Clamping device for expanding a threaded bolt

Abstract

A clamping device for expanding a threaded bolt is provided with a support pipe supported against an underlay surrounding the threaded bolt. A cylindrical housing arranged in extension of the support pipe has a piston movable in longitudinal direction and connectable to a hydraulic supply. A changeable bushing is axially carried by the piston and is provided with an inner thread and a radially expanded portion. A resilient arrangement is arranged around the bushing and acts axially on the piston. A lid is secured to the housing. The other support of the resilient arrangement is provided on the lower side of the housing. The lid has a lid base member and a closure lid. The lid base member is provided with an opening closable by the closure lid. The radial extent of the opening is greater than the radial extent of the radially expanded portion of the bushing.

Claims

1. A clamping device for expanding a threaded bolt by pulling on the threaded end portion (A) thereof, the clamping device comprising: a support pipe (2) which is supported as an abutment against an underlay (8) which surrounds the threaded bolt; a cylindrical housing (1) which is arranged in extension of the support pipe (2) and which has at least one piston (5) which can be moved therein in the longitudinal direction and which can be connected to a hydraulic supply line; a changeable bushing (10) which is constructed so as to be able to be axially carried by the piston (5) and which, for screwing to the threaded end portion (A) of the threaded bolt, is provided with an inner thread (11) and, for axial carrying by the piston (5), is provided with a radially expanded portion (25); a resilient arrangement (15) arranged around the changeable bushing (10) and acting axially on the piston (5); and a lid which is secured to the cylindrical housing (1); wherein the lid is of a two-part construction comprising a lid base member (40) and a closure lid (41), wherein the lid base member (40) is securely connected to the cylindrical housing (1) and has a top end with an annular radial collar projecting inwardly and having a radial inner rim defining an opening (48) of the lid base member (40), wherein a lower side of the annular radial collar forms the other support (47) of the resilient arrangement, wherein the closure lid (41) is removably secured in the opening (48) whose radial extent (W3) is greater than the radial extent (W1) of the radially expanded portion (25) of the changeable bushing (10), wherein, when the closure lid (41) is removed, the changeable bushing (10) is removable through the opening (48) from the clamping device and the resilient arrangement (15) remains supported at the annular radial collar.

2. The clamping device according to claim 1, wherein the inner extent (W2) of the resilient arrangement (15) is greater than the radial extent (W1) of the radially expanded portion (25) of the changeable bushing (10).

3. The clamping device according to claim 1, wherein the resilient arrangement (15) is in abutment with a resilient support (16) formed on the piston (5).

4. The clamping device according to claim 1, wherein the radially expanded portion (25) is a radial collar which is integrally formed on the changeable bushing (10).

5. The clamping device according to claim 1, wherein the radially expanded portion (25) is a carrier ring (32A) which is screwed to the base member (10A) of the changeable bushing (10).

6. The clamping device according to claim 1, wherein an annular face is formed at the radially expanded portion (25) and the changeable bushing (10) is axially supported by the annular face on a step (12) of the piston (5).

7. The clamping device according to claim 1, wherein the changeable bushing (10) is composed of: a first longitudinal portion (31) provided with the inner thread (11), a second longitudinal portion (32) being the radially expanded portion (25), and a third longitudinal portion (33) being constructed in a journal-like manner and filling an opening (50) in the upper side of the clamping device.

8. The clamping device according to claim 1, wherein the closure lid (41) is locked by rotation of the lid base member (40) in the opening (48).

9. The clamping device according to claim 1, wherein the closure lid (41) is an annular disc provided with an opening (50) which is coaxial relative to the opening (48) in the lid base member (40) and which is filled by a journal-like longitudinal portion (33) of the changeable bushing (10).

10. The clamping device according to claim 9, wherein the greatest radial extent (W1) of the changeable bushing (10) is greater than the radial extent (W4) of the opening (50) of the closure lid (41).

11. The clamping device according to claim 9, wherein the journal-like longitudinal portion (33) of the changeable bushing is provided with an outer end face (34) which in the initial state of the clamping device terminates with the upper side (35) of the clamping device, and is provided with a marking (37) below the outer end face (34).

12. The clamping device according to claim 1, wherein the lid base member (40) is screwed to the cylindrical housing (1).

