EP3216561B1

EP3216561B1 - Double-sided grinding disc with quick-change system

Info

Publication number: EP3216561B1
Application number: EP17159603.4A
Authority: EP
Inventors: Adrianus Gerardus Van Houten; Barry Johannes Van Eijden
Original assignee: Blastrac BV
Current assignee: Blastrac BV
Priority date: 2016-03-11
Filing date: 2017-03-07
Publication date: 2021-04-14
Anticipated expiration: 2037-03-07
Also published as: CN207289812U; EP3216561A1; NL2016421B1

Description

The present invention relates to a grinding disc for a surface-grinding machine, in which the grinding disc has a first and a second grinding side. Both grinding sides are each provided with at least one grinding element, in such a way that both grinding sides are usable for grinding a surface. In a central region, the grinding disc has an interface for coupling the grinding disc by means of a screw connection by means of a screw having a conical screw head to an adapter of a floor-grinding machine.
Furthermore, the invention relates to a grinding machine, in particular a floor or wall grinding machine and an assembly of an adapter and grinding disc which form a quick-change system.
Such a grinding disc is known from NL1028002 (family member of US20060154583 A1 ), on which the preamble of claim 1 is based. The known grinding disc for a floor-grinding machine comprises a metal plate-shaped disc body with a first and second grinding side.
The two grinding sides are provided with diamond-containing grinding elements. Both sides of the grinding disc are thus usable for a grinding operation. The grinding disc is attachable to a floor-grinding machine by means of a screw connection. The grinding disc has a central opening for coupling to a drive shaft of the grinding machine. The central opening is delimited by an edge with a corrugated shape. Two pairs of conical recessed boreholes are provided around the central opening. A first pair of recessed bolt holes is provided on the first grinding side and a second pair of recessed screw holes is provided on the second grinding side.
Although this known grinding disc can be attached relatively easily, it is a drawback of this known attaching arrangement of the grinding disc that the ease of use is not optimal. A quicker way of attaching such a grinding disc is desirable.
Numerous quick-connect systems for grinding discs are known from the prior art. However, a large number of these quick-connect systems are not exchangeable for use with a double-sided grinding disc.
In particular, the grinding disc of interest is a grinding disc for a grinding machine for grinding floors, walls or ceilings, such as for example known from US 7,326,106 . The grinding disc has to be of robust design in order to be able to absorb the forces occurring during grinding, for example, a granite floor or concrete wall. The quick-connect system for the grinding disc also has to be robust.
US 5,927,264 for example discloses a grinding disc for single-sided use and provided with a quick-connect system. The grinding disc is provided with two fastening pins which are positioned off centre on the rear side of a grinding disc. The fastening pins can be inserted into corresponding holes in an adapter plate, after which the grinding disc can be secured to the adapter plate by fitting nuts to both fastening pins. Due to the fastening pins on the grinding disc, the disc can only be attached in one way and is not reversible. The quick-connect system is thus not compatible for use with a double-sided grinding disc.
In addition, it is a further drawback of this known system that the speed with which the disc can be coupled to the adapter plate leaves much to be desired, despite it being referred to as a quick-connect system. Fitting both nuts still takes a significant amount of time.
EP 2,915,630 discloses a magnetic quick-connect system for attaching an annular grinding element with abrasive material on one grinding side. The quick-connect system provides a magnetic coupling between an adapter and the annular grinding element, in which a locking system for axial retention is provided, as an alternative to a screw connection with a series of screws. Furthermore, drivers in the form of pins are provided which fit into corresponding holes in the annular grinding element. The drivers prevent a relative rotating movement between the annular grinding element and the adapter.
A drawback of this known quick-connect system is that the magnets only allow a coupling on one side, making reversal of the grinding element impossible. As a result thereof, the quick-connect system with magnets is not compatible for use with a double-sided grinding disc. In addition, the locking system has many components which makes the coupling complicated.
EP 1,795,301 discloses a quick-connect system with a bayonet fastening. The quick-connect system requires corresponding coupling members in order to form the bayonet fastening in each grinding disc to be coupled. A drawback is that manufacturing such a grinding disc is laborious, which results in a high cost price of the grinding disc.
