Apparatus For Feeding And Stacking Loose Paper Sheets

Abstract

An apparatus for feeding and stacking loose paper sheets having a stacking station with an upstanding end stop for the sheets to be stacked and a lower and upper endless conveyor belt for clamping the sheets to be stacked therebetween and feeding the sheets to the stacking station. The lower conveyor belt extends underneath the stacking station and the upper conveyor belt passes around a return roller arranged a small distance upstream of the stacking station. Side guide members are arranged on each side of the lower conveyor belt for supporting the side portions of the sheets which side guide members are inclined from the lower conveyor belt downwardly and outwardly whereby the sheets are bent in the transverse direction. The side guide members and the lower conveyor belt have portions extending obliquely upward in the direction of feed of the sheets from a point lying upstream of the forward or upstream side of the stacking station to a point lying under the stacking station whereby any sheet fed without being overlapped by the preceding sheet can be pushed without disturbance, and without damaging its front edge, under the stack formed at the stacking station.

Description

BACKGROUND OF THE INVENTION

The invention generally relates to apparatus for feeding and stacking loose paper sheets. More in particular, the invention relates to such apparatus comprising a lower endless conveyor belt and an upper endless conveyor belt adapted to clamp the sheets to be stacked between them for feeding the sheets to a stacking station having an upstanding end stop for the sheets at the front or downstream side thereof, in which the lower endless belt extends under the stacking station and the upper endless belt passes around a return roller mounted for vertical movement a short distance upstream of the stacking station and urged downwards towards the lower endless belt. In this connection, the term "loose sheets of paper" means not only single sheets but also sheets folded a number of times, such as newspapers, periodicals, leaflets, and the like.

An apparatus of the above-mentioned kind is described in my co-pending U.S. Pat. application Ser. No. 51,184 and the construction described therein is intended particularly for stacking freshly printed newspapers which are delivered in rapid succession by the conveyor belts to the stacking station in a continuous stream, the sheets being held between the upper and lower conveyor belts while overlapping one another in a pantile-like arrangement with the forward edge part of each sheet underlying the rear edge part of the preceding sheet. At the stacking station, the sheets fed thereto thus successively slide underneath the stack being formed, to be lifted off by a periodically activated separating device after a stack of newspapers containing a pre-determined number of sheets has been formed which stack may then be discharged by further conveyor means. In this arrangement of my said co-pending application, the conveyor belt runs over rollers which are mounted in a frame articulated on the feed side of the apparatus, so that under the weight of this frame the upper conveyor belt is pressed onto the stream of sheets fed forward and can aline itself in the vertical direction in accordance with the thickness of the paper sheets. The apparatus further comprises side guide members arranged on both sides of the lower conveyor belt for supporting the side portions of the sheets which side guide members are inclined from the lower conveyor belt downwardly and laterally outwardly. The sheets supported by these side guide members are thus bent in the transverse direction whereby the paper stream fed forward and also the stack formed therefrom is given adequate stiffness in the longitudinal direction to prevent the sheets from undergoing relative displacement and to enable the sheets to slide smoothly under one another at the stacking station, while at the same time the separation and removal of the finished stacks are facilitated thereby.

In a stacking apparatus of the kind described the problem arises that if for any reason the continuous stream of paper is interrupted the front edge of the first sheet following this interruption can strike against the rear edge of the preceding sheet and consequently finds it difficult to slide under the stack, so that serious disturbances may occur. This difficulty also arises when the sheets are not fed in an overlapping pantile arrangement, but follows one another at a shorter or longer distance.

SUMMARY OF THE INVENTION

Accordingly, the invention has for its main object to provide a feeding and stacking apparatus of the above described kind which overcomes these difficulties and which allows a smooth stacking operation also in case successive sheets fed by the conveyor belts do not overlap one another.

