Apparatus for rounding the corners of glass sheets

Abstract

An apparatus for rounding at least one corner defined between two adjoining side edges of a glass sheet that is made to advance in a processing zone along a direction of advancement, which comprises at least one pair of separate tool units that are arranged side by side in fixed positions along the direction of advancement of the glass sheet. The aforesaid pair of tool units is movable in a substantially transverse direction with respect to the direction of advancement of the glass sheet. Thanks to the invention, rounding of the corners of the glass sheet is performed without the need to raise and lower the spindle of the tool unit in order to exchange the grinding tools and without having to move the tool unit along the direction of advancement of the glass sheet in order to perform circular interpolation for the corner rounding operation.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an apparatus for rounding the corners of glass sheets.

[0002] As is known, processing of the edges of a glass sheet traditionally provides for an initial step of removal of material, the so-called "grinding step", and a second finishing step, the so-called "polishing step". These processing steps are generally also applied in the so-called "rounding" of the corners of the glass sheet, i.e. the process through which the corners where two adjoining side edges of the glass sheet meet are rounded according to a circular profile.

[0003] An apparatus of the prior art for performing rounding of the corners of a glass sheet (patent No. EP 3 012 066 A1) uses a rounding tool unit with a spindle holding both the diamond grinding wheel and the polishing wheel. Although this configuration of the spindle has numerous advantages in terms of cost and overall dimensions of the corner rounding tool unit, it nonetheless requires axial movement of the spindle to be provided and managed during the corner rounding process to allow the exchange of the tools.

[0004] Furthermore, since the glass sheet is generally made to advance during the corner rounding process, in the apparatus of the prior art the corner rounding tool unit is mounted on a slide movable in a direction parallel to the direction of advancement of the glass sheet and performs the grinding and polishing steps sequentially, i.e. by "following" the glass sheet, meaning that the corner rounding tool unit moves along the axes of a Cartesian triple to follow the glass sheet, perform circular interpolation and axially move the spindle in order to engage the grinding wheel and the polishing wheel at the opportune moment.

[0005] In the known solutions described above, the problem that occurs is that, in order to allow time for travel of the corner rounding spindle, it is necessary for the travel of the slide holding the corner rounding tool unit to be sufficiently long, taking account of the speed of advancement of the glass sheet. However, since the distance between successive glass sheets to be processed must be the shortest possible in order to limit the dead times, an excessively long length of travel of the slide holding the corner rounding tool unit makes it necessary to keep the glass sheets greatly spaced apart from each other. Therefore, according to the prior art, in order to increase the speed of advancement of the glass sheets, it is necessary to lengthen the travel of the slide holding the corner rounding tool unit, with the consequence, however, that productivity is reduced, because the number of glass sheets processed per unit of time is reduced by the necessary distancing between them.

[0006] There is also a problem of minimum length of the glass sheet, which must be greater than the travel of the slide holding the corner rounding tool unit in order to allow the corner rounding process also to be performed on the tail corners of the glass sheet, in addition to the head ones, as it advances in the processing zone.

[0007] Publication No. EP 1 060 833 A1 describes a method for grinding and polishing the sides of a glass sheet.SUMMARY OF THE INVENTION

[0008] In order to resolve the problems mentioned here above, the object of the present invention is to provide an improved apparatus that allows the process of rounding the corners of a glass sheet to be performed in an operatively more convenient manner, without the need to raise and lower the spindle of the tool unit in order to exchange the grinding tools and without having to move the tool unit along the direction of advancement of the glass sheet in order to perform circular interpolation for the corner rounding operation.

[0009] More in particular, according to the present invention, this object is achieved with an apparatus for rounding at least one corner defined between two adjoining side edges of a glass sheet that is made to advance in a processing zone along a direction of advancement, characterised in accordance with claim 1.

[0010] According to the proposed solution underpinning the present invention, the problems mentioned here above, which are encountered in the conventional apparatus for performing rounding of the corners of a glass sheet, are overcome by providing for the structural and operational separation between the first and the second tool units, whereby the grinding tool and the polishing tool are installed respectively on separate spindles and each spindle is movable independently from the other in a transverse direction, but not necessarily perpendicular to the direction of advancement of the glass sheet in the processing zone.

