Apparatus and method for carrying out working on a sheet

Abstract

Apparatus and corresponding method for carrying out working of a sheet element (1), which has a first lateral surface (1a) and an opposing second lateral surface (1b), the sheet element (1) being held by special gripping members and comprising a first and at least one second working head which are mobile in two distinct directions in order to carry out working of the same or different types.

Description

[0001] “APPARATUS AND METHOD FOR CARRYING OUT WORKING ON A SHEET”

[0002] FIELD OF THE INVENTION

[0003] The present invention concerns an apparatus and a method for working a sheet, made of glass or other glass substitute materials, in particular material removal machines.

[0004] BACKGROUND OF THE INVENTION

[0005] Apparatuses for working sheet elements which are pre-cut into various shapes - rectangular, triangular, trapezoidal, etc. - in order to make a finished or semifinished product are known. A sheet element is typically defined by two opposite larger surfaces and a perimeter edge.

[0006] In these apparatuses, it is usually possible to identify a material loading zone, a work zone and an unloading zone. When these zones are aligned, they define a direction of advance X.

[0007] If Z is the direction orthogonal to one of the two larger surfaces of the sheet element, the Y axis is defined as the direction substantially orthogonal to X and Z. A rest or lying plane n of the sheet element is also defined, which is normally substantially parallel to the directions X and Y and orthogonal to Z.

[0008] Fig. 1 shows a schematic section view of some of the possible perimeter working of the sheet elements as above.

[0009] A grinding working can be carried out on a sheet 1, which consists in the removal of material from the perimeter edge operated by a tool (2001 , 2002, 2003) made to rotate around its own axis (Q, Q’, Q”, advantageously parallel to the Z axis), generating a grooved perimeter surface 1c. Tools of this type, also called grinding wheels, can be conformed in different ways depending on the type of final result to be achieved.

[0010] A second type of known working allows to localize the removal of material in a specific area of the sheet 1, for example fig.l shows a tool 2004 rotating around its own axis Q” ’ that makes a hole.

[0011] The same tool can also generate oblong milling or pockets.

[0012] These types of working can optionally be inserted as initial, final or intermediate working of a larger process, or be part of a stand-alone process. The known apparatuses for carrying out these types of working consists of at least one spindle on which tools are keyed that move in relative motion with respect to the sheet 1 being worked.

[0013] A first solution is to keep the sheet in a fixed position, moving the tools around it (fixed sheet machines).

[0014] For example, in EP2591879A1 the sheet being worked is held in an upright position by special holding means (suckers). However, this working process requires a long time, especially when compared to the cycle times of a possible insulating glass production line located downstream of it and served by it. In addition, the plurality of retractable suckers used, each with its own movement on the plane so as to be able to adapt to the various sizes of the sheets being worked, implies considerable complications and considerable costs of the solution.

[0015] A different solution is proposed in EP1166961B1, in which, in a horizontal configuration, the perimeter edge of a sheet is worked, while the sheet is held by a special arrangement of suckers. Four working heads are used simultaneously to achieve adequate productivity, two of which are installed on two parallel moving bridges. This results in each working head acting on only one of the four sides of the sheet, with a considerable reduction in cycle time.

[0016] The horizontal arrangement of the sheet, although advantageous thanks to the fact that the weight of the sheet acts at least partly to compensate for a flatness defect thereof, nevertheless has the disadvantage linked to the operational need to overturn the sheet several times, from a vertical position in which it is generally stored to a horizontal working position and vice versa, resulting in time losses and inefficiencies.

[0017] Also in this case, in order to guarantee sufficient quality of the working, it is necessary to hold the sheet with a considerable number of suckers in order to guarantee the stability of the workpiece and the reduction of vibrations.

[0018] Each sucker has to be equipped with a retractable mechanism so that it can be excluded if it is outside the perimeter of the sheet, so as not to interfere with the path followed by the working head.

[0019] Also in this case, therefore, the apparatus is very complex.

[0020] Another type of construction of known machines comprises means for moving the sheet in the direction X and means for moving the tool in the direction Y during working.

[0021] The in-plane path followed by the tool relative to a reference that is integral with the sheet will thus be determined by the combination of these two movements.

[0022] An example of this type of embodiment is found in EP3170622B1, where the working heads (two opposite) have exclusively linear movement along the vertical Y axis, while the sheet is moved during working along the horizontal X axis.

[0023] This embodiment, however, has a lower degree of precision than the fixed sheet machines due to the additional movement associated with the X axis.

[0024] There is therefore the need to perfect an apparatus and a method for carrying out working of a sheet that are characterized by high productivity and precision, so as to overcome the limitations of the state of the art.

[0025] One purpose of the present invention, which corresponds to the technical problem to be resolved, is to perfect a method and provide a corresponding apparatus for working a sheet element efficiently, quickly, and precisely.

[0026] Another purpose of the present invention is to perfect a method capable of working the sheets in a stable and reliable manner, supplying a high-quality finished product at exit, resolving the problem of the vibrations that are generated during the working with abrasive tools, being able to guarantee a correct relative positioning between the sheet to be worked and the tool, even for sheets that have geometric defects on their edges.

