EP2915630B1

EP2915630B1 - A wheel-holder flange for grinding cup wheels, with a quick-release system for the wheel

Info

Publication number: EP2915630B1
Application number: EP15156979.5A
Authority: EP
Inventors: Dino Zandonella Necca; Ferruccio Gonzo; Werner Ricciolini
Original assignee: ADI SpA
Current assignee: ADI SpA
Priority date: 2014-03-03
Filing date: 2015-02-27
Publication date: 2017-01-04
Anticipated expiration: 2035-02-27
Also published as: PL2915630T3; ES2620499T3; EP2915630A1

Description

The present invention relates to a wheel-holder flange for grinding cup wheels provided with a system for the quick release of the wheel from the flange, having the characteristics stated in the preamble to Claim 1, which is the principal claim. A wheel-holder flange of the type outlined above, which is provided with a locking device activated by the centrifugal action generated in the rotation of the wheel, is known by JP 2003-145432 .
The invention is particularly, but not exclusively, applicable to the field of grinding for machining materials in sheet form, which have to be machined at their edges by grinding operations in order to bring the workpieces to the desired size. These grinding operations generally require a plurality of grinding positions, in order to distribute the removal of material over a plurality of points or in order to execute a progressive finishing sequence.
Typically, the sheets to be ground to size and subjected to finishing are square or rectangular in shape, and are processed on high-output automatic lines.
Machines used for machining tiles, such as tiles made of ceramic material, are known as trimmers, while those used for glass sheets are called bilateral or straight grinders, according to their configuration. The aforesaid system is also used for machining other materials, known in the technical field by the English names of "engineered stone" and "ultra compact surface materials". The invention is particularly applicable to the aforementioned grinding machines which use grinding cup wheels.
Machines using cup wheels usually comprise different mandrels, on which the wheels are fitted, on each side. For machining ceramic tiles, the number of mandrels per side varies, for example, from 4 to 8, giving a total of 16 or 32 wheels per machine. Similar configurations may also be found in machines (of the bilateral type) for machining glass sheets. There are configurations having a greater number of wheels than those mentioned above, both in the aforesaid types of machines and in other applications.
The wheels are normally centred on a shaft and are fastened to it by tightening a series of screws for fastening the wheel to a wheel-holder flange, which in turn is fixed in rotation to the shaft of a motor or of a rotation transmission system. The wheels are typically protected by a safety housing system, which is also used for the containment of the coolant liquid. Normally, the protection system does not facilitate access to the wheel by maintenance personnel if the wheel on the flange has to be maintained or replaced.
One of the main objects of the invention is to simplify the operation of replacing the wheel tool on machines of the aforesaid type, thereby also making this operation faster. This is because, owing to the considerable number of wheels mounted on these machines, the time required for tool changing results in machine stoppages which may adversely affect the output of the machining line. Additionally, in order to increase the speed of movement of the workpieces, and hence the output, there is a tendency to increase the number of grinding stations, to provide better distribution of the removal of material. In these lines, therefore, machine stoppages becomes detrimental to the maintenance of the output of an installation, especially as the machines concerned are usually combined in lines with other parts of the plant (such as continuously operating kilns or tempering stations), so that a machine stoppage may also have a significant effect on other parts of the plant.
The object of the invention is therefore to provide a wheel-holder flange for cup wheels which is structurally and functionally designed to overcome the aforesaid limitations of the cited prior art.
This and other objects, which will be evident from the following text, are achieved by the invention by means of a wheel-holder flange for grinding cup wheels made in accordance with the appended claims.
The features and advantages of the invention will be more apparent from the following detailed description of some preferred examples of embodiment thereof, illustrated, purely for guidance and in a non-limiting way, with reference to the appended drawings, in which:

Figures 1 and 2 are perspective views of a first example of a wheel-holder flange according to the invention, shown in combination with a grinding cup wheel, with some parts detached,
Figure 3 is a partial view in axial section, and on an enlarged scale, of the flange and wheel assembly of the preceding figures;
Figures 4 and 5 are views in lateral elevation of the wheel-holder flange of the preceding figures, in two different operating conditions of the wheel,
Figure 6 is an exploded perspective view of a second example of a wheel-holder flange according to the invention, shown in combination with a grinding cup wheel, with some parts detached,
Figures 7 and 8 are partial view in axial section, and on an enlarged scale, of the flange and wheel assembly of Figure 6, in two different operating conditions of the wheel.

