Rectilinear grinding machine for sheet-like elements and corresponding grinding method

Abstract

Rectilinear grinding machine (10) comprising a plurality of grinding heads (22) defining a grinding plane (P), the machine (10) being configured to give a certain geometry to a sheet-like element (100) having at least one first ground side (I l la) and at least one second rough side (111b).

Description

[0001] “RECTILINEAR GRINDING MACHINE FOR SHEET-LIKE ELEMENTS AND CORRESPONDING GRINDING METHOD”

[0002] FIELD OF THE INVENTION The present invention concerns an automated machine for the rectilinear grinding of sheet-like elements, in particular glass sheets with rectilinear sides. These sheets find particular application in furnishing elements or accessories such as tables, shelves, display cases or similar objects.

[0003] BACKGROUND OF THE INVENTION Rectilinear grinding machines are known, used to square a glass sheet with rectilinear sides, or give it the desired angles, and bring it to its overall size, the glass sheet still having irregular edges due to previous cutting operations, and a reciprocal inclination between the sides that has not yet been perfected.

[0004] Such a machine comprises a loading station in which there is a first conveyor guide defining a loading plane for at least one rough sheet of glass to be worked.

[0005] Downstream of the loading station there is a grinding station in which a plurality of grinding wheels defines a grinding plane adjacent to the loading plane. Normally, the loading plane is at least adjustable in height to define, with respect to the grinding plane, the passing depth with which the grinding wheels will remove the excess material from the glass sheet that is fed against them.

[0006] As disclosed in document EP2616215B1, in order to obtain a correct squaring of the glass sheet, some known machines are equipped, in the loading station, with fixed sensors that discern the vertical sides of the sheet during its passage, identifying, by means of trigonometric calculations, the length of the side to be worked that is disposed on the loading plane and the angle subtended between this latter side and the vertical side already worked. Normally, in fact, a first side is worked without acquiring any information, simply by entering a predetermined value for the passing depth, the sheet is then rotated to dispose the worked side in view of sensors, so as to use it as a reference to work the next side. These known machines also comprise positioning means that allow the loading plane to be oriented with respect to the grinding plane as a function of the measurements acquired by the sensors, in order to obtain the correct squaring and size of the sides.

[0007] A drawback of these machines is that the acquisition of the measurements, angular and dimensional, occurs while the sheet is moving, so it is inherently inaccurate.

[0008] Another drawback is that, provided that the squaring of the glass sheet is substantially successful, the measurement of the length of the sides is not precise because it is acquired by considering at least one reference side that is still rough. Measuring a sheet of glass, even of considerable sizes, having a rough side as a reference leaves room for errors. It is known, in fact, that a cut, especially on glass with a medium or large thickness, is not linear and therefore cannot be a certain reference to obtain a desired final size of the sheet downstream of the grinding working.

[0009] Another drawback of these machines is that the reference for any measurements is always a vertical side of the sheet, so if there is an error of perpendicularity between sensors and loading plane, which acts as a reference, the error propagates and adds up, determining a cumulative angular error between the subsequent sides of the sheet, preventing the desired final shape from being achieved.

[0010] Furthermore, as described always in EP2616215B1, while the glass sheet proceeds from the loading station toward the grinding station, the loading plane has to be moved in a vertical direction in a manner that is interpolated with the feeding movement of the sheet. This is to keep the sheet in the correct working position. This interpolation of axes can introduce positioning errors that affect the quality of the finished product and, moreover, considering that the sheet rests on the loading plane along one of its edges that is still rough, and therefore such as to present irregularities, in the feeding movement toward the working zone, the glass sheet varies its resting points with the translation means and it is therefore subjected to rotational stresses which can lead to poor precision in the translational movement toward the grinding station.

[0011] There is therefore the need to perfect a rectilinear grinding machine for sheetlike elements and a corresponding grinding method that can overcome at least one of the disadvantages of the state of the art. To do this, it is necessary to solve the technical problem of acquiring an angular and dimensional measurement of the sides that is as accurate as possible, in order to obtain a finished glass sheet of shape and sizes with the desired working specifications. One purpose of the present invention is to provide a machine and perfect a method for the rectilinear grinding of sheet-like elements, in particular polygonal glass sheets, in order to obtain the desired geometry of the angles, which can be squared or intentionally not squared depending on the working specifications. Another purpose of the present invention is to provide a machine and perfect a method for the rectilinear grinding of sheet-like elements, in particular polygonal glass sheets, which is able to also guarantee correct final sizes based on the working specifications.

[0012] Another purpose of the present invention is to eliminate the interpolation between the movement of the loading plane in the vertical direction and the feed of the sheet during working.

[0013] The aim is also to prevent the translation of the glass sheet during working from being performed with the glass sheet resting on a rough and irregular edge.

[0014] Another purpose of the present invention is to provide a rectilinear grinding machine for sheet-like elements with a simple construction.

[0015] The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

[0016] SUMMARY OF THE INVENTION The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

[0017] In accordance with the above purposes and to resolve the technical problem described above in a new and original way, also achieving considerable advantages compared to the state of the prior art, a rectilinear grinding machine according to the present invention comprises a plurality of grinding heads defining a grinding plane, and is configured to give a certain geometry to a sheet-like element having at least one first reference side, in this specific case already worked, and at least one second side to be worked, that is, still rough. The grinding machine comprises, upstream of the grinding plane:

[0018] - a first transfer device configured to acquire the sheet-like element,

[0019] - a second transfer device configured to transfer the sheet-like element in a direction of transfer toward a working station, with the second side facing toward the grinding plane,

[0020] - detection means configured to detect at least one distance between at least one point lying on the at least one first side and a reference axis or the grinding plane, - positioning means configured to position the sheet-like element with respect to the grinding plane, orienting it angularly by a certain angle of orientation and translating it with respect to the grinding plane by a certain working height, as a function of the at least one distance and the certain geometry,

[0021] - and a control unit operationally connected at least to the detection means and to the positioning means, and in which at least data relating to the certain geometry are stored or entered.

