Ventilation device for an abrasive wheel and abrasive wheel comprising such a ventilation device

Abstract

The invention relates to a ventilation device for an abrasive wheel, the abrasive wheel (4) comprising a hollow circular body, a hub intended to be attached to a drive motor shaft, the circular body comprising an abrasive outer surface (6) comprising openings (7), an inner surface (8) and an inner space defined by the inner surface (8), the ventilation device comprising an annular body (21) and at least one blade (3) that is arranged radially with respect to the annular body (21), the ventilation device (1) being capable of being located within the inner space of the abrasive wheel (4) and the annular body (21) being capable of being rigidly attached to the hub of the abrasive wheel (4) or to the circular body at the periphery of the hub of the abrasive wheel (4).

Description

Description Title of the invention: VENTILATION DEVICE FOR ABRASIVE GRINDING WHEEL AND ABRASIVE GRINDING WHEEL COMPRISING SUCH A VENTILATION DEVICE

[0001] The present invention relates to a ventilation device for an abrasive wheel and an abrasive wheel comprising such a ventilation device, more specifically an abrasive wheel for retreading tires.

[0002] Recurring problems in the field of abrasion of a surface, particularly rubber, especially during tire retreading operations, are the formation of significant heat by friction, at the level of the surface to be abraded, or even the risks of ignition of the abraded particles, and the accumulation of abraded particles in the abrasive material, making the grinding wheel unusable.

[0003] Excessive temperature rise on the abraded surface alters the surface condition of the rubber, which leads to a qualitative reduction in the results of repair operations or the installation of a new tread.

[0004] The increase in temperature of the abraded particles, which become soft and sticky, makes it more difficult to remove them by centrifugal force. These particles tend to accumulate in the abrasive grain of the wheel, literally blocking the abrasive surface, making it smooth and inoperative.

[0005] The abrasive wheels are therefore changed prematurely, before the abrasive grain is completely worn, because the abrasive surface is saturated with abraded particles. The abrasive surface is therefore no longer sufficiently effective and causes the surface to be abraded to heat up too quickly, which can cause fires.

[0006] An abrasive wheel is commonly formed of a circular body equipped with a hub in its center, the outer periphery of the circular body is extended by a rim arranged perpendicular to the circular body, the outer surface of the rim of which is covered with an abrasive material.

[0007] In order to increase the air flow inside the grinding wheel, openings are provided in the circular body, creating an air intake through its openings and an air exhaust towards the open part of the grinding wheel, in the direction of the wheel drive axis.

[0008] To limit the accumulation of abraded particles in the abrasive grain of the wheel, and to theoretically provide airflow towards the surface to be abraded, holes have been made in the abrasive surface.

[0009] However, the air intake from the circular body of the grinding wheel is not directed towards the inner surface of the edge, opposite the abrasive surface.

[0010] In concrete terms, the air flow inside the wheel does not actually contribute to cooling either the abrasive surface or the surface to be abraded.

[0011] The holes arranged in the edge of the wheel do not themselves carry enough abraded particles inside the wheel to limit the clogging of the abrasive surface.

[0012] In addition, the clogging of the abrasive surface is due to hot and sticky particles, the presence of holes on the abrasive surface does not prevent their agglomeration.

[0013] Many developments have been proposed in modifying the abrasive edge orifices, such as US 3,406,489, US 3,579,928, US 3,916,579, but do not appear to contribute to solving the problems cited above.

[0014] Document WO2018 / 177541 proposes to direct the air flow inside the grinding wheel towards the lower surface of the edge, by creating cutouts in the circular body of the grinding wheel, consisting of openings and the counterparts of these openings forming tabs folded inwards.

[0015] The sizing of these tabs is limited by the circular body of the abrasive wheel, and does not appear to be sufficient to create air flow turbulence that can be directed towards the surface to be abraded.

[0016] The present invention proposes a ventilation device capable of being integrated into an abrasive wheel, making it possible to create significant air flows capable of cooling the abrasive surface and the surface to be abraded, making it possible to overcome the aforementioned drawbacks.

