JP3589164B2 - Extrusion processing method - Google Patents
Extrusion processing method Download PDFInfo
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- JP3589164B2 JP3589164B2 JP2000244237A JP2000244237A JP3589164B2 JP 3589164 B2 JP3589164 B2 JP 3589164B2 JP 2000244237 A JP2000244237 A JP 2000244237A JP 2000244237 A JP2000244237 A JP 2000244237A JP 3589164 B2 JP3589164 B2 JP 3589164B2
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Description
【0001】
【発明の属する技術分野】
本発明は、押出し加工方法、なかでも孔ダイスを用いて線材、棒鋼や鋼線といった中実鋼材を押出し加工する方法に関する。
【0002】
【従来の技術】
断面形状が円形の中実鋼材のうち線材や棒鋼は、圧延などの「1次加工」によって所望の寸法(直径)に仕上げられた後、更に、「2、3次加工」と称される熱処理や冷間押出し加工、冷間引抜き加工、冷間鍛造加工及び冷間切削加工などの冷間加工工程を経て、自動車、各種産業機械などに広く用いられるシャフトやロッド、ボルトなどの最終部品に成形される。
【0003】
上記部品の多くは冷間加工後の断面形状(真円度、外形寸法など)や、材料軸部の真直性に厳しい精度が要求される。このうち、材料軸部に特に厳しい真直性が要求される部品、例えば長軸ボルトやシャフトギアなどの場合には、冷間押出し加工によって断面形状精度の確保と真直性の確保を行うことも多い。しかしながら、押出し加工の際の加工条件によっては、却って長手方向に曲がりが生じることがあり、所望の真直精度が得られず、形状修正工程を追加する必要が生じる場合があった。
【0004】
【発明が解決しようとする課題】
本発明は、上記現状に鑑みなされたもので、断面形状が円形の中実鋼材、すなわち線材、棒鋼や鋼線を孔ダイス(以下、単にダイスともいう)を用いて押出し加工する方法、なかでも被加工材の曲がり発生量を後述する無次元曲率r/ρで0.0008以下に抑制できる押出し加工方法を提供することを目的とする。
【0005】
【課題を解決するための手段】
本発明は、下記に示す押出し加工方法を要旨とする。
【0006】
すなわち、「中実鋼材の押出し加工方法であって、出側テーパ角度の半角θ(゜)が下記 (1)式を満たすとともに、出側テーパ部長さL(mm)とベアリング部長さE(mm)との比が下記 (2)式を満たす孔ダイスを用いて、下記 (3)式を満たす加工率で加工する押出し加工方法。
【0007】
0.02゜≦θ≦0.5゜・・・(1)
1≦L/E≦30・・・(2)
0.10D≦E(d/D)2 ≦0.33D・・・(3)」である。
【0008】
ここで、Dは孔ダイス入り側における被加工材の直径(mm)、dは孔ダイスを出た被加工材の直径、つまり押出し加工後の被加工材の直径(mm)を意味する。
【0009】
本発明者らは、中炭素鋼線を供試材として、押出しによる軸絞り加工(以後、単に押出し加工という)を種々の条件で行い、加工後の長手方向の曲がり量を測定した。その結果、下記の知見を得た。
(a)直径D(mm)の鋼線を直径d(mm)に押出し加工した場合の長手方向の曲がり量は、ダイス形状としての出側テーパ部長さL(mm)、ベアリング部長さE(mm)、出側テーパ角度2θ、したがってその半角θ(゜)に大きく影響される。なお、図1は、上記L、E、θの形状のダイスを用いて直径D(mm)の鋼線を直径d(mm)に押出し加工する状況を示す図である。
【0010】
(b)押出し加工の減面率を調整することで長手方向の曲がり量を抑制することができる。
【0011】
そこで更に、各種の合金鋼線やステンレス鋼線を供試材とした押出し加工を種々の条件で行い、加工後の長手方向の曲がり量を測定した。その結果、上記(a)、(b)が合金鋼線やステンレス鋼線を供試材とする場合にも成り立つことが確認できた。
【0012】
本発明は、上記の知見に基づいて完成されたものである。
【0013】
【発明の実施の形態】
以下、本発明の各要件について説明する。
ダイスの出側テーパ角度の半角θ:
図2は、押出し加工後の曲がり量に及ぼすダイスの出側テーパ角度の半角θ(゜)の影響の一例として、直径Dが33mmであるJIS G 4051に記載のS45Cの棒鋼を押出し加工して30mmの直径dに加工した場合の状況を示すものである。
【0014】
なお、押出し加工後の曲がり量は、無次元曲率r/ρで評価した。この無次元曲率(r/ρ)は、押出し加工された鋼線の稜線座標を三次元測定器により測定し、その座標から曲率半径ρ(mm)を算出し、次いで、押出し加工後の鋼線の半径r(mm)を上記曲率半径ρで除して求めたものである。
