US 3748973 A
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United States Patent [1 1 Kuck  Inventor: Helmut Kuck, Intrup, Germany  Assignee: Windmoller & Holscher, Lengerich of Westphalia, Germany  Filed: July 29, 1971  Appl. No.: 167,154
 Foreign Application Priority Data Aug. 11, 1970 Germany P 20 39 942.2
 US. Cl. 93/93 DP  Int. Cl B3lb 1/98, B65b 27/08  Field of Search 93/93 DP, 93 M, 93 R, 93/8 R; 53/198, 188; 271/68  References Cited UNlTED STATES PATENTS 3,631,770 1/1972 Kratzert et al 93/93 DP 3,203,561 8/1965 Shields 271/68 X 3,346,128 10/1967 Hullhorst... 271/68 X 3,643,557 2/1972 Hayes 93/93 DP 3,416,286 12/1968 Ciccone 93/93 DP X 1 July 31, 1973 3,404,609 10/1968 Hartbauer et al. 93/93 M Primary Examiner-Andrew R. Juhasz Assistant Examiner-Horace M. Culver AttorneyFleit, Gipple & Jacobson  ABSTRACT In a bag-making machine where the bags are discharged by a cylinder and deposited on a substantially horizontal table disposed at the cylinder periphery, apparatus for collecting and withdrawing stacks of the deposited bags comprises gripping units effective to take successive stacks from the table and withdraw them from the cylinder and holding fingers for engaging the successive stacks, the holding fingers projecting upwardly through apertures in the table, being movable lengthwise of the table, being spring-influenced towards the cylinder, having their ends spaced from the cylinder periphery and being dimensioned so that they slide off each stack during initial withdrawal movement of the stack by one of the gripping units. Further but longer holding fingers are preferably adapted to slide off the stack during subsequent withdrawal movement of the stack.
5 Claims, 4 Drawing Figures PATENIEDJ'JL 3 1 I975 SHEEI 1 0F 4 INVENTOR Helmut KUCK ww w W his ATTORNEYS PATENIEDJUU 1 2925 3,748,973
' sum 2 or 4 INVENTOR Helmut KUCK y y fll @fimfawa his ATTORNEYS PATENIEL m 3 1 ms SHEU 3 [If 4 FIG.3
INVENTOR Helmut KUCK his ATTORNEYS PAIENTEL JUL 3 H SHEET Q I]? 4 INVENTOR Helmut KUCK his ATTORNEYS The invention relates to an apparatus for collecting and withdrawing stacks of bags delivered by a depositing cylinder of a bag-making machine. Such apparatus is, for example, described in our prior Application No. 12168/70 (German Application P 19 16 130.9) and may comprise a substantially horizontal depositing table to be disposed at the periphery of the cylinder and gripping units effective to take successive stacks from the table and withdraw them in a direction away from the cylinder.
Modern bag-making machines have such a high production capacity that there is an extremely small time interval between successive bags deposited on the table and it becomes extraordinarily difficult to move a gripping unit and a completed stack held thereby away from the cylinder and introduce an empty gripping unit before the first bag of the next stack has been delivered by the cylinder and deposited on the table. Special precautions must therefore be taken to prevent the deposited bags from dropping off the table or from becoming displaced in the stack while the gripping units are being changed.
The invention aims to provide an apparatus in which bags delivered by the depositing table while the gripping units are being changed are adequately supported until an empty gripping unit has arrived in an operative position.
According to the invention, apparatus for collecting and withdrawing stacks of bags delivered by a depositing cylinder of a bag-making machine comprises a substantially horizontal depositing table to be disposed at the periphery of the cylinder, gripping units effective to take successive stacks from the table and withdraw them from the cylinder, and holding fingers for engaging the successive stacks, wherein the holding fingers project upwardly through apertures in the table, are movable lengthwise of the table, are spring-influenced towards the cylinder, have their ends spaced from the cylinder periphery and are dimensionsed so that they slide off each stack during initial withdrawal movement of the stack by one of the gripping units.
The ends of the holding fingers are effective to press the deposited bags resiliently against the periphery of the cylinder and are released from a completed stack during initial movement thereof away from the cylinder, whereupon they immediately spring back towards the cylinder periphery. The holding fingers return to the cylinder periphery so rapidly that they will be ready to engage the very next bag arriving on the depositing cylinder and accurately position it, and successive bags, under light pressure directed towards the cylinder until a further gripping unit has been brought into position adjacent the cylinder. The spacing of the ends of the holding fingers from the cylinder periphery permits the arriving bags to enter between the holding fingers and the cylinder periphery.
