EP3129171B1 - Method for manufacturing a spinner bottom for a spinner of a household appliance, spinner, and household appliance - Google Patents

Description

The invention relates to a method for producing a component of a laundry drum of a household appliance from a sheet metal element which is formed into a hollow cylinder-like body, is connected to two opposite sides of the sheet metal element and is deformed, according to the preamble of claim 1. The invention also relates to a drum base produced by this method, a laundry drum with such a drum base and a household appliance with such a laundry drum.

Household appliances for the care of laundry items, such as washing machines, clothes dryers and washing (full) dryer, each containing a rotatably mounted in the household appliance laundry drum, in which the laundry items can be added. An exemplary construction of a laundry drum is in Fig. 1 illustrated. The laundry drum generally designated 1 usually consists of three interconnected components, namely a circular cylindrical drum shell 2, a drum rear wall 3 and a so-called drum top 4. The drum shell 2 is connected with its axial end faces on the one hand to the drum bottom 4 and on the other hand to the drum rear wall 3 , The connection is usually realized by means of a crimping of the respective elements. How out Fig. 1 Furthermore, it can be seen, the drum end 4 often serves as a running surface for bearing rollers 5, which are rotatably mounted on a bearing plate 6. In Fig. 1 Furthermore, a front wall 7 of a housing is shown.

Fig. 2 shows a section of the laundry drum 1 in a perspective view. Here, the respective connection points 8, 9 can be seen, which are realized by a curling of the drum shell 2 with the drum bottom 4 on the one hand and the drum rear wall 3 on the other. Depending on the device-specific requirements, the laundry drum 1 is usually designed both in terms of load and cost-efficient, which is achieved by a sheet thickness variation in the different components 2, 3, 4. While the forehead bottom 4 for reasons of stability is made of a sheet metal element of thickness 0.6 mm, the drum shell 2 and the drum rear wall 3 can be formed from a sheet of lesser thickness, namely, for example, 0.4 mm or 0.5 mm.

In the present case, the interest is directed to the production of the drum end base 4, wherein the production is also applicable to a drum rear wall 3. The drum end floor and the drum rear wall can also be referred to hereinafter only as drum base.

In the prior art, the drum bottom 4 and / or the drum rear wall 3 is produced in tumble dryers, washing machines and dryers by a three-stage forming process with subsequent crimping of the edge. As starting geometry for this manufacturing process circular blanks are used. Such a circular sheet metal element 10, from which the drum top 4 is made, is in Fig. 3 shown schematically. This circular sheet metal element 10 is according to Fig. 4 subjected to a first deep-drawing process. In a further step of the production process, the deep-drawn sheet metal element 10 is subjected to a separation process in which a circular central region of the sheet metal element 10 is punched out. This creates a passage opening through which the items of laundry can be introduced into the drum 1. The sheet metal element 10 after this separation process is in Fig. 5 shown schematically. Finally, a second deep drawing of the sheet metal element 10 takes place, so that a drum end floor 4 is provided, as it is in Fig. 6 is shown.

During the manufacturing process so only the outer ring of the discs used for the drum head is still used. The majority of the round plate - namely about 60% - is punched out and is then considered as a blend. In the production of tumble dryers, another component, the so-called clamping ring, is produced from this blend. However, the proportion of waste in this cheaper case is about 47%.

A major disadvantage of the existing process chain is also the production-related introduction of the highest degrees of deformation and residual stresses in the area of the flange 8, 9 (see. Fig. 2 ). On the one hand, relatively high demands are made on robustness the crimping process with regard to the resulting flare geometry, which has a crucial importance for the life of the drum end floor. On the other hand, precisely this region, which is heavily loaded from the production process by the crimp, serves as running surface for the front drum bearings or the rollers 5 (cf. Fig. 1 ) and thus has a supporting function. Due to the high loads from the forming process in the production of the laundry drum, the risk of premature failure in the operation of the household appliance is relatively large, which reduces the life of the entire household appliance.

