JPH0381008A - Manufacture of steel pipe to be cut - Google Patents

Abstract

PURPOSE:To improve a yield without inhibiting the realization of a good cutting property by executing a cold working on the pipe blank obtained by a hot working under the conditions of a specified reduction ratio in area. CONSTITUTION:In the case of the manufacture of the steel pipe to be cut on which cutting is executed later of the steel pipe for a machine structure of for an automobile part, etc., for instance, the pipe blank obtained by a hot working is subjected to cod working under the conditions becoming at <= 20% reduction in area. As a result, a high machinability is realized on a product pipe and also the correction of the bent, etc., caused at working time can be performed easily at high accuracy. Moreover, the steel pipe to be cut excellent in a machinability can be manufactured without incurring the reduction in a yield accompanying to the correction of its deformation.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、例えば自動車部品用の機械構造用鋼管等、後
に切削加工を施される被切削鋼管の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a steel pipe to be cut, such as a steel pipe for machine structural use for automobile parts, which is subsequently subjected to a cutting process.

〔従来技術〕[Prior art]

自動車の製造に際しては、各部の軸受部品等の多くの管
状部品を必要とし、これらの管状部品は、素材となる機
械構造用鋼管に所定の切削加工を施して製造される。こ
のように、後に切削加工を施される鋼管、即ち被切削泡
管には、切削加工時における工具寿命の延命化を図るべ
く、高い切削性が要求される。When manufacturing an automobile, many tubular parts such as bearing parts for various parts are required, and these tubular parts are manufactured by performing predetermined cutting on mechanical structural steel pipes. As described above, a steel pipe to be cut later, that is, a foam tube to be cut, is required to have high machinability in order to extend the life of a tool during cutting.

鋼材の切削性を改善する方法としては、硫黄。Sulfur is a method to improve the machinability of steel materials.

鉛等の不純物元素の添加及び高硬度化があるが、前者は
材質変化を伴う方法であり、この方法の採用により得ら
れる被切削鋼管、即ち、快削鋼製の被切削鋼管は、最終
的な用途が制限され、前述した軸受部品等の鋼の清浄度
が要求されるような部品用の素材として適正なものでは
ない。これに対し、後者の方法、即ち高硬度化は、材質
変化を伴うことがないため、最終的な用途の如何に拘わ
らず採用することができ、また、鋼材の硬度の高低は、
一般的に冷間での加工度の大小に対応することが公知で
ある。従って、自動車用部品等の素材とする被切削鋼管
においては、従来、熱間にて得られた管素材に冷間にて
可及的に大きい加工度を与え、硬度を高めて切削性を改
善することが行われている。The former involves adding impurity elements such as lead and increasing hardness, but the former method involves changes in material properties, and the cut steel pipe obtained by adopting this method, that is, the cut steel pipe made of free-cutting steel, is Its uses are limited, and it is not suitable as a material for parts such as the aforementioned bearing parts that require the cleanliness of steel. On the other hand, the latter method, that is, increasing the hardness, does not involve changes in material properties, so it can be adopted regardless of the final use.
It is generally known that it corresponds to the degree of cold working. Therefore, in the case of steel pipes to be cut to be used as raw materials for automobile parts, etc., conventionally, the pipe material obtained by hot processing is subjected to as large a degree of processing as possible in cold processing to increase hardness and improve machinability. things are being done.

〔発明が解決しようとする課題〕[Problem to be solved by the invention]

ところが、このようにして製造される従来の被切削鋼管
は、大きい加工度が与えられ、高い硬度を有しているた
めに、製造段階において曲がり鰯の変形が生じた場合、
これの矯正が、応力除去鵠鈍等の熱処理を行った後にお
いても困難であり、歩留りの悪化を招来するという難点
があった。However, since the conventional steel pipes to be cut manufactured in this way are given a large degree of processing and have high hardness, if deformation of the bent sardine occurs during the manufacturing stage,
It is difficult to correct this even after heat treatment such as stress relief dulling is performed, resulting in a problem of deterioration of yield.

