GB2364665A

GB2364665A - Method of bending sheet material and an article produced by bending sheet material

Info

Publication number: GB2364665A
Application number: GB0017038A
Authority: GB
Inventors: Abhilash Job Elim
Original assignee: GRANDPEAK ENGINEERING Ltd; Tecnomec Srl
Current assignee: GRANDPEAK ENGINEERING Ltd; Tecnomec Srl
Priority date: 2000-07-11
Filing date: 2000-07-11
Publication date: 2002-02-06
Anticipated expiration: 2020-07-11
Also published as: ITMI20011481A1; GB0017038D0; ITMI20011481A0; GB2364665B

Abstract

A method of forming blanks 1 particularly from metal sheets, and of using the blanks to form articles. The method comprises the use of a laser to form one or more scores along at least one bending line on the blank. The blank can then be manually and accurately bent to form the article. The laser can also be used to cut one or more such blanks from sheet material and a computer program is provided for maximising efficiency of this process. The method also provides for joining sides of the blank with each other or with other blanks using weldless joints.

Description

<Desc/Clms Page number 1> METHOD OF BENDING SHEET MATERIAL AND AN ARTICLE PRODUCED BY BENDING SHEET MATERIAL The present invention relates to bending sheets of material, particularly metal sheets, and to forming an article of sheet material by bending the sheet. The present invention also relates to forming a blank from sheet material for forming such an article, as well as to a blank and an article so formed.

At present, articles such as boxes to be formed of sheet metal, particularly in the light engineering industry, are manufactured by punching a number of different blanks from one or more sheets of metal and then performing one or more bending operations on each blank to form a number of three dimensional-components. The respective three-dimensional components are then assembled by welding, in particular seam welding, to form the finished article.

However, such a process has a number of problems, even for forming a simple box. These problems are increased where the shape of the article is complicated. Firstly, the operation of producing a number of blanks is performed by using a purpose-designed punch for each blank. This requires considerable capital expenditure to produce the required punches, which presents a prohibitive entry cost for producing relatively small manufacturing runs of such articles. In addition, the use of punches relies upon the skill of staff on a factory shop floor to manipulate the sheet material used in the punches to achieve the punching of as many blanks as possible from each sheet of material in order to reduce waste and to maximise production efficiency. Thus, there is considerable scope for human error.

Custornised punches that punch out a large number of blanks from a sheet each time a punching operation is performed can be obtained. However, due to the nature of the punching operation, punched blanks cannot share edges so that there is always at least a small amount of wastage of the sheet lying between blanks. The problem is particularly acute where large numbers of small blanks need to be punched. Additionally, the cost of such customised punches is prohibitive for small firms who are unable to afford the high initial capital outlay required.

An additional problem is that further capital expenditure is required to buy the dies necessary for bending each blank into the required shape, prior to assembly of the finished article. Again, each bending die must be customised for each required bending operation.

The problems of high capital expenditure and lowered production efficiency are further exacerbated in the event that the article to be manufactured is comparatively small, since the dimensions of each blank will be small compared to the overall dimension of the sheet to be punched. To improve efficiency, it is therefore necessary to procure large numbers of dies and punches. This requires significant investment, which increases working capital in a way that cannot easily be recovered by production activities, especially when only small lots of an article are to be manufactured on a one-off basis.

Moreover, bending of sheets and in particular of metal sheets has a number of associated drawbacks which become especially pronounced in the case of producing comparatively lightweight and/or small articles or if such articles have a complex shape. These problems include that in each bending operation, bending must be done around a single pin, that is, about a single axis, by often very complex machinery. The complexity of the machinery often leads to a large size. In the case that the article is small and has a complex shape, it is often impossible to produce a bending machine of small enough size to perform a required bending operation. Additionally, the use of bending machinery requires that if the article is to have a complex shape, particularly a closed shape such as a box, then two or more blanks must be bent into shape and subsequently welded together to produce the article.

Additionally, frequent angular adjustments of the bending are required because the elasticity of the material to be processed causes a backlash, such that the sheet tends to return to some extent to its initial planar form. This problem of elastic backlash is heightened when the sheet to be bent is comparatively thick.

