JP5802901B2 - Forging mold - Google Patents
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- JP5802901B2 JP5802901B2 JP2011085059A JP2011085059A JP5802901B2 JP 5802901 B2 JP5802901 B2 JP 5802901B2 JP 2011085059 A JP2011085059 A JP 2011085059A JP 2011085059 A JP2011085059 A JP 2011085059A JP 5802901 B2 JP5802901 B2 JP 5802901B2
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この発明は、例えば、ねじの頭部などを圧造する際に用いられる圧造金型に関する。 The present invention relates to a forging die used when forging a head portion of a screw, for example.
従来、十字穴付きねじ等のねじ切り前の部品は、圧造工具（上型）とダイス（下型）を用いて塑性加工の一種である圧造により製造されている。圧造工具先端の十字穴成形部は、圧造時に加圧軸方向へ圧縮応力が作用する。同時に、半径方向に膨張して被加工材料と密に接触し、続く除荷（圧造の逆工程で、圧造工具が加工開始点へ復帰する時）開始直後に、圧造工具の成形部が弾性回復することで被加工材料（圧造成形品の十字穴）が圧造工具に挟み込まれる。そのため、除荷中に圧造工具先端の十字穴成形部に加圧軸方向へ引張応力が発生するなど、応力が反復的に作用する。加えて、ねじ頭部形状の複雑化や寸法精度に対する要求が年々厳しくなっていることから、過酷な成形を余儀なくされ、工具寿命が低下するという問題があった。 Conventionally, parts before thread cutting such as a cross-recessed screw are manufactured by forging, which is a kind of plastic working, using a forging tool (upper die) and a die (lower die). The cross hole forming portion at the tip of the forging tool is subjected to compressive stress in the direction of the pressing axis during forging. At the same time, it expands in the radial direction and comes into close contact with the work material. Immediately after the start of subsequent unloading (when the forging tool returns to the machining start point in the reverse process of forging), the forming part of the forging tool recovers elastically. By doing so, the material to be processed (cross hole of the forged molded product) is sandwiched between the forging tools. For this reason, stress is repeatedly applied to the cross hole forming portion at the tip of the forging tool during unloading, for example, tensile stress is generated in the direction of the pressure axis. In addition, since the requirements for the complexity of the screw head shape and the dimensional accuracy have become stricter year by year, there has been a problem that strict molding is forced and the tool life is reduced.
そこで、このような問題に対処した従来技術を検討した結果、表面コーティングにより工具表面に硬質層を形成する方法（特許文献１，２）、また、特殊な熱処理により工具寿命を向上させる方法（特許文献３，４）を見出すことができた。 Therefore, as a result of studying the prior art that addresses such problems, a method of forming a hard layer on the surface of the tool by surface coating (Patent Documents 1 and 2), and a method of improving the tool life by a special heat treatment (patent) Documents 3 and 4) were found.
ところが、いずれの方法においても、工具表面硬度の向上による摩耗寿命対策を目的としており、通常の工具製作に加えて特殊処理を施す必要があり、工具製造コストが高騰するという不都合があった。 However, any of the methods is intended to prevent wear life by improving the tool surface hardness, and it is necessary to perform special processing in addition to the normal tool manufacturing, resulting in an increase in tool manufacturing costs.
圧造工具の工具寿命の低下は、圧造工具の交換回数が増えるので、その交換費用の増大を招き、また、圧造機の連続運転ができなくなり、生産効率が低下する原因にもなっていた。 The reduction in the tool life of the forging tool increases the number of times the forging tool is replaced, which increases the cost of replacement, and the continuous operation of the forging machine cannot be performed, resulting in a decrease in production efficiency.
このため、出願人は、「鍛造工具の設計方法及び鍛造工具」（特許第４４２８５８１号）及び「圧造工具」（特許第４６０１０１７号）を発明し、圧造工具内部に空間を設け、圧造工具の押圧部の微小な弾性変形を積極的に促進し、たわますことで圧造と除荷時の疲労破壊部の応力振幅を低下させることで圧造工具の疲労破壊を抑制し、耐久性の向上と長時間の連続使用を可能とした。すなわち、圧造工具に敢えて剛性の弱い部分を設けたことが特徴である。 Therefore, the applicant has invented the “forging tool design method and forging tool” (Patent No. 4428581) and the “forging tool” (Patent No. 4601007), providing a space inside the forging tool, and pressing the forging tool. By actively accelerating minute elastic deformation of the part and bending it, the stress amplitude of the fatigue fracture part at the time of forging and unloading is reduced to suppress fatigue fracture of the forging tool, improving durability and lengthening. Allows continuous use of time. That is, the forging tool is characterized in that it has a part with weak rigidity.
しかし、出願人が提案した空間を設ける疲労破壊の抑制策のみでは、今後、鋼等の高強度素材を用いたねじ圧造へ展開する場合、発生する応力が増大するため、疲労破壊部の応力振幅を低下させる微小な弾性変形の発現の制御に限界が生じるものと推察される。そこで、圧造工具内部に空間を設けない構成にて、圧造と除荷時の疲労破壊部での応力振幅の低減策が必要となる。 However, only the fatigue fracture suppression measures proposed by the applicant for the fatigue fracture suppression will cause an increase in the stress generated when developing to screw forging using high strength materials such as steel. It is inferred that there is a limit to the control of the development of minute elastic deformation that lowers. Therefore, it is necessary to take a measure for reducing the stress amplitude at the fatigue fracture portion during forging and unloading with a configuration in which no space is provided inside the forging tool.
この発明は、以上の実情に鑑みてなされたもので、安価で簡易な構成で、圧造工具の疲労破壊を抑制し、長時間の連続使用を可能とし、さらなる高強度素材のねじ圧造への適用を可能とする圧造金型を提供することを目的とする。 This invention has been made in view of the above circumstances, and is capable of suppressing fatigue fracture of a forging tool with a low-cost and simple configuration, enabling continuous use for a long time, and applying it to screw forging of a further high-strength material. An object of the present invention is to provide a forging die that makes it possible.
前記課題を解決し、かつ目的を達成するために、この発明は、以下のように構成した。 In order to solve the above-described problems and achieve the object, the present invention is configured as follows.
請求項１に記載の発明は、圧造にて成形される圧造品の成形穴を有するダイスと、
前記ダイスに対向して配置される一体構造の圧造工具とを備え、
前記ダイスの成形穴に加工前の素材を配置し、
前記圧造工具先端の押圧部により前記素材を押圧して前記圧造品を成形する
にあたり、
前記押圧部の弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧
造および徐荷時の圧造工具先端の十字穴成形部に作用する応力振幅を低減させる１つの底付き環状の溝空間または複数の底付き穴空間を、前記圧造工具先端の押圧部端面から圧造工具内部へ加圧軸と平行に形成したことを特徴とする圧造金型である。
The invention according to claim 1 is a die having a forming hole of a forged product formed by forging,
A monolithic forging tool disposed opposite to the die,
Place the raw material in the forming hole of the die,
In forming the forged product by pressing the material by the pressing portion at the tip of the forging tool,
One bottomed annular shape that positively promotes elastic deformation of the pressing portion and reduces the stress amplitude acting on the cross hole forming portion at the tip of the forging tool during forging and unloading by bending in the pressing axis direction. The forging die is characterized in that a groove space or a plurality of bottomed hole spaces are formed in parallel to the pressing shaft from the pressing portion end face of the forging tool tip to the inside of the forging tool.
請求項２に記載の発明は、前記１つの底付き環状の溝空間の溝内側輪郭が、ねじ頭部直径より大きく、かつ前記溝空間の溝外側輪郭が、前記圧造工具の外径より小さいことを特徴とする請求項１に記載の圧造金型である。 According to a second aspect of the present invention, the groove inner contour of the one bottomed annular groove space is larger than the screw head diameter, and the groove outer contour of the groove space is smaller than the outer diameter of the forging tool. The forging die according to claim 1.
