HRP930915A2

HRP930915A2 - Refractory lining and brick

Info

Publication number: HRP930915A2
Application number: HR930915A
Authority: HR
Inventors: Klaus Wieland; Bernhard Schmalenbach; Dieter Schlacht
Original assignee: Didier Werke Ag
Priority date: 1990-09-08
Filing date: 1993-05-19
Publication date: 1995-12-31

Description

Izum se odnosi na obzidavanje, odnosno kamen za obzidavanje peći, npr. za taljenje stakla, pri čemu obzidavanje, odnosno kamen za obzidavanje ima barem jedno udubljenje, koje tvore površine stijenki, koje reflektiraju kroz presjek otvora udubljenja iz peći izlazeću toplinu isijavanja. The invention relates to walling, i.e. stone for walling a furnace, e.g. for melting glass, wherein the walling, or stone for walling has at least one depression, which forms the surfaces of the walls, which reflect the radiant heat coming out of the furnace through the section of the opening of the depression.

Kamen za obzidavanje te vrste je opisan u DE 287 14 250 C2 za peć za rastaljivanje stakla. Kod DE 28 14 250 C2 su udubljenja tako formirana, da su plohe za reflektiranje topline što je moguće veće. U tu svrhu su udubljenja izvedena piramidno ili kao podsječeni stožac, pri čemu sa strane unutarnjeg prostora nalazeći se presjek otvora udubljenja tvori najveći presjek udubljenja. S time da bi se što je moguće veći dio na obzidavanje pripadajuće topline reflektirao na staklo, koje se tali, da bi se time povisila učinkovitost peći. A masonry stone of this type is described in DE 287 14 250 C2 for a glass melting furnace. With DE 28 14 250 C2, the recesses are formed in such a way that the surfaces for reflecting heat are as large as possible. For this purpose, the depressions are made pyramidal or as a truncated cone, where the section of the depression opening on the side of the inner space forms the largest section of the depression. With the fact that as much of the associated heat as possible would be reflected on the glass, which melts, in order to increase the efficiency of the furnace.

Naposljetku se pri DE 28 14 250 C2 kao kod glatkog svoda pogađajuće isijavanje reflektira pretežno neposredno u prostor peći. Kod takvog reflektiranog isijavanja plamena odnosno plina dolazi do reapsorpcije. Reapsorbirani udjeli isijavanja mogli bi ne doseći tvar koja se zagrijava. Finally, with DE 28 14 250 C2, as with a smooth vault, the striking radiation is mainly reflected directly into the furnace space. With such reflected emission of flame or gas, reabsorption occurs. Reabsorbed fractions of radiation may not reach the substance being heated.

Bilo je ustanovljeno, da povećanje toplotne refleksije na obzidavanju ne vodi do daljnjih poboljšanja, zato što se dio reflektiranog isijavanja topline na temelju jednake valne dužine reapsorbira sa strane izvora, koji emitira toplinu, dakle plamena. It was established that the increase in thermal reflection on the walling does not lead to further improvements, because part of the reflected heat radiation based on the same wavelength is reabsorbed on the side of the source, which emits heat, i.e. the flame.

Zadatak izuma je predložiti obzidavanje, odnosno kamen za obzidavanje u uvodu spomenute vrste, kod kojeg je od njega emitirano toplotno isijavanje povećano na račun od njega reflektiranog isijavanja. The task of the invention is to propose walling, that is, walling stone of the type mentioned in the introduction, where the thermal radiation emitted from it is increased at the expense of the radiation reflected from it.

Prema izumu je gornji zadatak kod obzidavanja, odnosno kamena za obzidavanje u uvodu spomenute vrste, riješen time, da su plohe stijenke, udubljenja geometrijski takvog oblika, da od jedne plohe stijenke reflektirana toplina isijavanja pogodi drugu plohu stijenke i time tu toplinu apsorbira kamen za obzidavanje. According to the invention, the above task of walling, i.e. walling stone of the type mentioned in the introduction, is solved by the fact that the flat walls, recesses are geometrically shaped in such a way that the radiant heat reflected from one flat wall hits the other wall surface and that heat is absorbed by the walling stone .