Furthermore, from the generic DE 100 21 456 A1 a method for producing a drum shell of a laundry drum of a washing machine known. In this method, a hollow cylindrical shell is rounded from a sheet metal blank and welded to its abutting edges. This hollow cylinder is reshaped in a further step by means of an expansion process, for example, to introduce bevels at the two edges of the drum shell. A disadvantage of this method is that the material can not be reshaped so far as to form the same complete drum bottom. In other words, this known method is used only for the production of the drum shell and in a further step, a separate drum base must continue to be manufactured and connected to the drum shell. This is done, for example, as already described above.

It is an object of the invention to provide a comparison with the prior art improved method for producing a component of a laundry drum of a household appliance, a drum base, a laundry drum and a household appliance. In particular, the component should be produced with as little waste. Furthermore, the degrees of deformation and thus the formation of high residual stresses should be reduced.

This object is achieved according to the invention by a method, by a drum base produced by this method, by a laundry drum and by a household appliance with the features according to the respective independent claims 1, 12, 13 and 14. Advantageous embodiments of the invention are the subject of the dependent claims, the description and the figures.

An inventive method is used to produce a component for a laundry drum of a household appliance from a sheet metal element. According to the invention, it is provided that a hollow cylinder of similar body, in particular a hollow cylinder and preferably a hollow circular cylinder, is used as the sheet metal element and the component forms a drum base. The drum bottom can be either a drum top or a drum back wall or both. Essential for the invention is that for the production of the drum base, a hollow cylinder similar body is used, which is formed by the connection of two opposite sides of the sheet metal element. A body similar to a hollow cylinder is understood to mean a body whose sectional surfaces are circular or elliptical with the sectional planes running perpendicular to its central cylinder axis, wherein the shape and size of the cut surfaces along the cylinder axis may be different. The hollow cylinder-like body can therefore not only have a purely circular cylindrical surface but also a frustoconical surface.

Furthermore, the drum base is produced by forming the sheet metal element or the hollow cylinder-like body. It is first produced from a flat sheet metal element by connecting two opposite sides of the hollow cylinder similar body, which is then formed in at least one further step to the drum base. Alternatively, a corresponding deformation, in particular by means of a so-called roll forming, can take place already during the molding of the hollow cylinder-like body, wherein the already formed sheet metal element is then connected in a further step on two opposite sides. It can then be performed after joining another forming step to achieve even higher Umformtrade. If after the bonding no further forming step is to take place, the sheet metal strip is formed before connecting the narrow sides in the shape of the drum base, being prepared by the step of connecting the narrow sides of the preformed sheet metal element ready drum bottom.

Subsequently, the hollow cylinder similar body is also referred to only as a hollow cylinder.

Instead of using a blank as a starting geometry for the production of the drum base, the invention makes use of the way of using a hollow cylinder as the starting geometry for the production process of the drum base. Such a procedure has several advantages. On the one hand, the use of a hollow cylinder ensures that the material waste can be minimized to a minimum, even zero, thereby enabling a cost-efficient production of the drum base. Namely, it does not need to be stamped out areas of the sheet metal element, so that in principle the material provided - especially stainless steel, such as 1.4016 or 1.4510 - can be fully utilized. On the other hand, there is a significant improvement over the prior art in increasing the process robustness. The induced by the proposed manufacturing process loads in the field of flanging are namely significantly lower compared to the prior art, whereby a reduction in the risk of premature failure of the frontal floor can be achieved. As already stated above, the forehead bottom is very often used as a running surface for the rollers (cf. Fig. 1 ), and it should be ensured for this reason that the front floor can withstand greater forces in the operation of the household appliance. In the case of the method according to the invention, this is made possible by the fact that, in the manufacture of the forehead bottom, this overall significantly lower load is applied in the area of the flange than is the case in the prior art. An FE process analysis (finite element method) has shown that the degree of deformation can be minimized, in particular in the area of the crimp with the drum shell. An FLC (Forming Limit Curve) analysis based on the FE results obtained has also shown that the process robustness in the method according to the invention is markedly improved compared to the conventional production method.

