EP3169965B1 - Tube bottom and heat exchanger - Google Patents

Description

Technical area

The invention relates to a tube sheet according to the preamble of claim 1. Such a tube sheet is known from DE 10 2011 076 225 A1 , Moreover, the invention relates to a heat exchanger.

State of the art

Coolant cooler can have a plurality of tubes, which can be flowed through by a medium and at the same time can be flowed around by a medium. In a known design, the tubes are added end in tube sheets. The tubesheets have a number of openings corresponding to the number of tubes, one tube each being inserted into an opening. The tubesheet is closed by a box-like lid to a collection box. For this purpose, the box-like cover is inserted into the tubesheet and is connected to this.

From the DE 199 20 102 B4 is a multi-chamber tube known. This multi-chamber tube can be used in appropriately adapted tube plates, so as to form a heat exchanger block. Between the multi-chamber tubes rib elements can be arranged, which improve the heat transfer.

From the DE 10 2011 085 479 A1 a heat exchanger is known, which has two tube sheets, in each of which a plurality of tubes are accommodated at the end. In the tube sheets, a box-like lid is also used in each case, whereby a flow-through heat exchanger block is formed.

From the DE 103 43 239 A1 a heat exchanger is known, which has a heat exchanger block of a plurality of tubes end accommodated in tube plates. By box-like cover, which are inserted into the tube sheets and connected to the tube sheets, a flow-through heat exchanger block is formed.

From the DE 10 2008 011 579 A1 is a bottom plate of a header for a heat exchanger known. The bottom plate forms the so-called tube plate, which has a plurality of openings, in which tubes can be inserted. In the tubesheet shown can also be used a box-like lid, whereby a flow-through heat exchanger block can be generated.

A disadvantage of the devices in the prior art is in particular that the known tube sheets can be adapted only to different widths wide openings otherwise constant width of the tube sheet. It is therefore an increased adaptation effort required to provide tube plates of equal width with different width openings. In particular, the receiving area of the tube sheets, in which the box-like lid is used must be particularly adapted to achieve a sufficiently high density. Therefore, differently wide tube sheets are used for different widths of openings, whereby the dimensions of the heat exchanger formed vary. This requires a higher installation effort, which adversely affects the assembly time and costs.

Presentation of the invention, object, solution, advantages

Therefore, it is the object of the present invention to provide a tube sheet, which can be adapted to different widths openings in the tube sheet with the same width of the tube sheet. Furthermore, it is the object of the present invention to provide a heat exchanger with such a tube sheet.

The task with respect to the tube sheet is achieved by a tube sheet having the features of claim 1.

An embodiment of the invention relates to a tube plate for a heat exchanger, with a slot-like openings having bottom portion, the slot-like openings are surrounded by passages and the tube sheet has a raised edge region, wherein between the passages and the erected edge region a U-shaped groove as a receiving area for the foot of a box-like cover is formed, wherein the U-shaped groove is formed by an inner first wall, the erected edge region and a second wall forming the channel bottom, wherein the inner first wall at least a hump-like shape in extension of a passage on the U having-shaped groove facing side which limits the width of the U-shaped groove between the erected edge region and the first wall and extending from the groove bottom toward the U-shaped groove facing end portion of the passage, which for generating an insertion bevel for pipes.

It is advantageous if a material displacement is formed toward the side facing away from the U-shaped groove side of the first wall by the molded recess.

By a hump-like shape of the inner wall, the width of the U-shaped channel can be limited particularly advantageous. At the same time, the height of the U-shaped groove on the inside can be defined by the hump-like shape. The hump-like shape can be adjusted in particular depending on the width of the passages. In this way, tube sheets can be produced with an identical basic width, which each have different widths openings and passages. This is advantageous because the same production machines can be used for the different tube sheets and only the respective thermoforming tools must be adapted. In addition, a standardized width for the tube sheets can be guaranteed even with pipes of different widths, whereby the space requirements of the heat exchanger generated can be standardized.

Through a molded recess, a targeted material shift can be achieved. It can be achieved as a greater material thickness, in particular on the side facing away from the U-shaped groove side of the inner wall, as additional material is displaced by the molding of the recess there. This is particularly advantageous for being able to produce sufficiently large chamfers for mounting the tubes on the tubesheet.

