JP2009066644A - Piercer boring method of hard-to-work material - Google Patents
Piercer boring method of hard-to-work material Download PDFInfo
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本発明は、難加工性材料ピアサー穿孔時の内面疵発生を防止する難加工性材料のピアサー穿孔方法に関するものである。 The present invention relates to a piercer drilling method for difficult-to-work materials that prevents the occurrence of internal flaws at the time of piercing difficult-to-work material.
従来、ピアサー・ミルで難加工性材料を圧延する際には、丸鋼片を穿孔して得た素管にヒダ状剥離膨れ欠陥や内面疵の発生することが多い。従って、これらのヒダ状剥離膨れ欠陥や内面疵の発生を防止するため、ステンレス鋼管については、穿孔速度を低減し、さらに穿孔温度を低減するなど、穿孔速度及び穿孔温度を規制した穿孔可能範囲が示されている。 Conventionally, when a difficult-to-work material is rolled by a Piercer mill, a pleated delamination defect and internal flaws often occur in an element tube obtained by drilling a round steel piece. Therefore, in order to prevent the occurrence of these fold-like delamination defects and inner surface flaws, the stainless steel pipe has a drillable range in which the drilling speed and the drilling temperature are regulated, such as reducing the drilling speed and further reducing the drilling temperature. It is shown.
また、上記ステンレス鋼以外の難加工性材料においても、ステンレス鋼より変形抵抗は低いが、オーバーヒート温度がステンレス鋼より低いため、従来の穿孔条件ではヒダ状欠陥や内面疵が発生する。さらに、オーバーヒートを避けるために、ビレット加熱温度を下げ過ぎるとピアサー・ミルに咬み込まないので穿孔ができない。そこで、適切なビレット加熱温度および穿孔速度を決定してオーバーヒートを防止する必要がある。 Further, in difficult-to-work materials other than the stainless steel, the deformation resistance is lower than that of the stainless steel, but since the overheat temperature is lower than that of the stainless steel, a pleated defect and an inner surface flaw are generated under the conventional drilling conditions. Furthermore, in order to avoid overheating, if the billet heating temperature is lowered too much, it will not bite into the piercer mill, and so drilling will not be possible. Therefore, it is necessary to determine an appropriate billet heating temperature and perforation speed to prevent overheating.
このように、難加工性材料ではピアサー・ミル穿孔時に加工発熱によってオーバーヒートを起こしやすいことが問題である。オーバーヒートによって素管中間部に欠陥が発生し、エロンゲーターミルで欠陥を延伸させ、サイジング・ミルでヒダ状剥離欠陥になる。従って、ヒダ状剥離欠陥や内面疵の発生をなくすには、オーバーヒートを防止するようにピアサー・ミルにより穿孔しなければならない。また、オーバーヒートを防止して穿孔するためには、ビレット加熱温度、搬送時のビレット温度低下、穿孔時間、および穿孔速度を考慮して最適穿孔条件を決定する必要がある。 As described above, it is a problem that difficult-to-process materials are likely to overheat due to processing heat generation during piercer mill drilling. Overheating causes a defect in the intermediate portion of the tube, and the defect is stretched by an elongator mill, and becomes a flaking-like peeling defect by a sizing mill. Therefore, in order to eliminate the occurrence of fold-like peeling defects and internal flaws, it is necessary to perforate with a piercer mill so as to prevent overheating. In addition, in order to prevent overheating and perform drilling, it is necessary to determine the optimum drilling conditions in consideration of billet heating temperature, billet temperature decrease during conveyance, drilling time, and drilling speed.
そこで、ピアサー・ミルで継目無管用管材に穿孔するに際し、オーバーヒートに起因する管内面ヒダ状剥離欠陥を生じさせない継目無管の製造方法として、例えば特開2000−301212号公報(特許文献1)に開示さているように、穿孔速度とビレット加熱温度との関係式を満たすビレット温度、圧延速度で難加工性材料を穿孔する管内面ヒダ状剥離膨れ欠陥を防止する難加工性材料の継目無管のピアサー穿孔方法が提案されている。
しかしながら、特許文献1での特許対象範囲から外れる難加工性材料が存在し、それらの難加工性材料については内面疵発生を防止することができないという問題がある。 However, there are problems in that there are difficult-to-work materials that are out of the scope of patents in Patent Document 1, and these difficult-to-work materials cannot prevent the occurrence of internal flaws.
