WO2002082070A1

WO2002082070A1 - Tire zipper fault detection system

Info

Publication number: WO2002082070A1
Application number: PCT/US2002/010300
Authority: WO
Inventors: Lester Homan; Bradley Smith
Original assignee: Pemstar, Inc.
Priority date: 2001-04-04
Filing date: 2002-04-03
Publication date: 2002-10-17

Abstract

The subject invention is a method and system (10) for accurately detecting the existence of the Zipper Effect in a tire. In one embodiment, the system includes a frame which supports a plurality of panels that generally enclose the system. A roller mechanism (24) depends from a panel attached to the top of the frame. An inflation mechanism (5) which includes a pair of arms, a sealing rim rotatively connected to each arm, and a motor (33) extend from a panel located along a bottom portion of the frame. A pair of scanners (34) are positioned within the frame to lie adjacent to and opposing the sidewall of a tire being tested.

Description

TIRE ZIPPER FAULT DETECTION SYSTEM BACKGROUND OF THE INVENTION

As shown in Figure 1 and 2, a tire is generally manufactured with one or more layers of steel cables (sidewall wires) overlaying each other. Each layer is typically angled with respect to the other, and each extends radially across a tire from sidewall to opposing sidewall. The ends of the sidewall wires wrap around bead wires that extend circumferentially around the tire core of each sidewall. If a tire is operated at low pressure for an extended period of time, a phenomenon known as the Zipper Effect may occur. As shown in Fig. 3, prolonged use of underinflated tires create a large amount of stress on the sidewall wires and may cause them to weaken and eventually fracture. If a sidewall wire fractures, a "zipper" is created around the fracture area by the broken sidewall wires. The "zipper" is generally weaker than the rest of the tire, and as such, it is generally more susceptible than the rest of the tire. If a tire having a "zipper" is inflated to full pressure, it can explode, possibly causing great damage to the vehicle and endangering service personnel.

The Zipper Effect is generally only recognizable by visual inspection of the tire if it is severe. In such an instance, the sidewall of the tire has a noticeable deformity. Less severe instances of Zipper Effect, require precise measurement of the sidewall under appropriate pressure in order to detect. Under such conditions, the Zipper Effect can be detected because the profile of the tire changes in the area of the defect. The Zipper Effect is especially problematic in the tire retread industry where tires are continuously being inflated for testing, and where there is generally no tire history to indicate the presence of a "zipper." As such, a system and a method is needed which can accurately detect the Zipper Effect in tires. There is also a further need, especially in a manufacturing setting such as a tire retread facility, for a system which can quickly detect the Zipper Effect in tires.

SUMMARY Accordingly, the subject invention presented is a method and system for accurately and quickly detecting the existence of the Zipper Effect in a tire. In one embodiment, the system includes a frame that generally supports the components comprising the subject invention, a roller mechanism to apply pressure, an inflation mechanism to inflate the tire and drive the rotation of a tire, a pair of scanners to scan the surface of a tire, and a processor to control the operation of the subject invention and to process data.

In one embodiment, the frame supports a plurality of panels that generally enclose the system. The roller mechanism depends from a panel attached to the top of the frame. The inflation mechanism is comprised of a pair of arms, a sealing rim rotatively connected to each arm, and a motor to drive the rotation of a sealing rim. The arms extend from a panel located along a bottom portion of the frame. Each scanner is positioned within the frame to lie adjacent to and opposing the sidewall of a tire being tested.

In one embodiment, each scanner includes a line laser and an image sensor such as a charge coupled device (CCD) array or a CMOS chip. The line laser functions as a light source providing a linear beam of coherent light extending radially across the surface of the sidewall. This beam of light is reflected by the tire back to the scanner wherein the image sensor detects the presence of the reflected light. Variations in surface height will cause some of the light to scatter, displacing its image on the image sensor. The relative height of the surface can be determined by measuring the position of the laser line on the image sensor.