請求項３に記載の発明は、前記１つの底付き環状の溝空間に、固体の充填材料を挿入し、前記溝空間より中心軸側の押圧部が、加圧時に加圧軸方向に対する垂直方向へのたわみを抑制することを特徴とする請求項１に記載の圧造金型である。 According to a third aspect of the present invention, a solid filling material is inserted into the one annular groove space with a bottom , and the pressing portion closer to the central axis than the groove space is perpendicular to the pressure axis direction during pressurization. The forging die according to claim 1, wherein the bending die is suppressed.
請求項４に記載の発明は、前記固体の充填材料のヤング率が、前記圧造工具のヤング率と同値かそれより低いことを特徴とする請求項３に記載の圧造金型である。 The invention according to claim 4 is the forging die according to claim 3 , wherein the Young's modulus of the solid filling material is equal to or lower than the Young's modulus of the forging tool.
請求項５に記載の発明は、前記複数の底付き穴空間を環状に配置し、前記複数の底付き穴空間の輪郭と接して形成される内接円直径が、ねじ頭部直径より大きく、かつ前記複数の底付き穴空間の輪郭と接して形成される外接円直径が、圧造工具の外径より小さいことを特徴とする請求項１に記載の圧造金型である。 The invention according to claim 5 , wherein the plurality of bottomed hole spaces are arranged in an annular shape, and an inscribed circle diameter formed in contact with an outline of the plurality of bottomed hole spaces is larger than a screw head diameter, The forging die according to claim 1, wherein a circumscribed circle diameter formed in contact with the contours of the plurality of bottomed hole spaces is smaller than an outer diameter of the forging tool.
請求項６に記載の発明は、前記複数の底付き穴空間に、固体の充填材料を挿入し、前記複数の底付き穴空間の配置の中心軸側の押圧部が、加圧時に加圧軸方向に対する垂直方向へのたわみを抑制することを特徴とする請求項１に記載の圧造金型である。 Invention of claim 6, the plurality of bottomed holes space, inserting the filling material of the solid, the pressing portion of the central axis side of the arrangement of the plurality of bottomed holes space, pressing axis when pressurized The forging die according to claim 1, wherein deflection in a direction perpendicular to the direction is suppressed.
請求項７に記載の発明は、前記固体の充填材料のヤング率が、前記圧造工具のヤング率と同値かそれより低いことを特徴とする請求項６に記載の圧造金型である。 The invention according to claim 7, the Young's modulus of the filler material of the solid, it is heading die of claim 6, wherein the lower than or Young's modulus equivalent to the heading tool.
前記構成により、この発明は、以下のような効果を有する。 With the above configuration, the present invention has the following effects.
この発明では、ダイスに対向して配置される一体構造の圧造工具を備え、圧造工具先端の押圧部により素材を押圧して圧造品を成形するにあたり、圧造工具先端の押圧部の弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧造および除荷時の圧造工具先端の十字穴成形部に作用する応力振幅を低減させる１つの底付き環状の溝空間または複数の底付き穴空間を、圧造工具先端の押圧部端面から圧造工具内部へ加圧軸と平行に形成し、また円筒状の圧造工具と、その内部に十字穴成形部が付帯した円柱状の圧造工具を挿入する二体構造としたことで、円柱状の圧造工具の押圧部の弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧造および除荷時の圧造工具先端の十字穴成形部に作用する応力振幅を低減させる構成であり、安価で簡易な構成で、加工回数が増大しても圧造工具の疲労破壊を抑制し、長時間の連続使用を可能とし、さらなる高強度素材のねじ圧造への適用が可能となる。
According to the present invention, a forging tool having an integrated structure disposed opposite to a die is provided, and when the material is pressed by the pressing portion at the tip of the forging tool to form a forging product, the pressing portion at the tip of the forging tool is positively elastically deformed. One bottomed annular groove space or a plurality of bottomed holes that reduce the stress amplitude acting on the cross-hole forming part at the front end of the forging tool during forging and unloading by the acceleration in the pressing axis direction A space is formed in parallel to the pressing shaft from the end surface of the pressing portion at the tip of the pressing tool into the pressing tool, and a cylindrical pressing tool and a cylindrical pressing tool with a cross hole forming portion inserted therein are inserted. By adopting the two-body structure, the elastic deformation of the pressing part of the cylindrical forging tool is positively promoted, and the cross-hole forming part at the tip of the forging tool at the time of forging and unloading by deflection in the pressing axis direction. It is a configuration that reduces the applied stress amplitude. Inexpensive and simple configuration, the number of manipulations suppresses the fatigue failure of forging tools be increased, for long time continuous use and then, it is possible to apply the screw heading further higher strength material.
なお、応力集中部を予め分割する二体型の工具として、特開２０００−６２７や、同じく二体型のダイスとして、特開平１−１９７０２９、特開平６−１９８３８１、特開２００６−２６７０９などがある。しかし、これらの技術は、応力集中する部位か、その近辺部位を分割の起点にする技術であり、この発明のように、応力集中とは関係のない部位を分割し、わざとたわますことで破壊部での応力振幅を低減する二体型の圧造工具構造では、そもそも設計思想が全く異なる。また、応力集中部か、その近辺部位を分割する従来技術では、分割部が加圧時にわずかに開き、そこへ材料が流入することでバリ（欠陥）が発生するが、この発明では、分割部位は材料と接触しないのでバリは発生しないなど優位性がある。 As a two-piece tool for dividing the stress concentration portion in advance, there are JP-A 2000-627, and as two-piece dies, there are JP-A 1-197029, JP-A-6-198381, JP-A 2006-26709, and the like. However, these technologies are technologies that use the part where stress is concentrated or the vicinity of the part as the starting point of the division, and like this invention, the part which is not related to the stress concentration is divided and it is bent on purpose. In the two-piece forging tool structure that reduces the stress amplitude at the fractured portion, the design philosophy is completely different. Moreover, in the prior art that divides the stress concentration part or its vicinity, the dividing part opens slightly during pressurization, and the material flows into the burrs (defects). Has the advantage of not generating burrs because it does not contact the material.
以下、この発明の圧造金型の実施の形態について説明する。この実施の形態はねじの冷間圧造金型であり、この発明の好ましい形態を示すものであるが、この発明はこれに限定されない。 Hereinafter, embodiments of the forging die according to the present invention will be described. Although this embodiment is a cold forging die of a screw and shows a preferred embodiment of the present invention, the present invention is not limited to this.
［第１の実施の形態］
この発明の第１の実施の形態を、図１乃至図１５に基づいて説明する。ねじの冷間圧造は、円柱素材から中間形状を成形する予備成形と、十字穴を持つ頭部を成形する主成形の２工程からなる。
[First Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. The cold forging of screws consists of two steps: preforming for forming an intermediate shape from a cylindrical material and main forming for forming a head having a cross hole.
図１に１／４カットモデルで示すとおり、予備成形に用いる冷間圧造用予備成形金型１００は、円柱素材を挿入するための穴１１０ａを有するダイス１１０と、このダイス１１０に対向して配置されるホルダー１２０と、このホルダー１２０に摺動可能に設けられた予備成形工具１２１を備えている。ホルダー１２０の成形穴１２０ａは、予備成形品４０の頭部を成形する形状である。ダイス１１０の穴１１０ａの下方には、ノックアウトピン１１１が摺動可能に設けられている。 As shown by a 1/4 cut model in FIG. 1, a cold forging preforming mold 100 used for preforming is arranged with a die 110 having a hole 110 a for inserting a columnar material and facing the die 110. Holder 120 and a preforming tool 121 slidably provided on the holder 120. The forming hole 120a of the holder 120 has a shape for forming the head of the preform 40. A knockout pin 111 is slidably provided below the hole 110a of the die 110.
