GB2306601A - Tightness indicator for threaded fasteners - Google Patents
Tightness indicator for threaded fasteners Download PDFInfo
- Publication number
- GB2306601A GB2306601A GB9521710A GB9521710A GB2306601A GB 2306601 A GB2306601 A GB 2306601A GB 9521710 A GB9521710 A GB 9521710A GB 9521710 A GB9521710 A GB 9521710A GB 2306601 A GB2306601 A GB 2306601A
- Authority
- GB
- United Kingdom
- Prior art keywords
- washer
- indicating means
- indicator
- abutment
- load indicating
- 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.)
- Withdrawn
Links
- 230000015572 biosynthetic process Effects 0.000 claims description 9
- 238000005755 formation reaction Methods 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 5
- 230000002093 peripheral effect Effects 0.000 claims description 4
- 229920003023 plastic Polymers 0.000 abstract description 3
- 239000004033 plastic Substances 0.000 abstract description 3
- 229910000831 Steel Inorganic materials 0.000 abstract description 2
- 239000010959 steel Substances 0.000 abstract description 2
- 239000002184 metal Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000011179 visual inspection Methods 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
- F16B31/02—Screwed connections specially modified in view of tensile load; Break-bolts for indicating the attainment of a particular tensile load or limiting tensile load
- F16B31/028—Screwed connections specially modified in view of tensile load; Break-bolts for indicating the attainment of a particular tensile load or limiting tensile load with a load-indicating washer or washer assembly
Abstract
A tightness indicator for a bolt (10) is in the form of a washer assembly comprising a washer (15), an abutment (16), and an indicator ring (17), the washer (15) having projections (19) which, prior to tightening of the bolt (10), space the washer (15) from the abutment (16) so that the indicator ring (17) can be rotated or moved radially, and which are deformable as the bolt is tightened so that the indicator ring (17) becomes gripped between the washer (15) and the abutment (16); the abutment (16) may be constituted by the head (11) of the bolt (10). The projections (19) are pressed at (21) out of the washer (15), and locate the indicator ring (17). The outer periphery (24) of the indicator ring (17) is serrated or knurled, and the indicator ring (17) is formed of stainless or other steel, or plastics.
Description
Title: FASTENER LOAD INDICATING MEANS
Description of Invention
This invention relates to a means for indicating when a threaded fastener such as a bolt has been tightened to a required degree to apply a required load between components it is connecting.
It is important that threaded fasteners such as nuts and bolts should be correctly tightened. If they are not tightened sufficiently, they may not correctly transfer loads between the components they are connecting, and/or they may work loose in service. If they are tightened too much, they or the components they are connecting may be damaged. Thus there is a requirement for a means for indicating when a threaded fastener is correctly tightened.
According to one aspect of the present invention, we provide a load indicating means for a threaded fastener, comprising spacing means for establishing, initially, a space between surfaces which are urged towards one another as the fastener is tightened, said spacing means being deformable under load exerted by the tighter.ed fastener; and indicating means including a portion disposed in said space and arranged to be trapped between said surfaces after a predetermined amount of deformation of said spacing means.
According to another aspect of the present invention, we provide a load indicating means for a threaded fastener, comprising a washer element; spacing means for establishing, initially, a space between a portion of the washer element and a facing surface of an abutment element, the spacing means being deformable in the direction of the axis of the fastener as the fastener is tightened, and an indicator element including a portion disposed in said space and arranged to be trapped between the washer element and abutment element after a predetermined amount of deformation of the spacing means.
Preferably the space initially defined between the washer element and surface of the abutment element is an annular space at a peripheral portion of the washer element, and the indicator element is of annular configuration. Such an indicator element is free to rotate about the axis of a fastener with which the washer assembly is used, until tightening of the fastener has caused sufficient deformation of the spacing means to prevent such rotation.
The spacing means preferably comprises a number of formations circumferentially disposed about the washer element and pressed axially out of the material thereof.
When such formations are disposed adjacent the inner periphery of the washer element, they may guide the indicator element to ensure that the latter remains at least generally concentric with the washer element.
Preferably the indicator element has an outer peripheral portion which is configured, e.g. serrated, knurled or the like, to make it easy to determine by visual inspection and/or by touch when it is free to rotate relative to the washer element and when it is trapped thereby.
It will be appreciated that in many cases threaded fasteners are tightened by electrically or pneumatically driven impact wrenches. When such tools are used, an indicator element which is free to rotate relative to the washer element will tend to do so in response to vibration created by the tightening tool, and it will be immediately apparent when such rotation ceases to indicate correct tightening of the fastener.
The indicator element may be generally L-shaped in cross-section, having a flat annular portion extending radially into said space and a portion extending substantially perpendicular thereto.
