Vertical Panel Saw Having a Panel-Lowering Device

A vertical panel saw includes a frame, a saw unit movably arranged on the frame, and a plurality of panel-lowering devices. The panel-lowering devices each include a height-adjustment device having an adjustment drive and a panel-holding unit for holding a panel, which panel-holding unit is height-adjustably arranged on the height-adjustment device. The height-adjustment device includes a height-adjustable adjustment carriage and the panel-holding unit includes a lifting carriage. The panel-holding unit is kinematically connected to the adjustment drive via a freewheel, the freewheel interrupting the kinematic connection between panel-holding unit and adjustment drive when a panel held by the panel-holding unit is placed on a support.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a vertical panel saw having a panel-lowering device as described herein.

Description of Related Art

Vertical panel saws are known from the prior art which comprise a usually approximately vertically upright frame and a saw unit arranged so as to be movable on the frame by means of a saw beam. Panels that are to be sawn, especially made from wood and/or plastics, are placed onto the frame and supported at the bottom by support elements which are often in the form of support rollers. Some vertical panel saws have one or more panel-lowering devices for lifting panels to be sawn or panel parts that have already been sawn and lowering them onto the support elements. Such panel-lowering devices comprise, for example, clamping elements which are lowered onto a panel from above and then clamp the panel in the region of its upper edge. The height of the clamping elements is adjusted with the aid of a height-adjustment device and an adjustment drive.

In order that the panel clamped with the clamping elements can be lowered onto the support elements or the clamping elements can be lowered onto the panel to be grasped without giving rise to damage due to the action of excessively large forces, it is necessary to monitor the lowering operation at various locations using a plurality of sensors, especially if there is an option to add further support elements at other frame heights. Moreover, the height adjustment needs to be very precisely controlled.

In view of the disadvantages of the vertical panel saws known hitherto, the problem underlying the invention is to provide a vertical panel saw having an improved panel-lowering device which minimises the risk of damage associated with the handling of panels and/or reduces the monitoring means necessary for minimising the risks of panel handling.

That problem is solved by the vertical panel saw according to the invention as described herein.

SUMMARY OF THE INVENTION

The core of the invention lies in the following: a vertical panel saw comprises a frame, a saw unit movably arranged on the frame, and a panel-lowering device. The panel-lowering device comprises a height-adjustment device having an adjustment drive and a panel-holding unit for holding a panel, which panel-holding unit is height-adjustably arranged on the height-adjustment device. The height-adjustment device comprises a height-adjustable adjustment carriage and the panel-holding unit comprises a lifting carriage. The panel-holding unit is kinematically connected to the adjustment drive via a freewheel, the freewheel interrupting the kinematic connection between panel-holding unit and adjustment drive when a panel held by the panel-holding unit is placed on a support.

When a panel held by the panel-holding unit is placed on a support, the freewheel prevents excessively large opposing forces from acting on the panel-holding unit and on the height-adjustment device with the adjustment drive, because the forces generated by the adjustment drive are coupled out. That is to say, even if the adjustment drive continues to run, it does not exert on the panel-holding unit any force which presses the panel further against the support, that is to say which counteracts the support force. This prevents damage from being caused as a result of cumulative forces. Exact control of the height adjustment to ensure that the panel held by the panel-holding unit is placed onto the support virtually without force-which also requires suitable monitoring means—is in principle not necessary for this purpose.

The freewheel can in principle also lead to a kinematic decoupling of panel-holding unit and adjustment drive, i.e. to an interruption of the kinematic connection between panel-holding unit and adjustment drive, if, in order grasp a panel, the panel-holding unit is lowered onto the panel from above and the lowering operation is not stopped in good time. Since, however, the panel-holding unit is usually not placed onto the panel without gaps, this is a relatively rare occurrence.

In a preferred embodiment, the lifting carriage is separably supported on the adjustment carriage.

