CUTTING MACHINE AND METHOD

Abstract

In a laser cutting machine for cutting a sheet of material, a laser scanner (12) is traversable in a lateral direction across a cutting surface (14). The laser scanner is controllable to direct a laser beam onto the cutting surface within a cutting area (A) of the cutting surface. A material-advancing mechanism is provided that is controllable to incrementally advance the sheet of material in a longitudinal direction over the cutting surface. In use, the material-advancing mechanism is controllable to position and hold stationary successive laterally- extending portions of the material in the cutting area. The laser scanner is controllable to cut each successive laterally-extending portion of the material held stationary in the cutting area before the material is advanced.

Claims

1. A laser cutting machine for cutting a sheet of material, comprising: a laser scanner traversable in a lateral direction across a cutting surface and controllable to direct a laser beam onto the cutting surface within a cutting area of the cutting surface; and a material-advancing mechanism controllable to incrementally advance the sheet of material in a longitudinal direction over the cutting surface; in which, in use, the material-advancing mechanism is controllable to position and hold stationary successive laterally-extending portions of the material in the cutting area and the laser scanner is controllable to cut each successive laterally-extending portion of the material held stationary in the cutting area before the material is advanced.

2. A laser cutting machine according to claim 1, wherein the cutting area is defined by a traversing direction of the laser scanner and by the laser scanner deflecting the laser beam laterally and longitudinally within the cutting area.

3. A laser cutting machine according to claim 1, wherein the material-advancing mechanism is controllable to incrementally advance the sheet of material, for cutting successive laterally-extending portions, through a distance less than a dimension of the cutting area in the longitudinal direction.

4. A laser cutting machine according to claim 1, controllable to cut the sheet of material according to a predetermined cutting pattern, wherein a dimension of the cutting pattern in the longitudinal direction is greater than a dimension of the cutting area in the longitudinal direction.

5. A laser cutting machine according to claim 1, comprising a reader for reading printed-matter printed onto the sheet of material, in which the printed matter is preferably selected from a printed cutting pattern, a registration mark or a printed image.

6. A laser cutting machine according to claim 5, wherein the reader is coupled to the laser scanner and is arranged to read a portion of the printed matter within a laterally-extending reading area.

7. A laser cutting machine according to claim 6, wherein the reading area is adjacent to the cutting area.

8. A laser cutting machine according to claim 6, wherein the reading area is positioned at least partially within the cutting area.

9. A laser cutting machine according to claim 6, wherein the reading area is the same as the cutting area.

10. A laser cutting machine according to claim 1, wherein the material advancing mechanism comprises a conveyor belt and wherein the cutting area is within an area of the sheet of material supported, in use, by the conveyor belt.

11. A laser cutting machine according to claim 6, wherein the material advancing mechanism comprises a conveyor belt and wherein the cutting area and the reading area are within an area of the sheet of material supported, in use, by the conveyor belt.

12. A laser cutting machine according to claim 10, comprising a vacuum mechanism for drawing the sheet of material into contact with the conveyor belt in the cutting area and, if present, the reading area.

13. A laser cutting machine according to claim 1, wherein the laser cutting machine comprises or is couplable to a printer for printing printed matter onto the sheet of material.

14. A laser cutting machine according to claim 13, in which the printer comprises a material-advancing mechanism for advancing the sheet of material through the same incremental advance distance as the laser cutting machine.

15. A laser cutting machine according to claim 13, in which the same material-advancing mechanism advances the sheet of material through the printer and the laser cutting machine.

16. A method for cutting a sheet of material comprising the steps of: incrementally advancing the sheet of material in a longitudinal direction such that successive laterally-extending portions of the sheet of material are positioned and held stationary at a predetermined cutting position within a laterally-extending cutting area; and traversing a laser scanner in a lateral direction to cut each laterally-extending portion of the material, while held stationary, by controlling the laser scanner to direct a laser beam within the cutting area in accordance with a cutting pattern; and repeating these steps to cut the successive laterally-extending portions of the material.

17. A method according to claim 16, wherein the laterally-extending portions of the sheet of material have a longitudinal dimension less than a longitudinal dimension of the cutting area.

