EP4069504B1 - Baling press and method for operating the baling press - Google Patents

Description

The present invention relates to a baling press with a press housing surrounding a press chamber, a press plate which can be moved in the press housing and which can be driven by hydraulic cylinders. The invention also relates to a method for operating the baler.

Out of DE 100 29 439 A1 discloses a baling press with a housing surrounding a baling chamber and a press ram inserted therein, the drive of which is formed by four hydraulic cylinders arranged laterally next to the press housing. The hydraulic cylinder drive is uncontrolled. The cylinders are used as pressure cylinders. This means: When the press ram moves down, hydraulic oil is applied to the piston surface of the cylinder, and when it moves up, the piston ring surface. Although a high pressing pressure can be generated in a baling press with pressure cylinders, this design has the disadvantage that the pressure cylinders basically protrude beyond the baling press due to the system. This is disadvantageous for rooms with a low overall height.

Out of U.S. 2013/0270730 A1 there is known a compression molding apparatus for melting a resin material, in which fibers are supplied to the molten resin, and then resin and fibers are pressed into a mold. The compression molding apparatus includes lower and upper molds and at least three compression hydraulic cylinders attached to the upper and lower molds. Position sensors are provided to detect the distance between the upper and lower moulds. And according to their information the Compression hydraulic cylinders can be controlled individually. The compression molding device is neither intended nor suitable for compressing material in the form of balls.

Out of U.S. 5,868,067 A a baler for compacting fibers and other compactable materials such as refuse is known. The baler consists of a primary hydraulic cylinder and a faster-acting secondary hydraulic cylinder, both of which are attached to a press plate designed to compact the material. The second compression means works faster than the first compression means and exerts a tamping movement on the material to be pressed, which has been pre-compacted by the first compression means. Both compression means have a common hydraulic system and a solenoid valve. Hydraulic oil is supplied to the two hydraulic cylinders and the ramming strokes are activated by means of a control provided for this purpose. The disadvantage of this system is that although two cylinder pairs with a total of four cylinders are provided, the two secondary cylinders only serve to increase the lifting speed in the unloaded state. The material compression is carried out exclusively with the primary cylinders.

Out of DE 195 28 813 A1 a device for compensating tilting moments on a ram of a press is known. The device comprises at least one pair of identical hydraulic cylinders, the pistons of which are each connected to the ram. The hydraulic cylinders are synchronous cylinders (also called synchronous cylinders), which have a piston rod on both sides of the piston surface. The volume of the inflowing and outflowing hydraulic oil is therefore always the same. The cylinder therefore moves in and out at the same speed. The chamber of each hydraulic cylinder arranged above the piston is connected to the chamber of the respective other hydraulic cylinder of the pair arranged below the piston via a respective connecting line. It's over DE 195 28 813A1 known device is able to detect and compensate for an inclined position of the ram, but such ram presses have no pressing chamber and are unsuitable as baling presses.

Out of U.S. 5,570,630 A a baler with two double-acting hydraulic cylinders is known. The hydraulic cylinders are connected to each other via a bridge construction and two pressure plates attached to it. In order to control the angularity of the platen as it moves downwards and hence during compaction, two electrical switches are provided which are activated by a pin whenever the bridge structure connecting the hydraulic cylinders is moved from its normally horizontal position position in an inclined position. The disadvantage of the control is that the cylinders can only be controlled roughly and fine control is not possible.

Out of AU001991082616A1 a press for wool with a frame and a press plate that can be moved into a press chamber is known. In order to hold the compressed wool in its pressed position after pressing, wool holding elements are provided in the form of pins engaging laterally in the pressed bale, which are inserted into the wool ball from the sides after compaction and before the pressing plate is moved upwards. The pins that engage laterally in the pressing chamber thus serve as hold-down devices for the material to be compacted and prevent it from expanding when the pressing plate returns.

