Centering unit for a tank treatment plant and a tank treatment plant

Abstract

Centering unit for a container handling system, in particular for a device for layering a palletizer, with at least one length-adjustable railing for laterally limiting a machine table and / or for laterally centering containers, in particular for forming a container layer, wherein the length-adjustable railing has at least one fixed centering rod for laterally holding and / or centering the containers and a centering rod movable relative to the fixed centering rod for length adjustment of the length-adjustable railing and in particular for extending the area for holding and / or centering the containers.

Description

[0001] The invention relates to a centering unit for a container treatment plant and to a container treatment plant, in particular a device for layering a palletizer.

[0002] Centering units for the lateral guidance and limitation of containers, packages and especially groups of packages are known in various designs from the prior art and are used in particular in devices for forming layers of several packages on a machine table for subsequent palletizing of the formed package layer.

[0003] In known devices, a lateral guide rail is typically provided on both sides for lateral guidance and limitation. The spacing between these rails and their length in the transport direction of the containers or packages are adapted to the dimensions of the package layer to be formed. These dimensions result, among other things, from the size of the pallet, the size of the containers, the number of containers in a package, and the desired layer pattern, which may well contain gaps.

[0004] Changing any of these dimensions may require adjusting the length of the guide rail in the transport direction. Depending on the format, this is done using different extension pieces, typically attached to one end of the guide rail. When changing product types or formats, the operator must therefore manually install or remove the extension pieces as needed, which is time-consuming and leads to extended downtime. Furthermore, there is a risk that the operator will install the wrong extension piece or make an error in its alignment, resulting in incorrectly formed layers and ultimately preventing correct palletizing of the containers or packages.

[0005] The invention is therefore based on the objective of creating a centering unit for a container treatment system that enables particularly fast, reliable and error-free adjustment during a changeover of product type and / or format.

[0006] The problem is solved according to the invention by a centering unit according to claim 1 and by a container treatment system according to claim 33. Advantageous embodiments are specified in the dependent claims.

[0007] The centering unit according to the invention for a container handling system, in particular for a device for layering a palletizer, has at least one length-adjustable railing for laterally limiting a machine table, in particular for receiving containers to be palletized, and / or for laterally centering containers, in particular for forming a container layer, wherein the length-adjustable railing has at least one fixed centering rod for laterally holding and / or centering the containers and a centering rod movable relative to the fixed centering rod for length adjustment of the length-adjustable railing and in particular for extending the area for holding and / or centering the containers.

[0008] Furthermore, the invention relates to a container treatment plant and in particular to a device for layering a palletizer with at least one centering unit according to the invention.

[0009] The centering unit according to the invention enables a fully automatic format change in a simple manner, which can be carried out particularly quickly and without the intervention of an operator at the centering unit and as a result of which errors in length setting can also be reliably avoided.

[0010] A centering unit is generally understood to be a component or machine designed to center, precisely align, and / or laterally guide containers placed on it. The containers are preferably moved into a target position at least temporarily, particularly preferably at the end of a centering process, and most preferably throughout their entire time on the centering unit, or held in a target position, so that the containers, now in their respective target positions, can subsequently be further processed and, in particular, palletized. Specifically, the centering unit is designed to simultaneously move a plurality of containers laterally into a target position, such that the containers are arranged in a defined layer pattern. Such a layer pattern is particularly necessary for the subsequent palletizing of the resulting layer.

[0011] According to the invention, the centering unit has a length-adjustable railing designed to laterally delimit a machine table of the centering unit for receiving the containers, at least in the area of ​​the containers and / or in the area of ​​a layer of containers to be formed. Preferably, the railing is designed to laterally support the containers at the edge of a layer of containers and / or to keep them in contact with the respective container. The railing stroke, i.e., the range of length adjustability, can be chosen arbitrarily. In its fully retracted state, the railing preferably has a length of at least 500 mm, more preferably at least 700 mm, very preferably at least 800 mm, and most preferably 820 mm.The railing, when fully extended, preferably has a length of at least 900 mm, particularly preferably at least 1100 mm, very preferably at least 1250 mm and particularly preferably 1280 mm.

