JP5036238B2 - Manufacturing method of screw member - Google Patents

Manufacturing method of screw member Download PDF

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JP5036238B2
JP5036238B2 JP2006195660A JP2006195660A JP5036238B2 JP 5036238 B2 JP5036238 B2 JP 5036238B2 JP 2006195660 A JP2006195660 A JP 2006195660A JP 2006195660 A JP2006195660 A JP 2006195660A JP 5036238 B2 JP5036238 B2 JP 5036238B2
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screw
thread
connecting rod
shaft portion
rolling
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JP2008025620A (en
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照基 亀田
勉 川村
浩司 牧野
勤二 福岡
和明 平林
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Toyota Motor Corp
Meidoh Co Ltd
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Toyota Motor Corp
Meidoh Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a screw member which prevents turning-in from occurring in a screw bottom part in a stress concentrated portion, even when rolled by a rolling die with one part lacked in a top part of a screw thread, in screw rolling work, and which enhancing fatigue resistant characteristic, a lagged breakage resistant characteristic and the like, and also to provide a manufacturing method therefor. <P>SOLUTION: A large-diametric shaft part 4a is formed in a female screw part and a screwed portion in a connecting rod bolt 1, a small-diametric shaft part 5a is formed in the female screw part and a nonscrewed portion, then a complete screw part 4 is formed in the large-diametric shaft part 4a, by a screw rolling work, an incomplete screw part 5 is formed in the small-diametric shaft part 5a. The turned-in 55 is thereby prevented from occurring in the screw bottom part in the stress concentrated incomplete screw part 5, even when rolled by the rolling die with the one part lacked in the top part of the screw thread, in the screw rolling work. The fatigue resistant characteristic, the lagged breakage resistant characteristic and the like in the connecting rod bolt 1 of the present invention, are enhanced by this manner compared with those in a conventional connecting rod bolt. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

本発明は、耐疲労特性及び耐遅れ破壊特性等に優れたねじ部材の製造方法に関するものである。 The present invention relates to a method for manufacturing a screw member having excellent fatigue resistance and delayed fracture resistance.

自動車には、多種多数のボルトが使用されているが、例えば、図１に示すように、半円筒状のキャップ６０を、コンロッド６１の半円筒部分に取り付ける際には、コンロッドボルト（ねじ部材）５１が使用されている。
すなわち、図３に示すように、キャップ６０には、従来のコンロッドボルト５１（図７参照）の軸部５２が挿通される貫通孔６２が形成されると共に、コンロッド６１には、キャップ６０が取り付けられる面を開口して、コンロッドボルト５１の軸部５２が挿通される貫通孔６３が形成され、この貫通孔６３に連続して雌ねじ部６４が形成されている。そして、このコンロッドボルト５１を、キャップ６０及びコンロッド６１それぞれの貫通孔６２及び６３に挿通して、コンロッド６１の雌ねじ部６４に螺合することにより、キャップ６０をコンロッド６１に取り付けている。 A large number of bolts are used in automobiles. For example, as shown in FIG. 1, when a semi-cylindrical cap 60 is attached to a semi-cylindrical portion of a connecting rod 61, a connecting rod bolt (screw member) is used. 51 is used.
That is, as shown in FIG. 3, the cap 60 is formed with a through hole 62 through which the shaft portion 52 of the conventional connecting rod bolt 51 (see FIG. 7) is inserted, and the cap 60 is attached to the connecting rod 61. A through hole 63 through which the shaft portion 52 of the connecting rod bolt 51 is inserted is formed, and a female screw portion 64 is formed continuously with the through hole 63. The connecting rod bolt 51 is inserted into the through holes 62 and 63 of the cap 60 and the connecting rod 61, respectively, and screwed into the female thread portion 64 of the connecting rod 61, so that the cap 60 is attached to the connecting rod 61.