Further, due to the steps of grabbing and positioning the sheet, which are inherent in any bending process, the position of the bend is not always in the correct location. This may adversely affect the quality of the finished article.

Also, the step of welding to form the finished article may present a number of further problems. These include that the level of precision of the finished article is fairly coarse in respect of both the final dimensions of the article and the angles of intersection of the sides of the article where they are welded.

Additionally, in many instances welding must be done manually. Even for welds, which could be performed by automated welding machines, it is often economically unfeasible, especially for smaller firms, to procure such custornised machines for performing each specific operation. The greater the number of operations, the greater the number of such welding machines that must be procured. The need for welding to be performed manually brings about a particularly hazardous environment for the operator's health, as well as a high cost situation, it being necessary to employ skilled welders.

Moreover, the quality of manual welding hinges on the ability and experience of the individual welder and the quality of welds and hence the finished article may therefore vary considerably according to which welder performed the welding operation. This problem is added to by the above-mentioned problem of elastic backlash, so that the welder must secure the bent sheet material in the correct position before the welding operation is performed. This may further reduce the accuracy with which the finished article is produced.

According to a first aspect of the present invention, there is provided a method for bending sheet material comprising: using a laser for forming one or more cuts along at least one line on the sheet; and bending the sheet about said at least one line.

According to a second aspect of the present invention, there is provided A method for forming at least one blank from a sheet of a material suitable for bending for forming an article, the method comprising using a computer program, in conjunction with a computer, for establishing an optimum arrangement of blanks on the sheet and for generating instructions for a computer controlled laser for cutting said optimum arrangement of said blanks.

According to a third aspect of the present invention, there is provided a method of bending sheet material comprising the use of a laser to score a bending line and then bending the sheet material at the bending line.

According to a fourth aspect of the present invention, there is provided a method of cutting sheet material to form a blank and of bending the blank at a bending line comprising the use of a laser to cut the blank and to score the bending line.

According to a fifth aspect of the present invention, there is provided a method of forming a blank including the use of a laser to score at least one bending line.

According to a sixth aspect of the present invention, there is provided a sheet of material having portions of or adjacent to a perimeter shaped such that when said sheet is bent respective ones of said portions are brought into a contiguous arrangement and attached by means of a weldless mortise and tenon joint wherein: said mortise is a hole or groove adjacent or intersecting said perimeter and extending through the whole depth of the sheet; and said tenon comprises: a first portion adapted to extend from a first side of said sheet where said mortise is formed at least part way into said mortise in the depthwise direction of said sheet; and a second portion adapted to extend past a second side of the sheet where said mortise is formed and to be bent out of the plane of the sheet where said tenon is formed to thereby attach the respective portions of the sheet, According to the present invention, there is also provided a blank, an article, an apparatus for forming the blank or the article or for performing any one of the methods of the present invention and a computer program.

Embodiments of the present invention will now be described by way of further example only and with reference to the accompanying drawings, in which: FIG. I is a plan view of a blank for forming an article of one embodiment of the present invention; FIG. 2 is a perspective view of an article assembled from the blank of FIG. 1; FIG. 3 is a perspective view of two sheet portions to be joined together for forming an article according to another embodiment of the present invention; FIG. 4A is a perspective view of a portion of a blank according to another embodiment of the present invention; FIG. 4B is a perspective view of the portion shown in FIG. 4A joined with another portion of a blank; FIG. 5 is a perspective view of two sheet portions to be joined together for forming an article according to another embodiment of the present invention; FIG. 6A is a perspective view of a portion of a blank according to another embodiment of the present invention; and

FIG. 6B is a perspective view of the portion shown in FIG. 6A joined with another portion of a blank.

The present invention provides a method in which sheet metal is processed into blanks, which blanks are subsequently bent into shape to form a required article, in which the need for punches and bending machinery is obviated and the requirement for welding to finish the article is also entirely or substantially eliminated.

According to the present invention, at least one cut or score is formed on a sheet of metal along a line about which the sheet is intended to be bent, that is, the bending line. This process is termed hereinafter as outlining the bending line. Preferably, the sheet is a metal or even a plastic sheet. Preferably, the sheet is in the form of a blank for subsequent assembly by manual bending for forming an article.