[0012] The machine table is preferably designed to directly accommodate containers, and in particular all containers necessary to form a layer of containers. For this purpose, the machine table preferably has a flat surface and / or a horizontal extent and / or a rectangular surface. The machine table can have a surface that is partially open or interrupted, as well as a completely closed surface. Furthermore, it is also conceivable that the surface of the machine table is designed to accommodate the containers via a transport device, in particular a conveyor belt. The length-adjustable railing preferably extends completely above a surface of the machine table. Furthermore, the length-adjustable railing preferably extends parallel to a side edge of the machine table.

[0013] A container for placement on the machine table and / or for lateral support or centering by means of the length-adjustable railing can be a single item, such as a bottle, a can, or any other packaging unit, or a group of such items, in particular a container consisting of several bottles, cans, or the like. The container is preferably intended for use in the food industry and, in particular, for holding a beverage. A beverage can, for example made of aluminum, or a beverage bottle, for example made of plastic, especially PET, or glass, is particularly preferred.

[0014] To adapt the centering unit to changing dimensions, particularly of the container, the bundles formed from the containers, and / or the pallet for subsequent container placement, the railing is designed to be length-adjustable according to the invention. This length adjustability is achieved by providing at least one, and preferably exactly one, centering rod, on which a further centering rod is slidably arranged, so that by moving the slidable centering rod relative to the fixed centering rod, the length of the railing is adjusted. The length-adjustable railing allows the length of the layer centering to be set.

[0015] Although the fixed and movable centering rods can be arranged arbitrarily relative to each other, the two centering rods are preferably at least partially and, more preferably, completely movable within one another. Preferably, one centering rod surrounds the other centering rod on at least two sides, at least in a fully inserted or maximally shortened state. Particularly preferably, the movable centering rod can be inserted into the fixed centering rod and / or between components of the fixed centering rod. Furthermore, the two centering rods are arranged to slide against each other or within each other, although, in principle, any other bearing element, such as ball or roller bearings, is also conceivable.

[0016] Both centering rods can, in principle, be made of any material, for example, a plastic, a fiber-reinforced plastic, a metal, a lightweight material, carbon fiber, or a combination of several of these materials. Preferably, both centering rods are made of the same material.

[0017] The two centering rods preferably each have at least one surface designed for direct contact with a container, and therefore referred to as a container guide surface. Particularly preferably, the stationary centering rod and / or the movable centering rod each have at least two, and more preferably exactly two, container guide surfaces. A container guide surface, and in particular each container guide surface, preferably extends substantially over the entire length of the respective centering rod. Furthermore, all container guide surfaces of one centering rod, and more preferably all container guide surfaces of all centering rods, are arranged in a common plane.

[0018] The container treatment system according to the invention preferably has a palletizer, wherein the centering unit and / or the device for layer formation is particularly preferably arranged directly in front of a palletizer, especially in the transport direction of the containers.

[0019] A preferred embodiment of the centering unit according to the invention provides that the movable centering rod can be fixed relative to the stationary centering rod by means of a locking unit in at least one, preferably several, positions with different length offsets. It is particularly preferred that the locking unit secures the movable centering rod relative to the stationary centering rod by means of a positive and / or force-fit connection and that the locking mechanism can be released manually and / or automatically to allow length adjustment of the railing.

[0020] The locking unit can be designed to be released manually by a user, and in particular by a machine operator, either exclusively or in addition to automatic release. For this purpose, the locking unit preferably includes an operating element, such as a lever or handle, for manual release. Automatic release means that the locking unit is not released directly by an operator, but rather by a technical means. This can be any actuator, any mechanism, and / or any actuating device.

[0021] According to an advantageous embodiment of the centering unit according to the invention, one of the fixed and the movable centering rods has a toothing extending at least partially along its length in the direction of length adjustment, and the other of the fixed and the movable centering rods has a locking unit with a mating toothing corresponding to the toothing for positively locking the two centering rods to one another. The toothing is preferably formed from teeth that are identical to each other and / or arranged at a constant distance from each other. More preferably, the toothing is formed as rectangular teeth and / or each tooth, particularly in one direction of length adjustment, has a rectangular, and especially preferably a square, cross-sectional area.However, any other tooth configuration and / or tooth shape is also conceivable, for example, helical teeth and / or saw teeth. The mating teeth also have at least one tooth, which is preferably positionable for locking in a space between two teeth of the toothing extending along the length in the direction of length adjustment. Particularly preferably, the mating teeth have several teeth, which are most preferably identical in shape and / or arranged at a constant distance from each other.

