FR3088315A1 - DEVICE FOR CONVEYING PRODUCTS AND METHOD FOR MANAGING THE TRANSFER OF SAID PRODUCTS - Google Patents

Abstract

The present invention relates to a device (2) for conveying products (1) within an industrial line, which may include an outlet (3) with a single movable surface in a drop zone; surrounding the outlet (3), a receiving surface (4) and an inlet (5) running along the opposite edge; an outlet transfer tool (6) for the products (1) from a receiving surface to the outlet; for each inlet (5) a product inlet transfer tool (1) from said inlet (5) to a receiving surface (4). The invention also relates to a product transfer management method (1), comprising at least determining the quantity of products (1) on each of the reception surfaces (4) near said outlet (3); order the transfer of products as the case may be, file from said first receiving surface (4), OR file from said second receiving surface (4), OR simultaneously file from a receiving surface (4) and file from the other receiving surface (4).

Description

Title: Device for conveying products and method for managing the transfer of said products

The present invention enters the field of conveying products within an industrial production and processing line for said products.

For the purposes of the present invention, the term "product" includes an individual object or a group of objects held together.

Such products can be bottles, cans, flasks, boxes, cases, cartons or bundles, in any type of material, in particular glass or plastic, or even cardboard. Such products are generally intended to contain liquids or food.

Within such an industrial line, the products can receive several different successive treatments, ranging from the manufacture of the container for example by a stretch-blowing operation to the packaging in cases or bundles of several products grouped together then the palletization of several cases or burdens, including filling and labeling of products individually.

In this context, the products are successively conveyed between processing stations using conveyors, essentially of the endless belt type. The products are processed or even conveyed in an aligned fashion in one or more lines, or alternatively in a staggered or loose fashion.

In known manner, the production rate of an industrial line is limited by the slowest machine, especially by certain processing stations at the unit of the products, such as the blower, the filler or the labeling machine. The other stations, generally those which process products in batches, such as shrinkwrapper, case packer or palletizer, therefore operate at speeds below their optimal possibilities.

A problem of conveying the products therefore lies in the difference in processing rates between an upstream station and a downstream station, for example, between a filling or labeling station successively processing the products individually and a processing machine. packaging, like a shrink wrapper, which processes several products simultaneously.

A known solution for managing these differences in rates is to link several machines to a single machine located downstream, faster, through an accumulation of products.

A product accumulation zone makes it possible in particular to prevent the stopping of a downstream machine directly leading to the stopping of the machine (s) upstream and to manage differences in light rates between two machines which follow. Such a zone is in principle arranged between each station of a line in order to ensure the continuity of the production flow.

The flow leaving several upstream machines is therefore pooled and transformed from several generally single-line flows to a single flow generally in bulk which then feeds an accumulation surface. This can be done through an unbundler, allowing one or more single-line product flows to be distributed transversely to their direction of travel. In particular, the products are slowed down and moved to the sides. The products are distributed in staggered rows over a greater planned width compared to the single-line conveyor, until they form a bulk flow which feeds an accumulation surface at the outlet.

According to one case, at the outlet of the accumulation surface, this bulk flow can supply a multi-wire station. The disorderly flow is then oriented towards corridors in order to form several rows, by means of a narrowing of the circulation voice along converging walls, forming a funnel.

Already, such a solution encounters a recurring problem of blocking of the products entering the corridors, due to the tightening, going so far as to cause them to fall, which leads to frequent stops in production. In addition, the bulk grouping induces shocks between the products likely to unbalance them, or even break them in the case of glass containers. These shocks also generate an extremely noisy sound environment. In addition, the tightening can cause a jam of several products at the entrance of the corridors, blocking the advancement of the other products. Finally, such a solution is not compatible with flexible or semi-rigid products, which more easily cause jams.

According to another case, at the outlet of the accumulation surface, this bulk flow can supply a single-line station. It is then necessary to realign the products in a single file. This is done along an aligner. Such an aligner makes it possible to converge a bulk flow of products distributed over a large width towards a single line, through successive accelerations and decelerations over its entire length.

As of now, such an aligner does not allow the single-line transformation of products of shapes, namely which have a polygonal or asymmetrical section or base. Indeed, an aligner uses the rolling of the products against each other. In addition, an aligner causes numerous shocks between the products, which could unbalance them and cause them to fall, or even break them in the case of glass products.