[0027] Another purpose is represented by the need to be able to also work sheets that have flatness defects in a reliable manner.

[0028] 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.

[0029] SUMMARY OF THE INVENTION

[0030] 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.

[0031] 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, an apparatus for working a sheet element comprises lower rest means for resting the sheet and at least two working heads, each comprising at least one tool or group of tools which can be moved at least along a lying plane TI independently of each other.

[0032] The sheet element comprises two opposite larger surfaces and a perimeter edge, and it is disposed on the lying plane i defined by one of such larger surfaces.

[0033] The two working heads can be moved at least in a first direction X and in a second direction Y, distinct from the first direction X, both these directions being parallel to the lying plane TI.

[0034] In accordance with another aspect of the present invention, each working head can comprise means for moving the tools or groups of tools in a third direction Z, normally substantially orthogonal to the directions X and Y.

[0035] In accordance with another aspect, each head can be individually configured to remove material along the perimeter of the sheet or inside this perimeter.

[0036] According to another aspect, the apparatus can comprise holding members, each able to be selectively moved and activated so as to sustain the sheet integrally during working without interfering with the tools’ path.

[0037] According to another aspect of the present invention, the holding members can conveniently be disposed in the first direction X, preferably in a zone adjacent to the sheet’s lower edge.

[0038] According to another aspect, the present invention can comprise rear rest members mobile in the second direction Y in order to adapt to the height of the glass.

[0039] According to another aspect of the present invention, the rest members can be moved outside the tools’ path.

[0040] According to another aspect of the present invention, the rest members can comprise additional retractable holding means, drivable to further improve the grip of the sheet.

[0041] According to some embodiments of the present invention, the lower rest means of the work zone can be positioned from a condition of contact with the lower edge of the sheet to a condition of distance therefrom, in order to allow the working heads to pass along the lower edge.

[0042] According to some embodiments of the present invention, each working head can comprise a stabilization unit for stabilizing the sheet element being worked with first and second sliding constraint members, which are opposing and selectively drivable to bring the respective sliding constraint members from a deactivation condition to a condition of interaction with the sheet and vice versa.

[0043] According to some embodiments of the present invention, the lower rest means can be equipped with means for translating the sheet element, for example suitable to move the sheet from a previous loading zone or working station to a work zone, and form here to a subsequent unloading zone or additional working station.

[0044] According to some embodiments of the present invention, each working head comprises sensors for detecting the actual geometry of the perimeter.

[0045] According to some embodiments of the present invention, each working head comprises fluid jets for lubricating and cooling the sheet element and the tool, which can be selectively activated.

[0046] According to some embodiments, the at least one work unit is comprised in a machine suitable for accommodating sheet elements disposed in such a way that the second direction Y has an inclination with respect to the floor greater than 0°.

[0047] According to some embodiments, this inclination is preferably chosen between 75° and 88°.

[0048] In accordance with one aspect of the present invention, the apparatus comprises a central control unit configured to execute a specific work program containing instructions to manage the working heads in a coordinated manner, so as to determine the method as described.

[0049] In accordance with one aspect of the present invention, the central control unit is configured to receive at input all the geometric data able to define the shape and sizes of the sheet element, including an initial position of the sheet element in the direction X.

[0050] In accordance with one aspect of the present invention, a method for carrying out working on a sheet element, which has a first lateral surface, an opposing second lateral surface and a perimeter edge, comprises at least the following steps:

[0051] - a step of positioning the sheet element to be worked in the work zone of the apparatus;

[0052] - a step of acquiring the position of the sheet element;

[0053] - a working step, in which the working tools associated with the working heads carry out a desired working of the sheet, by means of a movement of two or more of the working heads with respect to the sheet element; - a step of transporting the sheet outside of the work area.

[0054] According to another aspect, the positioning of the sheet element occurs so as to optimize the number of the mobile rest members and of the retractable holding means, whose active surface completely impacts the sheet element in a zone not affected by the working.

[0055] In accordance with another aspect, the method can comprise one or more of the following additional, complementary and non-exclusive steps, chosen from the following:

[0056] - positioning of rear rest members in the second direction Y at a level compatible with the height of the sheet to be worked;

[0057] - translation of the sheet in the first direction X from a previous work or loading station;

[0058] - selective displacement of the mobile rear rest members that interfere with the movement of the working heads into a position that does not interfere with this movement;

[0059] - selective displacement and activation of some of the retractable holding members into a gripping position, the retractable holding members being chosen so that their active surface, once moved, completely impacts the sheet in a zone that is internal to its perimeter that is not affected by the subsequent working;

[0060] - displacement of the lower rest means to a position not interfering with the paths of the working heads.

[0061] In accordance with another aspect of the method, if the working involves the perimeter of the sheet, sliding constraint members can interact operationally with the sheet in order to guarantee precision in the working and minimize vibrations.

