NO862009L - PROCEDURE AND DEVICE FOR AUTOMATIC CUTTING OF SKIN AND SIMILAR. - Google Patents

Description

The present invention relates to a method for direct and automatic cutting of skin followed by manual displacement of templates or patterns placed on the skin.

The invention is specifically applicable for cutting pattern pieces within the leather goods industry, in particular the shoe manufacturing industry, but can likewise be used in all other areas where problems arise with optimal placement of varied and more or less complicated shapes on any form of support for cutting the shapes.

Within the shoemaking industry, the cutting of intricately shaped pieces is primarily done by using hole punches. This allows the operator to maintain control over the placement of the tool on the skin to be cut, but is expensive for small scale production and makes production take longer due to the delay in making the tool.

In recent times, new cutting technology has been introduced and has tended to replace the hole punches.

Two recently discovered cutting devices that use laser beams and jet fluid together with electronic data processing devices now provide total flexibility that enables a company to react very quickly to changes in cutting requirements.

The system for placing the shape to be cut on the skin then becomes complicated and expensive, and no satisfactory solution has been found to date to this problem.

In a previously known placement technique, the cutter places a number of paper or cardboard templates on a main skin by hand. As soon as it has been covered in this way, it is scanned and the result stored in a computer which then controls the cutting of the skins on the basis of the stored information. A process of this nature is cumbersome, complicated and somewhat unreliable.

In another technique, which is more refined and automated, a computer that takes into account each individual skin to be cut according to the defects in each individual skin and organizes the positions of the various pattern pieces previously stored in its warehouse on it usable surface and subsequently the trimming of the skin is controlled.

However, such complicated and expensive systems do not have the desired operational reliability and cannot be used on an industrial basis.

In the so-called semi-automatic supply method, the various pattern pieces and the skin to be cut, together with errors and other parameters that must be taken into account when laying on the skin, are stored in a computer and can be displayed on a screen. By using a light pen, the operator can then select the pattern pieces to be cut and attempt to provide their optimal manual position on the skin, which is also displayed. When the operator has completely covered the skin, he instructs the computer to record this layer to be used for the subsequent cutting operation.

A system of this kind is slow and somewhat inconvenient since it requires the recording of each skin with its defects and other necessary parameters for the layout in advance.

It is an object of the present invention to provide a new method for automatic cutting of a skin which includes an interactive manual placement of the templates with means to substantially save the time it takes to use the method and combine the advantages of the manual supply directly on the skin by means of the cutter with the computer-based automatic control of the cutting of the skin by using existing modern technology such as devices using water jets and laser beams.

The present invention relates to a method for cutting a skin or similar material which contains interlocking placement of templates on the skin, where the method includes the steps: - placing the skin directly on the working surface of a cutting table for an automatic cutting system of water-jet, laser beam or similar type,

- placing the templates optimally on the skin by hand, within a predetermined frame on the work surface, each template being placed in advance by means of a coding device to identify the template and recognize the position within the frame,

- photographing the templates placed in this way within the frame,

- saving an image of this layer with templates,

- analyzing the image step by step by recognizing the codes successively, and - commanding supply of the cropping tool within the frame in response to each code reading and previously entered and stored contours and codes of all the templates and thus to reproduce the contour of a decoded template.

A method of this kind can produce significant time savings in use since the skin can be trimmed almost immediately after the manual application due to the fact that it does not have to be removed, brought to and placed on the trimming system, but is already ready for trimming even before the application is performed .

Although this method requires prior storage of different template shapes and codes assigned to each shape, this operation is performed on a system including a calculation unit, a digitizing table and a plotter, completely autonomous and independent of the cutting installation that constitutes the method according to the present invention. At the operation stage, this installation can be operated continuously by using data and instructions stored on cassette, e.g. in order to easily manipulate and make the mutual replacement.

