Sheet stacking equipment with suction-driven conveying belts

Abstract

Stacking equipment for sheets comprises suction-driven conveying belts and a stack support configured to receive sheets in a vertical stack. The conveying belts include lower branches positioned above the stack support and motor-driven to advance incoming sheets along a transport surface by suction applied through the lower branches. A stopping member, mounted on a functional block, arrests the advancing sheets, which are then deposited onto the stack support. The functional block is longitudinally adjustable according to the sheet length and carries intermediate and deviation rollers for the lower branches of the belts, thereby defining an accommodation space for the stop member above the transport surface. The stopping member includes a cross-section with a continuous profile that projects below the transport surface to reliably stop the conveyed sheets. The stacking equipment further includes a sensing device for detecting stack height and a compensation mechanism to adjust the stack support height accordingly.

Description

[0001] This application claims priority to Italian Application No. 102025000006117 filed on Mar. 25, 2025, the entire content of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present invention relates generally to sheet processing systems and, more particularly, to a sheet stacking equipment employing suction-driven conveying belts for high-speed sheet handling and alignment.

[0003] In particular, the invention relates to a sheet stacking equipment comprising suction conveyor belts, a stack support for vertically stacked sheets, input rollers for the sheets to be stacked, an electronic control unit, a stopping member for the incoming sheets, and a functional support block for the stopping member. The conveyor belts have lower branches arranged above the stack support and are motor driven for dragging incoming sheets along a transport surface by suction. The support block is longitudinally movable to position the stopping member at a distance from the input rollers based on the length of the sheets, such that stopped sheets are deposited onto the stack support or onto already stacked sheets.BACKGROUND

[0004] A stacking equipment of this type is disclosed in European Patent EP 4 363 234 of the Applicant TECNAU S.r.l., of which the present invention represents a substantial improvement.

[0005] In the TECNAU patent, the stopping member for incoming sheets is mounted on a support block and comprises a transverse plate with a plurality of stop fins on its lower portion. These fins project between the lower branches of the belts, forming a vertical alignment surface of the stack and being longitudinally movable depending on the length of the sheets to be stacked. The equipment also includes a compensation mechanism for adjusting the height of the stack support based on the stacked sheets and a pressure crossbar acting on the forming stack to stabilize it and detect stack height for the compensation mechanism.

[0006] Sheet stacking equipment with the above structure is fast, reliable and capable of handling large sheets with varying rigidity and sliding characteristics, particularly medium to heavy weight sheets. However, for very light sheets, discontinuities in the stop fins can cause damage to the leading edges of the sheets, aesthetic defects, misalignment, or jamming. Additional problems may arise from the action of the pressure crossbar, adjustment of the compensation mechanism, or its operation with particular types of sheets.SUMMARY

[0007] An object of the present invention is to provide stacking equipment with suction conveying belts that can reliably handle sheets at high speed, including sheets with widely varying characteristics and medium-to-light weight sheets.

[0008] According to this object, the sheet stacking equipment further comprises deviation means associated with the lower branches and supported by the functional support block, the deviation means being configured to form an accommodating space above the transport surface, upstream of and adjacent to the stopping member. The stopping member is arranged within the accommodating space and has a cross-section projecting below the transport surface to stop the sheets and define a vertical alignment surface of a stack. The cross-section of the stopping member has a continuous profile configured to act as a stop for the leading edge of the stacking sheets.

[0009] By providing a continuous stop surface instead of discrete fins, the equipment prevents damage to the leading edges of lightweight sheets and ensures precise vertical alignment.

[0010] According to another feature, the sheet stacking equipment further comprises a sensor device and a compensation mechanism for adjusting the height of the stack support. The sensor device includes a plurality of sensing rollers interposed between the lower branches of the transport belts and configured for individual movement; a plurality of sensing supports rotatably supporting the sensing; a common shaft with a plurality of contrast elements arranged above the sensing rollers; and spring means for applying a tensioning action from the contrast rollers onto the sensing supports via the common shaft.

[0011] The sensor device provides information to the electronic control unit for the compensation mechanism in response to rotation of the common shaft, determined by the maximum lifting height of the sensing rollers.DESCRIPTION OF THE DRAWINGS

[0012] The features of the invention will become clear from the following description, given by way of non-limiting example with the aid of the attached drawings, in which:

[0013] FIG. 1 represents a schematic perspective view, conventionally front, of sheet stacking equipment according to the invention;

[0014] FIG. 2 is a partial side section of the equipment of FIG. 1;

[0015] FIG. 2a shows some details, on an enlarged scale, of components of FIG. 2;

[0016] FIG. 3 represents a schematic top perspective view of some functional units of the equipment of FIG. 1;

[0017] FIG. 4 is a schematic bottom perspective view of the functional units of FIG. 3;

[0018] FIGS. 5a and 5b show some parts of FIG. 2, on an enlarged scale;

[0019] FIG. 6 is a schematic exploded view of some components of FIG. 3;

[0020] FIGS. 6a, 6b and 6c show some details of the components of FIG. 6;

[0021] FIGS. 7 and 7a are further schematic views of some components of FIG. 3;

[0022] FIG. 7b is a schematic bottom view of some components of FIG. 4;

[0023] FIGS. 8, 8a, 8b and 8c show some components of the equipment of FIG. 2, on an enlarged scale;

[0024] FIG. 9 represents parts of FIG. 8 during a calibration phase;

[0025] FIG. 10 represents a schematic top perspective view of further functional units of the equipment of FIG. 1 in a given operating condition;

[0026] FIG. 11 shows the units of FIG. 10 in another operating condition; and

[0027] FIG. 12 shows components of FIG. 2 in another operating condition.GENERAL DESCRIPTION

[0028] With reference to FIGS. 1 and 2, a sheet stacking equipment, indicated as 31, receives paper sheets 32 at the front from external apparatus along a direction “F”. The stacked sheets are sent, as a stack or pack 33, through an output gate “OG” at the rear to an external processing apparatus by means of a conveyor belt “CB”.

[0029] The stacking equipment 31 is of the type indicated as 21 in the aforementioned patent EP 4 363 234, hereinafter “Patent”, which is incorporated herein by reference.

[0030] In summary, the stacking equipment 31 includes, at the front, an alignment section 34, at the rear a stacking and delivery section 36, and comprises an electronic control unit 37, a push-button panel 38, a control panel “CP”, a compressed-air generator 39 and sensor elements (not shown) arranged along the sheet path.

[0031] The alignment section 34, similar to the section 31 of the Patent, aligns the sheets 32 on a respective receiving surface and forwards them toward the stacking and delivery section 36.

[0032] The stacking and delivery section 36 consists of a transport and deposition unit 41, similar to unit 41 of the Patent, adjacent to the alignment section 34, and an accumulation and delivery unit 42, similar to unit 42 of the Patent, arranged below the unit 41.

[0033] As regards the present invention, the alignment section 34 comprises a series of alignment rollers 43 that align the edges of the sheets 32, even when side-by-side. The incoming sheets are then forwarded along the direction “F”, with suitable spacing between sheets, on a receiving surface, horizontal in use, toward the stacking and delivery section 36.

[0034] The transport and deposition unit 41 comprises input rollers 51 and conveying belts 52 for receiving and positioning incoming sheets above the stack 33 along a transport surface “TS”. The accumulation and delivery unit 42 in turn comprises a stack support 53 and a compensation mechanism 54, similar to stack support 46 and compensation mechanism 47 of the Patent.

[0035] The stack support 53 as the stack support of the Patent receives the sheets being stacked and forwards the stack 33 toward the conveyor belt “CB”, while the compensation mechanism 54 vertically moves the support 53 depending on the stacked sheets. The accumulation and delivery unit 42 may also forward the received sheets 32, without stacking, through a rear service opening “DTG”, substantially aligned with the transport surface “TS”.

[0036] In the transport and deposition unit 41, the input rollers 51 (FIGS. 2, 5a and 5b) include a driving roller 56 and a pressure roller 57 engaging each other on an introduction surface coplanar with the receiving surface of the alignment section 34.

[0037] The driving roller 56 and the pressure roller 57 are rotatably mounted on a frame 58 of the unit 41 and are driven through belts and pulleys by a feed motor 59 controlled by the electronic unit 37 to advance the sheets 32 in the direction “F”.

[0038] The conveying belts 52 extend horizontally and have respective upper branches 61 and lower branches generally indicated as 62. The lower branches are positioned above the stack support 53 and define, with their outer surface, the transport surface “TS” for the incoming sheets 32, horizontal in use and located below the introduction surface between the rollers 56 and 57.

[0039] The conveying belts 52 are longitudinally holed and coupled with one or more transverse ducts 69 arranged above the lower branches 62. Each duct 69 is connected at its upper portion to a series of suction fans 71. On their lower surfaces the ducts 69 have belt-guiding slots with suction openings adapted to exert a suction action on the sheets 32.

[0040] The conveying belts 52 are tensioned, through suitable guides, by the driving roller 56, by front rollers 72 and 73 respectively upper and lower, and by rear rollers 74 and 76 respectively upper and lower, rotatably mounted on the frame 58. The front rollers 72 and 73 deviate upward and downward the belts 52 engaged by roller 56, while rollers 74 together with rollers 72 define the upper branches 61 horizontally.

[0041] In particular, the belt stretches between the input rollers 51 and the front rollers 72 are inclined downward and guide the sheets 32 emerging from rollers 51 toward the transport surface “TS”. The rear rollers 76 together with the front rollers 73 define the lower branches 62 forming the conveying surface “TS”. Return rollers 77 are also provided for tensioning the belts 52, rotatable on the frame 58 in an intermediate position between the rollers 74 and 76.

[0042] The upper branches 61 and lower branches 62 of the belts 52 are vertically spaced sufficiently to accommodate the ducts 69 with fans 71 and other components of the transport and deposition unit 41.

[0043] Conveniently, downstream of the input rollers 51 spring leaves 78 and a compressed-air nozzle 79 connected, via a corresponding solenoid valve, to the compressed-air generator 39 are provided. The spring leaves 78 and the nozzle 79, when activated with air jets, act on the downward inclined stretches of belts 52 to facilitate detachment of incoming sheets from the belts together with their release from the input rollers 51.

[0044] In a known manner, the guides for conveying the belts 52 are formed on the lateral surface of hollow cylinders corresponding to the numbering indicated. The hollow cylinders are rotatable through bearings on corresponding shafts mounted on the frame 58. These guides have a slightly convex (crowned) profile producing a self-centering effect on the moving belts 52.

[0045] By action of the feed motor 59 and through the driving roller 56, the conveying belts 52 drag the incoming sheets 32 by adhesion due to suction along the lower branches 62 and deposit them onto the stack support 53 or onto the last sheet of the forming stack 33.Functional Block and Stopping Member

[0046] The stacking equipment 31 comprises, in the transport and deposition unit 41, a functional block 81 similar to the functional block 50 of the Patent, on which a corresponding stopping member 82 for the incoming sheets 32 is mounted.

[0047] The functional block 81 also supports a sensing device 83 for the last deposited sheet of the stack, including a series of sensing rollers 84 and an electronic sensor 85.