It is an object of the present invention to at least partly overcome at least one of the abovementioned drawbacks, or to provide a usable alternative.
This object is achieved by a grinding disc for a floor-grinding machine according to claim 1.
The grinding disc according to the invention comprises a first and a second grinding side. Both grinding sides are provided with at least one grinding element. The grinding element has an abrasive surface and consists of, for example, a block-shaped element with diamond- containing material. Preferably, the grinding element is a separate detachable grinding element, in which the grinding element is detachable from a disc body of the grinding disc. Due to the grinding elements on both grinding sides, the grinding disc is double-sided. The two grinding sides of the grinding disc are usable for grinding a floor, ceiling or wall.
In a central region, the grinding disc has an interface for coupling the grinding disc by means of a screw connection to an adapter of a floor-grinding machine. The adapter is configured to connect the grinding disc to a rotatably drivable drive shaft of the grinding machine.
The interface comprises a central hole. The hole is a fastening hole for inserting a screw. The hole is a through-hole from the first to the second grinding side of the grinding disc. The grinding disc according to the invention provides an improvement, as the through-hole has a conical opening on both sides of the grinding disc. The conical opening serves to receive a conical screw head of a screw. Furthermore, the interface comprises at least a driver recess for receiving a driver on a bearing surface of the adapter. The driver recess is positioned at a distance from the through-hole in the radial direction.
The grinding disc according to the invention can provide various advantages.
A first advantage is the fact that the invention provides a quick-connect system, also referred to as a quick-change system, for a double-sided grinding disc. A grinding disc can quickly be exchanged for another grinding disc, but the grinding disc can also quickly be refitted in a reversed orientation in order to use the second grinding side instead of the first grinding side.
The invention provides the advantage that only a single screw is required to be able to provide attachment of a grinding disc to an adapter. Only a single screw has to be tightened in order to fasten the grinding disc. As a result thereof, the grinding disc can quickly be detached, reversed and reattached.
Advantageously, the same through-hole with a conical opening on both sides can be used both for a screw connection of the grinding disc, in which the first grinding side is mounted as the active grinding side, and for a screw connection of the grinding disc in a reverse orientation, in which the second grinding side is mounted as the active grinding side.
In an embodiment of the grinding disc according to the invention, the conical opening has a depth which is greater than or equal to the height of the conical screw head of the screw.
Preferably, the screw is a standard screw. In other words, a standard issue article. Preferably, the screw is a standard article, for example a standardized M8 screw with a conical screw head.
It is advantageous if the screw head of the screw which provides a screw connection for the grinding disc to the adapter is level with, or more preferably below, a surface of a disc body. Preferably, the screw head is fully recessed on a respective grinding side with respect to the surface of the disc body. Thus, the risk of the screw head dragging during a grinding operation and causing damage, such as a scratch, is minimized.
The grinding disc according to the invention is attached using a screw instead of using a bolt. Here, as on Wikipedia, the difference between a bolt and a screw is understood to mean that with a bolt the shank is provided with a head which is usually hexagonal and by means of which the bolt can be tightened on the outside - meaning externally (according to NEN 5501). If the possibility of tightening is however provided by a recess in the head - meaning internally - then this is referred to as a screw. The recess may in this case be, for example, a straight slot, a cross slot, a Robertson or hex socket, a six-pointed star or a twelve-pointed star.
In an embodiment of the grinding disc according to the invention, the grinding disc comprises a star disc body. Preferably, the disc body is made of steel. Preferably, the disc body has a disc thickness of at most 8 mm. Preferably, the disc body has a disc thickness of at least 5 mm. The at least one grinding element is positioned on an end surface of the disc body. The disc body is preferably plate-shaped, with the disc body having a substantially constant disc thickness. More preferably, the disc body is circular. This embodiment of the grinding disc contributes to the dynamic stability of the grinding disc during a grinding operation. Vibrations during a grinding operation are thus prevented.