[0017] Thus the ventilation device according to the invention, for an abrasive grinding wheel comprising a hollow circular body, a hub intended to be fixed to a drive motor shaft, the circular body comprising an abrasive outer surface comprising orifices, an inner surface and an inner space delimited by the inner surface, the ventilation device comprising an annular body and at least one blade arranged radially relative to the annular body, the ventilation device being able to be located in the inner space of the abrasive grinding wheel and the annular body being able to be fixed integrally to the hub of the abrasive grinding wheel or to the circular body at the periphery of the hub of the abrasive grinding wheel, characterized in that the outer periphery of the at least one blade is able to be located in the vicinity of the inner surface opposite the abrasive outer surface of an abrasive grinding wheel.

[0018] According to one characteristic, the ventilation device is capable of occupying substantially all of the interior space of an abrasive wheel.

[0019] According to an additional feature, the ventilation device is capable of creating air flows creating zones of turbulence as close as possible to the inner surface opposite the abrasive outer surface of an abrasive wheel.

[0020] According to embodiments, the at least one blade has a shape capable of creating an air suction flow from the interior surface to the interior space of the abrasive wheel.

[0021] According to embodiments, the at least one blade has a shape capable of creating an air flow directed towards the interior surface and being expelled through the orifices of the abrasive wheel.

[0022] The invention also relates to an abrasive grinding wheel comprising a hollow circular body, a hub capable of being fixed to a drive motor shaft, the circular body comprising an abrasive outer surface which comprises orifices and an inner surface, the circular body comprising an inner space delimited by the inner surface, characterized in that it comprises the ventilation device according to the invention.

[0023] According to one feature, the at least one blade is located at a distance greater than 0.3 millimeters from the inner surface of the abrasive wheel.

[0024] According to embodiments, the hollow circular body comprises a circular central wall in the extension of the hub, bordered by a rim perpendicular to the circular central wall, commonly called an abrasive wheel.

[0025] According to embodiments, the abrasive wheel comprises two hollow circular bodies assembled to each other, each comprising a semi-toric wall forming a torus, commonly called a donut.

[0026] The implementation of the invention will be better understood with the aid of the detailed description which is set out below with reference to the appended drawings in which:

[0027] Figures 1 to 3 illustrate a ventilation device and an abrasive wheel according to one embodiment of the invention.

[0028] [Fig 1] is a perspective view of a ventilation device assembled to an abrasive wheel.

[0029] [Fig 2] is a front view of Figure 1.

[0030] [Fig 3] is a perspective view of the ventilation device of Figure 1.

[0031] Figures 4 and 5 illustrate a ventilation device and an abrasive wheel according to another embodiment of the invention.

[0032] [Fig 4] is a perspective view of the ventilation device assembled to an abrasive wheel.

[0033] [Fig 5] is a side view of the ventilation device of Figure 4.

[0034] Figures 6 to 8 illustrate a ventilation device and an abrasive donut according to one embodiment of the invention.

[0035] [Fig 6] is an exploded perspective view of a ventilation device and an abrasive donut.

[0036] [Fig 7] is an assembled perspective view of Figure 6.

[0037] [Fig 8] is a perspective view of the ventilation device of Figure 6.

[0038] Figures 9 and 10 illustrate a ventilation device and an abrasive dome according to another embodiment of the invention.

[0039] [Fig 9] is an exploded perspective view of a ventilation device and an abrasive dome.

[0040] [Fig 10] is an assembled front view of Figure 9.

[0041] Figures 11 and 12 illustrate a ventilation device and an abrasive wheel according to one embodiment of the invention.

[0042] [Fig 11] is a perspective view of a ventilation device assembled to an abrasive wheel.

[0043] [Fig 12] is a perspective view of the ventilation device of Figure 11.

[0044] [Fig 13] illustrates temperature measurements of the outer surface of the abrasive wheel in action, as a function of time, during the operation of abrasion of the outer surface of a tire with an abrasive wheel and a ventilation device as illustrated in Figure 11, as well as with an abrasive wheel without the ventilation device.

[0045] The ventilation device (1) according to the invention is an independent part intended to be secured to an abrasive wheel (4).