[0022] In accordance with one aspect of the present invention, the detection means comprise one or more measuring elements able to be commanded by the control unit to detect the distance of at least two distinct points of the at least one first side with respect to the reference axis or the grinding plane.

[0023] Furthermore, according to the present invention, the second transfer device is advantageously distinct from the first transfer device.

[0024] The second transfer device is configured to laterally sustain the sheet- like element and guarantee its transfer at least from a detection zone, where the detection means are present, to the working station. The transfer occurs in the direction of transfer that is parallel to the grinding plane.

[0025] In accordance with another aspect of the present invention, some of the measuring elements can be positioned parallel to a first and / or a second positioning axis which are coplanar and orthogonal with respect to each other. In accordance with another aspect of the present invention, at least one of the measuring elements can be advantageously disposed in a fixed vertical position and can only be positioned parallel to the horizontal first positioning axis. Moreover, at least another of the measuring elements can be advantageously disposed in a fixed horizontal position and can only be positioned parallel to the vertical second positioning axis.

[0026] In accordance with another aspect of the present invention, the measuring elements can be associated with respective sliding members which can be positioned along respective linear guides which extend parallel to one or the other of the first and second positioning axis.

[0027] According to one embodiment of the present invention, a first measuring element associated with a first sliding member can be positioned along a first guide parallel to the horizontal first positioning axis. Moreover, a second measuring element associated with a second sliding member can be positioned along a second guide parallel to the horizontal first positioning axis, wherein the second guide is associated sliding with at least one positioning member parallel to the vertical second positioning axis.

[0028] According to one embodiment of the present invention, a third measuring element associated with a third sliding member can be positioned along a third guide parallel to the vertical second positioning axis. Moreover, a fourth measuring element associated with a fourth sliding member can be positioned along a fourth guide parallel to the vertical second positioning axis, wherein the fourth guide is associated sliding with at least another positioning member parallel to the horizontal first positioning axis.

[0029] In accordance with another aspect of the present invention, the third guide and the fourth guide can be of the telescopic type.

[0030] In accordance with a variant of the present invention, the measuring elements can be disposed in a fixed position along the first and / or the second positioning axis.

[0031] In accordance with another variant, the detection means can comprise a single measuring element mounted at a terminal end of a rod which is pivoted, at an opposing end, to a fixed part of the grinding machine, wherein to a rotation of the rod there corresponds a different positioning of the measuring element with respect to the at least one first side in order to detect the distance of the two distinct points.

[0032] In accordance with another aspect of the present invention, the detection means comprise two distinct measuring elements rotatably attached to a fixed part of the grinding machine, wherein to a rotation of each of the measuring elements around an orientation axis thereof, there corresponds a different positioning thereof with respect to the at least one first side in order to detect the distance of the two distinct points.

[0033] In accordance with another aspect of the present invention, the measuring elements are chosen between a contact or a remote sensor or transducer. In accordance with another aspect of the present invention, the first transfer device defines a substantially horizontal transfer plane for the sheet, with which the positioning means are associated.

[0034] In accordance with another aspect of the present invention, the first transfer device can be a motorized loading plane. According to a variant, the first transfer device can be a fixed resting plane for the sheet-like element.

[0035] In accordance with another aspect of the present invention, the second transfer device is configured to transfer the sheet in a direction substantially parallel to the grinding plane P, at least from the detection zone to the working station, holding it and sustaining it through at least one of its facing lateral surfaces with a larger extension.

[0036] In accordance with the present invention, a method is provided for the rectilinear grinding of a sheet-like element having at least one first reference side, already ground, and at least one second side, still rough, comprising: a loading step, in which the sheet-like element is acquired by a first transfer device, and optionally transferred in a direction of transfer, with the second side facing toward a grinding plane, a detection step, in which detection means detect at least one distance between at least one point lying on the at least one first side and a reference axis or the grinding plane, and send a corresponding detection signal to a control unit, a processing step, in which the control unit, as a function of the detection signal and of a certain geometry to be given to the sheet-like element, processes the angular inclination between the first side and the reference axis or the distance with respect to the grinding plane P, and sends a corresponding command signal to positioning means, a positioning step, in which the positioning means, on the basis of the command signal, position the sheet-like element with respect to the grinding plane, orienting it angularly by a certain angle of orientation and translating it by a certain working height, a feeding and subsequent working step, in which the sheet-like element is fed toward a plurality of grinding heads defining the grinding plane.

[0037] In accordance with one aspect of the present invention, in the detection step one or more measuring elements are commanded by the control unit to detect the distance of at least two distinct points of the at least one first side with respect to the reference axis or the grinding plane.

[0038] Moreover, in the feeding step the sheet-like element is moved parallel to the grinding plane by means of a second transfer device, distinct from the first transfer device, and configured to laterally sustain the sheet-like element and guarantee its transfer in a direction of transfer that is parallel to the grinding plane.

[0039] In accordance with one aspect of the present invention, during the detection step the sheet-like element is stationary.

[0040] In accordance with one aspect of the present invention, during the positioning step the positioning means act on the first transfer device which supports the sheetlike element at the lower part on a transfer plane.