[0022] Although the number of teeth of the locking unit or the mating teeth can be chosen arbitrarily, it is preferred that it has between one and 25 teeth, particularly preferably between two and 20 teeth, most preferably between three and ten teeth, and most preferably between four and eight teeth. The teeth of the mating teeth can be of any shape, with a rounded tooth shape and, in particular, teeth with a constant curvature and / or a semicircular shape in the area of ​​the front face of the teeth being preferred.

[0023] Furthermore, a preferred embodiment of the centering unit according to the invention is one in which the locking unit is fixed to the movable centering rod. This fixing is preferably achieved by means of a screw connection, with the locking unit being particularly preferably fixed directly to the movable centering rod, especially between two components of the movable centering rod.

[0024] In an advantageous embodiment of the centering unit according to the invention, the toothing extends at least over the length of the stationary centering rod along which the movable centering rod can be displaced relative to the stationary centering rod, and / or the toothing extends over at least 25%, preferably at least 50%, particularly preferably at least 60%, and most preferably at least 75% of the total length of the centering rod. More preferably, however, the toothing does not extend to the end regions of the centering rod and / or only to a region centrally located between two railing brackets of the centering unit. Accordingly, it is preferred that the toothing extends over a maximum of 95%, particularly preferably a maximum of 85%, and most preferably a maximum of 75% of the length of the centering rod.

[0025] It is further preferred that the mating teeth of the locking unit are arranged on a pinion, wherein the pinion is slidably mounted on the centering rod perpendicular to the direction of the length adjustment in order to engage and disengage the mating teeth with the teeth of the other centering rod. The pinion is preferably slidable at least over the length or depth of the teeth, and particularly preferably over at least twice the length or depth of the teeth, to allow complete and reliable release of the teeth from the mating teeth. Generally, it is preferred that the locking unit has a spring-loaded pressure piece for unlocking.

[0026] Furthermore, a preferred design of the centering unit according to the invention includes a pinion of the locking unit that is pre-tensioned to a locked position, in particular with the mating teeth of the pinion engaging with the teeth of the centering rod, by means of at least one spring element. Particularly preferably, the locking unit has a spring assembly for pre-tensioning to a locked position, in particular with the mating teeth of the pinion engaging with the teeth of the centering rod, wherein the spring assembly has at least two spring elements, which are preferably arranged parallel to each other. It is also particularly preferred that the spring assembly is formed from exactly two spring elements, which, however, need not be in contact with each other, so that the spring assembly can also be a single functional unit.Both, and especially all, spring elements of the locking unit are preferably of the same length, the same strength, and particularly preferably identical to each other. While the spring element can, in principle, be of any shape, it is preferably formed in one piece and / or from a single material. Particularly preferably, the spring element is formed from a coil spring.

[0027] Although the locking unit can be arranged arbitrarily on any one of the centering rods, it is preferred that the locking unit is fixed to the centering rod by means of a support plate and / or has an actuating plate, wherein the at least one spring element or the spring assembly is preferably arranged between the support plate and the actuating plate. Furthermore, it is preferred that the locking unit is designed such that pressing the actuating plate on one side of the fixed centering rod in the direction of the movable centering rod releases the locking mechanism or disengages the mating teeth of the pinion from the teeth of the fixed centering rod.Furthermore, an embodiment of the centering unit is conceivable in which the locking unit has at least one and preferably two spring bolts, wherein the actuating plate is fixed and, in particular, screwed to one end of the spring bolt(s) and the pinion is fixed and, in particular, screwed to the other end of the spring bolt(s). It is particularly advantageous if the two spring bolts of the locking unit are parallel to each other and / or each surrounded by a spring element, especially in the area between the support plate and the actuating plate.