To this end, in the apparatus according to the invention the side guide members have portions extending obliquely upwards in the feed direction of the sheets from a point lying upstream of the forward or upstream side of the stacking station to a point lying under the stacking station and in a similar way means are provided for guiding the lower conveyor belt obliquely upwards from a point upstream of the forward side of the stacking station to a point underneath the stacking station. In this way any sheet fed without being overlapped by the preceding sheet is guided under the stack formed at the stacking station and can be pushed under this stack without disturbance and without damaging its front edge since this edge cannot come into contact with the rear edge of the lowermost sheet of the stack.

According to a preferred embodiment of the invention the lower conveyor belt has a support provided with an aperture which extends from a point some distance upstream to a point downstream of the rear side of the stacking station and under the return roller for the upper conveyor belt, a supporting roller for the lower conveyor belt being disposed in said aperture, so that downstream of said supporting roller the return roller presses the lower conveyor belt downwards in a curve. As long as a continual stream of paper composed of overlapping sheets of paper is fed, these sheets of paper, taken as a whole, have sufficient stiffness, because of their transverse bending, to ensure that the return roller is practically unable to press the sheets and the bottom conveyor belt running under them downwards in a curve downstream of the supporting roller, or can do so only to a very slight extent, so that the paper stream runs into the stacking station on a practically rectilinear path. As soon as the stream of paper sheets is interrupted, however, because of the lack of overlapping the front edge of the sheet following this interruption will offer substantially less resistance to the downwardly directed compressive force of the return roller of the upper conveyor belt, so that said return roller can now easily press the front edge of said sheet downwards in a curve, and thus the edge can be effectively pushed under the rear edge of the preceding sheet and thus under said sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

A fuller explanation of the invention is given in the following description of a preferred embodiment, given by way of example with reference to the accompanying drawings, in which the parts not essential to an explanation of the invention are omitted, and in which:

FIG. 1 is a side elevation of the apparatus,

FIG. 2 a view in perspective of the apparatus, viewed obliquely from above, and

FIG. 3 a cross-section through FIG. 1 along the line III-III, viewed in the direction of the arrows.

PREFERRED EMBODIMENT OF THE INVENTION

The apparatus illustrated is provided with a lower conveyor belt 1 which is driven in the direction of the arrow in FIG. 1 and which feeds and supports in the center thereof the paper sheets 2, for example newspapers, to be stacked. This conveyor belt 1 runs under the stacking station 3 of the apparatus to a driving and return roller 4, from which it returns to the inlet side of the apparatus (not shown). The upper, operative run of this conveyor belt 1 runs over a support bar which is formed by a channel section 5 the side flanges of which point downwards and the web of which is wider that the conveyor belt 1 running over it. At its front or downstream side the stacking station 3 is provided with an end stop 6 which is upstanding transversely to the conveyor belt 1 and against which the fed sheets 2 strike by their front edge, so that a stack 7 of sheets is formed. The paper sheets 2 are normally fed in a continuous stream, overlapping one another in a pantile arrangement with the front edge of each sheet extending a certain distance under the preceding sheet. The stack 7 is consequently formed from below, the successive sheets being pushed under one another one after the other. The stacking station is also provided with arrangements (not shown in the drawings) for separating and discharging the stacks, each of which consists of a given number of sheets, and together with the appertaining seperating and discharge devices may for example be constructed as described in my previously mentioned co-pending U.S. Pat. application Ser. No. 51,184.

A driven upper conveyor belt 8 moves over the bottom conveyor belt 1 and runs from a drive roller 9 downwards to a guide roller 10 and from the latter forwards to a return roller 11 which is situated a short distance upstream of the rear side of the stacking station 3 or stack 7 and from which this upper conveyor belt then returns over a tensioning roller 12 to the drive roller 9. The rollers 10, 11 and 12 are mounted on arms 13, 14 and 15 of an upper frame which is swivellable about the axis of the drive roller 9, so that under the weight of this frame the conveyor belt 8 is pressed onto the stream of sheets 2 supported on the conveyor belt 1, whereby the upper belt 8 can adapt itself to the thickness of the sheets being fed. The conveyor belts 1 and 8 are in addition driven at the same speed, so that they clamp the paper sheets between them in the center and together move them forwards. The lower structure of the apparatus, which is only indicated diagrammatically in the drawings, may be constructed as described in detail in my above-mentioned co-pending patent application.