[0041] In accordance with one aspect of the present invention, after the positioning step a second transfer device takes delivery of the sheet- like element and sustains it through at least one of its lateral surfaces, and feeds it linearly toward a working station in which the plurality of grinding heads is disposed.

[0042] In accordance with one aspect of the present invention, after the second transfer device has taken delivery of the sheet-like element, the first transfer device and / or the positioning means are lowered in order to be released from the sheet-like element while the latter is fed toward the working station in a direction substantially parallel to the grinding plane.

[0043] In accordance with one aspect of the present invention, the sheet- like element can optionally be loaded in a zone distinct from the measuring zone, and the transfer of the sheet-like element into the measuring zone occurs by means of a suitable movement device integral with the transfer device or coinciding therewith. DESCRIPTION OF THE DRAWINGS

[0044] These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of an embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

[0045] - fig. 1 is a lateral view of a rectilinear grinding machine for sheet-like elements according to the present invention;

[0046] - figs. 2 and 3 show a schematic configuration of the detection means;

[0047] - figs. 4-7 show possible variants of the configuration of the detection means;

[0048] - figs. 8A-8D show a possible operating sequence for working a sheet-like element with a rectangular shape;

[0049] - figs. 9A-9C show a possible operating sequence for working a sheet-like element with a triangular shape;

[0050] - figs. 10A-10D show a possible operating sequence for working a sheet-like element with a parallelogram shape;

[0051] - figs. 11 A- HE show a possible operating sequence for working a sheet-like element with a pentagonal shape.

[0052] We must clarify that the phraseology and terminology used in the present description, as well as the figures in the attached drawings also in relation as to how described, have the sole function of better illustrating and explaining the present invention, their purpose being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

[0053] To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications.

[0054] DESCRIPTION OF AN EMBODIMENT OF THE PRESENT INVENTION

[0055] With reference to fig. 1, a grinding machine 10 according to the present invention is suitable to carry out the rectilinear grinding of a sheet-like element 100 which can be, for example, a sheet of glass, to which reference will be made for simplicity throughout the description.

[0056] The sheet 100 can essentially have a polygonal shape, that is, with a certain number of sides 111, for example three or more sides 111, forming its perimeter edge, and two opposing flat lateral surfaces 112, 113. Prior to working the sides 111 are still rough, rough side or sides hereafter, that is, they have a certain quantity of excess material that is subsequently removed, and are reciprocally angled in a substantially unknown, or at least not precisely determined, manner.

[0057] The grinding machine 10 comprises, in a known manner, a bearing structure 11 formed by a base 12 and an essentially vertical support wall 1 , or rather slightly inclined by a few degrees, for example by about 6°, with respect to a general vertical reference plane, on which the sheet 100 can possibly rest with one of the lateral surfaces 112, 113.

[0058] The support wall 13 can be provided with a series of lines of idle rollers 14, or other similar rolling elements, configured to promote the feed of the sheet 100 during certain working steps.

[0059] The grinding machine 10 comprises, in sequence, in a direction of transfer F of the sheet 100, which in the example of fig. 1 is from right to left, a loading station 15, a working station 16 and an unloading station 17.

[0060] The working station 16 comprises a plurality of grinding heads 22 aligned in the direction of transfer F and defining a grinding zone and a grinding plane P. The grinding heads 22 are configured to give the sheet 100 a certain geometry by removing a precise quantity of material from each rough side 111 at a time. The grinding plane P is essentially parallel to the direction of transfer F of the sheet 100.

[0061] By way of example only, the grinding heads 22 are able, in groups and in the order in which they are met by the sheet 100, to perform roughing, semi-finishing, finishing and polishing work on each side 111 of the sheet 100, possibly in a single pass.

[0062] According to some example embodiments, the grinding heads 22 can be in a number comprised between about 6 and about 15.

[0063] The grinding heads 22 can have an axis of rotation orthogonal with respect to the grinding plane P or be inclined with respect to this plane in order to perform beveling work.

[0064] The working station 16 also comprises a feeding device 23 configured to receive the sheet 100 and feed it in the direction of transfer F while the grinding heads 22 act on a rough side 111 that is in the working position, that is, facing the grinding plane P. The loading station 15, which is disposed upstream of the working station 16, comprises transfer means 18, advantageously associated with the base 12, which are configured to transfer the sheet 100 through the loading station 15 to a detection zone with a rough, that is, still to be ground, side 111 thereof facing toward a transfer plane T. The transfer plane T can be essentially horizontal, and the direction of transfer

[0065] F is parallel to the transfer plane T. The transfer plane T is, moreover, adjacent to the grinding plane P.

[0066] The loading station 15 also comprises detection means 19 disposed in the detection zone, which is intermediate between an entrance and exit section of the loading station 15.

[0067] The detection means 19 are configured to detect at least one distance D, D’ between at least one point lying on a reference side 111, distinct from the rough side 111 which is still to be ground, and a reference axis V of the detection zone, for example perpendicular to the grinding plane P.

[0068] By the term “reference side” here and hereafter in the description we mean a side of the sheet 100 that has already undergone the grinding work.

[0069] As a function of the disposition of the detection means 19, as will be better explained below, the detection means 19 can be configured to also, or alternatively, detect at least one distance D, D’ between at least one point lying on the reference side 111 and the grinding plane P, see for example fig. 2.

