EP0145527A2 - Fluid-jet cutting machine for webs - Google Patents

Abstract

Strip material cutting machine (30) by high pressure fluid jet. The cutting nozzle (22) moves in a direction (Y) perpendicular to the length of the strip, the latter being driven in both directions by a device (44), in a direction (X) parallel to its length. Pieces (32) of any shape can thus be cut. A transparent tunnel guides the strip on the table (36) upstream of the nozzle (22). The jet recovery (76) is equipped with a wear detector and slides tightly under a false table pre-cut by the jet. A photoelectric barrier (120), activated when a part is cut, detects it and stops the conveyor (40) so as to allow the part to be gripped.

Description

The present invention relates to a machine intended for cutting a strip material along any line by means of a high pressure fluid jet.

We know machines for cutting a work or a piece whose dimensions do not exceed those of the table that supports them. In such machines, the cutting can be obtained either by the combination of a transverse displacement of the cutting tool with a longitudinal displacement of the table supporting the workpiece, or by a transverse and longitudinal displacement of the cutting tool, the table then being fixed. A machine of this second type is described in French Patent No. 1,479,158.

In these two types of machine, it is possible to cut a part along any line. However, the table must be either longer or as long as the work to be cut, which leads to a very large footprint when cutting very long pieces and to significant downtime during the manufacture of certain pieces in series, since it is necessary to change the structure between each cutting operation.

The subject of the present invention is precisely a cutting machine which does not have the drawbacks of the machines of the prior art and which makes it possible in particular, for a reduced bulk, to cut a work in the form of a strip, which allows cutting parts of any length and mass production of parts at an accelerated rate, by simply advancing the strip.

To this end, the machine for cutting strip material by high pressure fluid jet according to the present invention comprises a substantially flat bearing surface capable of supporting said strip material, a cutting nozzle emitting a jet of fluid under high pressure. pressure towards said strip material, means for moving the nozzle in a direction Y perpendicular to the length of the strip, characterized in that it further comprises means for moving the strip material in both direction in a direction X parallel to the length of the strip, so that the combined movements of the strip material and of the nozzle make it possible to make cuts of any shape over any length of said strip material.

It is understood that the combination of the movements of the nozzle and of the strip itself makes it possible to obtain any form of cutout contained in the width of the strip, without limitation of length. In addition, there is practically no more dead time between the cutting of successive parts.

Since the material to be cut is generally wound and may have a certain stiffness, it may tend to keep a slight curvature when it moves on the machine. This is undesirable both because the strip material thus risks catching on certain parts of the machine and because the precision of the cut risks being reduced. For this reason, it is also offered in accordance with

the invention of producing the bearing surface of the machine, upstream of the cutting nozzle and on either side of the means for moving the strip material, in the form of a fixed table on which the latter is moves inside a guide tunnel.

Since the material to be cut can in particular be a prepreg composite material whose protective sheet, or separator, covering the underside is generally removed to facilitate subsequent use of the cut and reduce the time of implementation thereof, this underside may be sticky. When the strip material moves inside the tunnel, it is therefore desirable to prevent its underside from adhering to the fixed table. For this reason, means can be provided to create a fluid cushion between said table and the strip material.

Preferably, in order to allow visual control of the cut, taking into account that the strip material can move in both directions, the tunnel is transparent.

Conventionally, the cutting machine according to the invention comprises a system for recovering the jet placed opposite the cutting nozzle, on the other side of the material to be cut. In accordance with another aspect of the invention, this system comprises, in the path of the jet, at least a first metal plate ensuring the dislocation of the jet and a device for detecting wear of this plate comprising a normally sealed cavity located in- below said plate and the lower wall of which comprises at least one other metal plate struck by the jet when the first plate is pierced, and means for detecting the arrival of the jet in said cavity.

Preferably, these latter means comprise an electrical circuit comprising an indicator, the implementation of which is controlled by the closing of said circuit resulting from the contacting of said other wafer and of an electrode located in the cavity, when the jet of fluid happens in this one.

In order, both to confine the noise which occurs in the recuperator inside of it, and to prevent that the vapors formed during the dislocation of the jet do not escape upwards, the surface support preferably comprises, between the nozzle and the jet recovery system, a false stationary table having a slot substantially the width of the jet emitted by the nozzle, this slot being preferably cut directly in the table by the jet. The jet recovery system, which moves at the same time as the nozzle, then comprises at its upper end in contact with the table a seal having a reduced coefficient of friction with the latter.

