Patent Description:
To produce corrugated board, lines are used, to which endless webs of paper are fed. Some of these webs are subjected to a process that produces therein flutes orthogonal to the direction of feed. Alternate smooth and corrugated paper webs are superimposed and glued to one another to form a corrugated board. Each corrugated board comprises at least one web of smooth paper and one web of corrugated paper. The corrugated board web can then be creased and cut into single sheets.

To corrugate the paper webs, machines called "single facers" are used. Each single facer comprises a pair of corrugating rollers meshing with each other and defining a corrugating nip. The web of paper to be corrugated is fed through the nip formed by the two corrugating rollers meshing with each other and suitably heated. As a result of the thermal and mechanical action exerted by the corrugating rollers, the web of paper is permanently deformed, forming a plurality of flutes arranged parallel to each other and one after the other in the direction of feed of the web material. At the outlet of the single facer the web of corrugated paper is hot glued using pressure to a web of smooth paper, also known as "liner".

Examples of single facers of the current art are disclosed in <CIT>, <CIT>, which can be referred to for further details.

Usually, a corrugated board production line is provided with two or more single facers to produce single- or multiple-fluted corrugated board, according to requirements of each production order.

The shape and the dimension of the flutes of the corrugated board can vary according to the job order. Frequently, the orders are relatively small, i.e., the production of a limited amount of corrugated board is required for each order. It is thus necessary to replace the corrugating rollers, even with a certain frequency, to produce corrugated board with the characteristics required for each single order.

In order to simplify replacement of the corrugating rollers, the provision of so-called cartridges, hereinafter indicated as "corrugating units", is known, each comprising a pair of corrugating rollers mounted on heads integral with each other; the corrugating rollers of one corrugating unit mesh with each other and are already mounted on a containing and supporting structure. This enables them to be replaced rapidly.

Plants for moving and replacing corrugating units in a single facer have also been produced. <CIT> discloses a motorized carriage guided by an operator, for moving and transferring corrugating units in a plant.

<CIT> discloses a single facer provided with a lateral magazine. Two corrugating units can be arranged in the lateral magazine, usable alternatively to each other in a single facer that the magazine is placed next to. Translation guides are provided to replace a corrugating unit in use with a corrugating unit standing by in the magazine. The magazine comprises two seats for corrugating units, each of which is provided with a pair of guides. These are selectively aligned with a pair of guides integral with the single facer. A translation mechanism, comprising a motor fixed with respect to the single facer that controls a rack and pinion transmission, translates the single corrugating units along the guides. To translate a corrugating unit from the single facer to the magazine and vice versa, the corresponding guides of the magazine are aligned with the guides integral with the single facer to form a continuous guide system.

This known mechanism is not particularly flexible and has some problems. In particular, the moving mechanism makes it necessary to place the magazine very close to the single facer. Moreover, the corrugating units are transferred by running on guides that are located partly on the magazine and partly in the single facer. Once the corrugating unit has been inserted into the single facer, it must be lifted from the guides and held in an operating position at a greater height than the height of the guides. As the corrugating units are very heavy, and a vertical thrust oriented downward is also applied thereto to glue the web of corrugated paper to a web of smooth paper, actuators capable of generating very high thrusts, typically hydraulic piston-cylinder actuators, are required to maintain the corrugating unit in the correct operating position. Accidental decrease of the pressure of the fluid in the cylinder of the actuator causes emergency shutdown of the single facer.

<CIT> discloses a plant comprising a single facer having a supporting structure adapted to receive a corrugating unit. The corrugating unit comprises a first corrugating roller and a second corrugating roller meshing with each other. The plant further comprises a magazine including a plurality of seats for receiving corrugating units and movable along a guide. Each corrugating unit has wheels and can be moved from the single facer to the magazine and vice-versa. The magazine runs along the single face at a distance therefrom such that each corrugating unit can be transferred from the single facer directly into the magazine and vice-versa using the wheels, each corrugating unit is provided with. A cumbersome retention device is required to lock the corrugating unit in the single facer, preventing the corrugating unit from moving with respect to the single facer when in use.

Therefore, there is a need for a plant with simpler and more and efficient management and replacement of the corrugating units.