圧造の予備成形は、ダイス１１０の円柱素材を挿入する穴１１０ａに、予備成形後は予備成形品４０となる円柱素材を配置し、ダイス１１０の上にホルダー１２０を接触させ、予備成形工具１２１を下方へ摺動して予備成形工具１２１の押圧部１２１ａにより円柱素材を押圧して予備成形品４０を成形する。予備成形中は、ホルダー１２０、ダイス１１０、ノックアウトピン１１１は、固定状態となっている。予備成形後に、ホルダー１２０と予備成形工具１２１を、加圧方向と逆方向に平行移動させ、さらに、工具交換機構（図示せず）により加圧軸上に残さないように移動させ、圧造機械の成形部には、予備成形品４０、ダイス１１０、ノックアウトピン１１１を残しておく。 For the preforming of the forging, the cylindrical material that becomes the preformed product 40 after the preliminary molding is placed in the hole 110a into which the cylindrical material of the die 110 is inserted, the holder 120 is brought into contact with the die 110, and the preliminary molding tool 121 is placed. The preform 40 is formed by sliding downward and pressing the cylindrical material by the pressing portion 121 a of the preforming tool 121. During the preliminary molding, the holder 120, the die 110, and the knockout pin 111 are in a fixed state. After the preforming, the holder 120 and the preforming tool 121 are moved in parallel in the direction opposite to the pressing direction, and further moved so as not to remain on the pressing shaft by a tool changing mechanism (not shown). The preform 40, the die 110, and the knockout pin 111 are left in the molding portion.
図２に１／４カットモデルで示すとおり、主成形に用いる冷間圧造金型１は、図１の予備成形と同じダイス１１０と、このダイス１１０に対向して配置される圧造工具３０とを備えている。ダイス１１０の穴１１０ａには、図１において予備成形された予備成形品が残っており、圧造工具３０の成形穴３０ａ１は、圧造品４１の頭部を成形する形状であり、突起３０ａ２は、圧造品頭部の十字穴を成形する形状である。圧造工具３０の押圧部３０ａにより予備成形品を押圧して圧造品４１を成形し、この実施の形態では、突起３０ａ２により十字穴付ねじの十字穴を成形する。ここで、図２中に疲労破壊部２００を図示しておく。 As shown by a 1/4 cut model in FIG. 2, the cold forging die 1 used for the main forming includes the same die 110 as the preforming in FIG. 1 and the forging tool 30 disposed to face the die 110. I have. The preform 110 preformed in FIG. 1 remains in the hole 110a of the die 110, the molding hole 30a1 of the forging tool 30 has a shape for molding the head of the forging 41, and the protrusion 30a2 is forged. It is a shape that forms a cross hole in the product head. The preformed product is pressed by the pressing portion 30a of the forging tool 30 to form the forged product 41. In this embodiment, the cross hole of the cross hole screw is formed by the protrusion 30a2. Here, the fatigue fracture portion 200 is illustrated in FIG.
圧造の主成形は、図１の予備成形後に圧造機械の成形部に残しておいたダイス１１０、予備成形品４０、ノックアウトピン１１１を用いて、それらに対向して圧造工具３０を配置し、圧造工具３０を作動して押圧部３０ａにより予備成形品４０を押圧して圧造品４１を成形する。主成形中は、ダイス１１０、ノックアウトピン１１１は、固定状態となっている。圧造工具３０を加圧方向と逆方向に平行移動（この動作を除荷と言う）させ、さらに、ノックアウトピン１１１を加圧方向と逆方向へ摺動して圧造品４１を取り出す。 The main forming of the forging is performed by using the die 110, the preform 40, and the knockout pin 111 that are left in the forming portion of the forging machine after the preforming shown in FIG. The tool 30 is actuated to press the preformed product 40 by the pressing portion 30a to form the forged product 41. During main molding, the die 110 and the knockout pin 111 are in a fixed state. The forging tool 30 is moved in parallel in the direction opposite to the pressing direction (this operation is called unloading), and the knockout pin 111 is slid in the direction opposite to the pressing direction to take out the forging product 41.
圧造品４１は、図３に示すように、ねじ転造される前のねじ部品であり、ねじ転造される軸部４１ａと、頭部４１ｂとを有する。圧造工具３０の押圧部３０ａの突起３０ａ２を、軸心で十字状に突出する形状にすることで、頭部４１ｂに十字穴４１ｂ１が形成される。 As shown in FIG. 3, the forged product 41 is a screw part before being thread-rolled, and includes a shaft portion 41a and a head portion 41b that are thread-rolled. A cross hole 41b1 is formed in the head 41b by forming the protrusion 30a2 of the pressing portion 30a of the forging tool 30 into a shape that protrudes in a cross shape with an axial center.
圧造工具３０の内部には、図４に１／４カットモデルで示すように、冷間圧造の際に、圧造工具３０の押圧部３０ａの弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧造および除荷時の圧造工具先端の十字穴成形部に作用する応力振幅を低減させる円筒状の溝空間５０が、圧造工具先端の押圧部３０ａの押圧部端面３０ａ１から圧造工具内部へ加圧軸と平行に形成されている。 In the forging tool 30, as shown by a ¼ cut model in FIG. 4, during cold forging, elastic deformation of the pressing portion 30 a of the forging tool 30 is positively promoted in the pressing axis direction. The cylindrical groove space 50 for reducing the stress amplitude acting on the cross hole forming portion at the tip of the forging tool during forging and unloading due to the bending of the inner portion of the pressing tool from the pressing portion end surface 30a1 of the pressing portion 30a at the tip of the forging tool. It is formed parallel to the pressure axis.
図４（ａ）の実施の形態では、溝空間５０の内形と外形が圧造工具３０の外周形状と相似となる円筒形状であり、圧造工具３０の押圧方向において、溝空間５０の位置が圧造時の衝撃による応力が到達する領域内であり、圧造工具先端の押圧部３０ａがたわみやすい溝径と溝高さに形成される。図４（ｂ）の実施の形態では、溝空間５０が図４（ａ）の実施の形態と同様に形成され、この溝空間５０に充填材料５１を挿入し、充填材料５１のヤング率を、圧造工具３０のヤング率より低く設定した構成である。圧造工具３０は、高速度鋼である。 In the embodiment of FIG. 4A, the inner shape and outer shape of the groove space 50 are cylindrical shapes that are similar to the outer peripheral shape of the forging tool 30, and the position of the groove space 50 is forging in the pressing direction of the forging tool 30. In the region where the stress due to the impact reaches, the pressing portion 30a at the tip of the forging tool is formed with a groove diameter and a groove height that are easy to bend. In the embodiment of FIG. 4B, the groove space 50 is formed in the same manner as the embodiment of FIG. 4A, and the filling material 51 is inserted into the groove space 50, and the Young's modulus of the filling material 51 is The configuration is set lower than the Young's modulus of the forging tool 30. The forging tool 30 is high-speed steel.
図４（ａ），（ｂ）の実施の形態の溝空間５０は、圧造工具３０の押圧部３０ａの押圧部端面３０ａ１から始まり、溝空間５０の最小内径は、十字状に突出する形状の十字突起３０ａ２の仮想外径より大きく、圧造工具３０の外径の半分である。また、溝空間５０の深さＬは、圧造工具３０の全長の３分の１であり、溝空間５０の幅Ｄは、製作の容易性を考慮し、０．５〜２．５ｍｍ程度である。この溝空間５０は、旋削、放電加工等により製作される。 The groove space 50 in the embodiment of FIGS. 4A and 4B starts from the pressing portion end face 30a1 of the pressing portion 30a of the forging tool 30, and the minimum inner diameter of the groove space 50 is a cross having a shape protruding in a cross shape. It is larger than the virtual outer diameter of the protrusion 30a2 and is half the outer diameter of the forging tool 30. The depth L of the groove space 50 is one third of the entire length of the forging tool 30, and the width D of the groove space 50 is about 0.5 to 2.5 mm in consideration of ease of manufacture. . The groove space 50 is manufactured by turning, electric discharge machining, or the like.