[0028] The two ends of a spring element are preferably supported at one end on the actuating plate, and in particular on an inner surface of the actuating plate, and at the other end on a surface of the support plate surrounding the spring bolt. Furthermore, the two spring bolts are preferably arranged to project through or penetrate the support plate, for which purpose the support plate particularly preferably has corresponding bores substantially adapted to the diameter of the spring bolts. It is also preferred that the respective spring element is formed as a coil spring whose diameter is not greater than 200%, particularly preferably not greater than 150%, most preferably not greater than 125%, and particularly preferably not greater than 115% of the diameter of the spring bolt.It is also preferred that the spring bolt has a constant diameter and / or a smooth cylindrical surface, at least in the area surrounded by the spring element.

[0029] An advantageous embodiment of the centering unit according to the invention provides that the support plate is arranged on one side of the stationary centering rod and the pinion interacts with the opposite side of the stationary centering rod, and in particular with the rack or toothing. To ensure particularly reliable guidance of the locking unit, a sliding guide element is preferably arranged on the locking unit, especially on the support plate, or on the movable centering rod in the area of ​​the locking unit. This sliding guide element guides the two centering rods slidably within a guide slot of the stationary centering rod and / or secures them against movement perpendicular to the direction of length adjustment. The sliding guide element can also be formed integrally with a component of the locking unit, and in particular with the support plate.

[0030] The guide slot of the stationary centering rod preferably has a constant width over its entire length. The sliding guide element also preferably has at least one section and preferably at least two sections, which are arranged within the guide slot in a substantially form-fitting and / or sliding manner. Each section of the sliding guide element preferably extends along the direction of length adjustment at least twice, particularly preferably at least three times, and most preferably at least four times the width of the section, the sliding guide element, or the guide slot. Furthermore, a preferred embodiment of the centering unit includes a section of the sliding guide element or a sliding guide element on each side of the locking unit, and in particular the pinion of the locking unit, within the guide slot.

[0031] A preferred embodiment of a centering unit provides that at least two railing brackets, particularly for mounting the centering unit on a tank treatment system and / or on the machine table, are fixed to the stationary centering rod, and that a component of the longitudinally adjustable railing, in particular the locking unit, is arranged between the two railing brackets such that the locking unit comes into contact with one of the railing brackets at the end of the movable centering rod's travel relative to the stationary centering rod, thus forming an end stop. Furthermore, preferably, the railing brackets and the locking unit are designed such that they can come into planar contact with each other.This is done in particular in the area of ​​a flat side surface of the respective railing bracket and / or with a side surface of a component of the locking unit, in particular a side surface of the actuating plate and / or the support plate.

[0032] Although the two centering rods can, in principle, be moved arbitrarily, it is preferred that a motorized linear unit be provided for moving the movable centering rod relative to the stationary centering rod, and that this unit is preferably capable of engaging with the movable centering rod. It is preferred that the motorized linear unit is not continuously engaged with the movable centering rod, or that the movable centering rod, which is temporarily connected to the motorized linear unit, can be disengaged so that the motorized linear unit can be moved independently of the movable centering rod. Particularly preferred is that the two centering rods are permanently connected to each other by means of the locking unit when the motorized linear unit is disengaged.

[0033] Preferably, the linear unit for motorized drive comprises an electric cylinder or an electric linear motor. A length-adjustable railing particularly preferably comprises exactly one linear unit. Also particularly preferably, a linear unit comprises a single electric cylinder or a single electric linear motor. However, it is also conceivable that the linear unit is adjusted in another way, for example, pneumatically and / or hydraulically. In particular, the linear unit can have one, and especially a single, hydraulic and / or pneumatic cylinder. The electric cylinder or the electric linear motor preferably has a maximum stroke of between 200 mm and 1000 mm, particularly preferably between 250 mm and 750 mm, most preferably between 400 mm and 600 mm, and most preferably 500 mm.

[0034] To ensure reliable linear guidance, it is preferred that the linear unit has at least one, and preferably two, parallel linear guide rails, along which a bridge is preferably guided linearly displaceably by means of the electric cylinder or the electric linear motor, wherein the bridge is most preferably designed to interact with the displaceable centering rod, in particular by means of the locking unit. The linear unit and / or the at least one linear guide rail is preferably designed to absorb forces and / or to absorb tilting moments during linear guidance.Preferably, the at least one linear guide rail extends, and particularly preferably, the two linear guide rails extend over at least 75%, more preferably over at least 85%, and particularly preferably over at least 90% of the length of a base body of the linear unit for receiving the at least one linear guide rail and / or the length of the linear unit.

