JP7088759B2 - Bolt manufacturing method - Google Patents

Bolt manufacturing method Download PDF

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JP7088759B2
JP7088759B2 JP2018125092A JP2018125092A JP7088759B2 JP 7088759 B2 JP7088759 B2 JP 7088759B2 JP 2018125092 A JP2018125092 A JP 2018125092A JP 2018125092 A JP2018125092 A JP 2018125092A JP 7088759 B2 JP7088759 B2 JP 7088759B2
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rod
shaped material
bolt
manufacturing
insertion hole
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JP2020001083A (en
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慎悟 鳥居
啓一 宮田
貴士 大西
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Nitto Seiko Co Ltd
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Nitto Seiko Co Ltd
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本発明は、自動車のサスペンション等の締結において軸力を検知しながら締結されるボルトの製造方法に関する。 The present invention relates to a method for manufacturing a bolt to be fastened while detecting an axial force when fastening a suspension or the like of an automobile.

ボルトの締結において、軸力を適正に管理することが重要であることはよく知られている。そこで、超音波を利用してボルトの軸力を測定する超音波ボルト軸力測定装置がある（例えば、特許文献１参照）。この装置は、超音波探触子からボルト内へ超音波を送波してボルト内で超音波を伝播させ、反射波を超音波探触子で受波するように構成されている。そして、反射波が取得されるタイミングに基づいて、超音波がボルト内部を伝播した時間が測定される。 It is well known that it is important to properly manage the axial force when fastening bolts. Therefore, there is an ultrasonic bolt axial force measuring device that measures the axial force of a bolt using ultrasonic waves (see, for example, Patent Document 1). This device is configured to send ultrasonic waves from the ultrasonic probe into the bolt, propagate the ultrasonic waves in the bolt, and receive the reflected wave by the ultrasonic probe. Then, based on the timing at which the reflected wave is acquired, the time during which the ultrasonic wave propagates inside the bolt is measured.

締め付け前と比べて締め付け後では、ボルトは締め付け軸力によって伸びた状態になっているため、超音波の伝播経路が長くなる。また、締め付けられてボルトに軸力が加えられて引っ張り応力が発生していると、超音波伝播速度も遅くなる。つまり、締め付けの前後においてボルト内を伝播する超音波の伝播時間が異なる。このため、超音波ボルト軸力測定装置を利用して締め付けの前後における伝播時間の相違を知ることによって、ボルトの軸力を測定することができる。 After tightening, the bolt is in a stretched state due to the tightening axial force as compared with before tightening, so that the propagation path of ultrasonic waves becomes longer. Further, when the bolt is tightened and an axial force is applied to the bolt to generate a tensile stress, the ultrasonic wave propagation speed also slows down. That is, the propagation time of the ultrasonic wave propagating in the bolt is different before and after tightening. Therefore, the axial force of the bolt can be measured by knowing the difference in propagation time before and after tightening by using the ultrasonic bolt axial force measuring device.

特開２００１－１７４３４３号公報Japanese Unexamined Patent Publication No. 2001-174343

超音波の伝播時間からボルトの軸力を正確に測定するには、超音波の入射波と反射波を正確に検知する必要があり、ボルトの頭部側端面および軸部側端面が平滑でなければならない。しかしながら、一般的な方法で製造されたボルトは、線材を所定の長さに切断して棒状素材を準備する切断過程において、切断面にひずみが生じるため、このような棒状素材で製造されたボルトの両端面（頭部表面及び軸部端面）は平滑ではない。このため、両端面を平滑にするために研磨などによる追加工が必要になる問題を有していた。 In order to accurately measure the axial force of the bolt from the propagation time of the ultrasonic wave, it is necessary to accurately detect the incident wave and the reflected wave of the ultrasonic wave, and the head side end face and the shaft side end face of the bolt must be smooth. Must be. However, bolts manufactured by a general method are made of such a rod-shaped material because the cut surface is distorted in the cutting process of cutting the wire to a predetermined length to prepare the rod-shaped material. Both end faces (head surface and shaft end face) are not smooth. Therefore, there is a problem that additional machining such as polishing is required to smooth both end faces.