Out of U.S. 3,851,577 A discloses a baling press for compressing waste, for example cardboard boxes, with a compression chamber and a hydraulic cylinder mounted on a compression plate above the compression chamber. To reduce the overall height of the baler for shipping, the cylinder can be lowered down into the housing. However, the conversion is time-consuming and expensive. A further disadvantage of a system with a hydraulic cylinder arranged above the bale chamber is the high overall height associated therewith. Baling presses with such a structure are therefore unsuitable for rooms with a low overall height.

From the document DE 20 2015 102 601 U1 is a baler for compacting loose material such as cardboard boxes known. Such baling presses are used in supermarkets, among other things, to compress the cardboard boxes, cardboard and other wrappings of sales goods that are placed loosely on sales shelves or removed from them, in order to minimize the resulting volume of residues to be disposed of. The pressed cardboard boxes or the like can also be strapped with wires or plastic straps directly in a press shaft of a press housing. To compress the cardboard boxes and the like, a press plate is moved downwards with two hydraulic cylinders arranged on top of the press shaft. This requires a large overall height of the baler. In this prior art, the arrangement of the hydraulic cylinders above a press housing requires a large room height in order to be able to set up the baler in a building protected from the weather.

The document DE 10 2005 037 147 A1 shows a baler with a press housing, which surrounds a bale chamber, with a power drive consisting of four hydraulic cylinders, a press plate can be moved in the press chamber. Two hydraulic cylinders each work together as a master-slave cylinder pair. Furthermore, the hydraulic cylinders can also be arranged on the side of the press housing in order to reduce the overall height of the baling press. The operation of a baler with master-slave hydraulic cylinders requires considerable technical effort, in particular special and therefore expensive hydraulic cylinders.

The U.S. 10,471,673 B2 discloses a baling press with a press shield that can be moved in a press housing and is driven by hydraulic cylinders. The hydraulic cylinders arranged in the press housing act in groups on an additional intermediate plate and the press shield.

The DE 10 2005 037 147 A1 discloses a baling press according to the preamble of claim 1 with a press plate which can be moved in a press housing and which is driven by hydraulic cylinders. The hydraulic cylinders are arranged in pairs on two opposite sides outside of a bale chamber (2). The hydraulic cylinders are controlled according to the master-slave principle.

The DE 10 2013 014 discloses a baling press with a press shield that can be moved in a press housing and is driven by hydraulic cylinders. Three hydraulic cylinders are arranged linearly in a row. In this case, only one hydraulic cylinder can drive the pressing plate against a pressing direction.

The object of the present invention is therefore to specify a baling press that has a low overall height and a simplified structural design. Furthermore, a corresponding method for operating such a baling press is to be specified.

These tasks are solved by a baling press with the features of patent claim 1 and by a method with the features of patent claim 8 .

The core idea of the invention is that in a baling press which, as explained above, has a press housing with a pressing chamber, a pressing plate and hydraulic cylinders for driving it, a total of four hydraulic cylinders are provided are arranged in pairs on one side of the press plate, the hydraulic cylinders of each pair of cylinders being press pressure-dependent in each case selectively individually or jointly controllable by means of a control device.

By arranging the hydraulic cylinders on the side of the press housing, the overall height of the baling press is kept small. This is particularly the case when the baler is designed in such a way that the hydraulic cylinders are not used as pressure cylinders but as pull cylinders. In this context, a pressure cylinder is understood to mean a cylinder in which hydraulic oil is applied to the piston surface during the pressing process. A pull cylinder is understood to mean a cylinder in which hydraulic oil is applied to the piston ring surface during the pressing process.

A baler with pull cylinders has the advantage that the hydraulic cylinders do not protrude beyond the bale chamber or the press plate. In the case of two balers with the same overall height, one of which compresses the material to be pressed with pull cylinders and the other with pressure cylinders, the pull cylinder baler can therefore have a higher and therefore larger baling chamber than a pressure cylinder baler. The baling press according to the invention with traction cylinders is therefore particularly well suited for rooms with a low overall height.

For this purpose, the hydraulic cylinders acting on the press shield are preferably designed in such a way that, when the press shield is moved to its uppermost position, they practically do not protrude upwards over the press shield. In particular, for this purpose the hydraulic cylinders are arranged in pairs on the left and right opposite one another on two sides of the usually rectangular press plate. In the lower area of the baler, a lower transverse yoke is preferably provided, to which the cylinders are attached.

