EP0202676B1

EP0202676B1 - Apparatus for cutting sheet material having one or more layers

Info

Publication number: EP0202676B1
Application number: EP86106923A
Authority: EP
Inventors: Rodrigo Becerra Carrasco; Bernardo Alcantara Perez
Original assignee: Investronica SA
Current assignee: Inetum Espana SA
Priority date: 1985-05-22
Filing date: 1986-05-21
Publication date: 1991-01-30
Anticipated expiration: 2006-05-21
Also published as: DK224586A; IE57384B1; DK164086C; FI82812B; EP0202676A2; FI82812C; DE3677255D1; ATE60536T1; DK164086B; DE3530886A1; EP0202676A3; ES543394A0; FI861976A; JPS6219397A; IE861346L; FI861976A0; ES8706339A1; CA1278506C; DK224586D0

Abstract

Procedure and device for cutting pieces of material to order, from a band of material, by using a cutting table equipped with a vacuum installation for holding the band of material in place and a workable, longitudinal and traverse slide on the cutting table, running along the desired cutting lines, which is controlled by a data processor for marking and data control, as the carrier of a cutting tool driven by ultrasound, for the purpose of which a conveyor belt with a base similar to a brush serves as the means of transport for the band of material in the cutting area and as a cutting base, which is moved, step by step, by means of a slide range that, for the finished cut of a piece of material, is larger than the cutting tool's most ample movement in the longitudinal direction (X), for which purpose, the cutting tool in each case only moved following the transportation phase, with the conveyor belt being stationary all along the cutting lines.