The drum base is preferably a drum end floor (see Fig. 4 in Fig. 1 ). Optionally, it is also possible, the drum back wall (3 in Fig. 1 ) using a hollow cylinder, although the drum rear wall has an opening in a central area. This would be the case, for example, if the drum rear wall substantially corresponds to the drum end wall and thus also has a central opening. The central opening of the drum rear wall could be closed by a fixed part of the housing of the household appliance. In such a Drum solution, both the drum top floor and the drum rear wall could each have a running surface for the rollers for rotatably supporting the drum.

In one embodiment it is provided that the production of the drum base also includes the production of the hollow cylinder itself. The hollow cylinder is made from a sheet metal strip. For example, a sheet metal strip whose width is 100 mm and whose length is 1575 mm can be used. The thickness of the sheet used can be 0.6 mm.

If necessary, the material waste can be further reduced if the sheet metal strip is separated directly from a sheet metal coil by means of a production-related separation process. The preparation of the hollow cylinder can therefore be made without waste directly from the coil.

The production of the hollow cylinder preferably provides that the sheet metal strip is rolled round and / or bent. The hollow cylinder can thus be produced by round rollers and / or by bending the metal strip. The production of the hollow cylinder can thus be made without much effort and automated.

Preferably, in the manufacture of the hollow cylinder or the hollow cylinder similar body, two opposite narrow sides of the metal strip are connected in particular by welding material fit together. To select a suitable welding method, a technology analysis was carried out in this respect, in which the basic applicability of plasma welding, in particular micro-plasma welding, and laser welding was demonstrated both on the previously used material and on alternative materials. The two narrow sides of the metal strip can thus be connected to one another in an advantageous manner by means of a laser welding device and / or a plasma welding device. On the one hand, the production can thus be automated; On the other hand, this also the required stability and robustness of the hollow cylinder is achieved.

The hollow cylinder thus produced can then already form the bottom of the drum or be formed into the bottom of the drum:

The reshaping of the hollow cylinder may initially involve that, in order to produce a funnel shape of the sheet metal element, an axial cylinder section of the hollow cylinder is widened radially outward. In this way, the required funnel shape of the drum base can be produced without much manufacturing effort.

Alternatively, the funnel shape of the sheet metal element may be produced by already deforming the sheet metal strip into the funnel shape during rolling or bending, and subsequently joining the thus formed sheet metal strip to two opposing sides. These sides to be joined are preferably bevelled beforehand to avoid uneven material overhang. The particular advantage of this alternative is that only very small deformations of the sheet metal strip are required for the production of the funnel shape, whereby the process robustness for the production of the drum base can be significantly increased.

A funnel shape has proved advantageous when an angle of 45 ° to 55 °, in particular an angle of 50 °, is generated between a lateral surface of this cylinder section on the one hand and the cylinder axis on the other hand, in particular by widening of the cylinder section. This angular range represents a good compromise between the required shape of the sheet metal element on the one hand and the deformation degrees caused in the process on the other hand. It has been found that at an angle in the range of 45 ° to 55 ° no critical degrees of deformation are caused and the required process robustness not being affected.

It is preferable if the expansion of the cylinder portion is performed in at least two stages. In this way, the material is much less burdened compared to a single-stage expansion, which proves to be particularly particularly in terms of the life of the laundry drum to be particularly advantageous. On the other hand, a larger angle when expanding the cylinder portion can thus be achieved overall.

Preferably, in a first stage flaring operation, the cylinder portion is expanded by a larger angle than a second stage flaring operation. This embodiment makes use of the fact that the load of the material increases at a larger angle and thus in the first stage Overall, a larger angle can be achieved without significantly affecting the stability of the material.

In the first stage, for example, an angle of 35 ° to 45 °, in particular an angle of 40 °, generated.

In contrast, in the second stage, an angle change of 5 ° to 15 °, in particular an angle change of 10 °, are generated,

If the funnel shape of the sheet metal element is already produced during bending or rolling of the sheet metal strip, the first and optionally second expansion step can be omitted.