本発明は、上記問題に鑑みて創成されたものであり、ボルトの端面を平滑に仕上げることにより、超音波による軸力測定に好適なボルトの製造方法を提供することを目的とする。 The present invention has been created in view of the above problems, and an object of the present invention is to provide a method for manufacturing a bolt suitable for measuring an axial force by ultrasonic waves by finishing the end face of the bolt smoothly.

上記課題は、線材を所定の長さに切断する切断工程と、切断した棒状素材の両端部を先端にしたがって縮径させることにより両端面を平滑にする端面矯正工程と、棒状素材を両端面から圧縮することにより両端面を平滑に仕上げる圧縮工程と、棒状素材の先端部を絞り加工して軸部を成形する絞り工程と、棒状素材の他端部を押圧して頭部を予備成形する予備成形工程と、予備成形された棒状素材の他端部を押圧して頭部を圧造成形する仕上げ工程とによって両端面が平滑なボルトを製造するボルトの製造方法によって解決できる。The above-mentioned problems are a cutting process of cutting a wire rod to a predetermined length, an end face straightening process of smoothing both end faces by reducing the diameters of both ends of the cut rod-shaped material according to the tip, and cutting the rod-shaped material from both ends. A compression process that finishes both ends smooth by compression, a drawing process that draws the tip of the rod-shaped material to form the shaft, and a drawing process that presses the other end of the rod-shaped material to preform the head. This can be solved by a bolt manufacturing method for producing a bolt having smooth both end surfaces by a preforming step and a finishing step of pressing the other end of the preformed rod-shaped material to press-mold the head.

なお、端面矯正工程では、棒状素材を挿入可能な挿入孔を有する受け駒が用いられ、この挿入孔の内周面は、深部にしたがって縮径するテーパ部を備え、このテーパ部の全角θは、０＜θ≦３２°に設定され、かつこのテーパ部に挿入されることによって縮径される棒状素材の両端面の断面減少率φは、６０％≦φ≦８０％に設定されていることが好ましい。 In the end face correction step, a receiving piece having an insertion hole into which a rod-shaped material can be inserted is used, and the inner peripheral surface of the insertion hole is provided with a tapered portion whose diameter is reduced according to the deep portion, and the full angle θ of this tapered portion is , 0 <θ ≤ 32 °, and the cross-sectional reduction rate φ of both end faces of the rod-shaped material that is reduced in diameter by being inserted into this tapered portion is set to 60% ≤ φ ≤ 80%. Is preferable.

本発明のボルトの製造方法によれば、端面矯正工程によって棒状素材の両端面をある程度平滑にしてから、圧縮工程によって棒状素材の両端面が平滑に仕上げられる。このように、棒状素材の両端面を平滑に仕上げてから、ボルトの頭部および軸部を圧造成形するので、両端面（ボルトの頭部表面および軸部端面）の平滑性に優れたボルトを製造することができる。According to the bolt manufacturing method of the present invention, both end faces of the rod-shaped material are smoothed to some extent by the end face straightening step, and then both end faces of the rod-shaped material are smoothed by the compression step . In this way, after finishing the both end faces of the rod-shaped material to be smooth, the head and shaft of the bolt are press-molded, so that the bolt with excellent smoothness of both ends (head surface and shaft end face of the bolt) can be obtained. Can be manufactured.

本発明のボルトの製造方法における切断工程を示す工程図である。It is a process drawing which shows the cutting process in the manufacturing method of a bolt of this invention. 本発明のボルトの製造方法における端面矯正工程を示す工程図である。It is a process drawing which shows the end face straightening process in the manufacturing method of a bolt of this invention. 本発明のボルトの製造方法における圧縮工程を示す工程図である。It is a process drawing which shows the compression process in the manufacturing method of a bolt of this invention. 本発明のボルトの製造方法における絞り工程を示す工程図である。It is a process drawing which shows the drawing process in the manufacturing method of a bolt of this invention. 本発明のボルトの製造方法における予備成形工程を示す工程図である。It is a process drawing which shows the preforming process in the manufacturing method of a bolt of this invention. 本発明のボルトの製造方法における仕上げ工程を示す工程図である。It is a process drawing which shows the finishing process in the manufacturing method of a bolt of this invention.

