CN108691178B - Household appliance comprising at least one metal component - Google Patents

Abstract

The household appliance (12) according to the invention comprises at least one metallic component (14, 16), the component (14, 16) having a treated surface (17, 18), wherein the treated surface (17, 18) comprises a directly mechanically formed sub-millimeter structure (6). The method (S1) for treating a surface (17, 18) of a metallic component (14, 16) of a household appliance (12) according to the invention, wherein the surface (17, 18) is treated by mechanically forming a submillimeter-scale structure (6) directly on the metallic surface (17, 18). The invention is particularly advantageous for laundry treatment appliances, in particular laundry dryers, in particular comprising a heat pump.

Description

Household appliance comprising at least one metal component

Technical Field

The invention relates to a household appliance comprising at least one component having a treated surface. The invention also relates to a method for treating the surface of a metallic component of a household appliance. The invention is particularly useful for laundry treatment appliances, in particular laundry dryers, in particular comprising a heat pump.

Background

Laundry drying appliances typically use a heat exchanger to cool and/or heat the process air flowing in the process air channel. The heat exchanger has a heat exchanging surface exposed to process air from a laundry compartment, such as a drum. The process air typically contains moisture, fluff, hair, and the like. Especially if a heat exchanger is used to cool the process air, the content of the process air may remain on the heat exchange surfaces. Although the moisture may condense and mostly drip into the condensation basin or container, some condensate may remain on the heat exchange surfaces and reduce the effectiveness of the heat exchange. In addition, fluff and hair may stick to the heat exchange surface, further reducing effectiveness.

In order to keep the heat exchange effectiveness at a high level, it is known to clean the heat exchange surface by directing a jet or spray of water onto the surface. However, some fluff, hair, etc. may remain on the surface. Moreover, such cleaning devices can be expensive and require a large internal space.

It is also known to treat heat exchange surfaces by applying a non-stick coating to improve cleanability thereof. The disadvantage of applying such a coating is that it is costly and the coating itself reduces the heat exchange effectiveness.

Laundry drying appliances using heat pumps are known. For example, EP 1964965 a1 discloses a household appliance comprising a drying chamber for drying wet articles in the drying chamber, a process air circuit for circulating process air for drying the articles, and a heat pump. The heat pump includes a pumping circuit containing a pumping fluid to be circulated through the pumping circuit, an evaporator heat exchanger for transferring heat from process air into the pumping fluid by evaporating the pumping fluid, a liquefier heat exchanger for transferring heat from the pumping fluid to process air by liquefying the pumping fluid, a compressor for compressing the pumping fluid and driving the pumping fluid through the pumping circuit, and a nozzle for depressurizing the pumping fluid.

As another example, EP 2253757 a1 discloses a household appliance having a housing and comprising within the housing a control unit, a drying chamber for accommodating articles to be dried, a closed-loop process air channel for conveying process air along the articles for drying having a first blower operable by the control unit, a heat pump unit operable by the control unit for extracting moisture from the process air, a condensate collector for collecting condensate formed there by the heat pump unit, and means for cooling at least one component of the heat pump unit, the means comprising a second blower operable by the control unit, the means for cooling includes an open-loop cooling channel having the second blower for conveying cooling air from outside the housing to the at least one component. Further, the cooling channel includes a guide including the second blower, the guide connecting an inlet in the housing to the at least one component for cooling. The housing has a plurality of outlets so that cooling air can flow out of the housing.

WO 2013/144875 a1 discloses a heat exchanger comprising at least one set of tubes, each set of tubes comprising at least two tubes, wherein the tubes are mechanically connected by at least one connecting structure. At least two tubes are made of different metals having different coefficients of thermal expansion; at least two of the pipes having different coefficients of thermal expansion are connected by a soldered or brazed connection. At the junction of the two tubes, a tube made of a metal having a lower coefficient of thermal expansion is embedded in a tube made of a metal having a higher coefficient of thermal expansion. The invention also relates to a household appliance, in particular a laundry treatment appliance, comprising at least one such heat exchanger, and to a method for manufacturing such a heat exchanger.

WO 2015/068092 a1 discloses a heat pump designed for a household appliance, in particular a laundry treatment appliance, comprising a rotary compressor, a condenser, a flow restrictor and an evaporator, wherein the condenser is of the expansion tube fin type, the outer diameter of the tube of which is less than 7mm, and wherein the ratio of the height to the radius of the rollers is between 1.4 and 1.2. A household appliance, in particular a laundry treatment appliance, comprises such a heat pump.

