Device for measuring static imbalance in tire

Abstract

The invention relates to a device (10) for measuring a static imbalance in a tyre (P), the measuring device (10) comprising a weighing table (12) comprising a horizontal measuring plane (14) mounted on at least three weighing units, means for automatically positioning the tyre on the weighing table, and a processing unit (28), the invention relates to a tyre weighing station (10) comprising a plurality of weighing units (28) arranged at regular intervals on a single reference circle, positioning means capable of placing a tyre (P) with one of the sidewalls on a measuring plane (14) of the weighing station, positioning means capable of centering the tyre (P) in an automatic manner with respect to the center of the reference circle of the weighing units, and a processing unit (28) connected to each weighing unit.

Description

Technical Field

[0001] The present invention relates to the measurement of static imbalance in tires. Background Art

[0002] Patent application EP3901603 describes a machine for measuring imbalance in a wheel, which machine includes a rotating shaft on which the wheel is mounted, a sensor for measuring the imbalance force generated during the rotation of the shaft, an angle sensor for measuring the angular position of the shaft, and an electronic device for determining, based on the information sent by the sensors, the value and position of the correction mass to be applied to the wheel to eliminate the imbalance force.

[0003] Furthermore, patent application EP3901603 also includes means for projecting a light spot onto the wheel to indicate the position of the correction mass to be applied.

[0004] The rotating machine described in patent application EP3901603 is specifically designed for the measurement of imbalance in a wheel (i.e., an assembly consisting of a rim and a tire mounted to the rim).

[0005] In the case where this type of rotating machine is only used for the measurement of imbalance in a tire, for example, during the quality control process just after the tire is produced, it is necessary to pre-mount the tire to a rim that must be perfectly balanced, and it is also necessary to inflate the tire to the appropriate air pressure. In addition, it is usually also necessary to lubricate the bead wires of the tire in order to correctly mount the tire to the rim.

[0006] Finally, once the imbalance is measured, the tire must be removed from the rim.

[0007] Although an operator can relatively easily mount a passenger vehicle tire to a rim and remove it from the rim, this is not the case for tires designed for heavy trucks or airplanes.

[0008] For these larger and heavier tires, even with the assistance of automated devices for gripping and mounting / dismounting, the operator's operation time for mounting the tire to the rim and removing the tire from the rim is longer.

[0009] Finally, the machine described in patent application EP3901603 is more specifically designed for, for example, the measurement of imbalance in a wheel mounted on a vehicle, or for the measurement of imbalance in a tire that has just been produced but is preferably of the passenger vehicle type. Summary of the Invention

[0010] The object of the present invention is to eliminate the drawbacks of the rotating machines for measuring imbalance according to the prior art.

[0011] To this end, the subject of the present invention is a device for measuring static imbalance in a tire, the measuring device comprising a weighing table, means for automatically positioning the tire on the weighing table, and a processing unit, the weighing table comprising a horizontal measuring plane mounted on at least three weighing units, the weighing units being arranged at regular intervals on a single reference circle contained in a horizontal plane, the positioning means being capable of automatically placing the tire with one of its sidewalls on the horizontal measuring plane of the weighing table, the positioning means being capable of automatically centering the tire with respect to the center of the reference circle of the weighing units, the processing unit being connected to each weighing unit such that when the tire is placed in a stationary and centered manner on the measuring plane of the weighing table, each weighing unit transmits the value of the mass it supports to the processing unit.

[0012] Since the measurement is carried out by means of the weighing table, the measuring device according to the present invention can avoid mounting the tire on a rim or an equivalent support. Furthermore, since the measurement is carried out by means of the weighing table, the measuring device according to the present invention can easily and quickly adapt to tires of different sizes. In fact, when the size of the tire to be measured changes, there is no longer any need to change the tire rim or support.

[0013] Thanks to the automatic positioning means, manual handling of the tire is eliminated. This is particularly advantageous for carrying out imbalance measurements on large and heavy tires (such as tires designed for aircraft or heavy goods vehicles), especially during the quality control process in their production plants.

[0014] According to another advantage, the measuring device according to the present invention can both identify the position of the imbalance in the tire and determine the mass of the tire, which is advantageous for implementing quality control at the end of production.

