GB2522884A

GB2522884A - Support surface for a cutting machine

Info

Publication number: GB2522884A
Application number: GB1402144.8A
Authority: GB
Inventors: Leslie White; Alexander White; John White
Original assignee: Blackman & White Ltd
Current assignee: Blackman & White Ltd
Priority date: 2014-02-07
Filing date: 2014-02-07
Publication date: 2015-08-12
Anticipated expiration: 2034-02-07
Also published as: GB2522884B; GB201402144D0

Abstract

The present invention relates to support surfaces of cutting machines, to cutting machines including a support surface and to a method of installing a support surface on a cutting machine. The present invention further relates to a support surface in the form of a conveyor belt. A support surface 16 of a cutting machine comprises a sheet of layered material 18, this layered material comprises a flexible support layer 24 made from a ceramic or polymer material and a metal foil layer 26. There are plurality of holes (28 fig.3) formed through the metal foil layer. The metal foil layer can comprise of aluminum and the support layer can comprise glass fibers. The two layers can be bonded together using an adhesive and the total thickness of the layered material can be less than 1mm. the two end edges 22 can be joined together via engagement means 30 to make an endless loop. This engagement means can be a complementary hook means 32, 34. The holes in the foil layer and the typically permeable nature of the polymer layer allow the surface to be used with a vacuum means for holding the workpiece to be cut.

Description

Support Surface for a Cutting Machine

BACKGROUND

a. Field of the Invention

The present invention relates to support surfaces of cutting machines, to cutting machines including a support surface and to a method of installing a support surface on a cutting machine. The present invention further relates to a support surface in the form of a conveyor belt.

b. Related Art A variety of cutting machines are known to cut and shape a wide range of different materials including plastics sheets, foams, fabrics, composite materials and other sheet materials. These machines typically include one or more cutting tools and the choice of which cutting tool is used is, typically, dependent on both the material and shape being cut. Two primary types of cutting machine are knife cutting machines and laser cutting machines.

In these machines the material to be cut, or workpiece, is placed onto a horizontal support bed or table. The workpiece is held in position by means of suction through the support bed provided by a vacuum system. The cutting tool is mounted on a gantry above the support bed and is able to move along x, y and z axes relative to the workpiece in order to cut the required shape. Movement of the cutting tool is controlled by means of appropriate software that has been pre-programmed with the desired cutting plan.

Knife cutting machines can include a number of different knife cutting tools, including both fixed and driven blades. Depending on the application it may be desirable to use a stationary blade, a reciprocating or oscillating blade, a rotary blade similar to a pizza cutter, or a router. Furthermore, as the desire to provide more flexible cutting solutions increases, machines have been developed that can incorporate more than one type of knife cutting tool, or in which the cutting tools are interchangable.

There are also some machines that have been developed in which both knife cutting tools and laser cutting tools may be used interchangeably. However, a difficulty arises because the support bed required for these two types of cutting processes are significantly different.

In knife cutting machines, the workpiece is laid on a sacrificial bed or support layer typically made from a felt material. As the blade cuts through the material, the end of the blade contacts and cuts into the underlying felt support layer. In contrast, in laser cutting machines, the workpiece is laid onto a metallic support layer that minimises back reflections of the laser light that passes through the workpiece. In both cases the support layer must be permeable to air to enable the vacuum suction to be established. In machines in which knife and laser cutting tools are interchangeable, therefore, it is necessary to also change the support layer when the cutting tools are changed.

Another consideration in both knife cutting and laser cutting machines is how the workpieces are loaded into and removed from the cutting machine. In order to increase productivity it is desirable to minimise the shut down time of the cutting machine between workpieces, i.e. to minimise the time taken to replace the workpiece on the support bed. Accordingly, a number of systems have been developed which allow almost continuous use of the cutting machine. Some knife cutting machines, for example, incorporate a conveyor belt that assists in the removal of workpieces from and the placement of workpieces onto the main support bed of the machine. Another solution in some laser cutting machines is to separate the support bed into two independent halves such that, whilst cutting is underway in a first half, the workpiece can be replaced in the second half.

