Sheet Delivery Device

1. Field of the Invention

This invention relates to a sheet delivery device adapted for use in a paper feeding device of a corrugated cardboard box making machine and the like.

2. Description of the Prior Art

Describing a conventional sheet delivery device used in a paper feeding device of an ordinary corrugated cardboard box making machine with a reference to FIGS. 3, 4 and 5, reference numerals 1a through 1n indicate corrugated cardboard sheets, 2 is a front stopper, 3 is a back stopper, 4 is a gap, 5 is a print cylinder, 6 is a lever, 7 is a link, 8 is a moving suction box, 9 is a suction hole, 10 is a slidable pipe section, 11 is a rotary valve, 12 is a suction tank, 13 is a suction blower, 14 is an upper feed roll, 15 is a lower feed roll, 16 is a crankshaft, 17 and 18 are gears, 19 is a reduction gear and the like, 20 is a motor, 22 is a crank lever, 23 is a grooved lever, 24 is a receiving roll, and 25 is a gear. The corrugated cardboard sheets 1a through 1n supplied from a preceding process are piled in a space surrounded by the front stopper 2, side guides (not shown) and back stopper 3. In order to prevent the whole weight of the piled sheets from being applied to the lowest corrugated cardboard sheet 1a, the sheets are divided into two stacks or layers by the back stopper 3 and one stack is piled on the other. At the lowest corrugated cardboard sheet 1a is delivered through the gap 4 which is formed at the lower end of the front stopper 2 and designed so as to permit passage of that lowest one 1a, the lowest corrugated cardboard sheet out of the upper stack falls on the lower stack. Delivery of the corrugated cardboard sheet 1a is carried out by the moving suction box 8 which performs reciprocation in a sheet delivery direction in response to rotation of the print cylinder 5 via the crank lever 22, grooved lever 23, lever 6 and link 7. Specifically, in response to one revolution of the print cylinder 5 the crank lever 22 rotates one turn and the mechanism composed of the grooved lever 23, lever 6 and link 7 performs one reciprocative swing, this being transmitted to the suction box 8. A portion of the moving suction box 8 which contacts the lowest corrugated cardboard sheet 1a is formed with a number of suction holes 9 (see FIGS. 4 and 5). The interior of the moving suction box 8 is connected to the suction blower 13 through the sealed slidable double pipe mechanism 10, rotary valve 11 and suction tank 12. The rotary valve 11 operates such that it exerts a suction pressure only while the moving suction box 8 is advancing in response to swinging of the lever 6 which is synchronized in timing such that one corrugated cardboard sheet 1a can be delivered in response to one revolution of the print cylinder 5. In response to the above, the moving suction box 8 sucks the corrugated cardboard sheet 1a and moves the same through the gap 4 formed at the lower end of the front stopper 2 thereby to deliver in the direction of the arrow at the same rate as the circumferential speed of the print cylinder 5. The thus delivered corrugated cardboard sheet 1a is pushed to a nip section between the upper feed roll 14 and lower feed roll 15 and then sent to the print cylinder 5 and receiving roll 24 of a succeeding process step. The print cylinder 5, upper and lower feed rolls 14, 15, and crank lever shaft 16 are coupled through the gears 17, 18, 25, reduction gear 19 and the like to the motor (single driving source) 20 and driven thereby.

In operation of the conventional sheet delivery device shown in FIGS. 3, 4 and 5, the corrugated cardboard sheet 1a delivered by the moving suction box 8 shows some variation in delivery timing and an error appears in a following process step (such as a printing process). Specifically, a deviation of timing appears frequently in cases as follows: (1) if the sheet is delivered at high speed (in this case, although the corrugated cardboard sheet 1a follows the movement of the moving suction box 8 after suction is applied, there exists some time lag before the moving suction box 8 exerts its suction effect), (2) if the corrugated cardboard sheet 1a has a warp as shown in FIG. 5 (in this case, due to the presence of the gap 21 such a corrugated cardboard 1a needs additional time after it is sucked before it should be moved; thus, it tends to be fed obliquely), (3) if the corrugated cardboard sheet 1a has a small coefficient of surface friction (such as a coated sheet in this case, slippage tends to occur between the sheet and the moving suction box 8).

The present invention has been devised in order to solve the foregoing problems of the prior art, and the object of the present invention is to provide an impoved sheet delivery device which can correct a deviation in delivery timing and deliver reliably a sheet to equipment positioned on the downstream side of the delivery device.

In brief, a sheet delivery device according to the present invention includes a moving suction unit for delivering a sheet and feed rolls for receiving and delivering the sheet delivered by the moving suction unit and is characterized by a control unit which detects whether or not each sheet is delivered in synchronization with the operation timing of sheet processing equipment positioned on the downstream side of delivery effected by the feed rolls and sends a signal obtained when no synchronized delivery takes place to a rotation driving unit of the feed rolls thereby to change the revolution speed of the feed rolls.