Preferably, the cut does not extend through the whole depth of the sheet but instead only part way through the sheet, so that it forms a score. Thus, the cut is effectively etched or engraved in the sheet. Accordingly, the meaning of a cut for the purposes of this application is defined to include a score. Moreover, instead of a single cut, a number of cuts may be etched or engraved on the sheet, so that the cuts form a dashed outline about which the sheet is to be bent. If a cut is deep or extends through the whole depth of the sheet, it is preferable that there be a comparatively large number of cuts along the bending line or that as an large amount as possible of the sheet lying along the bending line is not removed by cutting. This maintains the mechanical properties of the sheet to a greater extent so that the sheet is not significantly weakened in the bending region.

Additionally, if a comparatively large number of cuts is formed along the bending line, the longitudinal axes of the cuts need not necessarily be along the bending line or even parallel to each other. Although straight line cuts are preferred, they may also be curved cuts or notches or holes of any suitable size, shape or configuration.

The effect of forming one or more cuts along the bending line is to provide an area of weakness in the sheet which facilitates accurate bending of the sheet manually. Thus, the provision of cuts along the metal sheet eliminates the need for expensive, purpose-designed bending machinery and its associated problems. These problems include inaccuracies in the bent sheet, including the incorrect location of the bend, due to inaccurate automated grabbing and positioning techniques, and the impossibility of providing a bending machine

capable of performing complex bending operations in confined spaces. Moreover, the provision of cuts also eliminates to a significant extent the problem of elastic backlash in known bending techniques The provision of cuts on a preformed blank of sheet metal entails problems in accurate positioning of the blank with respect to known mechanical cutting tools. Thus, in one embodiment, the present invention provides a method in which the steps of forming blanks from a metal sheet and outlining the bending lines using cuts are performed in the same operation. Specifically, these steps are performed by laser cutting.

Laser cutting is well known in the art and provides a number of advantages over other conventional techniques for cutting sheet metal. These advantages include that laser cutting provides a clean working environment since the process of removing material is performed by the alignment of an intense monochrome beam which may be accurately directed to a highly specific portion of the metal to be cut. Typically, a metal cutting laser beam has a diameter of only 0.2mm. Additionally, material lying in the path of the beam is vaporised without leaving behind any significant residues.

In contrast, other means of cutting, including cutting using an oxyacetylene torch are generally considerably less accurate and less localised and produce burring, jags and significant residues. A new oxyacetylene cutting technique, know as hypertherm, has been developed for high resolution cuts with comparable yields to laser cutting. However, hypertherm. requires the constant replacement of cutting nozzles, at least once every fifty through-cuts or work cycles. Thus hypertherm is associated with high running costs. In contrast, laser cutting requires comparatively little maintenance. Mechanical cutting operations, such as milling, are also slow and expensive when performed to a high degree of accuracy.

Moreover, laser cutting has the advantage that it can be used for cutting sheets of varying thickness.

For steel sheet precision cutting, the useof C02, N2, He and neon-helium (Ne-He) laser beams are all known. Of these, C02, N2and He laser beams are the most widely used due to lower overall purchase and operation costs. Each beam has the advantages of high speed, output and precision, with no burrs and low general maintenance costs. Typically, regular maintenance and readjustment of the laser is performed every 2000 - 4000 hours.

The use of lasers is also known for sheet metal engraving and marking. However, f or this type of operation, YAG lasers are most commonly used. YAG lasers are characterised by an extremely thin laser beam, suitable for low depth engraving for marking or optical reading.

Although the principle of laser cutting is suitable both for cutting blanks from sheets and for sheet engraving or marking, previously the techniques of laser cutting have not been used for outlining bending lines or combined for performing both types of operation on a single sheet of metal. The inventors of the present invention have conducted numerous experiments to determine the most effective conditions by which these two operations may be combined. In particular, the relationships between the laser beam, the distance of the laser source and the surface to be processed, the thickness of the sheet, the depth of cut required, and the specific material to be cut have been studied in detail.

