GB2245681A - Hydraulic piston/cylinder device - Google Patents
Hydraulic piston/cylinder device Download PDFInfo
- Publication number
- GB2245681A GB2245681A GB9014458A GB9014458A GB2245681A GB 2245681 A GB2245681 A GB 2245681A GB 9014458 A GB9014458 A GB 9014458A GB 9014458 A GB9014458 A GB 9014458A GB 2245681 A GB2245681 A GB 2245681A
- Authority
- GB
- United Kingdom
- Prior art keywords
- piston
- bolt
- cylinder
- webs
- cylinder device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000012530 fluid Substances 0.000 claims description 6
- 238000007789 sealing Methods 0.000 claims description 3
- 210000003746 feather Anatomy 0.000 claims 2
- 229920001971 elastomer Polymers 0.000 description 6
- 239000005060 rubber Substances 0.000 description 6
- 239000002184 metal Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000004323 axial length Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B31/00—Screwed connections specially modified in view of tensile load; Break-bolts
- F16B31/04—Screwed connections specially modified in view of tensile load; Break-bolts for maintaining a tensile load
- F16B31/043—Prestressed connections tensioned by means of liquid, grease, rubber, explosive charge, or the like
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
- B23P19/04—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes for assembling or disassembling parts
- B23P19/06—Screw or nut setting or loosening machines
- B23P19/067—Bolt tensioners
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
- B25B29/00—Accessories
- B25B29/02—Bolt tensioners
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Hand Tools For Fitting Together And Separating, Or Other Hand Tools (AREA)
Abstract
An annular piston and cylinder device comprises an annular cylinder 4 and a piston 6 therefor, the piston having sidewall portions 17, 18 which extend into the cylinder towards the base thereof in the form of tapering annular webs which together define between them a recess of asymmetrical cross-section. The device is used in a hydraulic nut, bolt or jacking tool. <IMAGE>
Description
Improvements in and relating to fasteners
This invention relates to hydraulically operated fastening devices. It is in particular concerned with hydraulic nuts, bolts and jacking tools used for tensioning bolts, including stud bolts.
Such devices are well known. For example EP-A-91783 discloses an arrangement in which a hydraulic jacking tool is built into the face of a nut, bolt or as a tool in its own right. Common to most devices of this type is an annular body which can be mounted in encircling relation to a bolt which is to be tensioned and which further features an annular piston and cylinder device arranged to exert force on the bolt in an axial direction.
Such devices have been used for many years, for example to secure marine propellers and also in the general industrial fastening field. A typical example is a threaded nut havi g an annular recess machined into one face to constitute the cylinder of a piston and cylinder device. The recess is equipped with an annular rubber tyre and an annular piston. In use, the nut is threaded onto a bolt so that the free end of the piston, which is usually in the form of a flange known as the load ring, abuts the hardware from which the bolt projects. Hydraulic fluid is then admitted into the tyre via a passage through the nut body and the tyre in turn applies thrust to the piston.
This thrust is then transmitted directly to the assembly, causing an increase in the axial length of the bolt together with compression of the assembly. As a result, the nut body is urged away from the assembly and the bolt is subjected to tension. Once a suitable gap has opened up, shims are inserted into the space between the underside face of the nut bod and the load ring so that the tension in the bolt is maintained after the hydraulic pressure is relieved. Similar results may be obtained by building an annular piston and cylinder device into the head of a conventional bolt. For somewhat lighter duty application, it is possible to replace the tyre with conventional piston seals, in the for of rubber rings.
Attempts have been made to use such piston and cylinder devices to tension bolts in applications where relatively high temperatures are experienced. For example there are applications in land based gas and steam turbines and in the nuclear industry. However at the operating temperatures concerned, which ray be in excess of 250C, the use of conventional rubber seals and rubber tyres is impracticable. Prolonged exposure to temperatures above around 150 C cause rapid deterioration of conventional rubbers. Accordingly, in an attempt to overcome this problem, it has been proposed to use a metal tyre. Whilst this solution is susceptible of use at temperatures as high as 5000C, the metal tyre is an expensive item requiring special techniques for its manufacture.