In an embodiment of the grinding disc according to the invention, the grinding disc comprises a through-hole with an inner diameter for the screw connection of the grinding disc to the adapter by means of an M8 screw, in which the M8 screw has a conical screw head. The through-hole has a hole length and a conical opening on both sides of the grinding disc which fits the screw head of the M8 screw. By means of the M8 screw, a secure screw connection can be achieved, in which the geometry of the screw head advantageously allows a disc thickness of at most 8 mm. With these optimum dimensions of the combination of disc thickness and screw size, the conical openings do not overlap and are separate from each other.
In an embodiment of the grinding disc according to the invention, the at least one driver recess of the grinding disc comprises a contour with a curved contour segment. The contour segment of the recess comprises a convex curvature. In contrast to a circular driver recess for receiving a pin-shaped driver, which has a concave curvature, the convex curvature advantageously provides an improved grip of the driver of the adapter on the driver recess of the grinding disc due to centrifugal action. The convex curvature provides a socket-shaped enclosure for the driver, with the centrifugal action during a grinding operation contributing to an improved grip between the adapter and the grinding disc. As a result of the improved grip of the driver, it is advantageously possible to achieve reduced wear between the driver and the driver recess, thus preventing unwanted play and vibrations.
In an embodiment of the grinding disc according to the invention, the at least one driver recess of the grinding disc comprises a contour with a contour segment which comprises at least a double curve. The double curve is S-shaped. The S shape of the contour segment results in both a concave and a convex portion. In contrast to a circular driver recess for receiving a pin-shaped driver, which only has a single curve, the contour segment with the double curve provides improved grip of the adapter to the grinding disc. The double curve advantageously provides an increased surface compared to a circular driver recess for contacting the driver, as a result of which loads are distributed more evenly across the driver. As a result thereof, wear may be prevented.
In an embodiment of the grinding disc according to the invention, the driver recess is mirror-symmetrical over a radial line. Advantageously, the driver recess comprises curved contour segments for both possible directions of rotation, in such a way that the action of the driver recess with curved contour segments is independent of a driven direction of rotation of the grinding disc. A first curved contour segment is provided for a clockwise direction of rotation, while a second curved contour segment is provided for a counter-clockwise direction of rotation.
In an embodiment of the grinding disc according to the invention, the grinding disc comprises at least two, preferably at least four driver recesses. Advantageously, loads which occur during the grinding operation are evenly distributed over the drivers of the adapter, as a result of which the grinding disc remains dynamically stable.
In an embodiment of the grinding disc according to the invention, the at least one driver recess of the grinding disc comprises an internal and/or external tangential straight contour segment on a contour. Advantageously, the tangential contour segment enables accurate positioning of the grinding disc with respect to the adapter, which contributes to dynamic stability during a grinding operation.
In an embodiment of the grinding disc according to the invention, the disc body comprises a first grinding side provided with at least one grinding element and a second side which is without a grinding element. The grinding disc may be provided with at least one grinding element receiver, for example at least a tapped hole for attaching a grinding element, on the second side.
In an embodiment of the grinding disc according to the invention, the disc body comprises at least one tongue on a periphery of the disc body. The tongue may be formed by adjacent indentations which extrend from the periphery of the disc body towards the central region. Advantageously, the at least one grinding element may be positioned on the tongue. Preferably, a pair of grinding elements is positioned on the tongue, in which case the pair comprises a grinding element with a rectangular cross section and a grinding element with a circular cross section.
In an embodiment of the grinding disc according to the invention, the disc body comprises a series of tongues along the periphery, in which, in the series of tongues every other tongue is provided with at least one grinding element and an adjacent tongue is without a grinding element.
Furthermore, the invention relates to a grinding machine according to claim 10.
Furthermore, the invention relates to a quick-change system according to claim 8.
Further embodiments are defined in the other subclaims.
The invention will be explained in more detail with reference to the attached drawings. The drawings form a practical embodiment of the invention and may not be interpreted as being limiting.

