EP2478300B1 - Method for producing a coated extension guide - Google Patents

Description

The present invention relates to a method for producing a coated drawer guide, in particular for ovens, with a rail, on which at least one further rail is movably mounted via rolling elements, wherein the rolling elements are guided along raceways on the rails.

The EP 1 607 685 discloses a coating method for a telescopic rail in which a PTFE coating is applied to chromed structural steel or stainless steel. For the pretreatment of the telescopic rail, a cleaning process is first carried out by a temperature treatment and then a surface treatment for roughening the surface by sandblasting. However, this type of pre-treatment is labor intensive and there is a risk that remain on the running surfaces of the telescopic rail blasting material residues that adversely affect the running quality of a pullout guide made with the rail. In addition, a high energy consumption must be spent in the thermal surface pretreatment. There is a treatment of the individual parts of a pullout guide, only after the application of the method described, the telescopic rails are mounted.

It is therefore an object of the invention to provide a method for producing a coated drawer slide, which is designed process-technically, cost-optimized and energy efficient.

This object is achieved by a method having the features of claim 1.

In the method according to the invention, a coated pull-out guide is produced which consists of a rail on which at least one further rail is movably mounted via rolling elements, the rolling elements being guided along raceways on the rails. The pullout guide with the rails and the rolling elements is first assembled into a unit. Subsequently, a metallic surface of at least one rail is cleaned by a mechanical and / or chemical cleaning process before a coating is applied to the cleaned metallic surface.

The EP 1 873 460 A2 discloses a pull-out system for a household appliance, in which the running properties are not to be changed by detergent. For this purpose, a coating with polyether ketone on a Wälzkörperkäfig or a contact element is provided.

The US 2003/207145 discloses a method of adhering a polymer to a substrate wherein the surface of the substrate is cleaned prior to application of the coating.

In the US 2003/0172952 For example, a method of cleaning a surface via a plasma manufacturing apparatus is disclosed.

The WO 2004/044257 discloses a method and apparatus for cleaning a metal surface wherein cleaning, chemical cleaning, brushing or plasma cleaning may be used.

In the US 2008/0092806 For example, removal of particles from a substrate is disclosed.

Finally, in the WO 2006/022858 discloses a sol-gel non-stick coating for a baking oven muffle. The coating should withstand both chemical cleaning processes and mechanical loads.

By mechanical and / or chemical cleaning, an additional thermal treatment can be avoided, which means a high energy consumption and longer residence time in a heat chamber. In the chemical and mechanical cleaning methods, the adhesive forces of impurities on the metallic surface are reduced so that the impurities can be removed by wiping or be removed by the cleaning agent. When using a mechanical cleaning process, an additional optional step for roughening the metallic surface may be omitted. Because in the cleaning process, the surface cleaning and roughening can be done simultaneously in one step. In this case, a combination of chemical and mechanical cleaning can be carried out, for example by liquid detergent is additionally caused to oscillate by an ultrasonic generator. By the subsequent coating of the metallic surface is a reduction of dirt adhesion; an increase in the anti-scaling, an increase in corrosion protection and / or increased scratch resistance achieved.

Preferably, the cleaning of the metallic surface is carried out at a temperature of 0 to 200 ° C, in particular at ambient temperature. As a result, any heating of the drawer guide during cleaning is reduced to a minimum.

In one embodiment, the tracks on the rails during coating remain coating-free, so that a high running quality is maintained. The coating-free raceways can be formed, for example, by masking or covering the raceways or by pushing the rails together during the coating process. The pullout guides are preferably in the mounted, retracted state during the coating process, especially in a coating in the spraying process, the raceways and rolling elements can not be contaminated by coating material.

1. i) Einbringen der Auszugsführung in eine Reinigungskammer,
2. ii) Reinigen der Auszugsführung von Verunreinigungen durch Benetzen der Oberfläche mit einer Reinigungslösung,
3. iii) Überführen der verschmutzten Reinigungslösung in eine Aufarbeitungseinheit,
4. iv) Aufarbeiten der Reinigungslösung, durch Entfernen von Verunreinigungen aus der Reinigungslösung,
5. v) Überführen der aufgearbeiteten Reinigungslösung in einen Vorratstank,
6. vi) Rückführen der Reinigungslösung in die Reinigungskammer.