[0046] A circular abrasive wheel (4) is commonly in the form of a wheel, a torus or a dome, as explained in more detail in the remainder of the description.

[0047] The ventilation device (1) is intended to cool the abrasive outer surface (6) and the substrate to be ground, to contribute to the evacuation of the abraded particles generated by the grinding process and to the cleaning of the grinding wheel, both inside the abrasive grinding wheel (4) and to limit or even drastically reduce the fouling of the abrasive outer surface (6) by the abraded particles.

[0048] During abrasion operations with the ventilation device (1) according to the invention, the abraded particles, instead of gradually increasing in temperature and agglomerating in the abrasive outer surface (6) of the grinding wheel, are directly subjected to powerful air flows, causing them to cool and harden rapidly.

[0049] The cooled and hard particles can no longer clump together in the abrasive outer surface (6) of the grinding wheel, and are in particular ejected to the outside by the rotation of the grinding wheel, as explained in more detail in the rest of the description.

[0050] The ventilation device (1) thus improves the cleanliness of the surface to be abraded and the cleanliness of the grinding wheel as a whole.

[0051] The shape and dimensioning of the ventilation device (1) is produced to order according to the shape and dimensioning of the abrasive wheel (4) in which it is intended to be secured.

[0052] The ventilation device (1) being fixedly assembled to the abrasive wheel (4), it thus rotates at the same speed as the abrasive wheel (4).

[0053] The air flows generated by the ventilation device (1) inside the abrasive wheel (4) increase depending on the rotation speed of the drive motor shaft of a machine tool.

[0054] The higher the rotation speed, the more powerful the air flows generated will be, proportionally compensating for the heating of the abrasive wheel (4) and the surface to be abraded.

[0055] Even at high rotation speed, the abrasive wheel (4) retains the ability to cool the work surface and clean the interstitial spaces between the abrasive grains.

[0056] A machine tool may be a hand-held power machine for abrasive wheels (4) in the form of a wheel, dome or donut, or a stationary workshop machine for abrasive wheels (4) in the form of a wheel or donut.

[0057] It is understood that the wheels and donuts mounted on a stationary machine have larger dimensions and have a rotation speed that is mainly higher than those mounted on a portable electric machine.

[0058] An abrasive wheel (4) may be open as in the case of a wheel or a dome, or closed as in a torus commonly called a donut.

[0059] It is understood that a torus is a so-called open torus, resembling an inner tube.

[0060] An abrasive wheel (4) thus comprises a hollow circular body provided with a hub (5) in its center capable of being connected to a drive motor shaft of a machine tool.

[0061] The circular body is represented by a single wall of revolution in the case of a wheel or a dome and two walls of revolution assembled in opposition for a donut.

[0062] It is understood that the circular body is centered on the periphery of the hub (5).

[0063] The hub (5) consists of a disc-shaped part provided with a circular opening intended to fit around the drive motor shaft of a machine tool.

[0064] A revolution wall of an abrasive wheel comprises a circular central wall (10) and a rim (11) located perpendicular to the outer periphery of the circular central wall (10).

[0065] The circular central wall (10) can be confused with or assimilated to the discoidal part of the hub (5).

[0066] The circular central wall (10) may include a depression extending from the outer periphery of the discoidal portion of the hub (5) to the base of the rim (11), as illustrated in Figure 1, but it could be otherwise, a circular central wall (10) is planar.

[0067] A wall of revolution of a dome open at its base, comprises an elliptical wall whose summit comprises a circular part advantageously provided with a depression directed towards the interior space of the dome. The circular part comprises at its center a discoidal part comprising an opening, the discoidal part and the opening constituting the hub (5), as illustrated in figure 9.

[0068] A revolution wall of a donut comprises a circular central wall (10) constituted by the discoidal part of the hub (5), and a semi-toric wall (12) located at the outer periphery of the circular central wall (10), as illustrated in figure 6.

[0069] The wall of revolution comprises orifices (7) on the abrasive outer surface (6) and advantageously on the circular central wall (10), advantageously distributed regularly.

