CA2024957A1 - Tire tread grooving apparatus and method - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

TIRE TREAD GROOVING APPARATUS AND METHOD

A cutting head assembly (28) is diametrically opposed to a foot assembly (30) which is capable of gripping a portion of the tire. A fluid cylinder (32) is attached at one end to the foot assembly (30) and has a movable shaft extending from the other end. The shaft is connected to the cutting head assembly (28) for moving it between a first and second portion with respect to the foot assembly (30). The cutting head assembly (28) has a cutting blade (38) attached thereto. The cutting blade (38) is substantially "U"
shaped having each free end attached to a conductive material, such as blocks of brass. The conductive material is then attached to an electrical power source (24) to provide heating of the blade. The cutting blade is placed such that it engages a portion of the tire tread while the foot assembly engages a portion of the tread and/or sidewall. Once the blade is heated the fluid cylinder forces the blade through the tread towards the foot assembly.

Description

~2~9~7 TIRE TREAD GROOVING APPARATUS AND METHO~

BACKGROUND OF THE INVENTION

This invention relates generalLy to the grooving o a tire tread surface on a cured tire. More particularly this invention relates to a portable tire tread grooving apparatus and method of grooving a tire tread surface on a tire. This invention being especially useful in the field grooving of tire tread surfaces of off-the-road tires.
Various methods and apparatus have been employed in the past to groove tire treads for both highway and off-the-road tires, for example as illustrated by U.S.
Patents: 4,081,016; 4,237,955; 4,311,182; 4,782,881;
S~ 3 and 4,805,684. Each of these devices results in a relatively large and fixed machine, and may require a large investment. On the other hand, it is also known in the art to carve tires, especially passenger tires, by a hand-held carving knives. Off-the-road tires are generally designed for specific type of operations and/or vehicles. For example, certain types of tires are better suited for farming, logging, mining, etc. A
tire designed for these different types of conditions may give excellent service for a majority of either customers or applications but may result in less than desirous performance based upon the physical conditions in which it operates. For example, a tire may be operating in conditions where traction characteristics are not as good as desired. One method that can be used to enhance the traction of the tire is by cutting additional grooves or deepening existing grooves in the treadface.

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2~2~3~7 In one trial, a regrooving tool used typically on passenger tires was employed to regroove a 36.00-51 E4 off-the-road tire. During this trial, ~he regrooving tool required two men to operate it and took two hours to regroove the tire while damaging three blades.
These devices made the operation labor intensive, time consuming and expensive. This was clearLy unsuitable for applications where tires needed to be removed from trucks and regrooved. This would be especially true in the use of large earthmover dump trucks where the capital cost of these trucks is such that any downtime must be kept to a minimum.
It is therefore desirous to be able to regroove tires in the field where the labor and the material costs can be kept to a minimum while also reducing the time of operation. A device, according to applicants' invention, in one trial regrooved a similar 36.00-51 E4 tire in a similar manner in about twenty-five percent of the time required in the other trial while being also able to use a cutting blade for more than one tire.

SUMMARY OF THE INVENTION
_ It therefore is desirous to provide a tire tread grooving apparatus which is portable.
It is also desirous to provide a tire tread grooving apparatus which is capable of being opera~ed by one individual.
It is also desirous to provide a tire tread grooving apparatus which is capable of cutting grooves in tire treads of large off-the-road tires.
Therefore according to one aspect of the invention an apparatus for grooving tires comprises a means having ~ ~irst and second end for spanning a portion of - .