Time je direktna refleksija toplinskog isijavanja u sam unutarnji prostor peći smanjena. To je zato jer se u udubljenju veliki dio topline odbija na kamen za obzidavanje, koji to toplinsko isijavanje apsorbira. Toplina, koju apsorbira kamen za obzidavanje se od istog opet emitira i time dovede u unutarnji prostor peći, posebno materijalu, koji se zagrijava. Toplinsko isijavanje, koje se u danom primjeru preko višekratne refleksije apsorbira u udubljenjima obzidavanja, se od obzida poslije reemitira s promijenjenom valnom dužinom, tako da materijal koji se zagrijava, dostiže veći udio isijavanja nego kod stanja tehnike. This reduces the direct reflection of thermal radiation into the inner space of the furnace. This is because in the recess, a large part of the heat is reflected on the masonry stone, which absorbs this thermal radiation. The heat that is absorbed by the walling stone is emitted from it again and is brought to the inner space of the furnace, especially to the material, which is heated. The thermal radiation, which in the given example is absorbed in the depressions of the walls through repeated reflection, is later re-emitted from the walls with a changed wavelength, so that the material that is heated reaches a higher proportion of radiation than in the state of the art.

Na primjeru peći za taljenje stakla se time u konačnom rezultatu dobiva s jedne strane reduciranje potrebne temperature obzidavanja, jer se već kod niže temperature, udio topline potreban za topljenje stakla, emitira sa obzida u unutarnji prostor peći. To ima za posljedicu, da se javljaju niže temperature otpadnih plinova i manji toplinski gubici. S druge strane se kod nereducirane temperature obzidavanja dobiva mogućnost povećanja količine stakla, kojeg treba rastaliti, povezano s poboljšanjem kakvoće stakla radi jednolikog i bržeg nadotaljivanja količine stakla. On the example of a glass melting furnace, the final result is thus a reduction of the required temperature of the walls, because already at a lower temperature, the proportion of heat required for glass melting is emitted from the walls into the inner space of the furnace. This results in lower waste gas temperatures and lower heat losses. On the other hand, with unreduced walling temperature, the possibility of increasing the amount of glass that needs to be melted is obtained, connected with the improvement of the quality of the glass for uniform and faster melting of the amount of glass.

Prednostne značajke izuma proizlaze iz podzahtjeva i slijedećeg opisa izvedbenih primjera. U nacrtima prikazuje: Advantageous features of the invention derive from the subclaims and the following description of the exemplary embodiments. In the plans it shows:

Sl. 1 dva kamena za obzidavanje u svodu peći u presjeku uzduž linije I-I sa Sl. 2, Sl. 1 two stones for walling in the vault of the furnace in a section along the line I-I from Fig. 2,

Sl. 2 pogled u smjeru strelice II sa Sl. 1, Sl. 2 view in the direction of arrow II from Fig. 1,

Sl. 3 alternativnu izvedbu udubljenja kamena za obzidavanje, Sl. 3 alternative execution of stone recesses for walling,

Sl. 4 daljnju alternativu oblika udubljenja, Sl. 4 a further alternative of the shape of the indentation,

SI. 5 Sl. 1 odgovarajući pogled daljnjeg izvedbenog oblika, SI. 5 Fig. 1 corresponding view of a further embodiment,

Sl. 6 daljnji izvedbeni primjer, Sl. 6 further exemplary embodiment,

Sl. 7 dodatni izvedbeni primjer u pogledu, koji odgovara Sl. 1 i Sl. 7 additional exemplary embodiment in view, which corresponds to FIG. 1 i

Sl. 8 Sl. 7 sličan izvedbeni primjer, Sl. 8 Fig. 7 similar implementation example,

Sl. 9 Sl. 7 sličan daljnji izvedbeni primjer, Sl. 9 Fig. 7 a similar further embodiment,

Sl. 10 obzidavanje s udubljenjem u obliku šuplje kugle, Sl. 10 walling with a depression in the form of a hollow sphere,

Sl. 11 pogled u smjeru strelice XI prema Sl. 10 i Sl. 11 view in the direction of arrow XI according to FIG. 10 i

Sl. 12 alternativa izvedbenom primjeru prema Sl. 11, odnosno Sl. 10. Sl. 12 alternative to the embodiment according to FIG. 11, or Fig. 10.