[0070] The orifices (7) located on the abrasive outer surface (6) are all the more essential in the context of the present invention, since they make it possible to conduct the significant air flows generated by the ventilation device (1), as explained in more detail in the remainder of the description.

[0071] The holes (7) in the abrasive outer surface (6) may be of any shape, such as grooves, circular or hexagonal holes, regularly distributed over the abrasive outer surface (6).

[0072] The greater the proportion of holes (7), the greater the cooling efficiency of the abrasive outer surface (6) and the surface of the substrate to be abraded will be.

[0073] However, the more the proportion of orifice (7) increases, the more the effective abrasion surface of the grinding wheel decreases.

[0074] The ratio between the proportion of orifices (7) and the effective abrasion surface must be modulated, depending on the chosen application, for example a ratio of one third.

[0075] The wall of revolution comprises an outer surface and an inner surface (8).

[0076] The outer surface of the revolution wall comprises at least one portion which comprises an abrasive material.

[0077] In the case of an abrasive wheel, the outer surface of the rim (11) comprises an abrasive material.

[0078] In the case of a dome or donut, substantially the entire outer surface of the wall of revolution comprises abrasive material.

[0079] The inner surface (8) of the wall of revolution of the hollow circular body defines an interior space (9) in which the ventilation device (1) is able to be housed.

[0080] Thus, the ventilation device (1) comprises an annular body (21, 22) and at least one blade (3) arranged radially relative to the annular body (21, 22).

[0081] The annular body (21, 22) comprises an outer circumference from which the blades (3) extend outwards.

[0082] The ventilation device (1) is intended to be coaxially secured to the abrasive wheel (4).

[0083] According to a first alternative, the annular body (21, 22) is a central hub (21), as illustrated in figures 1 to 10. The central hub (21) is capable of being secured to the hub (5) of the abrasive wheel (4), as explained in more detail in the remainder of the description.

[0084] According to a second alternative, the annular body (21, 22) is a ring (22), as illustrated in figures 11 and 12. The ring (22) is capable of being secured to the circular central wall (10) on the periphery of the hub (5) of the abrasive wheel (4), as explained in more detail in the remainder of the description.

[0085] The central hub (21) described in the embodiments illustrated in the figures 1 to 10, is interchangeable with the ring (22) without departing from the scope of the invention.

[0086] Note that the annular body (21, 22) may be a single piece, as shown in the illustrated embodiments, or be composed of several portions in an arc of a circle, the assembly of which with an abrasive wheel (4) forms an annular body (21, 22), but it could be otherwise: the annular body (21, 22) is composed of an assembly of rectilinear portions, the general shape of which, when assembled with an abrasive wheel (4), forms a regular polygon having a rotation of order n, such as a hexagon, an octagon, etc.

[0087] The number of blades (3) and their distribution around the annular body (21, 22) must of course be balanced, so that the rotation of the assembly formed by the abrasive wheel (4) and the ventilation device (1) is stabilized and homogeneous.

[0088] The ventilation device (1) may comprise two, three, four, five or more blades (3), or a single blade (1) for example in the form of a skirt, not shown.

[0089] Figures 4 and 9 illustrate ventilation devices (1) comprising five blades, Figure 1 illustrates a ventilation device (1) comprising six blades, Figure 6 illustrates a ventilation device (1) comprising twelve blades, and Figures 11 and 12 illustrate a ventilation device (1) comprising 16 blades.

[0090] The central hub (21) is intended to be fitted around the drive motor shaft of a machine tool, and to be fixed to the hub (5) of the abrasive wheel (4).

[0091] The ring (22) is intended to be fixed securely, for example by welding or riveting to the circular central wall (10) on the periphery of the hub (5) of the abrasive wheel (4), coaxially with the drive motor shaft of a machine tool.

[0092] The rotation speed of the motor shaft and the weight of the abrasive wheel (4) being important, it is understood that the solid attachment of the device of ventilation (1) to the abrasive wheel (4) must be carried out without play.

[0093] It is therefore imperative that any untimely vibration of the assembly consisting of the abrasive wheel (4) and the ventilation device (1) around the motor shaft is avoided.