[0048] The block 81 (FIGS. 2, 3, 5b and 7) comprises a transverse flat bar 86, two side members 87r and 87l at the sides of the bar 86, and a transverse profile 88.

[0049] The bar 86 supports the stopping member 82, while the profile 88 supports the sensing rollers 84 and is mounted in front of the bar 86.

[0050] The side members 87r and 87l are slidably coupled and lockable with two lateral guides 89r and 89l, allowing the stopping member 82 to be positioned at a distance from the input rollers 51 that exceeds the length of the sheets 32.

[0051] One or more ducts (69), the number of which depends on the length of the sheets to be stacked, are mounted on sides that slide along the lateral guides (89r, 89l) and are selectively positionable at varying distances from the input rollers (51) based on said sheet length.

[0052] The positioning of the block 81, and the ducts 69 may be performed manually or by means of motors, optionally controlled based on the sensed length of the sheets.

[0053] To avoid the problems of known stacking equipment, the equipment 31 adopts innovative and effective solutions for the stopping member 82 and for control of the compensation mechanism 54.

[0054] Conveniently, the stacking equipment 31 provides a continuous stop profile for the stopping member 82 and deviation means 90 for the lower branches of the belts carried by the functional block 81 so as to form, above the conveying surface “TS”, an accommodating space for the stopping member 82.

[0055] Specifically, the deviation means 90 comprise intermediate rollers 91 (FIGS. 2, 5b, 8), deviation rollers 92 and realignment rollers 93 guiding the lower branches 62 of the belts 52. The rollers 91, 92 and 93 are rotatably mounted between the side members 87r and 87l of the functional block 81 and form a loop in the belts 52 creating an accommodating space 94 for the stopping member 82.

[0056] The front lower rollers 73 (fixed) and the intermediate rollers 91 (movable) guide an active section 95 of the lower branches 62 along the conveying surface “TS” for sheet dragging. The deviation rollers 92 are arranged above the intermediate rollers 91 and guide, together with the rollers 91, an upward deviated section 96 of the lower branches forming downstream and near rollers 91 the accommodating space 94 above the stack support 53.

[0057] The realignment rollers 93 are arranged at the same height as the intermediate rollers 91 and guide, together with the deviation rollers 92, a downward deviated section 97 of the lower branches. Finally, the realignment rollers 93 together with the rear rollers 76 guide a terminal section 98 of the lower branches 62 along the conveying surface “TS”. In detail, the deviation rollers 92 are positioned in a median area between the intermediate rollers 91 and the realignment rollers 93, determining a substantially inverted-U section of the loop delimiting the accommodating space 94.

[0058] The stopping member 82 comprises a plate 99 with a transverse section 101 arranged adjacent and downstream of the intermediate guide rollers 91, inside the accommodating space 94, upstream of the bar 86 and projecting downward from the conveying surface “TS”. The section 101 is intended to stop the moving sheets 32 and define a vertical alignment surface “AS” for the forming stack 33.

[0059] During the stacking process, the sheets 32 advance by the combined action of the input rollers 51 and the conveying belts 52. However, the sheets leave the rollers 51 before their leading edges contact the transverse section 101, and movement up to the stop is ensured solely by the conveying belts 52 through adhesion.

[0060] Advantageously, the transverse section 101 has a continuous profile acting as an abutment for the leading edge of the sheets 32 being stacked.

[0061] The continuous stop profile solution avoids the problems associated with the comb-type stop structure of the Patent. In particular frontal damage, especially at high operating speeds, and the impossibility of handling light or very light paper (<60 gsm) due to stacking jams even at low speeds.

[0062] The intermediate guide rollers 91 (FIGS. 7, 7a, 7b, 8, and 8a) consist of pulleys 102, which support the belts 52 and project from a shaft 103 rotatable between the side members 87r and 87l of the functional block 81. In turn, the transverse profile 88 has a substantially “L”-shaped section and features a lower surface with a rounded front edge, which serves as a sliding surface for the lower branches of the belts, and longitudinal extensions 104, comb-shaped, at the sides of the pulleys 102.

[0063] The longitudinal extensions 104 function as guides for the leading edges of incoming sheets and, when abutting, up to the cross-section 101 of the stopping member 82. Conveniently, the longitudinal extensions 104 are inclined downward to gradually bring the leading edges of the sheets being stacked closer to the stack 33 near the stop.

[0064] Analogous to the equipment 21 of the Patent, the sheet-stacking equipment 31 also allows the formation of bundles with both regular blocks and staggered blocks.

[0065] To this end, the equipment 31 includes an offset stop 111, mounted in the accommodating space 94, and an offset actuator 112, for example of the electro-pneumatic type. The offset stop 111 has a cross-section 113, also with a substantially continuous profile, positioned behind the cross-section 101 of the stopping member 82 along direction “F”. The stopping member 82, with its cross-section 101, can be lifted by the offset actuator 112 to stop the sheets being stacked against the cross-section 113 of the offset stop 111 for a staggered stack surface relative to the alignment surface “AP”.

[0066] In detail, the plate 99 of the stopping member 82 is slidably mounted via guides 114 (FIGS. 6, 7, and 8), vertical in use, fixed to a front surface of the transverse bar 86. The offset stop 111 includes a crossbeam positioned behind the bar 86 and can be lifted by a lever 116 when the equipment 31 is set to transfer sheets 32 without stacking.

[0067] Conveniently, the cross-section 101 of the stopping member 82 has an inclined lower surface. This surface can be aligned with the lower surfaces of the longitudinal extensions 104 when the stopping member 82 is lifted by the offset actuator 112, enabling smooth stacking even for the formation of staggered blocks.

[0068] In the stacking equipment 31, the sensor device 83 (FIGS. 2, 5b, and 8c) is linked to the compensation mechanism 54 to ensure optimal conditions for stacking sheets regardless of the number of sheets already stacked. Specifically, the distance between the transport surface “TS” and the last sheet of the forming stack 33 is maintained constant in an optimized manner.Stack Height Compensation

[0069] According to another feature of the invention, in the sensor device 83, the sensing rollers 84 (FIGS. 5b, 6, 6b, 8, 8a) are arranged transversely between the lower branches 62 of the belts and are rotatably mounted on inverted U-shaped bridge supports 121. The bridge supports 121 are pivoted on pins 122 mounted via sensing blocks 123 on the transverse profile 88 and feature an upper part 124 above the rollers 84.

[0070] The sensing rollers 84 protrude with their lower sectors through corresponding windows 126 from the lower surface of the profile 88 (FIGS. 6b, 7b, and 8a) and face corresponding sheet sensing areas in the stack. A series of sensing springs, constituted by torsion springs 127 mounted on the pins 122 act on the bridge supports 121 to apply individual sensing pressure of the rollers 84 on the stack, and at rest, against end-of-travel stops 128.

[0071] A series of counter rollers 129, rotatable on intermediate supports 131, are arranged above the sensing rollers 84. The supports 131 are fixed but adjustable in angle via grub screws 132 on a common shaft 133. The shaft 133 is rotatably mounted on the profile 88 via supports 134 and serves as a mounting for two torsion springs 136 that push the counter rollers 129 against the upper part 124 of the bridge supports 121.

[0072] The transverse profile 88, together with the sensing rollers 84, the counter rollers 129, the common shaft 133, and associated parts, constitutes a sensing assembly that can be easily removed from the functional block 81 for maintenance via right and left knobs 137r and 137l securing the ends of the profile 88 to the side members 87r and 87l of the functional block 81.

[0073] On a setup phase of the stacking equipment 31, by means of a specific tool, the end-of-travel stops 1281 are adjusted so that the sensing rollers 84 are all aligned. Furthermore, the angular positions of the intermediate supports 131 is adjusted so that the counter rollers 129 are in contact with the upper parts 124 of the bridge supports 121.

[0074] During stacking, the sensing rollers 84 can be displaced upward by the sheet being stacked depending on its thickness (0.07–0.5 mm) in the sensing area. This displacement is transmitted to the counter-rollers 129 via the upper part 124 of the bridge supports 121, triggering the rotation of the common shaft 133 through the intermediate supports 131 and the upward lifting of the vane 141. Should a sheet 32 have a greater thickness in a specific sensing area, the rotation of the common shaft 133 is driven by the maximum lifting of the sensing rollers 84 operating on that thicker area.

[0075] The sensing action of the sensing rollers 84 on the sheets being stacked is performed by the combined force of the torsion springs 127 on the sensing rollers 84 and the torsion spring 136 on the common shaft 133, acting via the counter-rollers 129. The torsion springs 127 serve two functions: first, they maintain stable contact between the sensing rollers 84 and the sheets 32 in the thinner areas; second, they hold the rollers 84 against their respective end-of-travel stops 128 in the absence of sheets or their spacing.

[0076] In practice, the sheets 32 may exhibit imperfections (swelling, creases, ink variations, etc.) which the sensing rollers 84 detect by lifting. The sensing roller 84 that encounters the maximum imperfection lifts higher than the other and, via upper part 124 of the bridge supports 121, further rises the overlying counter-roller 129. This causes a further rotation of the shaft 133 and the lifting of the vane 141. Meanwhile, the other counter-rollers detach from the bridge parts 124 that remain lower, while the respective sensing rollers 84 are kept in contact with the sheets by the action of the springs 127.

[0077] In the sensor device 83, the electronic sensor 85 (FIG. 8c) is a laser illuminator / detector similar to that of the Patent. In the stacking equipment 31, the target area of the sensor device includes a vane 141 fixed on the shaft 133, which oscillates horizontally in response to movements of the sensing rollers 84 caused by incoming sheets and the corresponding movements of the counter rollers 129.

[0078] Advantageously, the accumulation and delivery assembly 42, in addition to the stack support 53 (FIGS. 2, 10, 11, and 12), includes a starting support 151 to ensure optimal stacking of the first sheets of the stack 33 and to accelerate transitions between the delivery of the completed pack and subsequent stacking.

[0079] The stack support 53 comprises, in summary, a frame 152 beneath the transport and deposit assembly 41, two transverse shafts 153 and 154, respectively front and rear, rotatably supported by the frame 152, a plurality of functional and delivery blocks 156 carried by the frame 152, and a delivery motor 157 for the shafts 153 and 154.

[0080] The functional and delivery blocks 156 (FIG. 2a) have an elongated parallelepiped shape, spaced transversely from one another, and each comprises a spar 158, two terminal pulleys 159 and 160 keyed on the shafts 153 and 154, intermediate idler rollers 161, and an elongated delivery belt 162 stretched between the pulleys 159 and 160. The pulleys 159 and 160 of each block 156 have upper sectors tangent to the upper surfaces of the spar 158. The upper run of the belt 162 rests on the upper surface of the spar 158, while the lower run is deflected upward by the idler rollers 161.

[0081] The assembly of the upper runs of the delivery belts 162 forms a supporting surface “BS” for the forming stack 33, with support by the spars 158. The belts 162 are driven by the motor 157 in direction “F”, sliding over the upper surfaces of the spars 158 during delivery by the stacking equipment 31.