[0062] In accordance with another aspect of the present invention, during the step of working along the perimeter of the sheet, two of the independently movable tools can start the working from a common comer of the sheet and finish it at an opposing comer, following distinct and complementary paths.

[0063] In accordance with one aspect of the present invention, the step of positioning in the work zone can comprise the movement in the first direction X from a previous loading station located upstream of the working station.

[0064] In accordance with one aspect of the present invention, the transport step after the working step can comprise the movement in the first direction X to a subsequent unloading station or to a subsequent working station.

[0065] In accordance with one aspect of the present invention, the step of transporting a new sheet element to be worked into the work zone can occur simultaneously with the step of transporting the previously worked sheet element toward the next station.

[0066] In accordance with one aspect of the present invention, several working heads with which the apparatus is equipped can be configured to work simultaneously and each perform the same or different types of working.

[0067] In accordance with this aspect of the present invention, this simultaneity can allow each working head to work different parts of the same sheet element, or each to work different sheet elements at the same time.

[0068] In accordance with one aspect of the present invention, the trajectory followed by the working heads can be optionally chosen from a trajectory controlled on the basis of a work program set by the user on the central control unit, or, in the case of perimeter working, it can be guided by the geometry of the workpiece (selflearning) by means of a suitable sensor that scans the actual geometry and allows to achieve the removal of a preset amount of material.

[0069] In accordance with another aspect of the present invention, the working tools can optionally be moved along a predefined rectangular path in order to carry out the squaring thereof.

[0070] In accordance with one aspect of the present invention, during the working of the perimeter of the sheet, some tools can be moved in a third direction Z in order to center the outline of the tool with the corresponding outline of the sheet element, or, for tools with a cylindrical geometry, they can be moved continuously and alternately in the third direction Z in order to distribute their wear.

[0071] In accordance with another aspect of the present invention, a plurality of tools can be housed in axial sequence on the shafts of the spindles, so that by moving this sequence in the third direction Z, it is possible to select the tool most suited to the specific working.

[0072] Conveniently, this movement of the tools in the third direction Z can also allow to carry out the removal of material during the milling / drilling working on the sheet.

[0073] In accordance with another aspect of the present invention, the method can advantageously comprise carrying out the working of the perimeter of the sheet element continuously, as a result of the coordinated movement of the axes which guarantees that the tool is always sequentially in contact with a side of the sheet element.

[0074] In accordance with one aspect of the present invention, this continuous perimeter working process can also occur in the presence of discontinuities in the tangency of the perimeter, such as sharp edges for example.

[0075] In accordance with one aspect of the present invention, during the working of the corners, constraint members are selectively activated to interact with the sheet element in a zone close to the working tools.

[0076] In accordance with one aspect of the present invention, during the working, the sliding constraint members mounted on the working heads can be selectively moved in a reference that is integral with the head, so as to guarantee the positioning thereof within the perimeter of the sheet element being worked. By doing so, it is possible to always keep the constraint members in a condition of interaction with the sheet element, even in correspondence with the comers, thus guaranteeing that the sheet element is always held symmetrically and in a balanced manner, so that the vibrations caused by the motion of the working tool against the sheet element are reduced to a minimum. The direct consequence of such a holding condition is that the working is much more precise and the mechanical stresses on the sheet element are limited.

[0077] In accordance with what provided by the present invention, during the working step, the sheet element is kept in a stationary position while the working heads can move in the first direction X and in the second direction Y.

[0078] DESCRIPTION OF THE DRAWINGS

[0079] These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

[0080] - fig. 1 schematically shows some possible working that can be performed according to the present invention;

[0081] - fig. 2 shows a front view of an embodiment of a working head comprised in the present invention;

[0082] - fig. 3 shows the D-D section view outlined in fig. 2; - fig. 4 shows the detail B identifiable in fig. 3;

[0083] - figs. 5 and 6 show the front view and the corresponding lateral view, respectively, of an embodiment of the present invention;

[0084] - fig. 7 shows a working sequence according to the embodiment of the present invention;

[0085] - figs. 8a and 8b shown an example embodiment of a retractable holding mean comprised in the present invention;

[0086] - fig. 9 shows the references to the geometric elements relating to a sheet element being worked, with particular reference to a quadrilateral figure.

[0087] 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.

[0088] 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.

[0089] DESCRIPTION OF AN EMBODIMENT OF THE PRESENT INVENTION

[0090] With reference to the attached drawings, the sheet elements subjected to working are identified with single-digit numbers, the main units of the machine are identified with double-digit numbers, while the details and construction mechanisms are indicated with four-digit numbers, the first two digits of which are those of the main unit to which they belong.

[0091] The sheet, or sheet element, is identified with 1 , and its sides are respectively indicated as follows: front surface la (surface of the sheet on the operator side), rear surface lb (surface of the sheet on the side resting on the lying plane JC). In the case of perimeter working of a quadrangular sheet, the edges are indicated (starting from the lower one and continuing counterclockwise) with: le, If, 1g, Ih. The set of these edges constitutes the perimeter, or perimeter edge, of the sheet 1 and will be indicated as a whole with lc. Finally, the comers, given by the intersection of the previously defined edges, are identified with li, Ij, Ik, 11, respectively. The thickness of the sheet is identified with the letter “T”. These conventions and numbers are all shown together in fig. 9.