By the separable supporting of the lifting carriage of the panel-holding unit on the adjustment carriage of the height-adjustment device a freewheel can be realised in a simple manner. When the lifting carriage is supported, raising of the adjustment carriage also raises the lifting carriage, with the result that the remaining parts of the panel-holding unit connected thereto are also raised. If, however, during a lowering operation with the lifting carriage supported on the adjustment carriage, the panel-holding unit encounters resistance, for example when a panel held by the panel-holding unit is placed on a support or if the panel-holding unit is lowered onto the panel from above and is stopped too late, the lifting carriage can become separated from the adjustment carriage due to the upwardly acting force. This thus results in freewheeling of the adjustment drive, and the kinematic connection between panel-holding unit and adjustment drive is interrupted.

The height-adjustment device advantageously comprises an adjustment spindle which is rotatable by means of the adjustment drive, and the adjustment carriage is arranged on the adjustment spindle and is adjustable in height by rotation of the adjustment spindle. Such an adjustment spindle is a simple means for effecting a lowering or raising movement of the adjustment carriage with an adjusting force generated by the adjustment drive.

Preferably, the height-adjustment device comprises at least one linear guide on which the panel-holding unit is linearly guided. As a result, the panel-holding unit is held so as to be stably adjustable; it is adjustable, for example slidable, relative to the linear guide only in one direction and its opposite direction.

Advantageously, the panel-holding unit has a separation sensor which detects the separation of the lifting carriage from the adjustment carriage. Such a separation sensor makes it possible to react to the separation of the lifting carriage from the adjustment carriage and, for example, to stop the adjustment drive or even to move the adjustment drive (briefly) in the opposite direction until the adjustment carriage is in contact with the lifting carriage again and, via the lifting carriage, the panel-holding unit is supported by the adjustment carriage again.

The panel-holding unit is advantageously a clamping unit having a fixed clamping jaw and a movable clamping jaw, between which a panel can be clamped, the movable clamping jaw being movable, preferably linearly guided, towards the fixed clamping jaw by means of a clamping jaw drive, preferably a pneumatic clamping jaw drive. The gripping and secure holding of a panel with the panel-holding unit can thus be realised in a simple manner.

In an advantageous embodiment, at least one supply line of the panel-holding unit is guided via two deflection rollers from a static region of the vertical panel saw to the panel-holding unit, one of the two deflection rollers being arranged to be movable in such a way that the higher the position of the panel-holding unit, the greater the spacing between the two deflection rollers. Preferably, the movably arranged deflection roller is pretensioned in a direction away from the other deflection roller. The guiding of a supply line of the panel-holding unit via the two deflection rollers which are arranged to be movable relative to one another provides an arrangement of the at least one supply line that is as defined and space-saving as possible in all adjustment positions of the panel-holding unit. The at least one supply line never simply hangs down in a loose and undefined way.

Advantageously, the panel-lowering device comprises pulling means, preferably a tension spring or at least one magnet, which pull the lifting carriage towards the adjustment carriage. Such pulling means serve to pull the lifting carriage towards the adjustment carriage, if this is possible, that is to say if this is not prevented by the panel-holding unit, with or without a panel, being supported on a support. In this way the kinematic connection between panel-holding unit and adjustment drive is ensured as quickly and as well as possible.

Preferably, the vertical panel saw comprises two or more panel-lowering devices which are preferably adjustable synchronously. A panel can be held more stably with two or more panel-lowering devices than with only one panel-lowering device. Moreover, it is thus possible to lift heavier weights.

Advantageously, the vertical panel saw comprises a control device for controlling the panel-lowering device or the two or more panel-lowering devices, as the case may be. Such a control device especially makes it possible also to effect targeted control of a plurality of panel-lowering devices, especially by an operator but possibly also automatically by a control program.

DESCRIPTION OF THE INVENTION

The following observations apply in respect of the description which follows: where, for the purpose of clarity of the drawings, reference signs are included in a Figure but are not mentioned in the directly associated part of the description, reference should be made to the explanation of those reference signs in the preceding or subsequent parts of the description. Conversely, to avoid overcomplication of the drawings, reference signs that are less relevant for immediate understanding are not included in all Figures. In that case, reference should be made to the other Figures. References to positions and directions, such as above, below, upwards, downwards, relate to the typical arrangement of the vertical panel saw shown in the Figures.