FIG. 1 is a side view showing a first embodiment of a sheet delivery device according to the present invention;

FIG. 2 is a perspective view showing a second embodiment of the present invention;

FIG. 3 is a side view showing the conventional sheet delivery device;

FIG. 4 is a perspective view of a feed roll section of the device shown in FIG. 3; and

FIG. 5 is a perspective view showing a sheet with warps.

A sheet delivery device according to the present invention will now be described with reference to FIG. 1 showing a first embodiment, in which reference numerals 1a through 1n indicate corrugated cardboard sheets, 2 is a front stopper, 3 is a back stopper, 5 is a print cylinder, 6 is a lever, 7 is a link, 8 is a moving suction box, 9 is a suction hole, 10 is a slidable pipe and the like, 11 is a rotary valve, 12 is a suction tank, 13 is a suction blower, 14 is an upper feed roll, 15 is a lower feed roll, 16 is a crankshaft, 17 and 18 are gears, 19 is a reduction gear and the like, 20 is a motor, 22 is a crank lever, 23 is a grooved lever, 24 is a receiving roll, 26 and 27 are pulse oscillators, 31 is a sheet position sensor means such as a phototube, 32 is a mirror, 33 is a motor, and 34 is a heat processing equipment sensor means such as a reference switch. The motor 33, pulse oscillator 26, pulse oscillator 27, reference switch 34 and phototube 31 are each individually connected to a control unit 43, shown in FIG. 1. The different aspects of the present embodiment from the conventional device include the phototube 31 and the mirror 32, which are disposed respectively above and below a passageway section of the corrugated cardboard sheets 1a defined between the upper feed roll 14 and the print cylinder 5, by which arrival of the corrugated cardboard sheet 1a at a reference position is detected. Although the conventional device used the motor 20 (the single driving source) the drive the print cylinder 5, upper and lower feed rolls 14, 15, and crank lever shaft 16, the present embodiment differs therefrom as follows. That is, in the present invention, the print cylinder 5 is driven by the motor 20 and the upper and lower feed rolls 14, 15 are driven by the motor 33. The extent of partial revolution each of the print cylinder 5, upper and lower feed rolls 14, 15 is detected by means of pulse counting with the pulse oscillators 26, 27. The delivery timing of the corrugated cardboard sheet 1a is made to agree with the operation timing of the print cylinder 5 by taking the reference switch 34 disposed above and opposite to the print cylinder 5 as a reference point. Other arrangements not mentioned above are identical to those of the conventional device.

Operation of the foregoing sheet delivery device shown in FIG. 1 will now be described. In order to supply one corrugated cardboard sheet 1a in compliance with one revolution of the print cylinder 5, the moving suction box 8, which performs one linear reciprocative motion in response to one reciprocation (swinging) of the lever 6 and link 7, delivers one corrugated cardboard sheet 1a in phase with the timing of the rotary valve 11 which makes effective a suction pressure only during the advancement stroke of the suction box 8. At this moment, the reference switch 34 is opposite to a reference point corresponding to a detection segment 34' provided on the print cylinder 5. The oscillator 26 is provided for pulse counting pulses corresponding to the extent of partial rotation which is given by subdividing one revolution of the print cylinder 5, whereby a set of pulses can be counted, each pulse corresponding to a fractional part of one revolution of the print cylinder 5. The pulses sent out from the oscillator 26 to the control unit 43 are cleared and restarted from zero count each time the detection segment 34' passes over the reference switch 34. The phototube 31 is provided for detection of arrival of the front end of the corrugated cardboard sheet 1a. The thus obtained detection signal and the foregoing pulse signal are processed by the control unit 43 to compute a degree of delay in delivery of the corrugated cardboard sheet 1a with respect to a degree of rotation of the print cylinder 5, and a control signal in the form of the thus obtained degree of delay is sent from the control unit to the motor 33 to control the revolution speed of the motor 33. The process of such control as above, i.e. the process of causing the detection segment 34' of the print cylinder 5 to reach the position 5'" when the front end 1a' of the corrugated cardboard sheet 1a comes to the same position 5'" of the print cylinder 5, will now be described in detail. The distance l.sub.1 from the position of the phototube 31 to the position 5'" is set equal to the circumferential distance L.sub.1 from the position 5" on the print cylinder 5 to the position 5'". Further, a certain number of pulses, for example, 100 pulses, are preset for the foregoing distance l.sub.1. If the detection segment 34' of the print cylinder 5 hs passed beyond the position 5" by a distance corresponding to the interval of three pulses at the time the front end 1a' of the corrugated cardboard sheet 1a reached the position of the phototube 31, this interval corresponding to three pulses is understood to be a delay time of the corrugated cardboard sheet 1a. Therefore, it is necessary to advance the corrugated cardboard sheet 1a a distance corresponding to 100 pulses while the print cylinder 5 rotates up to the position 5'", i.e. a circumferential distance corresponding to 97 pulses. Accordingly, by means of the foregoing control signal the revolution speed of the motor 33 is increased to increase the peripheral speed of the feed rolls 14, 15 while the corrugated cardboard sheet 1a is advancing a distance corresponding to the circumferential distance L.sub.1. When the revolution speed is increased and has reached a given rate, the peripheral speed of the feed rolls 14, 15 is controlled so that it becomes equal to that of the print cylinder 5.