[0011] In this manner, the drawback of having to provide and manage an axial movement of the spindle of the corner rounding tool unit during the rounding process, in order to allow exchange of the tools mounted on the same spindle, is overcome. The waste of time to exchange the tools is thus avoided and the control unit of the tool units is also simplified, because any axial adjustment of the spindles can be manual and, even if it were to be automated, it would still not be necessary to provide and manage axial movements of the spindles during the corner rounding process, since these movements would not be required during the work cycle.

[0012] Furthermore, by virtue of structural and operational separation between the tool unit with the spindle holding the grinding wheel and the tool unit with the spindle holding the polishing tool, these tool units do not need to "follow" the glass sheet as it advances in the processing zone. In fact, in order to perform the circular interpolation required for the corner rounding operation, it is sufficient to move each tool unit with the respective spindle only along an axis transverse to the direction of advancement of the glass sheet in the processing zone, since it is precisely the direction of advancement of the glass sheet that constitutes the second axis for circular interpolation. Compared to the apparatus of the prior art, which requires a lengthy travel of the slide on which the tool unit with the grinding and polishing spindle is mounted, in order to allow it to "follow" the glass sheet during the corner rounding process, the present invention allows an apparatus to be constructed that is not only more compact, but also more rigid, which improves the quality of processing.

[0013] Another advantage of the apparatus according to the invention relates to its higher productivity compared to the apparatus of the prior art. In the prior art, before starting the grinding of a new glass sheet, the tool unit with the grinding and polishing spindle must first have terminated the polishing of the current glass sheet and must be returned to the starting position, which is rearward with respect to the direction of advancement of the glass sheet. This makes it necessary to ensure an adequate distance between one glass sheet and the next one along the conveyor that moves the glass sheets in the processing zone. In the apparatus according to the invention, on the other hand, the structural and operational separation between the tool unit with the spindle holding the grinding wheel and the tool unit with the spindle holding the polishing tool allows the glass sheets to be kept closer to each other on the conveyor and, therefore, productivity of the processing to be recovered.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] These and further characteristics and advantages of the apparatus according to the present invention will become more apparent from the following detailed description of a preferred embodiment, illustrated by way of a non-limiting example in the appended drawings, wherein: Fig. 1 shows schematically the process of rounding a corner of a glass sheet performed with a conventional apparatus of the prior art, Fig. 2 is a perspective view of the apparatus according to the invention, Fig. 3 is a top view of the apparatus of Fig. 2, Fig. 4 is a partial perspective view of the apparatus of Fig. 2 showing the detail of the tool unit used for polishing the rounded corner of a glass sheet, and Fig. 5 shows schematically the rounding process steps performed with the apparatus of the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0015] The process of rounding a corner of a glass sheet performed with a traditional apparatus is illustrated schematically in Fig. 1, in which M denotes the spindle holding the diamond grinding wheel and the polishing wheel and P represents the circular profile created at a corner between two adjoining side edges of a quadrangular glass sheet L by means of a corner rounding process with the spindle M. In order to obtain corner rounding according to the profile P, the spindle M must first perform a forward travel F1 to perform grinding of the glass, and then must be lowered and raised in order to expose the polishing wheel on the glass, and then perform a backward travel F2 to the starting point in order to perform polishing of the glass.

[0016] In order to allow time for performance of travels F1 and F2 of the spindle M, it is necessary for the travel of the slide holding the corner rounding tool unit to be sufficiently long, taking account of the speed of advancement of the glass sheet. However, since the distance between successive glass sheets to be processed must be the shortest possible in order to limit the dead times, an excessively long length of travel of the slide holding the corner rounding tool unit makes it necessary to keep the glass sheets greatly spaced apart from each other. Therefore, according to the prior art, in order to increase the speed of advancement of the glass sheets, it is necessary to lengthen the travel of the slide holding the corner rounding tool unit, with the consequence, however, that productivity is reduced, because the number of glass sheets processed per unit of time is reduced by the necessary distancing between them.

[0017] There is also a problem of minimum length of the glass sheet, which must be greater than the travel of the slide holding the corner rounding tool unit in order to allow the corner rounding process also to be performed on the tail corners of the glass sheet, in addition to the head ones, as it advances in the processing zone.