Kamen 1 obzidavanja od vatrostalnog keramičkog materijala ima izvana više izreza 2. Prema Sl. 2 je predviđeno osam izreza 2. Izrezi 2 su otvoreni prema onoj površini 3 kamena 1 obzidavanja, koja je okrenuta k unutarnjem prostoru 4 peći. Kameni 1 obzidavanja su tako međusobno sastavljeni, da dva susjedna izreza 2 svaki put tvore udubljenje 5, koje je otvoreno samo k unutarnjem prostoru 4 peći s presjekom A otvora. Stone 1 of the walling made of refractory ceramic material has several cutouts 2 on the outside. According to Fig. 2, eight cutouts 2 are provided. The cutouts 2 are open to the surface 3 of the stone 1 of the walling, which faces the inner space 4 of the furnace. The stones 1 of the walling are put together in such a way that two adjacent cut-outs 2 each time form a recess 5, which is open only to the inner space 4 of the furnace with a section A of the opening.

Presjek A otvora je jednak ili manji od presjeka B udubljenja 5 u području dna 6 udubljenja 5. The section A of the opening is equal to or smaller than the section B of the recess 5 in the area of the bottom 6 of the recess 5.

Udubljenje 5 ima u nastavku dna 6 bočne stijenke 7. Dno 6 je tako oblikovano, da se na njega iz unutarnjeg prostora 4 peći nailazeća toplina isijavanja reflektira na bočnoj stijenki 7, te ove stijenke tu toplinu apsorbiraju. To je u slikama djelomično naznačeno crtkano. In the continuation of the bottom 6, the recess 5 has side walls 7. The bottom 6 is shaped in such a way that the radiant heat coming to it from the inner space 4 of the furnace is reflected on the side wall 7, and these walls absorb that heat. This is partially indicated by dashed lines in the pictures.

Kod izvedbenog primjera prema Sl. 1 dno 6 prolazi pod oštrim kutom a prema liniji L, koja je usporedna s površinom 3, pri čemu jedan dio dna 6 tvori izrez 2 jednog kamena 1 obzidavanja i drugi dio dna 6 čini izrez 2 susjednog kamena 1 obzidavanja. In the implementation example according to Fig. 1 the bottom 6 passes at a sharp angle a towards the line L, which is parallel to the surface 3, whereby one part of the bottom 6 forms a cutout 2 of one walling stone 1 and the other part of the bottom 6 forms a cutout 2 of the neighboring stone 1 of the walling.

Kod izvedbenog primjera prema Sl. 3 je dno 6 oblikovano slično kao kod izvedbenog primjera prema Sl. 1, samo što je oblikovano konkavno zakrivljeno. In the implementation example according to Fig. 3, the bottom 6 is shaped similarly to the embodiment according to Fig. 1, except that it is shaped concavely curved.

Kod izvedbenog primjera prema Sl. 4 je dno 6 konveksno oblikovano. Pri tom bočna ploha 7 čini s dijelom dna 6, koji je blizu njoj, oštar kut b. Kod izvedbenih primjera prema Sl. 1 do 4, mogu presjeci A otvora biti jednaki presjecima B, zato jer je oblikom dna 6 osigurano, da se veliki dio na dnu 6 reflektiranog toplinskog isijavanja apsorbira u bočnim stijenkama 7. S konusnim izlazom bočnih stijenki 7 na način, da je presjek A otvora manji od presjeka B, može se glede oblika dna 6, toplina, koju apsorbiraju bočne stijenke 7, povećati. In the implementation example according to Fig. 4, the bottom 6 is convexly shaped. At the same time, the side surface 7 forms a sharp angle b with the part of the bottom 6, which is close to it. 1 to 4, the cross-sections A of the openings can be equal to the cross-sections B, because the shape of the bottom 6 ensures that a large part of the reflected thermal radiation on the bottom 6 is absorbed by the side walls 7. With the conical exit of the side walls 7 in such a way that the cross-section A opening smaller than section B, due to the shape of the bottom 6, the heat absorbed by the side walls 7 can increase.

Izvedbeni primjeri sa Sl. 3 i 4 pokazuju također, da udubljenje nije nužno ostvariti sastavljanjem dvaju kamena za obzidavanje, nego može ležati potpuno u jednom samom kamenu za obzidavanje. Performance examples from Fig. 3 and 4 also show that the indentation is not necessarily created by assembling two masonry stones, but can lie completely in one masonry stone.

