EP3856457B1

EP3856457B1 - Grinding unit

Info

Publication number: EP3856457B1
Application number: EP19787479.5A
Authority: EP
Inventors: Giovanni Tupini; Rosario LO PICCOLO; Roberto De Toni; Guido Roman
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-09-25
Filing date: 2019-09-23
Publication date: 2022-10-26
Anticipated expiration: 2039-09-23
Also published as: WO2020065688A1; EP3856457A1

Description

Technical Field

The present invention relates to a grinding unit.
In general, the present invention relates to machines or devices designed for the grinding of surfaces of inorganic material flat, for example, stone, ceramic, porcelain.
In particular, the present invention relates to grinding heads to work on flat surfaces provided with oscillating abrasive blocks mounted on a rotating head.

Background Art

The state of the art is represented by IT patent 1,175,191 B concerning a head comprising a certain number of grinding wheels with oscillating sectors mounted on pins fixed to a watertight rotating casing with a central shaft fixed by flange to the machine, a rotating tilted disk engaged with peripheral clamps further pins that rotate the pins integral with the oscillating sectors by means of levers to make them oscillate during the rotation of the head.
The state of the art is also represented by US patent 5,339,569 A concerning a device for treating the surface of objects by grinding, polishing and deburring, comprising a conveyor belt of the objects to be treated, a grinding unit disposed on top of a grinding body parallel to the conveyor belt, a grinding body support rotatably driven by a first motor around at least two crankshafts in a plane parallel to the conveyor belt. By means of the first motor, a transmission system allows moving the grinding body support in an oscillating movement with respect to the conveyor belt. A second motor rotates a pinion and then a chain to rotate central support. In this way, the abrasive surface disposed on the lower side of the grinding body support undergoes a combined movement, ie a rotary and oscillating movement, which extends over the entire width of the conveyor belt favouring optimal processing of the surface of the objects located on the convenyor belt.
Moreover, the state of the art is represented by DE patent 4 408 560 C2 concerning a polishing head with abrasive segments for the surface treatment of natural and artificial stone that can be guided by means of a shaft with a grinding concentric wobble ring guided in a plane tilted with respect to the plane perpendicular to the shaft of grinding, with at least one spherical joint corresponding to the number of segments in the wobble ring for guiding bolts of abrasive segments in response to a predetermined angle.
In the DE patent 4 408 560 C2 , the state of the art is represented by US patent 5,145,326 A concerning a variable capacity wobble plate compressor with a variable angle non-rotary wobble plate oscillating plate not rotating mechanism by means of an oscillating plate mechanism mounted around a drive shaft.

Summary of Invention

Technical Problem

Generally, a head such as that of IT 1,175,191 B comprises a fixed cover provided with a first internally toothed crown, a rotating casing adapted to drag a certain number of grinding wheels with radial oscillating sectors with a lever, an idle cam interacting with the lever of each grinding wheel, the idle cam equipped with a second internally toothed crown coaxial to the rotating casing, at least one eccentric idle externally toothed wheel with correction, the eccentric idle externally toothed wheel with correction adapted to mesh with the first and with the second internally toothed crown to expand the movement of the rotating casing with respect to that of the idle cam obtaining a fast rotation of the rotating casing and a slow oscillation of the wheels with radial oscillating sectors.
The solution of IT1,175,191 B allows transmitting a high power of interaction of the tool on the material to be treated, by virtue of a large number of teeth in which the internal toothed gears are gripped. However, a gear transmission with internal toothing, hypocycloidal or epicycloidal, such as that used in the head of IT 1,175,191 B , does not allow the transmission ratio to be modified and therefore does not allow to vary the amount of the oscillating contribution with respect to the progressive one of the tool, except for disassembling the head to replace at least the eccentric idler wheel.
A polishing head as that of DE 4 408 560 C2 comprises a concentric wobble ring driven in a plane inclined with respect to the plane perpendicular to the shaft of grinding according to a preset value of the amount of angular travel of abrasive segments. However, the solution of DE 4 408 560 C2 does not allow any type of variation of the angular amplitude of the abrasive segments leaving unresolved the problem of correlating the angular stoke with the size of the abrasive segments.