[0018] The apparatus 1 of the invention, illustrated in Figures 2 to 4, is configured to be able to be installed on the support structure 2 of a machine of the conventional type for processing the edges of glass sheets, which includes a conveyor for moving a glass sheet L along a direction X in a processing zone.

[0019] The apparatus 1 comprises a first tool unit 3 with a spindle 5 holding a diamond tool, in particular a diamond grinding wheel, and a second tool unit 4 with a spindle 6 holding a polishing tool. The tool units 3 and 4 and the respective spindles 5 and 6 are arranged side by side, at a fixed distance from one another, along the direction X of advancement of the glass sheet L and are movable along the directions Y1 and Y2, respectively, which are transverse, but not necessarily perpendicular, to the direction X of advancement of the glass sheet L. The tool units 3 and 4 can provide for adjustment means 7 that allow to adjust the position thereof along a direction Z that is orthogonal to the directions X, Y1, and Y2.

[0020] For an illustration of operation of the apparatus 1 according to the invention, reference can be made to Fig. 5 of the drawings, which illustrates the steps of the corner rounding process performed on a corner S1 in which the two adjoining side edges A and B of a quadrangular glass sheet L that is made to advance in the direction X meet. Fig. 5(a) shows the start of the grinding step of the corner S1, Fig. 5(b) shows the end of the grinding step and the start of the polishing step of the corner S1, and, lastly, Fig. 5(c) shows the end of the polishing step of the corner S1. During the corner rounding operation, while the glass sheet L is made to advance along the direction X, the tool units 3, 4, with the corresponding spindles 5, 6, move in a programmed manner along the directions Y1 and Y2, respectively, transverse to the direction X. Subsequently to the rounding of the corner S1, the glass sheet is made to advance further along the direction X, as shown in Figs. 5(d)-(e), in order to position at the spindles 5, 6 of the tool units 3, 4 a successive corner S2 on which to perform rounding, which is arranged aligned with the corner S1 parallel to the direction X of advancement of the glass sheet L. Naturally, the processing steps described above can be performed simultaneously on the other corners S3 and S4 of the glass sheet L by another pair of tool units (not shown) identical to the tool units 3, 4 and arranged symmetrically with respect to them, with respect to the direction X of advancement of the glass sheet L.

[0021] It is clear from what is stated above that the invention allows the intended object to be achieved. In particular, the apparatus of the invention allows to perform the process of rounding the corners of a glass sheet with a reduced number of movements of the tool units and the respective spindles.

[0022] Although the invention has been described and illustrated in relation to a preferred embodiment thereof, it is clear that it is susceptible to numerous modifications and variants that are within the reach of a person skilled in the art and that are therefore within the scope of the appended claims.

Examples

Embodiment Construction

[0015]The process of rounding a corner of a glass sheet performed with a traditional apparatus is illustrated schematically in Fig. 1, in which M denotes the spindle holding the diamond grinding wheel and the polishing wheel and P represents the circular profile created at a corner between two adjoining side edges of a quadrangular glass sheet L by means of a corner rounding process with the spindle M. In order to obtain corner rounding according to the profile P, the spindle M must first perform a forward travel F1 to perform grinding of the glass, and then must be lowered and raised in order to expose the polishing wheel on the glass, and then perform a backward travel F2 to the starting point in order to perform polishing of the glass.

[0016]In order to allow time for performance of travels F1 and F2 of the spindle M, it is necessary for the travel of the slide holding the corner rounding tool unit to be sufficiently long, taking account of the speed of advancement of the glass sh...

BACKGROUND OF THE INVENTION

[0001] The present invention relates to an apparatus for rounding the corners of glass sheets.

[0002] As is known, processing of the edges of a glass sheet traditionally provides for an initial step of removal of material, the so-called "grinding step", and a second finishing step, the so-called "polishing step". These processing steps are generally also applied in the so-called "rounding" of the corners of the glass sheet, i.e. the process through which the corners where two adjoining side edges of the glass sheet meet are rounded according to a circular profile.