[0070] The distances D, D’ refer to two distinct points of the reference side 111 that are being detected. For a vertical or sub- vertical reference side 111 the distances D, D’ are preferably considered with respect to the reference axis V. For a horizontal or subhorizontal reference side 111 the distances D, D’ are preferably considered with respect to the grinding plane P.

[0071] The operation of the grinding machine 10 therefore provides that a first side 111 is worked without proceeding with any detection, and this subsequently acts as a reference for the next working cycle of a second side 111, and so on. This operation is known and provides the removal of a sufficient quantity of material to guarantee the working of the affected side is performed, without leaving rough, that is, not worked, parts. In the loading station 15, the grinding machine 10 also comprises positioning means 24 configured to position the sheet 100 with respect to the grinding plane P, orienting it angularly by an angle of orientation 5 and / or translating it vertically by a working height H, as a function of the detected position of only the at least one reference side 111. In this way, it is possible to determine the correct position of the rough side 111 to be worked with respect to the grinding plane P before the sheet 100 is transferred to the working station 16.

[0072] For example, if squaring a sheet 100, the latter is oriented angularly until the reference side 111 is positioned orthogonally to the grinding plane P. The grinding machine 10 also comprises a control unit 30 operationally connected to the detection means 19 to receive one or more detection signals containing the position of the at least one reference side 111, and to the positioning means 24 to send a command signal so that the latter determine the angular orientation (angle of orientation 8) and / or the vertical translation (working height H) of the sheet 100 with respect to the grinding plane P.

[0073] The data relating to the geometry that is to be given to the sheet 100 is also stored or entered in the control unit 30.

[0074] The detection signal can comprise data relating to the distances D and D’ of the at least one reference side 111 considered and the reference axis V.

[0075] Alternatively or additionally, the detection signal can comprise data relating to the distances D and D’ of the at least one reference side 111 considered and the grinding plane P.

[0076] The detection signals are processed by the control unit 30 to determine, if necessary, the angular inclination a between the side detected and the one to be worked, and are combined with the information relating to the specific geometry to be given to the sheet 100 in order to achieve the command signal.

[0077] The command signal comprises data relating to the angle of orientation 8 and the working height H.

[0078] According to some embodiments, the transfer means 18 comprise a first transfer device 20 defining the transfer plane T of the sheet 100. The transfer plane T is a physical entity.

[0079] The first transfer device 20 can be a motorized feeding plane. For example, the first transfer device 20 can, for example, be formed by a plurality of motorized rollers 20a with horizontal axes, or slightly inclined axes because of the inclination of the sheet 100. The motorized rollers 20a allow first to load the sheet 100 and subsequently to feed it from the inlet section to the detection zone, supporting it at the lower part as long as the detection means 19 are acting. The peripheral surface of the rollers 20a defines the transfer plane T of the sheet 100.

[0080] As an alternative to the motorized rollers 20a, a conveyor belt can be provided, defining a horizontal support plane, or other similar transfer elements.

[0081] According to another embodiment, the first transfer device 20 can consist of a fixed resting plane for the sheet 100. In this case, the sheet 100 can be conveniently loaded directly in the detection zone.

[0082] The subsequent feed toward the working station 16 can conveniently occur by means of a second transfer device 21 described below.

[0083] The positioning means 24 can advantageously be associated with the first transfer device 20 or can be configured to act directly on the sheet 100.

[0084] The transfer means 18 advantageously also comprise a distinct second transfer device 21 , disposed in cooperation with the first transfer device 20 and configured to transfer the sheet 100 at least from the detection zone to the working station 16 in the direction of transfer F. In order to guarantee accuracy in the transfer of the sheet 100, the second transfer device 21 is configured to hold and support the sheet 100 through one or both of its lateral surfaces 112, 113.

[0085] The second transfer device 21 is operationally commanded to hold the sheet 100 preferably after the detection means 19 have finished performing their function and advantageously after the positioning means 24 have been driven.

[0086] Once the sheet 100 is gripped in the second transfer device 21, the first transfer device 20 is moved away from the sheet 100, for example lowered in a vertical direction, by means of suitable movement members.

[0087] Likewise, if present and configured to act directly on the sheet 100, the positioning means 24 are also moved away from the sheet after the second transfer device 21 is driven.

[0088] From what disclosed above, it can be seen that, after the second transfer device 2 1 begins operation, in addition to the transfer function it also performs the support function, since the lower side of the sheet 100 is no longer in contact with the first transfer device 20 and / or with the positioning means 24.

[0089] The second transfer device 21 is also disposed in cooperation with the feeding device 23 of the working station 16, to which it can release the sheet 100 substantially without a break in continuity.

[0090] The feeding device 23 of the working station 16 can be replaced by the second transfer device 21 , if this is sufficiently long to comprise the loading station 15 and the working station 16.

[0091] The second transfer device 21 can be formed by feeding elements 21a facing each other to define a channel in which the sheet 100 is held “sandwiched” and fed.

[0092] The second transfer device 21 can for example comprise a pair of parallel conveyor belts configured to hold the sheet 100 with respect to its lateral surfaces 112, 113 leaving it free at the lower part in correspondence with the rough side 111 to be worked. The conveyor belts are supported in rotation by pulleys and optionally also by other return elements, able to be moved close to and away from each other in order to take and release the sheet 100. This belt conveyor system is well known to the person of skill in the art, and is therefore not shown in detail in the drawings. According to another embodiment, the second transfer device 21 can be conveniently realized by means of a holding system that makes the front side 112 of the sheet 100 accessible. An example embodiment of this can consist of a slide, sliding parallel to the direction of transfer F, with which there is integrally associated a plurality of suckers positioned between the support wall 13 and the sheet 100.