The control device is designed to apply hydraulic oil to the various hydraulic cylinders of the baling press in the desired manner, i.e. to lower the press plate to compress material to be pressed, such as cardboard boxes or the like, and to also raise the hydraulic cylinders in the opposite direction in a targeted manner of the press shield. The control device is designed in such a way that either only one or both hydraulic cylinders of each cylinder pair, which are arranged adjacent on one side of the press plate, are controlled. This offers the advantage that when the baling chamber of the baling press is almost empty or only easy-to-compact material is filled in, only one hydraulic cylinder on each side of the pressing plate is activated. Since hydraulic oil is only applied to two hydraulic cylinders in this phase, the required volume for driving the then only two driven hydraulic cylinders can be made available more quickly with an existing pump for the hydraulic oil than with four hydraulic cylinders, which results in faster movement of the press plate. The same also applies to a return movement of the pressing plate, which requires little force and for which only one cylinder of each cylinder pair is expediently controlled.

The piston rod of the cylinder that is not activated in each case is taken along by the cylinder that is activated in each case next to it. For this purpose, the two hydraulic cylinders arranged on one side of the press plate are mechanically coupled to one another, so that moving the piston rod of one controlled hydraulic cylinder up or down also moves the piston rod of the other cylinder.

However, if greater forces are required to move the press shield, particularly during the last phase of a press stroke of the press shield, for example in the last third to last fifth on the way down in the press chamber, this can be detected by a sensor in the control device, for example in that the pressure in the controlled hydraulic cylinders increases and the piston rods of the hydraulic cylinders only move very slowly or not at all. The control device can then switch over as a function of the pressing pressure in such a way that pressurized hydraulic oil is now also fed to the two previously unloaded hydraulic cylinders via further corresponding hydraulic lines in order to double the pressing force.

The hydraulic control device is preferably an electronic unit, such as a PLC control.

The selective activation of either only one hydraulic cylinder or both hydraulic cylinders on each side makes it possible, with the same performance of a hydraulic oil pump assigned to the press, to operate the press much more effectively with faster movement of the pressing plate with low power requirements and with a high pressing force when compressing the material to be pressed to reach.

A further advantage of the invention is that the lateral arrangement of the hydraulic cylinders means that the baling press can also be set up in rooms with low ceilings and can also be transported through low doors or gates.

Advantageous configurations of the invention are the subject matter of subclaims.

In particular, the hydraulic cylinders can be activated in such a way that if initially only one cylinder is activated on each side, this occurs crosswise, for example the left rear and right front cylinders or alternatively the left front and right rear cylinders. In this way, a more even application of force to the press plate by the hydraulic cylinder can be achieved in order to prevent the press plate from tilting.

According to a further development, a hydraulic main switching valve and a hydraulic pressure switching valve are provided for the actuation of the hydraulic cylinders, which can be controlled by the hydraulic control unit. The direction of movement of the hydraulic cylinders is basically determined by the main switching valve, i.e. raising or lowering of the press plate, depending on the direction in which the hydraulic cylinders are loaded with hydraulic oil. The pressure switching valve also regulates whether only one hydraulic cylinder or both hydraulic cylinders of the cylinder pair are pressurized with hydraulic oil on each side.

The hydraulic cylinders are preferably each connected to one another with an upper transverse yoke and/or a lower yoke. These yokes are then each arranged above or below the press housing. In order to allow mobility of the hydraulic cylinders relative to these yokes, spherical bearings and shafts can be provided at the connection points of cylinders and yokes.

A guide is preferably provided in the press housing for the movable press plate. For example, triangular, prismatic guide rails can be arranged on the pressing plate in cross-section, which interact with corresponding guide profiles on the inner surfaces of the pressing chamber. This counteracts tilting of the pressing plate when pressing material to be pressed.