Kod izvedbenog primjera prema Sl. 5 je presjek A otvora primjetno manji od presjeka B u području dna 6. Dno 6 kao takvo ovdje prolazi usporedno s površinom 3. Bočne stijenke 7 tvore s dnom 6 oštar kut b i s presjekom A otvora tupi kut c. In the implementation example according to Fig. 5, the section A of the opening is noticeably smaller than the section B in the area of the bottom 6. The bottom 6 as such here runs parallel to the surface 3. The side walls 7 form a sharp angle b with the bottom 6 and an obtuse angle c with the section A of the opening.

Kod izvedbenog primjera prema Sl. 6 udubljenja 5 nisu izrađena pomoću dva, s izrezima 2 opremljena kamena 1 za obzidavanje, nego pomoću tri kamena za obzidavanje. Predviđen je dulji kamen 8 za obzidavanje i kraći kamen 9 za obzidavanje, pri čemu je svaki put između dva dulja kamena 8 za obzidavanje raspoređen kraći kamen 9 za obzidavanje. Kraći kamen 9 za obzidavanje tvori dno 6, koje može i ovdje biti oblikovano konkavno ili konveksno. Oba susjedna kamena 8 za obzidavanje tvore bočne stijenke 7, sa koje se od dna 6 reflektira toplotno isijavanje. In the implementation example according to Fig. 6 recesses 5 were not made with two, with cutouts 2 equipped with masonry stones 1, but with three masonry stones. A longer walling stone 8 and a shorter walling stone 9 are provided, whereby a shorter walling stone 9 is arranged between two longer walling stones 8 each time. The shorter walling stone 9 forms the bottom 6, which can also be shaped concave or convex here. Both adjacent masonry stones 8 form side walls 7, from which heat radiation is reflected from the bottom 6.

Presjek A otvora je i ovdje manji ili jednak presjeku B u području dna 6. To je postignuto time, da je kamen 8 i/ili 9 za obzidavanje konusno oblikovan. The cross-section A of the opening here is also smaller or equal to the cross-section B in the area of the bottom 6. This was achieved by the fact that the walling stone 8 and/or 9 is conically shaped.

Ako je presjek A otvora manji od presjeka B u području dna 6, prolaze dakle bočne stijenke 7 koso ka površini 3, tada reflektiraju samo dio topline isijavanja, koja je bila na njih reflektirana s dna 6 natrag u udubljenje 5. To omogućava željenu apsorpciju toline isijavanja u kamenu za obzidavanje. If the section A of the opening is smaller than the section B in the area of the bottom 6, then the side walls 7 pass diagonally towards the surface 3, then they reflect only part of the radiant heat, which was reflected on them from the bottom 6 back into the recess 5. This enables the desired absorption of the cavity radiating in stone for walling.

Toplina, koju apsorbira kamen za obzidavanje na temelju opisanih refleksija topline isijavanja, se od gornjih površina 3 emitira u unutarnji prostor 4 peći. U cjelini se dakle od obzida, direktno u unutarnji prostor 4 peći reflektirano toplinsko isijavanje smanji i od kamena za obzidavanje emitirana toplina povećava. Time je omogućeno smanjenje temperature obzidavanja, jer se za taljenje stakla u unutarnjem prostoru 4 peći potreban udio topline emitira već kod niže temperature. The heat, which is absorbed by the masonry stone on the basis of the described radiant heat reflections, is emitted from the upper surfaces 3 into the inner space 4 of the furnace. As a whole, therefore, the thermal radiation reflected from the walls directly into the inner space of the furnace 4 decreases and the heat emitted from the masonry stone increases. This makes it possible to reduce the temperature of the walling, because for melting the glass in the inner space 4 of the furnace, the necessary part of the heat is already emitted at a lower temperature.

