METHOD FOR PRODUCING A FITTING, FITTING, DOMESTIC APPLIANCE AND ITEM OF FURNITURE
A method of producing a fitting for domestic appliances or furniture. The fitting including a plurality of components connected to one another. The method includes the steps of providing the plurality of components by one or more of stamping and bending metal sheets, assembling the plurality of components to form a fitting, coating the fitting, at least in sections, by applying at least one coating, one or both of drying and burning-in the coating, treating a surface of plurality of components abrasively before the coating of the fitting, thereby setting a surface roughness of the plurality of components, and cleaning the surface of the plurality of components.
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This application is a national stage of International Application PCT/EP2011/055125, filed Apr. 1, 2011, and claims benefit of and priority to German Patent Application Nos. 10 2010 016 316.3, filed Apr. 1, 2010 and 10 2010 037 146.7 filed Aug. 24, 2010, the content of which Applications are incorporated by reference herein.
BACKGROUND AND SUMMARYThe present disclosure relates to: a method for producing a fitting; a fitting; a domestic appliance; and, an item of furniture.
EP 1 607 685 B1 discloses a method for producing a telescopic pullout system, which at least partially has a polytetrafluoroethylene, or PTFE, coating. This method presumes that a separate coating of the individual parts of the telescopic pullout is performed and these parts are subsequently assembled to form the telescopic pullout guide. The fitting parts must be transferred after the stamping and bending from the manufacturing facility to a coating facility, which is typically spatially separated from the manufacturing facility. However, in this method additional transport and temporary storage capacities must be provided for the transport of the individual components.
DE 10 2009 044 340 A1 discloses that a component is smoothed before a coating of an inorganic-organic hybrid polymer layer. Smoothing is made possible, for example, by polishing. The surface roughness decreases further.
Embodiments of the present disclosure provide an alternative method for producing a fitting, which fitting operates more economically.
The present disclosure thus relates to a method of producing a fitting for domestic appliances or furniture. The fitting includes a plurality of components connected to one another. The method includes the following steps: providing the plurality of components by one or more of stamping and bending metal sheets; assembling the plurality of components to form a fitting; coating the fitting, at least in sections, by applying at least one coating; treating a surface of the plurality of components abrasively before the coating of the fitting, thereby setting a surface roughness of the plurality of components; and cleaning the surface of the plurality of components one of before, during, and after the step of abrasively treating the surface of the plurality of components. The present disclosure also relates to a fitting for furniture, the fitting including a coating applied according to the just described method.
According to an embodiment of the present disclosure, a method for producing a fitting, which fitting is assembled from at least two components that are connected to one another, comprises the following steps:
-
- i) providing the components, for example, by stamping and bending metal sheets;
- ii) assembling the components to form a fitting;
- iii) at least sectionally coating the fitting by applying at least one coating; and
- iv) drying and/or burning-in the coating; and before the coating of the fitting, a treatment of the surface for setting a surface roughness is performed and at least one step of cleaning the surface to be coated is performed, which is carried out before, during, or after the treatment of the surface.
According to the present disclosure, an improvement of the adhesion of the coating on the surface of a preassembled fitting can be performed by a targeted setting of the surface roughness. This can, therefore, also allow the durability of the fitting by longer protection from environmental influences.
Damage to the coating, as is possible during a machine assembly of coated components, is additionally advantageously avoided. Assembled fittings occupy less space than individual components of a fitting during the transport and the temporary storage upon the transfer from a manufacturing facility into a coating facility. In addition, a more rapid production rate of fittings can be achieved based upon the method of the present disclosure.
Embodiments of the present disclosure are discussed herein, including in the claims.
According to the present disclosure, it is advantageous if the surface to be coated of the assembled fitting is brought to a surface roughness by an abrasive treatment. The surface roughness can be implemented more or less strongly dependent on the coating composition and coating thickness. The abrasive treatment can be performed, among other ways, by grinding, but may, for example, be done by abrasive blasting methods.
In an embodiment of the present disclosure, the individual components can also be abrasively treated before they are assembled to form a fitting. Before the assembly, burrs and other coarse irregularities can thus also advantageously be removed.
In an embodiment of the present disclosure abrasive, that is, material-eroding, methods, setting of the surface roughness can also be performed by applying at least one porous basecoat to the assembled fitting and/or the fitting parts. The porous basecoat advantageously causes the enlargement of the surface area, to which the coating can be applied in the subsequent step. The basecoat can be applied both before or after the assembly of the components, but may, for example, be performed after the assembly of the fitting, however, to avoid possible damage to the porous basecoat during the automatic assembly.
In an embodiment according to the present disclosure, at least one hard material coating is applied to the surface of the fitting as the porous basecoat. This hard material coating as the basecoat causes, in addition to the coating applied thereon, an additional protection of the surface from corrosion and scratches.
In accordance with an embodiment of the present disclosure, a further method for the abrasive treatment can be performed in abrasive blasting using an inorganic and/or organic blasting medium, since, in such a case, the surface roughness can be controlled by the impact velocity of the blasting medium on the surface. The use of sand in a sandblasting method has proven to be cost-effective, the blasting medium being able to be reused after appropriate reconditioning.