In either case, the use of a staggered accumulation of products followed by their multifilar orientation or their single-line realignment requires a considerable length of conveyors, inducing a relatively high encroachment on the ground. The environment is noisy, especially when the products are made of glass due to repeated impacts between the products. In addition, these solutions are not perfectly controlled, giving random movement to the products.

In addition, in the case of several upstream flows, such a solution induces difficulties in synchronizing the downstream machine, depending on the processing hazards of the machines located upstream.

The object of the invention is to overcome the drawbacks of the state of the art by proposing a product conveying device making it possible to receive several distinct flows of products for transferring them to a single outlet, with less bulk, better reliability, an improved rate, especially for fragile products, as well as reduced noise.

Thus, the invention relates to a device for conveying products within an industrial line for the production and processing of said products, comprising:

- an outlet in the form of an outlet conveyor provided with a single movable surface in a drop-off area;

- on both sides, along the outlet at least one surface for receiving said products;

- At least one entry for each reception surface, each entry along the opposite edge of each reception surface with respect to said exit;

This device is characterized by the fact that it further comprises:

- at least one product transfer transfer tool from at least one receiving surface to the output;

- For each entry at least one product transfer transfer tool from said entry to a receiving surface.

Additionally, but in no way limiting, the device may include a single output transfer tool.

The output conveyor can be multi-wire.

The surface of the outlet conveyor may comprise at least a first section and a second section which are separate and motorized independently.

Each entry may include a single-line entry conveyor.

The device may comprise, on one side of the entrance situated opposite said reception surface, an additional reception surface with at least one additional entry along the edge opposite to said entry and at least one additional tool for transferring the products from said additional entrance to said additional receiving surface.

Each receiving surface can constitute a product accumulation surface.

The invention also relates to a method for managing the transfer of products within an industrial production and processing line for said products, in which:

- A single output is supplied with products by transfer from a first surface for receiving products supplied from a first input, and from a second surface for receiving products supplied from a second input, the first and second inputs being located opposite

of said output by compared to said first and second surfaces reception. This process East characterized in this that: it consists at less at : - determine the quantity of products sure each of

first and second receiving surfaces in the vicinity of said outlet;

- order the transfer of products as appropriate:

a) at least one line from said first receiving surface,

OR

b) at least one queue from said second receiving surface

OR

c) simultaneously of at least one queue from said first receiving surface and at least one queue from said second receiving surface.

Additionally, but in no way limiting, such a

process may consist to order the transfer of products according to case: a) of many lines since said first area of reception, OR b) of many lines since said second area of

reception.

Other characteristics and advantages of the invention will emerge from the detailed description which follows of nonlimiting embodiments of the invention, with reference to the appended figures in which:

- Figure 1 schematically shows a top view of an example of a conveying device, comprising a single double-file outlet symmetrically surrounded by two receiving surfaces from single-line inlets;

- Figure 2 schematically shows a view in vertical section of an exemplary implementation of the invention, showing a first step of transferring products from a receiving surface located on the left towards the outlet; and

- Figure 3 schematically shows a view similar to Figure 2, showing another step following the transfer visible in Figure 2, during which an output transfer tool is moved to the other receiving surface located on the left for transfer the products located there.

The present invention relates to the conveyance of products 1 within an industrial production and processing line for said products 1.

Such products 1 can be bottles, cans, flasks, boxes, cases, cartons or bundles, in any type of material, in particular glass or plastic, or even cardboard. Such products 1 are generally intended to contain liquids or food.

With a view to their processing along said industrial line, the products 1 are routed between different stations. To this end, the invention relates to a device 2 for conveying said products 1.

Such a device 2 is particularly suitable for allowing the conveying of one or more product flows 1 from one or more stations located upstream to a station located downstream.

The conveying device 2 comprises an outlet 3 in the form of an outlet conveyor 30 provided with a single movable surface in a deposit area. The deposit zone corresponds to the surface of the outlet conveyor to which the products are transferred 1. Typically, this zone extends between the reception surfaces 4 and does not extend longitudinally beyond these surfaces 4. This single mobile surface can receive products 1 over all or part of its width. It extends at least along the length of said depositing zone, preferably at a given time, namely that of depositing the products. The single movable surface therefore makes it possible to receive a group of products 1 according to one or more transfer steps and to evacuate this group in one go, necessarily simultaneously.