To ensure that the holding fingers will spring back towards the cylinder as rapidly as possible, they should project above the depositing table by only a small extent. However, these short holding fingers can engage only a limited number of bags and accurately hold them in position while the gripping units are being changed. This is so particularly because, as the number of bags held by the fingers increases, ie as the stack is growing, the fingers slide along the stack and eventually engage only a very narrow marginal portion of the stack. On the other hand, if the fingers can properly hold only a limited number of bags, insufficient time will be available for a new gripping unit to be brought into position adjacent the cylinder, especially if each gripping unit has to travel long distances in order to take a completed stack away. Accordingly, in the preferred form of the invention provision is made for at least one further but longer holding finger. The longer finger re mains in engagement with the stack when the shorter fingers have already snapped back to the cylinder periphery. For example, if each gripping unit is moved away from the cylinder in two stages (a first stage substantially radially of the cylinder and a second stage substantially tangentially thereto), the holding fingers may be dimensioned so that the shorter fingers snap back to the cylinder periphery during the first stage of movement of the gripping unit while each longer holding finger remains in engagement with the stack until the gripping unit is executing its second stage of movement. The longer holding finger therefore engages and supports a new stack that is being formed on the depositing table at a position more remote from the lower edge of the stack than the positions where the shorter fingers engage the stack. Even if the production capacity of the bag-making machine is very high, disruptions are therefore avoided while the successive stacks are being formed and transported away.
The holding fingers are preferably in the form of leaf springs which are secured beneath the table to a support thereof and which have upwardly projecting ends that are bent.
Each gripping unit may comprise a first jaw which is closable on a second jaw to grip therebetween a stack that is to be withdrawn from the cylinder, the closing movement of the first jaw being directed obliquely upwardly in relation to the cylinder. This ensures that the stack is lifted off the depositing table as the jaws of the gripjing unit are closed, whereby the shorter holding fingers will snap back towards the cylinder periphery during closure of the gripping unit.
An example of the invention will now be described with reference to the accompanying diagrammatic drawings, wherein:
FIG. 1 is a side elevation of a collecting and withdrawing apparatus in which a gripping unit is in an operative position adjacent a depositing cylinder of a bagmaking machine;
FIG. 2 is a similar view of the apparatus after the gripping unit has executed a short radial movement to carry away a completed stack;
FIG. 3 is a side elevation of the same apparatus after the gripping unit has also been moved substantially tangentially to the depositing cylinder, and
FIG. 4 is a part-section taken on the line lV-lV in FIG. 1.
Bags B from a bag-making machine are delivered by a continuously rotating depositing cylinder 1, are stacked and then taken away by gripping units 2, a photo-electric counter (not shown) being provided for each gripping unit so that each unit is moved away when a stack of a predetermined number of bags has been formed.
The cylinder 1 is associated with a depositing table 4 which is mounted on a machine frame 3. The table comprises a plurality of bars 4' which engage in peripheral grooves of the cylinder. Secured to the table there are holding fingers 5, 6 in the form of leaf springs which project beyond the table surface when they are in the operative position shown in FIG. 3 where they can engage bags arriving on the cylinder 1. As evident from FIG. 4, the holding fingers project through spaces between the bars 4' of the depositing table and they lie lightly against the periphery of the cylinder. They are secured to a lower support 4" of the table so that they will be pivotable radially upwardly of the cylinder against their own resilience. The free ends of the holding fingers are bent away from the periphery of the cylinder and from the bags which they are to engage so that the leading edges of the bags arriving on the cylinder can readily slip between the holding fingers and the cylinder periphery before they are released by grippers 1' of the depositing cylinder. The holding fingers 5 are shorter than each holding finger 6 (only one holding finger 6 is illustrated). Accordingly, the holding fingers 5 project beyond the table surface to a smaller extent than each holding finger 6.
Each gripping unit 2 comprises a carriage 8 movable along guide rails 7 and gripper members which are transversely displaceable in the direction of the arrows b, b", the gripper members being in the form of a supporting plate or jaw 9 and gripping fingers or second jaws 10 mounted on a common support 11. The gripping units 2 have their carriages 8 fixed at regular intervals to intermittently rotatable endless conveyor chains 12. As shown in FIG. 1, the overall arrangement of the gripping units 2 relatively to the depositing cylinder 1 is such that the gripping units are moved by the chains 12 in the direction of the arrow a tangentially upwardly with respect to the depositing cylinder and at a lateral spacing therefrom and so that their grippers or jaws 9, 10 are reciprocated transversely in the direction of the arrows b, b" radially with respect to the depositing cylinder by any suitable control means (not shown).
