ES2381834B2 - CLEANING DEVICE AND METHOD TO ELIMINATE COATINGS FROM ELASTOMEROS IN METAL SURFACES FOR USE IN THE BAKING OF BREADING PRODUCTS - Google Patents

Abstract

Cleaning device and method for removing elastomer-based coatings on metal surfaces used in baking baked goods that is characterized by blasting metal shot on the coated surface, in a second step the metal surface is partially passed clean, on a cleaning equipment based on a plurality of cleaning rollers with spikes (2, 5), which removes part of the material not released. In the third step (optional) the metal surfaces are introduced in an oven to, by a process of controlled thermal degradation, produce the decomposition of the elastomer and remains of products not yet detached from the metal surface, and in a fourth and last step ( also optional), a new blasting is produced that completely eliminates the waste produced in the baking and creates a roughness suitable for application of a new coating layer.

Description

CLEANING DEVICE AND METHOD FOR ELIMINATING ELASTOMER COATINGS ON METAL SURFACES FOR USE IN THE BAKING OF BREADING PRODUCTS

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The present invention relates to a process for removing elastomer-based coatings on metal surfaces in supports or parts of products used in the baking of bakery products and equipment designed for this purpose.

STATE OF THE PREVIOUS TECHNIQUE

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The pieces or supports that are used in baking for baking are usually rectangular format usually made of stainless steel, aluminum alloys and, occasionally, steels with aluminum surface layer also called aluminized steels. They usually have a square profile tube frame or other sections on which the really coated surface is fixed, which is usually between 0.8 and 2 mm thick. The surface to be coated may or may not be perforated. The surface can be completely flat, with several "waves", or with several embossments of very different geometries. These pieces or supports usually receive, also, the name of trays, cans, molds or simply plates, etc., of bread.

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In the technology of coating metal surfaces intended to be used in the presence of high temperatures for the support of bakery products, coatings consisting of single-component silicone rubber layers of the RTV type, which have regulation for food contact, are frequently used. These coatings have non-stick, non-stick, anti-corrosive or protection characteristics in general. Coatings of this nature can be applied to metal substrates capable of withstanding temperatures up to at least 250 to 300 ° C. Usually a first coating layer, called primer, is applied to the metal substrate that has previously been degreased or subjected to blasting of shot or corundum in order to cause sufficient roughness to improve adhesion to the metal. Subsequently, one or more layers of elastomer products are applied, which end up baking in an oven at temperatures included between 200 and 250 ° C.

The removal of these protective coatings suffers from many difficulties,

taking into account its characteristics of high adhesion and resistance to high procedures do not allow a complete cleaning by themselves, due to its complexity,

temperatures

In addition, when parts coated with elastomers are losing their

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Non-stick or non-stick characteristics, due to wear due to its use, is the

time to remove the aged coating and apply a new

covering. However, sometimes grease is applied to increase the

demoulding of the pieces and a mixture of elastomer and release grease is produced

which is dried and deposited on the elastomer. This new elastomer arrangement

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It further hinders the correct removal or removal of the coating.

The removal by mechanical abrasion, only, is very heavy and difficult,

due to the good physical and chemical properties of the coatings and the

different provisions and diversity of their status. They are very extensive

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Cleaning possibilities tested mechanically, from all types of equipment

from blasting or blasting to brushing, sanding equipment, etc. The experience has

demonstrated that in no case a complete, adequate, or clean cleaning is obtained

economic, of the metallic surfaces of use in the baking, only by these

media.

