DE2054743A1 - Process for conditioning tires to improve their uniformity - Google Patents

Description

Patent attorneys? Π R A 7 A * ί

Dr. Ing.Walter Abitz ^{c u QH} '*

Dr. Dieter R- Morf Dr. Hans-A. Brauns 8 Munich 36 _l PJ "" new "*. 28

November 6, 1970 GT-5 93-F

The General Tire & Rubber Company- One General Street, Akron, Ohio, V. St. A.

Process for conditioning tires to improve their evenness

A large number of variable sizes play a role in the construction of pneumatic tires. Some of the same are Insufficient dimensional accuracy, changes in the physical or strength properties and in the Size of the calendered fabric, the thickness, location and Overlapping of the various reinforcements of the tire, the large number of different compounds and materials used in tire manufacture human error such as inaccurate centering of the tread and the protector inlays as well as the application of unequal Adhesive prints and differences in the vulcanization of the tire such as size inaccuracies of the shape una uneven Vulcanization temperatures. All of these

109820/1512 2, bad original

«Τ-533-Γ

other sizes either individually or in interaction together have an adverse effect on the static and dynamic properties of the finished tire.

Many attempts have already been made to eliminate or compensate for this imbalance and irregularities. For example, a small additional mass is often added to the tire or its rim to reduce the imbalance of the tire to compensate. Attempts have also been made to produce a perfectly round or concentric tire by that the tread of the tire is processed or ground. There were other procedures and Devices designed and used to improve the qualitative and quantitative aspects of tires, however with little success.

Recently, a machine called a tire testing machine has been developed with which to operate under dynamic conditions. Changes or deviations in the force can be heard caused by a rotating against a surface Tire is exercised. In this machine, a tire is mounted on a rotating axle and inflated. Then the tire is set in rotation against a drum, the shaft of which is fitted with suitable strain gauges or transducers connected is. When the tire rotates in contact with the drum, the tension exerted on the strain gauges is exerted Force measured and fed to a suitable display device. The strain gauges can be used for this purpose, among other things the radial force, i.e. those forces that act in a plane parallel to the wheel surface, and the lateral forces to measure, i.e. those forces that are in a

act on a plane perpendicular to the plane of the wheel surface.

Try different types of tire testing machines

109820/1522

NEN have shown that changes or variations in radial forces around the tire are important Factor in the particular problem of tire evenness and the associated running properties. It has recently been found that this eliminates the radial and lateral unevenness can be that a small amount of rubber from the shoulder rib of the tire in the area of the largest Unevenness is removed. Details of the method and a machine for performing such Compensation are in the USA patent application S.i <J. 613.25 2 of February 1, 196 7. Although usually by compensating for the irregularities in this way the running properties of the tire are improved he certain disadvantages. For example, in some tires the unevenness is so great that it is considerable Amount of rubber must be taken away. Furthermore, the removal of rubber compensates for the unevenness, but not a correction of the same. As an alternative to removing rubber, a tire is required excessive radial force irregularity is treated as scrap or sold at a lower price will. A tire of the type mentioned is structurally correctly designed, but can because of its lack aesthetic quality do not warrant a special price or used as initial equipment for new automobiles will.

Many of the tires currently on the market have a carcass made from a skimmed fabric of Hylon or polyester cord is composed. These two synthetic fibers have properties that make them well suited make for use in pneumatic tires. However, it has been observed that after a tire has been vulcanized, nylon

- 3 109820/1522

GT-S93-F

and polyester cords both tend to shrink when cooled and then stretch slowly, while the tire is in operation. This often leads to tread cracks and premature degradation of the tire. U.S. Patent 3,002,228 states that cord shrinkage can be minimized by cooling the tire takes place slowly while maintaining its internal pressure. This is done in the vulcanizing press or it the tire can be removed from the press and mounted on an inflatable rim on which it can be placed in the inflated state to cool down. This post-vulcanization inflation has in many cases, such as trials have shown on a * tire testing machine a adverse effect on tire evenness. By Although such a method reduces the problem of cord shrinkage and the subsequent stretching in the drive, but at the same time the problem of tire unevenness difficult.

It was also found that temperature gradients and other variable quantities that occur before, during or after the vulcanization cycle of a tire, thermally induced structural deviations in the tire result in the build-up of stresses in the Lead tire cords by varying the shrinkage of the latter on cooling. All of these factors contribute to excessive radial force irregularities in the tire.