図2に一例を示したように、ダイスの出側テーパ角度の半角θが0.5゜を超えると、押出し加工後の曲がり量が急激に増加し、無次元曲率r/ρの値が0.0008を超えてしまう。一方、ダイスの出側テーパ角度の半角θが0.02゜より小さい場合、曲がりの発生を抑制できるものの、ダイスとの接触による押出し荷重の増加やダイスとの焼き付きなどの問題が生じる。したがって、ダイスの出側テーパ角度の半角θに関し、前記 (1)式を満たすように規定した。
出側テーパ部長さとベアリング部長さとの比(L/E):
図3は、押出し加工後の曲がり量に及ぼすダイスのL/Eの影響の一例として、直径Dが33mmであるJIS G 4051に記載のS45Cの棒鋼を押出し加工して30mmの直径dに加工した場合の状況を示すものである。なお、この図3においても押出し加工後の曲がり量は、無次元曲率r/ρで示した。
図3に一例を示したように、L/Eの値が1より小さい場合、押出し加工後の曲がり量が急激に増加し、無次元曲率r/ρの値が0.0008を超えてしまう。一方、L/Eの値が30を超える場合、曲がりの発生を抑制できるものの、ダイス自体の大きさが極端に大きくなって、工業的には適用が困難になる。したがって、出側テーパ部長さとベアリング部長さとの比であるL/Eの値に関し、前記 (2)式を満たすように規定した。
加工率:
図4は、押出し加工後の曲がり量に及ぼす加工率及びダイスベアリング長さの影響の一例として、直径Dが33mmであるJIS G 4051に記載のS45Cの棒鋼を、種々のベアリング部長さE(mm)のダイスで押出し加工して直径dが30mmにした場合の状況を示すものである。なお、この図4においても押出し加工後の曲がり量は、無次元曲率r/ρで示した。
図4に一例を示したように、ベアリング部長さE(mm)と押出し加工後及び押出し加工前の鋼線の直径の比(d/D)の2乗との積であるE(d/D)2 の値が0.10Dより小さいか、0.33Dを超える場合には無次元曲率r/ρの値が0.0008を超えてしまう。したがって、押出し加工の加工率に関し、前記 (3)式を満たすように規定した。
【0015】
以下、本発明を実施例によって更に詳しく説明する。
【0016】
【実施例】
表1に示す化学組成を有する鋼1と鋼2を通常の方法によって溶製した。鋼1と鋼2はそれぞれJIS G 4051に記載のS45CとJIS G 4104に記載のSCr420に相当する鋼である。なお、Tiは不純物として含まれていたものである。
【0017】
【表1】
これらの鋼を通常の方法によって鋼片とした後、1230℃に加熱してから1200〜950℃の温度で直径35mmの丸棒に熱間鍛造し、その後常温まで空冷した。
【0018】
このようにして得られた丸棒の外表面を切削加工して直径が33mmで長さが1mの試験片を作製した。
【0019】
次いで、上記試験片を切断して通常の方法で燐酸亜鉛皮膜処理を施し、500トンプレスを用いて、加工後の直径が30mmになるように種々の条件で押出し加工を行って、加工後の長手方向の曲がり量を測定した。表2に、押出し加工した条件を示す。
【0020】
【表2】
表2から、本発明に係る試験番号1〜5においては、曲がり発生量を無次元曲率r/ρで0.0008以下に抑制できることが明らかである。
これに対して、本発明で規定する条件を外れた試験番号6、7、9及び10においては、曲がり発生量は無次元曲率r/ρで0.0008を超えている。なお、試験番号8は、焼付きが発生したので、加工後の長手方向の曲がり量測定は行わなかった。
【0021】
【発明の効果】
本発明の押出し加工方法によれば、押出し加工後の被加工材の曲がりを抑制できるので、断面形状精度の確保と真直性の確保を行うことが可能である。
【図面の簡単な説明】
【図1】孔ダイスを用いて直径D(mm)の鋼線を直径d(mm)に押出し加工する状況を示す図である。
【図2】押出し加工後の曲がり量に及ぼすダイスの出側テーパ角度の半角θの影響の一例を示す図である。
【図3】押出し加工後の曲がり量に及ぼすダイスのL/Eの影響の一例を示す図である。
【図4】押出し加工後の曲がり量に及ぼす減面率の影響の一例を示す図である。
【符号の説明】
L:ダイスの出側テーパ部長さ(mm)
E:ダイスのベアリング部長さ(mm)
θ:ダイスの出側テーパ角度の半角(゜)[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an extrusion method, and more particularly to a method of extruding a solid steel material such as a wire rod, a steel bar or a steel wire using a hole die.
[0002]
[Prior art]
