GB2270169A - Testing torque wrenches(e.g.SPS)which sense fastener yield - Google Patents
Testing torque wrenches(e.g.SPS)which sense fastener yield Download PDFInfo
- Publication number
- GB2270169A GB2270169A GB9317500A GB9317500A GB2270169A GB 2270169 A GB2270169 A GB 2270169A GB 9317500 A GB9317500 A GB 9317500A GB 9317500 A GB9317500 A GB 9317500A GB 2270169 A GB2270169 A GB 2270169A
- Authority
- GB
- United Kingdom
- Prior art keywords
- torque
- torque wrench
- force
- rotation
- resilient means
- 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- Withdrawn
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L25/00—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
- G01L25/003—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency for measuring torque
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
Abstract
Apparatus for testing a torque wrench 18 includes comprises a body 10, 21 and resilient means 11 either as part of a mechanism 17, 16, 15, 12 connected between the torque wrench and the body (Fig 2) or acting between a surface 25 adjacent body 21 (Fig 6) and a fixed surface 30. A method is provided wherein resilient means 11 deforms elastically when torque is applied by the torque wrench 18, allowing rotation of the torque wrench and offering increasing resistance to such rotation until sufficient torque is applied to the apparatus to move the body relative to the adjacent surface against the force of gravity and/or the force of friction. The resilient means may be a coil spring 11, a torque meter (not shown) or leaf springs 31. The body may be lifted from the adjacent surface (Fig 2) or may slip on clutch plates 23, 24 compressed by a spring (Figs 4, 6). Mass 10 and distance I may be variable. The method and apparatus simulate the yielding of a fastener under torque and are suitable for testing SPS torque wrenches. <IMAGE>
Description
METHOD OF AND DEVICE FOR TESTING
A TOROUE WRENCH
The invention relates to a method of and a device for testing a torque wrench.
The invention will be discussed with reference to its use in testing an SPS Yield Sensing Torque
Wrench, but it should be appreciated that the method and device of the invention could be used to test any torque wrench.
SPS yield sensing torque wrenches contain a microprocessor unit which senses both the torque applied by the wrench and the angle through which the wrench has moved to apply the torque. By differentiating the torque measurement with respect to the angle of turn, the slope of the load/deflection (torque/angle) curve is found. If the fastener acted upon by the torque wrench is made of steel (or a material with similar yielding characteristics) then when it reaches its yield point the slope of the torque/angle curve decreases sharply as shown in
Figure 1. The microprocessor senses the change and indicates to the user that the fastener is starting to yield.
An SPS torque wrench to date has to be checked for accuracy by checking the electronic components and there has been no test for the unit as a whole. The testing is therefore costly and time consuming and is generally carried out infrequently. The invention seeks to overcome this problem.
The present invention provides a method of testing a torque wrench wherein the torque wrench is used to apply torque to apparatus which uses the torque applied by the torque wrench to move a body relative to an adjacent surface against the force of gravity and/or the force of friction, which apparatus includes resilient means either as part of a mechanism connected between the torque wrench and the body or acting between the said adjacent surface and a fixed surface, which resilient means deforms elastically when torque is applied by the torque wrench, allowing rotation of the torque wrench and offering increasing resistance to such rotation until sufficient torque is applied to the apparatus to move the body relative to the adjacent surface against the force of gravity and/or the force of friction.
In a first method according to the invention the torque wrench is used to apply torque to apparatus which converts the torque to a lifting force acting on the body to lift the body from a supporting adjacent surface, the apparatus having resilient means in the mechanism connected between the torque wrench and the body, which resilient means deforms elastically when torque is applied by the torque wrench to allow rotation of the torque wrench and which resilient means offers increasing resistance to deformation thereby offering increasing resistance to rotation of the torque wrench and allowing increasing lifting force to be applied to the body until the lifting force on the body is sufficient to lift the body from the supporting adjacent surface.
