[go: up one dir, main page]

US3881878A - Large-sized and large thickness composite sleeves - Google Patents

Large-sized and large thickness composite sleeves Download PDF

Info

Publication number
US3881878A
US3881878A US452269A US45226974A US3881878A US 3881878 A US3881878 A US 3881878A US 452269 A US452269 A US 452269A US 45226974 A US45226974 A US 45226974A US 3881878 A US3881878 A US 3881878A
Authority
US
United States
Prior art keywords
weight percent
thickness
sleeves
layer
inner layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US452269A
Other languages
English (en)
Inventor
Kenzi Maruta
Atsushi Yamada
Tsunemi Tsuji
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Proterial Ltd
Original Assignee
Hitachi Metals Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Metals Ltd filed Critical Hitachi Metals Ltd
Application granted granted Critical
Publication of US3881878A publication Critical patent/US3881878A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/922—Static electricity metal bleed-off metallic stock
    • Y10S428/923—Physical dimension
    • Y10S428/924—Composite
    • Y10S428/925—Relative dimension specified
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12951—Fe-base component
    • Y10T428/12958—Next to Fe-base component
    • Y10T428/12965—Both containing 0.01-1.7% carbon [i.e., steel]

Definitions

  • Appl' 452'269 comprises an outer layer of high carbon cast alloy steel having a carbon content in a range between 1.6 [30] Foreign Application Priority Data and 2.2 percent by weight and a Shore hardness num- Mar. 30, 1973 Japan 48-35681 b of over and an inner layer Of cast Steel of high carbon content in which crystallization of graphite has 52 us. (:1 29/191; 29/1961; 308/237 R taken place and which has a Shore hardness number 51 1111.
  • This invention relates to large-sized and large thickness composite sleeves adapted for use with horizontal rolls and vertical rolls of the assembly type for a universal rolling mill for producing l-I-shaped beams which has mounted on the shaft large-sized sleeves having a small width relative to the diameter.
  • Rolls of the assembly type have been widely in use because the shaft can be used again by replacing one sleeve by another one and the rolls of the assembly type are low in roll cost, so that they are more economical than rolls of the solid type.
  • l-leretofore it has been customary to use sleeves of cast steel of medium carbon content having a Shore hardness number of below 50 for rolls of the asembly type of a universal rolling mill for producing l-l-shaped beams.
  • Some disadvantages are associated with such sleeves. Wear is caused on the lateral surface of each sleeve, scars are formed in the flange by striking, and the sleeve is unable to withstand pressure applied by folding of the metal to be rolled or form other reasons.
  • the sleeves should be tough and devoid of the possibilities of fractures
  • the sleeves should be highly resistant to wear and should not produce surface roughness
  • the sleeves should be highly resistant to crack formation when heated.
  • the sleeves should be deep hardening or low in the reduction of internal hardness when the range of diameters for effective use is great.
  • sleeves of the composite type each comprising outer and inner layers of equal thickness made of dissimilar materials. More specifically, such sleeves would consist of an effective surface layer or outer layer made of a high hardness alloy or high carbon content alloy which is highly resistant to wear, production of surface roughness and crack formation upon heating and which is highly deep hardening, and an inner layer made of a soft and ductile material of low hardness which is so tough that it does not fail when subjected to a shrinkage fitting stress during production or when rolling and thermal stresses are simultaneously applied to the sleeve in service, and which has a reduced internal residual stress.
  • Composite sleeves of the prior art have hitherto been produced by casting two types of metals by using the fixed mold provided with a partition of an steel plate, or by first casting a molten melt for the outer layer and replacing the inner portion of the poured molten metal by another molten metal for the inner layer after the outer layer has solidified a predetermined distance from the surface.
  • the former has disadvantages in that the outer and inner layers are sometimes not welded together properly, hot top has little effect because the outer and inner layers are separated by the partition, and degasing of the poured molten metals is not effected properly.
  • a pipe of small thickness formed in two layers and made of a ferrous or non-ferrous material can readily be produced by centrifugal casting and the two layers form well-defined concentric circular areas because the pipe has a small thickness and the outer and inner layers quickly solidity. Since such pipe is not subjected to a high load both mechanically and thermally as is the case with rolls, there is no technical problem to be obviated in producing such pipe.
  • a sleeve in which the thicknesses of the outer and inner layers are not proper has the possibilities of failures during production or in service.
