EP1420103A2 - Dryer, particularly laundry dryer - Google Patents

Abstract

The dryer device has a rotary driven drum (11) with a cylindrical sheet casing (23) and circular running rings (13) supporting the drum on running wheels and driven by at least one running wheel. The running wheels are joined by struts (25) so that the rings and the struts form a stable drum cage (22). The struts are preferably fixed to the rings and./or are profiled in section.

Description

The invention relates to a dryer, in particular a tumble dryer, according to the The preamble of claim 1, 4 and 11, respectively.

Dryers, in particular tumble dryers for commercial use (Laundries, etc.), have a rotating drivable drum. The drum points At opposite ends or opposite end portions on races. With The drum rests on wheels on the races. At least one impeller is drivable, so that hereby the drum frictionally in a rotational movement about its longitudinal central axis is displaceable. The longitudinal center axis of the drum forms at the same time their Axis of rotation.

In the known dryers, especially dryers, the Running rings formed from a metal strand formed into a circle. Such races have only a moderate running accuracy. Seal the drum to a These surrounding, fixed housing must therefore be quite expensive than so-called slip ring seals are formed. These slip ring seals wear out over time, making it difficult to turn the drum.

Another disadvantage of known dryers is that one for the formation of the drum Serving cylindrical jacket plate is bolted to the races. That makes it difficult not only the production of known drums; above all, a repair becomes more expensive, if the shroud or parts of the same must be replaced. In addition let the glands of the jacket plate with the races unavoidable Length changes of the jacket plate or its parts during heating and cooling of the Dryer only limited. The result is thermally induced deformations, in particular bulges, of the jacket sheet.

On this basis, the invention has the object, a dryer, In particular, tumble dryer, to create a simple and light has mountable and removable drum. At the same time, the dryer should be low-wear.

A dryer for solving this problem has the features of claim 1. The inventive compound of the races by struts leads to a stable Drum cage, which allows a precise concentricity of the drum. The drum cage forms a static-carrying part of the drum, which is a reliable and accurate Storage of the jacket plate of the drum allows, whereby the jacket sheet itself no or does not have to have any significant bearing properties. This can in particular, formed from a plurality of jacket plate parts jacket plate with the Drum cage can be easily connected without having to connect the sheath sheet metal parts is required with each other.

The preferably welded to the races struts are according to a preferred Design of the device provided with a profiled cross-section. Preferably, the struts are box-shaped or hollow profile-like, where it is sufficient the hollow profile is not completely closed, but for example open on one side train. This design of the struts contributes in particular in connection with the Welding the same with the races to form a stable, in itself carrying drum cage.

Another dryer to solve the aforementioned problem, in which it also may be a development of the dryer described above, the Features of claim 4. Accordingly, the shrouds are of several individual Sheath sheet parts formed, which are connected by clamping with the drum cage. The thus out of the drum cage and several directly not in connection Standing drum formed sheet metal parts drum can be easily assembled. Just as simple, if necessary, individual sheath sheet metal parts can be replaced. It are no longer as with known dryers many screws for connecting the Sheath plate or the jacket sheet metal parts with the races required. By the clamping connection of at least some edge regions of the shell sheet metal parts with the Drum cage can be the number of screws to connect the shroud to the Drum cage can be significantly reduced. The at least partially clamping connection the cladding panel parts with the drum cage allows relative movements of the cladding panel parts to the drum cage, for example, by a temperature-induced expansion the shell sheet metal parts this or their corresponding edges due to by the Clamping frictional and / or non-positive connection takes place relative to Drum cage, in particular the struts of the same, can move.

According to a preferred embodiment of the device, only the transverse edges or adjoining edge regions of the shell sheet metal parts on the struts continuous clamped, preferably by terminal strips. The attachment of the Cross edges of the shroud parts is to pay special attention to it is sufficient, only the transverse edges of the shell sheet metal parts clamped to the bars of To attach drum cage. The longitudinal edges of the Mantelblechteile can in conventional Be screwed to the races, where it is sufficient, only relatively few screws to use.

The clamping bars are preferably simultaneously as projecting ribs in the interior of the Drum formed. As a result, the terminal strips have a double function, that is, There are no additional components required for the terminal strips.

