WO2005087640A1

WO2005087640A1 - Method and device for stacking flat mail items

Info

Publication number: WO2005087640A1
Application number: PCT/EP2005/002422
Authority: WO
Inventors: Armin Zimmermann; Holger Schererz; Thomas Fröhlich
Original assignee: Siemens Aktiengesellschaft
Priority date: 2004-03-13
Filing date: 2005-03-08
Publication date: 2005-09-22
Also published as: US20070176348A1; DE502005004187D1; EP1725486A1; JP2007529384A; CN1930070A; DE102004012379A1; DE102004012379B4; EP1725486B1

Abstract

According to the invention, in each stacking run, in which the mail items are stacked vertically, a mail item to be stacked is propelled against a stop wall at a stacking point by means of a stacking roll that can be displaced away from the stack in opposition to a spring force and that is driven in a controlled manner in a starting-braking mode. The mass of each mail item to be stacked is determined prior to stacking. Stack pressures are measured when the stacking roll engages with the mail item to be stacked using a measuring device that is positioned in the vicinity of the stacking roll on the transport plane of the mail or on the stacking roll. If the stack pressure is too high, the stack is accordingly transported away from the stacking point. In a preceding test phase, the target values for the stack pressures and the braking curves of the stacking roll up until the mail items have reached the stop are defined and stored based on statistical analyses in accordance with the mass of the respective mail items to be stacked. The speed of the respective mail item is reduced by the stacking roll according to the braking curve that has been assigned to the determined mass of the mail item.

Description

Method and device for stacking flat items

The invention relates to a method and a device for stacking flat mail items. The consignments are transported one after the other in stack receptacles and stacked upright in these. In each stack receptacle, a consignment to be stacked is conveyed to a stop wall by means of a stacking roller. The consignment to be stacked hits the consignment that is already stacked at an acute angle. A controlled underfloor belt and a stack support which is releasably coupled or separately driven are moved away from the stacking point as the stack grows. Each consignment to be stacked must be routed in such a way that it reaches the stop wall and its front and bottom edges are aligned with the goods that have already been stacked. When moving away the partial stack according to DE 102 23 349 AI from the stacking point to the place for the consignment to be stacked, the selected travel path is smaller than the determined thickness of the consignment to be stacked. For this reduction in the travel distance compared to the measured thickness value, an average compressibility of the partial stack is assumed. If the actual value deviates considerably from the assumed value due to incompressible mail items, there is nevertheless a disproportionate increase in the stack pressure, since the stacking force can only be measured after the mail item has hit the stack receptacle and then corrected. U.U. the consignment does not reach the stop wall of the stack holder. The spring effect of the stack of items cannot be taken into account.

If, in order to avoid this effect, as in EP 0743269 B1, the partial stack is moved away from the stacking point by the full determined amount of the thickness + safety margin (measurement inaccuracies), the supporting function of the stacking roller is temporarily abandoned. Then it comes especially with large format broadcasts to tilt the stack, which dramatically affects the quality of the stack. If the consignment in the stack receptacle has reached the stop wall, the stacking forces are determined by stacking force measurement in the area of the stacking roller and the stacking force is set in a readjustment process by moving the underfloor belt in an area which is defined by threshold values for the permissible stacking force range. In addition, after the inaccurate positioning of the consignment in the stack receptacle, force is applied to the consignment by the constantly rotating stacking roller in the direction of transport, which can lead to damage, warping and twisting of the stacked goods.

The invention has for its object to provide a method and a device for stacking flat mail items in a standing position in a Stapelauf, with which mail items with very different dimensions and masses are gently stacked aligned with their front and bottom edges.

According to the invention the object is achieved by the features of claims 1 and 6.