FIG.1shows an exemplary embodiment of a vertical panel saw according to the invention on which a panel9to be sawn is arranged and held. The vertical panel saw has a frame2which comprises a plurality of vertical bars21, a lower crossbar22, an upper crossbar23and a support grid24arranged thereon for supporting the rear side of panels to be sawn, as well as a number of feet26. Distributed over the length of the lower crossbar22and projecting therefrom are a multitude of support elements in the form of support rollers25which serve as vertical support for panels to be sawn. InFIG.1, the panel9is supported on eight such support rollers25.

The vertical panel saw further comprises three mutually spaced, identically constructed panel-lowering devices1,1′ and1″, with which panels to be sawn can be securely held, lifted and lowered. The panel-lowering devices1,1′,1″ each have a height-adjustably arranged panel-holding unit11,11′,11″ which are able to grip from above over the upper edge of a panel to be sawn. InFIG.1, the panel-holding unit11of the panel-lowering device1is located in its upper end position, while the panel-holding unit11′ of the panel-lowering device1′ and the panel-holding unit11″ of the panel-lowering device1″ have grasped the panel9at its upper end and are holding it securely. The panel-holding units11′ and11″ have been lowered a short distance downwards away from their respective upper end positions.

For sawing the panels, in known manner the vertical panel saw has a saw unit3which is arranged on a saw beam31so as to be adjustable in height, that is to say substantially vertically adjustable, and which is pivotable between a vertical cutting position, in which a vertical cut can be performed, and a horizontal cutting position, in which a horizontal cut can be performed. The saw beam31is guided on the frame2so as to be movable in a longitudinal direction of the lower and upper crossbars22,23, so that by longitudinal or horizontal displacement of the saw beam31with the saw unit3arranged thereon it is possible to perform a horizontal cut. A vertical cut can be performed by adjustment of the height of the saw unit3along the saw beam31.

The vertical panel saw shown inFIG.1further comprises, likewise in known manner, an extraction device5for extracting sawdust and a switch cabinet6.

Finally, the vertical panel saw comprises a control device4for controlling especially the saw unit3, the panel-lowering devices1,1′,1″ and the extraction device5. The control device4is arranged on a control beam41which is adjustably guided on the frame2in a longitudinal direction of the upper crossbar23, that is to say, like the saw beam31, it is longitudinally and horizontally displaceable.

FIG.2shows the same vertical panel saw asFIG.1but here, instead of the panel9, a panel90is arranged thereon. The panel90is much longer and narrower than the panel9and is held by the panel-holding units11,11′,11″ of all three panel-lowering devices1,1′,1″. In the position shown, it has been lifted off the support rollers25.

FIGS.3-5show—representative of the identically constructed panel-lowering devices1,1′,1″—the panel-lowering device1in a perspective view seen obliquely from the front (FIG.3), in a perspective view seen obliquely from the front without the front casing (FIG.4) and in a front view (FIG.5).FIG.7shows an enlarged view of detail A ofFIG.5.

The panel-lowering device1comprises a height-adjustment device10and a panel-holding unit11for holding a panel, which panel-holding unit is height-adjustably arranged on the height-adjustment device10, that is to say is substantially vertically adjustable.

The height-adjustment device10comprises a height-adjustable adjustment carriage101, which is arranged on an adjustment spindle104rotatably mounted in a lower spindle bearing1041and an upper spindle bearing1042and the height of which is adjustable by rotation of the adjustment spindle104. For that purpose, the adjustment carriage101has an internal thread complementary to the external thread of the adjustment spindle104and thus forms a kind of spindle nut which is arranged so as to be fixed against rotation and is therefore adjusted in height on rotation of the adjustment spindle104. Rotation of the adjustment carriage101is prevented by the adjustment carriage being rigidly connected to a runner1011which is able to slide up and down in a substantially vertical direction on a substantially vertically arranged linear guide102.