Durch die Zirkulierung des Reinigungsmittels beim Reinigungsverfahren können Abfallprodukte des Reinigungsmittels weitgehend vermieden werden. Die Prozessführung ermöglicht zudem eine vollautomatische Reinigung vor dem Beschichtungsschritt.If the chemical cleaning method of the metallic surface is used, it preferably has the following steps:

1. i) introducing the drawer guide into a cleaning chamber,
2. ii) cleaning the pullout guide of contaminants by wetting the surface with a cleaning solution,
3. iii) transferring the soiled cleaning solution to a processing unit,
4. iv) working up the cleaning solution by removing impurities from the cleaning solution,
5. v) transferring the reconditioned cleaning solution to a storage tank,
6. vi) returning the cleaning solution into the cleaning chamber.

By the circulation of the cleaning agent in the cleaning process waste products of the cleaning agent can be largely avoided. The process control also allows a fully automatic cleaning before the coating step.

The cleaning of the metallic surface can be done by a blasting process. In this case, ice blasting, ice blasting with blasting agent addition, carbon dioxide pellet blasting and / or carbon dioxide snow blasting can be used. These methods are particularly advantageous because they both remove impurities, as well as abrasive, so that cleaning and surface roughening done in one step. At the same time, no residual blasting agent remains on the raceways and other areas of the rails. By using a blasting agent additive during ice blasting, a purging step for dissolving and / or rinsing off the blasting agent additive may be required. Advantageously, salts having a low water solubility are added to the ice stream as blasting agents, they increase the abrasiveness and can be removed without residue by a rinsing step, if required.

The cleaning of the metallic surface may preferably be carried out by an ultrasonic method. In this case, a solvent can be applied to the surface, which dissolves ultrasonic waves initiated by cavitation impurities from this surface. Additionally or alternatively, in addition to the solvent and cleaning additives or solvent mixtures can be used, which enhance the cleaning effect of the solvent. These may be, for example, other solvents of different polarity, surfactants, acids or bases and salts.

Furthermore, the cleaning of the metallic surface can be done by a plasma process. Plasma is generated by ionization of oxygen at room temperature under vacuum (low pressure plasma), ambient pressure (atmospheric plasma) or overpressure (high-pressure plasma). The reactive oxygen ions burn organic contaminants cold to carbon dioxide without additional heat stress on the pullout guide. Thus, the procedure very environmentally friendly, since only oxygen is used for cleaning and as a reaction product predominantly non-toxic carbon dioxide (CO ₂ ) and water (H ₂ O) is formed. In addition, the vacuum technology of the plasma cleaning process can be used for a subsequent plasma coating process of the pullout guide, which allows a reduction in the expenditure on equipment.

According to a further embodiment, the cleaning of the metallic surface is carried out by a laser cleaning, which can eliminate even very strong impurities particularly precisely.

Alternatively or additionally, a chemical cleaning of the metallic surface can take place. For this purpose, liquid carbon dioxide, alkaline solutions, and / or pickling can be used. Furthermore, an electrolytic cleaning can be carried out with alkaline and / or acidic solution. When using carbon dioxide is advantageous that this is safe and easy to separate from the detached contaminants. Alkaline and acid solutions are readily available, so that their use is inexpensive. A workup of these solutions is also easily possible. Cleaning solutions, which are used for cold cleaning and degreasing, contain a different proportion of nonpolar solvents, depending on the type of impurities. These cleaning solutions can be worked up by distillation and then recycled. In particular, a pickling process can also lead to a targeted roughening of the surface. Thus, the cleaning and a possible roughening of the surface can take place in one process step.

It is furthermore advantageous if the coating comprises PTFE, PEEK, PEK and / or inorganic-organic hybrid polymer-containing materials. These coatings have proven to be beneficial for food applications. At the same time, in particular, coatings containing inorganic-organic hybrid polymer-containing materials can also withstand temperatures above 300 ° C., which a conventional household furnace develops in pyrolysis operation.

