METHOD OF AND DEVICE FOR MECHANICAL TENSIONING OF BOLTS, STUDS AND THE LIKE

Abstract: For elongating and relaxing a bolt, a stud and the like (1) having an axis and arranged in an object (2), the stud (1) is connected with a first part (4) which is movable only in an axial direction so as to pull the stud (1) in the axial direction to elongate the stud (1) and thereby to tension it in the object (2) or to relax the stud (1), the first part (4) is moved only in the axial direction by connecting the first part (4) with a second part (3) which is movable in a transverse direction, a friction element (5) cooperates with at least one of the parts (3, 4) so as to change friction between the parts (3, 4) so that one of the parts (3, 4) has a higher friction than another of the parts (3, 4).

Description: Description Method of and Device for Mechanical Tensioning of Bolts, Studs and the Like Technical field The present invention relates to a method of mechanical tensioning of bolts, studs and the like and also to a device for mechanical tensioning the same. More particularly, it relates to a method of and a device for mechanical tensioning of bolts, studs and the like, which are arranged in an object, such as for example a flange and the like. Background Art Methods and devices for tensioning of the above mentioned general type are known in the art. For example, a mechanical nut is utilized, which has two elements movable relative to one another in opposite axial directions to elongate or relax a bolt, a stud and the like. There are however many applications where no gaskets are used to seal the two flange portions or where the stud is oversized relative to the required clamping force. Therefore with a steel-to-steel flange connection there is no compression feasible, and with an oversized stud there is no stud elongation feasible, and thus the axial movement of one of the parts of the thusly formed nut becomes possible. Disclosure of Invention Accordingly, it is an object of the present invention to provide a method of and a device for mechanical tensioning of bolts, studs and the like, which avoids the disadvantages of the prior art. Keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a method of elongating and relaxing a bolt, a stud and the like having an axis and arranged in an object, which comprises the steps of connecting a stud with a first part which is movably only in an axial direction so as to pull the stud in the axial direction to elongate the stud and thereby to tension it in the object or to relax the stud; and moving the first part only in the axial direction by connecting the first part with a second part which is movable in a transverse direction, cooperating a friction element with at least one of the parts so as to change friction between the parts so that one of the parts has a higher friction than another of the parts and so that the second part is not connected with the friction element but instead is freely turnable relative to the friction element while freely abutting against the latter, and applying a force to at least one of the parts whereby the second part is moved in the transverse direction and the first part is moved in the axial direction to move the stud in the axial direction so as to elongate the stud and apply to the object a clamping force so that the two parts, the stud and the friction element cannot move transversely and axially relative to the object and vice versa, and a unitary structure is produced with all components which are immovably clamped with one another. In accordance with another feature of the present invention a mechanical tensioner for elongating and relaxing a bolt, a stud and the like having an axis and arranged in an object is proposed, which comprises a first part connectable with said stud to pull said stud and movable only in an ^ axial direction so as to pull said stud in the axial direction so as to elongate said stud and thereby to tension it in said object, or to relax said stud; and means for moving said first part in the axial direction and including a second part connected with said first part and movable in a transverse direction, and a friction element SUBSTITUTE which cooperates with at least one of said parts so as to change friction between said parts so that one of said parts has a higher friction than another of said parts, said second part being not connected with said friction element but being freely turnable relative to said friction element while freely abutting against the latter, so that when a force is applied to at least one of said parts in a transverse direction to said axis, said second part moves in said transverse direction and said first part moves only in said axial direction to move said stud in said axial direction so as to elongate said stud and apply to the object a clamping force so that the two parts, the stud and the friction element cannot move transversely and axially relative to the object and vice versa, and a unitary structure is produced with all components which are immovably clamped with one another. When the method is performed and the device is designed in accordance with the present invention, the desired elongation of the bolt, stud and the like is obtained in a reliable manner, the required clamping force is applied to the object such as a flange or the like, and all parts of the device form a unitary structure in which the components cannot move relative to one another and a reliable clamping of all parts with one another is provided. The novel features which are considered as characteristic for the 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 The single Figure of " the drawings is a view showing a cross-section of a device for mechanical tensioning a bolt, a stud and the like in accordance with the present invention which implements a new method of mechanical tensioning in accordance with the present invention. Best Mode of Carrying Out the Invention A method of and a device for mechanical tensioning in