| 1. | A method of transferring printhouse products, particularly folded newspapers (2) , from a moved flow of products in imbricated formation to gripping members (12) in connection with a moved chain conveyor (14) , the gripping members being moved along a path past a delive¬ ry end of a conveyor for the row of imbricated products, where the gripping members (12) are successively actua¬ ted to grip the products, the gripping members generally being advanced with the same speed as the products, characterized in that the row of imbricated products is currently transferred from its ordinary conveyor (4) to a delivery conveyor (10) , which is driven at increased speed so as to actively project the leading edges of the delivered products (2) into the passing gripping members (12) prior to the respective actuations thereof. |
| 2. | A method according to claim 1, characterized in that the delivery conveyor (10) is driven in synchronism with the chain conveyor (14) and that the associated driving means (16) are operatively connected with sensor means (20) for detecting the front edge passage of the products on the ordinary conveyor (4) . |
| 3. | A method according to claim 1, characterized in that the products on the ordinary conveyor are delivered to the delivery conveyor in a lower level. |
| 4. | A method according to claim 3, characterized in that the delivery end portion of the ordinary conveyor is a conveyor section (4) of the type, the delivery end of which is horizontally adjustable, and that the loca¬ tion of the delivery end is adjusted according to the length of the products. |
| 5. | A method according to claim 1 or 4, characte¬ rized in that the product row is kept pressed down against the reversing roller (6) , from which the deli¬ very to the delivery conveyor takes place. |
| 6. | A method according to claim 5, characterized in that with the use of pressure wheels (26,28) above the delivery conveyor a comoved pressure is exerted down¬ wardly against the front edge area of each newly deli¬ vered product over a short movement path thereof, upon the product at its rear end having passed out of the pressure engagement (6,22) at the delivery end of the ordinary conveyor (4) . |
| 7. | A system for exercising the method according to the preceding claims, characterized in having means enabling such exercising. |
The present invention relates to a system for deli¬ vering printhouse products, in particular folded newspa¬ pers, from a moved flow of products in imbricated forma¬ tion to gripping means in connection with a chain con¬ veyor. Mainly by the production of newspapers in rotary presses it is customary that the papers are delivered in imbricated formation on a conveyor belt, but at a later stage of the flow it may be desirable that the flow is guided both upwardly and downwardly, whereby it is actu¬ al to let it be transferred to conveying means that may positively hold the single products, this suitably being done by means of a chainlike gripping conveyor. This latter should then be equipped with suitably interspaced grippers that can be actuated for gripping the products advanced on the conveyor belt.
The product flow appears with a relatively high velocity, and in practice it has been found that it is very problematic to arrange for the relevant transfer in a fully safe manner. For natural reasons it is highly disturbing if the transfer gets out of order, as the rotary press can only be stopped by extreme emergencies once the production has started.
Generally, according to the invention, a transfer with increased safety is obtainable when there is ar¬ ranged, immediately before the place of transfer, an acceleration of the products advanced on the conveyor belt, such that these can be brought to be actively projected into the further conveying gripping means of the gripping chain system. These grippers, for natural reasons, should be advanced in synchronism with the products on the first conveyor, but in successively either raising the delivery speed of the products or periodically lowering the receiver velocity of the grip-
ping means it will be achievable that the leading edges of the advanced products be brought into a safe engage¬ ment with the gripping means of the succeeding gripping conveyor.
It is quite important, however, that the products are accelerated in a uniform manner. From the rotary press they are delivered with a non-uniform precision in the imbrication pattern, and care must be taken that after the acceleration they are delivered to the grip¬ ping chain in an at least almost uniform manner. It has been found that the products in the imbricated formati¬ on, when transferred from the first conveyor directly to the faster conveyor, may become mutually spaced in an irregular manner in the accelerated row of products, and for the invention it is important to indicate how this problem can be overcome. It will be possible to use one or more of the following measures:
1) In the transfer area, use is made of an overly¬ ing pressure belt at the delivery end of the supplying conveyor belt, such that the products are not released for any relative displacement until after their rear ends having left this area, i.e. from a location where a certain displacement force may already have been applied to the products. In case of minor differences the pro¬ ducts might otherwise be projected into mutually diffe¬ rent positions, and this will be counteracted by the measure mentioned here.
2) The receiving acceleration conveyor is mounted in a level somewhat lower than the feeding conveyor, whereby the row of imbricated copies carries out a cer¬ tain dive in the transition area. In this dive the copi¬ es will be freely carried and be moving downwardly, whereby the friction between them will be reduced in the critical transfer area. This will contribute to ensure that small differences in the friction between the pro¬ ducts will not give rise to noticeable mutual displace-
ments between the products when these are caused to be projected by the action of the acceleration belt.