The clamping of the transverse edge regions of the shell sheet metal parts takes place on the drum cage preferably between the terminal strips and the struts. This is shown by the struts according to a preferred embodiment of the invention in the plane of the transverse edge regions the shell panel parts lying protruding clamping legs. By Counter screws of the terminal strips against the struts are the terminal strips or Andruckschenkel the same, pressed in the direction of the clamping legs of the struts. In this case, transverse edge regions of the cladding sheet metal parts between the Andruckschenkeln the clamping bars and clamping legs of the struts clamped. In this way comes with an easy to manufacture, but reliable and durable friction and frictional connection of the transverse edges or transverse edge regions of the Mantelblechteile with the drum shell concluded. In particular, the Querkantenbereiche the shroud parts between the clamping legs and the Move Andruckschenkeln thereby changing the length of the shell panel parts when warming up and cooling down the drum. Any constraints of Mantelblechteile, in particular bulges thereof, are practical locked out.

Another dryer to solve the aforementioned problem, which is also may be a preferred embodiment of the dryer described above, has the features of claim 11. Accordingly, at least one frontal Opening the drum relative to the fixed housing by at least one sealed non-contact seal. This non-contact seal is as good as not subject to wear and does not brake the drum against the direction of rotation. As a result, the force to drive the drum over known dryer with friction grinding ring seals reduced.

The non-contact sealing of the drum with respect to the housing takes place in the area each race on an opening having an end face of the drum. In particular For drums with a stable drum cage has the respective race over a high running accuracy, whereby with small gap widths a reliable and always non-contact seal can be realized.

To increase the running accuracy of the races even more, the outer peripheral surface and the outer end face of at least that race which is used to form a non-contact seals used, edited. The preferably machining (Turning, grinding or the like) takes place after the races through the struts are connected by welding in particular. Then at the same time at the Machining eliminates any distortion of the races due to welding. In particular, with the invention statically supporting, stable training of Drum cage and the machining of the races can be a very high Accuracy of even large drums achieve the non - contact seals for Housing also allows for relatively small gap widths.

The non-contact sealing of the drum with respect to the stationary housing takes place in the region of the respective opening on one or both opposite End faces of the drum through annular end-side areas of the races opposite to a closely spaced adjacent end wall of the housing. In this case, the existing sealing gap can be reduced by at least one gap-reducing ring-like coating, in particular sealing coating. This one is designed that he does not the respective end face of the race during the rotation of the drum touched, and leaves only a sealing gap to the relevant end face of the race, the is relatively narrow.

Fig. 1

eine schematische, perspektivische Ansicht eines Wäschetrockners,

Fig. 2

eine perspektivische Ansicht einer Trommel des Wäschetrockners,

Fig. 3

eine stirnseitige Ansicht der Trommel der Fig. 2,

Fig. 4

einen mittigen Querschnitt durch die Trommel der Fig. 2 und 3 im Bereich zweier gegenüberliegender Rippen,

Fig. 5

einen vergrößerten Teilquerschnitt durch den Wäschetrockner im Bereich einer Dichtung zwischen der Trommel und einem Gehäuse, und

Fig. 6

einen vergrößert dargestellten Querschnitt durch die Trommel im Bereich einer Rippe.

A preferred embodiment of the device according to the invention will be explained in more detail with reference to the drawing. In this show:

Fig. 1

a schematic, perspective view of a clothes dryer,

Fig. 2

a perspective view of a drum of the clothes dryer,

Fig. 3

an end view of the drum of Fig. 2,

Fig. 4

a central cross-section through the drum of Fig. 2 and 3 in the region of two opposite ribs,

Fig. 5

an enlarged partial cross section through the dryer in the region of a seal between the drum and a housing, and

Fig. 6

an enlarged cross section through the drum in the region of a rib.

The dryer shown here is a tumble dryer, one Continuous tumble dryer, especially for commercial purposes such as Laundries.

The tumble dryer has a stationary, preferably cuboidal Housing 10, in which a rotatably driven, cylindrical drum 11 is located. The Drum 11 is rotationally driven about a longitudinal central axis 12. This forms the Longitudinal axis 12 of the drum 11 at the same time the axis of rotation thereof. The drum 11 has cylindrical in the areas of their opposite end faces Race rings 13 on. With the races 13, the drum 11 rests on wheels 14. Im shown embodiment, four wheels 14 are provided, each race 13 two wheels 14 are assigned (Fig. 1). Two wheels 14, one impeller 14 per race 13, are shown by a common drive, in the Embodiment an electric motor 15, rotationally driven. The two driven wheels 14 act as friction wheels for Reibradantrieb the drum 11 on the outer circumference of the races 13. The wheels 14 and the drive, in particular the electric motor 15 are mounted inside the housing 10 under the drum 11, and on a frame, not shown, of the tumble dryer.