[0082] The stack support 53 can move vertically via a pair of vertical guides 163l and 163r between a reference position “RP” and a delivery position “DP” (FIG. 9). The reference position “RP”, high, corresponds to an operational condition following an initial phase of no sheets. The delivery position “DP” is the lowest position of the stack support 53, where the surface “BS” is substantially coplanar with the lower edge of the output gate “OG” and with the conveyor belt “CB”.

[0083] A panel 164 is mounted vertically downward on a rear part of the frame 152. The output gate “OG” is shielded by the panel 164 when the stack support 53 is in the reference position “RP” and is clear when the support 53 is in the delivery position “DP”.

[0084] For the condition of sheet transfer without stacking, the stack support 53 can also be moved to a high extra-stroke position where the supporting surface “BS” is tangent to the lower branches 62 of the conveyor belts, coplanar with the “TS” surface in correspondence of the rear service opening “DTG”.

[0085] As previously reported, depending on the number of sheets stacked, the compensation mechanism 54 lowers the stack support 53 from the reached position to the delivery position “DP” upon completion of the stack 33. In this position “DP”, the upper runs of the delivery belts 162 are moved by the delivery motor 157 to forward the stack 33, through the output gate “OG”, onto the conveyor belt “CB” for subsequent processing.

[0086] The compensation mechanism 54 comprises a pair of ball-screw assemblies with splined shafts 166 and 167 and corresponding nuts 168 and 169. The nuts 168 and 169 are fixed to the sides of the frame 152, while the splined shafts 166 and 167 are rotatably supported, with a lower end, on a transverse plate 171 and are driven in rotation, via belts and pulleys, by a compensation motor 172, which is also controlled by the electronic unit 37.

[0087] The starting support 151 includes a frame 179 positioned beneath the alignment section 34, a multi-fork support 181 mounted for sliding on the frame 179, a series of forks 182 mounted on the multi-fork support, an actuation mechanism 183 for the multi-fork support, and a starting compensation mechanism 184 for the frame 179.

[0088] The forks 182 can be inserted between the functional and delivery blocks 156 and are actuated by the fork actuation mechanism 183, activated by the electronic unit 37, to move the forks 182 from a retracted configuration to an inserted configuration. In the retracted configuration, the forks are closed on the frame 179 below the alignment section 34. In the inserted configuration, the forks protrude from the frame 179 and can be inserted between the functional and delivery blocks 156 of the stack support 53.

[0089] In summary, the fork actuation mechanism 183 comprises two pulleys 187 and 188 rotatably supported, centrally, at the front and rear of the frame 179, a displacement belt 189 stretched between pulleys 187 and 188, and a fork actuation motor 191. The multi-fork support 181 is engaged with the upper run of the displacement belt 189 for moving the forks 182 between the retracted and inserted configurations.

[0090] The starting compensation mechanism 184 is provided to adjust the height of the frame 179 with the multi-fork support according to the height of the sheets being stacked. This mechanism 184, similar to the compensation mechanism 54 and comprising a starting compensation motor 192 and a screw-and-nut conversion mechanism, is not described here for the sake of brevity.

[0091] During a startup phase, the stack support 53 is in the reference position “RP” and the forks 182 are in the inserted configuration, above the upper runs of the delivery belts 162. The forks 182 thus form a temporary support replacing the belts 162, with a surface optimized for stacking the first sheets of the stack.

[0092] For a predetermined stack height, e.g., 10 sheets, the forks 182 are slightly lower than the supporting surface “BS” and the forming stack 33 rests on the delivery belts 162. The electronic unit 37 can activate the actuation mechanism 183 to move the forks 182 to the retracted configuration and can activate the starting compensation mechanism 184 to adjust the height of the stack support 53 during operation based on the number of sheets stacked beyond the predetermined height.

[0093] According to a feature of the invention, the stacking equipment 31 provides for the stacking of the sheets a fixed reference represented by a “machine zero” level and software-based control for the height compensation of the stack support 53 or the starting support 151. The “machine zero” level corresponds to the one of a transport surface “TS” of the sheets 32 in the area of tangency with the conveyor belts 52 guided by the intermediate rollers 91. The software control, in turn, allows adjustment of the height compensation of the stack support 53 or the starting support 151 based on operational experience of the equipment 31.

[0094] Upon request, the sensor device 83 can be calibrated using a calibration tool (master) 196 (FIG. 9) to correctly set the initial reading value for the “machine zero” level.

[0095] The calibration tool 196 comprises an L-shaped profile in which a vertical part 197 is comb-like and a base part 198 is flat. The vertical part 197 can be inserted between the conveyor belts 52 and coupled with the front part of the profile 88, while the base part 198 lifts the sensing rollers 84 to the “machine zero” level, allowing the operator to correctly set the sensor zero. Once the calibration tool 196 is removed, the sensing rollers 84 return to their initial position against the end-of-travel stops 128, performing a displacement “X” that will correspond to the initial reading value of the sensor device 83.

[0096] The electronic sensor 85, reading the target area constituted by the vane141, will therefore measure a deviation value “X” relative to another previously measured value. The measured values are then used to correct, via software, the descent of the support on which the stack is being formed, thus closing the process control loop.

[0097] More specifically, by means of a parameter that can be set from the panel “CP”, depending on the paper thickness, the operator sets the “theoretical pitch” for the descent of the stack support 53 and starting support 151, for example, 0.15 mm. The operator also sets the “theoretical reference position” for the sensor reading: “zero”, “negative”, or “positive” values. For instance, if the set value is “zero”, the support will descend so that the sensor 85 consistently measures values near zero, thus keeping the stack composition close to “machine zero” for an average compression of the stack 33 being formed.

[0098] If the set value is greater than zero, the support will descend while attempting to maintain the sensor measurement at this value, resulting in a more compressed stack (position of the the sensing rollers 84 higher than “machine zero”). If the set value is less than zero, the support will descend while attempting to maintain the sensor measurement at this value, resulting a less compressed stack (position of the sensing rollers 84 lower than “machine zero”).

[0099] During stacking, the software also perform a sampling every “n” values measured by the sensor 85 and calculates an average. The average value is then used to correct the “theoretical pitch” set by the operator. The resulting “average corrected pitch” will allow for an optimal descent of the stack support or starting support to keep the sensor reading close to the set value. Consequently, this descent will be the one expected for the last incoming sheet on the stack being formed.

[0100] The “average corrected pitch” is also displayed on the panel for the operator, who can thus have visual feedback of the actual pitch currently being applied by the equipment 31.

[0101] To accommodate the multiple types of paper and formats processable, the values set by the operator can be saved in reusable recipes to ensure repeatability of the operations.

[0102] The operation of the equipment 31 for sheet stacking is as follows:

[0103] Depending on the longitudinal dimensions of the sheets 32 to be stacked (FIGS. 1 and 2), the operator positions the functional block 81 and the duct or ducts 69 at programmed distances from the input rollers 51. Through the control panel “CP”, the operator also sets data on the number of sheets 32 to stack, the number of sheets per block for offset stacking (if required), the characteristics of the sheets, the “theoretical pitch” and the “average corrected pitch”. The operator can also set the number of sheets to stack on the forks 182 during the start phase and thus the reference position “RP”.

[0104] In an initial phase, the stack support 53 (FIG. 3) is empty and in the reference position “RP”, and the output gate “OG” is blocked by the panel 164. The starting support 151 is in a high position, at the “machine zero” condition, with the forks 182 in the inserted configuration, interposed between the blocks 156 of the stack support 53, to receive the incoming sheets in stacking.

[0105] The electronic unit 37 activates the feed motor 59, rotating the input rollers 51 with movement of the belts 52 at a conveying speed slightly higher than the sheet feed speed.

[0106] At the exit from the alignment section 34, the input rollers 51 advance the sheet 32 positively along the inclined belt sections. The sheet is bent and guided downward until its leading edge meets the forks 182 of the starting support 151. The sheet is then bent again and guided horizontally by the action of the input rollers 51 and with the contribution of the lower branches 62 of the belts 52.

[0107] The first sheet 32 continues its travel until its leading edge passes the position of the duct or first duct 69. Here, the sheet is lifted against the branches 62 of the belts 52 by suction from the duct 69 through the openings in the guide notches and through the holes in the belts 52. The sheet continues to advance through the passage and suction of successive parts in front of the openings and the combined positive drag action of the input rollers 51.

[0108] If the equipment 31 includes multiple ducts 69, after the first duct lifts the sheet 32, adhesion to the belts 52 is perfected as the sheet passes in front of the other ducts.

[0109] After the trailing edge leaves the rollers 51, the sheet 32 continues to be dragged solely by the belts 52, with adhesion ensured by the duct or ducts 69, and tends to return to a flat configuration, facilitated by the elastic separating tabs 69 and compressed air jets from the nozzle 79.

[0110] As it moves along the belts 52, the first sheet 32 encounters its leading edge with the sensing rollers 84, which are raised depending on the sheet thickness, lifting the vane 141. The sheet is finally stopped when it meets the cross-section 101 of the stopping member 82, with slippage of the belts 52 on the sheet. While waiting for another sheet 32 to be stacked, the feed motor 59 remains activated, keeping the input rollers 51 and the belts 52 in motion.

[0111] The introduction of the first sheet 32 into the transport and deposit group 41 triggers, by command of the electronic unit 37, the start compensation motor 192 to lower the starting support 151 by an amount corresponding to the “theoretical pitch” and the “theoretical position”, in response to feedback from the laser illuminator / detector 85 on the position of the target area 141.

[0112] A new sheet 32 entering from the input rollers 51 is also bent and guided downward by the input rollers 51 and the inclined belt sections, but its leading edge now meets the previous sheet. Due to the pushing action from the input rollers 51, the inclined belt sections, and the insertion roller 73, the new sheet is bent and guided horizontally, inserting itself between the lower branches 62 of the belts and the portions of the previous sheet still adhering to the branches 62.

[0113] The new sheet 32 continues its travel above the previous sheet until its leading edge reaches the duct or the first duct 69, coming into contact with its lower surface. The portion of the previous sheet, no longer held by the suction of the duct falls onto the surface of the forks 182, while the new sheet adheres to the branches 62 of the belts and is dragged by them. The new sheet then continues to advance due to the passage and suction of successive parts in front of other ducts 69, while the previous sheet progressively settles onto the forks 182 as the first sheet of the stack 33.

[0114] The new sheet 32 continues its movement solely by means of the conveyor belts 52 due to adhesion ensured by the duct or ducts 69 after its trailing edge leaves the rollers 51. The new sheet tends to return to a flat configuration and rests its trailing edge on the previous sheet, facilitated by the spring leaves 78 and compressed air jets. In sequence, the new sheet lifts the sensing rollers 84 depending on its thickness, with the consequent lifting of the vane 141. The sheet is finally stopped when its leading edge contacts the cross-section 101 of the stopping member 82, with the moving belts 52 slipping on the sheet.

[0115] The completion of the introduction of the new sheet 32 into the transport and deposition unit 41 triggers again the compensation motor 192, under the control of the electronic unit 37 and feedback from the sensor device 83, lowering the starting support 151 by an amount corresponding to the set data..