3) Above the acceleration conveyor there is mounted a rotary roller having projecting fingers or ribs which, by a synchronized movement, can operate to press down the front edge area of the successively advanced pro¬ ducts, down against the acceleration conveyor. Hereby it is possible to work with quite well defined moments of this conveyor effectively taking over the control of the product conveyance. Inasfar as the products may vary in thickness, the relevant receiver area of the conveyor should be resiliently supported, such that the pressing down may take place with a well adapted force irrespec¬ tively of the thickness of the row of products.
In the following, the invention is described in more detail with reference to the drawing, which shows a side view of a transfer system according to the inventi¬ on.
A row of printed products in imbricated formation, e.g. newspapers 2, is delivered to a first conveyor 4 having an upper effective run, which is length variable in that a delivery roller 6 may be moved horizontally for adjustment of the system. This conveyor is driven by a motor 8 in synchronism with the feeding belt.
After the conveyor 4 another conveyor 10 receives the row of newspapers at a somewhat lower level, such that the paper row is moved in a non-supported dive over a certain distance. The latter conveyor accelerates the papers and delivers them successively to grippers 12 on a gripping chain 14, which, together with the conveyor 10, is driven by a motor 16. The two parts should be driven in synchronism, with the chain 14 slightly slow- lier than the conveyor. The newspapers are delivered in being projected over an outlet roller 18, whereby their folded front edges are projected into the grippers 12, which are automatically closed so as to take over the
conveying of the papers. A good gripping engagement is ensured by virtue of the papers being advanced with a higher speed than the grippers, such that the paper front edges may reach the bottom of the grippers before these are closed. This is important both for the grip¬ ping security and for the order with which the papers are delivered from the chain conveyor.
However, for such a transfer of the products to be safe, it is a condition that the products be guided such that their front edges are located in a precise manner for engaging with the gripper. To a certain extent this is achievable by controlling the phase of the gripping chain relative to the arrival of the product front ends, but this is not fully safe, because there may be irregu¬ larities both in the supplied product row and in the uniformity of the acceleration of the products on the conveyor 10; this acceleration is counteracted by the products initially sliding on the conveyor 10 and by the products being held back by the overlying products in the imbricated row.
A superior control may be provided for by means of a sensor 20 detecting the passage of the product front edges on the first conveyor 4 and causing the motor 16 to be adjusted until a correct engagement is ensured.
By the said dive of the product row between the two conveyors 4 and 10 it is obtained that the friction between the products in the very transfer area will be reduced, whereby variations in the product friction will be of reduced influence on the accuracy of the transfer.
According to the invention, however, it is both de¬ sirable and possible to further improve the safety, viz. in anchoring the products to the conveyor 4 as long as they are still resting thereon and/or bringing the pro¬ ducts to engage the conveyor 10 with increased friction as soon as they have left the conveyor 4. Thereby it is avoided that the transfer accuracy is influenced by
variations in the sliding friction between the over¬ lapping products.
The anchoring of the products to the conveyor 4 is effected by means of a pressure roller 22, pressing down against the delivery roller 6, preferably by intermedi¬ ate of a pressure belt 24, which will guide the product front edges safely under the roller 22. When the roller 22 or a corresponding row of interspaced short rollers is rotated with the same peripheral speed as the speed of the conveyor 4 the products 2 will be prevented from being drawn out from this engagement by the relatively weak pulling force exerted by the frictional engagement between conveyor 10 and the foremost portion of the products. Thus, the acceleration of the products cannot start until the moment where the rear end of the pro¬ ducts leave the pressure engagement at the delivery rollers 6 and 22. For obvious reasons the roller 22 should be adapted to follow the roller 6 in the horizon¬ tal adjustment movements thereof.
The said strengthened frictional engagement between the products 2 and the conveyor 10 may be obtained by means of a roller 26 arranged above this conveyor and driven through a transmission 24 from the motor 16, the roller having protruding ribs or fingers 28, which, by the rotation of the roller, will successively press the front edge areas of the products 2 down against the ac¬ celeration belt 10. Beneath this pressure area the belt 10 is supported by a resilient element 30, such that the pressing down can be done with almost the same force, irrespectively of the thickness of the product row.
It is of a noticeable effect that between the rol¬ lers 22 and 26 there is a distance a, which corresponds to or is just slightly larger than the length of the products 2. This may be preadjusted by displacing the pair of rollers 6,22. If a tendency arises for a change of the passages of the front edges at the critical mo-
ments of time, the sensor 20 will provide for such an adjustment of the motor 16 that the ribs or fingers 28 will again step correctly on the products, e.g. a couple of centimetres behind their front edges. Thereafter the products will automatically arrive at the grippers in a correct manner.
Preferably, the roller 26 is made of two mutually separated wheels which cooperate with the products near the opposed side edges thereof, i.e. in areas where there is no printing ink on the products. Also the free dive of the product row in the transition area contri¬ butes to avoiding smearing out of printing ink.