本発明は斯かる事情に鑑みてなされたものであり、良好
な切削性の実現を阻害することなく、渉留りの向上を可
能とする被切削鋼管の製造方法を提供することを目的と
する。The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for manufacturing a steel pipe to be cut, which makes it possible to improve the wading retention without hindering the realization of good machinability. .

〔課題を解決するための手段〕[Means to solve the problem]

本発明に係る被切削鋼管の製造方法は、後工程において
切削加工を施される被切削鋼管を製造するに際し、熱間
にて得られた管素材を、２０％以下の断面減少率にて冷
間加工して製品管を得ることを特徴とする。The method for producing a steel pipe to be cut according to the present invention cools a pipe material obtained in a hot state at a cross-sectional area reduction rate of 20% or less when producing a steel pipe to be cut to be subjected to cutting in a subsequent process. It is characterized by obtaining a product pipe through processing.

〔作用〕[Effect]

本発明においては、熱間にて得られた管素材を断面減少
率２０％以下なる条件下にて冷間加工することにより、
後に切削加工を施される用途に用いられる被切削鋼管を
、歩留りの低下を招来することなく製造する。In the present invention, by cold-working the hot-obtained tube material under conditions where the cross-sectional reduction rate is 20% or less,
To manufacture a steel pipe to be cut, which is used for a purpose that is later subjected to cutting processing, without causing a decrease in yield.

〔実施例〕〔Example〕

以下本発明をその実施例に基づいて詳述する。 The present invention will be described in detail below based on examples thereof.

前述した如く、鋼材の切削性の良否は硬度の高低に対応
し、また、硬度の高低は冷間での加工度の大小に対応す
る。一方、製造段階において生じる曲がり等の変形の矯
正は、製品管の硬度が高くなるに従って困難となる。本
発明者等は、以上のことに着目し、良好な切削性と矯正
の容易さとを同時的に実現すべく、種々の鋼種の管素材
を種々の加工度（断面減少率）にて冷間加工して製品管
を得る製管試験を行った結果、断面減少率が２０％以下
の場合、冷間加工後の製品管を十分な精度にて矯正する
ことが可能であり、また、断面減少率が１０％〜２０％
の範囲において、これよりも十分に大きい断面減少率を
与えて冷間加工を行った場合に比較して、切削性はむし
ろ向上し、同一の切削条件下にて工具寿命が増すことを
知見した。As mentioned above, the machinability of a steel material corresponds to its hardness, and the hardness corresponds to its degree of cold working. On the other hand, as the hardness of the product pipe increases, it becomes more difficult to correct deformations such as bends that occur during the manufacturing stage. The present inventors focused on the above, and in order to achieve good machinability and ease of straightening at the same time, the present inventors cold-worked pipe materials of various steel types at various degrees of processing (area reduction rate). As a result of pipe manufacturing tests to obtain product pipes by processing, if the cross-sectional reduction rate is 20% or less, it is possible to straighten the product pipe after cold working with sufficient accuracy, and it is possible to correct the cross-sectional reduction. rate is 10%~20%
It was found that the machinability was rather improved and the tool life was increased under the same cutting conditions, compared to when cold working was performed with a sufficiently larger area reduction ratio than this range. .

実施例として、転がり軸受用の素材となる高炭素クロム
軸受鋼２種（ＳＵＪ２鋼）での試験結果を示す。As an example, test results are shown for a type 2 high carbon chromium bearing steel (SUJ2 steel) which is a material for rolling bearings.

管素材としては、外径４８．６ｍｍ、肉厚１０．５ｍｍ
の大きさに熱間加工した後に所定の熱処理を施したもの
を用い、この管素材を種々の断面減少率下にて冷間加工
して、第１表に示す５種類の製品管を製造し、これらの
夫々に対して、硬度の測定及び切削性の評価を行うと共
に、偏平試験により変形能の良否を判定し、更に、製品
管に生じている曲がりの矯正をストレートナ−により実
施し、矯正状態の良否を判定した。The tube material has an outer diameter of 48.6 mm and a wall thickness of 10.5 mm.
After hot working to the size of the pipe material and then subjecting it to the specified heat treatment, this pipe material was cold worked under various cross-sectional reduction ratios to produce the five types of product pipes shown in Table 1. For each of these, the hardness is measured and the machinability is evaluated, the deformability is determined by a flattening test, and any bends that have occurred in the product tube are corrected using a straightener. The quality of the correction was determined.