It is advantageous if the blasting medium is removed by being suctioned or flushed off in a cleaning step. That is so that the fitting is not restricted in its functionality by a remaining blasting medium and the coating does not have flaws due to the inclusion of sand grains.
In accordance with an embodiment of the present disclosure, a further cleaning step after the surface treatment can also comprise an alkaline cleaning and/or an ultrasonic cleaning, firmly-adhering dirt residues, oils, or remaining blasting medium being removed from the surface. An alkaline cleaning can be performed, for example, after an etching step, for setting the surface roughness.
A polymer, polymer derivative, or a polymer mixture having a fluoropolymer, but, for example, a perfluoroalkoxyalkane (PFA) and/or polytetrafluoroethylene (PTFE) can, for example, be selected as the coating to improve the anti-adhesive properties of the fitting.
If the fitting is not subjected to enhanced soiling conditions, the fitting can be coated using a polyether ketone, for example, a polyether ether ketone (PEEK), which has a lower anti-adhesive effect than fluoropolymers, but a higher scratch resistance.
In accordance with an embodiment of the present disclosure, an inorganic-organic hybrid polymer layer can also be applied as the coating to the surface of the fitting. Silicon-containing organic compounds may be preferred, which, in relation to the above-mentioned fluoropolymers and polyether ketone polymers, have a higher adhesive strength on the surface, for example, of metallic fittings, because of their inorganic silicon components.
Synergy effects can also advantageously be achieved by combining the various properties of the mentioned polymers in a polymer mixture with one another. It is advantageous if the fluoropolymers, the polyether ketones, and/or the inorganic-organic hybrid polymers are represented in a greater mass proportion than other components, for example, colorants and the like, in the composition of a coating.
It is advantageous if the method of the present disclosure is applied for coating a pullout guide which has a rail, on which at least one further rail is mounted so it is movable via roller bodies. The roller bodies are guided along runways on the rails and, before the abrasive treatment for setting the surface roughness. A part of the surface of the pullout guide is masked to protect the surface from material erosion and roughening.
In an embodiment of the method according to the present disclosure, the masking for the runways of the pullout guide is performed by covering the runways, so as not to negatively influence the sliding properties of the roller bodies in the runways. In addition, the coating can be, for example, easily eroded because of the high mechanical load in the sections of the runways at this point. In the event of uncontrolled damage of a coating in a section, the erosion of the coating can disadvantageously be accelerated, which is prevented by the protection of the runways.
After the step of coating and after the drying and/or burning-in of the inorganic-organic hybrid polymer, additional tempering of the coated fitting is performed. Organic components are at least partially oxidized, so that conversion and additional curing, which is linked thereto, of the hybrid polymer layer are performed. The tempering can be performed in an oxygen-rich or oxygen-poor atmosphere, an oxygen-rich atmosphere having a mass proportion of greater than 15% oxygen in the atmosphere and an oxygen-poor atmosphere having a mass proportion of less than 15% oxygen in the atmosphere.
Tempering in an oxygen-poor atmosphere, and, for example, in a nitrogen-rich atmosphere, may be preferred, since incomplete oxidation of the organic components of the hybrid polymer occurs, so that the surface coating is only partially cured and therefore can absorb shocks and impacts. Furthermore, better anti-adhesion properties are thus achieved.
Higher scratch resistance is achieved by tempering in an oxygen-rich atmosphere at at least 500° C., or, for example, approximately 650-750° C., such that the hybrid polymer layer cures completely. The completely cured hybrid polymer layer is suitable, for example, for use in ovens having pyrolysis function.
According to embodiments of the present disclosure, a fitting has a coating which is produced according methods of the present disclosure. This fitting is resistant with respect to corrosion and abrasive influences over a long time. In addition, it is suitable for mass production.
According to embodiments of the present disclosure, a domestic appliance or item of furniture has a fitting as just described. The fitting can be used in all domestic appliances. These include, among others, refrigerators, washing machines, and ovens. For use in ovens, a fitting must additionally be resistant to alternating temperatures up to at least 250° C. and also meet the specifications of the FDA, or Food and Drug Administration, regulations for the contact of plastics with foods and the regulation number 1935/2004 of the European Parliament and of the Council of 27 Oct. 2004 on materials and articles intended to come into contact with food, to be suitable for use in the field of food.
Other aspects of the present disclosure will become apparent from the following descriptions when considered in conjunction with the accompanying drawings.
A pullout guide 1 comprises a guide rail 2, which is fixable on a side grating in, for example, an oven, a side wall of an oven, or on a furniture body. A middle rail 3 is mounted so it is movable via roller bodies 6 on the guide rail 2. The middle rail 3 is used to mount a slide rail 4. At least two, or, for example, three runways 9 for roller bodies 6 are on the guide rail 2 and the slide rail 4 for mounting the rails 2, 3, and 4. The roller bodies 6 are held as a unit in a roller body cage 7. Furthermore, a total of at least four runways, or, for example, eight runways 8 for roller bodies 6 are on the middle rail 3. At least two runways 8 are assigned to the guide rail 2 and at least two runways 8 are assigned to the slide rail 4, respectively.
Two clamps 5 are fixed on the guide rail 2 for fastening the pullout guide 1 on, for example, a side grating of an oven. Other fasteners or fastening points can also be provided on the guide rail 2.
