EP1189731B1 - Method and installation for making abrasive grinders and grinder obtained by said method - Google Patents

Abstract

An abrasive product is formed, in a blank making machine, into a layer forming a blank consisting of at least abrasive grains which is then set atop on at least another material layer and assembled thereto. The installation comprises, besides at least a blank making machine, an assembly line (2) along which are successive posts (21, 22, 23, 24, 25, 26, 27, 28) at the site whereof the elements designed to form the grinder are set on top of one another to form a stack and a station (29) for heating said stack, and at least a pressing machine (3) to compress the heated stack. Another embodiment of the invention does not include the heating station (29). The grinder is a thin grinder comprising at least a reinforcing layer pierced with hole wherein the abrasive product is distributed. The invention is useful for making grinders for parting, machining or pumicing.

Description

The invention relates to the manufacture of abrasive wheels, and more precisely a method and an installation for manufacturing such wheels, as well as mills obtained, see GB-A-673 334, which describes the preamble of claims 1 and 7 and a wheel, of the type thin wheel, having at least one layer formed from abrasive grains and two layers not containing abrasive grains.

At present, to make abrasive grinding wheels of the type "Thin grinding wheel" (having a thickness of a few millimeters), example the cut-off wheels, generally, we have in a mold placed on a production tray, a central ring around which one Stacks layers of various materials to form the wheel; by example, a protective sheet called "paper" is deposited. superimposes a reinforcement sheet called "fabric" which is pierced with holes that can be defined by meshes if the sheet has a woven structure, pours on the reinforcing sheet a powder product formed from grains abrasives comprising a coating constituted by a binder so that this product is distributed in the holes of the reinforcement sheet and is also a layer superimposed on this reinforcement sheet, the product layer is scraped off powder to reduce its thickness to the desired value, one superimposes a second reinforcement sheet to the powdery product layer, and then, if the grinding wheel to manufacture is of the type with a single layer of abrasive (called grinding wheel "Monolayer"), a second so-called protective sheet is superimposed "Paper" to this reinforcement sheet, and press in a press the whole thus constituted, while to manufacture a mill with several layers of abrasives (so-called "multilayer" grinding wheel), before superimposing this second sheet of protection and compress, alternately, one pours as many times as a layer of the powdery product and is superimposed so many times a sheet of reinforcement, that requires the type of grinding wheel to manufacture.

The automatic implementation of this process is generally on a rotary table of generally circular shape with sectors are arranged as workstations; each station is equipped with several identical tools to perform the same task simultaneously on the several molds, the first task being the establishment of the ring, and the last being the unloading of the grinding wheels after pressing, this one being realized on the table.

In relatively simple installations that are not intended to make a very large number of grinding wheels, the rotary table can for example, to include six positions (for setting up the ring, place of the "paper", the laying of the "fabric", the discharge of the powdery product and scraping by means of a sliding drawer tool, the installation of the second "fabric", the establishment of the second "paper", the pressing and the unloading) and four tools per station, which requires that the table already has an area of several square meters; a bigger job specialization quickly leads to eight-station facilities, and the need to manufacture a larger quantity, to each have nine tools.

Tasks can be spread across multiple rotating tables between which the sets being manufactured need to be transferred, and this especially as the number of layers of powdery products so tooling with drawers must be higher.

It can be seen that already in the simple case of a rotary table with six four tools, 24 tools must be available, the cost of which individual is very high.

In addition, the speed of rotation of the table is imposed by the duration of the longest task that is usually the spill of the product powder and its scraping, or pressing if it is carried out in continuity with the previous tasks.

In addition, the inevitable accidental spill of powdery product formed from abrasive grains, even in very small quantities, out of the mold, leads to rapid wear of the rotary table and tools that are associates, in particular drawer tools whose sliding becomes difficult ; the change of even a single tooling leads to the immobilization of the rotary table and thus the stop of the manufacture.

Also, every time we want to make wheels of a different type, it is necessary to change a large number of tools.

As a result, the actual "availability" time of the table rotary, for the manufacture of grinding wheels, is relatively small.

In addition, the installation is not very scalable because it is practically it is impossible to add workstations or tools on the rotary table.

In addition, the pressing to be carried out under high pressure on several sets simultaneously, it is necessary to develop efforts very important and so use materials and devices with high mechanical resistance.

Finally, the distribution of the powdery product on the surface of the "fabric" is difficult to master, and we see on the wheels an unbalance more or less important to cause the disintegration of the wheel during its use at high speed.

The object of the invention is to remedy these drawbacks and For this purpose, a method of manufacturing grinding wheels comprising an abrasive product, thin-wheel type as claimed in claim 1. The method comprises a step of superimpose at least two constituent layers, one of which is a slab at least from abrasive grains, and to assemble these at minus two layers of constituent.

"Constituent layer" means a layer comprising at least one least a material intended to constitute the grinding wheel. These materials are in particular of the type of protective sheet called "paper", or of the type sheet of so-called "fabric" reinforcement, or of the type of a layer formed from abrasive grains comprising a coating constituted by a binder.

The term "slab" means a constituent layer which has a consistency such as the slab can be manipulated, and in particular grasping and moved by hand or using a machine.

