JP3860079B2

JP3860079B2 - Cutting steel bar having excellent shearability and method for producing the steel bar

Info

Publication number: JP3860079B2
Application number: JP2002182227A
Authority: JP
Inventors: 弘昭中里; 昭一梶本
Original assignee: Sanyo Special Steel Co Ltd
Current assignee: Sanyo Special Steel Co Ltd
Priority date: 2002-06-21
Filing date: 2002-06-21
Publication date: 2006-12-20
Anticipated expiration: 2022-06-21
Also published as: JP2004027258A

Description

【０００１】
【発明の属する技術分野】
シャー切断性に優れた棒鋼であって熱延あるいは熱処理などにより発生した黒皮肌の除去、表面キズ保証、脱炭保証あるいは寸法精度保証のために切削仕上げした棒鋼に関するものである。
【０００２】
【従来の技術】
熱間、温間あるいは冷間による鍛造用の棒鋼は、ユーザーにて切断し、その後所定の処理をして鍛造される場合が多い。この切断方法としては、シャー切断あるいは鋸切断が主として採用されている。ところで、例えばφ９０以上の特に太いサイズの棒鋼を除けば、シャー切断されるのが通常である。従来、棒鋼は熱間圧延仕上げ、あるいは熱間圧延後に焼きなましなどの熱処理を施した黒皮肌の棒鋼が使用されており、特に表面キズ保証、脱炭保証あるいは寸法精度保証の厳しい用途に対してはバーターニング（ピーリング、ターニング）等の切削による皮むき仕上げした棒鋼が使用されていた。
【０００３】
このような従来の技術において、最近は、鍛造歩留りの向上や、鍛造仕上げ寸法精度の向上等のニーズが強くなってきている。それに伴い素材である棒鋼に対しては、シャー切断後の棒鋼の重量管理のシビアー化に対応するため、みがき棒鋼並の寸法精度が求められてきており、また、シャー切断後のＴＰのダレ防止等の寸法精度向上のために切断機ガイドのクリアランスが小さくなってきている。さらに、鍛造仕上げ寸法精度向上に伴い、鍛造品の表面欠陥は極端に嫌われるようになり、それの原因となる素材の表面欠陥もあってはならず、たとえ錆び的なものでも嫌われる。従って、素材の防錆処理も重要となってきている。
【０００４】
棒鋼のシャー切断に関する従来の技術としては、切断方法に関するものとして特開昭５７−６１４１２号公報、特開昭５９−１６６４０８号公報、特開昭６３−３４０１３号公報など、良好な切断を実現するための材料の組織制御、硬さ制御等に関するものとして特開平１０−６０５９４号公報、特開平１０−６０５９５号公報、特開平１１−１９９９２７号公報など、切断装置に関するものとして特開平３−２９４１０４号公報、特開平７−３１４２３８号公報などが開示されているが、いずれもシャー切断用棒鋼の表面粗さ、防錆油の粘度には言及していない。
【０００５】
以上の従来技術において、上記した黒皮肌の棒鋼では、その寸法精度向上のニーズには応えきれていないため、シャー切断棒鋼のシビアーな重量管理が実現できていない。さらに、切断機ガイドでのクリアランスが良好に保てないため、ガイドでの詰まりが生じ、また、切断棒鋼のダレなどのため、良好な寸法精度が確保できていない。また、従来の切削によるピーリング仕上げ棒鋼は表面が平滑であって、かつ、防錆油が塗布されているため、シャー切断時に滑りを起こし、このため切断棒鋼の切断面が斜め（いわゆる「倒れ」）になり、これがその後の鍛造でキズの原因になる。さらに、切断時に滑るため、切断棒鋼のシビアーな重量管理も実現できていない、などの種々の問題点がある。
【０００６】
【発明が解決しようとする課題】
本発明が解決しようとする課題は、熱延仕上げや熱延後の焼きなましなどの熱処理後に発生した黒皮肌の除去、表面キズ保証および脱炭保証のための切削仕上げした棒鋼において、棒鋼表面の粗さと、その後に塗布される防錆油の粘度を適正に制御することにより、切断用母材（鋼材）の寸法精度を、通常幅で、例えば０．１〜０．２ｍｍとするが、ユーザーのニーズに応じた仕様に確保して、良好なシャー切断作業性、切断棒鋼の寸法精度およびシビアーな重量管理を実現する方法を提供するものである。
【０００７】
【課題を解決するための手段】
上記の課題を解決するための本発明の手段は、請求項１の発明では、棒鋼の黒皮肌の表面粗さＲｚを２．９〜８．８μｍとして切削仕上げした棒鋼表面に粘度５〜１４（Ｐｏｉｓｅ）の防錆油を防錆および鋼材同士の擦れキズ防止のため塗布したことを特徴とするシャー切断性に優れた切削仕上げ棒鋼である。
【０００８】
請求項２の発明では、棒鋼の黒皮肌の切削仕上げにおいて、表面粗さ：Ｒｚを２．９〜８．８μｍとして切削仕上げを行い、この切削仕上げした棒鋼の表面に粘度５〜１４（Ｐｏｉｓｅ）の防錆油を防錆および鋼材同士の擦れキズ防止のため塗布することを特徴とするシャー切断性に優れた切削仕上げ棒鋼の製造方法である。
【０００９】
【発明の実施の形態】
本発明の実施の形態を以下に示す実施例の発明例と比較例および従来例を通じて説明する。先ず、説明に先立って、本発明の作用および本発明の手段の限定理由を述べると、本発明は良好なシャー切断作業性と切断棒鋼の寸法精度、シビアーな重量管理を実現できるもので、その手段の限定理由を説明すると以下のとおりである。
【００１０】
本発明における棒鋼はφ９０以下の例えばφ２２．５〜４４．５の棒鋼であって、切削仕上げ棒鋼の表面粗さＲｚを２．９〜８．８μｍとする理由は、表面粗さＲｚが小さいと、シャー切断時にホルダーとの「噛み合い」が弱いため棒鋼が滑るので、この滑りを防止するためにＲｚ２．９μｍ以上が必要である。表面粗さＲｚが大きすぎるとシャー切断時に切断部近傍でクラックが生じ易くなり、その後の鍛造でキズの原因になる可能性が高くなるので、このクラックの発生を防止するためにＲｚの上限を８．８μｍとする必要がある。そこで、切削仕上げ棒鋼の表面粗さＲｚを２．９〜８．８μｍとする。
【００１１】
防錆油の粘度：５〜１４（Ｐｏｉｓｅ）とする理由は、防錆油の粘度が小さすぎると、鋼材搬送中に鋼材同士の擦れキズが発生し、また防錆効果も小さくなるために粘度の下限を５（Ｐｏｉｓｅ）とする。防錆油の粘度が大きすぎると、シャー切断時に鋼材とシャー切断ホルダーの間に防錆油が残留し易くなり、そのため鋼材とシャー切断ホルダーとの「噛み合い」が弱くなり滑るので、粘度の上限を１４（Ｐｏｉｓｅ）とする。そこで、防錆油の粘度を５〜１４（Ｐｏｉｓｅ）とする。
【００１２】
【実施例】
熱間圧延仕上げして得られた黒皮肌を有するφ２４〜φ４６の棒鋼をピーリング機により黒皮を除去する切削仕上げし、防錆油を塗布し、それらの棒鋼の９種を得た。それらをシャー切断してその切断性で評価した。表１に示すように、これら９種は、それぞれ切削仕上げ棒鋼の表面粗さＲｚ、防錆油の粘度が本発明の範囲にあるものを本発明例として４種と、一つでも本発明の範囲外のものを比較例の３種と従来例の２種として、それぞれシャー切断性は、切断作業能率および切断棒鋼の寸法精度で判断し、シャー切断性の良好なものを○、切断できたが問題のあるものを△、切断不良のものを×で評価した。なお、寸法精度については、切断面の形状が良好なもの、すなわち切断面が斜めにならず、いわゆる「倒れ」が発生せず、かつ、切断部近傍でクラックが発生しないものを○とした。
【００１３】
【表１】