In a second method according to the invention the torque wrench is used to apply torque to apparatus which transmits the torque to a first body which abuts an adjacent surface provided by a member which is held in abutment with the said body wherein the resilient means deforms when torque is applied by the torque wrench to allow rotation of the torque wrench without movement of the first body relative to the adjacent surface and wherein the resilient means offers increasing resistance to deformation and transmits an increasing torque to the first body until the torque applied is sufficient to overcome frictional forces acting between the first body and the adjacent surface and the first body moves relative to the adjacent surface on further rotation of the torque wrench.
The present invention also provides a device for testing a torque wrench comprising: a first body, a second body adjacent to and in contact with the first body, a force input member for rotation by the torque wrench to be tested and a transmission mechanism for transmitting motion from the force input member to the first body, which transmission mechanism transmits the torque applied to the force input member by the torque wrench from the force input member to the first body as a force acting to move the first body relative to the second body against the force of gravity and/or the force of friction, wherein the device includes resilient means either in the transmission mechanism or acting between the second body and a third fixed body, which resilient means deforms when torque is applied to the force input member to allow rotation of the force input member by the torque wrench and which resilient means offers increasing resistance to increasing deformation thereby offering increasing resistance to rotation of the force input member by the torque wrench until the force applied to the first body is sufficient to move the first body relative to the second body against the force of gravity and/or the force of friction.
In a first embodiment of the device the first body is a mass initially at rest on the second body, the transmission mechanism comprises gearing which rotates upon rotation of the force input member and a lever arm which rotates on rotation of the gearing and the resilient means comprises a resilient member interconnected between the lever arm and the mass, wherein rotation of the gearing in one sense causes upward rotation of the lever arm and causes a lifting force to be applied to the mass, which lifting force causes extension of the resilient member until such time as the force applied to the mass is sufficient to lift the mass away from the second body.
Preferably the mass be replaced by masses of varying weights to alter the calibration characteristics of the device.
Additionally or alternatively connection means is provided which allows the resilient means to be connected to the lever arm at a plurality of positions along the lever arm whereby different calibration characteristics of the device can be chosen by connecting the resilient means at different positions on the lever arm.
In a second embodiment of the device the first body comprises at least one plate like member, the second body comprises at least one plate like member held in abutment with the plate like member of the first body and the transmission mechanism transmits a torque to the first body acting to rotate the first body relative to the second body, wherein the resilient means deforms to allow rotation of the torque wrench without rotation of the first body relative to the second body and wherein the resilient means offers increasing resistance to deformation to apply an increasing resisting torque on the torque wrench until the resilient torque applied between the first and second bodies is sufficient to overcome frictional forces acting therebetween and the first body rotates relative to the second body on further rotation of the torque wrench.
Preferably there is additionally provided means for measuring rotation of the force input member.
Preferably the force input member is shaped to match the torque wrench to be tested.
Preferably the resilient means can be controlled to alter its resistance to deformation or may be replaced by various resilient means offering differing resistance to deformation.
Preferably the apparatus used in the method is a device for testing a torque wrench as described above.
A preferred embodiment of the present invention will now be described with reference to the accompanying drawings, in which:
Figure 1 shows a graph depicting the applied torque/extension characteristics of a high strength steel fastener.
Figure 2 shows a first embodiment of a device for testing a torque wrench according to the invention.
Figure 3 shows a graph of the applied torque/extension characteristics measured by an SPS yield sensing torque wrench applying torque to the calibration device of Figure 2.
Figure 4 shows a second embodiment of a device for testing a torque wrench according to the invention.
Figure 5 shows a simplified fragmentary view of a third embodiment of a device for testing a torque wrench according to the invention.
Figure 6 shows a cross-sectional view of the embodiment of figure 5.
The graph of Figure 1 shows the typical applied torque/extension behaviour of a high-strength steel fastener. Up until the point B the fastener behaves elastically and the extension is proportional to the torque applied. Thereafter the material yields and the torsional deflection of the fastener is no longer proportional to the torque applied. Yielding continues until the point C when the material breaks.