[0035] Preferably, the bridge is slidably fixed to the respective linear guide rail by means of a guide rail slide. Also preferably, the bridge is essentially formed from a rectangular bar. The bridge preferably extends linearly, particularly preferably at least between the two linear guide rails, and most preferably at one end beyond the guide rail and / or beyond the upper edge of the linear unit. At the other end, the bridge preferably terminates in the region of the linear guide rail. The bridge is preferably configured to interact with the movable centering rod in the region of an end of the bridge projecting beyond the linear unit.

[0036] Furthermore, it is preferred that the linear unit has a base body, wherein the electric cylinder or the electric linear motor is arranged on one side of the base body and the bridge and / or the at least one linear guide rail is arranged on the other side of the base body. The base body is preferably formed in one or more pieces as an L-profile. It is also preferred that the electric cylinder or the electric linear motor is arranged within the angled section of the L-profile, in particular screwed to the base body. Each linear guide rail is also preferably screwed to the respective surface of the base body.

[0037] In a preferred embodiment of the centering unit according to the invention, the electric cylinder or the electric linear motor is connected to the bridge by means of a coupling piece, wherein the coupling piece is preferably arranged within a coupling slot projecting through the base body and wherein the coupling slot of the base body is preferably arranged parallel to the linear guide rails and / or between the linear guide rails.

[0038] To enable the linear unit to move the centering rod, the linear unit preferably acts on the movable centering rod by means of the bridge and can, in particular, be engaged such that the movable centering rod can be moved relative to the stationary centering rod by means of the linear unit. A centering pin is preferably arranged on the bridge, particularly at an end projecting beyond the linear unit, and can be positioned within a receiving bore in the movable centering rod, preferably in the locking unit and especially preferably in the actuating plate. The receiving bore preferably receives the centering pin in a substantially positive-locking manner and / or has a diameter substantially identical to that of the centering pin.Preferably, the centering pin has a rounded and / or tapered tip to facilitate insertion into the receiving bore. Although the centering pin can generally have a round cross-section and / or a cylindrical outer surface, it is preferred that parts of the outer surface of the centering pin are flattened.

[0039] According to an advantageous embodiment of the centering unit according to the invention, the length-adjustable railing, particularly via the linear unit, can be displaced in a direction perpendicular to the direction of length adjustment of the centering rods by means of a railing centering device. For this purpose, the railing centering device preferably comprises a centering drive, which most preferably acts laterally on the length-adjustable railing and / or on the linear unit via a displaceable rack. The railing centering device preferably acts in the direction of the center of the machine table. The centering drive also preferably comprises a gear and / or a shaft. Furthermore, the centering drive preferably acts directly on the rack to displace the length-adjustable railing in a direction perpendicular to the direction of length adjustment.The device for railing centering is preferably provided to close gaps within a formed layer and / or to prevent individual containers from being pushed laterally out of a layer.

[0040] Furthermore, it is preferred that the device for railing centering has two racks, each connected to the length-adjustable railing and, in particular, to the linear unit, which are preferably adjusted simultaneously by means of the centering drive to enable angular displacement parallel to an edge of the machine table. Particularly preferably, both racks are identical in design and / or arranged parallel to each other.

[0041] The locking unit of a further development of the centering unit can be configured to unlock by the insertion of the centering bolt into the receiving bore and the subsequent pressing of a pressure surface on the surface of the bridge against a contact surface of the actuating plate of the locking unit. The contact surface preferably surrounds the receiving bore on the surface of the locking unit and / or is located on the surface of the actuating plate and / or on a surface of the locking unit facing away from the centering rod. The pressure surface preferably surrounds the centering bolt on the surface of the bridge and / or is located on a surface of the linear unit facing the locking unit.During unlocking, the actuating plate is pressed against the tension of the spring pack by moving the linear unit and in particular the bridge using the railing centering device, so that the pinion with the mating teeth comes out of engagement with the teeth of the centering rod.