Description

The invention refers to an apparatus for cutting sheet material having one or several layers, comprising a cutting table equipped with a vacuum installation for holding the material in place, a slide device moving lengthwise in Y-direction and crosswise in Y-direction of the cutting table as carrier or an ultrasound driven cutting tool unit, movable in Z-direction perpendicular to the cutting table, the movements of the slide device along the cutting lines are controlled by means of a data processor which processes the marking data and the data control and an airpermeable synthetic fiber base on the cutting table as support surface for the material to be cut, whereby the ultrasonic cutting unit comprises a cutting tool with a cutting edge, a coupling element, an ultrasonic emitter and a converter which are connected to a carrier, said carrier is up and down movably supported.
Apparatus for cutting sheet material comprising a table for supporting the material to be cut and a carriage which is displaceable in X- and Y-direction relatively to the table and carrying a cutting tool and a drive mechanism for operating the cutting tool during the movements of the carriage are known for example by GB-A-2.019.295.
As the sheet material to be cut normally comprises a plurality of layers the length of the up and down motion of the mechanically driven cutting tool being rotatable mounted about the longitudinal axis-known as Z-axis-perpendicular to the surface of the cutting table is about 20 mm. Moreover, the table for supporting the material to be cut must have a penetrable bristle bed defining the material supporting surface upon which the material to be cut is supported. The single fibres of such a bristle bed must have a great length which is in the range of 30 mm.
Therefore, assemblies of this kind are relatively costly both in view of the construction of such cutting heads and of the need of a voluminous bristle bed. Further, cutting heads of this type are also inconvenient from the point of view of their large masses given that during the cutting movements along the cutting lines they must accelerate and stop continuously, entirely independent of the fact that their maintenance is also burdensome and costly.
According to GB-A-2.087.290 the mechanically driven cutting tool is replaced by an ultrasonically vibrated cutting tool which has a small dimension. To achieve a good cutting result it is important that the tip of the cutting tool does not go away from the surface defined by the top of the fibers of the bristle bed and does not touch the base of the cutting table; that means to hold the tip of the tool continuously in the area defined by the length of the fibers of the bristle bed independently of parallelism errors existing between the surface defined by the bristle bed and the plane defined by the X-Y-carriage mechanism that moves the cutting tool. In view of the large dimensions of such areas errors are not negligible. To ensure a preset value of distance between the cutting surface and an elevator carriage carrying the cutting tool a displacement sensor is located near said cutting surface.
This document is the basis for the preamble of claim 1.
Cutting a pile of sheet material at high speed with an ultrasonically vibrated cutting tool of small dimension is thus a problem.
According to DE-B1-1.053.151 a cutting apparatus is known which comprises a steel wire set in vibrations by an ultrasonic generator for cutting soft food supplies or paper. For cutting of sheet material consisting of one or several layers of fabric spread out on a cutting table such a cutting apparatus is not usable.
In the light of ever-increasing costs, there is a considerable demand for inexpensive installations for automatical cutting pieces of material or cloth to order.
Function of the present invention is to improve and simplify a cutting apparatus of the kind to establish a simpler construction and of easier maintenance than used up to date.
In accordance with the invention the improved cutting apparatus is characterized in that the carrier is mounted on a disc in form of a cogwheel, having a hollow central sleeve as bearing which surrounds the coupling element of the cutting tool and is rotatably mounted around said Z-direction on a crossbar joined to the Y-carrier of the slide device of the apparatus, that the cutting tool is mounted to said converter and having a blade stroke between a few hundreths to a few tenths of a millimeter, and that the fiber base on the cutting table consists of individual fibers which are approximately 0.5 mm in diameter and 5 mm in length.
Advantageously the ultrasonic cutting unit comprises a cutting tool with a cutting edge perpendicular to the surface of the cutting table, whereby said cutting tool is connected to the ultrasonic emitter such that one of the cutting edges of the cutting tool is oriented exactly in the Z-direction, and whereby the up and down movement of the carrier is generated by a cylinder which is connected to the cutting unit.
Regarding the known mechanical cutting systems, in which the blade stroke of the cutting tool amounts to approximately 15-20 mm, here it is between a few hundreths to a few tenths millimeter. The height of the fibers on the brush surface can thus be considerably reduced to 2 or 3 mm, which provides for considerable savings, especially, when an endless conveyor as a supporting surface for the material to be cut is used. Further, the cutting frequency is much greater than in known mechanical systems.
Another advantage to be considered is the fact that the control of the cutting tool around axis Z is simpler to carry out than it has been to date, and because of the vertical movement along axis Z can take place with the blade stroke stopped, contrary to the known systems, in which the cutting tool, when freely run, i.e. at maximum speed, is moved from one piece to be cut to another.
The movable carriers coordinated with the area for cutting to order are controllable in known manner by means of a NC data-control processor in the X and Y direction, so that the cutting head can reach any designated point on the surface of the band of material. Also, the controlling signals for the direct current motors that move the carriers are generated in known manner in a so-called cutting line generator, thus making the directions of the movements and the accelerations and speeds controllable within ample limits. In this way, it is possible to cut profitably different materials under NC-control, such as fabric, paper, cardboard, plastic and similar materials, material in the shape of bands in individual layers or also in multible layers for the purpose of which the material to be cut can be processed from a roll or as a flat sheet.

Description of the drawings

Figure 1 is a perspective view of an NC-controlled cutting machine for the cutting of pieces of materials from a band of material according to the invention;
Figure 2 is a diagrammatically side view of a vacuum device used in the cutting machine according to Figure 1, holding a band of material in place during the cutting process;
Figure 3 is a perspective view of a drive device for the cutting head carrier of the cutting machine according to Figure 1;
Figure 4 is a diagrammatically view of the cutting tool for the cutting machine according to Figure 1;
Figure 5 is a modified cutting tool according to Figure 4 in form of a diagram;
Figure 6 is a cutting head for the cutting machine according to Figure 1, in a perspective drawing, and
Figure 7 is in diagram form, a partial cross section of a side view of the cutting head according to Figure 6.