The coding with which each template is provided is preferably a circular bar code type and consists of a ring-shaped disc placed or displayed on the side of the template at a suitable location and with which is associated an orientation point materially produced on the image on the layer, said point being placed or displayed on the side of the template at a predetermined distance from the center of the outer annular disc.

Each template shape is advantageously recorded in the form of a vector representation comprising a set of vectors originating from the center of the ring-coded disk, the ends of which, when connected, reproduce the outline of the template.

In another embodiment, the purpose of the invention is to provide a device for carrying out the method for cutting skin or similar material which includes the mutual placement of templates on the skin, the method being of the kind previously mentioned, and where the device is a cutting system of the type which uses a water jet, laser beam or the like and where the cutting system includes a cutting table, a work surface on the cutting table, a cutting tool, a computer to control the cutting tool, a camera positioned above the work surface and a calculation unit connected to the camera and the computer, the calculation unit including a processor and a floppy disk drive or the like for information storage with respect to the templates, vector rendering of the templates and the templates' codes.

Other features and advantages of the invention shall be described in more detail below by way of example and with reference to the drawings, where: Fig. 1 schematically shows an installation for carrying out the method

according to the present invention.

Fig. 2 shows a preferred method for storing shabu flower forms. Fig. 3 shows a template provided with coding in accordance with the invention.

Fig. 4 shows a code disk in accordance with the invention.

Fig. 5 shows how two parts of the disc separated by a diameter become

identified.

Fig. 6 shows a variant of the template in fig. 2.

Fig. 7 shows the vector rendering of the hole in the template in fig. 6.

Fig. 8 shows a template in accordance with the invention in the input identifier the tion. Fig. 9 shows the template of fig. 8 after the turn at the time it is

placed.

Fig. 10 shows a template provided with an alternative coding in accordance with the invention.

The device schematically shown in fig. 1 includes a cutting table 1 e.g. for a cutting device of the type that uses a water jet, which spray nozzle 2 is movable in two orthogonal directions X and Y by means of a conventional sliding and carrying system symbolically shown with the reference number 3.

The nozzle 2 can thus be moved to any point above the cutting surface of the table 1 on which a skin 4 or similar material is placed which is to be cut, and which is held by means of e.g. a well-known suction system that keeps the skin on the table.

The cutting device is controlled by a processor which forms part of a calculation system symbolically shown with reference number 5 connected to a chamber 6 mounted at a fixed position above the cutting surface of the table 1 and also connected to terminal 7 containing keyboard and display screen.

The usable area within which the templates, such as that shown at reference numeral 8, must be placed on the skin 4 is limited by the cutting table by means of an illuminated reference marking, e.g. an illuminated line 9 defining a rectangle, projected by means of a light box 10 placed next to or surrounding the camera. A luminous reference mark 9 of this kind marks a work surface of e.g.

600mm x 400mm.

The light box 10 can e.g. be replaced by a spot lamp that illuminates the work surface, as the illuminated area limits the usable area.

An infrared barrier schematically shown at reference number 11 and generated by a suitable conventional device 12 prevents access to the working area when the cutting system 2-3 is in motion. The barrier 11 placed at the front of the cutting table between the operator and the work surface, as such a barrier can also be placed at the sides if necessary.

This installation is operated as follows: After placing the various templates on the work surface within the area limited by the illuminated frame 9 and in accordance with the requirements for optimal laying, the operator starts the calculation unit 5 e.g. by pressing a push button to generate an external signal. The calculation unit 5 instructs the camera 6 to photograph the working surface bounded by the frame 9. While the operator removes the templates, the processor of the system 5 performs its routines for recognizing the templates 8 (ie their shapes and orientations) within the frame 9. The calculation unit successively calculates for each template the position on the working surface of a certain number of points on the contour of the template (previously inserted and saved by means of a procedure to be described later) and starts the instruction, after the operator has started an authorization signal to continue with successive cutting of the different template shapes recognized and placed on the work surface, the device 2-3 being commanded via an intermediary to the processor that controls this device.