そこで、従来のコンロッドボルト５１は、図７に示すように、頭部５４と軸部５２とからなり、該軸部５２には、その略全長に亘って、ねじ山断面形状が略三角形状となる完全ねじ部５３が形成されている。この完全ねじ部５３は、図６に示す第１及び第２転造ダイス７０、７１によるねじ転造加工によって形成される。
しかしながら、従来のコンロッドボルト５１の軸部５２にねじ転造加工により完全ねじ部５３を形成する際、ねじ山の頂部の一部が欠けた第１または第２転造ダイス７０、７１により過転造されて完全ねじ部５３が形成されると、図７（ｂ）に示すように、完全ねじ部５３のねじ底部に亀裂５５が現出する。 Therefore, as shown in FIG. 7, the conventional connecting rod bolt 51 includes a head portion 54 and a shaft portion 52. The shaft portion 52 has a substantially triangular cross-sectional shape over the entire length thereof. A complete screw portion 53 is formed. The complete threaded portion 53 is formed by thread rolling using the first and second rolling dies 70 and 71 shown in FIG.
However, when the complete thread portion 53 is formed on the shaft portion 52 of the conventional connecting rod bolt 51 by the thread rolling process, the first or second rolling dies 70 and 71 lacking a part of the top of the thread are over-rolled. When the complete screw portion 53 is formed, a crack 55 appears at the screw bottom of the complete screw portion 53 as shown in FIG.

そこで、従来のコンロッドボルト５１の完全ねじ部５３のねじ底部に現出される亀裂５５の発生メカニズムを、図８に基いて図６も参照しながら以下（１）〜（５）にて説明する。
（１）ねじ転造加工により、コンロッドボルト５１の軸部５２に完全ねじ部５３を形成する際には、図６に示すように、コンロッドボルト５１の軸部５２を、固定位置で回動する円柱状の第１転造ダイス７０と、第１転造ダイス７０側に進退移動すると共に回動する円柱状の第２転造ダイス７１との間に配し、第２転造ダイス７１を回動させながら第１転造ダイス７０側に移動させて、コンロッドボルト５１の軸部５２を第１転造ダイス７０と第２転造ダイス７１との間で転動させる。すると、図８（ａ）に示すように、コンロッドボルト５１の軸部５２の材料が、第１及び第２転造ダイス７０、７１の各ねじ山間のねじ溝をねじ底部に向かって流れ込み、正規の高さに対して約８割程度の高さのねじ山５６、５６が形成される。
（２）引き続き、コンロッドボルト５１の軸部５２が第１及び第２転造ダイス７０、７１間を転動すると、図８（ｂ）に示すように、コンロッドボルト５１の軸部５２の材料が、第１及び第２転造ダイス７０、７１の各ねじ山間のねじ溝に完全に充填されて、コンロッドボルト５１の軸部５２に、正規の高さのねじ山５３、５３（完全ねじ部）が形成される。 Therefore, the generation mechanism of the crack 55 appearing at the screw bottom portion of the complete screw portion 53 of the conventional connecting rod bolt 51 will be described in the following (1) to (5) with reference to FIG. .
(1) When the complete thread portion 53 is formed on the shaft portion 52 of the connecting rod bolt 51 by thread rolling, the shaft portion 52 of the connecting rod bolt 51 is rotated at a fixed position as shown in FIG. The second rolling die 71 is rotated between the cylindrical first rolling die 70 and the second cylindrical rolling die 71 that moves forward and backward toward the first rolling die 70 and rotates. The shaft portion 52 of the connecting rod bolt 51 is moved between the first rolling die 70 and the second rolling die 71 by moving to the first rolling die 70 side while moving. Then, as shown in FIG. 8A, the material of the shaft portion 52 of the connecting rod bolt 51 flows into the screw groove between the screw threads of the first and second rolling dies 70 and 71 toward the screw bottom portion. Threads 56 and 56 having a height of about 80% with respect to the height are formed.
(2) Subsequently, when the shaft portion 52 of the connecting rod bolt 51 rolls between the first and second rolling dies 70 and 71, the material of the shaft portion 52 of the connecting rod bolt 51 is changed as shown in FIG. The thread grooves between the respective threads of the first and second rolling dies 70 and 71 are completely filled, and the thread portions 53 and 53 (full thread portions) of a normal height are formed on the shaft portion 52 of the connecting rod bolt 51. Is formed.