Thus, in the present invention, blanks are cut and bending lines are outlined by forming one or more cuts along the bending lines, preferably using single laser head, in the same process step. The type of laser to be used and the specific operating procedures are critically dependent on the thickness and the type of material of the sheet to be processed. These factors determine the depth of the bending line outline and the power and/or type of laser(s) to be used. Variables in the laserinclude selection of the laser beam adductor gas. In the present invention, sheets of low carbon up to high resistance steel, stainless steel, aluminium, titanium, brass, copper, other metal materials, plastic materials and other suitable materials may be processed. The sheets may have a thickness of 50mm. or greater, but preferably up to 20nim.

The laser head may comprise one, two or more laser sources, each provided for performing a specific processing operation. For example, the laser head may comprise a YAG laser, for performing the operation of providing cuts along the bending line or lines of the blank or blanks, and an He laser, for performing the operation of cutting the blanks from the sheet. In certain specific circumstances, depending on the material and thickness of the sheet, it may be possible to use a single laser on the laser head. The provision of lasers on the laser head is dependent, in each case, on the sheet to be processed and the processing operations to be performed.

Preferably, the laser head forms part of a computer numerically controlled (CNQ machine such that the position of the laser(s) with respect to the sheet is controlled in at

least two axes parallel to the plane of the sheet. Preferably, the power of the laser(s) and the distance of the laser source(s) from the sheet are also computer numerically controlled. Moreover, it is preferable that the selection of the laser on the laser head is automatically selected by computer numerical control, so that once the CNC machine has been programmed, further intervention during cutting by an operator is unnecessary.

The operations of outlining the bending lines on the blanks and cutting the blanks from the sheet are generally performed at the same workstation by the same laser head.

However, it is possible to have more than a single laser head operating at each workstation on a single sheet, although the cost of the machinery is thereby increased. The operation of outlining all the bending lines with cuts may be completed for a single sheet before the operation of cutting all of the blanks from the sheet is performed. However, the two operations may also be performed concurrently or alternated with each other during processing of a single sheet, Moreover, it is possible for blanks to be punched according to prior art methods and only subsequently subjected to outlining of the bending lines by laser cutting or engraving. Similarly, the blanks may be produced from a sheet by laser cutting means and subsequently the bending lines may be outlined using more conventional techniques, such as milling.

In the present invention, there is further provided an inventive data processing tool for establishing the best arrangement of the blanks to be processed on the sheet. This data processing tool is capable of maximising the number of blanks that can be formed from a sheet of a given size and may lay out the arrangement of the blanks on the sheet to minimise the time required to perform the operations of cutting the blanks and outlining the bending line or lines. The use of such a tool has the immediate advantages that waste through shavings and discards is minimised and throughput and efficiency of the cutting and outlining steps are maximised.

In operation, the shape and dimensions of one or more blanks to be formed may for example be inputted into the data processing tool, together with the number of blanks required and the dimensions of the sheet to be processed. Additional information may include the width of the blank-cutting laser and/or the width of a cut. The data processing tool is then able to determine the optimum layout of the blanks on the sheet. In particular, the data processing tool may take advantage of the fact that two or more blanks may share one or more edges on the sheet. Thus, the data processing tool may output a jigsaw-like

pattern of interlocking blanks of the same or differing shapes, which share edges with each other. In this way, the number of cuts to be performed by the laser may be significantly reduced, as may the amount of wastage due to shavings and discards. This represents substantial cost savings over prior art methods.

Additionally, the data processing tool may convert the geographic layout of the blanks and other specified operating conditions directly into a machine language readable by the CNC machine. Moreover, the data processing tool may be dynamic so that changes in the shape of the blank may be communicated to the CNC machine while the cutting and outlining steps are performed. Time-consuming, costly programming and adjustment of the CNC machine is'therefore significantly reduced.

By means of the laser cutting and outlining procedures and the data processing tool of the present invention, the optimum number of blanks is obtained and the blanks require no further processing before assembly. In particular, the use of laser cutting techniques allows the production of blanks having a constant, high degree of quality without jags, thereby avoiding subsequent manual finishing steps such as rounding and levelling.