The separation of the support bed into two halves in laser cutting machines, however, limits the available surface area for a single workpiece. It would be desirable, therefore, to be able to use a conveyor belt system in laser cutting machines. However, it has typically been difficult to form a metal conveyor belt that provides the necessary support for the workpiece, is flexible enough to pass around the conveyor rollers and allows operation of the vacuum suction system.

A number of solutions to this problem have been proposed. The first involves the use of a metal chain-mail type structure and the second comprises a series of linked metal slats or bars forming a track-like belt. Both of these structures are flexible enough to pass around the rollers of the conveyor system and both provide the necessary air holes for the vacuum suction, either between the links of the chain-mail or between the individual slats or bars. However, both of these systems have the disadvantage that the resultant metal belts are very heavy.

If these belts are used on a multi-purpose machine, i.e. one that can utilise both knife cutting and laser cutting tools, the users of the machine are required to handle the entire length of the belt to install it in the machine when the laser tool is to be used. This often requires several people to be able to lift, manipulate and secure the belt in position. Furthermore, the installation of the belt takes a significant length of time. Similarly, significant manpower and time is required to remove the belt from the machine and, additionally, the belt must then be stored somewhere until it is next required.

It is an object of the present invention to provide an improved support surface for use with a laser cutting tool that overcomes the above mentioned problems.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a support surface of a cutting machine, the support surface comprising a sheet of layered material, and the layered material comprising: -a flexible, support layer made from a ceramic or polymer material; and -a metal foil layer, a plurality of holes being formed through the metal foil layer.

The thickness of the metal foil layer is preferably less than 200 pm, and is more preferably between 5 pm and 50 pm.

In preferred embodiments the metal foil layer comprises aluminium. The support layer may comprise glass fibres. Typically the metal foil layer is bonded to the support layer by an adhesive.

The thickness of the layered material is preferably less than 1 mm such that the support surface is flexible and is relatively lightweight.

Preferably the holes are formed in an array over the full surface of the metal foil layer.

The support surface preferably further comprises a band of edging material extending along at least two opposing edges of the layered material, the edging material being impermeable to air. In some embodiments the band of edging material extends fully around all of the edges of the layered material.

In some embodiments the support surface forms a conveyor belt of the cutting machine. In these embodiments the layered material has two longer side edges and two shorter end edges, the two end edges comprising engagement means such that the two end edges can be connected together to form a continuous loop of material.

The engagement means are preferably such that they can be repeatedly engaged and disengaged to enable the conveyor belt to be installed on and removed from the cutting machine respectively. Preferably the engagement means comprise complementary hook means. In preferred embodiments each of the hook means comprises a strip of relatively rigid plastics material that is attached to a respective end edge of the layered material.

According to a second aspect of the present invention there is provided a cutting machine including a support surface according to the first aspect of the invention.

According to a third aspect of the present invention there is provided a conveyor belt for a laser cutting machine, the conveyor belt comprising an elongate sheet of layered material having two longer side edges and two shorter end edges, the two end edges comprising engagement means such that the two end edges can be connected together to form a continuous loop of material, and the layered material comprising: -a flexible, support layer made from a ceramic or polymer material; and -a metal foil layer, a plurality of holes being formed through the metal foil layer.

According to a fourth aspect of the present invention there is provided a cutting machine including a conveyor belt according to the third aspect of the invention.

According to a fifth aspect of the present invention there is provided a method of installing a support surface on a cutting machine, the cutting machine comprising a felt belt supported on rollers, the support surface being in the form of a conveyor belt in which the layered material has two end edges comprising engagement means such that the two end edges can be connected together to form a continuous loop of material, and the method comprising the steps of: -attaching a first end edge of the support surface to the felt belt; -advancing the cutting machine such that the conveyor belt is drawn around said rollers; and -joining the end edges of the support surface together by connecting the engagement means to form a continuous loop of material.