18. A method according to claim 16, for cutting the sheet of material according to a predetermined cutting pattern, wherein a dimension of the cutting pattern in the longitudinal direction is greater than a dimension of the cutting area in the longitudinal direction.

19. A method according to claim 16, comprising a step of reading printed matter printed onto the sheet of material, in which the printed matter is preferably selected from a printed cutting pattern, a registration mark or a printed image.

20. A method according to claim 19, wherein the reader is coupled to the laser scanner and comprising the step of reading a portion of the printed matter printed on the laterally-extending portion of the sheet of material held stationary in the predetermined cutting position.

21. A method according to claim 19, wherein the reader is coupled to the laser scanner and comprising the step of reading a portion of the printed matter printed on a laterally-extending portion of the sheet of material adjacent to the laterally-extending portion of the sheet of material held stationary in the predetermined cutting position.

22. A method according to claim 16, wherein the material advancing mechanism comprises a conveyor belt and in which the sheet of material is supported by the conveyor belt during cutting.

23. A method according to claim 19, wherein the material advancing mechanism comprises a conveyor belt and in which the cutting area and the reading area are supported by the conveyor belt during reading and cutting.

24. A method according to claim 16, in which printed matter is printed on the sheet of material by a printer, and the sheet of material output by the printer advances directly to be cut as defined in claim 16.

25. A laser cutting machine according to claim 11, comprising a vacuum mechanism for drawing the sheet of material into contact with the conveyor belt in the cutting area and, if present, the reading area.

Description

DESCRIPTION OF SPECIFIC EMBODIMENTS AND BEST MODE OF THE INVENTION

[0046] Embodiments of the invention will now be described by way of example, with reference to the accompanying drawings in which:

[0047] FIG. 1 is a perspective view of a laser cutting machine according to a first embodiment of the invention;

[0048] FIG. 2 is a perspective view of the laser cutting machine of FIG. 1 illustrating the movement of a sheet of material through the laser cutting machine;

[0049] FIG. 3 is a cross section of the laser cutting machine according to the first embodiment of the invention;

[0050] FIG. 4 is a perspective view of a laser cutting machine according to a second embodiment of the invention;

[0051] FIG. 5 is a perspective view of a laser cutting machine according to a third embodiment of the invention;

[0052] FIG. 6 is a longitudinal section of the laser cutting machine of FIG. 5, on A-A;

[0053] FIG. 7 is a more detailed longitudinal section of the laser cutting machine of FIG. 5, on A-A;

[0054] FIG. 8 is a lateral section showing part of the laser cutting machine of FIG. 5, on B-B, namely the purge and vacuum system in the scanning area; and

[0055] FIG. 9 is a schematic diagram of a further embodiment of the invention, in which a laser cutting machine is integrated with a printing machine, or printer.

[0056] A laser cutting machine according to a first embodiment of the invention is shown in FIG. 1. It comprises a fixed support or gantry 10 on which a laser scanner 12 is traversably mounted. Beneath the gantry is a cutting surface 14 which comprises a metal mesh conveyor belt 22 for carrying a sheet of material for cutting. The traversably-mounted laser scanner is controllable to direct a laser beam from a fixed laser source 16 onto the cutting surface 14 within a cutting area A.

[0057] The laser scanner 12 is traversable in a lateral direction along the fixed gantry and is controllable to steer, or direct the laser beam in both lateral and longitudinal directions within a scanning area beneath the laser scanner. Lateral and longitudinal deflection of the laser beam by the laser scanner, in combination with the traversing of the laser scanner along the gantry, defines a long, thin rectangular cutting area A on the cutting surface 14.

[0058] The laser cutting machine of FIG. 1 also comprises a reader 18, which is fixed to and traversable with the laser scanner 12. The reader, which is an optical reader, or camera, therefore traverses in a lateral direction, parallel to the gantry 10. The reader is arranged to read within a reading area B of the cutting surface 14. In FIG. 1, the reading area B is the same size and shape as the cutting area A, and adjacent to and upstream from the cutting area A. The reading area partially overlaps the cutting area. In FIG. 1 the reading area B is demarcated by short dashed lines and the cutting area A is demarcated by long dashed lines.