. FIG. I shows a perspective view of a blank 1 produced in accordance with the present invention. As shown in FIG. 1, the blank 1 comprises a flat sheet of material which has been cut from a larger sheet of material and which has had further processing operations applied thereto, before, after or during the time at which the blank was cut. These operations include outlining of the bending lines 3 and 4 by engraving or etching, as indicated by dashed lines. The blank I shown in FIG. 1 includes six outlined bending lines. An additional operation is the provision of cuts 5 that extend throughout the depth of the sheet and are disposed to lie between an edge of the blank 1 and bending line 4, thereby demarcating portion 8 of the blank. On portion 8, a further operation of forming holes 6 in the blank I has been performed. In one embodiment of the present invention, such holes are formed by laser cutting. However, they may also be formed by any other known method suitable for the purpose.

FIG. 2 shows a perspective view of an article 9 assembled by bending the blank 1 shown in FIG. 1. The article 9 has a rectangular cross-section and, as shown FIG. 2, the blank 1 has been bent about each of the bending lines 3 to an angle of approximately 900 to form this shape. Of course, the angle of bending need not be 900, but can be any desired angle. Moreover, portion 8 of the blank 1 has been bent out of the plane of the upper

surface 10 of article 9 about bending line 4. Again, the angle of bending about bending line 4 may be any desired angle.

Preferably, the article is formed by manual bending, which has a number of advantages over the use of conventional bending techniques, including the elimination of the need for expensive bending machinery, as well as the problems associated therewith, the reduction of elastic backlash and improved quality of the finished article. Manual bending is facilitated by the process of outlining the bending lines, as described above.

Additionally, the fact that the blank can be bent manually significantly reduces the need for welding in order to produce the finished article. Since extremely complex shapes can be bent from a single blank in accordance with the present invention, it is generally possible to produce an article have a complex shape from only one, or a very limited number, of blanks. In contrast, using conventional techniques it is generally necessary to stamp and bend a number of blanks and then to weld the bent blanks together to produce the finished article. Thus, the present invention substantially reduces the need for performing welding.

Indeed, depending on the rigidity of the material of the blank, it may be unnecessary to perform any welding operations whatever for producing the article. For example, depending on the use to which the article 9 shown in FIG. 2 is to be put, it may be unnecessary to perform any welding operations to finish article 9. However, if is desired to strengthen the article, then spot welding or seam welding can be performed along only three edges 2 of the article 9, which lie along the top surface 10 of the article 9.

Moreover, in order to further reduce or eliminate the requirement for welding, especially where it is desired to improve the structural integrity of an article or it is necessary to produce an article having a particularly complex shape using two or more blanks, the present invention provides a method for joining opposing edges of one or more blanks together by means of a joint. Preferably the joint is a weldless joint and, more preferably, the joint is a mortise and tenon joint. On the blank shown in FIG. 1, mortises may be provided on three edges 30 and tenons may be provided on three corresponding edges 40. FIGS. 3 to 6 show examples of such joints.

In FIG. 3 there is shown a perspective view of either two portions of a single blank or one portion of each of two separate blanks. The two portions 12 and 14 are to be joined together along respective joining edges to form an article, the article having a single joint

edge where the respective joining edges of portions 12 and 14 meet. On the joining edge of the right hand portion 12 there is provided a projection 11 extending from the joining edge in the direction of the plane of portion 12. As shown in FIG. 3, projection 11 has a rectangular shape, when viewed perpendicularly to the plane of portion 12, so that the upper and lower edges of projection 11 are perpendicular to the vertical edge of portion 12. However, the projection may have a square shape or even a dovetail shape so that the angles of the upper and lower edges of projection 11 with the vertical edge of portion 12 are not 901. Moreover, although it is shown in FIG. 3 that, when viewed in the direction of the plane of portion 12, each of the upper and lower edges of projection 11 has an angle that is perpendicular to the plane of portion 12, these angles may also be adjusted to any desired angle. Indeed, the shape of projection I I need not a regular geometric shape with straight, flat edges but may have any appropriate shape.

The left hand portion 14 is provided with a groove 13 that intersects with the joining edge of portion 14. Groove 13 is shaped to have edges corresponding to projection 11 so that when the joining edges of portions 12 and 14 are brought into a contiguous arrangement, projection 11 and groove 13 co-operate with one another.