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The use of heat to cause degradation of the protective coating could be

A sufficient procedure by itself. However, it is a source of products

highly polluting due to the decomposition of elastomers

elements that cannot be dispersed in the atmosphere. In addition the provisions

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Frequent elastomer coatings with grease for use in food

produce a combustion with fire that causes flames at high temperatures of

degradation. This fire thermally affects the metal surface reaching

sometimes cause permanent deformation of parts and supports, including

in aluminum supports and their alloys metal losses occur. All of it

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carries with it very serious damages of the pieces or supports. Therefore this

Nor should the procedure be used solely by itself. In any case,

when used, the production of combustion must be avoided at all costs

accompanied by fire by decreasing the amount of material to

incinerate and avoiding that the piece has grease or these remains are minimal. To do this

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you must have a thorough control of the oven temperature and a procedure

to extract the fat previously. In addition these ovens must be accompanied by a

   post-combustion chamber that, at about 8oo at 1000 ° C, causes degradation

Complete of fumes and prevents the discharge of pollutants into the atmosphere. In

definitive and, therefore, again experience has shown that these

high economic cost and the risk of loss of parts or supports.

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The use of chemical procedures is well known. The use of alkaline baths, baths with powerful degreasers, baths with all types of acids, detergents, etc., both at room temperature and hot, have been the most common alternative until recently. An example is developed in German patent DE10047734 by means of an alkaline solution and a subsequent bath with a diluted acid. The problems associated with the treatment of waste that these systems require, added to the slowness of the cleaning process of these coatings make it inadvisable, nowadays, from the economic point of view.

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Another extraction procedure is that as proposed in the Italian patent IT MI940391 through an impact on the surface by means of a solid state laser beam. This system may be of interest in fluoropolymer resins because of their physical and chemical qualities. However, elastomer tests have not been efficient.

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US patent US 6491762 proposes the extraction through an impact system of an ultra high pressure water jet on the coated metal surface. This requires an investment in expensive equipment and its application in elastomer coatings is not valued, but only in fluoropolymer resins.

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German patent DE88579 proposes the extraction of coatings by contact with a gas stream, usually nitrogen, at a very low temperature. The exposure of the gas on the coated surface produces a spontaneous subtraction of heat within the coating and as a consequence an intense contraction and a detachment of the layer from the substrate. Again, it must be stressed that this technique is not valued in applications with elastomers on metal surfaces for use in bakery and the cost of the equipment is very high.

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U.S. Pat. No. US4858264 is directed to an ultrasonic-assisted protective coating removal system, particularly for removing paint or similar coatings from an airplane.

   The French patent FR2717406 proposes cleaning in a fluidized bed with a special sand and a gas, the assembly produces a "bubbling" and by friction action

of sand and high temperature causes the release of dirt and debris

organic This patent does not value the extraction of the coatings of these pieces.

The tests carried out with specialists in the sector have been completely

discouraging

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German patent DE19618613 proposes a procedure to eliminate

worn coatings from rollers as well as a device for

Performing this procedure. The device focuses on the elimination of

coating on rotating cylindrical rollers.

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Another method of cleaning a vulcanization matrix is described, by

example, in the European patent with publication number EP0740989. This

method comprises the steps of previously generating a plasma from a gas

reagent, inject the plasma of the reactive gas from several injection holes

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formed in a spray tube to the inner surface of a matrix of

vulcanization arranged in a vacuum processing chamber, and letting the

reactive gas plasma react with an elastomer residue attached to the surface

inside the matrix, thus eliminating the elastomer residue by incineration.

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Patents DE420068g, DE429612, DE19508840, DE4133784, GB 190822234,

show different equipment and configurations that allow the cleaning of the pieces or

supports through rollers, belts, brushes, etc., combined with water spray,

steam, detergents or dry. Now these systems are prepared for the

cleaning of organic remains and baking in the supports or parts for the

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baked but not for the extraction of the coatings.

In short, none of the patents described address the issue of disposal

for coating surface elastomers for bakery parts and utensils and

related industries.