US 2009/0046362 a1 discloses an apparatus and method for a nanopatterning process for making nanostructures. Roller dies are used to continuously imprint nanostructures onto flexible ribbons or rigid substrates. The process includes a coating and embossing module that simultaneously rotates the ribbon. A liquid resistant material is used for imprinting and the pattern is cured by thermal or UV curing. The process is used to produce double layer metal wire grid polarizers, organic solar cells and organic light emitting diodes.

US2009/0162623a1 discloses a method for structuring a surface, i.e. for forming at least one array of features having a lateral feature dimension of the sub-millimeter order on a planar surface of a product comprising a rigid glass element and at least one layer attached to said glass element, the structuring being performed on said layer, the surface structuring by plastic or viscoplastic deformation being performed by contact with a structuring element, called a mask, by application of pressure, the structuring being performed by continuous movement of the product parallel to the surface and movement of the mask about an axis parallel to the plane of the surface of the product. US2009/0162623a1 also relates to glass products having a structured surface and to the use thereof.

Disclosure of Invention

It is an object of the present invention to at least partially overcome the problems associated with the prior art. A particular object of the present invention is to provide a component of a laundry treatment appliance, the surface of which has improved functional properties, wherein the surface has been improved in a particularly cost-effective and environmentally friendly manner.

This object is achieved according to a feature of the present invention. Advantageous and permissible embodiments can be derived, for example, in the technical solutions of the invention, in the following description and in the drawings.

This object is achieved by a household appliance comprising at least one metallic component having a treated surface, wherein the treated surface comprises a directly mechanically formed sub-millimeter structure.

The household appliance has the following advantages: by virtue of the submillimeter-scale structure, the surface may exhibit improved functional properties (e.g. hydrophobicity or oleophobicity) in a particularly cost-effective manner. For example, the formation may be accomplished as a single step process. It is not necessary to apply a coating or cure to achieve the desired properties as required, for example, by thermal forming or UV roll-to-roll forming. This in turn saves material, reduces manufacturing complexity, saves energy, and achieves higher durability and higher chemical resistance. Thus, better environmental protection is also achieved.

The household appliance may be a household appliance. The household appliance may be a large appliance or a large household appliance, i.e. a large machine for everyday household tasks, for example for cooking and/or baking (e.g. ovens and/or cooking ovens), washing and/or drying laundry or food preservation (e.g. refrigerators and/or freezers).

One embodiment is: the household appliance is a laundry drying appliance. The laundry drying appliance may be a dryer or a combined washing/drying machine ("washer-dryer"). The laundry drying appliance may comprise at least one heat exchanger.

One embodiment is: the laundry drying appliance comprises a process air channel, within which at least one heat exchanger is located. Advantageously, at least two heat exchangers are located in the process air channel.

The process air channel may be part of a closed circuit ("process air circuit") and may connect the process air outlet of the laundry compartment to the process air inlet of the laundry compartment. The laundry compartment may be a rotatable drum, in particular a horizontally rotatable drum. Alternatively, the process air channel is an open channel.

In case of at least two heat exchangers, these heat exchangers may comprise a first heat exchanger, which is closer to the laundry compartment than a second heat exchanger in the flow direction of the process air from the laundry compartment. Thus, the process air from the laundry compartment reaches the first heat exchanger first and then the second heat exchanger. The first heat exchanger may be used to cool warm and humid process air. By cooling the process air, condensate may be formed at the heat exchange surfaces of the first heat exchanger. Fluff and hair carried by the process air tend to stick to the moist heat exchange surfaces. After passing through the first heat exchanger, the process air is significantly cooler and cleaner. The process air then passes through a second heat exchanger where it is heated. After the second heat exchanger, the process air may re-enter the laundry compartment again.

One embodiment is: the heat exchanger is a component of a heat pump. In particular, the first heat exchanger may be an evaporator of a heat pump, and the second heat exchanger may be a condenser of the heat pump.

The at least one component having a treated surface may in particular be a component having a surface exposed to the process air, for example a heat exchange surface of a heat exchanger.