上述したような問題を解消するために、発明者らは鋭意開発を進めた結果、穿孔前材料温度ないしは穿孔直後材料温度、穿孔速度を制御することにより、穿孔時の材料温度がオーバーヒート温度に到達するのを防止することにより、オーバーヒートによる内面疵を防止することが出来る難加工性材料のピアサー穿孔方法を提供する。 In order to solve the above-mentioned problems, the inventors have made extensive developments. As a result, the material temperature at the time of drilling reaches the overheat temperature by controlling the material temperature before drilling, the material temperature immediately after drilling, or the drilling speed. By providing this method, there is provided a method for piercing a piercer of a difficult-to-work material capable of preventing internal flaws due to overheating.
その発明の要旨とするところは、
(1)難加工性材料をピアサーミルで圧延穿孔し継目無鋼管を製造する方法において、材料温度に対する熱間変形抵抗(σ[MPa])との関係式(1)式で表され難加工性材料をピアサー穿孔するに当たり、穿孔直前材料温度(T[K])と穿孔中の材料先進速度(V[mm/s])との関係式(2)を満たすように設定することにより、穿孔中のオーバーヒートによる内面疵発生を防止することを特徴とする難加工性材料のピアサー穿孔方法。σ[MPa]=A×exp(D/T[K])×(dε/dt)m … (1)
T[K]+(1+0.002V[mm/sec])×K(T)<T0 [K]… (2)
但し、A:0〜1
D:実験で得られた鋼種によって決まる値を示す
m:歪み速度感受性指数、鋼種によって決まる値
V:ピアサー穿孔速度(m/sec)
K(T):鋼種、温度によって決まる値
T0 :オーバーヒート温度[K]であって、グリーブル試験で試験温度を上げたとき に、絞り値が最大値に対して5%低下するときの温度
(2)前記(1)に記載の穿孔直前材料温度(T[K])と穿孔直後材料温度(T´[K])との間には式(3)の関係があり、穿孔直後材料温度(T´[K])をオーバーヒート温度(T0 )より低くすることを特徴とする難加工性材料のピアサー穿孔方法にある。T´[K]≒T[K]+(1+0.002V[mm/sec])×K(T)…(3)
The gist of the invention is that
(1) In a method of producing a seamless steel pipe by rolling and drilling a difficult-to-work material with a Piercer mill, the difficult-to-work material represented by the relational expression (1) with the hot deformation resistance (σ [MPa]) with respect to the material temperature Is set so as to satisfy the relational expression (2) between the material temperature immediately before drilling (T [K]) and the material advanced speed during drilling (V [mm / s]). A method for piercing a piercer of a difficult-to-work material, characterized by preventing generation of internal flaws due to overheating. σ [MPa] = A × exp (D / T [K]) × (dε / dt) m (1)
T [K] + (1 + 0.002V [mm / sec]) × K (T) <T 0 [K] (2)
However, A: 0 to 1
D: A value determined by the steel type obtained in the experiment m: Strain rate sensitivity index, a value determined by the steel type V: Piercer drilling speed (m / sec)
K (T): Value determined by steel type and temperature T 0 : Overheat temperature [K], the temperature at which the aperture value decreases by 5% of the maximum value when the test temperature is raised in the greeble test ( 2) The relationship between the material temperature immediately before drilling (T [K]) described in (1) and the material temperature immediately after drilling (T ′ [K]) is expressed by Equation (3). T ′ [K]) is lower than the overheat temperature (T 0 ). T ′ [K] ≈T [K] + (1 + 0.002 V [mm / sec]) × K (T) (3)
以上述べたように、本発明による穿孔直前材料温度ないしは穿孔直後材料温度、穿孔速度を制御することにより、穿孔時の材料温度がオーバーヒート温度に到達するのを防ぎ、内面疵の不良を低減させることが出来る極めて優れた効果を奏するものである。 As described above, by controlling the material temperature immediately before drilling or the material temperature immediately after drilling according to the present invention, and the drilling speed, the material temperature at the time of drilling can be prevented from reaching the overheat temperature, and the defect of the inner surface flaw can be reduced. It has an extremely excellent effect.
以下、本発明について詳細に説明する。
ピアサー・ミル穿孔条件は、ビレット加熱温度、穿孔速度、加工発熱量を考慮して温度解析を行い、ビレット内部の温度はオーバーヒート温度以下で、かつピアサー・ミルに咬み込み穿孔可能な温度以上となるように決められる。オーバーヒート温度はグリーブル試験によって得られる。ピアサー・ミル穿孔後のビレット内部温度分布の計算は公知の有限要素法を用いて解析した。
Hereinafter, the present invention will be described in detail.