It is advantageous if the application of the coating by a plasma coating process, since the plasma coating process better material adhesion with the metallic surface of the pullout guide having. The spraying process proves to be advantageous since only the outer surfaces of the mounted pullout guide are coated and the raceways, the rolling elements and Wälzkörperkäfige remain coating-free in contrast to the conventional dipping process. The running characteristics of the pullout guide are not adversely affected. An improvement of the material adhesion is likewise advantageously ensured by the application of a functional coating according to a sol-gel process. A coating according to the sol-gel process can also be applied by spraying.

Figuren 1 bis 3

mehrere Ansichten eines Ausführungsbeispiels einer mit dem erfindungsgemäßen Verfahren hergestellten Auszugsführung.

The invention will be explained below by means of an embodiment with reference to the accompanying drawings. They show:

FIGS. 1 to 3

several views of an embodiment of a pullout guide produced by the method according to the invention.

A pullout guide 1 comprises a guide rail 2 which can be fixed to a side rail in an oven, a side wall of a baking oven or a furniture body. On the guide rail 2, a center rail 3 is movably mounted on rolling elements 6. For supporting the rails 2, 3 and 4, at least two, in the exemplary embodiment, three raceways 9 for rolling bodies 6 are formed on the guide rail 2 and the running rail 4. The rolling elements 6 are held on a Wälzkörperkäfig 7 as a unit. Furthermore, a total of at least four raceways, in the exemplary embodiment, eight raceways 8 for rolling elements 6 are formed on the middle rail 3, with at least two raceways 8 of the guide rail 2 and at least two raceways 8 being assigned to the running rail 4.

For fixing the pullout guide 1 on a side rail of a baking oven two brackets 5 are fixed to the guide rail 2. Other fastening means or fastening points may be provided on the guide rail 2.

The pullout guide 1 is provided on the externally accessible area, ie on the outside of the guide rail 2 and the running rail 4 with, for example, a PTFE-containing coating (polytetrafluoroethylene). A fixed to the rail 4 plug 10 is also at its externally accessible areas coated eg with a PTFE-containing coating. Also, a retaining bolt 11 is equipped for example with a PTFE-containing coating. The inside of the running rail 4 and the guide rail 2, on which the raceways 9 are formed for the rolling elements 6, has no coating. The middle rail 3, which is arranged completely in the inner region of the pullout guide 1 when the running rail 4 is arranged in the retracted position, has no coating at least in the region of the raceways 8. Thereby, the raceways 8 may be formed by the material of the rails 2, 3 and 4, usually the raceways 8 and 9 are made of a bent steel sheet. On the outside is made possible by the PTFE-containing coating on the rails 2 and 4, for example, easy cleaning. As a result, the pullout guide 1 can be used particularly well in an oven, whereby a high running quality is achieved over a long service life. In the Fig. 1 to 3 an over extension with three rails, 2, 3, and 4 is shown. A version with at least three rails as a full extension is also conceivable. It is also possible to form the pullout guide as a partial extension with only two rails (without the middle rail 3) or with more than three rails.

In addition to the PTFE-containing coating, the pullout guide can also have a PEEK-containing coating (polyether-ether-ketone) and / or an inorganic-organic hybrid polymer-containing coating.

The in the Figures 1-3 The pullout guide shown is first assembled into a unit according to a first method according to the invention. In this case, both the assembly process and the coating process can be completely automated.

In the first variant of the method, the cleaning of the assembled drawer guide takes place without changing the roughness by a non-abrasive cleaning method. These include u.a. Non-abrasive blasting, ultrasonic cleaning, plasma cleaning, laser cleaning, steam cleaning and dry cleaning.

In this case, in a particularly preferred embodiment of the method, the mounted pull-out guides for cleaning are immersed in an ultrasonic bath and are preferably exposed to cleaning for 2 to 30 minutes by means of cavity effects. The cleaning solution in the ultrasonic bath is deionized water (deionized water) with a pH of 6-13, but preferably of 7-12.

To adjust a basic pH, a sodium hydroxide solution is used.

Preferred solvent of a chemical cleaning is isopropanol.

Subsequently, if necessary. Drying of the surface. Thereafter, at least in some areas, a coating is applied to the cleaned surface of the drawer guide.