Whilst it would be within the broadest scope of the present invention for the abutment element to be constituted by a fastener part, e.g. the head of a bolt, preferably the invention comprises a washer assembly which includes a washer element and indicator element as aforesaid and also the abutment element.
Preferably the abutment element is generally in the form of a washer and there is retaining means for holding the washer element to the abutment element with the indicator element therebetween prior to use of the washer assembly. Such retaining means conveniently comprises a tubular element of thin and readily deformable material, extending between central apertures of the washer element and abutment element.
The invention will now be described by way of example with reference to the accompanying drawing, which is a diagrammatic cross-section through a washer assembly in accordance with the invention, used with a threaded fastener and illustrating its condition prior to and in use.
In the drawing, a threaded fastener in the form of a bolt is indicated generally at 10, the bolt having a head 11 and shank 12 with a threaded portion 13. A washer assembly indicated generally at 14 comprises a washer element 15, an abutment element 16, and an indicator element 17. The washer element and abutment element are of sheet metal, and prior to use of the washer assembly are held to one another by a thin tubular metal or plastics retaining element 18 which is a press fit in the interior apertures of the washer element and abutment element.
The washer element 15 is provided with spacing means in the form of a number of spacing formations 19 spaced circumferentially about the washer element and formed by a pressing operation or operations using a press tool or tools operating in the direction of arrow 20 and leaving recesses 21 in the opposite face of the washer element. The spacing formations 19 space the washer element from the abutment element, initially, by a gap as indicated at 22 therebetween.
The indicator element 17 is an L-shaped ring, possibly of sheet metal (e.g. stainless steel or some other steel), or possibly of plastics material. it is Lshape in cross-section, having a portion 23 which extends into the gap 22 and a portion 24 which lies adjacent the periphery of the abutment element 16 and preferably is configured, e.g. knurled or serrated, to render it easy to ascertain, by sight or touch, whether the indicator element is free to move rotationally and to a small extent radially relative to the abutment element 16.
The condition assumed by the washer assembly when the bolt is tightened is shown in the right half of the drawing. As the bolt is tightened and the washer assembly is subjected to axial compressive forces between the head of the bolt and whatever component is being held by the bolt, the spacing formations 19 become compressed so that the abutment element approaches the washer element. As the gap 22 therebetween diminishes, there comes a point at which the part 23 of the indicator element within such gap is trapped between the facing surfaces of the washer element and abutment element. Such trapping of the indicator element, indicative of the bolts having been tightened to the required extent, is readily detected and a person tightening the bolt knows that further tightening is unnecessary.
It would be within the broadest aspect of the present invention if the abutment element were to be constituted by the head of the bolt 10 and not to be present as a separate component. In this embodiment, the washer element could be a light press fit on the shank of the bolt with the indicator element held between the washer element and bolt head.
The invention thus provides a simple means for indicating when a threaded fastener such as a bolt has been correctly tightened to apply a required load. The invention may be used to indicate different loads by the substitution of different indicator elements having different thicknesses of their portions which extend into the gap between the washer and abutment elements, the configuration of the washer elements remaining unchanged. Alternatively, washer elements having different configurations of spacing formations could be utilised, the different spacing formations having different characteristics in respect of their deformation in response to axial loads.
The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.
Claims (13)
1. A load indicating means for a threaded fastener, comprising spacing means for establishing, initially, a space between surfaces which are urged towards one another as the fastener is tightened, said spacing means being deformable under load exerted by the tightened fastener; and indicating means including a portion disposed in said space and arranged to be trapped between said surfaces after a predetermined amount of deformation of said spacing means.
2. A load indicating means for a threaded fastener, comprising a washer element; spacing means for establishing, initially, a space between a portion of the washer element and a facing surface of an abutment element, the spacing means being deformable in the direction of the axis of the fastener as the fastener is tightened and an indicator element including a portion disposed in said space and arranged to be trapped between the washer element and abutment element after a predetermined amount of deformation of the spacing means.
3. A load indicating means according to Claim 2 wherein the space initially defined between the washer element and surface of the abutment element is an annular space at a peripheral portion of the washer element, and the indicator element is of annular configuration.
4. A load indicating means according to Claim 2 or Claim 3 wherein the spacing means comprises a number of formations circumferentially disposed about the washer element and pressed axially out of the material thereof.
A A load indicating means according to Claim 4 wherein said formations are disposed adjacent the inner periphery of the washer element and guide the indicator element to ensure that the latter remains at least generally concentric with the washer element.
6. A load indicating means according to any of Claims 2 to 5 wherein the indicator element has an outer peripheral portion which is serrated, knurled or the like.