The object of the invention is to improve the running properties of pneumatic tires for cars and trucks.

Furthermore , the invention should reduce the amount of tread

■. 4 - ■. ■. * ■

109820/1522

materials are reduced in those tires where compensation due to tire unevenness is required must be taken away.

The invention also aims to increase the size of the radial force irregularities are reduced, which are caused by thermally induced irregularities within of a tire. The invention is also intended to provide a special and unusual heat treatment process After measuring the tire evenness, the size and dB effect are created to reduce the irregularities.

The above and other objects are achieved in the manner described in more detail below in that the area of the tire with the maximum radial force

deviation is determined, the tire is stored in the vertical position so that the area of maximum force change is in the upper quadrant of the tire, and the tire or a part thereof is subjected to a heat treatment at a temperature and for a period of time which is sufficient To reduce the size of the peak-to-peak or first harmonic radial force deviation thereof. Temperatures from 65 ° - 138 ° C (150 ° to 280 ° F) for a period of 5 or 10 minutes to 60 minutes at an inflation pressure of 0-3.50 kJ
proven appropriate.

2
pressures of 0-3.50 kg / cm (0-50 psi) prove to be

In particular, after a pneumatic tire has been assembled, it is pressurized in a conventional tire vulcanizing press at a temperature between about 143 and 177 ° C (about 290 ° and 350 ° F). vulcanized. Awake to the removal from the vulcanizing press the tire can immediately be inflated again on a tire rim of the type

109820/1522

be as it is called, for example, in Fig. 2 of the pre _t USA patent described, whereupon it to a temperature below 99 ° C (210 ⁰ F) under main- "

2 maintenance of an internal pressure of about 3.50 kg / cm (approx 50 psi) to cool down. As mentioned, this inflation after vulcanization reduces the inclination of the cord, to shrink on cooling and to stretch again during operation of the tire, decreased. The pumping up after vulcanizing has a further advantage in that it increases the dwell time of the tire in the vulcanizing press so that the latter can be used more effectively. Usually this procedure is used Applied to tires that contain synthetic fibers such as nylon and polyester, however it is usually at Rayon tires not required.

After the fully cured tire to a temperature below 99 ° C (210 ⁰ F) has been cooled, it is mounted in a tire testing machine, for example in the Model 60 Tire Uniformity Grading Machine, of represents Company Akron Standard Mold Division of Eagle Picher Corporation is available. In this machine, the tire is inflated and pressed against a road wheel with a certain static load, whereupon the tire at a constant speed of, for example, 60 / rpm. is driven to rotate. During the rotation, the distance between the tire axis and the axis of the drum remains constant. Radial force transducers connected to the drum shaft produce a signal proportional to the constantly changing force exerted by the tire against the drum during rotation, and this signal is appropriately indexed or in Correlation is set to determine the exact position on the circumference of the tire at which the maximum force is generated.

109820/1522

GT-593-F h

This position is marked, for example by the fact that a point on the sidewall of the tire between the Position and the tire axis is attached. This marking can be done manually or automatically. With a corresponding Conditioning of the signal from the transducers can determine the maximum combined force (the often referred to as peak-to-peak change), which is composed of the summation of all radial harmonic forces generated, measured and marked at a given location in the tire. Possibly may be the maximum value of the first harmonic curve, which is the main contributing factor to the change curve of the composite Force is to be determined and its position on the tire marked. The location of this maximum value of the first harmonic is often referred to as the phase angle.

After the high point of the uniformity curve, either the composite curve or the curve after the first harmonic, is marked on the tire, this is od on a rim, a hook. Like; brought in in such a way that the marked point of the tire, which represents the maximum change in force, is at the top of the tire is located, whereupon the tire is heated in a vertical position for a period of time which sufficient to reduce the size of the maximum force changes. The tire can no longer pressurize

2
than about 3.5 kg / cm (about 50 psi) during heating, which is usually done in a steam autoclave, a hot air oven, or an infrared oven.

It was found that both the magnitude of the peak-to-peak radial force change as well as the value of the curve after the first harmonic of a large percentage

109820/1522

of tires can be reduced by heating the tires to a temperature below the degradation temperature of the tire for a period of time sufficient to release the cord tensions. For polyester and Nylonkordreifen a desired temperature range between 65 ° C and 127 ° C (between 150 ⁰ F and 260 F) although some improvement can be seen at room temperature and temperatures (F 280 ⁰⁾ may be tolerated for a short time to 133 ° C. In the desired temperature range, a treatment time between about 10 and 10 minutes is generally satisfactory. The degree of enhancement, even with prolonged treatment times, is less noticeable at temperatures below about 82 ° C (about 180 ⁰ F). Innernalb the desired range temperatures (b about 230 °, is 260 ⁰ F) of about 110 ° to 127 ° C, comparable to those which are applied to the tire repair preferred.