In one embodiment, the processor includes a number of interfaces which enable it to communicate and control the scanners, the inflation mechanism, and the roller mechanism. The processor also includes a number of software applications which are used to analyze the data received from the scanners, and to operate the subject system. An input device, such as a keyboard, enables a user to communicate with the processor and control the operation of the system. A display device also communicates with the processor and enables the processor to display options and data to the user.

In one embodiment, the subject invention contains two processors. Processor 1 generally performs laser data collection and system hardware control, and processor 2 manages the processing and displaying of the sidewall data collected from the lasers onto the display device. One method of testing for the Zipper Effect includes scanning the sidewall of a tire and generating a sidewall height profile from the scan data. The scan data collected is referenced to an index, enabling the system to present data at any point on the sidewall of the tire. The zipper effect is manifested by a distinct profile that becomes evident in the Zipper Effect area of the tire and is not generally manifested elsewhere. Utilizing a graphic function or a color map of the height profile of the sidewall surface produced by the subject invention, a user is able to more accurately and quickly determine the presence of a Zipper Effect in a tire. While several embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description. As will be realized, the invention is capable of modifications in various obvious aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a front view of a tire showing a Zipper Effect area. Fig. 2 is a cross-sectional view of the cable structure of the tire of Fig. 1.

Fig. 3 is a cross-sectional view of the tire of Fig. 1 with pressure applied thereto. Fig. 4 is a cross-sectional view of the tire of Fig. 1 with a line laser applied thereto.

Fig. 5 is a perspective view of one embodiment of a tire zipper fault detection system. Fig. 6 is a front cut-away view of the system of Fig. 5.

Fig. 7 is a side cut-away view of the system of Fig. 5. Fig. 8 is a system diagram of one embodiment. Fig. 9 is a functional flow diagram of one embodiment. Fig. 10a is a diagram of one embodiment of a measuring technique. Fig. 10b is a graphic representation of an image produced by a level surface.

Fig. 10c is a graphic representation of an image produced by an unlevel surface.

Fig. 11 are graphic representations of a zipper effect. DETAILED DESCRIPTION

General Overview

The subject invention is a method and system for accurately detecting the existence of the Zipper Effect in a tire. As shown in Fig. 4, the Zipper Effect can be detected by scanning the tire sidewall and observing the tire sidewall height profile generated from the scan data. The scan data collected is referenced to an index, enabling the system to present data at any point on the sidewall of the tire. The zipper effect is manifested by a distinct profile that becomes evident in the Zipper Effect area of the tire and is not generally manifested elsewhere. The area at the location of the zipper problem is illustrated by a sidewall height variation as compared to the rest of the sidewall. An operator can recognize and detect the defect by observing a graphic representation of the height profile of the sidewall or by observing a color map of the height profile.

For the purposes of explanation only, the disclosed embodiment uses a scanner that utilizes a line laser and an image sensor to scan the surface of the sidewall. As can be readily appreciated by one skilled in the art, there are a number of other methods of scanning known in the art which can be utilized to determine the height profile of the sidewalls. One skilled in the art may adapt ultrasonic methods, pressure transducers, or infrared methods, to name a few, to essentially perform the same functions as the scanner disclosed herein.

System description:

Figs. 5, 6, and 7 discloses one embodiment of the subject Zipper Effect detection system 10. The system 10 includes a frame 12 that supports the other components of the system 10, and generally divides the subject invention into input, testing and output sections respectively. The frame 12 supports and reinforces a plurality of panels 14 surrounding the testing section, the panels 14 providing protection for a user in the event that a tire ruptures when the tire is inflated or during analysis. A track 16 extends longitudinally across the frame 12 from the input section to the output section.

In one embodiment, a plurality of tire handlers 18 engage the track 16 and travel thereon from one section to another. The tire handlers 18 include two rollers 20 that are rotatively connected to a base portion 22 that engages the track.

The rollers 20 receive the tire and permit rotation of the tire. The base portion 22 cooperates with the track 16 to enable movement of the tire handler 18 thereon.