Solution to Problem

A cue to the solution of the problem of being able to vary the amount of the oscillating contribution with respect to the progressive one of the tool is provided by US 5,339,569 A by combining a first motor to transmit an oscillating movement of a grinding body support with a second motor to rotate a central support by imparting a combined oscillating and rotating action of tools to the surface of objects to be treated.
A cue to the solution of the problem of being able to correlate the angular excursion with the size of the abrasive segments is provided by US 5,145,326 A , combining a concentric wobble ring guided in an inclined plane with respect to the plane perpendicular to the milling shaft contributing to supply a predetermined value of the magnitude of the angular excursion of the abrasive segments to a system for adjusting EP-A1-0 687 527 and DE-C-800 112 disclose grinding units whereas EP-A1-0 687 527 forms the basis for the preamble of claim 1. the angular excursion controlled by an actuator.
The object of the present invention is that of not using a permanent cover provided with a first internally toothed crown, but a rotating casing adapted to drag a certain number of grinding wheels with radial oscillating sectors with a lever, a non-idle and not-provided cam of a second crown wheel internally coaxial to the rotating casing, but a rotary cam through the motion of a central shaft coaxial to the rotating casing, without externally eccentric toothed wheel with correction, a first motor connected to the rotating casing and a second motor connected to the rotating cam to allow diversification of the movement of the rotating casing with respect to that of the rotating cam obtaining a fast rotation of the rotating casing and a slow oscillation of the wheels with radial oscillating sectors, a control system able to diversify the contribution of the two movements in real time.
A further object is that of being able to adjust the law of motion of the tool which is a function of the speed difference of the rotating cam and of the rotating casing, in other words, with the same speed of the rotating cam and that of the rotating casing the tool resulting free of oscillating motion.
A further object is to simplify the mechanical construction of the head eliminating the transmission of wheels and toothed crowns.
A further object is practically that of starting conceptually from a head such as that of IT 1,175,191 B to create a sort of eccentric idle external toothed wheel with correction, in which this correction is made variable through a controlled actuator.
A further purpose is that of being able to adjust the angular excursion of the tool as a function of geometric parameters such as the dimensions of the tool and physicalchemical materials to increase the efficiency of the machining.
A further object is practically that of starting conceptually from a head such as that of DE 4 408 560 C2 to create a sort of concentric wobble ring guided in an inclined plane said ring able to modify the trim of this inclined plane by means of a controller.
The aforementioned and other objects and advantages of the invention, as they will emerge from the following description, are achieved with a grinding unit, as described in the main claim. Preferred embodiments and non-trivial variants of the present invention form the object of the dependent claims. It is understood that all the deriving claims form an integral part of the present description. It will be immediately obvious that innumerable variations and modifications (for example relating to shape, dimensions, arrangements and parts with equivalent functionality) can be made to the description within the scope of protection of the invention as it appears from the appended claims.

Advantageous Effects of Invention

A first advantage of the invention as appears from the enclosed claims is that of being able to determine a series of dragging speed to oscillate the abrasive blocks as a function of the nature of the material to be worked, offering a method of distribution of the pivoting motion with respect to continuous motion of the tool.
A second advantage is that of being able to provide a grinding unit without gear contributing to lower considerably mechanical friction increasing the overall efficiency of the process.
Another advantage regards the possibility of reducing the costs of manufacture of a grinding unit with a mechatronic architecture.

Brief Description of Drawings

The present invention will be better described by some preferred embodiments thereof, given as a non-limiting example, with reference to the enclosed drawings, in which:

FIG. 1 is a functional diagram of a first example of a grinding unit not being part of the present invention;
FIG. 2 is a functional diagram of a second example of a grinding unit not being part of the present invention;
FIG. 3 is a functional diagram of an embodiment of the grinding unit according to the present invention;
FIG. 4 shows a front view of the first example not being part of the invention;
FIG. 5 shows a section view according to the line V-V of view of the previous figure;
FIG. 6 shows a perspective view of example not being part of the present invention; and
FIG. 7 shows an important component belonging to the FIG. 5.

