KR101211295B1 - Golf ball having high initial velocity - Google Patents

Abstract

The multi-layered ball includes a core made of a high energy material, such as a highly neutralized polymer, and a cover made of soundproof material. There is a specific relationship between the compression and rebound coefficient of the core and ball. The initial velocity of the ball is higher than can be predicted based on the rebound coefficient of the ball compared to conventional balls. The use of sound insulation material allows the ball's coefficient of repulsion to be relatively low, thereby improving the likelihood of spin in half wedge shots while maintaining the driver distance.

Description

GOLF BALL HAVING HIGH INITIAL VELOCITY

Cross Reference of Related Application

This application is incorporated by reference herein and filed August 20, 2010, entitled U.S. Provisional Patent Application 61 / 375,775 entitled "Golf Ball Having High Initial Velocity." 35 USC Claim priority under §119 (e).

Field of technology

The present invention generally relates to a golf ball having a plurality of layers. These layers are designed to have a specific relationship between repulsion coefficient and compression to achieve high initial velocities.

Manufacturing golf balls with multiple layers is standard in the industry. In industry, individual designers may feel that certain features are more important than others, and golf balls can be designed to optimize certain features. Individual golfers may also feel that certain features are more important or desirable than others.

In many cases, golfers want a golf ball that provides the longest drive possible. Drive distance is governed by a number of factors beyond the golfer's control, such as the relative height of the tee box and fairway, obstacles on or near the fairway, wind speed and weather. Drive distance is also governed by the golfer's club head speed, the golfer's posture and the golfer's swing parameters such as the club the golfer chooses to use for a particular drive. The drive distance is also governed by the initial speed at which the ball leaves the driver.

In other cases, such as in short games, golfers want a golf ball that has a good sense and good spin / spinability when hit. The sense of golf ball is often governed by the material from which the cover layer (s) are formed. The choice of cover material may also depend on durability, scuff resistance, color, and the like.

Many golfers want a balance between the length of the ball trajectory and the sense of the ball. Some golfers only want one or the other, but golfers are more likely to want to balance these features.

Therefore, it is desirable to develop a ball that contains a combination of good sensations and features of maximum initial velocity. The combination of these features is generally considered to be desirable by golfers who play the ball.

In one embodiment, a golf ball is provided. The golf ball may have a core and a cover surrounding the core. The core may comprise a highly neutralized polymer. The cover may comprise a deadening material. The core may have a first coefficient of repulsion and the ball may have a second coefficient of repulsion. The difference between the first and second rebound coefficients is less than about 0.032.

In another embodiment, a golf ball is provided. The golf ball may have a core and a cover surrounding the core. The core may have a compression (x). The coefficient of repulsion of the ball can be given by the equation 0.6511-0.024x ² + 0.1165x. The coefficient of repulsion of the core can be given by the equation 0.7951-0.0121x ² + 0.416x. The coefficient of repulsion for any ball made according to this trend line can be imposed to create a ball that conforms. Using sound insulation material as the cover may enable the designer to create a matching ball using a high energy core.

The golf ball can be designed such that compression, rebound coefficient and initial velocity have a specific relationship. The material and rebound coefficient of the core can be devised to produce an initial velocity higher than the ball's expected and / or spinability of the ball. The material and compression of the core can be devised to produce a coefficient of repulsion for the ball that is different from what is overall predicted. In particular, balls made in accordance with the present invention will tend to have higher initial velocities than expected for a given rebound coefficient. This means that, especially for half wedge shots, the spin probability is increased due to the low repulsion coefficient in the short game, while the golfer can get an initial speed sufficient to get a good driver distance.

A ball comprising a high energy material in the core, such as a highly neutralized polymer, and a soundproof or cushioning material in a cover, such as a thermoplastic polyurethane, can achieve this benefit. Balls with certain high energy cores can provide designers with more cover choices to achieve desirable ball performance parameters.

Other systems, methods, features and advantages of the embodiments may be or will become apparent to those skilled in the art upon examination of the following figures and detailed description. All such additional systems, methods, features, and advantages are intended to be included within this specification and this summary, within the scope of the disclosure herein, and protected by the following claims.

The present invention may be better described with reference to the following drawings and detailed description. The components in the figures are not necessarily drawn to scale, but instead highlighted when illustrating the principles of the invention. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the various views.