Rayon cord tires can operate at higher temperatures than tires made of polyester or nylon cord are heat treated without serious degradation. In fact, Reyon requires due its higher thermal stability and its resistance to heat change a stronger heat treatment in order to reduce the force changes, and temperatures of 135 ° C (275 ° F) for 30-60 minutes are in the inventive Practice not uncommon.

Although the tire can be hung on a hook or the like during the heat treatment, smoother results are obtained when the tire is mounted on rims such as those used in inflating the tire after vulcanization . Rims are also essential when making the tire

109820/1522

GT-593-F

should be inflated during the heat treatment.

The following examples are given to further illustrate the advantages of the invention.

Example I.

A number of Pesonenkraftwagenreifen the Diagonaiijauart each comprising a carcass of two inserts kalanclriertem Reyongewebe were vulcanized in ^ a conventional tire curing press and removed from it at an average temperature between 155 ° C and 160 ⁰ C (between 31ü ° F and 320 ⁰ F). The tires were then placed on a pump-up rim with the exception noted in Table I.

2
mounted, inflated to 3.50 kg / cm and allowed to cool to a temperature of about 93 ° C (about 200 F) '. The tires were then removed from the inflatable rim and checked for radial and lateral uniformity on an A3M Model 60 Tire Uniformity Grading Machine. On the sidewall of each tire, a suitable marking was made at the point of the phase angle, dn at the apex of the radial force curve after the first liarmonic. Those tires which had a maximum first harmonic force change of less than 9 kg (20 lbs) were rated A, indicating that they did not require correction or readjustment. The tires with a maximum first harmonic force change between 9 and 18 kg (20 and 40 lbs) were labeled Ii and those greater than 18 kg (10 lbs) were labeled C. The tires labeled B were those that can normally be improved to grade A by grinding or removing small amounts of rubber from the tread of the tire, while the inflexibility of the tires labeled C as

- 9 109820/1522

-GT-5 93-F

Ho

to correct by grinding within a reasonable Period was considered too large.

After marking of the tires this standing (pot heater) in a heating device were brought to a temperature of 105 ° - heated for 20 minutes by the results shown in Table I. - 138 ° C (220-280 ⁰ F) for periods of 10 ; The tires were not inflated during the heat treatment. From the table it is readily apparent that the heating of the tire to temperatures between 105 ° and 138 ⁰ C (2 between 20 ° and 280 ⁰ F) for periods of 10-20 minutes, a very marked effect on the evenness

• the tire has. The heat treatment of the in a vertical Tire placed with the phase angle on the top of the tire improved the evenness in almost all cases in which the tires were previously inflated after vulcanization. (See experiments

• 4, 5, 7, 8 and 9). However, as shown for Experiment 6, in which the rayon tires were not inflated after curing, there was no substantial improvement achieved. The tires of tests 1 and 2 show no significant improvement, while the evenness of three tires in test 3 typically deteriorated.

Table I.

- 10 -

109820/1522

Table I.

Reyon tires

Trial number d. Time Temp. Position of the unevenness unevenness series Tire (min.) C point degree - before - degree - after -

No.

BC AB C cVi

-, ι i

1 15 15 138 any 9 6 8 3 4

2 15 10 138 any 15 9 6

- * 3 3 10 138 below 111 - 3

4 10 10 138 above - 4 6 4 3 3

YY S 13 20 138 above 5 8 - 11 2

O ₁ 6 ⁺ 18 15 138 above 14 4 15 3. -

-M- * 7 32 15 127 above - 32 23 6 ^; 3

8 14 15 116 above 14 8 2 4

9 36 15 105 above - * 36 26 8 2

not inflated after vulcanizing

GT-593-F iö

A number of these randomly selected tires have been tested in conventional disc wheel tests as well as one Endurance test and a snow run test, The tires were found to be generally comparable in performance to control tires, not after the heat treatment according to the invention have been subjected to vulcanization and subsequent inflation. It is important, however, that in many cases tires that were unusable for grinding (quality C) were sufficiently improved when subjected them to the heat treatment according to the invention so that they could be classified in quality level B or A.