The channel section or support bar 5 for the lower conveyor belt 2 has an aperture 16, the web of this channel section being cut out in a region which extends from a point lying some distance upstream of the rear side of the stacking station 3 to a point lying some distance downstream of this rear side. In the opening formed in this manner there is mounted between the side flanges of the section 5 a freely rotatable supporting roller 17 which has a larger diameter than the return roller 11 of the upper conveyor belt 8 and the axis of which is disposed a short distance upstream of the axis of said return roller 11, viewed in the direction of movement of the paper sheets, as can be seen from FIG. 1.

A guide plate 18 adjoins said support bar 5 on each side and drops laterally obliquely downwards from said bar 5. These two guide plates 18 serve to support the side portions of the sheets 2 being fed, so that these sheets assume a curved shape in the transverse direction and the paper stream formed by them is given the desired stiffness in the longitudinal direction. Thereby the individual sheets will have less tendency to be displaced in relation to one another and can more easily be pushed under the stack 7 being formed. These guide plates 18 also extend under the stack 7, so that the latter is also given a profile which is curved in the transverse direction.

These guide plates 18 have a portion 19 which extends in the direction of movement of the paper sheets to a point directly upstream of the stacking station 3 and has a greater lateral inclination than the portion 20 of the guide plates which lies below the stacking station 3. Between these plate portions 19 and 20 of the plates there is situated a transition portion 21 which extends obliquely upwards in the longitudinal direction of the plates and which merges with corresponding rounded transitions into the portions 19 and 20. Upstream of the plate portion 19, a plate portion 23 extends which has the same lateral inclination as the plate portion 20 and which merges into the plate portion 19 by way of a corresponding transition portion 22.

When the individual paper sheets 2 are fed in an uninterrupted paper stream, overlapping one another, as illustrated in FIG. 1, they have as a whole adequate stiffness to be able to withstand the pressure of the return roller 11 of the upper conveyor belt 8, so that the paper stream runs practically in a rectilinear path over the supporting roller 17 and under the return roller 11 to the stacking station and under the stack of sheets 7. The side portions of all the sheets of paper 2 of this continuous stream rest on the lateral guide plates 18, sagging further downwards in the region of the plate portions 19.

As soon as an interruption occurs in the paper stream, however, the front end of the first sheet following the interruption has reduced stiffness because of the lack of an overlap, so that this front edge 24 (FIGS. 1 and 2)together with the conveyor belt 1 is pressed downwards under the pressure of the return roller 11 on leaving the supporting roller 17 whereby between the latter and the end of the aperture 16 in the support bar 15 the conveyor belt 1 is guided in a downward curve 25 (FIG. 1) which penetrates under the rear edge of the paper stack 7. Consequently, the center of the front edge 24 of said sheet 2 is introduced under the rear edge of the lowermost sheet of the stack 7 and into the stacking station without striking against this rear edge of the lowermost sheet of the stack 7. On both sides of the bottom conveyor belt 1 the front edge 24 of this foremost sheet slides over the guide plate portions 19 and under the rear edge of the stack 7 resting on the guide plate portions 20, this front edge then moving along the transition portions 21 of the guide plates upwards past said rear edge of the stack, so that here again the front edge 24 cannot strike against the stack. In order to ensure that the side portions of the sheets lie close against the guide plate portions 19, pressure rollers 26 are preferably disposed on both sides of the upper conveyor belt 8, driven auxiliary belts 27 running over said pressure rollers (FIG. 2).