Especially when the baling chamber is filled unevenly, the pressing plate can tilt due to different resistances of the material to be pressed, ie tilts towards its own principal plane. In view of this, the invention proposes that the pressing plate be assigned a position sensor which detects an inclined position of the pressing plate and from which position signals can be transmitted to the hydraulic control unit. In this way, the control device and the position sensor can be used to determine if the press plate is in an inclined position that exceeds a predefinable limit value. The control device can then control the hydraulic cylinders in such a way that the tilting is compensated, i.e., for example, hydraulic oil is applied to only one hydraulic cylinder on a leading side of the pressure plate and hydraulic oil is applied to both hydraulic cylinders on the opposite, lagging side of the pressure plate in order to move the pressure plate level again.

To operate the baling press according to the invention, the hydraulic cylinders of each pair of cylinders are selectively activated individually or together depending on the pressing pressure. This means that either only one or both of the two hydraulic cylinders, which are arranged on one side of the press plate and are mechanically coupled to one another, are controlled to raise and lower the press plate. When the power requirement is low, only one hydraulic cylinder of each pair of cylinders is charged with hydraulic oil in order to quickly move the press plate down or raise it again, and when there is a high power requirement, i.e. when compressing the material to be pressed, both hydraulic cylinders of each pair of cylinders are then charged with hydraulic oil.

Figur 1

eine Ballenpresse in einer ersten perspektivischen Ansicht,

Figur 2

die Ballenpresse in Draufsicht,

Figur 3

die Ballenpresse in einer zweiten perspektivischen Ansicht,

Figur 4

ein Paar von Hydraulikzylindern der Ballenpresse in einer Seitenansicht und

Figur 5

ein Schaltbild der Hydraulikanlage der Ballenpresse, zusammen mit einigen weiteren Teilen der Ballenpresse.

An exemplary embodiment of the invention is explained below with reference to a drawing. The figures of the drawing show, each in a schematic representation:

figure 1

a baler in a first perspective view,

figure 2

the baler in top view,

figure 3

the baler in a second perspective view,

figure 4

a pair of hydraulic cylinders of the baler in a side view and

figure 5

a schematic of the hydraulic system of the baler, together with some other parts of the baler.

In the following description of the figures, the same parts in the various figures are always provided with the same reference numbers, so that not all reference numbers have to be explained again for each figure.

Furthermore, the figures of the drawing, their description and the claims contain numerous features in combination. It is clear to a person skilled in the art that these features can also be considered individually or that they can be combined to form further combinations that are not described in detail here. The invention also expressly extends to those embodiments which are not given by combinations of features from explicit back references of the claims, with which the disclosed features of the invention can be combined with one another as desired, insofar as this is technically meaningful.

The exemplary embodiments illustrated in the figures are therefore only of a descriptive nature and are not intended to limit the invention in any way.

The terms used below: "upper", "above", "lower", "left" or "right" refer to the arrangement of the components of the baler in the operating mode shown in the drawing.

figure 1 shows a baler 1 with a press housing 3, for example made of steel, and a press chamber 2, whose chamber door 9 forming a front side of the press housing 3 is open here. The chamber door 9 is provided with a filling opening 10 in its upper part. With the chamber door 9 closed, parts to be pressed, such as cardboard boxes, cardboard, packaging or empty plastic beverage bottles, which are found in supermarkets, for example, can be filled into the pressing chamber 2 through the filling opening 10 .

The material to be pressed is then moved and compacted in direction R1 by a pressing plate 4, which is shown here in a raised, upper position, preferably strapped with wire or plastic straps and then removed as a pressed bale with the chamber door 9 open. This significantly reduces the volume of materials to be disposed of and the bales are easy to store and transport.

