METHOD AND APPARATUS FOR MEASURING THE THICKNESS OF RUBBER OVER A METAL REINFORCED LAYER

Abstract: An improved undertread measuring apparatus includes a lift cylinder attached to a support structure which raises and lowers sensors that sense the undertread thickness. The sensors are rotatably connected to a rod such that they rotate out of the way if impacted and automatically realigned. The sensors are also sequenced first one sensor then the other sensor is brought into proper position. As the sensors come into contact with a tire casing which may rotate, two rollers maintain the sensors in alignment.

Description: METHOD AND APPARATUS FOR MEASURING THE THICKNESS OF RUBBER OVER A METAL REINFORCED LAYER Technical Field This invention pertains to the art of methods and apparatuses for use in the retreading of tires, and more specifically to methods and apparatuses for measuring the thickness of rubber overlaying the belt of a tire, such as when an old tread is being ground off of a tire casing. Background Art As a tire is used, the tread of die tire tends to wear off. Sometimes it is desirable to attach a new tread onto the tire casing. The process of putting a new tread on a tire casing is known as retreading. In the process of retreading, it is necessary to grind or buff the rubber overlaying the belt of the tire, known as undertread, to a specific thickness, such as 3/32 ( cm) of an inch, before attaching the new tread. Thus, an important step in the retreading process is measuring the thickness of the undertread. Common problems often encountered in the art deal with the alignment of sensors on a buffer machine used to measure the undertread thickness. If the sensors are knocked out of alignment, for example, by a tire being mounted on a buffer machine, the operator has to realign the sensors. Also, a sequential alignment of the sensors may be desired. A sequential alignment is an alignment in which one sensor comes into operative association with the tire casing before another sensor. The prior does not disclose sequential alignment of sensors. Still another alignment problem is that sensors are displaced out of alignment when they are brought into operative association with a tire casing. The present invention provides methods and apparatuses for measuring the undertread thickness using a sequencing, self-aligning mechanism. Thus, the alignment difficulties inherent in current undertread measuring apparatuses are overcome in a way which is simple and efficient, while providing better and more advantageous results. Disclosure of Invention The present invention, an improved undertread measuring apparatus, includes a lift cylinder which raises and lowers die undertread sensors and is attached to a support structure. This invention also includes a sensor holding plate for holding the undertread sensors and an alignment mechanism. One advantage of the present invention is that it enables the undertread sensors to automatically realign when impacted. If, for example, while the operator was mounting a tire casing, the tire casing was to hit the undertread sensors, they would simply swing out of the way and then realign for undertread measurement. Another advantage of the present invention is that it sequences the undertread sensors. When the operator lowers the undertread sensors, one sensor is brought into operative association with the tire, then, sequentially, another sensor is brought into operative association with the tire. Still another advantage of the present invention is that it self-aligns the undertread sensors when they are brought into operative association with the tire casing. This self-alignment is maintained even during the rotation of the tire casing. Still other benefits and advantages of the invention will become apparent to those skilled in the art to which it pertains upon a reading and understanding of the following detailed specification. Brief Description of Drawings The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail in this specification and illustrated in the accompanying drawings which form a part hereof and wherein: FIGURE 1 is a perspective side view of an improved undertread measuring apparatus of the present invention; FIGURE 2 is a perspective front view of the improved undertread measuring apparatus of the present invention; FIGURE 3 is a perspective bottom view of the improved undertread measuring apparatus of the present invention; FIGURE 4 is an enlarged perspective bottom view of the improved undertread measuring apparatus showing rollers positioned in line with each other; FIGURE 5 is a front view of a prior art undertread measuring apparatus being used with a tire buffer machine; FIGURE 6 is a side view of a prior art undertread measuring apparatus being used with a tire buffer machine; FIGURE 7 is an enlarged front view of a prior art undertread measuring apparatus which has been knocked out of alignment; FIGURE 8 is a front view of a prior art undertread measuring apparatus which cannot be aligned sequentially; FIGURE 9 