The forming of the sheet metal element may further include deep drawing of the sheet metal element. This deep-drawing process is preferably carried out after production of the funnel shape of the sheet metal element, in particular after the widening of the cylinder section, so that the deep drawing is subjected to the already expanded or funnel-shaped sheet metal element. By deep drawing the required final shape of the drum base can be created. Thus, this method differs from that DE 100 21 456 A1 known method also characterized in that no expansion process is required for the production of the drum base. The special distribution is that during deep drawing compared to the expansion process higher cycle times for the production of the drum base can be achieved.

The invention may also include a method which is used for producing a laundry drum for a domestic appliance, wherein the laundry drum is produced from a drum base produced by a method according to the invention, which is connected to a cylindrical drum shell, in particular by means of crimping is connected.

The invention also relates to a drum base produced by the method according to the invention and a laundry drum for a domestic appliance for the care of laundry items, with a cylindrical drum shell which is connected at at least one of its axial end faces with such drum base. The laundry drum can also at both its axial (front) sides after Having drum base produced by the process according to the invention. This is particularly advantageous if the drum rear wall corresponds in shape to the end wall. Thus, the rear wall of the drum also has an opening corresponding to the passage opening of the end wall, which may be closed by a fixed housing part of the household appliance.

An inventive household appliance for the care of laundry comprises a laundry drum according to the invention. The household appliance may be a tumble dryer, a washing machine or a washer-dryer.

Further features emerge from the claims, the figures and the description of the figures. All the features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively indicated combination but also in other combinations or alone. In particular, the laundry drum and the domestic appliance according to the invention may comprise the device features disclosed by the method according to the invention or directly derived therefrom.

Fig. 1

in schematischer und perspektivischer Darstellung ein Trommelsystem eines Haushaltgeräts;

Fig. 2

in schematischer und perspektivischer Schnittdarstellung ein Ausschnitt einer Wäschetrommel mit einem Trommelboden;

Fig. 3 bis 6

schematische Darstellungen zur Erläuterung eines Herstellungsverfahrens gemäß dem Stand der Technik;

Fig. 7 bis 9

schematische Darstellungen zur Erläuterung eines Herstellungsverfahrens gemäß einer Ausführungsform der Erfindung;

Fig. 10

ein Flussdiagramm des Verfahrens gemäß einer Ausführungsform der Erfindung;

Fig. 11

schematische Darstellung eines Herstellungsverfahrens gemäß einer alternativen Ausführungsform der Erfindung; und

Fig. 12

ein FLC-Diagramm.

The invention will now be explained in more detail with reference to a preferred embodiment and with reference to the drawings. Show it:

Fig. 1

a schematic and perspective view of a drum system of a household appliance;

Fig. 2

in a schematic and perspective sectional view of a section of a laundry drum with a drum base;

Fig. 3 to 6

schematic representations for explaining a manufacturing method according to the prior art;

Fig. 7 to 9

schematic representations for explaining a manufacturing method according to an embodiment of the invention;

Fig. 10

a flowchart of the method according to an embodiment of the invention;

Fig. 11

schematic representation of a manufacturing method according to an alternative embodiment of the invention; and

Fig. 12

an FLC diagram.

Fig. 10 shows a flowchart of a manufacturing method according to a first embodiment of the invention. In this process, a drum top 4 is made as in Fig. 1 is shown. The method begins in a first step S1, in which a metal strip is separated from a sheet metal coil or a strip material, for example by means of laser cutting or the like. The provided metal strip may have, for example dimensions of 100 x 1575 mm. As a band material, the material 1.4016 or 1.4510 can be used, in general terms, stainless steel is used. The sheet thickness can be 0.6 mm. The metal strip is preferably a rectangular element.

In a further step S2, the metal strip now designated 11 is rolled round, so that the shape of a straight hollow circular cylinder is produced. In a subsequent step S3, the hollow cylinder is produced by opposite narrow sides 12, 13 of the sheet metal strip 11 are welded together. In the exemplary embodiment, a laser welding device or a plasma welding machine is used.