The tire handlers 18 may be moved manually or they may be motorized in a known fashion. In one embodiment, a roller mechanism 24 depends from a panel

14 attached to the top of the frame 12 and applies pressure to the tire. The roller mechanism includes a roller 26 and a transducer (not shown) coupled to the roller

26 for determining the amount of pressure being applied to the tire. The roller mechanism 24 can be actuated onto the tire using an actuator mechanism that is known in the art, or the roller mechanism 24 can be fixedly or adjustably connected to the frame 12. The pressure transducer can be coupled to the roller

26 in a known fashion.

In one embodiment, an inflation mechanism extends from a panel

14 located on the bottom of the testing section of the frame 12. The inflation mechanism 28 includes a pair of arms 30, each extending from the panel 14 along opposite sides of the track 16. A sealing rim 32 is releasably connected to each arm 30. Each sealing rim 32 engages a sidewall, generally sealing the inner portion of the tire. The sealing rims come in various sizes in order to accommodate tires of varying sizes.

An air source 29 cooperates with the sealing rim 32 to inflate a tire.

The air source 29 includes a pneumatic tube 31 that is connected along one end to the air source 29, is carried by the arm to the sealing rim 32, and extends through the sealing rim 32 to communication with the interior portion of the tire. The air source 29 may be activated manually, or may be automatically controlled by the system 10.

A motor 33 is connected to an arm 30 and is rotatively coupled to a sealing rim 32. The motor 33 drives the rotation of the sealing rim 32, causing the tire to rotate. The motor 33 may include a manually adjustable speed control, or it may be automatically controlled by the system 10.

In one embodiment, a pair of scanners 34 are used to determine the contour of a tire sidewall. Each scanner includes a line laser 36 and an image sensor 38. The image sensor can be any optic sensor or a group of optic sensors which is subdivided into regions called pixels or are combined to form an array of pixels. Preferably, the image sensor 38 is a CCD array or a CMOS chip. The laser 36 functions as a light source providing a generally linear beam of coherent light across the surface of the tire. The image sensor captures the light reflecting from the sidewall, and provides data to the system 10 from which a height profile of the surface is calculated. Each scanner is connected to the frame 12, with each generally positioned to oppose the sidewall of a tire resting on the tire handler 18. The scanners 34 can be actuated into proper position relative to a sidewall using an actuator mechanism that is known in the art, or the scanners 34 may be fixedly or adjustably connected to the frame 12.

As shown in Figs. 8 and 9, in one embodiment, a processor 40 is used to communicate with the line laser 36, the inflation mechanism 28, and the roller mechanism 24. The processor 40 is housed in a lower part of the frame 12, behind the panels 14. An input device, such as a keyboard 42, enables a user to communicate with the processor 40 and control the operation of the system 10. A display device 42 is also in communication with the processor 40 and enables the processor 40 to display options and data to the user. The display device 42 also includes a touch screen enabling the user to communicate directly with the processor 40 by touching screen options. The processor 40 includes therein a number of software applications which are used to analyze the data received from the scanners 34, and to generally operate the system 10. The processor 40 also includes a number of interfaces which enable it to communicate with the scanner, the inflation mechanism 28, and the roller mechanism 24.

The processor 40 can be any computer known to those skilled in the art, including standard attachments and components thereof (e.g., a disk drive, hard drive, CD/DND player or network server that communicates with a CPU and main memory, a sound board, a keyboard and mouse, and a monitor). The processor 40 may be any conventional general-purpose single- or multi-chip microprocessor. In addition, the processor 40 may be any conventional special purpose processor such as a digital signal processor or a graphics processor. The microprocessor can include conventional address lines, conventional data lines, and one or more conventional control lines.