[0059] The metal mesh conveyor belt 22 extends across the cutting area A and the reading area B for transporting a sheet of material, such as fabric, for reading and cutting. The top surface of the conveyor belt forms the cutting surface 14. Within the conveyor belt 22 and beneath the reading area B and the cutting area A of the cutting surface 14, a U-shaped channel 20 extends in a lateral direction and defines a vacuum chamber. A vacuum applied to the vacuum chamber can draw the sheet of fabric onto the conveyor belt across the entire areas of both the reading area B and the cutting area A.

[0060] The printed fabric (or other sheet material) is advanced through the laser cutting machine by the conveyor belt 22 which draws the fabric from a feed roller 24. Cut fabric is collected on a collection roller 26.

[0061] FIG. 2 shows the laser cutting machine of FIG. 1 with a roll of printed fabric 28 laid across the cutting surface. Virtual dotted lines on the fabric 28 (not printed on the fabric) show successive strips of fabric that will be read, incrementally advanced and then cut by the laser cutting machine. The reader 18 can read a cutting pattern printed on the roll of fabric 28. The cutting pattern can extend over several strips or increments. For example, in FIG. 2, the printed cutting pattern extends over 4 strips.

[0062] The conveyor belt 22 is controllable by a programmable controller (not shown), to position and hold stationary in the cutting area successive strips of the material. The reader is controllable by a programmable controller (not shown) to read a cutting pattern printed on a strip of the material while it is held stationary in the reading area before the material is advanced. A memory (not shown) stores the read cutting pattern of the strip of material that has been read by the reader. The laser scanner is controllable by a programmable controller (not shown), to cut each strip of the material, according to the cutting pattern printed on the strip of material while it is held stationary in the cutting area before the material is advanced. After a strip of the material has been cut, the material is advanced so that the next strip of the material is stationary in the cutting area and can be cut.

[0063] Although the embodiment is described with reference to controlling the cutting machine by reading and following a cutting pattern printed on the fabric, alternative approaches may be used as described above. These may include reading registration marks printed on the fabric and cutting a predetermined pattern aligned with the registration marks, or programming the cutting machine to cut predetermined patterns in register with printed images, for example to cut desired outlines around printed images.

[0064] When the printed sheet of material for cutting is placed on the cutting surface 14, the sheet of material is advanced to the position shown in FIG. 2 in which a first strip 1 of the material is held stationary in the reading area B and the printed cutting pattern in a the first strip 1 of the sheet of material is read. The reader stores the read printed cutting pattern (and/or the location of registration marks or printed images) in the first strip 1 in a data file in the memory. The sheet of material is then advanced, such that the first strip 1 of the sheet of material is held stationary in the cutting area A. The first strip 1 of the sheet of material is then cut in accordance with the read cutting pattern of the first strip 1, using the information on the first strip 1 stored by the reader in the data file. At the same time as the first strip 1 of the sheet of material is cut in cutting area A, a second strip 2 of the sheet of material is read in the reading area B by the reader traversing in unison with the laser scanner. After the first strip 1 has been cut in the cutting area A and the second strip 2 has been read in the reading area B, the conveyor belt advances the sheet of material, such that the second strip 2 is held stationary for cutting in cutting area A and a third strip 3 is held stationary for reading in the reading area B. The conveyor belt continues to incrementally advance the printed sheet of material through the laser cutting machine, in this manner.

[0065] When the material to be cut is on the conveyor belt, the vacuum 20 draws the material onto the conveyor belt over both the reading area B and the cutting area A. There is even suction from the vacuum across these two areas. The vacuum continues to draw the material onto the conveyor belt during reading of the material in the reading area, advancement of the material, and cutting of the material in the cutting area.

[0066] The distance through which the material moves in each incremental advancement is less than the width of the cutting area to ensure that all portions of the material can be cut. The width of each strip of material is equal to the distance through which the material moves in each incremental advancement.

[0067] In the laser cutting machine according to the first embodiment of the invention shown in FIGS. 1 and 2, the cutting of a strip of material in cutting area A is performed at the same time as the reading of an adjacent strip of material in cutting area B because the reader is moveable with the laser scanner which traverses along the gantry. In FIG. 1, the reader is positioned to read within the reading area B which is adjacent to or slightly overlapping the cutting area A. However, the reader could read a strip of material any distance ahead of the cutting area, or overlapping the cutting area. Preferably, the reading area B and the cutting area A have a sufficient degree of overlap such that each strip of material is centred in, and falls entirely within, the reading area when the strip of material is being read, and within the cutting area when it is being cut.