[0092] Fig. 2 shows the front view of an embodiment of a working head 200 suitable to be installed in an apparatus according to the present invention, configured to perform material removal working on the perimeter 1c of sheets 1 made of glass, or more generally a material having a sheet-like conformation.

[0093] The working head 200 is mounted on a plate 2030 which is able to be moved in the first X and second Y directions with respect to the sheet 1.

[0094] Fig. 3 shows the working head 200 in section, according to the line D-D of fig. 2.

[0095] A spindle unit 203 is associated with the working head 200.

[0096] The spindle unit 203 can conveniently consist of a spindle 2039 on which a sequence of tools, or a single tool 2005, can be mounted, rotatably associated with its axis of rotation Z 1.

[0097] The sequence of tools 2005 can advantageously consist of a succession in the axial direction of one or more tools with cylindrical symmetry such as, by way of example, flat, sector, V-shaped or trapezoidal grinding wheels, which in turn can be chosen to selectively adapt to different thicknesses of the sheet.

[0098] The base of this spindle unit 203 can be mounted on sliding blocks 2032, which are associated sliding with guides 2033 integral with the plate 2030, which allow it to be moved in the direction Z1 by means of a known drive (not shown).

[0099] These translation movements in the third direction Z of the spindle units are particularly useful in working sheet elements for the following reasons: in the case of shaped tools (for example the tool 2002 of fig. 1), they allow to center the tool with respect to the sheet’s thickness;

[0100] - it is common practice to mount a plurality of tools on each axis of the spindle unit 203, thus creating a sequence of tools (2005) in succession in the third direction Z. The movement of the spindle unit 203 in the third direction Z allows to change the tool with which it is provided to perform the working of the edge without stopping the machine;

[0101] - in the case of tools with a cylindrical geometry, it is possible to continuously vary the position of the tool in the third direction Z during the working of the edge, in order to guarantee a uniform wear of the tool;

[0102] - in the case of drilling operations, the translation movement in the third direction Z constitutes the tool’s advancing movement.

[0103] In any variant provided, it is possible to optionally mount, integrally with the working head 200, jets 2036, 2036’ for the introduction of lubricating-cooling fluid into the working.

[0104] The person of skill in the art will understand that these jets can be in any number whatsoever and be positioned in a known manner with respect to the tools.

[0105] Sensors 2010 suitable to survey the actual geometry of the workpiece being worked can optionally be mounted integrally with the working head 200.

[0106] These sensors 2010 are configured to allow the machine to remove desired amounts of material, rather than working the workpiece in order to obtain a predetermined shape.

[0107] The working head can be equipped with one or more stabilization units 202 that can rotate around their axis Zp (advantageously chosen coincident with the axis of rotation of the spindle) so as to assume the angular position C appropriate for the working step to be performed.

[0108] The stabilization unit 202 consists of a first sliding constraint member 2023 and a second sliding constraint member 2022, respectively opposing on the two surfaces lb and la of the sheet 1.

[0109] Fig. 4 shows the detail indicated with letter B of fig. 3.

[0110] Each constraint member 2022 and 2023 can advantageously be realized by a contact element 2025, 2027 characterized by a high yielding material, to allow to reduce the contact pressure on the respective surfaces la, lb of the sheet 1 to a minimum, and by rolling elements 2024, 2026 keyed onto the contact elements.

[0111] Alternatively, each constraint member can also be made by placing a plurality of rolling elements and contact elements in succession.

[0112] The axis of rotation of the constraint member 2023 can be integrally connected to the rotatable plate 2030 of the head 200, while the axis of rotation of the constraint member 2022 is controlled in the third direction Z by the drive 2021 , so as to be able to distance it (“deactivation” step) or move it closer (“activation” step) with respect to the corresponding surface 1 a that faces it.

[0113] The step of activating the stabilization unit 202 has to necessarily take place when the sheet 1 is comprised between the respective sliding constraint members 2022, 2023, so as to guarantee that the interaction between the sheet 1 and the stabilization units does not generate impacts caused by the discontinuity of the contact. It can be understood how, in the case of glass sheets that are not perfectly planar, the movement of activation of the constraint member 2022 allows to bring the sheet into its theoretical position and keep it in the correct position with respect to the tool during working.

[0114] In the embodiment described in fig. 3, this interaction consists in the physical contact between the constraint members 2022, 2023 and the respective surfaces la, lb.

[0115] It follows that, if this interaction is active, in correspondence with the stabilization unit 202 the sheet 1 is constrained to slide on a plane that is parallel to the surface la relative to the working head 200, while any displacements (also understood here as micro displacements or vibrations) in the third direction Z will be locally prevented or damped, thus guaranteeing quality working with high working speeds.

[0116] The person of skill in the art can easily deduce further technical variants that create the same effect.