It is thus possible to eliminate the vapor suction system generally provided in this type of generator, the dislocated fluid being evacuated by gravity.

According to yet another aspect of the invention, the machine according to the invention comprises automatic control means of the means for moving the nozzle and means for moving the strip material, in order to ensure the cutting in the latter of parts and of scraps, the bearing surface comprising, downstream of the cutting nozzle, at least one conveyor belt, the advance of which feeds the scraps to a means for removing scraps of the cut material, and detection means presence of a part on said conveyor belt controlling its stopping, said detection means being respectively activated and deactivated by said automatic control means, depending on whether they cut a part or a fall, in order to control the stop of the conveyor belt to allow the gripping of the parts and to convey the falls without stopping the belt to said means for evacuating falls.

In this case, a second conveyor belt, the advance of which is controlled automatically, for a determined time, by the automatic control means. that, after the cutting of a part or a drop, can be placed between the cutting nozzle and said conveyor belt in order to facilitate the cutting of the material into a strip.

• - la figure 1 est une vue en perspective représentant de façon schématique une machine de découpe réalisée conformément à l'invention,
• - la figure 2 est une vue en coupe transversale schématique de la partie de la machine située en amont de la buse de découpe,
• - la figure 3 est une vue en perspective à plus grande échelle et en coupe partielle montrant notamment le système de récupération placé en vis-à-vis de la buse de découpe, et
• - la figure 4 est une vue de dessus illustrant de façon schématique le fonctionnement de la machine, selon que l'élément découpé par celle-ci est une chute ou une pièce.

A preferred embodiment of the machine according to the invention will now be described, by way of nonlimiting example, with reference to the appended drawings in which:

• FIG. 1 is a perspective view schematically showing a cutting machine produced in accordance with the invention,
• FIG. 2 is a schematic cross-sectional view of the part of the machine located upstream of the cutting nozzle,
• FIG. 3 is a perspective view on a larger scale and in partial section showing in particular the recovery system placed opposite the cutting nozzle, and
• - Figure 4 is a top view schematically illustrating the operation of the machine, depending on whether the element cut by it is a scrap or a part.

Referring first to FIG. 1, it can be seen that the cutting machine according to the invention comprises three separate parts constituted by an electromechanical execution assembly 10, a control assembly 12 and a source of fluid under very high pressure 14. These three sets can be physically separated from each other as illustrated in the figure.

The control assembly 12 comprises a digital control 16 and a control bay 18. It is connected to the electromechanical assembly 10 by connection cables 20.

The source of fluid under very high pressure 14 is constituted by a high pressure group deli vrant in the most common case of water under very high pressure which is conveyed to the cutting nozzle 22 of the assembly 10 by a pipe 24.

The electromechanical execution assembly 10 comprises a frame 26 supporting at one of its ends a coil 28 of a strip material 30, to be cut into pieces 32 whose shape can be any. The reel 28 is mounted on an axis 34 which can rotate freely on the frame 26, so as to allow the unreeling of the strip 30.

The horizontal upper face of the frame 26 constitutes a bearing surface formed, from the end of the frame carrying the coil 28 to the opposite end, of a fixed table 36, of a first endless conveyor of small length 38 and a second endless conveyor 40 of greater length. The width of these various elements constituting the bearing surface on which the strip 30 is received is slightly greater than the width of the latter, in particular in order to allow the strip to be guided on the table 36.

Furthermore, the frame 26 supports, from the end carrying the reel 28 to its opposite end, a device 42 for unwinding the strip 30, a device 44 for advancing and guiding the strip on the table 36, a cutting device 46 located between the table 36 and the first conveyor 38 and a device 48 for sorting and evacuating scraps allowing the gripping of the pieces.

The unwinding device 42 comprises a rubberized roller 50 frictionally driving the reel 28. For this purpose, the roller 50 is fixed on an axis 52 parallel to the axis 34 of the reel and this axis 52 is mounted rotating at the end an articulated arm (not shown) whose opposite end is articulated at the turn of a fixed axis 54. The rubberized roller 50 is thus pressed against the coil under the action of gravity, possibly reinforced by the action of elastic means (not shown).

Two belts 56 and 58 mounted on appropriate pulleys serve to transmit to the shaft 52 carrying the roller 50 the rotational movement of an axis 60 of the device 44 for advancing the strip, passing through the fixed axis 54.