In each stack receptacle in which the mail items are stacked in a standing position, a mail item to be stacked is sent to a stack at a stacking point by means of a stacking roller which can be moved away from the stack against a spring force and which is driven in a controlled manner in the start / brake operation. Transported billboard. A controlled underfloor belt and a stack support that is detachably coupled or separately driven are removed from the

Stacking place moved away. The consignment to be stacked hits the previous consignment that has already been stacked at an acute angle. Before stacking, the mass of each item to be stacked is determined. Stacking pressures are measured with a measuring device arranged in the area of the stacking roll on the letter run level or on the stacking roll itself when the stacking roll has the amount to be stacked. has detected. In an upstream test phase, the setpoints for the stack pressures and the braking curves of the stacking roller until the mail items have reached the stop are determined and stored on the basis of statistical analyzes, depending on the mass of the mail items to be stacked. In accordance with the braking curve assigned to the determined mass of mail, the respective mail is then braked by the stacking roller. As a result of the displaceable stacking roller, the stacking force, regardless of the properties of the stack that is already in the stack holder, never exceeds a value that prevents correct stacking without losing the supporting function of the stack. Regardless of their dimensions and masses, the mail items are braked in a defined manner in order to reduce the kinetic energy so that an optimally aligned stack results. By braking the stacking rollers, the application of force to the mailing in the direction of transport is reduced after the respective mailing has been positioned, thereby preventing damage or warping of the stacked mailings.

Advantageous embodiments of the invention are set out in the subclaims. So it is advantageous if the thickness of the consignment to be stacked is determined and for the stacking of a consignment the underfloor belt and / or the stack support away from the stacking point by the measured thickness of this consignment plus or minus a correction value for setting the consignment mass assigned and stored to the determined consignment mass

Target stack pressure and then at an actual stack pressure measured on the stack roller and deviating from the target stack force are moved to this consignment to maintain the target stack pressure. The target batch pressure is dependent on the mass and thickness of the mail item currently to be stacked and the spectrum and the properties (mass, thickness, compressibility) of the mail items previously stacked. It is also advantageous if the mass of the consignments is determined indirectly by measuring the dimensions of the consignment, calculating the volume therefrom and multiplying it by a fixed mass factor per volume.

During the braking process of the stacking roll, the braking curve can advantageously be designed such that the peripheral speed of the stacking roll at the point in time when the shipment has reached the stop wall is inversely related to the mass of the shipment and that the stacking roll is subsequently brought to a standstill when the subsequent one The shipment is so far away that there is enough time to accelerate the stacking roll back to the nominal speed before the shipment has reached it.

If the subsequent shipment falls below a certain distance from the stack pickup, e.g. If the time to accelerate from 0 to the nominal speed is not sufficient, it is advantageous to accelerate the peripheral speed of the stacking roll immediately after the stacking of the respective shipment to the nominal speed of the means of transport.

The invention is then based on the drawing in one

Exemplary embodiment explained.

1 shows a schematic top view of a device for stacking with a consignment to be stacked,

2 shows a representation of the speed curve of the stacking roller over time, 3 shows a representation of the course of the stacking force over time and over the position of the stacking roll.

As shown in FIG. 1, the stacking roll 1 is arranged to be displaceable in the direction of the mailing stack 18 to be generated. This is realized via a rocker 2. A linear arrangement is also possible. The stacking roller 1 is positioned in the rest position by means of a spring 3 with a defined spring characteristic in the direction of a stop 4. This stop 4 is adjustable, which enables calibration of the sensor. Depending on the thickness, incoming mail items 19 cause the stacking roller 1 to be displaced to a greater or lesser extent. The size of the displacement produces an increase in the reaction force of the spring 3 and thus the stack pressure. With an appropriate design of the spring characteristic, it is ensured that the stack pressure only increases to such an extent that all items reach the stop wall 15 safely. A further stop 5 prevents the stacking roll 1 from overshoot when retracting, in particular, thicker mail items 19.

In order to avoid unwanted vibrations, a damping element 6 is attached to the rocker 2. As can be seen in FIG. 1, the mail items 19 are transported one after the other and clamped between the stacking belts 11, 12 in a standing position in the direction of the stacking roll 1. So that the stacking can take place, the transport belt 12 directed in the direction of the partial stack 18 is deflected in front of the stacking device via a deflection roller 13, whereas the other stacking belt 11 is deflected only in front of the stacking roller 1 via a deflection roller 10. The transmission 19 is due to their kinetic ^"energy and by frictional forces at the stack belt 11 along the stacking roller 1 to the located there sta- pelstütze 14, if no further broadcast yet are stacked, or piled against the last engaged transmission of the partial stapeis 18 passed at an acute angle and then held between this and the stacking roll 1.