[0094] The integral fixing of the central hub (21) of the ventilation device (1) to the hub (5) of the abrasive wheel (4) can be achieved by a mechanical connection, by welding or by gluing.

[0095] The mechanical connection of the hub (5) of the abrasive wheel (4) and the central hub (21) of the ventilation device (1) to the drive motor shaft may be achieved by any means known in the field of fixing a hub to a motor shaft, such as with a coupling adapter also called a hub-shaft locking device, for example a threaded shaft and a nut, or the combination of keys and grooves, or pins, etc.

[0096] It is also conceivable that the central hub (21) of the ventilation device (1) comprises a sleeve which is fitted into the hub (5) of the abrasive grinding wheel (4) and fitted around the drive motor shaft, as illustrated in figure 10. The rotational guidance is for example achieved by the combination of bores and ribs or keys, not illustrated.

[0097] The central hub (21) comprises a discoidal part whose inner periphery delimits the opening intended to be fitted around the drive motor shaft, and whose outer periphery is extended by blades (3) or is connected to blades (3).

[0098] Any blade shape (3) located in the interior space (8) of the circular body of the abrasive wheel (4), will create an air flow inside the wheel, during the rotation of the assembly formed by the abrasive wheel (4) and the ventilation device (1).

[0099] However, in order to cool the abrasive surface and the surface to be abraded, the periphery of a blade (3) requires being close, advantageously as close as possible, to the inner surface (8) located opposite the abrasive outer surface (6) of the abrasive wheel (4).

[0100] According to embodiments, not illustrated, the ventilation device (1) is capable of extending throughout the interior space (9) of the abrasive wheel (4).

[0101] According to the preceding embodiments, the blades (3) extend to the inner surface (8) located opposite the abrasive outer surface (6), namely are in contact with the inner surface (8) of the abrasive wheel (4).

[0102] According to embodiments, the ventilation device (1) is capable of extending throughout substantially the entire interior space (9) of the abrasive wheel (4).

[0103] According to the preceding embodiments, at least a portion of the periphery of a blade (3) is located in the vicinity of at least a part of the inner surface (8) located opposite the abrasive outer surface (6).

[0104] In order to optimize the internal air flows of the grinding wheel and to support a concentric air circulation on the internal wall of the grinding wheel and in order to avoid any deposition of particles on the internal wall of the grinding wheel and between a blade (3) and the internal surface (8) of the abrasive grinding wheel (4), it is recommended that the distance between the blades (3) and the internal surface (8) be greater than or equal to three times the average size of the abraded particles.

[0105] The average size of the abraded particles is dependent on the size of the abrasive grains of the abrasive surface, and is of the order of 0.1 to 1 millimeter.

[0106] According to an additional characteristic, the outer periphery of a blade (3) located opposite the inner surface (8) arranged opposite the abrasive outer surface (6), is located at a distance greater than or equal to 0.3 millimeters, advantageously remaining nearby, namely in the vicinity of the inner surface (8).

[0107] The outer periphery of a blade (3) is understood to mean the end or tip of the blade (3) located furthest from the annular body (21, 22).

[0108] By proximity to the inner surface (8) is meant a distance between 0.3 millimeters and 70%, preferably 50%, more preferably 30% of the radius of the abrasive wheel, or the radius of the base of a dome, or the diameter of the torus of a donut, depending on the required use and the diameter of the abrasive wheel (4).

[0109] According to one characteristic, the outer periphery of a blade (3) located opposite the inner surface (8) arranged opposite the abrasive outer surface (6), is located at a distance less than or equal to 70%, preferably 50%, more preferably 30% of the radius of the abrasive wheel, or of the radius of the base of a dome, or of the diameter of the torus of a donut.

[0110] Preferably, the outer periphery of a blade (3) located opposite the inner surface (8) arranged opposite the abrasive outer surface (6), is located at a distance less than or equal to 50% of the radius of the abrasive wheel, or of the radius of the base of a dome, or of the diameter of the torus of a donut.

[0111] More preferably, the outer periphery of a blade (3) located opposite the inner surface (8) arranged opposite the abrasive outer surface (6), is located at a distance less than or equal to 30% of the radius of the abrasive wheel, or of the radius of the base of a dome, or of the diameter of the torus of a donut.

