GB2186553A - Sheet stacking apparatus - Google Patents

Abstract

The apparatus comprises a vertically movable table (B) and lateral plates, the plates comprising vibrating portions (42) alternating with non-vibratory portions (40). As described, each vibratory portion (42) is located opposite a non-vibratory portion (40). The portions, preferably equally spaced apart, may also be movable into a withdrawn position, fig. 5. <IMAGE>

Description

SPECIFICATION Sheet stacking apparatus The invention relates to a sheet stacking apparatus.

Sheet stacking apparatus is used, for example, in the paper industry, following the cross cutters. In many cases, e.g. when the sheets are to be used for multi-colour printing, it is important to ensure that they are stacked on one another in exact alignment.

This is normally achieved by means of the vibrator plates, which act on the longitudinal edges ofthe initially loose sheets which to some extent float on one anotheron an aircushion atthetop partofa stack. By their very nature, however, these vibrator plates do not occupy any defined position, so that there is a certain dangerthatthe sheets will be thrown to and fro by vibrations between the vibrator plates until finally, under the weight of the sheets above them and the resulting mutual friction, they somehow come to rest. Although the resultant deviations are generally very slight, it is nevertheless necessaryto remedy this situation.

An object of thins invention is therefore to enable a sheet stacking apparatusto be so constructed that those edges of the sheets which are subjected to the action ofthe opposed vibrator plates will in every case assume an accurately defined position.

According to the present invention in a sheet stacking apparatus the vibrator plates are divided into portions which succeed each other in the horizontal direction, portions arranged to perform vibratory movements alternating with non vibratory portions.

The non vibratory portions occurring between the successive effective portions of the vibrator plates present to the edges of the sheets a defined contact surface against which the said edges can come to rest.

An embodiment of sheet stacking apparatus, in accordance with the invention, will now be described by way of example only, with reference to the accompanying drawings in which:- Figure lisa schematic side view of a sheet stacking apparatus Figure2is a similarlyschematic pianviewofthe sheet stacking apparatus of Figure 1, FigureS is a section along the line llllll of Figure 2, showing an effective portion of a vibrator plate, Figure4is a section along the line IV-IVof Figure 2, showing one of the non vibratory plate portions, and Figure5is a section similarto that of Figure3 but showing the relevant portion of the vibrator plate in a raised "parking" position.

In Figures 1 and 2 a frame 2 of a stacking apparatus may be seen in which a lifting table 8, which can be automatically lowered as the size of the stack 6 increases, is suspended by chains 4. The lifting table 8 bears the stack 6 on a pallet 10. The chains 4 pass over pulleys 12,14, 6 and 18, of which the latter, in known manner, can be driven by a motor (not shown) in conjunction with an automatic stack height scanning system, in such a way that the upper part of the stack 6 always remains at approximately the same height.

Likewise in the conventional manner a plurality of adjacent endless sheet guide belts 20 extend over the stack 6 in the longitudinal direction, passing round two rollers 22 and 24, mounted in the frame 2 and situated in front of and behind the stack respectively, and are driven from the roller 22. Blocks 28, in which a roller30 is mounted, are displaceably mounted on longitudinally extending bars 26 on both sides of the frame 2. A plurality of adjacent endless sheet guide belts 32 pass over the roller30.

The upper runs ofthe sheet guide belts 32 are situated in the zone in front of (downstream of) the stack 6 and directly below the lower runs of the sheet guide belts 20, and the driving system for the belts is such that sheets 35 entering between the belts 20,32 are driven thereby in the direction shown by the arrow34 and fed to the top of the stackS.