In accordance with the present invention, a ball can be obtained that includes a combination of features of good sensation and maximum initial speed, and the combination of these features can provide a golfer with a ball that is generally desirable to play.

1 is a side view of a golf ball according to the present invention.
2 is a cross-sectional view of an embodiment of a ball according to the present invention.
3 is a cross-sectional view of another embodiment of a ball according to the present invention.
4 is a cross-sectional view of another embodiment of a ball according to the present invention.
5 is a chart comparing the initial velocity and rebound coefficient of the ball when tested with a driver.
6 is a chart comparing repulsion coefficients and compression for two balls and their corresponding cores.
FIG. 7 is a chart showing various trend lines for various cores from FIGS. 5 and 6.

A ball of multilayers is disclosed. Although the embodiments described herein are limited to golf balls, the invention is not intended to be so limited. The techniques described herein may be applicable to any layered article, in particular projectiles, balls, entertainment devices or components thereof.

1 is a side view of a ball 100 that may be prepared according to the techniques disclosed herein. 1 through 4 illustrate a typical dimple pattern applied to the outer surface 102 of the ball 100. The dimple pattern on the ball 100 may affect the flight path of the ball 100, but no particular dimple pattern is critical to the use of the disclosed embodiments. The designer can select any suitable pattern applied to the ball 100.

FIG. 2 is a cross-sectional view of the first embodiment of the ball 100 taken along line 2-2 of FIG. 1. As shown in FIG. 2, the ball 200 may have two layers. The ball 200 can include a core 204 and a cover 206 surrounding the core 204. Any embodiment of a golf ball described herein can be compression and / or injection molding of a core, injection molding of any outer layer, adhesion of layers of a golf ball, optionally with adhesive, and spraying, brushing, dipping and pads. It may be prepared according to any known technique such as painting or coating a ball by printing or the like.

The core 204 can be made of a material that is energy efficient. Energy efficient materials tend to collide in a highly elastic manner. The core 204 may be made from, in some embodiments, mainly or wholly highly neutralized polymers. In some embodiments, the highly neutralized polymer is E.I. It may be HPF 1000 or HPF 2000 available from E.I. DuPont de Nemours and Company. In some embodiments, core 204 may have a diameter of about 38 to about 41 mm. The cover 206 may, in some embodiments, be made of a low energy or soundproof material. Low energy efficiency materials tend to collide in a low elasticity manner. In some embodiments, cover 206 may be made primarily or entirely of thermoplastic urethane resin. In some embodiments, cover 206 may have a thickness of at least 2.1 mm.

In some embodiments, one or more additional outer layers may be included but are not shown in FIG. 2 or in any of the remaining figures. There may be a top coat on the outside of the cover 206 of FIG. 2. The top coat may be a coat applied to enhance or adjust the appearance of the ball 200. For example, the top coat can be applied to change the color of the ball 200 or to change the glossiness of the ball 200. In other embodiments, the additional coat may take the form of the application of a logo or other print on the outer surface 202 of the ball 200. Other additional coats may also be applied to the exterior of the cover 206. Such an outer coat can be applied to any of the embodiments described herein, and therefore, it will be understood by those skilled in the art that this optional coating will not be described further in connection with the following examples. It should be noted that the golf ball should typically be coated. All tested balls described in this application were equipped with coatings such as paints and protective coatings. The coating may have some influence on the coefficient of repulsion of the ball, but this effect is considered negligible in consideration of the embodiments of the present invention. However, if the coating is made from a sufficiently thick or very hard material or a very soft material, this impact may be important for the design purpose of the embodiment according to the invention.

3 is a cross-sectional view of a second embodiment of a ball 100 taken along line 2-2 of FIG. 1. As shown in FIG. 3, the ball 300 may have three layers. The ball 300 can include a core 304, an inner cover layer 308 surrounding the core 304, and an outer cover layer 310 surrounding the inner cover layer 308.

The core 304 may be made of a material that is energy efficient. Core 304 may be fabricated from highly neutralized polymers, predominantly or entirely, in some embodiments. In some embodiments, the highly neutralized polymer is E.I. It may be HPF 1000 or HPF 2000 available from Dupont de Nemore and Company. The core 304 may have a diameter of about 38 mm to about 41 mm. In some embodiments, any layer other than the cover layer (s) may comprise a highly neutralized ionomer. In some embodiments, all other layers other than the cover layer (s) may be in size from about 38 mm to about 41 mm in total. In some embodiments, all other layers other than the cover layer (s) may add up to about 38.6 mm.

