WO2020178675A1

WO2020178675A1 - Machine for grinding sheet-like elements and relative method

Info

Publication number: WO2020178675A1
Application number: PCT/IB2020/051672
Authority: WO
Inventors: Giuliano SIGNORINI
Original assignee: Soltek S.R.L.
Priority date: 2019-03-01
Filing date: 2020-02-27
Publication date: 2020-09-10
Also published as: IT201900003001A1

Abstract

Described is a machine (100) for grinding sheet-like elements (10), comprising a main frame (101), a plurality of positioning systems (1) of said respective tools (2), each of said positioning systems (1) comprising a portion (6) for the rigid connection of said positioning system (1) to said main frame (101) of said machine (100), said rigid connection being configured for placing said positioning system (1) substantially perpendicular to said feed direction (A) of said sheet-like elements (10) on said machine (100), at least one movement sensor (3) configured for measuring an instantaneous distance (D) with respect to said tool (2).

Description

DESCRIPTION

MACHINE FOR GRINDING SHEET-LIKE ELEMENTS AND RELATIVE METHOD

Technical field

This invention relates to the field of machining slabs, for example tiles, made from ceramic material, stone, glass or the like.

In particular, the invention relates to a machine for grinding sheet-like elements.

The invention also relates to an operating method of a machine for grinding sheet-like elements.

Background art

It is known that the slabs produced industrially and which can be used as tiles for flooring and other types of covering require a grinding operation. The main aim of this grinding operation is to guarantee the orientation and dimensions of the sides of the slabs in such a way as to allow the placing alongside, during installation, of the various slabs without clearance between the slabs.

In the field of the industrial production of slabs this operation is carried out by means of grinding machines which are able to quickly process large quantities of products which feed in succession on a horizontal movement plane.

The sides of the products to be processed protrude laterally and come into contact with a succession of grinding wheels, which remove the excess material and move the outer perimeter flush and, if necessary, one or more inclined grinding wheels, for performance of the chamfering operation.

In commonly used machines, the grinding of the slabs is performed in two steps. In a first step, they are ground by specific grinding wheels facing each other facing the movement plane on two opposite sides of each slab.

The slabs are then rotated by 90° in such a way that the two remaining sides can be ground by further grinding wheels facing and alongside the movement plane.

The grinding operation generally starts with an overall calibration, determined on the basis of the dimensions of the initial slab and those desired as the final result.

The calibration comprises the positioning by the user of each single grinding wheel included in the two benches of the machine, left and right, so as to correctly set the so-called“working cone”, that is to say, the grinding lines of the two benches of grinding wheels inside of which the slab being machined slides.

For this purpose, the grinding wheels are movable towards and away from the centre of the machine so as to define the correct positioning with respect to the slab being machined.

After the initial calibration operation, it is necessary, during the machining, to keep under control the wear of each single grinding wheel so as to correctly perform the overall grinding.

There are prior art machines for grinding sheet-like elements comprising systems for manual positioning of each single grinding wheel.

In this circumstance, the user must correctly position each single grinding wheel, at the start of machining a new batch of slabs, according to the working design data of the single batch (working cone); this operation is the above-mentioned calibration.

A prior art machine is described in patent document CN106392815.

Even though they require a long time to carry out the initial calibration, these prior art machines, once this is performed, allow the grinding in a reliable manner at least until the moment in which the wear of one or more grinding wheels is clearly evident. In fact, the control of the state of wear of the grinding wheels cannot be verified automatically and is performed by a visual inspection of the finished slab.

Therefore, unfortunately, this type of machine does not allow a continuous control of the correct positioning of the individual grinding wheels, that is to say, it does not allow the“working cone” to be kept contestant over time, which results in the production of slabs which are inconsistent with the work design of the batch initially set up.

Another type of machine for grinding sheet-like elements is described in patent document EP2542381 .

The above-mentioned machine comprises a system for automatically performing the initial calibration.

In particular, the above-mentioned machine comprises a light beam (positioned operatively between a respective emitter and a respective receiver) for each bench of grinding wheels, positioned parallel to the feed direction of the slabs being machined which acts as a contact sensor for the grinding wheels of a single bench.

In short, the light beam corresponds to a side of the working cone.

With the machine not operating (that is, without the passage of any slab being machined) the above-mentioned light beam emitter is switched on, the individual grinding wheels are moved forwards and backwards until each is positioned flush with the light beam, that is, along the above-mentioned side of the working cone.