以下、図面に基づいて、本発明であるボルトの製造方法の実施形態を説明する。当該ボルトの製造方法は、図１ないし図６に示すように、線材２０を所定の長さに切断する切断工程と、前記切断工程により切断した棒状素材２３の先端部２３ａおよび他端部２３ｂの両端部を縮径する端面矯正工程と、縮径した棒状素材２３を両端部から圧縮する圧縮工程と、棒状素材２３の先端部２３ａを絞り加工してボルトの軸部を成形する絞り工程と、棒状素材２３の他端部２３ｂを押圧して頭部を予備成形する予備成形工程と、予備成形された棒状素材２３の他端部２３ｂを押圧してボルトの頭部を圧造成形する仕上げ工程とによる。Hereinafter, embodiments of the bolt manufacturing method of the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 6, the method for manufacturing the bolt includes a cutting step of cutting the wire rod 20 to a predetermined length, and the tip portion 23a and the other end portion 23b of the rod-shaped material 23 cut by the cutting step. An end face correction process that reduces the diameter of both ends, a compression process that compresses the reduced diameter rod-shaped material 23 from both ends, and a drawing process that draws the tip 23a of the rod-shaped material 23 to form the shaft portion of the bolt. , A preforming step of pressing the other end 23b of the rod-shaped material 23 to preform the head, and a finishing step of pressing the other end 23b of the preformed rod-shaped material 23 to press-mold the head of the bolt. According to.

図１に示すように、切断工程は、金属製の線材２０を切り駒２１の貫通孔２１ａへ挿通するとともに、線材２０の先端がストッパ２２に当接するまで繰出し、切り駒２１の貫通孔２１ａの開口部分から突出した線材２０を所定の長さに切断し、金属片の一例である棒状素材２３を製作する工程である。また、線材２０の切断は、線材２０の軸線と直交する方向（矢印Ａで示す方向）へ移動するカッター２４により行われる。 As shown in FIG. 1, in the cutting step, the metal wire 20 is inserted into the through hole 21a of the cutting piece 21 and extended until the tip of the wire 20 comes into contact with the stopper 22 to form the through hole 21a of the cutting piece 21. This is a step of cutting the wire rod 20 protruding from the opening portion to a predetermined length to manufacture a rod-shaped material 23 which is an example of a metal piece. Further, the cutting of the wire 20 is performed by a cutter 24 that moves in a direction orthogonal to the axis of the wire 20 (the direction indicated by the arrow A).

図２（ａ）に示すように、端面矯正工程は、前記切断工程によって切断した棒状素材２３の他端部２３ｂを受け駒３１を用いて小径に絞り込む工程である。この受け駒３１は、棒状素材２３を挿入可能な挿入孔３１ａを有しており、この挿入孔３１ａの内周面は、深部にしたがって縮径するテーパ部３１ｂを備える。 As shown in FIG. 2A, the end face straightening step is a step of narrowing down the diameter to a small diameter by using the receiving piece 31 at the other end 23b of the rod-shaped material 23 cut by the cutting step. The receiving piece 31 has an insertion hole 31a into which the rod-shaped material 23 can be inserted, and the inner peripheral surface of the insertion hole 31a includes a tapered portion 31b whose diameter is reduced according to the deep portion.