（３）さらに、コンロッドボルト５１の軸部５２に完全ねじ部５３が形成された後、図８（ｃ）に示すように、この完全ねじ部５３が、第１または第２転造ダイス７０、７１のねじ山の頂部が欠けた部分５８を転動すると、過転造になると共に隣接するねじ山５３、５３の斜面の途中に段差５７、５７がそれぞれ形成される。
（４）さらに、コンロッドボルト５１の各段差５７、５７の部位が、再び第１または第２転造ダイス７０、７１の正常なねじ山の部分を転動すると、図８（ｄ）に示すように、過転造の状態が続き、各ねじ山５３、５３の各段差５７、５７の部分が、矢印で示すようにねじ底部に向かって押されるようにそれぞれ流動して、ねじ底部にて干渉し重なり合う現象が発生して、その部分に亀裂５５が現出される。
（５）その後、前項（３）及び（４）の動作が繰り返して行われると、ねじ底部に現出された亀裂５５が枝状に分かれるようにして伸び、亀裂５５（以下まくれ込みという）がさらに深く現出されるようになる。 (3) Further, after the complete thread portion 53 is formed on the shaft portion 52 of the connecting rod bolt 51, as shown in FIG. 8 (c), the complete thread portion 53 is formed by the first or second rolling die 70, When the portion 58 lacking the top of the thread 71 is rolled, overrolling occurs and steps 57 and 57 are formed in the middle of the slopes of the adjacent threads 53 and 53, respectively.
(4) Further, when the steps 57 and 57 of the connecting rod bolt 51 roll on the normal thread portions of the first or second rolling dies 70 and 71 again, as shown in FIG. In addition, the over-rolling state continues, and the steps 57 and 57 of the screw threads 53 and 53 respectively flow so as to be pushed toward the screw bottom as indicated by arrows, and interfere with each other at the screw bottom. An overlapping phenomenon occurs, and a crack 55 appears at that portion.
(5) Thereafter, when the operations of (3) and (4) above are repeated, the crack 55 appearing at the screw bottom portion extends in a branch shape, and the crack 55 (hereinafter referred to as turning up) is formed. It will appear more deeply.

そして、前述したようにねじ底部にまくれ込み５５が現出された従来のコンロッドボルト５１により、図３のようにキャップ６０をコンロッド６１に取り付け、該コンロッドボルト５１に曲げ荷重が繰り返し作用すると、応力が、コンロッドボルト５１の、コンロッド６１の貫通孔６３と雌ねじ部６４との境界部分に位置する完全ねじ部５３のねじ底部のまくれ込み５５に集中して、該まくれ込み５５を起点に破断し易くなり、コンロッドボルト５１の耐疲労特性及び耐遅れ破壊特性等を十分に満足することができなくなってしまう。   When the cap 60 is attached to the connecting rod 61 as shown in FIG. 3 and the bending load is repeatedly applied to the connecting rod bolt 51 as shown in FIG. However, the connecting rod bolt 51 concentrates on the turning-up 55 of the screw bottom portion of the complete threaded portion 53 located at the boundary portion between the through-hole 63 of the connecting rod 61 and the female threaded portion 64, and is easily broken from the turning-up 55 as a starting point. As a result, the fatigue resistance and delayed fracture resistance of the connecting rod bolt 51 cannot be fully satisfied.

ところで、完全ねじ部５３のねじ底部へのまくれ込み５５の現出を防ぐためには、ねじ転造加工する際の作業管理において、段取の前後で軸部５２の位置を確認することで過転造とならないように管理し、さらに、第１及び第２転造ダイス７０、７１のねじ山の頂部に欠けた部位５８が有るか否かを定期的に検査する必要がある。
しかしながら、各転造ダイス７０、７１のねじ山の頂部に欠けた部位５８が有るか否かを検査する方法は、目視及び手感による検査方法であるため、微小なダイス欠け５８を見逃す虞があり、作業管理上において、特に、各転造ダイス７０、７１のダイス欠け５８の有無を厳密に管理することは困難であった。 By the way, in order to prevent the full thread portion 53 from appearing in the screw bottom 55, in the work management when performing the thread rolling process, the position of the shaft portion 52 is confirmed before and after the setup to overrun. Therefore, it is necessary to periodically check whether or not there is a missing portion 58 at the top of the thread of the first and second rolling dies 70 and 71.
However, since the method for inspecting whether or not there is a chipped portion 58 at the top of the thread of each rolling die 70 and 71 is an inspection method by visual observation and hand feeling, there is a possibility that a minute die chip 58 may be missed. In terms of work management, it is particularly difficult to strictly manage the presence or absence of the die chipping 58 of each of the rolling dies 70 and 71.