[0093] The control unit 30 is also operationally connected to the transfer / feeding devices 20, 21, 23 to coordinate the movement of the sheet 100.

[0094] According to the present invention, the detection means 19 comprise one or more measuring elements 25, preferably from two to four in number, capable of being selectively brought in correspondence with only one, or more than one, already ground side of the sheet 100, figs. 2 and 3. Therefore, the measuring elements 25 are normally in a waiting position and all, or only some, of them can be selectively brought into a measuring position.

[0095] The measuring elements 25 lie and can move on an essentially vertical detection plane, for example parallel to the support wall 13 and thus to the lying plane of the sheet 100. The detection plane is disposed in such a way that the measuring elements 25 can be aligned with the edge of the sheet 100.

[0096] According to possible embodiments, the detection means 19 can be structurally associated with the support wall 13. At least some of the measuring elements 25 can preferably be positioned parallel to a first and / or a second positioning axis X, Y in order to be disposed in correspondence with at least one already worked side 111 of the sheet 100. Positioning the measuring elements 25 parallel to the positioning axes X, Y has the purpose of adjusting their position with respect to the sizes, understood as overall dimensions, of the sheet 100.

[0097] The measuring elements 25, once positioned parallel to one or both positioning axes X and Y, can also be moved toward the at least one ground side 111 , so as to come into contact or close contact therewith, in order to detect the position of the at least one ground side 111 with respect to the position of the grinding plane P or to the reference axis V.

[0098] The positioning axes X, Y can be essentially orthogonal to each other. A first positioning axis X can be essentially horizontal; a second positioning axis Y can be essentially vertical.

[0099] According to some embodiments, the measuring elements 25 can be associated with sliding members 26 which can be positioned along linear guides 27 which extend parallel to one and / or the other positioning axis X, Y.

[0100] Each sliding member 26 can advantageously carry a single measuring element 25.

[0101] A possible configuration and disposition of the measuring elements 25, of the corresponding guides 27 and sliding members 26 is shown in figs. 2 and 3.

[0102] A first measuring element 25a associated with a first sliding member 26a can be positioned along a first guide 27a parallel to the horizontal first positioning axis X, and is therefore capable of detecting the position of a first point of a vertical side 111 of the sheet 100. As shown in fig. 2, this first detection point is close to the position of the first transfer device 20 and the first measuring element 25a is capable of providing information on the position of the sheet 100 in the direction X. A second measuring element 25b associated with a second sliding member 26b is mobile along a second guide 27b parallel to the horizontal positioning axis X. The second guide 27b is parallel to the first guide 27a.

[0103] The second guide 27b is associated sliding with at least one positioning member 29 parallel to the vertical second positioning axis Y. The second measuring element 25b is therefore capable of detecting the position of a second point of a vertical side 111 of the sheet 100. As shown in fig. 2, this second detection point is at a greater vertical height than the first point and can be at a different horizontal height from that of the first point. With the position of the first and second point as described heretofore, the control unit 30 can process the calculation of the angular inclination a between the side 111 and the reference axis V.

[0104] A third measuring element 25c associated with a third sliding member 26c can be positioned along a third guide 27c parallel to the second positioning axis Y. Furthermore, a fourth measuring element 25d associated with a fourth sliding member 26d can be positioned along a fourth guide 27d parallel to the second positioning axis Y, wherein the fourth guide 27d is associated sliding with at least one additional positioning member 31 parallel to the horizontal first positioning axis X.

[0105] According to some embodiments, the third guide 27c and the fourth guide 27d are of the telescopic type.

[0106] The respective sliding members 26c, 26d can slide along the telescopic guides or can be fixed and benefit from their extension / contraction to be positioned.

[0107] In the above-described configuration, the third and fourth measuring element 25c and 25d are capable of giving the position of a third and a fourth point of a side 111 of the horizontal or sub-horizontal sheet 100.

[0108] According to possible embodiments, at least one of the measuring elements 25, in this specific case the first measuring element 25a, is disposed in a fixed vertical position and can only be positioned parallel to the horizontal first positioning axis X moving toward / away from the sheet 100.

[0109] At least another of the measuring elements 25, in this specific case the third measuring element 25c, is disposed in a fixed horizontal position and can only be moved parallel to the vertical second positioning axis Y moving toward / away from the sheet 100.

[0110] According to other possible embodiments, all the measuring elements 25 can be positioned both parallel to the first positioning axis X and also parallel to the second positioning axis Y.

[0111] By suitably combining the movements along the two positioning axes X and Y, the second and fourth measuring element 25b and 25d can conveniently and optionally be moved so as to slide along the respective sides 111 of the sheet 100 that they face, carrying out a plurality of detections (virtually an infinite number) simultaneously with the movement along the sides 111, realizing, in fact, an even more accurate detection of the geometry thereof.

[0112] In this configuration, the first measuring element 25a in a fixed vertical position and the third measuring element 25c in a fixed horizontal position are superfluous and can, therefore, optionally be eliminated or kept inactive without compromising the operation of the machine.

[0113] By way of example, the measuring elements 25 can consist of mechanical probes, in turn associated with known electric / electronic transducers, for example of the linear or rotary type, readily available and known to the person of skill in the art, and they can be equipped with movement to pass from a rest position in which they leave free transit to the sheet 100, to a work position in which they can come into contact with the sheet 100, or the transducers can alternatively consist of non-contact sensors, for example of the optical type, with detection beam / image in a direction orthogonal to the sheet’s 100 resting plane.