According to one embodiment of the invention at least one slab is consisting of adhesive grains coated with a binder.

According to another variant of the invention, at least one slab comprises, in addition to abrasive grains coated with a binder, at least one layer component without abrasive grain, especially a reinforcing sheet, especially made from glass fibers.

Thanks to the fact that one makes first of all a cake, and that one then superimposes the different layers, the time of passage at each post can be significantly reduced since it no longer depends on the duration spill operations of the powdery product or pressing under high pressure.

• pour fabriquer la galette, on déverse dans un moule un produit abrasif formé à partir de grains abrasifs comportant un enrobage constitué par un liant, on égalise le niveau de produit abrasif à une valeur voulue, et on comprime le produit abrasif ;
• on pose successivement l'une sur l'autre des couches de constituant comprenant au moins une galette pour constituer une pile, puis on chauffe la pile, et ensuite on presse la pile ;
• on superpose les couches de constituant le long d'une ligne d'assemblage équipée de postes de pose des couches le long de laquelle on fait défiler les couches en superposition sous la forme de piles, et dans au moins certains postes on constitue des stocks de piles où l'on prélève une à une les piles stockées pour y superposer une nouvelle couche de constituant, et on évacue du poste la pile munie de sa nouvelle couche vers le poste suivant.

The method may also have one or more of the following features:

• to manufacture the wafer, an abrasive product formed from abrasive grains having a binder coating is poured into a mold, the level of abrasive product is leveled to a desired value, and the abrasive product is compressed;
• successively laying one on the other constituent layers comprising at least one wafer to form a stack, then the battery is heated, and then the battery is pressed;
• the constituent layers are superimposed along an assembly line equipped with laying stations for the layers along which the superposed layers are made to run in the form of piles, and in at least some positions stocks of piles where one takes one by one stored batteries to superimpose a new layer of constituent, and is evacuated from the station the battery with its new layer to the next station.

In a variant according to the invention, when the cake comprises at least one layer of component free of abrasive, it is first poured into the mold an abrasive product formed from abrasive grains having a coating constituted by a binder, the level of abrasive product is equalized to a desired value, then at least one further layer of abrasive-free, including a reinforcement sheet, above the level of the abrasive product and the assembly consisting of at least one sheet of reinforcement and abrasive product.

This last variant is particularly adapted to the realization so-called "extra-thin" wheels whose thickness is, for example, less than 2 mm, or even equal to or less than 1 mm. This particular type of grinding wheel is generally consists of a "monolayer" grinding wheel, and asks to be made with the utmost care to avoid problems of unbalance or lack of product in certain areas of the grinding wheel which are particularly acute when producing this type of grinding wheel by traditional methods. We notes indeed that the reinforcement layers are poorly distributed in the millstone. The method according to the variant of the invention, where a slab is produced having a reinforcing sheet placed on a layer of abrasive in a mold to manufacture said cake, makes it possible to overcome significantly problems of unbalance and lack of product in certain areas of the grinding wheel and thus greatly increase the production yields of grinding wheels extra-thin.

In fact, first depositing the abrasive grains and then reinforcing foil and then squeezing the whole makes it possible to obtain a cake planar and parallel faces where the reinforcing sheet has been well maintained in place against the upper face of the mold during the pressing operation. Stacking at least one other constituent layer on said slab is with a flat reference surface and makes it possible to obtain, after pressing, the set, a grinding wheel where the reinforcing sheets are distributed in a plane way and controlled in the grinding wheel. It is then possible to manufacture "extra-thin" wheels Of 0, 5 mm or even 0.4 mm thick, or even grinding wheels monograins in the thickness.

In addition, it is possible to automate, partially or totally a grinding line based on the principle of this method.

The invention also relates to a mill manufacturing facility comprising an abrasive product, of the type thin grinding wheel, as claimed in claim 7. This installation comprises in a variant at least one machine for making pancakes from grains abrasives, an assembly line including, in particular, succession on the basis of which layers intended to constitute the grinding wheel and comprising at least one slab from the manufacture of pancakes are superimposed to form a stack of layers superimposed, followed by a heating station where the stack of layers is heated, and at least one pressing machine for compressing the battery, this pressing machine being in the form of a pressing station at the end of the line assembly or following the assembly line.

Thanks to the fact that the installation comprises on the one hand a machine of manufacture of patties and, secondly, an oven and a pressing station, the pressing operations can be performed under moderate pressure.

• la machine de fabrication de galettes comporte une table de fabrication rotative équipée de moules et des postes de travail spécialisés comprenant un poste de déversement d'abrasif, un poste d'égalisation, un poste de pressage, un poste de déchargement et un poste de nettoyage, et elle comporte également une table d'entreposage pour entreposer les galettes fabriquées ; pour des raisons d'encombrement, il est possible de prévoir une installation où la machine de fabrication de galettes comporte un ou des postes, où deux ou plus opérations décrites ci-dessus sont réunies en un même poste. On choisira de préférence une machine où le poste de déversement d'abrasif et d'égalisation sont réunis, notamment pour la fabrication de meules extra-minces,
• la ligne d'assemblage comporte un convoyeur progressant en circuit fermé et portant des plateaux fixes adaptés pour recevoir des plateaux amovibles adaptés pour recevoir des piles d'éléments constituants de la meule,
• la ligne d'assemblage comporte un poste de pose de bague, des postes de pose de couche de constituant et un poste de chauffage,
• la ligne d'assemblage comporte au moins un poste comprenant un dispositif de stockage provisoire.