The blocks 28 also carry a rear contact plate 36 immediately adjacent to the roller 30 and serving as a rear stop for the stack, while opposite this plate, on the other side of the stack a stop plate 38 for the sheets leading edges is secured in the horizontal direction in theframe 2. In place ofthe conventional continuous vibrator plates those ofthe present system are subdivided into individual portions forming tongues 40 fixed in the horizontal direction and alternating with horizontally movable tongues 42.Themutuallyadjacenttongues40and42,aswill be described in greater detail in due course, are suspended from a supporting beam 44 on which they can be raised and lowered.The apparatus usually has a number of such supporting beams, corresponding to the number of vibrator plates normally provided. They are laterally transportable along transverse rails46 and 48 oftheframe 2,for adjustment to different sheet widths, by means of a driving system 50 not shown in detail. The plates 36 and 38 and also the tongues 40 and 42 are so designed that they only enclose between them the upper part of the stack 6, where the sheets 35 have notyetfinallycometo rest.

As may be seen in greater detail from Figures 3 and 5,the supporting beams 44 are fitted with guide plates 52 facing downwards, one for each of the tongues 42. The guide plates 52 are fitted, at the rear as viewed in Figure 1, with a guide block 54 by the aid of which the relevant tongue, against which the guide plate 52 rests flat, is mounted so that it can be moved upwards and downwards. To be more exact, the guide block 54 is provided, on the side facing towards the tongue, with a number of offset blind borings 56, inwhich littie plungers 58 are slidably mounted. On the side facing awayfrom the tongue, these little plungers can be actuated by compressed airthrough a channel 60 in orderto press the tongue againsttheguideplate52,whilethetongueis otherwise freely movable up and down between the guide plate 52 and the guide block 54.

From each tongue 42 a lateral attachment 62 extends th rough a slit 64 ofthe relevant guide plate 52, both in order to limitthe movement ofthetongue in the downward direction and in orderto enablethe tongue to be raised into the position shown in Figure 5. Forthis latter purpose the attachment 62 is able to rest on a strut 66 which is parallel with the supporting beam 44 and which is movable up and down on two rails 68 and 70 (Figure 1 and 2) extending downwards from the said supporting beam. This movement is brought about by a chain drive 72, only shown schematically in Figure 1, in conjunction with a geared motor74,which is common to the struts 66 of all supporting beams 44.

The tongues 40 differ from the tongues 42 in that they are thicker than the latter by an amount approximately corresponding to the stroke of the vibratory movementwhich the tongues 42 normally perform in operation. The tongues 40 thus fill, as shown in Figure 4, the whole ofthe resulting gap if they are used between two mutually adjacent stacks 6. Although the tongues 40 may be suspended and mounted exactly like the tongues 42, they are secured on the relevantstrut66, in the example shown in Figure 4, by means of a vertical guide consisting of the parts 76 and 78. The downward movement of the tongues 40 is then limited by a stop 80, which also serves to enable the tongues 40 to be raised by means of the attachment 62.

Each of the tongues 40 and 42 is provided atthe top with a bent over portion 82 which, when in the raised position and as shown by a tongue 42 in Figure 5, byway of example, can enter a recess 84of the supporting beam 44. As may also be seen from Figure 1,an endless roller chain 86takes a longitudinal course in the supporing beam and is guided in such a mannerthatitstwo runs are situated one above the other. Over one part of its length the chain 86 is provided, at an equal pitch corresponding to that of the alternating tongues 40 and 42, with lateral extensions 88 forming securing lugsforthe portions 82 ofthetongues, in orderto enable these latter two be secured in their raised positions (e.g. in Figure 5).

Figure 3 and 4 showthe relevanttongues 40 and 42 assuming their operating position, in which (in this example) they enter the space between two adjacent stacks 6. The tongues and strut 66 then occupytheir lowest terminal positions. If the strut 66 is raised it takes the tongues along with it, via the attachments 62 and the stops 80 until the tongues reach their upper terminal positions, as in the example shown in Figure 5.If now by means of a timed motor90 (Figures and 2)the chain 86 is displaced bya predetermined number of pitch distances, so that one or more of the extensions 88 comes to rest underneath the selected number of portions 82, then those tongues will thereby be locked in their raised ("parking") positions, regardless ofthe position assumed bythestrut66thenceforward.