일 수 있다. 몇몇 실시예에서, 내측 커버층(308) 및 외측 커버층(310)의 조합된 두께는 약 2.1 mm일 수 있다.Inner cover layer 308 and outer cover layer 310 may be made of one or more energy efficient materials or soundproof materials in some embodiments. In some embodiments, inner cover layer 308, outer cover layer 310, or both, may be made primarily or entirely of thermoplastic urethane resin or thermoplastic polyurethane resin. In other embodiments, the inner cover layer 308, the outer cover layer 310, or both, may be made predominantly or wholly of the ionomer resin. In some embodiments, the ionomer resin is E. I. SURLYN commercially available from Dupont de Nemore and Company

Lt; / RTI > In some embodiments, the combined thickness of the inner cover layer 308 and the outer cover layer 310 may be about 2.1 mm.

4 is a cross-sectional view of the ball 100 taken along line 2-2 of FIG. 1. As shown in FIG. 4, the ball 400 may have four layers. The first layer 412 can be an inner core layer. The second layer 414 can be an outer core layer and can surround the first layer 412. The third layer 416 may be an inner cover layer and may surround the second layer 414. The fourth layer 418 can be an outer cover layer and can surround the third layer 416. The first or inner core layer 412 and the second or outer core layer 414 together may be regarded as core 420 and may be referred to as cores. The third or inner cover layer 416 and the fourth or outer cover layer 418 together may be regarded as a cover 422 and may be referred to as a cover.

일 수 있다. 몇몇 실시예에서, 내측 커버층(416)과 외측 커버층(418)의 조합된 두께는 약 2.1 mm일 수 있다. 몇몇 실시예에서, 커버층(들) 이외의 임의의 층은 고도로 중화된 아이오노머를 포함할 수 있다. 몇몇 실시예에서, 커버층(들) 이외의 모든 층은 총합이 약 38 mm 내지 41 mm의 크기가 될 수 있다. 몇몇 실시예에서, 커버층(들) 이외의 모든 층은 총합이 약 38.6 mm가 될 수 있다.The core 420 may be made of one or more high efficiency materials, and each of the first layer 412 and the second layer 414 may be made of high efficiency materials of different compositions. At least one layer of the core 420 may be made from highly neutralized polymers, mainly or entirely, in some embodiments. In some embodiments, the highly neutralized polymer is E.I. It may be HPF 1000 or HPF 2000 available from Dupont de Nemore and Company. The cover 422 may be made of a low efficiency material or a soundproof material. In some embodiments, third layer 416, fourth layer 418, or both, may be primarily or wholly thermoplastic urethane resins. In other embodiments, third layer 416, fourth layer 418, or both, may be made predominantly or entirely of ionomer resin. In some embodiments, the ionomer resin is E. I. SURLYN commercially available from Dupont de Nemore and Company

Lt; / RTI > In some embodiments, the combined thickness of inner cover layer 416 and outer cover layer 418 may be about 2.1 mm. In some embodiments, any layer other than the cover layer (s) may comprise a highly neutralized ionomer. In some embodiments, all layers other than the cover layer (s) may be in size from about 38 mm to 41 mm in total. In some embodiments, all layers other than the cover layer (s) may add up to about 38.6 mm.

In FIG. 4, the ball 400 is described and illustrated as having a plurality of layers. In some embodiments, additional layers may be added. For example, in some embodiments, an envelope layer may be added between the core 420 and the cover 422. In other embodiments, an intermediate cover layer may be inserted between the inner cover layer 416 and the outer cover layer 418. In other embodiments, an intermediate core layer may be inserted between the inner core layer 412 and the outer core layer 414.

It will also be apparent to those skilled in the art that similar modifications may be made in any embodiment based on the designer's particular needs without departing from the intent of the embodiments of the present invention. For example, a four layer ball may include an inner core layer, an intermediate core layer, an outer core layer, and a single cover layer. Likewise, a four layer ball may comprise a single core layer, an inner cover layer, an intermediate cover layer and an outer cover layer. Balls with other numbers of interlayers will also be apparent to those skilled in the art. Accordingly, the illustrated embodiments are exemplary in nature and not intended to be limiting.