As described hereinabove, the sheet delivery device according to the present invention includes the moving suction unit for delivering a sheet and the feed rolls for receiving and delivering the sheet delivered by the moving suction unit, is characterized by the control unit 43 which detects whether or not the sheet is delivered in synchronization with the operation timing of equipment positioned on the downstream side of delivery effected by the feed rolls and sends a signal obtained when no synchronized delivery takes place to the rotation driving unit of the feed rolls thereby to change the revolution speed of the feed rolls, operates in such a manner as described hereinabove, and, thus, provides the following effect. In case the print cylinder performs high speed printing, the desired timing of the mechanical operation can easily be attained. If the suction action caused by vacuum pressure is combined with the mechanical operation, the resultant timing becomes unstable and a time lag arises. Because the sheet delivery device delivers the corrugated cardboard sheets and the like by the use of the moving suction unit, variation easily occurs in delivery timing of the corrugated cardboard sheets and the like. However, the present device having the foregoing structure and operating in the foregoing manner can correct any deviation of timing and effectively deliver the corrugated cardboard sheets and the like to the print cylinder or like sheet processing equipment or units.

A second embodiment of the sheet delivery device according to the present invention will now be described with reference to FIG. 2. In this second embodiment, a sheet orientation sensor means such as a plurality of phototubes 36, are arranged on a vertical surface perpendicular to the advancing direction of the corrugated cardboard sheet 1a between a first upper feed roll 37 and a second upper feed roll 37' and the print cylinder 5 (see FIG. 1), and detect arrival of the corrugated cardboard sheet 1a. The upper and lower feed rolls are divided with respect to the transverse of the feed roll assembly center into a first A-side feed roll 37 and a second B-side feed roll 37', the adjacent ends of the upper feed rolls 37, 37', near the transverse center of the feed roll assembly, are supported rotatably by an upper bearing 40, and the opposite ends of the rolls 37, 37' are coupled to an A-side motor 39 and a B-side motor 39', respectively. A first lower feed roll 38 and a second lower feed roll 38' are structured similarly to the above, except for the motors 39, 39'. The A-side upper and lower feed rolls 37, 38 are rotated in the respective directions of the arrows by the A-side motor 39 via a pair of gears 42, and the B-side upper and lower feed rolls 37', 38' are rotated in the respective directions of the arrows by the motor 39' similarly to the A-side unit.

Operation of the foregoing sheet delivery device shown in FIG. 2 will now be described. The corrugated cardboard sheet 1a with warps needs a long time before complete suction is effected because of the presence of the gap 21, and tends to be fed obliquely, as shown in FIG. 5. In this second embodiment, passage of the corrugated cardboard sheet 1a delivered obliquely is detected by the plurality of phototubes 36, whereby positional discrepancy between the left end and right end of the sheet is adjusted in orientation by means of a control unit 43, which is connected to the motors 39, 39' and the phototubes 36, for rotation control over the A-side upper and lower feed rolls 37, 38 and the B-side upper and lower feed rolls 37', 38' before the corrugated cardboard sheet 1a reaches the print cylinder 5. The process of sheet orientation adjustment control on the second embodiment is similar to the first embodiment shown in FIG. 1. Specifically, in the second embodiment, the motors 39, 39' for the A-side upper and lower feed rolls 37, 38 and the B-side upper and lower feed rolls 37', 38' are controlled individually by the control unit 43. In the exemplary state shown in FIG. 2, the right end of the corrugated cardboard sheet 1a deviates rearward with respect to the left and right phototubes 36, 36; thus, the revolution speed of the A-side upper and lower feed rolls 37, 38 must be increased in comparison to the B-side upper and lower feed rolls 37', 38'. In the case of using the divided feed rolls, the set of upper and lower feed rolls 14, 15 shown in FIG. 1 is merely replaced by the set of divided feed rolls.

Similarly to the first embodiment, the second embodiment of the sheet delivery device according to the present invention shown in FIG. 2 and described hereinabove includes the moving suction unit for delivering a sheet and the feed rolls for receiving and delivering the sheet delivered by the moving suction unit, is characterized by the control unit 43 which detects whether or not the sheet is delivered in synchronization with the operation timing of sheet processing equipment positioned on the downstream side of delivery effected by the feed rolls and sends a signal obtained when no synchronized delivery takes place to the rotation driving unit of the feed rolls thereby to change the revolution speed of the feed rolls, and provides the same effect as that of the first embodiment shown in FIG. 1. In addition, the second embodiment provides the advantage that it can take away a deviation in desired orientation of the sheet which tends to appear between the left and right end portions before the sheet is sucked by the moving suction unit or in the course of delivery action due to warps and/or delivery resistance of the sheet that may cause the sheet to be delivered obliquely.

While the preferred embodiments have been described, variations thereto will occur to those skilled in the art within the scope of the present inventive concepts which are delineated by the following claims.