The treated surface is a mechanically formed surface, in particular comprising a surface which has been permanently (e.g. plastically or viscoplastically) deformed by mechanical means or loading to produce a corresponding sub-millimeter structure.

The treated surface is a directly mechanically formed surface, in particular comprising a tool for forming (deforming) the surface interacting directly with the surface, e.g. pressing the surface in direct contact. Thereby avoiding the use of intermediate coatings and the like.

In particular, sub-millimeter structures include or are micro-or nano-scale structures.

In the case of a micro-scale structure, the surface comprises at least one local micro-scale object having at least one lateral dimension (e.g. length) of at least 1 micrometer but less than 1000 micrometers, in particular at least 1 micrometer but less than 100 micrometers, in particular at least 1 micrometer but less than 50 micrometers.

One embodiment is: the other lateral dimension (e.g. width) also has a dimension of at least 1 micron but less than 1000 microns, in particular at least 1 micron but less than 100 microns, in particular at least 1 micron but less than 50 microns.

One embodiment is: the depth of the micro-scale object has a dimension of at least 1 micrometer but less than 1000 micrometers, in particular at least 1 micrometer but less than 100 micrometers, in particular at least 1 micrometer but less than 50 micrometers.

One embodiment is: the spacing between adjacent micro-scale objects is at least 1 micron but less than 1000 microns, particularly at least 1 micron but less than 100 microns, particularly at least 1 micron but less than 50 microns.

In the case of nanoscale structures, the surface comprises at least one nanoscale object having at least one lateral dimension (e.g. length) of at least 1 nanometer but less than 1000 nanometers, in particular at least 1 nanometer but less than 100 nanometers, in particular at least 1 nanometer but less than 50 nanometers.

One embodiment is: the other lateral dimension (e.g. width) also has a dimension of at least 1 nanometer but less than 1000 nanometers, in particular at least 1 nanometer but less than 100 nanometers, in particular at least 1 nanometer but less than 50 nanometers.

One embodiment is: the depth of the nano-scale objects has a dimension of at least 1 nanometer but less than 1000 nanometers, in particular at least 1 nanometer but less than 100 nanometers, in particular at least 1 nanometer but less than 50 nanometers.

One embodiment is: the spacing between adjacent nanoscale objects is at least 1 nanometer but less than 1000 nanometers, particularly at least 1 nanometer but less than 100 nanometers, particularly at least 1 nanometer but less than 50 nanometers.

One embodiment is: the sub-millimeter structure is a micron-scale structure. Thus, the surface of the metallic component shows micro-scale objects without nano-scale objects. This embodiment can be realized in a particularly inexpensive manner.

One embodiment is: submillimeter-scale structures are nanoscale structures. Thus, the surface shows nanoscale objects but no microscale objects.

In general, the submillimeter-scale structure may be or comprise a combination of micro-scale and nano-scale structures, i.e. the submillimeter-scale may comprise at least one directly formed micro-scale object and at least one directly formed nano-scale object.

One embodiment is: the surface of the metal includes at least one nano-scale object within at least one micro-scale object. In particular, the surface of the metal includes nano-scale structures within micro-scale structures. This has the following advantages: a particularly high functionality can be achieved on a small area. For example, the micro-scale objects may be recesses or depressions, the bottom of which comprises one or more than two formed nano-scale objects. In another example, the micro-scale objects may be protrusions, the top of which includes one or more formed nano-scale objects.

The micro-or nano-scale objects may be recesses or protrusions formed in a ring shape, a cylindrical shape, a box shape, a pyramid shape, a conical shape, a line shape, a wedge shape, etc. In general, the form of the micro-or nano-scale objects is not limiting.

In general, the sub-millimeter structures may be formed by any suitable mechanical means, in particular by embossing.

One embodiment is: the sub-millimeter structure is a roll-to-roll (roll-to-roll) imprinted structure. The use of a roll-to-roll embossing process has the advantage of being particularly easy to implement and of being cost effective to operate. Moreover, the maintenance cost is low. Furthermore, roll-to-roll embossing enables continuous embossing of endless workpieces, for example rolls (coils).