The installation may also have one or more of the following characteristics:

• the wafer making machine comprises a rotary manufacturing table equipped with molds and specialized workstations comprising an abrasive discharge station, an equalization station, a pressing station, an unloading station and a cleaning station and it also includes a storage table for storing the manufactured slabs; for reasons of space, it is possible to provide an installation where the wafer manufacturing machine has one or more positions, where two or more operations described above are combined in one station. It is preferable to choose a machine where the abrasive discharge and equalizing station are joined, in particular for the manufacture of extra-thin grinding wheels.
• the assembly line comprises a conveyor progressing in a closed circuit and carrying fixed trays adapted to receive removable trays adapted to receive stacks of constituent elements of the grinding wheel,
• the assembly line comprises a ring setting station, constituent layer laying stations and a heating station,
• the assembly line comprises at least one station comprising a temporary storage device.

It should be noted that, the use of an oven to heat the battery, before pressing, is optional. We have indeed found that we obtain excellent results on the wheels produced without operating this heating before pressing, especially in cases where the pile is not thick, which particularly suitable for making extra-thin grinding wheels.

• les éléments précédents sont disposés autour d'une table de fabrication rotative sur laquelle est fixé au moins un moule,
• la table de fabrication rotative est divisée en secteurs correspondant à des postes de travail pour des opérations consécutives, chaque secteur comprend au moins un emplacement X pour un moule et au moins un emplacement Y, sur lequel on peut disposer une ou des couches de constituant d'une meule.

The installation may also have one or more of the following characteristics:

• the preceding elements are arranged around a rotary manufacturing table to which at least one mold is attached,
• the rotary manufacturing table is divided into sectors corresponding to workstations for consecutive operations, each sector comprises at least one location X for a mold and at least one location Y, on which one or more layers of constituent of a millstone.

• dépose et égalisation des grains abrasifs enrobés d'un liant dans un moule situé sur un emplacement X du secteur, notamment à l'aide d'un outil, et dépose d'au moins une couche de composant, notamment une couche de protection sur un emplacement Y dudit secteur,
• dépose d'au moins une couche de composant, notamment une feuille de renfort sur les grains abrasifs dans le moule et dépose d'au moins une couche de composant, notamment une feuille de protection et/ou une feuille de renfort sur un emplacement Y,
• un pressage à l'aide de la machine destiné à former au moins une galette de pressage à partir des couches de constituant contenues dans au moins un moule,
• une constitution de la pile qui consiste à prendre au moins une galette d'un emplacement X pour la poser sur un emplacement Y et constituer ainsi au moins une pile formée par les couches de constituant préalablement disposées dans un emplacement Y par au moins et une galette,
• une pressage de la pile située sur l'emplacement Y pour consolider une meule à l'aide de la machine de pressage,
• évacuation de la ou des meules.

According to an advantageous variant, the rotary manufacturing table is divided into several sectors, each sector respectively corresponding to the workstations where the following consecutive operations are performed:

• depositing and equalizing the abrasive grains coated with a binder in a mold located at a location X of the sector, in particular by means of a tool, and depositing at least one component layer, in particular a protective layer on a Y location of said sector,
• depositing at least one component layer, especially a reinforcing sheet on the abrasive grains in the mold and depositing at least one component layer, in particular a protective sheet and / or a reinforcing sheet on a location Y,
• pressing with the machine for forming at least one pressing wafer from the constituent layers contained in at least one mold,
• a constitution of the stack which consists in taking at least one wafer from a location X to place it on a location Y and thus constitute at least one stack formed by the constituent layers previously arranged in a location Y by at least one wafer ,
• pressing the stack located on the location Y to consolidate a grinding wheel using the pressing machine,
• evacuation of the grinding wheel (s).

In this configuration of the installation, the manufacturing machine slab is integrated into the assembly line. It should be noted that it is also possible to make an installation with the elements arranged in line.

• la machine de pressage comporte une table rotative équipée de presses à vérin comportant un outillage mobile comprenant un moule comportant un fond et une paroi latérale montée coulissante autour du fond, et un support de moule fixé au piston du vérin et auquel le fond et la paroi latérale sont solidarisés par des dispositifs à ressorts adaptés pour soumettre la pile à un effort de pressage en la faisant entourer par la paroi latérale, lors de l'extension du vérin, et pour entraíner le début de la remontée de la paroi latérale tandis que le fond est toujours contre la pile, puis la remontée du fond tandis que la paroi latérale poursuit sa remontée, lors de la rétraction du vérin,
• la machine de pressage comporte des presses munies chacune d'un support pour un plateau amovible adapté pour recevoir une pile de couches de constituants de la meule, et une surface de came parcourue par des galets solidarisés chacun à un support pour élever le support en vue de l'évacuation de la meule et du rechargement du plateau amovible sur la ligne d'assemblage.