Preferably, the most extended, outermost edge of projection 11 lies in the same plane as the flat left hand surface of the sheet of portion 14 (which surface is visible in FIG. 3). Similarly, the joining edge of portion 14, except where groove 13 is formed, preferably lies in the same plane as the flat right hand surface of the sheet of portion 12 (which surface is also visible in FIG. 3). In other words, projection 11 has the same length as the thickness of the sheet of portion 14 and groove 13 has the same depth as the thickness of the sheet of portion 12. The sheets forming portions 12 and 14 need not necessarily have the same thickness. Thus, an effective joint is formed between the two portions 12 and 14.

FIGS. 4A and 4B, show another arrangement of a joint. FIG. 4A shows a portion 18 of a blank having a joining edge similar to portion 12 shown in FIG. 3. However, the projection is shaped differently. Specifically, the projection comprises a first region 11, having the same shape as projection 11 of FIG. 3, a second region 16, having a smaller cross-sectional area than that of region 11, and a tab 15, having a larger cross-sectional area than that of region 16.

FIG. 4B shows portion 18 joined with portion 14, which is the same as portion 14 shown in FIG. 3. In this case, region 11 of the projection extends into groove 13, which

has a corresponding shape so that the edges of region 11 and groove 13 co-operate. However, region 11 need not extend the whole thickness of the sheet of portion 14, although tab 15 and usually region 16 of the projection extend beyond the flat surface of the sheet of portion 14. To form the joint, tab 15 is bent out of the plane of portion 18 about region 16, which has weakened mechanical strength due to its smaller cross-sectional area. Thus, the step of welding need not be performed.

FIG. 5 shows a further arrangement of a joint, in which right hand portion 12 is the same as right hand portion 12 shown in FIG. 3 and is provided with projection 11. Left hand portion 20 is similar to left hand portion 14 shown in FIG. 3, except instead of a groove formed intersecting the joining edge of the portion, there is provided a hole 17 disposed to lie adjacent to, but not contacting, the edge of portion 20. Preferably, hole 17 extends through the whole of the thickness of portion 20. Hole 17 and projection 11 are disposed to have corresponding edges, so that these edges are coincident when the joint is formed.

FIGS. 6A and 6B show a further arrangement of a joint, in which portion 18 shown in FIG. 4A is joined with portion 20 shown in FIG. 5. In this case, to form the joint tab 15 is again bent or twisted out of the plane of portion 18 about region 16.

In FIGS. 3 to 6B, the angle of each of the joining edges is shown as square with, that is at 90' to, the plane of the portion of the blank on which it is formed. Thus, the portions will be joined at 900 to each other. However, it will be clear to persons skilled in the art that the joining angle between any two portions need not be 90', regardless of the type of joint effected. Indeed, changes in the joining angle can be simply effected by adjusting the angles of the joining edges with respect to the planes of the respective portions of a blank. The joining angle may also be 180' so that the two portions lie in the same plane.

Moreover, it will be clear to persons skilled in the art that any groove or hole formed as a mortise in a blank need not extend through the whole thickness of the sheet. The length of corresponding projections may be adjusted accordingly. Similarly, it will be clear to persons skilled in the art that the length of a projection need not be the same as the depth as the corresponding groove or hole.

The provision of projections and grooves on joining edges of portions of a blank or blanks for forming joints is ideally suited to the method of laser cutting of the present invention. Laser cutting is also suited for forming the projections and grooves in the case

where portions of one or more blanks are not joined perpendicularly to one another, so that joining edges are not perpendicular to the planes of the respective portions on which they are formed. This is especially so since laser cutting is well suited for providing the accuracy required for such joints to be effective and for providing projections and grooves which allow respective portions of one or more blanks to be joined together at an angle other than 900.

Any number of joints can be provided for on a single joining, edge of an article. The use of such joints between respective edges of portions of one or more blanks has a number of significant advantages. Firstly, the strength of the join may be enhanced and the mechanical rigidity of the article to be produced thereby improved by the use of such joints. Additionally, projection 11 and groove 13 may be shaped, for example to form a dovetail joint, so that welding of the finished product is unnecessary. This may be enhanced by the selection of different types of joint on different joining edges of an article or even on the same joining edge.

However, if it is deemed to be advantageous to further strengthen the finished article, then it is necessary to form only a limited number of spot welds, either on the joint or joints or on other portions of the joint edge, thereby significantly reducing the amount of welding, especially seam welding, required.