The pullout guide 1 is provided on the externally accessible region, that is, on the outer side of the guide rail 2 and the slide rail 4, with, for example, a PTFE-containing coating, or polytetrafluoroethylene-containing coating. A frontal stop 10, which is fastened on the slide rail 4, is also coated on its externally accessible regions with a PTFE-containing coating, for example. A holding pin 11 is also equipped with a PTFE-containing coating, for example. The clamps 5 are also equipped with a PTFE-containing coating, for example. The inner side of the slide rail 4 and the guide rail 2, on which the runways 9 for the roller bodies 6 are implemented, does not have a coating. The middle rail 3, which is arranged completely in the inner region of the pullout guide 1 when the slide rail 4 is arranged in the retracted position, also has no coating, at least in the region of the runways 8. The runways 8 can thus be formed by the material of the rails 2, 3, and 4. The runways 8 and 9 are typically produced from a bent steel sheet. Easy cleaning is made possible on the outer side by, for example, a PTFE-containing coating on the rails 2 and 4 on the outer side. The pullout guide 1 can thus be used in an oven, a high running quality being achieved over a long service life. An upper pullout having three rails 2, 3, and 4 is shown in
In addition to the PTFE-containing coating, the pullout guide can also have a PEEK-containing coating, a PFA, or perfluoroalkoxy-containing coating, and/or an inorganic-organic hybrid-polymer-containing coating.
The pullout guide shown in
The shaping or provision of a plurality of components identified with numerical descriptions 2-11, is performed in a first step 101. This is performed, for example, by stamping and bending a metal strip.
This is followed by a step 102, in which a treatment of the surface is performed by abrasive blasting to set a surface roughness. This setting can be specified by specifying one or more fixed parameters. These parameters can, for example, be the pressure at which the blasting medium leaves a corresponding blasting nozzle and/or the distance of the blasting nozzle from the surface to be treated. The blasting medium is not dry snow or ice.
An abrasive treatment, among others, such as, for example, abrasive blasting, in contrast to smoothing, results in the increase of the surface roughness. Thus, the average and the maximum roughness depths in relation to an untreated surface, an overall roughened surface texture is provided and, for example, protruding corners and burrs are eroded simultaneously.
The roughening of the surface improves the adhesion of the coating subsequently to be applied. The coating can “claw” into the provided surface structure. An intimate connection results between the surface and the coating, and the risk is therefore reduced that components or elements of the coating will detach from the surface. The coating becomes more resistant in relation to mechanical attacks, for example, by scrubbing pads or sharp objects.
In step 103, cleaning is performed by removing the blasting medium from the surface, for example, from the rails 2-4. This may be performed by suctioning or blowing off the blasting medium. In accordance with embodiments of the present disclosure, the pullout guide can also be flushed using a cleaning fluid.
In step 104, assembly of the individual components, with numerical designations 2-11, to form the pullout guide 1 is performed. The individual components 2-11 are plugged together and subsequently limited in their movement path by introducing notches or embossments into the rails 2-4.
Subsequently, the surface is freed of production residues in a further cleaning step in step 105. This can, for example, be performed by a cleaning fluid. The cleaning in this step is, for example, not performed by abrasive cleaning methods, so as not to cause a change of the surface roughness after step 102. The non-abrasive cleaning methods include, among others, non-abrasive blasting methods, ultrasonic cleaning, plasma cleaning, laser cleaning, steam cleaning, and chemical cleaning. For example, step 105 can be carried out in an alkaline cleaning medium under ultrasonic action. Furthermore, one or more flushing steps using demineralized water can follow, until a neutral pH value has resulted.
It is within the scope of the present disclosure that the cleaning of the surface in step 105 can be followed by drying of the pullout guide 1 in step 106. A first decision stage A can control whether or not drying is necessary as a function of the cleaning method.
Following the cleaning according to step 105 or the drying according to step 106, the coating of the pullout guide 1 is at least sectionally performed in step 107. Any high-temperature-resistant plastic comes into consideration, for example, mixtures containing PFA, PEEK, and/or PTFE. These solutions can be dispersed in a fluid, for example, water, and subsequently applied to the surface of the pullout guide 1 by lacquering or spraying.
It is within the scope of the present disclosure that an inorganic-organic hybrid polymer can be applied at least partially to the surface of the pullout guide 1 in a sol-gel method.
It is within the scope of the present disclosure that other modes of application can also be used, depending on the type of the applied plastics. Thus, for example, mixtures containing PEEK and PFA can be applied in a spraying method, for example, by plastic flame spraying.
The coating is followed in step 108 by drying of the applied coating, in which the fluid vaporizes and only the dispersed plastic particles remain on the surface of the pullout guide 1.
Depending on the type of the applied coating and the application method, burning-in of the coating material into the surface of the pullout guide can be performed in a step 109. The burning-in is carried out at 250-500° C. The burning-in time lasts a few minutes up to several hours depending on the temperature. For example, residual moisture is removed and a homogeneous polymer layer is implemented during the burning in.
Following the burning in, lubrication or application of lubricant to the pullout guide 1 is performed in step 110. The lubricant, like the applied coating composition, has to be high-temperature-resistant up to a temperature of at least 250° C. for the use of the pullout guide 1 in the field of ovens. Furthermore, the lubricant must be approved for the field of food.