accordance with the present invention is used for elongating and relaxing a stud 1 which is arranged in an outside object such as a flange 2 and the like. In accordance with the invention, the stud 1 is engaged by an inner part which is identified as a whole with reference numeral 4 and is movably only in an axial direction to pull the stud in the axial direction so as to elongate it and thereby to tension it in the object, or to relax the stud as will be explained hereinbelow. The inner part 4 is moved only in the axial direction by means of an outer part 3 which is connected with the inner part 4 and is movable in a transverse direction, and by means of a friction element 5 which cooperates with at least one of the parts 3 and 4 so as to change friction between the parts 3 and 4 as will be explained hereinbelow. The outer part 3 has an end portion 7 facing away of the flange 2 and provided with engaging formations, for example splines 8, to be engaged by a tool. The outer part 3 also has a portion 9 which faces toward the flange 2 and has a surface 10 arranged to abut against the friction element 5. Finally, the outer part 3 has an inner thread 11. The outer part 3 can be formed as a tubular member provided with the above specified formations. The inner part 4 has an end portion 12 which faces away of the flange 2 and is provided with a plurality of engaging formations, for example splines 13, to be engaged by a tool. It also has an outer surface provided with a thread 14 which engages with the thread 11 of the inner surface of the outer part 3. The inner parr4 has a portion 15 which is located inside the cooperating part 4 and has an outer surface provided with engaging formations, for example splines 16. Finally, the inner part 4 has an inner surface provided with engaging formations formed for example as an inner thread 17, for engaging with the stud 1. The inner part 4 is also formed as a tubular member. The friction element is disc-shaped. It is to be located between the end portion 9 of the outer part 3 and the flange 2 on the one hand, and surrounds the portion 15 of the inner part 4 on the other hand. The friction element 5 has an inner surface 18 provided with a plurality of engaging formations, for example splines 18, which engage with the splines 16 of the portion 15 of the inner part 4. The friction element 5 has a surface 19 against which the surface 10 of the outer part 3 abuts, and also an opposite surface 20 which abuts against the outer surface of the flange 2. The thread 11 of the outer part 3 and the thread 14 of the inner part 4 have one direction, while the thread 17 of the inner part 4 can have another direction. For example, the thread 17 can be a right-hand thread, while the threads 11 and 14 can be left-hand threads. The connecting means 11, 14 connecting the inner part 4 with the outer part 3 is thread means, while the connecting means 16, 18 for connecting the inner part 4 with the friction. element 15 can be spline means. These connecting means 11, 14 and 16, 18 are axially spaced from one another. It can be said that the inner part 4 has four surfaces cooperating with other parts and subjectable to friction. In particular, it has the surface of the inner thread 17, the surface of the outer thread 14, the end surface abutting against the friction element 5, and the end surface abutting against the flange 2. In contrast, the outer part 3 has only two surfaces which are subjectable to friction, namely the surface of the inner" thread 11, and the surface 19 SUBSTT abutting against the friction element 5. In order to elongate or relax the stud in accordance with the present invention, a tool is applied so that it engages the splines 8 of the outer part 3 to move the latter and also engages the splines 13 of the inner part so as to at least hold the part 4. When the outer part 3 is moved in a direction which is transverse to an axis of the tensioner and the stud, or more particularly is turned about this axis, its -surface 10 abuts against the surface 19 of the friction element 5 and therefore the outer part 3 cannot move further onto the friction element 5 in the axial direction. Under the action of turning of the outer part 3 and due to the cooperation between the threads 11, 14, the inner part 4 is displaced in the axial direction, upwardly in the drawings, and at the same time does not displace in the transverse direction or in other words does not turn around the axis. During these movements the friction element 5 is neither displaced in the transverse direction (turned around the axis) nor in the axial direction. It is immovable relative to the flange 2. The axial upward displacement of the inner part 4 without the transverse displacement (turning around the axis) causes pulling of the stud 1 upwardly and therefore it is elongating. Thus due to inventive cooperation of the parts 3 and 4 and the friction element 5 which imparts a higher friction to the inner part 4 than the outer part 3, when a force is applied to one of the parts 3, 4 in a transverse direction to the axis (by applying a force to one part, by holding one part and turning another part, by applying a turning force to both parts in opposite directions with equal forces) , after elimination of the gaps in the assembly the outer part 3 moves in the transverse direction to the axis (rotates) while the inner part 4 moves only in the axial direction to pull the stud 1 upwardly in the axial direction. When the bolt, stud and the like 1 is elongated, a substantial clamping force is applied to the flange 2, so that the parts 3, 4, the friction element 5 and the stud 1 cannot move transversely or axially relative to the flange 2 and vice versa, so that a unitary structure is produced with all components which are immovably clamped with one another. While the invention has been illustrated and described as embodied in a method of and a device for mechanical tensioning of bolts, studs and the like, 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.