[0114] According to other possible embodiments, the measuring elements 25 can consist of distance meters, for example of the laser triangulation optical type with a beam substantially parallel to the support wall 13.

[0115] In this case, the first and second measuring element 25a and 25b can conveniently be positioned at a fixed abscissa along the first positioning axis X, fig. 4. Similarly, the third and fourth measuring element 25c and 25d can conveniently be positioned at a fixed ordinate along the second positioning axis Y, fig. 4.

[0116] According to another embodiment, it is possible to use only one measuring device per axis, for example it is possible to use only the second and fourth measuring element 25b and 25d, where the second measuring element 25b, equipped exclusively with a travel along the second positioning axis Y, is capable of detecting the distance of the side I l la from the reference axis V in a plurality of positions along the second positioning axis Y, while the fourth measuring element 25d, equipped exclusively with a travel along the first positioning axis X, is capable of detecting the distance of the side 111 with respect to the grinding plane P in a plurality of positions along the first reference axis X.

[0117] According to this other embodiment, it is possible to further simplify the construction of the present invention, further increasing its precision thanks to the possibility of averaging repeated measurements. According to another embodiment, it is possible to use only two distinct measuring elements 25, integral with the bearing structure 11 of the grinding machine 10, equipping each one with a rotary movement around an axis thereof, fig. 6.

[0118] According to another embodiment shown in fig. 7, it is possible to use a single measuring element 25, with roto-translational or simply rotary movement around the perimeter of the sheet 100, to detect one or more reference sides 111. For example, the measuring element 25 can be mounted at a terminal end 32a of a rod 32 which is pivoted, at an opposing end 32b, to a fixed part of the grinding machine 10, wherein to a rotation of the rod 32 there corresponds a different positioning of the measuring element 25 with respect to the side to be measured.

[0119] According to some embodiments, the positioning means 24 can be operationally associated with the first transfer device 20 to determine a rotation and / or a translation thereof, on the basis of the command signal, advantageously before the transfer of the sheet 100 toward the working station 16 begins. Therefore, the positioning of the first transfer device 20, and therefore of the sheet 100, is static, that is, it occurs preferably with the sheet 100 stationary.

[0120] According to possible embodiments, the positioning means 24 can cooperate directly with the sheet 100. In this case, the first transfer device 21 remains in the static position.

[0121] The positioning means 24 can for example comprise two distinct actuators 28 which can act simultaneously to raise or lower the first transfer device 20, or the sheet 100 directly, and / or in an independent manner to determine a rotation of the first transfer device 20, or of the sheet 100 directly.

[0122] The operation of the grinding machine 10 described heretofore, which corresponds to the method according to the present invention, provides, for each sheet 100, an initial working cycle in which the sheet 100 is first acquired by the first transfer device 20, optionally transferred in the direction of transfer F and subsequently disposed with a first side 11 la at a certain working height H from the grinding plane P by means of the positioning means 24. At this point, the second transfer device 21 comes into action, and then the first transfer device 20 is lowered. The transfer of the sheet 100 continues along the grinding plane P so as to perform a removal of material equal to a predetermined depth of pass. The initial working cycle is followed by a certain number of other working cycles, equal to the remaining number of sides 111 of the sheet 100 that has to be ground.

[0123] Each additional working cycle essentially comprises the following steps. A loading step, in which the same sheet 100 is acquired by the transfer means 18, in particular by the first transfer device 20, and optionally transferred in the direction of transfer F with a second side 11 lb to be ground, distinct from the first side I l la, facing toward the transfer plane T or the grinding plane P until it reaches the detection means 19. A detection step, in which, with the sheet 100 stationary, the detection means 19 detect at least one distance D, D’ between a point on the at least one first side I l la and the reference axis V and / or the grinding plane P and send a corresponding detection signal to the control unit 30.

[0124] A processing step, in which the control unit 30, as a function of the detection signal received and of the certain geometry to be given to the sheet 100, sends a corresponding command signal to the positioning means 24.

[0125] A positioning step, in which the positioning means 24 position the sheet 100 with respect to the grinding plane P to grind the second side 111b, orienting it angularly by a certain angle of orientation 5 and translating it vertically by a certain working height H.

[0126] In the positioning step, the positioning means 24 can preferably act on the first transfer device 20 which supports the sheet 100.

[0127] According to a variant, the positioning means 24 can act directly by positioning the sheet 100. A step in which the second transfer device 21 closes and engages the glass sheet

[0128] 100, and subsequently the first transfer device 20 and / or the positioning means 24 are lowered so as to no longer affect the glass sheet 100 during the subsequent steps.

[0129] A feeding and subsequent working step, in which the sheet 100 is fed toward the plurality of grinding heads 22 by the second transfer device 21, possibly in cooperation with the feeding device 23 present in the working station 16.

[0130] During the feeding and subsequent working step, the second transfer device 21 then takes delivery of the sheet 100, previously positioned, holds it through its lateral surfaces 112, 113 and feeds it linearly toward the grinding plane P. Before the movement of the sheet 100 begins, the first transfer device 20 is lowered, or in general released, with respect to the sheet 100.

[0131] An unloading step, in which the sheet 100, which now also has the second side 111b ground, is fed in the direction of feed and removed.

[0132] The other working cycles are essentially repeated with the sheet 100 which, in the loading step, is disposed with another side to be ground facing toward the transfer plane T or toward the grinding plane P, and positioned in similar manner to what described above.

[0133] For example, with reference to fig. 8A, a first side 11 la of a rectangular-shaped sheet 100 is worked by the machine 10.