The pressing plate 4 is moved by means of four hydraulic cylinders 5, 6, 7, 8 arranged in pairs on the side of the press housing 3, with in figure 1 only the two hydraulic cylinders 5, 6 are fully visible. The two further hydraulic cylinders 7, 8 are arranged on the side of the press housing 3 facing away from the viewer and are largely covered. The Hydraulic cylinders 5, 6, 7, 8 each have a piston 23 and a piston rod 22. The pistons 23 each have a piston surface 25 on one side and a piston ring surface 24 surrounding the piston rod 22 on the other side. Because the hydraulic cylinders 5, 6, 7, 8 are arranged laterally on the press housing 3, the height of the baler 1 is advantageously low. The overall height is also particularly low due to the fact that the hydraulic cylinders 5, 6, 7, 8 are designed as pulling cylinders, which are acted upon with hydraulic fluid on their piston ring surface 24 during their movement in the pressing direction R1.

The side edges of the pressing plate 4 are connected here to four vertical, prismatic guide rails 13 which project upwards beyond the pressing plate 4 and which interact with corresponding guide profiles 14 on the two lateral inner surfaces of the press housing 3 .

The two hydraulic cylinders 5, 6 on one side and the two further hydraulic cylinders 7, 8 on the other side are at the top by means of an upper transverse yoke 11 and at the bottom by means of a lower yoke 17 running parallel to the upper transverse yoke below the baling chamber 2 within each cylinder pair and cylinder pair connected to form a pair of cylinders. In addition, the upper transverse yoke 11 is connected to the upper side of the press plate 4 .

In figure 2 the baler 1 is shown in plan view. The four hydraulic cylinders 5 , 6 , 7 , 8 here engage laterally in pairs opposite one another via the upper transverse yoke 11 on the pressing plate 4 . The hydraulic cylinders 5, 6 on one side and the hydraulic cylinders 7, 8 on the other side are connected to one another by means of the upper transverse yoke 11. A mechanical coupling of the hydraulic cylinders 5, 6, 7, 8 is achieved by the transverse yoke 11.

Furthermore, the press shield 4 has four vertical, prismatic guide rails 13 on its lateral edges, which interact with the corresponding guide profiles 14 on the inner surface of the press housing 3 . These guide rails 13 and guide profiles 14 counteract a tilting of the pressing plate 4, since when the pressing plate 4 tilts on the leading side, there is increased frictional resistance of the guide rails 13 there in the guiding profile 14, so that the pressing plate 4 is braked on this side and quasi automatically aligns horizontally again.

The four hydraulic cylinders 5 , 6 , 7 , 8 are each connected to the upper transverse yoke 11 via a pivot bearing 16 .

down in figure 2 lies the closed chamber door 9.

In figure 3 is the baler 1 in a perspective view obliquely from the front with an opposite of figure 1 changed viewing direction shown. The press shield 4 of the baler 1 is in the raised position here. Furthermore, it can be seen that two hydraulic cylinders 5, 6 or 7, 8 arranged on one side of the press plate 4 are mechanically coupled to one another. This coupling takes place via the joint bearings 16 which act on the upper transverse yoke 11 here. Furthermore, the guide rails 13 on the edge of the press plate 4 are also connected to one another here parallel to the transverse yoke 11 , which serves to increase the mechanical stability of the press plate 4 .

In figure 4 are two adjacent hydraulic cylinders 5, 6 of the in figure 1 visible pair of cylinders shown in a side view, which are connected to each other here via the upper transverse yoke 11 and the lower yoke 17. The joint bearings 16 are used for the articulated connection of these components to one another. The outer piston rod ends of the cylinders 5, 6 with the upper transverse yoke 11 are at the top by means of the joint bearings 16 there and the cylinder housings of the cylinders 5, 6 with the joint bearings 16 there with the lower yoke 17 are at the bottom tied together. On the other side of the press housing, not shown here, there is a mirror-symmetrical arrangement with the other two hydraulic cylinders 7, 8 there.

This in figure 4 The lower right joint bearing 16 is an enlargement of the detail Z on the right figure 4 shown again.

In figure 5 1 is a hydraulic circuit diagram of the hydraulic system of the baler together with some other parts of the baler to illustrate the hydraulic components and the hydraulic connections of the various components of the baler 1 shown in solid lines. The cuts AA and BB are each laterally in figure 5 shown schematically.