[0117] By way of example, the drive 2021 can be realized by means of pneumatic, electric, hydraulic, or hybrid type actuators (oil-electric, hydro-pneumatic, ...).

[0118] In turn, the sliding constraint members can alternatively consist of rolling or swiveling elements, sliding blocks or fluidic pads.

[0119] In the latter case, the condition of interaction with the sheet is obtained by keeping the fluidic pads at a controlled distance from the surface to be stabilized (for example a few tenths of a millimeter), a distance necessary to keep the correct pressure of the fluid with respect to the respective surfaces la, lb of the sheet 1.

[0120] Another variant consists in equipping both sliding constraint members 2022, 2023 with movement in the third direction Z. In this way, it is possible to guarantee the complete decoupling of the sheet from both elements.

[0121] Fig. 2 shows a reciprocal position of the sheet being worked with respect to the head 200, in which the respective contact elements 2025, 2027 of the respective constraint members 2022, 2023 of the holding and stabilization unit 2020 are located within the perimeter delimited by the edge 1 c of the sheet 1.

[0122] In this case, as already explained above, it is advantageous to activate the holding and stabilization unit in order to guarantee its interaction with the sheet, thus minimizing vibrations and optimizing the quality of the working.

[0123] Fig. 3 shows the section according to the plane D-D of fig. 2. In it, the stabilization unit 202, according to the embodiment shown by way of example in this variant, is made integral with a frame 2060 that can rotate around the axis Z1 by means of a rolling coupling 2061. The frame 2060, associated with the stabilization unit 202, can be angularly positioned in this specific case by means of a toothed belt 2062 or similar mechanical means, in turn connected to the drive 2031. The rotation C of the stabilization unit 202 with respect to the working head 200 is thus realized (see fig. 2).

[0124] In a working step in which the tool of the pack 2005 is travelling along a rectilinear segment, the inclination C is advantageously chosen so as to guarantee that the rolling plane of the sliding constraint members 2022 and 2023 is parallel to this rectilinear segment.

[0125] In a transitional step of changing the trajectory of the tool (for example in the presence of corners) or at the beginning / end of the working, the inclination C can be advantageously chosen so as to promote the stabilization of the workpiece during working.

[0126] For example, in a step of starting the working it is possible to rotate the stabilization unit 202 slightly “forward”, so that upon impact with the grinding wheel the sheet is already stabilized.

[0127] Similarly, to deal with a corner, it is possible to anticipate the rotation C with respect to the path of the grinding wheel in order to guarantee the continuity of contact of the stabilization unit with the sheet.

[0128] This achieves the maximum effectiveness of the stabilization unit 202, even during the working of particular angles and outlines.

[0129] Steps of activating and deactivating the constraint members 2022 and 2023 in a selective and progressive manner are provided in the head 200, in particular in the steps of starting and ending the working.

[0130] In a second variant, the working head 200 could be configured without the stabilization unit 202 and corresponding means for the rotation around its axis Zp, and in another variant the working head could be configured to mount a milling or drilling tool on the spindle, similar to the tool 2004 of fig. 1, so as to produce manufactured articles with holes, pockets or complex contours. The working head 200 is suitable to be integrated into suitable machines for working sheets, thus creating high productivity apparatuses.

[0131] Generally, these machines are characterized by a single lying plane n of the sheets during all movements, that is, by a single inclination of the Y axis with respect to the horizontal plane.

[0132] Advantageously, this inclination is chosen so that the Y axis is in proximity to the vertical.

[0133] In this way, the machine becomes very compact in its size and the time to load and unload the sheets becomes extremely fast, by using the same lying condition in which the sheets are stored and transported.

[0134] However, the present invention can be easily extended by the person of skill in the art to any configuration whatsoever in which the sheet to be worked is, after the loading step, sustained along one of the edges as a result of its own weight.

[0135] We will define this configuration with the term “vertical machine”.

[0136] Fig. 5 shows a front view of an example embodiment of a vertical machine 30 that integrates two working heads as described above and indicated here with the numbers 200 and 210, meaning that the working head 210 is completely similar to the 200, but equipped with independent movements according to the X, Y axes.

[0137] The machine 30 comprises a main body 3001 to which there are attached rest means 302 and 301 for the sheet 1, which define a sliding plane n on which the sheet is rested during the translation in the direction X.

[0138] Typically, this sliding plane is equipped with idle wheels placed tangentially to the sheet; however, other solutions are also widely used, such as, for example, compressed air pads.

[0139] The support from the lower side of the sheet occurs with lower rest means 304, which can optionally also provide to move the sheet in the first direction X, dragging the lower edge le of the sheet 1 by friction.

[0140] These lower rest means can rotate idle, if they exclusively perform a function of sustaining the weight of the sheet, or they can be mechanically connected to a motor, if they also have the dragging function.

[0141] These rest means are known to the person of skill in the art and can, for example, consist of rolls coated with polymeric material, or belts or chains.

[0142] At least some of the lower rest means 304 can be moved between an active position 3041, suitable to sustain and transport the sheet in the direction X, and an inactive position 3041 ’, at a distance from the sheet to allow the passage of the working head (see fig. 6).