この主成形に用いる冷間圧造金型１では、図２に示すように、圧造工具３０を摺動して圧造工具３０の押圧部３０ａにより予備成形品４０を押圧し塑性加工し、十字穴４１ｂ１を有する圧造品４１を冷間圧造する。この圧造品４１を成形する際に、図４（ａ）の実施の形態では、圧造工具３０の内部に、圧造工具３０の押圧部３０ａの弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧造および除荷時の圧造工具先端の十字穴成形部の疲労破壊部２００に作用する応力振幅を低減させる円筒状の溝空間５０を、圧造工具３０の押圧部３０ａの押圧部端面３０ａ１から圧造工具内部へ加圧軸と平行に形成したことで、安価で簡易な構成で、加工回数が増大しても図２の疲労破壊部２００の疲労破壊を抑制し、長時間の連続使用を可能とし、さらなる高強度素材のねじ圧造への適用が可能となる。 In the cold forging die 1 used for the main forming, as shown in FIG. 2, the forging tool 30 is slid and the preform 40 is pressed by the pressing portion 30a of the forging tool 30 to be plastically processed, and the cross hole 41b1 is formed. The forged product 41 having the above is cold forged. When the forged product 41 is formed, in the embodiment of FIG. 4A, the elastic deformation of the pressing portion 30 a of the forging tool 30 is positively promoted inside the forging tool 30 in the pressurizing axis direction. The cylindrical groove space 50 that reduces the stress amplitude acting on the fatigue fracture portion 200 of the cross hole forming portion at the tip of the forging tool at the time of forging and unloading due to the bending of the pressing portion 30a of the pressing portion 30a of the forging tool 30 Since it is formed in parallel with the pressing shaft from 30a1 to the inside of the pressing tool, the fatigue failure of the fatigue failure part 200 in FIG. This makes it possible to apply higher strength materials to screw forging.
図４（ａ）の実施形態の圧造工具３０は、円筒形状の溝空間５０の溝内径と高さの組み合わせで、圧造および除荷時の圧造工具先端の十字穴成形部の疲労破壊部２００に作用する応力振幅を制御できる。また、図４（ｂ）の実施の形態では、円筒形状の溝空間５０に、溝空間と同形状の充填材料５１を挿入した。充填材料５１により、加圧時の圧造工具３０の押圧部３０ａの微小な曲がりによる圧造品の欠陥発生を抑制できる。さらに、充填材料５１のヤング率を、圧造工具３０の押圧部３０ａのヤング率より低くすることで、押圧部３０ａの弾性変形を積極的に促進し、たわみにより圧造および除荷時の圧造工具先端の十字穴成形部の疲労破壊部２００に作用する応力振幅を抑制できる。 The forging tool 30 of the embodiment of FIG. 4A is a combination of the groove inner diameter and height of the cylindrical groove space 50, and is used as a fatigue fracture portion 200 of the cross hole forming portion at the tip of the forging tool during forging and unloading. The acting stress amplitude can be controlled. Further, in the embodiment of FIG. 4B, the filling material 51 having the same shape as the groove space is inserted into the cylindrical groove space 50. The filling material 51 can suppress the occurrence of defects in the forged product due to the slight bending of the pressing portion 30a of the forging tool 30 during pressurization. Further, by making the Young's modulus of the filling material 51 lower than the Young's modulus of the pressing portion 30a of the pressing tool 30, the elastic deformation of the pressing portion 30a is actively promoted, and the leading end of the pressing tool at the time of pressing and unloading by deflection. The stress amplitude acting on the fatigue fracture portion 200 of the cross hole molded portion can be suppressed.
図５は、冷間圧造による主成形時の有限要素法解析モデルを示す。圧造工具は弾性体とし、３０，０００要素に分割した。この圧造工具は、高速度鋼であり、ヤング率２２８０００ＭＰａ、ポアソン比０．２８である。素材は、剛塑性体とし、解析のために２０，０００要素に分割した。主成形時の素材は、予め解析しておいた予備成形後の加工品とした。 FIG. 5 shows a finite element method analysis model at the time of main forming by cold forging. The forging tool was an elastic body and divided into 30,000 elements. This forging tool is high-speed steel and has a Young's modulus of 228000 MPa and a Poisson's ratio of 0.28. The material was a rigid plastic and was divided into 20,000 elements for analysis. The raw material at the time of the main molding was a processed product after preliminary molding that was analyzed in advance.
次に、圧造および除荷時の圧造工具先端の十字穴成形部の疲労破壊部２００に作用する応力振幅の有限要素解析結果（効果）を、図６乃至図８に基づいて説明する。図６は、円筒状の溝空間の深さ４ｍｍの場合の、応力振幅に及ぼす溝空間内径の影響を説明する図である。溝幅を１ｍｍとし、溝空間に溝空間と同形状の充填材料を挿入した。なお、充填材料は圧造工具と同じ材質で、高速度鋼である。溝空間の内径を変化させて、圧造工具先端の十字穴成形部の疲労破壊部２００に作用する応力振幅を、有限要素法を用いた数値解析により求めた。図６に示すとおり、溝空間を形成することで、溝空間を設けない従来の圧造工具と比較して、圧造工具の押圧部は、溝空間がいずれの設定内径であっても剛性が低下し、たわみやすくなり、疲労破壊に影響を及ぼす応力振幅が低下している。また、溝空間の深さ４ｍｍの場合、溝空間の内径が大きくなるほど応力振幅は低下する。 Next, the finite element analysis results (effects) of the stress amplitude acting on the fatigue fracture portion 200 of the cross hole forming portion at the tip of the forging tool during forging and unloading will be described based on FIGS. 6 to 8. FIG. 6 is a diagram for explaining the influence of the groove space inner diameter on the stress amplitude when the depth of the cylindrical groove space is 4 mm. The groove width was 1 mm, and a filling material having the same shape as the groove space was inserted into the groove space. The filling material is the same material as the forging tool and is high speed steel. By changing the inner diameter of the groove space, the stress amplitude acting on the fatigue fracture portion 200 of the cross hole forming portion at the tip of the forging tool was determined by numerical analysis using a finite element method. As shown in FIG. 6, by forming the groove space, the pressing portion of the forging tool has a reduced rigidity regardless of the set inner diameter as compared with a conventional forging tool that does not provide the groove space. The stress amplitude that affects the fatigue fracture is reduced. Further, when the groove space has a depth of 4 mm, the stress amplitude decreases as the groove space has an increased inner diameter.
図７は、円筒状の溝空間の内径６ｍｍの場合の、応力振幅に及ぼす溝空間深さの影響を説明する図である。溝幅を１ｍｍとし、溝空間に溝空間と同形状の充填材料を挿入した。圧造工具と充填材料の材質は、図６と同様である。溝空間の深さを変化させて、圧造工具先端の十字穴成形部の疲労破壊部２００に作用する応力振幅を、有限要素法を用いた数値解析により求めた。図６に示すとおり、溝空間を形成することで、溝空間を設けない従来の圧造工具と比較して、圧造工具の押圧部は、溝空間がいずれの設定深さであっても剛性が低下し、たわみやすくなり、疲労破壊に影響を及ぼす応力振幅が低下している。また、溝空間の深さが４ｍｍで、応力振幅は最低値を示し、溝空間の深さが４〜８ｍｍの範囲では従来の圧造工具の応力振幅より低下した。 FIG. 7 is a diagram for explaining the influence of the groove space depth on the stress amplitude when the inner diameter of the cylindrical groove space is 6 mm. The groove width was 1 mm, and a filling material having the same shape as the groove space was inserted into the groove space. The material of the forging tool and the filling material is the same as in FIG. By changing the depth of the groove space, the stress amplitude acting on the fatigue fracture portion 200 of the cross hole forming portion at the tip of the forging tool was determined by numerical analysis using a finite element method. As shown in FIG. 6, by forming the groove space, the pressing portion of the forging tool is less rigid regardless of the set depth of the groove space compared to a conventional forging tool that does not provide the groove space. However, it becomes easy to bend, and the stress amplitude which affects fatigue fracture is reduced. Further, the depth of the groove space was 4 mm, and the stress amplitude showed the lowest value. When the depth of the groove space was in the range of 4 to 8 mm, it was lower than the stress amplitude of the conventional compacting tool.