Among solid steel materials having a circular cross-sectional shape, wire rods and steel bars are finished to desired dimensions (diameter) by “primary processing” such as rolling, and further, heat treatment called “secondary and tertiary processing” And cold extrusion, cold drawing, cold forging, cold cutting, etc. to form final parts such as shafts, rods and bolts widely used in automobiles, various industrial machines, etc. Is done.
[0003]
Many of the above parts require strict precision in the cross-sectional shape (roundness, external dimensions, etc.) after cold working and in the straightness of the material shaft. Of these, in the case of parts requiring particularly strict straightness in the material shaft portion, for example, in the case of a long-axis bolt or a shaft gear, it is often the case that cold extrusion is performed to ensure the cross-sectional shape accuracy and the straightness. . However, depending on the processing conditions at the time of extrusion processing, bending may occur in the longitudinal direction, and desired straightness accuracy may not be obtained, and it may be necessary to add a shape correction step.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above situation, and is a method of extruding a solid steel material having a circular cross section, that is, a wire, a steel bar or a steel wire using a hole die (hereinafter, also simply referred to as a die). An object of the present invention is to provide an extrusion method capable of suppressing the amount of bending of a workpiece to 0.0008 or less in a dimensionless curvature r / ρ described below.
[0005]
[Means for Solving the Problems]
The gist of the present invention is an extrusion method described below.
[0006]
In other words, “This is a method of extruding a solid steel material, in which the half angle θ (゜) of the exit taper angle satisfies the following equation (1), and the exit taper portion length L (mm) and the bearing portion length E (mm). (3) using a hole die that satisfies the following equation (2) at a processing rate that satisfies the following equation (3).
[0007]
0.02 ゜ ≦ θ ≦ 0.5 ゜ (1)
1 ≦ L / E ≦ 30 (2)
0.10D ≦ E (d / D) 2 ≦ 0.33D (3) ”.
[0008]
Here, D represents the diameter (mm) of the workpiece at the hole die entry side, and d represents the diameter of the workpiece exiting the hole die, that is, the diameter (mm) of the workpiece after extrusion.