Description of Embodiments

With reference to FIGS. 1, 2, 3, a grinding unit 100 comprises a rotating head 10 provided with abrasive oscillating blocks B mounted on tool supports 11 connected to a rotating casing 12, for working on flat surfaces, rotating cam means 131, 132, 133, connected to the abrasive oscillating blocks B through arms 14 integral with the tool supports 11.
Advantageously, a first motor 20 is adapted to move the rotating casing 12 by imparting a first dragging speed ωt1. A second motor 30 is adapted to move the rotating cam means 131, 132, 133 by imparting a second dragging speed ωt2. A controller of the first motor 20 and of the second motor 30 is adapted to allow to regulate the distribution of the value of the first dragging speed ωt1 and that of the second dragging speed ωt2 to allow to obtain the desired law of motion ωB of the abrasive oscillating blocks B.
In particular, the desired law of motion ωB depends on a function F of the value of the difference between the first and second dragging speeds ωt1- ωt2 specified as ωB = ωt1 + F (ωt1- ωt2).
In addition to this desired law of motion explicated as ωB, for the values of the first dragging speed ωt1 equal to those of the second dragging speed ωt2, the oscillation of the abrasive oscillating blocks B is null.
According to a first example, a second example and an embodiment of the grinding unit 100, with reference to FIGS 4 to 7 as regards the first example, the rotating casing 12 is integral with a central flange 15, the central flange 15 being connected to a central flanged hollow shaft 21 moved by the first motor 20.
According to the first example and the second example of the grinding unit 100, with reference to FIGS. 5, 7 as regards the first example, the rotating cam means 131, 132 are integral with a central pin 16, the central pin 16 being connected to a central shaft 31 moved by the second motor 30.
In particular, according to the first example of the grinding unit 100, the rotating cam means 131 consists of an axial cam with an almost sinusoidal profile interacting with the arms 14.
According to the second example of the grinding unit 100, with reference to FIG. 2, the rotating cam means 132 consists of an inclined plate interacting with said arms 14.
According to the embodiment of the grinding unit 100, with reference to FIG. 3, the rotating cam means 133) are connected to a central pin 16 through an angular joint 17 and to a device of variation of the axial orientation 40. In particular, the device for variation of the axial orientation 40 is moved by a controlled motor 50 through a gear reducer 41 to allow the axial orientation of the rotary cam means 133 to be changed of a value determined as a function of an angular rotation β. The central pin 16 is connected to a central shaft 31 moved by the second motor 30.
The rotating cam means 133 consists of a plate with variable inclination to allow adjustment of the amplitude of the angular excursion of the abrasive oscillating blocks B, independently of the desired law of motion ωB of the abrasive oscillating blocks B.

Claims

Grinding unit (100), comprising a rotating head (10) provided with abrasive oscillating blocks (B) mounted on tool supports (11) connected to a rotating casing (12), for working on flat surfaces, rotating cam means (133), connected to the abrasive oscillating blocks (B) through arms (14) integral with the tool supports (11), and further comprising a first motor (20) adapted to move the rotating casing (12) by imparting a first dragging speed (ωt1) and a second motor (30) adapted to move the rotating cam means (133) by imparting a second dragging speed (ωt2), a controller of the first motor (20) and of the second motor (30) adapted to allow to regulate the distribution of the value of the first dragging speed (ωt1) and that of the second dragging speed (ωt2) to allow to obtain a desired law of motion (ωB) of the abrasive oscillating blocks (B), characterized in that said rotating cam means (133) are connected to a central pin (16) through an angular joint (17) and to a device of variation of the axial orientation (40), said device for variation of the axial orientation (40) moved by a controlled motor (50) through a gear reducer (41) to allow the axial orientation of said rotary cam means (133) to be changed of a value determined as a function of an angular rotation (β), said central pin (16) connected to a central shaft (31) moved by the second motor (30).
Grinding unit (100) according to the previous claim, characterized in that said desired law of motion (ωB) depends on a function (F) of the value of the differences between the first and second dragging speeds (ωt1 - ωt2), said desired law of motion specified as (ωB = ωt1 + F(ωt1 - ωt2)).
Grinding unit (100) according to the previous claim, characterized in that for the values of the first dragging speed (ωt1) equal to those of the second dragging speed (ωt2), the oscillation of the abrasive oscillating blocks (B) is null.
Grinding unit (100) according to one of the previous claims, characterized in that said rotating casing (12) is integral with a central flange (15), said central flange (15) connected to a central flanged hollow shaft (21) moved by the first motor (20).
Grinding unit (100) according to claim 1, characterized in that said rotating cam means (133) consist of a plate with variable inclination to allow adjustment of the amplitude of the angular excursion of the abrasive oscillating blocks (B), independently of the desired law of motion (ωB) of the abrasive oscillating blocks (B).