図８は、応力振幅に及ぼす充填材料の影響を説明する図であり、円筒状の溝空間の内径は６ｍｍ、深さは４ｍｍで、溝空間に充填材料を挿入しない場合と、溝空間に充填材料を挿入し、充填材料の材質を高速度鋼（ＳＫＨ材）、高速度鋼よりヤング率が低い炭素鋼（Ｓ４５Ｃ）の場合について、圧造工具先端の十字穴成形部の疲労破壊部２００に作用する応力振幅を、有限要素法を用いた数値解析により求めた。圧造工具は高速度鋼とした。溝空間に充填材料を挿入しない場合と、溝空間に充填材料を挿入した場合ともに、溝空間を設けない従来の圧造工具と比較して、疲労破壊に影響を及ぼす応力振幅が低下している。溝空間に充填材料を挿入しない場合より溝空間に充填材料を挿入した場合の方が、疲労破壊に影響を及ぼす応力振幅が低下し、充填材料のヤング率は、圧造工具３０のヤング率より低い方が疲労破壊に影響を及ぼす応力振幅が低下した。 FIG. 8 is a diagram for explaining the influence of the filling material on the stress amplitude. The cylindrical groove space has an inner diameter of 6 mm and a depth of 4 mm. When the filling material is not inserted into the groove space, the groove space is filled. Inserting material and acting on the fatigue fracture part 200 of the cross hole forming part at the tip of the forging tool in the case of high speed steel (SKH material) and carbon steel (S45C) whose Young's modulus is lower than that of the high speed steel. The stress amplitude to be obtained was obtained by numerical analysis using the finite element method. The forging tool was high speed steel. In both the case where the filling material is not inserted into the groove space and the case where the filling material is inserted into the groove space, the stress amplitude that affects fatigue fracture is lower than that of a conventional forging tool in which no groove space is provided. When the filling material is inserted into the groove space, the stress amplitude that affects fatigue fracture is lower than when the filling material is not inserted into the groove space, and the Young's modulus of the filling material is lower than the Young's modulus of the forging tool 30. The stress amplitude that affects fatigue fracture decreased.
次に、圧造工具３０に形成する溝空間５０の深さの極限状態を示す。極限とは、溝空間５０の深さＬを最大限（圧造具３０を貫通することになるため、必然的に二体型の圧造工具となる）とし、溝空間５０の幅Ｄを最小限（必然的に二体型となった圧造工具同士をすきま嵌めの状態とする）とする構成であり、それらの実施形態を、図９乃至図１１に示す。すなわち、請求項８の二体型の圧造工具は、請求項１の一体型の圧造工具の深さの最大限と溝幅の最小限を表現したものであるとも言える。図９は、溝空間５０の深さＬを最大限にし、溝空間５０の幅Ｄを最小限とする構成を示し、この構成は、図１０に示すように実施される。 Next, the limit state of the depth of the groove space 50 formed in the forging tool 30 is shown. The limit is that the depth L of the groove space 50 is maximized (because it passes through the forging tool 30, so that it is necessarily a two-piece forging tool), and the width D of the groove space 50 is minimized (necessarily) 9 to FIG. 11, and the embodiments thereof are shown in FIG. 9 to FIG. 11. That is, it can be said that the two-piece forging tool according to claim 8 expresses the maximum depth and the minimum groove width of the integrated forging tool according to claim 1. FIG. 9 shows a configuration in which the depth L of the groove space 50 is maximized and the width D of the groove space 50 is minimized, and this configuration is implemented as shown in FIG.
図９を実用的にした図１０の実施の形態では、円筒状の圧造工具６０と、その内部に十字穴成形部が付帯した円柱状の圧造工具７０を挿入する二体構造としたことで、円柱状の圧造工具７０の押圧部７０ｃの弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧造および除荷時の圧造工具先端の十字穴成形部に作用する応力振幅を低減させる構成である。円筒状の圧造工具６０の貫通孔６２は、下段孔６２ａと上段孔６２ｂとを有する段付き孔であり、円柱状の圧造工具７０は、下段部７０ａと上段部７０ｂとを有する。 In the embodiment of FIG. 10 in which FIG. 9 is put into practical use, a cylindrical forging tool 60 and a cylindrical forging tool 70 attached with a cross hole forming portion therein are formed into a two-body structure. The elastic deformation of the pressing portion 70c of the cylindrical forging tool 70 is actively promoted, and the stress amplitude acting on the cross hole forming portion at the tip of the forging tool during forging and unloading is reduced by the deflection in the pressing axis direction. It is the structure to make. The through hole 62 of the cylindrical forging tool 60 is a stepped hole having a lower step hole 62a and an upper step hole 62b, and the columnar forging tool 70 has a lower step portion 70a and an upper step portion 70b.
この円柱状の圧造工具７０の下段部７０ａを、円筒状の圧造工具６０の上段孔６２ｂから挿入して下段孔６２ａに位置させ、円柱状の圧造工具７０の上段部７０ｂを、上段孔６２ｂに位置させることで、円柱状の圧造工具７０の押圧部７０ｃの弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧造および除荷時の圧造工具先端の十字穴成形部に作用する応力振幅を低減させる。 The lower step portion 70a of the columnar forging tool 70 is inserted from the upper step hole 62b of the cylindrical forging tool 60 and positioned in the lower step hole 62a, and the upper step portion 70b of the columnar forging tool 70 is inserted into the upper step hole 62b. By locating, the elastic deformation of the pressing portion 70c of the cylindrical forging tool 70 is positively promoted, and acting on the cross hole forming portion at the tip of the forging tool at the time of forging and unloading by deflection in the pressing axis direction. To reduce the stress amplitude.
この円柱状の圧造工具７０は、上段部７０ｂの外径には特別な制限は無く、抜け落ち防止ができれば、直径は下段部７０ａより０．５ｍｍ大きい程度でよい。また、円柱状の圧造工具７０の上段部７０ｂの長さにも特別な制限は無く、上段部７０ｂの直径が下段部７０ａの直径と比較して十分に小さければ（０．５ｍｍ程度）、剛性に大きな変化はないため、円柱状の圧造工具７０の上段部７０ｂの長さは生産可能であり、圧造作業に支障とならない範囲内で決められる。 In the cylindrical forging tool 70, there is no particular restriction on the outer diameter of the upper step portion 70b, and the diameter may be about 0.5 mm larger than the lower step portion 70a as long as it can be prevented from falling off. Further, the length of the upper step portion 70b of the cylindrical forging tool 70 is not particularly limited. If the diameter of the upper step portion 70b is sufficiently smaller than the diameter of the lower step portion 70a (about 0.5 mm), the rigidity is increased. Therefore, the length of the upper step portion 70b of the cylindrical forging tool 70 can be produced and determined within a range that does not hinder the forging operation.
このように、円筒状の圧造工具６０に、円柱状の圧造工具７０を挿入し、円柱状の圧造工具７０の押圧部７０ｃの弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧造および除荷時の圧造工具先端の十字穴成形部に作用する応力振幅を低減させることで、安価で簡易な構成で、加工回数が増大しても長時間の連続使用を可能とし、さらなる高強度素材のねじ圧造への適用が可能となる。 In this way, the cylindrical forging tool 70 is inserted into the cylindrical forging tool 60, and the elastic deformation of the pressing portion 70c of the columnar forging tool 70 is positively promoted, and the deflection in the pressurizing axis direction is caused. By reducing the stress amplitude acting on the cross hole forming part at the tip of the forging tool during forging and unloading, it can be used continuously for a long time even if the number of machining operations is increased with an inexpensive and simple configuration. Application to high-strength material for screw forging becomes possible.