Example II

A second series of attempts with several G78-14 and G78-15 diagonal carcass tire with belt and two carcass inserts Made of calendered polyester fabric and two non-stretchable fiberglass belts. The tires were

* 2

Vulcanized for 15 minutes at 12.95 kg / cm (185 psi) via steam, hot water and cold water. The tires were then removed from the press and immediately pumped up on a pump fig for about 30 minutes, then they were removed from the rim and checked for evenness in a tire testing machine, iiei the test series 10-14 the tires were back on one

2 Rims were returned, whereupon they were inflated to 3.50 kg / cm (50 psi) and heated in a pot heater. After being removed from the heater, they were left to cool in the inflated state to prevent the cords from shrinking. In test series 15 and 16, the tires were not inflated during the heat treatment and were on a rack

10982Q / 15Ü "

hung in a rubber oven instead of being treated in the aforementioned heater. As can be seen from Table II results, the heat treatment improved mean values of the radial force changes when the tire was so vertically arranged became that the area of maximum unevenness was on top. The reverse was when the area was maximal Unevenness is reflected in the underside of the tire found the evenness of the tire usually worse. It can also be seen that an increase in temperature led to a corresponding increase in the degree of improvement.

A considerable number of these Diagonalkarkassenreifen were subjected to various creep rupture tests, strength tests and fast winding tests, which revealed that they were comparable to the control tire in these relationships that no heat treatment had been subjected.

Table II

- 13 -

109820/1522

Number d.
tires Time
(Min.) Jemp. Table II Location d.
Point Peak-to-peak ^{radial force} later % Ver
better first harmonic * later CD
H. ι * 30th 116 below before 43 -14.7 before 24.5 I.
cn
IP
CU
.4, Attempt
row no. 15th 30th 116 pressure
kp above 37.5 33 30th 18th 14.2 10 10 20th 116 3.50 above 47.3 31.9 18.4 28 13.5 % Ver
better 11 5 30th 93 3.50 above 39.1 34.8 5 21.5 15.8 -36 12th 5 60 93 3.50 above 36.6 32.4 . 26th 16 15.8 49 13th 15th 15th 82 3.50 ¹ above 43.8 33.6 9 29 13.8 37 14th 5 15th 82 3.50 ¹ below 36.9 41.2 -12 21.1 30.6 1 15th none 37.8 25.6 45 16 none 35 -20

GT-S93-F

Example III

in a further experiment, sixteen diagonal belted carcass tires of the same type as those tested in Example II were tested, the mean tip-to-peak radial force change being 15.01 kg (33.1 lbs) and an average maximum change after The first harmonic was found to be 8.75 kg (19.3 lbs). The hoops were hung vertically at room temperature for a side space of 24 hours. A group of 3 mature people was hung with the point of maximum change in force in the top layer, while a second group of 8 tires with the area of maximum change in force was hung at the bottom of the tire. These tires were tested again on the tire testing machine at the end of the 24 hour period. checked. The peak-to-peak radial force change for the tires in the first group was decreased to a mean of 13.96 kg (30.8 lbs) while the mean of the first harmonic was decreased to 8.02 kg (17.7 lbs). Six of these 8 tires showed some improvement in evenness. Conversely, the mean peak-to-peak value of the second group of eight tires increased to 15.64 kg (34.5 lbs) while the first harmonic increased to 3.16 kg (20.2 lbs). The evenness of all eight tires in the second group deteriorated. From these results it can be seen that the invention can be benefited even at lower temperatures. However, the time required for a tire to be improved by an incremental amount becomes much longer at room temperature. Accordingly, the invention will normally be practiced at elevated temperatures at which its benefits can be obtained in much shorter periods of time.

- 15 109820/1522

GT-593-F.