【００１４】
表１に見られるように、表面粗さＲｚおよび防錆油の粘度が共に本発明の範囲にあるものはいずれもシャー切断性は良好で問題はなかった。これに対し比較例のＮｏ．５のものは表面粗さＲｚが本発明の上限を超えており、この場合は鍛造品にシャー切断部近傍で発生したクラックが起因の鍛造キズの発生が見られた。比較例のＮｏ．６のものは表面粗さＲｚは本発明の範囲にあるが、防錆油の粘度が本発明の下限未満であり、この場合は素材擦れキズの発生が見られた。さらに、比較例のＮｏ．７のものは表面粗さＲｚは本発明の範囲を満足するが、防錆油の粘度が本発明の上限を超えるものであり、この場合は滑りが発生して切断が不良で×であった。従来例のＮｏ．８のものは、黒皮品であり、鋼材（切断用母材）の寸法公差、真円度などの寸法精度保証ができておらず、そのため詰まりを発生して満足にシャー切断出来なかった。さらに、従来例のＮｏ．９のものは表面粗さＲｚが本発明の下限値に満たなかったもので、防錆油は本発明の範囲に入る粘度のものであったが、滑りが発生して満足にシャー切断出来なかった。
【００１５】
【発明の効果】
以上説明したように、本発明は、熱間圧延仕上げや熱間圧延後焼きなましした黒皮肌の棒鋼を、例えばピーリングなどにより切削仕上げ棒鋼とする際に、その切削仕上げ粗さおよび切削仕上げ後塗布する防錆油の粘度を最適化することにより、シャー切断の噛み合いが良好で、切断寸法精度が良好で有るなど極めて優れたシャー切断性を有する棒鋼に製造できる優れた効果を有するものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel bar having excellent shearability, which has been finished for removal of black skin caused by hot rolling or heat treatment, surface scratch guarantee, decarburization guarantee or dimensional accuracy guarantee.
[0002]
[Prior art]
In many cases, hot, warm or cold forging steel bars are cut by a user and then forged by a predetermined treatment. As this cutting method, shear cutting or saw cutting is mainly employed. By the way, the shear cutting is usually performed except for a steel bar having a particularly large size of φ90 or more. Conventionally, steel bars that have undergone hot rolling finish or heat treatment such as annealing after hot rolling have been used, especially for applications with severe surface scratches, decarburization, or dimensional accuracy. Steel bars that were peeled off by cutting such as bar turning (peeling, turning) were used.
[0003]
In such a conventional technique, recently, needs such as improvement of forging yield and improvement of forging finish dimensional accuracy have become stronger. Along with that, in order to cope with the severe weight management of the steel bar after shear cutting, dimensional accuracy equivalent to that of polished steel bar has been demanded, and prevention of sagging of TP after shear cutting. In order to improve the dimensional accuracy, etc., the clearance of the cutting machine guide is becoming smaller. Further, as the forged finish dimensional accuracy is improved, the surface defects of the forged product are extremely disliked, and the surface defects of the material that causes the forged product should not be present, even if it is rusty. Therefore, the rust prevention treatment of the material has become important.
[0004]
As conventional techniques relating to shear cutting of steel bars, good cutting methods such as Japanese Patent Application Laid-Open Nos. 57-61412, 59-166408, and 63-34013 are realized as related to cutting methods. JP-A-10-60594, JP-A-10-60595, JP-A-11-199927, etc., as related to the structure control, hardness control, etc. of the material, JP-A-3-294104 Japanese Patent Laid-Open No. 7-314238 and the like are disclosed, but none of them mentions the surface roughness of shear cutting steel bars and the viscosity of rust preventive oil.
[0005]
In the above prior art, the above-described black skinned steel bar cannot meet the needs for improving its dimensional accuracy, and thus severe weight management of shear-cut steel bar cannot be realized. Furthermore, since the clearance in the cutting machine guide cannot be maintained well, clogging occurs in the guide, and due to sagging of the cut bar steel, good dimensional accuracy cannot be ensured. In addition, the conventional peeled steel bar has a smooth surface and is coated with rust-preventive oil, which causes slippage during shear cutting, and therefore the cut surface of the cut steel bar is slanted (so-called “falling”) This will cause scratches in the subsequent forging. Furthermore, since it slides at the time of cutting, there are various problems such as severe weight management of the cut steel bar has not been realized.
[0006]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to cut the steel bar surface after the heat treatment such as hot rolling finish and annealing after hot rolling, and to cut the steel bar for surface scratch and decarburization. By appropriately controlling the roughness and the viscosity of the rust preventive oil applied thereafter, the dimensional accuracy of the base material for cutting (steel material) is set to a normal width, for example, 0.1 to 0.2 mm. By ensuring the specifications according to the needs, there is provided a method for realizing good shear cutting workability, dimensional accuracy of the cut steel bar and severe weight management.