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EXPLANATION OF THE INVENTION

The present invention deals with how to solve the technical problem derived from the removal of surface elastomer coating of parts and utensils for bakery and related industries, where by the combined use of blasting means with metal shot, subsequent extraction mechanics through equipment designed for this purpose, pyrolysis in an oven and finally

finish by blasting. Therefore, in this invention, both the process of

extraction as the equipment, allows to give an efficient and economic solution to the

extraction of coatings in parts and supports for baking products

baking

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More specifically, a first aspect of the invention relates to a method for

remove elastomer-based coatings on metal surfaces in

stands or pieces of products used in the baking of bakery products in

Four steps In the first one a metal shot blasting is applied on the

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coated surface, in the second step the metal surface is passed,

partially clean, on specially designed cleaning equipment and subject to

this patent, which eliminates part of the material not released. In the third step

(optional) the metal surfaces are introduced into an oven for, by means of a

controlled thermal degradation process, produce the decomposition of

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elastomer and product remains not yet detached from the metal surface, and in

a fourth and last step (equally optional), there is a new blasting that

completely eliminates the waste produced in baking and creates a roughness

suitable for application of a new coating layer.

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In a first aspect of the invention, the device consists essentially of a

device comprising a table located on a machine chassis and at least

two cleaning rollers housed inside a sheet metal housing, which prevents the

remains of elastomer detached jump out of the equipment, and that is characterized by

each of said cleaning rollers comprises a steel core and a

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outer surface formed by a plurality of barbs of a hard and flexible polymer,

said barbs being arranged as parallel discs; and where the speed

of said cleaning rollers is adjustable through a first variator motor; in

where said cleaning rollers are mounted on individual supports of

bearing which, in turn, are jointly and severally attached to the equipment chassis,

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configuring these supports, in turn, the height adjustment modifying the space

between the cleaning cylinders and the table; and where the removal of the coating of

the parts are produced by the friction of the tines of the cleaning cylinders that

produce a detachment of the elastomer.

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In a second aspect of the invention, the cleaning method consists,

essentially in an automatic shot blasting stage, where the piece is subjected to

   clean at a shot blasting stage in an automatic shot blasting equipment;

and a cleaning stage by the equipment described above; getting a

removal of between 75% and 100% of the coating surface of the

elastomer and its mixtures with fats and remains of bakery products.

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The method comprises an additional and optional stage of degradation of the coating by thermal effects through a furnace in which the temperature is progressively raised to values between 300 to 400 ° C for a time between 14 and 30 minutes .

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Finally, the method comprises an additional stage of finishing by blasting in an automatic blasting equipment, so that the piece is left ready for a new coating.

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Throughout the description and the claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention. The following examples and drawings are provided by way of illustration, and are not intended to be limiting of the present invention. In addition, the present invention covers all possible combinations of particular and preferred embodiments indicated herein. BRIEF DESCRIPTION OF THE DRAWINGS

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FIG1. It shows a plan view of the cleaning equipment for removing elastomer coatings on metal surfaces used in the baking of bakery products, object of the present invention. FIG2. It shows a front view of the cleaning equipment for removing elastomer coatings on metal surfaces used in the baking of bakery products, object of the present invention. FIG3. It shows a side view of the cleaning equipment for removing elastomer coatings on metal surfaces used in the baking of bakery products, object of the present invention.

DETAILED EXHIBITION OF MODES OF EMBODIMENT

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   As indicated, the present invention provides a useful and economical method for removing elastomers and mixing these elastomers with oils and fats for use in food, including remnants of bakery products for parts or supports commonly used in baking of these products. The invention essentially materializes in a method comprising at least

Four stages: automatic blasting, cleaning on the equipment subject to the

invention of coating degradation by thermal effects through an oven

and finishing by blasting.

5

The first automatic shot blasting stage enables metal shot blasting,

wherein the support or piece is subjected to said blasting. High flexibility and good

elastic resilience of elastomers has traditionally done

the use of impact extraction or blasting procedures is inadvisable. Do not

However, after many tests with different shot blasting equipment, different types of

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abrasive material, different angles and impact speeds, values have been obtained

of the appropriate technological parameters that allow a separation of

elastomeric coating between 20% and 8% of the total surface. These

values depend, to a large extent, on the initial state of the coating to be extracted, it is

that is, the degree of wear of the coating, if it is mixed with

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grease or bakery products, of the geometry of the piece or support, as well as of the

manufacturing material of this piece or support.