[0112] According to embodiments, the outer periphery of a blade (3) located opposite the inner surface (8) arranged opposite the abrasive outer surface (6), is located at a distance of between 0.3 millimeters and 70%, preferably 50%, more preferably 30% of the radius of the abrasive wheel.

[0113] According to embodiments, the outer periphery of a blade (3) located opposite the inner surface (8) arranged opposite the abrasive outer surface (6), is located at a distance of between 0.3 millimeters and 70%, preferably 50%, more preferably 30% of the radius of the base of a dome.

[0114] According to embodiments, the outer periphery of a blade (3) located opposite the inner surface (8) arranged opposite the abrasive outer surface (6), is located at a distance of between 0.3 millimeters and 70%, preferably 50%, more preferably 30% of the diameter of the torus of a donut.

[0115] The general profile of the ventilation device (1) may be flat or include a depression at the periphery of the annular body (21, 22) in order to adapt to the possible depression of the circular central wall (10) of the abrasive wheel (4). The possible depression of the ventilation device (1) is materialized by the profile of the blades (3).

[0116] The orientation and shape of a blade (3) according to the direction of rotation of the abrasive wheel (4) generates air flows either of suction from the outside towards the inside of the wheel through the orifices (7) of the abrasive outer surface (6), or of exhaust air from the inside towards the outside of the wheel through the orifices (7) of the abrasive outer surface (6).

[0117] The profile of a blade (3) can be flat or curved.

[0118] A flat blade (3) arranged perpendicular to the axis of rotation of the motor shaft, generates, regardless of the direction of rotation of the grinding wheel, air flows from the inside to the outside of the grinding wheel. More precisely, an air intake along the axis of rotation of the motor shaft and an air exhaust in a direction perpendicular to the axis of rotation of the motor shaft.

[0119] Figures 6 to 8 illustrate a donut-shaped abrasive wheel (4) and a ventilation device (1) comprising blades (3) arranged perpendicular to the central hub (21).

[0120] Thus, according to the embodiment illustrated in figures 6 to 8, the ventilation device (1) comprises a central hub (21) consisting of a discoidal part and flat blades (3) arranged perpendicular to the discoidal part of the central hub (21).

[0121] According to the previous embodiment, the blades (3) are discs welded perpendicular to the central hub (21).

[0122] According to one embodiment, not illustrated, the abrasive wheel (4) is a dome and the ventilation device (1) comprises a central hub (21) and blades (3) arranged perpendicular to the central hub (21).

[0123] According to another embodiment, not illustrated, the abrasive wheel (4) is a wheel comprising a depression extending from the outer periphery of the discoidal part of the hub (5) to the base of the edge (11), the device ventilation (1) comprises a central hub (21) and blades (3) arranged perpendicular to the central hub (21).

[0124] Considering a counterclockwise direction of rotation, a flat blade (3) making an angle with the axis of rotation of the motor shaft, for example 45°, or a curved blade (3), whose leading edge is located in the vicinity of or in contact with the inner surface (8) of the abrasive wheel (4) and whose trailing edge is located in the direction of the opening of the abrasive wheel (4), generates an intake of air from the rear, namely in the direction of the periphery of the hub (5), and an exhaust of air from the front, namely in the direction of the opening of the abrasive wheel (4) in the shape of a dome or wheel, and generates a radial suction phenomenon at the end of the blade (3), namely at the edge (11) of a wheel or at the largest diameter part of a dome.

[0125] According to the embodiment illustrated in Figures 9 and 10, the abrasive wheel (4) is a dome and the ventilation device (1) comprises flat blades (3) oriented at 45° relative to the central hub (21). The blades (3) are in the vicinity of the inner surface (8) of the dome, namely that the blades (3) are not in contact with the inner surface (8) of the abrasive wheel (4).

[0126] According to the embodiment illustrated in figures 4 and 5, the abrasive wheel (4) is a wheel comprising a depression extending from the outer periphery of the discoidal part of the hub (5) to the base of the edge (11), the ventilation device (1) comprises a central hub (21) and curved blades (3) whose profile is intended to adapt to the depression of the abrasive wheel.