The device 44 for advancing and guiding the strip 30 comprises a drive roller 62 mounted on the axis 60 of a motor 64, above the strip 30. A metal roller 66 is placed below the strip 30 in a notch of the table 36, so that its upper generatrix is flush with the upper face of the latter, as illustrated in FIG. 2. The axes 60 and 68 of the roller 62 and of the roller 66 are parallel to the axis 34 of the coil 28 and situated in the same vertical plane, so as to press the strip 30 therebetween. This result is obtained by applying the roller 62 against the metal roller 66 with a determined pressure, using means known (not shown). An encoder or counter 70 is associated with the metal roller 66 in order to determine the number of revolutions of the latter and therefore the length of the strip which runs on the table 36.

In accordance with an essential characteristic of the present invention, the motor 64 serving to control the advance of the strip 30 on the table 36 can move this strip parallel to its length in either direction by means of the mechanism which has just been described, as illustrated by the arrow X in FIG. 1.

We have seen that the belts 56 and 58 allow the motor 64 to simultaneously rotate the roller 50 and roller 62. The diameters of these rollers as well as the diameters of the pulleys on which the belts are received are chosen so that the peripheral speeds of the two rollers are equal to each other. Thus, the device 44 for advancing the strip does not have to overcome the inertia of the reel 28, but only that of the portion of strip lying between the roller 50 and the cutting device 46 and that of the rigid roller. 66.

As illustrated in FIG. 1, precise positioning of the strip in the direction X is obtained by holding it against a selvedge guide 71 disposed along one of the longitudinal edges of the table 36.

To take account of the fact that the strip material 30 to be cut may have a certain rigidity, provision is made in a preferred embodiment of the invention to maintain the strip on the table 36, in order to avoid that the strip does not retain a certain curvature, which would risk both very significantly reducing the precision of the cutting and leading to incidents such as the hanging of the strip on certain projecting parts of the machine.

As shown schematically in FIG. 2, good flatness of the unwound strip is obtained in the cutting area by placing on the table 36 a tunnel 72 comprising a notch for the passage of the roller 62.

When the strip material to be cut is a prepreg composite material, the latter is generally stored in continuous strip in the tacky state between two sheets called separators. When the strip of composite material is unrolled for cutting, the separator which covers the underside of the strip, that is to say the side facing the plate of the machine, is removed in order, on the one hand, to facilitate the subsequent use of the blank and, on the other hand, to reduce the handling times of the blanks. Indeed, if the two separators remained in place, the operator would have to turn over the cut to remove the second separator and would risk leaving pieces, in his precipitation, pieces which would adversely affect the quality of the composite.

Given this remark, in a preferred embodiment of the invention, the machine further comprises orifices 74 formed in the table 36 along a substantially median axis, as illustrated in FIG. 2. These orifices are supplied with air compressed, which allows to permanently create between the table and the band 30 an air cushion preventing the latter from coming to adhere to the table. Thus, the precision of the movement of the strip 30 along the axis X is not affected. It should be noted that the air cushion created between the strip and the table 36 tends to move the strip away from the table, but that this movement is limited by the tunnel 72.

Preferably, the tunnel 72 is transparent, so as to allow visual control of the cutting operations.

The cutting device 46 comprises, in known manner, a cutting nozzle 22 disposed vertically above the strip 30 and a jet recovery system 76 disposed below the strip, opposite the nozzle 22. The nozzle 22, like the recovery system 76, are mounted on transverse guide columns 78 and 80 parallel to the axis 34 of the roller 28. A motor 82 allows, by means of pulleys and suitable belts designated so general by the reference 84, to move the nozzle 22 and the recuperator 76 along their guide column respec tive in one direction or the other, so that they remain permanently opposite one another. The transverse displacement thus obtained is designated by the arrow Y in FIG. 1.

In accordance with an essential characteristic of the invention, it can be seen that it is possible, by simultaneously controlling the operation of the motors 64 and 82 using the digital control 16 according to an appropriate program, to cut from the band 30 parts 32 of any shape and size, within the limits of the width and length of the strip, by means of an electromechanical assembly 10, the dimensions of which may remain relatively small. The machine according to the invention also makes it possible to carry out in series the cutting of a large number of parts according to a determined program and without loss of time.

Referring now to Figure 3, we see that the recovery system 76 of the jet delivered by the nozzle 22 is placed below a false table 86 extending the table 36 and having a slot 88 whose width is substantially equal to the width of the jet leaving the nozzle 22. In order that the width of the slot 88 is as small as possible and that this slot is placed exactly in alignment with the jet, the false table 86 is preferably made in a material capable of being cut by the jet, such as a plastic, and the slot 88 is cut from this material by the jet itself.