そこで、特許文献１には、ネジ山を潰して形成した不完全ネジ部を、ネジ部の長さ方向中間に光軸調整に必要な範囲内に設けた、自動車用前照灯の光軸調整用アジャスタスクリューが開示されている。
実開昭５８−６１９１６号公報 Therefore, Patent Document 1 discloses an optical axis adjustment of an automotive headlamp in which an incomplete screw portion formed by crushing a screw thread is provided in the middle of the screw portion in the range necessary for optical axis adjustment. An adjuster screw for use is disclosed.
Japanese Utility Model Publication No. 58-61916

しかしながら、上述した特許文献１の発明は、アジャストスクリューに、ネジ山を潰して不完全ネジ部を形成することで、この不完全ネジ部と車体側のナットとの密着性を増大させて、振動等によってアジャストスクリューが妄りに回動するのを未然に防止するもので、特許文献１の発明によって、ねじ山の頂部の一部が欠けた転造ダイスによってねじ転造加工される際、ねじ底部にまくれ込みが現出されるのを防ぐことは到底できない。   However, the above-mentioned invention of Patent Document 1 increases the adhesion between the incomplete screw portion and the nut on the vehicle body by crushing the screw thread to form an incomplete screw portion in the adjustment screw, and vibration In order to prevent the adjustment screw from rotating unreasonably due to, for example, according to the invention of Patent Document 1, when the thread rolling process is performed by a rolling die in which a part of the top of the screw thread is missing, It is impossible to prevent the trickling from appearing.

本発明は、かかる点に鑑みてなされたものであり、ねじ転造加工時、ねじ山の頂部の一部が欠けた転造ダイスによって転造された場合でも、応力の集中する部位のねじ底部にまくれ込みが現出されず、耐疲労特性及び耐遅れ破壊特性等が向上するねじ部材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 points, and when thread rolling, even when the thread is rolled by a rolling die that lacks a part of the top of the screw thread, the thread bottom of the portion where stress is concentrated It is an object of the present invention to provide a method for manufacturing a screw member that does not appear to be turned up and improves fatigue resistance and delayed fracture resistance.

また、上記課題を解決するための手段として、請求項１に記載したねじ部材の製造方法の発明は、雌ねじ部に螺合されるねじ部材の製造方法であって、前記ねじ部材の軸部を、小径軸部と大径軸部とに形成する工程と、同一の転造ダイスによるねじ転造加工により、前記小径軸部にねじ山断面形状が略台形状となる不完全ねじ部を形成すると同時に、前記大径軸部にねじ山断面形状が略三角形状となる完全ねじ部を形成する工程と、を含むことを特徴とするものである。
請求項２に記載したねじ部材の製造方法の発明は、請求項１に記載した発明において、前記軸部を前記小径軸部と前記大径軸部とに形成する前記工程では、前記小径軸部と前記大径軸部とが転造加工によって形成されることを特徴とするものである。
請求項３に記載したねじ部材の製造方法の発明は、請求項１または２に記載した発明において、前記不完全ねじ部は、前記雌ねじ部との非螺合部位に形成されると共に、前記完全ねじ部は、前記雌ねじ部との螺合部位に形成されることを特徴とするものである。 Further, as a means for solving the above-mentioned problem, the invention of the method for manufacturing a screw member according to claim 1 is a method for manufacturing a screw member to be screwed into the female screw portion, wherein the shaft portion of the screw member is By forming the incomplete screw portion in which the thread cross-sectional shape is substantially trapezoidal by the step of forming the small diameter shaft portion and the large diameter shaft portion and the thread rolling process using the same rolling die. at the same time, the it is to the step of screw thread cross-sectional shape in the large-diameter shaft portion to form a complete thread portion becomes a substantially triangular shape, comprising a.
The invention of a screw member manufacturing method according to claim 2 is the invention according to claim 1, wherein in the step of forming the shaft portion in the small diameter shaft portion and the large diameter shaft portion, the small diameter shaft portion is formed. And the large diameter shaft portion are formed by rolling.
According to a third aspect of the present invention, there is provided a screw member manufacturing method according to the first or second aspect, wherein the incomplete screw portion is formed at a non-threaded portion with the female screw portion, and the complete screw portion is formed. The threaded portion is formed at a threaded portion with the female threaded portion.