As shown in Fig. 8, in one embodiment, the Zipper Effect detection system 10 includes two processors 40. Processor 1 generally performs laser data collection and system hardware control, and processor 2 manages the processing and displaying of the sidewall data collected from the lasers 36 onto the display device 42. As shown in Fig. 9, Processor 1 will have general control over the functional aspects depicted in blocks 1, 5, and 7 and Processor #2 will generally control over the functional aspects depicted in blocks 2, 3, 4, and 6.

Measurement Technique: In one embodiment, the scanner is comprised of a line laser 36 and an image sensor 38, preferably comprising a CCD array or a CMOS chip. The scanner uses the line laser 36 to project a coherent and linear beam of light extending radially along the surface of the sidewall. The projected light is subsequently reflected by the sidewall back toward the scanner wherein it is detected by the image sensor 38.

As shown in Fig. 10a, 10b, 10c, since the angle (θ) between the image sensor 38 and the line laser 36 is known, the relative height of the surface along the line of the laser can be determined by measuring the position of the reflected line on the image sensor 38. The image sensor is sub-divided into regions called pixels. By observing which pixel the laser's image falls on, a height can be assigned to that corresponding point on the surface. Typically, the image sensor 38 creates a string of serial data representing the height of each point in a scan line. For example, a typical CCD array 38 collects 500 points per scan cycle. As the tire is rotated, data is collected at regular intervals (.015" to .1"). This CCD array data is transferred via a video card to the processor 40 wherein the data is graphed creating the height profile of Fig. 11.

As shown in Fig. 11, the lasers 36 collect surface height data around the sidewall surface of the tire. The data collected is referenced to an index (from an encoder mounted on the tire inflator). This enables the system 10 to present data at any point on the sidewall of the tire. This data is mathematically adjusted to form a tire sidewall height profile referenced to a plane. The whole circumference of both sidewalls of the tire is scanned starting with the first index and ending with the last index. The height profile is mapped onto a graph so that the actual profile measurements can be read. Fig. 11 illustrates a tire having the zipper effect along index Ix to Iy. Fig. 11 also illustrates how the profile changes for different indices around the tire. The area at the location of the zipper problem is illustrated by a a sidewall height variation that is noticeably different than the normal curvature produced along the majority of the indices.

As shown in Fig. 11, the zipper effect is manifested by a height profile which is distinct from other areas of the sidewall. Whereas the unaffected areas of the sidewall will generally display a normal curvature, the Zipper Effect area will show a distinct triangular profile. The Zipper Effect is also made clearly evident by creating a color map of the height profile. The color map is created by assigning in a known fashion, a color scale to correspond with the surface height measurement. As shown in Fig. 11 , the surface profile produces a pronounced color changes for the area surrounding the Zipper Effect. An operator can easily recognize and detect the defect by observing the height profile or a color map thereof.

Operation As shown in Figs. 5, 6 and 7, after the tire is placed in the input stage of the system 10, the operator sets the tire parameters from the operator touch screen and/or keyboard. Tire parameters such as sidewall height, tire diameter, scan line step distance, index parameters, and scan time are typically set by the operator. In one embodiment, the tire is then inflated by the inflation mechanism 28. This is achieved by moving the arms towards the tire and enabling the sealing rims to engage the tire. The sealing rims 32 seal the interior portion of the tire, enabling the air source 29 to inflate the tire. Once inflated to the set pressure, the roller mechanism 24 engages the tire and applies pressure thereto, so that the Zipper Effect is made more pronounced. The motor 33 then rotates a sealing rim, causing the tire to rotate. As the tires rotate, the scanners 34 scan the surface of both sidewalls of the tire, and the scan data is sent to the processor 40. The processor then arranges the data into a number of indexes.

Fig. 11 illustrates a scan profile for one side of a tire sidewall. The distance between the first and last index represents the circumference of the sidewall of the tire. The indexes Ix and Iy represent an area of operator interest where a zipper profile may exist. The operator can examine the height profiles at various indices as part of the analysis by selecting a point on the monitor. Point Iz illustrates one such profile in a graph so that the actual profile measurements can be read.

