GB2146774A - Grip measuring device - Google Patents
Grip measuring device Download PDFInfo
- Publication number
- GB2146774A GB2146774A GB08324740A GB8324740A GB2146774A GB 2146774 A GB2146774 A GB 2146774A GB 08324740 A GB08324740 A GB 08324740A GB 8324740 A GB8324740 A GB 8324740A GB 2146774 A GB2146774 A GB 2146774A
- Authority
- GB
- United Kingdom
- Prior art keywords
- measuring device
- gripping force
- grip
- receiver
- jaws
- 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- Withdrawn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
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
- G01L5/0061—Force sensors associated with industrial machines or actuators
- G01L5/0076—Force sensors associated with manufacturing machines
- G01L5/0085—Force sensors adapted for insertion between cooperating machine elements, e.g. for measuring the nip force between rollers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
- G01L1/225—Measuring circuits therefor
- G01L1/2262—Measuring circuits therefor involving simple electrical bridges
Landscapes
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Force Measurement Appropriate To Specific Purposes (AREA)
Abstract
A grip measuring device comprises a measuring unit 10 locatable between the jaws of a chuck to be rotated with it, and including means to measure the gripping force being exerted on it, and a transmitter 24 arranged to transmit a signal proportional to the measured gripping force to a receiver 26, the receiver being spaced from the transmitter and connected to an indicator 28 of the gripping force. The measuring unit may include a resistance bridge 16 including strain gauges. Its voltage output is applied to a voltage to frequency converter 22 via an amplifier 20. Thus L.E.D receives half square waves, and sends out light pulses at a frequency proportional to the grip of the jaws to a stationary phototransistor 26. The pulses received are counted. and from the rate of the pulses the display 28 gives a figure proportional to the gripping force. <IMAGE>
Description
SPECIFICATION
Grip measuring devices
The present invention relates to grip measuring devices and in particular to devices arranged to measure the gripping force exerted by the jaws of a chuck when the chuck is rotating.
When a workpiece is held by the jaws of a chuck, if the workpiece is not held with a sufficient force when the chuck rotates, the workpiece may slip or be released from the chuck. Slipping or release of the workpiece can not only be extremely dangerous to personnel in the immediate vicinity but can also damage the workpiece.
The gripping force exerted by the jaws under a given input power may decrease as a result of normal wear in the mounting of the jaws, bad maintenance and poor lubrication.
Furthermore, the gripping force may decrease when the chuck starts to rotate, as the centrifugal force acting on each of the jaws urges them away from gripping the workpiece. Obviously, as the rotational speed increases, the centrifugal force acting on the jaws increases and the gripping force exerted on the workpiece decreases. Accordingly there is a need to measure the gripping force which will be exerted on a workpiece while the chuck is rotating.
A prior proposal for measuring the gripping force exerted by the jaws of a rotating chuck has comprised a measuring unit held between the jaws, which is thus caused to rotate with the chuck. A stationary lead is electrically connected to the rotating measuring unit by a slip ring assembly provided on the measuring unit. The measuring unit produces an electrical signal proportional to the force being exerted by the jaws, and the signal is fed via the slip ring assembly and the stationary lead to a display unit which gives an indication of the gripping force. Whilst this arrangement is able to give a reading of the gripping force exerted by the rotating jaws of the chuck, the slip ring assemblies are expensive to produce and are prone to wear, particularly if the central axis of the slip ring assemblies is not precisely coincident with the rotational axis of the chuck.
Furthermore, as the measuring unit with the slip ring assemblies has to be so accurately mounted on the chuck, it is difficult and time consuming to set up the measuring device.
According to one aspect of the present invention, a grip measuring device comprises a measuring unit adapted to be located between the jaws of a chuck, the measuring unit including means arranged to measure the gripping force being exerted on the measuring unit and a transmitter arranged to transmit a signal proportional to the measured gripping force to a receiver, the receiver being spaced from the transmitter and connected to an indicator arranged to give an indication of the gripping force being exerted on the measuring unit. With such a measuring device, there is no contact between one component which rotates relatively to a stationary component, and accordingly the measuring device does not suffer any wear in that respect.Furthermore, the device may be quickly and easily mounted in the jaws of a chuck as there is no need to precisely align the rotating component with the stationary component in order to reduce the frictional wear which will take place between the components.