It is within the scope of the present disclosure that step 110, for example, the application of lubricant, can also follow directly after the drying in step 108.
It is within the scope of the present disclosure that tempering can also be performed in step 111 following the drying in step 108. The tempering may, for example, be performed at a temperature above 200° C. Tempering according to step 111 may, for example, be performed if an inorganic-organic hybrid polymer is provided as the coating. Tempering could be performed, for example, by slow heating to the target temperature over 3 to 7 hours. The target temperature of, for example, 500° C. is maintained over 30 to 120 min. Slow cooling to ambient temperature is then performed.
The tempering can be carried out in a first tempering step 111a in a nitrogen atmosphere, the coating additionally being compacted. The anti-adhesive effect of the coated surface can advantageously be improved by the tempering step in an oxygen-poor, nitrogen-rich atmosphere. Such a surface is additionally more elastic and can absorb impacts on the pullout guide 1.
It is within the scope of the present disclosure that tempering can be performed in an air atmosphere with a mass proportion of approximately 20-25% O2 in the air, in a second tempering step 111b, the coating being at least partially oxidized, whereby greater hardness and scratch resistance is produced, for example, in an inorganic-organic hybrid polymer coating.
This scratch resistance can within the scope of the present disclosure, be increased, in that a third tempering step 111c is performed in oxygen-rich atmosphere and having an O2 mass proportion greater than 25% in the air, for example, at approximately 650-750° C.
The treatment of the coated component after the drying in step 108 can be controlled. A second decision stage B can be provided for this purpose, which regulates a step sequence directly after the drying. Thus, steps 109, 110, and 111a-c can directly follow step 108.
It is within the scope of the present disclosure that the second decision stage B can be automated, it being decided at least on the basis of one measurement parameter after the drying according to step 108 whether burning-in or a tempering step is necessary.
The layer thickness, the hardness, and/or an interfacial tension can, for example, be ascertained as actual values and compared to predefined target values. If the actual values correspond to the target values, the coated pullout guide 1 can, for example, be provided with lubricant directly in step 110 and subsequently can be packaged. Otherwise, for example, with inorganic-organic hybrid polymers, tempering can be performed by one or more tempering steps 111a-c or, in the case of PEEK, PFA, and PTFE, burning-in can, for example, be performed according to step 109.
The step sequence can be set by a third and a fourth decision stage C and D in such a manner that the oxygen supply and/or the temperature are increased step-by-step or continuously. That is so that the tempering is initially performed in oxygen-poor, nitrogen-rich atmosphere at approximately 500° C. over multiple hours and is subsequently performed in oxygen-rich atmosphere and/or at 700° C. over 10-30 min.
It is within the scope of the present disclosure that the third and fourth decision stages C and D can also be automated and can be performed by determination of at least one actual value and comparison to a target value, for example, the hardness, the layer thickness, or the interfacial tension. The transition from at least one oxygen-poor, nitrogen-rich tempering step 111a to one of at least two oxygen-rich tempering steps 111b, 111c or step 110 of lubricating the pullout guide is subsequently regulated. In addition, the decision stages B-D can also regulate the duration of each tempering step.
Subsequently, a quality control of pullout guide 1 is performed in a further step 112. It is within the scope of the present disclosure that parameters can be ascertained during the quality control, which can be used to control the tempering and burning-in steps, for example, the temperature, the duration, and the oxygen content during the burning-in or tempering of the coating of the pullout guide 1.
The pullout guide 1 is subsequently packaged and shipped.
After step 101, that is, the provision or shaping of the components 2-11, the assembly of the pullout guide 1 is performed in step 104.
Since the setting of the surface roughness may, for example, be performed using sandblasting, isolated surfaces of the pullout guide 1 are initially masked after the assembly. During masking according to step 113, a protective layer is applied against the abrasive treatment, for example, over the runways 8 and 9 of the pullout guide 1. This protective layer can have a wax-like consistency, for example, which at least damps the velocity of the blasting medium before it strikes the runways 8, 9 or entirely prevents the striking, so that erosion of material from the surface of the runways 8, 9 is no longer possible.
This is followed by step 102, that is, the setting of the surface roughness, roughening of the surface being performed by abrasive blasting using a blasting medium. Step 103 relates to the removal of the blasting medium from the surface and can advantageously be combined with step 105, a further cleaning step for removing production residues. This is followed by optional step 106, the drying of the pullout guide 1.
The pullout guide 1 is now provided with a coating in step 107 and subsequently processed further similarly to the method described in
The shaping of the individual components 2-11 of the pullout guide 1, the assembly of the pullout guide 1, and finally the cleaning of the pullout guide 1 are initially performed similarly to
In accordance with the present disclosure, an optional drying according to step 106 of the pullout guide 1 can be performed following the cleaning.
After the cleaning according to step 105 or the drying according to step 106, the coating of the pullout guide 1 with a porous basecoat is performed in a step 114. This basecoat increases the surface roughness. While material-removing or abrasive methods were described in
The porous basecoat acts as a type of adhesion promoter between the actual coating, which is subsequently applied, and the typically metallic surface of the fitting 1. For example, with fluoropolymers, such a porous basecoat has proven to be advantageous and improves the adhesion of PTFE, for example.