[0116] Stacking of subsequent sheets occurs sequentially as previously described for the second sheet, with the progressive formation of the stack 33 and any corrections to the lowering of the starting support 151 based on the “average corrected pitch”.

[0117] Upon reaching the number of sheets planned for the stack height at start-up, the forks 182 are positioned to a level slightly lower than the surface “BS”, and the forming stack 33 rests on the delivery belts 162. The electronic unit 37 then activates the fork actuation motor 191 to move the forks into their retracted configuration, thereby leaving the stack support 53 free to receive further sheets being stacked.

[0118] The forming stack 33 now rests on the supporting surface “BS” constituted by the delivery belts 162, and the stacking process of sheets 32 continues as previously described for the support on the forks 182, but with the height compensation of the stack support 53 entrusted to the compensation mechanism 54. Specifically, for the new incoming sheets 32, the electronic unit 37 activates the compensation motor 172, lowering the stack support 53 according to the set data and corrections based on the “average corrected pitch”.

[0119] In the event that the offset option is provided, after the set number of sheets forming each block has been stacked, the electronic unit 37 activates the offset actuator 112, lifting the stopping member 82. The offset stop 111 replaces the transverse section 101, thereby determining the alignment plane for the staggered blocks.

[0120] During the stacking process, the continuous profiles of the transverse sections 101 or 113 of the stopping members 82 prevent the impact of incoming sheets 32 and the thrusts of the conveyor belt 52 from causing deformations of the leading edges or sheet curling, which could lead to overlapping and jamming upon the arrival of subsequent sheets.

[0121] In turn, the accurate detection of the thickness and imperfections of the sheet 32 being stacked prevents any undulations in the stacked sheet from causing errors in the height position of the starting support 151, avoiding other jamming risks for the new sheet to be stacked. Furthermore, the accurate detection of thicknesses and imperfections of the sheets being stacked prevents any undulations on the stacked sheet from causing height positioning errors of the starting support 151, thus avoiding further risks of jamming for the new sheet to be stacked.

[0122] Upon reaching the total number of sheets 32 to be stacked, the electronic unit 37 temporarily disables the input of new sheets and activates the compensation motor 172, moving the stack support 53 from the last stacking position to the delivery position “DP”. The supporting surface “BS” of the delivery belts 162 is coplanar with the conveyor belt “CB”, and the panel 164 is located below the output gate “OG”, uncovering it completely.

[0123] The electronic unit 37 then activates the delivery motor 157, moving the upper branches of the delivery belts 162 in the direction “F”, resulting in the subsequent conveyance of the stack 33 (FIG. 12) with the stacked sheets onto the conveyor belt “CB” for dispatch to the user equipment.

[0124] During this delivery phase, the electronic unit 37 activates the starting compensation mechanism 184 and the fork actuation mechanism 183, moving the starting support 151 to the “machine zero” condition, high, with the forks 182 in the retracted configuration, and re-enables the intake of new sheets for forming a new stack, thereby reducing dwell times.

[0125] Once the delivery of the stack 33 is completed, the electronic unit 37 stops the motor 157 and activates the compensation motor 172, with the rotation of the splined shafts (166 and 167) in the direction opposite to the lowering direction, lifting the stack support 53 to the reference position “RP” of FIG. 3 for the start of a new stacking operation, with the surface “BS” positioned below the forks 182.

[0126] In the specific condition of sheet forwarding without any stacking, the operator lifts the stopping member 82 and the offset stop 111 using the lifting lever 116 and inputs an exclusion command, via the control panel, to the electronic unit 37, with the activation of the compensation mechanism 54 and the delivery motor 157. The starting support remains high, but with the forks 182 in the retracted configuration, below the alignment section 34.

[0127] The compensation mechanism 54 lifts the stack support 53 to the extra-stroke position, with the supporting surface “BS” in a condition of tangency with the lower branches 62 of the conveyor belts 52 in correspondence of the rear service opening, while the delivery motor 157 moves the delivery belts 162.

[0128] The incoming sheets, after being deflected downward by the input rollers 51, are guided along the surface “TS” through the sequential action of the active section 95 (also with suction) and of the terminal section 98 of the lower branches 62 of the conveyor belts and by the upper branches of the delivery belts 162, up to the service opening “DTG”.

[0129] Naturally, without departing from the principle of the invention, the actuation forms and construction details of the sheet stacking equipment may be widely varied with respect to what has been described and illustrated by way of non-limiting example, without thereby departing from the scope of the present invention.

[0130] For instance, the accommodating space for the stopping member and for the offset stop can be realized by deflection means other than the intermediate rollers and the deviation rollers.

[0131] In the event that the forwarding without stacking is not required, the structure of the functional block and the path of the conveying belts can be simplified by providing only intermediate rollers and deviation rollers for the formation of the accommodating space. In this variant, the terminal section of the lower branches of the belts will be guided by rear rollers at the level of the upper part of the deviation rollers, without the possibility of forwarding sheets for transfer.

[0132] According to a variant, the sheet thickness control utilizes an equivalent structure where the torsion springs 127 are omitted, and the sensing action of sensing rollers 84 on sheets 32 is performed solely by the force of the torsion springs 136 or different springs acting on the common shaft 133.

[0133] In a further variant, the intermediate element for movement transmission between the sensing supports 121 and the common shaft 133 is achieved for example via a single rocker arm, featuring angular adjustment capability on the common shaft and a rounded terminal that cooperates with the upper part 124 of the corresponding sensing support 134.

Examples

Embodiment Construction

[0028]With reference to FIGS. 1 and 2, a sheet stacking equipment, indicated as 31, receives paper sheets 32 at the front from external apparatus along a direction “F”. The stacked sheets are sent, as a stack or pack 33, through an output gate “OG” at the rear to an external processing apparatus by means of a conveyor belt “CB”.

[0029]The stacking equipment 31 is of the type indicated as 21 in the aforementioned patent EP 4 363 234, hereinafter “Patent”, which is incorporated herein by reference.

[0030]In summary, the stacking equipment 31 includes, at the front, an alignment section 34, at the rear a stacking and delivery section 36, and comprises an electronic control unit 37, a push-button panel 38, a control panel “CP”, a compressed-air generator 39 and sensor elements (not shown) arranged along the sheet path.

[0031]The alignment section 34, similar to the section 31 of the Patent, aligns the sheets 32 on a respective receiving surface and forwards them toward the stacking and del...

[0001] This application claims priority to Italian Application No. 102025000006117 filed on Mar. 25, 2025, the entire content of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present invention relates generally to sheet processing systems and, more particularly, to a sheet stacking equipment employing suction-driven conveying belts for high-speed sheet handling and alignment.

[0003] In particular, the invention relates to a sheet stacking equipment comprising suction conveyor belts, a stack support for vertically stacked sheets, input rollers for the sheets to be stacked, an electronic control unit, a stopping member for the incoming sheets, and a functional support block for the stopping member. The conveyor belts have lower branches arranged above the stack support and are motor driven for dragging incoming sheets along a transport surface by suction. The support block is longitudinally movable to position the stopping member at a distance from the input rollers based on the length of the sheets, such that stopped sheets are deposited onto the stack support or onto already stacked sheets.BACKGROUND

[0004] A stacking equipment of this type is disclosed in European Patent EP 4 363 234 of the Applicant TECNAU S.r.l., of which the present invention represents a substantial improvement.

[0005] In the TECNAU patent, the stopping member for incoming sheets is mounted on a support block and comprises a transverse plate with a plurality of stop fins on its lower portion. These fins project between the lower branches of the belts, forming a vertical alignment surface of the stack and being longitudinally movable depending on the length of the sheets to be stacked. The equipment also includes a compensation mechanism for adjusting the height of the stack support based on the stacked sheets and a pressure crossbar acting on the forming stack to stabilize it and detect stack height for the compensation mechanism.

[0006] Sheet stacking equipment with the above structure is fast, reliable and capable of handling large sheets with varying rigidity and sliding characteristics, particularly medium to heavy weight sheets. However, for very light sheets, discontinuities in the stop fins can cause damage to the leading edges of the sheets, aesthetic defects, misalignment, or jamming. Additional problems may arise from the action of the pressure crossbar, adjustment of the compensation mechanism, or its operation with particular types of sheets.SUMMARY

[0007] An object of the present invention is to provide stacking equipment with suction conveying belts that can reliably handle sheets at high speed, including sheets with widely varying characteristics and medium-to-light weight sheets.

[0008] According to this object, the sheet stacking equipment further comprises deviation means associated with the lower branches and supported by the functional support block, the deviation means being configured to form an accommodating space above the transport surface, upstream of and adjacent to the stopping member. The stopping member is arranged within the accommodating space and has a cross-section projecting below the transport surface to stop the sheets and define a vertical alignment surface of a stack. The cross-section of the stopping member has a continuous profile configured to act as a stop for the leading edge of the stacking sheets.

[0009] By providing a continuous stop surface instead of discrete fins, the equipment prevents damage to the leading edges of lightweight sheets and ensures precise vertical alignment.

[0010] According to another feature, the sheet stacking equipment further comprises a sensor device and a compensation mechanism for adjusting the height of the stack support. The sensor device includes a plurality of sensing rollers interposed between the lower branches of the transport belts and configured for individual movement; a plurality of sensing supports rotatably supporting the sensing; a common shaft with a plurality of contrast elements arranged above the sensing rollers; and spring means for applying a tensioning action from the contrast rollers onto the sensing supports via the common shaft.

[0011] The sensor device provides information to the electronic control unit for the compensation mechanism in response to rotation of the common shaft, determined by the maximum lifting height of the sensing rollers.DESCRIPTION OF THE DRAWINGS

[0012] The features of the invention will become clear from the following description, given by way of non-limiting example with the aid of the attached drawings, in which:

[0013] FIG. 1 represents a schematic perspective view, conventionally front, of sheet stacking equipment according to the invention;

[0014] FIG. 2 is a partial side section of the equipment of FIG. 1;

[0015] FIG. 2a shows some details, on an enlarged scale, of components of FIG. 2;

[0016] FIG. 3 represents a schematic top perspective view of some functional units of the equipment of FIG. 1;

[0017] FIG. 4 is a schematic bottom perspective view of the functional units of FIG. 3;

[0018] FIGS. 5a and 5b show some parts of FIG. 2, on an enlarged scale;

[0019] FIG. 6 is a schematic exploded view of some components of FIG. 3;

[0020] FIGS. 6a, 6b and 6c show some details of the components of FIG. 6;

[0021] FIGS. 7 and 7a are further schematic views of some components of FIG. 3;

[0022] FIG. 7b is a schematic bottom view of some components of FIG. 4;

[0023] FIGS. 8, 8a, 8b and 8c show some components of the equipment of FIG. 2, on an enlarged scale;

[0024] FIG. 9 represents parts of FIG. 8 during a calibration phase;

[0025] FIG. 10 represents a schematic top perspective view of further functional units of the equipment of FIG. 1 in a given operating condition;

[0026] FIG. 11 shows the units of FIG. 10 in another operating condition; and

[0027] FIG. 12 shows components of FIG. 2 in another operating condition.GENERAL DESCRIPTION

[0028] With reference to FIGS. 1 and 2, a sheet stacking equipment, indicated as 31, receives paper sheets 32 at the front from external apparatus along a direction “F”. The stacked sheets are sent, as a stack or pack 33, through an output gate “OG” at the rear to an external processing apparatus by means of a conveyor belt “CB”.