With initial reference to Figures 1 and 5, the number 1 indicates the whole of a first example of a wheel-holder flange for a cup wheel 2, made in accordance with the present invention.
The cup wheel 2 is of the type comprising a disc-shaped support 3, substantially axially symmetrical with a main axis X, pierced centrally so as to have an annular configuration. From one of the opposite faces of the support 3 there extends the abrasive material, shaped for example in the form of a ring with a cylindrical shell 4, applied to the support by adhesive bonding, welding or moulding, or by any other suitable fastening system.
The wheel 2 can be locked removably on the flange 1, coaxially with the latter, so as to be fixed in rotation about an axis of rotation coinciding with the main axis X. In turn, the flange is designed to be fixed in rotation to a driving shaft (not shown) by means of which the flange and cup wheel assembly is made to rotate about the axis X.
The flange 1 is also disc-shaped, with a central through hole 5 for coupling the flange to the driving shaft, and can be fastened with the cup wheel 2 by means of a first and a second locking device, indicated by 6 and 7 respectively, which are described in detail below.
The first device 6 is designed for locking the wheel support 3 on the flange 1 by magnetic attraction. It conveniently comprises a plurality of permanent magnets, all indicated by 8, positioned with a regular angular intervals along an outer circumferential band of the flange 1, so that each has a front surface 8a for contacting a corresponding surface portion of the wheel support. Respective cavities, indicated by 8b, are provided in the flange 1 to house the corresponding magnets 8. Each magnet 8 is fastened to the flange in a removable manner, for example by using a respective screw means 8c engaged in a corresponding threaded hole 8d provided in the flange.
The number and sizes of the magnets 8 are selected in such a way that the magnetic locking force is sufficient to ensure locking between the wheel and the flange, in opposition to the stress usually generated by the abrasion forces exerted by the workpiece on the wheel. By way of example, with reference to the configuration described, 18 magnets are conveniently provided for a wheel measuring 300 mm in diameter, with an attractive force per unit of about 80 N, giving a total force of about 1440 N. With smaller wheel diameters, it may be convenient to choose a smaller number of magnets.
The number 9 indicates a cut-out formed on the outer circumferential edge between the flange 1 and the wheel 2, for receiving the end of a lever or similar detaching tool, by means of which the wheel can be removed from the flange, overcoming the magnetic locking force. This enables the wheel to be detached rapidly from the flange, which is particularly advantageous in the operation of changing the wheel.
In addition to the locking action of the device 6, the second device 7 is made to provide a safety locking action between the wheel and the flange, in order to prevent the detachment of the wheel during its operation in use, for example as a result of anomalous stresses that may develop during the grinding operation, and that are potentially capable of overcoming the magnetic locking force of the first device 6. Such an event may occur, for example, if the workpiece breaks, when the workpiece may become caught in the wheel, creating stresses that may cause the wheel to be detached from the flange in a hazardous manner. The second device 7 is designed to be activated, advantageously, by the effect of the forces of a centrifugal nature generated by the rotation of the wheel in the operating phase, and, conversely, to be disengaged, without causing any locking action, below a specified rotation speed of the wheel, and particularly when the wheel is not subject to rotation.
The device 7 comprises a pair of retaining blocks 10, which are held in such a way as to be able to slide in a limited manner on the flange 1 and are able to be radially urged, by centrifugal action, to engage in a recess 11 provided in the wheel support 3, so as to oppose relative movements between the flange and the wheel support, principally in the axial direction, during the rotary movement of the wheel.
The retaining blocks 10 are positioned on the flange in an axially symmetrical position with respect to the main axis X. Since they are structurally identical to one another, only one of them will be described in detail below.
Each block 10 is disc-shaped and, in particular, is centrally pierced so as to have an annular profile. The block is housed in a floating manner in a respective seat 12, formed in a portion of the flange 1 located between the central hole 5 and the circumferential band containing the magnets 8.
The seats 12 are formed on a diametral plane, at 180° to one another, and are mirror-symmetrical about a plane passing through the axis X and perpendicular to the aforesaid diametral plane.
Each seat 12 is formed by a cavity made in the flange and can be closed in a removable manner by a cap 13, for example by means of fastening screws 14. The seat 12 also has an opening 15, radially facing the support 3, the size of this opening being predetermined in such a way that the block 10 housed in the seat can project, when impelled by centrifugal action, beyond the opening 15 to a certain extent (limited by the interference between the block and the opening), so as to engage in the recess 11 formed in the support 3. More particularly, the recess 11 is formed by a groove having a closed circular profile, running circumferentially around the hole passing centrally through the support.
The cavity of each seat 12 is delimited by opposed lateral walls 18, extending from the opening 15 towards an opposed end wall 19.
The opposed lateral walls 18 comprise respective opposed portions 18a of wall with an inclined profile converging towards the opening 15 of the seat.