13. The clamping device according to claim 1, wherein the closure lid (41) is an annular disc provided with an opening (50) which is coaxial relative to the opening (48) in the lid base member (40), wherein the greatest radial extent (W1) of the changeable bushing (10) is greater than a radial extent (W4) of the opening (50) of the closure lid (41).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other details and advantages will be appreciated from the following description of the embodiments illustrated in the drawings:

(2) FIG. 1 is a simplified sectioned illustration of a hydraulically functioning threaded bolt clamping device, placed on a threaded bolt and supported on an underlay, a closure lid being illustrated above the clamping device.

(3) FIG. 2 shows the objects according to FIG. 1 with the changeable bushing removed from the clamping device.

(4) FIG. 3 shows the upper portion of a second embodiment of a hydraulically functioning threaded bolt clamping device, here with the changeable bushing removed.

(5) FIG. 4 shows an alternative variant compared with the embodiment according to FIGS. 1 to 3 for securing the closure lid in the lid base member.

(6) FIG. 5 shows an alternative variant compared with the embodiment according to FIGS. 1 to 3 for securing the closure lid in the lid base member.

(7) FIG. 6 shows an alternative variant compared with the embodiment according to FIGS. 1 to 3 for securing the closure lid in the lid base member.

(8) FIG. 7 shows an alternative variant compared with the embodiment according to FIGS. 1 to 3 for securing the closure lid in the lid base member.

(9) FIG. 8 shows an alternative variant compared with the embodiment according to FIGS. 1 to 3 for securing the closure lid in the lid base member.

(10) FIG. 9 shows an alternative variant compared with the embodiment according to FIGS. 1 to 3 for securing the closure lid in the lid base member.

(11) FIG. 10 shows an alternative variant compared with the embodiment according to FIGS. 1 to 3 for securing the closure lid in the lid base member.

DESCRIPTION OF PREFERRED EMBODIMENTS

(12) The hydraulically operated clamping device serves to tighten and optionally also to release highly loaded screw connections. With the clamping device, it is possible to apply a predetermined pretensioning force to the threaded bolt 3 in the longitudinal direction of the bolt for a specific length of time in order in the meantime to tighten or retighten a nut 4 of the screw connection, which nut is screwed onto the threaded bolt 3.

(13) A changeable bushing 10 which is arranged in the clamping device is provided with an inner thread 11. This inner thread is screwed onto the threaded end portion A of the threaded bolt 3, which portion protrudes beyond the nut 4. Subsequently, the changeable bushing 10 which is screwed in this manner onto the threaded bolt is hydraulically placed under traction, whereby the threaded bolt 3 expands in a longitudinal direction.

(14) The clamping mechanism is surrounded by a cylindrical housing 1. This may also be composed in a modular manner from a plurality of cylindrical portions.

(15) The rigid continuation of the cylindrical housing 1 in a downward direction forms a support pipe 2 which surrounds the nut 4. The support pipe 2 may alternatively also be a component which is separated with respect to the cylindrical housing 1, for example, a component which can be placed thereon.

(16) The support pipe 2 is open at the lower side thereof and is supported on that underlay 8, mostly a machine component on which the nut 4 is also supported. Furthermore, there may be provided a gear mechanism which operates through an opening 9 in the support pipe 2 and by means of which the nut 4 which is screwed onto the threaded bolt 3 can be rotated. This rotation is naturally only possible when the clamping device is operational and the nut 4 is therefore not subjected to considerable friction.

(17) There is located laterally on the cylindrical housing 1 which is constructed in a pressure-resistant manner a hydraulic connection 7, by means of which the hydraulic operating space of the clamping device is connected to an external hydraulic supply with valve control.

(18) The cylindrical housing 1 comprises one or alternatively also a plurality of hydraulic cylinders, which are connected to the external hydraulic supply by means of the hydraulic connection 7 and a flexible, pressure-resistant hydraulic line. In each hydraulic cylinder, a piston 5 which is sealed with respect to the inner cylindrical wall is arranged so as to be able to be moved in the longitudinal direction. In the embodiment described in this instance, only one cylindrical step and consequently only one piston 5 are provided.

(19) By supplying hydraulic pressure to the operating space, the hydraulic piston 5 is raised. This is carried out counter to the pressure force of a resilient arrangement 15 which is supported from above on the piston. The resilient arrangement 15 comprises in this instance annular disc springs which are arranged one on the other and consequently connected in series.

(20) The resilient arrangement 15 presses from above on a resilient support 16 which is formed directly on the piston 5 and acts in this manner on the piston 5 directly with a force which seeks to keep the piston 5 in the basic position which is illustrated in FIG. 1 and FIG. 2 and in which the hydraulic operating space is at a minimum.