[0015] Advantageously but not mandatorily, the present invention may also include the following:

[0016] - The means for positioning the tire on the weighing table is a robotic arm or an automatic gantry equipped with means for gripping the tire, the means for gripping the tire having inner jaws or outer jaws; - The measuring device is equipped with a system for acquiring the entry position of the tire; - The measuring device includes means for marking the position of the static imbalance determined by the processing unit on the tire, preferably with a red dot; - The means for marking the position of the static imbalance includes an output conveyor for receiving the tire to be marked and a robotic arm equipped with a marker, the robotic arm being preferably a pneumatic robotic arm; - The measuring device includes an entry conveyor for the tire and an intermediate conveyor for the tire, the positioning means being capable of automatically picking up the tire on the entry conveyor in order to automatically transport and place the tire on the measuring plane of the weighing table, and being capable of automatically picking up the tire on the measuring plane of the weighing table in order to automatically transport and place the tire on the intermediate conveyor.

[0017] The subject matter of the present invention also includes a method for measuring static imbalance in a tire, which implements the device for measuring static imbalance in a tire according to the present invention.

[0018] According to the first method, the tire is first placed on the measurement plane of the weighing table in an automatic manner by a positioning device, and then picked up from the weighing table in an automatic manner so as to be re-placed on the weighing table in an automatic manner for the second time, so as to achieve better centering relative to the reference circle of the weighing unit. Then, the weighing unit performs at least one measurement on the supported mass for at least one position of the tire on the measurement plane of the weighing table, and sends the information to the processing unit.

[0019] For example, in the first method, before the weighing unit measures the supported mass, the tire is picked up and re-placed on the measurement plane of the weighing table in an automatic manner several times by the positioning device, preferably at least three times.

[0020] According to the second method, the measuring device is equipped with a system for acquiring the entry position of the tire. Before the tire is grasped by the positioning device, the entry position of the tire is acquired by the measuring device. Then, the tire is transported to the measurement plane of the weighing table in an automatic manner by the positioning device. The centering of the tire on the measurement plane of the weighing table is achieved by previously acquiring the entry position of the tire. Then, the weighing unit performs at least one measurement on the supported mass for at least one position of the tire on the measurement plane of the weighing table, and sends the information to the processing unit.

[0021] In the context of implementing the measuring method according to the present invention, the following are also possible:

[0022] - The weighing unit performs the measurement at the end of a non-zero period after the tire is placed on the measurement plane of the weighing table; - The weighing unit measures the supported mass for several positions of the tire on the measurement plane of the weighing table around the center of the reference circle of the weighing unit; - The weighing unit measures the supported mass for X positions of the tire on the measurement plane of the weighing table, and the angle in degrees between each position and the next position is equal to 360 / (X + 1). Description of the Drawings

[0023] Further features and advantages of the present invention will become apparent from the following description. The following description is given by way of non-limiting example with reference to the accompanying drawings, in which:

[0024] Figure 1 is a perspective view of the device for measuring static imbalance in a tire according to the present invention;

[0025] Figure 2is a top view of a device for measuring static imbalance in a tire according to the present invention;

[0026] Figure 3 is a front view of a device for measuring static imbalance in a tire according to the present invention. Detailed Description of the Invention

[0027] The present invention relates to a device 10 for measuring static imbalance in a tire, such as the device shown by the example in Figure 1 The example in.

[0028] The measuring device 10 is designed to measure static imbalance in all types of tires.

[0029] Measuring the imbalance in a tire can first determine whether the measured imbalance is within the tolerance range specified by the manufacturer of the tire or within the tolerance range specified by the future user of the tire (such as an aircraft manufacturer). Measuring the mass and position of the imbalance in the tire can also add patches, i.e., rubber blocks, on the opposite side of the position of the imbalance in the tire. Finally, measuring the mass and position of the imbalance in the tire can mount the tire onto the rim such that the imbalance of the tire is on the opposite side of the imbalance of the rim on which it is mounted.

[0030] According to the present invention, the device 10 for measuring static imbalance in a tire includes a weighing platform 12, which includes a horizontal measuring plane 14 mounted on at least three weighing units 16, and these weighing units are arranged at regular intervals on a single reference circle 18 contained in a horizontal plane PH (such as the measuring plane 14).

[0031] The weighing unit is a weighing sensor of the central support point type.

[0032] To measure static imbalance in a tire, at least three weighing units are required. In the case where the weighing platform includes three weighing units, these weighing units are arranged relative to each other at 120°. However, the weighing platform can also include four or more weighing units. In all cases, all the weighing units of the weighing platform are preferably arranged at regular intervals on a single reference circle 18 contained in the horizontal plane PH.

[0033] More specifically, the weighing platform 12 includes a bracket 20, which supports a mounting plane 22, and the weighing units 16 are mounted on the mounting plane 22 around its reference circle 18. The measuring plane 14 is flatly mounted on the weighing units 16 in the form of a circular plate 24 and is centered relative to the reference circle 18 of the weighing units.