[0134] Subsequently, the sheet 100 is removed from the unloading station 17 and returned onto the loading station 15 rotated clockwise by 90°. The first and second measuring element 25a and 25b (fig. 8B) are now capable of detecting the position of the side 11 la with respect to the reference axis V and of sending the information useful to command the correct positioning of the sheet 100 to the control unit 30, so that the grinding plane P (that is, the future second side 111b, after working) is in the correct angular position with respect to the side I l la, already worked.

[0135] The next working transition, fig. 8C, provides another 90° clockwise rotation of the sheet 100. At this point, the already worked sides are indicated with references I l la and 11 lb. As can be seen from fig. 8C, the third and fourth measuring element 25c and 25d are used to correctly position the first side I l la both angularly and also in terms of distance from the grinding plane P (detection of the distances D and D’ in fig. 2). In other words, the detection of the position of the first side 11 la allows to position the third side 111 c to be ground at a desired distance and angle with respect to the grinding plane P.

[0136] Before working the last side 11 Id of the sheet 100, the third and fourth measuring element 25c and 25d are still used for the positioning, as seen in fig. 8D.

[0137] The example referred to in figs. 8A-8D just described concerns the case where the direction of feed is from right to left and the measuring elements 25a and 25b are mounted on the side facing in the direction of transfer F.

[0138] In the event that the direction of feed was opposite to those shown in the previous example, the rotation of the sheet 100 between one working transition and the next would need to be performed counterclockwise instead of clockwise.

[0139] Similarly, in the event that the direction of transfer F was from right to left and the measuring elements 25a and 25b were disposed on the side opposite the direction of transfer F, the rotation of the sheet 10 between one working transition and the next would have to occur counterclockwise.

[0140] It is now clear from the example disclosed above how it is possible to control both the angular position of the various sides of the sheet 100 and also its sizes, through measurements always acquired with respect to the sides already worked previously.

[0141] The example of figs, from 9 A to 9C shows the working cycle of a triangularshaped sheet 100. It can be seen that first the first side I l la is worked, then the third and fourth measuring element 25c and 25d are used to correctly position the sheet 100 in order to work the second side 111b. Finally, to guarantee the correct shape and the correct sizes of the finished piece, the first, third and fourth measuring element 25a, 25c and 25d are used to position the sheet 100, before working the third side 111c.

[0142] Furthermore, in the case of figs, from 10A to 10D, in which the sheet 100 has the shape of a parallelogram, it is sufficient to use only the third and fourth measuring element 25c and 25d in order to determine all the positions.

[0143] Finally, as an additional example, in the case of a sheet 100 with a regular pentagonal shape, the rotations of the sheet 100 before working the next side are of 144° and combinations of the first, third and fourth measuring element 25a, 25c and 25d are used, as shown in figs, from 11 A to 1 IE.

[0144] It is clear that modifications and / or additions of parts may be made to the grinding machine 10 and to the method as described heretofore, without thereby departing from the field and scope of the present invention, as defined by the claims.

[0145] It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art will be able to achieve other equivalent forms of a rectilinear grinding machine for sheet-like elements and corresponding grinding method, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

[0146] In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors with regard to the field of protection defined by the claims.

Claims

CLAIMS1. Rectilinear grinding machine (10) comprising a plurality of grinding heads (22) defining a grinding plane (P), said machine (10) being configured to give a certain geometry to a sheet-like element (100) having at least one first reference side (H la) and at least one second side (11 lb) to be worked, wherein said grinding machine (10) comprises, upstream of said grinding plane (P):- a first transfer device (20) configured to acquire said sheet-like element (100),- a second transfer device (21) configured to transfer said sheet-like element (100) in a direction of transfer (F) toward a working station (16), with said second side (11 lb) facing toward said grinding plane (P),- detection means (19) configured to detect at least one distance (D, D’) between at least one point lying on said at least one first side (11 la) and a reference axis (V) or said grinding plane (P), - positioning means (24) configured to position said sheet-like element ( 100) with respect to said grinding plane (P), orienting it angularly by an angle of orientation (5) and translating it with respect to said grinding plane (P) by a working height (H), as a function of said at least one distance (D, D’) and said certain geometry, and - a control unit (30) operationally connected at least to said detection means(19) and to said positioning means (24), and in which at least data relating to said certain geometry are stored or entered, characterized in that it comprises one or more measuring elements (25) able to be commanded by said control unit (30) to detect the distance (D, D’) of at least two distinct points of said at least one first side ( 111 a) with respect to said reference axis (V) or said grinding plane (P), and in that said second transfer device (21) is distinct from said first transfer device (20) and configured to laterally sustain said sheet-like element (100) and guarantee its transfer at least from a detection zone to said working station (16) in the direction of transfer (F) parallel to said grinding plane (P).

2. Grinding machine (10) as in claim 1, characterized in that some of said measuring elements (25) can be positioned parallel to a first and / or a second positioning axis (X, Y) which are coplanar and orthogonal with respect to eachother.

3. Grinding machine (10) as in claim 2, characterized in that at least one of said measuring elements (25) is disposed in a fixed vertical position and can only be positioned parallel to said horizontal first positioning axis (X), and in that at least another of said measuring elements (25) is disposed in a fixed horizontal position and can only be positioned parallel to said vertical second positioning axis (Y).

4. Grinding machine (10) as in claim 2 or 3, characterized in that said measuring elements (25) are associated with sliding members (26) which can be positioned along respective linear guides (27) which extend parallel to one or the other of said first and second positioning axis (X, Y).