Upon completion of the calibration step, the machine can be actuated and the grinding of the slabs can start.

Even though this type of prior art machine allows the initial calibration operations to be considerably reduced, it is not able to optimise the machining with regard to the control and maintenance during the grinding process of the working cone, in particular with an increase in wear of the single grinding wheels of the two work benches. It should be noted that the lack of continuous control of the wear of each single grinding wheel also results in a further important drawback.

If, for example, any grinding wheel of a single bench wears until no longer intercepting the passing slab, the remaining grinding wheels of the bench will have to make up for the work not carried out by the worn grinding wheel and they will wear even more than an optimum working condition.

Aim of the invention

In this context, the technical purpose which forms the basis of the invention is to provide a machine for grinding sheet-like elements and a relative method which overcome at least some of the above-mentioned drawbacks of the prior art.

In particular, the aim of the invention is to provide a machine for grinding sheet-like elements and a relative method as an alternative to and more efficient than the prior art, with regard to the instantaneous positioning of each single tool with respect to the sheet-like element being machined. Another aim is to provide a machine for grinding sheet-like elements and a relative method which is able to command and control each tool independently from the others in order to optimise the use and minimise the wear.

Another aim of the invention is to provide a machine for grinding sheet-like elements and a relative method which is able to vary the mutual positioning of the tools with respect to the sheet-like elements being machined, continuously and without having to interrupt the operation of the machine for the grinding itself.

The technical purpose indicated and the aims specified are substantially achieved by a machine for grinding sheet-like elements and a relative method comprising the technical features described in one or more of the accompanying claims.

The dependent claims correspond to possible embodiments of the invention. Further features and advantages of the invention are more apparent in the non-limiting description which follows of a preferred embodiment of a machine for grinding sheet-like elements and a relative method.

Brief description of the drawings

The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without restricting the scope of the invention and in which:

- Figure 1 shows a detail of a system for positioning a tool for grinding sheet like elements of a machine according to the invention,

- Figure 1 A shows an enlargement of a detail of the system for positioning a tool of a machine for grinding sheet-like elements shown in Figure 1 ,

- Figure 2 shows a schematic side view of a series of three systems for positioning a tool for grinding sheet-like elements,

- Figure 3 shows a perspective view of Figure 2,

- Figure 4 shows a top view of a machine for grinding sheet-like elements equipped with a plurality of systems for positioning a tool for grinding sheet like elements according to the invention and

- Figure 5 shows a perspective view of a machine for grinding sheet-like elements according to the invention equipped with a plurality of systems for positioning a tool for grinding sheet-like elements.

Detailed description of preferred embodiments of the invention

A machine 100 for grinding sheet-like elements 10, which is the object of the invention, is illustrated in the accompanying drawings and denoted generically with reference numeral 100.

The machine 100 for grinding sheet-like elements 10 comprises at least one system 1 for positioning a tool 2.

The description below will refer to the system 1 for positioning a tool 2 for grinding sheet-like elements 10 as the“positioning system 1”.

The machine 100 comprises a main frame 101 on which is installed at least one conveyor 102, for example of the double superposed belt type, configured for moving a plurality of sheet-like elements 10 along a feed direction A from a first infeed station 1 10 to an outfeed station 120.

The machine 100 also comprises a plurality of electric motors 5 connected to respective tools 2, and fixed stably to the main frame 101 .

The electric motors 5, and therefore the tools 2 connected to them, face the conveyor 102 (that is, the sheet-like elements 10) between the infeed station 1 10 and the outfeed station 120.

The electric motors 5 are configured to rotate the tools 2 to perform the operation for grinding the sheet-like elements 10 positioned on the conveyor 102 and moving along the feed direction A.

The machine 100 also comprises a plurality of systems 1 for positioning respective tools 2.

Each system 1 for positioning a tool 2 for grinding sheet-like elements 10, comprises, in its basic embodiment, a portion 6 for rigid connection of the positioning system 1 to the machine 100 for grinding sheet-like elements 10 according to the invention, the above-mentioned rigid connection being configured for placing the entire positioning system 1 substantially perpendiculars to a direction A for feeding the sheet-like elements 10 being machined on the machine 100.

In particular, it is important that the positioning system 1 is fixed in a stable fashion, advantageously to a main frame 101 of the machine 100, to prevent it undergoing undesired movements during machining.

Threaded connections of known type can be used, for example, for this fixing.