以上の５種の製品管について硬度（ロックウェル硬さ）
測定を行った結果を第１図に示す。この図から、製品管
の硬度は、冷間加工の際の加工度の増加、即ち、断面減
少率の増加に伴って増す傾向を示すが、断面減少率の増
加に対する硬度の増加割合は一様ではなく、断面減少率
が１０％に達するまでの間にて硬度は急増するのに対し
、１０％を超えた後の硬度の増加割合は緩やかとなるこ
とが明らかである。Hardness (Rockwell hardness) of the above five types of product pipes
The results of the measurements are shown in Figure 1. This figure shows that the hardness of the product pipe tends to increase as the degree of work increases during cold working, that is, as the area reduction rate increases, but the ratio of increase in hardness to the increase in area reduction rate is uniform. Rather, it is clear that the hardness rapidly increases until the area reduction rate reaches 10%, whereas the rate of increase in hardness after it exceeds 10% becomes gradual.

また、前述した５種の製品管の切削性を評価すべく、切
削加工試験を行った結果を第２図に示す。Further, in order to evaluate the machinability of the five types of product pipes mentioned above, a cutting test was conducted, and the results are shown in FIG.

この切削加工試験は、タングステン系の高速度工具鋼４
種（ＳＫＨ４）製の工具による旋削加工を、切込み深さ
１．０ｍｍ、送り速度０．２５ｍｍ／　ｒｅｖ、なる条
件下において、５０ｍ／ｍｉｎ、　６０ｍ／ｍｉｎ、　
７０ｍ／ｎ＋ｉｎなる３種の切削速度を与えて無潤滑に
て夫々行い、切削不能に至るまでの工具寿命の長短によ
り切削性の良否を判定した。This cutting test was conducted using tungsten-based high-speed tool steel 4.
Turning was performed using a tool made of SKH4 under the following conditions: depth of cut 1.0 mm, feed rate 0.25 mm/rev, 50 m/min, 60 m/min,
Three different cutting speeds of 70 m/n+in were applied without lubrication, and the machinability was judged based on the length of tool life until cutting became impossible.

この図から、切削速度５０ｍ／ｍｉｎにおいては、断面
減少率が１５％程度のときに工具寿命が最も長く、切削
性が最も良好となり、断面減少率が１５％よりも小さい
場合も大きい場合も共に、工具寿命の低下が生じ、切削
性が悪化する傾向を示すことが明らかである。また、切
削速度が６０ｍ／ｌｌ１ｉｎ及び７０ｍ／ｍｉｎである
場合、前述した試験条件下においては工具寿命が短か過
ぎ、各製品管間の差異は認め難いが、切削速度が５０ｍ
／ｍｉｎである場合と同様、断面減少率が１０〜２０％
であるときに工具寿命が長く、切削性が良好となること
が明らかである。From this figure, at a cutting speed of 50 m/min, the tool life is the longest and the machinability is the best when the area reduction rate is about 15%, and both when the area reduction rate is smaller and larger than 15%. , it is clear that there is a tendency for the tool life to decrease and the machinability to deteriorate. In addition, when the cutting speed is 60m/ll1in and 70m/min, the tool life is too short under the test conditions mentioned above, and it is difficult to recognize the difference between each product pipe, but when the cutting speed is 50m/min.
/min, the area reduction rate is 10-20%
It is clear that the tool life will be longer and the cutting performance will be better when the conditions are as follows.

更に、前記５種の製品管の夫々に対し、偏平試験を行っ
た結果を第２表に、また曲り矯正試験を行った結果を第
３表に夫々示す。Furthermore, Table 2 shows the results of a flattening test for each of the five types of product pipes, and Table 3 shows the results of a bend straightening test.