[0009]
The present inventors carried out axial drawing by extrusion (hereinafter simply referred to as extrusion) under various conditions using a medium carbon steel wire as a test material, and measured the amount of bending in the longitudinal direction after the processing. As a result, the following findings were obtained.
(A) When a steel wire having a diameter D (mm) is extruded to a diameter d (mm), the bending amount in the longitudinal direction is determined by the length L (mm) of the tapered portion on the outgoing side as a die shape and the length E (mm) of the bearing portion. ), The output side taper angle 2θ, and therefore its half angle θ (゜). FIG. 1 is a diagram showing a situation in which a steel wire having a diameter D (mm) is extruded to a diameter d (mm) using a die having the shape of L, E, and θ.
[0010]
(B) The amount of bending in the longitudinal direction can be suppressed by adjusting the area reduction rate of the extrusion process.
[0011]
Therefore, further, extrusion processing was performed under various conditions using various alloy steel wires and stainless steel wires as test materials, and the amount of bending in the longitudinal direction after the processing was measured. As a result, it was confirmed that the above (a) and (b) also hold when alloy steel wires or stainless steel wires are used as test materials.
[0012]
The present invention has been completed based on the above findings.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, each requirement of the present invention will be described.
Half angle θ of the exit taper angle of the die:
FIG. 2 shows an example of the effect of the half angle θ (゜) of the exit taper angle of the die on the amount of bending after the extrusion, by extruding a S45C steel bar described in JIS G 4051 having a diameter D of 33 mm. This shows the situation in the case of processing to a diameter d of 30 mm.
[0014]
In addition, the amount of bending after the extrusion was evaluated by the dimensionless curvature r / ρ. The dimensionless curvature (r / ρ) is obtained by measuring the ridge coordinates of the extruded steel wire with a three-dimensional measuring device, calculating the curvature radius ρ (mm) from the coordinates, and then calculating the extruded steel wire. Is obtained by dividing the radius r (mm) of the above by the radius of curvature ρ.
As shown in an example in FIG. 2, when the half angle θ of the exit taper angle of the die exceeds 0.5 °, the amount of bending after the extrusion process sharply increases, and the value of the dimensionless curvature r / ρ becomes 0. .0008. On the other hand, if the half angle θ of the exit taper angle of the die is smaller than 0.02 °, although the occurrence of bending can be suppressed, problems such as an increase in the extrusion load due to contact with the die and seizure with the die occur. Therefore, the half angle θ of the exit taper angle of the die is defined so as to satisfy the expression (1).
Ratio (L / E) between the length of the tapered portion on the exit side and the length of the bearing portion:
FIG. 3 shows an example of the effect of the L / E of the die on the amount of bending after the extrusion, and extruded an S45C steel bar described in JIS G 4051 having a diameter D of 33 mm to a diameter d of 30 mm. It shows the situation in the case. In FIG. 3 as well, the amount of bending after extrusion is shown by a dimensionless curvature r / ρ.
As shown in an example in FIG. 3, when the value of L / E is smaller than 1, the amount of bending after extrusion processing increases sharply, and the value of the dimensionless curvature r / ρ exceeds 0.0008. On the other hand, when the value of L / E exceeds 30, although the occurrence of bending can be suppressed, the size of the die itself becomes extremely large, which makes industrial application difficult. Therefore, the value of L / E, which is the ratio of the length of the exit side taper portion to the length of the bearing portion, is defined so as to satisfy the above equation (2).
Processing rate:
FIG. 4 shows an example of the effect of the working ratio and the length of the die bearing on the amount of bending after the extrusion process, by using a bar steel of S45C described in JIS G 4051 having a diameter D of 33 mm and various bearing portion lengths E (mm 3) shows the situation when the diameter d is made 30 mm by extrusion with a die. In FIG. 4 as well, the amount of bending after the extrusion is shown by the dimensionless curvature r / ρ.