According to this configuration, the block 10 can be returned into the seat 12, thereby disengaging the recess 11, when, in the absence of rotation of the wheel, the flange 1 is orientated in a predetermined position such that each block is moved, by the gravitational force acting on it, along the respective inclined portion 18a.
Figure 4 shows the aforementioned position, in which the main axis of the wheel 2 is located perpendicularly to the vertical direction of action of the gravitational force and the diametral plane of symmetry intersecting the blocks 10 is substantially perpendicular to the vertical direction of action of gravity. In this condition, each block 10, subject to gravity, is urged to slide along the respective inclined portion until it returns fully into the seat 12, thus disengaging the recess 11.
Conversely, when the wheel is rotated, the blocks 10 are urged radially by the centrifugal forces acting on them until they project from the respective openings 15 to engage the recess 11, as shown clearly in Figure 5. In this condition, each block engages a portion of the recess 11 indicated by L in the drawing, so as to hold the flange and the wheel support together, mainly in the axial direction, thereby opposing any relative movements tending to detach the wheel from the flange. When the wheel is stationary, the device 7 therefore automatically releases the respective locking system, as described above.
The angle of inclination A, indicated in Figure 4, of the portion 18a of the wall 18 is conveniently chosen to be greater than 20°, in the case of a configuration with two blocks.
If the chosen configuration has three blocks, they are positioned at 120° to one another to provide better balancing, and the angle A is usefully chosen to be greater than 30°. According to a preferred choice, the angle A is chosen to be greater than 35°. This choice enables the blocks 10 to be disengaged from the recess 11 by orientating the wheel in a position in which, still with the axis X perpendicular to the vertical direction, one of the blocks is aligned along the vertical direction of gravitational action.
Figures 6 to 8 show a second exemplary embodiment of the invention, differing from the first substantially in the different shape of the blocks and of the seats for housing them. Details corresponding to those of the previous example are identified by the same reference numerals.
In this example, each block 10' comprises a base 20 having a cylindrical profile, from which a portion 21 with a frustoconical profile extends. A shoulder 22 is provided between the base 20 and the portion 21, as is clearly shown in Figures 7 and 8.
Each corresponding seat 12' in the flange 1 is formed in a cavity which has a bottom 23 with a conical profile for receiving, substantially with a positive connection, the frustoconical portion 21 of the block 10'.
As a result of this configuration, each block 10', when urged radially by the centrifugal force generated by the rotation of the wheel, can slide relative to the bottom 23 of the seat, until it projects through the opening 15, so as to engage the recess 11 of the wheel support with part of its cylindrical base 20.
The frustoconical configuration of the block advantageously enables the block to be returned into the seat under the effect of gravity when the wheel, having stopped, is orientated with its main axis parallel to the vertical direction of gravitational action. Thus, for cup wheels operating in the orientation described (with the axis of rotation lying vertically), the locking device 7 with the blocks 10' enables the locking system to be released automatically once the rotation of the wheel has ceased.
The number 25 indicates a disc-shaped closing cover suitable for closing both of the seats 12', using screw clamping means 26. Alternatively, it is possible to provide separate cover elements, for closing the respective seats 12 separately from one another, in a similar manner to the configuration with the caps 13 described in the previous example.
It is also possible for each block 10, 10' to be associated with resilient return means acting on the blocks to urge them towards disengagement from the respective recess.
These return means may comprise springs whose rigidity (that is to say, the elastic constant characterizing them) is chosen to be such that the resilient force acting on the block 10, 10' is overcome by centrifugal force when a predetermined speed of rotation of the wheel is reached, such that, when this speed is reached and/or exceeded, the blocks 10, 10' are urged to engage the recess 11 of the wheel support 3.
The number 30 indicates pin-like formations provided in the flange and forming anti-rotation means. The pins 30 project frontally from the flange 1 and can engage, by frontal insertion, corresponding holes 31 provided in corresponding positions on the wheel support 3.
The pins 30 are also placed in axially symmetrical positions and at regular angular intervals along the circumferential profile of the flange 1. A preferred choice, in applications with wheel diameters of 100 mm to 400 mm, is to have two pins 30 placed at 180° to one another. In the case of a flange configuration with two blocks 10, 10', the pins 30 are conveniently located along a diametral direction perpendicular to the direction of alignment of the blocks on the flange. The anti-rotation pins enable relative rotary movements between the wheel and the flange to be prevented.
Thus the invention achieves the proposed objects while yielding the stated advantages by comparison with the known solutions.
A principal advantage is that, owing to the invention, the phase of tool changing is improved in grinding machines, particularly those having cup wheels, the wheel replacement operation being simplified and made more rapid, while ensuring suitable locking of the wheel on to the wheel-holder flange during the machining phases. The rapidity is achieved by providing a quick-release locking system. The reduction of the wheel replacement time leads to a substantial improvement in the output of the machining line, particularly in machining lines using multiple-mandrel grinding machines designed to be fitted with large numbers of wheels.