The subsequent application of the coating comprises the application of the coating agent and then the curing of the coating, by stepwise heating of the coating to temperatures above 200 ° C. Following the coating, lubricants can be applied to the raceways to ensure high runnability of the pullout guide.

In a further variant of the method, the cleaning of the assembled pullout guide takes place by means of an abrasive blasting method on the surface to be coated. Ice or dry ice can be used for this. The ice or dry ice is coated with grains having an average size between 0.5 mm and 3 mm onto the surface to be cleaned with a pressure of e.g. between 2000 hPa and 20,000 hPa, in particular 5000 hPa to 15000 hPa. This cleaning process causes at the same time a cleaning as well as a surface roughening in one process step. In this case, impurities are dissolved by mechanical shocks and then transported away, for example by melt water. Finally, the cleaned surface is dried and the coating is applied.

In a first particularly preferred embodiment variant of the cleaning process, CO ₂ snow is generated from a riser cylinder with the aid of liquid carbon dioxide and inflated onto the drawer guide. For this purpose, a CO ₂ snow is brought into a compressed air jet and inflated at an angle between 30-90 ° on the surface of the pullout guide. The preferred working distance is 10-30 mm and the compressed air jet has 4000-8000 hPa and a volume flow between 1 and 8 m ³ / h. The feed rate of the nozzles, with which the CO ₂ snow is inflated on the pullout guide amounts preferably between 80-120 mm / s. The consumption of liquid carbon dioxide is in this method between 10-25 kg / h.

In a second particularly preferred embodiment of the cleaning CO ₂ pellets are inflated with a pressure of preferably 4000-6000 hPa on the pullout guide. The dry ice consumption is between 25-50 kg / h. Although the consumption in this process is higher, but harder adhering contaminants are removed by it. In this method, a knife set can be introduced into the CO ₂ pellet stream to split the pellets into small, hard particles before impacting the surface to be cleaned. These mostly sharp-edged particles increase the cleaning effect. When hitting the dirt, it is cooled down to embrittlement. The next impinging CO ₂ particle then dissolves the pollution. The compressed air supports the removal of embrittled dirt from the surface to be cleaned. Furthermore, the short-term existence of liquid CO ₂ can be assumed when hitting the surface to be cleaned, which leads to an increased cleaning effect in greasy soiling.

Furthermore, the CO ₂ pellets can be passed separately with a conveying air stream up to a two-fluid nozzle, in order to avoid rubbing and agglomeration of the pellets during transport to the point of use. A second hose delivers compressed air to the _two- component nozzle to accelerate the CO ₂ pellets for the cleaning process. This arrangement leads to a further increase in the cleaning performance, especially against particulate, firmly adhering soils.

In order to add an abrasive component to the CO ₂ purification process, an introduction of abrasive particles into the CO ₂ snow or CO ₂ pellet stream can take place. Carbonates are suitable, for example, as an abrasive component in CO ₂ purification processes. Carbonates can be removed in a further aqueous cleaning step residue-free again from the surface to be cleaned, thus there is no risk of damage to the raceways of the drawer slides to be cleaned. Furthermore, in particular salts can be used as blasting agent additive in CO ₂ purification processes. These salts preferably have little or no solubility in CO ₂ but are readily soluble in water. Thus, they can after the CO ₂ cleaning well in a downstream aqueous cleaning step are removed without residue from the surface to be cleaned.

In a further process variant, the roughness of the surface can be changed by electrolytic cleaning. After drying, it is also possible to apply a coating to this surface.

In a further embodiment, a chemical cleaning of the surface of the drawer guide takes place after their assembly.

The detergent loaded with the contaminants can be recycled for reuse. This is done for example by distillation.