Preferably the method further includes, after joining the end edges together, covering said join with tape having a metal foil surface layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be further described by way of example only and with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a cutting machine on which a support surface of the present invention in the form of a conveyor belt may be installed; Figure 2 is a longitudinal cross-section through a support surface according to a preferred embodiment of the present invention; Figure 3 is a top view of the support surface of Figure 2; and Figure 4 is a perspective view of part of a join of the support surface of Figure 2.

DETAILED DESCRIPTION

Figure 1 shows a cutting machine 1 including a support surface 2 and a gantry 4 on which is mounted a cutting head 6, including both a knife cutting tool 8 and a laser cutting tool 10. The cutting machine 1 further comprises control means 12 for controlling the movement of the cutting head 6 over the support surface 2.

Specifically, the gantry 4 is movable in a first direction along the length of the support surface 2, and the cutting head 6 is moveable in a second direction along the gantry 4, the second direction being perpendicular to the first direction. This enables any two dimensional shape to be cut from material placed on the support surface 2.

The support surface 2 comprises a continuous belt of material 14 supported on rollers (not shown). Typically this belt 14 will be made of a felt material as is known in the art. When the knife cutting tool 8 is used] a tip of a blade will contact or cut into this felt belt 14 and, accordingly the felt belt 14 is sacrificial.

Workpieces (not shown), comprising material to be cut, are held flat on the support surface 2 by means of a vacuum system (not shown) that draws air down through the material of the support surface 2, thereby drawing the workpiece down onto the support surface 2 by suction. When a felt belt 14 is used, the open structure of the felt material means that air can easily be drawn through the material, creating even suction over the support surface 2.

Figures 2 to 4 show a support or cutting surface 15 in the form of a conveyor belt 16 according to a first embodiment of the present invention. The conveyor belt 16 is designed to be installed on the cutting machine 1 described above to enable the laser cutting tool 10 to be used. As described further below, the conveyor belt 16 can be easily installed on the machine 1 without needing to remove the felt belt 14 or to make any other modifications to the cutting machine 1.

The conveyor belt 16 comprises an elongate sheet 18 of laminated or layered material. The sheet 18 has two longer side edges 20 and two shorter end edges 22. The layered material comprises a flexible support layer 24 and a metal foil layer 26. To form the conveyor belt 16, the sheet is formed into a loop with the metal foil layer 26 on a radially outer surface.

Installing the conveyor belt 16 on the cutting machine 1 enables the laser cutting head 10 to be used because the laser light is reflected by the metal foil layer 26.

This means that the cutting machine 1 can be easily changed between knife cutting operations and laser cutting operations by simply installing or removing the conveyor belt 16 as required.

The sheet 18, and therefore the conveyor belt 16, preferably has a thickness of about 1 mm, but may have a thickness of between 0.7 mm and 1.2 mm. This means that the conveyor belt 16 is lightweight and flexible allowing it to be easily manipulated by a user. Additionally, its thinness and flexibility enables it to be installed around the existing rollers of the cutting machine 1, such that the existing tensioning and alignment systems can be used.

The metal foil layer 26 may be made from any suitable metal that has high reflectivity in the frequency range of the laser cutting tool 10. In preferred embodiments the metal foil layer comprises aluminium. The metal foil layer 26 preferably has a thickness of less than 200 pm. More preferably the metal foil layer 26 has a thickness of less than 100 pm. Most preferably the metal foil layer 26 has a thickness of between 5 pm and 50 pm.

The support layer 24 is made from a ceramic or polymer material, and in a preferred embodiment is made from a glass cloth material comprising glass fibres.

A glass fibre fabric forming the support layer 24 may be impregnated with a polyurethane to prevent fraying of the fabric. In other embodiments the support layer 24 may be made from polyimide or polyester.

