US 3901502 A
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United States Patent [1 1 Vits [ Aug. 26, 1975 TILTING SUCTION DEVICE FOR LlFTlNG OBJECTS WITH FLAT TOP SURFACES  Inventor: Hilmar Vits, Huschelrath 16,
Leichlingen, Germany  Filed: Dec. 21, 1973  Appl. No.: 427,120
 Foreign Application Priority Data Dec. 28, 1972 Germany 2263732  US. Cl 271/103; 271/106  Int. Cl. B6511 3/08  Field of Search 271/103, 106, 90-92,
 References Cited UNITED STATES PATENTS 1.264.211 4/1918 Saucr 271/106 1,794,843 3/1931 Freeman 271/106 3,039,767 6/1962 Staines 271/106 X 3,l55 386 11/1964 Burlcigh 271/103 Primary ExaminerEvon C. Blunk Assistant ExaminerRobert Saifer Attorney, Agent, or Firm-Holman & Stern 5 7 ABSTRACT A tilting suction device for lifting objects having a flat surface in which the bellows is peripherally pleated over its entire length; one diametrical half having an axial rigidity differing from that of the other diametrical half so that when evacuated, it will assume an angularly inclined condition to reorient the object being lifted and/or the pleated bellows is permanently inclined and is introduced to an object being lifted in an inclined condition and when evacuated assumes an inclined condition to reorient the object being lifted.
4 Claims, 4 Drawing Figures TILTING SUCTION DEVICE FOR LIFTING OBJECTS WITH FLAT TOP SURFACES FIELD OF THE INVENTION The invention relates to a tilting suction device for lifting objects with flat top surfaces, in particular sheets of paper, said device having a liftable, inclinable suction cup connected to a nipple of a vacuum suction pipe.
BACKGROUND OF THE INVENTION In a known tilting suction device of this type, the suction cup is a rigid element which, after aspirating a sheet by the vacuum action, can be swivelled about a pivot, against a spring, into an inclined position, from which, after removal of the sheet, it is pressed back into its original position parallel to the top surface of a stack of the sheets by the action of the spring.
Another known tilting suction device comprises an elastic suction cup, the axis of which is inclined at an angle to the object to be lifted, so that the edge of the suction cup positioned in a plane approximately perpendicular to the suction cup axis during the lowering process, on one side comes into contact with the object to be lifted. During further lowering, owing to an elastic deformation of the suction cup, the remainder of its edge also comes into contact with the object to be lifted.
SUMMARY OF THE INVENTION The object of the invention is to provide a tilting suction device which operates without mechanical moving parts.
In accordance with the invention, a tilting suction device for lifting objects with flat top surfaces comprising a liftable inclinable suction cup connected with a nipple of a suction pipe, the suction cup being placed at one end of a bellows, of which the other end is attached to the nipple of the suction pipe, and two diametrically opposite halves of the said bellows having adifferent axial spring rigidity respectively.
In a further alternative arrangement in accordance with the invention a tilting device for lifting objects having flat top surfaces comprises a liftable, inclinable suction cup connected with a nipple of a suction pipe, the suction cup being connected to one end of a bellows connected at its other end to the nipple of the suction pipe, the said bellows having approximately the same axial rigidity over its complete periphery, and the suction cup being inclined.
Preferably, to give the bellows a differing axial rigidity, the elastic material of the bellows is thicker on the one half than on the other.
Conveniently, so as to maintain the depression in the suction pipe leading to the bellows, when the bellows is expanded, without recourse to costly means, the bellows is connected with a vacuum source through a throttle which is provided on the end of the bellows opposite the suction cup.
BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings, in which:
FIG. 1 shows a first alternative form of tilting suction device, in axial section, with the bellows expanded,
FIG. 2 shows the tilting suction device according to FIG. 1 in elevation, with the bellows contracted,
FIG. 3 shows a second alternative embodiment of tilting suction device in axial section, with the bellows contracted, and with a lifted object, and
FIG. 4 shows the tilting suction device according to FIG. 3, in elevation, after deposition on the article to be lifted.
DESCRIPTION OF THE PREFERRED EMBODIMENTS To a nipple 1 of a suction pipe 2, which is connected to a vacuum source and serves as a support, one end 3 of a bellows 4 is firmly attached. A throttle 5 is located in the nipple 1. The opposite end of the bellows 4, is shaped as a suction cup 6. The opening 7 of the bellows 4 has a substantially larger cross-section than the opening 8 afforded by the throttle 5. The left hand half of the bellows 4 shown in the drawing, has a thicker wall than the right hand half. Since the material of the be]- lows 4 is elastic, that is for example, it is made of rubber or plastic, a different spring rigidity in the axial direction is obtained for the two halves of the bellows 4.