[0029] The stacking equipment 31 is of the type indicated as 21 in the aforementioned patent EP 4 363 234, hereinafter “Patent”, which is incorporated herein by reference.

[0030] In summary, the stacking equipment 31 includes, at the front, an alignment section 34, at the rear a stacking and delivery section 36, and comprises an electronic control unit 37, a push-button panel 38, a control panel “CP”, a compressed-air generator 39 and sensor elements (not shown) arranged along the sheet path.

[0031] The alignment section 34, similar to the section 31 of the Patent, aligns the sheets 32 on a respective receiving surface and forwards them toward the stacking and delivery section 36.

[0032] The stacking and delivery section 36 consists of a transport and deposition unit 41, similar to unit 41 of the Patent, adjacent to the alignment section 34, and an accumulation and delivery unit 42, similar to unit 42 of the Patent, arranged below the unit 41.

[0033] As regards the present invention, the alignment section 34 comprises a series of alignment rollers 43 that align the edges of the sheets 32, even when side-by-side. The incoming sheets are then forwarded along the direction “F”, with suitable spacing between sheets, on a receiving surface, horizontal in use, toward the stacking and delivery section 36.

[0034] The transport and deposition unit 41 comprises input rollers 51 and conveying belts 52 for receiving and positioning incoming sheets above the stack 33 along a transport surface “TS”. The accumulation and delivery unit 42 in turn comprises a stack support 53 and a compensation mechanism 54, similar to stack support 46 and compensation mechanism 47 of the Patent.

[0035] The stack support 53 as the stack support of the Patent receives the sheets being stacked and forwards the stack 33 toward the conveyor belt “CB”, while the compensation mechanism 54 vertically moves the support 53 depending on the stacked sheets. The accumulation and delivery unit 42 may also forward the received sheets 32, without stacking, through a rear service opening “DTG”, substantially aligned with the transport surface “TS”.

[0036] In the transport and deposition unit 41, the input rollers 51 (FIGS. 2, 5a and 5b) include a driving roller 56 and a pressure roller 57 engaging each other on an introduction surface coplanar with the receiving surface of the alignment section 34.

[0037] The driving roller 56 and the pressure roller 57 are rotatably mounted on a frame 58 of the unit 41 and are driven through belts and pulleys by a feed motor 59 controlled by the electronic unit 37 to advance the sheets 32 in the direction “F”.

[0038] The conveying belts 52 extend horizontally and have respective upper branches 61 and lower branches generally indicated as 62. The lower branches are positioned above the stack support 53 and define, with their outer surface, the transport surface “TS” for the incoming sheets 32, horizontal in use and located below the introduction surface between the rollers 56 and 57.

[0039] The conveying belts 52 are longitudinally holed and coupled with one or more transverse ducts 69 arranged above the lower branches 62. Each duct 69 is connected at its upper portion to a series of suction fans 71. On their lower surfaces the ducts 69 have belt-guiding slots with suction openings adapted to exert a suction action on the sheets 32.

[0040] The conveying belts 52 are tensioned, through suitable guides, by the driving roller 56, by front rollers 72 and 73 respectively upper and lower, and by rear rollers 74 and 76 respectively upper and lower, rotatably mounted on the frame 58. The front rollers 72 and 73 deviate upward and downward the belts 52 engaged by roller 56, while rollers 74 together with rollers 72 define the upper branches 61 horizontally.

[0041] In particular, the belt stretches between the input rollers 51 and the front rollers 72 are inclined downward and guide the sheets 32 emerging from rollers 51 toward the transport surface “TS”. The rear rollers 76 together with the front rollers 73 define the lower branches 62 forming the conveying surface “TS”. Return rollers 77 are also provided for tensioning the belts 52, rotatable on the frame 58 in an intermediate position between the rollers 74 and 76.

[0042] The upper branches 61 and lower branches 62 of the belts 52 are vertically spaced sufficiently to accommodate the ducts 69 with fans 71 and other components of the transport and deposition unit 41.

[0043] Conveniently, downstream of the input rollers 51 spring leaves 78 and a compressed-air nozzle 79 connected, via a corresponding solenoid valve, to the compressed-air generator 39 are provided. The spring leaves 78 and the nozzle 79, when activated with air jets, act on the downward inclined stretches of belts 52 to facilitate detachment of incoming sheets from the belts together with their release from the input rollers 51.

[0044] In a known manner, the guides for conveying the belts 52 are formed on the lateral surface of hollow cylinders corresponding to the numbering indicated. The hollow cylinders are rotatable through bearings on corresponding shafts mounted on the frame 58. These guides have a slightly convex (crowned) profile producing a self-centering effect on the moving belts 52.

[0045] By action of the feed motor 59 and through the driving roller 56, the conveying belts 52 drag the incoming sheets 32 by adhesion due to suction along the lower branches 62 and deposit them onto the stack support 53 or onto the last sheet of the forming stack 33.Functional Block and Stopping Member

[0046] The stacking equipment 31 comprises, in the transport and deposition unit 41, a functional block 81 similar to the functional block 50 of the Patent, on which a corresponding stopping member 82 for the incoming sheets 32 is mounted.

[0047] The functional block 81 also supports a sensing device 83 for the last deposited sheet of the stack, including a series of sensing rollers 84 and an electronic sensor 85.

[0048] The block 81 (FIGS. 2, 3, 5b and 7) comprises a transverse flat bar 86, two side members 87r and 87l at the sides of the bar 86, and a transverse profile 88.

[0049] The bar 86 supports the stopping member 82, while the profile 88 supports the sensing rollers 84 and is mounted in front of the bar 86.

[0050] The side members 87r and 87l are slidably coupled and lockable with two lateral guides 89r and 89l, allowing the stopping member 82 to be positioned at a distance from the input rollers 51 that exceeds the length of the sheets 32.

[0051] One or more ducts (69), the number of which depends on the length of the sheets to be stacked, are mounted on sides that slide along the lateral guides (89r, 89l) and are selectively positionable at varying distances from the input rollers (51) based on said sheet length.

[0052] The positioning of the block 81, and the ducts 69 may be performed manually or by means of motors, optionally controlled based on the sensed length of the sheets.

[0053] To avoid the problems of known stacking equipment, the equipment 31 adopts innovative and effective solutions for the stopping member 82 and for control of the compensation mechanism 54.

[0054] Conveniently, the stacking equipment 31 provides a continuous stop profile for the stopping member 82 and deviation means 90 for the lower branches of the belts carried by the functional block 81 so as to form, above the conveying surface “TS”, an accommodating space for the stopping member 82.

[0055] Specifically, the deviation means 90 comprise intermediate rollers 91 (FIGS. 2, 5b, 8), deviation rollers 92 and realignment rollers 93 guiding the lower branches 62 of the belts 52. The rollers 91, 92 and 93 are rotatably mounted between the side members 87r and 87l of the functional block 81 and form a loop in the belts 52 creating an accommodating space 94 for the stopping member 82.

[0056] The front lower rollers 73 (fixed) and the intermediate rollers 91 (movable) guide an active section 95 of the lower branches 62 along the conveying surface “TS” for sheet dragging. The deviation rollers 92 are arranged above the intermediate rollers 91 and guide, together with the rollers 91, an upward deviated section 96 of the lower branches forming downstream and near rollers 91 the accommodating space 94 above the stack support 53.

[0057] The realignment rollers 93 are arranged at the same height as the intermediate rollers 91 and guide, together with the deviation rollers 92, a downward deviated section 97 of the lower branches. Finally, the realignment rollers 93 together with the rear rollers 76 guide a terminal section 98 of the lower branches 62 along the conveying surface “TS”. In detail, the deviation rollers 92 are positioned in a median area between the intermediate rollers 91 and the realignment rollers 93, determining a substantially inverted-U section of the loop delimiting the accommodating space 94.

[0058] The stopping member 82 comprises a plate 99 with a transverse section 101 arranged adjacent and downstream of the intermediate guide rollers 91, inside the accommodating space 94, upstream of the bar 86 and projecting downward from the conveying surface “TS”. The section 101 is intended to stop the moving sheets 32 and define a vertical alignment surface “AS” for the forming stack 33.

[0059] During the stacking process, the sheets 32 advance by the combined action of the input rollers 51 and the conveying belts 52. However, the sheets leave the rollers 51 before their leading edges contact the transverse section 101, and movement up to the stop is ensured solely by the conveying belts 52 through adhesion.

[0060] Advantageously, the transverse section 101 has a continuous profile acting as an abutment for the leading edge of the sheets 32 being stacked.

[0061] The continuous stop profile solution avoids the problems associated with the comb-type stop structure of the Patent. In particular frontal damage, especially at high operating speeds, and the impossibility of handling light or very light paper (<60 gsm) due to stacking jams even at low speeds.

[0062] The intermediate guide rollers 91 (FIGS. 7, 7a, 7b, 8, and 8a) consist of pulleys 102, which support the belts 52 and project from a shaft 103 rotatable between the side members 87r and 87l of the functional block 81. In turn, the transverse profile 88 has a substantially “L”-shaped section and features a lower surface with a rounded front edge, which serves as a sliding surface for the lower branches of the belts, and longitudinal extensions 104, comb-shaped, at the sides of the pulleys 102.

[0063] The longitudinal extensions 104 function as guides for the leading edges of incoming sheets and, when abutting, up to the cross-section 101 of the stopping member 82. Conveniently, the longitudinal extensions 104 are inclined downward to gradually bring the leading edges of the sheets being stacked closer to the stack 33 near the stop.

[0064] Analogous to the equipment 21 of the Patent, the sheet-stacking equipment 31 also allows the formation of bundles with both regular blocks and staggered blocks.

[0065] To this end, the equipment 31 includes an offset stop 111, mounted in the accommodating space 94, and an offset actuator 112, for example of the electro-pneumatic type. The offset stop 111 has a cross-section 113, also with a substantially continuous profile, positioned behind the cross-section 101 of the stopping member 82 along direction “F”. The stopping member 82, with its cross-section 101, can be lifted by the offset actuator 112 to stop the sheets being stacked against the cross-section 113 of the offset stop 111 for a staggered stack surface relative to the alignment surface “AP”.

[0066] In detail, the plate 99 of the stopping member 82 is slidably mounted via guides 114 (FIGS. 6, 7, and 8), vertical in use, fixed to a front surface of the transverse bar 86. The offset stop 111 includes a crossbeam positioned behind the bar 86 and can be lifted by a lever 116 when the equipment 31 is set to transfer sheets 32 without stacking.

[0067] Conveniently, the cross-section 101 of the stopping member 82 has an inclined lower surface. This surface can be aligned with the lower surfaces of the longitudinal extensions 104 when the stopping member 82 is lifted by the offset actuator 112, enabling smooth stacking even for the formation of staggered blocks.