The rotation of the adjustment spindle104is effected with an adjustment drive105in the form of a servomotor which—as can best be seen inFIGS.10and12—drives a toothed belt1052via a drive pulley1051, which toothed belt in turn drives an output pulley1053which turns the adjustment spindle104. In the other Figures, the drive pulley1051, the toothed belt1052and the output pulley1053are either hidden by housing parts or are not visible on account of the view chosen.

The panel-holding unit11comprises a lifting carriage111which in a normal situation according toFIGS.3-5and7is separably supported on the adjustment carriage101. The lifting carriage111and the adjustment carriage101are connected to one another via a tension spring14which pulls the lifting carriage111towards the adjustment carriage101. The lifting carriage111is provided on the left and on the right with a runner1111and1112, respectively, the runner1111being able to slide up and down in a substantially vertical direction on the linear guide102, and the runner1112being able to slide up and down in a substantially vertical direction on a substantially vertically arranged linear guide103parallel to the linear guide102. The panel-holding unit11is thus linearly guided by the two linear guides102,103.

The lifting carriage111carries a clamping unit having a fixed clamping jaw112and a movable clamping jaw113, between which a panel can be clamped. Below the fixed clamping jaw112there is arranged a panel edge sensor122for detecting the edge of a panel. The movable clamping jaw113is movable towards the fixed clamping jaw112by means of a clamping jaw drive described hereinbelow. Above the clamping jaws112,113and the clamping jaw drive, the clamping unit has a cover116having an LED display1161. By means of the LED display1161, the operating state of the panel-lowering device1can be displayed, for example “descending”, “ascending”, “movable clamping jaw113being adjusted”, “lifting carriage111supported on adjustment carriage101”, “lifting carriage111separated from adjustment carriage101”, etc.

Below the lifting carriage111there is a tensioning cylinder housing117in which there is arranged inter alia a pneumatic cylinder118for adjusting the movable clamping jaw113, which pneumatic cylinder can be seen inFIGS.9and11. The pneumatic cylinder118can be supplied with compressed air and controlled via a pneumatic hose119, an unlockable non-return valve120and a throttle valve121, see especiallyFIG.7.

As can best be seen inFIGS.3and5, the panel-lowering device1has a rear housing wall106and two front housing wall portions107and108. InFIGS.4and6, the panel-lowering device1is shown without the two front housing wall portions107,108, which allows a view of the adjustment spindle104and a central support stop109for the panel-holding unit11, which central support stop is mounted on the rear housing wall106. The central support stop109is optionally removable and in that case a lower stop1090for the panel-holding unit11is provided.

In contrast toFIGS.3-5and7,FIG.6shows the panel-lowering device1with the lifting carriage111separated from the adjustment carriage101.FIG.8shows an enlarged view of detail B ofFIG.6.

Starting from the situation shown inFIGS.3-5and7, the situation shown inFIGS.6and8is reached in particular if, during a lowering operation with the lifting carriage111supported on the adjustment carriage101, the panel-lowering device1encounters resistance, for example when a panel held by the panel-holding unit11is placed on a support, for example on the support rollers25, or if the panel-holding unit11is lowered onto the panel from above and is stopped too late. As a result of the upwardly acting force, the lifting carriage111has become separated from the adjustment carriage101, because the adjustment carriage101has been moved further downwards, while the lifting carriage111has remained stationary. The kinematic connection between panel-holding unit11and adjustment drive105is thus interrupted, because the movement of the adjustment carriage101is no longer being transmitted to the lifting carriage111. This corresponds to freewheeling of the adjustment drive105in relation to the panel-holding unit11.

As soon as, after an upward movement of the adjustment carriage101, the latter comes into contact with the lifting carriage111again, a kinematic connection between the adjustment drive105and the lifting carriage111is re-established, that is to say an upward movement generated by the adjustment drive105is transmitted directly to the lifting carriage111via the adjustment carriage101.

Once a panel carried by the panel-holding unit11, for example the panel9, has been placed onto the support rollers25, in order to obtain an optimum force distribution it can be advisable briefly to raise the adjustment carriage101again directly after the placement of the panel in order that the lifting carriage111is supported on the adjustment carriage101again.