According to claim <NUM>, a plant for producing corrugated board is provided, comprising at least one single facer, having a supporting structure adapted to receive a corrugating unit with a first corrugating roller and a second corrugating roller meshing with each other. The plant also comprises a magazine with a plurality of receiving seats for receiving corrugating units. The magazine is movable along a first guide, preferably in a direction orthogonal to the axes of the corrugating rollers, when the corrugating rollers are located in the single facer. Associated with the single facer is a moving shuttle, adapted to move between the single facer and the guide of the magazine and to transfer corrugating units from the single facer to the magazine and vice versa. The movement of the shuttle is preferably orthogonal to the movement of the magazine.

Differently from some plants of the current art, therefore, the single facer is provided with its own shuttle, which moves back and forth from the single facer to the magazine and vice-versa, to transfer corrugating units from the single facer to the magazine and vice versa. The shuttle can pick up a corrugating unit from the single facer, transfer the corrugating unit from the single facer to the magazine and release the corrugating unit in a free one of the seats of the magazine. The same shuttle can pick up one of the corrugating units from the magazine, transfer the corrugating unit from the magazine to the single facer and release the corrugating unit in the single facer.

The corrugating units do not need to be provided with their own wheels and motors, for moving back and forth from the single facer to the magazine and vice-versa. Moreover, safer and easier locking of the corrugating unit in the single facer can be obtained in a simple and reliable manner.

In this way, it is possible to obtain a highly flexible management of the corrugating units.

The shuttle comprises lifting members, adapted to lift the corrugating units from the supporting structure of the single facer and from the magazine and to lower the corrugating units onto the supporting structure of the single facer and onto the magazine. Therefore, when the corrugating unit is in the operating position in the single facer, it is positioned at a lower height than the height at which it is positioned when it is on the shuttle. This avoids the need for complex actuators that push the corrugating unit upward when it is operating in the single facer. Besides representing a simplification from a mechanical point of view, this makes the plant safer and more reliable, and also less subject to stoppages.

Advantageously, the shuttle is preferably movable along a second guide extending between the single facer and the first guide. The guide of the magazine and the guide of the shuttle can be arranged substantially orthogonal to each other and can be substantially about on the same plane and intersecting with each other. In this way it is possible to reduce the excavation works required to install the guides and at the same time reduce their footprint above the floor. This makes implementation of the plant less costly and reduces the presence of obstacles that may negatively affect the passage or transit of vehicles, materials and people in the plant.

In advantageous embodiments, the plant can comprise a plurality of single facers arranged in sequence along a direction of alignment parallel to the first guide. Each single facer can comprise a respective shuttle movable between the single facer and the first guide, adapted to transfer corrugating units from the respective single facer to the magazine and vice versa. The magazine can be adapted to be positioned selectively in alignment with one or other of the single facers, to transfer, by means of the respective shuttle, corrugating units from the magazine to the respective single facer and vice versa.

According to another aspect, a method for inserting a corrugating unit into a single facer is disclosed, the corrugating unit comprising a first corrugating roller and a second corrugating roller meshing with each other. The method is defined in claim <NUM>. The method comprises the steps of:.

Further advantageous embodiments and possible features of the plant and of the method disclosed herein are illustrated below with reference to the accompanying drawings.

The invention will be better understood by following the description and the accompanying drawings, which illustrate an exemplifying and non-limiting embodiment of the invention. More particularly, in the drawings:.

<FIG> shows a plan view of a plant <NUM> for producing corrugated board, wherein only the elements of the plant useful for a better understanding of the present invention are represented schematically. In the example illustrated in <FIG>, the plant <NUM> comprises two single facers 3A, 3B, aligned along a direction F that represents the general direction of feed of the webs of paper through the plant. One of these single facers, indicated generically hereinafter with <NUM>, will be described in greater detail below with reference to the subsequent figures. While <FIG> shows two single facers 3A, 3B, it must be understood that the number of single facers of a line or plant for producing corrugated board can vary. In some cases, even only one single facer may be provided, although preferably two or more single facers will be provided in sequence, which can either all be operating or can be activated selectively depending upon the type of corrugated board to be produced.

On one side of the sequentially arranged single facers <NUM> a first guide <NUM> is positioned, for example comprising two rails 5A, on which a magazine <NUM> is movable. The reference f7 indicates the direction of movement of the magazine <NUM> along the guide <NUM>.