[0003] An apparatus of the prior art for performing rounding of the corners of a glass sheet (patent No. EP 3 012 066 A1) uses a rounding tool unit with a spindle holding both the diamond grinding wheel and the polishing wheel. Although this configuration of the spindle has numerous advantages in terms of cost and overall dimensions of the corner rounding tool unit, it nonetheless requires axial movement of the spindle to be provided and managed during the corner rounding process to allow the exchange of the tools.

[0004] Furthermore, since the glass sheet is generally made to advance during the corner rounding process, in the apparatus of the prior art the corner rounding tool unit is mounted on a slide movable in a direction parallel to the direction of advancement of the glass sheet and performs the grinding and polishing steps sequentially, i.e. by "following" the glass sheet, meaning that the corner rounding tool unit moves along the axes of a Cartesian triple to follow the glass sheet, perform circular interpolation and axially move the spindle in order to engage the grinding wheel and the polishing wheel at the opportune moment.

[0005] In the known solutions described above, the problem that occurs is that, in order to allow time for travel of the corner rounding spindle, it is necessary for the travel of the slide holding the corner rounding tool unit to be sufficiently long, taking account of the speed of advancement of the glass sheet. However, since the distance between successive glass sheets to be processed must be the shortest possible in order to limit the dead times, an excessively long length of travel of the slide holding the corner rounding tool unit makes it necessary to keep the glass sheets greatly spaced apart from each other. Therefore, according to the prior art, in order to increase the speed of advancement of the glass sheets, it is necessary to lengthen the travel of the slide holding the corner rounding tool unit, with the consequence, however, that productivity is reduced, because the number of glass sheets processed per unit of time is reduced by the necessary distancing between them.

[0006] There is also a problem of minimum length of the glass sheet, which must be greater than the travel of the slide holding the corner rounding tool unit in order to allow the corner rounding process also to be performed on the tail corners of the glass sheet, in addition to the head ones, as it advances in the processing zone.

[0007] Publication No. EP 1 060 833 A1 describes a method for grinding and polishing the sides of a glass sheet.SUMMARY OF THE INVENTION

[0008] In order to resolve the problems mentioned here above, the object of the present invention is to provide an improved apparatus that allows the process of rounding the corners of a glass sheet to be performed in an operatively more convenient manner, without the need to raise and lower the spindle of the tool unit in order to exchange the grinding tools and without having to move the tool unit along the direction of advancement of the glass sheet in order to perform circular interpolation for the corner rounding operation.

[0009] More in particular, according to the present invention, this object is achieved with an apparatus for rounding at least one corner defined between two adjoining side edges of a glass sheet that is made to advance in a processing zone along a direction of advancement, characterised in accordance with claim 1.

[0010] According to the proposed solution underpinning the present invention, the problems mentioned here above, which are encountered in the conventional apparatus for performing rounding of the corners of a glass sheet, are overcome by providing for the structural and operational separation between the first and the second tool units, whereby the grinding tool and the polishing tool are installed respectively on separate spindles and each spindle is movable independently from the other in a transverse direction, but not necessarily perpendicular to the direction of advancement of the glass sheet in the processing zone.

[0011] In this manner, the drawback of having to provide and manage an axial movement of the spindle of the corner rounding tool unit during the rounding process, in order to allow exchange of the tools mounted on the same spindle, is overcome. The waste of time to exchange the tools is thus avoided and the control unit of the tool units is also simplified, because any axial adjustment of the spindles can be manual and, even if it were to be automated, it would still not be necessary to provide and manage axial movements of the spindles during the corner rounding process, since these movements would not be required during the work cycle.

[0012] Furthermore, by virtue of structural and operational separation between the tool unit with the spindle holding the grinding wheel and the tool unit with the spindle holding the polishing tool, these tool units do not need to "follow" the glass sheet as it advances in the processing zone. In fact, in order to perform the circular interpolation required for the corner rounding operation, it is sufficient to move each tool unit with the respective spindle only along an axis transverse to the direction of advancement of the glass sheet in the processing zone, since it is precisely the direction of advancement of the glass sheet that constitutes the second axis for circular interpolation. Compared to the apparatus of the prior art, which requires a lengthy travel of the slide on which the tool unit with the grinding and polishing spindle is mounted, in order to allow it to "follow" the glass sheet during the corner rounding process, the present invention allows an apparatus to be constructed that is not only more compact, but also more rigid, which improves the quality of processing.

