DESCRIPTION REVERSE SLANT LINING STRUCTURE OF FURNACE WITH REDUCED PART STRUCTURE Technical Field [0001] The present invention relates to a reverse slant lining structure for a furnace having a cone structure, such as a converter, an AOD furnace, a hot metal pretreatment furnace, and a torpedo car, inparticular, anovel improvementmadebyconstructinga reverse slant lining structure for a furnace having a cone part structure by laying lining bricks at the cone part on a reverse slant to thereby protect the bricks from cracking and attain stable operation. Background Art [0002] In general, a furnace having a cone part structure, such as a converter, adopts a horizontal lining structure in which bricks at the cone part are laid in parallel with lining bricks lined vertically to an iron shell of a straight barrel part, or has a slant lining structure in which lining bricks at the cone part are laid in such a manner that a center axis of each of the bricks in the thickness direction thereof is positioned on an obtuse angle side defined by a direction of an iron shell of the cone part and a direction vertical to the iron shell of the straight barrel part. In the horizontal lining structure, the lining bricks at the base of the cone part, that is, the bricks close to the straight barrel part side, may suffer cracks and fall off. This is triggered by 1 a factor that the lining bricks exposed to high temperature expand in the furnace receiving hot metal or molten steel, leading to an upward-thrusting stress generated from the furnace bottom to the furnace throat, and the stress concentrates on the lining bricks at the cone part. As a result, the life of the furnace is shortened. There has been proposed, as a method for solving this problem, the slant lining structure of the cone part. Structures related to the above-mentioned structures are disclosed in the following Patent Documents. [10003] First, Patent Documents 1 and 2 disclose a slant lining structure and a horizontal lining structure. Patent Document 3 discloses a slant lining structure in which bricks are laid vertically to an iron shell surface at the cone part. Patent Document 4 discloses a horizontal lining structure. Also, PatentDocument5disclosesahorizontalliningstructure, which is characterized in that bricks are laid in such a manner that an angle defined by an axial line of a furnace and a lining brick surface is smaller than an angle defined by the axial line and an iron shell at a cone part. Patent Document 6 discloses a structure related to an AOD furnace, and Patent Document 7 discloses a structure related to a torpedo car. [0004] Patent Document 1: Japanese Utility Model Application 2 Laid-open No. Sho 61-159357 Patent Document 2: JP 2003-231910 A Patent Document 3: Japanese Utility Model Application Laid-open No. Hei 03-067050 Patent Document 4: JP Hei 05-279719 A Patent Document 5: JP Hei 07-003321 A Patent Document 6: JP Hei 07-224316 A Patent Document 7: JP Hei 08-176634 A Disclosure of the Invention Problem to be solved by the Invention [0005] The conventional furnace having a cone part, such as a converter, has been constructed as described above, and therefore has involved the following problems. That is, the slant lining structure produces an effect of reducing stress as compared with the horizontal lining structure, however, the bricks may fall off during construction of the furnace, or the bricks may come out when the furnace is in use. Also, even if the furnace has been constructed as intended, during most of the time of operation of the furnace, the bricks laid on a slant are always under downward pressure due to the gravity force, and may fall off particularly in the end stage of operation when the bricks are reduced in thickness due to wear. Further, the inventors of the present invention has discovered based on studies that the slant lining structure may reduce stress which leads to cracks in the bricks, but the bricks at the cone part easily 3 generate a gap therebetween as compared with the horizontal lining. Means for solving the Problem [00061 A reverse slant lining structure for a furnace having a cone part structure according to the present invention includes a cone part structure of a furnace having a straight barrel part and a cone part, the cone part structure being characterized by including a structure obtained by laying lining bricks in such a manner that a center axis in the thickness direction of each of the lining bricks to be lined