/ 6

Example IV A

Further attempts have been made with a large number of diagonal carcass tires carried out with a belt, with v / elchen the carcass inserts made of polyester cord and the circumferential belt were composed of fiberglass around the carcass. The purpose of these experiments was to find the preferred conditions to determine the heat treatment of this type of tire. Before trying, these tires were all in the conventionally vulcanized and were all after vulcanizing eiran inflation process on conventional inflation rims subjected. During the tests, different groups of 10 tires each were mounted on rims and vertically in a horizontal heater (pot heater) with the phase angle at the top of the tire for a heat treatment. Different groups were inflated at temperatures of 66 °, 93 ° and 121 ° C (150 °, 200 ° and 250 °. F), and not

ο
to 3.50. kg / cm inflated, treated for periods of 15 and 30 minutes. Radial force measurements taken on the tires before and after heat treatment showed mean statistical changes in the forces as follows:

Table III

radial radial, first

Peak-peak (kg) harmonics (kg)

Temp. C * 66 - cg.9 93 • · "- 1.60 121
1 “ 1.84 1
Time (minutes) 15th - 1.20 30, - 1.20 - 16 - 109820/1522

- 0.51

- 1.96

- 3.52

- 2.01

- 1.92

/ f

Table III continued

radial radial, first

Peak-peak (kg) harmonics (kg)

Pressure (kg / cm)

0 - 1.33 - 2.32

3.50-1, Q7-1.36

From these results it can be seen that, for this type of tire, there is very little difference in the result between heat treating the tire for 15 minutes as opposed to 30 minutes and that there is little advantage in heating the tire in the uninflated state over one can achieve inflated state. Of course, the improvements in iCraft change depend on the heat treatment temperature. For example, it has been found that an average improvement of 9% and 33% for peak to peak and after the first harmonic at 121 ° C (250 ⁰ F) as compared to an improvement of 0.6% and 4.3% at 66 ° C (150 ^° F) with 90 % of the tires showing improvement at the higher temperature and only 55% at the lower temperature. However, the improvement achieved at higher temperatures must be balanced against the loss of desirable properties that may result from heat treating the tire at a temperature sufficiently high to cause degradation of the cords or rubbers in the tire.

Example IV B ■ Additional groups of tires of the same size and

109820M5722

Kind were not inflated at 121 ° C (25O ° D during Tested for 5 minutes with the tire in a vertical position, with the point of maximum radial force change at a distance of 45 °, 90 and 180 from the top. The results obtained all confirm that instead of the Reduce force change of the tire, the heat treatment in an undesirable manner the size of the radial force changes increased from peak to peak and after the first harmonic. Furthermore, these conditions became progressive worse if the position of the maximum force change was moved downwards. Further tests show the benefits of the invention are largely lost if the tire is tilted more than 30 ° from the vertical position even if the maximum force change is at the top of the tire. .

Example V

Tests similar to those described in Example IVA were carried out on diagonal carcass tires with belted and four Carcass inserts made of rayon and two non-stretchable fiberglass belts. The results of these experiments are shown in Table IV below.

Table IV

- 18 -

y) 9820/1522

GT-593-F

/ 3

Table IV

radial 'radial, first peak-peak (kg) harmonic (kg)

Temp. ⁰ C

66 - 1.33 - 1.36

93 x 2.91-3, IU

121 ■ - 3.26 - 3.40

Time (minutes)

15 - 2.37 - 2.53

30 - 2.6H ₍ - 2.79

2 pressure (kg / cm)

0 - 2.89 - 3.32

3.50 - 2.11 - 1.96

Again, it was found that the beneficial effects of the treatment increased as the heat treatment temperatures increased progressing from 66 ° to 121 ° C (from 150 ° to ■ 250 ° F) and that the treatment on uninflated tires was baser than on inflated tires. The heat treatment of 30 minutes appeared to be slightly better than the 15 minute treatment.

Additional tests with these rayon / fiber tires at 121 ° C (250 ⁰ F) for 15 minutes and an inflation pressure showed that the tires were less sensitive to slight changes in the position of maximum Radialkraftänferung than comparable tires Polyesterreifen.-

J. 19 -

109820/1522

GT-593-F 2 O 5 A 7 Λ 3

cords contained. For example, it has been found that the rayon tire can be rotated so that the position of the maximum force is close to 90 ° from vertical before the maximum values begin to increase rather than decrease. The same applies if the tire is tilted from the vertical position during the heat treatment, however, the point of maximum force on the tire remains up. For example, the 10th Reeyon tire set to 121 ° C • (250 ° F) heated for 15 minutes, an average reduction of 4.08 and 4.26 kg (9.0 and 0.4 lbs) in radial force changes from tip to tip or obtained after the first harmonic with a slope of 0. At an incline of 30 °, the mean was Decreases 3.72 and 4.98 kg (8.2 and 10.10 lbs, respectively) for peak to peak and after the first harmonic, respectively, during tilting the tire 90 ° from the vertical for an average decrease of 1.45 kg or 0.045 kg (3.2 lbs) (or 0.1 lbs) for peak to peak and after the first harmonic, so at 90 are the benefits the invention largely repealed. This is in contrast to polyester tires, which have these advantages to a large extent burn if the tire is up to 30 ° from the vertical is inclined.