By adjusting the hump-like shape, the transition region between the U-shaped groove and the end portion of the passage can be configured individually, so that a sufficient guidance and fixation for the foot of a box-like lid is given and at the same time a sufficient material thickness for the formation of insertion bevels for Facilitates the pipe assembly remains.

Moreover, it is advantageous if the deflection of the hump-like formation from the inner wall, starting from the channel bottom, increases toward the respective passage. This is advantageous since an inclined surface is thus produced, which faces the U-shaped groove and can serve as a centering aid for the foot region of a box-like cover.

It is also advantageous if the hump-like shape extends into the bottom area and at least partially surrounds the passage. This is particularly advantageous in order to produce a higher stability and at the same time to achieve smoother transitions between the draft and the bump-like formation or the inner wall.

It is also expedient if the first wall has an insertion bevel on its side facing away from the U-shaped groove, wherein the insertion bevel is arranged on the bump-like formation and the lead-in bevel produces a narrowing of the slot-like openings framed by the passages.

An insertion bevel is advantageous in order to facilitate the insertion of the tubes into the openings framed by the passages. It is particularly advantageous if the chamfers are formed in areas of the tube sheet, which has a sufficient material thickness to form a sufficiently long insertion bevel.

Moreover, it is advantageous if the insertion bevel is formed on the molded-in depression. An insertion bevel on the molded-in depression is advantageous because an accumulation of material is created by the depression, which allows a sufficiently large insertion bevel.

A further preferred embodiment is characterized in that the slot-like openings have two opposite narrow sides and have two opposite broad sides, wherein a slot-like opening on the narrow side and the narrow side facing end portions the broadsides is tapered by insertion bevels. It is particularly advantageous if insertion bevels are formed both on the narrow side and on the broad sides in order to allow the most accurate and simple production possible. In particular, the insertion of the tubes is thereby facilitated.

Furthermore, it is particularly advantageous if the hump-like shape and / or the recess in the bump-like shape is embossed into the tube sheet and / or is formed by deep-drawing. The embossing and / or deep-drawing is advantageous in order to produce the hump-like shape and the recess with the same manufacturing method, as the rest of the tube sheet. This simplifies production and thus reduces costs.

It is also preferable if the first wall and the surface of the bump-like formation facing the U-shaped groove are aligned at an angle greater than 90 degrees to the channel bottom. An angle greater than 90 degrees is advantageous to create a slope which allows for an advantageous insertion of the foot region of a box-like lid into the U-shaped groove.

It is also advantageous if the U-shaped groove facing side of the hump-like formation forms a centering aid for the insertion of the box-like lid in the U-shaped groove.

The object with regard to the heat exchanger is achieved by a heat exchanger with the features of claim 10.

An embodiment of the invention relates to a heat exchanger with two tube sheets, wherein the heat exchanger has a plurality of tubes which are arranged parallel to each other and are each end received in a framed by a passage opening of a tube plate, wherein the tubes along the insertion bevels into the respective openings are introduced, wherein in the U-shaped groove of each tube sheet each have a box-like lid is inserted, which is connected to the respective tubesheet.

Such a heat exchanger is particularly advantageous because it is particularly easy to assemble. The chamfers allow easy positioning of the tubes in the openings. Furthermore, the centering allows the hump-like shape easy positioning of the box-like lid in the U-shaped groove.

Advantageous developments of the present invention are described in the subclaims and in the following description of the figures.

Brief description of the drawings

Fig. 1

eine Schnittansicht eines Rohrbodens, wie er im Stand der Technik bekannt ist,

Fig. 2

eine Schnittansicht eines Rohrbodens, wobei der Übergang zwischen dem Durchzug und der U-förmigen Rinne durch eine höckerartige Ausformung gebildet ist,

Fig. 3

eine Ansicht zweier Konturen jeweils einer U-förmigen Rinne,

Fig. 4

eine perspektivische Ansicht eines Rohrbodens, wobei die Öffnung beziehungsweise der Durchzug sehr breit ausgebildet ist,

Fig. 5

eine perspektivische Ansicht eines alternativ ausgestalteten Rohrbodens, wobei die Öffnungen beziehungsweise die Durchzüge weniger breit ausgestaltet sind als in der vorausgegangenen Figur 4, wobei die höckerartige Ausformung ein Plateau aufweist,