この円柱状の圧造工具７０は、下段部７０ａの外径を可変すると、圧造および除荷時の圧造工具先端の十字穴成形部に作用する応力振幅を制御できる。また、円筒状の圧造工具６０と円柱状の圧造工具７０の材質が、同一であることが好ましいが、円筒状の圧造工具６０のヤング率と、円柱状の圧造工具７０のヤング率を変化させることで、圧造および除荷時の圧造工具先端の十字穴成形部に作用する応力振幅を制御できる。 The cylindrical forging tool 70 can control the stress amplitude acting on the cross hole forming portion at the tip of the forging tool during forging and unloading by varying the outer diameter of the lower step portion 70a. The material of the cylindrical pressing tool 60 and the cylindrical pressing tool 70 is preferably the same, but the Young's modulus of the cylindrical pressing tool 60 and the Young's modulus of the cylindrical pressing tool 70 are changed. Thus, the stress amplitude acting on the cross hole forming portion at the tip of the forging tool during forging and unloading can be controlled.
また、円筒状の圧造工具６０が、下段部７０ａと上段部７０ｂとを有する段付形状であることで、除荷時の抜け落ち防止機能を有する。さらに、円筒状の圧造工具６０に、円柱状の圧造工具７０を圧入しないで挿入するから、円柱状の圧造工具７０が破壊したらこれのみを交換し、円筒状の圧造工具６０は、繰り返し使用できる。 Further, the cylindrical forging tool 60 has a stepped shape having a lower step portion 70a and an upper step portion 70b, thereby having a function of preventing a dropout during unloading. Further, since the columnar forging tool 70 is inserted into the cylindrical forging tool 60 without being press-fitted, when the columnar forging tool 70 is broken, only this is replaced, and the cylindrical forging tool 60 can be used repeatedly. .
図１１は、冷間圧造後の除荷時の有限要素法解析モデルを示し、ラムによって圧造工具を押し、圧造工具によって図５の圧造品である素材を押圧し、加工後、ダイスを固定し、圧造工具を上に引き抜くときに圧造工具の疲労破壊の要因となる引張り応力が発生する。この現象をモデル化した。圧造工具は解析のために３０，０００要素に分割した。図１１（ａ）の圧造工具は、従来型のものを用い、高速度鋼である。図１１（ｂ）の圧造工具は、圧造工具の押圧方向に沿って貫通孔を形成し、この貫通孔に円柱状の圧造工具を挿入し、円柱状の圧造工具の弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧造および除荷時の圧造工具先端の十字穴成形部に作用する応力振幅を低減させる。 FIG. 11 shows a finite element method analysis model at the time of unloading after cold forging, pressing the forging tool with a ram, pressing the material that is the forging product of FIG. 5 with the forging tool, and fixing the die after processing. When the forging tool is pulled upward, a tensile stress that causes fatigue failure of the forging tool is generated. This phenomenon was modeled. The forging tool was divided into 30,000 elements for analysis. The forging tool in FIG. 11 (a) is a conventional high-speed steel. The forging tool in FIG. 11B forms a through hole along the pressing direction of the forging tool, and a cylindrical forging tool is inserted into the through hole to actively promote elastic deformation of the columnar forging tool. Then, the deflection in the pressing axis direction reduces the stress amplitude acting on the cross hole forming portion at the tip of the forging tool during forging and unloading.
次に、圧造および除荷時の圧造工具先端の十字穴成形部の疲労破壊部２００に作用する応力振幅の有限要素解析結果（効果）を、図１２乃至図１５に基づいて説明する。図１２は応力振幅に及ぼす円柱状の圧造工具７０の下段部７０ａの直径の影響を説明する図であり、円筒状の圧造工具６０と円柱状の圧造工具７０は、同一材質で高速度鋼とし、円柱状の圧造工具７０の円筒状の圧造工具６０へ圧入しない（すきま嵌め）で挿入した。また、上段部７０ｂの直径は、下段部７０ａより０．５ｍｍ大きくした。円柱状の圧造工具７０の下段部７０ａの直径を変化させて疲労破壊部２００に作用する応力振幅を有限要素法を用いた数値解析により求めた。円柱状の圧造工具７０は、溝空間を設けない従来の圧造工具と比較して設定したいずれの直径でも剛性が低下し、たわみやすくなり、疲労破壊に影響を及ぼす応力振幅が低下している。 Next, the finite element analysis result (effect) of the stress amplitude acting on the fatigue fracture portion 200 of the cross hole forming portion at the tip of the forging tool at the time of forging and unloading will be described based on FIGS. FIG. 12 is a diagram for explaining the influence of the diameter of the lower step portion 70a of the columnar pressing tool 70 on the stress amplitude. The cylindrical pressing tool 60 and the columnar pressing tool 70 are made of the same material and are made of high-speed steel. The cylindrical forging tool 70 was inserted into the cylindrical forging tool 60 without being press-fitted (clearance fitting). Moreover, the diameter of the upper step part 70b was 0.5 mm larger than the lower step part 70a. The stress amplitude acting on the fatigue fracture portion 200 by changing the diameter of the lower step portion 70a of the cylindrical forging tool 70 was obtained by numerical analysis using a finite element method. The cylindrical forging tool 70 has a reduced rigidity at any diameter set as compared with a conventional forging tool that does not provide a groove space, is easily bent, and has a reduced stress amplitude that affects fatigue fracture.
この実施の形態の圧造工具の応力振幅は、円柱状の圧造工具７０の下段部７０ａの直径が、従来の圧造工具の直径（１２ｍｍ）の１／２で最低値を示し、直径４〜８ｍｍの範囲では、従来の圧造工具より応力振幅は低下する。円柱状の圧造工具７０の下段部７０ａの最小外径は、圧造品にバリ（欠陥）を生じさせないために、ねじ頭部最大直径以上である必要があり、最大外径は、円筒状の圧造工具６０を加工できる直径までとなる。 The stress amplitude of the forging tool according to this embodiment is such that the diameter of the lower step portion 70a of the cylindrical forging tool 70 is half the diameter (12 mm) of the conventional forging tool, and the minimum value is 4 to 8 mm. In the range, the stress amplitude is lower than that of the conventional heading tool. The minimum outer diameter of the lower step portion 70a of the columnar forging tool 70 needs to be equal to or larger than the maximum screw head diameter so as not to cause burrs (defects) in the forged product, and the maximum outer diameter is cylindrical forging. The diameter is such that the tool 60 can be machined.
図１３は、応力振幅に及ぼす円筒状の圧造工具６０と円柱状の圧造工具７０の挿入状態（圧入の有無と圧入の程度）の影響を説明する図であり、円筒状の圧造工具６０と円柱状の圧造工具７０は、同一材質で高速度鋼とし、円柱状の圧造工具７０の下段部７０ａの直径は、図１２で最も応力振幅が低下する６ｍｍとした。また、上段部７０ｂの直径は、下段部７０ａより０．５ｍｍ大きくした。円柱状の圧造工具７０を円筒状の圧造工具６０に圧入することで、円柱状の圧造工具７０の剛性が向上し、たわみ難くなるため、応力振幅は低下せず、圧入率が上昇すると共に疲労破壊に影響を及ぼす応力振幅は上昇する。すなわち、円柱状の圧造工具７０を円筒状の圧造工具６０に圧入しないで挿入し、円柱状の圧造工具７０の押圧部７０ｃの弾性変形を積極的に促進させると、圧造および除荷時の圧造工具先端の十字穴成形部の疲労破壊部２００に作用する応力振幅は低下する。 FIG. 13 is a diagram for explaining the influence of the insertion state of the cylindrical pressing tool 60 and the cylindrical pressing tool 70 (the presence or absence of pressing and the degree of pressing) on the stress amplitude. The columnar forging tool 70 is made of the same material and made of high-speed steel, and the diameter of the lower step portion 70a of the columnar forging tool 70 is 6 mm at which the stress amplitude decreases most in FIG. Moreover, the diameter of the upper step part 70b was 0.5 mm larger than the lower step part 70a. By pressing the cylindrical forging tool 70 into the cylindrical forging tool 60, the rigidity of the columnar forging tool 70 is improved and it becomes difficult to bend. Therefore, the stress amplitude does not decrease, the press-in rate increases, and fatigue occurs. The stress amplitude that affects fracture increases. That is, when the cylindrical forging tool 70 is inserted into the cylindrical forging tool 60 without being press-fitted, and the elastic deformation of the pressing portion 70c of the columnar forging tool 70 is positively promoted, forging during unloading and unloading is performed. The stress amplitude acting on the fatigue fracture portion 200 of the cross hole forming portion at the tip of the tool decreases.