Each of the facilities described above may also have one or more of the following features:

• the pressing machine comprises a rotary table equipped with jack presses comprising a mobile tool comprising a mold having a bottom and a side wall slidably mounted around the bottom, and a mold support fixed to the piston of the jack and to which the bottom and the wall lateral are secured by spring devices adapted to subject the stack to a pressing force by making it surround by the side wall, during the extension of the jack, and to cause the beginning of the rise of the side wall while the bottom is still against the pile, then the rise of the bottom while the side wall continues to rise, during the retraction of the cylinder,
• the pressing machine comprises presses each provided with a support for a removable tray adapted to receive a stack of layers of constituents of the grinding wheel, and a cam surface traversed by rollers each secured to a support for raising the support in order to removing the wheel and reloading the removable tray on the assembly line.

According to a variant of the invention, the arrangement of the elements of pressing could be reversed, with the removable tray located above the mold. In this variant, the battery to be pressed on the bottom of the mold, then the bottom of the mold and mold until the sidewalls of the mold come in contact with the underside of the tray to close the mold and to be able to start the pressing operation.

The invention also relates to a grinding wheel comprising a product abrasive, of the type thin wheel, manufactured by the method defined above. This grinding wheel may comprise at least one reinforcing layer pierced with holes in which is distributed part of the abrasive product, which is formed to from abrasive grains.

• elle comporte une bague centrale,
• elle comporte au moins une couche de produit abrasif, et chaque couche de produit abrasif est intercalée entre deux couches de renfort,
• son épaisseur est inférieure ou égale à 2 mm, voire inférieure ou égale à 1 mm.

The wheel may further have one or more of the following features:

• it comprises a central ring,
• it comprises at least one layer of abrasive product, and each layer of abrasive product is interposed between two reinforcing layers,
• its thickness is less than or equal to 2 mm, or even less than or equal to 1 mm.

It is possible to separate grain handling activities abrasives from the final manufacturing area of the grinding wheels. This installation is particularly advantageous because the abrasive grains can not disperse in the final manufacturing area of the grinding wheels, which makes it possible to obtain clean premises and also considerably extend the life time of machines avoiding abrasion or grain-related malfunctions of abrasives that are usually distributed throughout the workshop. manufacture of grinding wheels. In particular, significant savings can be made because it is not necessary to cool or finely regulate the temperature of the final manufacturing area because a slab is more stable thermally as the abrasive grains coated with a binder.

• la figure 1 est une vue schématique de dessus, d'une machine de fabrication de galettes adaptée pour être mise en oeuvre dans le cadre de l'invention,
• la figure 2 est une vue schématique de dessus, d'une ligne d'assemblage à laquelle est associée une machine de pressage, pour fabriquer des meules abrasives à partir des galettes fabriquées par la machine de la figure 1,
• la figure 3 est une section schématique par un plan vertical, d'une partie d'une presse équipant la machine de pressage montrée schématiquement sur la figure 2,
• les figures 4 à 6 sont des sections schématiques par un plan vertical, d'éléments de la presse dont une partie est schématisée sur la figure 3, facilitant après pressage l'évacuation des meules et le rechargement de la ligne d'assemblage, et,
• la figure 7 est une vue schématique de dessus d'une installation de fabrication de meules abrasives adaptée notamment à la variante du procédé selon l'invention où la galette A comprend au moins une couche de constituant dépourvue de grain abrasif.

Other features and advantages of the invention will emerge from the following description of a method and an installation according to this invention as well as a wheel obtained, given by way of non-limiting example and illustrated by the drawings. joints in which:

• FIG. 1 is a diagrammatic view from above, of a machine for manufacturing wafers adapted to be used in the context of the invention,
• FIG. 2 is a diagrammatic view from above, of an assembly line with which a pressing machine is associated, for producing abrasive grinding wheels from the slabs produced by the machine of FIG. 1,
• FIG. 3 is a schematic section through a vertical plane of a portion of a press equipping the pressing machine shown schematically in FIG. 2;
• FIGS. 4 to 6 are diagrammatic sections through a vertical plane of elements of the press, part of which is shown diagrammatically in FIG. 3, facilitating, after pressing, the evacuation of the grinding wheels and the reloading of the assembly line, and
• Figure 7 is a schematic top view of an abrasive grinding wheel facility adapted in particular to the variant of the method according to the invention wherein the wafer A comprises at least one constituent layer devoid of abrasive grain.

According to the invention, the manufacture of an abrasive wheel does not include no step of pouring on a layer of reinforcement called "fabric", a pulverulent abrasive product formed from abrasive grains but on the other hand a step of manufacturing from such abrasive grains having a coating constituted by a binder, an abrasive slab that can be used in as a constituent layer in the manufacture of the grinding wheel; for this purpose, can for example superimpose this cake to a conventional reinforcement layer itself superimposed on a layer called "paper", and cover it with a second layer of reinforcement which is in turn covered by a "paper" for constitute a so-called "monolayer" wheel (that is to say a single layer abrasive); one can also, in order to constitute a multilayer wheel, superimpose on a reinforcement layer as many times a slab and a new reinforcement layer that this is necessary to get the features required.