The cylindrical drum 11 has a cylindrical drum wall and two opposite, circular end faces on. In the continuous tumble dryer shown here is in each end face of the drum 11 is a circular opening, and Although a loading opening 16 and a discharge opening 17 are provided. Both the Beladeöfffnung 16 and the discharge opening 17 are of one at the respective Surround side of the drum 11 arranged annulus 18. The housing 10 has in each of the opposite end walls 19 via a with the Loading opening 16 and the discharge opening 17 in the drum 11 corresponding, circular housing opening 20 and 21. Each housing opening 20 and 21 is through each a lid 44 closed. This is during the drying process the Housing 10 to the outside liquid and temperature-tight lockable.

In accordance with the invention special way, the drum 11 is formed. The drum 11 is composed of a drum cage 22 and a cylindrical jacket plate 23, wherein the jacket plate 23 is formed of several parts, namely of several Cover plate parts 24 composed. In the exemplary embodiment shown (FIGS. 2 and 3) four equally large shell sheet metal parts 24 are provided, each with about a Quarter of the circumference of the jacket plate 23 extend.

The drum cage 22 is formed stable according to the invention. This training is like that taken that the drum cage 22 forms a statically self-supporting unit. Of the Drum cage 22 thereby holds the shroud parts 24 together, without that the shell sheet metal parts 24 are interconnected. The drum cage 22 settles together of two races 13 and serving to connect the same struts 25th In the illustrated embodiment, the races 13 are equal by four trained struts 25 connected, which is uniform on the circumference of the cylindrical Drum 11 are distributed, so have about quarter circle distances from each other. The opposite end faces of the drum 11 associated races 13 are the same formed, preferably have the same dimensions. The struts 25 are with the Race rings 13 welded. This gives the drum cage 22 according to the invention provided inherently stable and self-supporting property.

The races 13 have in the drum 11 shown here an L-shaped angle profile on. A longer leg 26 of this angle profile is circular. The outside of the long leg 26 forms a cylindrical tread 27 of the race 13, which the races 13 rest on the wheels 14. One in the level of each Front lying short leg 28 of each race 13 extends in the direction of Longitudinal central axis 12. In this case, the circumferential short leg 28 forms the Loading opening 16 and the discharge opening 17 surrounding annular wall 18 at the respective end face of the drum 11. An outwardly facing side of the through circulating. short leg 28 of the respective race 13 formed Kreisringwandung 18 of the drum 11 forms a circular sealing surface 29. The races 13th are preferably processed after the completion of the drum cage 22. Preferably are the running surfaces 27 and the sealing surfaces 29 of the races 13 machined machined by milling, turning, grinding or the like. These edits preferably occur during a continuous rotation of the finished drum cage 22. As a result, the running surfaces 27 extend exactly concentric to the longitudinal central axis 12 and thus also to the axis of rotation of the drum 11. Also run through the processing of the Sealing surfaces 29 exactly perpendicular to the longitudinal central axis 12, whereby the races 13 of the Drum 11 give a very precise concentricity.

The struts 25 are formed as elongated profiles. These may be hollow sections or box profiles. In the exemplary embodiment shown (FIG. 6), the cross section is each strut 25 is formed approximately Ω-like. Accordingly, each has the same trained struts 25 over a central U-shaped area, the U to the Outside the drum 11 is open. At free outer ends of the parallel Legs of the U-shaped central region close outwardly projecting Clamping leg 30 at. The two clamping legs 30 extend in opposite directions Outward directions, so are directed away from each other. The clamping legs 30 are to the outer diameter of the jacket plate 23 of the drum eleventh adapted by the facing the interior of the drum 11 surfaces of the clamping legs 30 are approximately on the outer diameter of the jacket plate 23.