1. a. In einer Reinigungskammer wird die zu reinigende Auszugsführung entweder durch Sprühen oder durch Eintauchen der Auszugsführung in ein Bad mit Reinigungsmitteln gereinigt. Die Reinigungskraft kann optional durch den Einsatz von Ultraschall verbessert werden.
2. b. Entleerung der Reinigungskammer und Transfer des Reinigungsmittels zur Destillations-Einheit.
3. c. Zusätzliche Dampfreinigung der Auszugsführung, wobei reiner Lösemitteldampf der Reinigungsmittelbestandteile, der durch die Destillationseinheit erzeugt wird, in die Reinigungskammer geleitet wird und auf den kälteren Teilen der Auszugsführung kondensiert. Die Ölfilm-Rückstände werden somit vollständig beim Ablaufen des Kondensats von der Oberfläche entfernt.
4. d. durch die Erzeugung eines Vakuums in der Reinigungskammer wird die Verdampfung des Lösemittels beschleunigt und die lösemittelhaltige Luft aus der Arbeitskammer evakuiert.
5. e. Belüftung der Reinigungskammer, insbesondere unter normalen atmosphärische Bedingungen. Die Lösemittelkonzentration in der Reinigungskammer wird überwacht, und die Lade- und Entladezone wird erst dann freigegeben, wenn die Konzentration unter den durch die VOC-Richtlinie spezifizierten Werten liegt.

A cleaning of the drawer guide with subsequent workup of a cleaning agent can be carried out as follows:

1. a. In a cleaning chamber, the drawer slide to be cleaned is cleaned either by spraying or by immersing the drawer slide in a bath with cleaning agents. The cleaning power can optionally be improved by the use of ultrasound.
2. b. Discharge of the cleaning chamber and transfer of the cleaning agent to the distillation unit.
3. c. Additional steam cleaning of the drawer slide wherein pure solvent vapor of the detergent ingredients produced by the distillation unit is directed into the cleaning chamber and condenses on the colder parts of the drawer slide. The oil film residues are thus completely removed as the condensate drains from the surface.
4. d. by generating a vacuum in the cleaning chamber, the evaporation of the solvent is accelerated and the solvent-containing air is evacuated from the working chamber.
5. e. Ventilation of the cleaning chamber, especially under normal atmospheric conditions. The solvent concentration in the cleaning chamber is monitored and the charge and discharge zone is not released until the concentration is below the values specified by the VOC guideline.

CO ₂ snow can also be used to clean the metallic surface of the drawer runner. The carbon dioxide snow is not toxic and ecologically harmless. Unlike the sandblasting process, which allows sand residue to remain on the rails and negatively affect runnability, CO ₂ snow sublimes after cleaning without residue. Hydrocarbons, fats and even silicones can be effectively removed by CO ₂ snow. This carbon dioxide particles are radiated through a nozzle on the surface to be cleaned and released gaseous carbon dioxide. By impulse transmission of the CO ₂ snow particles, the adhesion forces of the impurities are lifted on the surface. There are no chemical interactions of the carbon dioxide snow with the surface. This material-saving procedure is particularly advantageous in the area of the tracks of the pullout guide and ensures high running quality. Carbon dioxide purification is superior to conventional detergent-based cleaning.

A medium-fine cleaning with removal of particles with particle sizes of 10-50 μm can be achieved by treating a surface with CO ₂ snow followed by a wiping process in accordance with VDI 2083-4 and in some cases under the instructions on coarse particle size method mentioned in DIN EN ISO 14644-5. , Medium and fine cleaning done. Furthermore, the cleaning effect of the carbon dioxide snow can be attributed to the release of impurities due to differential thermal expansion of contaminants and surfaces due to the rapid temperature drop associated with embrittlement effects.

In this case, a mixing of CO ₂ snow and compressed air can take place after the exit from the separate nozzles or can advantageously already take place before exiting from a single nozzle. The cleaning effect by the carbon dioxide snow can be increased by cleaning additives, for example by pretreatment of the surface with the ecologically and toxicologically harmless cleaning additive succinate.

The assessment of the adhesive strength of the coating was carried out in accordance with DIN EN ISO 2409. It has been shown that coated drawer slides with a cross hatch mark of "1" show good practical suitability. In the case of the coatings applied according to the invention, however, the cross-cut characteristic value of "0" was predominantly not exceeded.

Before cleaning and coating, a roughness R _{a of} less than 2 μm in accordance with DIN 4768 was determined on the drawer guides. The measured values were preferably between 0.04 μm and 1.5 μm. It has been found that the surface roughness for the majority of the coatings has a sufficient structure for high adhesion.

The coatings preferably have a layer thickness between 8 and 50 μm.

Depending on the application, the coatings have a temperature resistance of up to 600 ° C.