In the situation shown inFIGS.6and8, the tension spring14, which is attached by one end to the underside of the lifting carriage111and by the other end to the side of the adjustment carriage101, has been stretched and tensioned and is pulling the lifting carriage111more strongly towards the adjustment carriage101. However, as long as the panel9held by the panel-holding unit11is supported on the support rollers25and thus an irresistible counterforce to the spring force and the weight force of the panel-holding unit11is in effect, the lifting carriage111does not move. The purpose of the tension spring14is especially to move the lifting carriage111towards the adjustment carriage101if no irresistible counterforce is present, but the weight force of the panel-holding unit11may not be sufficient to overcome counterforces (such as, for example, frictional forces or the supply lines pulling the panel-holding unit11upwards). This is usually only the case if the panel-holding unit11is not holding a panel.

Instead of being generated by the tension spring14, the attractive force between adjustment carriage101and lifting carriage111can alternatively also be generated by a magnet or a plurality of magnets.

FIGS.9,10,12and13show the panel-lowering device1, partly in diagrammatic form, from the side in various sectional views and in a perspective view seen obliquely from the rear.FIG.11shows an enlarged view of detail C ofFIG.9andFIG.14shows an enlarged view of detail D ofFIG.13.

FIG.12shows how a panel9is clamped between the fixed clamping jaw112and the movable clamping jaw113and thus held by the panel-holding unit11, while being simultaneously supported on the support rollers25.

It can be seen fromFIGS.9and11that the movable clamping jaw113is mounted on a tensioning carriage123which is connected to a tensioning cylinder piston1180of the pneumatic cylinder118by means of a tensioning cable124guided over a cable pulley125. A restoring spring126ensures that the tensioning carriage123with the movable clamping jaw113is pretensioned in a direction away from the fixed clamping jaw112. As can be seen especially inFIG.7, the pneumatic cylinder118can be supplied with compressed air and controlled via a pneumatic hose119, an unlockable non-return valve120and a throttle valve121. In this way the clamping unit with the fixed clamping jaw112and the movable clamping jaw113is adjustable by means of a pneumatic clamping jaw drive, which is in turn controllable by the control device4.

The pneumatic hose119is a supply line which is guided from a static region of the vertical panel saw to the panel-holding unit11. To prevent the hose from hanging down in a loose and undefined way in the wide variety of adjustment positions of the panel-holding unit1, in a static upper region of the panel-lowering device1the pneumatic hose119is guided into the interior of a chain13, see especiallyFIGS.5and7, which is guided around two deflection rollers131,132to the pneumatic cylinder118in the interior of the tensioning cylinder housing117, see especiallyFIGS.9-14, in which the chain13is shown partly in diagrammatic form simply as a line. While the upper deflection roller131is mounted in fixed position close to the upper end of the panel-lowering device1, the lower deflection roller132is arranged so as to be movable and suspended. The pivot shaft1320of the lower deflection roller132is mounted in an angled 25 part133. The angled part133is connected to one end of a tension spring139, the other end of which is connected to a fastening element138mounted on the rear housing wall106. The tension spring139pulls the angled part133downwards and thus pretensions the movably arranged lower deflection roller132in a direction away from the upper deflection roller131. This has the result that the higher the position of the panel-holding unit11, the greater the spacing between the two deflection rollers131,132, the chain13being under tension to some extent at all times, that is to say it does not simply hang down in a loose and undefined way. Such an arrangement with the chain13guided around two deflection rollers131,132is also relatively space-saving.

InFIG.14it can seen that in the lifting carriage111of the panel-holding unit11there is arranged a (preferably inductive) separation sensor114which detects the separation of the lifting carriage111from the adjustment carriage101. This makes it possible to react to the separation of the lifting carriage111from the adjustment carriage101and, for example, to stop the adjustment drive105or even to move the adjustment drive briefly in the opposite direction until the adjustment carriage101is in contact with the lifting carriage111again and, via the lifting carriage111, the panel-holding unit11is supported by the adjustment carriage101again.

Furthermore, in a static upper region of the panel-lowering device1there is arranged a (preferably inductive) reference sensor115with which the position of the panel-holding unit11can be determined.