The machine 1 for making pancakes illustrated by the diagram of the FIG. 1 comprises a rotary table 10 step-by-step general circular comprising here four sectors equipped with molds, and specialized fixed workstations for performing the different tasks or manufacturing operations on the contents of the molds when these pass in front of them; thus, several patties can be simultaneously being manufactured on the table 10. It also has a table 11 rotary storage on which the slabs made on the table 10 are aligned or / and stacked before being picked up for transfer to an assembly line.

The positions that equip the machine 1 are a spill station abrasive 12, a scraper equalizing station 13, a pressing station 14, a unloading station of the slabs 15, and a cleaning station of the table 16.

The molds, generally cylindrical in shape, have a wall side 17 within which is mounted a sliding bottom 18 adapted for sliding in the vertical direction, provided with a central core 19.

The abrasive discharge station 12 is provided at its upper part of a reservoir 121 of abrasive product consisting of abrasive grains comprising a coating constituted by a binder; at the bottom, the dumping station has a closable slot so that the product can be dumped into the mold when it is positioned under the slot, the bottom of the mold being positioned in the side wall to a depth greater than the thickness desired for the cake.

The abrasive product being spilled slightly in excess, the station equalizer 13 scrapes the product flush with the side wall 17 of the mold.

The pressing station 14 compresses the product by means of a force of the order of a few tons (or tens of thousands of newtons), forming the slab A intended to be introduced into the assembly line which will be described in the following.

The unloading station 15 transfers the slabs A from the table of manufacturing 10 at the storage table 11.

The cleaning station 16 cleans the sector of the table 10 that passes in vis-à-vis, downstream of the unloading station.

So, in this case where each of the four sectors of the table 10 is equipped with a single mold, there is simultaneously or almost a mold in filling course, a mold being scraped off, a cake being pressing, and a cake being unloaded from the manufacturing table.

Thanks to the fact that patties are ready to be introduced in an assembly line, it is easier to manufacture grinding wheels different dimensions and for example from "monolayer" grinding wheels to "multilayer" grinding wheels or to go from the manufacture of grinding wheels 115 mm in the manufacture of 125 mm wheels and conversely.

Indeed, the tools of the posts being not very complex, can in case of manufacturing change or breakdown, be exchanged very quickly.

In addition, the rotary table is of relatively small dimensions (the diameter can be reduced to a value less than one meter), and the molds, used only for the manufacture of pancakes, are of low weight (less 15 kg).

The pressing force to exert on the abrasive product to constitute the patties one by one is relatively moderate, of the order of a few tons (or tens of thousands of newtons), for about 1 second.

As a result, it is easy to reach with a table rotating four molds, a rate of 1000 pancakes per hour.

In addition, as the abrasive product does exist in the line only in the form of slabs and no longer in pulverulent form, wear of the assembly line in which the layers of constituents are stacked is significantly reduced.

The assembly line 2 illustrated by the diagram of FIG. intended for the manufacture of abrasive two-layer grinding wheels, so here in two patties.

It comprises a conveyor 20 progressing in a closed circuit, along which are allocated specialized fixed workstations to carry out respectively the different operations of manufacture of the grinding wheel proper. This conveyor carries trays fixed on it, adapted for receive removable trays 201 on which, as and when scroll of the conveyor, are stacked on one another the different elements and in particular the different layers of constituents of the grinding wheels.

More specifically, the assembly line 2 comprises in succession in the direction of travel of the conveyor 20, a central ring setting station 21, a basic "paper" laying station 22, a layer laying station lower reinforcement 23, a lower slab installation station 24, a laying a central reinforcing layer 25, a top pancake setting station 26, an upper reinforcement layer installation station 27, a stationary installation station Upper "paper" 28, a heating station 29, and an unloading station and reloading 30.

Each workstation intended to superimpose a layer of constituent has a stock of batteries each carried by a removable tray 201, and thus a short interruption in the operation of one of the posts for example due to a failure does not completely interrupt the manufacturing millstones, downstream workstations working on their stock, and upstream positions that can be ordered to increase theirs. We obtain therefore here advantageously a desynchronization of manufacturing operations.

The heating station 29 heats the batteries P which run through it at a temperature of about 50 to 80 ° C which facilitates a slight flow of the product abrasive material constituting the slabs in the holes of the reinforcing layer, by example meshes in the case of a real fabric or the like.

As each station performs a single overlay operation, the assembly line has a certain modularity and the increase of number of layers can be done by simply adding the number of positions appropriate; for example, to make three-slab wheels, to add to the assembly line that has just been described, a station of installation of patties and a reinforcing layer setting station.

In the case where the reinforcement layers or "fabrics" are delivered coated with the "paper" layer, the two immediately successive respectively of "paper" and "fabric" laying (or vice versa) are replaced by a single item.

It can be noted that the laying stations can be automated or manuals.

Following the assembly line 2, the installation includes a pressing machine 3 in which the removable plates with their contents, leaving the heating station 29, are transferred by the unloading station and reload 30; alternatively, this pressing machine could make part of the assembly line.