Fig. 6

eine perspektivische Ansicht eines alternativen Rohrbodens, wobei das Plateau flacher ausgestaltet ist als bei dem in Figur 5 gezeigten Rohrboden,

Fig. 7

eine Schnittansicht durch einen erfindungsgemäßen Rohrboden, wobei in die höckerartige Ausformung von oben eine Vertiefung eingeformt ist, welche eine Materialanhäufung an der nach unten gerichteten Seite der höckerartigen Ausformung erzeugt,

Fig. 8

eine perspektivische Ansicht des Rohrbodens gemäß Figur 7,

Fig. 9

eine Ansicht der Unterseite des Rohrbodens gemäß der Figuren 7 und 8,

Fig. 10

eine Schnittansicht durch zwei Rohrböden, wobei ein Rohrboden mit einem weniger breiten Durchzug und ein Rohrboden mit einem breiteren Durchzug dargestellt ist, und

Fig. 11

eine perspektivische Ansicht eines Rohrbodens mit zwei unterschiedlichen Ausgestaltungen einer Einführschräge.

In the following the invention will be explained in detail by means of embodiments with reference to the drawings. In the drawings show:

Fig. 1

a sectional view of a tube sheet, as is known in the art,

Fig. 2

a sectional view of a tube plate, wherein the transition between the passage and the U-shaped groove is formed by a hump-like shape,

Fig. 3

a view of two contours each of a U-shaped channel,

Fig. 4

a perspective view of a tube sheet, wherein the opening or the passage is formed very wide,

Fig. 5

a perspective view of an alternatively configured tube plate, wherein the openings or the passages are designed to be less wide than in the previous FIG. 4 , wherein the hump-like shape has a plateau,

Fig. 6

a perspective view of an alternative tube sheet, wherein the plateau is made flatter than in the FIG. 5 shown tube sheet,

Fig. 7

a sectional view through a tube sheet according to the invention, wherein in the hump-like formation from above a recess is formed, which generates a material accumulation on the downward side of the bump-like formation,

Fig. 8

a perspective view of the tube sheet according to FIG. 7 .

Fig. 9

a view of the bottom of the tube sheet according to the FIGS. 7 and 8 .

Fig. 10

a sectional view through two tube sheets, wherein a tube sheet is shown with a less wide passage and a tube sheet with a wider passage, and

Fig. 11

a perspective view of a tube sheet with two different configurations of a lead-in.

Preferred embodiment of the invention

The Fig. 1 shows a cross section through a tube sheet 1, as is known in the art. The tube plate 1 has a plurality of openings 3, which are arranged on the flat bottom portion 2. The openings 3 are each surrounded by passages 4. Right and left of the openings 3 U-shaped grooves 5 are formed, which are formed substantially between a raised edge region 6 and an inner wall 7 extending parallel thereto.

The U-shaped grooves 5 are closed at the bottom by the groove bottom 8. Along the direction 9 tubes can be inserted into the openings 3.

The Fig. 2 shows a sectional view through an alternatively configured tube sheet 10, which in particular has a different geometry for the U-shaped groove 14. In particular, the transition of the passages 13 towards the U-shaped groove 14 is deviating.

The tube sheet 10 has a bottom portion 11 in which a plurality of openings 12 are formed, which are surrounded by collar-like passages 13. The left and right lying end portions of the passages 13 are closed by hump-like formations 22, which can be introduced, for example, by an embossing process in the inner wall 17 of the tube sheet 10. The passages 13 extend through the hump-like formations 22 out into the U-shaped channel 14. The U-shaped channel 14 is formed by the erected edge region 15, the inner wall 17 and the channel bottom 24. The upper region 16 of the erected edge region 15 is further angled in comparison to the lower region 15.

In particular, the inner wall 17 is at an angle greater than 90 ° to the channel bottom 24. The hump-like shape 22 forms on its outward to the erected edge region 15 side facing a surface 21, which in particular as a centering for inserting a box-like cover or the foot of the box-like lid can be used. The surface 21 is inclined in such a way that a box-type lid inserted from above is automatically deflected into the U-shaped channel 14 provided for this purpose.