[0143] In this inactive position, the weight of the sheet is entirely sustained by the fixed holding unit 35, in turn consisting of a plurality of retractable holding means 500, each able to be moved and activated selectively.

[0144] Advantageously, the retractable holding means 500 are disposed in line and in proximity to the lower edge le of the sheet element 1, as shown in fig. 5.

[0145] This arrangement, unlike the state of the art which provides a distribution of holding elements on a matrix instead of on a line, makes the construction simpler and cheaper.

[0146] An example embodiment of one of these means 500 is shown in fig. 8a and fig. 8b, in a lateral and top view, respectively.

[0147] These means can consist of a fixed support 5002 to which there are constrained gripping means 5003 which are movable between an active position 5001 ’ and an inactive position 5001” by means of a suitable actuator 5004.

[0148] This active position 5001 ’ allows the gripping members 5003 to be positioned with their active surfaces 5005 in correspondence with the rest plane TI of the sheet, so that these surfaces can exert their gripping action on the sheet.

[0149] Advantageously, the gripping members 5003 can be realized by means of suckers, the gripping action of which is exerted by activating the corresponding vacuum circuit (not shown, since it is widely known).

[0150] Advantageously, the movement between the active position 5001 ’ and the inactive position 5001” can be realized by means of a translation in the direction Z, constrained by means of linear guides 5006.

[0151] Optionally, clearance recovery clamping means (not shown) can also be activated in position 5001 ’, to guarantee that the sheet is sustained rigidly during working.

[0152] Additional rear mobile rest members 306 can be comprised in correspondence with the work area 303 which, in a first active position, have the function of allowing the resting and sliding during the steps of movement of the sheet on the face lb, thanks to the presence of suitable sliding means 3068 (consisting, for example, of idle wheels). From this active position, the mobile rest means 306 are equipped with one or more exclusion movements in an inactive position (306’), in which the sliding means 3068 are moved away from the sheet’s rest plane (plane K), thus allowing the passage of the working head.

[0153] This exclusion movement can conveniently take place by means of a translation along the Y and / or Z axes of the mobile rest means 306.

[0154] Advantageously, the movement along Y can also allow the mobile lateral rest m eans to be able to adapt to the different heights of the sheet element to be worked.

[0155] The mobile rest means 306 can optionally be equipped, as well as with sliding means 3068, as previously described, also with retractable holding means 500’, each able to be moved and activated selectively.

[0156] In this way, it is possible to hold the sheet integrally also on a second portion thereof, located at a higher level in the direction Y with respect to the retractable holding members 500.

[0157] This allows to further reduce vibrations, especially in the presence of sheets that develop in height considerably.

[0158] The machine 30 comprises at least 2 uprights 3060, 3070 mobile in the direction X along the guides 3062, 3063.

[0159] Each upright in turn comprises at least one working head, as previously described, able to be moved in the direction Y with respect to the uprights along guides 3061, 3071.

[0160] Advantageously, the machine 30 also comprises a sensor 3080 that allows to read the position of the sheet in the direction X, the sensor 3080 being advantageously mounted in a fixed position in the first direction X or on a suitable slider that can be positioned sliding in the direction X.

[0161] Alternatively, the sensor 3080 can also be installed on board one of the two uprights 3060, 3070.

[0162] Optionally, the machine 30 also comprises sensors (not shown) suitable to detect the thickness and sizes of the sheet.

[0163] The machine 30 also comprises a control unit (not shown) operationally connected to the mobile means and to the sensors, and in which the data relating to the geometry to be given to the sheet 1 are stored or entered.

[0164] Operationally, the process begins with a positioning of the rest members 306 in the direction Y, in order to bring these members to a level in the direction Y that is compatible with the sizes of the sheet and to a level in the third direction Z such as to position the corresponding sliding means 3068 tangential with the sheet’s rest plane n.

[0165] The sheet can be conveniently introduced by an upstream machine, located sequentially on one side of the machine 30 (for example to the left thereof looking at fig.5).

[0166] The sheet will then be moved in the direction X by the lower rest means 304, into a precisely known position within the work area 303, thanks to the aid of the sensor 3080.

[0167] Preferably, this positioning occurs in such a way as to optimize the number of mobile rest means 306 and of the retractable holding means 500 whose active surface, once moved, completely impacts the sheet in a zone inside its perimeter which is affected by the subsequent working.

[0168] In this way, it is possible to optimize how the sheet is sustained and rested.

[0169] Optionally, the sheet can be loaded directly in the work area 303 with known manual or automatic means.

[0170] Also in this case, the sensor 3080 will provide to acquire its position in the direction X, so as to start the working from a certain reference.

[0171] As is widely known in this field to the person of skill in the art, other physical quantities of the sheet can optionally also be acquired, such as for example thickness, sizes and, in the case of glass with a low emissive coating, also the orientation of such coating.