The pressing machine 3 comprises a rotary table of form circular system comprising, for example, six sectors equipped with identical cylinder passing in turn to a tray receiving location. Each removable tray reaching the unloading and reloading station 30 with its pounded is transferred to the cylinder press momentarily at this site, which, continuing its circular route, presses the pile on the tray and then interrupts the pressing in such a way in a disposal site, the grinding wheel produced as a result of the pressing of the still hot pile is evacuated from the press by an evacuation station and the removable tray 201 is transferred again, by the unloading station and reloading 30, on the conveyor 20. As a result of the pressing, part of the abrasive product of each slab being distributed in the holes of the layers of reinforcement, the different layers of constituents are joined together, and after cooling the grinding wheel presents its final structure.

As the abrasive product was already in the form of slabs, the duration of the pressing step is relatively low, and as each press works only on one stack, the pressing force can remain relatively moderate (of the order of 20 tons that is, about 2.10 ⁵ N).

The press 31, a part of which is schematically represented on the FIG. 3 comprises a mobile upper tool comprising a mold of pressing adapted to fit at the top around the stack P of layers of components placed on the removable plate 201, during the pressing operation, and secured to a mold support 310 attached to the end of the piston of the cylinder. This mold comprises a bottom 311 and a sliding side wall 312 around the bottom, so that the pressing force can be applied basically at the bottom 311 of the mold and thus to avoid the deterioration of the side wall 312 thereof; preferably, the side wall 312 is in two parties in order to be able to change which of the two parts that is intended to come apply against the removable tray, in case of deterioration. The bottom of mold is secured to the mold support 310 by at least one device to springs which, in the absence of stress, keep the bottom of the mold at a distance of the mold support, and which, when the bottom of the mold bears against the stack, compresses to allow the mold support to bottom of the mold and transmit to him the totality of the pressing force; Wall side of the mold is secured in the same way to the mold support, this difference that the free end of the side wall is set back (upwards) a few millimeters from the bottom, while the distance from the mold support is approximately the same as long as neither the bottom nor the side wall is supported, that is to say as long as the springs of their respective securing devices are not compressed.

Thus, when extending the cylinder downwards, the bottom 311 of the mold comes into contact with the pile P while the side wall 312 is not yet in contact with the removable tray 201. The mold support 310 pursuing its stroke, the springs compressing, the distance between the mold support and the bottom of the mold begins to diminish, and after a rapprochement of some millimeters, the side wall of the mold itself comes into contact with the removable tray 201; the mold support 310 still pursuing its course, it comes into contact with the bottom 311 of the mold and the pressing force is then applied to the pile P, while the mold support is still not in contact with the side wall 312 which, being itself in contact with the plate removable 201, prevents any lateral development of the layers of the battery P. After the desired period of time, the cylinder is retracted upwards, the support of 310 mold goes back to the beginning of the rise of the side wall 312 mold up, while the bottom 311 of the mold is still applied against the pile P, then goes back in turn while the side wall continues its ascent.

As most of the moving parts are at the top of the the risk of deterioration caused by loose abrasive grains accidentally the grinding wheel is reduced.

In order to facilitate the evacuation of the wheels of the pressing machine and the reloading of the assembly line by the removable plates 201, threaded around a pin 315 carried by the table of the pressing machine and passing through the support 314, the pressing machine comprises in part lower a cam surface 316 traversed by a roller secured by a spacer device 314 to the support of the removable tray 201 (FIGS. 6). The cam surface 316 has three levels. The lower level of the Cam surface corresponds to the pressing step. When the roller reaches the intermediate level, the 314 support takes off from the machine table pressing, and the grinding wheel being at a level higher than the free end of the pin 315 can be pushed laterally towards an evacuation conveyor; when the roller, continuing its path on the cam surface 316, reaches the higher level thereof, the support 314 moves further away from the table, and the removable tray 201 itself arrives at a level higher than the end free of pin 315, and so can be transferred back to the line assembly to receive a new ring and a new stack of layers of constituents.

The wheels unloaded from the pressing machine 31 are then known way, transferred to another oven to undergo annealing before to be stored for delivery.

This installation allows as in the example described above the manufacture of flat grinding wheels, but also the manufacture of grinding wheels with hubs deported.

Some or all of the transfer operations, particularly between the pancake making machine 1 and the assembly line 2, in the posts in the assembly line, or between the assembly line and the machine pressing 3, can be manual.

It also results from the design of the installation that has just been described, that its reliability is much higher than that of known installations; of addition, the size of the installation is relatively small, and for example for the production of about a thousand grinds per hour, the footprint of the installation remains less than one hundred square meters.

Due to the modularity of the installation, it is possible to change grinding wheel type in about fifteen minutes, and wheel diameter in one thirty minutes.

Similarly, it is possible to associate several manufacturing machines slabs to the assembly line so that they can be quickly failures, or to provide slabs for two or more laying of patties in the case of the manufacture of multilayer wheels, or prepare the production, chained very quickly, of a second type of millstone.

The production line illustrated in the diagram of FIG. intended for the manufacture of single-layer wheels from a slab A comprising a reinforcing sheet.