  • This invention has as its object the provision of ideal large-sized and large thickness composite sleeves having predetermined properties and adapted for use with rolls of the assembly type for producing H-steels, such composite sleeves being produced by centrifugal casting and obviating the aforementioned disadvantages of the prior art.
  • composite sleeves produced by centrifugal casting and each having an outer diameter of over 900 millimeters, such composite sleeves each comprising an outer layer of high carbon alloy steel having a carbon content in a range between L6 and 2.2 by weight and a Shore hardness number of over 55, and an inner layer of high carbon cast steel in which crystallization of graphite has taken place and which has a Shore hardness number in a range between 35 and 42.
  • large-sized and large thickness composite sleeves of the type described in which the ratio of the thickness of the outer layer to that of the inner layer is in a range between 0.5 and 2.6.
  • FIG. I is a front view of a composite sleeve according to the present invention.
  • FIG. 2 is a vertical sectional view of the composite sleeve shown in FIG. 1;
  • FIG. 3 is a diagram showing hardness penetration in internal hardness.
  • FIG. I shows the construction of a composite sleeve of large thickness adapted for use with a horizontal roll of large thickness and small width of the assembly type used with a universal rolling mill for producing H-shaped beams.
  • the sleeve comprises an outer layer 1 of large thickness made of high carbon alloy steel, an inner layer 2 made of tough high carbon cast steel in which crystallization of graphite has taken place and which has a low Shore hardness number, and a boundary layer 3 consisting of a mixture of the materials for the outer and inner layers 1 and 2. 4 designates a shrinkage fitting surface.
  • Large-sized and large thickness composite sleeves of over 900 millimeters in diameter in which the ratio of the thickness t to the outer diameter D of t/D is in a range between 0.20 and 0.40 are produced as follows.
  • a predetermined quantity of molten alloy steel of high carbon content is poured into a metallic mold for centrifugal casting rotating at high speed on a horizontal centrifugal casting apparatus to form the outer layer 1 which will have a Shore hardness number of over 55 and a carbon content in a range between 1.6 and 2.2 percent after the casting is produced.
  • a predetermined quantity of molten metal of high carbon content for the inner layer in which crystallization of graphite can be made to take place upon solidification is poured into the mold in such a manner that the ratio 21 of the outer layer 1 to the thickness of :2 of the inner layer 2 or tl/t2 will be in a range between 0.50 and 2.6 and the Shore hardness number of the inner layer 2 will be in a range between 35 and 42 after the casting is produced.
  • the reason why the diameter of the sleeves according to the invention is limited over 900 millimeters and the ratio of the thickness t to the outer diameter t or t/D is limited to a range between 0.20 and 0.40 is as follows.
  • the object of the invention is to provide large-sized and large thickness composite sleeves of over 900 millimeters in outer diameter.
  • the ratio t/D is below 0.20, there is no problem to be obviated because cooling of the sleeves takes place relatively quickly.
  • the lower limit of the ratio t/D is set at 0.20.
  • the ratio t/D is over 0.40, the casting has an inordinately large thickness and is not therefore generally referred to as a sleeve.
  • the carbon content of the alloy steel for the outer layer 1 is limited to a range between 1.6 and 2.2 percent by weight according to the invention because, if the carbon content exceeds 2.2 percent, then the material is brittle and surface cracks formation tends to occur when subjected to a heat treatment, and, if the carbon content is below 1.6 percent by weight, then hot rolling causes wear and seizure to occur in the sleeves.
  • the ratio of the thickness :1 of the outer layer 1 to the thickness 22 of the inner layer 2 or t/t2 of the sleeves according to the invention is limited to a range between 0.50 and 2.6 because of the following reason.
  • a portion of the inner surface of the outer layer 1 should be melted again after solidification by the molten metal for the inner layer 2 and allowed to solidify again.
  • the quantity of the molten metal for the inner layer 2 should be such that the ratio tl/t2 does not exceed 2.6 so that the molten metal for the inner layer has a thermal capacity which is high relative to the volume of the outer layer 1, whereby a portion (having a thickness between 15 and 20 millimeters) of the inner surface of the outer layer can be melted again immediately before completion of solidification. If the ratio tl/t2 is below 0.5, then the thickness of the outer layer 1 is extremely small as compared with the thickness of the inner layer 2.
  • the thermal capacity of the molten metal for the inner layer 2 is excessively high relative to the volume of the outer layer 1, with the result that the inner surface of the outer layer 1 is too readily melted again and diffused to enable the outer layer 1 to have a predetermined thickness and to permit the boundary layer 3 to be formed in the form of a circle free from eccentricity.