In one particularly preferred embodiment the sheet 18 has a thickness of 0.8 mm, and the metal foil layer has a thickness of 20 pm.

The metal foil layer 26 is adhered to the support layer 24 using a suitable adhesive. In preferred embodiments the adhesive is a silicone adhesive which is able to withstand temperatures up to about 250 °G. This reduces the possibility of the metal foil layer 26 cracking or delaminating from the support layer 24 during use.

In order to permit airflow through the conveyor belt 16, to enable proper operation of the vacuum system described above: it is necessary to form a plurality of holes 28 through the metal foil layer 26. Preferably the holes 28 have a diameter of about 0.1 mm to 0.2 mm. Typically an even distribution of holes 28 is formed over the foil layer 26 to provide even suction over the surface of the conveyor belt 16.

In a preferred embodiment the holes 28 are formed in a square array, with a distance between holes being approximately 20 mm. The holes 28 are preferably formed by one or more needles that puncture the foil layer 26.

At each end edge 22 of the sheet 18 there is provided engagement means 30 for connecting the two end edges 22 together so as to form a continuous loop of material. The engagement means 30 are configured to enable the ends 22 of the conveyor belt 16 to be repeatedly connected together and pulled apart, to permit the conveyor belt 16 to be installed on and removed from the cutting machine 1, as described further below.

In this embodiment the engagement means 30 comprise complementary hook means 32, 34 secured to each of the end edges 22. One of the hook means 34 is attached to the metal foil layer 26 and the other one of the hook means 32 is attached to the support layer 24. In this way, as shown most clearly in Figures 2 and 4, when the hook means 32, 34 are engaged, end portions 36 of the sheet 18 overlap thereby resulting in a continuous loop of material. The hook means 32, 34 comprise elongate strips 38 of plastics material having opposing longer edges 40, extending along a length of the strip 38, and opposing shorter edges 42, extending across a width of the strip 38. The strips 38 are secured across the full width of the conveyor belt 16 such that the longer edges 40 are parallel to a respective end edge 22 of the sheet 18. The strips 38 of plastics material are only secured to the sheet 18 over a part of their width such that an unsecured part of the strip 38 forms a flap or hook portion 44. The secured part of the strip 38 is the part of the strip 38 closest to the respective end edge 22 of the sheet 18 such that the flap 44 extends in a direction away from the end edge 22. In this way, when the sheet 18 is formed into a loop and the end portions 36 are brought together, the opposing flaps 44 can be interlocked.

The strips 38 of plastics material are secured to the support layer 24 and metal foil layer 26 of the sheet 18 by stitching. In other embodiments, however, the strips 38 may be secured using any suitable means. Furthermore, the engagement means may be of any suitable configuration to enable the end portions 36 of the sheet 18 to be secured together to form a continuous loop. Preferably the engagement means 30 are configured such that end portions 36 of the sheet 18 overlap when the engagement means 30 are interlocked.

Bands of edging material 48 are provided along each of the long edges 20 of the sheet 18 and extend along the full length of the sheet 18. The edging material is impervious to air, and in a preferred embodiment the bands of edging material 48 are made from poly(vinyl chloride) (PVC). Because the sheet 18 is relatively thin and flexible, it is difficult to achieve a flat surface when the conveyor belt 16 is initially installed on the cutting machine 1. In particular, there is a tendency for the long edges 20 of the conveyor belt 16 to wrinkle, which means that the belt 16 cannot pass smoothly through the machine 1. By including edging bands 48 that are impervious to air, when the conveyor belt 16 is installed on the cutting machine 1, these edging bands 48 are pulled down flat against the felt belt 14 by means of the vacuum suction system. This, in turn, causes the rest of the conveyor belt 16 above the suction system to be flattened as the edges 20 of the conveyor belt 16 are sealed and air is drawn through the support layer 24 and metal foil layer 26 of the conveyor belt 16.