Through the abovedescribed apparatus according to the invention the effect is consequently achieved that the sheets being fed are always pushed under the sheets already stacked, even when in consequence of an interruption in the usually continuous paper stream these sheets do not overlap one another. With the apparatus according to the invention it is therefore also possible for sheets which for any special reason are introduced between the two conveyor belts 1 and 8 without overlapping, to be stacked in the manner described above without disturbance.

In my above mentioned co-pending patent application the frame carrying the upper conveyor belt is adjustable in the longitudinal direction in order to be able to adapt the position of the return roller 11, in relation to the stationary end stop 6, to the length of the paper sheets 2 in the direction of feed, in such a manner that said return roller always lies a short distance upstream of the stack 7 formed. In the apparatus described above this adjustment of the return roller 11 must naturally also be accompanied by adjustment of the supporting roller 17 and the guide plates 18 in the longitudinal direction. For this reason, these parts are also slidable in the longitudinal direction of the apparatus, in a manner not illustrated, in which they may be coupled to the movable upper frame of the apparatus.

While the invention has been shown and described with reference to a specific embodiment thereof, various modifications of this embodiment may be resorted to within the scope of the following claims.

Claims

What is claimed is:

1. An apparatus for feeding and stacking loose paper sheets comprising a stacking station having a forward and a rear side, a driven lower endless conveyor belt extending under said stacking station and returning at a point downstream of the latter, an upper endless conveyor belt, a return roller for said upper conveyor belt arranged a short distance upstream of said stacking station, means for mounting said return roller for vertical movement while urging said roller downwards whereby said lower and upper conveyor belts may clamp the sheets to be stacked between them in the central area thereof to feed said sheets to said stacking station, said stacking station having an upstanding end stop for said sheets disposed at the front or downstream side thereof, two lateral guide members one arranged on each side of said lower conveyor belt for supporting side portions of said sheets laterally of said sheet central area, said lateral guide members being inclined from said lower conveyor belt downwardly and laterally outwardly whereby said sheets assume a curved shape in the transverse direction, said lateral guide members having portions extending obliquely upwards in the feed direction of the sheets from a point lying upstream of the rear or upstream side of said stacking station to a point lying under said stacking station, and means for guiding said lower conveyor belt obliquely upwards from a point lying upstream of said rear side of said stacking station to a point under said stacking station whereby any sheet fed without being overlapped by the preceding sheet can be pushed without disturbance and without damage to its front edge under the stack formed at the stacking station.

2. The apparatus of claim 1 further comprising a support member for said lower conveyor belt having an aperture extending from a point some distance upstream of to a point some distance downstream of said rear side of said stacking station and underneath said return roller for said upper conveyor belt, and a supporting roller for said lower conveyor belt arranged in said aperture in a position in which its axis lies upstream of the axis of said upper conveyor belt return roller whereby downstream of said supporting roller the lower conveyor belt can be pressed downwards in a curve by said return roller.

3. The apparatus of claim 2 in which said support member for said lower conveyor belt comprises a channel section arranged with its lateral flanges directed downwards, said channel section having a web which is wider than the lower conveyor belt, said web being cut out to form said aperture and said supporting roller being arranged between the flanges of said channel section and projecting from below into this cutout.

4. The apparatus of claim 2 in which said lateral guide members comprise guide plates adjoining said support member for said lower conveyor belt and extending obliquely and laterally downwards therefrom, said guide plates each merging from a point situated a short distance upstream of said rear side of said stacking station, by way of a transition portion extending obliquely upwards in the feed direction of the sheets, from a determined lateral inclination upstream of said stacking station into a lesser lateral inclination under said stacking station.

5. The apparatus of claim 4 further comprising pressure roller means arranged on both sides of said upper conveyor belt a short distance upstream of said stacking station, said auxiliary roller means being adapted to press said side portions of said sheets against said guide plates.

6. The apparatus according to claim 2 in which said return roller for said upper conveyor belt and said supporting roller for said lower conveyor belt are together mounted for adjustment in the longitudinal direction of the apparatus whereby the latter can be adapted to the size of the sheets to be stacked.