(21) The piston 5 is annular and is provided at the inner edge thereof with a preferably continuous step 12. The step 12 forms, facing away from the underlay 8, an axial face on which the changeable bushing 10 is supported by means of an expanded portion 25 which is formed integrally thereon. In this manner, the changeable bushing 10 can be axially carried by the piston 5.

(22) The changeable bushing 10 which is illustrated separately in FIG. 2 is composed, when viewed from the underlay 8, of a first longitudinal portion 31, a second longitudinal portion 32 and a third longitudinal portion 33.

(23) On the first longitudinal portion 31, the changeable bushing 10 has the inner thread 11 which can be subjected to high loads and which can be screwed onto the threaded end portion A of the threaded bolt 3 by means of rotating the changeable bushing. The axial length of the inner thread 11 and consequently the screwing depth available should be at least equal to the thread diameter of the bolt 3, preferably 1.5 times the thread diameter.

(24) The second longitudinal portion 32 of the changeable bushing 10 is in the embodiment according to FIGS. 1 and 2 constructed as an integrally formed collar. This longitudinal portion 32 at the same time forms the largest portion of the changeable bushing in terms of radius. As already described, it serves to axially support the changeable bushing on the piston 5.

(25) The third longitudinal portion 33 is constructed in a journal-like manner and has a smaller diameter than the second longitudinal portion 32 so that, in order to rotate the changeable bushing 10, it can be readily gripped by hand on the third longitudinal portion 33.

(26) The closure of the changeable bushing 10 is formed by a planar outer end face 34. In the embodiment described in this instance, the outer end face 34 in the initial state of the clamping device terminates in a plane with the upper side 35 of the clamping device. In the end face 34, a polygon for motorised rotation of the changeable bushing 10 can be formed centrally. Alternatively, it is possible to extend the longitudinal portion 33 upwards until it clearly protrudes above the upper side 35 and can be gripped by hand at that location in order to rotate the changeable bushing 10. To this end, the longitudinal portion 33 may be provided with a friction-increasing corrugation.

(27) Below the outer end face 34, a marking 37 in the form of a groove is formed in the third longitudinal portion 33. Owing to the position of the marking 37 with respect to the upper side 35 of the clamping device, it is possible for the user to optically identify how far the clamping process has progressed.

(28) In order to be able to completely remove the changeable bushing 10, without previously having to remove a lid base member 40 and the resilient arrangement 15, the changeable bushing 10 has a maximum radial extent W1 which is smaller than the inner extent W2 of the annular disc springs, from which the resilient arrangement 15 is composed. In this instance, the changeable bushing 10 has at the expanded portion 25 or 32 the largest diameter thereof.

(29) The changeable bushing 10 including the three longitudinal portions 31, 32, 33 thereof in the embodiment according to FIGS. 1 and 2 is integral and preferably produced as a rotary component in which only the inner thread 11 additionally has to be produced.

(30) The upper closure of the cylindrical housing 1 is formed by a two-part lid which is composed of the annular lid base member 40 and a closure lid 41. At a lower side of the lid base member 40 facing the piston 5 is the other resilient support 47, that is to say, the resilient support for the end of the resilient arrangement 15 facing away from the piston 5. The lid base member 40 of the two-part lid is securely connected to the cylindrical housing 1, preferably by means of screwing to the cylindrical housing 1.

(31) The lid base member 40 is provided in the centre thereof with a round opening 48 for inserting the closure lid 41. The radial extent W3 of this opening 48 is at least as large as the radial extent W1 of the expanded portion 25 of the changeable bushing 10. Through the opening 48 of the lid base member 40, therefore, it is possible to replace the complete changeable bushing 10, the resilient arrangement 15 remaining in the cylindrical housing.

(32) The closure lid 41 is constructed as an annular disc with an opening 50 of the extent W4, which opening is coaxial with respect to the opening 48 in the lid base member 40. The opening 50 in the closure lid 41 is filled by the journal-like longitudinal portion 33 of the changeable bushing 10. On the whole, therefore, the upper side of the clamping device is composed of the upper side 35 of the lid base member 40, the upper side 51 of the annular closure lid 41 and finally the outer end face 34 of the changeable bushing 10.