[0034] To avoid the operator from operating on the tire, the device 10 for measuring static imbalance in a tire includes a device 26 for automatically positioning the tire P on the weighing platform 12.

[0035] In order to be able to determine the position and mass of the static imbalance based on the information sent by the weighing unit, the tire to be measured must be placed on the measuring plane 14 with one of its sidewalls, and the tire placed in this way must be centered relative to the reference circle 18 of the weighing unit.

[0036] Therefore, the positioning device 26 can automatically place the tire to be measured on the horizontal measuring plane 14 of the weighing table with one of its sidewalls, and the positioning device 26 can also automatically center the tire P relative to the center of the reference circle 18 of the weighing unit 16. For this purpose, the positioning device 26 knows the position of the center of the reference circle 18 of the weighing unit 16. For example, the positioning device 26 has previously obtained the position of the center of the reference circle 18 of the weighing unit 16 through learning with a calibration template.

[0037] In order to estimate the position and mass of the static imbalance in the tire P placed on the measuring plane 14 and centered, the device 10 for measuring the static imbalance in the tire includes a processing unit 28 connected to each weighing unit 16, such that when the tire P is placed on the measuring plane 14 of the weighing table in a stationary and centered manner, each weighing unit 16 transmits the mass value it supports to the processing unit 28.

[0038] For example, the device 26 for positioning the tire P on the weighing table 12 is a robotic arm 30 equipped with a device 32 for gripping the tire (this device has an inner jaw 34). The robotic arm 30 can be a robotic arm with 3, 4, or 5 moving axes. The device 32 for gripping the tire includes, for example, three inner jaws 34 designed to grip the tire from the inside (i.e., at the bead wire of the tire). The inner jaws 34 are mounted on a star-shaped support 36, which includes as many branches as there are inner jaws. For example, the inner jaws 34 include movable hooks 38, and the hooks 38 are, for example, swingably mounted at their lower ends in order to grip the tire through one of the bead wires of the tire.

[0039] Alternatively, the positioning device 26 can be an automatic gantry capable of moving the gripping device 32 along multiple axes (this variant is not shown in the drawings).

[0040] As an alternative to the inner jaws, the gripping device 32 can be equipped with outer jaws for clamping the tire from the outside (the variant is not shown).

[0041] In order to avoid the positioning device deforming the tire, it is possible to provide an adjustment of the clamping torque of the jaws of the gripping device 32. In fact, this type of deformation will have an adverse effect on the centering of the tire on the weighing table and will cause deviations in the determination of the mass and position of the static imbalance in the tire.

[0042] In order to be able to add a patch (i.e., a rubber block) on the opposite side of the unbalanced position in the tire, or to mount the tire on the rim such that the unbalance of the tire is on the opposite side of the unbalance of the rim on which it is mounted, the measuring device 10 may include a device 46 for marking (preferably with a red dot) the position of the static unbalance determined by the processing unit on the tire.

[0043] For example, the device 46 for marking the position of the static unbalance includes an output conveyor 48 for receiving the tire to be marked and a robotic arm 50 equipped with a marker 52, which is preferably a pneumatic robotic arm. For example, the output conveyor 48 is a belt conveyor.

[0044] For the entry and conveyance of the tire P to be measured to the weighing table 12, and for the conveyance from the weighing table to the output conveyor 48, the measuring device 10 may include an entry conveyor 54 for the tire and an intermediate conveyor 56 for the tire. The positioning device 26 can pick up the tire on the entry conveyor 54 in an automatic manner in order to convey and place it automatically on the measuring plane 14 of the weighing table 12, and can pick up the tire P on the measuring plane of the weighing table in an automatic manner in order to convey and place it automatically on the intermediate conveyor 56. For example, the entry conveyor 54 and the intermediate conveyor 56 are belt conveyors.

[0045] Ideally, in order to facilitate the conveyance process of the tire, the entry conveyor 54, the intermediate conveyor 56 and the output conveyor 48 are placed one after the other in this order.

[0046] In order to be able to transfer the tire P between the three conveyors in the event of a malfunction of the weighing table 12 or the positioning device 26, the weighing table 12 is arranged parallel to the three conveyors. Preferably, the weighing table 12 is arranged parallel to the intermediate conveyor 56.

[0047] Alternatively, the measuring device 10 may only include an entry conveyor and an output conveyor (this variant is not shown in the drawings). In this case, the weighing table is aligned with the two conveyors and is located between the two conveyors.