Reference numerals 18 and 19 show different possible positions for a foot region of a box-like lid. The limit 20 represents the maximum possible inner position for a foot area. A further displacement of the foot area inwards would become a faulty one lead a non-accurate installation. Each arrangement of a foot area, which lies to the left of the marking 20, leads, with the aid of the centering aid 21, to a snug fit of the foot area in the U-shaped groove 14. The tube sheet 10 of FIG FIG. 2 is also already known from the prior art.

The FIG. 3 shows two cross sections of U-shaped grooves each a tube plate. In this case, the reference numeral 30, a contour of a U-shaped channel is shown with a hump-like shape, as for example in FIG. 2 is indicated. The reference numeral 31 shows a contour of a U-shaped groove, as shown in FIG FIG. 1 is shown by way of example. The FIG. 3 illustrates the different structure, in particular the different width or the different height on the inner side of the different U-shaped grooves.

The FIG. 4 shows a perspective view of a tube sheet 10, as already in the FIG. 2 was shown. In FIG. 4 In particular, it can be seen that the hump-shaped formation 22 has a flat surface 21 directed towards the erected edge region 15, which also serves as a centering aid. The hump-like shape 22 is formed from the otherwise flat inner wall 17, for example by deep drawing or by embossing.

The hump-like formation 22 extends not only over the inner wall 17, but also into the bottom area 11, where in particular the portion 23 of the hump-like formation 22 encloses the passage 13 along its broad sides.

The FIG. 5 shows an alternative embodiment of a tube plate 40. The tubesheet 40 has a bottom portion 41 which has a plurality of openings 42 which are surrounded by collar-like passages 43.

The passages 43 and the openings 42 have in the embodiment of FIG. 5 a shorter extension in the width of the tube bottom 40th Die Breite des Tube bottom 40 is measured here and also in the other exemplary embodiments in each case by an erected edge region 45 to the edge region opposite thereto.

To this shortening of the openings 42 and the passages 43 in comparison to the execution of FIG. 4 to compensate, the hump-like formation 48 on an extended portion, which is formed as a plateau 50. As in the previous one FIG. 4 A portion 49 of the hump-like formation 48 also partially encloses the broad sides of the respective passage 43. The hump-like formation 48 likewise has an area facing the raised edge region 45, which can be used as a centering aid.

The U-shaped channel 44 is formed by the erected edge region 45, the inner wall 47 and the channel bottom 51. The erected edge region 45 has slots, which can serve to secure the box-like cover in the tube plate 40. The attachment of the box-like cover can be achieved, for example, by jamming, the provision of a corrugated slot flanging or with the aid of other known fixing elements.

The hump-like shape 48, in particular the plateau 50 and the portion 49 are also formed by an embossing process or by deep drawing from the inner wall 47 and the bottom portion 41.

The plateau 50 serves to bridge between the U-shaped groove 44 and the passage 43. It must preferably be shallow enough that sufficient material remains on the underside of the tube bottom 40 in order to form a sufficient insertion be able and at the same time high enough to to ensure a sufficient height of the U-shaped groove 44 on the inside. The plateau 50 is in the embodiment of FIG. 5 highly trained. This allows a sufficient height of the U-shaped groove 44, but is not optimal with respect to the insertion slope at the bottom. The following FIG. 6 shows a plateau 70, which is flatter and thus more advantageous in terms of the formation of an insertion bevel is, but at the same time a lower height of the U-shaped channel conditionally, which is disadvantageous.

The FIG. 6 shows a further alternative embodiment of a tube plate 60, which has a bottom portion 61 with an opening 62 arranged therein and a collar-like passage 63. The opening 62 and the passage 63 point in FIG. 6 a relatively short extension in the width of the tube plate 60. The hump-like formation 68, for this reason, also has a plateau 70, the plateau 70 compared to the plateau 50 of the preceding FIG. 5 shorter and flatter fails. For this, the portion 69, which includes the broad sides of the passages 63, further formed from the plane of the bottom portion 61 as the plateau 70. The portion 69 forms a U-shaped bead, which the passage 63 both on the broad sides and on the The narrow side encloses.

Also, the tube plate 60 has a U-shaped groove 64. The U-shaped channel 64 is analogous to the preceding figures by a raised edge portion 65, an inner wall opposite this 67 and a channel bottom 71 formed. The erected edge region 65 also has an outwardly angled portion 66 in the upper region. The hump-shaped formation 68 also has an area directed to the raised edge area 65, which can be used as a centering aid.