また、請求項１に記載したねじ部材の製造方法の発明では、ねじ部材の軸部に小径軸部を形成した後、該小径軸部にねじ転造加工によりねじ山断面形状が略台形状となる不完全ねじ部が形成されるので、ねじ転造加工する際、ねじ山の頂部の一部が欠けた転造ダイスで転造されたとしても、小径軸部においては、転造ダイスの各ねじ山間のねじ溝にねじ部材の材料が完全に充填されず過転造の状態にならないために、不完全ねじ部のねじ底部にまくれ込みが現出されることがない。これにより、ねじ部材に、完全ねじ部が拘束された状態で曲げ荷重が繰り返し作用して、その応力が完全ねじ部と不完全ねじ部との境界部分の不完全ねじ部のねじ底部に集中しても、その応力がねじ底部の全体に分散されるため、ねじ底部にまくれ込みが現出された従来のねじ部材よりも耐疲労特性及び耐遅れ破壊特性等を向上させたねじ部材を製造する方法が提供される。
請求項２に記載したねじ部材の製造方法の発明では、ねじ部材の軸部が、加工硬化して高強度に形成され、従来のねじ部材よりも耐疲労特性及び耐遅れ破壊特性等を向上させたねじ部材を製造する方法が提供される。
請求項３に記載したねじ部材の製造方法の発明では、ねじ部材により複数の部材を締結した状態で、このねじ部材に曲げ荷重が繰り返し作用すると、応力が集中する箇所はねじ部材の雌ねじ部との非螺合部位に形成した不完全ねじ部となるが、その不完全ねじ部のねじ底部にはまくれ込みが現出されていないので、応力は不完全ねじ部のねじ底部の全体に分散されて、ねじ部材の耐疲労特性及び耐遅れ破壊特性等が十分に満足されるねじ部材を製造する方法が提供される。 Further, the present invention provides a method for preparing a screw member according to claim 1, after forming the small-diameter shaft portion to the shaft portion of the screw member, the thread cross section by thread rolling process in the small-diameter shaft portion and a substantially trapezoidal shape Incomplete threaded parts are formed, so that when rolling a thread, even if it is rolled with a rolling die that lacks a part of the top of the thread, Since the screw groove material between the screw threads is not completely filled with the material of the screw member and does not become an over-rolled state, no turning-up appears at the screw bottom portion of the incomplete screw portion. As a result, a bending load is repeatedly applied to the screw member in a state where the complete screw portion is constrained, and the stress is concentrated on the screw bottom portion of the incomplete screw portion at the boundary portion between the complete screw portion and the incomplete screw portion. However, since the stress is distributed over the entire screw bottom, a screw member with improved fatigue resistance and delayed fracture resistance is manufactured as compared with the conventional screw member in which the screw bottom appears. A method is provided.
In the invention of the method for manufacturing the screw member according to claim 2 , the shaft portion of the screw member is formed by work hardening to have high strength, and the fatigue resistance property and the delayed fracture resistance property are improved as compared with the conventional screw member. A method is provided for manufacturing a screw member.
In the invention of the method for manufacturing a screw member according to claim 3 , when a bending load is repeatedly applied to the screw member in a state where a plurality of members are fastened by the screw member, a portion where the stress is concentrated is an internal thread portion of the screw member. Incomplete thread formed at the non-threaded part of the screw, but the screw bottom of the incomplete thread does not show up-turning, so the stress is distributed over the entire thread bottom of the incomplete thread. Thus, there is provided a method for manufacturing a screw member in which the fatigue resistance and delayed fracture resistance of the screw member are sufficiently satisfied.

本発明によれば、ねじ転造加工時、ねじ山の頂部の一部が欠けた転造ダイスによって転造された場合でも、応力の集中する部位のねじ底部にまくれ込みが現出されず、耐疲労特性及び耐遅れ破壊特性等が向上するねじ部材の製造方法を提供することができる。 According to the present invention, at the time of thread rolling processing, even when rolled by a rolling die that lacks a part of the top of the screw thread, no turn-up appears on the screw bottom of the part where the stress is concentrated, It is possible to provide a method for manufacturing a screw member with improved fatigue resistance and delayed fracture resistance.