Kod kamena 1 za obzidavanje, predstavljenom na SI. 7, ima isto - drugačiji nego kod izvedbenog primjera prema Sl. 5 - samo na jednoj svojoj strani 10 izrez 2. Taj izrez tvori dno 6 i jednu od bočnih stijenki 7. Druga bočna stijenka 7 je načinjena na onoj strani 11 kamena 1 za obzidavanje, koji leži nasuprot strane 10. Bočna stijenka 7, koju tvori izrez 2, stoji pod oštrim kutom b glede dna 6. Prema toj bočnoj stijenki 7 prolazi s druge strane 11 načinjena bočna stijenka 7 paralelno. Udubljenje 5 je pri tom ograničeno s dnom 6 i jednom od bočnih stijenki kamena za obzidavanje i pomoću druge bočne stijenke 7 susjednog kamena 1 za obzidavanje. At stone 1 for walling, presented on SI. 7, has the same - different than in the embodiment according to Fig. 5 - only on one of its sides 10 cutout 2. This cutout forms the bottom 6 and one of the side walls 7. The other side wall 7 is made on the other side 11 of the walling stone 1, which lies opposite the side 10. The side wall 7, which is formed by cutout 2, stands at a sharp angle b with respect to the bottom 6. The side wall 7 made parallel to the side wall 7 passes on the other side 11. The recess 5 is limited by the bottom 6 and one of the side walls of the walling stone and by the other side wall 7 of the adjacent walling stone 1.

Izvedbeni primjer prema Sl. 8 je sličan onome sa Sl. 7. Ovdje tvore dno 6 i bočna stijenka 7 i izreza 2 tupi kut d. Tome odgovarajući bočna stijenka 7 strši ispred strane 11, koja leži nasuprot izrezu 2. Time je s jedne strane između dva susjedna kamena za obzidavanje postojeća dodirna reška 12 zatvorena naspram direktnog toplinskog isijavanja iz unutarnjeg prostora 4 peći. S druge strane je poboljšana veza kamena 1 za obzidavanje, jer se isti ne mogu bez slijedećeg pomicati pravokutno na površinu 3. An exemplary embodiment according to Fig. 8 is similar to that of Fig. 7. Here, the bottom 6 and the side wall 7 and the cut-out 2 form an obtuse angle d. The corresponding side wall 7 protrudes in front of the side 11, which lies opposite the cut-out 2. Thus, on the one hand, between the two adjacent masonry stones, the existing contact slot 12 is closed against of direct thermal radiation from the inner space of 4 furnaces. On the other hand, the connection of stone 1 for walling has been improved, because they cannot be moved perpendicularly to the surface 3 without the following.

Također kod izvedbenih primjera prema Sl. 7 i 8 se od dna 6 toplina isijavanja reflektira na jednu od bočnih stijenki 7. Osim toga se također iz unutarnjeg prostora 4 peći na jednu od bočnih stijenki 7 nailazeća toplina isijavanja reflektira na drugu bočnu stijenku 7 udubljenja 5. Also in the implementation examples according to Fig. 7 and 8, the radiant heat is reflected from the bottom 6 to one of the side walls 7. In addition, also from the inner space 4 of the oven to one of the side walls 7, the incoming radiant heat is reflected to the other side wall 7 of the recess 5.

Kod izvedbenih primjera prema Sl. 7 i 8 može biti presjek A otvora također veći od presjeka B u području dna 6, jer jedna od bočnih stijenki 7 sama toplinsko isijavanje reflektira na bočnu stijenku 7, koja leži nasuprot udubljenju 5. In the implementation examples according to Fig. 7 and 8, the section A of the opening can also be larger than the section B in the area of the bottom 6, because one of the side walls 7 itself reflects the thermal radiation to the side wall 7, which lies opposite the recess 5.

Prema Sl. 9 tvori jedna od bočnih stijenki 7 s površinom 3 kamena 1 za obzidavanje tupi kut, dok suprotno ležeće bočne stijenke 7' s površinom 3 tvori oštar kut. S time nastaje udubljenje 5. U njemu bočna stijenka 7 pomoću presjeka A otvora reflektira ulazeće toplinsko isijavanje na suprotno ležeću bočnu stijenku 7'. According to Fig. 9, one of the side walls 7 with the surface 3 of the masonry stone 1 forms an obtuse angle, while the opposite side walls 7' with the surface 3 form a sharp angle. This creates a recess 5. In it, the side wall 7 reflects the incoming thermal radiation onto the opposite side wall 7' by means of the section A of the opening.

Kod izvedbenog primjera prema Sl. 10 i 11 je udubljenje ograničeno s konkavno zakrivljenom stijenskom plohom 13. Ova ima u biti oblik šuplje kugle, pri čemu je presjek A otvora manji od najvećeg promjera udubljenja 5. Udubljenja 5 mogu biti oblikovana potpuno na kamenu 1 za obzidavanje. Nastati mogu također i time, da se dva kamena za obzidavanje međusobno sastave s odgovarajućim konkavnim izrezima (usporedi Sl. 10/11). In the implementation example according to Fig. 10 and 11, the recess is bounded by a concavely curved rock surface 13. This essentially has the shape of a hollow sphere, with the cross-section A of the opening being smaller than the largest diameter of the recess 5. The recesses 5 can be formed completely on the masonry stone 1. They can also be created by joining two masonry stones together with corresponding concave cutouts (compare Fig. 10/11).