そこで、端面矯正工程では、まず、受け駒３１の挿入孔３１ａに棒状素材２３を挿入する。続いて、ピン３２で棒状素材２３の先端部２３ａを押圧し、矢印Ｂで示す方向へ押し込む。すると、棒状素材２３の他端部２３ｂは、塑性変形によりテーパ部３１ｂに流入し、縮径される。最後に、受け駒３１側から挿入されたノックアウトピン３３で棒状素材２３の他端部２３ｂを押圧し、矢印Ｃで示す方向に移動させることによって、棒状素材２３は受け駒３１から排出される。 Therefore, in the end face correction step, first, the rod-shaped material 23 is inserted into the insertion hole 31a of the receiving piece 31. Subsequently, the tip portion 23a of the rod-shaped material 23 is pressed by the pin 32 and pushed in the direction indicated by the arrow B. Then, the other end portion 23b of the rod-shaped material 23 flows into the tapered portion 31b due to plastic deformation, and the diameter is reduced. Finally, the rod-shaped material 23 is discharged from the receiving piece 31 by pressing the other end 23b of the rod-shaped material 23 with the knockout pin 33 inserted from the receiving piece 31 side and moving the rod-shaped material 23 in the direction indicated by the arrow C.

さらに、端面矯正工程では、図２（ｂ）に示すように、棒状素材２３の先後を入れ替えて、図２（ａ）に示したように、棒状素材２３の他端部２３ｂを縮径した方法と同様の方法で、棒状素材２３の先端部２３ａを縮径する。一方で、棒状素材２３の他端部２３ｂは、ピン３２によって圧縮されるため、挿入孔３１ａの内径にまで拡径される。最後に、棒状素材２３は受け駒３１から排出され、圧縮工程に移行する。Further, in the end face straightening step, as shown in FIG. 2 (b), the tip and the back of the rod-shaped material 23 are exchanged, and as shown in FIG. 2 (a), the other end portion 23 b of the rod-shaped material 23 is reduced in diameter. The diameter of the tip portion 23a of the rod-shaped material 23 is reduced in the same manner as in the above method. On the other hand, since the other end 23b of the rod-shaped material 23 is compressed by the pin 32, the diameter is expanded to the inner diameter of the insertion hole 31a. Finally, the rod-shaped material 23 is discharged from the receiving piece 31, and the process proceeds to the compression process .

図３に示すように、圧縮工程は、棒状素材２３を両端部から圧縮する工程である。まず、受け駒４１の中心線上に穿設された貫通孔４１ａに棒状素材２３を挿入する。この貫通孔４１ａの内径は、全長にわたって前記受け駒３１の挿入孔３１ａの内径のうち最大径と同じ寸法に設定されており、つまり棒状素材２３の最大径と同じ寸法に設定されている。また、貫通孔４１ａには、棒状素材２３を挿入した開口とは反対側の開口からノックアウトピン４２が挿入されており、貫通孔４１ａに挿入された棒状素材２３は、このノックアウトピン４２の先端で支持されている。続いて，貫通孔４１ａに挿入された棒状素材２３の他端部２３ｂをピン４１で矢印Ｂで示す方向に押圧することにより、棒状素材２３を両端部からピン４１及びノックアウトピン４２によって圧縮する。最後に、ノックアウトピン４２を矢印Ｃで示す方向へ移動させることによって、棒状素材２３は受け駒４１から排出される。As shown in FIG. 3, the compression step is a step of compressing the rod-shaped material 23 from both ends. First, the rod-shaped material 23 is inserted into the through hole 41a formed on the center line of the receiving piece 41. The inner diameter of the through hole 41a is set to the same dimension as the maximum diameter of the inner diameter of the insertion hole 31a of the receiving piece 31 over the entire length, that is, the same dimension as the maximum diameter of the rod-shaped material 23. Further, a knockout pin 42 is inserted into the through hole 41a from an opening opposite to the opening into which the rod-shaped material 23 is inserted, and the rod-shaped material 23 inserted into the through hole 41a is at the tip of the knockout pin 42. It is supported. Subsequently, by pressing the other end 23b of the rod-shaped material 23 inserted into the through hole 41a with the pin 41 in the direction indicated by the arrow B, the rod-shaped material 23 is compressed from both ends by the pins 41 and the knockout pin 42. Finally, by moving the knockout pin 42 in the direction indicated by the arrow C, the rod-shaped material 23 is ejected from the receiving piece 41.