5. Grinding machine (10) as in claim 4, characterized in that a first measuring element (25a) associated with a first sliding member (26a) can be positioned along a first guide (27a) parallel to said horizontal first positioning axis (X), and in that a second measuring element (25b) associated with a second sliding member (26b) can be positioned along a second guide (27b) parallel to said horizontal first positioning axis (X), wherein said second guide (27b) is associated sliding with at least one positioning member (29) parallel to said vertical second positioning axis (Y)-6. Grinding machine (10) as in claim 4 or 5, characterized in that a third measuring element (25c) associated with a third sliding member (26c) can be positioned along a third guide (27c) parallel to said vertical second positioning axis (Y), and in that a fourth measuring element (25d) associated with a fourth sliding member (26d) can be positioned along a fourth guide (27d) parallel to said vertical second positioning axis (Y), wherein said fourth guide (27d) is associated sliding with at least another positioning member (31) parallel to said horizontal first positioning axis (X).

7. Grinding machine (10) as in claim 6, characterized in that said third guide (27c) and said fourth guide (27d) are of the telescopic type.

8. Grinding machine (10) as in claim 1, characterized in that said measuring elements (25) are disposed in a fixed position along a first and / or a second positioning axis (X, Y) which are coplanar and orthogonal with respect to each other.

9. Grinding machine (10) as in claim 1, characterized in that said detectionmeans (19) comprise a single measuring element (25) mounted at a terminal end (32a) of a rod (32) which is pivoted, at an opposing end (32b), to a fixed part of said grinding machine (10), wherein to a rotation of said rod (31 ) there corresponds a different positioning of said measuring element (25) with respect to said at least one first side (I l la) in order to detect the distance (D, D’) of said two distinct points.

10. Grinding machine (10) as in claim 1, characterized in that said detection means (19) comprise two distinct measuring elements (25) rotatably attached to a fixed part of said grinding machine (10), wherein to a rotation of each of said measuring elements (25) around an orientation axis thereof, there corresponds a different positioning thereof with respect to said at least one first side (I l la) in order to detect the distance (D, D’) of said two distinct points.

11. Grinding machine (10) as in any claim hereinbefore, characterized in that said measuring elements (25) are chosen between a contact or a remote sensor or transducer.

12. Grinding machine (10) as in any claim hereinbefore, characterized in that said first transfer device (20) defines a substantially horizontal transfer plane (T) for said sheet-like element (100), with which said positioning means (24) are associated.

13. Grinding machine (10) as in any claim hereinbefore, characterized in that said second transfer device (21) is configured to transfer said sheet-like element (100) holding it and sustaining it through at least one of its facing lateral surfaces (112, 113) with a larger extension.

14. Grinding machine (10) as in any claim hereinbefore, characterized in that said first transfer device (20) is a motorized loading plane.

15. Grinding machine (10) as in any claim from 1 to 13, characterized in that said first transfer device (20) is a fixed resting plane.

16. Method for the rectilinear grinding of a sheet-like element (100) having at least one first reference side (I l la) and at least one second side (111b) to be worked, comprising: a loading step, in which said sheet-like element (100) is acquired by a first transfer device (20) with said second side (111b) facing toward a grinding plane (P), a detection step, in which detection means (19) detect at least one distance (D, D’)between at least one point lying on said at least one first side (I l la) and a reference axis (V) or said grinding plane (P), and send a corresponding detection signal to a control unit (30), a processing step, in which said control unit (30), as a function of said detection signal and of a certain geometry to be given to said sheet-like element (100), processes the angular inclination (a) between said first side (I l la) and said reference axis (V) and sends a corresponding command signal to positioning means (24), a positioning step, in which said positioning means (24), on the basis of said command signal, position said sheet-like element (100) with respect to said grinding plane (P), orienting it angularly by a certain angle of orientation (5) and translating it by a certain working height (H), a feeding and subsequent working step, in which said sheet-like element (100) is fed toward a plurality of grinding heads (22) defining said grinding plane (P), characterized in that in said detection step one or more measuring elements (25) are commanded by said control unit (30) to detect the distance (D, D’) of at least two distinct points of said at least one first side (I l la) with respect to said reference axis (V) or said grinding plane (P), and in that in said feeding step said sheet-like element (100) is moved parallel to said grinding plane (P) by means of a second transfer device (21) distinct from said first transfer device (20) and configured to laterally sustain said sheet-like element (100) and guarantee its transfer in a direction of transfer (F) parallel to said grinding plane (P).

17. Method as in claim 16, characterized in that during said detection step the sheet-like element (100) is stationary.

18. Method as in claim 16 or 17, characterized in that during said positioning step said positioning means (24) act on said first transfer device (20) which supports the sheet-like element (100) on the lower part on a transfer plane (T).

19. Method as in any claim from 16 to 18, characterized in that after said positioning step the second transfer device (21) takes delivery of the sheet-like element (100) and sustains it through at least one facing lateral surface (112, 113) thereof with a greater extension, and feeds it linearly toward a working station (16) in which said plurality of grinding heads (22) is disposed.

20. Method as in claim 19, characterized in that after the second transfer device(21 ) has taken delivery of the sheet-like element (100), the first transfer device (20) and / or the positioning means (24) are lowered in order to be released from the sheet-like element (100) while the latter is fed toward said working station (16).

21. Method as in any claim from 16 to 20, characterized in that said sheet-like element (100) is loaded in a zone distinct from said measuring zone, and the transfer of said sheet-like element (100) into the measuring zone occurs by means of a suitable movement device integral with said transfer device (20) or coinciding therewith.

Images