With opposite, slightly tapered end portions are the struts 25 with the respective race 13 preferably connected by welding (Figure 5). This Connection takes place in the region of the horizontal, long leg 26 of each race 13, namely at the inside of the drum 11 facing inside the long leg 26. In the embodiment shown, the clamping legs 30 are in that area, in which the end portions of the struts 25 overlap the long legs 26 are removed (Fig. 5), so that the struts 25 with their radial legs 47 with the legs 26 of the Race rings 13 are welded. Due to the welding of the struts 25 with the Running rings 13 and the profiled formation of the cross section of the struts 25 form the Strive 25 with the races 13 the inherently stable, statically supporting drum cage 22. It is also conceivable to form the struts 25 completely as a U-profile, so that the Struts 25 have no clamping legs 30. It is then in between the races 13 are located portion of the U-shaped struts 25 a preferably slightly smaller U-profile arranged with protruding to opposite sides clamping legs. The clamping legs of this US profile take over the function of the clamping legs 30th For this purpose, the clamping legs - as well as the clamping legs 30 - in the circumferential direction of the Drum 11 lying integrally formed on the U-profile. The lengths of the clamping legs are shorter as the smallest (clear) distance between the races 13th

The shell panel parts 24 are dimensioned so that between each other Transverse edges 31 of adjacent shell sheet metal parts 24 a narrow gap arises, through which projects the U-shaped central part of the respective strut 25. Overlap at the transverse edges 31 of adjacent shroud parts 24 adjacent transverse Edge portions of the shroud parts 24 partially, preferably for the most part, the Clamping leg 30 of the respective strut 25 (Fig. 6). On the clamping legs 30 are the from the transverse edges 31 outgoing transverse edge regions in each case two adjacent shell sheet metal parts 24 approximately continuously clamping over its entire length fastened, namely clamped, by a respective terminal block, the same time a rib 32 forms inside the drum 11. Each rib 32 is thus simultaneously one Terminal strip. Each of the identically formed ribs 32 has a hat-like Cross-section. This is formed by a narrow web 33, from both sides obliquely directed legs 34 go out. The legs 34 are opposite obliquely directed and thereby proceeding from the web 33 diverging in the direction to the clamping legs 30 of the respective strut 25. The to the clamping legs 30th pointing ends of the legs 34 are inwardly to the U-shaped central portion of respective strut 25 angled and run parallel to the clamping legs 30th These angled ends of the legs 34 form Andruckschenkel 35, to the the Clamping legs 30 opposite inner sides of the transverse edges of the 31st adjacent shell sheet metal parts 24 outgoing transverse edge regions the same concern (Fig. 6). At the frontal areas of the struts 25 are the End portions of the legs 34 angled outwardly to form Eckwinkeln 46th (Figures 2, 4 and 6).

The ribs 32 are indirectly bolted to the struts 25. These are in the interior of the hat-shaped profiled rib 32 preferably at least in the radial direction of the drum 11th elastic coupling members 36 are provided. The coupling links 36 are on the web 37 of the U-shaped central portion of the respective strut 25 and arranged here with the web 37th connected to the strut 25. At the top of each coupling member 36 carries a nut 38. In the nut 38 is a screw not shown in FIG. 6 through a Through hole 39 in the web 36 of the rib 32 can be screwed. Preferably, per Strut 25 or rib 32 two to four screws and associated coupling links 36 is provided which distributes uniformly over the length of the strut 25 and the rib 32 are (Fig. 4). By appropriate tightening the respective screw is the Koppeglied 36 elastically stretched in the radial direction of the drum 11, so that a Top of the respective coupling member 36 with the nut 38 to rest under the web 33rd the rib 32 passes. The elongated coupling members 36 tend to the rib 32 against to press the respective strut 25, so seen in the radial direction of the drum 11 after Outside. The outgoing of the transverse edges 31 of the shell panel parts 24 are transversely directed edge regions thereof continuously between the clamping legs 30th the strut 25 and Andruckschenkeln 35 of the rib 32 clamped (Fig. 6), by the bias of the coupling members 36, the Andruckschenkel 35 against the transverse Edge regions of the shell sheet metal parts 24 and thus against the clamping legs 30 of the strut 25 presses. It comes thereby a surface, frictional and non-positive attachment of the transverse edges 31 of the shell panel parts 24 outgoing transverse edge regions the same at the respective strut 25 of the drum cage 22 state. This kind of Connection of the transverse edge regions of the jacket sheet metal parts 24 with the struts 25th allows almost constraintless changes in length of the shroud parts 24, by Extensions of the heated shell sheet metal parts 24 a further pushing the transversely directed edge regions of the shell sheet metal parts 24 in the gap between the Andruckschenkel 35, the rib 32 and the clamping leg 30 of the strut 25 allow. Conversely, a shortening of the jacket plate part 24 leads to a cooling of the same in that the transverse edges 31 of the shroud parts 24 are in the said gap can withdraw. Overstressing and especially bulging the Mantelblechteile 24 due to thermally induced changes in length of the same thereby effectively avoided.