Such an output conveyor 30 can be single-wire but preferably multi-wire, namely that its surface includes a width making it possible to receive a line but preferably several lines of products 1.

Said outlet conveyor 30 can be of the endless belt type.

According to one embodiment, its movable surface can comprise a single mat.

According to another embodiment, the surface of the outlet conveyor 30 can comprise at least a first section and a second section which are separate and motorized independently, conferring different displacements of the sections along said outlet conveyor 30. The two sections follow one another along the outlet conveyor 30. Therefore, when a first section is positioned at a stop at a given time along the depositing zone, at least one other section, loaded with products 1 before, can move. Once the products 1 loaded on the first section, it can be moved, preferably with sufficient acceleration to catch up with the second surface, until abutment and achieve continuity of these two sections. Then, the second section returns to empty to reposition itself along the drop zone. The cycle can then be repeated, vice versa with the second section stopped.

Thus, when it is positioned in the drop-off zone, only one of the sections at a time receives products 1 with a view to conveying them via outlet 3.

On both sides, along the outlet 3, the device 2 comprises at least one receiving surface 4 for said products 1. In sum, two receiving surfaces 4 are arranged on each side of the outlet 3. The conveyor of outlet 30 is surrounded by two receiving surfaces 4. Each receiving surface 4 extends along at least part of the longitudinal edge of said outlet conveyor 30. The above-mentioned deposit area corresponds to at least part of the length receiving surfaces 4. The receiving surfaces 4 extend transversely with respect to the longitudinal direction of movement of the products 1 along the outlet conveyor 30.

The receiving surfaces 4 are in principle abutted and flush with the upper face of the outlet conveyor 30. A junction surface 40, such as a fixed plate called "dead", can be added to ensure flush between a surface 4 and the surface of the exit conveyor 30.

As visible in the example of FIG. 1, the products 1 are moved transversely on the reception surfaces 4, in a convergent manner, towards the exit 3, until arriving along the edge of each reception surface 4 along the exit. 3, along the drop zone. These movements are preferably orthogonal to the longitudinal direction of conveying the products 1 on the outlet conveyor 30.

Each receiving surface 4 can constitute a product accumulation surface 1. Consequently, several longitudinal lines of products 1 can be received on one and / or the other of the receiving surfaces 4. Preferably, the products 1 are moved transversely on the receiving surfaces 4 and accumulated as close as possible to the outlet 3, with a view to their transfer to the outlet conveyor 30 at the deposition zone and their evacuation by the single movable surface.

The reception surfaces 4 can in particular be represented by conveyors, in particular of the endless belt type.

As such, the device 2 comprises at least one outlet transfer tool 6 for the products 1 from at least one receiving surface 4 towards the outlet 3. Such an outlet transfer tool 6 operates from one and / or the other. 'other receiving surface 4 towards the deposit area to move the products 1 to the outlet 3.

The device 2 can include an outlet transfer tool 6 for each receiving surface 4, but preferably it includes a single outlet transfer tool 6. This single tool 6 is provided for moving to take products 1 from one and / or the other of the receiving surfaces 4, to move them to the outlet 3 in the drop-off area.

The mobility of each tool 6 is ensured by suitable means, in particular a motorization by means of a multi-axis robotic arm or along sliding and transverse displacement guides (of the “Cartesian robot” type), in particular by via a pulley and belt drive, or a motorization in the form of linear motors.

Thus, each tool 6 can move along a forward transfer path from the top of a receiving surface 4 to above the outlet 3, and conversely along a return path, empty without transferring products 1, from the top of the outlet 3 to a receiving surface 4. Thus, in the case of a single tool 6, it can move to move from one of the receiving surfaces 4 to the outlet 3 and return to one or the other of the receiving surfaces 4. As can be seen in FIG. 3, this return can take place through an elevation of the outlet tool 6 vertical to the outlet 3, then a displacement in translation transversely relative to the direction of longitudinal movement along said outlet 3, before descending to the right of one and / or the other of the receiving surfaces 4, in the lowered position in order to again transfer products 1 which there are stored or accumulated.