The piercer mill drilling conditions are analyzed by considering the billet heating temperature, drilling speed, and processing heat generation, and the temperature inside the billet is below the overheating temperature and above the temperature at which the piercer mill can be bitten and drilled. To be decided. The overheat temperature is obtained by a greeble test. The calculation of billet internal temperature distribution after piercer mill drilling was analyzed using a known finite element method.
難加工性材料は、ピアサー・ミルで一般的に穿孔した場合に一般的な合金より変形抵抗が高く、高い熱間延性が得られる温度範囲が狭いため、ビレット加熱温度、穿孔速度等の穿孔可能条件が狭い。そこで、難加工性材料に条件を加え、材料温度に対する熱間変形抵抗(σ[MPa])との関係式(1)式で表され難加工性材料に関してのピアサー穿孔をする場合に、穿孔直前材料温度(T[K])と穿孔中の材料先進速度(V[mm/sec])との関係式(2)を満たすように設定するものである。これにより、穿孔中のオーバーヒートによる内面疵発生を防止するものである。 Difficult-to-work materials generally have higher deformation resistance than ordinary alloys when drilled with a piercer mill, and the temperature range where high hot ductility can be obtained is narrow, so billet heating temperature, drilling speed, etc. can be drilled Conditions are narrow. Therefore, when adding conditions to difficult-to-work materials and performing piercer drilling on difficult-to-work materials expressed by the relational expression (1) with hot deformation resistance (σ [MPa]) relative to material temperature, immediately before drilling It is set so as to satisfy the relational expression (2) between the material temperature (T [K]) and the material advanced speed (V [mm / sec]) during drilling. This prevents the occurrence of internal flaws due to overheating during drilling.
例えば、オーバーヒート温度(T0 )が1225℃、熱間変形抵抗(σ[MPa])がσ[MPa]=0.3×exp(7600/T[K])×(dε/dt)0.15 で表される材料を穿孔する場合、穿孔直前材料温度(T[K])を1070℃、穿孔圧延速度を400mm/sに設定すればオーバーヒートによる内面疵発生を防止することができる。 For example, the overheat temperature (T 0 ) is 1225 ° C., and the hot deformation resistance (σ [MPa]) is σ [MPa] = 0.3 × exp (7600 / T [K]) × (dε / dt) 0.15 . When drilling a material to be drilled, if the material temperature immediately before drilling (T [K]) is set to 1070 ° C. and the drilling and rolling speed is set to 400 mm / s, it is possible to prevent generation of internal flaws due to overheating.
また、穿孔直前材料温度(T[K])と穿孔直後材料温度(T´[K])との間には式(3)の関係があり、穿孔直後材料温度(T´[K])をオーバーヒート温度(T0 )より低くすることにより、穿孔中のオーバーヒートによる内面疵発生を防止するものである。T´[K]≒T[K]+(1+0.002V[mm/s])×K(T) … (3)
これにより、穿孔直後材料温度を管理することにより、適切なビレット加熱温度および穿孔速度にすることで管内面疵の発生を減少させることができる。
Further, there is a relationship of the formula (3) between the material temperature immediately before drilling (T [K]) and the material temperature immediately after drilling (T ′ [K]), and the material temperature immediately after drilling (T ′ [K]) is By making the temperature lower than the overheat temperature (T 0 ), the generation of internal flaws due to overheating during drilling is prevented. T ′ [K] ≈T [K] + (1 + 0.002V [mm / s]) × K (T) (3)
Thereby, by controlling the material temperature immediately after drilling, the occurrence of flaws on the inner surface of the pipe can be reduced by setting the billet heating temperature and drilling speed appropriately.
以下、本発明について実施例によって具体的に説明する。
オーバーヒート温度(T0 )を1523(K)、熱間変形抵抗(σ[MPa])を0.3×exp(7600/T[K])×(dε/dt)0.15 で表される難加工性材料を対象に、ピアサー穿孔を行った。表1に示すように、穿孔直前材料温度(T[K])と穿孔直後材料温度(T´[K])とを変えてピアサー穿孔を行い、ピアサー穿孔直後材料温度(T´[K])をサーモトレーザで測定し、穿孔後の材料内面を目視観察して内面疵の有無を調査した。その結果を表1に示す。
Hereinafter, the present invention will be specifically described with reference to examples.