[0127] According to the preceding embodiment, the leading edge of a blade (3) is oriented towards the inner surface (8) of the central part (10), the trailing edge of a blade (3) is oriented towards the opening of the abrasive wheel (4), and the tip of a blade (3) is oriented opposite the inner surface (8) of the border (11).

[0128] According to another embodiment illustrated in Figures 1 to 3, the abrasive wheel (4) is an abrasive wheel comprising a depression extending from the outer periphery of the discoidal part of the hub (5) to the base of the edge (11), the ventilation device (1) comprises a central hub (21) and V-shaped blades (3) oriented in the counterclockwise direction and arranged in the depression of the abrasive wheel (4).

[0129] According to the preceding embodiment, a blade (3) comprises a descending flat part oriented radially relative to the central hub (21), a flat part parallel to the discoidal part of the central hub (21) and a rising flat part oriented counterclockwise following the curvature of the periphery of the discoidal part of the central hub (21).

[0130] According to the preceding embodiment, the descending planar portion comprises an opening and a fin, the fin being the counterpart of the opening, which is bent inwardly towards the inner surface of the central portion circular (10). This opening and this tab contribute to driving the air flow along the rising flat part. The fins also contribute to forming turbulence in the center of the wheel, preventing the deposit of abrasive particles within the abrasive wheel (4), promoting its internal cleaning.

[0131] As previously introduced, upon counterclockwise rotation, the air flow is brought along the upper surface of the rising flat portion, generating a radial suction flow of air via the orifices (7) arranged in the border (H).

[0132] According to the embodiment illustrated in figures 11 and 12, the ventilation device (1) comprises a ring (22) whose annular wall extends radially outwards by blades (3).

[0133] According to the previous embodiment, a blade (3) is composed of a branch which extends radially in a coplanar manner with respect to the outer circumference of the ring (22), and is extended by a flat wall oriented at 45° with respect to the branch.

[0134] According to the preceding embodiment, the ring (22) comprises fixing orifices regularly distributed on its annular wall. The fixing orifices are capable of being secured to the circular central wall (10) on the periphery of the hub (5) of the abrasive wheel (4) by riveting. The circular central wall (10) comprises complementary fixing orifices, not shown, to those of the ventilation device (1).

[0135] Abrasion tests, as illustrated in Figure 13, of a tire surface were carried out using an abrasive wheel and the ventilation device (1) as shown in Figure 11, as well as with only an abrasive wheel without ventilation device, as a control test. These tests were carried out by exerting a substantially continuous force for 330 seconds. The temperature measurements of the outer surface of the grinding wheel were carried out using an infrared thermometer. The temperature measurements were carried out with an interval of 15 seconds. The temperature measurements take into account the differential with the ambient temperature, namely that the first measurement has a temperature equal to zero degrees Celsius. The pressure exerted by the tool on the tire surface was deliberately as strong as possible given the resistance of the machine tool, so as to accentuate friction and the rise in temperature.The tire matrix was almost pierced in several places.

[0136] At the end of the test carried out with the abrasive wheel and the ventilation device (1) as shown in Figure 11, the interior and exterior of the abrasive wheel remained perfectly clean, the abrasive outer surface (6) being completely free of abraded particles. The abrasive outer surface (6) was slightly dulled, due to the abrasion of the metal wires inside the tire matrix. The tire surface was warm to the touch, which is unusual. In Normally, abraded particles which heat up systematically become embedded in the interstices of the grains of the abrasive surface.

[0137] Indeed, at the end of the abrasion control test, the abrasive wheel without ventilation device, has a deposit of abraded particles covering the entire interior surface of the wheel. Although the control test is relatively short, in comparison with real use, the abrasive surface of the control wheel still shows a significant accumulation of abrasive particles.

[0138] The temperature measurements of the outer surface of the abrasive wheel including the ventilation device (1) as illustrated in Figure 11 are almost half as high after 330 seconds as those taken by the control wheel without ventilation device.