The stacking roll 1 has a direct drive 16. The maximum peripheral speed of the stacking roll 1 corresponds to the transport speed of the items 19 to be stacked during the stacking phase.

The stack pressure that forms between the first mailing of the stack 18 and the stacking roll 1 must be so great that each mailing safely reaches between the stacking roll 1 and the stacking support 14 or the uppermost mailing of the stack 18 up to the stop wall 15, where the kinetic residual energy of the broadcast 19 is reduced. The stacking roll 1 is displaced more or less by incoming consignments 19 depending on the consignment thickness and the stack compressibility, so that the stacking pressure does not become too high when stacking a consignment 19. The stack pressure which arises slightly in accordance with the spring characteristic of the spring 3 is measured and adjusted to the desired value (readjusted) by moving a stack support 14 and / or an underfloor belt 17 and thus the partial stack 18.

A suitable sensor for detecting the stack pressure as the reaction force of the stacking roller 1 is provided for measuring the stack pressure. The sensor can be a displacement transducer 7 in the area of the rocker arm 2, which uses the spring characteristic to determine the stack pressure (FIG. 1) and feeds it to the controller 9. Another possibility is a force sensor connected in series with the spring 3. Because of the very different consignment properties (e.g. dimension, mass, surface quality), the stacking roll 1 is also in

Dependency of these significant properties of the mail items and the position of the incoming mail item is defined in a rotationally accelerated and braked manner. As a result, heavy mail items 19 are braked so that they are not compressed too much. Because the stacking roll 1 does not run continuously, mail items 19 with sensitive surfaces, such as plastic, are not damaged. They also go away not, which can result in the subsequent mail items 19 not being able to enter the stacking device. The speed control of the stacking roll 1 takes place according to FIG. 2 as a function of the mail mass. If the consignment 19 is transported in the direction of the stacking roll 1, the stacking roll 1 is accelerated in time, regardless of the mail item mass, so that the transport speed is reached on the circumference before the mailing 19 comes into contact with the stacking roll 1. If the consignment 19 is securely engaged by the stacking roll 1, it is braked. The

Delay, i.e. the braking ramp is selected higher for consignments 19 with a large mass than for thin, light consignments 19. If the consignment 19 has arrived at the stop wall 15 of the stack receptacle, after a short delay in order to prevent rebound effects, the stacking roller 1 is used to avoid the Stress on the uppermost stacked mail item is completely braked over a longer period of time by the rotating stacking roll 1, provided that no further mail item 19 is fed into the stack receptacle at a specified distance. If another consignment 19 follows at a minimum distance, the stacking roll 1 is not braked completely, but continues to run at the speed reached at that point in time until the following consignment 19 has been transported to such an extent that the stacking roll 1 must be accelerated again in order to be on time to be at transport speed again for the arrival of the mail item 19 on the stacking roll 1. The stack pressure is controlled by moving the stack support 14 and / or the underfloor belt 17. When the mail item 19 to be stacked has reached a defined position, the advance of the underfloor belt 17 / stack support 14 is calculated and started. The feed has ended before the mail item 19 has reached the stacking roll 1.

The feed is calculated from the thickness of the mail item 19 and the stacking pressure which is to be set when the mail item 19 is engaged on the stacking roll 1 and is thus deflected by the mail item 19. Via the spring characteristic the support of the stacking roll 1, the path is calculated by which the underfloor belt 17 must move the stack of mail items 18 away from the stacking roll 1 in order to change the stacking pressure accordingly. If the stack pressure is to be increased, then the feed results from the consignment thickness, minus the distance that must be moved to the desired stack pressure in order to increase it. If the stack pressure is to be reduced, the feed results from the consignment thickness, plus the distance that has to be moved to the desired stack pressure in order to reduce it.