Claims

A wheel-holder flange for a cup wheel (2) of the type in which the wheel comprises a support (3) bearing the abrasive material and the support may be detachably locked on the flange so that it can be fixed in rotation with the flange about an axis of rotation (X) of the wheel, said flange comprising:
- a first device (6) for locking the wheel support (3) on the wheel-holder flange by magnetic attraction, and

- a second device (7) for locking the wheel support (3) on the flange, wherein the locking may take place by the action of the forces of a centrifugal nature generated by the rotation of the wheel,

- the second locking device (7) comprising at least a pair of retaining blocks (10) held in such a way as to be able to slide in a limited manner on the flange and able to be radially urged, by centrifugal action, to engage a recess (11) provided in the wheel support (3) so as to oppose relative movements between the flange and the wheel support, principally in the axial direction, during the rotary movement of the wheel (2),
each block (10) being shaped as a disc and being housed in a floating manner in a respective seat (12) of the flange, the seat having an opening (15) facing the recess (11) of the support (3), through which the corresponding block projects when it is urged by centrifugal action to engage the recess,
characterised in that each seat (12) housing the corresponding block (10) comprises opposite lateral walls (18) having portions (18a) with an inclined profile and converging in the direction of the opening (15) in the seat (12), so that the block (10) is returned into the seat (12), thereby disengaging the recess (11), when the wheel (2) is not in rotation and the flange is orientated into a position such as to displace the block (10), under the action of gravity, along the inclined portions (18a) of the walls (18) of the seat.
A wheel-holder flange according to Claim 1, wherein the retaining blocks (10) of the aforesaid pair are positioned on the flange in an axially symmetrical position with respect to the axis of rotation (X) of the wheel.
A wheel-holder flange according to Claim 1 or 2, wherein the wheel support (3) is shaped as a centrally pierced disc so as to have an annular profile and said recess (11) is defined by a groove running circumferentially around the hole passing centrally through the support.
A wheel-holder flange according to Claim 1, wherein each seat (12) housing the corresponding block (10) comprises a cavity formed in the flange, which may be closed, in a removable manner, by a respective closure cap (13), the corresponding block (10) continuing to be retained in a floating manner between the walls (18) of the cavity and the closure cap (13).
A wheel-holder flange according to any one of the preceding claims, wherein resilient return means are provided to act on the blocks (10) in order to urge said blocks to disengage the recess (11) when the wheel is not in rotation.
A wheel-holder flange according to Claim 5, wherein the rigidity of the resilient means is selected such that the resilient force acting on each block (10) is overcome by the force of centrifugal nature at a predetermined speed of rotation of the wheel (2), such that when this speed is reached, the blocks (10) are urged to engage the recess (11) of the wheel support.
A wheel-holder flange according to any one of the preceding claims, wherein anti-rotation means are provided in the form of a pin (30) projecting at the front of the flange, and are positioned on the flange in axially symmetrical positions and at regular angular intervals, the pin means (30) being adapted to engage corresponding coupling holes (31) provided in corresponding positions on the wheel support (3).