is an enlarged front view of a prior art undertread measuring apparatus which pivots out of alignment; FIGURE 10 is a front view of an improved undertread measuring apparatus of the present invention, being used with a tire buffer machine; FIGURE 11 is a front view of an improved undertread measuring apparatus of the present invention, showing sequential alignment; FIGURE 12 is an enlarged front view of an improved undertread measuring apparatus of the present invention, showing how the rollers prevent the undertread sensing devices from pivoting out of alignment; FIGURE 13 is a perspective side view of another embodiment of this invention which does not require a steel tube; FIGURE 14 is an enlarged perspective bottom view of another embodiment of this invention which has one undertread sensing device; and, FIGURE 15 is an enlarged perspective bottom view of another embodiment of this invention in which the rollers are not in line with each other. Detailed Description of the Invention Referring now to the drawings wherein the showings are for purposes of illustrating a preferred embodiment of the invention only and not for purposes of limiting the same, FIGURES 1-3 show an improved undertread measuring apparatus 10 for measuring the thickness of rubber overlaying the belt of a tire. This embodiment is for use on tire casings but it is also applicable to tires as well. The improved undertread measuring apparatus 10 includes a sensor-to-bearing support plate 12 which is attached to a linear bearing rail assembly 14. The linear bearing rail assembly 14 is attached to a bearing support plate 16 which is attached to a base plate 18. A lift cylinder 20 is attached at one end 19 to die base plate 18 and at die other end 21 to a lift cylinder bracket 22. The lift cylinder bracket 22 is attached to one end 13 of the sensor-to-bearing support plate 12. A sensor holding plate 24 having a left sensor slot 25 and a right sensor slot 26 is rotatably attached to a rod 28 by a front clevis 30 and a rear clevis 29 which are held in position on the rod 28 by a front split collar 32 and a rear split collar 31. The rod 28 fits inside a steel tube 34. Now, with reference to FIGURE 2, steel tube 34 is attached to die center 36 of the sensor- to-bearing support plate 12. A left undertread sensing device 37, which may be of any type known in the art. For example an electromagnetic transducer which measures the magnetic resistance between itself and the belt of the tire is positioned inside the left sensor slot 25. A right undertread sensing device 38, which may be of any type known in the art, for example an electromagnetic transducer, which measures magnetic resistance between itself and d e belt of the tire, is positioned inside the right sensor slot 26. FIGURE 2 also shows that bearing support plate 16 is positioned at a less than 90° angle θ with respect to line 73 which is parallel with the base 18 and the ground or floor (not shown). Now, with reference to FIGURE 3 which shows a bottom view of the improved undertread measuring apparatus 10, a roller bar 40 is attached to die bottom 23 of the sensor holding plate 24. Mounted to die roller bar 40, such that they can roll freely, are a left roller 41 and a right roller 42. The left roller 41 and the right roller 42 are in line with each other, as shown in FIGURE 4, such that line 35 drawn along the left roller 41 axis of rotation, and line 39 drawn along die right roller 42 axis of rotation, and a third line 43 drawn between the center 45 of the left roller 41 and die center 47 of the right roller 42, are positioned such that line 43 is substantially perpendicular to line 35 and line 39. FIGURES 5 and 6 show a undertread measuring apparatus 50 currently known in the art. The undertread measuring apparatus 50 includes a support assembly 54 arranged perpendicularly widi respect to the ground 71, and a support bracket 51 which supports a left undertread sensing device 55, a right undertread sensing device 56, and a roller 52 for aligning the left undertread sensing device 55 and d e right undertread sensing device 56 with a tire casing 74 that can rotate. The support bracket 51 is attached to a rod 58 which fits inside a metal tube 60 iat is connected to a brace plate 62. A pneumatic cylinder 64 connected to a base 66 and to die brace plate 62 through a pulley system 68, positions the support bracket 51. In the application shown in FIGURES 5 and 6, d e undertread measuring apparatus 50 is being used wid a tire buffer machine 70. A tire casing 74 is shown positioned on the buffer machine 70 such that the undertread measuring apparatus 50 can be used to measure its undertread d ickness. In the operation of the undertread measuring apparatus 50, an operator using the pneumatic cylinder 64, lowers die support bracket 51 so that the roller 52 comes into contact with the tire casing 74. The tire casing 74 may be rotated by the tire buffer machine 70. There are three common alignment problems associated widi the operation of the prior art undertread