以下、本発明を実施するための最良の形態を図１〜図５に基いて詳細に説明する。
本発明の実施の形態に係るねじ部材は、図１に示すように、例えば、キャップ６０をコンロッド６１に取り付ける際のコンロッドボルト１に採用されている。
本コンロッドボルト１は、図２に示すように、頭部２と軸部３とから構成されている。
本コンロッドボルト１の軸部３には、図２及び図３に示すように、コンロッド６１の雌ねじ部６４との螺合部位にねじ山断面形状が略三角形状となる完全ねじ部４が形成されると共に、コンロッド６１の雌ねじ部６４との非螺合部位、すなわち、コンロッド６１の貫通孔６３及びキャップ６０の貫通孔６２の大半部分に位置する部位にねじ山断面形状が略台形状となる不完全ねじ部５が形成される。また、完全ねじ部４は、軸部３の先端部に形成されると共に、不完全ねじ部５は、軸部３の中間部に形成される。 Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS.
As shown in FIG. 1, the screw member according to the embodiment of the present invention is employed in, for example, a connecting rod bolt 1 when a cap 60 is attached to a connecting rod 61.
This connecting rod bolt 1 is comprised from the head 2 and the axial part 3, as shown in FIG.
As shown in FIGS. 2 and 3, the shaft portion 3 of the connecting rod bolt 1 is formed with a complete screw portion 4 having a substantially triangular thread cross-sectional shape at the screwing portion with the female screw portion 64 of the connecting rod 61. At the same time, the thread cross-sectional shape is not substantially trapezoidal at the non-threaded portion of the connecting rod 61 with the female threaded portion 64, that is, the portion of the connecting rod 61 located in the most part of the through hole 63 and the through hole 62 of the cap 60. A complete thread portion 5 is formed. Further, the complete screw portion 4 is formed at the tip portion of the shaft portion 3, and the incomplete screw portion 5 is formed at an intermediate portion of the shaft portion 3.

そして、本コンロッドボルト１の製造方法を図２に基いて説明する。
まず、第１の工程として、図２（ａ）に示すように、本コンロッドボルト１は、冷間型鍛造により、棒状体の一端部がブロック状の頭部２に型成形されて、頭部２と軸部３とに形成される。 And the manufacturing method of this connecting rod bolt 1 is demonstrated based on FIG.
First, as shown in FIG. 2 (a), as a first step, the connecting rod bolt 1 is formed by cold forging one end of a rod-like body into a block-like head 2, and the head 2 and the shaft portion 3.

次に、第２の工程として、図２（ｂ）に示すように、図２（ａ）に示す本コンロッドボルト１の軸部３が、転造成形加工により、先端部及び基端部に大径軸部４ａが形成されると共に、中間部に小径軸部５ａが形成される。この大径軸部４ａの外径は、図２（ａ）に示す軸部３の外径よりも小径で、最終的にねじ転造加工により形成される完全ねじ部４の外径に形成される。また、小径軸部５ａは、大径軸部４ａの外径よりも、０．０１ｍｍ〜０．５ｍｍの所定値小径に形成される。
また、先端部に形成される大径軸部４ａの長さは、図３に示すように、コンロッド６１の雌ねじ部６４の長さと略同一に設定されている。一方、中間部に形成される小径軸部５ａの長さは、コンロッド６１の貫通孔６３の長さに、キャップ６０の貫通孔６２の約６割程度の長さを合わせた相当の長さに設定されている。また、図２（ｂ）に示すように、軸部３の小径軸部５ａと大径軸部４ａとは、テーパ面またはＲ面（図２（ｂ）ではテーパ面）６ａで接続される。
なお、軸部３が転造成形加工により大径軸部４ａと小径軸部５ａとに形成される第２の工程は、頭部２がブロック状に型成形される第１の工程に含まれる場合もある。 Next, as a second step, as shown in FIG. 2B, the shaft portion 3 of the connecting rod bolt 1 shown in FIG. A diameter shaft portion 4a is formed, and a small diameter shaft portion 5a is formed in the middle portion. The outer diameter of the large-diameter shaft portion 4a is smaller than the outer diameter of the shaft portion 3 shown in FIG. 2A, and is finally formed to be the outer diameter of the complete thread portion 4 formed by thread rolling. The Further, the small diameter shaft portion 5a is formed to have a small diameter of a predetermined value of 0.01 mm to 0.5 mm than the outer diameter of the large diameter shaft portion 4a.
Further, the length of the large-diameter shaft portion 4a formed at the tip portion is set to be substantially the same as the length of the female thread portion 64 of the connecting rod 61 as shown in FIG. On the other hand, the length of the small-diameter shaft portion 5a formed in the intermediate portion is equivalent to the length of the through hole 63 of the connecting rod 61 and the length of about 60% of the through hole 62 of the cap 60. Is set. Further, as shown in FIG. 2B, the small-diameter shaft portion 5a and the large-diameter shaft portion 4a of the shaft portion 3 are connected by a taper surface or an R surface (taper surface in FIG. 2B).
In addition, the 2nd process in which the axial part 3 is formed in the large diameter axial part 4a and the small diameter axial part 5a by a rolling molding process is included in the 1st process by which the head 2 is shape-molded in block shape. In some cases.