[0139] For dome or donut type abrasive wheels, an air evacuation phenomenon from the inside to the outside towards the abrasive outer surface (6) seems to be preferred, particularly for a donut in order to avoid the accumulation of abraded particles inside the toric shape of the wheel.

[0140] For abrasive wheels, suction or air flow blowing phenomena towards the abrasive surface can be used.

[0141] As introduced previously, the rise in temperature of the substrate to be abraded makes the particles soft and sticky which agglomerate in the interstices of the abrasive outer surface (6), making the abrasive wheel (4) unusable.

[0142] Let us recall that the ventilation device (1) according to the invention creates powerful air flows, which allow the abraded particles, the abrasive surface and the surface to be abraded to be kept at a low temperature.

[0143] In addition to the ejection, by centrifugal force, of the abraded particles towards the outside of the grinding wheel, the suction of the abraded particles through the orifices (7) of the abrasive outer surface (6), greatly limits or even prevents the aggregation of these particles in the grains of the abrasive outer surface (6), increasing its useful life.

[0144] Furthermore, the creation of air flows blowing towards the inner outer surface (8) of the abrasive wheel (4) by the ventilation device (1), creates a phenomenon of ejection of the abraded particles in contact with the outer abrasive surface (6), which in synergy with the centrifugal force, expels the abraded particles, preventing their possible agglomerations in the outer abrasive surface (6).

[0145] The physical wear of the abrasive materials seems to become the only limit to the longevity of the assembly formed by the abrasive wheel (4) and the ventilation device (1) according to the invention.

Claims

Demands

1. A ventilation device (1) for an abrasive wheel, said abrasive wheel (4) comprising a hollow circular body, a hub (5) for being fixed to a drive shaft, the circular body comprising an abrasive outer surface (6) having orifices (7), an inner surface (8) and an inner space (9) delimited by the inner surface (8), the ventilation device (1) comprising an annular body (21, 22) and at least one blade (3) arranged radially with respect to the annular body (21, 22), the ventilation device (1) being able to be located in the inner space (9) of the abrasive wheel (4) and the annular body (21, 22) being able to be fixed rigidly to the hub (5) of the abrasive wheel (4) or to the circular body on the periphery of the hub (5) of the abrasive wheel (4), characterized in that the outer periphery of at least one blade (3) is able to be located in the vicinity of the inner surface (8) opposite the outer abrasive surface (6) of an abrasive wheel (4).

2. Ventilation device (1) according to claim 1, characterized in that it is capable of occupying substantially the entire interior space (9) of an abrasive wheel (4).

3. Ventilation device (1) according to claim 1 or 2, characterized in that it is capable of creating airflows creating turbulent zones as close as possible to the inner surface (8) opposite the outer abrasive surface (6) of an abrasive wheel (4).

4. Ventilation device (1) according to any one of the preceding claims, characterized in that at least one blade (3) has a shape suitable for creating an air suction flow from the inner surface (8) to the inner space (9) of the abrasive wheel (4).

5. Ventilation device (1) according to any one of claims 1 to 3, characterized in that at least one blade (3) has a shape suitable for creating an airflow directed towards the inner surface (8) and for being expelled through the orifices (7) of the abrasive wheel (4).

6. Grinding wheel (4) comprising a hollow circular body, a hub (5) suitable for being fixed to a drive shaft, the circular body comprising an abrasive outer surface (6) which includes orifices (7) and an inner surface (8), the circular body comprising an inner space (9) delimited by the inner surface (8), characterized in that it comprises the device of ventilation (1) according to any one of the preceding claims.

7. Abrasive grinding wheel (4) according to the preceding claim, characterized in that at least one blade (3) is located at a distance greater than 0.3 millimeters from the inner surface (8) of the abrasive grinding wheel (4).

8. Abrasive wheel (4) according to claim 6 or 7, characterized in that the hollow circular body comprises a circular central wall (10) in the extension of the hub (5), bordered by a rim (11) perpendicular to the circular central wall (10), commonly called an abrasive wheel.

9. Abrasive grinding wheel (4) according to claim 6 or 7, characterized in that it comprises two hollow circular bodies assembled together, each comprising a semi-toric wall (12) forming a torus, commonly called a donut.

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