Referring now to FIG. 5, a chart illustrating the difference between the disclosed embodiment and the current commercially available balls is shown. These balls are described in more detail below. The value on the y-axis on the left is the initial velocity of the ball when tested with the driver. Each ball was hit with the same conditions (head speed, attack angle, etc.) with a Nike SQ driver with a loft angle of 9.5.

The initial velocity is shown in the chart by the height of each bar on the bar graph. The initial velocity, as shown as a bar graph, is shown in units of miles per hour. An initial speed of 150 miles per hour is equivalent to about 220 feeds per second. An initial speed of about 170 miles per hour is equivalent to about 250 feet per second.

The value on the right side of the chart reflects the rebound coefficient of the ball as a whole. To measure the rebound coefficient of an object, the object is fired by an air cannon at an initial speed of about 40 meters per second. The steel plate is located about 1.2 meters from the cannon and the speed monitoring device is located at a distance of about 0.6 to about 0.9 meters from the canon. The object is fired from the air cannon and passes through a speed monitoring device to measure the initial speed. The object is then rebound back through the speed monitoring device to hit the steel plate and measure the return speed. The rebound coefficient is the ratio of the return velocity to the initial velocity. The coefficient of repulsion of each ball is shown by line 544 shown on the chart.

으로 제조된다.The x-axis identifies the ball tested. Each ball tested was tested for initial velocity and rebound coefficient. The first nine balls (denoted 1 through 9) are commercially available golf balls. Each of these golf balls has a core made of butadiene rubber compound having a diameter of about 40 mm. For each ball, the exact composition of the core is slightly different. The core of each ball is made of butadiene rubber with different additives or different sizes that produce different compression and rebound coefficients. It is believed that there is a correlation, possibly a strong correlation, between the repulsion coefficient and the core size, which allows a small deviation of the core size to have a negligible effect on the rebound coefficient. Each cover of the ball is about 1.4 mm thick, mainly SURLYN

Is prepared.

On the other hand, the ball indicated as 10 is a ball made according to an embodiment of the present invention. The ball, indicated as 10 , has a core made of a highly neutralized polymer resin, mainly about 38 mm in diameter. The diameter of the core can be as large as about 41 mm. The cover of the ball is about 2.1 mm thick, but may be as thin as about 0.9 mm thick. If desired, an envelope may be included to ensure that the ball meets the minimum USGA size specification of 42.67 mm (1.680 inches).

When comparing the relationship between the initial velocity and the coefficient of repulsion, it is noted that for balls 1 to 9, there is a general correlation between the coefficient of repulsion and the initial velocity. For example, for balls 1, 2, 4 and 5 with a coefficient of repulsion less than 0.795, the initial velocity is lowered to less than about 150.2. For balls 3, 6, 7 and 8 with repulsion coefficient greater than 0.800, the initial velocity is greater than about 150.8. For ball 9 with a coefficient of repulsion of about 0.800, the initial velocity is about 150.5. Thus, the chart shows the general correlation between the coefficient of repulsion and the initial velocity.

However, the chart shown in FIG. 5 indicates that the initial velocity of the ball 10 deviates from the expected initial velocity of a conventional ball with a repulsion coefficient of 0.774. For the ball 10, the coefficient of repulsion has a value of about 0.774. As can be predicted from conventional balls 1 to 9, instead of the initial speed being less than 150 miles per hour, the initial speed of ball 10 is maintained at 150.8, which is a ball with a repulsion coefficient much higher than almost ball 10 As high as the initial rate. Thus, by using the above described ball structure, the ball repulsion coefficient can be kept relatively low for better sensation and spin potential in the short game while maintaining a moderately high initial speed for longer distances with the driver.

This is especially important for half wedge shots. Due to the low rebound coefficient ball, the golfer may tend to hit the ball stronger, ie at a higher club head speed, to achieve the same distance as a ball with a higher rebound coefficient. A stronger blow (higher club head speed) gives the ball more spin. Thus, a golfer may have a good initial velocity and driver distance, but a ball of low rebound coefficient, which increases the spin potential in short games.