The recovery system 76 comprises in its upper part a tube 90 of vertical axis carrying at its upper end a cylindrical seal 92 made for example of felt in order to have a coefficient of friction as low as possible with the false table 86 The seal 92 is drilled in the center of a hole 94 of appreciable diameter equal to the diameter of the jet. This seal thus allows, in combination with the false table 86, to confine as much as possible the noise inside the recovery system and to prevent the water vapor formed in it from escaping. by its superior end.

Conventionally, after having traveled a certain distance inside the tube 90, the jet is dislocated on a horizontal plate 96 of sintered metal fixed at the bottom of the tube. Holes 98 formed in the tube 90 above the plate 96 allow the water vapor formed by the dislocation of the jet to flow by gravity to a pipe 100. It will be noted that the presence of the false table 86 and of the gasket 92 make it possible to avoid any risk of escape of the water vapor from the top of the tube, so that it is no longer necessary as in the devices of the prior art to provide additional means to suck the water vapor formed by the dislocation of the jet on the wafer. The noise of the machine is thus further reduced, as well as its cost.

According to a preferred embodiment of the invention, the recovery system 76 further comprises means 102 for detecting the piercing of the wafer 96 by the jet. These means consist of a chamber 104 formed at the lower part of the tube 90, below the plate 96 and normally sealed. The lower partition of this chamber 104 has in its central part a second plate 106 also made of sintered metal, as well as an electrode 108 separated from the plate 106 by a block 110 of an electrically insulating material. The plate 106 and the electrode 108 are mounted in an electrical circuit (not shown) further comprising an indicator wear plate 96 and a source of electrical voltage.

When the plate 96 is pierced by the jet of fluid emitted by the cutting nozzle 22, the water passes through the chamber 104 and strikes the plate 106 which ensures its dislocation. The water thus admitted into the chamber 104 brings the wafer 106 into contact with the electrode 108, which has the consequence of closing the electrical circuit and energizing the indicator. It should be noted that the detection of the piercing of the plate 96 is thus practically immediate and is carried out without a single drop of water being discharged outside the recovery system 76.

As mentioned previously, the false table 86 is extended by a first conveyor belt 38, the implementation of which is controlled by a motor 116. A second conveyor belt 40 extends the band 38 and is controlled independently of it by a second motor 118. The device for sorting and evacuating scraps 48 comprises a means for detecting the pieces 32 constituted by a photoelectric barrier 120 placed at the end of the conveyor belt 40 situated at the end of the assembly 10. It further comprises a receiving tray 122 placed below the end of the conveyor 40, so as to receive the scraps conveyed by the latter.

According to a preferred embodiment of the invention, the various motors 64, 82, 116 and 118 as well as the light barrier 120 of the electromechanical assembly 10 are controlled by the control assembly 12, so that the cutting of the 32 pieces are made according to a determined program, that the falls resulting from this cutting fall automatically- ment in the tray 122 and that the conveyor 40 stops when it supports a part 32.

So that the device 48 can sort between the pieces and the scraps, the digital control 16 is designed so that it sends an activation order of the light barrier 120 when it orders the cutting of a piece in the strip 30 by means of the motors 64 and 82 and that it sends an order to deactivate the light barrier 120 when it controls the cutting of a drop in the strip material.

In view of this last remark, the operation of the machine is as follows.

The control assembly 12 continuously sends, according to a program determined in advance, orders to cut the pieces and falls in the strip 30. These orders result in combined movements of the cutting nozzle 22 and the strip to be cut respectively in directions Y and X, leading to the successive cutting of parts and scraps according to this program.

Each time the cutting of an element is finished, whether this element is a part or a fall, the control assembly 12 starts the motor 116 which was previously stopped during the cutting. The part or the scrap is thus conveyed by the conveyor 38 to the conveyor 40, after which the conveyor 38, whose motor 116 is supplied in a timed manner, stops.

The motor 118 of the conveyor 40 is normally supplied continuously from the control assembly 12, so that the part or the scrap whose cutting has just been completed is transported to the end of the conveyor belt 40. At this stage, and as shown schematically in Figure 4, two cases must be distinguished.

In the first case, the element which is on the conveyor 40 is a fall 33. We have seen previously that in this case, the photoelectric barrier 120 is deactivated. The barrier therefore does not detect the passage of the fall, so that the motor 118 remains energized and the fall falls at the end of the conveyor 40 in the tank 122.