An SPS yield sensing torque wrench, as previously mentioned, senses point B to inform the user that the fastener is yielding. The problem to date has been to provide a calibration device which can model the applied torque/extension characteristics of a yielding material.
A device for testing a torque wrench according to the invention is illustrated in Figure 2. It comprises a mass 10, a spring 11, a lever arm 12, a support structure 13, and a transmission mechanism indicated generally as 14.
The transmission mechanism comprises a gear 15 attached to the lever arm 12 such that they rotate together, a gear 16 which meshes with gear 15 and a gear 17 which meshes with gear 16.
The gear 17 is attached to a force input member (not shown) configured to match the torque wrench to be tested.
An SPS torque wrench is shown schematically in
Figure 2 at 18.
The SPS torque wrench 18 is tested by using it to apply torque to the force input member attached to gear 17. The transmission mechanism 15 transmits the torque applied by the torque wrench 18 to the lever arm 12. On rotation of the force input member by the torque wrench 18 the lever arm 12 moves upward through a degree of rotation z 2 proportional to the degree of rotation O1 of the torque wrench. As the lever arm 12 moves upward it extends the spring 11. The downward force on the lever arm applied by the spring increases in proportion to the degree of upward motion of the lever arm 12 (Hooke's Law) until such time as the force exerted by the spring equals the weight of the mass 10. This can be seen on the graph of figure 3 between the points D and E.
After the point E has been reached and the force exerted on the lever arm 12 is equal to the weight of the mass 10, then no further increase in the force on the lever arm 12 is possible, further rotation merely lifting the mass 10 from its rest position upward.
This is seen in the portion E to F of the graph.
The graph of figure 3 is a graph of the torque (force) applied by the torque wrench 18 compared with the extension (rotation b 1) of the torque wrench 18.
It will be seen that the torque/torsional deflection characteristics provided by the testing device of the invention shown in Figure 3 are similar to those of a yielding material. The point E is known since the weight of the mass 10 is known and the length Q (see figure) to the mass 10 can be easily measured using a physical scale. Therefore the readings of the SPS torque wrench can be checked. The wrench can also be checked to ensure that it will accurately warn of yielding of a fastener, the change in slope between the torque/torsional deflection characteristics of the calibration device between the ranges D and E and E and F providing a simulated yielding.
It is preferred that the mass 10 can be simply replaced by other masses of varying weights so that many different calibration points are possible.
It is also preferred that the spring 11 is configured such that its spring rate can be varied or alternatively is easily replacable by springs of different spring rates so that different calibration points may be selected.
Furthermore it is preferred that the lever arm 12 has a series of attachment points such that the mass 10 may be attached at various distances from the axis of rotation of the lever arm such that the torque required to lift the mass 10 is varied.
Whilst in the embodiment described above the calibration device is designed to lift a mass, the applicant envisages that the mass may be dragged along a surface from a state of rest against the force of friction, the frictional force being a force of definite value. Embodiments embodying the principle is shown in Figures 4, 5 and 6.
The device 19 shown in Figure 4 includes a clutch mechanism 20, connected between an input shaft 21 and an output shaft 22. The clutch mechanism includes plates 23 connected to the input shaft 21 for receiving torque, the input shaft 21 having a splined end which engages with notches in the plates 24 such that the plates 24 rotate on rotation of the shaft but are allowed to move axially of the shaft. Plates 24 are connected to a member 25 integral with the output shaft 22 such that the member 25 rotates on rotation of the plates whilst the plates are allowed to move in a direction axial of the input shaft 21 and output shaft 22. A spring 28 biases the plates 24 and 23 into abutment. The output shaft 22 is connected to a normal torque meter (not shown). When torque is initially applied to the input shaft 21 the output shaft 24 rotates with rotation of the input shaft, the torque meter resisting the rotation of the output shaft 22 by applying a resisting torque proportional to the rotation of the output shaft. Eventually sufficient resultant torque will be applied on the plates 23 and 24 to overcome frictional forces acting between the plates 23 and 24 and one set of plates will move relative to the other. The torque wrench will thus sense torsional characteristics equivalent to yielding and should issue a warning to the user.
