Material or article handling – Apparatus for moving intersupporting articles into – within,... – Stack forming apparatus
Reexamination Certificate
1999-09-02
2001-11-20
Krizek, Janice L. (Department: 3652)
Material or article handling
Apparatus for moving intersupporting articles into, within,...
Stack forming apparatus
C271S217000, C414S926000
Reexamination Certificate
active
06318954
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national stage of PCT/EP98/01342 filed Mar. 7, 1998 and based upon German national application 197 11 406.7 filed Mar. 19, 1997 under the International Convention.
TECHNICAL FIELD
The invention relates to a device for stacking sheets onto pallets, particularly paper or cardboard sheets fed in a scale-like (overlapping) manner.
BACKGROUND OF THE INVENTION
For the stacking of sheets downstream of a crosscutter it is known to use devices which have a raisable and lowerable storage platform, on which pallets for receiving the stacks have been laid. The sheets are conveyed to the stacking area and laid on the upper side of the stack by a vertically stationary feeder, arranged above the ground at a height which is greater than the maximal stack level. During stacking the storage platform is continuously lowered corresponding to the growth of the stack, so that the drop height of the sheets from the feeder to the upper side of the stack remains constant, insuring a trouble-free stacking with precisely aligned edges.
For a stack replacement the storage platform with the full pallet is lowered to the ground level. After the full pallet is removed and replaced with an empty pallet, the platform is raised to a level slightly below the feeding level. In order not to interrupt the feeding of sheets during a stack replacement, devices with an auxiliary stacking platform are known, which support the forming stack while the finished stack is removed. The empty pallets are then moved to a level directly below the auxiliary stacking platform and take over the partial stack formed on the auxiliary stacking platform.
STATE OF THE ART
From DE 38 23 806 C2 a stacking device is known, wherein the control of the lowering motion of the storage platform is performed by means of an optical sensor, which is arranged on the incoming side of the stacking area and detects the stack height.
The document EP-A-0 211 996 discloses a generic stacking device wherein laterally next to the storage platform three optical sensors are arranged vertically one above the other, which are all active during operation. The individual sensors are arranged at distances of 10-20 mm, 20-40 mm and 40 to 60 mm underneath the upper end of the feeding conveyor and serve for controlling the lowering speed of the storage platform.
From the EP-A-0 149 737 a stacking device is known, wherein at the beginning of the stacking area laterally five initiators are arranged vertically one above the other at a height at which the storage platform is supposed to be when a stack replacement is to take place. Each of the initiators can be separately activated and can trigger a braking device for stopping the supplied flow of sheets, in case the storage platform has reached this position due to the curvature of the sheets, although the preset number of sheets to be deposited has not been reached.
In practice it has been proven that the drop height of the sheets, which has to be kept substantially constant, has to be set differently, depending on the type of paper or cardboard. Therefore in case of a paper-type change, the optical sensor registering the desired stack level has to be reset in another vertical position in a complicated manner.
OBJECT OF THE INVENTION
It is the object of the invention to improve a generic stacking device, so that the drop height of the sheets can be set at various values without effort, in a simple manner.
SUMMARY OF THE INVENTION
According to the invention, at least three optical sensors for the upper stack side are arranged vertically one above the other and are separately actuatable. Each time two selected sensors establish the maximal drop height deviation and in this way make possible a control of the storage platform in such a manner that an upper maximal value cannot be exceeded and so that it can not fall below a lower minimal value.
In accordance with the invention, a device for stacking sheets onto pallets, particularly paper or cardboard sheets fed in an overlapping manner comprises a vertically stationary feeding conveyor for the sheets arranged above the floor at a height exceeding the maximum stacking level, a raisable and lowerable storage platform on which the stacks are formed, and at least three optical sensors arranged vertically one above the other at a slight distance below the feeding level. The optical sensors can be separately activated and are arranged on the incoming side upstream of the stacking area, whereby the vertical distance between two sensors amounts to a maximum 20 mm. More particularly, the vertical distance between two sensors can range between 5 mm and 10 mm. The sensors can be reflecting optical sensors.
REFERENCES:
patent: 4027580 (1977-06-01), Sundin
patent: 0 149 737 A1 (1985-07-01), None
patent: 0 211 996 A1 (1997-03-01), None
Claassen Ernst
Voss Peter
Dubno Herbert
Jagenberg Papiertechnik GmbH
Krizek Janice L.
LandOfFree
Device for stacking sheets, in particular sheet-fed paper or... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for stacking sheets, in particular sheet-fed paper or..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for stacking sheets, in particular sheet-fed paper or... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2617061