In the circumferential direction of the drum 11 extending longitudinal edges of the shell sheet metal parts 24th are with the races 13, namely the long legs 26 thereof, screwed (Figure 2). Because of the clamping attachment of the transverse edge portions of the shell sheet metal parts 24 on the struts 25, which extends continuously over the entire transverse edges 31 the shroud parts 24 extend, and thus the shroud parts 24 over the whole Length of their transverse edges 31 on the drum cage 22 are clamped, need the Longitudinal edges of the shell sheet metal parts 24 only with a few screws on the races 13 to be attached. The holes in areas of the longitudinal edges of the Sheath sheet metal parts 24 may be formed slot-like, so that the screws thermally do not hinder conditional changes in length of the shell panel parts 24.

Each largely open end of the drum 11 is opposite the respective end wall 19 of the housing 10 sealed, according to the invention by means of a non-contact seal 40. In Fig. 5, the seal 40 in the region of the loading opening 16 of the tumble dryer partially shown. With a same seal 40 is the Discharge opening 17 in the opposite end face of the drum 11 relative to the Housing 10 sealed. The gasket 40 is formed between an outer one Ring portion of the annular sealing surface 29 on the outside of the short Leg 28 of each race 13 and a housing opening 20 surrounding annular area of the end wall 19 on the loading side of the housing 10. This is in the embodiment shown facing the end face of the drum 11 Inside the Sitrnwandung 19 of the housing 11, a housing opening 20th surrounding annular sealing lining 41 assigned. The sealing pad 41 is connected to the Inside the end wall 19 of the housing 10 firmly connected, preferably glued. Formed is the sealing pad 41 made of a soft material, in particular is heat resistant. It can be a felt material, a rubber, a plastic or the like. The sealing pad 41 partially overlaps the sealing surface 29 of the short leg 28 of the respective race 13 (Fig. 5). It arises between the Sealing surface 29 and pointing to this sealing surface 42 of the sealing pad 41 a Narrow annular gap 45, which is a non-contact, labyrinthine sealing of the relevant end face of the drum 11 relative to the housing 10 brought about, so that no appreciable air exchange between the inside of the drum 11 and the Outside thereof, in particular a lower part 43 of the housing 10, take place can. In addition, an air exchange with the environment is prevented by the lid 44. The lid 44 closes when running through washing machine the housing opening 20 located on the loading side and also a central part the loading opening 16 of the drum 11, but by an annular gap 45 no Contact with the rotating drum 11 can take place.

The invention is not only suitable for the continuous tumble driers described above with a loading opening 16 on an end face of the drum 11 at a Discharge opening 17 on the opposite end face of the drum 11; rather, too for other types of dryers, especially those that only at one end of the Drum 11 have an opening which also serves as a loading and unloading. In In this case, a seal 40 needs only at that end face of the drum 11th to be present, which also serves to load and unload the laundry. The opposite, closed end of the drum 11 then requires no Seal 40. Incidentally, however, the drum is designed as described above, in particular with a self-supporting drum cage 22 and shell sheet metal parts 24th provided, the continuous over the entire length of the transverse edges 31 and transverse edge regions clamped to the struts 25 of the drum cage 22 are attached.

LIST OF REFERENCE NUMBERS

10

casing

11

drum

12

Longitudinal central axis

13

race

14

Wheel

15

electric motor

16

loading opening

17

unloading

18

Kreisringwandung

19

end wall

20

housing opening

21

housing opening

22

drum cage

23

shell plate

24

Coat sheet metal part

25

strut

26

long thigh

27

tread

28

short thigh

29

sealing surface

30

clamping leg

31

transverse edge

32

rib

33

web

34

leg

35

pressure-applying

36

coupling member

37

web

38

mother

39

Through Hole

40

poetry

41

sealing covering

42

sealing surface

43

lower part

44

cover

45

annular gap

46

corner angle

47

radial leg

Claims (15)