[0068] FIG. 3 shows a cross section of the cutting machine of FIG. 2. The material to be cut is provided on a feed roller 24, and is transported through the laser cutting machine by the conveyor belt 22. The material to be cut is drawn onto the conveyor belt by the vacuum 20 which is positioned below both the reading area and the cutting area. Once cut, the material is collected on a collection roller 26.

[0069] A laser cutting machine according to a second embodiment of the invention is shown in FIG. 4. The arrangement of the fixed gantry 10, laser scanner 12, reader 18 and laser source 16 is the same as described in relation to the first embodiment shown in FIGS. 1, 2, and 3. Beneath the gantry is a cutting table 32 which comprises a short conveyor belt 30 positioned within an opening in the cutting table. The short conveyor belt 30 covers the cutting area A and the reading area B and has a vacuum chamber (not shown) extending across both the cutting area A and the reading area B.

[0070] A material to be cut is provided on the feed roller 24. The material may be considered as being divided into virtual, successive, laterally-extending portions that will be read, advanced and then cut, as described in relation to FIG. 2. When the material to be cut is positioned on the cutting table 32, the material is incrementally advanced by the conveyor belt 30. The conveyor belt is controllable by a programmable controller (not shown), to position and hold stationary in the cutting area successive strips of the material. As the material is advanced by the conveyor belt according to the second embodiment of the invention, it is drawn from the feed roller 24, over a first stationary part of the cutting table 32(a) and onto the conveyor belt 30. The material is drawn onto the conveyor belt by a vacuum (not shown) which extends under the width of the top surface of the conveyor belt. The vacuum holds down the material whilst a printed cutting pattern on a strip of the material to be cut is read by the reader in the reading area B, incrementally advanced by the conveyor belt and then cut by the laser scanner in the cutting area A. The conveyor belt can therefore be the same size as the reading area B and the cutting area A. Once the same strip of the material is cut, the conveyor belt transports the cut strip of material such that it comes off the conveyor belt onto a second stationary part of the cutting table 32(b), where it can be collected on the collection roller 26.

[0071] In FIGS. 1 to 4, the reader is fixed upstream of the laser scanner to read within the reading area B which is adjacent to, and slightly overlapping the cutting area A. In an alternative embodiment of the invention (not shown), the reader is fixed alongside the laser scanner such that the reading area is the same as, or contains, the cutting area A. This could then operate by reading the printed pattern in a strip in a first traverse of the laser scanner/reader and then cutting the same strip, without advancing the material, in a second traverse of the laser scanner/reader. Alternatively, the printed pattern in the strip may be read immediately ahead of the traversing laser scanner so that the material can be cut immediately after reading, in a single traverse.

[0072] In a further embodiment of the invention, illustrated in FIG. 9, the laser cutting machine of FIGS. 1 to 4 is combined with a printer 50. The printed material 52 may exit directly from the printer, in the direction of the arrow in the Figure, onto the conveyor belt of the laser cutting machine to be read and then cut. The cutting machine and the printer may be controlled by a common programmable controller 54. Modern printers typically advance sheets of material incrementally. It is therefore possible to synchronise and match the rates of the incremental advancement of the fabric exiting the printer with the incremental advancement of the conveyor belt of the laser cutting machine. A desired quantity of slack material, as shown at 52 in FIG. 9, may be provided to accommodate any intermittent differences in the material feed rates of the printer and the cutting machine, and appropriate feedback provided to ensure that the feed rates remain synchronised.

[0073] In one embodiment, the printer and the cutting machine may advance the material in different incremental distances. In such cases, the frequency with which the material is incrementally advanced by each machine may be adjusted to produce the same average rate of material advance.

[0074] In addition, in preferred embodiments, the same data files, or versions of the same data files having different resolutions or different colour information, may be used to control the printer and the cutting machine. The cutting machine may require data files with lower resolution than the printer, and with no colour information unless the reader of the cutting machine requires colour information in order to recognise images or patterns printed by the printer.