Additional features that can be compared between the existing balls and the balls of the present invention can be seen in FIG. 6. 6 is a chart illustrating the relationship between compression and rebound coefficients for various balls and ball cores. The value on the x-axis represents the compression of the inner core layer of the ball. Compression is determined in a manner known in the art. Sphere cores and / or balls are placed under an initial load of 10 kg. Typically a measurement of the diameter of the ball in millimeters is taken at one or more points, such as pole (s), seams or random points. The single value or the average of the values is recorded. The load is increased to 130 kg and a second measurement of the diameter of the ball in millimeters is made at the same point or points. The single value or average of the values under higher load is recorded. The difference between the values recorded in millimeters is the compression.

The values on the y-axis represent the coefficient of restitution for each of the four items considered. Line 650 represents the relationship between compression and rebound coefficient for a core about 38 mm in diameter and made of butadiene rubber compound. The formula for this rubber core trend line is

&Quot; (1) "

Where x is the internal core compression and y is the corresponding coefficient of repulsion.

Line 660 represents the relationship between the compression and rebound coefficient for a ball that includes a cover covering the core shown in line 650. The expression for this line is

&Quot; (2) "

Where x is the compression of the core and y is the coefficient of repulsion of the ball as a whole. The difference between the relative rebound coefficient of the core and the rebound coefficient of the ball ranges from about 0.035 to about 0.037.

However, comparisons of the coefficients of relative repulsion for balls comprising cores made predominantly or entirely of highly neutralized polymers show a distinct difference. Line 670 represents the relationship between the compressive and rebound coefficients for a core about 38 mm in diameter and made primarily or entirely of highly neutralized polymer. The expression for this line is

&Quot; (3) "

Where x is the compression of the core and y is the corresponding coefficient of repulsion.

Line 680 represents the relationship between the compression and rebound coefficient for the ball that includes a cover covering the core shown in line 670. The cover is the same cover structure as the cover of the ball governed by line 650. The expression for this line is

&Quot; (4) "

Where x is the compression of the core and y is the coefficient of repulsion of the ball as a whole. The difference between the relative rebound coefficient of the core and the rebound coefficient of the ball ranges from about 0.026 to 0.031.

Thus, as is evident in FIG. 6, for a given inner core compression, the ball with the rubber core will have a lower rebound coefficient than the ball with the HNP core. In addition, in order to maximize the effect of the sound insulation material, the difference between the coefficient of rebound of the core and the coefficient of restitution of the ball should be at least 0.026, but may be significantly higher, such as 0.037, 0.05, 0.1 or even more. The lower the coefficient of repulsion of the ball, the more spin the ball may be, so a ball with a higher coefficient of repulsion, such as at least 0.037 or at least 0.05, may be desirable. As mentioned above, the relatively high rebound coefficient of the cores produced in accordance with the present invention, as a whole, may still be within a high performance range when the rebound coefficient of the ball is provided with a soundproof cover, thus providing considerable flexibility in the selection of the cover material. Allow.

These gains are shown more simply in FIG. 7, where the rubber core trend line 762 shows a consistently lower core compression for some coefficient of restitution than the HNP core trend line 760. HNP core ball trend line 764 (trend line for the entire ball with the HNP core) is shown for reference.

Thus, replacing a rubber core having the same specified resilience coefficient with a resin core having the specified resilience coefficient allows a significant difference in the relative resilience coefficient of the ball and the core. This is true especially when the resin core repulsion coefficient exceeds the rebound coefficient provided by the rubber core trend line, and the ball has a repulsion coefficient lower than that provided by the following equation,

<Equation 5>

Where y is the coefficient of repulsion and x is the internal core compression.

This can typically be accomplished by making at least one inner / non-cover layer from a highly neutralized ionomer / polymer. The properties of the cover do not require a change between the butadiene rubber core and the highly neutralized polymer core. However, the difference in resilience coefficient between the core and the ball is at least about 0.004 smaller when a highly neutralized polymer core is used. This allows balls with a higher coefficient of repulsion to be made of the same cover material.

Other limitations may need to be observed when balls are made of highly neutralized polymer cores, and when following the coefficient of rebound coefficient trend described above for highly neutralized polymer cores. For example, a matching ball may have a repulsion coefficient lower than a trend provided by Equation 5 or more approximately by the following equation,

<Equation 6>

Where y is the coefficient of repulsion and x is the internal core compression. Thus, the designer may want to impose a limit on the repulsion coefficient of the ball according to Equation 4 such that the restitution coefficient does not exceed the restitution coefficient provided by Equation 6.