A total of four hydraulic cylinders 5, 6, 7, 8 act on the press shield 4 of the baler 1 via the upper transverse yoke 11 in order to move it downwards with the press shield 4 in the pressing direction R1 or to raise it in the opposite direction to the pressing direction R1.

A position sensor 18, such as an inclination angle sensor, is arranged on the press plate 4 or, as shown here, on the transverse yoke 11 in order to prevent the press plate 4 from tilting out of its position register horizontal position. As indicated by the dashed line, the position sensor 18 is connected to a control device 12 .

The control device 12 in turn is connected via a control line to a main switching valve 19 and can control the hydraulic cylinders 5, 6, 7, 8 via this.

The hydraulic system also includes a pressure changeover valve 20, which is connected upstream of the main switching valve 19 and switches depending on the hydraulic pressure

In operating phases of the baler with a low power requirement, only the two hydraulic cylinders 5, 8 are controlled in such a way that these hydraulic cylinders 5, 8 move the press plate 4 up or down. The respective other hydraulic cylinder 6, 7 of each pair of cylinders is carried along by the respectively controlled hydraulic cylinder 5, 8 due to their mechanical coupling. The entrained hydraulic cylinders 6, 7 are filled with hydraulic oil from a hydraulic oil tank of the hydraulic system without pressure via a tank line with a check valve arranged therein due to the resulting vacuum in the replenishment process.

If there is a greater need for power, which can be determined by an increase in hydraulic oil pressure, in particular when compressing the material to be pressed, the pressure switchover valve 20 is activated in such a way that the other two hydraulic cylinders 6, 7 are also activated and charged with pressurized hydraulic oil, in order then to work with all four hydraulic cylinders 5, 6, 7, 8 to produce a higher, almost twice the pressing force of the pressing plate 4.

When the power requirement is low, the control device 12 activates two hydraulic cylinders crosswise, i.e. only the hydraulic cylinders 5, 8 or the hydraulic cylinders 6, 7, for example located in the baling chamber, the other two hydraulic cylinders 6, 7 and 5, 8 are also activated on both sides. This means that a hydraulic oil pump then supplies the hydraulic oil to all four hydraulic cylinders 5, 6, 7, 8.

Should the pressing plate 4 tilt during the pressing process, which is detected by the position sensor 18 and transmitted to the control device 12, the hydraulic cylinders 5, 6, 7, 8 can be controlled accordingly by the control device 12 and the main switching valve 19 in order to compensate for this tilting .

A directional switching valve 21 is used to switch the direction of movement of the hydraulic cylinders 5, 6, 7, 8 and thus the pressing plate 4.

A typical baler 1 operating cycle is as follows:
Initially, the baler 1 is in a filling state, with the hydraulic cylinders 5, 6, 7, 8 in the raised position, ie in the position they are in when the pressing plate 4 is in its uppermost position for the purpose of filling the baling chamber 2 located.

Parts of the material to be pressed are filled manually or mechanically through the opened chamber door 9 into the pressing chamber 2 until a predeterminable fill level is reached, and the chamber door 9 is closed.

From this position, the hydraulic cylinders 5, 8 or 6, 7 are filled with hydraulic oil by the pump P in the annular space of the cylinders to compress the material to be pressed, which is located below the pressing plate 4. Thus, from each pair of cylinders 5, 6 and 7, 8 mounted laterally on the press 1, only one cylinder 5 and 8 is filled with oil. If hydraulic oil is now filled into the annular space of the cylinders 5, 8 connected to the pump P, then the piston rods of these cylinders 5, 8 and thus the press plate 4 connected to them move downwards.

The cylinders 5, 6 and 7, 8 of a pair of cylinders are each mechanically connected to one another. So if the piston rod of one cylinder 5, 8 moves down in the pressing direction R1, then the piston rod of the other cylinder 6, 7 also moves down in the pressing direction R1 - by mechanical power transmission via the mechanical connection. The entrained hydraulic cylinders 6, 7 are filled with hydraulic oil from a hydraulic oil tank of the hydraulic system without pressure via a tank line with a check valve arranged therein due to the resulting vacuum in the replenishment process.

