LIFTING APPARATUS

Abstract: Lifting apparatus, especially for stacking or unstacking stations of panel handling lines, said lifting apparatus comprising a raiseable and lowerable lifting frame (1) and means for raising and lowering the lifting frame. The means for raising and lowering the lifting frame comprise at least one drive shaft (2, 3) and at least two lifting belts (4, 5, 6, 7), whose first end is attached to the drive shaft (2, 3) in a manner allowing the lifting belts to be wound up around the shaft, while their second end is attached to the lifting frame (1) or arranged to pass via a diverting pulley on the lifting frame and attached to the frame structure of the lifting apparatus.

Description: LIFTING APPARATUS The present invention relates to a lifting apparatus as defined in the preamble of claim 1. In panel handling systems, especially in conjunction with feed stations or stacking stations, a lifting apparatus with a raiseable and lowerable lifting frame is often used. The lifting frame can be provided with a conveyor system or e.g. a roller track, which serves as a carrier to move panels or panel stacks. In panel handling systems, lifting capacities of the order of e.g. 10000-20000 kg are needed. In a known solution, pre- sented in international patent specification WO 94/11285, the lifting apparatus applied in the feed station employs a hydraulic drive that raises and lowers a lifting frame using chain transmission. Such a solution requires fairly complex and strong structures. Moreover, the hydraulic system is susceptible to leaks that may cause damage to the panels being handled. Adjusting the hydraulic systems is difficult and usually requires the use of proportional or servo techniques, leading to complex systems involving difficulties e.g. in respect of maintenance. The object of the present invention is to achieve a new type of lifting apparatus that obviates the drawbacks of prior art. The invention is characterized by what is presented in the claims. The apparatus of the invention has numerous significant advantages. The invention makes it possible to use a structural solution that is simpler than earlier solutions. Slots formed at the ends of lifting shafts permit easy and reliable attachment of lifting belts. The use of lifting belts allows a very compact structure. The drive system permits very accurate vertical positioning of the lifting frame, which can also be easily adjusted. Master and slave drives allow precise adjustment of several drive shafts even in a situation where the lifting frame has an uneven load. In the following, the invention will be described in de- tail by the aid of an embodiment example by referring to the attached drawing, in which Fig. 1 presents a lifting apparatus according to the invention in side view, Fig. 2 presents a lifting apparatus according to the invention in end view, Fig. 3 presents a lifting apparatus according to the invention in top view, Fig. 4 presents a detail of Fig. 1 as sectioned along line IV-IV, Fig. 5 presents the end of a drive shaft in the lifting apparatus of the invention as sectioned along an axial plane, and Fig. 6 presents the end of the drive shaft as sec- tioned along line VI-VI in Fig. 5. Lifting apparatus, especially for stacking or unstacking stations on panel handling lines, said apparatus comprising a raiseable and lowerable lifting frame 1 and means for raising and lowering the lifting frame. The means for raising and lowering the lifting frame comprise at least one drive shaft 2, 3 and at least two lifting belts 4, 5, 6, 7, the first end of which is attached to the drive shaft 2, 3 while the second end is attached to the lifting frame 1 or arranged to pass via the lifting frame and attached to the frame structure of the lifting apparatus. The lifting apparatus comprises a frame which has a pillar 8 at each corner as well as longitudinal supporting beams 9 and transverse supporting beams 10. In the em- bodiment illustrated by the figures, the drive shafts 2, 3 are disposed in the upper part of the frame in a transverse position between the pillars 8. The drive shafts 2, 3 are supported by bearings placed at a distance from the end of the shaft 2, 3 so that the end of each shaft remains free. The drive shafts 2, 3 are driven by a drive unit 11, preferably via a transmission 12. The drive unit preferably consists of a conventional combination of a cage induction motor 11 and a pin transmission 12. The lifting belts 4, 5, 6, 7 are placed on the free ends of the drive shafts 2, 3, so that, when the shafts 2, 3 are rotated, the belts are wound around the shafts, thus raising the lifting frame 1. When the shafts are rotated in the opposite direction, the lifting belt 4, 5, 6, 7 is unwound from the shaft and the lifting frame 1 is lowered. The other end of the lifting belt is attached by means of fixing devices 13, 14, 15 to the lifting frame 1, or alternatively the lifting belt is arranged to pass via a diverting pulley or the like mounted on the lifting frame and attached by means of fixing devices to the frame of the lifting apparatus. ■ "Lifting belt' refers to a lifting strap with at least one loop formed in it. Usually the lifting belt has a loop at each end. The drive shaft 2, 3 is provided with a slot 16 or the like to permit a lifting belt 4 to be attached to the drive shaft (Fig. 5 and 6) . The slot 16 forms a cleft at the end of the drive shaft. In the axial direction of the shaft, the slot 16 extends through a distance at least corresponding to the width of the lifting belt 4. The loop at the end of the lifting belt 4 is placed on the shaft 2 so that part of the loop is in the slot 16. The edges of the slot are preferably rounded. The end of the drive shaft 2 is provided with a flange element 17 to prevent the lifting belt 4 from coming off the shaft 2 as it is wound up on the shaft. The flange element 17 has a diameter substantially larger than that of the shaft 2. The flange element comprises a counter element 18 designed to fit into the slot 16. The counter element 18 prevents the shaft end segments 2', 2 ' ' on opposite sides of the slot 16 from being pressed together. Preferably the shaft end is provided with a cen- tral mortise 19, in which case the counter element 18 of the flange 17 is a projection, sleeve or the like that fits into the mortise. Formed in the flange element 17 is a cut-out 20 that fits onto the shaft end so that the flange element can be firmly fixed to the end of the drive shaft 2 by means of fixing elements 21, such as screws. At the same time, the flange element 17 keeps the shaft end segments 2', 2 ' ' and therefore the slot 16 in a straight position. In the example illustrated by Fig. 1 - 4, the lifting apparatus has two drive shafts 2, 3, each with two lifting belts 4, 5, 6, 7 arranged to raise and lower the lifting frame 1. The lifting belts are arranged to raise the lifting frame 1 directly via fixing elements 13, 14, 15. Alternatively, a solution can be used in which the lifting belt 4, 5, 6, 7 passes around one or more diverting pulleys (not shown) . The drive shafts 2, 3 are driven by a drive unit 11 preferably provided with a frequency converter and a pulse sensor or equivalent. This allows a very accurate control of the drive shafts. When there are more than one drive unit, one of the drive units is a so-called master drive while the others are so-called slave drives. The slave drives closely follow the master drive e.g. on the basis of readings obtained from the pulse sensor, with the result that the lifting frame 1 e.g. remains accurately in a straight position. This also makes it possible to avoid deviations of the lifting frame from the horizontal plane due to uneven load. When the lifting capacity of the lifting apparatus of the invention is e.g. 10000 kg, it is possible to use a " lifting belt of polyester textile material having a width of 100 mm and a thickness of 3.2 mm and a rated load of 4000 kg. It is obvious to the skilled person that the invention is not restricted to the embodiments described above, but that it may be varied in the scope of the claims presented below. Thus, it is also possible to use an embodiment having only one drive shaft, to which the lift- ing belts are attached.