One embodiment is: the household appliance is a laundry drying appliance comprising at least one heat exchanger, wherein the directly mechanically formed sub-millimeter structured metal surface is a heat exchange surface of the heat exchanger. This has the following advantages: the heat exchanging surface may be implemented such that it is less prone to attachment of fluff and hairs. This in turn enables higher heat exchange effectiveness, and/or less need for cleaning surfaces. Thus, smaller cleaning devices can be used, or even cleaning devices can be dispensed with altogether. For this purpose, the heat exchange surface may comprise a sub-millimeter structure (non-stick surface) that reduces the adhesion of hairs and fluff. Alternatively or additionally, the sub-millimeter structure may exhibit a hydrophobic and/or oleophobic functionality.

One embodiment is: the heat exchanger is a finned tube heat exchanger. One embodiment is: the heat exchange surface is a surface of at least one fin of a finned tube heat exchanger. This is particularly advantageous because the fins are more covered by fluff, hairs, etc. than other parts of the heat exchanger. Moreover, the distance between adjacent fins may be small, making the non-stick properties of the fins particularly important.

The object is also achieved by a method for treating a surface of a metal of a component of a household appliance, wherein the surface is treated by mechanically forming a sub-millimeter structure directly on the surface of the metal. The method can be implemented similarly to the household appliance described above and has the same advantages.

Forming the sub-millimeter structure may include mechanically embossing the sub-millimeter structure directly onto the surface.

One embodiment is: the embossing is roll-to-roll embossing. Roll-to-roll embossing may use two parallel ("embossing") rollers arranged adjacent to each other, or even the rollers may be arranged staggered or not arranged facing each other. The metal workpiece may be fed between the rollers or fed past the rollers such that the rollers roll on the respective surfaces of the metal workpiece. The workpiece is subjected to pressure from the roller, thereby impressing the surface. The contact surface of at least one roller comprises an embossed structure ("embossed pattern") which is a negative image of a sub-millimeter structure to be produced on the surface of the metal of the workpiece. If, for example, recesses are to be produced on the surface, the roller may comprise adapted protrusions, and vice versa.

One or both of the embossing rollers may include an embossing pattern. If the workpiece is to be embossed on both sides, the workpiece may pass the rollers once if both rollers comprise an embossed pattern, or may pass the rollers twice if only one of the rollers comprises an embossed pattern.

In one embodiment, the pressure applied to the rollers or to the workpiece by the rollers may be up to 5000 MPa.

To protect the imprinted pattern from wear and damage, the roller may have an additional hard coating, such as a diamond coating or a coating of boron nitride, boron carbide, or the like.

One embodiment is: roll-to-roll embossing is performed using a heated roll. This has the advantage that metals are more susceptible to plastic or viscoplastic deformation. This is particularly advantageous for small structures or objects, since for such small deformations the elastic part of the metal, which is usually elasto-plastic deformation behavior, can be particularly high. The heated rollers reduce the elastic response of the metal.

One embodiment is: the temperature applied to or by the roller may be up to 1000 ℃.

One embodiment is: roll-to-roll forming is performed using at least one roll having a casing with a submillimeter-scale pattern. Such a sleeve can slide onto the rollers and provide a rolling/deforming structure. This has the following advantages: different embossing patterns can be used with a set of rollers, which simplifies the operation. The case may also be referred to as a slip-on cover.

One embodiment is: the metal sheet is directly mechanically formed, in particular stamped, and then divided. This simplifies manufacturing, especially if a plurality of individual pieces are to be manufactured. For example, a roll of sheet metal may be fed through a roll-to-roll stamping apparatus and then separated into multiple pieces, such as by stamping, cutting (e.g., laser cutting), and the like.

The metal of the metal part may be steel, aluminum, copper, etc. or alloys thereof. In particular, the metal may be aluminium alloy 8011 according to DIN 573. The metal part may have an oxide layer or an oxidized layer.

One embodiment is: the metal sheet is divided into fins of a fin-and-tube heat exchanger. Since the fins are sheet-like members, they are suitable for manufacture by roll-to-roll embossing. Moreover, the fins serve as heat exchange surfaces of the heat exchanger, thereby being particularly easily covered by condensate, fluff, hair, and the like. The sub-millimeter structure may help keep the fins clean by being implemented as a non-stick and/or hydrophobic and/or oleophobic structure.

The fins may be made of an aluminium alloy, in particular aluminium alloy 8011.

The thickness of the fins may be in the range of 0.10 to 0.20mm, in particular in the range of 0.12 to 0.15 mm.