As will clarified below, the magazine <NUM> is provided with several seats 7A, 7B, 7C for receiving corrugating units, each of which comprises a pair of corrugating rollers meshing with each other. The corrugating units can be inserted selectively into one or into the other of the single facers 3A, 3B. In the embodiment illustrated, the magazine <NUM> comprises three seats for three corrugating units. Moreover, it must be understood that the number of seats of the magazine <NUM> can differ from the number illustrated by way of example.

The magazine <NUM> can be used both to load one or the other of several corrugating units onto just one single facer 3A, 3B, and also to transfer corrugating units from one to the other of the various single facers of the line.

To transfer the corrugating units (not shown in <FIG>) from the magazine <NUM> to one or to the other of the single facers 3A, 3B, and vice versa, each single facer 3A, 3B comprises a respective second guide 9A, 9B, which can be formed of a pair of rails 10A, 10B. A shuttle 11A, 11B is movable on each second guide 9A, 9B. The reference f11 indicates the direction of movement of each shuttle. The shuttles 11A, 11B can be the same as one another and one of them, indicated with <NUM>, will be described in greater detail below with reference to the remaining figures.

Advantageously, the guides <NUM>, 9A, 9B are mounted approximately at the level of the floor P on which the single facers 3A, 3B are installed, so as to limit to a minimum the excavation works and encumbrances above the floor P. More in particular, the rails 10A, 10B of the guides 9A, 9B can be fixed directly on the floor, while the rails 5A of the guide <NUM> can be anchored to a structure embedded in the floor P. The rails 10A, 10B can be interrupted at the rail 5A with which they intersect.

In this way, for example, conveyors can be easily arranged for transferring the reels of paper into and out of the production line in which the unwinders are inserted, without encountering obstacles.

Each shuttle 11A, 11B can be selectively inserted into the respective single facer 3A, 3B, or into the magazine <NUM>, so as to be able to position a corrugating unit in the single facer 3A, 3B or in the magazine <NUM>. To allow the shuttle 11A, 11B to be positioned in alignment with the magazine <NUM>, i.e., inside or underneath it, the rails 10A, 10B of the second guide 9A, 9B can be interrupted in the point of intersection with one of the rails 5A of the first guide <NUM>.

In the example of <FIG> the magazine <NUM> is movable with respect to the single facers 3A, 3B so as to allow alignment of one or other of the seats of the magazine with one or other of said single facers 3A, 3B. In this way, it is possible to transfer corrugating units from any one of the single facers 3A, 3B to the magazine <NUM> and vice versa. The magazine <NUM> therefore allow sharing of a plurality of corrugating units with only one single facer 3A, or 3B, or alternatively with both single facers 3A, 3B, and with other single facers, not shown, if present in the production line.

The use of a magazine <NUM> movable between a plurality of aligned single facers is particularly useful and advantageous, in particular as it allows the use of a single member to transfer corrugating units from one to the other of several single facers. It is also possible to increase the capacity of the magazine, providing it with a number of seats higher than the three seats represented schematically in <FIG>.

Moreover, it would also be possible for the plant to have only one single facer served by a magazine, or for the plant to have several single facers and several magazines. For example, it is possible to provide a guide <NUM> on which two or more magazines, capable of interfacing with only one single facer or, preferably, with a series of single facers, are movable.

In some embodiments, the guide <NUM> of the magazine <NUM> can also extend beyond the single facers, for example toward a standby area, where corrugating units can be loaded onto or unloaded from the magazine, for example with a carriage or with an overhead crane or other means. In other embodiments, it would also be possible for the guide <NUM> to extend toward a heating area, provided with means for heating the corrugating rollers of the corrugating units installed on the magazine, before inserting them into the respective single facer.

When a magazine only serves one single facer it is still particularly advantageous, as it allows one or the other of several corrugating units to be loaded on the single facer, one corrugating unit being normally in the operating position in the single facer, while the others are located in the seats of the magazine.

In the figures subsequent to <FIG>, the plant <NUM> is represented limited to one single facer <NUM> with respective shuttle <NUM> and second guide <NUM> for moving the shuttle <NUM>. It must be understood that this is purely an example and that all the characteristics of the magazine, of the shuttle, of the guides, of the corrugating unit and of the single facer described in detail with reference to <FIG> and the following ones can be provided in a plant in which the magazine serves several single facers in line.

The structure of a plant according to the present invention will be described in greater detail below with specific reference to <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG>. The replacement cycle of a corrugating unit will be described later with reference to the sequence of <FIG>, <FIG>, <FIG> and <FIG>.

The plant <NUM> of <FIG> and the following ones comprises the single facer <NUM>, arranged at the side of which is the first guide <NUM>, which can comprise the rails 5A. The magazine <NUM> moves on the guide according to the arrow f7. In the illustrated example, the magazine <NUM> comprises three seats 7A, 7B, 7C for three corrugating units. In the appended drawings, two corrugating units, indicated with 20A and 20B, are visible. In the arrangement of <FIG>, a first corrugating unit 20A is in operating position in the single facer <NUM>, while a second corrugating unit 20B is located in one of the three seats of the magazine <NUM>. In <FIG> both the corrugating units 20A, 20B are located in the magazine <NUM>. <FIG> also shows some details of the magazine <NUM>.

In particular, in the illustrated embodiment the magazine <NUM> comprises a structure consisting of cross members <NUM> joined to each other by a beam <NUM>. The cross members <NUM> and the beam <NUM> in substance define a comb structure, inside which the shuttle <NUM> associated with the single facer <NUM> can enter. Each pair of adjacent cross members <NUM> defines a seat for a respective corrugating unit.

The magazine <NUM> also has wheels <NUM>, arranged in pairs to run along the rails 5A. At least one pair of wheels <NUM> is motorized, for example by means of a motor <NUM> (see <FIG>) carried by the magazine <NUM>.

The structure of the corrugating unit <NUM> is generally known and only some aspects thereof useful in the present context will be described below. With reference in particular to <FIG> and <FIG>, each corrugating unit 20A, 20B, indicated with <NUM> in <FIG> and <FIG>, comprises two heads <NUM>, <NUM>, supported between which are a first corrugating roller <NUM> and a second corrugating roller <NUM> meshing with each other in a corrugating nip <NUM> (<FIG>). The heads <NUM>, <NUM> are joined to each other by beams <NUM>. Reference <NUM> indicates a toothed pulley or toothed wheel that receives motion from a mover, not shown, and rotates the two corrugating rollers <NUM>, <NUM> when the corrugating unit <NUM> is in the single facer <NUM>.

Reference <NUM> indicates four feet for supporting the corrugating unit <NUM> on the floor P or on the magazine <NUM>.

Each of the two heads are fitted with two profiles <NUM>, <NUM>, which define surfaces for supporting and centering the corrugating unit <NUM> on the single facer <NUM>. More in particular, the two profiles <NUM> define a supporting surface shaped with two V-shaped notches, while the profiles <NUM> define flat supporting surfaces. The two profiles <NUM>, <NUM> are configured to rest on complementary profiles <NUM>, <NUM>, integral with a supporting structure <NUM> of the single facer <NUM>.

The supporting structure <NUM> of the single facer <NUM> comprises side panels <NUM>, <NUM> joined by cross members <NUM>. The side panel <NUM> forms a through opening <NUM>, while the side panel <NUM> forms a through opening <NUM> (see in particular <FIG>). The openings <NUM> and <NUM> allow the insertion of a corrugating unit <NUM> into the supporting structure <NUM> passing through either one or the other of the two side panels <NUM>, <NUM> for the purposes that will be explained below. In other embodiments, the side panel <NUM> can be without a through opening, in which case the corrugating units <NUM> are inserted into and extracted from the single facer <NUM> only through the side panel <NUM>.

Each shuttle <NUM> comprises a base structure <NUM>, for example formed by a frame of welded beams, equipped with wheels. More in particular, the wheels of the shuttle <NUM> can be arranged in pairs. As shown in particular in <FIG>, a first pair or wheels <NUM> is advantageously motorized by means of a motor <NUM> carried by the shuttle <NUM>, while two pairs of wheels <NUM> and <NUM> are idle and are arranged in the vicinity of the end of the shuttle opposite the end at which the motorized wheels <NUM> are located and oriented toward the magazine <NUM>.

Advantageously, the pairs of wheels <NUM> and <NUM> are arranged with their axes close to one another so as to provide a continuous support on the rails <NUM>, along which the shuttle <NUM> moves, also in the areas in which the rails <NUM>, forming the guide <NUM>, are interrupted to intersect one of the rails 5A of the first guide <NUM>.

Advantageously, the shuttle <NUM> can comprise lifting members <NUM>, shown in particular in the detail of <FIG>. In the illustrated embodiment, the lifting members <NUM> comprise two supporting surfaces <NUM>, <NUM> movable vertically by means of a lifting and lowering actuator <NUM>, for example a piston-cylinder actuator. The lifting and lowering actuator <NUM> can act directly on a pair of levers <NUM> pivoted about an axis which is stationary with respect to the shuttle <NUM>, so that the extension and contraction of the lifting and lowering actuator <NUM> causes a rotation movement of the levers <NUM> and consequent lifting and lowering of the supporting surface <NUM>. By means of a transmission bar <NUM> the movement of the lifting and lowering actuator <NUM> can be transmitted to a second pair of levers <NUM>, which rotate to control the lifting and lowering movement of the surface <NUM>. The lifting mechanism is described purely by way of example. Any other lifting mechanism can be used, for example also using different power sources, such as pneumatic or electric mechanisms.

The supporting surfaces <NUM>, <NUM> form supports for the corrugating unit <NUM>. Said supporting surfaces <NUM>, <NUM> can coact with the heads <NUM>, <NUM> of each corrugating unit <NUM>. By means of these supporting surfaces, it is possible to lift a corrugating unit <NUM> from the supporting structure <NUM> of the single facer <NUM> or rest a corrugating unit <NUM> on this supporting structure <NUM>. By means of the aforesaid supporting surfaces it is also possible to deposit a corrugating unit <NUM> on the magazine <NUM>, or lift it from the magazine <NUM>. The lifting and lowering movement with which the shuttle <NUM> is provided can also be used to rest the corrugating units <NUM> on, or lift them from, the floor P.

<FIG>, <FIG>, <FIG> show, in a plan view, the movement that can be carried out by the magazine <NUM> and by the shuttle <NUM> in order to replace the corrugating unit 20A, which is located in the single facer <NUM>, with the corrugating unit 20B located on the magazine <NUM>. More in particular, in this exemplary embodiment the magazine <NUM> has three seats 7A, 7B, 7C for three corrugating units <NUM>. The seat 7A is empty, the seat 7B is occupied by the corrugating unit 20B and the seat 7C is empty. In <FIG> the magazine <NUM> is translating according to the arrow f7 from right to left, so as to carry the seat 7C into alignment with the openings of the side panels <NUM>, <NUM> of the corrugating unit 20A located in the single facer <NUM>. The shuttle <NUM> is located in the single facer <NUM>, under the corrugating unit 20A.

In <FIG> the magazine <NUM> is located with its seat 7C aligned with the single facer <NUM>. The shuttle <NUM> and the corrugating unit 20A are still located in the single facer <NUM>.

In <FIG> the shuttle <NUM> has transferred the corrugating unit 20B toward the magazine <NUM> according to the arrow f11. To carry out this operation, as mentioned above, the corrugating unit 20A is lifted by means of the lifting and lowering actuator <NUM> (<FIG>), which causes lifting of the supporting surfaces <NUM>, <NUM>. In this way, the corrugating unit 20A is lifted and moved away from the shaped profiles <NUM>, <NUM> and can be transferred from the shuttle <NUM> to the magazine <NUM>. When the shuttle <NUM> is located under the magazine <NUM>, the lifting and lowering actuator <NUM> lowers the supporting surfaces <NUM>, <NUM>, releasing the corrugating unit 20B onto the seat 7C of the magazine <NUM>. At each seat 7A, 7B, 7C of the magazine <NUM>, suitable supporting elements can be provided, onto which the respective corrugating unit <NUM> can be released. In the embodiment illustrated in the accompanying drawings, the supporting elements are indicated with <NUM> and are configured and arranged to receive the feet <NUM> of the respective corrugating unit <NUM>. The configuration is such that the lifting movement can be very limited, for example of only a few centimeters. This makes the replacement operations faster and safer.

From the position of <FIG>, the magazine <NUM> can translate from left to right to align the seat 7B with the openings <NUM>, <NUM> of the side panels <NUM>, <NUM> so as to carry out, again by means of the shuttle <NUM> and with operations in reverse order to those described above, insertion of the corrugating unit 20B into the single facer <NUM>.

<FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG>, <FIG> show, in an axonometric view (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>) and in a sectional view according to the lines B-B (<FIG>, <FIG>, <FIG>, <FIG>, <FIG>) by way of example a transfer cycle of a corrugating unit (in the illustrated example the corrugating unit 20A) from the magazine <NUM> to the single facer <NUM>. The sequence is self-explanatory and will only be described briefly. The operations are carried out by means of the shuttle <NUM> equipped with the lifting members <NUM>.

In <FIG>, <FIG> the seat 7C of the magazine <NUM> is aligned with the single facer <NUM>. The shuttle <NUM> is located in the single facer <NUM>, to allow positioning of the magazine <NUM>. In <FIG>, <FIG> the shuttle <NUM> is being transferred (arrow f11) under the magazine <NUM>. In <FIG>, <FIG> the shuttle <NUM> is under the corrugating unit 20A. In <FIG>, <FIG> the shuttle <NUM> is transferring (arrow f11) the corrugating unit 20A into the single facer <NUM>. Before starting the movement towards the single facer, the lifting members <NUM> have lifted the corrugating unit 20A from the supports <NUM> of the seat 7C of the magazine <NUM>. In <FIG>, <FIG> the shuttle <NUM> with the corrugating unit 20A is inserted into the single facer <NUM>, between the two side panels <NUM>, <NUM> thereof and the corrugating unit 20A can be lowered and taken to rest on the side panels <NUM>, <NUM>.

As mentioned, the side panel <NUM> is open to allow insertion of a corrugating unit <NUM> therethrough from the side opposite to the magazine <NUM>. For this purpose, an auxiliary carriage <NUM>, shown in <FIG> and <FIG>, can be used. The auxiliary carriage <NUM> can have a steering and control handlebar <NUM>. Reference <NUM> indicates a frame of the auxiliary carriage <NUM>. Reference <NUM> indicates a rear driving wheel, pivoting about a vertical axis. The motor of the wheel <NUM> is not shown. Reference <NUM> indicates idle wheels arranged on the front part of the auxiliary carriage <NUM>. The wheels <NUM>, <NUM> can be partially rubber coated, to allow the free movement of the auxiliary carriage <NUM> on the floor or ground surface P. A part, with a smaller diameter, of the wheels <NUM>, <NUM> can be made of steel to coact with the rails 10A, 10B of the shuttle <NUM>.

The auxiliary carriage can advantageously comprise auxiliary lifting members <NUM>, <NUM>, which can be configured as the previously described lifting members <NUM> or in any other suitable way. The lifting members <NUM> can comprise vertically movable surfaces that lift and lower a corrugating unit <NUM> with respect to the floor P and/or with respect to the supporting structure <NUM> of the single facer. For this purpose, the lifting members <NUM> are placed at a suitable height to be able to release the corrugating unit <NUM> on the ground, resting thereon by means of the respective supporting feet <NUM>.

The auxiliary carriage <NUM> can be used both for inserting a corrugating unit <NUM> into the single facer <NUM> and for extracting it therefrom, and for loading a corrugating unit onto the magazine <NUM> or removing it therefrom. The auxiliary carriage can also be used to move the corrugating units <NUM> to any part of the plant, as said auxiliary carriage <NUM> can move freely rather than on guides. In this way the plant <NUM> becomes very flexible and allows easy movement of even a very large number of corrugating units <NUM>.

To facilitate insertion of the auxiliary carriage <NUM> into the single facer <NUM> through the side panel <NUM>, an aligning device <NUM> can be provided, described below with particular reference to <FIG> and <FIG>. The aligning device <NUM> is positioned at the side of the single facer <NUM> outside the side panel <NUM>. The aligning device <NUM> can comprise a frame structure <NUM> integral with the supporting structure <NUM> of the single facer <NUM>. A platform <NUM> is hung from the frame structure <NUM>, approximately flush with the floor P and movable according to the double arrow f75 transversely to a direction of alignment of the auxiliary carriage <NUM> with respect to the supporting structure <NUM> of the single facer <NUM>. The direction of alignment is substantially parallel to the direction of the axes of the corrugating rollers <NUM>, <NUM> when the respective corrugating unit <NUM> is correctly inserted into the single facer <NUM>.

Advantageously, the platform <NUM> has a small thickness so as to be able to be placed approximately flush with the floor P without requiring to dig a hole to house it, but if necessary lowering the floor only slightly at P1 (<FIG>).

In the illustrated embodiment, to allow the platform <NUM> to float with respect to the floor P according to the arrow f75, the platform <NUM> is hung by means of tie rods <NUM> from the frame structure <NUM>. In this way, no guide members of the platform <NUM> are required to be housed in the floor P and there is no need for excavations. In substance, the platform <NUM> is hung on the frame structure <NUM> in the manner of a pendulum by means of the tie rods <NUM>. The swinging movement of the platform <NUM> is limited to a few degrees and therefore the platform remains substantially parallel to the floor P during the oscillating motion.

A fixed guide <NUM> is associated with the platform <NUM>, integral with the floor P and adapted to generate a thrust on the auxiliary carriage <NUM> in a direction transverse to a direction of approach and insertion of the auxiliary carriage into the single facer <NUM>, i.e., a thrust with a component parallel to the movement f75 of the platform <NUM> with respect to the floor P. The fixed guide <NUM> can have two side members opposite each other and converging from the outside toward the side panel <NUM> of the supporting structure <NUM>. Downstream of the converging side members forming the fixed guide <NUM> are rails <NUM> on which the front wheels <NUM> of the auxiliary carriage <NUM> can be mounted. The rails <NUM> can form an extension of the rails on which the shuttle <NUM> runs.

With this arrangement, insertion of a corrugating unit <NUM> with a manual operation using the auxiliary carriage <NUM> is particularly easy, notwithstanding the weight of a few tons of the corrugating unit <NUM>. In fact, even if the auxiliary carriage <NUM> moves laterally toward the single facer <NUM> with a direction of movement not perfectly parallel to the direction that the axes of the corrugating rollers <NUM>, <NUM> must assume after being inserted into the single facer <NUM>, the impact of the front part of the carriage <NUM> against the side members <NUM> of the alignment guide corrects the trajectory of the auxiliary carriage <NUM>, due to the fact that the lateral thrust exerted by the side members <NUM> on the auxiliary carriage <NUM>, while it is resting with the front wheels <NUM> on the floating platform <NUM>, causes a translation movement according to the arrow f75 of the platform and therefore of the front part of the carriage, until obtaining the correct alignment.

The above described embodiment of the corrugated board manufacturing plant <NUM> allows many advantages to be obtained. The presence of a shuttle <NUM> for moving the corrugating units <NUM> away from and toward the magazine <NUM> allows said magazine and the related guide <NUM> to be positioned even at a considerable distance from the corrugated board line, i.e., far from the single facers <NUM>. In fact, there are substantially no limits to the distance that can be traveled by the shuttles <NUM>. If the guides <NUM> are flush with the floor or ground level P, they practically cause no obstacle to the movement of people or vehicles.

Using lifting members in the shuttle <NUM>, it is possible to provide the corrugating units <NUM> with a structure suitable to be positioned in the operating position by lowering them onto the supporting profiles <NUM>, <NUM>. It is possible to omit the actuators normally required in the single facers of the prior art, to maintain the corrugating units raised against reference stops positioned in the upper area. This simplifies the machine and greatly increases its reliability. The corrugating unit can be maintained blocked in the correct operating position simply by its weight and if required with the aid of the pressure exerted thereon by a roller or other pressure member that, in a known manner, applies the gluing pressure on the corrugating roller <NUM>.

Claim 1:
A plant for producing corrugated board, comprising:
at least one single facer (<NUM>), comprising a supporting structure (<NUM>), adapted to receive a corrugating unit (<NUM>) comprising a first corrugating roller (<NUM>) and a second corrugating roller (<NUM>) meshing with each other; and
a magazine (<NUM>) comprising a plurality of seats (7A, 7B, 7C) for receiving corrugating units (20A, 20B) and movable along a first guide (<NUM>) to align one of said eat with the single facer (<NUM>);
wherein a shuttle (<NUM>) associated with the single facer (<NUM>) is provided, wherein the shuttle (<NUM>) is movable between the single facer (<NUM>) and the guide (<NUM>) of the magazine (<NUM>), adapted to transfer corrugating units (20A, 29B) from the single facer (<NUM>) to the magazine (<NUM>) and vice versa; and that the shuttle (<NUM>) comprises lifting members (<NUM>), adapted to lift the corrugating units (20A, 20B) from the supporting structure (<NUM>) of the single facer (<NUM>) and from the magazine (<NUM>) and to lower the corrugating units (20A, 20B) onto the supporting structure (<NUM>) of the single facer (<NUM>) and onto the magazine (<NUM>), whereby corrugating units can be lifted by the shuttle from the supporting structure of the single facer, transferred by the shuttle to the magazine and released by the shuttle on the magazine, and vice-versa..