[0068] In the stacking equipment 31, the sensor device 83 (FIGS. 2, 5b, and 8c) is linked to the compensation mechanism 54 to ensure optimal conditions for stacking sheets regardless of the number of sheets already stacked. Specifically, the distance between the transport surface “TS” and the last sheet of the forming stack 33 is maintained constant in an optimized manner.Stack Height Compensation

[0069] According to another feature of the invention, in the sensor device 83, the sensing rollers 84 (FIGS. 5b, 6, 6b, 8, 8a) are arranged transversely between the lower branches 62 of the belts and are rotatably mounted on inverted U-shaped bridge supports 121. The bridge supports 121 are pivoted on pins 122 mounted via sensing blocks 123 on the transverse profile 88 and feature an upper part 124 above the rollers 84.

[0070] The sensing rollers 84 protrude with their lower sectors through corresponding windows 126 from the lower surface of the profile 88 (FIGS. 6b, 7b, and 8a) and face corresponding sheet sensing areas in the stack. A series of sensing springs, constituted by torsion springs 127 mounted on the pins 122 act on the bridge supports 121 to apply individual sensing pressure of the rollers 84 on the stack, and at rest, against end-of-travel stops 128.

[0071] A series of counter rollers 129, rotatable on intermediate supports 131, are arranged above the sensing rollers 84. The supports 131 are fixed but adjustable in angle via grub screws 132 on a common shaft 133. The shaft 133 is rotatably mounted on the profile 88 via supports 134 and serves as a mounting for two torsion springs 136 that push the counter rollers 129 against the upper part 124 of the bridge supports 121.

[0072] The transverse profile 88, together with the sensing rollers 84, the counter rollers 129, the common shaft 133, and associated parts, constitutes a sensing assembly that can be easily removed from the functional block 81 for maintenance via right and left knobs 137r and 137l securing the ends of the profile 88 to the side members 87r and 87l of the functional block 81.

[0073] On a setup phase of the stacking equipment 31, by means of a specific tool, the end-of-travel stops 1281 are adjusted so that the sensing rollers 84 are all aligned. Furthermore, the angular positions of the intermediate supports 131 is adjusted so that the counter rollers 129 are in contact with the upper parts 124 of the bridge supports 121.

[0074] During stacking, the sensing rollers 84 can be displaced upward by the sheet being stacked depending on its thickness (0.07–0.5 mm) in the sensing area. This displacement is transmitted to the counter-rollers 129 via the upper part 124 of the bridge supports 121, triggering the rotation of the common shaft 133 through the intermediate supports 131 and the upward lifting of the vane 141. Should a sheet 32 have a greater thickness in a specific sensing area, the rotation of the common shaft 133 is driven by the maximum lifting of the sensing rollers 84 operating on that thicker area.

[0075] The sensing action of the sensing rollers 84 on the sheets being stacked is performed by the combined force of the torsion springs 127 on the sensing rollers 84 and the torsion spring 136 on the common shaft 133, acting via the counter-rollers 129. The torsion springs 127 serve two functions: first, they maintain stable contact between the sensing rollers 84 and the sheets 32 in the thinner areas; second, they hold the rollers 84 against their respective end-of-travel stops 128 in the absence of sheets or their spacing.

[0076] In practice, the sheets 32 may exhibit imperfections (swelling, creases, ink variations, etc.) which the sensing rollers 84 detect by lifting. The sensing roller 84 that encounters the maximum imperfection lifts higher than the other and, via upper part 124 of the bridge supports 121, further rises the overlying counter-roller 129. This causes a further rotation of the shaft 133 and the lifting of the vane 141. Meanwhile, the other counter-rollers detach from the bridge parts 124 that remain lower, while the respective sensing rollers 84 are kept in contact with the sheets by the action of the springs 127.

[0077] In the sensor device 83, the electronic sensor 85 (FIG. 8c) is a laser illuminator / detector similar to that of the Patent. In the stacking equipment 31, the target area of the sensor device includes a vane 141 fixed on the shaft 133, which oscillates horizontally in response to movements of the sensing rollers 84 caused by incoming sheets and the corresponding movements of the counter rollers 129.

[0078] Advantageously, the accumulation and delivery assembly 42, in addition to the stack support 53 (FIGS. 2, 10, 11, and 12), includes a starting support 151 to ensure optimal stacking of the first sheets of the stack 33 and to accelerate transitions between the delivery of the completed pack and subsequent stacking.

[0079] The stack support 53 comprises, in summary, a frame 152 beneath the transport and deposit assembly 41, two transverse shafts 153 and 154, respectively front and rear, rotatably supported by the frame 152, a plurality of functional and delivery blocks 156 carried by the frame 152, and a delivery motor 157 for the shafts 153 and 154.

[0080] The functional and delivery blocks 156 (FIG. 2a) have an elongated parallelepiped shape, spaced transversely from one another, and each comprises a spar 158, two terminal pulleys 159 and 160 keyed on the shafts 153 and 154, intermediate idler rollers 161, and an elongated delivery belt 162 stretched between the pulleys 159 and 160. The pulleys 159 and 160 of each block 156 have upper sectors tangent to the upper surfaces of the spar 158. The upper run of the belt 162 rests on the upper surface of the spar 158, while the lower run is deflected upward by the idler rollers 161.

[0081] The assembly of the upper runs of the delivery belts 162 forms a supporting surface “BS” for the forming stack 33, with support by the spars 158. The belts 162 are driven by the motor 157 in direction “F”, sliding over the upper surfaces of the spars 158 during delivery by the stacking equipment 31.

[0082] The stack support 53 can move vertically via a pair of vertical guides 163l and 163r between a reference position “RP” and a delivery position “DP” (FIG. 9). The reference position “RP”, high, corresponds to an operational condition following an initial phase of no sheets. The delivery position “DP” is the lowest position of the stack support 53, where the surface “BS” is substantially coplanar with the lower edge of the output gate “OG” and with the conveyor belt “CB”.

[0083] A panel 164 is mounted vertically downward on a rear part of the frame 152. The output gate “OG” is shielded by the panel 164 when the stack support 53 is in the reference position “RP” and is clear when the support 53 is in the delivery position “DP”.

[0084] For the condition of sheet transfer without stacking, the stack support 53 can also be moved to a high extra-stroke position where the supporting surface “BS” is tangent to the lower branches 62 of the conveyor belts, coplanar with the “TS” surface in correspondence of the rear service opening “DTG”.

[0085] As previously reported, depending on the number of sheets stacked, the compensation mechanism 54 lowers the stack support 53 from the reached position to the delivery position “DP” upon completion of the stack 33. In this position “DP”, the upper runs of the delivery belts 162 are moved by the delivery motor 157 to forward the stack 33, through the output gate “OG”, onto the conveyor belt “CB” for subsequent processing.

[0086] The compensation mechanism 54 comprises a pair of ball-screw assemblies with splined shafts 166 and 167 and corresponding nuts 168 and 169. The nuts 168 and 169 are fixed to the sides of the frame 152, while the splined shafts 166 and 167 are rotatably supported, with a lower end, on a transverse plate 171 and are driven in rotation, via belts and pulleys, by a compensation motor 172, which is also controlled by the electronic unit 37.

[0087] The starting support 151 includes a frame 179 positioned beneath the alignment section 34, a multi-fork support 181 mounted for sliding on the frame 179, a series of forks 182 mounted on the multi-fork support, an actuation mechanism 183 for the multi-fork support, and a starting compensation mechanism 184 for the frame 179.

[0088] The forks 182 can be inserted between the functional and delivery blocks 156 and are actuated by the fork actuation mechanism 183, activated by the electronic unit 37, to move the forks 182 from a retracted configuration to an inserted configuration. In the retracted configuration, the forks are closed on the frame 179 below the alignment section 34. In the inserted configuration, the forks protrude from the frame 179 and can be inserted between the functional and delivery blocks 156 of the stack support 53.

[0089] In summary, the fork actuation mechanism 183 comprises two pulleys 187 and 188 rotatably supported, centrally, at the front and rear of the frame 179, a displacement belt 189 stretched between pulleys 187 and 188, and a fork actuation motor 191. The multi-fork support 181 is engaged with the upper run of the displacement belt 189 for moving the forks 182 between the retracted and inserted configurations.

[0090] The starting compensation mechanism 184 is provided to adjust the height of the frame 179 with the multi-fork support according to the height of the sheets being stacked. This mechanism 184, similar to the compensation mechanism 54 and comprising a starting compensation motor 192 and a screw-and-nut conversion mechanism, is not described here for the sake of brevity.

[0091] During a startup phase, the stack support 53 is in the reference position “RP” and the forks 182 are in the inserted configuration, above the upper runs of the delivery belts 162. The forks 182 thus form a temporary support replacing the belts 162, with a surface optimized for stacking the first sheets of the stack.

[0092] For a predetermined stack height, e.g., 10 sheets, the forks 182 are slightly lower than the supporting surface “BS” and the forming stack 33 rests on the delivery belts 162. The electronic unit 37 can activate the actuation mechanism 183 to move the forks 182 to the retracted configuration and can activate the starting compensation mechanism 184 to adjust the height of the stack support 53 during operation based on the number of sheets stacked beyond the predetermined height.

[0093] According to a feature of the invention, the stacking equipment 31 provides for the stacking of the sheets a fixed reference represented by a “machine zero” level and software-based control for the height compensation of the stack support 53 or the starting support 151. The “machine zero” level corresponds to the one of a transport surface “TS” of the sheets 32 in the area of tangency with the conveyor belts 52 guided by the intermediate rollers 91. The software control, in turn, allows adjustment of the height compensation of the stack support 53 or the starting support 151 based on operational experience of the equipment 31.

[0094] Upon request, the sensor device 83 can be calibrated using a calibration tool (master) 196 (FIG. 9) to correctly set the initial reading value for the “machine zero” level.

[0095] The calibration tool 196 comprises an L-shaped profile in which a vertical part 197 is comb-like and a base part 198 is flat. The vertical part 197 can be inserted between the conveyor belts 52 and coupled with the front part of the profile 88, while the base part 198 lifts the sensing rollers 84 to the “machine zero” level, allowing the operator to correctly set the sensor zero. Once the calibration tool 196 is removed, the sensing rollers 84 return to their initial position against the end-of-travel stops 128, performing a displacement “X” that will correspond to the initial reading value of the sensor device 83.

[0096] The electronic sensor 85, reading the target area constituted by the vane141, will therefore measure a deviation value “X” relative to another previously measured value. The measured values are then used to correct, via software, the descent of the support on which the stack is being formed, thus closing the process control loop.

[0097] More specifically, by means of a parameter that can be set from the panel “CP”, depending on the paper thickness, the operator sets the “theoretical pitch” for the descent of the stack support 53 and starting support 151, for example, 0.15 mm. The operator also sets the “theoretical reference position” for the sensor reading: “zero”, “negative”, or “positive” values. For instance, if the set value is “zero”, the support will descend so that the sensor 85 consistently measures values near zero, thus keeping the stack composition close to “machine zero” for an average compression of the stack 33 being formed.