[0013] Another advantage of the apparatus according to the invention relates to its higher productivity compared to the apparatus of the prior art. In the prior art, before starting the grinding of a new glass sheet, the tool unit with the grinding and polishing spindle must first have terminated the polishing of the current glass sheet and must be returned to the starting position, which is rearward with respect to the direction of advancement of the glass sheet. This makes it necessary to ensure an adequate distance between one glass sheet and the next one along the conveyor that moves the glass sheets in the processing zone. In the apparatus according to the invention, on the other hand, the structural and operational separation between the tool unit with the spindle holding the grinding wheel and the tool unit with the spindle holding the polishing tool allows the glass sheets to be kept closer to each other on the conveyor and, therefore, productivity of the processing to be recovered.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] These and further characteristics and advantages of the apparatus according to the present invention will become more apparent from the following detailed description of a preferred embodiment, illustrated by way of a non-limiting example in the appended drawings, wherein: Fig. 1 shows schematically the process of rounding a corner of a glass sheet performed with a conventional apparatus of the prior art, Fig. 2 is a perspective view of the apparatus according to the invention, Fig. 3 is a top view of the apparatus of Fig. 2, Fig. 4 is a partial perspective view of the apparatus of Fig. 2 showing the detail of the tool unit used for polishing the rounded corner of a glass sheet, and Fig. 5 shows schematically the rounding process steps performed with the apparatus of the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0015] The process of rounding a corner of a glass sheet performed with a traditional apparatus is illustrated schematically in Fig. 1, in which M denotes the spindle holding the diamond grinding wheel and the polishing wheel and P represents the circular profile created at a corner between two adjoining side edges of a quadrangular glass sheet L by means of a corner rounding process with the spindle M. In order to obtain corner rounding according to the profile P, the spindle M must first perform a forward travel F1 to perform grinding of the glass, and then must be lowered and raised in order to expose the polishing wheel on the glass, and then perform a backward travel F2 to the starting point in order to perform polishing of the glass.

[0016] In order to allow time for performance of travels F1 and F2 of the spindle M, it is necessary for the travel of the slide holding the corner rounding tool unit to be sufficiently long, taking account of the speed of advancement of the glass sheet. However, since the distance between successive glass sheets to be processed must be the shortest possible in order to limit the dead times, an excessively long length of travel of the slide holding the corner rounding tool unit makes it necessary to keep the glass sheets greatly spaced apart from each other. Therefore, according to the prior art, in order to increase the speed of advancement of the glass sheets, it is necessary to lengthen the travel of the slide holding the corner rounding tool unit, with the consequence, however, that productivity is reduced, because the number of glass sheets processed per unit of time is reduced by the necessary distancing between them.

[0017] There is also a problem of minimum length of the glass sheet, which must be greater than the travel of the slide holding the corner rounding tool unit in order to allow the corner rounding process also to be performed on the tail corners of the glass sheet, in addition to the head ones, as it advances in the processing zone.

[0018] The apparatus 1 of the invention, illustrated in Figures 2 to 4, is configured to be able to be installed on the support structure 2 of a machine of the conventional type for processing the edges of glass sheets, which includes a conveyor for moving a glass sheet L along a direction X in a processing zone.

[0019] The apparatus 1 comprises a first tool unit 3 with a spindle 5 holding a diamond tool, in particular a diamond grinding wheel, and a second tool unit 4 with a spindle 6 holding a polishing tool. The tool units 3 and 4 and the respective spindles 5 and 6 are arranged side by side, at a fixed distance from one another, along the direction X of advancement of the glass sheet L and are movable along the directions Y1 and Y2, respectively, which are transverse, but not necessarily perpendicular, to the direction X of advancement of the glass sheet L. The tool units 3 and 4 can provide for adjustment means 7 that allow to adjust the position thereof along a direction Z that is orthogonal to the directions X, Y1, and Y2.