図１４は、応力振幅に及ぼす円筒状の圧造工具６０のヤング率の影響を説明する図である。ここで、円柱状の圧造工具７０の下段部７０ａの直径は、図１２で最も応力振幅が低下する６ｍｍとし、円柱状の圧造工具７０を円筒状の圧造工具６０に圧入しないで挿入しており、円柱状の圧造工具７０の材質は、高速度鋼とした。また、円筒状の圧造工具６０の材質は、高速度鋼（ＳＫＨ材）、炭素鋼（Ｓ４５Ｃ）の場合について、圧造および除荷時の圧造工具先端の十字穴成形部の疲労破壊部２００に作用する応力振幅を有限要素法を用いた数値解析により求めた。この実施の形態では、円柱状の圧造工具７０を円筒状の圧造工具６０に圧入していないため、いずれのヤング率でもたわみ易くなり、従来の圧造工具と比較して疲労破壊に影響がある応力振幅は大幅に低下する。しかし、ヤング率が小さくなるとたわみ過ぎてしまい、かえって応力振幅が上昇することになる。したがって、円筒状の圧造工具６０と円柱状の圧造工具７０の材質が同一であると、たわみ過ぎることなく、応力振幅を低下することができるので好ましい。 FIG. 14 is a diagram for explaining the influence of the Young's modulus of the cylindrical forging tool 60 on the stress amplitude. Here, the diameter of the lower step portion 70a of the columnar forging tool 70 is 6 mm at which the stress amplitude is the lowest in FIG. 12, and the columnar forging tool 70 is inserted into the cylindrical forging tool 60 without being press-fitted. The material of the cylindrical forging tool 70 was high speed steel. In addition, when the material of the cylindrical forging tool 60 is high speed steel (SKH material) or carbon steel (S45C), it acts on the fatigue fracture portion 200 of the cross hole forming portion at the tip of the forging tool during forging and unloading. The stress amplitude was obtained by numerical analysis using the finite element method. In this embodiment, since the cylindrical forging tool 70 is not press-fitted into the cylindrical forging tool 60, any Young's modulus is easily deflected, and stress that has an effect on fatigue fracture as compared with a conventional forging tool. The amplitude is greatly reduced. However, if the Young's modulus becomes small, it will bend too much and the stress amplitude will increase. Therefore, it is preferable that the material of the cylindrical forging tool 60 and the columnar forging tool 70 is the same because the stress amplitude can be reduced without excessive deflection.
図１５は、圧造後の除荷時の解析結果（効果）を示し、図１５（ａ）は、直径１２ｍｍの従来型の圧造工具の押圧部の先端部分の最大主応力分布を示す縦断面図であり、図１５（ｂ）は直径４ｍｍの圧造工具の押圧部の先端部分の最大主応力分布を示す縦断面図であり、図１５（ｃ）は直径６ｍｍの圧造工具の押圧部の先端部分の最大主応力分布を示す縦断面図であり、図１５（ｄ）は直径８ｍｍの圧造工具の押圧部の先端部分の最大主応力分布を示す縦断面図であり、図１５（ｃ）〜図１５（ｄ）はパンチの円筒状の圧造工具６０と円柱状の圧造工具７０は同材質で圧入しないで挿入した。 FIG. 15 shows the analysis result (effect) at the time of unloading after forging, and FIG. 15 (a) is a longitudinal sectional view showing the maximum principal stress distribution of the tip portion of the pressing portion of a conventional forging tool having a diameter of 12 mm. FIG. 15B is a longitudinal sectional view showing the maximum principal stress distribution of the tip portion of the pressing portion of the pressing tool of 4 mm in diameter, and FIG. 15C is the tip portion of the pressing portion of the pressing tool of 6 mm in diameter. 15 (d) is a longitudinal sectional view showing the maximum principal stress distribution of the tip portion of the pressing portion of the forging tool having a diameter of 8 mm, and FIG. 15 (c) to FIG. In FIG. 15D, the cylindrical forging tool 60 and the columnar forging tool 70 were inserted with the same material without being press-fitted.
図１５（ｅ）は直径６ｍｍの圧造工具の押圧部の先端部分の最大主応力分布を示す縦断面図であり、円筒状の圧造工具６０と円柱状の圧造工具７０は同材質で、０．５％で圧入して挿入した。図１５（ｆ）は直径６ｍｍの圧造工具の押圧部の先端部分の最大主応力分布を示す縦断面図であり、円筒状の圧造工具６０と円柱状の圧造工具７０は同材質で、０．９％で圧入して挿入した。図１５（ｇ）は直径６ｍｍの圧造工具の押圧部の先端部分の最大主応力分布を示す縦断面図であり、円筒状の圧造工具６０の材質を円柱状の圧造工具７０よりヤング率が低いＳ４５Ｃとし、圧入しないで挿入した。 FIG. 15E is a longitudinal sectional view showing the maximum principal stress distribution at the tip of the pressing portion of the pressing tool having a diameter of 6 mm. The cylindrical pressing tool 60 and the columnar pressing tool 70 are made of the same material. It was press-fitted at 5% and inserted. FIG. 15 (f) is a longitudinal sectional view showing the maximum principal stress distribution at the tip of the pressing part of the pressing tool having a diameter of 6 mm. The cylindrical pressing tool 60 and the columnar pressing tool 70 are made of the same material and have a thickness of 0.2 mm. It was press-fitted at 9% and inserted. FIG. 15G is a longitudinal sectional view showing the maximum principal stress distribution at the tip of the pressing portion of the 6 mm diameter pressing tool. The material of the cylindrical pressing tool 60 is lower in Young's modulus than the cylindrical pressing tool 70. It was set as S45C and inserted without press-fitting.
円柱状の圧造工具７０の周縁よりも軸心で十字状に突出する先端面によって圧造品に十字穴が成形され、解析による圧造工具の最大主応力は、図１５（ｈ）に示すように、応力レンジ０〜８００（ＭＰａ）とし、図に示す５段階に分け表示している。すなわち、円柱状の圧造工具７０の最大主応力は、十字状に突出する先端面に対応する部分から円弧状に応力が分布し、十字状に突出する先端面に対応する部分が、５段階目の６４０〜８００（ＭＰａ）であり、最大主応力が最も大きくなっている。この応力が最も大きくなっている部分において円柱状の圧造工具７０における疲労破壊の要因となる。 As shown in FIG. 15 (h), a cross hole is formed in the forged product by the tip surface projecting in a cross shape in the axial center from the peripheral edge of the cylindrical forging tool 70. As shown in FIG. The stress range is 0 to 800 (MPa), and is divided into five stages shown in the figure. That is, the maximum principal stress of the cylindrical forging tool 70 is that the stress is distributed in an arc shape from the portion corresponding to the tip surface protruding in a cross shape, and the portion corresponding to the tip surface protruding in a cross shape is the fifth stage. 640 to 800 (MPa), and the maximum principal stress is the largest. In the part where this stress is the largest, it becomes a factor of fatigue failure in the cylindrical forging tool 70.