The cylinders 5, 8 to be filled with hydraulic oil when the power requirement is low and the pressing pressures are low are arranged crosswise, ie the cylinder 5 is hydraulically connected to the cylinder 8. The cylinders 5, 8 are under pressure in the operating state in which the pressure switching valve 20 has not yet switched over to the filling of all cylinders 5, 6, 7, 8 standing hydraulic oil. The pressing plate 4 moves down relatively quickly in the vast majority of the pressing cycle, without building up much pressure.

The pressure for pressing the material to be pressed is only required in the lower part, approximately the lower third to fifth, of the pressing chamber 2 when the pressing chamber 2 is already reasonably full. The hydraulic oil flow is then released not only into the hydraulic cylinders 5 and 8 via the pressure switching valve 20, but also the respective adjacent hydraulic cylinders 6 and 7 are supplied with pressurized hydraulic oil.

At the time when such a changeover of the pressure switching valve 20 takes place, the pressing plate 4 is already in the lower part of the pressing chamber 2. The cylinder pairs 5, 6 and 7, 8 on each side of the pressing plate 4 are connected via the transverse yoke 11, which is located above the pressing plate 4, connected to each other.

The guide rails 13 are located on the pressing shield 4 and work together with the compatible, pronounced guide profiles 14 in the side walls of the pressing chamber 2 . If now z. If, for example, a different pressure builds up under the right-hand part of the pressing plate 4 than under the left-hand part, then the pressing plate 4 is pulled at an angle because the cylinders 5, 6 or 7, 8 on one side receive less oil than the cylinders 7, 8 or 5, 6 the other side.

The guide rails 13, which interact with the guide profiles 14 in the side wall and which extend upwards from the press plate 4, ensure that when a pair of cylinders 5, 6 or 7, 8 advances and the press plate 4 tilts as a result, the guide rails 13 and guide profiles 14 on the leading side cause greater friction with each other than the guide rails 13 and guide profiles 14 on the trailing side of the pressing plate 4. This makes the initially leading guide through the guide rails 13 and guide profiles 14 stiff, so that the hydraulic oil prefers to flow into the other pair of cylinders 7, 8 or 5, 6 and leads to a compensation of the advance of one side of the pressing plate 4, which acts counter to the inclined position.

However, if the inclination of the pressing plate 4 becomes too great, then this is detected by means of the position sensor 18 attached to the transverse yoke 11 above the pressing plate 4 , for example an angle sensor, and reported to the control device 12 . If the inclined position exceeds a specific, specifiable limit value, then the control device 12 Direction switching valve 21 of the hydraulic system is set to return and the pressing plate 4 moves back to its upper starting position. At the latest at the end of the retraction, the pressing plate 4 aligns itself horizontally again by running against an upper stop, after which it can then be moved back down from there for a new pressing step.

At the end of the last pressing step, i. H., when a pressed bale has been pressed, the press plate 4 is in its lower position. In this position of the press shield 4, the press bale can be tied in a manner known per se. From this position, after switching over the direction switching valve 21, the pressing plate 4 is moved back upwards again. In this case, too, only two cylinders 5, 8 are acted upon by hydraulic oil in the return, so that due to the small volume of hydraulic oil required for this, the pressing plate 4 can be returned relatively quickly in the upward direction. The twin cylinder 6, 7 connected to the cylinder 5, 8 that is acted upon in each case is not moved upwards by the pressurized hydraulic oil flowing into its pressure chamber, but is carried along by the respective adjacent hydraulic cylinder 5, 8 due to the mechanical connection and due to the force transmission taking place via it. The hydraulic oil released in the annular space of the hydraulic cylinders 6, 7 runs into the pressureless hydraulic oil tank. For this purpose, the hydraulic cylinders 6, 7 are only connected to the hydraulic oil tank on their bottom side via pure leakage oil lines and can also draw air when the cylinders 5, 8 are extended. The piston space of the entrained hydraulic cylinders 6, 7 therefore never needs to be charged with pressurized hydraulic oil.