[0075] FIGS. 5 to 8 illustrate a third embodiment of a cutting machine embodying the invention. In the third embodiment, all of the structure of the first embodiment, of FIGS. 1 to 3, is retained and the same reference numerals are used in FIGS. 5 to 8. In the third embodiment, an additional purge gas and vacuum system is added to the first embodiment.

[0076] The purge gas and vacuum system comprises a purge gas hood 60 positioned below the laser scanner 12 and above the fabric, or sheet of material, 14. The hood is traversably mounted on a support beam 62 of the gantry 10, for movement parallel to the traversing movement of the laser scanner. A flexible air-supply tube 64 feeds air to an inlet of the hood during cutting, to ensure that the laser cuts the fabric cleanly. A flexible vacuum tube 66 is coupled to a vacuum pump (not shown) and withdraws air, and fumes from the laser cutting, from an outlet 68 of the hood.

[0077] The purge gas and vacuum system further comprises a vacuum plenum 70 arranged below the conveyor belt 14, within the vacuum chamber 20. The plenum is traversably mounted on a support beam 72 extending within the vacuum chamber, for movement parallel to the traversing movement of the laser scanner, A flexible vacuum tube 74 is coupled to a vacuum pump (not shown) and withdraws air (and any fumes) from an outlet 76 of the vacuum plenum.

[0078] The hood has a downwardly-facing opening, surrounding a scanning area in which the laser scanner can control the movement of the laser beam during cutting. The plenum has an upwardly-facing opening covering substantially the same area as the opening of the hood. The conveyor belt and the fabric, or sheet of material, carried by the conveyor belt pass between the downwardly-facing opening of the hood and the upwardly-facing opening of the plenum.

[0079] The vacuum applied to the plenum may be stronger than the vacuum applied to the hood, so that the vacuum applied by the plenum draws the fabric into contact with the conveyor belt, and holds it there during cutting.

[0080] The hood and the plenum are linked by a cable 80 passing around pulleys 82 so that the hood and the plenum always move together, and the hood remains above the plenum at all times. Movement of the hood and the plenum can then be controlled by a drive mechanism so that the hood remains below and aligned with the laser scanner at all times as the laser scanner traverses, and the plenum remains below the hood.

[0081] The vacuum applied to the hood and the plenum advantageously withdraws any fumes generated by laser cutting. The localisation of the hood and the plenum in the scanning area advantageously minimises the volume of fume-laden air withdrawn during cutting, which simplifies the filtering and cleaning of the air.

[0082] In the embodiment, a vacuum is additionally applied to the vacuum chamber 20 to hold the fabric (or other material) in contact with the conveyor belt across the entire cutting area and reading area. This may advantageously optimise the accuracy with which the conveyor belt advances the fabric and holds it during reading and cutting. However, in alternative embodiments it may be possible to reduce the size of the vacuum chamber. This may be desirable in order to reduce the volume of air to be drawn through the vacuum system, and therefore to reduce the energy consumption of the cutting machine. It may even be possible to or even to eliminate the vacuum chamber completely.

[0083] One such modification may be applied to any of the embodiments of the invention described herein. In this modification, in which the traversable hood and/or vacuum plenum may or may not be present, the size of the vacuum chamber is reduced so that it extends only to cover the cutting area of the cutting machine, and not the reading area. This approximately halves the area of fabric to which the vacuum is applied, and may correspondingly halve the flow rate of air required to maintain the vacuum, and so approximately halve the energy consumption. This may be appropriate as long as any loss in accuracy of positioning the fabric is acceptable. For example, this may be acceptable unless the fabric is deformable or elastic.

[0084] An alternative modification may be applied to the third embodiment described herein, and illustrated in FIGS. 5 to 8. In this modification, the vacuum chamber may be removed completely. The hood and the vacuum plenum in the scanning area are retained, and only the vacuum applied to the vacuum plenum is used to hold the fabric in contact with the conveyor belt. This may involve a loss in accuracy in the advancement of the fabric into the reading area and from the reading area to the cutting area, but may advantageously ensure that the fabric is securely held in the scanning area as it is being cut. This may be acceptable for fabrics or other materials that are not deformable or elastic, or which can otherwise be advanced accurately.