inside of the cone part is positioned on an acute angle side defined by an upside axis and perpendicular axis, said upside axis provided on an iron shell surface of the cone part and extending heightwise from the straight barrel part to the cone part along the iron shell, and said perpendicular axis provided perpendicular to the iron shell surface of the straight barrel part. Further, the center axis in the thickness direction forms a reverse slant angle from 5 to 30 degrees with the perpendicular axis. Further, the lining bricks laid at the cone part produce a smooth internal face of the furnace. Further, the furnace includes any one of a converter, an AOD furnace, a torpedo car, and a hot metal pretreatment furnace. Effects of the Invention [0007] The reverse lining structure for a furnace having a cone part structure according to the present invention is constructed as described above, and therefore is capable of producing the 4 following effects. That is, the lining bricks are laid on a reverse slant in a furnace having a cone structure, such as a converter, an AOD furnace, a hot metal pretreatment furnace, or a torpedo car, which prevents the bricks frombeingmisalignedor falling off during construction of the furnace, to thereby making it possible to construct the furnace with ease. Accordingly, there is produced an effect of significantly reducing construction time of the furnace. Also, according to the present invention, it is possible to protect the bricks from cracking by eliminating stress concentration due to expansion of the bricks when the furnace is in use. Further, it is possible to attain a stable operation because the bricks at the cone part do not generate a gap therebetween. Furthermore, it is not necessary to conduct repair work which has been conventionally conducted to deal with the cracking or the falling off of the bricks, eliminating the need of repairing material accordingly, thereby producing an effect of giving the furnace a significantly longer life. Brief Description of the Drawings [0008] [Fig. 1] Fig. 1 is a cross-sectional view of a main part showing a reverse slant lining structure for a furnace having a cone part structure according to the present invention. [Fig. 2] Fig. 2 is an enlarged cross-sectional view of the main part of Fig. 1. [Fig. 3] Fig. 3 is a cross-sectional view showing another 5 embodiment of Fig. 2. [Fig. 4] Fig. 4 is across-sectional viewshowing still another embodiment of Fig. 2. [Fig. 5] Fig. 5 is a cross-sectional view showing further another embodiment of Fig. 2. (Fig. 6] Fig. 6 is an enlarged cross-sectional view showing the raising brick of Fig. 1. [Fig. 7] Fig. 7 is a cross-sectional view showing another embodiment of Fig. 6. [Fig. 8] Fig. 8 is an overall block diagram showing how to determine a reverse slant angle of a reverse slant lining of a main part of Fig. 1. [Fig. 9] Fig. 9 is an enlarged view of a main part of Fig. 8. [Fig. 10] Fig. 10is a cross-sectionalview showinga structure of a torpedo car to which the structure of Fig. 1 is applied. Best Mode for carrying out the Invention [0009] It is an object of the present invention to provide a reverse slant lining structure for a furnace having a cone part structure, which is obtained by laying lining bricks of the furnace on a reverse slant, the reverse slant lining structure including a lining structure capable of preventing the bricks from being misaligned or falling off during the construction of the furnace making it easy to construct the furnace anda lining structure capable 6 of protecting the bricks from cracking by eliminating concentration of stress due to the expansion of the bricks when in use, and a lining structure in which the bricks at the cone part are closely spaced without generating a gap therebetween when the furnace is in use. Embodiment [0010] Hereinbelow, a preferred embodiment of a reverse slant lining structure for a furnace having a conepart structure according to the present invention is described with reference to the accompanying drawings. In general, a furnace 20 is constructedby laying bricks upward from a bottom 20a of the furnace 20. An example thereof is described with reference to Fig. 1. In Fig. 1, a permanent lining 2 and a wear resistant lining 3 are constructed inside of an iron shell 1. The permanent lining 2 may be formed of a refractory of finite form, such as a brick, or formed of a refractory of infinite form suchascastable, astampmaterial, orafillingmaterial. Meanwhile, the