The hollow cylinder produced in step S3 is then formed into the drum top 4 in a subsequent step S4. This reshaping involves three steps. According to Fig. 7 is an axial cylinder portion 14 of the in Fig. 7 Flared with 15 designated hollow cylinder radially outwardly widened. The hollow cylinder 15 represents a sheet metal element 16, which is the basis of the production of the drum end base 4.

With further reference to Fig. 7 In the expansion process of the first stage, an angle of 40 ° is generated between a lateral surface 17 of the cylinder section 14, on the one hand, and the cylinder axis 18, on the other hand. In a further stage, a second widening process of the same cylinder section 14 then takes place Fig. 8 carried out in which an angle change of 10 ° and thus an angle of 50 ° between the lateral surface 17 and the cylinder axis 18 is generated.

In a final step of forming, the sheet metal element 16, as shown in FIG Fig. 8 shown subjected to a deep drawing process. By deep drawing, the final shape of the drum end floor 4 is generated, as in Fig. 9 is shown. By deep drawing can optionally a tread for the bearing rollers 5 (see. Fig. 1 ) be created.

The FIG. 11 shows a second embodiment of the invention. First, the above-described step S1 of the first embodiment is executed. In the subsequent step corresponding to step S2, the metal strip 11 is guided in the feed direction 26 or 26 'between two shaping rollers. In this case, the metal strip 11 is rolled round as in step S2 and additionally at the same time formed into a funnel shape, so that an at least partially conical hollow cylinder is produced. The two forming rollers 22 and 25 form a first forming stage and rotate in opposite directions about the axes of rotation 22.1 and 25.1. The with directions of rotation of the forming rollers 22 and 25 are shown by the arrows 22.2 and 25.2.

In the FIG. 11 illustrated embodiment has a second and possibly further forming stages, not shown. The second forming stage again consists of two counter-rotating forming rollers 23, 24, which further reshape the metal strip 11 located between the forming rollers. In the FIG. 11 are also the axes of rotation 23.1, 24.1 and the direction of rotation 23.2, 24.2 of the forming rollers 23, 24 shown. Preferably, the first, second and further forming stage are arranged on a circular path. In this way, the hollow cylinder similar body 15 can be particularly easily formed, which already has a funnel shape or even a shape corresponding to the drum bottom cross-section has.

This is followed by the step S3, in which the already formed sheet metal strip 11 is connected to each other with its narrow sides. Depending on the number of selected Umformstufen and degrees of deformation, the sheet metal element 16 produced in step S3 may already form the drum end 4 or it is analogous to the first embodiment, the step S4 carried out to produce by further forming the final shape of the drum top 4.

By such a manufacturing method, the material waste can be minimized, and a cost-efficient production of the drum end floor 4 can be made possible. Another advantage is the increase in process robustness and the reduction in the stress induced by the manufacturing process in the region of the flange 8 (cf. Fig. 2 ), whereby a reduction in the risk of premature failure of the drum end floor 4 can be achieved. FE process analysis was performed on this manufacturing process, and the results showed that the degrees of deformation in the area of the flange 8 of the drum end floor 4 are minimized. The degree of deformation is represented by the change in shape φ, which is defined as the integral of h ₀ to h ₁ over (dh / h ₀ ), where h is a length in a defined direction, h _{0 is} a length of the component before forming, h _{1 is} the Length after deformation and that is the differential change in length. The result of an FLC analysis based on the FE analysis is in Fig. 12 for two orthogonal directions φ ₁ and φ ₂ , showing the shape change φ of a pattern at a selected area in comparison of two forming processes. 19 designates the determined change in shape φ of the FLC analysis for the method according to the invention and 20 for the method according to the prior art. A failure limit is designated 21. How out Fig. 12 As can be seen, the distance to the failure limit in the inventive method is significantly greater than in the conventional manufacturing process. This shows that the process robustness in the proposed method is significantly better than in the conventional process chain.