[0007]
[Means for Solving the Problems]
The means of the present invention for solving the above-described problems is that, in the invention of claim 1, the surface roughness Rz of the black skin of the steel bar is 2.9 to 8.8 μm and the steel bar surface is finished with a viscosity of 5 to 14 (Poise) rust preventive oil is applied to prevent rust and scratches between steel materials.
[0008]
In the invention of claim 2, in the cutting finish of the black skin of the steel bar , the surface roughness: Rz is 2.9 to 8.8 μm and the finishing is performed, and the surface of the steel bar after the cutting finish has a viscosity of 5 to 14 (Poise). Is applied to prevent rust and scratches between steel materials, and is a method for producing a finished steel bar having excellent shear cutting ability.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described through invention examples, comparative examples, and conventional examples of the following examples. First, prior to the description, the reason for limiting the action of the present invention and the means of the present invention will be described.The present invention can realize good shear cutting workability, dimensional accuracy of the cut steel bar, and severe weight management. The reason for limiting the means will be described as follows.
[0010]
The steel bar in the present invention is a steel bar of φ90 or less, for example, φ22.5 to 44.5, and the reason why the surface roughness Rz of the cut steel bar is 2.9 to 8.8 μm is that the surface roughness Rz is small. Since the steel bar slips because the “meshing” with the holder is weak when cutting the shear, Rz of 2.9 μm or more is necessary to prevent this slip. If the surface roughness Rz is too large, cracks are likely to occur in the vicinity of the cut part during shear cutting, and there is a high possibility of causing scratches in subsequent forging. Therefore, in order to prevent the occurrence of cracks, the upper limit of Rz is set. It must be 8.8 μm. Therefore, the surface roughness Rz of the cut steel bar is set to 2.9 to 8.8 μm.
[0011]
Viscosity of rust preventive oil: 5 to 14 (Poise) The reason is that if the viscosity of the rust preventive oil is too small, rubbing scratches between the steel materials are generated during conveyance of the steel material, and the rust preventive effect is also reduced. Is set to 5 (Poise). If the viscosity of the rust preventive oil is too high, the rust preventive oil tends to remain between the steel material and the shear cutting holder during shear cutting, so the "meshing" between the steel material and the shear cutting holder becomes weak and slips, so the upper limit of viscosity Is 14 (Poise). Therefore, the viscosity of the rust preventive oil is set to 5 to 14 (Poise).
[0012]
【Example】
A steel bar of φ24 to φ46 having a black skin surface obtained by hot rolling finish was cut and finished with a peeling machine to remove the black skin, and rust preventive oil was applied to obtain 9 types of the steel bars. They were sheared and evaluated by their cutting properties. As shown in Table 1, each of these nine types has four types as examples of the present invention, each of which has the surface roughness Rz of the cut steel bar and the viscosity of the rust preventive oil within the scope of the present invention. Three types of comparative examples and two types of conventional examples were used, and the shear cutting ability was judged based on the cutting work efficiency and the dimensional accuracy of the cut steel bar, and those having good shear cutting ability could be cut. The problem was evaluated by Δ, and the defective one was evaluated by ×. Regarding the dimensional accuracy, a case where the shape of the cut surface is good, that is, a case where the cut surface is not inclined, so-called “falling” does not occur, and cracks do not occur in the vicinity of the cut portion is indicated as “◯”.
[0013]
[Table 1]