The camera 6 can be a charge-coupled device (CCD) or similar camera with a resolution of 488 and 388 lines.

Signal from the camera is sent and processed by the calculation system 5 to recognize on the basis of the code the position of each template within the frame 9 in accordance with a Cartesian (X, Y) system of identical coordinates, which naturally is associated with the displacement of the nozzle 2 .

When the last recognized shape of the computing unit has been cut, the nozzle 2 is returned to its rest position and the infrared barrier 11 is switched off. If part of the operator's body or another object interrupts the infrared beam during the trimming process, the trimming system will be switched off immediately.

When the trimming has been completed, the operator moves the skin 4 by hand so as to bring into the frame 9 a new area of skin to be trimmed, the front end of the skin (on the side of the trimming system 2-3) having been received in a transverse trough 13 placed in the gap between the table 1 and the frame of the cutting system 2-3.

Using the keyboard terminal 7, it is possible to converse between the cutter and the machine. It can be used to indicate the total number of pieces to be cut at a time. Connected to a buzzer, it can indicate the templates that are not to be used again.

The cutter can use the terminal to change the number of pieces he wants to cut and verify at any time that the operation is being carried out correctly.

In order for the processor of the calculation system 5 to be able to process images produced by the camera 6, the templates must be coded so that their shapes, types and orientations in the cutting plane are easily, quickly and reliably recognisable.

For this purpose and in connection with the invention, each template has its shape represented in vector form and coded as will now be described and shown in fig. 2 and 3.

Fig. 2 shows the contour 14 of a template shape defining a polygon. This polygon has a marking center 15 and an orienting reference point 16. The center 15 is the starting point for a coded marking that contains all the information necessary to identify the shape in question. The center 15 is also the starting point for a set of vectors Vjp, ^11» ^12 •••• ^14»n<y>ilch ends are connected together to form the contour 14.

The contour 14 can thus be precisely defined by the above-mentioned vectors from the same starting point 15 and respective modules and arguments of which are known, which are determined relative to the so-called main direction 17 defined by the two points 15 and 16.

Any template shape can be defined in this way, the contour of the template consisting of rectilinear segments connecting the ends of the various vectors emanating from the point 15. When the shape of the template is polygonal, as shown in fig. 2, a small number of vectors is sufficient. For round shapes or partial shapes, the number of vectors must be increased so that the "vector" contour is the same as the theoretical contour within a necessary degree of accuracy.

The coded marking should preferably have no main direction, as this would have to be determined by using a cumbersome process routine.

The well-known circular bar code is particularly suitable for this application. Regardless of the angular position of the template, the processor of the system 5 can read the code along the horizontal diameter (or any other diameter that serves as a reference) and therefore decode the number of black and white rings on this diameter that make up the embodiment. Fig. 3 shows a template placed in accordance with the invention with a circular bar code symbolically produced with the reference number 18 and centered on the marking center 15 and with an orientation reference point 16. Fig. 4 shows a preferred code scheme. This contains two half-areas Z1 and Z2 separated by a diameter 19 and each includes nine concentric rings (white in the figure) and one peripheral ring 20 (black).

In area Zl, eight half-rings give the code for the type of shoe in a given season.

In area Z2, seven half-ring codes give the number of templates for the shoe type and the outer half-ring 21 the code for the season (summer or winter).

The number of rings can clearly be varied in accordance with the number of templates and the number of shoe types. The number of rings nevertheless lies between two limits, one of which is given by the resolution of the camera 6. For the type of camera used, the resolution is between 1 and 1.5 mm per pixel (image element) and the rings must therefore have a width that exceeds this resolution, such as e.g. 2 mm.

The second limit is the maximum diameter of the concentric rings that can be fitted on the smallest template.

The ninth ring 22 serves to identify the half area Z1 and Z2.

in

This ring 22 is white for the area Z1 and black for the area Z2, e.g.

To prevent problems should the diameter along which the processor reads the code coincide with the diameter 19, the ring 22 is divided into two asymmetric white (22a) and black (22b) half rings.