• le secteur 100 comprend une machine 150 de dépose et d'égalisation de grains abrasifs revêtus d'un liant pour remplir un moule 170 situé sur un emplacement X, et un moyen 160 de préhension et de dépose d'une couche de protection pour déposer ladite couche sur un emplacement Y,
• le secteur 200 comprend un moyen de préhension et de dépose d'une feuille de renfort au-dessus des grains abrasifs dans le moule 170 situé sur un emplacement X et d'une autre feuille de renfort sur la couche de protection préalablement déposée sur un emplacement Y. Sur la figure, cette opération est assurée à titre d'exemple par un opérateur 250,
• le secteur 300 comprend une machine de pressage 350 destinée à comprimer les couches de constituant comprises dans le moule 170 pour former une galette A,
• le secteur 400 comprend des moyens 450 pour saisir la galette A de la position X et la superposer aux couches de constituant préalablement disposées à l'emplacement Y pour constituer une pile P,
• le secteur 500 comprend une machine de pressage 550 pour comprimer la pile P située sur l'emplacement Y et former ainsi une meule,
• le secteur 600 comprend des moyens 650 d'évacuation de la meule.

It comprises a rotary manufacturing table 700, which rotates in the direction of the arrow F, divided into several sectors 100, 200, 300, 400, 500, 600, each sector comprising a location X and a location Y corresponding to a position of work where the following operations are performed consecutively in the direction of rotation of the arrow F and can be simultaneously in time:

• the sector 100 comprises a machine 150 for depositing and equalizing abrasive grains coated with a binder to fill a mold 170 located on a location X, and a means 160 for gripping and depositing a protective layer for depositing said layer on a Y location,
• the sector 200 comprises means for gripping and depositing a reinforcing sheet over the abrasive grains in the mold 170 located on a location X and another reinforcing sheet on the protective layer previously deposited on a location Y. In the figure, this operation is provided by way of example by an operator 250,
• the sector 300 comprises a pressing machine 350 for compressing the constituent layers included in the mold 170 to form a wafer A,
• the sector 400 comprises means 450 for grasping the wafer A of the position X and superposing it on the constituent layers previously arranged at the location Y to form a stack P,
• the sector 500 comprises a pressing machine 550 for compressing the stack P located on the location Y and thus forming a grinding wheel,
• the sector 600 comprises means 650 for removing the wheel.

It should be noted that a press 31 of the type of that described in FIG. can be used and correspond to the 550 press machine of sector 500.

It is advantageous to use a press of this type with the plateau 201 located above the mold 31 and remove the battery P on the bottom of the mold 311, the edge of the mold 312 is then brought into contact with the plate 201 and the pressing can be done.

It is possible to have several X and Y slots segment to increase the number of grinding wheels produced at the same time on the rotary table 700. In particular, it is possible to use "cassettes" removable devices on which we find one or more locations X and / or Y and which are arranged on the rotary table 700.

This system makes it possible to quickly change all locations X and Y, either of one sector or of all sectors of the rotary table 700 in order, for example to change the size of the locations X and Y to produce wheels of a different size.

The production line can be manual, semi-automatic or completely automated.

The constancy of the characteristics of the wheels manufactured is remarkable in terms of regularity of thickness and unbalance.

Claims (22)

1. Method for the manufacture of a wheel of the thin-wheel type by the pressing of at least one layer formed from abrasive grains and two layers which do not contain abrasive grains and which frame the wheel, characterized in that

   a layer of abrasive grains is formed directly in a mould (17, 170) in the absence of an underlying reinforcing layer,

   where appropriate, a reinforcing layer is deposited on this layer of abrasive grains,

   the layer or layers is or are pressed in order to form a wafer (A),

   the wafer is removed from the mould,

   the wafer (A) is assembled together with

   either one or two other reinforcing layers, in such a way that two reinforcing layers frame the wheel,

   or at least one other wafer (A) and at least one or two other reinforcing layers, in such a way that two reinforcing layers frame the wheel,

   the assembly is pressed.
2. Method according to Claim 1, characterized in that at least one wafer (A) comprises at least one layer of constituent free of abrasive grains, in particular a reinforcing sheet.
3. Method according to Claim 1, characterized in that , in order to manufacture the wafer (A), an abrasive product formed from abrasive grains comprising a coating consisting of a binder is poured into a mould (17, 170), the level of abrasive product is equalized to a desired value, and the abrasive product is compressed.
4. Method according to Claim 2, characterized in that , in order to manufacture the wafer (A), an abrasive product formed from abrasive grains comprising a coating consisting of a binder is poured into a mould (17, 170), the level of abrasive product is equalized to a desired value, at least one other layer of constituent free of abrasive grain, in particular a reinforcing sheet, is deposited, and the whole is compressed.
5. Method according to any one of the preceding claims, characterized in that layers of constituent comprising at least one wafer (A) are laid successively one onto the other in order to form a stack (P), the stack is then heated, and the stack is subsequently pressed.
6. Method according to any one of the preceding claims, characterized in that the layers of constituent are superposed along an assembly line (2) which is equipped with stations for laying the layers (22, 23, 24, 25, 26, 27, 28) and along which the layers are caused to travel in superposition in the form of stacks (P), and, in at least some stations, stores of stacks are formed, from which the stored stacks are taken one by one in order to superpose a new layer of constituent onto them, and the stack provided with its new layer is discharged from the station towards the following station.
7. Installation for the manufacture of wheels of the thin-wheel type by the pressing of at least one layer formed from abrasive grains and two layers that do not contain abrasive grains and which frame the wheel, characterized in that it comprises at least

