GB2066780A - Method and apparatus for transporting sheets - Google Patents

Abstract

In a paper feeder wherein sheets are lifted by means of a suction head the number of movements of sheets from one position to another cannot be increased by increasing the speed as the speed at which the sheet is moved must not exceed a certain limit in order to prevent the paper from crumpling or flying. By using a method and an apparatus wherein it is the same suction head which both lifts and transports sheets the required distance from pile to conveyor belt and with an additional suction head (15) for moving sheets (1), the moving capacity can be doubled without increasing the speed. The apparatus is provided with suction heads (15) on arms (12) which are moved from a central shaft (7) by cam discs (8, 9) and rods (10, 11) in such a way that the path of movement of the arms does not cross each other, the return path running over the feeding path. <IMAGE>

Description

SPECIFICATION Method and apparatus for transporting sheets Method for transporting sheets from one position to another such as from a pile to a conveyor belt in a paper feeder where the top sheet of the pile is lifted by means of a suction head and then transported to the conveyor belt by means of a motion system, whereas the suction head is moved down to the top sheet of the pile and the movement is repeated, and an apparatus for carrying out the method.

When putting together sheets which are to be placed in a certain order, f.inst. notebooks, pads, debit notes etc., a so-called paper feeder is used.

This consists of a number of juxtaposed stations for placing piles of sheets consisting of the paper which according to the order has to be placed before the sheet of the pile to the one side and after the sheet of the pile to the other side of the completed pile.

Over each pile there is placed a suction head which lifts the top sheet whereupon f.inst. a gripping device or a tape drive carries the top sheet across the machine and onto a longitudinal conveyor belt which conveys the sheets one after another to a collecting pile where the sheets are placed on top of each other in the pre-determined order.

There are machines which are provided with up to 25 stations and which can thus place 25 sheets in a pre-determined order in the completed pile at the end of the conveyor belt.

By a known method the suction head is lowered at the front edge of the paper in the pile at the same time as air is blown horizontally from the side between the top sheets which are thereby separated. In this way the suction head can easily lift the top sheet whereupon a gripping or holding device carries the sheet to a position above the conveyor belt where it is dropped.

By the known methods the speed from the pile to the conveyor belt depends on the type of paper to be transported as in connection with thin types of paper, such as carbon paper and the like, the speed has to be suitably low to prevent the paper from flying or crumpling and thus rendering the further transportation impossible. This means a substantial reduction in output as it is not possible to increase the speed by the known methods.

It is the object of the invention to remedy this deficiency and this is achieved by a method where, when the suction head has lifted the top sheet from the pile and transported it from the pile to the conveyor belt, a second suction head is carried to the pile where the following sheet is held and transported to the conveyor belt and in such a way that when returning to the pile the suction head describes a path which does not collide with the suction head moving a sheet. By this method a considerably greater capacity is first and foremost achieved, the sheets being delivered at a number which with two sets of suction heads is the double of the previously known - and without moving the paper any faster through the air from the pile to the delivery on the conveyor belt.Furthermore, this transport is effected in a very safe and reliable way as it is the same suction head which lifts, moves and delivers the sheet. Thus the slow and unreliable gripping device or tape drive which was previously necessary for transporting the sheet across the machine is avoided. This simplifies the method and contributes to increasing the output speed.

By using the apparatus disclosed in claim 2 with the suction heads mounted on an arm corresponding to the number of suction heads for each pile a safe transport is achieved, all lifts and deliveries taking place at exactly the same time as each arm can be operated synchronically.

Moreover, as disclosed in claim 3, it is suitable to let the returning arm pass over the arm moving a sheet which can thus describe a straight path from pile to delivery position.

Finally, as disclosed in claim 4, it is advantageous to control all movements from a single driving shaft.

The invention will be further described in the following with reference to the drawing, wherein Fig. 1 shows a perspective view of a skeleton drawing of the movable parts and Fig. 2 shows a skeleton drawing of the sheet transportation from pile to conveyor belt.

As it appears from Fig. 1, schematically showing the traversing transport section in an embodiment of a paper feeder, said feeder is provided with a central rotating shaft 7 whereto there are secured some sets of cam discs 8 and 9 corresponding to the number of suction heads on arms 12.