Claims: CLAIMS 1. Lifting apparatus, especially for stacking or un- stacking stations on panel handling lines, said lifting apparatus comprising a raiseable and lowerable lifting frame (1) and means for raising and lowering the lifting frame, characterized in that the means for raising and lowering the lifting frame comprise at least one drive shaft (2, 3) and at least two lifting belts (4, 5, 6, 7), whose first end is attached to the drive shaft (2, 3) in a manner allowing the lifting belts to be wound up around the shaft, while their second end is attached to the lifting frame (1) or arranged to pass via a diverting pulley on the lifting frame and attached to the frame structure of the lifting apparatus. 2. Lifting apparatus as defined in claim 1, characterized in that the drive shaft (2, 3) is provided with a slot (16) or the like to allow the lifting belt (4, 5, 6, 7) to be attached to the drive shaft (2, 3) . 3. Lifting apparatus as defined in claim 1 or 2, characterized in that the lifting belt (4, 5, 6, 7) comprises at least one loop by which the lifting belt is attached to the drive shaft (2, 3) . 4. Lifting apparatus as defined in any one of the preceding claims 1 - 3, characterized in that the slot (16) cleaves the end of the shaft. 5. Lifting apparatus as defined in any one of the preceding claims 1 - 4, characterized in that the slot (16) extends in the axial direction of the shaft through a distance at least corresponding to the width of the lifting belt (4, 5, 6, 7). 6. Lifting apparatus as defined in any one of the preceding claims 1 - 5, characterized in that the end of the drive shaft (2 r 3) is provided with a flange element (17) comprising a counter element (18) that can be fit- ted into the slot (16) . 7. Lifting apparatus as defined in any one of the preceding claims 1 - 6, characterized in that the end of the drive shaft (2, 3) is provided with a mortise (19) , preferably centrally, and the counter element (18) of the flange (17) consists of a projection, sleeve or the like that fits into the mortise. 8. Lifting apparatus as defined in any one of the pre- ceding claims 1 - 7, characterized in that the flange element (17) has a cut-out (2) formed for the end of the drive shaft (2, 3) . 9. Lifting apparatus as defined in any one of the pre- ceding claims 1 - 8, characterized in that the lifting apparatus has two drive shafts (2, 3) , each with two lifting belts (4, 5, 6, 7) arranged to raise and lower the lifting frame (1) . 10. Lifting apparatus as defined in any one of the preceding claims 1 - 9, each drive shaft (2, 3) is arranged to be driven by a drive unit (11) provided with a frequency converter and a pulse sensor or equivalent. 11. Lifting apparatus as defined in any one of the preceding claims 1 - 10, characterized in that if there are more than one drive (11), one of the drives is a so- called master drive while the others are so-called slave drives .

Inventors: LEHTIMAEKI TEUVO, LEHTIMAEKI, TEUVO
Applicants: LEHTIMAEKI TEUVO, SUNDS DEFIBRATOR PANELHANDLING, LEHTIMAEKI, TEUVO, SUNDS DEFIBRATOR PANELHANDLING OY
Application year: 1997
Main classification: B66F7
IPC codes: B65H1, B66F7