With knowledge of the radius of contact of the plates 23 and 24, the spring load applied by spring 26 and the coefficient of friction between them the torque required to cause rotation of one relative to the other could be calculated and hence accurate testing carried out.
A second embodiment using friction is shown in
Figures 5 and 6. The second embodiment is identical in many respects to the embodiment of Figure 4.
However, the embodiment of Figure 5 does not require attachment to a torque meter. Instead the member 25 is connected to a housing 30 by leaf springs 31. The leaf springs serve to apply a torque to the member 25 which increases with rotation of the member. As with the embodiment of Figure 4 the torque applied by the torque wrench to the input shaft increases until the torque applied is sufficient to overcome the frictional forces between the plates of the clutch mechanism.
Claims (13)
1. A method of testing a torque wrench wherein the torque wrench is used to apply torque to apparatus which uses the torque applied by the torque wrench to move a body relative to an adjacent surface against the force of gravity and/or the force of friction, which apparatus includes resilient means either as part of a mechanism connected between the torque wrench and the body or acting between the said adjacent surface and a fixed surface, which resilient means deforms elastically when torque is applied by the torque wrench, allowing rotation of the torque wrench and offering increasing resistance to such rotation until sufficient torque is applied to the apparatus to move the body relative to the adjacent surface against the force of gravity and/or the force of friction.
2. A method of testing a torque wrench as claimed in Claim 1 wherein the torque wrench is used to apply torque to apparatus which converts the torque to a lifting force acting on the body to lift the body from a supporting adjacent surface, the apparatus having resilient means in the mechanism connected between the torque wrench and the body, which resilient means deforms elastically when torque is applied by the torque wrench to allow rotation of the torque wrench and which resilient means offers increasing resistance to deformation thereby offering increasing resistance to rotation of the torque wrench and allowing increasing lifting force to be applied to the body until the lifting force on the body is sufficient to lift the body from the supporting adjacent surface.
3. A method of testing a torque wrench as claimed in Claim 1 wherein the torque wrench is used to apply torque to apparatus which transmits the torque to a first body which abuts an adjacent surface provided by a member which is held in abutment with the first body, wherein the resilient means deforms when torque is applied by the torque wrench to allow rotation of the torque wrench without movement of the first body relative to the adjacent surface and wherein the resilient means offers increasing resistance to increasing deformation and applies an increasing torque to the first body until the torque applied by the torque wrench is sufficient to overcome frictional forces acting between the first body and the adjacent surface and the first body moves relative to the adjacent surface on further rotation of the torque wrench.
4. A device for testing a torque wrench comprising:
a first body
a second body adjacent to and in contact with the first body
a force input member for rotation by the torque wrench to be tested and
a transmission mechanism for transmitting motion from the force input member to the first body, which transmission mechanism transmits the torque applied to the force input member by the torque wrench from the force input member to the first body as a force acting to move the first body relative to the second body against the force of gravity and/or the force of friction, wherein
the device includes resilient means either in the transmission mechanism or acting between the second body and a fixed reference, which resilient means deforms when torque is applied to the force input member to allow rotation of the force input member by the torque wrench and which offers increasing resistance to increasing deformation thereby offering increasing resistance to the rotation of the force input member until the force applied to the first body is sufficient to move the first body relative to second body against the force of gravity and/or the force of friction.