' 2~2~57 the tire tread surface; a means for cutting carried by said first end of said means for spanning; and a means for moving said means for cutting towards said seco~d end, across said tread sur~ace in a predetermined path, for removing material from said tread surface.
In accordance to a~lother aspect of the invention an apparatus for grooving tires may comprise a means for engaging a portion of the tread surface of the tire;
a cutting head assembly diametrically opposed to, said means and supported for movement with respect to said means for engaging between a first position at which the cutting head is retracted from said means and a second position at which the cutting head is closer to the means for engaging than at the first position;
a cutting means carried by said cutting head assembly for removing portions of said tread surface; a means for moving said cutting head assembly between said first and second positions; and wherein portions of said tread are removed as said cutting head asse~bly moves ~rom said first to said second positions.
In accordance to yet another aspect of the invention an apparatus for grooving tires may comprise a foot assembly having a means for gripping a tire and a handle; a fLuid cylinder having a cylinder body attached at one end to said foot assembly, a shaft portion extending from another end of said cylinder body and capable of movement between first a second position; a cutting head assembly attached to said shaft portion of said fluid cylinder, having a cutting blade releasably connected at each end to a conductive material, and a handle; a means to adjust the force and speed of movement between said first and second positions of the shaft and the cutting assembly; a means for actuating and/or stopping the movement 2n2~9~7 between said positions; adjustable electrical power supply; and a means for connecting the electrical power supply to said conductive material of said cutting head assembly.
In accordance to yet another aspec~ o ~he invention a method o~ providing grooves in a ~ire ~read surface may comprise the steps o~: (a) causing a grooving tool having a cutting head assembly and a engaging means to extend apart from one another; (b) placing said grooving tool along a tire tread surface such that the cutting blade will travel along the desired path to be cut and that the engaging means is in contact with a portion of said tread or sidewall of said tire; (c~ actuating said grooving tool to cause said cutting blade to engage the tire tread surface to be cut; (d) heating said cutting blade; and (e) actuating said grooving tool to force the hot cutting blade through the rubber of said tread surface and towards said engaging means.
DESCRIPTION OF THE DRAWINGS
The following is a brief description af the drawings in which like parts may bear like reference numerals and in which:
Fig. 1 is a perspective elevational view of a tire grooving apparatus according to one embodiment of the invention;
Fig. 2 is a fragmentary view of the grooving tool according to the embodiment of Fig. l;
Fig. 3 is an elevational view of the cutting head assembly taken substantially along line 3-3 of Fig. 2;
Fig. 4 is an elevational and exploded view of ~he block assemblies of Fig. 3;

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2~2~g~7 Fig. 5 is a schematic diagram of the pneumatic operation according to the embodiment of Fig. l;
Fig. 6 is an elevational view of a cutting blade according to one aspect of the invention;
Fig. 7 is an elevational view o the cutting blade of Fig. 6 taken along lines 7-7;
Fig, 8 is a cross-sectional view of the cutting blade taken along line 8-8 o Fig. 7;
Fig. 9 is a perspective view of the operation of the grooving tool of Fig. l;
Fig. 10 is an alternate embodiment of the invention utilizing manual operation.

DESCRIPTION OF THE INVENTION
Referring to Fig. 1, there is illustrated a tire grooving apparatus shown generally as reference numeral 20. The grooving apparatus preferably comprises a grooving tool, shown generally as reference numeral 22, an electrical power supply 24, and an activation means, such as a foot operated switch 26.
The grooving tool 22 comprises a cutting head assembly, a foot assembly, and a fluid cylinder assembly, such as an air cylinder, each shown generally as reference numerals 28, 30, and 32 respectively. The grooving tool 22 is connected to the electrical power supply 24 by electrical cables 34, while the foot switch 26 is connected to the electrical power supply by a cable 36.
Now referring to Figs. 2, 3, and 4 the cutting head assembly 28 is provided with a cutting blade 38 which is retained in a pair of blocks of a conductive material, such as brass 40. It is preferred that there is at least two cutting blade locating slots 42, 44 provided in each brass block 40. It is preferred that - - :
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~û2~7 one of the cutting blade locating slots 42 is inclined at an angle while the other cutting blade locating slot 44 is substantially vertical. The use of at least ~wo different cutting blade retaining slots 42, 44 permits either a straight sided or an angled blade to be used, This avoids distortion of the blade when clamping either type of blade to the brass blocks and therefore prolongs blade life. Each slot is cut deep enough into the brass block to permit a predetermined amount of the blade 38 to protrude therefrom. In the preferred embodiment, the slots are cut completely through the blocks to permit the free ends of the cutting blade to project above the brass blocks, thus permitting a wide range of cutting depths from a single design of blade.
lS The cutting blade 38 is restrained by steel clamp plates 46 to the brass blocks 40. The steel c~amp plates are releasably fastened to the brass blocks to permit the removal and change of cutting blades. For example, the steel clamp plates may be fastened by screws 48. The steel clamp plates 46, e~tend above the brass blocks 40 and are provided on the top edge of each with a lip 50.
Free ends of the cutting blade projecting above the brass blocks can present a potential safety problem should the operator have his hand in this area.
Therefore, the clamp plates 46, extend above the brass block to form a safety guard. The provision of the lip 50 on the clamp plates 46, is to help ensure that no portion of the blade can extend above the clamp plate.
It is preferred that the leading edges of the brass blocks 40 and the clamping plates 46, are chamfered to prevent the grooving tool from jamming when following the contour of the tire being grooved or cut.