Drawings

The above-mentioned features and advantages of the invention and their type of realisation will now be schematically described in more detail in the context of one or more figures, by means of embodiments.

Fig. 1 shows an oblique view of a submillimeter scale imprint apparatus according to a first embodiment during an imprint process;

fig. 2 shows an oblique view of a submillimeter scale imprinting apparatus according to a second embodiment during an imprinting process;

fig. 3 shows a process step of manufacturing a household appliance; and

fig. 4 shows a greatly simplified cross-sectional side view of a household appliance.

Detailed Description

Fig. 1 shows a submillimeter roll-to-roll embossing apparatus 1 comprising a first embossing roll 2, a second embossing roll 3 and two feed rolls 4. As indicated by curved arrows, the metal sheet MS is fed through between the platen rollers 2 and 3 by rotating the platen rollers 2 and 3 and the feeding roller 4. The metal sheet MS may be a roll made of an aluminium alloy with a thickness between 0.12mm and 0.15 mm. At least one of the embossing rollers 2 and 3 can be pressed onto the metal sheet MS, applying a pressure of, for example, up to 5000 MPa. In order to promote plastic deformation of the surfaces 17, 18 of the metal sheet MS, at least one of the embossing rollers 2 and 3 may be heated, for example to a temperature of up to 1000 ℃.

Of the embossing rollers 2 and 3, only the embossing roller 2 has an embossing pattern 5. The metal sheet MS is thus printed with a submillimetric surface structure 6 on only one surface 17. In order to emboss the other surface 18, the metal sheet MS has to be fed twice through the embossing rollers 2, 3.

The imprint pattern 5 may be a pattern designed to produce a submillimeter-scale surface structure 6, which submillimeter-scale surface structure 6 has submillimeter-scale recesses 7 arranged in a repeating pattern, in particular in the form of a matrix. For example, the submillimeter-sized protrusions 8 of the embossing pattern 5 may be arranged in a plurality of similar parallel rows on the embossing roller 2, with the same distance between adjacent rows.

During embossing, the metal sheet MS has no intermediate coating, but is directly mechanically embossed by direct contact of the protrusions 8 with the surface 17 of the metal sheet MS. The surface of the rolls 2, 3 may be hardened, for example by having a hard coating or the like.

In a first variant, the protrusions 8 are on the order of micrometers and may have a length, width and depth respectively greater than 1 micron but less than 50 microns. The pitch of adjacent parallel rows of protrusions 8 is between 1 micron and 50 microns. Further, the pitch of adjacent protrusions 8 in a row is between 1 and 50 microns. Accordingly, the length, width and depth of the recesses 7 created by the protrusions 8 are greater than 1 micron but less than 50 microns. The pitch of the vertical and horizontal rows of the matrix is also between 1 micron and 50 microns.

In a second variant, the projections 8 are on the nanometre scale and may have a length, width and depth respectively greater than 1 nm but less than 50 nm. The pitch of adjacent parallel rows of protrusions 8 is between 1 and 50 nanometers. Furthermore, the pitch of adjacent protrusions 8 in a row is between 1 and 50 nanometers. Accordingly, the length, width and depth of the recesses 7 created by the protrusions 8 are greater than 1 nanometer but less than 50 nanometers. The vertical and horizontal rows of the matrix are also spaced between 1 and 50 nanometers apart.

In yet another variation, the imprint pattern 5 may include a mixture of micro-scale objects and nano-scale protrusions. For example, the imprint pattern 5 may comprise protrusions 8, for example according to a first variant. The surface of these protrusions 8 is patterned in nanometric dimensions, for example according to a second variant. This results in a nanoscale structure within the microscale structure.

Fig. 2 shows an oblique view of the submillimeter-scale imprint apparatus 9 during the imprint process. The embossing device 9 differs from the embossing device 1 in that the first embossing roller 10 has a removable jacket 11 with a submillimeter pattern. The jacket 11 comprises an embossed pattern 5. This has the following advantages: the embossed pattern 5 can be changed simply by replacing the sleeve 11.

Fig. 3 shows the process steps for manufacturing a household appliance in the form of a laundry dryer 12 as shown in fig. 4.