Fig. 1 shows an exploded view in perspective of an assembly of a grinding disc, adapter and fastening screw;
Fig. 2 shows a perspective view of the assembly from Fig. 1, in which the grinding disc is fitted to the adapter by means of the fastening screw;
Fig. 3 shows a top view of the grinding disc from Fig. 1;
Fig. 4 shows a top view of the adapter from Fig. 1.

In the figures, identical reference numerals are used to indicate similar components.
Fig. 1 shows an exploded view in perspective of an assembly of a grinding disc 1, an adapter 2 and a fastening screw 3. By means of the screw 3, the grinding disc 1 can be attached to the adapter 2. As a component of a quick-change system, the adapter 2 is configured to couple the grinding disc 1 to a drive shaft of a grinding machine, in particular a floor-grinding or wall-grinding machine.
Fig. 2 shows the assembly from Fig. 1 in a perspective view, in which the grinding disc 1, the adapter 2 and the fastening screw 3 are shown in a fitted position.
The grinding disc 1 is configured for grinding a floor or wall. The grinding disc 1 is, for example, configured for grinding a stone floor, for example a granite floor or a façade wall. The grinding disc is configured for coupling to a floor-grinding machine.
The grinding disc 1 is substantially circular. The grinding disc 1 has a disc body 10 with a constant disc thickness. Here, the disc thickness is 8 mm. The disc body 10 is made of steel. The disc body 10 is rigid and forms a robust base, which is able to withstand the strong forces which occur when grinding a floor or wall.
The grinding disc 1 relates to a double-sided grinding disc. The grinding disc can be used twice by reversing the grinding disc during use. The grinding disc 1 has a first grinding side 11 and second grinding side 12. The first and second grinding sides 11, 12 are each provided with at least one grinding element 19. Here, the at least one grinding element 19 comprises an elongate grinding element 19.1 and a cylindrical grinding element 19.2. The elongate grinding element 19.1 has a rectangular cross section. The cylindrical grinding element 19.2 has a circular cross section. The elongate and cylindrical grinding elements 19.1 and 19.2 form a pair and are positioned next to each other. The pair of grinding elements 19.1 and 19.2 are positioned near the periphery, the outer edge, of the grinding disc 1. Each pair of grinding elements 19.1 and 19.2 is positioned on a tongue 18 of the grinding disc 1.
The grinding disc has several tongues 18 along the periphery. The tongues 18 are formed by slot-shaped indentations along the periphery. Here, the grinding disc has a series of eighteen tongues, in which every other tongue is provided with at least one grinding element and a tongue is without a grinding element, respectively.
As Fig. 3 shows, the grinding disc 1 has an interface 13 in a central region CA for coupling the grinding disc 1 to an adapter 2 of a floor-grinding machine by means of a screw 3. The screw 3 has a conical screw head 31 and a screw shank 32. In this case, the screw is an M8 screw. The M8 screw is a standardized article. The interface 13 is positioned in a region of the disc body 10 which is situated inside the indentations which form the tongues 18.
The interface 13 comprises a through-hole 14. The through-hole 14 is a fastening hole for passing through a screw shank. The through-hole 14 extends from the first grinding side 11 to the second grinding side 12. On both the first and the second grinding side, the through-hole has a conical opening 141 for receiving a conical head of a screw 3. The geometry of the conical opening 141 corresponds with the geometry of the conical screw head 31 of the screw 3. As illustrated in Fig. 2, the conical opening 141 preferably has a depth which is greater than or equal to the height of the conical screw head 31 of the screw 3, in such a way that the head of the screw 3 does not protrude above a grinding side 11 or 12 when the grinding disc 1 has been attached to the adapter 2. The head of the screw 3 is preferably completely recessed below the surface forming the grinding side. Due to the presence of a conical head 141 on both sides of the grinding disc, the grinding disc with a first orientation and a second orientation which is opposite to the first orientation may be attached to the adapter 2 in such a way that both grinding sides 11, 12 of the grinding disc 1 can be used.
Furthermore, the interface 13 comprises at least one driver recess 15. The driver recess 15 is positioned at a distance with respect to the through-hole 14 in a radial direction. Here, the interface 13 comprises four driver recesses 15. The driver recesses 15 are evenly distributed around the through-hole 14. Here, the driver recesses 15 are of identical shape. The driver recesses 15 are four-fold rotationally symmetrical, in such a way that the grinding disc 1 fits onto an adapter under four different angles. This contributes to a quick and secure installation of the grinding disc 1 onto an adapter.