[0048] In order to identify the entry position of the tire P, for example on the entry conveyor 54, the measuring device 10 may be equipped with a system 60 for acquiring the entry position of the tire P. For example, the acquisition system 60 is a camera 62 supported by the positioning device 26. The entry position of the tire P is the position where the tire P is grasped by the clamping device 32 when the tire P reaches the input end of the measuring device. Alternatively, the acquisition system 60 may be mounted on a support independent of the positioning device 26.

[0049] According to the present invention, the measurement of the static imbalance in the tire P consists in identifying the eccentricity of the center of gravity of the tire caused by the imbalance present in the tire. Using the measuring device 10 according to the present invention, the measurement of the static imbalance in the tire P consists in identifying the position of the center of gravity of the tire relative to the center of the reference circle 18 of the weighing unit, thereby identifying the eccentricity. The eccentricity of the center of gravity of the tire is determined by the processing unit 28 based on the information sent by the weighing unit 16 (i.e., the mass supported by each weighing unit). Then, knowing the eccentricity of the center of gravity and the distance at which a patch (rubber block) can be applied to the tire (e.g., inside the tire), the processing unit 28 can determine the mass of the patch. The relationship used by the processing unit is as follows: imbalance (in grams·meters) = total mass of the tire (in grams) × eccentricity (in meters). In the context of the present invention, the mass and position of the static imbalance are calculated on the median plane of the measured tire.

[0050] The present invention also relates to a method for measuring the static imbalance in the tire P, which implements the measuring device 10 according to the present invention.

[0051] According to the first measuring method, the tire P is first automatically placed by the positioning device 26 on the measuring plane 14 of the weighing table, and then automatically picked up from the weighing table 12 in order to be automatically re-placed on the weighing table 12 at least a second time, so as to achieve better centering relative to the reference circle 18 of the weighing unit.

[0052] To further improve the centering of the tire P on the measuring plane of the weighing table, the tire P can be automatically picked up and re-placed on the measuring plane of the weighing table 12 several times by the positioning device 26, preferably at least three times. At each new pick-up, the position of the tire gets closer and closer to the perfectly centered position on the weighing table.

[0053] After this or these operations of picking up and re-placing the tire P on the weighing table, the weighing unit 16 performs at least one measurement of the mass it supports for at least one position of the tire P on the measuring plane 14 of the weighing table, and sends this information to the processing unit 28.

[0054] According to the second measuring method aimed at avoiding the operation of picking up and re-placing the tire P on the weighing table, before the tire is grasped by the positioning device 26, the entry position of the tire is acquired by the measuring device 10 (specifically, by the acquisition system 60), and then the tire is automatically transported by the positioning device to the measuring plane 14 of the weighing table. The centering of the tire P on the measuring plane of the weighing table is achieved by pre-acquiring the entry position of the tire. Then, the weighing unit 16 performs at least one measurement of the mass it supports for at least one position of the tire on the measuring plane 14 of the weighing table, and sends this information to the processing unit 28.

[0055] In any of the above measurement methods, in order to avoid deviations in the measurements performed by each weighing unit due to vibrations, it can be stipulated that the weighing unit 16 performs the measurement at the end of a non-zero period after the tire P has been placed on the measurement plane 14 of the weighing table. This non-zero period corresponds to the stabilization time of the measured value sent by the weighing unit, which varies according to the size and stiffness of the tire. For example, the weighing unit 16 performs the measurement within 2 to 40 seconds after the tire P has been placed on the measurement plane 14 of the weighing table.

[0056] In order to more precisely and reliably determine the position of the center of gravity of the tire P, and also in any of the above two measurement methods, it can be stipulated that the weighing unit 16 measures the mass it supports for several positions taken by the tire P around the center of the reference circle 18 of the weighing unit on the measurement plane of the weighing table. This thus limits the possibility of calculation errors due to random positions of imbalance relative to the weighing unit. Since the tire P must be centered on the measurement plane of the weighing table, between two different measurement positions, the tire P only needs to be rotated around the center of the reference circle of the weighing unit 16 by the positioning device 26. During the change of the position of the tire on the weighing table, the positioning device preferably picks up the tire and then replaces it on the weighing table. During each change of the position of the tire on the weighing table, several pick-up and replacement operations can also be performed, and / or the measurement can only be carried out by the weighing unit at the end of a non-zero period after the tire P has been replaced in a new position on the measurement plane 14 of the weighing table.

[0057] More specifically, the weighing unit 16 measures the mass it supports for X positions of the tire P on the measurement plane of the weighing table, and the angle (in degrees) between each position and the next is equal to 360 / (X + 1). For example, 3 to 9 positions of the tire P on the measurement plane of the weighing table are used to determine the static imbalance in each tire.