Example VI

Two dozen 185-R-14 radial tires each with two carcass inserts made of rayon and a vulcanized cord thread angle of about 90 ° and four non-stretchable protector inserts, each of which formed the same but opposite angles of 9 ° with respect to the tire center line, were made according to your teaching treated of the invention. The tires were all kept at a maximum temperature of about 170 C (approx

- 20 109820/1522

340 F) vulcanized for about 16-17 minutes and cooled to room temperature without pumping after vulcanizing. The tires were all tested on an evenness tester with a composite radial force change from tip to tip of at least 16.78 kg (at least 37 lbs). The tires were mounted vertically on a rack for 60 minutes at 132 C (pot heater) (270 ⁰ F) in a horizontal heater ernitzt, the tire was arranged on the frame so that the point of maximum force was upwards. The tires were then removed from the heater, cooled and tested again in the evenness testing machine. As a result of the heat treatment, the tip-to-tip radial force change was decreased by an average of 3.18 kg (7 lbs), with changes in decrease ranging from -0 to 8.62 kg (19 lbs). The first harmonic has been decreased by an average of 3.76 kg (8.3 lbs). It was found that the force change curve after the treatment was very similar to the curve obtained before the treatment, except that the amplitude of the changes was reduced by the heat treatment.

Example VII

An infrared oven was used to heat treat a number of Grusse G78-15 belted polyester fiberglass diagonal carcass tires, all of which had an initial maximum radial force change from tip to tip between 17.2 3 and 24.95 kg (38 and 55 lbs). In the first series of tests, two groups of 36 tires each were hung from a 1 1/2 inch metal tube and hung in the infrared oven so that the area of maximum force of each tire was within itself

- 21 109820/1522

G.T-593-F

dd

was in the upper quadrant of the tire. In each group, the entire circumferential tread of the tire was through Infrared lamps heated to a surface temperature not exceeding 115 ° or 121 ° C (240 ° or 250 ° F).

The first group was heated for 10 minutes until the temperature of the inner carcass ply of each tire was 8 2 ° C (180 F) reached. The tires were then removed from the oven, cooled, and retested. The mean the change in force from tip to tip was reduced by about 1.14 kg (about 2.5 lbs), with 27 tires being some Showed improvement, four showed no change, and five got worse. The average reduction in the first harmonic of these tires was 1.5 9 kg (3.5 lbs) with 26 tires showing some improvement.

The second group of 36 tires were heated for 15 minutes until the temperature of the inner carcass ply reached 99 ° C (210 ^° F). For these tires the peak-to-peak force change was decreased by 1.17 kg (2.6 lbs) and the change in force after the first harmonic was decreased by an average of 2.17 kg (4.8 lbs).

In another set of experiments using infrared heat, two additional sets of 36 tires were hung vertically on a tube with the phase angle up, and the heat from infrared lamps was concentrated on a 60 ° section of the tire, 30 ° to either side of the phase angle . The first group of tires 36 was heated to an inner Karkassentemperatur of 8 2 ° C (180 ⁰ F), with 15 minutes was required for reaching this temperature. These tires, when retested, showed an average reduction of I ₁ W kg (2.5 lbs) in tip-to-tip change and

- 22 -

109820/1522

CT-S ₉₃ -F

2.54 kg (5.6 lbs) the first harmonic size, with 26 of the 36 tires showing at least some improvement. Another group of tires was heated in the same way, but to 99 ° C (210 ⁰ F) held on. 8 2 ° C (180 ⁰ F). About 50 % of these tires showed some improvement in peak-to-peak change, while 31 tires showed improvement in first harmonic force change.

Example VIII

In yet another series of attempts, several diagonal carcass passenger car tires with four nylon carcass plies were found vulcanized and then pumped up, whereupon they were tested for their evenness. the Tires were then divided into three groups according to the values of the maximum peak-to-peak force change, with the Group 1 values between 15.88 and 20.41 kg (35 and 4 5 lbs) * Group 2 had fourth between 20.41 kg and 24.95 kg (45 and S5 lbs) and Group 3 tires with a maximum Force change. In excess of 24.95 kg (55 lbs) contained. These

Two tires were mounted on a rim and inflated to 3.5 kg / an (50 psi), whereupon they were heated in a vertical position in an autoclave at 115 ° C (240 ° F) for 30 minutes, the point of maximum force was on top of the tire. These tires were then allowed to cool for 20 minutes after which they were retested in a tire evenness tester. Upon retesting, it was found that an average reduction was obtained in the peak to peak force variation of 13% for the first group, of 22% for the second group and of 40% for the third group. These experiments clearly show that the benefit from the invention is proportional to the initial magnitude of the change in force.