The FIG. 7 shows an inventive embodiment of a tube plate 80. The tube plate 80 has a bottom portion 81. In the bottom region 81 openings 82 are formed, which are surrounded by collar-like passages 83. The openings 82 had two opposite narrow sides 98 and two opposite broad sides 97. Accordingly, the passages 83, which surround the openings 82 each have two narrow sides 98 and two broad sides 97. The U-shaped groove 84 is formed by a raised edge portion 85 and an inner wall 87 opposite thereto and the channel bottom 94.

From the inner wall 87 and the bottom portion 81 a hump-like shape 88 is formed, which in particular with the raised edge portion 85 facing surface 91 includes a smaller angle to the erected edge portion 85 than the inner wall 87. In addition, the hump-like shape 88 has a from above formed recess 90, which is disposed immediately adjacent to the end portion of the passage 83.

By the recess 90, which can also be formed by a stamping process or by deep drawing in the bump-like formation 88, a material displacement takes place downwards, which in particular on the downwardly directed side 96 of the inner wall 87 and the bottom portion 81 a formation of a Insertion bevel allowed. As a result of the material displacement, the insertion bevel can be made larger overall, wherein in particular the extent of the insertion bevel along the direction of insertion of the tubes can be increased. This simplifies the insertion of the tubes and thus allows a more stable assembly process. The insertion bevel is in FIG. 7 not shown.

In FIG. 7 The hump-like formation 88 also encloses the broad sides 97 of the passage 83 with a portion 89. Furthermore, the hump-like formation forms a sufficient height of the U-shaped groove 84, whereby a secure positioning of a box-like cover can be ensured.

The FIG. 8 shows a further perspective view of the tube plate 80, as already in the FIG. 7 was shown. In FIG. 8 it can be seen in particular that the recess 90 is formed by a straight, parallel to the U-shaped groove 84 extending recess. Furthermore, in FIG. 8 to recognize that both the end portion 99 of the broad sides 97 and the narrow side 98 of the passage 83 and the opening 82 from the portion 89 of the bump-like formation 88 are enclosed. Furthermore, the hump-like shape 88 also forms a flat, inclined surface 91, which can be used as a centering aid for the foot of a box-like lid.

The FIG. 9 shows a view of the tube sheet 80 of FIGS. 7 and 8 with a view from below of the opening 82 and the passage 83. It is the side facing away from the U-shaped groove 84 side 96 of the inner wall 87 can be seen. In the FIG. 9 Furthermore, in particular the insertion bevels 92 and 93 can be seen, which run both on the narrow side 98 of the passage 83 and on the end regions 99 of the two broad sides 97. These insertion bevels 92 and 93 are formed in particular in the region of the material displacement produced by the depression 90. These serve in particular for the simplified positioning and mounting of the tubes in the openings 82.

The embodiment of the invention as shown in the FIGS. 7 to 9 can be shown, in particular with the previous embodiments for less wide passages 43 and wider passages 13 of the FIGS. 4 to 6 be combined. In particular, the additional recess 90, which leads to a material displacement, is advantageous in order to obtain the required material on the underside of the passages 83 in order to form sufficiently sized chamfers 92 and 93 can. This is due in particular to the fact that the tubesheets, as in the FIGS. 1 to 9 are shown, preferably produced from a platinum-like material by a plurality of deep drawing operations. In each deep-drawing process, material compression and expansion take place, which ultimately lead to a dilution of the base material. By introducing an additional depression, this partially disadvantageous dilution can be counteracted and material can be selectively transferred to defined areas.

The FIG. 10 shows a comparative view of an embodiment with a tube sheet 80 with a less wide passage 83 and a wider passage 13, as it is already in the FIG. 4 was shown. It is in FIG. 10 In particular, it can be seen that the U-shaped groove 14 or 84 is designed to be identical regardless of the width of the passage 13 or 83. In the case of the less wide passage 83, the recess 90 is formed in the hump-like shape 88, as shown in the FIGS. 7 to 9 was presented. In the case of the broader Passage 13 is this depression, as already in FIG. 4 shown, not provided. However, in an alternative embodiment, the recess may also be combined with a wide passage 13.