In the opposite case where the element which has just been cut is a part 32, the light barrier 120 is activated, so that it immediately detects the part when it reaches its level. This detection has the immediate effect of stopping the engine 118 and, consequently, the conveyor 40. The gripping of the part can then be carried out by any means, that is to say both manually and by a device appropriate automatic handling. This grip is represented schematically by the arrow 123 in FIG. 4.

As soon as the part is removed from the conveyor 40, the signal emitted by the light barrier 120 disappears and the motor 118 again controls the advance of the conveyor 40 until the arrival of a new part which will in turn be detected by the photoelectric barrier.

Of course, the invention is not limited to the embodiment which has just been described by way of example, but covers all the variants using known equivalent means.

Claims (10)

1. Machine for cutting strip material (30) by high pressure fluid jet, comprising a substantially planar support surface (36, 38, 40) capable of supporting said strip material, a cutting nozzle (22) emitting a jet of fluid under high pressure towards said strip material, means (82) for moving the nozzle in a direction (Y) perpendicular to the length of the strip, characterized in that it further comprises means (44) for move the strip material in either direction in a direction (X) parallel to the length of the strip, so that the combined movements of the strip material and the nozzle allow cuts to be made any shape over any length of said strip material, said bearing surface comprising, upstream of the cutting nozzle (22) and on both sides of the means (44) for moving the strip material, a table fixed (36) on which the latter moves inside a guide tunnel age (72). 2. Machine according to claim 1, characterized in that means (74) are provided for creating a fluid cushion between said table (36) and the strip material (30). 3. Machine according to any one of claims 1 and 2, characterized in that the tunnel (72) is transparent. 4. Machine according to any one of claims 1 to 3, characterized in that it further comprises a system (76) for recovering the jet placed opposite said nozzle (22), on the other side of the material to be cut, said system comprising, in the path of the jet, at least a first metal plate (96) ensuring the dislocation of the jet and a device (102) for detecting wear of this plate comprising a normally sealed cavity (104) located below said plate and the lower wall of which comprises at least one other metal plate (106) which strikes the jet when the first plate is pierced, and means (108) for detecting the arrival of the jet in said cavity. 5. Machine according to claim 4, characterized in that the means for detecting the arrival of the jet in the cavity comprise an electric circuit comprising an indicator whose implementation is controlled by the closing of said circuit resulting from the contacting of said other wafer (106) and an electrode (108) located in said cavity (104), when the fluid arrives therein. 6. Machine according to any one of claims 4 and 5, characterized in that the means (82) for moving the nozzle (22) in the direction (Y) act simultaneously on the jet recovery system (76), to keep it permanently opposite the nozzle, said bearing surface comprising, between the nozzle and the jet recovery system a false fixed table (86) having a slot (88) substantially the width jet emitted by the nozzle, the jet recovery system comprising at its upper end in contact with the table a seal (92) having with the latter a reduced coefficient of friction. 7. Machine according to claim 6, characterized in that the false fixed table (86) located between the nozzle (22) and the system (76) for recovering the jet is made of a material capable of being traversed by the jet, such that said slot (88) is cut directly into the table by the latter. 8. Machine according to any one of the reven dications 6 and 7, characterized in that the system (76) for recovering the jet comprises means (100) for evacuation by gravity of the fluid dislocated by said first wafer. 9. Machine according to any one of claims 1 to 8, characterized in that it further comprises means (12) for automatic control means (82) for moving the nozzle and means (44) for moving the material in a strip, in order to ensure the cutting in the latter of parts (32) and scraps (33), said bearing surface comprising, downstream of the cutting nozzle, at least one conveyor belt (40), the advance routes the scraps to a means (122) for removing scraps of the cut material and means (120) for detecting the presence of a part (32) on said conveyor belt controlling the stopping thereof , said detection means being respectively activated and deactivated by said automatic control means, depending on whether they cut a workpiece or a scrap, in order to control the stop of the conveyor belt (40) to allow the gripping the pieces and routing the scraps without stopping the belt until the mean evacuation audit (122) uation of falls. 10. Machine according to claim 9, characterized in that said bearing surface comprises, between the cutting nozzle (22) and said conveyor belt (40), a second conveyor belt (38) whose advance is automatically controlled by said automatic control means (12), after the cutting of a workpiece (32) or a fall (33), for a determined time.

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