図４に示すように、絞り工程では、まず、絞り駒５１の挿通孔５１ｂに棒状素材２３を先端部２３ａから挿入する。続いて、この棒状素材２３を絞りピン５２で絞り孔５１ａの位置する方向（矢印Ｂで示す方向）へ押圧する。すると、棒状素材２３の先端部２３ａは、塑性変形により挿通孔５１ｂより小径の内径を成す絞り孔５１ａへ流入し、ボルトの軸部が成形される。最後に、絞り駒５１の絞り孔５１ａ側から挿入されたノックアウトピン５３を挿通孔５１ｂの位置する方向（矢印Ｃで示す方向）へ移動させることによって、棒状素材２３は絞り駒５１から排出される。 As shown in FIG. 4, in the drawing step, first, the rod-shaped material 23 is inserted into the insertion hole 51b of the drawing piece 51 from the tip portion 23a. Subsequently, the rod-shaped material 23 is pressed by the diaphragm pin 52 in the direction in which the diaphragm hole 51a is located (the direction indicated by the arrow B). Then, the tip portion 23a of the rod-shaped material 23 flows into the drawing hole 51a having an inner diameter smaller than that of the insertion hole 51b due to plastic deformation, and the shaft portion of the bolt is formed. Finally, the rod-shaped material 23 is discharged from the drawing piece 51 by moving the knockout pin 53 inserted from the drawing hole 51a side of the drawing piece 51 in the direction in which the insertion hole 51b is located (the direction indicated by the arrow C). ..

図５に示すように、予備成形工程は、受け駒６１および予備成形パンチ６２を用いて、前記絞り工程によって成形された棒状素材２３の他端部２３ｂをボルトの頭部の完成形状に近づけるための工程である。この受け駒６１は、棒状素材２３の先端部２３ａであって、つまりボルトの軸部となる部分を挿入可能で、かつ他端部２３ｂを挿入不可能な内径に設定された挿入孔６１ａを有しており、棒状素材２３の他端部２３ｂは、受け駒６１から突出した状態となる。 As shown in FIG. 5, in the preforming step, the receiving piece 61 and the preforming punch 62 are used to bring the other end portion 23b of the rod-shaped material 23 formed by the drawing step closer to the completed shape of the head of the bolt. This is the process. The receiving piece 61 has an insertion hole 61a which is a tip portion 23a of the rod-shaped material 23, that is, a portion which is a shaft portion of a bolt can be inserted, and the other end portion 23b is set to an inner diameter which cannot be inserted. The other end 23b of the rod-shaped material 23 is in a state of protruding from the receiving piece 61.

また、予備成形パンチ６２は、端面に予備成形凹部６２ａを有する。予備成形パンチ６２の予備成形凹部６２ａを棒状素材２３の他端部２３ｂに向かって（矢印Ｂで示す方向）押圧する。これにより、棒状素材２３の他端部２３ｂは予備成形凹部６２ａの内周面に沿って胴部膨れするように変形してボルトの頭部が予備成形される。最後に、ノックアウトピン６３を矢印Ｃで示す方向へ移動させることによって、棒状素材２３は受け駒６１から排出される。 Further, the preforming punch 62 has a preforming recess 62a on the end face. The preforming recess 62a of the preforming punch 62 is pressed toward the other end 23b of the rod-shaped material 23 (in the direction indicated by the arrow B). As a result, the other end 23b of the rod-shaped material 23 is deformed so as to bulge along the inner peripheral surface of the preformed recess 62a, and the head of the bolt is preformed. Finally, by moving the knockout pin 63 in the direction indicated by the arrow C, the rod-shaped material 23 is ejected from the receiving piece 61.

