Work holders – With fluid means – Vacuum-type holding means
Reexamination Certificate
2000-06-21
2001-10-16
Banks, Derris H. (Department: 3723)
Work holders
With fluid means
Vacuum-type holding means
C269S020000
Reexamination Certificate
active
06302387
ABSTRACT:
DESCRIPTION
The present invention relates to a vacuum hold-down system comprising a supporting base and a modular suction device, mountable on a support surface of the supporting base, upon which a work piece to be clamped to can be placed, wherein the support surface of the supporting base is provided with shutoff valves through which air suction can be applied for holding down the modular suction device and/or the work piece, and wherein the modular suction device has, on its underside contacting the support surface, a seal surrounding at least one shutoff valve, thereby forming a closed space which can be evacuated through the shutoff valve.
For woodworking machines in particular, spreader bars are known upon which modular suction devices are mounted (DE 295 18 188 U1) and which serve to hold-down work pieces for working on them, for example wood slats and the like. After the modular suction devices are mounted on the spreader bars, the modular suction devices are securely suctioned to the spreader bars in fixed positions. This is accomplished by opening shutoff valves in a first vacuum circuit, through which a first closed space on the underside of each modular suction device is connected to the first vacuum circuit. After the work piece is placed on the modular suction device, vacuum is applied at a second vacuum circuit, such that the modular suction device sucks down the work piece. This is achieved by providing on a topside of the modular suction device a hold-down space which is connected to the underside of the modular suction device by a connecting line which passes through the modular suction device, and which leads from a second space provided there for holding down the modular suction device to the spreader bar. This connection line is connected to the second vacuum circuit. In order to hold down the work piece, the modular suction device is first positioned and the work piece is then held down. These hold-down systems have a significant advantage in that the modular suction devices can be centrally held down, and the work pieces can be centrally sucked down through the modular suction devices. Thus, a hose connection to each individual modular suction device, which often is problematic, is not required. The work piece can thus be detached without detaching the modular suction device.
However, the spreader bars have proven to be relatively expensive since they must be equipped with two vacuum circuits. In addition, the spreader bars must be provided with two shutoff valves at each location not covered by modular suction devices, so that the two vacuum circuits can be closed there. Furthermore, the modular suction devices can only be displaced on the spreader bars linearly, that is, along one direction, corresponding to a longitudinal extension of the spreader bar. The spreader bars must be displaced relative one another in a direction transverse thereto. If different work pieces are processed in succession, under certain conditions this can lead to considerable expense for adjustments. In addition, the modular suction devices generally cannot be rotated.
Also known are work-hold-down tables upon which modular suction devices can be optionally placed. These work-hold-down tables have the advantage that positions of the individual modular suction devices can be precisely adjusted to a shape of a work piece. Furthermore, repositioning of the modular suction devices is relatively simple.
A disadvantage of such work-hold-down tables, however, is that the individual modular suction devices must be connected to vacuum sources by hose connections. These hose connections are problematic when working on the work pieces because for one thing they lie on the work-hold-down table beside the modular suction devices and they become covered up by waste materials. Such hose lines can also be easily damaged.
It is therefore an object of this invention to eliminate the previously described disadvantages and/or to provide a vacuum hold-down system of relatively simple construction which offers flexibility of use.
This object is achieved by the invention, in that a space provided on an underside of a modular suction device is coupled to a pressure control valve which is, in turn, coupled to a topside of the modular suction device by opening into a hold-down space that is circumscribed by a second seal.
In the vacuum hold-down system of the invention, the space for holding down the modular suction device on a hold-down base, for example a spreader bar, a work-hold-down table, or the like, is connected by the pressure control valve to the hold-down space provided on the topside, by which the work piece is held down. The work piece is thus held down over the space which serves to hold down the modular suction device. This inventive solution has the significant advantage that only a single vacuum circuit is required to hold down both the modular suction device and the work piece. A structure of the supporting base is therefore considerably simpler than for systems having two vacuum circuits. Despite the use of only one vacuum circuit, the work piece and the modular suction device can be held down independently of one another. The work piece can thus be detached while the modular suction device remains held down. No hose connections are required. The modular suction device can be mounted on beams as well as on tables.
Since only a single vacuum circuit is required, only one shutoff valve is needed for a suction holes in the supporting base, so that the number of shutoff valves required is halfed compared to known embodiments. In addition, the modular suction device in the vacuum hold-down system of this invention need not be placed on the supporting base in a particular configuration. In the current state-of-the-art, a modular suction device must always be attached so that a first suction hole communicates with a space for sucking down the modular suction device and a second suction hole communicates with a connection line to the hold-down space. If the modular suction device were mounted in a rotated orientation—if this were even possible—malfunctions could result. Since the modular suction device can only be mounted in a specified position or orientation, options for use of known hold-down systems are therefore limited. In the hold-down system according to the invention, the modular suction device as well as the work piece are held down with a single suction hole in the supporting base. Thus, the modular suction device can also assume any desired position and configuration (rotational position) on the supporting base, provided that the space for holding down the modular suction device communicates with a suction hole in the supporting base.
In one embodiment according to the invention, the pressure control valve on the one hand opens when a given negative pressure is reached, and on the other hand couples the hold-down space on the topside of the modular suction device with the space on its underside. The single-circuit system, according to the invention, is driven by two different pressures. The one negative pressure serves to hold down the modular suction device and the second negative pressure, which is larger than the first negative pressure, serves to hold down the work piece (and thus, holds down the modular suction device as well), with the pressure control valve being controlled by the second negative pressure such that it opens and establishes the connection between the hold-down space provided at the topside and the space for holding down the modular suction device. In order to hold down the work piece, the system vacuum need only be increased. The pressure control valve according to the invention can be thusly vacuum-activated.
However, other embodiments are also conceivable in which the pressure control valve is formed from a push valve, so that upon mounting of the work piece on the modular suction device, the valve is opened by the work piece to evacuate the hold-down space, thus effecting hold-down of the work piece.
In order to detach the work piece, only the pressure i
Schmalz Kurt
Schmalz Wolfgang
Stockburger Ralf
Banks Derris H.
J. Schmalz GmbH.
Shanley Daniel
LandOfFree
Vacuum tightening system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vacuum tightening system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vacuum tightening system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2584309