[0172] Once the sheet has been positioned, the gripping means 5003 of the corresponding unit 35 that are inside the perimeter of the sheet are selectively displaced toward the sheet’s rest plane n and activated so as to guarantee the gripping thereof, while the mobile rear rest members 306 that are in a position of interference with the path of the tools are moved into a position of non-interference with these paths of the working heads (for example they can be displaced in the direction Y or Z).

[0173] The lower rest means 304 are then brought into an inactive position 3041 ’, so that the sheet is sustained exclusively by the holding means 500 and the path of the tool does not interfere with the lower rest means 304 during the working of the lower edge.

[0174] The mobile uprights 3060, 3070 can then begin to move the corresponding working heads 200 and 210 along the set working paths.

[0175] As already described above, in the case of perimeter working, it is useful that the stabilization units 202 constrain the sheet 1 in proximity to the tool in order to minimize its vibrations.

[0176] Alternatively, the machine 30 can be configured so that at least one of the two working heads 200, 210 can perform drilling or milling operations.

[0177] In this case, at least one of the two spindle units 203 can be configured to accommodate the tool suitable to drill or mill, and it can be configured to exclude or remove the stabilization unit 202.

[0178] This allows to configure the machine in a flexible manner, allowing, for example, to perform exclusively perimeter grinding working with both working heads, or to perform drilling and milling working with both working heads, or even to be able to dedicate one of the heads to grinding and a second head to milling, thus allowing maximum production flexibility.

[0179] In the latter case, the machine would have the advantage over the state of the art of carrying out two types of working with a single positioning, with clear advantages also with regard to precision.

[0180] The simultaneous presence of a plurality of working heads (200, 210) that are independent of each other also allows to carry out working at a higher speed than a machine according to the prior art equipped with a single spindle.

[0181] For example, if there are two working heads, as shown in fig. 5, the working speed is twice that of the state of the art.

[0182] Alternatively, it is also possible to load two or more sheets simultaneously into the work area and dedicate each head 200, 210 to different sheets.

[0183] It goes without saying that in the example embodiment of fig. 5 there are two working heads 200, 210, but the person of skill in the art can easily extend the embodiment to a greater number of heads.

[0184] For example, in the case of perimeter working (grinding) of a glass sheet with a quadrangular shape, it is possible to choose a working strategy that consists in starting the working from one of the corners of the sheet and ending the working in the opposite comer, making each head and corresponding tools follow two distinct paths.

[0185] In this way, each tool will have travelled a similar perimeter portion (the same in the case of parallelogram-shaped or rectangular sheets), thus optimizing their paths.

[0186] By way of example, fig. 7 schematically shows successive instants of working the perimeter of a rectangular sheet, starting from the corner 11 (position of heads 210, 200) and ending at the comer Ij (position 210-3, 200-3).

[0187] The working head 210, starting from the corner 11, runs along the lower side le and subsequently the right side If (see subsequent positions 210-1, 210-2, 210-3), while the head 200 runs along the left side Ih and subsequently the upper side 1g, until it reaches the corner Ij (see subsequent positions 200-1, 200-2, 200-3).

[0188] As already described, it is easy to understand how the corners at which the working starts and ends can be chosen in any manner whatsoever, advantageously according to opposing pairs in order to optimize process times.

[0189] For example, it is alternatively possible to start from the corner Ik and end the working in the corner 1 i, achieving the same result.

[0190] Once the working has ended, the working heads can optionally return to the position originally assumed before the process (in this example, bottom left).

[0191] Alternatively, the working heads can start the subsequent working starting from the last corner they reached (Ij, in the specific case), so as to minimize positioning times.

[0192] Another operating mode can provide to execute the working with a number of working heads lower than those available.

[0193] The working heads (200 or 210) that remain stationary during working can be subject to maintenance or tooling operations for subsequent working, while still guaranteeing the operation of the machine itself.

[0194] Once the working has ended, the lower rest means 304 will be restored to the active position of sustaining the sheet, and the retractable holding means 500 will be deactivated and brought to the inactive position, that is, such as to distance the respective active surfaces 5005 out of the plane n.

[0195] Similarly, the mobile rest members 306 previously moved so as not to interfere with the path of the tools are returned to the position of sustaining the sheet. The sheet can then optionally be picked up by the operator or moved in the first direction X toward a subsequent station.

[0196] The machine described can also be used for the perimeter working of non- rectangular and non-quadrangular sheets. In these cases, the movement of each working head is carried out in an interpolated manner in the directions X and Y, as a function of the geometry of the sheet element to be obtained.

[0197] The person of skill in the art, in fact, drawing on the technical literature and other patent titles, can easily deduce optimal methods to optimize the paths, by exploiting the presence of several working heads that can conveniently be made to work in parallel.

[0198] It appears evident that this invention, in its different embodiment configurations, allows to overcome the limitations of the state of the art, realizing a peripheral working of a sheet with excellent quality and shorter times than a similar traditional machine.

[0199] It is clear that modifications and / or additions of parts may be made to the apparatuses and corresponding methods for working sheets as described heretofore, without thereby departing from the field and scope of the present invention, as defined by the claims.