Kod izvedbenog primjera prema Sl. 12 je udubljenje 5 oblikovano kao kanal, kojeg presjek je u biti kružni (usporedi Sl. 10). In the implementation example according to Fig. 12, the recess 5 is shaped like a channel, the section of which is essentially circular (compare Fig. 10).

Claims

1. Walling for a furnace, for example, for melting glass, wherein the walling has at least one depression, which forms side walls, which, by means of the section of the opening of the depression, reflect the radiant heat coming out of the furnace, characterized by the fact that the flat walls (6, 7, 7 ', 13) depressions (5) geometrically shaped in such a way, that from one rock surface (6, 7, 7', 13) the radiant heat is directed to the other rock surface (7, 7', 13) and thus the walling absorbs the heat.

2. Walling according to claim 1, characterized by the fact that the wall surface (13) of the recess (5) is concave, primarily circularly curved.

3. Walling according to claim 1, characterized in that the wall surfaces (6, 7, 13) of the recess (5) form at least one side wall (7, 7') and the bottom (6), whereby at least one side wall (7, 7') and the bottom (6) are at an angle to each other, which reflects the radiant heat reflected from the bottom (6) or the side wall (7) onto the side wall (7, 7').

4. Walling according to claim 3, characterized by the fact that the depression (5) is made by means of adjacent stones (8, 9) for walling, whereby the middle stone (9) for walling forms the bottom (6) and both other stones (8) for the walling consists of the side walls (7).

5. Walling according to claim 4, characterized by the fact that the middle stone (9) for walling and/or both other stones (8) for walling taper conically, so that the section A of the opening is smaller than the section B of the depression (5) in the area of the bottom (6).

6. Stone for lining the furnace, for example for glass melting, where the lining stone has at least one recess, which forms wall surfaces, which reflect the radiant heat coming out of the furnace through the section of the recess opening, indicated by the fact that the wall surfaces (6, 7 , 7', 13) recesses (5) face each other in such a way that the radiant heat reflected by one of the wall surfaces (6, 7, 13) encounters the other wall surface (7, 7', 13) and thus absorbs it stone (1) for walling.

7. A stone according to claim 6, characterized in that the side surface (13) of the depression (5) forms essentially a hollow sphere, wherein the section A of the opening is smaller than the maximum section of the hollow sphere.

8. Stone according to claim 6, characterized in that the side surfaces form at least two side walls (7, 7') and, in the given example, the bottom (6).

9. A stone according to claim 7 or 8, characterized in that the walling stone (1) has at least one cutout (2), which together with the cutout (2) of the adjacent walling stone (1) forms a recess (5).

10. A stone according to claim 8 or 9, characterized in that the section A of the opening of the recess (5) is smaller than the section B of the recess (5) in the area of the bottom (6).

11. Walling, or stone for walling according to one of the previous requirements, characterized by the fact that the bottom (6) runs concavely or convexly.

12. Walling, i.e. stone for walling according to one of the previous requirements, characterized by the fact that the side wall (7) and the part of the bottom (6), which is attached to it, are mutually at an obtuse angle b.

13. Walling, i.e. stone for walling according to one of the previous claims 1-11, characterized by the fact that the side wall (7) and the part of the bottom (6), which is attached to it, stand at an obtuse angle to each other (90 -And).

14. Walling, i.e. stone for walling according to one of the previous requirements, indicated by the fact that the side wall (7) stands at an obtuse angle c with respect to the section of the opening A of the recess (5).

15. A stone according to one of the previous claims, indicated by the fact that it has a cutout (2) on one of its sides (10), which forms the bottom (6) and one of the side walls (7) of the depression (5), and that its opposite the lying sides (11) form the second side wall (7).

16. A stone according to claim 15, characterized in that the side wall (7), which is formed by the cutout (2), stands at an acute angle b or an obtuse angle d with respect to the bottom (6), and that the side wall (7), which is on the opposite lying side (11), it stands essentially parallel to the first-mentioned side wall (7).