Measurement methods and definitions adhesiveness

The adhesive strength of the coating was examined in the cross-cut test in accordance with DIN EN ISO 2409 (1994). In this test, a standard blade cutter is pulled over the coating under specified conditions. For the present tests of adhesion, a cutter with 6 blades is used. The cutting guide is repeated at an angle of 90 ° to the previous cutting test so that the cuts made in the surface by the blades form a grid.
Subsequently, a standardized transparent self-adhesive tape with a bond strength of 10 ± 1 N per 25 mm wide adhered to the surface and peeled off. The cut edges are then examined for spalling of the coating. The rating of the test results is in cross hatch values of 0 to 5, where the cross hatch value of 0 means that no chips were detected.

Roughness R _a

The surface roughness given in connection with this invention relates to the average roughness value R _a [μm] according to DIN 4768. The average roughness value R _a is the arithmetic mean of the absolute amounts of the distances y of the roughness profile from the middle line within a measurement path. The roughness measurement is carried out with electric stylus devices according to DIN 4772. For the measurement of the average roughness value R _a the measurement conditions are defined according to DIN 4768 T1.

LIST OF REFERENCE NUMBERS

1

pull-out guide

2

guide rail

3

middle rail

4

runner

5

clip

6

rolling elements

7

Rolling Element

8th

raceways

9

raceways

10

Plug

11

retaining bolt

Claims (14)

1. Method for producing a coated pull-out guide (1), in particular for baking ovens, comprising a rail (2) on which at least one further rail (3, 4) is displaceably supported by means of rolling elements (6), wherein the rolling elements (6) are guided along tracks (8, 9) on the rails (2, 3, 4), characterized by the following steps:

   i) at first assembling the pull-out guide (1) into a unit;

   ii) subsequently cleaning a metal surface of at least one rail (2, 3, 4) of the pull-out guide by a mechanical and/or chemical cleaning method; and

   iii) subsequently applying a coating to the cleaned metal surface.
2. The method according to claim 1, characterized in that the cleaning of the metal surface takes place at a temperature of 0 to 200°C, preferably at ambient temperature.
3. The method according to claim 1 or 2, characterized in that the tracks (8, 9) remain coating-free when applying the coating by masking or covering the tracks or by pushing the rails together during the coating process.
4. The method according to any one of the preceding claims, characterized in that the chemical cleaning process of the surface comprises the following steps:

   i) inserting the pull-out guide into a cleaning chamber,

   ii) cleaning the pull-out guide from impurities by wetting the surface with a cleaning solution,

   iii) transferring the contaminated cleaning solution into a processing unit,

   iv) processing the cleaning solution by removing impurities from the cleaning solution,

   v) transferring the processed cleaning solution into a storage tank,

   vi) returning the cleaning solution into a cleaning chamber.
5. The method according to any one of the preceding claims, characterized in that the cleaning of the metal surface is accomplished by a blasting process.
6. The method according to claim 5, characterized in that the blasting process comprises ice blasting, ice blasting with blasting media additive, carbon dioxide pellet blasting and/or carbon dioxide snow jets.
7. The method according to any one of the preceding claims, characterized in that the cleaning of the metal surface is accomplished by an ultrasound process.
8. The method according to any one of the preceding claims, characterized in that the cleaning of the metal surface is accomplished by a plasma process.
9. The method according to any one of the preceding claims, characterized in that the cleaning of the metal surface is accomplished by a laser cleaning.
10. The method according to any one of the preceding claims, characterized in that the cleaning of the metal surface is accomplished by a chemical process using liquid carbon dioxide, alkaline solutions, chalk and/or mordants.
11. The method according to any one of the preceding claims, characterized in that the cleaning of the metal surface is accomplished by electrolytic cleaning using alkaline and/or acidic solution.
12. The method according to any one of the preceding claims, characterized in that the coating comprises PTFE, PEEK and/or inorganic-organic hybrid polymer-containing coating.
13. The method according to any one of the preceding claims, characterized in that the application of the coating is accomplished by a plasma coating process.
14. The method according to any one of the preceding claims, characterized in that the application of the coating is accomplished by a sol-gel process and/or a spray process.

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