[0042] It is also preferred that, following unlocking, the railing's length can be adjusted, and in particular the movable centering rod can be shifted relative to the fixed centering rod by means of the linear unit, due to the centering pin located within the receiving bore. During the railing's length adjustment, the locking unit is preferably fully unlocked, in particular by pressing the bridge of the linear unit against the actuating plate of the locking unit. Likewise, the electric cylinder or the electric linear motor of the linear unit is only operated once the locking unit has been completely unlocked. A corresponding control unit can be provided for this purpose, which can also control any other functions and / or process steps of the centering unit.

[0043] To determine the position of the linear unit relative to the movable centering rod and, in particular, to the locking unit, a position detection sensor is arranged on the bridge in a preferred embodiment of the centering unit according to the invention. Preferably, the position detection sensor comprises a light barrier and / or a laser distance sensor directed towards the locking unit, wherein a shutter, detectable by means of the position detection sensor, is particularly preferably arranged on the locking unit. Most preferably, the shutter is arranged on the locking unit and, in particular, on the support plate, has a reflective surface, and / or is adjustable, in particular slidably, and / or fixed by means of screws.Furthermore, it is preferred that the aperture has a passage opening which is arranged and / or formed such that, when a light beam from the position detection sensor penetrates it, the centering pin of the linear unit is positioned exactly opposite the receiving bore of the locking unit. It is also preferably the case that the electric cylinder or the electric linear motor has a means for position sensing or position detection in order to determine the current position and, if necessary, transmit it to a control unit.

[0044] A preferred embodiment of the container treatment system according to the invention provides that two centering units are arranged on two opposite sides of the container treatment system, and in particular on a machine table, wherein the length-adjustable railings of the two centering units are preferably arranged parallel to each other. The two centering units are preferably identical to each other or mirror-symmetrical to each other.

[0045] An exemplary embodiment of a device for layering a palletizer with a centering unit according to the invention is explained in more detail below with reference to the drawings. The figures show: Fig. 1 a section of the area of ​​two centering units of a device for layering a palletizer, Fig. 2 a perspective view of a length-adjustable railing of one of the two centering units, Fig. 3 one opposite Fig. 2. Perspective view of the length-adjustable railing of the centering unit, rotated by 180°. Fig. 4 a top view of the length-adjustable railing in a fully retracted state, Fig. 5 a sectional view of the length-adjustable railing in a fully extended state, Fig. 6 an enlarged sectional view of a locking unit of the length-adjustable railing, Fig. 7 a perspective view of a linear unit of the centering unit, Fig. 8 one opposite Fig. 7. Perspective view of the linear unit of the centering unit, rotated by 180°. Fig. 9 an enlarged view of the area of ​​a bridge of the linear unit, Fig. 10 a view of a section of the centering unit in the area of ​​a device for railing centering, Fig. 11 a greatly enlarged view of the area of ​​interaction between the locking unit and the bridge, and Fig. 12 another, greatly enlarged view of the area of ​​interaction between the locking unit and the bridge with a position detection sensor.

[0046] One in Fig. 1. A device for layer formation 2 of a palletizer, shown in sections, has a centering unit 1 arranged laterally on a machine table 4, with a length-adjustable railing 4 for lateral limitation of the machine table 4 and for lateral centering of containers from containers when forming a layer for subsequent palletizing.

[0047] The in the Fig. Figures 2-5, showing a length-adjustable railing 3, have a fixed centering rod 5, which is fixed to the machine table 4 or its frame by means of two spaced-apart railing brackets 18. A length-adjustable centering rod 6 is fixed to the fixed centering rod 5. Both centering rods 5 and 6 each have two container guide surfaces 39 running parallel to each other and extending over the entire length of the respective centering rod 5 or 6. These surfaces are designed to be positioned laterally against the containers and thus define the later boundaries of the machine table 4. All four container guide surfaces 39 of a length-adjustable railing 3 extend within a common plane.