図１５（ａ）の従来型の圧造工具の押圧部の先端部分の最大主応力分布では、５段階目の６４０〜８００（ＭＰａ）の領域が大きいが、図１５（ｂ），（ｃ），（ｄ），（ｇ）の実施の形態の円柱状の圧造工具７０の先端部分の最大主応力分布では、５段階目の６４０〜８００（ＭＰａ）の領域が極端に小さくなっている。図１５（ｅ），（ｆ）の形態の円柱状の圧造工具７０の先端部分の最大主応力分布では、５段階目の６４０〜８００（ＭＰａ）の領域が小さくなっていない。 In the maximum principal stress distribution of the tip portion of the pressing portion of the conventional forging tool of FIG. 15 (a), the region of 640 to 800 (MPa) at the fifth stage is large, but FIG. 15 (b), (c), In the maximum principal stress distribution of the tip portion of the cylindrical forging tool 70 according to the embodiments (d) and (g), the region of 640 to 800 (MPa) at the fifth stage is extremely small. In the maximum principal stress distribution of the tip portion of the cylindrical forging tool 70 in the form of FIGS. 15E and 15F, the region of 640 to 800 (MPa) at the fifth stage is not small.
図１５（ｂ），（ｃ），（ｄ），（ｇ）では、円柱状の圧造工具７０の先端面を、周縁よりも軸心で突出する形状にし、この実施の形態で、圧造工具を摺動して円柱状の圧造工具７０により素材を押圧して圧造品を成形する際に、円筒状の圧造工具６０に円柱状の圧造工具７０を挿入し、円柱状の圧造工具７０の弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧造および除荷時の圧造工具先端の十字穴成形部に作用する応力振幅を低減させることができた。 15 (b), (c), (d), and (g), the front end surface of the columnar forging tool 70 is shaped so as to protrude from the periphery at the axis, and in this embodiment, the forging tool is used. When forming a forged product by sliding and pressing the material with the columnar forging tool 70, the columnar forging tool 70 is inserted into the cylindrical forging tool 60, and the columnar forging tool 70 is elastically deformed. The stress amplitude acting on the cross-hole forming part at the tip of the forging tool during forging and unloading could be reduced by the deflection in the pressing axis direction.
［第２の実施の形態］
この発明の第２の実施の形態を、図１６に基づいて説明する。図１６は圧造工具を先端側から見た斜視図であり、この第２の実施の形態は、第１の実施の形態と同じ構成は同じ符号を付して説明を省略する。
[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIG. FIG. 16 is a perspective view of the forging tool as viewed from the tip side. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
この第２の実施の形態は、第１の実施の形態の圧造工具３０に形成する溝空間５０に代えて複数の穴空間５５を、圧造工具先端の押圧部端面から圧造工具内部へ加圧軸と平行に形成している。この複数の穴空間５５の配置により形成される形状が円形状であり、圧造工具３０の外周形状と相似である。 In the second embodiment, instead of the groove space 50 formed in the forging tool 30 of the first embodiment, a plurality of hole spaces 55 are pressed from the pressing portion end surface of the forging tool tip to the inside of the forging tool. It is formed in parallel with. The shape formed by the arrangement of the plurality of hole spaces 55 is circular and is similar to the outer peripheral shape of the forging tool 30.
このように、複数の穴空間５５の配置により形成される形状が、圧造工具３０の外周形状と相似であり、複数の穴空間５５の配置により形成される形状の中心軸側の押圧部３０ａの外径が、ねじ頭部直径より大きく、複数の穴空間５１の配置により形成される形状の中心軸と反対側の押圧部３０ａの内径が、圧造工具３０の外径より小さい。 Thus, the shape formed by the arrangement of the plurality of hole spaces 55 is similar to the outer peripheral shape of the forging tool 30, and the shape of the pressing portion 30 a on the central axis side of the shape formed by the arrangement of the plurality of hole spaces 55. The outer diameter is larger than the screw head diameter, and the inner diameter of the pressing portion 30 a opposite to the central axis of the shape formed by the arrangement of the plurality of hole spaces 51 is smaller than the outer diameter of the forging tool 30.
また、複数の穴空間５５の配置により形成される形状の内側および外側の形状が、任意形状であり、複数の穴空間５５の長さが、圧造工具先端の押圧部端面から圧造工具後端面より小さい。 Further, the inner and outer shapes of the shapes formed by the arrangement of the plurality of hole spaces 55 are arbitrary shapes, and the length of the plurality of hole spaces 55 is longer than the pressing portion end surface of the forging tool front end than the forging tool rear end surface. small.
この複数の穴空間５５に、固体の充填材料を挿入し、複数の穴空間５５の配置の中心軸側の押圧部３０ａが、加圧時に加圧軸方向に対する垂直方向へのたわみを抑制する構成とすることができ、固体の充填材料のヤング率が、圧造工具３０のヤング率と同値かそれより低く構成される。 A structure in which a solid filling material is inserted into the plurality of hole spaces 55, and the pressing portion 30a on the central axis side of the arrangement of the plurality of hole spaces 55 suppresses the deflection in the direction perpendicular to the pressure axis direction at the time of pressurization. The Young's modulus of the solid filling material is equal to or lower than the Young's modulus of the forging tool 30.
この発明は、圧造する際に用いられる圧造金型に適用可能であり、安価で簡易な構成で、圧造工具の疲労破壊を抑制し、長時間の連続使用を可能とし、さらなる高強度素材のねじ圧造への適用を可能とする。 The present invention can be applied to a forging die used for forging, has a low-cost and simple configuration, suppresses fatigue failure of a forging tool, enables continuous use for a long time, and is a screw of a further high-strength material. Enables application to forging.
１ 冷間圧造金型
３０，６０，７０ 圧造工具
３０ａ 押圧部
３０ａ１ 成形穴
３０ａ２ 突起
４０ 予備成形品
４１ 圧造品
５０ 溝空間
５１ 充填材料
５５ 穴空間
７０ｃ 押圧部
１１０ ダイス
１１１ ノックアウトピン
DESCRIPTION OF SYMBOLS 1 Cold forging die 30, 60, 70 Forging tool 30a Pressing part 30a1 Forming hole 30a2 Protrusion 40 Preliminary product 41 Forging product 50 Groove space 51 Filling material 55 Hole space 70c Pressing part 110 Die 111 Knockout pin
Claims (7)
前記ダイスに対向して配置される一体構造の圧造工具とを備え、
前記ダイスの成形穴に加工前の素材を配置し、
前記圧造工具先端の押圧部により前記素材を押圧して前記圧造品を成形する
にあたり、
前記押圧部の弾性変形を積極的に促進し、加圧軸方向へのたわみにより、圧
造および徐荷時の圧造工具先端の十字穴成形部に作用する応力振幅を低減させる１つの底付き環状の溝空間または複数の底付き穴空間を、前記圧造工具先端の押圧部端面から圧造工具内部へ加圧軸と平行に形成したことを特徴とする圧造金型。 A die having a hole for forming a forged product formed by forging;
A monolithic forging tool disposed opposite to the die,
Place the raw material in the forming hole of the die,
In forming the forged product by pressing the material by the pressing portion at the tip of the forging tool,
One bottomed annular shape that positively promotes elastic deformation of the pressing portion and reduces the stress amplitude acting on the cross hole forming portion at the tip of the forging tool during forging and unloading by bending in the pressing axis direction. A forging die, wherein a groove space or a plurality of bottomed hole spaces are formed in parallel with a pressing shaft from an end surface of the pressing portion at the tip of the forging tool into the forging tool.
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| CN111167985B (en) * | 2020-01-16 | 2021-02-09 | 二重（德阳）重型装备有限公司 | Forming method and device for large-scale long-axis cross-shaped forge piece |
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