図６に示すように、前記仕上げ工程は、受け駒７１を用いて予備成形された棒状素材２３の他端部２３ｂをボルトの頭部に完成させるための工程であり、受け駒７１は、その中心軸線上に穿設された挿入孔７１ａを有し、挿入孔７１ａの開口部分には、段付き部７２ｂが形成されている。この挿入孔７１ａに棒状素材２３を先端部２３ａから挿入し、他端部２３ｂは、段付き部７２ｂに引っかかる。この状態で、パンチ７２で棒状素材の他端部２３ｂを押圧することによって、棒状素材２３の他端部２３ｂが段付き部７２ｂを充填するように塑性変形することによって、頭部１１が完成する。最後に、ノックアウトピン７３を矢印Ｃで示す方向へ移動させることによって、頭部（棒状素材の他端部２３ｂ）と軸部（棒状素材２３の先端部２３ａ）が成形されたボルトが受け駒７１から排出される。 As shown in FIG. 6, the finishing step is a step for completing the other end portion 23b of the rod-shaped material 23 preformed by using the receiving piece 71 on the head of the bolt, and the receiving piece 71 is a step thereof. It has an insertion hole 71a formed on the central axis, and a stepped portion 72b is formed in the opening portion of the insertion hole 71a. The rod-shaped material 23 is inserted into the insertion hole 71a from the tip portion 23a, and the other end portion 23b is caught by the stepped portion 72b. In this state, by pressing the other end 23b of the rod-shaped material with the punch 72, the other end 23b of the rod-shaped material 23 is plastically deformed so as to fill the stepped portion 72b, thereby completing the head 11. .. Finally, by moving the knockout pin 73 in the direction indicated by the arrow C, the bolt having the head (the other end 23b of the rod-shaped material) and the shaft (the tip 23a of the rod-shaped material 23) formed is the receiving piece 71. Is discharged from.

ここで、端面矯正工程において、挿入孔３１ａのテーパ部３１ｂの全角θは、２０°に設定されている。また、図２（ａ）に示すように、棒状素材２３の他端部２３ｂは、棒状素材２３の他端面の断面減少率φが５７％になる位置までテーパ部３１ｂに押し込まれる一方、図２（ｂ）に示すように、棒状素材２３の先端部２３ａは、その先端面の断面減少率φが６６％になる位置までテーパ部３１ｂに押し込まれる。 Here, in the end face correction step, the full-width θ of the tapered portion 31b of the insertion hole 31a is set to 20 °. Further, as shown in FIG. 2A, the other end portion 23b of the rod-shaped material 23 is pushed into the tapered portion 31b to a position where the cross-sectional reduction rate φ of the other end surface of the rod-shaped material 23 becomes 57%, while FIG. As shown in (b), the tip portion 23a of the rod-shaped material 23 is pushed into the tapered portion 31b to a position where the cross-sectional reduction rate φ of the tip surface thereof becomes 66%.

また、上記全角θおよび断面減少率φは、前述の数値に限定されるものではなく、テーパ部３１ｂの全角θは、０＜θ≦３２°に設定され、かつこのテーパ部３１ｂに挿入されることによって縮径される棒状素材２３の両端面の断面減少率φは、６０％≦φ≦８０％に設定されてる。この数値範囲であれば、棒状素材２３の両端部２３ａ，２３ｂの端面は、平滑になる一方、この数値範囲で縮径させると、塑性変形の過程で端面の中央部分が凹んでしまい平滑にならない現象が生じる。このように、本発明のボルトの製造方法によれば、端面矯正工程によって棒状素材２３の両端面をある程度平滑にしてから、圧縮工程によって棒状素材の両端面が平滑に仕上げられる。このように、ボルトの頭部および軸部を成形する前に、棒状素材２３の両端面を平滑に仕上げてから、ボルトの頭部および軸部を圧造成形するので、両端面（ボルトの頭部表面および軸部端面）の平滑性に優れたボルトを製造することができる。Further, the full-width θ and the cross-section reduction rate φ are not limited to the above-mentioned numerical values, and the full-width θ of the tapered portion 31b is set to 0 <θ≤32 ° and is inserted into the tapered portion 31b. The cross-sectional reduction rate φ of both end faces of the rod-shaped material 23 to be reduced in diameter is set to 60% ≦ φ ≦ 80%. Within this numerical range, the end faces of both ends 23a and 23b of the rod-shaped material 23 become smooth, but if the diameter is reduced within this numerical range, the central portion of the end face is dented in the process of plastic deformation and does not become smooth. A phenomenon occurs. As described above, according to the bolt manufacturing method of the present invention, both end faces of the rod-shaped material 23 are smoothed to some extent by the end face straightening step, and then both end faces of the rod-shaped material are smoothed by the compression step . In this way, before molding the head and shaft of the bolt, both end faces of the rod-shaped material 23 are smoothed, and then the head and shaft of the bolt are press-molded, so that both ends (head of the bolt) are formed. It is possible to manufacture a bolt having excellent surface smoothness (surface and end face of shaft portion).