The positioning system 1 also comprises a spindle 4 for supporting the tool 2 movable axially along a direction F.

Each movement of the spindle 4 therefore corresponds to a similar movement of the tool 2 supported by it.

The tool 2 must be fixed to the spindle 4 in such a way that it is possible to replace it easily, for example by means of threaded connections of known type.

The spindle 4 is in turn connected and controlled by a respective actuator 7, for example linear, which is configured to move it axially along the direction“F”.

In order to rotate the tool 2 and therefore carry out the grinding operation, the spindle 4 is also connected to a respective electric motor 5.

The positioning system 1 also comprises at least one movement sensor 3 configured for measuring an instantaneous distance D, that is, continuously over time, with respect to the tool 2.

The movement sensor 3 is positioned in a fixed manner with respect to the spindle 4, in such a way that if the spindle 4 vibrates or undergoes micro movements, these would correspond to identical vibrations or micro movements of the movement sensor 3, thereby not affecting or varying the measurement of the distance D.

Advantageously, the movement sensor 3 is fixed on the same portion of machine 100, such as, for example, the main frame 1 01 , where the electric motor 5, spindle 4 and tool 2 are fixed.

Advantageously, the distance D is measured along a direction parallel to the direction F of axial movement of the spindle 4 and substantially perpendicular to the direction A for feeding the sheet-like elements 10 on the machine 100.

This configuration is that indicated in Figures 1 , 2 and 3.

Alternatively, the distance D can be measured along a direction perpendicular both to the direction F of axial movement of the spindle 4 and substantially perpendicular also to the direction A for feeding the sheet-like elements 10 on the machine 100.

According to this configuration the movement sensor 3 is fixed above or below the tool 2.

Preferably, the positioning system 1 according to the invention also comprises a command and control unit 20 configured for comparing the value of the distance D measured instantaneously by the movement sensor 3 with a value D’ of the reference distance D stored in the command and control unit 20. The reference value D’ is the value pre-set in the machine 100 by a user and identifies a particular grinding operation for a batch of sheet-like elements 10 being machined.

In short, the combination of all the single values D’ of each single tool 2 included in a machine 100 defines the two sides of the working cone of the machine 100.

The working cone results in the actual final dimension of the sheet-like element 10 upon completion of the grinding.

Advantageously, the command and control unit 20 is operatively connected to the actuator 7 in such a way as to move the spindle 4 along the direction F in such a way that the distance D measured instantaneously by the movement sensor 3 always corresponds to the reference value D’ during the grinding operation.

The movement sensor 3 can comprise, for example, an optical sensor, based for example on laser, micrometric or millimetric technology, sensors based on ultrasound or sonar technologies or any sensor which is able to read the distance between itself and an object with a minimum precision in the order of 1 mm.

The movement sensor 3 is advantageously positioned at a distance of between 10 mm and 120 mm with respect to the tool 2.

Advantageously, according to a preferred embodiment the distance D is measured between the movement sensor 3 and the lower half 2a of the tool 2; basically, the movement sensor 3 is positioned beneath the working plane of the sheet-like elements 10 where the quantity of dust and foreign bodies produced during the grinding operation is less.

By way of example, and with reference to Figures 4 and 5, a machine 100 for grinding sheet-like elements 10 can comprise ten positioning systems 1 (connected, therefore, to ten respective tools 2) for each bench, the right and the left with respect to the feed direction A.

The positioning systems 1 are connected in a rigid and stable fashion to the main frame 101 . Operatively connected to the plurality of positioning systems 1 there is a command and control unit 20 for varying the position of each individual tool 2 as a function of said distance D measured instantaneously by the movement sensor 3 relative to a reference value D’ stored in the command and control unit 20).

The invention also relates to method for grinding sheet-like elements 10. The above-mentioned method comprises a first step of preparing a plurality of positioning systems 1 on a machine 100, and, subsequently, measuring through the movement sensor 3 included in the positioning system 1 , an instantaneous distance D between the movement sensor 3 and a tool 2. The measurement of the distance D is performed continuously during the grinding of the sheet-like elements 10.

Advantageously, in this way it is also possible to compare the distance D with a reference value D’ stored in the command and control unit 20 in order to move the spindle 4 supporting the respective tool 2 by means of the respective actuator 7 along the direction F in response to this comparison. In particular, the movement controlled by the command and control unit 20 is performed in such a way that the distance D measured instantaneously by the movement sensor 3 always corresponds to the reference value D’ stored in the command and control unit 20 during the entire grinding operation.