- 23 -

109820/1522

GT-593-F

I »

Although it has been found that by the invention the
Radial force changes in a large number of tires is reduced, that is accompanying the invention
Phenomenon not fully understood. However, it appears that the heat treatment of a tire is certain
Tensions within the fabric of the carcass and / or
the protector inlay creates which tensions contribute to the unevenness. The subsequent heat treatment normalizes the tissue and relieves some of these tensions, which leads to a reduction in unevenness.

The importance of placing the tire in a vertical position with the maximum radial force on the
The top of or near the top of the tire is believed to be at least in part attributable to the creep properties of the tire cords, which may be imparted by the
Train gravity is affected. The creeping speed of synthetic long-chain synthetic cords
Polymers such as polyester and nylon are larger than that of a cord made from rayon, which may explain why tires made from rayon respond more slowly during heat treatment and are less sensitive to the position of the phase angle during
the treatment are. Because of the sensitivity of the
Care must be taken to heat-treat tires containing nylon or polyester cords to avoid overcorrecting these tires by heating them at a high temperature for too long a time. This top correction can reduce the maximum force near the top of the tire, but it can result in the. Phase angle (i.e. the high point of the first harmonic curve) is shifted and the maximum force increases elsewhere on the tire, thereby canceling the beneficial effect resulting from the

109820/1522

GT-5 93-F

XS

reduction of the original maximum force results.

It was also observed that the manner of storage of the tire subjected to a heat treatment during this that seems to affect results, for example If the tire is mounted on a hook, the entire weight of the tire is concentrated on one point, with the application of the teachings according to the invention the position of the maximum force coincides. The test results show a much more notable change in the position and magnitude of these forces during heating on hooks than when the tires are heated when they are mounted on rims or arranged on racks.

As mentioned, the tire unevenness is caused by a Causes a number of factors, only one of which is related to the condition of the tire fabric. It therefore has the It appears that the invention is directed to improving one or more structural features of the tire, which contribute to its complete evenness, regardless of the origin of each feature. The invention is therefore applicable to any tire with stress conditions similar to those imposed by the Vulcanization or inflation after vulcanization can be caused even if the tire itself is not has been subjected to the heat treatment.

Although the placement of the tire so that the area of maximum unevenness in the tire during the heat treatment is on top is an important feature of the invention, it should be noted that the measurement of the actual uniformity on any type of machine and by any method with which such a determination can be made, can be performed . It should also be mentioned that in the present case the "above" is usually the case with tires

- 25 -

109820/1522

GT-5 93-F

IC

the top quadrant of the tire is instead of top dead center. This upper quadrant is commonly called the one Defined area of the tire that extends in the circumferential direction * extends by about H5 ° to each side of the top dead center.

Pot heaters, rubber ovens, and infrared ovens have been specifically mentioned above for practicing the invention, though other suitable heating ovens and vessels can also be used. A pot heater is a large pressure vessel in which live steam is used to heat the tires. When inflated tires are heated in a pot heater, The vapor pressure in this must not exceed the tire inflation pressure n-ight, otherwise the tire will be seated on the Rim loses.

Although the invention is a method for reducing the size of the radial force changes a large percentage teaches of tires, there is some tendency for these tires to reverse in use, as set forth below will.

Example IX

Sixteen G78-15 belted diagonal carcass tires were measured for tire uniformity and then heated in a pot heater at 115 ° C (240 ° F) for 30 minutes with the phase angle upright stored vertically. The tires were measured again and a marked improvement of 21 % in the change in peak-to-peak force was found. The tires were then mounted on vehicles and driven approximately 80 kg (approximately 50 miles), after which they were removed from the vehicles and measured again. It

- 26 109820/1522

GT-593-F

it was found that about 30% of the initial improvement was lost during use. The values, however, were still much better (IU% for peak-to-peak) than those obtained before treatment.

As such, measurement of tire evenness does not form part of the invention, with the exception that it serves to determine the high point of the force change curve. Indeed, any suitable means for Determination of the position in the tire at which the maximum Force change generated during rotation can be used.