  • the Shore hardness number of the outer layer 1 should be over 55 is because the sleeves should be sufficiently hard to be resistant to wear and the production of surface roughness. If the Shore hardness number of the inner layer 2 exceeds 42, then the sleeves become exceedingly brittle, thereby producing the possibilities of failures during production and in service. If the Shore hardness number of the sleeves is below 35, then the shrinkage fitting surface of the sleeves lacks rigidity after shrinkage fitting is effected and assembling is effected, thereby posing the problem of slipping of the sleeves. To obviate this problem, therefore, the Shore hardness number of the inner layer 2 is limited to a range between 35 and 42 in which crystallization of spherical graphite form tends to occur. It
  • the hardness of the inner layer 2 5 h h sleeves d d are f f fl Th is elQSetY related t range between and of the Shore hardness number of the surface of the sleeves ratio 11/12 and that the Shore hardness number of the was between 50 and 61 hfl the Shore hardness ihhel layer 2 is Preferably in the neighborhood of 35 at ber of the inner surface was between 38 and 41.
  • the which the steel is high in toughness and crystallization higmy deep hardness of the sleeves was as shown in of spherical graphite form takes Place a yto FIG. 3.
  • the ratio l/D was 0.25 and the A 9 51.6mm aforemenuoned, a ratio t1/t2 was 2.5, which are in the predetermined meetlng the requirements is sub ected to homogenizing ranges and spherodizing when considered necessary.
  • Table 2 is cut into sleeves of a smaller size which are subjected to heat :eatment, quenchmg and tempering Layer Tensile Strength Ductility Charby Impact that the final products or sleeves can be produced in (kg/mm!) Test (kgmlcmz) which the ratio 21/22 is in a range between 0.5 and 2.6. 25
  • the final products are mounted on shafts by shrink- 3 2:: 33 age fitting.
  • Table 1 shows the chemical composition of metals rolling in one operation, as compared with the H- used for producing a composite sleeve for a horizontal shaped beams of 1,000 tons produced by rolling in one roughing roll which has an outer diameter of 1,390 operation by conventionaal rolls having a Shore hardmillimeters, an inner diameter of 650 millimeters and 35 ness number b l 50, a total length of L600 millimeters, and in which re- The amount of wear caused on the side wall was bequired thickness of the outer layer is over 245 millimetween 0.15 and 0.20 millimeter for one operation ters.
  • the metal for the inner layer kept at l500C was poured sleeves according to the invention have no possibilities into the metallic mold again. Rotation of the mold was of fractures, and can have a service life about twice as interrupted when solidification of the molten metals ng as that Of sleeves of the prior art. The use of the was completed in about 5 hours. sleeves according to the invention is economical be-
  • the outer layer had a particularly large thickness and cause the cost of material required for the rolls is low. was made of high carbon alloy steel which is brittle if What is claimed is: not subjected to some treatment after being produced l. A large-size and large thickness composite sleeve by casting in a mold.
  • the casting was reproduced by centrifugal casting and having a diameter moved from the metallic mold while being maintained of over 900 millimeters, said composite sleeve comprisat a temperature of over 600C and subjected to hoing an outer layer of high carbon cast alloy steel having mogenizing and spherodizing. Thereafter, the casting a carbon content of about 1.6 to 2.2 percent by weight was cut into smaller pieces by turning, each piece having a required width. After each sleeve was subjected to rough working, it was quenched and tempered.
  • each sleeve was worked to have predetermined and a Shore hardness of over 55, and an inner layer of high carbon cast steel in which crystallization of graph ite has taken place, said inner layer having a Shore hardness of about 35 to 42, the ratio of the thickness of said outer layer to the thickness of said inner layer being about 0.5 to 2.6.
  • a large-size and large thickness composite sleeve produced by centrifugal casting and having an outer diameter of over 900 millimeters and a sleeve thickness to outer diameter ratio (t/D) of from 0.2 to 0.4, said composite sleeve comprising an outer layer of high carbon cast alloy steel having a carbon content of about 1.6 to 2.2 percent by weight and a Shore hardness of over 55, and an inner layer of high carbon cast steel in which crystallization of graphite has taken place, said inner layer having a Shore hardness of about 35 to 42, the ratio of the thickness of said outer layer to the thickness of said inner layer being about 0.5 to 2.6.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
  • Rolls And Other Rotary Bodies (AREA)
US452269A 1973-03-30 1974-03-18 Large-sized and large thickness composite sleeves Expired - Lifetime US3881878A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3568173A JPS5613539B2 (pt) 1973-03-30 1973-03-30