According to this invention an annular piston and cylinder device for use in bolt tensioning apparatus comprises an annular cylinder and a piston therefor, the piston having sidewall portions which extend into the cylinder towards the base thereof in the form of tapering annular webs which together define an annular recess between them, the cross section of said recess being asymmetrical. The webs preferably have substantially the same height in an the direction of the base of the recess. The radially innermost web is preferably thinner than the other web, so as to confer greater flexibility on said web.
The piston is preferably a tight, sliding fit in the cylinder and no conventional rubber seal is employed.
Surprisingly, it has been discovered that b use of the asymmetric profile just mentioned it is possible to configure the webs such that a conventional seal is not required. This means that a piston and cylirder device according to this invention is susceptible of use at elevated temperatures in excess of 5000, there being no conventional seal to deteriorate under such conditions. It has been observed that a symmetrical recess does not provide the sealing performance which is required.
To illustrate the effectiveness of the invention, a sample hydraulic nut according to this invention was pressurised to stress a bolt. The bolted assembly was thereafter subjected to sustained temperatures of the order of 2500C, in an oven. On removing the assembly from the oven, it proved possible to re-energise the nut and only after it had been re-energised several times was there any sign of slight leakage. In view of the lack of a conventional seal, this performance was quite outstanding.
In order that the invention be better understood, a preferred embodiment of it will now be described by way of example with reference to the accompanying drawing in which the sole figure is a cross sectional side viEi through a nut and bolt assembly. In the figure, a bolt 1 having a head 3 is used to clap together an asse...b'.
generally designated 2. It will be appreciated that the bolt extends through an aperture in the assembly 2. The free end of the bolt is provided with a hydraulic nut in the form of cylindrical body 4 having an internal screw thread ccrrespondlng to that of the bDt i. The nut ' ~s screwed down the bolt, a plurality of tommy bar holes 12 being provided for this purpose. That face of the nut which in use contacts the hardware 2 is provided with an annular piston and cylinder device, comprising a cylinder 15 and a piston 6 which is integral with a load ring 7, the latter abutting against the hardware 2. A port 21 is provided for the injection of hydraulic fluid into the cylinder 15; a screw threaded coupling adaptor 22 being provided for this purpose.That portion of the piston 6 which is in use exposed to hydraulic fluid in the cylinder 15 is provided with annular webs 17 and 18 respectively.
Although these are of the same height in an axial direction, the annular recess defined between them is asymmetrical. The effect of the asymmetry is such that the web 17 lying radially inwardly of the device is relatively thin compared with the web 18 lying radially outwardly of it. In consequence of this, the web 17 has increased flexibility over that of the web 18. Initially both webs were machined to be a tight but sliding fit in the cylinder 15. In use, with the load ring 7 flush with the face of the nut 4 (with the piston fully retracted) the nut is screwed down firmly against the hardware 2.
Hydraulic fluid is then admitted through the adaptor 22 and the port 21 to the cylinder 15. The pressure is thereafter increased causing the nut body 4 to be displaced away from the load ring 7, opening up a gap between the components. When the gap width reaches a point at which a desired level of stress in the bolt 1 has been achieved, shims or distance pieces are inserted into the gap. The hydraulic pressure is thereafter relieved, thereby completing the installation procedure.
To remove the nut for example after a prolonged period at elevAted temperature, the procedure is reversed. Oil is admitted under pressure to the cylinder 15; the bolt is subjected to sufficient further stress until the shims or distance pieces can be removed. The hydraulic pressure is thereafter relieved and the nut unscrewed, using the tommy bar holes 12.
Claims (7)
1. A hydraulic nut, bolt or jacking tool comprising an annular cylinder and a piston therefor, the piston having sidewall portions which extend into the cylinder towards the base thereof in the form of tapering webs which together define an annular recess between them, the cross section of said recess being asymmetrical.
2. A device according to claim 1 wherein said webs have substantially the same height in an axially direction.
3. A device according to claim 1 or claim 2 wherein the radially innermost web is thinner than the other web, so as to confer greater flexibility on said innermost web.
4. A device according to any proceeding claim wherein said tapering webs constitute the only fluid sealing means for the piston and cylinder.
5. A device according to any proceeding claim where said webs are constituted as a pair of concentric feather edges directed towards the closed base of the cylinder.
6. A device according to any proceeding claim wherein the piston and cylinder device is built into a nut.
7. A hydraulic nut, bolt or bolt tensioning tool
substantially as herein described with reference to
and as illustrated by the accompanying drawing.