(33) Since, according to FIG. 1, the diameter or the radial extent W4 of the opening 50 of the closure lid 41 is smaller than the extent W1 of the radially expanded portion 25 of the changeable bushing 10, when the closure lid 41 is secured, the changeable bushing 10 cannot be ejected upwards out of the clamping device. Such a situation may occur in exceptional cases in the event of failure of the changeable bushing. The securing in the longitudinal direction of the closure lid 41 in the lid base member 40 is therefore an important safety feature.

(34) The closure lid 41 can be locked, for example, by means of rotation in the opening 48 of the lid base member 40. To this end, in the embodiment according to FIGS. 1 and 2, elements of a rotary locking system are formed on the lid base member 40 and on the closure lid 41, in this instance a bayonet locking system. The rotation angle until locking is small and preferably from 15° to 60°. To this end, in the embodiment described here, in the region of the opening 48 there are studs 57 which engage in a locking manner in the manner of a bayonet in grooves 55 which are formed on the periphery of the closure lid 41. In order to close the closure lid 41, it is inserted from above into the opening 48, and then rotated through a rotation angle.

(35) An advantageous aspect for the rotation of the closure lid 41 are finger recesses 56 in the upper side 51 of the closure lid 41.

(36) Further securing of the closure lid 41 is not necessary. The closure lid 41 is also not subjected to loading by the resilient arrangement 15. The latter is supported axially exclusively at the inner side of the lid base member 40 and not against the annular closure lid 41.

(37) FIG. 3 shows another embodiment of the clamping device. The single difference with respect to the first embodiment mentioned is that the changeable bushing 10 is constructed in two parts and is composed of a base member 10A and a carrier ring 32A which can be screwed from above on an outer thread 59 of the base member 10A. In this embodiment, the radial extent W3 of the opening 48 of the lid base member 40 and the radial inner extent W2 of the resilient arrangement 15 is also greater than the radial extent W1 of the carrier ring 32A which forms the radially expanded portion.

(38) FIGS. 4-10 show various other variants for releasably securing the closure lid 41 to the lid base member 40.

(39) In FIG. 4 there is located in the lid base member 40 a resiliently loaded securing element 60 which engages in a resilient manner in a corresponding recess on the periphery of the closure lid 41 and thus locks the lid.

(40) In FIG. 5, the closure lid 41 is provided at the periphery thereof with an outer thread which is screwed into a corresponding inner thread of the lid base member 40 so that a screw connection 61 is produced.

(41) In FIG. 6 there is located in the lid base member 40 a securing element 60 in the form of a resiliently loaded bolt. The bolt protrudes outwards with a portion of the length thereof out of the lid base member 40 and can therefore be pulled outwards for unlocking.

(42) In FIG. 7, there acts as a securing element a stud 57 which is located securely in the closure lid 41 and which can be unlocked simply by means of a bayonet which is formed in the edge of the lid base member 40 by means of slight rotation.

(43) In FIG. 8, a resiliently loaded bar 62 is located so as to be radially movable in the closure lid 41. A component of the bar 62 is a button 63 which releases the securing by being pulled radially inwards.

(44) In FIG. 9, the securing of the closure lid 41 with respect to the lid base member 40 is carried out by means of a magnet 64. As illustrated, this may be secured to the lid base member 40 or alternatively to the closure lid 41.

(45) In FIG. 10, finally, the closure lid 41 is locked by means of a bar 65 which is pivotably supported on the lid base member 40. The bar 65 is illustrated in the locking position thereof in each case.

(46) The specification incorporates by reference the entire disclosure of German priority document 10 2013 113 982.5 having a filing date of Dec. 13, 2013, of which the instant application claims priority.

(47) While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

LIST OF REFERENCE NUMERALS

(48) 1 Cylindrical housing 2 Support pipe 3 Threaded bolt 4 Nut 5 Piston 7 Hydraulic connection 8 Underlay 9 Opening 10 Changeable bushing 10A Base member of the changeable bushing 11 Inner thread 12 Step 15 Resilient arrangement 16 Resilient support 25 Expanded portion 31 Longitudinal portion 32 Longitudinal portion 32A Carrier ring 33 Longitudinal portion 34 Outer end face 35 Upper side 37 Marking 40 Lid base member 41 Closure lid 47 Resilient support 48 Opening 50 Opening 51 Upper side 55 Groove 56 Finger recess 57 Stud 59 Outer thread 60 Securing element 61 Screw connection 62 Bar 63 Button 64 Magnet 65 Bar A Threaded end portion W1 Radial extent W2 Inner extent W3 Radial extent W4 Radial extent