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2~24~7 Electrical current is supplied from the electrical power supply by the electrical cables 34 which are connected to the brass blocks 40. The current then passes from the blocks 40 to the cutting blade whlch in turn heats the cutting blade. The cutting blade may be further retained by a pair o~ clamping screws 52, one of which each passes through the respective brass bLock 40 to engage the cutting blade 38. It is also preferred that the clamping screws 52 which bear against the cutting blade are comprised of the same conductive material, such as brass. These clamping screws 52 provide positive contact with the blade and the brass block which permits maximum current flow while reducing or preventing arcing and while also assisting in retaining or locking the blade into place.
Each brass block 40 is fastened, for example by nuts and bolts 53, to a channel 54 having a slot 56 located therein to permit the lateral movement o~ the blocks. In this manner, the cutting head assembly is able to adapt or be used with a number of different types of cutting blades. An insulating means 58 is provided between a brass block 46 and the channel 54 and between the nut/bolt 53 and the channel 54 to electrically insulate each from the other. For example, the insulating means 58 may be PTFE spacers.
The channel 54 is then attached to a support member 60 such as a square steel tube. The attachment of the channel 54 to the support member may be reinforced by a plate 62 connec~ing the support member 60 and the channel 54 together. Attached to the steel tube may be a cable guide 64 in which the electrical cables 34 may pass. Further attached at one end of the suppor~
member 60 is a handle 66 with an air control valve 68 attached thereto.

- 202~7 The use of the brass blocks 40 to retain the blade 38 provides a heat sink, such that the blade remains cool at the point 70 where it emerges from the brass blocks. This point 70 is the maxlmum stress point on the blade 38 which is quickly distorted i~ overhea~ed.
The use of the brass blocks 40 also allows the use of a larger diameter bolt and stud to better secure the electrical cables 34 and the brass blocks 40 to the support member 60. This provides a rugged construction which makes it more suitable for field use, such as mine sites and other similar locations where shifting spanners are commonly employed.
It is preferred that the lower portion of the channel 54 is inclined at an angle A with respect to the cutting blade 38. In other words, the lower portion 72 of the channel 54 is not perpendicular to the cutting blade 38 but rather is angled at an angle which is slightly less than being perpendicular theretoO The angular relationship of the channel to the cutting head assists the tool following the contour of the tire. It is preferred that the angle A be approximately 5 degrees less than a line 71 which would be perpendicular to the cutting blade 38.
The foot assembly 30 is provided with a handle 74 having an air control valve 76 attached thereto. The foot assembly 30 is further comprised by a means 78 for gripping the tire during the tire cutting operation.
More specifically, the means for gripplng the tire may be furnished with a plurality of spikes 80 which are used to grip the tire tread lugs.
The fluid cylinder assembly 32 comprises a shaft portion 82 which connects at one end to the cutting head assembly 28 and extends into the cylinder body 84 at the other end. The fluid cylinder assembly 28 is 2~2l~3~7 connected to the foot assembly at one end of the ai~
cylinder body 84 by a plurality of threaded rods 85.
It is preferred that the sha~ por~ion or piston rod 82 is attached to the cutting head assembly 28 such ~hat some rotation of the cutting head is possibLe.
The use of an air cylinder allows the operation of grooving a tire to be possible for one person.
Furthermore, the air cylinder helps to extend the life of a cutting blade. This is provided by maintaining an even or constant force which makes it possible to reduce the blade te~perature thereby increasing its operating life. While an air cylinder is preferable in order to provide the portability of the tire grooving apparatus, it is within the scope of this invention that the air cylinder could be replaced with another 1uid means such as for example a hydraulically operated cylinder.
Referring now to Figs. 2 and 5 the air cylinder 84 is a double acting non-cushioned air cylinder. For example, an air cylinder having a 3" diameter bore and a typical stroke of 15" has been used. However, the bore size and stroke may vary according to different applications. Two ports of the air cylinder body 84 are provided ~ith adjustable control valves 86 which can restrict the exhaust but are freely opened to input air. Each adjustable control valve 86 is then connected to an air control valve 68, 76 such as a poppet valve, for supplying air to each port. With an air control valve 68, 76 in the rest or unactuated position, there is no air supplied to the port and the port itself is exhausted to the atmosphere. When an air control valve 68 is actuated, air is then supplied to the port and the exhaust is closed. A self-venting 88 three-way adjustable reducing valve supplies air to " ~. ~