Moreover, the provision of such mortise and tenon joints allows the article to be manually assembled with the elimination of assembly tolerance errors, since the joints allow precise location of the respective joining edges of portions of the blank or blanks to be joined. The need for additional tools, such as vices, for assembly is therefore eliminated or significantly curtailed and the article can be more quickly assembled.

Finally, occasional errors in the process of assembling similar parts can be limited with the use of specific templates.

In summary, the present invention provides a solution to the high capital expenditure and the high manufacturing costs involved in producing articles of sheet metal, at the same time eliminating or substantially reducing the problems involved with punches, bending dies and welding.

The aforegoing description has been given by way of example only and it will be appreciated by a person skilled in the art that modifications can be made without departing from the scope of the present invention.

Claims

CLAIMS: 1. A method for bending sheet material comprising: using a laser for forming one or more cuts along at least one line on the sheet; and bending the sheet about said at least one line.
2. A method according to claim 1, wherein at least one of said one or more cuts is formed through the whole thickness of the sheet.
3. A method according to claim I or claim 2, wherein at least one of said one or more cuts is formed only partially through the thickness of the sheet.
4. A method according to any one of the preceding claims, wherein said material is metal or plastic.
5. A method according to any one of the preceding claims, wherein said sheet is bent manually.
6. A method according to any one of the preceding claims, wherein said laser is disposed at 90' to said sheet.
7. A method according to any one of claims 1 to 5, wherein an angle of said laser with respect to a surface of said sheet is variable. 8. A method according to any one of the preceding claims, wherein said laser is controlled by a computer. 9. A method according to any one of the preceding claims comprising using two or more lasers of different types. 10. A method according to any one of the preceding claims, wherein:

<Desc/Clms Page number 15>

using a laser for forming one or more cuts along at least one line comprises cutting at least one blank from the sheet; and bending the sheet comprises bending the blank to form an article. 11. A method for forming at least one blank from a sheet of a material suitable for bending for forming an article, the method comprising using a computer program, in conjunction with a computer, for establishing an optimum arrangement of blanks on the sheet and for generating instructions for a computer controlled laser for cutting said optimum arrangement of said blanks. 12. A method according to claim 10, further comprising the step of using a computer program, in conjunction with a computer, for establishing an optimum arrangement of blanks on the sheet and for generating instructions for the laser for cutting said optimum arrangement of said blanks. 13. A method according to any one of claims 10 to 12, wherein a portion of or adjacent to a perimeter of said blank is shaped for forming a portion of an interlocking joint. 14. A method according to claim 13, wherein said interlocking joint is a tenon and mortise joint. 15, A method according to claim 14, wherein said tenon is a dovetail. 16. A method according to claim 14, wherein said tenon has a rectangular or square profile. 17. A method according to claim 14, wherein said mortise is a hole or groove adjacent or intersecting said perimeter and extending through the whole depth of the sheet; and said tenon comprises: a first portion adapted to extend from a first side of said sheet where said mortise is formed at least part way into said mortise in the depthwise direction of said sheet; and

<Desc/Clms Page number 16>

a second portion adapted to extend through said mortise past a second side of the sheet and to be bent out of the plane of the sheet where said tenon is formed to thereby attach the respective portions of the sheet. 18. A method ac cording to any one of claims 13 to 17, wherein said joint is a weldless joint. 19. A method of bending sheet material comprising the use of a laser to score a bending line and then bending the sheet material at the bending line. 20. A method of cutting sheet material to form a blank and of bending the blank at a bending line comprising the use of a laser to cut the blank and to score the bending line. 21. A method of forming a blank including the use of a laser to score at least one bending line. 22. A blank formed according to the method of claim 20 or claim 21. 23. A sheet of material having portions of or adjacent to a perimeter shaped such that when said sheet is bent respective ones of said portions are brought into a contiguous arrangement and attached by means of a weldless mortise and tenon joint wherein: said mortise is a hole or groove adjacent or intersecting said perimeter and extending through the whole depth of the sheet; and said tenon comprises: a first portion adapted to extend from a first side of said sheet where said mortise is formed at least part way into said mortise in the depthwise direction of said sheet; and a second portion adapted to extend past a second side of the sheet where said mortise is formed and to be bent out of the plane of the sheet where said tenon is formed to thereby attach the respective portions of the sheet. 24. An article formed using a method according to any one of claims 1 to 21 or using a blank according to claim 22 or a sheet according to claim 23.