In a first step S1, the metal sheet MS is fed through the submillimeter-scale embossing device 1 or 9. By this, at least one of the surfaces 17, 18 of the metal sheet MS is provided with the sub-millimeter surface structure 6 by directly mechanically embossing the surfaces 17, 18 of the metal sheet MS.

In a second step S2, the metal sheet MS is divided, for example by stamping, cutting (e.g. laser cutting), etc., to produce individual workpieces.

In the third step S3, the fin-and-tube heat exchanger 13 is assembled using the plurality of stamped workpieces of step S2 as fins 14. The heat exchange surfaces of the heat exchanger 13 comprise the surfaces 17, 18 of the fins 14 with the submillimeter-sized surface structure 6.

In a fourth step S4, the domestic appliance in the form of the laundry dryer 12 is assembled using the finned tube heat exchanger 13 of step S3. The heat exchanger 13 may be an evaporator of a heat pump of the laundry dryer 12. The other heat exchanger 15 is a condenser of a heat pump. The heat exchanger 15 may also be a finned tube heat exchanger. The fins 16 thereof may or may not include sub-millimeter surface structures.

Steps S2 to S4 may also be regarded as steps for manufacturing the home appliance.

Of course, the invention is not limited to the described embodiments.

For example, both embossing rollers 2 and 3 may have an embossing pattern. The embossing patterns may be the same or may be different. This embodiment has the following advantages: the metal sheet MS can be structured on both sides in one step.

List of reference numerals

1 submillimeter-scale roll-to-roll imprinting equipment

2 first impression roller

3 second impression roller

4 supply roll

5 embossing pattern

6 submillimeter-level surface structure

7 concave part

8 protrusion

9 submillimeter-level roll-to-roll imprinting equipment

10 first impression roll

11 case

12 clothes dryer

13-finned tube type heat exchanger

14 fins

15 finned tube type heat exchanger

16 fin

17 surface of the metal sheet

18 surface of metal sheet

MS metal sheet

S1 first processing step

S2 second processing step

S3 third processing step

S4 fourth processing step

Claims (9)

1. A laundry drying appliance (12) comprising at least one finned tube heat exchanger (13, 15) having at least one fin (14, 16) of metal, said at least one fin (14, 16) having a treated surface (17, 18) comprising directly mechanically formed sub-millimeter structures (6), said sub-millimeter structures (6) comprising nano-scale structures within micro-scale structures, wherein the sub-millimeter structures (6) comprising nano-scale structures within micro-scale structures are roll-to-roll embossed structures embossed by using heated rollers (2, 3), wherein the heat exchange surface with the sub-millimeter structures comprising nano-scale structures within micro-scale structures reduces the adhesion of fluff and hairs and achieves a higher heat exchange efficiency.

2. Laundry drying appliance (12) according to claim 1, wherein the treated surface (17, 18) comprises at least one micro-scale object in the form of a recess, the bottom of which comprises one or more formed nano-scale objects.

3. Laundry drying appliance (12) according to claim 1 or 2, wherein the treated surface (17, 18) comprises at least one micro-scale object in the form of a protrusion, the top of which comprises one or more formed nano-scale objects.

4. A method for treating a surface (17, 18) of a metal fin (14, 16) of a finned tube heat exchanger (13, 15) of a laundry drying appliance (12), wherein the surface (17, 18) is treated by direct roll-to-roll embossing of submillimeter-scale structures (6) comprising nano-scale structures within micro-scale structures on the surface (17, 18) of the metal using heated rollers (2, 3), wherein the heat exchange surface with submillimeter-scale structures comprising nano-scale structures within micro-scale structures reduces the attachment of fluff and hair and achieves a higher heat exchange effectiveness.

5. Method according to claim 4, wherein the roll-to-roll embossing is performed using at least one roll (2, 3) having a casing (11) with a submillimeter pattern.

6. The method according to any one of claims 4-5, wherein the surface (17, 18) is at least one surface (17, 18) of a Metal Sheet (MS) which is directly mechanically embossed and then divided (S2).

7. A method according to claim 6, wherein the metal is an aluminium alloy and the Metal Sheet (MS) is divided into fins (14, 16) of a finned-tube heat exchanger (13, 15).

8. A method according to claim 5, wherein the temperature applied to the roller (2, 3) or by the roller (2, 3) is up to 1000 ℃.

9. A method according to claim 5, wherein the rolls (2, 3) have an additional hard coating.

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