REFERENCE TO RELATED APPLICATION
This application claims the benefit of Swiss Patent Application No. CH-1476/04, filed Sep. 6, 2004, the entire disclosure of which is herein incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
The invention concerns a method for the holding of sheet metal strips which are output simultaneously from a cutting device in essentially their output relative positions and which pieces, by letting them fall from the holding device, are transferred to a conveyor mechanism. The invention further concerns a corresponding device as well as a scissor shears which includes the holding device or performs the holding method.
STATE OF THE ART
In the cutting of sheet metal plates into strips by means of rotating knives the cut strips lie practically next to one another as they are output simultaneously from the cutting device. To permit an ordered transfer of the strips to a conveyor mechanism it is known, from Italian Patent IT-A-1 053 021 to hold the strips by rotatable rods against which the strips lie at their lower faces in essentially their relative output positions from the rotating knives, and also slightly inclined. By the rotation of the rods the strips then fall onto the repository plane of a conveyor means having chains running upwardly at an incline and having projecting shagging catches, which catches project from below and through the repository plane and deliver the strips which lie close to one another in the repository plane in spaced condition to the rotary knives of a scissor shears. The rotary rods must be oriented exactly parallel to one another to hold the sheet metal strips and to give them away freely. With each change in the width of the strips the rotary rods also have to be adjusted and their parallel condition has to be tested and adjusted, which is expensive to do.
BRIEF DESCRIPTION OF THE INVENTION
The invention has as its basic object the avoidance of the above-mentioned disadvantages.
This object is achieved with the previously mentioned method in that the sheet metal strips at their upper faces are held magnetically and/or by suction. In particular, the holding preferably takes place exclusively at the upper faces of the sheet metal strips.
Accordingly, since the strips are held at their upper faces magnetically and/or by suction, the need for holding the strips exactly parallel with their edges disappears; and it is sufficient if the holding device is engaged with each strip upper surface so that each strip—until it is let free to fall—is held essentially in the position in which it has been output from the cutting device. The free fall then occurs in a simple way by the deactivation of the electromagnetic holding device and/or by a mechanical operation on the strip to overcome the permanent magnet holding force, or by deactivation of the suction pressure, by means of which the sheet had been held against an opposing surface.
Preferably the holding is achieved electromagnetically and by means of rolls against which each strip moves at its upper side, it is discharged from the cutting device. Also magnetic rails, preferably with friction reducing coatings for the strips, may be used. In the case of pneumatic holding by means of suction pressure, surfaces with suction openings and friction reducing coatings are also preferred. Also preferred is a stationary holder (that is, the rollers are stationary, since their roller axes are stationary), along which holder the involved sheet metal strips move. This provides a simple and robust holder without a special motion driver.
The mentioned advantages are further achieved by a holding device for a scissor shears according to claim 9 and by a scissor shears according to claim 17.
BRIEF DESCRIPTION OF THE DRAWINGS
Further developments, advantages and uses of the invention will be apparent from accompanying claims and from the following description aided by the figures. The figures are:
FIG. 1 a schematic view from the front into the first cutting device of a first embodiment of the invention;
FIG. 2 a side view of the embodiment of FIG. 1;
FIG. 3 a side view of a further embodiment; and
FIG. 4 a view of a third embodiment of the invention in partially cut away form.
WAYS FOR CARRYING OUT THE INVENTION
FIGS. 1 and 2 show different views, in highly simplified illustration, of a scissor shears 1 by means of which sheet metal plates 20 are cut in a first cutting device 2, which as a rule has several pairs of slicing rolls, into sheet strips 21, 22, 23 and 24. In FIG. 2 it can be easily seen how a sheet metal plate 20, which is lifted from a plate stack 4, moves through the cutting device 2 and is discharged by the output rolls 16 and 17 in the direction of the arrow A as sheet metal strips 21.
FIG. 1 is a frontal view looking into the cutting device 2 with the output direction of the arrow A being perpendicular to the viewing plane and running away from the observer. From FIG. 1 it is seen that four sheet metal strips 21, 22, 23 and 24 are cut from the sheet plate. This number and the size of the sheet strips is naturally only exemplary and depends on the number and the spacing of the roller knife pairs of the cutting device 2. According to the preferred use of the holding device in a scissor shears 1, these sheet strips are now delivered to a further cutting device 3, which usually is arranged at a right angle to the cutting device 2, wherein the sheet strips 21-24 are cut one after another into small sheet sections 40. For this a conveyor device 14 conveys the sheet strips 21-24 from the repository 13 to the cutting device 3. Such a scissor shears and also the associated conveyor device are well known to a person skilled in the art and need not be explained in more detail here. For more details reference can especially be made to Italian Patent IT-A-1 053 021, wherein a person skilled in the art is shown a scissor shears of the previously mentioned kind and a conveyor device with conveying chains running at an upward incline and having catches of different heights, which conveyor device is preferably used also in the case of scissor shears having a holding device according to the present invention, as yet to be further explained hereafter.