[0020] For an illustration of operation of the apparatus 1 according to the invention, reference can be made to Fig. 5 of the drawings, which illustrates the steps of the corner rounding process performed on a corner S1 in which the two adjoining side edges A and B of a quadrangular glass sheet L that is made to advance in the direction X meet. Fig. 5(a) shows the start of the grinding step of the corner S1, Fig. 5(b) shows the end of the grinding step and the start of the polishing step of the corner S1, and, lastly, Fig. 5(c) shows the end of the polishing step of the corner S1. During the corner rounding operation, while the glass sheet L is made to advance along the direction X, the tool units 3, 4, with the corresponding spindles 5, 6, move in a programmed manner along the directions Y1 and Y2, respectively, transverse to the direction X. Subsequently to the rounding of the corner S1, the glass sheet is made to advance further along the direction X, as shown in Figs. 5(d)-(e), in order to position at the spindles 5, 6 of the tool units 3, 4 a successive corner S2 on which to perform rounding, which is arranged aligned with the corner S1 parallel to the direction X of advancement of the glass sheet L. Naturally, the processing steps described above can be performed simultaneously on the other corners S3 and S4 of the glass sheet L by another pair of tool units (not shown) identical to the tool units 3, 4 and arranged symmetrically with respect to them, with respect to the direction X of advancement of the glass sheet L.

[0021] It is clear from what is stated above that the invention allows the intended object to be achieved. In particular, the apparatus of the invention allows to perform the process of rounding the corners of a glass sheet with a reduced number of movements of the tool units and the respective spindles.

[0022] Although the invention has been described and illustrated in relation to a preferred embodiment thereof, it is clear that it is susceptible to numerous modifications and variants that are within the reach of a person skilled in the art and that are therefore within the scope of the appended claims.

Examples

Embodiment Construction

[0015]The process of rounding a corner of a glass sheet performed with a traditional apparatus is illustrated schematically in Fig. 1, in which M denotes the spindle holding the diamond grinding wheel and the polishing wheel and P represents the circular profile created at a corner between two adjoining side edges of a quadrangular glass sheet L by means of a corner rounding process with the spindle M. In order to obtain corner rounding according to the profile P, the spindle M must first perform a forward travel F1 to perform grinding of the glass, and then must be lowered and raised in order to expose the polishing wheel on the glass, and then perform a backward travel F2 to the starting point in order to perform polishing of the glass.

[0016]In order to allow time for performance of travels F1 and F2 of the spindle M, it is necessary for the travel of the slide holding the corner rounding tool unit to be sufficiently long, taking account of the speed of advancement of the glass sh...

Claims

1. An apparatus (1) for rounding at least one corner defined between two adjoining side edges of a glass sheet (L) that is made to advance in a processing zone along a direction of advancement (X), characterised in that it comprises at least one pair of separate tool units (3, 4) that are arranged side by side in fixed positions along the direction of advancement (X) of said glass sheet (L) and are movable in a direction (Y1, Y2) substantially transverse with respect to the direction of advancement (X) of said glass sheet (L), wherein a first tool unit (3) of said pair of tool units (3, 4) is adapted to perform the grinding of the corner where said two adjoining side edges of said glass sheet (L) meet and a second tool unit (4) of said pair of tool units (3, 4) is adapted to perform the polishing of said corner where said two adjoining side edges of said glass sheet (L) meet, and wherein said first tool unit (3) is arranged upstream of said second tool unit (4) with respect to the direction of advancement (X) of said glass sheet (L) in the processing zone.

2. The apparatus according to claim 1, characterised in that said first tool unit (3) includes a spindle (5) holding a diamond tool, in particular a diamond grinding wheel, and said second tool unit (4) includes a spindle (6) holding a polishing tool.

3. The apparatus according to claim 1, characterised in that said tool units (3, 4) are movable in a direction (Y1, Y2) perpendicular or oblique with respect to the direction of advancement (X) of said glass sheet (L) in the processing zone.

4. The apparatus according to the preceding claims, characterised in that it comprises two pairs of identical tool units (3, 4) arranged so as to perform simultaneously the rounding process on a pair of corners of said glass sheet (L) arranged aligned along an axis perpendicular to the direction of advancement (X) of said glass sheet (L).

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