The tests have shown satisfactory results with a shot blasting device

"hook" type automatic equipped with two 7.5 kW turbines and with

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Adjustable speed between 1000 and 3000 rpm. The speed of the conveyor over the

that the part or support is fixed is adjustable between 1 and 10 rpm, the speed of

shot blasting between 38 and 78 mjs. The shot is metal angular type

of iron with a fineness between 0.4 and 2 mm. Cycle times vary

between 2 and 6 minutes with surfaces to be cleaned between 1 to 3 square meters per cycle.

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In the blasting process, initially, the blasting parts are mounted on a

structure of circular and square section steel profiles that produce a

support as a rectangular lattice suitable for fixing the

pieces. The dimensions of said support range between 8oo and 1000 mm wide and

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1000 to 1500 mm high. Each blasting cycle allows to fix three supports on a

hook. If we look at the layout of the floor supports, they are arranged as a

sides of an equilateral triangle. Hook blasting equipment allows

mount two sets of three brackets so that while doing a cycle of

cleaning with one set, the operator is fixing the new parts in the other set

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free.

   The second stage or phase allows the introduction of the pieces in the equipment shown

in the attached figures, which comprises at least two cleaning rollers and one

table (13), wherein each of said cleaning rollers has a length

between 1000 and 1500 mm in its preferred embodiment, and comprises:

a core of a steel shaft (2), with a core diameter between 100 and 150

mm; and an outer surface (5) formed by a plurality of barbs of a diameter

between 5 and 8 mm of a hard and flexible polymer, with each

5

barbed between 6 and 90 mm long, said spikes being also

arranged as parallel discs, there is a separation between discs of

between 25 and so mm, while the diameters of the disks vary between 200 and

300mm;

and wherein the speed of said cleaning rollers is adjustable through

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a first variator motor (4) and reaches speeds between 150 and

250 rpm

The cleaning rollers are mounted on two bearing supports (3)

which, in turn, are jointly and severally attached to the chassis of the team. These supports (3)

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allow, in turn, height adjustment by modifying the space between the cylinders

Cleaning and table (13).

In the usual operation of the described device, the part to be cleaned (1) is

insert the first barbed cleaning roller and the bed or table (13) of the

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device, so that enough space is left between them to allow

let the parts pass ensuring the efficiency of the system. This introduction is

performed manually, since the equipment has two chains (7), one at each end

of the table, on which a piece of rectangular section or plate (6) is arranged, which

moves in solidarity with the chain and sweeps the entire width of the table. This

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plate (6) drags the parts or supports in its movement towards the first roller of

cleaning. This movement is governed by chains (7), as it has been

indicated, to which the movement is transmitted by a serrated plate through a

pinion connected to a second motor-reducer (12). From the keypad of the team

there is a frequency inverter that allows you to vary the speed of this second

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reducing motor (12), consequently of the chain, reaching speeds of the

piece between 0.2 to 1 minute.

Once the first roller has passed and the pieces are trapped by the second roller of

cleaning, these move autonomously to the other side of the platform or

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table. At the exit of the second roller there are several plates (8) for fixing the

Straps (9), which act as "nails", perform brake effect and prevent the expulsion of the

   high speed part. The extraction of the coating of the pieces is produced by the

friction of the spikes (5) of the cleaning cylinders that produce a

elastomer detachment.

Sliding polymer plates (10) have been fixed on the equipment table (13),

that improve the movement of the piece on the table. Cleaning rollers

they are housed inside a crankcase (11), which prevents the remains of

5

detached elastomer jump out of the equipment.

In most cases the application of the two phases described, blasting and

passing through the equipment, allows the elimination of between 75 and 90%, rarely

100% of the surface of the elastomer and its mixtures with grease and product residues

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of baking.

In cases where the third phase is necessary, in practice most of the pieces,

partially clean parts or supports are introduced in an open belt oven

or continuous oven in which the temperature rises progressively to values

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between 300 to 400 ° C with belt speeds between 1.5 to 3 mjmin.

The width of the mouth of the oven can range from Sao to 1500 mm, the height of the

mouth is between 150 to 250 mm. The time spent in the oven is a

key factor that must be properly controlled and that must be assessed

depending on the state of the surface. The usual values are understood between

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14 to 30 minutes. The objective is to ensure complete degradation of the coating

not yet detached.