The means arranged to produce the gripping force may be adapted to produce a voltage proportional to the gripping force, and the measuring device may include a converter adapted to convert the voltage to a frequency proportional to the voltage. The frequency produced by the converter provides a convenient way of transmitting the signal to the receiver for example, either in the form of electromagnetic waves or via a light emitting diode mounted on the measuring unit. Where a light emitting diode is used to transmit the signal, the receiver may comprise a phototransistor arranged to be located adjacent to, but spaced from the light emitting diode.The converter may be adapted to produce a frequency in the form of a half square wave which allows the light emitting diode to produce light in pulses, each pulse being for the required duration and being of generally constant luminous intensity.
There may be a frequency measuring device connected between the receiver and the indicator, which frequency measuring device may comprise a gate which counts pulses from the receiver.
The indicator may comprise a digital display arranged to give a figure proportional to the gripping force.
It will be appreciated that the measuring device, although primarily intended for measuring the gripping force of the jaws of the chuck whilst the chuck is rotating, may also measure the same gripping force while the chuck is stationary.
The invention may be carried into practice in various ways, but one embodiment will now be described by way of example and with reference to the accompanying diagram of a grip measuring device.
The grip measuring device comprises a measuring unit 10 which, in use, is mounted in the jaws of a chuck so as to be able to rotate with the chuck, and a receiving unit 1 2 which is spaced from the unit 10 and remains stationary when the chuck is rotating.
The measuring unit 10 includes a battery power source 14 which applies a voltage across a resistance bridge 1 6 via a voltage stabiliser 1 8. The resistance on one side of the bridge 1 6 remains generally constant, its function being to nullify or reduce any mis readings which might tend to be produced on alteration of the temperature or humidity in which the measuring unit operates. The resistance on the other side of the bridge 1 6 varies in dependence upon the load exerted by the jaws of the chuck on the measuring unit. One way of enabling the resistance to so vary is to include strain gauges into the bridge.
The voltage produced by the bridge 16, which is proportional to the load being exerted by the jaws, is fed through a voltage amplifier 20 and then through a voltage to frequency converter 22 which produces a half square wave whose frequency is proportional to the grip of the jaws. The half square wave is supplied to a light emitting diode 24 which produces pulses of light at the frequency dictated by the output of the converter 22.
The receiving unit 1 2 includes a phototransistor 26 which is positioned so that it can receive light from the light emitting diode 24.
When the photo-transistor 26 receives pulses of light from the diode 24, a gate provided in the receiving unit counts the pulses, and from the rate of pulses counted the display 28 produces a figure proportional to the gripping force of the jaws.
Claims (11)
1. A grip measuring device comprising a measuring unit adapted to be located between the jaws of a chuck, the measuring unit including means arranged to measure the gripping force being exerted on the measuring unit and a transmitter arranged to transmit a signal proportional to the measured gripping force to a receiver, the receiver being spaced from the transmitter and connected to an indicator arranged to give an indication of the gripping force being exerted on the measuring unit.
2. A grip measuring device as claimed in claim 1, in which the means arranged to measure the gripping force is adapted to produce a voltage proportional to the gripping force, and the measuring device includes a converter adapted to convert the voltage to a frequency proportional to the voltage.
3. A grip measuring device as claimed in claim 2, in which the signal is transmitted in the form of electromagnetic waves.
4. A grip measuring device as claimed in claim 2, in which the signal is transmitted in the form of light.
5. A grip measuring device as claimed in claim 4, in which the measuring device includes a light emitting diode.
6. A grip measuring device as claimed in claim 5, in which the receiver comprises a photo-transmitter arranged to be located adjacent to, but spaced from, the light emitting diode.
7. A grip measuring device as claimed in claim 5 or claim 6, in which the converter is adapted to produce a frequency in the form of a half square wave which allows the light emitting diode to produce light in pulses, each pulse being of the required duration and being of generally constant luminous intensity.
8. A grip measuring device as claimed in any one of claims 2 to 7, in which a frequency measuring device is connected between the receiver and the indicator.
9. A grip measuring device as claimed in claim 8, in which the frequency measuring device comprises a gate which counts pulses from the receiver.
10. A grip measuring device as claimed in any one of the preceding claims, comprising a digital display arranged to give a figure proportional to the gripping force.
11. A grip measuring device constructed and arranged substantially as herein described, with reference to the accompanying drawing.
1 2. A method of measuring the gripping force of the jaws of a chuck, comprising locating between the jaws of the chuck a measuring unit including means to measure the gripping force exerted on the measuring unit and a transmitter arranged to transmit a signal proportional to the measured gripping force, and positioning a receiver to receive the transmitted signal, the receiver having an indicator arranged to give an indication of the gripping force.
1 3. A method of measuring substantially as herein described with reference to the accompanying drawing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08324740A GB2146774A (en) | 1983-09-15 | 1983-09-15 | Grip measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08324740A GB2146774A (en) | 1983-09-15 | 1983-09-15 | Grip measuring device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8324740D0 GB8324740D0 (en) | 1983-10-19 |
| GB2146774A true GB2146774A (en) | 1985-04-24 |
Family
ID=10548838
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08324740A Withdrawn GB2146774A (en) | 1983-09-15 | 1983-09-15 | Grip measuring device |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2146774A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2606145A1 (en) * | 1986-11-04 | 1988-05-06 | Skirail Ind | Method and device for checking a clamping force, intended in particular for a releasable grip for a cable transportation device |
| EP0588776A2 (en) * | 1992-09-16 | 1994-03-23 | Valmet Paper Machinery Inc. | Method and device for measurement of the nip force and/or of the nip pressure in a nip formed by a revolving roll or by a band employed in the manufacture of paper |
| EP1591766A2 (en) * | 2004-04-28 | 2005-11-02 | SENSTRONIC Deutschland GmbH | Optical measuring device and force sensor |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB664160A (en) * | 1949-01-20 | 1952-01-02 | Gen Electric Co Ltd | Improvements in or relating to electric measuring, testing or indicating means |
| GB1576006A (en) * | 1970-12-08 | 1980-10-01 | Secr Defence | Methods of monitoring machines |
-
1983
- 1983-09-15 GB GB08324740A patent/GB2146774A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB664160A (en) * | 1949-01-20 | 1952-01-02 | Gen Electric Co Ltd | Improvements in or relating to electric measuring, testing or indicating means |
| GB1576006A (en) * | 1970-12-08 | 1980-10-01 | Secr Defence | Methods of monitoring machines |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2606145A1 (en) * | 1986-11-04 | 1988-05-06 | Skirail Ind | Method and device for checking a clamping force, intended in particular for a releasable grip for a cable transportation device |
| EP0588776A2 (en) * | 1992-09-16 | 1994-03-23 | Valmet Paper Machinery Inc. | Method and device for measurement of the nip force and/or of the nip pressure in a nip formed by a revolving roll or by a band employed in the manufacture of paper |
| EP0588776A3 (en) * | 1992-09-16 | 1994-04-13 | Valmet Paper Machinery Inc. | Method and device for measurement of the nip force and/or of the nip pressure in a nip formed by a revolving roll or by a band employed in the manufacture of paper |
| US5379652A (en) * | 1992-09-16 | 1995-01-10 | Valmet Paper Machinery Inc. | Method and device for measuring the nip force and/or nip pressure in a nip |
| EP1591766A2 (en) * | 2004-04-28 | 2005-11-02 | SENSTRONIC Deutschland GmbH | Optical measuring device and force sensor |
| EP1591766A3 (en) * | 2004-04-28 | 2006-06-07 | SENSTRONIC Deutschland GmbH | Optical measuring device and force sensor |
| US7249522B2 (en) | 2004-04-28 | 2007-07-31 | Senstronic Deutschland Gmbh | Optical measuring device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8324740D0 (en) | 1983-10-19 |
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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) |