wear resistant lining 3 is formed of bricks of predetermined shape. The permanent lining 2 and the wear resistant lining 3 are constructed from a furnace bottom 4 of the furnace 20 which is in an upright position as shown in Fig. 1, so as to construct the furnace bottom 4, a lower corner part 5, and a straight barrel part 6 in the stated order from bottom to top. When the construction of the straight barrel part 6 is completed, a cone part 7 is started to 7 be constructed. The wear resistant lining 3 of the cone part 7 is constructed by laying bricks 7a according to the reverse slant lining structure of the present invention. Then, on top of the cone part 7, a furnace throat 8 is provided. [0011] The wear resistant lining 3 at the straight barrel part 6 is constructed of bricks which are laid horizontally, which makes it impossible to construct the cone part 7 immediately above the straight barrel part 6 by laying bricks on a reverse slant. For this reason, a lower raising brick 9 is used to construct the bottom part of the cone part 7. The lower raising brick 9 works as a bridge between the horizontal lining and the reverse slant lining, and as shown in Fig. 2, one or more lower raising bricks 9 are used to gradually change an angle of the horizontal lining to an angle of the reverse slant lining. The bricks are laid to provide the reverse slant lining towardthe top of the cone part 7. At the furnace throat 8, thebricks are again laidhorizontally, and an upper raising brick 10 is used to bring the bricks to come in contact with the iron shell 1 of the furnace throat 8. Fig. 1 shows an example in which only one upper raising brick 10 is used as the last one of the bricks, however, a plurality of raising bricks 10 may also be used. [0012] The lining bricks 7a constituting the wear resistant lining 3 which are laid on a reverse slant at the cone part 7 may be laid so as toproduceasmooth internal face 7aA (operation surface) 8 of the furnace and a back face 7aB as shown in Fig. 2, or may be laid in a staircase pattern as shown in Figs. 3 to 5. However, the corners of the stepped bricks are susceptible to cracking when the furnace is in use, and therefore, the construction of Fig. 2 is more preferable, in which the lining bricks 7a at the cone part 7 are laid without producing steps in the internal face 7aA of the furnace. [0013] A reverse slant angle of the reverse slant lining which is constituted by the lining bricks 7a and provided to the cone part 7 is determined as follows. In Figs. 8 and 9, when a center axis 14 in the thickness direction of each of the lining bricks 7a provided to the cone part 7 is positioned on an acute angle side 13 defined by a perpendicular axis 11 perpendicularly extending with respect to the iron shell 1 of the straight barrel part 6 toward the internal face 7aA of the furnace and an upside axis 12 extending heightwise along the iron shell 1 of the cone part 7, the bricks are laid on a reverse slant. On the other hand, when the center axis 14 of each of the lining bricks 7a in the thickness direction thereof is positioned on an obtuse angle side 15 of Fig. 9, the bricks are laidona slant. Areverse slant angle 16 which is defined by the center axis 14 and the perpendicular axis 11 of the brick 7a in the thickness direction thereof in Fig. 9 may be set to an arbitrary angle to produce an intended effect as long as the bricks are laid on a reverse slant. However, it is desirable to provide 9 the reverse slant angle 16 from 5 to 30 degrees. If the reverse slant angle 16 is less than 5 degrees, it reduces an effect of protecting the lining bricks 7a from cracking and closely spacing the lining bricks 7a without generating a gap therebetween, in contrast to the object of the present invention, and the lining bricks 7a may tend to fall off easily. If the reverse slant angle 16 is more than 30 degrees, it may be possible, for example, to provide a dowel (not shown) to one or both of the upper and lower faces of the lining bricks 7a in order to prevent the lining bricks 7a from falling off when the furnace is in operation. The constructionmethod of the present invention may be adopted to construct a converter, an AOD furnace, a torpedo car, a hot metal pretreatment furnace, or the like, which has a cone part, to thereby produce an effect. [0014] Next, Table 1 includes a first table which shows results of experiments performed by using a plurality of types of furnaces to which the reverse slant lining structure for a furnace having a contracting part structure according to the present invention is applied. 