Examples of several transfer steps are shown in Figures 2 and 3, first showing a transfer of several rows of products 1 from a first receiving surface 4, located on the left, to the outlet conveyor 3. All products 1 transferred are then evacuated along the single outlet 3, while the tool 6 is moved to transfer rows of products 1 located on the other receiving surface 4, located on the right. Such a tool 6 then ensures an alternating transfer of the products 1 from one then from the other of the receiving surfaces 4.

In a non-exhaustive manner, a transfer mode makes it possible to move products 1 from a receiving surface 4 to the outlet 3 in the deposit area before evacuating them. Another transfer mode makes it possible to first move products 1 from a first receiving surface 4 to the depositing zone, then to move other products from the second receiving surface 4 to said depositing zone, before placing them evacuate onto the single moving surface. Another transfer mode can consist of a succession of several transfers of products 1 from the same receiving surface 4 to the outlet 3 before simultaneously evacuating all of the products transferred to the single mobile surface of the depositing area.

Yet another operation can consist of a tool 6 ensuring a simultaneous transfer of one or more lines of n

products 1 from each of the receiving surfaces 4 to the outlet 3.

Such a transfer tool 6 ensures the displacement, for example by translation of several products 1, per line. It tightens the product columns during their transfer to the drop-off area.

A transfer tool 6 can transfer the products 1 by pushing transversely, preferably orthogonally from at least one receiving surface 4 to the outlet 3. The tool 6 can comprise at least one pusher, in the form of a rod or bar but preferably in the form of at least one substantially vertical plate 60, preferably several plates 60 arranged parallel to each other and extending along the longitudinal direction. The plates 60 are spaced apart according to an interval, configurable or not, depending on the dimensions of the products 1, in particular their diameter. Consequently, a row of products 1 can be surrounded by two plates 60. Each plate 60 extends vertically. Thus, the number of plates 60 determines the number of rows of products 1 that it is possible to transfer in a single movement of the tool. An example of such a tool 6 is shown in FIGS. 2 and 3, showing three plates 60 allowing simultaneously to transfer one, two rows or three rows of products 1.

Another transfer tool 6 can transfer the products 1 by gripping, in particular from above by means of tulips coming to grip the upper parts of said products 1, for example their neck. Another gripping may include clamps coming to grip the products 1 on their side (s). Once seized, the products 1 can be lifted before being moved laterally, towards the outlet 3 where they are deposited. In a related way, once entered, the products 1 can simply be slid onto the receiving surface 4 and the surface of the outlet 3.

It is understood that gripping by seizing the products 1 requires tools and a configuration depending on the shape and dimensions of the products, as well as their positioning, but allows the products to be attached. A transfer tool 6 with plates 60 makes it possible to adapt to several formats and dimensions of products 1, even if they are not perfectly aligned, but two rows of products 1 transferred simultaneously are spaced at least from the thickness of the pusher .

The device 2 comprises at least one inlet 5 for each receiving surface 4. Each inlet 5 runs along the opposite edge of each receiving surface 4 relative to said outlet 3. Each inlet 5 is therefore on the other side relative to the outlet drop-off area 3. In sum, each receiving surface 4 therefore includes its inlet 5.

Preferably, each inlet 5 extends parallel to the longitudinal direction of the outlet 3.

Consequently, two opposite longitudinal edges of each receiving surface 4 adjoin an edge of its inlet 5 and one of the edges of the outlet 3.

Preferably, the surface of each entry 5 is abutted with its receiving surface 4, flush with the upper face.

An inlet 5 can comprise at least one multi-wire but preferably single-wire input conveyor.

Preferably, the upper faces of the outlet 3, of the inlets 5 and of the reception surfaces 4 extending outwards, substantially in the same plane. They can be horizontal or substantially horizontal.

Further on, an entrance 5 may include a transit zone 50 extending along the edge of its adjacent reception surface 4 and a zone 51 situated upstream supplying said transit zone.

Said upstream zone 51 of an inlet 5 can be single-wire or multi-wire, preferably single-wire. The transit zone 50 can be single or multi-wire. In addition, an upstream zone 51 can be single-wire and supply a transit zone 50, for example multi-wire, in particular of two rows of products 1, for example through a splitting of said single-wire flow coming from the upstream zone 51. Such a zone transit 51 makes it possible to absorb a continuous flow of products coming from the upstream area 51, despite displacements of products 1 towards the receiving surface 4 carried out discontinuously when the products are stopped.