[0098] If the set value is greater than zero, the support will descend while attempting to maintain the sensor measurement at this value, resulting in a more compressed stack (position of the the sensing rollers 84 higher than “machine zero”). If the set value is less than zero, the support will descend while attempting to maintain the sensor measurement at this value, resulting a less compressed stack (position of the sensing rollers 84 lower than “machine zero”).

[0099] During stacking, the software also perform a sampling every “n” values measured by the sensor 85 and calculates an average. The average value is then used to correct the “theoretical pitch” set by the operator. The resulting “average corrected pitch” will allow for an optimal descent of the stack support or starting support to keep the sensor reading close to the set value. Consequently, this descent will be the one expected for the last incoming sheet on the stack being formed.

[0100] The “average corrected pitch” is also displayed on the panel for the operator, who can thus have visual feedback of the actual pitch currently being applied by the equipment 31.

[0101] To accommodate the multiple types of paper and formats processable, the values set by the operator can be saved in reusable recipes to ensure repeatability of the operations.

[0102] The operation of the equipment 31 for sheet stacking is as follows:

[0103] Depending on the longitudinal dimensions of the sheets 32 to be stacked (FIGS. 1 and 2), the operator positions the functional block 81 and the duct or ducts 69 at programmed distances from the input rollers 51. Through the control panel “CP”, the operator also sets data on the number of sheets 32 to stack, the number of sheets per block for offset stacking (if required), the characteristics of the sheets, the “theoretical pitch” and the “average corrected pitch”. The operator can also set the number of sheets to stack on the forks 182 during the start phase and thus the reference position “RP”.

[0104] In an initial phase, the stack support 53 (FIG. 3) is empty and in the reference position “RP”, and the output gate “OG” is blocked by the panel 164. The starting support 151 is in a high position, at the “machine zero” condition, with the forks 182 in the inserted configuration, interposed between the blocks 156 of the stack support 53, to receive the incoming sheets in stacking.

[0105] The electronic unit 37 activates the feed motor 59, rotating the input rollers 51 with movement of the belts 52 at a conveying speed slightly higher than the sheet feed speed.

[0106] At the exit from the alignment section 34, the input rollers 51 advance the sheet 32 positively along the inclined belt sections. The sheet is bent and guided downward until its leading edge meets the forks 182 of the starting support 151. The sheet is then bent again and guided horizontally by the action of the input rollers 51 and with the contribution of the lower branches 62 of the belts 52.

[0107] The first sheet 32 continues its travel until its leading edge passes the position of the duct or first duct 69. Here, the sheet is lifted against the branches 62 of the belts 52 by suction from the duct 69 through the openings in the guide notches and through the holes in the belts 52. The sheet continues to advance through the passage and suction of successive parts in front of the openings and the combined positive drag action of the input rollers 51.

[0108] If the equipment 31 includes multiple ducts 69, after the first duct lifts the sheet 32, adhesion to the belts 52 is perfected as the sheet passes in front of the other ducts.

[0109] After the trailing edge leaves the rollers 51, the sheet 32 continues to be dragged solely by the belts 52, with adhesion ensured by the duct or ducts 69, and tends to return to a flat configuration, facilitated by the elastic separating tabs 69 and compressed air jets from the nozzle 79.

[0110] As it moves along the belts 52, the first sheet 32 encounters its leading edge with the sensing rollers 84, which are raised depending on the sheet thickness, lifting the vane 141. The sheet is finally stopped when it meets the cross-section 101 of the stopping member 82, with slippage of the belts 52 on the sheet. While waiting for another sheet 32 to be stacked, the feed motor 59 remains activated, keeping the input rollers 51 and the belts 52 in motion.

[0111] The introduction of the first sheet 32 into the transport and deposit group 41 triggers, by command of the electronic unit 37, the start compensation motor 192 to lower the starting support 151 by an amount corresponding to the “theoretical pitch” and the “theoretical position”, in response to feedback from the laser illuminator / detector 85 on the position of the target area 141.

[0112] A new sheet 32 entering from the input rollers 51 is also bent and guided downward by the input rollers 51 and the inclined belt sections, but its leading edge now meets the previous sheet. Due to the pushing action from the input rollers 51, the inclined belt sections, and the insertion roller 73, the new sheet is bent and guided horizontally, inserting itself between the lower branches 62 of the belts and the portions of the previous sheet still adhering to the branches 62.

[0113] The new sheet 32 continues its travel above the previous sheet until its leading edge reaches the duct or the first duct 69, coming into contact with its lower surface. The portion of the previous sheet, no longer held by the suction of the duct falls onto the surface of the forks 182, while the new sheet adheres to the branches 62 of the belts and is dragged by them. The new sheet then continues to advance due to the passage and suction of successive parts in front of other ducts 69, while the previous sheet progressively settles onto the forks 182 as the first sheet of the stack 33.

[0114] The new sheet 32 continues its movement solely by means of the conveyor belts 52 due to adhesion ensured by the duct or ducts 69 after its trailing edge leaves the rollers 51. The new sheet tends to return to a flat configuration and rests its trailing edge on the previous sheet, facilitated by the spring leaves 78 and compressed air jets. In sequence, the new sheet lifts the sensing rollers 84 depending on its thickness, with the consequent lifting of the vane 141. The sheet is finally stopped when its leading edge contacts the cross-section 101 of the stopping member 82, with the moving belts 52 slipping on the sheet.

[0115] The completion of the introduction of the new sheet 32 into the transport and deposition unit 41 triggers again the compensation motor 192, under the control of the electronic unit 37 and feedback from the sensor device 83, lowering the starting support 151 by an amount corresponding to the set data..

[0116] Stacking of subsequent sheets occurs sequentially as previously described for the second sheet, with the progressive formation of the stack 33 and any corrections to the lowering of the starting support 151 based on the “average corrected pitch”.

[0117] Upon reaching the number of sheets planned for the stack height at start-up, the forks 182 are positioned to a level slightly lower than the surface “BS”, and the forming stack 33 rests on the delivery belts 162. The electronic unit 37 then activates the fork actuation motor 191 to move the forks into their retracted configuration, thereby leaving the stack support 53 free to receive further sheets being stacked.

[0118] The forming stack 33 now rests on the supporting surface “BS” constituted by the delivery belts 162, and the stacking process of sheets 32 continues as previously described for the support on the forks 182, but with the height compensation of the stack support 53 entrusted to the compensation mechanism 54. Specifically, for the new incoming sheets 32, the electronic unit 37 activates the compensation motor 172, lowering the stack support 53 according to the set data and corrections based on the “average corrected pitch”.

[0119] In the event that the offset option is provided, after the set number of sheets forming each block has been stacked, the electronic unit 37 activates the offset actuator 112, lifting the stopping member 82. The offset stop 111 replaces the transverse section 101, thereby determining the alignment plane for the staggered blocks.

[0120] During the stacking process, the continuous profiles of the transverse sections 101 or 113 of the stopping members 82 prevent the impact of incoming sheets 32 and the thrusts of the conveyor belt 52 from causing deformations of the leading edges or sheet curling, which could lead to overlapping and jamming upon the arrival of subsequent sheets.

[0121] In turn, the accurate detection of the thickness and imperfections of the sheet 32 being stacked prevents any undulations in the stacked sheet from causing errors in the height position of the starting support 151, avoiding other jamming risks for the new sheet to be stacked. Furthermore, the accurate detection of thicknesses and imperfections of the sheets being stacked prevents any undulations on the stacked sheet from causing height positioning errors of the starting support 151, thus avoiding further risks of jamming for the new sheet to be stacked.

[0122] Upon reaching the total number of sheets 32 to be stacked, the electronic unit 37 temporarily disables the input of new sheets and activates the compensation motor 172, moving the stack support 53 from the last stacking position to the delivery position “DP”. The supporting surface “BS” of the delivery belts 162 is coplanar with the conveyor belt “CB”, and the panel 164 is located below the output gate “OG”, uncovering it completely.

[0123] The electronic unit 37 then activates the delivery motor 157, moving the upper branches of the delivery belts 162 in the direction “F”, resulting in the subsequent conveyance of the stack 33 (FIG. 12) with the stacked sheets onto the conveyor belt “CB” for dispatch to the user equipment.

[0124] During this delivery phase, the electronic unit 37 activates the starting compensation mechanism 184 and the fork actuation mechanism 183, moving the starting support 151 to the “machine zero” condition, high, with the forks 182 in the retracted configuration, and re-enables the intake of new sheets for forming a new stack, thereby reducing dwell times.

[0125] Once the delivery of the stack 33 is completed, the electronic unit 37 stops the motor 157 and activates the compensation motor 172, with the rotation of the splined shafts (166 and 167) in the direction opposite to the lowering direction, lifting the stack support 53 to the reference position “RP” of FIG. 3 for the start of a new stacking operation, with the surface “BS” positioned below the forks 182.

[0126] In the specific condition of sheet forwarding without any stacking, the operator lifts the stopping member 82 and the offset stop 111 using the lifting lever 116 and inputs an exclusion command, via the control panel, to the electronic unit 37, with the activation of the compensation mechanism 54 and the delivery motor 157. The starting support remains high, but with the forks 182 in the retracted configuration, below the alignment section 34.

[0127] The compensation mechanism 54 lifts the stack support 53 to the extra-stroke position, with the supporting surface “BS” in a condition of tangency with the lower branches 62 of the conveyor belts 52 in correspondence of the rear service opening, while the delivery motor 157 moves the delivery belts 162.

[0128] The incoming sheets, after being deflected downward by the input rollers 51, are guided along the surface “TS” through the sequential action of the active section 95 (also with suction) and of the terminal section 98 of the lower branches 62 of the conveyor belts and by the upper branches of the delivery belts 162, up to the service opening “DTG”.

[0129] Naturally, without departing from the principle of the invention, the actuation forms and construction details of the sheet stacking equipment may be widely varied with respect to what has been described and illustrated by way of non-limiting example, without thereby departing from the scope of the present invention.

[0130] For instance, the accommodating space for the stopping member and for the offset stop can be realized by deflection means other than the intermediate rollers and the deviation rollers.

[0131] In the event that the forwarding without stacking is not required, the structure of the functional block and the path of the conveying belts can be simplified by providing only intermediate rollers and deviation rollers for the formation of the accommodating space. In this variant, the terminal section of the lower branches of the belts will be guided by rear rollers at the level of the upper part of the deviation rollers, without the possibility of forwarding sheets for transfer.

[0132] According to a variant, the sheet thickness control utilizes an equivalent structure where the torsion springs 127 are omitted, and the sensing action of sensing rollers 84 on sheets 32 is performed solely by the force of the torsion springs 136 or different springs acting on the common shaft 133.

[0133] In a further variant, the intermediate element for movement transmission between the sensing supports 121 and the common shaft 133 is achieved for example via a single rocker arm, featuring angular adjustment capability on the common shaft and a rounded terminal that cooperates with the upper part 124 of the corresponding sensing support 134.