2 and 3 show the relationships when the stack pressure is increased. As can be seen from the stack pressure curves, an average stack pressure F _tl , which is previously determined experimentally, is assumed at the time tl. If a consignment is registered in front of the stacking roll 1, the underfloor belt 17 / stacking support 14 moving back from the stacking point sets the stacking pressure F _tll suitable for this stacking 19 due to its mass for secure stacking. Then the mail item 19 deflects the stacking roll 1 and the stacking pressure rises briefly to the limited value F _t2 . The stack of mail items 18 is then moved back through the underfloor belt 17 to such an extent that the stack pressure F _t ι is established again.

Claims

claims

1. A method for stacking flat mail items, wherein - the mail items (19) are successively transported in stack receptacles by means of transport (10, 11, 12, 13) and stacked upright in these, - in each stack receptacle, a single consignment (19) to be stacked is conveyed to a stop wall (15) by means of a stacking roller (1) which can be moved away from the stack (18) against a spring force and which is driven in a controlled manner in the start / brake operation, and a controlled underfloor belt ( 17) and a detachably coupled or separately driven stack support (14) with growing stack (18) are moved away from the stacking point, - the mail item (19) to be stacked hits the previous, already stacked mail item at an acute angle, - before the stacking, the mass of each consignment (19) to be stacked is determined, - with one in the area of the stacking roll (1) on the letter plane or on the stacking roll (1) itself arranged measuring device, stack pressures are measured when the stack roll (1) has detected the consignment (19) to be stacked, - in an upstream test phase on the basis of statistical analyzes, the target values for the stack pressures and the braking curves of the stack roll (1) until the mail items (19) have reached the stop wall (15), depending on the mass of the mail items (19) to be stacked, are determined and stored, the respective mail item (19) according to the braking curve associated with the determined mail item mass from the stacking roll (1) is braked.

, The method according to claim 1, wherein the thickness of the consignment (19) to be stacked is determined and for the stacking of a consignment 19) the underfloor belt (17) and / or the stack support (14) away from the stacking point by the measured thickness of this consignment ( 19) plus or minus a correction value for setting the target stack pressure assigned and stored to the determined mail item mass as a function of the mass and the thickness of the mail item to be stacked (19) and of the spectrum and the properties (mass, thickness, compressibility) of the previously stacked items Shipments and then at an actual stack pressure measured on the stacking roller (1) and deviating from the target stack pressure are moved to this mailpiece (19) in order to maintain the target stack pressure.

Method according to claim 1, wherein to determine the mass of the mail items (19), their dimensions are measured, the volume is calculated therefrom and multiplied by a fixed mass factor per volume.

4. The method according to claim 1, wherein the braking curve of the stacking roller (1) is such that its peripheral speed at the time when the consignment (19) has reached the stop wall (15) is opposite to the mass of the consignment (19) and wherein the stacking roll (1) is then brought to a standstill when the subsequent consignment is so far removed that the time is sufficient to accelerate the stacking roll (1) to nominal speed before the consignment has reached it.

5. The method according to claim 1, wherein the peripheral speed of the stacking roller (1) is accelerated immediately after the stacking of the respective shipment (19) to the nominal speed of the means of transport (10,11,12,13) when the subsequent shipment of a predetermined distance the stack intake falls below.

6. Device for stacking flat mail items, with - a transport means (10, 11, 12, 13) for transporting the mail items (19) one after the other in stack receptacles, in which they are stacked standing upright, - in each stack receptacle at a stacking point, Stacking rollers (1) which can be displaced away from the stack (18) against a spring force and which are driven in a controlled manner in the start-braking operation and which convey the fertilizers (19) to a stop wall (15), and with a controlled underfloor belt (17 ) and a stack support (14) detachably coupled or separately driven, which are moved away from the stacking point as the stack (18) grows, - a measuring device which determines the mass of each mail item (19) to be stacked, - one in the area of the stacking roll (1) measuring device (7) arranged on the letter run level or on the stacking roll (1) itself for measuring the stacking forces, wherein0 in a preceding test phase on the basis of statistical The setpoints for the stacking pressures and the braking curves of the stacking roll (1) until the mailings (1) have reached the stop wall (15) are determined and stored depending on the mass of the mailings (19) to be stacked in each case and the respective mail item (19) can be braked from the stacking roller (1) in accordance with the braking curve assigned to the mail item mass.