When the analysis is complete the operator releases the tire and the tire is moved to the third (output) stage where the operator removes the tire from the system 10.

While the present invention has been described with reference to several embodiments thereof, those skilled in the art will recognize various changes that may be made without departing from the spirit and scope of the claimed invention. Accordingly, this invention is not limited to what is shown in the drawings and described in the specification but only as indicated in the appended claims. Any numbering or ordering of elements in the following claims is merely for convenience and is not intended to suggest that the ordering of the elements of the claims has any particular significance other than that otherwise expressed by the language of the claim.

Claims

CLAIMSWe claim:

1. A tire testing apparatus comprising: a tire inflation mechanism; and a sidewall scanner.

2. The apparatus of claim 1 , wherein the scanner includes a line laser and a CCD array.

3. The apparatus of claim 1, wherein the scanner includes a line laser and a CMOS chip.

4. The apparatus of claim 1, further comprising a roller mechanism.

5. The apparatus of claim 1, and further comprising a processor in communication with the scanner.

6. The apparatus of claim 5, wherein the processor receives scan data from the scanner and calculates the surface height of a point on the sidewall of the tire.

7. The apparatus of claim 1, wherein the processor receives surface height data of a sidewall and creates a color map representing the surface height profile.

8. A tire testing apparatus comprising: an inflation mechanism; a scanner having a laser and an image sensor; and a processor in communication with the scanner.

9. The apparatus of claim 8, and further comprising a rolling mechanism.

10. The apparatus of claim 9, wherein the rolling mechanism includes a transducer coupled to the drive roller.

11. The apparatus of claim 8, wherein the image sensor is a CMOS chip.

12. The apparatus of claim 8, wherein the image sensor is a CCD array.

13. The apparatus of claim 8, and further comprising frame defining an input, testing, and output section, and further comprising a track extending between the input, testing and output section.

14. The apparatus of claim 13, and further comprising a tire handler having a base portion movably engaged to the track and a pair of rollers rotatively engaged to the base portion.

15. The apparatus of claim 8, wherein the inflation mechanism includes a pair of opposing sealing rims, each rim disengageably connected to an arm.

16. The apparatus of claim 15, and further comprising an air source in cooperation with the sealing rim.

17. The apparatus of claim 16, and further comprising a motor coupled to a sealing rim and connected to an arm.

18. A method of testing a tire comprising: inflating a tire; and scanning the tire's sidewalls.

19. The method of claim 18, wherein the step of scanning includes applying a linear beam of coherent light from a laser onto the sidewall.

20. The method of claim 19, wherein the step of scanning includes collecting light reflected by the tire onto an image sensor, and further comprising the additional step of calculating a surface height profile of the sidewall from the output of the image sensor.

21. The method of claim 20, wherein the step of scanning includes providing a line laser as a light source.

22. The method of claim 21, and further comprising the step of mapping the surface height profile onto a color scale and creating a color map.

23. The method of claim 18, wherein the step of inflating includes sealing the interior of the tire.

24. The method of claim 23, and further comprising the step of rotating the tire.

25. The method of claim 18, and further comprising the step of applying pressure to the tire.

26. The method of claim 17, and further comprising the step of analyzing the output of a scanner for an indication of Zipper Effect.

27. A method of testing a tire for the zipper effect comprising: inflating a tire to a set pressure; applying a set pressure to the tire; rotating the tire; scanning the surface of a sidewall of the tire as it rotates; and creating a sidewall height profile.

28. The method of claim 26, and further comprising mapping the sidewall height profile onto a color scale and creating a color map.

29. The method of claim 26, and further comprising the step of comparing the the sidewall height profile to find a zipper effect profile.

30. The method of claim 25, wherein the step of scanning includes firing a line laser at a sidewall of the tire and receiving laser light reflected by the tire through an image sensor.

31. The method of claim 25, wherein the step of inflating the tire includes the step of placing a sealing structure on the tire core.

32. A method of testing a tire comprising scanning the surface of a tires sidewall to determine a height profile.