The conveying device 2 comprises for each inlet 5 at least one product inlet transfer tool 1 from said inlet 5 to a receiving surface 4. In sum, each inlet 5 has its own tool, ensuring the transfer of the products 1 from entrance 5, in particular its transit zone 50, to the adjacent reception surface 4.

In addition, such a transfer from an inlet 5 is carried out transversely, towards the outlet 3. Preferably, the transfers at inlet 5 and at outlet 3 are carried out parallel, orthogonal to the directions of conveying and displacement of the products 1 the along each entry 5 and along exit 3.

The input transfer tool can be similar to an output transfer tool 6.

According to another embodiment, an entry transfer tool can extend from an entry 5 over all or part of a receiving surface 4, in order to allow the movement of the products 1 from an entry 5 to a location of the adjacent receiving surface, in particular as close as possible to the edge adjoining the outlet 3. Such a displacement from the inlet 5 to the closest to the outlet 3 makes it possible to optimize the quantity of products 1 stored on each surface reception 4.

According to one embodiment, not shown, the conveying device 2 can comprise, on one side of an inlet 5, situated opposite a receiving surface 4, an additional receiving surface with at least one additional inlet along the edge opposite to said entry 5. In sum, a third entry may be provided on one side of one of the entries 5, or even a fourth. This additional entry is separated from an entry 5 by an additional receiving surface, allowing products to accumulate therein. In addition, the device 2 comprises at least one additional product transfer tool 1 from said additional entry to said surface. additional reception. This tool can also make it possible, as the case may be, to move the products 1 from the additional entry to as close as possible to the entry 5. Another tool or the tool of the entry 5 can ensure the movement of the products 1 accumulated on the additional receiving surface towards the entrance 5.

The invention envisages managing different transfer possibilities, in particular as a function of the quantity of products 1 accumulated on both of the receiving surfaces 4.

To do this, the invention also relates to a product transfer management method 1. Such a management method is preferably provided for the implementation of the conveyor device 2 according to the invention.

As mentioned above, a single outlet 3 is supplied with products 1 by transfer from a first a receiving surface 4 for products 1 supplied from a first inlet 5 and from a second receiving surface 4 for products 1 supplied from a second inlet 5. The first and second inlets 5 are located opposite said outlet 3 with respect to said first and second receiving surfaces 4. Such a configuration is visible in FIG. 1.

Advantageously, the quantity of products 1 is determined on each of the receiving surfaces 4 near said outlet 3. This determination can be obtained at inlet 5, by detection and counting of the products 1 arriving from inlet 5, in particular during their passage within the transit zone 50. Thus, each quantity of products 1 is known with exactitude, in particular the number of lines, accumulated on each reception surface 4 and which can be transferred to the outlet 3.

Consequently, the transfer of products 1 is controlled, depending on the case, of at least one queue from said first receiving surface 4, or at least one queue from said second receiving surface 4, or at least one queue from said first receiving surface 4 and at least one line from said second receiving surface 4. In sum, depending on the presence of a sufficient quantity of products 1 on one and / or the other of the surfaces of reception 4, the invention makes it possible to choose which transfer to perform, from one or other of the reception zones 4, or even from each reception zone 4.

Further, in the case of a transfer of products 1 from the two receiving surfaces 4 to the outlet 3, it is possible to carry out an alternating transfer first with a first transfer step from a first receiving surface 4 , then perform a second transfer step from the other receiving surface 4. At each step, one or more product lines 1 can be transferred from each of said receiving surface 4.

Another possibility may consist in simultaneously transferring one or more product lines from each of the receiving surfaces 4 to the outlet 3. In this case, the outlet transfer tool 6 must be adapted to operate simultaneously.

Consequently, the tool can have at least two members, of the pusher or gripping type, movable in spacing and approaching one with respect to the other. Thus, it is possible to position the members by spreading them at the level of the products 1 present on the two receiving surfaces 4, in order to bring them closer during (or) simultaneous transfer (s) (or not) of the products 1 from the surfaces reception 4 to the exit 3 drop-off area.