measuring apparatus 50. The first alignment problem is the necessity of realignment action by the human operator should me left undertread sensing device 55 and the right undertread sensing device 56 be knocked out of alignment. If, for example, the support bracket 51 was bumped by the tire casing 74 as it was being mounted onto die tire buffer machine 70, the left undertread sensing device 55 and the right undertread sensing device 56 would be knocked out of alignment. This alignment problem is illustrated in FIGURE 7 which shows that die distance XI between d e left undertread sensing device 55 and die tire casing 74 and the distance Yl between the right undertread sensing device 56 and die tire casing 74 are not the same. Thus, the operator would have to realign the left undertread sensing device 55 and the right undertread sensing device 56. The second alignment problem, illustrated in FIGURE 8, is that the left undertread sensing device 55 and the right undertread sensing device 56 cannot be aligned sequentially by die support assembly 54. A sequential alignment can be accomplished by a support assembly that allows one undertread sensing device to always come into operative association with the tire casing before e otiier one. However, because the support assembly 54 is perpendicular with respect to a line 72 which is parallel with the ground (not shown in FIGURE 8), when the support bracket 51 is lowered by the pneumatic cylinder (not shown in FIGURE 8), both die left undertread sensing device 55 and the right undertread sensing device 56 may come into operative association with d e tire casing 74 at the same time. This alignment problem is illustrated in FIGURE 8 which shows that die distance X2 between die left undertread sensing device 55 and d e tire casing 74 and die distance Y2 between die right undertread sensing device 55 and the tire casing 74 are me same. This would result in die left undertread sensing device 55 and die right undertread sensing device 56 coming into operative association with the tire casing 74 simultaneously, not sequentially. The third common alignment problem associated with d e operation of the prior art undertread measuring apparatus 50, illustrated in FIGURE 9, is that the roller 52 does not ensure that the alignment of the left undertread sensing device 55 and die right undertread sensing device 56 will be maintained as the roller 52 comes into contact with die tire casing 74 and during the rotation of the tire casing 74. As the support bracket 51 is lowered, die roller 52 comes into contact with die tire casing 74. The support bracket 51 can pivot about the roller 52 causing one sensing device, for example the left undertread sensing device 55, to come into association widi the tire casing 74 at a distance X3 which may be too close to the tire casing 74 for proper alignment. Thus, the left undertread sensing device 55 would be misaligned and would be likely to incorrectly measure me undertread diickness. At the same time, the other sensing device, for example the right undertread sensing device 56, would come into association with the tire casing 74 at a distance Y3 which may be too far from the tire casing 74 for proper alignment. Thus, the right undertread sensing device 56 would be misaligned and would be likely to incorrectly measure the undertread diickness. It will now be explained how the current invention, an improved undertread measuring apparatus 10, shown in FIGURES 1-3, overcomes the alignment problems of the prior art mentioned above. FIGURE 10 shows an improved undertread measuring apparatus 10 being used with a tire buffer machine 70. A tire casing 74 is shown positioned on the buffer machine 70 such that die improved undertread measuring apparatus 10 can be used to measure its undertread thickness. In the operation of the improved undertread measuring apparatus 10, referring now to FIGURES 1-3 and FIGURE 10, an operator using the lift cylinder 20 lowers the sensor holding plate 24 toward the tire casing 74. The problem of having the sensing devices knocked out of alignment and thus requiring operator input to realign, known in the prior art and discussed above, is overcome by die improved undertread measuring apparatus 10. FIGURES 1 and 2 show that die sensor holding plate 24 is rotatably attached to rod 28 by a front clevis 30 and a rear clevis 29. This rotatable attachment allows die sensor holding plate 24 to freely rotate about rod 28. Thus, if d e sensor holding plate 24 was struck by a tire casing as it was being mounted by the operator, the sensor holding plate 24 would simply swing out of me way and dien gravity would bring it back into proper alignment, parallel with a line 73 which is parallel with the ground (not shown in FIGURES 1 and 2), without operator input. The problem of not having a sequential alignment, known in the prior art and discussed above, is also overcome by the improved undertread measuring apparatus 10. As seen in FIGURE 10, the bearing support plate 16 is attached to the base plate 18 at