As shown in FIG. 4, E (d / D) is a product of the length E (mm) of the bearing portion and the square of the ratio (d / D) of the diameters of the steel wires after and before the extrusion. If the value of 2 is smaller than 0.10D or exceeds 0.33D, the value of the dimensionless curvature r / ρ will exceed 0.0008. Therefore, the working ratio of the extrusion process is defined so as to satisfy the above-mentioned formula (3).
[0015]
Hereinafter, the present invention will be described in more detail with reference to Examples.
[0016]
【Example】
Steels 1 and 2 having the chemical compositions shown in Table 1 were melted by an ordinary method. Steel 1 and Steel 2 are steels corresponding to S45C described in JIS G 4051 and SCr420 described in JIS G 4104, respectively. Note that Ti was included as an impurity.
[0017]
[Table 1]
These steels were made into billets by a conventional method, heated to 1230 ° C., hot forged into round bars having a diameter of 35 mm at a temperature of 1200 to 950 ° C., and then air-cooled to room temperature.
[0018]
The outer surface of the thus obtained round bar was cut to prepare a test piece having a diameter of 33 mm and a length of 1 m.
[0019]
Next, the test piece was cut, subjected to a zinc phosphate coating treatment in a usual manner, and extruded under various conditions using a 500-ton press so that the processed diameter became 30 mm. The amount of bending in the longitudinal direction was measured. Table 2 shows the conditions of the extrusion processing.
[0020]
[Table 2]
From Table 2, it is clear that in Test Nos. 1 to 5 according to the present invention, the amount of bending can be suppressed to 0.0008 or less in dimensionless curvature r / ρ.
On the other hand, in Test Nos. 6, 7, 9 and 10 out of the conditions specified in the present invention, the amount of bending exceeds 0.0008 in the dimensionless curvature r / ρ. In Test No. 8, since seizure occurred, the measurement of the amount of bending in the longitudinal direction after processing was not performed.
[0021]
【The invention's effect】
According to the extrusion processing method of the present invention, since the bending of the workpiece after the extrusion processing can be suppressed, it is possible to ensure the cross-sectional shape accuracy and the straightness.
[Brief description of the drawings]
FIG. 1 is a diagram showing a state in which a steel wire having a diameter D (mm) is extruded to a diameter d (mm) using a hole die.
FIG. 2 is a diagram illustrating an example of an effect of a half angle θ of a taper angle on an exit side of a die on a bending amount after extrusion processing.
FIG. 3 is a diagram showing an example of the effect of L / E of a die on the amount of bending after extrusion.
FIG. 4 is a diagram showing an example of the effect of the area reduction rate on the amount of bending after extrusion.
[Explanation of symbols]
L: Outer side taper length of die (mm)
E: Die bearing length (mm)
θ: Half angle of die exit taper angle (゜)
Claims (1)
0.02゜≦θ≦0.5゜・・・(1)
1≦L/E≦30・・・(2)
0.10D≦E(d/D)2 ≦0.33D・・・(3)
ここで、Dは孔ダイス入り側における被加工材の直径(mm)、dは孔ダイス出側における被加工材の直径(mm)である。This is a method of extruding a solid steel material, wherein a half angle θ (゜) of an outlet side taper angle satisfies the following expression (1), and a relationship between an outlet side taper portion length L (mm) and a bearing portion length E (mm). An extrusion method characterized by processing using a hole die having a ratio satisfying the following expression (2) at a processing rate satisfying the following expression (3).
0.02 ゜ ≦ θ ≦ 0.5 ゜ (1)
1 ≦ L / E ≦ 30 (2)
0.10D ≦ E (d / D) 2 ≦ 0.33D (3)
Here, D is the diameter (mm) of the workpiece on the entrance side of the hole die, and d is the diameter (mm) of the workpiece on the exit side of the hole die.
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JP5363395B2 (en) * | 2010-03-30 | 2013-12-11 | 株式会社神戸製鋼所 | Extrusion method and extrusion die for aluminum bar |
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