The tires used in all of the experiments described above are of conventional design and construction a carcass or composed of a body, the two or more layers of calendered fabric, two Contains inextensible beads, sidewalls and a tread. The rubber components were conventional from elastomeric approaches made of natural rubber, styrene-butadiene mixed polymer, Polybutadx rubber or combinations thereof made. These approaches and components and their uses are in tire building technology known.

The treatment of tires in the manner according to the invention does not require the removal of rubber from the tire to compensate for unevenness, but serves to modify the tire in such a way that the unevenness is corrected. The term treatment, as used here and to be understood as being according to the invention does not include the dragging or removal of any part of the tire. However, you can with

- 27 109820/1522

GT-593-F

another process, for example with a loop Process, are coupled to improve the evenness of the tire even further.

The invention is of course not limited solely to the teachings given above, but can within experience various deviations from their framework.

&■; ■

- 28 -

109820/1522

Claims (1)

Patent application : 1. Victims to improve the evenness of a Vulcanized pneumatic tire, characterized in that a) the area of the tire at which the maximum change in radial force occurs when rotating against a surface would be generated, is determined, b) the tire is arranged in an upright position in such a way that " that the region of maximum change lies in the upper quadrant of the same, and c) the tire is treated in this position in order to reduce the size of the maximum change in radial force. . 2. The method according to claim 1, characterized in that the treatment comprises heating the tire. 3. The method according to claim 2, characterized in that the tire during treatment to a temperature between about 66 ° C and about 138 ° C (between about 150 ⁰ F and etwa.280 ⁰ F) for a period of up to 60 minutes is heated. Method according to claim 3, characterized in that the tire is placed on a fig during the heat treatment. - 29 - 109820/1522 ... GT-593-F 00 is mounted. 5. The method according to claim H, characterized in that that the tire to a pressure of no more than 2 5.60 kg / cm (80 psi) inflated during treatment will. Method according to claim 3, characterized in that the tire contains cords selected from the group consisting of polyester cords and nylon cords are selected and heating at a temperature between 110 ° and 127 ° C (between 2 ^ 0 ° and 2G0 ° F) is carried out for a period of between about 10 and about 30 minutes. ! Process for improving the running properties of a A pneumatic tire containing cords made from a synthetic linear polymer in which the tire has been vulcanized at elevated temperatures in a vulcanizing press, has been removed from the press and pumped up and during the cooling in the following vulcanization is held inflated state, characterized in that a) the forces exerted by the inflated rotating tire under load against a surface are measured will, ; the; The area of the tire is determined in which the greatest force change is generated, and j 109820/1 SM 2 ^ 54743 • 6T-S93-F. c) the tire in a substantially vertical position, in which the mentioned area is located located on the top of the tire, heat treated at a temperature and for a period of time which are sufficient to reduce the value of the forces, but are not sufficient, bring about a thermal degradation of the tire. 8. The method according to claim 7, characterized in that HO minutes is heat-treated tire at a temperature between about 66 ° C and about 138 ° C (between about 150 and about 280 ⁰ F ⁰ F) for a period of less than. . 9. The method according to claim 8, characterized in that the tire is at a temperature of not heat treated less than 82 ° C (180 ⁰ F). 10. The method according to claim 9, characterized in that the tire is at a temperature between about 110 ⁰ C and about 127 ° C (between about 230 and about 260 ⁰ F ⁰ F) is heat-treated. 11. The method according to claim 10, characterized in that the tire to a pressure of not more than 5.60 kg / cm ' (80 psi) inflated before the heat treatment and the heat treatment is carried out at an external pressure, which is not higher than the tire inflation pressure. • * - 31 109820/1522 * ". • GT-5 9 3-F 12. The method according to claim 8, characterized in that that the area in which the maximum force is generated is usually in the upper quadrant of the tire
while a heat treatment is arranged. 13. The method according to claim 12, characterized in that the tire during the heat treatment by no more
than is arranged at about 30 ° to the vertical. Method according to claim 8, characterized in that ■ · infrared heat is used for heat treatment. 15. The method according to claim 12, characterized in that the heat is concentrated on the area of the tire
in which the maximum force is generated. 16. The method according to claim 7, characterized in that process step b) comprises: a) the force is separated into the first and higher harmonics and b) the area of the tire is determined in which
is the apex of the first harmonic curve.