7. A load indicating means according to any of Claims 2 to 6 wherein the indicator element is generally L-shaped in cross-section, having a flat annular portion extending radially into said space and a portion extending substantially perpendicular thereto.
8. A washer assembly comprising a washer element, abutment element and indicator constituting a load indicating means according to any one of Claims 2 to 7.
9. A washer assembly according to Claim 8 wherein the abutment element is generally in the form of a washer and there is retaining means for holding the washer element to the abutment element with the indicator element therebetween, prior to use of the washer assembly.
10. A washer assembly according to Claim 9 wherein said retaining means comprises a tubular element of thin and readily deformable material, extending between central apertures of the washer element and abutment element.
11. A load indicating means stibstantially as hereinbefore described with reference to the accompanying drawings.
12. A threaded fastener having a load indicating means according to any one of the preceding claims.
13. Anv novel feature or novel combination of features described herein and/or in the accompanying dr.l\vinUs.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9521710A GB2306601A (en) | 1995-10-24 | 1995-10-24 | Tightness indicator for threaded fasteners |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9521710A GB2306601A (en) | 1995-10-24 | 1995-10-24 | Tightness indicator for threaded fasteners |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9521710D0 GB9521710D0 (en) | 1996-01-03 |
| GB2306601A true GB2306601A (en) | 1997-05-07 |
Family
ID=10782782
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9521710A Withdrawn GB2306601A (en) | 1995-10-24 | 1995-10-24 | Tightness indicator for threaded fasteners |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2306601A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2326921A (en) * | 1997-07-04 | 1999-01-06 | Mark Andrew Graham | Collapsable washer |
| WO2013030567A1 (en) * | 2011-08-31 | 2013-03-07 | PHIPPS, Maria Jane | A load-indicating device |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB909775A (en) * | 1960-08-29 | 1962-11-07 | Babcock & Wilcox Co | Improvements in fittings for closing handholes or the like openings in pressure vessels |
| US3960048A (en) * | 1975-03-28 | 1976-06-01 | Illinois Tool Works Inc. | Fastener assembly for creating accurate tension indicating fastener and method of calibrating the same |
| GB1491192A (en) * | 1974-01-28 | 1977-11-09 | Illinois Tool Works | Load-indicating fasteners |
| US4072081A (en) * | 1975-11-14 | 1978-02-07 | Illinois Tool Works Inc. | Tension indicating washer unit |
| GB2217421A (en) * | 1988-04-09 | 1989-10-25 | Stewart Dudley Jelfs | Load indicating device |
| US5280967A (en) * | 1992-03-27 | 1994-01-25 | Donald Travis | Device for indicating the proper installation of fittings |
-
1995
- 1995-10-24 GB GB9521710A patent/GB2306601A/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB909775A (en) * | 1960-08-29 | 1962-11-07 | Babcock & Wilcox Co | Improvements in fittings for closing handholes or the like openings in pressure vessels |
| GB1491192A (en) * | 1974-01-28 | 1977-11-09 | Illinois Tool Works | Load-indicating fasteners |
| US3960048A (en) * | 1975-03-28 | 1976-06-01 | Illinois Tool Works Inc. | Fastener assembly for creating accurate tension indicating fastener and method of calibrating the same |
| US4072081A (en) * | 1975-11-14 | 1978-02-07 | Illinois Tool Works Inc. | Tension indicating washer unit |
| GB2217421A (en) * | 1988-04-09 | 1989-10-25 | Stewart Dudley Jelfs | Load indicating device |
| US5280967A (en) * | 1992-03-27 | 1994-01-25 | Donald Travis | Device for indicating the proper installation of fittings |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2326921A (en) * | 1997-07-04 | 1999-01-06 | Mark Andrew Graham | Collapsable washer |
| GB2326921B (en) * | 1997-07-04 | 1999-07-28 | Mark Andrew Graham | Collapsible washer |
| WO2013030567A1 (en) * | 2011-08-31 | 2013-03-07 | PHIPPS, Maria Jane | A load-indicating device |
| KR20140077890A (en) * | 2011-08-31 | 2014-06-24 | 패스너스 솔루션즈 리미티드 | A load-indicating device |
| CN103975228A (en) * | 2011-08-31 | 2014-08-06 | 紧固件方案有限公司 | A load-indicating device |
| CN103975228B (en) * | 2011-08-31 | 2016-11-02 | 滕斯康有限公司 | Load indicator |
| US9612172B2 (en) | 2011-08-31 | 2017-04-04 | Tenscon Limited | Load-indicating device |
| KR102043812B1 (en) * | 2011-08-31 | 2019-11-12 | 패스너스 솔루션즈 리미티드 | A load-indicating device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9521710D0 (en) | 1996-01-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |