GB2589089A - A surface testing device - Google Patents

A surface testing device Download PDF

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Publication number
GB2589089A
GB2589089A GB1916562.0A GB201916562A GB2589089A GB 2589089 A GB2589089 A GB 2589089A GB 201916562 A GB201916562 A GB 201916562A GB 2589089 A GB2589089 A GB 2589089A
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United Kingdom
Prior art keywords
test strip
testing device
test
movement
pressure pad
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Granted
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GB1916562.0A
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GB2589089B (en
GB201916562D0 (en
Inventor
Robert Bunting David
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Surface Control Ltd
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Surface Control Ltd
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Priority to GB1916562.0A priority Critical patent/GB2589089B/en
Publication of GB201916562D0 publication Critical patent/GB201916562D0/en
Publication of GB2589089A publication Critical patent/GB2589089A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N19/00—Investigating materials by mechanical methods
    • G01N19/02—Measuring coefficient of friction between materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
    • G01B5/28—Measuring arrangements characterised by the use of mechanical techniques for measuring roughness or irregularity of surfaces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N19/00—Investigating materials by mechanical methods
    • G01N19/08—Detecting presence of flaws or irregularities

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Force Measurement Appropriate To Specific Purposes (AREA)

Abstract

A device for testing a surface’s friction comprises housing 1 containing a test strip 6 which contacts test surface 7. Pressure pad 5 applies simultaneous longitudinal and normal forces to test strip 6. Upon application of said forces, the test strip 6 will move when the coefficient of friction between test strip 6 and test surface 7 is less than the coefficient of friction between the test strip 6 and pressure pad 5. The device includes means for sensing and indicating said movement. The device may include a lever 2 and bearing 3 as a means for applying pressure with pressure pad 5. The housing 1 may comprise a plurality of surface-engaging rubber feet. The movement detection means may comprise optical and magnetic sensors. The movement indicator signal may be visual, audible or wirelessly transmitted to a remote device. Also provided is a method for using the device and recording the results of the movement indication.

Description

A Surface resting Device T his invention pertains general ly to the field of surface testing devices, and in particular, surface testing devices for testing the effectiveness of surface treatments.
Slip is a problem encountered on a number of different floor surfaces. Any hard surfaces on which people may stand or walk such as floors, baths, shower trays and other surfaces that have surface finishes that have inherently low coefficients of friction, can often cause people to slip and fall. Such a surface can be made safer by modifying it by chemical or mechanical means to increase the surface friction. Typical ly, the surface is treated with chemical formulations to help to improve grip. A material that has been treated will have an increased roughness due to surface irregularities typically created by either chemically altering the surface or by mechanical ly abrading the surface.
The treatments may become less effective over time due to wear or repeated cleaning of the surface. A means is required to check whether the original treatment is still effective or whether it needs to be repeated to make the surface safer again. The measurement of surface friction is well-known and many devices and methods exist to do it However the devices are frequently expensive and complicated to manufacture, calibrate and use. T hey may also be difficult to set up and are often operated by unqualified people, especially where a large number of tests must be performed quickly such as for the testing of hotel baths.
The prior art shows a number of devices which attempt to address these needs in various ways. By definition all standard measurements of friction are a ratio between a force normal to the surface being measured and the force needed to move the object applying the normal force over the surface or move the surface past the object applying the normal force. Typical ly friction measuring devices will al l have this characteristic and differ in how the forces are created and measured.
GB 2438731(Collins et al) discloses a machine based on the widely used pendulum tester that uses a replaceable shoe and measures the energy loss when the shoe is moved over a surface to be measured. The machine is portable and can measure the dynamic coefficient of friction of a wide range of surfaces. It dos not measure the static coefficient of friction However, although lighter and smaller than the purely mechanical pendulum tester that it supersedes it is still relatively large and only suitable for measuring level and flat surfaces. It is also requires a sophisticated inbuilt processing device to convert the force and speed measurements to standard friction values. It is therefore expensive and unsuited to measuring curved surfaces or small areas such as are typical ly found in baths and shower trays. The replaceable shoe is not the measurement reference and this differs f mm the approach in the proposed invention.
US 2013,167,614 (Miller et al) discloses a method of detecting the change in surface friction of an interchangeable sample surface being polished by the change in force and consequent lateral movement of a sensor in contact with the moving polished surface. However this machine is not portable and is designed to work with samples of the material to be tested and it is the sample that is moved. The technique is not applicable to large fixed surfaces such as floors or baths.
US 5,490,410 ( L OR E NT ZEN & WET TRE AB) discloses a system for measuring the static and dynamic friction of a sample of paper in the form of a strip which is pulled between opposing friction surfaces and the force needed to move the paper initial ly (the static friction) and to move it continuously (the dynamic friction) are measured. Although the system contains a strip of material superficial ly similar in arrangement to the proposed invention the strip is not the measuring agent but the thing being measured and the techniques cannot be applied to large solid surfaces such as floors and baths. The system includes sensitive equipment for measuring the forces involved and calculating the Whilst some of the prior art appears to address the issue of testing various surfaces to determine surface characteristics, and therefore to understand whether further surface treatments ought to be applied, these devices are somewhat cumbersome, often unintuitive to the untrained user, and tend to incorporate numerous moving and complex parts, increasing the chance of device failure. They are often too bulky to be used on small surface areas or require separate samples of the surface to be measured to be prepared, and are difficult to carry about and to store.
Preferred embodiments of the present invention aim to provide a portable surface testing device for determining the surface characteristics of a surface in situ, to determine the presence of the surface changing treatment by comparing the static coeffici ent of the surface with a known reference, and to provide a reliable device for measuring small areas of test surface, that is intuitive to use, portable, and easy to store when not in use.
According to one aspect of the present invention, there is provided a surface testing device for testing the slip resistance of a test surface, the surface testing device comprising: a housing a test strip for engaging with a test surface, said test strip comprising a pressure pad engaging surface and a test surface engaging surface; a pressure pad for exerting a longitudinal force and a simultaneous normal force onto the test strip; a r uvement detecting means operatively connected to the test strip for detecting any longitudinal movement of said test stri p when engaged with a surface; and, an indicator within the housing for indicating when any longitudinal movement of the test strip has occurred, whereby the test strip is configured such that, in use, the pressure pad exerts the longitudinal force and the simultaneous normal force onto the test strip, forcing the test strip onto the test surface, and when the coefficient of friction between the test surface engaging surface and the test surface is less than the coefficient of friction between the pressure pad engaging surface and the pressure pad, the movement detecting means detects movement of said test strip and the indicator indicates that movement of said test strip has occurred.
The movement detecting means may comprise a mechanical pointer, whereby said mechanical pointer is configured to move position when movement of the test strip is detected.
Preferably, the movement detecting means comprises an electrical switch.
The electrical switch may comprise a pair of terminals that are configured to join together when movement is detected.
The electrical switch may comprise an optical sensor.
The electrical switch may comprise a magnetic sensor.
Preferably, the indicator comprises an illuminated signal.
The illuminated signal may comprise a light emitting diode.
Alternatively, the indicator may comprise an audible alert.
In yet a further embodiment the indicator may comprise a wireless transmitter for transmitting a wireless signal to a remote device.
The pressure pad may be mounted to a lever, such that, in use, when a user applies a force to the lever, the pressure pad applies the normal force and simultaneous longitudinal force to the test strip.
The test strip may be releasably secured to a rotatable support means, whereby, in use, said rotatable support means is rotated to engage the movement detecting means, thereby indicating when movement of the test strip has occurred.
The lever may be operatively connected to a leaf spring, for returning the lever to a start position.
Preferably, the housing comprises a plural ity of surface engaging feet.
The feet may comprise rubber.
Preferably, the test strip is interchangeable.
The pressure pad may be metal.
A method of testing a surface using the aforementioned surface testing device, comprising the steps of: a. mounting the test strip to the housing; b. placing the housing onto a test surface so that the test strip is engaged with said test surface; exerting a force to the pressure pad for exerting a longitudinal force and a simultaneous normal force onto the test strip; For a better understanding of the invention and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which: Figure 1 shows one embodiment of surface testing device in side view, with a test strip mounted in position for engaging with a test surface; Figure 2 shows the surface testing device embodiment of Figure 1 i n section view, showing the position of the test strip after operation on the test surface, when a movement detecting means has not detected movement of the test strip, and an indicator is in an off position; Figure 3 shows the surface testing device of Figure 1 i n section view, showing the position of the test strip after operation on the test surface, when the movement detecting means has detected movement of the test strip, and the indicator is in an on position; Figure 4 shows one embodiment of test strip with surface engaging surface comprising surface characteristics that are different to a pressure pad engaging surface; and, Figure 5 shows an isometric view of one embodiment of surface testing device showing an underside view, and the test strip mounted to a rotatable support means.
The present invention addresses the issues outlined above by means of a device that uses as a reference a test strip that has upper and lower surfaces with particular predetermined frictional characteristics.
The test strip interacts with the surface to be tested by means of a smooth metal pressure pad that presses the test strip onto the test surface whilst simultaneously exerting a longitudinal force that attempts to move the test strip across the surface. Any movement of the strip is detected. A lack of movement indicates the presence of the treatment and a significant movement indicates the absence of the treatment.
In order for the invention to work in this manner the lower surface of the test strip is prepared such that it has a high coefficient of static friction with a treated surface and a lower coefficient of static friction with an untreated surface. The upper surface of the test strip is prepared so that it has a coefficient of static friction with the pressure pad that is between the high and low levels of the coefficients for the lower surface of the test strip and the test surface.
If the surface is treated the strip will not move because the coefficient of static friction is higher between the lower surface of the strip and the test surface than it is between the pressure pad and the upper surface of the strip. Conversely if the test surface is untreated the strip will move with the pressure pad because the upper coefficient of static friction is larger than the coefficient of static friction between the lower test strip surface and the test surface.
In a typical embodiment the lower surface of the test strip will have a surface with raised features that interact with the surface roughness features created by the surface treatment. This results in a high frictional resistance. However the material of the test strip is chosen to be softer than the material under test and therefore it will not abrade or otherwise modify the test surface. As a result if the surface features created by the treatment are absent there is a much lower level of static friction between the test strip and the test surface. Preferably the test strip will be formed from plastic selected from Poly I acti c Acid ( P L A) or from Polyethylene ( P E) or from Polyethylene terephtha I ate (PET) or from Polyvinyl Chloride (PV C) or from Polypropylene (PP) or other material chosen according to the surface to be tested.
The movement of the strip may be detected by any convenient means such as a mechanical pointer or an electrical switch that can use mechanical contacts or optical sensors or any other convenient means for detecting the movement. If movement is detected then a failure indication is made and if no movement is detected then a pass indication is made. The indication may be by any convenient means such as an ill uminated signal, a sound, or a radio transmission to a remote device that records the result or any combination of these and other convenient methods.
The preparation of the upper and lower surfaces of the test strip may be different according to the material to be tested and therefore different test strips may be supplied to test different materials using the same invention.
The use of such a test strip means that any device that is an embodiment of the invention does not need to measure any forces or distances and is therefore simple and robust in construction. The device does not need to be calibrated and has a minimal number of moving parts that improves reliability and reduces the cost The contact area is very small and if it occurs the movement is approximately two mi II i metres. This means that the invention can be used to measure the condition of curved surfaces and small areas. A test surface sample can be supplied with the device that enables the operation to be checked. If the test strip becomes worn or damaged correct operation will be restored by simply replacing the strip from spare test strips carried with the device.
In the figures like references denote like or corresponding parts.
As shown in Figure 1, an outer case 1 supports a lever 2 that is pivoted on a bearing at 3. Rigidly attached to the lever is the pressure pad Sand an indicator light 4 is on the upper surface of the lever. The test strip 6 is mounted on a rotatably movable support 8 so that it is between the pressure pad and the test surface 7. Mounted on the movable support 8 is a contact strip which together with the contact 9 forms an electrical switch. When the lever 2 is pressed to the horizontal position it activates the electrical switch 10 which connects the electrical storage battery to the electrical circuits. The upper contact of the switch 10 acts as a leaf spring to return the lever to the upper position when it is released and also to cause pressure to be applied to the pressure pad as the lever is depressed. The rear of the case 1 has feet 11 on which the rear of the device is supported and which act as a fulcrum so that when the lever 2 is pressed against the resistance of the spring 10 the whole device tends to rotate about the fulcrum thereby causing pressure to be applied to the test strip 6 by means of the pressure pad 5.
Figure 2 shows the arrangement of the device after the lever 2 has been pressed to test a surface 7 that has been treated. T he friction between the test strip 6 and the test surface 7 is high and therefore the test strip 6 does not move. The pressure pad 5 slides over the upper surface without moving the strip 6. The switch 9 remains open and the switch 10 is closed by the action of the lever 2. This results in the indicator lamp 4 being ill uminated and showing the treatment on the test surface is effective.
Figure 3 shows the arrangement of the device after the lever 2 has been pressed to test a surface where the treatment is absent. Because the friction between the test strip 6 and the test surface 7 is low the movement of the pressure pad 6 causes the test strip to move across the surface 7. T his causes the movable block 8 on which the test strip 6 is mounted to rotate and the contact arm for switch 9 mounted on the block completes the circuit with the other contact for switch 9. The closure of this switch 9 prevents the indicator lamp 4 from illuminating thereby indicating that the treatment is absent from the test surface 7.
Figure 4 illustrates the construction of the test strip 13 showing a low friction upper surface 14 and a high friction test surface 15 created by a raised surface pattern on the lower surface of the test strip.
Figure 5 shows a general view of this embodiment as an aid to understanding the position of the various components referred to above.

Claims (19)

  1. CLAIMS: 1. A surface testing device for testing the friction characteristics of a test surface, the surface testing device comprising: - a housing; - a test strip for engaging with a test surface, said test strip comprising a pressure pad engaging surface and a test surface engaging surface; - a pressure pad for exerting a longitudinal force and a simultaneous normal force onto the test strip; -a movement detecting means operatively connected to the test strip for detecting any longitudinal movement of said test strip when engaged with a surface; and, - an indicator within the housing for indicating when any longitudinal rrovement of the test strip has occurred, whereby the test strip is configured such that in use, the pressure pad exerts the longitudinal force and the simultaneous normal force onto the test strip, forcing the test strip onto the test surface, and when the coefficient of friction between the test surface engaging surface and the test surface is less than the coefficient of friction between the pressure pad engaging surface and the pressure pad, the movement detecting means detects movement of said test strip and the indicator indicates that movement of said test strip has occurred.
  2. 2. A surface testing device according to claim 1, wherein the movement detecting means comprises a mechanical pointer, whereby said mechanical pointer is configured to move position when movement of the test strip is detected.
  3. 3.
  4. 4.
  5. 5.
  6. 6.
  7. 7.
  8. 8.
  9. 9.A surface testing device according to claim 1, wherein the movement detecting means comprises an electrical switch.A surface testing device according to cl ai m1, wherein the electrical switch comprises a pair of terminals that are configured to join together when movement is detected.comprises a magnetic sensor.A surface testing device according to any one of the preceding claim, wherein the indicator comprises an illuminated signal.A surface testing device according to claim 7, wherein the illuminated signal comprises a light emitting diode.A surface testing device according to any one of the preceding claims, wherein the indicator comprises an audible alert.A surface testing device according to claim 1, wherein the electrical switch comprises an optical sensor.A surface testing device according to claim 1, wherein the electrical switch
  10. 10. A surface testing device according to any one of the preceding claim, wherein the indicator comprises a wireless transmitter for transmitting a wireless signal to a remote device.
  11. 11. A surface testing device according to any one of the preceding claim, wherein the pressure pad is mounted to a lever, such that in use, when a user applies a force to the lever, the pressure pad applies the normal force and simultaneous longitudinal force to the test strip.
  12. 12. A surface testing device according to any one of the preceding claim, wherein the test strip is releasably secured to a rotatable support means, whereby, in use, said rotatable support means is rotated to engage the movement detecting means, thereby indicating when movement of the test strip has occurred.
  13. 13. A surface testing device according to claim 11, wherein the lever is operatively connected to a leaf spring, for returning the lever to an open configuration.
  14. 14. A surface testing device according to any one of the preceding claim, wherein the housing comprises a plural ity of surface engaging feet.
  15. 15. A surface testing device according to claim 14, wherein the feet comprise rubber.
  16. 16. A surface testing device according to any one of the preceding claims, wherein the test strip is interchangeable.
  17. 17. A surface testing device according to any one of the preceding claim, wherein the test strip has upper and lower surfaces that have been prepared to have surface characteristics such that the lower surface will interact with the surface to be tested in a known manner and the upper surface will interact in a known manner with a pressure applying surface that is a component of the device in which the test strip is used.
  18. 18. A surface testing device according to any one of the preceding claims, wherein the pressure pad is metal.
  19. 19. A method of testing a surface using the surface testing device of claims 1 to 18, comprising the steps of: a. mounting the test strip to the housing; b. switching on the surface testing device to activate it c. placing the housing onto a test surface so that the test strip is engaged with said test surface; d. exerting a force to the pressure pad for exerting a longitudinal force and a simultaneous normal force onto the test strip: e. recording the result as indicated by the indicator
GB1916562.0A 2019-11-14 2019-11-14 A surface testing device Active GB2589089B (en)

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GB2589089A true GB2589089A (en) 2021-05-26
GB2589089B GB2589089B (en) 2022-05-25

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07270304A (en) * 1994-03-29 1995-10-20 Kowa Gomuito Seizo Kk Slide tester
US5490410A (en) * 1991-09-20 1996-02-13 Ab Lorentzen & Wettre Process and a device for measuring static and dynamic friction of sheet-shaped materials
JPH09236537A (en) * 1996-03-01 1997-09-09 Oriental Photo Ind Co Ltd Method and apparatus for measuring surface slipperiness
US20150369585A1 (en) * 2013-02-07 2015-12-24 Commissariat A L'energie Atomique Et Aux Energies Alternatives Device for measuring the surface roughness of a surface

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5490410A (en) * 1991-09-20 1996-02-13 Ab Lorentzen & Wettre Process and a device for measuring static and dynamic friction of sheet-shaped materials
JPH07270304A (en) * 1994-03-29 1995-10-20 Kowa Gomuito Seizo Kk Slide tester
JPH09236537A (en) * 1996-03-01 1997-09-09 Oriental Photo Ind Co Ltd Method and apparatus for measuring surface slipperiness
US20150369585A1 (en) * 2013-02-07 2015-12-24 Commissariat A L'energie Atomique Et Aux Energies Alternatives Device for measuring the surface roughness of a surface

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Publication number Publication date
GB2589089B (en) 2022-05-25
GB201916562D0 (en) 2020-01-01

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