Balls made within the scope of the present invention are considered to have improved properties. This ball is considered to have a higher initial velocity than can be predicted. Such balls may also allow for a wider variety of cover materials, including those having particularly low costs. Such a ball can provide a golfer with a low cost ball with a longer trajectory than other balls.

Alternative constructions of layered articles may also be possible to enhance these benefits. For example, a golf ball may have a layer having a specified modulus and hardness of the disclosure of the present specification and of the invention filed on August 20, 2010, the disclosure of which is incorporated herein by reference in its entirety. Golf Ball Having Layers with Specified Moduli and Hardnesses, US Patent Application No. 12 / 860,785 It may be prepared according to the teaching of the contents described in the call.

While various embodiments of the invention have been described, the description is intended to be illustrative rather than restrictive, and it is apparent to those skilled in the art that many more embodiments and implementations are possible that are within the scope of the disclosure herein. something to do. Accordingly, the disclosure of this specification is not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes can be made within the scope of the appended claims.

100: ball 102: outer surface
200: ball 202: outer surface
204: core 206: cover
300: ball 304: core
308: inner cover layer 310: outer cover layer
400: ball 412: first layer (inner core layer)
414: Second layer (outer core layer) 416: Third layer (inner cover layer)
418: fourth layer (outer cover layer) 420: core
422: cover

Claims (20)

As a ball,
A core comprising a highly neutralized polymer,
A cover comprising a soundproof material and disposed radially outward of the core and surrounding the core
Including,
The core has a first coefficient of repulsion, the ball has a second coefficient of repulsion,
Wherein the difference between said first and second rebound coefficients is greater than 0.026. The ball of claim 1, wherein the first coefficient of repulsion is greater than 0.78. The ball of claim 1, wherein the second coefficient of repulsion is less than 0.79. 4. The ball of claim 3, wherein the second coefficient of repulsion is 0.774. The method of claim 1, wherein the core has at least two layers, wherein at least one layer comprises a highly neutralized polymer, and wherein the cover comprises at least two layers, wherein at least one layer comprises a thermoplastic urethane. Ball to have. delete As a ball,
A core having a compression "x",
A cover surrounding the core
Including,
The coefficient of repulsion of the ball is given by 0.6511-0.024x ² + 0.1165x,
The repulsion coefficient of the core is provided by 0.7951-0.0121x ² + 0.0416x. 8. The ball of claim 7, wherein the repulsion coefficient of the core is greater than 0.78. 8. The ball of claim 7, wherein said ball has a coefficient of repulsion of less than 0.79. 8. The ball of claim 7, wherein the core has one or more layers comprising a highly neutralized polymer. 8. The ball of claim 7, wherein the cover has one or more layers comprising thermoplastic urethane. 8. The ball of claim 7, wherein the rebound coefficient of the ball is lower than the rebound coefficient provided by -0.0103x + 0.8419. As a ball,
A core comprising one or more layers,
A cover comprising one or more layers and positioned radially outward of the core and surrounding the core
Including,
The core has a diameter of at least 38 mm,
At least one core layer comprises a highly neutralized ionomer,
The core has a rebound coefficient greater than a rubber core trend line rebound coefficient, wherein the rubber core trend line rebound coefficient is given by the formula y = -0.0128x ² + 0.055x + 0.7531, where "y" Coefficient of repulsion, where "x" is internal core compression. The ball of claim 1 or 13, wherein the ball has a higher initial velocity than a rubber core ball having a similar non-core layer. The ball of claim 13, wherein the ball has a coefficient of repulsion lower than the coefficient of restitution provided by the formula y = −0.0103 × + 0.8419. The ball of claim 13, wherein the core comprises a highly neutralized polymer. 17. The ball of claim 16, wherein the cover comprises thermoplastic polyurethane. The ball of claim 13, wherein the core consists of two layers, and at least one of the two layers consists of a highly neutralized polymer. The ball of claim 13, wherein the cover consists of two layers, and at least one of the two layers consists of thermoplastic polyurethane. 14. The ball of claim 13, wherein the repulsion coefficient of the ball is lower than the restitution coefficient provided by the formula y = -0.0103x + 0.8299.

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