<Desc/Clms Page number 17>

25. An apparatus adapted for performing a method according to any one of claims I to 21 or for producing a blank according claim 22 or a sheet according to claim 23 or for forming an article according to claim 24. 26. A computer program for performing the method of claim 10 or claim 11. 27. A method for forming a blank from sheet material substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings. 28. A method for bending sheet material substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings. 29. A blank substantially as hereinbefore, described with reference to and as illustrated in any one of the accompanying drawings. 30. An article substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings. 31. A computer program substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings.

<Desc/Clms Page number 18>

CLAIMS: A method for bending sheet material comprising: using a laser for cutting at least one blank from a sheet and for forming one or more cuts along at least one line on the blank; and bending the blank about said at least one line to form an article, wherein a portion of or adjacent to a perimeter of said blank is shaped for forming a portion of an interlocking joint. 2. A method according to claim 1, wherein said interlocking joint is a tenon and mortise joint. 3. A method according to claim 2, wherein said tenon is a dovetail. 4. A method according to claim 2, wherein said tenon has a rectangular or square profile. 5. A method according to claim 2, wherein said mortise is a hole or groove adjacent or intersecting said perimeter and extending through the whole depth of the sheet; and said tenon comprises: a first portion adapted to extend from a first side of said sheet where said mortise is formed at least part way into said mortise in the depthwise direction of said sheet;. ahd a second portion adapted to extend through said mortise past a second side of the sheet and to be bentput of the plane of the sheet where said tenon is formed to thereby attach the respective portions of the sheet. 6. A method according to any one of the preceding claims, wherein said joint is a weldless joint. 7. A method accordingo, to any one of the preceding claims, wherein at least one of said one or more cuts is formed through the whole th4kness of the blank.

<Desc/Clms Page number 19>
8 A method according to any one of the preceding claims, wherein at least one of said one or more cuts is formed only partially through the thiclmess of the blank.
9. A method according to any one of the preceding claims, wherein said material is metal or plastic.
10. A method according to any one of the preceding claims, whereia said blank is beat manually.
11. A method according to any one of the preceding claims, wherein said laser is disposed at 90* to said sheet.
12. A method according to any one of claims 1 to 10, wherein an angle of said laser with respect to a surface of said sheet is variable.
13. A method according to any one of the preceding claims, wherein said laser is controlled by a computer.
14. A method according to any one of the preceding claims comprising using two or more lasers of different types.
15. A method according to any one of the preceding claims, further comprising the step of using a computer program, in conjunction with a computer, for establishing ail optimum arrangement of blanks on the sheet and for generating instr a*ctions for the laser for cutting said optimum arrangement of said blanks.
16. A blank formed according to the method of any one of the precedincr claims. a . 0

<Desc/Clms Page number 20>
17. A sheet of material having portions of or adjacent to a perimeter of said sheet shaped such that when said sheet is bent respective ones of said portions are adapted to be brought into a contiguous arrangement and attached by means of a weldless mortise and tenon joint wherein: said mortise is a hole or groove adjacent or intersecting said perimeter and extending through the whole depth of the sheet; and said tenon comprises: a first portion adapted to extend from a first side of said sheet where said mortise is formed at least part way into said mortise in the depthwise, direction of said sheet; and a second portion adapted to extend past a second side of the sheet where said mortise is formed and to be bent out of the plane of the sheet where said tenon is formed to thereby attach the respective portions of the sheet.
18. An article formed using a method according to any one of claims I to 15 or using a blank according to claim 16 or a sheet according to claim 17.
19. An apparatus comprising a laser and a control means for performing a method according to any one of claims I to 15 or for producing a blank according to claim 17 or for forming an article according to claim 18.
20. A data processing tool for performing the method of any one of claims I to 15.
21. A method for forming a blank from sheet material substantially as hereinbefore described with refereAce to and as illustrated in any one of the accompanying drawings.
22. A method for bending sheet material substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings.
23. A blank substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings.

<Desc/Clms Page number 21>
24. An article substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings.
25. A data processing tool substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings.