The present invention relates to an improved industrial plant and method, in particular to a unit or apparatus for in-line loading workpieces and the method for in-line loading workpieces.

In well-known industrial plants for mass production of assembled furniture, taken as an example here, a line performs various machining operations (drilling, milling, ... and assembly operations) on the components fed at its entry. Components, e.g. panels and/or hardware, are automatically picked up from loading bays, which components are then sequentially processed along the line to eventually make up the assembled furniture or part thereof. See e.g. EP 1 342 535.

The preparation of the components on each bay is a critical step.

Currently, each bay is first prepared manually. A worker goes to the warehouse to find the necessary workpieces specified on an order list for that day, and then he takes the bay at the entry of the line, where a machine will pick up the workpieces.

It is easy to see that such a system has several disadvantages.

Not only is the time for preparing the bays very long, increasing the production cost, but large storage spaces are needed to allow for the movement and job of the workers (and many workers are needed).

If then the finished product, or a production with many variations, requires many different workpieces (e.g. different colors or sizes), the number of workpieces in the warehouse increases and with it the complexity and difficulty of preparing the bays.

It is clear that such a system discourages the design of, or thwarts the investment in, a production plant capable of manufacturing products with wide-ranging models.

The main object of the invention is to improve the present state of the art.

Another object of the invention is to make an improved industrial plant for producing an assembled product (e.g. a piece of furniture), or an assembled part of a product (e.g. a drawer), starting from separate components (e.g. panels and/or hardware).

In particular, the object of the invention is to make a workpiece feeder for the industrial plant to produce said assembled product more efficiently.

These and other objects are achieved by what is contained in the attached claims; advantageous technical features are defined in the dependent claims.

An aspect of the invention is a method for loading on a line, capable of producing an assembled product (e.g. a piece of furniture) or an assembled part of a product (such as a drawer) starting from a set of N separate components (N >= 2) and assembling the N separate components in a certain order. E.g. a separate component of the N components is a top panel, a back panel, a bottom panel, or two side panels, and optionally an intermediate shelf, and/or linear guides and/or reinforcement strips, to make up a drawer or cabinet compartment at the end of the line.

The method allows the N components, which are required to eventually produce a desired finished part, to be loaded at the entry of a line in a predefined sequence, and has the steps of

- subdividing the set of N components into K subsets of components (e.g. stacks), K >= 2, and spatially arranging the K subsets in a spatial sequence (e.g. in rows or stacks),

- moving a train of workpiece-carriers in front of the K subsets in such a manner that o all the workpiece-carriers arrive sequentially at each K-th subset at least once so that, when necessary, a component (at a time) can be taken from a K-th subset and loaded onto the workpiece-carrier (e.g. when it is closer), and o all the workpiece-carriers also arrive sequentially at the line entry, and

- for each workpiece-carrier arriving (close) to each K-th subset, activating or excluding the loading of a component from that K-th subset so that, progressively as the train moves, consecutive workpiece-carriers of the train are loaded with components corresponding to the predefined sequence, and

- components are picked up from said consecutive workpiece-carriers and loaded onto the line, emptying one workpiece-carrier after the other.

Therefore, the line is fed with the desired sequence of components.

In other words, each of the consecutive workpiece-carriers arrives (close) to each K- th subset, and in that circumstance it is decided to load a component from that K-th subset if the final sequence of components in said consecutive workpiece-carriers requires such component, otherwise nothing is loaded from that K-th subset and the empty workpiece-carrier will eventually be loaded from a subsequent K-th subset.

Said consecutive workpiece-carriers may possibly comprise empty workpiececarriers from time to time, even if production efficiency is lower.

As the carriers of the train visit all the K subsets, consecutive workpiece-carriers of the train are progressively loaded with components corresponding to the predefined sequence, which is completed when the last workpiece-carrier of the consecutive ones has left the last K-th subset. Then the components will be loaded sequentially on the line picking them up from the chain of consecutive workpiece-carriers.

Preferably, a component from each K-th subset is loaded onto a workpiece-carrier by means of a robot or a manipulator, in particular a robot or manipulator dedicated only to such K-th subset. It is also possible to provide only one robot or manipulator for all K subsets.

Preferably, components are picked up from said consecutive workpiece-carriers and loaded onto the line by means of a robot or manipulator,

Preferably, the robots or manipulators of each K-th subset are activated to load a component onto a workpiece-carrier or controlled to do something else (e.g. set to pause) if, respectively, the current workpiece-carrier present at such K-th subset must contain a component to comply with the predefined sequence, or not.

Although the train could be a row of workpiece-carriers moving linearly back and forth, for greater efficiency and less bulk the train is preferably a closed chain of workpiece-carriers moving on a closed or circular path, e.g. always in the same direction of movement.

Preferably each K-th subset consists of adjacent stacks of equal components, each stack having the same height (and/or same number of components).

Preferably from the adjacent component stacks of each K-th subset, a plane of components is unloaded and deposited in a work area, from which they are picked up as needed to be loaded onto a workpiece-carrier.

The work area may be a dedicated space, or a portion of a conveyor means.

More preferably, if unused components remain in the plane of components present in the work area (because the piece sequence does not require them), instead of sending them back to the warehouse, they are placed in a temporary rest area and loaded onto a workpiece-carrier at the first occurrence.

Preferably, a workpiece that is single and not needed on the line in large quantities is loaded onto a workpiece-carrier by picking it directly from a storage unit without the subdivision into K subsets.

Another aspect of the invention relates to a feeder apparatus or device capable of carrying out the above method. The apparatus is configured to feed the entry of a production line, made up of several machines in series, with a predetermined sequence of N components, the N components being necessary to produce a desired finished part at the end of the line. The apparatus comprises:

- K subsets of components (e.g. stacks), K >= 2, spatially arranged in a spatial sequence (e.g. in a row or stack),

- a train of workpiece-carriers that is movable with respect to the K subsets so that each workpiece-carrier sequentially arrives to each K-th subset at least once and also arrives at said entry.

Although loading from the K subsets and/or unloading toward the line could be done manually, in order to automate the system the feeder apparatus preferably comprises means or one or more manipulators to pick up a component from a K-th subset (e.g. at a time) and load it onto a workpiece-carrier of the train (when the workpiece-carrier is closer). To increase the production speed, more preferably at each K-th subset there is a means or one or more manipulators for picking from such K-th subset.

Although the loading from the train to the line could be done manually, to automate the system the feeder apparatus preferably comprises means or one or more manipulators to pick up from a workpiece-carrier of the train the component contained therein and load it onto the line.

Each workpiece-carrier in the train is adapted to contain at a time only components (one or more than one) taken from a single K-th subset.

Although the control of the means or one or more manipulators to pick up from a K-th subset and/or the control of the means or one or more manipulators to pick up from a workpiece-carrier of the train and load it onto the line could be done manually, to automate the system the feeder apparatus preferably comprises a programmable electronic unit for driving the aforementioned means or manipulators.

In particular, to increase production speed and efficiency, more preferably the apparatus comprises

- first means, or one or more manipulators, to pick up a component from a K-th subset and load it onto a workpiece-carrier of the train,

- second means, or one or more manipulators, to pick up a component from a workpiece-carrier of the train and load it onto the production line,

- an electronic control unit configured for

• controlling the movement of the workpiece-carriers so that they arrive sequentially at each K-th subset at least once and also arrive sequentially at the line entry, • driving the first means to be able to pick up a component from a K-th subset and load it onto a workpiece-carrier,

• driving the second means to pick up a component from a workpiece-carrier and load it onto the line,

• activating or excluding the loading of a component from a K-th subset so that, progressively as the train moves, consecutive workpiece-carriers of the train are loaded with components corresponding to the predefined sequence, and

• driving the second means to pick up components from said consecutive workpiece-carriers and load them onto the line, emptying one carrier after the other.

In the apparatus, the train comprises a row of workpiece-carriers adapted to move linearly back and forth. For greater efficiency, the train preferably comprises a closed chain of workpiece-carriers adapted to move on a closed or circular path, e.g. always in the same direction of movement.

Preferably, in the apparatus each K-th subset consists of adjacent stacks of equal components. E.g. each stack has the same height (and/or the same number of components).

Preferably, the apparatus comprises a conveyor device adapted to transport a stack of components and/or each K-th subset from a warehouse to the train of workpiececarriers.

In particular, the apparatus comprises K of said conveyor devices, one dedicated to each K-th subset.

In particular, one or each conveyor device comprises a roller or conveyor belt.

In particular, the said K conveyor devices are arranged in parallel rows in front of the train of workpiece-carriers. In particular, the parallel rows are arranged along a direction perpendicular to a linear row of workpiece-carriers in the train.

In particular, one or each conveyor device comprises a temporary rest area for workpieces.

In particular, one or each conveyor device comprises a first transporting means a second transporting means placed in series with the first one, and two robots or manipulators, one placed between the first transporting means and the second transporting means to transfer workpieces from the first transporting means to the second transporting means, and one placed between the second transporting means and the train to transfer workpieces from the second transporting means to the train of workpiece-carriers.

More specifically, the temporary rest area is provided on the second transporting means, close to the first transporting means.

Preferably the panels are wooden and/or flat.

In the apparatus and method, preferably the activity of manipulators, robots and transporting means in general is controlled and regulated via software.

Known manipulators, robots and transporting means may also be used in the apparatus and method.

In the apparatus and method e.g. a pallet catenary or a belt advancing at a predefined rate can be used as a workpiece train.

Further advantages will become clear from the following description, which refers to an example of preferred embodiment of workpiece-feeding apparatus in which:

Figure 1 shows a scheme of the feeder apparatus,

Figure 2 shows a loading bay,

Figure 3 shows a scheme variant for the feeder apparatus.

Equal numbers in the figures indicate equal or substantially equal parts. Arrows indicate the movement direction of the material.

A feeder MC of Fig. 1 is placed between the entry of a production line LN and an warehouse ST to feed the line LN with a predefined sequence of workpieces. The production line LN consists of a series of machines 80 that successively process the workpiece loaded at its entry. The warehouse ST is e.g. a well-known warehouse, from which the workpieces to be processed are taken.

The feeder MC comprises a plurality of loading bays 10 and a conveyor 50.

Each bay 10 accommodates stacked workpieces 32, e.g. on a support or pallet 30 (see Fig. 2), which is movable on roller tracks or rails 12 (only some shown) to and from the warehouse ST to bring workpieces to the conveyor 50 continuously. The number of bays 10 may vary, two or more. The bays 10 are arranged in a row on one side of the ring, with the entry of the line LN arranged on the opposite side. Each bay 10 contains workpieces that are all equal and different from those of the other bays 10. The conveyor 50 comprises a train of workpiece-carriers 52 driven to move continuously to reach the bays 10 and the line LN. The train of workpiece-carriers 52 can e.g. move forward-backward, or more efficiently on a ring-shaped closed loop (see arrow F). Each carrier 52 may contain one or more workpieces of the bays 10. The carriers 52 are spaced from each other approximately as far apart as the distance between two bays 10, so as the train moves along the ring each carrier 52 can pass in front of each bay 10. A or each workpiece-carrier 52 may be, for example, a suspended tray conveyor, a frame, a container or a clampable gripper.

The workpieces are first transferred from the bays 10 to the conveyor 50 and then from the conveyor 50 to the line LN. Although the transfer of workpieces could be done manually, it is best to make the system faster and more automatic by using robots or manipulators 14 to transfer workpieces from the bays 10 to the conveyor 50 and robots or manipulators 16 to transfer workpieces from the conveyor 50 to the line LN. At least one dedicated robot or manipulator 14 should be dedicated for each bay 10 and one or more robots or manipulators 16 for the line LN.

To serve the bays 10, it is also possible to provide a single robot or manipulator 14 capable of moving from one bay 10 to another.

To facilitate the transfer of workpieces, the conveyor 50 is preferably configured or driven to stop temporarily in order to let the workpiece-carriers 52 be stationary near the bays 10.

The operating logic of the feeder MC will now be explained, using an example wherein there are three bays 10, denoted for convenience by 10a, 10b, 10c, containing workpieces 20, 22, 24 respectively, and on the line LN the sequence of workpieces 20- 24-24-22-22 is needed. The sequence of workpieces is prepared on consecutive workpiece-carriers 52, which we will distinguish for convenience with 52a, 52b, 52c, 52d and 52e, respectively.

The workpiece-carrier 52a arrives empty at the bay 10a and the manipulator 14 loads the workpiece 20 onto it. When the train of workpiece-carriers 52 then advances, the workpiece-carrier 52a will arrive at the bays 10b and 10c but the manipulator 14 will load nothing.

The workpiece-carrier 52b arrives empty at the bay 10a and the manipulator 14 loads nothing. Then the workpiece-carrier 52b runs on and arrives empty at the bay 10b and there the manipulator 14 loads nothing. Then the workpiece-carrier 52b runs on and arrives at the bay 10c where the manipulator 14 loads the workpiece 24 on it. The same will happen for the workpiece-carrier 52c.

The workpiece-carrier 52d arrives empty at the bay 10a and the manipulator 14 loads nothing. Then the workpiece-carrier 52d runs on and arrives empty at the bay 10b and there the manipulator 14 loads the workpiece 22. Then the workpiece-carrier 52d runs on and arrives at the bay 10c and the manipulator 14 loads nothing there.

The same will happen with the workpiece-carrier 52e.

With this load, the train of workpiece-carriers 52 advances, bringing the workpiececarriers 52a, 52b, 52c, 52d, 52e in the vicinity of the line LN, where the manipulator 16 picks up the workpieces from the workpiece-carriers 52 in the order in which they arrive, forming the sequence of workpieces 20-24-24-22-22 on the line LN.

In short, in order to fill consecutive workpiece-carriers 52 with the desired sequence of workpieces, it is determined which consecutive workpiece-carriers 52 must contain the workpieces of the sequence. Then, each time an empty carrier 52 stops near a bay 10, worpieces are loaded on it (from that bay 10) only if they match those of the sequence for that carrier 52. In other words, at each bay 10 there are loaded the workpieces required to form the sequence in the consecutive carriers 52.

When the last workpiece-carrier 52 of the consecutive workpiece-carriers 52 leaves the last bay 10, there will be the desired sequence of workpieces on the consecutive workpiece-carriers 52.

Generally speaking, to obtain a desired sequence of workpieces on consecutive supports 52, it is enough that each bay 10 loads its workpiece/s onto the supports 52 that require that/those workpiece/s. When all the bays 10 have been passed, the sequence of workpieces will have been formed on the consecutive supports 52.

This operating logic is carried out e.g. by programming a PLC or computer that controls the motion of the conveyor 50 and the various robots and manipulators 12, 14 accordingly.

Fig. 3 illustrates a variant of the apparatus indicated with MC2.

Here, between the bays 10 and the conveyor 50, conveyor transporting means 70 equipped with a temporary rest platform 72 for the workpieces are interposed.

The manipulator 14 is placed at one end of the means 70 and is able to pick up a plane or layer of workpieces from the bays 10 and lay it on the transporting means 70 which transfer it towards the manipulator 74 (arrow W). Each of the transporting means 70 comprises, at the opposite end, a manipulator 74 for loading workpieces onto the workpiece-carriers 52 by taking them from the transporting means 70 according to the logic indicated above.

It should be noted that here the workpieces are taken from the transporting means 70 and not directly from the bays 10.

In the event that workpieces not immediately required for the composition of the sequence of workpieces on the conveyor 50 remain on one of the transporting means 70, the manipulator 14 removes them and temporarily parks them on the plane 72, leaving the means 70 free for a change of format or workpieces. The workpieces parked on the platform 72 will be the first to be picked up by the manipulator 14 and repositioned on the means 70 at the service of the production before recalling other identical workpieces from the bays 10. If necessary, the platform 72 may also act as a buffer station for the workpieces, if more time is needed in recalling from the warehouse ST a particular bay 10 than the others.

As an option, an apparatus according to the invention, e.g. that indicated with MC and/or MC2, may comprise a transporting means 90 for carrying (see arrow Q) to the conveyor 50 individual workpieces, or workpieces present in smaller quantities, arriving directly from the warehouse ST without the need to pick up from a stack (i.e. without passing over a bay 10). In this case, the transporting means 90 directly feed the manipulator 74 which loads the workpieces onto the workpiece-carriers 52.

For the apparatus of Fig. 3 as well, to serve the bays 10 it is possible to provide a single robot or manipulator 14 capable of moving to pass from one bay 10 to the other. To serve the means 70, it is also possible to provide a single robot or manipulator 74 capable of moving to pass from one means 70, 90 to the other.

In the apparatuses according to the invention preferably the activity of manipulators, robots and/or transporting means generally is controlled and regulated electronically via software.

The feeder apparatus according to the invention can be further improved with the following options.

The conveyor 50 may have several levels or 'planes' of workpiece-carriers 52 travelling in parallel to increase transport capacity.

To facilitate the gripping of the robots or manipulators 14, the workpieces 32 on the supports or pallets 30 are arranged on adjacent stacks.

Furthermore, from these stacks preferably a robot or manipulator 18 (e.g. with suction cups) picks up a layer of workpieces and places them in a temporary area from where the robot or manipulator 14 will pick them up and load them onto the conveyor 50.

To minimize the risk of incorrect workpieces, each support 30 comprises an identifier, which is read by a reader device before reaching the destination bay 10. When a bay 10 has no more workpieces, the corresponding pallet returns to the warehouse ST to be reloaded and is replaced by a full pallet or support 30. For this purpose, a or each pallet or support 30 is movable and/or motorized.

It can happen that after many cycles in a bay, here called a bay 10x, only a few workpieces remain which will not be used in near-future sequences. The bay 10x risks creating a stoppage of the line LN if a sequence of workpieces is needed containing more workpieces than the bay 10x has (because it is necessary to wait for the arrival of a loaded support 30 from the warehouse ST).

To avoid this problem, the logic of the feeder envisages loading the few remaining workpieces of the bay 10x onto the supports 52 as soon as possible. Thus, the empty support 30 can be cleared from the bay 10x and replaced with one full of the same or different workpieces.