10 uO O O oa o 0 w 4r 0 0 Ln 0 4 4 -1 w - 0 0 a0) O1 E 1 44(f U 1) H 12 4-) H r l H 0 0 D 0 0 0 0 1) O C n LD O0 o Ino-o E-12 423 12) o) a) ) 0" 00n C N r m a)) n M 2)C o4J 41 a)0 - 4) F: 0 I n L, w Ln N 4 N0 0 r-2) u uW Q m 4-) M O to- Co ciyo r, 0 r. OI o4 L Oo O4 12) a) a) 0 V H) 0 12) V V a) a) w u 0) C 12) o 0E.0 12 U) V (L1) w2 12) I - 0n N) 4If 0 04 0W r/ a) O -) 0 y >10) 0. 0 U) -. U)O U n t ~D Qr2 cN C , -dU c 0 A OiX , ou w 1) V 4-1 12) WH j a N4 12 ) 0 42 0AN 4 4 C 4 C - 0- * 0 0 0 0 V r) En V) 12) X2 u 4 m 0 00 C 0 E 0 (L) 0) IA 4 N 0 0 C) 0 0 >N H 0 0 0 0 V) tp W12))a) W 4 )W 4 ( 4 a VN W 4-4 4-' .4 1 o- 12)o 4 ow Na Inw N1 N1 4-' 4-1 44 U 1W U H 0 4 0a 01 <D 040wW oa 0 O4 14I UInEn I r 0) - -j - -,g _ CZ4 0 a) 0 r. c N 4-4 W 4 ~ 0 U '4-4W W 4 )N H44 J H j 44- 4-) 1012 04 ,l u -W'~ 0 4-1 W - 0 u 0 W tp j~jH w-1J- m~ a)2 : V 04 En' (I) 0 (a )41U1 In 4 )WWl D -4 w . i -4 : 0 m0WNz 0W . (D N H Q w- )- H- w) w0~ W.4c -f M~, U~ 0~ INMZI 0 )(0 D 0 ::12) U I W 4 J 0 : -0 M (D 4 - 4 H 0n H U J J W4-) M W 4-) a)A u a 1) 4 -1 )4- * -W 4--4 Ct nQ 0 0 C) VW0 0 OD a) 0 :s a) E E )0 a) c4-) C\) 0 ) J 1 ( *00a a) a) 41) .4 41 a) a) 4 4-) V) a) a)0. 0 a)a) a) 1::4-) 4-) 0 LnU) V) .- 4a)4-) U a) a) 4-) ~ M W . 04 0 0 (D (Dr 0W'p( 0 co a:1-4 4 a 4-) a) V) -0 u a) a) C:4 ~ 0 N) 0 .. '0 ,a a) 4 C co n.c 0 0 L o 0 14~ 0 0 0 H E0U) U a)) U) a) a) -44 m N 0 1 0'a a )4 a) 4-) 4-) 4-) a o0a 0 0 Ln C) C rN 1 a riw C - 0 0 0 C r.. -o F.4 V) 0r 4N0 0 N -4 C 14 q.N 0 r 0 U ro 0. j W ~ - 0 0 U-) CD w0 0 m 0 0 a)r a) ) 1-4 4-) (D I- N -40 0 0' C -4 a) 0 0 0 LO ) V) ty'a) 0 0a) a) -- I 4 (Da a) 41 a4.) 4) 440a) 44a) F.04.4-) 4.0.0 rav~ (a4. 0u 00a l -41 41-4 ~ a) 4 = 0 04 a) 0 ) 4 , 0 (!' a (o a ,10 4 V) En 4 4' -4 4 j 0.- l~ u 44U ma aa 0) 0 O 0 H U ~ ~ r C: 4-- H)' 0 4)~ ) 4) U a0 . ) H ) 4-4 U (DH 0.-4 4( U M)~0 O 4-0a .' ) U 4 0 a-) U( i U4) a)-4 4)-- a)H U -4 4-) 0 ) a) . - 4-jO .O O a) - 0 a)0a . r..C wV -4. en Vn 4.j C... (a IL ~ C. t,,, - . 1 [0016] In the first table, the conepart construction time ratio is obtained by dividing the time needed to make preparations and built the furnace according to the technology of the present invention by the time needed to make preparations and built the same furnace by laying bricks on a slant as a comparative example. With the ratio of 100 indicating that the present invention is equal to the comparative example, the smaller numericvalue of the ratio indicates the shorter construction time which is preferable. In the first table, the degree of breakdown of the bricks due to cracking at the construction part is obtained by dividing the rate of breakdown (mm/ch) of the bricks resulting from cracking when the furnace is constructed according to the technology of the present invention by the rate of breakdown of the bricks resulting from cracking when the same furnace is constructed by laying bricks onaslantasacomparativeexample. Withthedegreeofl00indicating that the present invention is equal to the comparative example, the smaller numeric value of the ratio indicates the smaller rate of breakdown which is preferable. Further, the degree of falling off of the bricks at the cone part is obtained by dividing the number of bricks that have fallen off from the cone part of the furnace, during one generation thereof, which is constructed according to the technology of the present invention by the number of bricks that have fallen off from the cone part of the same furnace, during one generation thereof, which 13 is constructed by laying bricks on a slant as a comparative example. With the degree of 100 indicating that the present invention is equal to the comparative example, the smaller numeric value of the ratio indicates the smaller rate of breakdown, which is preferable. Accordingly, as understood from the first table, any of the embodiments of the present invention is superior to the corresponding comparative examples. Industrial Applicability [0017] The reverse slant lining structure for a furnace having a cone part according to the present invention is applicable to any furnace in which the lining bricks are used. It shouldbenotedthat Fig. 10isacross-sectionalviewshowing a construction obtained by applying the present invention to the lining of a torpedo car 30. The members similar to those of Fig. 1 are denoted by the same reference numerals, and the description thereof is omitted. 14