Publications (1)

Publication Number Publication Date
US3881878A true US3881878A (en) 1975-05-06

Family

ID=12448616

Family Applications (1)

Application Number Title Priority Date Filing Date
US452269A Expired - Lifetime US3881878A (en) 1973-03-30 1974-03-18 Large-sized and large thickness composite sleeves

Country Status (7)

Country Link
US (1) US3881878A (pt)
JP (1) JPS5613539B2 (pt)
AU (1) AU462312B2 (pt)
BR (1) BR7402473D0 (pt)
CA (1) CA994507A (pt)
DE (1) DE2415044C2 (pt)
GB (1) GB1450303A (pt)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0154196A1 (en) * 1984-02-24 1985-09-11 Mazda Motor Corporation Process for forming a wear-resistant layer on a substrate
US20110150998A1 (en) * 2009-12-22 2011-06-23 Laura-Lee Farrell Methods For Producing ECM-Based Biomaterials
US20130087645A1 (en) * 2010-06-18 2013-04-11 Meinhard Frangenberg Profiled Binding For A Roller Press
CN103350206A (zh) * 2013-06-07 2013-10-16 马鞍山市恒毅机械制造有限公司 压力油缸复合离心铸造的方法
CN103350204A (zh) * 2013-06-07 2013-10-16 马鞍山市恒毅机械制造有限公司 密封环复合离心铸造的方法
CN109403771A (zh) * 2017-08-17 2019-03-01 大同金属工业株式会社 车辆用滑动门的导向辊

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS55122661A (en) * 1979-03-15 1980-09-20 Sumitomo Metal Ind Ltd Steel ingot for rolled wheel and production thereof
FR2464741A1 (fr) * 1979-09-07 1981-03-20 Usinor Cylindre composite de compactage
JPS5736058A (ja) * 1980-08-12 1982-02-26 Kubota Ltd Fukugoenbanjorooranoseizoho
JPS6021003B2 (ja) * 1980-12-15 1985-05-24 株式会社クボタ Ｈ型鋼圧延用複合スリ−ブロ−ル及びその製造法
JPS5855552A (ja) * 1981-09-29 1983-04-01 Kubota Ltd Ｈ型鋼圧延用複合スリ−ブ及びその製造方法
US4546527A (en) * 1981-12-01 1985-10-15 Kubota Ltd. Composite sleeve for use in rolling rolls for H-section steel and channel steel
JPS5923845A (ja) * 1982-07-31 1984-02-07 Kubota Ltd Ｈ型鋼圧延ロ−ル用スリ−ブ
JPS5924568A (ja) * 1982-07-31 1984-02-08 Kubota Ltd Ｈ型鋼圧延用ロ−ル
JPH0669577B2 (ja) * 1987-05-22 1994-09-07 川崎製鉄株式会社 圧延ロール用複合スリーブ及びその製造方法
DE3720832A1 (de) * 1987-06-24 1989-01-05 Voith Gmbh J M Gegossener walzenmantel, insbesondere press- oder kalanderwalze zur behandlung bahnfoermigen gutes, sowie verfahren und vorrichtung zu seiner herstellung
FR2625226B1 (fr) * 1987-12-23 1990-06-08 Chavanne Ketin Cylindre de travail composite bimetallique
DE3814433A1 (de) * 1988-04-28 1989-11-09 Krupp Polysius Ag Walzenmuehle sowie verfahren zur beschichtung einer walze
CN111589874B (zh) * 2020-05-27 2022-05-20 陈歌 一种用环保方式制造的组合轧辊及其制造方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2710997A (en) * 1952-06-13 1955-06-21 Campbell Wyant & Cannon Co Method of producing bimetal castings
US2964251A (en) * 1956-09-21 1960-12-13 United States Pipe Foundry Roll structure
US3014266A (en) * 1956-09-21 1961-12-26 United States Pipe Foundry Method for making and repairing rolls
US3416435A (en) * 1966-06-13 1968-12-17 Beloit Corp Roller press

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE657579C (de) * 1931-11-26 1938-03-08 Gontermann Peipers Akt Ges Fue Gusseisen fuer Verbundhartgusswalzen