The present invention concerns now the holding of, or a holding device 10, 10′ or 10″ for, the individual sheet metal strips which simultaneously leave the first cutting device 2, before their transfer to the conveyor device 14, so that they are held above the conveyor device and so that an orderly transfer of the strips to the conveyor device takes place. The sheet strips according to the state of the art, for which reference is again made to the mentioned Italian Patent, are held by specially shaped rotary rods on which the sheet strips lie at the edge regions of their bottom faces. As already explained, these rotary rods are rotated to effect the discharge of the strips onto a receiver of the advancement means, from which receiver the strips are taken hold of by the conveyor means and delivered to the second cutting device 3. The present invention concerns the taking and holding of the sheet strips 21-24 during and after the discharging of the sheet strips from the first cutting device. According to the invention a holding of the sheet strips at their upper faces and preferably only at their upper faces takes place so that no holding element works on the underfaces of the sheet strips. However, in addition to the holding of the strips from above, auxiliary elements can also be provided which, for example, face the underfaces to additionally support the strips and which are moved away to allow the strips to fall. The holding on the upper faces of the strips occurs magnetically and/or pneumatically by suction. A first embodiment is preferred wherein the holding device 10 accomplishes the holding by magnetic rolls along which the involved strips move when they leave the cutting device 2. In FIG. 2 it is seen how the strip 21 moves in the direction of the arrow A in leaving the cutting device 2 and how it moves along the rolls 6a-6e, such that the strip in the position shown in FIG. 2 has already reached the rolls 6a, 6b and 6c. Because of the magnetic effect of the magnetic rolls the strip in its discharge position will be held over the receiver 13. If permanent magnet rolls are used, the release of the sheets 21-24 in the direction of the arrow B from the respectively associated roll sets 6-9, which are visible in the front view of FIG. 2, is effected by mechanically overcoming the holding force of the rolls. As to this, for example, the rolls can be moved upwardly in their own indicated roller carrier 5, so that the rollers are lifted from the respectively associated sheet strips which are held back by the roll carrier 5 or by nonmagnetic projections on the roller carrier, so that the movement of the rollers upwardly cannot take the strips with the rollers. Also a moveable element can be provided which presses the sheet strips downwardly from the rolls. However preferably the rolls are electromagnetically activateable so that by switching on the current creating the magnetic field, a magnetic holding of the sheet strips to the rolls is effected and by the turning off the current a dropping of the strips to the receiver 13 is effected. In FIGS. 1 and 2 this is illustrated by a corresponding electromagnetic arrangement 11 which is controlled by the control circuitry 27 of the scissor shears. The associated development of such an electromagnetic roll arrangement is within the ability of the person skilled in the art and need not be here described in more detail. As already mentioned the other sheet strips 22-24 are also held by corresponding roll sets 7, 8 and 9, so that all sheets which leave the cutting device 2 are held in the corresponding way above the receiver 13 and can be dropped as desired for further advancement. The rolls as a rule are driven only by the strips which are moved along them from the cutting device, or as the case may be, by driven output rollers 16, 17. However the rolls can also be driven by motor, which serves for all of the rolls or for only one or several rolls.
FIG. 3 shows a further embodiment of the invention as a holding device 10′, in the case of which only a side view of the scissor shears similar to that of FIG. 2 is shown, and wherein the same reference numbers indicate the same elements as in FIG. 2. In place of each roll set, in this embodiment a magnetizable rail 30 is provided over which the associated strip slides when it is output from the cutting device 2 and which rail holds the strip while it is magnetized by the associated electromagnet arrangement. So that the strip 21 can be pushed over the rail 30 without large frictional resistance with its upper side which rail for example is arranged in a rail holder 35, the rail 30 at its contact surface with the metal strip is provided with a friction reducing coating, for example a plastic material coating. Also a combination of the embodiments of FIGS. 1 and 2 as well as FIG. 3 is possible so that some of the strips are held by roll sets and other strips are held by rails. In the case of the rolls sets it is not necessary that all of the rolls have a magnetic effect, and also some of the rolls can be made for example as plastic rolls, and similarly the rails can also have some sections made of plastic and other sections made of metal.
FIG. 4 shows a further embodiment of the invention as a holding device 10″, in the case of which the holding of the sheet material strips is effected from above by suction, so that each strip is sucked against the carrier 36. For this purpose a single carrier 36 can be provided for each strip or a single carrier can be used for all of the strips in common, which likewise is true for the roll or rail carriers. At its outer surface 38 the carrier 36 has a number of openings 37 through which air is sucked into the carrier by means of a suction pump 31. A sub-atmospheric pressure therefore exists in the carrier 36 which holds the associated strip 21 to the carrier. The forward shifting of the strip can again be made easier by a low friction coating on the outer surface of the carrier 36 which overlies the upper surface of the strip 21. By shutting off the suction pump 31, which can again be controlled by the non-illustrated control, dropping of the strip 21 onto the receiver is effected.
The preferred implementation of the advancing means 14 is that which is shown in the mentioned Italian patent and which includes an inclined chain run and catches of different heights which project through the discharge plane 13 and effect an separation of the strips lying tightly next to one another on the receiver 13. However, instead of this advancing means some other desired advancing means known to experts in the art can also be used.
Although in the present application preferred embodiments of the invention have been described, it is to be understood that the invention is not limited to these embodiments and that the invention can be carried out by other ways and means falling within the scope of the following claims.
Patent Application
20080022819