   one station (100, 200) for filling a mould (170) with the layer or layers of constituent from which a wafer (A) is formed,

   one machine (350) for pressing the layer or layers of constituent contained in the mould (170) in order to form the said wafer (A),

   one assembly station (400) intended for forming a stack (P) of superposed layers from at least one wafer (A) and from at least one other layer of constituent,

   one pressing machine (550) for compressing the stack (P) and forming the wheel.
8. Installation according to Claim 7, characterized in that it comprises an assembly line (2) provided with stations (22, 23, 24, 25, 26, 27, 28) which are arranged in succession and at the location of which layers intended for forming the wheel are superposed in order to form the stack (P) of superposed layers, the said stations being followed by a heating station (29) where the stack of layers is heated.
9. Installation according to Claim 7 or Claim 8, characterized in that it comprises a wafer-manufacturing machine (1) which comprises a rotary production table (10) equipped with moulds and with specialized workstations comprising a station for the pouring on of abrasive (12), an equalization station (13), a pressing station (14), an unloading station (15) and a cleaning station (16), and it also comprises a storage table (11) for storing the manufactured wafers.
10. Installation according to either one of Claims 8 and 9, characterized in that the assembly line (2) comprises a conveyor (20) advancing in a closed circuit and carrying fixed platforms designed for receiving removable platforms (201) designed for receiving stacks (P) of component elements of the wheel.
11. Installation according to one of Claims 8 to 10, characterized in that the assembly line (2) comprises a ring-laying station (21), stations for laying a layer of constituent (22, 23, 24, 25, 26, 27, 28) and a heating station (29).
12. Installation according to one of Claims 8 to 11, characterized in that the assembly line (2) comprises at least one station comprising a temporary storage device.
13. Installation according to one of Claims 7 to 12, characterized in that the elements (100, 200, 350, 400, 550) are arranged around a rotary production table (700) on which at least one mould (170) is fastened.
14. Installation according to Claim 13, characterized in that the rotary production table (700) is divided into sectors (100, 200, 300, 400, 500, 600) corresponding to workstations for consecutive operations, and in that each sector comprises at least one location (X) for a mould (170) and at least one location (Y) at which one or more layers of constituent of a wheel can be arranged.
15. Installation according to Claim 14,
    characterized in that it comprises a rotary production table (700) divided into a plurality of sectors (100, 200, 300, 400, 500, 600), each sector corresponding respectively to the workstations where the following consecutive operations are carried out:

    deposition and equalization of the abrasive grains coated with a binder in a mould (170) situated at a location (X) of the sector (100), particularly with the aid of a tool (150), and deposition of at least one layer of component, in particular a protective layer, at a location (Y) of the said sector,

    deposition of at least one layer of component, in particular a reinforcing sheet, on the abrasive grains in the mould (170), and deposition of at least one layer of component, in particular a protective sheet and/or a reinforcing sheet, at a location (Y),

    pressing with the aid of the pressing machine (350), intended for forming at least one wafer (A) from the layers of constituent which are contained in at least one mould (170),

    formation of the stack (P), which involves taking at least one wafer (A) from a location (X) in order to lay it at a location (Y) and thus form at least one stack formed by the layers of constituent previously arranged at a location (Y) and by at least one wafer (A),

    pressing of the stack (P) situated at the location (Y) in order to consolidate a wheel with the aid of the pressing machine (550),

    discharge of the wheel or wheels.
16. Installation according to one of Claims 7 to 15, characterized in that the pressing machine (3, 550) comprises a rotary table equipped with jack presses (31) comprising a movable tool which comprises a mould comprising a bottom (311) and a side wall (312) mounted slideably around the bottom, and a mould support (310) which is fastened to the piston of the jack and to which the bottom and the side wall are secured by means of spring devices designed to subject the stack (P) to a pressing force by causing it to be surrounded by the side wall, during the extension of the jack, and to bring about the start of the rise of the side wall while the bottom is still against the stack, then the rise of the bottom while the side wall continues its rise, during the retraction of the jack.
17. Installation according to one of Claims 8 to 16, characterized in that the pressing machine (3, 550) comprises presses (31), each provided with a support (314) for a removable platform (201) designed for receiving a stack (P) of layers of constituents of the wheel, and a cam surface (316) travelled over by rollers, each secured to a support (314), in order to raise the support for the purpose of discharging the wheel and of reloading the removable platform (201) on the assembly line (2).
18. Wheel of the thin-wheel type, comprising at least one layer formed from abrasive grains and two layers which do not contain abrasive grains and which frame the wheel, the said wheel being manufactured by means of the method according to any one of Claims 1 to 6.
19. Wheel according to Claim 18, characterized in that it comprises at least one reinforcing layer pierced with holes in which is distributed part of the abrasive product which is formed from abrasive grains.
20. Wheel according to Claim 18 or 19, characterized in that it comprises a central ring.
21. Wheel according to one of Claims 18 to 20, characterized in that it comprises at least one layer of abrasive product, and each layer of abrasive product is interposed between two reinforcing layers.
22. Wheel according to one of Claims 18 to 21, characterized in that its thickness is smaller than or equal to 2 mm or even smaller than or equal to 1 mm.

Images