To install the conveyor belt 16 on the cutting machine 1 one of the end edges 22 is secured to the felt belt 14 with the support layer 24 in contact with the surface of the felt belt 14. The sheet 18 is secured such that the end edge 22 extends across a width of the felt belt 14. The end edge 22 will typically be secured to the felt belt 14 using adhesive tape.

The rollers of the cutting machine 1 are then advanced to draw the felt belt 14 and also the end of the sheet 18 around and through the rollers. Once the sheet 18 has been drawn around by the rollers, the tape securing the end edge 22 to the felt belt 14 may be removed. The second end 22 of the sheet 18 can then be secured to the first end 22 using the engagement means 30. In this embodiment, the flap 44 of the hook means 32 at the second end 22 of the sheet 18 is hooked under the flap 44 of the hook means 34 at the first end 22. In this way, the flap 44 of the hook means 32 is positioned between the flap 44 of the hook means 34 and the metal foil layer 26. This is shown most clearly in Figures 2 and 4.

A length of metallised tape 50 is then secured over the uppermost end edge 22 to seal the join in the conveyor belt 16. The tape 50 preferably comprises an upper surface layer of aluminium foil.

It has been found that, because the engagement means 30 extend parallel to the end edges 22 across substantially the full width of the conveyor belt 16, running the conveyor belt 16 through the cutting machine 1 a few times automatically aligns the conveyor belt 16 correctly. This is also aided by the shape of the rollers, which are typically crowned.

The cutting machine 1 can then be operated as usual with the workpieces being laid directly onto the metal foil layer 26 of the conveyor belt 16. These workpieces can be cut using the laser cutting tool in the usual way, with little or no adverse effect on the underlying conveyor belt 16.

To remove the conveyor belt 16 for the cutting machine 1, the length of tape 50 is removed and the engagement means 30 disengaged from each other. The conveyor belt 16 can then be drawn out from around the rollers of the machine 1 and stored until the next time it is required. Because the conveyor belt 16 is relatively lightweight and flexible, it can be easily rolled up and stored in a suitable location, which may be remote from the cutting machine 1.

It will be appreciated that the sheet of layered material described above may also be used as a support or cutting surface in a static or flatbed cutting machine. In these cutting machines the support bed on which the workpieces are placed is stationary.

The support bed of a flatbed cutting machine typically comprises a metal base layer or table covered by a felt mat. The base table will generally include an aluminium upper surface on which the felt mat is seated. When a knife cutting tool is being used, a tip of a blade will contact or cut into this felt mat as described above in relation to the felt belt. When it is desired to use a laser cutting tool, the felt mat is removed and the workpiece is laid directly onto the surface of the metal table. The disadvantage of this is that the felt mat is relatively heavy and, due to its thickness, is generally unable to be folded or rolled for storage.

In these situations, therefore, it is advantageous to utilise a support surface comprising a sheet of layered material according to the present invention to enable the laser cutting tool to be used without needing to remove the felt mat.

In these embodiments, when it is desired to use the laser cutting tool, a sheet of layered material cut to the size of the support bed is laid on top of the felt mat, with the metal foil layer uppermost.

When the knife cutting tool is to be used, the support layer is simply removed from the cutting machine exposing the felt mat. Because the support layer is relatively lightweight and flexible, it can be easily rolled up and stored in a suitable location, which may be remote from the cutting machine.

As described above, because the sheet of layered material is relatively thin and flexible, it may be difficult to achieve a flat surface when the support surface is installed on the cutting machine. In particular, there may be a tendency for longer edges of the support surface to wrinkle. In preferred embodiments, therefore, bands of edging material are provided along edges of the sheet. The edging material is impervious to air, and in a preferred embodiment the bands of edging material are made from poly(vinyl chloride) (PVC). The inclusion of edging bands that are impervious to air means that, when the support surface is installed on the cutting machine, these edging bands are pulled down flat against the felt mat by the vacuum suction system. This, in turn, causes the rest of the support surface to be flattened because the edges of the sheet are sealed and air is drawn through the support layer and metal foil layer of the support surface.