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2710997A (en) * 1952-06-13 1955-06-21 Campbell Wyant & Cannon Co Method of producing bimetal castings
US2964251A (en) * 1956-09-21 1960-12-13 United States Pipe Foundry Roll structure
US3014266A (en) * 1956-09-21 1961-12-26 United States Pipe Foundry Method for making and repairing rolls
US3416435A (en) * 1966-06-13 1968-12-17 Beloit Corp Roller press

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0154196A1 (en) * 1984-02-24 1985-09-11 Mazda Motor Corporation Process for forming a wear-resistant layer on a substrate
US20110150998A1 (en) * 2009-12-22 2011-06-23 Laura-Lee Farrell Methods For Producing ECM-Based Biomaterials
US8329219B2 (en) 2009-12-22 2012-12-11 Cook Biotech Incorporated Methods for producing ECM-based biomaterials
US8784890B2 (en) 2009-12-22 2014-07-22 Cook Medical Technologies Llc Methods for producing ECM-based biomaterials
US20130087645A1 (en) * 2010-06-18 2013-04-11 Meinhard Frangenberg Profiled Binding For A Roller Press
US9180516B2 (en) * 2010-06-18 2015-11-10 Khd Humboldt Wedag Gmbh Roller press bimetallic annular casing
US9586260B2 (en) 2010-06-18 2017-03-07 Khd Humboldt Wedag Gmbh Process for producing a casing for a roller press
CN103350206A (zh) * 2013-06-07 2013-10-16 马鞍山市恒毅机械制造有限公司 压力油缸复合离心铸造的方法
CN103350204A (zh) * 2013-06-07 2013-10-16 马鞍山市恒毅机械制造有限公司 密封环复合离心铸造的方法
CN109403771A (zh) * 2017-08-17 2019-03-01 大同金属工业株式会社 车辆用滑动门的导向辊
CN109403771B (zh) * 2017-08-17 2020-09-25 大同金属工业株式会社 车辆用滑动门的导向辊

Also Published As

Publication number Publication date
DE2415044C2 (de) 1985-07-11
GB1450303A (en) 1976-09-22
DE2415044A1 (de) 1974-10-24
CA994507A (en) 1976-08-10
JPS49123158A (pt) 1974-11-25
JPS5613539B2 (pt) 1981-03-28
BR7402473D0 (pt) 1974-12-03
AU462312B2 (en) 1975-06-19
AU6713074A (en) 1975-06-19

Similar Documents

Publication Publication Date Title
US3881878A (en) Large-sized and large thickness composite sleeves
US3894325A (en) Large-sized and thick compound sleeves of high hardness
EP0430241B1 (en) Wear-resistant compound roll
JP6948556B2 (ja) 遠心鋳造製熱間圧延用複合ロールの製造方法
CA2228488C (en) Roll for hot rolling having enhanced abrasion resistance and reduced carbide segregation
US3659323A (en) A method of producing compound cast rolls
JPH02258949A (ja) 耐摩耗複合ロール
US2964251A (en) Roll structure
US3670800A (en) Casting process for rolls
KR100612491B1 (ko) 액체 플러스 액체 이중원심주조 프로세스를 이용하여제조된 연주가이드 롤 및 이를 이용하여 제조된 이송트랜스 롤
JPH04319059A (ja) 超硬合金と鋳鉄からなるロール及びその製造方法
JPH0699776B2 (ja) 複合ロールリング
JP2601746B2 (ja) 遠心鋳造製スリーブロールとその製造方法
CN111893374B (zh) 一种含石墨的贝氏体半钢精轧辊环
JPH0680176B2 (ja) 熱間圧延用作業ロールの製造法
JPS6320627B2 (pt)
JP3729178B2 (ja) 冷間圧延用遠心鋳造製複合ワークロール
JPS61144216A (ja) アルミニウムおよびアルミニウム合金熱間押出プレス用金型の製造方法
US2171229A (en) Process for manufacturing cast bearings from light metal alloys
US3890167A (en) Method and apparatus for producing a casting having a satisfactory surface with a continuous casting operation
JPH0340102B2 (pt)
JPS646842B2 (pt)
TWI469835B (zh) Centrifugal casting legal compound roll and its manufacturing method
CN116586897A (zh) 一种铝合金铸锭缺陷修复方法及一种铝合金铸锭
JPS58110168A (ja) 異種金属を軸方向において接合した軸状鋳物のその接合部鋳造法