If the length of the stack is to be shorterthan that shown in Figure 1, forwhich purpose the blocks 28 are moved farthertowardsthe right on the bars 26, as shown in Figures 1 and 2, then the roller 30 moves with the sheet guide belts 32 and the rear contact plate 36 into the zone ofthetongues 40 and 42. The chain 86 now enables all the tongues 40 and 42 not at present required to be locked in their raised position, while the stack can, whatever its length, be subjected over practically its whole length to the action ofthe tongues.

As may bye further seen from Figures 3 and 5, the lower end of each guide plate 52, which extends down into the vicinity of the upper strand of the sheet guide belts 20, bears a pneumaticvibrator92to which compressed aircan be fed through a hose 94 and via a shut-offvalve (not shown). The material and the dimensions of the guide plates 52 are such that under the action of the vibrator orvibrators 92 they undergo a vibratory movemept perpendicular to the planes of the plates and transmitted to the tongues 42 in contact therewith. The side surfaces of the adjacent stack 6 are thus vibrated into proper alignment in a zone where the stack has not yet been consolidated.

The vibrators 92 of the tongues 42 at present not in operation (Figure 5) are normally switched off. One vibrator 92 can be provided forthe guide plates 52 of several different tongues 42. Forthis purpose the guide blocks 54 of the relevant tongues, as shown in Figures 2,3 and 5, are interconnected by a rail 96 attached to the bottom. The system can be so arranged (Figure 2) that opposite each tongue 42 belonging to a supporting beam 44 and subjected to vibrations there is a rigid tongue 40 of the adjacent supporting beam, and vice versa. Finally, where the tongues only act on one side on a stack, it may be possible to use only tongues of the vibratorytype illustrated and described here, i.e. 42, since the relevantvibrators 92, are individually disconnectable. In this case it will naturally be desirable in some manner or other, e.g. by means of a continuous strut similar to the strut 66, to ensure that the tongues shut off, if in the operating position, assume a defined lateral position corresponding to the terminal position occupied bythevibrating tongues 42 on the stack.

Claims (11)

1. Sheet stacking apparatus comprising a lifting table which can be automatically lowered in accordance with the height of the stack being formed and vibrator plates positioned at opposite sides of the upper part of the stack position which plates are subdivided into portions succeeding each other in the horizontal direction, portions arranged to perform vibratory movements alternating in non vibratory portions.

2. Sheet stacking apparatus in accordance with Claim 1, in which opposite each vibratory portion belonging to one plage there is a non vibratory portion ofthe other opposite side plate.

3. Sheet stacking apparatus in accordance with Ciaim 1 or Claim 2, in which the portions for performing vibratory movement can be put out of operation individually or in sets.

4. Sheet stacking apparatus in accordance with any of the preceding claims, in which the portions for performing vibratory movements can be actuated dynamically by a vibrator.

5. Sheet stacking apparatus in accordance with any of the preceding claims, in which at leastthe portions for performing vibratory movements consist of elastic and/or elastically suspended tongues.

6. Sheet stacking apparatus in accordance with Claim 4togetherwith Claim 5 inwhich theoreach vibrator is mounted on an elastic or elastically suspended guide plate and supportorsupportsthe vibratory tongues.

7. Sheet stacking apparatus in accordance with any ofthe preceding claims in which the vibratory portions are thinner than the non vibratory portions.

8. Sheet stacking apparatus in accordance with any of the preceding claims, in which the vibratory portions and/orthe non vibratory portions of each plate are positioned at the same distances apart.

9. Sheet stacking apparatus in accordance with any of the preceding claims in which at least those portions of each plate of the stackwhich perform vibratory movements are suspended from a respective common supporting beam.

10. Sheet stacking apparatus in accordancewith any ofthe preceding claims, in which the portions can be moved individually or in sets into a "parked position" in which they are disengaged from a stack.

11. Sheet stacking apparatus substantially as described herein with reference to oras illustrated in the accompanying drawings.