The last phase of the invention described herein is intended as a preparation.

suitable for the subsequent application of a new coating. The little ones

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Remains of degraded elastomer, oils, fats or baking remains are

completely eliminated by blasting which, in this case, is usually performed

with corundum The granulometry of the same is usually between 0.2 and 1.5

mm This blasting is done in a continuous suction type device that

described below and which is not the subject of this patent.

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It is a team equipped with various nozzles, between 6 and 8, that move

alternatively by means of a pneumatic device and they sweep the surface of

the piece. The diameter of the nozzles ranges between 6 and 10 mm, the speed of the

blasting nozzles ranges from 1 to 0.5 mjs per second. The piece moves to the

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lean on 6 rubber bands of circular section to which the

movement by a grooved roller through a reduction motor. Two exists

   rollers, one driver and another driven at each end of the machine. The

speed of the piece to drip varies between 1 to 2 mjmin. Equipment installation

requires an air pressure between 2 to 5 kpjcm2 •

Claims (5)

1.-Cleaning device to remove elastomer coatings in

5

Metal surfaces used in the baking of bakery products (1) which

comprises a table (13) located on a machine chassis and, at least two

cleaning rollers housed inside a sheet metal housing (11), which prevents

the remains of elastomer released jump out of the equipment, characterized

because each of said cleaning rollers comprises

10

a core (2) and an outer surface (5) formed by a plurality of spikes

of a hard and flexible polymer, said spikes being arranged as discs

parallel; yen where the speed of said cleaning rollers is adjustable through

of a first drive motor (4);

wherein said cleaning rollers are mounted on individual supports of

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bearing (3) which, in turn, are jointly and severally attached to the equipment chassis,

configuring these supports (3), in turn, the height adjustment modifying the

space between the cleaning cylinders and the table (13);

and where the extraction of the coating of the pieces (1) is produced by the

friction of the spikes (5) of the cleaning cylinders that produce a

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elastomer detachment.

and because the piece to be cleaned (1) is inserted between the first cleaning roller

of tines and the bed or table (13) of the device, so that it is left between them

sufficient space to allow the pieces to be cleaned (1), and where it is

introduction is done manually, since the team has at least two

25

chains (7), one at each end of the table (13), on which a piece is arranged

rectangular section or plate (6), which moves in solidarity with the chain

(7) and sweeps the entire width of the table, this plate (6) being the one that drags in its

movement to the parts or supports (1) towards the first cleaning roller.

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2.-Cleaning device according to claim 1

characterized in that once the first roller has passed and the pieces are trapped by the

second cleaning roller, these move autonomously towards the other side of

the platform or table (13); and where at the exit of the second roller there are several

strips (8) for fixing the straps (9), which act as "nails", brake effect

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and prevent the expulsion of the piece at high speed.

3. -Clean device according to the preceding claims

characterized in that on the table of the equipment (13) some plates of

Sliding polymer (10), which improve the movement of the piece on the table.

4.-Cleaning method to remove elastomer coatings

in

surfaces

metallic from use in he baked from products from baking

characterized in that it comprises at least the stages of:

5

(to) an automatic shot blasting stage, where the piece is subjected to

clean (1)

to a shot blasting stage in a shot blasting equipment

automatic; Y

(b) a cleaning step by means of the equipment of claims 1 to 5;

obtaining a removal of between 75% and 100% of the surface of

10

coating of the elastomer and / or its mixtures with fats and traces of products of

baking

5.-Cleaning method according

with claim 5 characterized

because it comprises an additional stage of degradation of the coating by effects

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through a furnace in which the temperature rises progressively to

values between 300 to 400 oc for a time between

14 and 30 minutes.

6.-Cleaning method according to claims 5 and 6 characterized

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because it comprises an additional stage of finishing by blasting in an equipment of

Automatic shot blasting completely eliminates waste produced

in he

baked and creates a roughness suitable for applying a new layer of

covering.