outer thread  6  of a stud  7  introduced into an object  8 . The nut further has a washer  9  which has engaging formations  10  interacting with engaging formations  11  of the inner sleeve  3 , so that the washer  9  can not turn relative to the inner sleeve  3 . The engaging formations  10  and  11  can be formed for example as interengaging splines. The washer  9  further has outer engaging formations  12  formed for example as external splines.  
         [0014]     The nut in accordance with the present invention operates in the following manner:  
         [0015]     When a power tool is applied to the nut so that a non-rotatable part of the power tool engages the washer  9  so as to at least hold the washer non-rotatably, while a rotatable part of the power tool turns the outer sleeve  1 , the inner sleeve  3  can not turn but instead is displaced only in an axial direction, and thereby the stud  7  also displaces in an axial direction so as to elongate or to relax.  
         [0016]     In order to hold the washer  9  non-rotatably and to turn the outer sleeve  1 , a power tool is provided which has a power drive  21 . The power drive  21  includes a cylinder  22  which defines an inner chamber  23 , and a piston  24  which is displaceable in the inner chamber  23  of the cylinder  22  in response to supply of a pressurized fluid at a corresponding side of the piston  24 . The piston  24  has a piston rod  25  and moves reciprocatingly with the latter.  
         [0017]     The power tool is provided for operating the fastener so as to at least hold the washer  9  and to turn the outer sleeve  1 . For this purpose, a pawl-ratchet mechanism is provided.  
         [0018]     In accordance with the present invention the pawl-ratchet mechanism includes a pawl which is identified with reference numeral  31  and forms a part of the power tool. The pawl  31  is turnably connected at its one end with the piston rod  25  and has engaging formations formed for example by two teeth  32  and  33  at the opposite side. A ratchet of the pawl-ratchet mechanism is formed by the outer sleeve  1 . For this purpose the outer sleeve  1  is provided with a plurality of ratchet teeth identified with reference numeral  34  and formed on its periphery. The tooth  32  of the pawl  31  which can be formed as a pushing tooth, and the tooth  33  of the pawl  26  which can be formed as a pulling tooth and engageable with the teeth  34  of the outer sleeve  1 .  
         [0019]     During the operation when the piston  24  with the piston rod  25  are displaced in one direction, the pushing tooth  32  of the pawl  31  engages between the teeth  34  of the outer sleeve  1  and pushes the sleeve  1 , for example in a clockwise direction, while when the piston  24  with the piston rod  25  are displaced in an opposite direction the pulling tooth  33  engages between the teeth  34  of the ratchet sleeve  1  and pulls the outer sleeve  1  also in the same clockwise direction, to provide a continuous rotation of the outer sleeve  1 .  
         [0020]     It is therefore believed to be clear that in accordance with the present invention the pawl-ratchet mechanism  4  which converts the displacement of the piston into turning of the nut includes the pawl provided exclusively in the tool part and the ratchet located exclusively in the fastener part.  
         [0021]     As can be seen from the drawings, a leaf spring  35  is provided to maintain the engagement of the pawl  31  with the teeth  34  of the outer sleeve  1  as can be seen from  FIG. 2 .  
         [0022]     As can be also seen from  FIG. 3 , a side plate  41  which forms an immovable part of the housing of the power tool is engaged with the splines  12  of the washer  9 , while an opposite side plate  42  is not engaged. A spacer  43  is provided between the side plate  41  and  42  to backup on the outer diameter of the nut. When for example an active turning force is applied by the pawl  31  to the outer sleeve  1  formed as the ratchet with the ratchet teeth  34 , an opposite reaction force is generated in the housing and in the side plate  41  which at least holds the washer  9  from turning, with the action force and the reaction force being equal to one another.  
         [0023]     It is to be understood that the nut and the fastener in this invention can be also different from those shown in the drawings and described above.  
         [0024]     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.  
         [0025]     While the invention has been illustrated and described as embodied in a nut for elongating and relaxing a stud, and a tool for and a method of actuating the same, 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.  
         [0026]     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 the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.