Conveyors: power-driven – Conveyor section – Having means to enhance the friction or adherence between...
Reexamination Certificate
1998-07-24
2003-07-08
Valenza, Joseph E. (Department: 3651)
Conveyors: power-driven
Conveyor section
Having means to enhance the friction or adherence between...
C198S690100, C271S018100, C271S094000, C271S193000, C271S197000, C271S276000
Reexamination Certificate
active
06588580
ABSTRACT:
The invention relates to an apparatus for the transport of workpieces, in particular of suspended, panel-shaped workpieces, such as sheets or plates, with at least one rotationally driven conveyor belt for the workpieces to be laid onto the latter, and with a holding device, past which the conveyor belt is led, the holding device retaining the workpieces on the conveyor belt by means of a magnetic field passing through the conveyor belt and/or by generating a vacuum at suction orifices of the conveyor belt.
The general procedure for conveying workpieces, in particular for the suspended transport of sheets or plates, is, after the sheet has been unwound from a coil, to cut it by means of sheet shears into panels to be further processed. These panels are delivered to a feed conveyor, from which they are received by means of the apparatus initially described. After being transported, the sheets or plates are discarded at desired locations and form stacks for packages on lifting tables. Further processing subsequently takes place, for example, in bending devices or molding presses.
An apparatus in the embodiment initially described became known from DE-C-196 14 741. The set purpose, here, was to allow suspended or supported transport or conveyance of magnetic and nonmagnetic workpieces at high speeds. To this effect, the known teaching provides a combined vacuum/magnet system (VMS) which has at least one magnet arranged adjacent to the transport band and a vacuum duct connected to a vacuum source. This vacuum duct is connected to the suction orifices of the transport band or conveyor belt via suction lines passing through the magnet. The conveyor belt, provided with ferromagnetic inserts, is guided in appropriately shaped guide strips on the magnet. Said conveyor belt is provided, on its side facing the workpieces, with a plurality of successively arranged annular elevations, on which the workpieces bear. Consequently, according to the prior art, one and the same conveyor belt is used for transporting both ferromagnetic and nonferromagnetic workpieces. Moreover, in general, both the vacuum system and the magnet system are in operation, in order to ensure that the workpieces are pressed particularly effectively onto the surface of the transport band. A vacuum is therefore employed even in the conveyance of ferromagnetic workpieces.
The known procedure or the previously published apparatus is often merely a compromise, on the one hand, as regards the ability to suck up workpieces by means of a vacuum and, on the other hand, as regards the outlay in terms of construction. Thus, in the case of the so-called flat seals used according to the prior art, problems may arise on the conveyor belt with respect to leakages which occur. Increased energy consumption for the plant as a whole is therefore to be expected in that case.
In addition, the otherwise known conveyor belts with elevations resembling suction cups (DE-A-30 01 531) are not used at this point, since elevations or suction pockets of this kind may be destroyed by steel plates which are to be transported by means of the conveyor belt.
Moreover, suction losses occur due to the fact that the known conveyor belt with a flat seal cannot readily adapt to dented or otherwise distorted sheet metal plates. Further pressure losses must therefore be expected in the region of a bulge or dent of this kind.
Irrespective of this, an apparatus, working with suction air, for the suspended transport of sheets became known from DE-A-43 42 753. This apparatus has transport bands of finite length which span the transport zone and are arranged transversely to the latter next to and parallel to one another. The transport bands can be driven via common drive and movement means, the movement drive of which is reversible for the purpose of a reciprocating movement of the transport bands and which, in the region in which the sheets are grasped, in each case have a stand-guided slidelike rigid part possessing a sucker means or are connected to such a part. An apparatus for the suspended transport even of nonmagnetizable articles is thereby to be provided.
The technical problem on which the invention is based is to develop an apparatus in the embodiment initially described, in such a way that, along with reduced energy consumption, optimum adaption to the workpieces to be transported is ensured.
To achieve this object, in a generic apparatus of the transport of workpieces, the invention proposes that the holding device have at least one magnetic device with a magnetic conveyor belt and at least one vacuum device separated from this and having a vacuum conveyor belt, the magnetic device and/or the vacuum device in each case being capable of being displaced with their respective conveyor belt relative to a common reference member and (alternately) of being brought into contact with the workpieces to be transported. Within the scope of the invention, the term “alternately” also, of course, includes the possibility of bringing both devices, that is to say the magnetic device and vacuum device, simultaneously into contact with the workpieces.
Furthermore, according to a preferred embodiment, there is provision for jointly connecting the magnetic device and the vacuum device to a profiled holding strip extending in the transport (plane) direction and acting as a reference member, the profiled holding strip having a basic carrier and a displacement carrier, and the magnetic device being flanged to the basic carrier and the vacuum device being flanged to the displacement carrier, or vice versa, said displacement carrier being movable, for this purpose, essentially vertically in relation to the transport (plane) direction. According to an alternative embodiment of the invention, there is provision for the vacuum device to be integrated into the magnetic device designed as a reference member and for said vacuum device to be movable, relative to the usually stationary magnetic device, in the direction of the workpieces. Of course, the normally stationary magnetic device may also be brought, as a whole, into contact with the workpieces, specifically as an as it were vertically adjustable holding device. It also goes without saying that the vacuum device integrated into the magnetic device may also be combined with the above-described device. In other words, within the scope of the invention, it is conceivable to have a holding device which possesses a magnetic device and vacuum device which are connected to a profiled holding strip and, in addition, a vacuum device which is integrated into the magnetic device. Furthermore, there is preferably provision for the magnetic device integrated into the vacuum device to be designed with a U-shaped cross section having a U-base and U-legs, at least two magnetic conveyor belts being led, on the foot side, past the two respective U-legs, while the vacuum device together with the vacuum conveyor belt is arranged in the longitudinal extent between the two magnetic conveyor belts.
By virtue of these measures of the invention, not only is the energy consumption markedly reduced, but, at the same time, optimum adaption to the workpieces to be transported also takes place. It should be emphasized, in this respect, that the apparatus described is suitable both for suspended and for carrying or supporting transport. At all events, it is always ensured that either the magnetic device or the vacuum device are used alternately (or else jointly).
The invention proceeds, in this case, from the current knowledge that, in general, approximately 90% of the transported workpieces are ferromagnetic, and therefore the magnetic device is used predominantly. It is consequently unnecessary to make additional provision for the workpieces to be sucked up. A simple, cost-effective toothed belt can therefore be used as a magnetic conveyor belt. There is no need for special sealing properties because, on the one hand, the magnetic device with the magnetic conveyor belt and, on the other hand, the vacuum device with the vacuum conveyor belt are designed se
Collard & Roe P.C.
Neuhäuser GmbH & Co.
Valenza Joseph E.
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