If the ring 22 thus has the same color on either side of the center when it is read, the processor is commanded to read along a diameter at right angles used for the previous reading operation, so that it is ensured that two different colors are detected on the ring 22 , one on each side of the centre, and so that two areas Zl and Z2 will be read without any possibility of distortion.

In the coding scheme shown in fig. 4, provision is made for up to 256 different shoe types per season, with two possible seasons (summer or winter) and up to 128 constructions of templates per type.

If the number of shoe constructions is reduced, it is naturally not necessary to divide the coding rings into two areas or to add a ring 22 to identify these areas.

In fig. 3, the concentric encoders 18 are symbolically shown with only the outer ring. The point 16 is placed within the outer ring and is at a distance d from the marking center 15.

It should be noted that the processor can calculate the distance d that makes it possible to verify the code reading (as this distance d is stored in the vector description of the template) and it is possible to distinguish between two shapes that have the same code.

Fig. 6 shows a template of identical shape with respect to the outer contour to that shown in Fig. 2, but has a triangular hole 23.

With the help of the present invention, it is possible to produce this hole in vector form (cf. fig. 7), as the triangular shape 23 is shown on the basis of the same center 15 and the same orientation point 16 (vectors V2p, V21, <V>22) - The should be noted that the vector V2p, similar to the vector Vjp (Fig. 2), corresponds to a displacement of the cutting tool 2 in the raised position, as the tool does not come into operation until the end of

the vector.

It should be noted that the various internal shapes similar to the shape 23 to be cut out are stored by the calculation unit and need not be shown on the template.

The vectors that define a particular template shape are stored with any initial orientation. The template 8 is e.g. on fig. 8 processed or fed into the system with the main direction 17 horizontal.

When this template, placed by the operator, is recognized by the calculation unit 15 through the intermediary in the form of the camera 6, it can be in any angular position relative to the input position. In the position shown in fig. 9, the main direction 17 of the template 8 has been turned over the angle 9°.

To find the coordinates of the points on the contour of the template in fig. 9, it is sufficient to rotate all the vectors that determine the contour of the template in fig. 8 above 0°. This is done with the help of the calculation system 5 after the detection of the center 15, the point 16 and the code 18.

The templates are entered and coded using a system that is totally automatic and independent of the cutting installation and includes a calculating unit, a digitizer and a plotter.

The digitizer associated with the calculation unit was used to enter any template shape. To do this, a drawing of the template is placed on the digitizer and its contour is traced with a "stylus" or mouse, depending on the type of digitizer used. The calculation unit stores the contour in its storage. It then determines the minimum number of points necessary to define the template within tolerances given by error-control methods, such as least squares. The calculation unit can then "vectorise" the shape by defining (either by itself or with the help of the person using the system in accordance with the invention) the position of the concentric ringed disk 18 representing the code of the template, previously defined automatically or manually, and the point 16 which is necessary to determine the orientation. Once the "vectorization" has been done, the computing unit stores the contour in its storage (on diskette) and can then draw it up or apply plotting, either on a rigid thin material subsequently cut to size by any suitable process or on a thin foil material so that it will make it possible to cut out a more rigid material on the installation, cf. fig. 1, which uses the just-written diskette, the marked foil material being glued to the template.

The drawing of the template includes:

- the contour so that its accuracy can be checked against the original; - the code diskette 18; - orientation point 16;

- marking for the template in readable form.

This will allow you to cut out as many sets of templates as necessary.

The calculation system 5 in fig. 1 receives the disks produced in this way associated with the desired shoe type or shoe types. The operator instructs the calculation unit 5 to load the shapes stored on the diskette or disks as applicable.

The current operating cycle in the machine can then begin.