As illustrated in Fig. 4, the adapter 2 has a bearing surface 21 for applying the grinding disc 1. In the bearing surface, the adapter 2 has a number of elements for fastening the grinding disc 1. In the centre of the bearing surface, the adapter 2 has a tapped hole. The tapped hole is a threaded borehole for securing a screw. Around the tapped hole 24, at least one driver 25 is provided. In a radial direction, the driver 25 is positioned at a distance with respect to the tapped hole 24. Here, the bearing surface 21 comprises four drivers 25.
The driver 25 protrudes above the bearing surface 21. Preferably, the driver protrudes at least 3 mm above the bearing surface 21. The driver 25 protrudes at most 8 mm, in particular at most 5 mm above the bearing surface 21. The driver 25 forms an elevated portion with respect to the bearing surface 21 which is smaller than the disc thickness of the disc body 10. As a result thereof, the driver does not protrude above a grinding side of the grinding disc during use.
The drivers 25 are evenly distributed around the tapped hole 24. Here, all drivers are identical in shape. The shape of the drivers corresponds with the shape of the driver recesses in the interface 13, in such a way that a relative rotating movement between the grinding disc and the adapter is prevented when fitting a grinding disc.
The driver 25 and the corresponding driver recess 15 are of a design which contributes to durable use of the grinding disc. The design is such that wear of the driver recess 15 with respect to the driver 25 remains limited.
The driver 25 comprises an external profile with several profile segments 25.1, 25.2, 25.3, 25.4. The driver 25 is mirror-symmetrical over a radial line. The external profile has an internal straight profile segment 25.1 which extends in a tangential direction. Furthermore, the external profile has an external straight profile segment 25.2 which extends in a tangential direction.
The design of the driver 25 comprises curved profile segments. The external profile comprises a first and second profile segment 25.3, 25.4, each of which comprises a double curve. The curved profile segments are S-shaped. The first curved profile segment 25.3 is mirror-symmetrical over a radial line with the second curved profile segment 25.4. The curved profile segments 25.3, 25.4 extend from the internal straight profile segment 25.1 to the external straight profile segment 25.2.
The design of the driver recess 15 corresponds with the design of the driver 25.
The driver recess 15 comprises a contour with several contour segments 15.1, 15.2, 15.3, 15.4. The driver recess 15 is mirror-symmetrical over a radial line. The contour has an internal straight contour segment 15.1 which extends in a tangential direction. Furthermore, the contour has an external straight contour segment 15.2 which extends in a tangential direction.
The contour of the driver recess 15 comprises curved contour segments. The contour comprises a first and second contour segment 15.3, 15.4, each of which comprise a double curve. The curved contour segments are S-shaped. The first curved contour segment 15.3 is mirror-symmetrical with the second curved contour segment 15.4. The curved contour segments 15.3, 15.4 extend from the internal straight contour segment 15.1 to the external straight contour segment 15. 2.
It should be noted that aspects according to the invention and in particular aspects mentioned in the dependent claims are regarded as being independently patentable, separately from aspects in the other claims. These aspects may, for example, become the subject of divisional patent applications, in which these aspects are defined independently from the aspects which are presently included in the independent claims or other dependent claims.
Many variants are possible in addition to the embodiments illustrated in the figures, without departing from the scope of the protection of the claims. In a variant of the illustrated embodiment of the interface, the interface may have only one single driver recess instead of four.
The invention is not limited to the illustrated and described embodiments, but all embodiments which fall within the definition of the attached claims are within the scope of protection of the invention.
Thus, the invention provides a quick-change system according to claim 8. The quick-change system is advantageous, because only a single screw has to be loosened in order to reverse the double-sided grinding disc. In addition, the quick-change system is robust due to the design of the at least one driver, which is preferably provided with a concave driver profile segment.

Key:

1	Grinding disc	25	Driver profile segment
11	First grinding side	25.2	External straight profile segment
12	Second grinding side	25.3	Curved profile segment
18	Tongue	25.4	Curved profile segment
19	Grinding element	3	Fastening screw
13	Interface	31	Screw head
14	Through-hole	32	Screw shank
141	Conical opening
15	Driver recess
15.1	Internal straight contour segment
15.1	Internal straight contour segment
15.3	Curved contour segment
15.4	Curved contour segment
2	Adapter
21	Bearing surface
24	Tapped hole

Claims

Grinding disc (1) for a floor-grinding machine comprising a disc body (10) with a first and a second grinding side (11, 12), in which both grinding sides (11, 12) are each provided with at least one grinding element (19), in such a way that both grinding sides (11, 12) are usable for grinding a floor, in which the grinding disc (1) has an interface in a central region for coupling the grinding disc by means of a screw connection to an adapter (2) of a floor-grinding machine, wherein the interface (13) comprises a central through-hole extending from the first to the second grinding side, and the interface (13) comprises at least a driver recess (15) for receiving a driver (25) which is provided on a bearing surface (21) of the adapter (2), and the driver recess (15) is positioned at a radial distance with respect to the through-hole (14), characterized in that the through-hole (14) has a conical opening (141) on both sides of the grinding disc for receiving a conical screw head (31) of a screw (3).
Grinding disc according to claim 1 in which the grinding disc has the disc body (10) with a disc thickness of at most 8 mm.
Grinding disc according to claim 2, in which the through-hole has an inner diameter for the screw connection of the grinding disc to an adapter by means of an M8 screw with a conical screw head (31).
Grinding disc according to any of the preceding claims, in which the at least one driver recess (15) comprises a contour with a contour segment (15.3, 15.4), in which the contour segment comprises a curvature such that the contour segment is convex.
Grinding disc according to claim 4, in which the contour segment (15.3, 15.4) comprises at least a double curve.
Grinding disc according to claim 4 or 5, in which the driver recess (15) is formed so as to be mirror-symmetrical over a radial line.
Grinding disc according to any of claims 4-6, in which the grinding disc comprises at least two, in particular at least four driver recesses (15).
Quick-change system comprising a grinding disc (1) according to any of the claims 1-7 and an adapter and a screw (3) with a conical screw head (31) for attaching the grinding disc (1) to a floor-grinding or wall-grinding machine wherein the adapter (2) comprises a bearing surface (21) with a tapped hole (24) in a central region (CA) for receiving a screw shank (32) of the screw (3) in order to attach the grinding disc (1), in which at least one driver (25) is provided which is positioned at a radial distance with respect to the tapped hole (24) and protrudes above the bearing surface (21).
Quick-change system according to claim 8, in which the at least one driver (25) comprises an external profile with a curved concave profile segment (25.3, 25.4).
Grinding machine comprising a quick-change system according to claim 8 or 9.