[0200] 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 apparatus and method for carrying out working on a sheet, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

[0201] 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. Apparatus (30) for working at least one sheet element (1) having two opposite larger surfaces and a perimeter edge, said sheet element (1) lying on a lying plane (K) defined by one of said larger surfaces, comprising:- lower rest means (304) suitable to counteract the weight of said sheet element (1) along a lower edge (le) thereof;- at least two working heads (200, 210), each comprising at least one tool or group of tools (2005) which can be moved at least in a first direction (X) and a second direction (Y) different from said first direction (X), both directions being parallel to said lying plane (JI);- holding means (500) retractable between a gripping position (5001 ’) and an inactive position (5001”);- stabilization units (202) selectively and independently drivable to bring the respective sliding constraint members (2022, 2023) from a deactivation condition to an activation condition in interaction with said sheet elements and vice versa.

2. Apparatus as in claim 1, wherein each working head (200, 210) is associated sliding with distinct mobile uprights (3060, 3070) in order to move in said second direction (Y), the mobile uprights (3060, 3070) in turn are sliding in said first direction (X).

3. Apparatus as in claim 2, wherein said first direction (X) is orthogonal to said second direction (Y).

4. Apparatus as in any claim hereinbefore, wherein each working head (200, 210) is equipped with means for displacing said at least one tool or group of tools (2005) in a third direction (Z) orthogonal with respect to said lying plane (K).

5. Apparatus as in any claim hereinbefore, wherein said retractable holding means (500) are disposed along an axis parallel to the first direction (X).

6. Apparatus as in any claim hereinbefore, comprising rest members (306) mobile at least in a direction parallel to the lying plane (n) and comprising sliding elements (3068) suitable for said sheet element (1) to be rested on one of the two lateral faces (lb).

7. Apparatus (30) as in claim 6, wherein said rest members (306) are mobile in said second direction (Y).

8. Apparatus (30) as in claim 6 or 7, wherein said rest members (306) are drivablefrom an inactive position (306’) in which they do not interfere with the passage of the working head, to an active position (306) in which they interact with the sheet element (1).

9. Apparatus (30) as in any claim from 6 to 8, wherein said rest members (306) comprise further retractable holding means (500’), each selectively drivable between a gripping position (51 ’) and an inactive position (51 ”).

10. Apparatus (30) as in any claim hereinbefore, wherein said lower rest means (304) are equipped with a movement to move from a position (3041) of contact with the lower edge (le) of the sheet element (1), to a position not interfering (3041 ’) with the paths of the working heads (200, 210).1 1. Apparatus (30) as in any claim hereinbefore, wherein said lower rest means (304) are equipped with means for translating the sheet element (1) in a direction (X).

12. Method for carrying out working of at least one sheet element (1) comprising a first lateral surface (lb), an opposing second lateral surface (la) and a perimeter edge (1c), said method comprising at least the steps of: a) preparing an apparatus (30) as in any claim from 1 to 11; b) positioning the rest members (306) in the direction (Y) at a level compatible with the sizes of the sheet element (1) to be worked; c) positioning the sheet element (1) to be worked in the work zone (303) of said apparatus (30); d) acquiring the position of said sheet element (1); e) holding said sheet element (1), operated by the gripping members (5003) of the retractable holding members (500) which are comprised within the perimeter of the outline of the sheet element (1) not involved in the working; f) displacing the rest members (306) which are not entirely comprised within the area to be worked into a position (306’) of non-interference with the path of the tools; g) carrying out the desired working, operated by means of one or more working tools (2005) associated with one or more working heads (200, 210) for working said sheet element (1), by means of a relative movement between said working heads (200, 210) and said sheet element (1); h) removing said sheet element (1) from the work zone (303) of said apparatus13. Method as in claim 12, wherein said positioning of said sheet element (11) in step c) occurs so as to optimize the number of said mobile rest means (306) and of said retractable holding means (500), the active surface of which completely impacts the sheet element (1 1) in a zone not affected by the working.

14. Method as in any claim from 12 to 13, wherein before the working step further retractable holding means (500’) comprised in the mobile rest members (306) comprised within the area to be worked are brought to a position of gripping of said sheet element and activated.

15. Method as in either claim 12 or 14, wherein after holding the sheet element (1) with the retractable holding members (500) and before starting the working, the lower rest means (304) are displaced to a position not interfering with the paths of the working heads (3041 ’).

16. Method as in any claim from 12 to 15, wherein sliding constraint members (2022, 2023) are brought to interact with said sheet element (1) during the working of the corresponding tool with which it is associated, and are brought into a condition of deactivation when said working is finished.

17. Method as in any claim from 12 to 16, wherein two of the working heads start the working from a common corner (11) of the sheet element (1) and finish the working on an opposing corner (Ij), following distinct and complementary paths.

18. Method as in any claim from 12 to 17, wherein at least some working comprises the displacement of the work tool in a direction (Z) orthogonal to the lying plane (re).

19. Method as in any claim from 12 to 18, comprising further steps of movement in the direction (X) of the sheet elements (1) before and / or after the working step.

Images