Claims: _ g _ Claims 1. A method of elongating and relaxing a stud having an axis and arranged in an object, the method comprising the steps of connecting a stud with a first part which is movably only in an axial direction so as to pull the stud in the axial direction to elongate the stud and thereby to tension it in the object or to relax the stud; and moving the first part only in the axial direction by connecting the first part with a second part which is movable in a transverse direction, cooperating a friction element with at least one of the parts so as to change friction between the parts so that one of the parts has a higher friction than another of the parts and so that the second part is not connected with the friction element but instead is freely turnable relative to the friction element while freely abutting against the latter, and applying a force to at least one of the parts whereby the second part is moved in the transverse direction and the first part is moved in the axial direction to move the stud in the axial direction so as to elongate the stud and apply to the object a clamping force so that the two parts, the stud and the friction element cannot move transversely or axially relative to an object surface and vice versa, and a unitary structure is produced with all components which are immovably clamped with one another. 2. A method as defined in claim 1 f wherein the connecting the first part with the stud is performed by first thread means and the connecting the second part with the first part is performed by second thread means. 3. A method as defined in claim 1; and further comprising the step of arranging the friction element between the object and an end portion of the second part which faces the object so that the friction element surrounds an end portion of the first part which faces the object. 4. A method as defined in claim 1, wherein said step of applying a force includes engaging the second part by a tool and moving the second part by a tool in the transverse direction. 5. A method as defined in claim 1, wherein said applying force includes engaging the first part by a tool and holding the first part immovably in the transverse direction. 6. A method as defined in claim 1; and further comprising the step of providing first connecting means for connecting the first part with the second part so that the second part moves in the transverse direction, and second connecting means axially spaced from the first connecting means and connecting the first part with the friction element so that the first part moves only in the axial direction. SUBSTITUTESHEET 7. A mechanical tensioner for elongating and relaxing a bolt, a stud and the like having an axis and arranged in an object is proposed, which comprises a first part coπnectable with said stud to pull said stud and movable only in an axial direction so as t pull said stud in the axial direction so as to elongate said stud and thereby to tension it in said object, or to relax said stud; and means for moving said first part in the axial direction and including a second part connected with said first part and movable in a transverse direction, and a friction element which cooperates with at least one of said parts so as to change friction between said parts so that one of said parts has a higher friction than another of said parts, said second part being not connected with said friction element but being freely turnable relative to said friction element while freely abutting against the latter, so that when a force is applied to at least one of said parts in a transverse direction to said axis, said second part moves in said transverse direction and said first part moves only in said axial direction to move said stud in said axial direction so as to elongate said stud and apply to the object a clamping force so that the two parts, the stud and the friction element cannot move transversely or axially relative to an object surface and vice versa, and a unitary structure is produced with all components which are immovably clamped with one another. 2. A mechanical tensioner as defined in claim 7; and further comprising first connecting means which connect said first part with the stud and second connecting means which connect said second part with said first part, said connecting means being formed as threads having opposite directions. SUBSTITUTES 9. A mechanical tensioner as defined in claim 7, wherein said friction element has a first means formed so that said first part moves in said axial direction relative to said friction element and does not move in said transverse direction relative to said friction element, and second means formed so that said second part moves in said transverse direction relative to said friction element and stops movement of said second part onto said friction element in said axial direction. 10. A mechanical tensioner as defined in claim 9 , wherein said first means of said friction element includes a plurality of splines extending in an axial direction. 11. A mechanical tensioner as defined in claim 9, wherein said second means of said friction element includes an abutment surface facing toward said second part so that said second part abuts against said abutment surface when it is moved in said axial direction onto said friction element. 12. A mechanical tensioner as defined in claim 7, wherein each of said parts has an end portion arranged to face the object, said friction element being located between said end portion of said second part and the object and surrounds said end portion of said first part. 13. A mechanical tensioner as defined in claim 7, wherein said second part has means for engaging by a tool for moving " said second part in said transverse direction. 14. A mechanical tensioner as defined in claim 7, wherein said first part has means for engaging by a tool so as to at least hold said first part immovably in said transverse direction. 15. A mechanical tensioner as defined in claim 7, wherein said second part having a threaded inner surface, said friction element having a polygonal inner surface, said first part having an outer surface with two axially spaced portions including a first cylindrical axial portion which is threaded and engages with said threaded inner surface of said second part and a second axial portion which is polygonal and engages with said polygonal inner surface of said friction element. 16. A mechanical tensioner as defined in claim 7; and further comprising first connecting means for connecting said first part with said second part so that said second part moves in said transverse direction; and second connecting means axially spaced from said first connecting means and connecting said first part with said friction element so that said first part moves only in said axial direction.

Inventors: JUNKERS JOHN K, JUNKERS, JOHN, K.
Applicants: JUNKERS JOHN K, JUNKERS, JOHN, K.
Application year: 1993
Main classification: F16B37
IPC codes: B23P19, B25B21, B25B23, B25B29, F16B21, F16B31, F16B33