A system of articulated rods 10 and 11 engages each cam disc to the effect that the arms 12 secured to the rods are set in motion when the shaft rotates.

A number of holders 14 for suction heads 15 are secured to the arms 12. There are shown five sets of suction heads corresponding to five stations and thus five piles. Less or more stations are possible, the machine merely being made shorter or longer lengthwise.

When the shaft 7 rotates, the arms are set in motion and thus the suction heads as is sketched in Fig. 2 showing a cycle for an embodiment having two suction heads for each pile. At a station 3 there is a pile 2. The top sheet is kept at the same level by generally known means e.g. in the form of a vertically adjustable support.

Air 4 is supplied from the side through not shown nozzles for separating the top sheets. In this way a reliable lifting of sheets is ensured by means of the suction head shown in a dot-anddash line which holds the sheet by a partial vacuum through the mouth piece.

When the cam discs rotate, the arms are moved by the rod 10 to the left on the drawings carrying a sheet 1 as is shown in a solid line in Fig. 2.

Longitudinally to the machine there is provided a not shown conveyor belt, a cross-section of which is shown in Fig. 2 and which by means of movable teeth 6 or the like conveys the sheets to a collecting or complete pile at the end of the conveyor belt 5.

When the mouth piece with the sheet has been carried all the way to the left on the drawings, the vacuum source is cut off and the sheet drops down onto the conveyor belt.

The mouth piece itself is now by means of the cam disc 8 and the rod 10 carried back towards the pile but this time it describes a changed path as is shown by arrows in Fig. 2. The cam disc 9 moves the rod 11 which lifts the arm 12 and thus the mouth piece 1 5 over the feeding path so that the other arm can pass under it with a sheet.

In this way it is possible to work at twice the normal speed as the two mouth pieces synchronically carry sheets from the pile to the conveyor belt which can thus work at twice the speed without increasing the speed of the mouth piece with a sheet.

In another embodiment there is only secured one mouth piece to each arm so that each station is operated by one set of arms having one mouth piece on each arm, said arms being moved by rods and cam discs as mentioned above. In this way it is possible to construct the machines in modules as each station is an independently working unit with the cam discs mounted on a common shaft.

In practice it will be possible to work with more than two arms with mouth pieces, and this is possible if at both ends there are provided slideways wherein the arms slide. By thus being able to move a suitable number of arms in these slideways, the number of movings can be increased correspondingly.

The method has been described with reference to a paper feeder but, naturally, it can be used all places, especially within the printing technique, where there is a need for moving sheets from one position to another and at the same time obtaining the same advantayes as described above.

Claims (6)

1. Method for transporting sheets from one position to another such as from a pile to a conveyor belt in a paper feeder where the top sheet of the pile is lifted by means of a suction head and then transported to the conveyor belt by means of a motion system, whereas the suction head is moved down to the top sheet of the pile and the movement is repeated, characterized in that when the suction head ( 1 5) has lifted the top sheet (1) from the pile (2) and transported it from the pile to the conveyor belt (5), a second suction head (15) is carried to the pile (2) where the following sheet is held and transported to the conveyor belt and in such a way that when returning to the pile (2) the suction head (15) describes a path which does not collide with the suction head moving a sheet (1).

2. Apparatus for carrying out the method according to claim 1, and wherein one or several suction heads are secured to a mounting arm which is moved by means of articulated rods operated by cam discs, characterized in that the number of arms (12) corresponds to the number of suction heads (15) for each pile (2), and that each arm (12) is connected to articulated rods (10, 11) which carry the arm (12) in its path.

3. Apparatus according to claim 2, characterized in that the path of the arm (12) goes directly from the lifting position by the pile (2) to the delivery position by the conveyor belt (5), whereas the return path describes a path over the direct path.

4. Apparatus according to claims 2 and 3, characterized in that the cam discs (8, 9) are connected to a common driving shaft (7).

5. A method for transporting sheets from one position to another, substantially as herein described.

6. Apparatus for transporting sheets from one position to another, substantially as herein particularly described with reference to the accompanying drawings.