Claims

1. A device (10) for measuring the static imbalance in a tyre (P), the measuring device (10) comprising a weighing table (12), means (26) for automatically positioning the tyre on the weighing table, and a processing unit (28), the weighing table (12) comprising a horizontal measuring plane (14) mounted on at least three weighing units (16), the weighing units being arranged at regular intervals on a single reference circle (18) contained in a horizontal plane, the positioning means being able to place the tyre (P) on the horizontal measuring plane of the weighing table in an automatic manner with one of its sidewalls, and being able to centre the tyre (P) automatically with respect to the centre of the reference circle (18) of the weighing units, the processing unit (28) being connected to each weighing unit (16) such that when the tyre (P) is placed in a stationary and centred manner on the measuring plane of the weighing table, each weighing unit transmits the mass value it supports to the processing unit.

2. The device (10) for measuring the static imbalance in a tyre according to claim 1, wherein, The device (26) for positioning the tire on the weighing table is a robotic arm (30) or an automatic gantry equipped with a device (32) for gripping the tire, and the device for gripping the tire has inner jaws (34) or outer jaws.

3. The device (10) for measuring the static imbalance in a tyre according to any one of the preceding claims, the measuring device (10) being equipped with a system (60) for acquiring the entry position of the tyre (P).

4. The device (10) for measuring the static imbalance in a tyre according to any one of the preceding claims, further comprising means (46) for marking on the tyre the position of the static imbalance determined by the processing unit, preferably with a red dot.

5. The device (10) for measuring the static imbalance in a tyre according to claim 4, wherein, The device (46) for marking the position of the static imbalance includes an output conveyor (48) for receiving the tire to be marked, and a robotic arm (50) equipped with a marker (52), and the robotic arm is preferably a pneumatic robotic arm.

6. The device for measuring the static imbalance in a tyre according to any one of the preceding claims, further comprising an entry conveyor (54) for the tyre and an intermediate conveyor (56) for the tyre, the positioning means (26) being able to pick up the tyre (P) automatically on the entry conveyor (54) in order to transport and place the tyre automatically on the measuring plane of the weighing table, and being able to pick up the tyre (P) on the measuring plane of the weighing table in order to transport and place the tyre automatically on the intermediate conveyor (56).

7. A method for measuring the static imbalance in a tyre (P), which implements the device (10) for measuring the static imbalance in a tyre according to any one of the preceding claims, wherein, The tire (P) is first placed on the measuring plane (14) of the weighing table in an automatic manner by the positioning device (26), and then picked up from the weighing table in an automatic manner so as to be re-placed on the weighing table in an automatic manner for the second time, so as to achieve better centering relative to the reference circle (18) of the weighing unit. Then, the weighing unit (16) performs at least one measurement on the supported mass for at least one position of the tire (P) on the measuring plane of the weighing table, and sends the information to the processing unit (28).

8. The method for measuring the static imbalance in a tyre according to claim 7, wherein, Before the weighing unit measures the supported mass, the tire (P) is picked up and re-placed on the measuring plane of the weighing table (12) several times in an automatic manner by the positioning device (26), preferably at least three times.

9. A method for measuring the static imbalance in a tire (P), which is implemented according to the device (10) for measuring the static imbalance in a tire as claimed in any one of claims 1 to 6, wherein, The measuring device (10) is equipped with a system for obtaining the entry position of the tire. Before the tire is grabbed by the positioning device (26), the entry position of the tire is obtained by the measuring device (10). Then, the tire is transported to the measuring plane (14) of the weighing table in an automatic manner by the positioning device. The centering of the tire (P) on the measuring plane of the weighing table is achieved by pre-obtaining the entry position of the tire. Then, the weighing unit (16) performs at least one measurement on the supported mass for at least one position of the tire on the measuring plane of the weighing table, and sends the information to the processing unit (28).

10. The method for measuring the static imbalance in a tire as claimed in any one of claims 7 to 9, wherein, The weighing unit (16) performs the measurement at the end of a non-zero period after the tire (P) is placed on the measuring plane (14) of the weighing table.

11. The method for measuring the static imbalance in a tire as claimed in any one of claims 7 to 10, wherein, The weighing unit (16) measures the supported mass for several positions of the tire (P) on the measuring plane of the weighing table around the center of the reference circle (18) of the weighing unit.

12. The method for measuring the static imbalance in a tire as claimed in claim 11, wherein, The weighing unit measures the supported mass for X positions of the tire on the measuring plane of the weighing table, and the angle in degrees between each position and the next position is equal to 360 / (X + 1).

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