２３ 棒状素材
３１ 受け駒
３１ａ 挿入孔
３１ｂ テーパ部
23 Rod-shaped material 31 Receiving piece 31a Insertion hole 31b Tapered part

Claims (2)

線材を所定の長さに切断する切断工程と、
切断した棒状素材の両端部を先端にしたがって縮径させることにより両端面を平滑にする端面矯正工程と、
棒状素材を両端面から圧縮することにより両端面を平滑に仕上げる圧縮工程と、
棒状素材の先端部を絞り加工して軸部を成形する絞り工程と、
棒状素材の他端部を押圧して頭部を予備成形する予備成形工程と、
予備成形された棒状素材の他端部を押圧して頭部を圧造成形する仕上げ工程と、
によって両端面が平滑なボルトを製造することを特徴とするボルトの製造方法。A cutting process that cuts the wire to a predetermined length,
An end face correction process that smoothes both ends by reducing the diameter of both ends of the cut rod-shaped material according to the tip.
A compression process that smoothes both ends by compressing the rod-shaped material from both ends.
The drawing process of drawing the tip of the rod-shaped material to form the shaft,
The pre-molding process of pressing the other end of the rod-shaped material to pre-mold the head,
The finishing process of pressing the other end of the preformed rod-shaped material to press-mold the head, and
A method for manufacturing a bolt, which comprises manufacturing a bolt whose both end faces are smooth. 端面矯正工程では、棒状素材を挿入可能な挿入孔を有する受け駒が用いられ、この挿入孔の内周面は、深部にしたがって縮径するテーパ部を備え、このテーパ部の全角θは、０＜θ≦３２°に設定され、かつこのテーパ部に挿入されることによって縮径される棒状素材の両端面の断面減少率φは、６０％≦φ≦８０％に設定されていることを特徴とする請求項１に記載のボルトの製造方法。In the end face correction step, a receiving piece having an insertion hole into which a rod-shaped material can be inserted is used, and the inner peripheral surface of the insertion hole is provided with a tapered portion whose diameter is reduced according to the deep portion, and the full angle θ of this tapered portion is 0. The cross-sectional reduction rate φ of both end faces of the rod-shaped material which is set to <θ≤32 ° and whose diameter is reduced by being inserted into this tapered portion is set to 60%≤φ≤80%. The method for manufacturing a bolt according to claim 1 .
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002316235A (en) 2001-04-17 2002-10-29 Toyota Motor Corp Bolt and method for forming bolt
JP2006136915A (en) 2004-11-11 2006-06-01 Toyota Motor Corp Method for working bolt base-stock, bolt base-stock and die for working bolt base-stock
JP2017109235A (en) 2015-12-18 2017-06-22 日東精工株式会社 Cold headed component and manufacturing method for the same

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3045397B2 (en) * 1990-08-02 2000-05-29 株式会社日本パーツ製作所 Method for manufacturing locking projection of insert fitting
JPH05104191A (en) * 1991-10-15 1993-04-27 Suzuhide Kogyo Kk Cold forging method for shaft body with flange

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002316235A (en) 2001-04-17 2002-10-29 Toyota Motor Corp Bolt and method for forming bolt
JP2006136915A (en) 2004-11-11 2006-06-01 Toyota Motor Corp Method for working bolt base-stock, bolt base-stock and die for working bolt base-stock
JP2017109235A (en) 2015-12-18 2017-06-22 日東精工株式会社 Cold headed component and manufacturing method for the same

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