In Figure 1, a NC controlled cutting machine for automatically cutting to order, which is defined generally with reference number 20, is represented. A material 24 to be cut is on the cutting surface 26, also defined as the cutting table.
The cutting surface is comprised of a type of brush surface 28 (Figures 4 and 5) of synthetic fibers, approximately 0.5 mm thick and 5 mm in length, which is air-permeable, which covers the entire cutting surface and upon which the vacuum acts, which is generated by means of a generator 40 see Figure 2.
A cutting head 81 which holds the cutting tool 106 still to be described is housed and moves in the X and Y directions, which coincide with the lengthwise and crosswise directions of the cutting surface 26. As is shown in detail in Figure 3, a x-carrier 49 has been designed, which is movable in the X direction and a y-carrier 62, movable in the Y direction. The X-carrier 49 slides along rails 64, which are arranged in parallel to one another in the cutting area 26, while Y-carrier movement is crosswise and that of X-carrier is lengthwide. As the movements in both directions take place according to the same principle, only the movem- vent in direction X is described here.
The drive of the X-carrier in direction is comprised of a direct current motor 66, located at the front part of the cutting area, a tachometer 68 and a position regulator 70, which is controlled by a position servoregulator, not shown here. Through a reducing gear 72-74, the motor 66 moves on an axle 76, which is projected crosswise through the cutting table, over which a nonstop conveyor belt is guided, which supports the brush surface 28. At the free ends of the axis, there are toothed pulleys 78, 80, by means of which the toothed belts 82, 84 are guided, nonstop, which are kept taut by means of the toothed pulleys 86, 88. The X-carrier 49 is screwed to the toothed pulleys 84, through which it is synchronized in movement with the belts 82, 84.
On the X-carrier 49, there is a direct current motor 90, a tachometer 92, a position regulator 94, a gear 96, 98 with drive pulleys 100, a toothed belt 102 and a tensing roller 104, which serve to drive Y-carrier 62. The movements in direction Y are controlled in the same way that it is done in direction X, by means of a coordinated regulation of the position, for which purpose the habilitation signals for the X and Y regulation coils, in addition to the cutting tool 106 for the movement, rotation, around axis Z located perpendicularly to the cutting surface 26 are generated in a control apparatus 18.
As shown in Figure 4, the cutting tool 106 has one blade edge 108 which is oriented exactly in the direction of axle Z, perpendicular to the cutting face 26 around which the cutting tool 106 rotates. In this way, the length of the blade edge 108 only has to be longer by a short safety distance,-reference number 112,-measuring approximately 2-3 mm longer than the pile of material 24a to be cut. In this way, it is assured that along the full length, the blade does not penetrate the base of the cutting surface 26; see Figure 1.
According to a second example of the invention, cutting tool 116 is used in a different way, principally, when few layers of cloth are to be cut. This cutting tool 116 is shown in Figure 5 and has one blade edge 118, which is located under a slight cutting angle a regarding the cutting surface 26. This angle is smaller than the right angle, which is formed by the edge 108 in Figure 4, regarding the cutting surface 26. This arrangement makes the cutting easier and enhances the movement of the tool.
Although it may depend on the cutting to be done, the cutting tool can vary, the drive in the form of a transducer 30 (emitter) is the same, see Figure 7. By means of the transducer, the cutting tool is started vibrating from 20 to 40 Khz, with amplitudes of from a few hundreths to a few tenths of a millimeter, with higher or lower intensities, depending upon the material and the height of the cut, utilizing for this process the general principles of an ultrasonic procedure, as is, in itself, already known. For this purpose, an ultrasonic generator 31 (Figure 1) is provided for, not shown in greater detail, which generates a sequence of electrical signals, which are transmitted by means of a cable 32 (Figures 6 and 7) and a so-called convertor 34 of the transducer, which convert the electrical signals into mechanical vibrations, which are transmitted to a booster 36, which has the special shape as seen in Figure 7. A booster of this type is a mechanical amplifier. Lastly, the transducer 30 also includes a "Sonot- rode" 38, on which the cutting tool is mounted. Here, ultrasonic energy is used. One part of this is represented by the blade. The geometric forms can also vary regarding the shape shown, depending upon the cutting tool, to thus achieve an ideal adaptation, the booster and the Sonot- rode thus form a coupling element.
In Figures 6 and 7, further details of the cutting head are shown. In these Figures, a motor 60 is provided, which serves to adjust the blade around axle Z. The motor 60 drives the cutting group defined in conjunction with 73 by means of cogwheels 63 and 65, see Figure 7. For this purpose, the cogwheel 65 used as a pulley is joined to a hollow axis 67, rotating in a housing on the ball bearings 69 and 71, which, in turn, are located on the crossbar 66 of the unit 73. The crossbar 66 is joined to the Y-carrier 62, see also Figure 3. A carrier 75, working in an up and down movement, mounted on a crossbar 61, positioned on the cogwheel 65, supports the ultrasonic emitter or transducer 30 and can be moved by means of a cylinder 77. The cutting head 81 is thus moveable in the X- or Y-direction by means of X-and Y-carriers, described in relation to Figure 3; and in direction Z, funadamentally only the cutting tool, by means of Z-carrier 75, previously described in relation to Figure 7, while the rotation of the cutting tool around axle Z takes place by means of the motor 60.
The control commands in the control apparatus 18 must be set in such a way that the rotation around axle Z is not over 360° or 2x360°, for the purposes of avoiding a crossing of the cables and feeder lines; to the contrary, rotating joints would have to be used. However, the cutting head has to be able to move within these limits and with a free-run movement-for this purpose, without any cutting movements-to adopt the 0° position.
Although the possibility does also exist of using sliprings as couplers for the cables and feeder lines.
The cutting head, according to Figure 7, also has a presser bar (79), by means of which the material to be cut, for example a cloth, is pressed down slightly, by the action of a spring 83 against the cutting surface 26. The pressure bar is mounted on the hollow axle 67 in the area of the passing blade 106. The spring 83 is supported by a base 89, also mounted on the hollow axle 67.