In either case, for example, a line of products 1 can be transferred from the first receiving surface 4 while two queues can be transferred from the other receiving surface 4. The outlet 3 is then finds itself loaded with three rows of products 1, which they can then evacuate. Another possibility may

consist see you first transfer a or many lines of products 1 present sure a surface of reception 4, which East replenished in products 1 since his entry 5 during the transfer or by displacement of said area of

reception 4, before carrying out a new transfer from this same reception area 4 of the products 1 which have just been brought closer to the edge of the drop-off zone of the outlet 33. It is only then that all the products 1 transferred and present on the drop-off zone are evacuated from exit 3.

Preferably, during the transfer (s), the drop-off area of the outlet 3 is stopped.

Preferably, a single transfer operation is carried out between each evacuation.

Preferably, the management method according to the invention can control the transfer of products 1, as the case may be, only alternately, namely that one chooses to transfer at least one file of products from said first receiving surface 4 before evacuating them. , or to transfer at least one file of products from said second receiving surface 4 before evacuating them.

Thus, it is possible to have several product flows 1 coming from as many stations upstream, in particular in a single line at the filling or labeling outlet, to supply as many inputs 5. The invention makes it possible to transform several flows from separate machines at inputs 5 to a single flow to pool them and supply a single machine located downstream. The products 1 are then accumulated on one and / or the other of the receiving surfaces 4, before being transferred to the single outlet 3 which evacuates them to a station located downstream. The management of the transfer makes it possible to improve the accumulation of products 1 and their transfer, in particular with a view to evacuating several rows of products 1 at once, for example with a view to feeding a shrinkwrapper. The invention provides better flexibility in the event of an unexpected upstream position, especially if they work individually, and makes it possible to improve the production rate. The invention also makes it possible to avoid passing through a bulk and to get rid of the defects inherent in a bulk arrangement of the products mentioned above (large footprint, impacts between the products, incompatibility with the treatment of certain products , noise...) . The products remain aligned and the output configuration can be easily modulated (number of lines). The synchronization between the different stations is also improved.

Claims (9)

1. Device (2) for conveying products (1) within an industrial production and processing line for said products (1), comprising: - an outlet (3) in the form of an outlet conveyor (30) provided with a single movable surface in a deposit area; - on either side, along the outlet (3) at least one receiving surface (4) of said products (1); - at least one entry (5) for each receiving surface (4), each entry (5) running along the opposite edge of each surface of reception (4) by compared to said outlet (3); characterized by the fact than said device (2) of conveying includes outraged : - at least one tool transfer Release (6) of products (1) from at least one surface reception towards the exit ; - For each inlet (5) at least one product transfer transfer tool (1) from said inlet (5) to a receiving surface (4). 2. Conveying device (2) according to claim 1, characterized in that it comprises a single outlet transfer tool (6). 3. Conveying device (2) according to any one of the preceding claims, characterized in that the outlet conveyor is multi-wire. 4. Conveying device (2) according to any one of the preceding claims, characterized in that said surface of the outlet conveyor (30) comprises at least a first section and a second section separate and motorized independently. 5. Conveying device (2) according to any one of the preceding claims, characterized in that each entry (5) comprises a single-line entry conveyor. 6. Conveying device (2) according to any one of the preceding claims, characterized in that it comprises on one side of the inlet (5) located opposite to said receiving surface (4), an additional receiving surface with at least one additional entry along the edge opposite said entry (5) and at least one additional product transfer tool (1) from said additional entry to said additional receiving surface. 7. Conveying device (2) according to any one of the preceding claims, characterized in that each receiving surface (4) constitutes a product accumulation surface (1). 8. Method for managing the transfer of products (1) within an industrial production and processing line for said products (1), in which: - products (1) are supplied with a single outlet (3) by transfer from a first receiving surface (4) of products (1) supplied from a first inlet (5), and from a second receiving surface (4) of products (1) supplied from a second inlet (5), the first and second inlets (5) being located opposite said outlet (3) relative to said first and second receiving surfaces (4), characterized in that '' it consists of at least: - determine the quantity of products (1) on each of the first and second receiving surfaces (4) near said exit (3); - order the transfer of products as appropriate: a) at less a girl since said first area of reception (4) OR b) at less a girl since said second area of reception (4), OR according to a queue from said at least one queue from (4). claim 8, to order the transfer of c) simultaneously from at least first receiving surface (4) and said second receiving surface 9. Management method characterized in that it consists of products (1) as appropriate: a) several queues since reception (4), OR b) several queues since reception (4). said first area of said second area of