The FIG. 11 shows a comparative view of two insertion bevels 101 and 102, as they can be formed depending on the width of the passage, which is designated by the reference numeral 100. The insertion bevels 101 and 102 form in particular the end-side insertion bevels, which are formed on the respective narrow side of the passage 100. The insertion bevel formed on the narrow side preferably has an angle of approximately 40 ° relative to a vertical, while the insertion bevels at the end regions of the broad sides preferably have an angle of approximately 30 ° to the vertical. These values are exemplary and in particular do not limit the design of the individual embodiments.

The embodiments of the preceding FIGS. 1 to 11 are exemplary and partially represent embodiments as known in the art. In particular, a combination of the features of the known from the prior art embodiments, which in the FIGS. 1 to 6 are shown, and the features of the embodiments according to the invention, which in the FIGS. 7 to 9 are shown is possible at any time. The individual embodiments of the figures, in particular with regard to the choice of material, the arrangement of the individual elements and the dimensioning of the respective elements have no limiting character.

Claims (11)

1. A tube bottom (80) for a heat exchanger, which has a bottom region (81) with slot-type openings (82), wherein the slot-type openings (82) are rimmed by eyelets (83) and the tube bottom (80) has an attached rim region (85), wherein between the eyelets (83) and the attached rim region (85), a U-shaped trough (84) is formed as a receiving area for the bottom of a box-like cover, wherein the U-shaped trough (84) is formed by an inner first wall (87), the attached rim region (85) and a second wall forming the trough bottom (94), wherein the inner first wall (87) has at least one hump-like portion (88) in the extension of an eyelet (83) on the side (95) facing the U-shaped trough (84), which bounds the breadth of the U-shaped trough (84) between the attached rim region (85) and the first wall (87) and extends from the trough bottom (94) to the end region of the eyelet (83) facing the U-shaped trough (84), characterised in that a depression (90) is formed in the hump-like portion (88) which serves to produce a lead-in chamfer (92, 93) for tubes.
2. The tube bottom according to claim 1, characterised in that a displacement of the material towards the side (96) of the first wall (87) facing away from the U-shaped trough (84) is formed by the moulded-in depression (90).
3. The tube bottom (80) according to claim 1 or 2, characterised in that the deflection of the hump-like portion (88) from the inner wall (87) increases from the trough bottom (94) towards the respective eyelet (83) .
4. The tube bottom (80) according to one of the preceding claims, characterised in that the hump-like portion (88) extends into the bottom region (81) and at least partly surrounds the eyelet (83).
5. The tube bottom (80) according to one of the preceding claims, characterised in that the first wall (87) has a lead-in chamfer (92, 93) on its side (96) facing away from the U-shaped trough (84), wherein the lead-in chamfer (92, 93) is arranged on the hump-like portion (88) and the lead-in chamfer (92, 93) creates a tapering of the slot-type openings (82) rimmed by the eyelets (83).
6. The tube bottom (80) according to claim 5, characterised in that the lead-in chamfer (92, 93) is formed on the moulded-in depression (90).
7. The tube bottom (80) according to one of claims 5 or 6, characterised in that the slot-type openings (82) have two opposing narrow sides (98) and two opposing wide sides (97), wherein a slot-type opening (82) is tapered by lead-in chamfers (92, 93) on the narrow side (98) and on the end regions (99) of the wide sides (97) facing the narrow side (98).
8. The tube bottom (80) according to one of the preceding claims, characterised in that the hump-like portion (88) and/or the depression (90) is impressed into the tube bottom (80) in the hump-like portion (88) and/or moulded in by means of thermoforming.
9. The tube bottom (80) according to one of the preceding claims, characterised in that the first wall (87) and the surface (91) of the hump-like portion (88) oriented to the U-shaped trough (84) are directed towards the trough bottom (94) at an angle of more than 90 degrees.
10. The tube bottom (80) according to one of the preceding claims, characterised in that the surface (91) of the hump-like portion (88) facing the U-shaped trough (84) provides a centring aid for inserting the box-like cover into the U-shaped trough (84) .
11. A heat exchanger with two tube bottoms according to any one of the preceding claims, characterised in that the heat exchanger has a plurality of tubes, which are arranged parallel to each other and are accommodated at their ends in each case in an opening of a tube bottom rimmed by an eyelet, wherein the tubes are each inserted in the respective openings along the lead-in chamfers, wherein a box-like cover, which is connected to the respective tube bottom, is inserted into the U-shaped trough of each tube bottom.

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