[0014]
As can be seen from Table 1, both the surface roughness Rz and the viscosity of the rust preventive oil were within the range of the present invention, and the shear cutting property was good and there was no problem. In contrast, No. of the comparative example. In the case of No. 5, the surface roughness Rz exceeded the upper limit of the present invention, and in this case, forging flaws due to cracks generated in the vicinity of the shear cutting portion were observed in the forged product. Comparative Example No. In the case of No. 6, the surface roughness Rz is in the range of the present invention, but the viscosity of the rust preventive oil is less than the lower limit of the present invention. In this case, generation of scratches on the material was observed. Furthermore, No. of the comparative example. In No. 7, the surface roughness Rz satisfies the range of the present invention, but the viscosity of the rust preventive oil exceeds the upper limit of the present invention. . No. of the conventional example. No. 8 is a black skin product, and dimensional accuracy such as dimensional tolerance and roundness of a steel material (cutting base material) has not been guaranteed, so clogging has occurred and shear cutting has not been achieved satisfactorily. Furthermore, No. of the conventional example. In No. 9, the surface roughness Rz was less than the lower limit of the present invention, and the rust preventive oil had a viscosity falling within the range of the present invention. It was.
[0015]
【The invention's effect】
As described above, the present invention is applied to a cut-finish roughness and a post-cut-finish coating when a black-skinned steel bar annealed after hot-rolling finish or after hot-rolling is made into a cut-finished steel bar by , for example, peeling. By optimizing the viscosity of the rust-preventing oil, it has an excellent effect of being able to produce a steel bar having extremely excellent shear cutting properties such as good shear cutting engagement and good cutting dimensional accuracy.

Claims

The surface of the steel bar with a skin roughness of Rz 2.9 to 8.8 μm was applied to the surface of the steel bar with a rust preventive oil with a viscosity of 5 to 14 (Poise) to prevent rust and scratches between steel materials. This is a finished steel bar with excellent shear cutting characteristics.

When cutting the black skin of the steel bar , the surface roughness: Rz is set to 2.9 to 8.8 μm, and the surface of the steel bar is finished with rust preventive oil with a viscosity of 5 to 14 (Poise). A method for producing a machined steel bar having excellent shear cutting properties, which is applied to prevent rust and scratches between steel materials.