Difficult workability represented by an overheat temperature (T 0 ) of 1523 (K) and hot deformation resistance (σ [MPa]) of 0.3 × exp (7600 / T [K]) × (dε / dt) 0.15 Piercer drilling was performed on the material. As shown in Table 1, piercer drilling was performed by changing the material temperature immediately before drilling (T [K]) and the material temperature immediately after drilling (T ′ [K]), and the material temperature immediately after piercing drilling (T ′ [K]). Was measured with a thermo-laser, and the inner surface of the material after drilling was visually observed to investigate the presence of inner surface flaws. The results are shown in Table 1.
その結果、材料先進速度100[mm/sec]〜600[mm/sec]の場合には、少なくとも穿孔直後材料温度が1526K以下の場合には疵の発生が生じていない。従って、穿孔直前材料温度(T[K])と穿孔直後材料温度(T´[K])の間には式3の関係があることが判明し、この穿孔直後材料温度(T´[K])をオーバーヒート温度(T0 )より低くすることにより、オーバーヒートによる内面疵の発生を防止できることが分かる。 As a result, when the material advanced speed is 100 [mm / sec] to 600 [mm / sec], no wrinkle is generated when the material temperature is 1526K or less immediately after drilling. Therefore, it is found that there is a relationship of Equation 3 between the material temperature immediately before drilling (T [K]) and the material temperature immediately after drilling (T ′ [K]), and the material temperature immediately after drilling (T ′ [K]). ) Lower than the overheat temperature (T 0 ), it can be seen that generation of internal flaws due to overheat can be prevented.
上述したように、穿孔直前材料温度と穿孔直後材料温度の間には式3の関係があることが多くの実験により判明したことにより、作業上において穿孔直後材料温度の温度を管理することにより、適切なビレット加熱温度および穿孔速度とすることにより管内面に疵の発生を防止することが可能となり、疵の発生を低減し安定した操業をすることが出来る極めて優れた効果を奏するものである。
特許出願人 山陽特殊製鋼株式会社
代理人 弁理士 椎 名 彊
As described above, the fact that there is a relationship of Equation 3 between the material temperature immediately before drilling and the material temperature immediately after drilling has been found by many experiments, and by managing the temperature of the material temperature immediately after drilling on the operation, By setting the billet heating temperature and the perforation speed appropriately, it is possible to prevent the generation of soot on the inner surface of the pipe, and it is possible to reduce the generation of soot and achieve an extremely excellent effect that enables stable operation.
Patent Applicant Sanyo Special Steel Co., Ltd.
Attorney: Attorney Shiina
Claims (2)
σ[MPa]=A×exp(D/T[K])×(dε/dt)m … (1)
T[K]+(1+0.002V[mm/sec])×K(T)<T0 [K]… (2)
但し、A:0〜1
D:実験で得られた鋼種によって決まる値を示す
m:歪み速度感受性指数、鋼種によって決まる値
V:ピアサー穿孔速度(m/sec)
K(T):鋼種、温度によって決まる値
T0 :オーバーヒート温度[K]であって、グリーブル試験で試験温度を上げたと きに、絞り値が最大値に対して5%低下するときの温度 In a method of manufacturing seamless steel pipes by rolling and drilling difficult-to-process materials with a Piercer mill, the relationship between the hot deformation resistance (σ [MPa]) with respect to the material temperature is expressed by the formula (1), and the difficult-to-work materials are Pierce drilled. In doing so, the inner surface due to overheating during drilling is set by satisfying the relational expression (2) between the material temperature immediately before drilling (T [K]) and the material advanced speed (V [mm / sec]) during drilling. A piercer drilling method for difficult-to-process materials, characterized by preventing wrinkles.
σ [MPa] = A × exp (D / T [K]) × (dε / dt) m (1)
T [K] + (1 + 0.002V [mm / sec]) × K (T) <T 0 [K] (2)
However, A: 0 to 1
D: A value determined by the steel type obtained in the experiment m: Strain rate sensitivity index, a value determined by the steel type V: Piercer drilling speed (m / sec)
K (T): Value determined by steel type and temperature T 0 : Overheat temperature [K], the temperature at which the aperture value decreases by 5% of the maximum value when the test temperature is raised in the greeble test
T´[K]≒T[K]+(1+0.002V[mm/sec])×K(T) … (3) The relationship between the material temperature immediately before drilling (T [K]) and the material temperature immediately after drilling (T ′ [K]) according to claim 1 is represented by the equation (3), and the material temperature immediately after drilling (T ′ [ K]) is made lower than the overheat temperature (T 0 ).
T ′ [K] ≈T [K] + (1 + 0.002 V [mm / sec]) × K (T) (3)
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