第　　２　　表 （以下余白） 第 表 第２表中の偏平比は、製品管を断面の半径方向に圧縮し
た際に、管壁に疵割れが生じる限界における縦横長さの
比であり、変形能の優劣を示す指標となるものである。Table 2 (blank below) The aspect ratio in Table 2 is the ratio of the vertical and horizontal lengths at the limit at which flaws occur in the pipe wall when the product pipe is compressed in the radial direction of the cross section, and is the It serves as an indicator of the superiority or inferiority of

また、第３表中の曲り矯正状態の欄には、製品管に生し
ている１１１１りの矯正をストレートナ−にて実施した
際、長さ１０００ｍｍに対して１ｍｍ以下の精度での曲
り矯正が、１回の矯正作業により全数に亘って実現され
たものに対して○を、また、数回の矯正作業により前記
１１′１度が実現されたものに対して△を、更に、前記
精度の実現の前に矯正による割れが発生したものに×を
、夫々付しである。In addition, in the column of bend straightening condition in Table 3, when straightening 1111 of the product pipes with a straightener, the bends were straightened with an accuracy of 1 mm or less for a length of 1000 mm. ○ indicates that the above-mentioned 11'1 degree was achieved through several correction operations. An "X" is attached to each item where cracking occurred due to correction before the realization of the above.

第２表から、半径方向の圧縮に対して割れが発生する限
界の偏平比は、冷間における断面減少率が大きく、硬度
が増大するに伴って増大する傾向を示し、製品管の変形
能は、断面減少率の増大にイ゛［っで劣化することが明
らかであり、またこのことは、第３表に示す曲り矯正状
態の判定結果からも明らかである。即ち、これらの結果
から、冷間加工特における断面減少率が２０％以下であ
る場合、製品管の変形能は高く、加工後における曲り矯
正が、実用上十分な精度にて容易に実施できることがわ
かる。Table 2 shows that the critical aspect ratio at which cracking occurs due to radial compression has a large cross-sectional area reduction rate during cold working, tends to increase with increasing hardness, and the deformability of the product pipe is It is clear that deterioration occurs due to an increase in the area reduction rate, and this is also clear from the determination results of the bending straightening state shown in Table 3. In other words, these results show that when the cross-sectional reduction rate during cold working is 20% or less, the deformability of the product pipe is high and bend straightening after processing can be easily carried out with sufficient precision for practical use. Recognize.

〔効果〕〔effect〕

以上詳述した如く、熱間にて得られた管素材を断面減少
率２０％以下にて冷間加工して製品管を得る本発明に係
る被切削鋼管の製造方法によれば、製品管に高い切削性
が実現されると共に、加工時に生じる曲り等の変形の矯
正を高精度にて容易に行うことができ、切削性に優れた
被切削鋼管を変形の矯正に伴う歩留りの低下を招来する
ことなく提供することが可能となる等、本発明は優れた
効果を奏する。As described in detail above, according to the method for producing a cut steel pipe according to the present invention, which obtains a product pipe by cold working a pipe material obtained by hot processing at a cross-sectional reduction rate of 20% or less, the product pipe In addition to achieving high machinability, it is also possible to easily correct deformations such as bends that occur during machining with high precision, which reduces the yield of steel pipes to be cut that have excellent machinability due to correction of deformations. The present invention has excellent effects, such as being able to provide the product without having to use the product.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は種々の断面減少率にて冷間加工を行って得られ
た製品管の硬度の測定結果を示す図、第２図は同様にし
て得られた製品管に切削加工を施した際の工具寿命を調
べた結果を示す図である。Figure 1 shows the results of measuring the hardness of product pipes obtained by cold working at various cross-sectional reduction rates, and Figure 2 shows the results of measuring the hardness of product pipes obtained in the same manner by cutting. It is a figure which shows the result of investigating the tool life of.

Claims (1)

【特許請求の範囲】[Claims] １、後工程において切削加工を施される被切削鋼管を製
造するに際し、熱間にて得られた管素材を、２０％以下
の断面減少率にて冷間加工して製品管を得ることを特徴
とする被切削鋼管の製造方法。1. When manufacturing steel pipes to be cut that will be subjected to cutting in the subsequent process, it is necessary to cold-work the pipe material obtained by hot processing at a cross-sectional area reduction rate of 20% or less to obtain the product pipe. Characteristic manufacturing method for cut steel pipes.