The basecoat can advantageously be implemented as a hard coating, so that in addition to increasing the surface roughness of the fitting 1, it also ensures an increase of the scratch resistance. For example, silicon carbide or silicon nitride are suitable as porous hard material coatings. They form a suitable basecoat for a coating using an inorganic-organic hybrid polymer, since the inorganic-organic hybrid polymer is based on a silicon-oxygen framework.
After the application of the basecoat according to step 114, a cleaning step 115 of the surface of the pullout guide 1 is optionally performed. This can, for example, be performed by a cleaning fluid. If this is the case, a step 116 of drying the surface can, within the scope of the present disclosure, follow cleaning step 115.
A sixth decision stage F connected downstream from cleaning step 115 ascertains the residual moisture of the surface and, subsequently thereto, supplies the pullout guide 1 either to a drying facility or directly to a further coating facility, which applies the actual coating to the surface of the pullout guide 1 in step 107.
As needed, cleaning step 115 can be performed or coating 107 can be performed directly. A fifth decision stage E regulates which of the two method steps is to be carried out after the application of the basecoat, that is, after step 114.
Further method steps 108-112, which can be carried out similarly to the embodiment in
Within the scope of the present disclosure, as an alternative to the method described in
According to another embodiment of the present disclosure, a measurement of the surface roughness is performed after the surface treatment according to step 102 and/or 114. If the surface roughness proves to be inadequate, the method step of surface treatment, for example, the abrasive blasting, is to be repeated.
This measurement of the surface roughness can, for example, be performed in the continuous production method by a laser measurement.
The method step of cleaning is required during the treatment of the surface due to the surface treatment by brushing. In contrast to the case of sandblasting, no foreign materials or residues, for example, blasting medium, remain on the surface. Additional wet-chemical cleaning of the surface can, for example, be performed in addition to the brushing.
Through the surface treatment, for example, by brushing, the adhesion of the coating on the surface is improved in relation to an untreated surface of the same material.
The brushing 117 may, for example, be performed by processing by rotating brushes from three sides, for example, by metal brushes whose contact pressure on the surface is individually settable. The shape of the brushes may, for example, be concave, in order to also reach corner regions of a rail profile, for example. Furthermore, however, no stamping is performed in step 101, the shaping, so that an endless profile results, which is isolated in a later processing step (not shown) before the assembly 104 of the components 2-11 to form the pullout guide 1.
The brushing is carried out using a brushing machine, in which one or more brushing stations are arranged. A total of three brushes, for example, may be used per brushing station.
The brushing is, for example, performed on the outer surfaces of the rails 2, 3, 4 of a pullout guide 1, that is, on the surfaces which are perceived by the observer of a respective rail 2, 3, 4 in the case of a pullout guide 1 in the retracted state.
An endless profile is guided in the feed direction through the brushing station. Two brushes stand opposite to one another in a brush assembly of the brushing station and allow the surface processing from diametrically opposite lateral external surfaces of the endless profile. For example, the brushes each execute a linear movement toward the endless profile. A third brush for processing an upper side of the endless profile executes a second linear movement, for example, perpendicular to the plane of the first linear movements and the feed direction.
The brushes are arranged on a shared linear carriage, which has a defined travel path. The movement of the linear carriage is performed, for example, via a servomotor, the contact pressure of each individual brush being individually settable. Multiple brush assemblies can also be arranged on one linear carriage.
The speed of the brushes is settable via frequency rectifiers to implement a uniform profile on all sides of the endless profile. The brushes are each operated by a separate drive.
At least “matte gloss” according to DIN 67530 is ensured on the surface by the brushing 117.
During the brushing, the profile is freed of longitudinal grooves, which can already be present in the starting material and are only removable with difficulty using means known from the prior art.
It is within the scope of the present disclosure that, as an alternative, the surface is cleaned by treatment with ultrasound 118, a liquid medium being applied to the surface of the components 2-11 and subsequently ultrasonic waves are transmitted to the liquid medium by an ultrasound generator with the aid of a sonotrode. These ultrasonic waves result in the formation and implosion of gas bubbles because of cavity effects in the liquid medium, whereby adhering contaminants are eroded from the surface of the component.
In an embodiment of the present disclosure that includes cleaning by brushes, the feed velocity of the profile or the component is at least twice the feed velocity of the brushes.
A high gloss without brushing and at least matte gloss with brushing can, within the scope of the present disclosure, be achieved on the surface by the treatment using ultrasound 118.
The treatment using ultrasound 118 and the brushing 117 are performed in a an embodiment of the present disclosure on an endless profile. The isolation of the endless profile to form components of a pullout guide 1 (not shown) being performed subsequently to the treatment using ultrasound 118.
Such an embodiment is advantageous, since it is easily possible to guide an endless profile in a manufacturing facility in the production process.
The cleaning process in the ultrasound station can be controlled by ascertaining the profile brilliance. This is performed by regulating the feed velocity of the profile and the vibration amplitudes.
The degree of soiling, a further criterion for the quality of the cleaning method, can subsequently be determined by a wiping test.
A soft cloth is rubbed over the profile surface and the degree of soiling is determined visually. In embodiments of the present disclosure, the cloth does not have any perceptible soiling.
Improved corrosion resistance, for example, surface corrosion resistance, in relation to untreated profiles was proven by a 96 hour salt spray test. An evaluation was performed after 16 hours, 24 hours, 72 hours, and 96 hours.
Since the components used in the assembly of the components 2-11 to form the pullout guide 1 are already precleaned, for example, high-gloss components, additional cleaning 105, as shown in
The metallic gloss of the profile is, advantageously, maintained in the case of a transparent coating.
Different ways of processing for components 2-11 of a pullout guide 1 are shown in
In further components of the pullout guide 1, for example, a stop 10, a clamp 5, and/or a roller body 6, after the shaping 119, roughening of the surface is performed by abrasive blasting 120 using a blasting medium.
After the assembly of the pullout guide 1, remaining contaminants on the surface and the runways 8, 9 of the pullout guide 1 are established in the decision stage G and, if they are present, a cleaning 105 is carried out, which is optionally followed by drying 106. If the surface and the runways 8, 9 of the pullout guide 1 are free of contaminants, a coating step 107 and a following method sequence, similar to
In a decision step H, in an embodiment of the method sequence, the surface roughness is measured and subsequently a method of surface processing is determined as a function of the degree of the measured surface roughness. Following the brushing 117 or the abrasive blasting 102, a high-gloss surface free of grease, oil, or other deposits is provided by an ultrasonic cleaning 118.
It is within the scope of the present disclosure that in an alternative embodiment, the rails of the pullout guide 1 are isolated directly after the shaping 101 and assembled together with further components by assembly 104 to form the pullout guide 1.
Further components of the pullout guide 1 are surface treated similarly to
The method shown in
The surface is thus also freed of contaminants.
In another embodiment according to the present disclosure, the rails 2-4 of the pullout guide 1, for example, the guide rail 2 and the slide rail 4 and optionally the middle rail 3, at least sectionally have a brushed surface before the coating. The texture of the surface has a main orientation direction, in the longitudinal direction of the rails 2, 3, 4, and includes a plurality of grooves having low penetration depth of, for example, less than 7 μm in the surface, which have individual orientation directions. The mean value of the individual orientation directions or the direction vectors of the grooves specifies the main orientation direction of the texture or the surface structure. The pullout guide 1 is matte gloss. The scatter of the mean roughness value of the metallic surface after the brushing is decreased in relation to an unbrushed surface. The scatter of the mean roughness value of the metallic surface is, for example, less than half of the scatter of an unbrushed surface. The scatter of the mean roughness value is an index of whether a surface having homogeneous roughness is provided or whether a surface has irregularities. An uneven surface can have channels and tension cracks of a maximum roughness depth of greater than 7 μm, for example. The brushed surface extends at least over the entire outer surface of the respective rail, that is, the surface which is visible to the end user in the case of a pullout guide 1 in the installed state.
In addition to the measurement of the mean roughness value Ra, an ascertainment of the average roughness depth Rz and the maximum roughness depth Rmax can also be performed, in order to obtain more detailed specifications on the roughness of the surface. Metal sheets made of stainless steel, which have been subjected to an abrasive treatment of the surface to set a surface roughness, and an untreated metal sheet made of stainless steel are compared hereafter. The maximum roughness depth and the average roughness depth for the roughened metal sheet and the untreated metal sheet were ascertained.
In the present embodiment, the abrasive treatment is performed by a brushing procedure. The metallic surface of the fitting 1 is guided past a brushing station. The brushing station has brushes which are equipped with special grinding bristles. Bristles impregnated with abrasive medium as a trimming material for brushes for finish processing are designated as grinding bristles. The bristle material can include nylon, for example. Silicon carbide, aluminum oxide, chromium oxide, diamond, and/or zirconium may, for example, be used as the abrasive medium. The grinding effect results through the hard and sharp tips of the grinding material which is enclosed in the brush material, for example, nylon. During the processing of workpieces, a specific quantity of the abrasive medium is always released by the wear of the brush material.
The parameters 80, 120, 240, and 2000 therefore correspond to the grain size of the grinding bristles of the respective brush trimming with which the surface of a fitting 1 has been roughened by abrasive treatment. The designation “series” identifies the surface roughness of an untreated fitting. The designation “ultrasound” reflects the measured values of the maximum roughness depth and average roughness depth as parameters of the surface roughness of a surface of a fitting 1 cleaned using ultrasound.
The measurement was carried out in the case of the 120 grain size, the series, and the ultrasound measured values on three fittings respectively, a triple measurement having been performed on each of the three different fittings. A total of nine measurements were thus carried out per measured value.
A total of six measurements were carried out on the same fitting in the case of the 80, 240, and 2000 grain sizes. The measured values in the following table were measured using stainless steel of the alloy 1.4301 (WNr. 1.4301 (X5CrNi18-10), AISI 304 (V2A)).
The measured values in the following table were measured employing stainless steel of the alloy 1.4016 (WNr. 1.4016 (X6Cr17), AISI 430).
It can be seen, on the basis of the measured values, that roughening of the surface has occurred as a result of the abrasive treatment, by brushing here. The measurement of the surface roughness was performed using a Hommel Tester T1000.
In an embodiment of the present disclosure, the average roughness depth Rz of the fitting after the abrasive treatment of the surface is greater than 1.85 or, for example, greater than 2.0 or, for example, greater than 2.7
The mean value of the average roughness depth Rz of the fitting from at least six measurements is, for example, 3.0-4.0 μm.
The mean value of the maximum roughness depth Rmax of the fitting from at least six measurements is, for example, greater than 3.3 μm, or, may be greater than 3.5 μm. The mean value of the maximum roughness depth Rmax from at least six measurements is, for example, 3.8-5.2 μm.
In spite of the increased measured values of the average roughness depth and the maximum roughness depth in relation to the surface of an untreated fitting, the mean roughness value is, for example, between 0.3-0.49 μm. A uniformly roughened surface may therefore be concluded with simultaneously increased roughness depth.
In an embodiment according to the present disclosure, the surface after the abrasive treatment therefore has a mean roughness value Ra of less than 2 μm, or, for example, less than 0.8 μm, or, for example, less than 0.5 μm.
In another embodiment according to the present disclosure, the outer surfaces of the pullout guide 1 have a high-gloss surface. This is achieved by a treatment using ultrasound 118. The mean brilliance of the metallic surface is, with a 60° geometry, greater than 150, or may be, for example, greater than 200, and is carried out based on DIN 67530 using a measuring device REFO 60 from Hach-Lange.
The following table describes the improved gloss behavior of the fitting 1 due to the cleaning of the surface of the fitting to be coated, which causes an improvement of the appearance of the fitting 1 and simultaneously provides a larger surface for applying the coating.
The mean value shown in the table is the ascertained brilliance of the surfaces before and after cleaning by ultrasound.
The measurement of the brilliance was performed using an REFO 60 portable 60° angle reflectometer, the measured gloss units being specified according to DIN 67530.
In an embodiment according to the present disclosure, a metallic surface after the step of cleaning the surface to be coated according to a method disclosed herein has a brilliance of at least 120, or, for example, at least 140, or, for example, at least 190.
Cleaning of the surface is, for example, performed in a non-thermal cleaning method in accordance with the present disclosure.
Measuring methods and definitions are next discussed.
Roughness Ra
The surface roughness specified in the context of the embodiments of the present disclosure relates to the mean roughness value Ra, or μm, according to DIN 4768. The mean roughness value Ra is the arithmetic mean value of the absolute values of the distances y of the roughness profile from the center line within a measuring section. The roughness measurement is performed using electrical stylus instruments according to DIN 4772. The measurement conditions are established according to DIN 4768 T1 for the measurement of the mean roughness value Ra. The measurement was performed transversely to the texture of the surface.
The distance of two parallels to a center line, which contact the measured actual profile at the highest point and at the lowest point within an individual measuring section, is designated as the individual roughness depth Zi.
The average roughness depth Rz, in μm, is the arithmetic mean of the individual roughness steps Zi of five equidistant adjoining individual measuring sections.
The maximum roughness depth Rmax, in μm, is the greatest value of five individual roughness depths Z1 to Z5.
Corrosion monitoring
To monitor the nucleation process and the corrosion behavior, the electrochemical noise is tracked by electrochemical measuring apparatus. Stainless steels are enclosed by a protective passive layer of only approximately 1-20 nm thickness, which can also partially regenerate itself in the event of damage. This layer is typically thinner than the wavelength of visible light, so that it is not perceptible using typical optical microscopes. The formation, damage, and regeneration of the passive layer is dependent on the corrosive medium, the metal, and the design. The design is determined by the surface roughness, the type of joining, structurally related gaps, and the overall structure. The influence of the corrosive medium is determined by the concentration of, for example, corrosion-promoting agents, such as chloride ions, the temperature, and the flow velocity of the corrosive medium. Corrosion can occur on stainless steels in the event of the deviation of parameters, for example, the local oxygen concentration, the extent of possible nuclei on the surface, and the achievement of a critical temperature range. Damage to the passive layer by tension cracks and corrosion of the surface can possibly also occur as a result of the shaping.
Dissolving processes and layer formation processes of the passive layer oppose one another. As a result, the passive layer is not a constant-thickness cover layer, but rather is subject to a dynamic equilibrium.
If a liquid medium is subsequently deposited on a metal surface, metal ions go into solution. The remaining electron excess and the potential change are detectable. Corrosion always forms in energetically preferred regions, for example, local contaminants or flaws in the layer, such as scratches or upon the processing of pressed-in foreign bodies. These locally delimited regions are typically only briefly available, so that the passive layer can form again. In some cases, however, gap corrosion or progressing hole corrosion occurs.
The nuclei and corrosion regions are perceived as a result of the potential changes as a varying signal sequence, the so-called electrochemical noise. Causes of electrochemical noise on passive metals are the activation and repassivation processes of the passive layer or the variations thus induced of the charge at the phase interface metal passive layer/electrolyte, respectively. These charge variations can be measured as current or potential noise depending on the experimental setup. However, this method is used in the present embodiments for the quality control of the surface composition after the cleaning of the pullout guide 1 by brushing, treatment using ultrasound, and/or treatment using plasma, in order to ensure the quality of the cleaning and the presence of a nucleus-free passive layer. Damage to the surface, as is necessary in other control methods, does not have to be performed in the present embodiments. In addition, ultrasmall nuclei which are barely visually perceptible can be detected and the corresponding cleaning method can be optimized to reduce the number of these nuclei. The occurrence of an increased concentration of compounds having chloride ions on the surface, for example, by salt water spray and the like, is also detectable in this manner.
Brilliance
A mean brilliance indicates the extent to which light is reflected upon incidence on the fitting 1. The brilliance is divided in the case of metallic surfaces into high gloss, medium gloss, and matte gloss and is defined based on DIN 67530. The brilliance is measured for different geometries, for example, 20°, 60°, and 85°. The determination of the brilliance is a standardized measuring method according to DIN 67530. The measurements were carried out based on DIN 67530.
Although the present disclosure has been described and illustrated in detail, it is to be clearly understood that this is done by way of illustration and example only and is not to be taken by way of limitation. The scope of the present disclosure is to be limited only by the terms of the appended claims.
Claims
1. A method of producing a fitting for domestic appliances or furniture, the fitting including a plurality of components connected to one another, the method comprising the following steps:
- providing the plurality of components by one or more of stamping and bending metal sheets:
- assembling the plurality of components to form a fitting:
- coating the fitting, at least in sections, by applying at least one coating:
- one or both of drying and burning-in the coating;
- treating a surface of the plurality of components abrasively before the coating of the fitting, thereby setting a surface roughness of the plurality of components; and
- cleaning the surface of the plurality of components one of before, during, and after the step of abrasively treating the surface of the plurality of components.
2. The method according to claim 1, further comprising the step of treating the surface of one of the assembled fitting and the individual components and by applying at least one porous basecoat.
3. The method according to claim 2, wherein the porous basecoat comprises at least one hard material coating.
4. The method according to claim 1, wherein the abrasive treatment is performed by abrasive blasting using one or more of a mineral and organic blasting medium.
5. The method according to claim 4, wherein the cleaning of the plurality of components comprises at least removing the blasting medium by one of suctioning and flushing.
6. The method according to claim 1, wherein the cleaning of the plurality of components comprises one or more of alkaline cleaning and ultrasonic cleaning.
7. The method according to claim 1, wherein the coating includes at least one of a polymer, polymer derivative, and a polymer mixture, selected from a group consisting of:
- fluoropolymers;
- polyether ketones; and
- inorganic-organic hybrid polymers.
8. The method according to claim 1, wherein the coating includes one of a polymer and polymer derivative selected from a group consisting of:
- fluoropolymers;
- polyether ketones; and
- inorganic-organic hybrid polymers.
9. The method according to claim 1, wherein the fitting is a pullout guide, including a guide rail, on which at least one of a middle rail and a slide rail is mounted and configured to be movable via roller bodies, the roller bodies being guided along runways on one or more of the rails, and further comprising a step of masking of a part of a surface of the pullout guide being performed before the abrasive treatment step to set the surface roughness.
10. The method according to claim 9, wherein the masking includes a masking on the runways that is performed by covering the runways by applying a wax-like substance.
11. The method according to claim 1, wherein after one or both of the drying and the burning-in of the coating, a tempering of the coated fitting is performed.
12. The method according to claim 11, wherein the tempering is performed in an oxygen-poor atmosphere.
13. The method according to claim 12, wherein the tempering the oxygen-rich atmosphere is performed at at least 500° C.
14. The method according to claim 1, wherein the cleaning step is performed using one of ultrasound and plasma.
15. The method according to claim 1, wherein the treatment of the surface is performed by brushes.
16. The method according to claim 9, wherein the cleaning step includes using brushes and which cleaning step is performed at least on the outer surfaces of the rails of a pullout guide.
17. The method according to claim 1, wherein an average roughness depth of the fitting after the abrasive treatment of the surface is greater than 1.85 μm.
18. A fitting for furniture, the fitting including a coating applied according to claim 1.
19. A domestic appliance including a fitting according to claim 18.
20. An item of furniture including a fitting according to claim 18.
21. The method according to claim 7, wherein the fluoropolymers include one or more of perfluoroalkoxyalkanes and polytetra fluoroethylene, and the polyether ketones include polyether ether ketones.
22. The method according to claim 8, wherein the fluoropolymers include one or more of perfluoroalkoxyalkanes and polytetra fluoroethylene, and the polyether ketones include polyether ether ketones.
23. The method according to claim 12, wherein the tempering in the oxygen-rich atmosphere is performed at approximately 650-750 ° C.
24. The method according to claim 1, wherein an average roughness depth of the fitting after the abrasive treatment of the surface is greater than 2.0 μm.
25. The method according to claim 11, wherein the tempering is performed in a nitrogen-rich atmosphere.
Type: Application
Filed: Apr 1, 2011
Publication Date: May 23, 2013
Applicant: PAUL HETTICH GMBH & CO. KG (Kirchlengern)
Inventors: Peter Jährling (Bunde), Daniel Rehage (Bielefeld), Kathrin Urban (Ravensburg), Lars Schrubke (Kirchlengern), Arthur Krause (Lubbecke), Friedrich Meyer (Bohmte), Andre Eckholt (Lomimgen)
Application Number: 13/638,800
International Classification: B21D 53/10 (20060101); A47B 88/04 (20060101);