After reaching the upper starting position of the pressing plate 4, the chamber door 9 can be opened and the pressed and tied bale can be removed from the pressing chamber 2.

Reference list:

1

baler

2

press chamber

3

press housing

4

press shield

5

hydraulic cylinder

6

hydraulic cylinder

7

hydraulic cylinder

8th

hydraulic cylinder

9

chamber door

10

filling hole

11

crossbar

12

control device

13

guide rail

14

leadership profile

15

Wave

16

pivot bearing

17

subjugation

18

position sensor

19

main switching valve

20

pressure switching valve

21

direction switching valve

22

piston rod

23

Pistons

24

piston ring surface

25

piston area

A-A

cut

B-B

cut

R1

pressing direction

Z

detail (from 3 )

Claims (10)

1. A baler (1) with a baler housing (3) surrounding a bale chamber (2) and with a pressing plate (4) that is movable in the baler housing (3) and which can be driven by hydraulic cylinders (5, 6, 7, 8) arranged in pairs on two opposite sides outside the bale chamber (2),
   characterized in that
   a hydraulic control device (12) is provided, by means of which the hydraulic cylinders (5, 6, 7, 8) of each pair of cylinders (5 and 6, 7 and 8) can each be controlled either selectively individually or jointly, depending on the press pressure.
2. The baler (1) as claimed in claim 1, characterized in that in the case of individual control of a respective hydraulic cylinder (5 or 6, 7 or 8) of each side, the hydraulic cylinders (5 and 8 or 6 and 7) can be controlled crosswise.
3. The baler (1) as claimed in claim 1 or 2, characterized in that for the actuation of the hydraulic cylinders (5, 6, 7, 8) a hydraulic main switching valve (19) and a hydraulic pressure switching valve (20) are provided, which can be controlled by the hydraulic control device (12).
4. The baler (1) as claimed in any one of claims 1 to 3, characterized in that the hydraulic cylinders (5, 6, 7, 8) are each connected to one another by a top-side transverse yoke (11) and/or a bottom-side lower yoke (17).
5. The baler (1) as claimed in any one of claims 1 to 4, characterized in that a guide for the pressing plate (4) is formed in the baler housing (3).
6. The baler (1) as claimed in any one of claims 1 to 5, characterized in that in that the pressing plate (4) is assigned a position sensor (18) which detects an inclined position of the pressing plate (4) and from which position signals can be transmitted to the hydraulic control device (12).
7. The baler (1) as claimed in any one of claims 1 to 6, characterized in that:

   - the hydraulic cylinders (5, 6, 7, 8) are double-acting cylinders which comprise a piston rod (22) and a piston (23) and in which the piston (23) has a piston surface (25) on one side and a piston ring surface (24) surrounding the piston rod (22) on the other side, and

   - the control device (12) is designed in such a way that, during the movement of the pressing plate (4) in the pressing direction (R1), the piston ring surfaces (24) of the pistons (23) are acted upon by a hydraulic fluid, so that the cylinders (5, 5, 7 and 8) act as pulling cylinders.
8. A method for operating a baler (1) with a baler housing (3) surrounding a bale chamber (2) and with a pressing plate (4) that is moveable in a baler housing 3) and which is driven by hydraulic cylinders (5, 6, 7, 8) arranged in pairs on two opposite sides outside the bale chamber (2),
   characterized in that
   the hydraulic cylinders (5, 6, 7, 8) of each pair of cylinders are each controlled either selectively individually or jointly, depending on the press pressure.
9. The method as claimed in claim 8, characterized in that in the case of individual control of a respective hydraulic cylinder (5 or 6, 7 or 8) of each side, the hydraulic cylinders (5 and 8 or 6 and 7) are controlled crosswise.
10. The method as claimed in claim 8 or 9, characterized in that the hydraulic cylinders (5, 6, 7, 8) moving the pressing plate (4) have a piston (23) with a piston surface (25) and a piston ring surface (24) and, when the pressing plate (4) is moved in the pressing direction (R1), are acted upon at their piston ring surface (24) by a hydraulic fluid.

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