As long as the free opening 7 of the bellows 4 is not sealed tightly by a sheet of paper in close contact with the edge of the suction cup 6, the bellows 4 is expanded, as illustrated in FIG. 1. Air is still aspirated into the suction pipe 2 through the opening 8 of the throttle 5, but not sufficient to cause the vacuum in the suction pipe 2 to collapse. If a sheet of paper 9 is pressed against the edge of the suction cup 6 by lowering of the bellows 4 onto A stack 10 of such sheet and if the bellows 4 is sealed as a result, a vacuum will build up inside the bellows 4, this vacuum effecting an asymmetrical contraction of the bellows 4 in the axial direction, due to the different rigidity of the two bellows halves, as illustrated in FIG. 2. This differing contraction causes the edge of the paper sheet 9 picked up by the device, to become inclined, so that between the sheets of the stack 10 and the lifted sheet of paper 9, a wedge-shaped gap is produced, into which, for the purpose of lifting the sheet 9 away from the stack 10, air may be blown in the direction of arrow 11. The sheet of paper 9 can then be removed laterally from the stack 10 on an air cushion.
The alternative embodiment shown in FIGS. 3 and 4 differs from that illustrated in FIGS. 1 and 2, in respect of the bellows 14 and the suction cup 16. In this embodiment, the axial rigidity is constant over the entire periphery of the bellows 14. This is achieved by using identical material and identical wall thickness over the entire periphery. Because of this design, the suction cup 16, during lowering of the tilting suction device, meets the uppermost sheet 9 on the stack 10 with one side. With continued lowering, the entire edge of the suction cup 16 comes into contact with the uppermost sheet, the bellows 14 being more strongly compressed on one side than on the other. As soon as the sheet 9 has sealed the suction cup 16, a vacuum is produced in the interior of bellows 14, so that when the tilting suction device lifts, the sheet 9 is lifted with it. At the same time, due to the fact that there is uniform axial rigidity over the entire periphery of the bellows, tilting takes place into the position illustrated in FIG. 3.
The first alternative solution is more advantageous in many respects compared with the second. Firstly, the space between the top surface of the object to be lifted and the suction cup, with the bellows expanded, can be kept very small, which allows a small stroke and the resulting possibility of rapid movement. Furthermore, in the first alternative solution, during the deposition of the device, no transverse thrust relative to the direction of deposition is produced, as the suction cup is simultaneously deposited with its entire edge. However, in the second alternative solution, there is essentially a transverse thrust relative to the direction of deposition, which effects displacement of the sheet of paper to be lifted, and leads to increased abrasion of the edge of the suction cup. In addition, a greater stroke is necessary for the suction cup to be sealed by complete contact with the surface of the object to be lifted.
What we claim is:
1. A tilting device for lifting objects having flat top surfaces, comprising a liftable, inclinable suction cup connected with a nipple of a suction pipe, the suction cup being disposed at one end of a bellows having folds over its complete periphery, the other end of the bellows being attached to the nipple of the suction pipe, and the wall of the bellows comprising elastic material and the spring rigidity of the elastic material in opposed halves of the wall being different.
2. A tilting device for lifting objects with flat top surfaces, in particular for sheets of paper, comprising a liftable, inclinable suction cup connected with a nipple of a suction pipe, the suction cup being connected to one end of a bellows having a straight central axis connected at its other end to the nipple of the suction pipe, over its complete periphery the said bellows having both folds and approximately the same axial rigidity, and the suction cup being inclined to the straight central axis of the bellows.
3. A tilting device for lifting objects having flat top surfaces, comprising a liftable, inclinable suction cup connected with a nipple of a suction pipe, the suction cup being disposed at one end of a bellows having folds over its complete periphery, the other end of the bellows being attached to the nipple of the suction pipe, and two diametrically opposite halves of said bellows respectively having a different axial spring rigidity the wall of the bellows being of an elastic. material and thicker on one half than on the other.
4. A tilting device in accordance with claim 3, wherein the bellows is connected to a vacuum source through a throttle provided at the end of bellows opposite to the suction cup.