In some embodiments the bands of edging material are provided only along two opposing edges of the sheet of layered material. Preferably the bands of edging material are provided along two longer edges of the support layer. In other embodiments the bands of edging material are provided fully around all of the edges of the sheet of layered material, to form an uninterrupted sealing edge.

Although in these embodiments the layered sheet has been described as comprising a single support layer and a single metal foil layer, it will be appreciated that in other embodiments the sheet may be made from a multilayer material having a plurality of support layers and a plurality of metal foil layers. The material may comprise, for example, between 5 and 30 layers.

The present invention, therefore, provides an improved support surface for use with a laser cutting tool, and a cutting machine including such a support surface, that overcome many of the problems associated with prior art devices.

Claims

CLAIM S1. A support surface of a cutting machine, the support surface comprising a sheet of layered material, and the layered material comprising: -a flexible, support layer made from a ceramic or polymer material; and -a metal foil layer, a plurality of holes being formed through the metal foil layer.
2. A support surface as claimed in Claim 1, wherein the thickness of the metal foil layer is less than 200 pm.
3. A support surface as claimed in Claim 1 or Claim 2, wherein the thickness of the foil layer is between 5 pm and 50 pm.
4. A support surface as claimed in any preceding claim, wherein the metal foil layer comprises aluminium.
5. A support surface as claimed in any preceding claim, wherein the support layer comprises glass fibres.
6. A support surface as claimed in any preceding claim, wherein the metal foil layer is bonded to the support layer by an adhesive.
7. A support surface as claimed in any preceding claim, wherein the thickness of the layered material is less than 1 mm.
8. A support surface as claimed in any preceding claim, wherein the holes are formed in an array over the full surface of the metal foil layer.
9. A support surface as claimed in any preceding claim, the support surface further comprising a band of edging material extending along at least two opposing edges of the layered material, the edging material being impermeable to air.
10. A support surface as claimed in Claim 9, wherein a band of edging material extends fully around all of the edges of the layered material.
11. A support surface as claimed in any of Claims 1 to 9, wherein the layered material has two longer side edges and two shorter end edges, the two end edges comprising engagement means such that the two end edges can be connected together to form a continuous loop of material, and wherein the support surface forms a conveyor belt of the cutting machine.
12. A support surface as claimed in Claim 11, wherein the engagement means comprise complementary hook means.
13. A support surface as claimed in Claim 12, wherein each of the hook means comprises a strip of relatively rigid plastics material that is attached to a respective end edge of the layered material.
14. A cutting machine including a support surface as claimed in any of Claims 1 to 13.
15. A conveyor belt for a cutting machine, the conveyor belt comprising an elongate sheet of layered material having two longer side edges and two shorter end edges, the two end edges comprising engagement means such that the two end edges can be connected together to form a continuous loop of material, and the layered material comprising: -a flexible, support layer made from a ceramic or polymer material; and -a metal foil layer, a plurality of holes being formed through the metal foil layer.
16. A cutting machine including a conveyor belt as claimed in Claim 15.
17. A method of installing a support surface on a cutting machine, the cutting machine comprising a felt belt supported on rollers, the support surface being according to any one of Claims 11 to 13, and the method comprising the steps of: -attaching a first end edge of the support surface to the felt belt; -advancing the cutting machine such that the support surface is drawn around said rollers; and -joining the end edges of the support surface together by connecting the engagement means to form a continuous loop of material.
18. A method as claimed in Claim 17, wherein the method further includes, after joining the end edges together, covering said join with tape having a metal foil surface layer.
19. A support surface substantially as herein described with reference to the accompanying drawings.
20. A conveyor belt substantially as herein described with reference to or as shown in Figure 2 to 4.
21. A cutting machine substantially as herein described with reference to the accompanying drawings.
22. A method of installing a support surface on a cutting machine substantially as herein described with reference to the accompanying drawings.