LIST OF REFERENCE NUMBERS

1

washing drum

2

drum shell

3

Drum rear wall

4

Barrel front floor

5

bearing rollers

6

end shield

7

front wall

8, 9

Connecting points in the form of flanging

10

sheet metal element

11

metal strip

12, 13

narrow sides

14

cylinder section

15

hollow cylinder

16

sheet metal element

17

lateral surface

18

cylinder axis

19

Shape change of a pattern according to the inventive method

20

Shape change of a pattern according to a method known from the prior art

21

failure limit

22, 23, 24, 25

forming roller

22.1, 23.1, 24.1, 25.1

Rotary axis of the respective form roller

22.2, 23.2, 24.2, 25.2

Direction of rotation of the respective form roller

26, 26 '

Feed direction of the metal strip

S1, S1, S3, S4

steps

φ

strain

H

Length of a pattern

ie

differential length change

Claims (14)

1. Method for manufacturing a component of a laundry drum (1) of a household appliance from a sheet metal element (16), which is shaped to form a body (15) similar to a hollow cylinder, in particular to form a hollow cylinder, is joined on two opposing sides (12, 13) of the sheet metal element (16) and is shaped, wherein the body (15) is manufactured from a sheet metal strip (11) and two opposing shorter edges (12, 13) of the sheet metal strip (11) are joined to one another in order to form the body (15) similar to the hollow cylinder, characterised in that the component is a drum base (4) of the laundry drum (1), wherein the drum base (4) is manufactured by shaping the body (15) and the step of joining the shorter edges (12, 13) is performed prior to a step of shaping the body (15) similar to a hollow cylinder in order to manufacture the drum base (4) or after a step of shaping the sheet metal strip (11) in the form of the drum base (4).
2. Method according to claim 1, characterised in that the sheet metal strip (11) is separated from a sheet metal coil by means of a separation method.
3. Method according to one of claims 1 or 2, characterised in that the body (15) is manufactured by rounding and/or by bending and/or by roll forming the sheet metal strip (11).
4. Method according to one of claims 1 to 3, characterised in that when the body (15) is manufactured, the two opposing shorter edges (12, 13) of the sheet metal strip (11) are joined to one another with an adhesive bond by welding, in particular by means of a laser welding device and/or a plasma welding device.
5. Method according to one of the preceding claims, characterised in that the body (15) or the sheet metal element (16) forms a funnel shape.
6. Method according to claim 5, characterised in that the shaping of the body (15) comprises a step in which an axial cylinder section (14) of the body (15) is expanded radially outwards in order to generate the funnel shape of the sheet metal element (16).
7. Method according to claim 5 or 6, characterised in that an angle of 45° to 55°, in particular an angle of 50°, is generated between a lateral area (17) of this cylinder section (14) on the one hand and the cylinder axis (18) on the other hand.
8. Method according to claim 6 or 7, characterised in that the cylinder section (14) is expanded in at least two stages.
9. Method according to claim 8, characterised in that with an expansion process of a first stage, the cylinder section (14) is expanded by a larger angle than with an expansion process of a second stage.
10. Method according to claim 8 or 9, characterised in that in the first stage an angle of 35° to 45°, in particular an angle of 40°, is generated between a lateral area (17) of the cylinder section (14) and the cylinder axis (18).
11. Method according to one of the preceding claims, characterised in that the shaping comprises a deep-drawing of the sheet metal element (16), in particular of the sheet metal element (16) already expanded.
12. Drum base for a laundry drum for a household appliance for the care of laundry items, wherein the drum base is formed from a sheet metal element (16) to form a body (15) which is connected and shaped on two opposing sides (12, 13) of the sheet metal element (16), wherein the body (15) is manufactured from a sheet metal element (11) and two opposing short edges (12, 13) of the sheet metal element (11) are connected to one another in order to form the body (15) similar to the hollow cylinder, wherein the drum base (4) is manufactured in accordance with a method according to one of the preceding claims.
13. Laundry drum (1) for a household appliance for the care of laundry items, having a cylinder-shaped drum shell (2), which, on at least one of its axial front ends, is joined to a drum base (4) according to claim 12.
14. Household appliance for the care of laundry items, having a laundry drum (1) according to claim 13.

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