Whilst the chains 12 are stationary, a gripping unit will be in an operative position as shown in FIG. 1 in which the jaws 9, 10 are open, the jaws l0 projecting between the bars 4 of the table 4 and between the holding fingers 5, 6 to engage in peripheral grooves of the cylinder 1 and being at substantially the same level as the table surface.
In the FIG. 1 operative position of the gripping unit, the bags B delivered in very rapid sequence by the cylinder l are deposited directly on the jaw 10 of the gripping unit between the holding fingers 5, 6 and the cylinder periphery. The bags are formed to a stack St which soon grows to reach the jaw 9 and push the holding fingers 5, 6 into recesses 13 of the jaw 9. As soon as the desired number of bags has been deposited on the jaws 10, the aforementioned photo-electric counter operates a switch which is effective to move the jaws 10 in the direction of the arrow b towards the jaw 9 in the sense of closing the jaws and subsequently to move the chains 12 so that the gripping unit is moved upwardly in the direction of the arrow a. The completed stack is therefore clamped by the jaws of the gripping unit and firstly moved radially out of the region of the cylinder 1 and then away tangentially with respect to the depositing cylinder. During the short radial movement of the stack, the shorter holding fingers 5 slide off the stack St in the direction of the arrow c in FIG. 2 and snap back against the periphery of the cylinder to catch the first bag that is delivered by the cylinder for the next stack to be formed. All subsequent bags are therefore deposited on the table 4 whilst being securely held by the fingers 5. After the gripping unit 2 has started to move tangentially upwardly, each longer holding finger 6 will also slide off the stack and spring back towards the cylinder as shown in FIG. 3 to engage the new stack St that is being formed. The holding finger 6 engages this new stack at a distance above the table surface sufficient to prevent the stack from buckling or bowing. It will now be evident that the holding fingers 5, 6 engage the new stack St on the table until, as shown in chaindotted lines in FIG. 3, an empty gripping unit 2' has,
been positioned adjacent the cylinder from below the table to assist in the supporting function of the holding fingers 5, 6.
In the illustrated embodiment, the jaws 10 of each gripping unit are carried by parallel crank arms 14 so that they move in the oblique upward direction of the arrow d shown in FIG. 3 when they close on the jaw 9, that is to say the jaws 10 are moved in an arcuate path. This causes a completed stack St to be lifted off the table 4 already while the jaws of the gripping unit are closing and therefore the shorter holding fingers 5 will slide off the completed stack at a very early stage and spring back towards the cylinder in time to catch the first bag for the next stack.
1. An apparatus having a delivery cylinder of a bag making machine for delivering individual bags made thereby and an apparatus for receiving and withdrawing a predetermined number of said bags as a stack, said apparatus comprising a substantially horizontal table positioned at the periphery of said cylinder and adapted to receive said bags, said table having a plurality of apertures therein, gripping means adapted to grip successive stacks from said table and withdraw said stacks from said cylinder, and a plurality of springbiased holding fingers having one end positioned below said table and the other end projecting upwardly through said apertures in said table and spaced from the periphery of said cylinder, said holding fingers being adapted to engage the successive stacks and being moveable in a direction away from said cylinder, said holding fingers being dimensioned such that they slide off of each of said stacks during the initial withdrawal of said stacks from said cylinder by said gripping means.
2. The apparatus of claim 1 in which at least one of said plurality of holding fingers has one end projecting upwardly through said apertures in said table to a point which is above the upper ends of the remaining of said holding fingers such that at least one of said holding fingers slides off of said stack after said remaining holding fingers.
3. The apparatus of claim 2 in which said holding fingers are leaf springs which have said one end attached at a point beneath said table and in which said other end of said holding fingers is bent such that said other end points in a direction away from said cylinder.
4. The apparatus of claim 1 in which said gripping means comprises first and second jaws adapted to grip a stack and in which said first jaw is moveable toward said second jaw in an oblique upward direction during the withdrawal of said stack.
5. The apparatus of claim 1 in which each of said gripping units is mounted on an intermittently moveable conveyor.