[0048] To lock the movable centering rod 6 relative to the fixed centering rod 5, a locking unit 7 is provided (see Fig. 5, Fig. 6 , Fig. 11 and Fig. 12). For this purpose, the locking unit 7 has a pinion 10 with a mating tooth 9 which can engage with a tooth 8 of the stationary centering rod 5. To prevent the locking unit 7 from unlocking automatically, the pinion 10 with the mating tooth 9 is biased in the direction of the tooth 8 by means of a spring assembly 12. The spring assembly 12 consists of two identical spring elements 11 in the form of coil springs, each spring element 11 surrounding a spring bolt 15 of the locking unit 7.

[0049] The spring bolts 15 are each fixed at one end to the pinion 10 and at the other end to an actuating plate 14, whereby pressing the actuating plate 14 opens the locking unit 7, i.e., disengages the mating teeth 9 from the teeth 8. A support plate 13 is provided to fix the locking unit 7 to the movable centering rod 6, wherein the spring bolts 15 extend through the support plate 13 and the spring elements 11 of the spring assembly 12 are arranged between the support plate 13 and the actuating plate 14, surrounding the spring bolts 15.

[0050] In order to enable secure guidance of the locking unit 7, which is firmly connected to the movable centering rod 6, on the stationary centering rod 5, a sliding guide element 16 is arranged on the locking unit 7, which is guided in a form-fitting manner on both sides of the pinion 10 in a guide slot 17 in the stationary centering rod 5.

[0051] In order to be able to move the movable centering rod 6 relative to the fixed centering rod 5 in a motorized and reliable manner, a [missing information] is required in the Fig.A linear unit 19 is provided as shown in Figures 7-9. The linear unit 19 has an L-shaped base body 23, on one side of which an electric cylinder 20 is mounted as a linear motor for adjustment. On the opposite side of the base body 23, two linear guide rails 21 are arranged parallel to each other. A bridge 22 is attached to each of these linear guide rails 21 by means of a guide rail slide 38, and the bridge 22 extends beyond the base body 23 at one end. The bridge 22 is connected to the electric cylinder 20 via a coupling piece 24, the coupling piece 24 extending through a coupling slot 25 in the base body 23.

[0052] At the end of the bridge 22 that extends beyond the base body 23 at one end, a centering pin 26 is arranged. When the bridge 22 is positioned appropriately, the electric cylinder 20 of the linear unit 19 allows the centering pin 26 to be inserted into a receiving bore 27 of the actuating plate 14 of the locking unit 7. This connects the movable centering rod 6 to the linear unit 19 via the locking unit 7. When the bridge 22 is moved towards the center of the machine table 4, a pressure surface 31 of the bridge 22 surrounding the centering pin 26 presses against a contact surface 32 surrounding the receiving bore 27, thus unlocking the locking unit 7.

[0053] To enable such movement of the linear unit 19, it is connected to a railing centering device 28. The railing centering device 28 has an electric centering drive 29 which, on both sides, drives a gear via a shaft at the output side. This gear moves a rack 30 connected to the linear unit 19, thus enabling the linear unit to be moved laterally.

[0054] To ensure reliable insertion of the centering bolt 26 into the receiving bore 27, a photoelectric sensor 33 is arranged on the bridge 22 as a position detection sensor. A shutter 34 with a reflective surface 35 is positioned on the locking unit 7 such that a first signal is generated when the centering bolt 26 approaches the receiving bore 27. In the precise position for this signal, the shutter 34 has a passage opening 37 in the area of ​​the light beam from the position detection sensor 33, generating a different, second signal. To adjust the correct positioning of the shutter 34, it is fixed to the locking unit 7 by means of screws 36. Reference symbol list 1 centering unit 2 Device for layer formation 3 Length-adjustable railings 4 machine table 5 fixed centering rods 6 adjustable centering rods 7 Locking unit 8 gear teeth 9 Counter-gearing 10 sprockets 11 Spring element 12 spring pack 13 Support plate 14 Actuator plate 15 spring bolts 16 Sliding guide element 17 guide slots 18 railing brackets 19 linear units 20 electric cylinders 21 Linear guide rail 22 Bridge 23 Basic shapes 24 coupling piece 25 coupling slots 26 centering bolts 27 Intake bore 28 Device for railing centering 29 Centering drive 30 Rack and pinion 31 printing area 32 Plant area 33 Position detection sensor 34 aperture 35 reflective surface 36 screw 37 Passage opening 38 guide rail carriages 39 Container guide surface

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