Examples

Embodiment Construction

[0028]With reference to FIGS. 1 and 2, a sheet stacking equipment, indicated as 31, receives paper sheets 32 at the front from external apparatus along a direction “F”. The stacked sheets are sent, as a stack or pack 33, through an output gate “OG” at the rear to an external processing apparatus by means of a conveyor belt “CB”.

[0029]The stacking equipment 31 is of the type indicated as 21 in the aforementioned patent EP 4 363 234, hereinafter “Patent”, which is incorporated herein by reference.

[0030]In summary, the stacking equipment 31 includes, at the front, an alignment section 34, at the rear a stacking and delivery section 36, and comprises an electronic control unit 37, a push-button panel 38, a control panel “CP”, a compressed-air generator 39 and sensor elements (not shown) arranged along the sheet path.

[0031]The alignment section 34, similar to the section 31 of the Patent, aligns the sheets 32 on a respective receiving surface and forwards them toward the stacking and del...

Claims

1. An equipment for stacking sheets comprising suction conveyor belts, a stack support configured to receive sheets in a vertically stacked arrangement, input rollers configured to feed sheets to be stacked, an electronic control unit, a stopping member, and a functional support block supporting the stopping member, the lower branches are arranged above the stack support and are motor-driven to convey incoming sheets by suction along a transport surface, and the functional support block is movable in a longitudinal direction to position the stopping member at a distance from the input rollers as a function of a length of the sheets, such that sheets stopped by the stopping member are deposited on the stack support or on previously stacked sheets, wherein the equipment further comprises:deviation means associated with the lower branches and supported by the functional support block, the deviation means being configured to form an accommodating space above the transport surface, upstream of and adjacent to the stopping member;wherein the stopping member is arranged within the accommodating space and has a cross-section projecting below the transport surface to stop the sheets and define a vertical alignment surface of a stack; andthe cross-section of the stopping member has a continuous profile configured to act as a stop for a leading edge of the stacking sheets.

2. The equipment of claim 1, wherein:the deviation means comprises a plurality of intermediate rollers and a plurality of deviation rollers rotatably mounted on the functional block;the intermediate rollers and the deviation rollers guide the lower branches of the conveyor belts;the equipment further comprises a plurality of lower front rollers, wherein the lower front rollers and the intermediate rollers guide an active section of the lower branches along the transport surface for dragging the sheets; andsaid deviation rollers are arranged above the intermediate rollers to guide a deviated section of the lower branches, thereby forming the accommodating space downstream of the intermediate rollers.

3. The equipment of claim 2, further comprising:a plurality of lower rear rollers configured to guide a rear portion of the lower branches of the conveyor belts, a plurality of deviation rollers and a plurality of realignment rollers rotatably mounted on the functional block;wherein the realignment rollers and the deviation rollers together guide the lower branches of the conveyor belts, and the rear rollers return a terminal section of the lower branches to the transport surface in alignment with the active section.

4. The equipment of claim 1,wherein the intermediate rollers comprise pulleys protruding from a common shaft, and the functional block supports the stopping member upstream of the common shaft, said functional block comprising side members of support for the common shaft and a transverse profile having a substantially “L”-shaped section; andwherein said transverse profile includes longitudinal extensions at the sides of the pulleys acting as guides for the leading edges of the incoming sheets up to the cross-section of the stopping member.

5. The equipment of claim 4, further comprising:a compensation mechanism for adjusting a height of the stack support; anda sensing device, said sensing device being mounted on the functional block to sense a stack height relative to a reference surface and comprising:a plurality of sensing rollers with sensing supports interposed between the lower branches of the conveyor belts upstream of the accommodating space, each sensing roller having individual displacement capability;spring means configured for applying a tensioning action to the sensing supports so as to enable sensing of sensing areas of the sheets adjacent to the stopping member for a lifting from the stacking sheet according to the thicknesses of the sheets; andmeans for providing stack height information to the electronic control unit in response to the lifting of the sensing rollers,wherein said transverse profile defines windows between the longitudinal extensions, andwherein the sensing rollers protrude with their lower sectors through said windows from the lower surface of said profile.

6. The equipment of claim 1, further comprising an offset stop and an offset actuator, the offset stop being mounted in the accommodating space and having a continuous profile cross-section arranged behind the stopping member with respect to a direction of dragging of the sheets; wherein the stopping member is liftable by the offset actuator to allow the sheets to stop against the offset stop to define an offset stacking surface shifted from the vertical alignment surface.

7. The equipment of claim 1, further comprising a sensing device and a compensation mechanism for adjusting a height of the stack support, the sensing device comprising:a plurality of sensing rollers interposed between the lower branches of the conveyor belts and configured for individual movement;a plurality of sensing supports rotatably supporting the sensing rollers and biased by a plurality of springs;a common shaft having a plurality of intermediate supports and counter rollers arranged above the sensing rollers; andspring means for applying a tensioning action from the counter rollers onto the sensing supports via the common shaft;wherein the sensing device provides information to the electronic control unit for the compensation mechanism in response to rotation of the common shaft determined by a maximum lifting height of the sensing rollers.

8. The equipment of claim 7, wherein a descent of the stack support for each incoming sheet is determined by a reference value selectively set according to a thickness of the sheets and by additive or subtractive correction values, resulting in a corresponding change in a compression degree of the stack.

9. The equipment of claim 1, further comprising a software control for height compensation of the stack support, wherein:the equipment defines a fixed reference "machine zero" level for stacking the sheets,the "machine zero" level corresponds to the transport surface, andthe sensing device is configured to be calibrated by a calibration tool to set an initial reading value for the "machine zero" level.

10. The equipment of claim 9, wherein a descent of the stack support for each incoming sheet is determined by a reference value selectively set according to a thickness of the sheets and by additive or subtractive correction values, resulting in a corresponding change in a compression degree of the stack; and wherein a current descent value is monitored to obtain an average value, and said average value is used to update the reference value.

11. The equipment of claim 1,wherein the input rollers comprise a driving roller, and the conveyor belts are tensioned between the driving roller, rear rollers, and front rollers including lower front rollers for the lower branches;wherein the incoming sheets emerging from the input rollers are deviated toward the stack support by inclined sections of the belts between the driving roller and the lower front rollers, the equipment further comprising spring leaves and a compressed air nozzle; andwherein:the spring leaves are interposed between the inclined sections of the belts; andthe compressed air nozzle is configured to provide a compressed air jet on the inclined sections of the belts to facilitate detachment of the incoming sheets from the belts upon release from the input rollers.

12. The equipment of claim 1, further comprising at least one duct and suction fans, wherein the at least one duct is arranged transversely above the lower branches of the conveyor belts and defines guide areas for said lower branches, wherein the conveyor belts comprise longitudinal perforations, and wherein the at least one duct supports said suction fans and comprises openings at the guide areas to provide suction on the incoming sheets for adhesive dragging by the conveyor belts.

13. The equipment of claim 12, comprising lateral guides, wherein the number of ducts depends on the length of the sheets to be stacked, the functional block and the duct or the ducts are slidably coupled and lockable with said lateral guides allowing the stopping member to be positioned at a distance from the input rollers depending on the length of the sheets to be stacked that exceeds said length.

14. The equipment of claim 1, further comprising a compensation mechanism operatively connected with the stack support for a vertical shifting maintaining constant the height of a last sheet of the stack from the transport surface, and an output gate, and wherein said stack support comprises a plurality of elongated delivery belts and support members for said delivery belts, wherein said elongated delivery belts have respective upper branches which are guided by the support members and are of support for the sheets in stacking, said stack support is vertically shiftable by the compensation mechanism to a delivery position in correspondence of the output gate, while the delivery belts are longitudinally shiftable by a delivering motor for forwarding the stacked sheets trough the output gate to following treatments, wherein said compensation mechanism is provided for moving the stack support to a high extra-stroke position where the upper branches of the delivery belts are tangent to the transport surface and to a rear service opening and said delivering motor is actuatable for a condition of sheet forwarding without any stacking by the lower branches of the conveyor belts and by the upper branches of the delivery belts.

15. The equipment of claim 1, wherein the stack support comprises a plurality of delivery belts and delivery belt supports, said equipment further comprising a multi-fork support, a fork actuation mechanism, and a startup compensation mechanism;wherein the multi-fork support comprises a plurality of forks insertable between the delivery belt supports;the electronic control unit is configured to control the fork actuation mechanism and the startup compensation mechanism during a startup phase to position the forks above and between upper branches of the delivery belts to provide a temporary support for a forming stack.

16. The equipment of claim 15,wherein the startup compensation mechanism is configured to adjust a height of the multi-fork support according to the stacked sheets until a predetermined stack height is reached where the forks are positioned below the delivery belts; andwherein, upon reaching the predetermined stack height, the electronic control unit causes the fork actuation mechanism to extract the forks and restores control of the compensation mechanism to adjust the height of the stack support for sheets stacked beyond the predetermined stack height.

17. An equipment for stacking sheets, comprising:a conveying system configured to advance sheets along a transport surface;a stack support positioned below the transport surface and configured to receive the sheets in a stacked arrangement;a stopping element configured to intercept a leading edge of the sheets to define an alignment position; anda support structure supporting the stop element and movable relative to the conveying system to adjust a position of the stop element as a function of a sheet dimension;wherein the conveying system comprises at least one suction-based conveyor defining said transport surface, and the equipment further comprises a deviation arrangement associated with the conveying system and configured to locally deviate at least a portion of the conveying system to form a recess in the transport surface in a region of the stop element; andwherein the stop element extends at least partially into the recess and projects below the transport surface to intercept the sheets; and the stop element defines a continuous stopping profile for engaging the leading edge of the sheets.

18. The equipment of claim 17, further comprising a sensing device and a common shaft coupled to the sensing elements,wherein the sensing device is configured to detect a height of a stack on the stack support and comprises a plurality of sensing elements positioned upstream of the stop element and configured for independent displacement, said sensing elements are biased by one or more springs toward the sheets, andwherein the common shaft is coupled to the sensing elements such that a movement of the common shaft corresponds to a maximum displacement among the sensing elements.

19. The equipment of claim 18, wherein the stack support comprises a plurality of delivery belts configured to support and discharge the stacked sheets, further comprising a temporary support comprising a plurality of movable forks insertable between the delivery belts, an actuator configured to move the forks between an active position supporting a forming stack and a retracted position and a control unit configured to control the forks during a startup phase of stacking.

20. An equipment for stacking sheets, comprising:a plurality of suction conveyor belts having respective lower branches defining a transport surface;a stack support positioned below the transport surface;input rollers configured to feed sheets to the conveyor belts;a stop element; anda movable support block supporting the stop element;wherein the lower branches are configured to convey sheets by suction along the transport surface; the support block is movable in a longitudinal direction to adjust a distance between the stop element and the input rollers as a function of a sheet length;wherein the equipment further comprises: a plurality of rollers carried by the support block and configured to guide the lower branches along a deviated path so as to form a recess above the transport surface adjacent to the stop element; andwherein: the stop element is positioned within the recess and has a portion projecting below the transport surface to stop the sheets and define a vertical alignment surface.

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