a less dian 90° angle θ with respect to the ground 71 or with respect to a line 15 parallel with the ground 71. In FIGURE 2 this angle θ is shown with respect to line 73 which is parallel with the ground (not shown). This arrangement assures that as the sensor holding plate 24 is lowered, the right undertread sensing device 38 comes into operative association with the tire casing 74 first, then sequentially, die left undertread sensing device 37 would come into operative association with die tire. This sequential alignment is illustrated in FIGURE 11 which shows that as the sensor holding plate 24 is lowered, it moves along a radial line 44 toward the center 46 of the tire casing 74. The sensor holding plate 24 remains positioned parallel wid line 75 which is parallel with the ground (not shown in FIGURE 11) due to the force of gravity and the rotating attachment between the holding plate 24 and the rod 28. As shown in FIGURES 1 and 2, die rotating attachment is effected by the rear clevis 29 and the front clevis 30. FIGURE 11 shows only the front clevis 30. Referring again to FIGURE 11, die distance X4. between the left undertread sensing device 37 and the tire casing 74 is larger than the distance Y4. between the right undertread sensing device 38 and the tire casing 74. Thus, the right undertread sensing device 38 would come into operative association with the tire casing 74 then, sequentially, the left undertread sensing device 37 would come into operative association with the tire casing 74. The alignment problem caused by the support bracket pivoting about the roller, known in the prior art and discussed above, is also overcome by the improved undertread measuring apparatus 10. As shown in FIGURE 3 and FIGURE 12, the improved undertread measuring apparatus 10 has a roller bar 40 with a left roller 41 and a right roller 42. As the sensor holding plate 24 is lowered, first d e right roller 42 then the left roller 41 come into contact with the tire casing. The rollers are sequenced, first the right roller 42 then die left roller 41, just as d e right undertread sensing device 38 and the left undertread sensing device 37 are sequenced. This is shown in FIGURE 11 and discussed above. Referring now to FIGURE 12, since there are two rollers, a right roller 42 and a left roller 41, once they come into contact with the tire casing 74, which may rotate, the right undertread sensing device 38 and die left undertread sensing device 37 are automatically put into proper alignment without die sensor holding plate 24 pivoting out of alignment. Thus, me distance X5 between the left undertread sensing device 37 and the tire casing 74, and die distance Y5 between the right undertread sensing device 38 and die tire casing 74 are always the correct distances for proper alignment. An application may arise where the lateral adjustments possible with steel tube 34 are not necessary, for example in d e event of a standard size tire. In such case, die lateral distance will be constant. In another embodiment of this invention, shown in FIGURE 13, the rod 28 on which the sensor holding plate 24 rotates is directly attached to die sensor-to-bearing support plate 12. In this embodiment, rod 28 is not extensible along its length. Minor length adjustments can be made with die collars 31,32. In this embodiment, no steel tube 34, as shown in FIGURE 1, is required. In another embodiment of mis invention, shown in FIGURE 14, only one undertread sensing device 33 is used. This undertread sensing device 33 could be of any type known in the art, for example an electromagnetic transducer which measures the magnetic resistance between itself and the belt of the tire. In still anodier embodiment of this invention, shown in FIGURE 15, the left roller 41 and die right roller 42 are not in line with each od er. In this embodiment one roller, for example the right roller 42, is located forwardly and laterally of the other roller, for example the left roller 41. A left roller bar 49 is attached to the bottom 23 of e sensor holding plate 24 widi d e left roller 41 mounted to it such diat the left roller 41 can roll freely. A right roller bar 48 is attached to the bottom 23 of the sensor holding plate 24 with the right roller 42 mounted to it such that the right roller 42 can roll freely. The preferred embodiments have been described, herein above. It will be apparent to those skilled in die art that die above methods may incorporate changes and modifications widiout departing from die general scope of this invention. It is intended to include all such modifications and alterations in so far as they come within die scope of d e appended claims or the equivalents thereof. Having thus described the invention, it is now claimed:

Claims: CLAIMS 1. An apparatus for measuring me thickness of rubber overlaying the belt of an associated tire, said apparatus comprising: first sensing means for sensing the thickness of rubber overlaying the belt of the tire; positioning means for positioning said sensing means; supporting means for supporting said first sensing means and said positioning means, said apparatus being characterized by self-aligning means for self-aligning said first sensing means. 2. The apparatus of claim 1 wherein said self-aligning means comprises: a rod having a first end and a second end, said first end of said rod fixedly connected to said supporting means, said second end of said rod extending over said tire; sensor holding means for holding said first sensing means; rotating attachment means, said rotating attachment means fixedly attached to said sensor holding means, said rotating attachment means rotatably attached to said second end of said rod; and, first and second rollers, said first and second rollers fixedly connected to said sensor holding means, said first and second rollers being free-rolling. 3. The apparatus of claim 2 further comprising: second sensing means for sensing the thickness of rubber overlaying the belt of die tire, said second sensing means cooperating with said first sensing means, said sensor holding means holding said first sensing means and said second sensing means. 4. The apparatus of claim 3 wherein said first roller is located forwardly and laterally of said second roller. 5. The apparatus of claim 3 wherein said first roller is substantially in line widi said second roller. 6. An apparatus for measuring the thickness of rubber overlaying the belt of an associated tire, said apparatus comprising: first and second sensing means for sensing the diickness of rubber overlaying the belt of die tire; positioning for positioning said first and second sensing means; supporting means for supporting said first and second sensing means and for supporting said positioning means; said apparatus being characterized by said second sensing means coming into operative association with me tire after said first sensing means comes into operative association with the tire. 7. The apparatus of claim 7 wherein said sequencing arrangement comprises: a base; said base located laterally of die tire; an angled member having a lower end and an upper end, said lower end of said angled member fixedly attached to said base, said angled member making an angle od er than 90° with respect to the ground; a rod having a first end and a second end, said first end of said rod fixedly attached to said upper end of said angled member, said second end of said rod extending over the tire; sensor holding means for holding said first and second sensing means; and, rotating attachment means, said rotating attachment means fixedly attached to said sensor holding means, said rotating attachment means rotatably attached to said second end of said rod, said second sensing means coming into operative association with the tire after said first sensing means comes into operative association with the tire. 8. The apparatus of claim 7 wherein said first sensing means is a first electromagnetic transducer, said first electromagnetic transducer measuring magnetic resistance between said first electromagnetic transducer and d e belt of the tire. 9. The apparatus of claim 8 wherein said second sensing means is a second electromagnetic transducer, said second electromagnetic transducer measuring magnetic resistance between said second electromagnetic transducer and the belt of die tire. 10. An apparatus for measuring a thickness of rubber overlaying a belt of an associated tire, said apparatus comprising: first sensing means for sensing the thickness of rubber overlaying the belt of the tire; positioning means for positioning said first sensing means; supporting means for supporting said first sensing means and said positioning means; said apparatus being characterized by swinging means, said swinging means cooperating with said supporting means for swinging said first sensing means when said first sensing means is impacted. 11. The apparatus of claim 10 wherein said swinging means comprises: a rod having a first end and a second end, said first end of said rod fixedly attached to said supporting means, said second end of said rod extending over the tire; sensor holding means for holding said first sensing means; and, rotating attachment means, said rotating attachment means fixedly attached to said sensor holding means, said rotating attachment means rotatably attached to said second end of said rod, said sensor holding means and said first sensing means rotating around said rod upon impact. 12. The apparatus of claim 11 further comprising: second sensing means for sensing die diickness of rubber overlaying the belt of die tire, said second sensing means cooperating with said first sensing means, said sensor holding means holding said first sensing means and said second sensing means. 13. The apparatus of claim 12 wherein said supporting means has a sequencing arrangement, said sequencing arrangement comprising: a base; said base located laterally of the tire; an angled member having a lower end and an upper end, said lower end of said angled member fixedly attached to said base, said angled member making an angle odier than 90° with respect to the ground, said first end of said rod fixedly attached to said upper end of said angled member, said second sensing means coming into operative association with the tire after said first sensing means comes into operative association with the tire. 14. The apparatus of claim 13 further comprising first and second rollers, said first and second rollers fixedly connected to said sensor holding means, said first and second rollers being free- rolling. 15. The apparatus of claim 14 wherein said first roller is located forwardly and laterally of said second roller. 16. The apparatus of claim 14 wherein said first roller is substantially in line with said second roller. 17. The apparatus of claim 16 wherein said positioning means comprises a first lift cylinder. 18. A method for automatically re-aligning a device knocked out of alignment by a force, said device to be used with an associated tire, said device cooperating with supporting means for supporting said device, a rod having a first end and a second end, said first end of said rod fixedly connected to said supporting means, said second end of said rod extending over the tire, device holding means for holding said device, and rotating attachment means, said rotating attachment means fixedly attached to said device holding means, said rotating attachment means rotatably attached to said second end of said rod, said mediod characterized by die steps of: aligning said device; applying a force to said device or said device holding means, said holding means rotating in a direction corresponding to said force around said second end of said rod, said holding means then in response to die effects of gravity rotating in an opposite direction around said second end of said rod, said holding means in continuing response to the effects of gravity continuing to rotate in a direction corresponding to said force then in die opposite direction until said device holding means stops rotating. 19. A method for sequencing first and second devices to be used widi an associated tire, said first and second devices cooperating widi positioning means for positioning said first and second devices, supporting means for supporting said first and second devices and said positioning means, said supporting means having a base, said base located laterally of the tire, an angled member having a lower end and an upper end, said lower end of said angled member fixedly attached to said base, said angled member making an angle other than 90° with respect to d e ground, a rod having a first end and a second end, said first end of said rod fixedly connected to said supporting means, said second end of said rod extending over the tire, device holding means for holding said first and second devices, rotating attachment means, said rotating attachment means fixedly attached to said device holding means, said rotating attachment means rotatably attached to said second end of said rod, and first and second rollers, said first and second rollers fixedly connected to said device holding means, said first and second rollers being free-rolling, said mediod characterized by the steps of: lowering said device holding means toward the tire with said positioning means until said first roller contacts the tire, said first device coming into operative association with the tire; and, continuing to lower said device holding means, said device holding means rotating around said second end of said rod until said second roller contacts the tire, said second device coming into operative association with the tire. 20. A mediod for self-aligning a first device to be used wid an associated tire, said first device cooperating with positioning means for positioning said first device, supporting means for supporting said first device and said positioning means, a rod having a first end and a second end, said first end of said rod fixedly connected to said supporting means, said second end of said rod extending over an associated tire, device holding means for holding said first device, rotating attachment means, said rotating attachment means fixedly attached to said device holding means, said rotating attachment means rotatably attached to said second end of said rod, and first and second rollers, said first and second rollers fixedly connected to said device holding means, said first and second rollers being free-rolling, said method characterized by die steps of: lowering said device holding means toward die tire with said positioning means until said first roller contacts the tire; and, continuing to lower said device holding means, said device holding means rotating around said second end of said rod until said second roller contacts die tire, said first device coming into proper alignment.

Inventors: PARRISH GARY CHARLES, PARRISH, GARY, CHARLES
Applicants: GOODYEAR TIRE & RUBBER, PARRISH GARY CHARLES, PARRISH, GARY, CHARLES, THE GOODYEAR TIRE AND RUBBER COMPANY
Application year: 1996
Main classification: G01B7
IPC codes: G01B7