7. A device according to any of claims 1 to 5 wherein the piston and cylinder device is built into the head of a bolt.
8. A piston and cylinder device according to any of claims 1 to 5 wherein the piston and cylinder device constitutes a bolt tensioning tool having an aperture therethrough which is a clearance for a bolt which is to be tensioned and the piston acts upon a screw-threaded puller engaged on the threaded portion of the bolt.
9. A hydraulic nut, bolt or bolt tensioning tool substantially as herein described with reference to and as illustrated by the accompanying drawing.
AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS.
1. A hydraulic nut, bolt or jacking tool comprising an
annular piston and cylinder device (6, 15),
characterised in that the piston has axially directed
sidewall portions constituted by a pair of tapering
annular webs (17, 18) which constitute the only fluid
sealing means for said piston and cylinder device,
the radially innermost web (17) being thinner than
the other web (18) to confer greater flexibility on
said innermost web, the webs together defining
between them an annular recess whose cross-section is
asymmetrical.
2. A device according to claim 1 characterised in that
said webs have substantially the same height in an
axial direction.
3. A device according to any proceeding claim further
characterised in that said webs are constituted as a
pair of concentric feather edges (17, 18) directed
towards the closed base of the cylinder (15).
4. A device according to any proceeding claim
characterised in that the piston and cylinder device
(6, 15) is built into a nut (4).
5. A device according to any of claims 1 to 4
characterised in that the piston and cylinder device
(6, 15) is built into the head of a bolt.
6. A piston and cylinder device according to any of
claims 1 to 3 characterised in that the piston and
cylinder device constitutes a bolt tensioning tool
having an aperture therethrough which is a clearance
for a bolt whic.h is to be tensioned and the piston
acts upon a screw-threaded puller engaged on the
threaded portion of the bolt.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9014458A GB2245681B (en) | 1990-06-28 | 1990-06-28 | Improvements in and relating to fasteners |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9014458A GB2245681B (en) | 1990-06-28 | 1990-06-28 | Improvements in and relating to fasteners |
Publications (3)
Publication Number | Publication Date |
---|---|
GB9014458D0 GB9014458D0 (en) | 1990-08-22 |
GB2245681A true GB2245681A (en) | 1992-01-08 |
GB2245681B GB2245681B (en) | 1994-01-19 |
Family
ID=10678391
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB9014458A Expired - Fee Related GB2245681B (en) | 1990-06-28 | 1990-06-28 | Improvements in and relating to fasteners |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2245681B (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0609924A1 (en) * | 1993-02-05 | 1994-08-10 | Hydra-Tight Limited | Tensioning arrangement |
US6763570B2 (en) | 2001-11-30 | 2004-07-20 | Westinghouse Electric Company Llc | Method of closing a pressure vessel |
CN111590285A (en) * | 2020-04-27 | 2020-08-28 | 咸阳石油化工有限公司 | Method and equipment for disassembling pressure body of piston compressor |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2090941A (en) * | 1980-12-24 | 1982-07-21 | Elspan Int | Hydraulic Jack with Expanding Piston |
EP0200459A2 (en) * | 1985-04-29 | 1986-11-05 | Hedley Purvis Limited | Fluid-actuated piston-cylinder assembly |
-
1990
- 1990-06-28 GB GB9014458A patent/GB2245681B/en not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2090941A (en) * | 1980-12-24 | 1982-07-21 | Elspan Int | Hydraulic Jack with Expanding Piston |
EP0200459A2 (en) * | 1985-04-29 | 1986-11-05 | Hedley Purvis Limited | Fluid-actuated piston-cylinder assembly |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0609924A1 (en) * | 1993-02-05 | 1994-08-10 | Hydra-Tight Limited | Tensioning arrangement |
US5527015A (en) * | 1993-02-05 | 1996-06-18 | Hydra-Tight Limited | Hydraulic tensioning device |
US6763570B2 (en) | 2001-11-30 | 2004-07-20 | Westinghouse Electric Company Llc | Method of closing a pressure vessel |
CN111590285A (en) * | 2020-04-27 | 2020-08-28 | 咸阳石油化工有限公司 | Method and equipment for disassembling pressure body of piston compressor |
Also Published As
Publication number | Publication date |
---|---|
GB2245681B (en) | 1994-01-19 |
GB9014458D0 (en) | 1990-08-22 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20080628 |