The invention achieves the present aims, overcoming the disadvantages of the prior art and bringing important advantages.

A first important advantage consists in the fact that a machine 100 for grinding sheet-like elements according to the invention allows the continuous command and control of each machining tool 2.

This very important both during the first calibration step, that is, when the positioning system positions all the tools 2 so that the value of the distance D is equal to the value D’ of the batch being produced, and during the actual grinding step to instantaneously compensate for the individual wear of each single tool. A further important advantage resulting from the instantaneous command and control of the positioning of each single tool 2 is the fact that guaranteeing a correct positioning of all the tools 2 with respect to the pre set working cone guarantees the maximising of the efficiency of each single tool without work over-loads or under-loads of any tool.

In fact, the solution described defines an effective alternative to the prior art solutions and it is simpler and more efficient to perform the mutual positioning between each single tool and the sheet-like element being machined.

Claims

1 . A machine (100) for grinding sheet-like elements (10), comprising:

- a main frame (101 );

- a conveyor (102) configured for moving a plurality of sheet-like elements (10) along a feed direction (A) from an infeed station (1 10) to an outfeed station (120);

- a plurality of electric motors (5) connected to respective tools (2), said electric motors (5) being connected to said main frame (101 ) and facing said conveyor (102) between said infeed station (1 10) and said outfeed station (120) and configured for rotating said tools (2) for grinding said sheet-like elements (10) arranged on the conveyor (102);

- a plurality of systems (1 ) for positioning said respective tools (2) each of said positioning systems (1 ) comprising:

- a portion (6) for rigid connection of said positioning system (1 ) to said main frame (101 ) of said machine (100), said rigid connection being configured for placing said positioning system (1 ) substantially perpendicular to said direction (A) for feeding said sheet-like elements (10) on said machine (100),

- a spindle (4) for supporting said tool (2) said spindle (4) being movable axially along a direction (F),

- an actuator (7) for moving axially said spindle (4) along said direction (F),

- at least one movement sensor (3) configured for measuring an instantaneous distance (D) with respect to said tool (2), said movement sensor (3) being positioned in a fixed manner relative to said spindle (4), wherein said distance (D) is measured along a direction parallel to said direction (F) of axial movement of said spindle (4) and substantially perpendicular to said direction (A) for feeding said sheet-like elements (10) on said machine (100), said distance (D) being measured between said movement sensor (3) and the lower half (2a) of said tool (2), said machine (100) also comprising a command and control unit (20) operatively connected to said plurality of positioning systems (1 ) for varying the position of each single tool (2) as a function of said distance (D) measure instantaneously by said movement sensor (3) with respect to a reference value (D’) stored in said command and control unit (20).

2. The machine (100) according to claim 1 , wherein said command and control unit (20) is operatively connected to said actuator (7) in such a way as to move said spindle (4) along the direction (F) in such a way that said distance (D) measured instantaneously by said movement sensor (3) corresponds to said reference value (D’) during the grinding operation.

3. The machine (100) according to any one of the preceding claims, wherein said movement sensor (3) is positioned at a distance of between 10 mm and 120 mm with respect to said tool (2).

4. The machine (100) according to any one of the preceding claims, wherein said movement sensor (3) comprises an optical sensor, based on laser technology, with micrometric or millimetric precision.

5. The machine (100) according to any one of claims 1 to 3, wherein said movement sensor (3) comprises a sensor based on ultrasound technology.

6. The machine (100) according to any one of claims 1 to 3, wherein said movement sensor (3) comprises a sensor based on sonar technology.

7. The machine 100 according to any one of the preceding claims, wherein said movement sensor (3) is positioned beneath said conveyor (102).

8. A method for grinding sheet-like elements (10) comprising the following steps: - preparing a machine (100) according to claims 1 to 7,

- measuring through said movement sensor (3) said instantaneous distance (D) between said movement sensor (3) and a tool (2), characterised in that said measurement of said distance (D) is performed continuously during the grinding of said sheet-like elements (10).

9. The method according to claim 8, also comprising a step of comparing said distance (D) with a reference value (D’) stored in a command and control unit (20) of said positioning system (1 ), and a step of moving a spindle (4) for supporting a tool (2) by means of a respective actuator (7) operatively connected to said spindle (4) along the direction (F) in such a way that the distance (D) measured instantaneously by said movement sensor (3) corresponds instantaneously to said reference value (D’) during the grinding operation.