The processor of the calculation system 5 locks onto the stored image of the work surface photographed by the camera 6 for the codes 18 and orientation points 16 for each shape. It is then given rotation to the first found shape. The calculation results are sent to the processor control of the cropping system 2-3 which becomes operative on its own initiative as soon as it has received sufficient contour points. The computing unit 15 then moves on to the second shape, etc., to the last shape to be cut out which has been recognized in the stored image, after which it instructs the system 2-3 to return to its rest position.

in Fig. 10 shows an alternative embodiment of the template coding.

The template 8' includes three points 24, 25, 26 within a closed contour 27 of any shape which enables points to be isolated and adjacent template points which have just been recognized to be ignored when the analysis is carried out by image storage.

These three points are connected by two straight lines 28 and 29 which enable the calculation unit to locate other two points quickly from the first located point. Each point has a diameter of 6 mm so that it can easily be detected by the imaging system.

The intersection of two segments 28, 29 gives the original (point 24) of the piece 8'. The longer segment 28 defines the direction and thus the orientation of the template 8' in the plane.

The combination of the distances a and b separating the original point 24 from the other two points is uniquely defined and defines the code of the templates, types, season, year, etc.

The distance between two points is between 20 mm and 2000 mm, e.g. with an increase of 4 mm (the resolution limit of the imaging system), which enables more than 90,000 different combinations.

The point 24 at which two straight lines 28 and 29 intersect is the starting point for the vectors of the contour for the template 8' as in fig. 2 and 3.

The position of the three points, the marking of these points and the marking of the contour 27 and the segments 28, 29 are effected automatically during the aforementioned digitization phase.

It should be noted that the machine can cut through a number of stacked hides at the same time. In order to maintain a frame 9 of constant size regardless of the thickness of the skin or skins lying on the cutting table, the positions of the table are adjusted vertically relative to the system 6-10. Opposite arrangements are also possible, including a fixed away and a vertically movable camera/lightbox assembly.

Claims (9)

1. Method for cutting a skin or similar material containing the interposition of templates on the skin, characterized by - placing the skin directly on the working surface of a cutting table by an automatic cutting system of water jet, laser beam or similar type, - placement of templates optimally on the skin by hand within a predetermined frame on the work surface, each template being provided in advance with a coding for identification of the template and recognition of its position within the frame, - photography of the templates placed in the above-mentioned manner within the frame, - saving image of this layer with templates, - analyzing the image step by step by recognizing the coding successively, and - commanding the displacement of the cutting tool within the frame as a result of code reading and previously introduced and stored contours and codes of all the templates in order to reproduce the contour of the decoded template. 2. Method according to claim 1, characterized in that a circular bar code type is used as coding which consists of a ring-shaped disc applied or displayed on one side of the template at a suitable place and with the help of which an orientation point is associated which can be materially detected on the image layer, the point being applied or appear on the side of the template at a predetermined distance from the center to and outside the annular disc. 3. Method according to claim 2, characterized in that the ring-shaped coding disk is divided into two areas separated by a diameter, one area being used for coding different shoe types and the other for template construction per shoe type. 4. Method according to claim 2, characterized in that the disc includes a ring which serves as a code for the season (summer or winter). 5. Method according to claim 3, characterized in that the disk includes a ring to identify the area that is asymmetrical in relation to the diameter that separates the areas. 6. Method according to claim 1, characterized in that the coding with which each template is provided consists of three separate points surrounded by a continuous line, one of which points is connected to each of the other two by means of respective straight line segments, the length of the segments serves to identify the template. 7. Method according to claim 1, characterized in that each template shape is recorded in a vector form for production including a set of vectors from a starting point to the coding, the ends of which are connected together to reproduce the shape of the template. 8. Apparatus for carrying out the method for cutting skin and similar materials including cooperative placement of the template on the skin as stated in claim 1, characterized in that it includes a cutting system of water jet, laser beam or similar type, where the cutting system includes a cutting table, a work surface on the cutting table . . 9. Apparatus according to claim 8, characterized in that the usable area for the working surface of the cutting table is limited by an illuminated area or a marking projected on the skin, which is placed on the table, the camera being focused on the area thus limited.