2~9~7 the air control valves 68, 76 through a T-~unction.
The use of a pressure reducing valve on the pneumatic supply line ensures that the ~orce applied to the cutting head can be controlled while the use o an adjustable exhaust restrictor valve on both cylinder ports permits control of the cutting head speed in both directions. The air supply is then attached to the self-venting valve for providing air to the system.
The operation of the tire grooving apparatus is by means of the two separate air control valves 58, 76.
Depressing air control valve 68 advances the cutting head assembly while depressing the other air control valve 76 retracts the cutting head assembly. The use of the two separate air control valves requires that both hands of the operator are required to operate the movement of the cutting head assembly thereby keeping the hands of the operator well clear of the cu~ting blades.
Referring now to Figs. 6, 7, and 8 there is illustrated a typical cutting blade 38 according to one embodiment of the invention. The cutting blade has substantially a U-Shape profile wherein the vertice 90 has been rounded or blunted by a radius R. It is preferred that the cutting blade 38 is cold-formed from a suitable hardened steel such as produced by Viking Flex. Cutting blades have been formed from steel strips of 1.5mm thick and 15mm wide. The steel strip has been formed such that the cutting blade has an overall length L of approximately 90mm, a height H of approximately 120mm, a width W of about 15mm, and a radius R of about 20mm. The cutting edge 92 of the cutting blade 38 is double tapered to a predetermined point T. Cutting blades have been produced in which the point T is located from between 3-5mm rom the end 92 of the cutting blade.

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2~2'~7 A method of operation of the invention will be explained in conjunction with Fig. 9. First, before the tire grooving apparatus is to be used the various controls need to be preset. The voltage should be set at such a level as to ensure that the blade does not overheat and distort. This setting, however, has to be balanced by the air pressure required to give the highest operatlng speeds. Exhaust restrictor valves are also adjusted and provide additional control to the cutting head speeds~ particularly when the cutting head is being retracted.
The required groove outline is first marked in chalk 100 on the tread surface 102. With the air cylinder piston rod in the extended position, the foot 30 and cutting head assemblies 28 are placed in the required positions to ensure that the cutting blade 38 will travel along the groove outline 100. The foot assembly 30 may grip a portion of the tread or the tire sidewall 104.
The air control valve 68 is then actuated so that the piston rod 82 retracts, and the blade 38 makes contact with the lug or portion 106 of the tread surface 102 to be cut. Once pressure is applied, the foot switch (not shown) is actuated which thereby provides current to the cutting blade which in turn heats the blade 38. Air pressure produced by the cylinder forces the hot cutting blade through the rubber and toward the foot assembly. Just as the cut is completed, the air control 68 valve and electric foot switch are released. The air cylinder can then be moved to its extended position by operating the switch 76 and placed in position for another cut.
The tire grooving apparatus therefore provides for the cutting of straight grooves at almost any position 2a2~

on the tire tread face. It further allows for the cutting of these grooves on tires while they are either on or off a vehicle depending upon the si~e of the tire and clearances of the vehicle itsel~, Furthermore with applicants' invention the reduction o~ high cutting blade temperatures produces an increased length o~
blade life.
The tire grooving apparatus as described above while being portable could also be installed in a permanent installation. For example, a grooving tool could be mounted on a spring-loaded suspended tool holder that would counterbalance the weight of the assembly and facilitate the operation thereof. A fixed installation would lend itself to the advantages of hydraulic operation instead of pneumatic. A
hydraulically operated device could have limit switches on the piston rod to stop the cutting action at any required position on the stroke. Furthermore, a hydraulically operated device could be set for semiautomatic operation. The tire could be mounted on a `horizontal turn table indexed to advance the tire in one lug intervals. At each stop, the device, mounted on a suitable carriage, could advance to the treadface and make the required cut or cuts. This mode of operation would lend itself to the use of smooth treads to be cut at a later date in a predetermined manner.
Applicants' invention while being able to be used in an automatic or powered mode using the air cylinders or hydraulic cylinders can also be used in a manual mode. Referring now to Fig. 10 the cutting head assembly 28 may be supplied with two handles 110, 112.
One handle 110 extending from one end of the support member 60 with the other handle 112 extending from the other end of the support member 60. It is preferred 2~2~7 that the handles 110, 112 are designed such that the operator's hands are above the blade 38 of the cutting head assembly 28 which thereby permits the cutting head assembly to be easily controlled.
A chain 114 is attached to the cutting head assembly at a point which positions the center o e~fort in close proximately to the center of resistance, which is the cutting blade itself. In this way correcting forces are kept to a minimum and the tool is therefore light and accurate to use. In the manual mode the required groove position is again marked in chalk on the tread surface. A first operator puts the cutting head assembly into position to start the cut. A second operator attaches a lever to a chain and then places the lever against the tire and applies tension to the chain which in turn applies tension to the cutting head assembly. As soon as tension is applied the first operator activates a foot switch to heat the blade. The first operator steers the cutting head while the second operator continues to apply tension as the cut is being made. The first operator then cuts off the current by releasing the foot switch at the end of the cut.
While in the manual mode varying blade pressure caused by the manual operation of the lever and chain can cause similar problems to those noted in the prior art applicants' invention still reduces the blade temperature of the cutting blade to thereby increase blade life and allows for large groove size to be cut.
It is believed important to the invention to be able to select desired current levels being supplied to the cutting blade to thereby reduce the heat generated therein. One manner in which applicants have attempted to accomplish this has been through the use of a tapped . . .
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transformer which is installed in the electrical power supply. Changing the tap setting on the transformer produces a corresponding change in the current output from the transformer. In this manner the current output can be raised or lowered dependlng upon t~e desired conditions. While it is welL known that there are various ways in which current can be adjusted either up or downJ the use of a voltage transformer being just one of them, applicants' invention is not to be construed as being limited strictly thereto.

These descriptions and details have been shown for the purpose of illustrating this invention and will beco~e apparent to those skilled in the art that various changes and/or modifications may be made therein without departing from the original spirit or scope of the invention.

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Claims (18)

1. An apparatus for grooving grooves in a tire tread surface comprising a means having a first and second end for spanning a portion of the tire tread surface;
a means for cutting carried by said first end of said means for spanning; and a means for moving said means for cutting towards said second end, across said tread surface in a predetermined path, for removing material from said tread surface.

2. An apparatus for providing grooves in a tire tread surface comprising;
a means for engaging a portion of the tread surface of the tire;
a cutting head assembly diametrically opposed to said means and supported for movement with respect to said means for engaging between a first position at which the cutting head is retracted from said means and a second position at which the cutting head is closer to the means for engaging than at the first position;
a cutting means carried by said cutting head assembly for removing portions of said tread surface;
a means for moving said cutting bead assembly between said first and second positions; and wherein portions of said tread are removed as said cutting head assembly moves from said first to said second positions.

3. The apparatus of claim 2 wherein said cutting blade is heated.

4. The apparatus of claim 3 further comprising;
an electrical power supply operably connected to said cutting blade for providing current thereto.

5. The apparatus of claim 4 wherein said electrical power supply is capable of adjusting the amount of electrical current.

6. The apparatus of claim 5 wherein said means for moving is a fluid cylinder.

7. The apparatus of claim 6 wherein said fluid cylinder comprises a means to adjust the force applied to the cutting head and a means to adjust the speed of movement between said first and second positions.

8. The apparatus of claim 7 wherein said fluid cylinder is an air cylinder.

9. The apparatus of claim 7 wherein said fluid cylinder is a hydraulic cylinder.

10. The apparatus of claim 6 wherein said apparatus is portable.

11. An apparatus for providing grooves in a tire tread surface comprising.
a foot assembly having a means for gripping a tire and a handle;
a fluid cylinder having a cylinder body attached at one end to said foot assembly;
a shaft portion extending from another end of said cylinder body and capable of movement between a first to a second position;

a cutting head assembly, attached to said shaft portion of said fluid cylinder, having a cutting blade, releasably connected at each end to a conductive material, and a handle;
a means to adjust the force and speed of movement between said first and second positions of the shaft and the cutting assembly;
a means for actuating and/or stopping the movement between said positions;
an adjustable power supply; and a means for connecting the electrical power supply to said conductive material of said cutting head assembly.

12. An apparatus for providing grooves in a tire tread surface comprising:
a cutting blade having substantially a U-shaped cross-section and each end connected to a conductive material;
a means for carrying said cutting blade and conductive material and further having a handle attached thereto;
a means for supplying electrical power to said conductive material to provide for heating of the cutting blade; and a means for drawing said cutting blade across said tread surface.

13. The method of providing grooves in a tire tread surface comprising the steps of:
(a) causing a grooving tool having a cutting head assembly and a engaging means to extend apart from one another;

(b) placing said grooving tool along a tire tread surface such that the cutting blade will travel along the desired path to be cut and that the engaging means is in contact with a portion of said tread or sidewall of said tire;
(c) actuating said grooving tool to cause said cutting blade to engage the tire tread surface to be cut;
(d) heating said cutting blade; and (e) actuating said grooving tool to force the hot cutting blade through the rubber of said tread surface and towards said engaging means.

14. The method of claim 13 wherein said cutting blade is forced through said rubber at a predetermined constant force.

15. The method of claim 14 wherein said steps are performed on a tire mounted on a rim.

16. The method of claim 14 wherein said steps are performed on a tire mounted on a vehicle.

17. The method of claim 14 wherein said steps are performed in the field.

18. The method of claim 14 further comprising repeating said steps for a plurality of grooves.