Claims

1. Apparatus for cutting sheet material (24) having one or several layers, comprising a cutting table (26) equipped with a vacuum (40) installation for holding the material in place, a slide device (49, 62) moving lengthwise (X-direction) and crosswise (Y-direction) of the cutting table as carrier of an ultrasound driven cutting tool unit (73), movable in a direction (Z-direction) perpendicular to the cutting table (26), the movements of the slide device along the cutting lines are controlled by means of a data processor (18) which processes the marking data and the data control and an air-permeable synthetic fiber base on the cutting table as support surface for the material to be cut, whereby the ultrasonic cutting unit (73) comprises a cutting tool (106) with a cutting edge (108, 118), a coupling element (38), an ultrasonic emitter (30) and a converter (34) which are connected to a carrier (75), said carrier is up and down movably supported, characterized in that the carrier (75) is mounted on a disc in form of a cogwheel (65) having a hollow central sleeve (67) as bearing which surrounds the coupling element (38) of the cutting tool and is rotatably mounted around said Z-direction on a crossbar (66) joined to the carrier Y (49) of the slide device of the apparatus, that the cutting tool (108, 118) is mounted to said converter (34) and having a blade stroke between a few hundreths to a few tenths of a millimeter, and that the fiber base (28) on the cutting table consists of individual fibers which are approximately 0.5 mm in diameter and 5 mm in length.

2. Apparatus according to claim 1, characterized in that the ultrasonic cutting unit (73) comprises a cutting tool (106) with a cutting edge (108) perpendicular to the surface of the cutting table (26) and that said cutting tool (106) is connected to the ultrasonic emitter (30) such that one of its cutting edges (108) of the cutting tool (106) is oriented exactly in the Z-direction.

3. Apparatus according to claim 1, characterized in that the up and down movement of the carrier (75) is generated by a cylinder (77) which is connected to the cutting unit (73).

4. Apparatus according to claim 1, characterized in that the hollow sleeve (67) on its free end is fitted with a springboard presser bar (79), the central area of which can be passed by the cutting tool (106).

5. Apparatus according to claim 1, characterized in that the fiber base (28) is supported by a nonstop conveyor belt guided over the cutting table (26).