5. A device as claimed in Claim 4 wherein the first body is a mass initially at rest on the second body, the transmission mechanism comprises a plurality of gears which rotate upon rotation of the force input member and a lever arm which rotates on rotation of the gears and the resilient means comprises a resilient member interconnected between an end of the lever arm and the mass, wherein rotation of the gears in one sense causes upward rotation of the lever arm and causes a lifting force to be applied to the mass, which lifting force causes extension of the resilient member until such time as the force applied to the mass is sufficient to lift the mass away from the second body.
6. A device as claimed in Claim 5 wherein the mass be replaced by masses of varying weights to alter calibration characteristics of the device.
7. A device as claimed in Claim 5 or Claim 6 wherein connection means is provided which allows the resilient means to be connected to the lever arm at a plurality of positions along the lever arm whereby different calibration characteristics of the device can be chosen by connecting the resilient means at different positions on the lever arm.
8. A device as claimed in claim 4 in which the first body comprises at least one plate like member, the second body comprises at least one plate like member held in abutment with the plate like member of the first body and the transmission mechanism transmits a torque to the first body acting to rotate the first body relative to the second body, wherein the resilient means deforms to allow rotation of the torque wrench without rotation of the first body relative to the second body and wherein the resilient means offers increasing resistance to deformation to apply an increasing resisting torque on the torque wrench until the resultant torque applied between the first and second bodies is sufficient to overcome the frictional forces acting therebetween and the first body rotates relative to the second body on further rotation of the torque wrench.
9. A device as claimed in any one of claims 4 to 7 wherein there is additionally provided means for measuring rotation of the force input member.
10. A device as claimed in any one of claims 4 to 9 wherein the force input member is shaped to match the torque wrench to be tested.
11. A device as claimed in any one of Claims 4 to 10 wherein the resilient means can be controlled to alter its resistance to deformation or may be replaced by various resilient means offering differing resistance to deformation.
12. A method of testing a torque wrench as claimed in Claim 1 wherein the apparatus used comprises a device for testing a torque wrench as claimed in any one of Claims 4 to 11.
13. A device for testing a torque wrench substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB929217989A GB9217989D0 (en) | 1992-08-24 | 1992-08-24 | Method of and device for testing a torque wrench |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9317500D0 GB9317500D0 (en) | 1993-10-06 |
| GB2270169A true GB2270169A (en) | 1994-03-02 |
Family
ID=10720872
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB929217989A Pending GB9217989D0 (en) | 1992-08-24 | 1992-08-24 | Method of and device for testing a torque wrench |
| GB9317500A Withdrawn GB2270169A (en) | 1992-08-24 | 1993-08-23 | Testing torque wrenches(e.g.SPS)which sense fastener yield |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB929217989A Pending GB9217989D0 (en) | 1992-08-24 | 1992-08-24 | Method of and device for testing a torque wrench |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB9217989D0 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CZ297604B6 (en) * | 2000-06-20 | 2007-02-07 | Midko S. R. O. | Device for checking setting of torque wrenches |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107782491A (en) * | 2017-02-19 | 2018-03-09 | 郑州东辰科技有限公司 | Bionical handle clamp support mechanism and torque spanner calibrating installation |
| CN117191596B (en) * | 2023-11-07 | 2024-01-30 | 上海烨柏自动化设备股份有限公司 | Torsion resistance device and torsion resistance method based on track type force arm |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2038006A (en) * | 1978-12-14 | 1980-07-16 | Daimler Benz Ag | Apparatus for checking and adjusting a machine screw-driver |
-
1992
- 1992-08-24 GB GB929217989A patent/GB9217989D0/en active Pending
-
1993
- 1993-08-23 GB GB9317500A patent/GB2270169A/en not_active Withdrawn
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2038006A (en) * | 1978-12-14 | 1980-07-16 | Daimler Benz Ag | Apparatus for checking and adjusting a machine screw-driver |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CZ297604B6 (en) * | 2000-06-20 | 2007-02-07 | Midko S. R. O. | Device for checking setting of torque wrenches |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9317500D0 (en) | 1993-10-06 |
| GB9217989D0 (en) | 1992-10-07 |
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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) |