Dryer, in particular tumble dryer, with a rotating drivable drum (11) having a cylindrical jacket plate (23) and circular races (13), wherein the drum (11) with the races (13) on wheels (14) and supported by at least one impeller (14) is drivable, characterized in that the races (13) by struts (25) are connected such that the races (13) with the struts (25) form a stable drum cage (22). Dryer according to claim 1, characterized in that the races (13) are connected by a plurality of preferably evenly distributed on the circumference of the drum (11) and parallel to a longitudinal central axis (12) of the drum (11) extending struts (25), wherein the Struts (25) are preferably fixedly connected to the races (13) and / or the struts (25) are profiled in cross section, in particular box or hollow profile-like design. Dryer according to one of the preceding claims, characterized in that the running rings (13) on the end faces of the drum cage (22) are arranged or end faces of the drum cage (22) form, and the struts (25) for connecting the races (13) between the end faces of the drum cage (22) are located. Dryer, in particular tumble dryer, with a rotatably drivable, cylindrical drum (11) having a jacket plate (23) and races (13), in particular according to one of the preceding claims, characterized in that the races (13) by struts (25) are connected to a drum cage (22), and the jacket plate (23) consists of a plurality of individual jacket plate parts (24) is formed which at least partially by clamping with the drum cage (22) are connectable. Dryer according to one of the preceding claims, characterized in that transverse edges (31) or from the transverse edges (31) outgoing edge regions of the cladding sheet metal parts (24) on the struts (25) are clamped fastened, preferably the transverse edges (31), in particular adjacent thereto Areas of the cladding sheet metal parts (24), in particular by force and / or frictionally engaged by clamping bars on the struts (25) are clamped. Dryer according to one of the preceding claims, characterized in that in the region of each strut (25) and each terminal strip opposite transverse edges (31) and adjoining edge regions of adjacent shroud parts (24) continuously, preferably over the substantially entire length of the transverse edges ( 31) or adjoining edge regions, can be fastened in a clamping manner. Dryer according to one of the preceding claims, characterized in that the transverse edges (31) or adjoining edge regions of the cladding sheet parts (24) between on opposite sides of the struts (25) projecting clamping legs (30) of the struts (25) and approximately parallel to the Clamping legs (30) extending Andruckschenkeln (35) of the terminal strips are clamped. Dryer according to one of the preceding claims, characterized in that in each case a terminal strip with a strut (25) releasably connected, in particular screwed, wherein the distance between the terminal strip, in particular the Andruckschenkel (35) to the clamping legs (30) of the respective strut (25 ), preferably elastically or resiliently can be changed for the continuous clamping of the transverse edges (31) and adjoining edge regions of the shell sheet metal parts (24) on the drum cage (22). Dryer according to one of the preceding claims, characterized in that the sheath sheet metal parts (24) are additionally fastened with their circular arc-shaped longitudinal edges on the races (13), preferably by screws. Dryer according to one of the preceding claims, characterized in that the clamping strips as in the interior of the drum (11) projecting ribs (32) are formed. Dryer, in particular tumble dryer, with a rotatably drivable, cylindrical drum (11) having a jacket plate (23) and races (13) and at least one opening in one end face, and with a drum (11) surrounding fixed housing (10 ), in particular according to one of the preceding claims, characterized in that at least the end face of the drum having the opening is sealed off from the housing (10) by at least one non-contact seal (40). Dryer according to one of the preceding claims, characterized in that the or each seal (40) in the region of at least one race (13) is arranged, preferably the respective seal (40) between a free outer end of at least one race (13) and a this opposite end wall (19) of the housing (10) is arranged. Dryer according to one of the preceding claims, characterized in that the seal in a narrow gap (annular gap 45) between the end face of the respective race (13) and the adjacent end wall (19) of the housing (10) is arranged. Dryer according to one of the preceding claims, characterized in that at least the or each of the end face of the respective race (13) facing inside the end wall (19) of the housing (10) at least partially narrowing the gap (annular gap 45) or bounding one side Sealing lining (41) is provided. Dryer according to one of the preceding claims, characterized in that at least one race (13) in particular on the outer peripheral surface (tread 27) and the front wall (19) of the housing (10) facing outer end face (sealing surface 29) is processed, preferably the outer end face of at least one race (13) is machined such that the end face (sealing face 29) runs as exactly as possible perpendicular to the axis of rotation of the longitudinal center axis (12) of the drum (11) and / or the running face (27) of at least one raceway (13 ) is machined such that it is as concentric as possible to the axis of rotation or longitudinal central axis (12) of the drum (11).

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