次に、第３の工程として、図２（ｂ）に示すコンロッドボルト１の小径軸部５ａ及び先端部分の大径軸部４ａを、図６に示す第１及び第２転造ダイス７０、７１によりねじ転造加工することで、図２（ｃ）に示すように、本コンロッドボルト１の先端部分の大径軸部４ａには、コンロッド６１の雌ねじ部６４と螺合される、ねじ山断面形状が略三角形となる完全ねじ部４が形成される。一方、本コンロッドボルト１の小径軸部５ａには、ねじ山断面形状が略台形状となる不完全ねじ部５が形成される。なお、完全ねじ部４の各ねじ山の角度と、不完全ねじ山５の各ねじ山の角度とは略同一である。   Next, as a third step, the small-diameter shaft portion 5a and the large-diameter shaft portion 4a of the tip end portion of the connecting rod bolt 1 shown in FIG. 2B are replaced with the first and second rolling dies 70 and 71 shown in FIG. 2 (c), the thread section of the threaded portion of the connecting rod bolt 1 that is screwed with the female threaded portion 64 of the connecting rod 61. As shown in FIG. A complete screw portion 4 having a substantially triangular shape is formed. On the other hand, the small diameter shaft portion 5a of the connecting rod bolt 1 is formed with an incomplete screw portion 5 having a substantially trapezoidal cross section. In addition, the angle of each screw thread of the complete screw part 4 and the angle of each screw thread of the incomplete screw thread 5 are substantially the same.

そして、このように形成された本コンロッドボルト１を、図３に示すように、キャップ６０の貫通孔６２及びコンロッド６１の貫通孔６３に挿通して、先端部の完全ねじ部４をコンロッド６１の雌ねじ部６４に螺合することにより、キャップ６０をコンロッド６１に取り付けている。   Then, the connecting rod bolt 1 thus formed is inserted into the through hole 62 of the cap 60 and the through hole 63 of the connecting rod 61 as shown in FIG. The cap 60 is attached to the connecting rod 61 by being screwed into the female screw portion 64.

そこで、本コンロッドボルト１に、ねじ転造加工にて完全ねじ部４及び不完全ねじ部５が形成される際、ねじ山の頂部の一部が欠けた転造ダイス７０、７１により転造された場合、図４に示すように、本コンロッドボルト１の完全ねじ部４の範囲には、従来と同様にそのねじ底部にまくれ込み５５が現出されるが、不完全ねじ部５の範囲には、各転造ダイス７０、７１の各ねじ山間のねじ溝に、小径軸部５ａの材料が完全に充填されず過転造の状態にならないために、不完全ねじ部５のねじ底部にまくれ込み５５が現出されることはない。   Therefore, when the complete thread portion 4 and the incomplete thread portion 5 are formed on the connecting rod bolt 1 by the thread rolling process, the connecting rod bolt 1 is rolled by the rolling dies 70 and 71 in which a part of the top of the thread is missing. In this case, as shown in FIG. 4, in the range of the complete thread portion 4 of the connecting rod bolt 1, a turn-up 55 appears at the bottom of the screw as in the conventional case, but in the range of the incomplete thread portion 5. Since the material of the small-diameter shaft portion 5a is not completely filled in the thread grooves between the respective screw threads of the respective rolling dies 70, 71, the overrolling state does not occur. No 55 will appear.

そこで、上述したような製造方法を採用することにより、不完全ねじ部５のねじ底部に、まくれ込み５５が現出されないことを図５に示すグラフに基いて説明する。図５は、切り込み量（図６に示す第２転造ダイス７１が被加工軸部の外周面に接触してから第１転造ダイス７０側に移動した距離）と、ねじ底部に現出したまくれ込み量（亀裂の深さ）との関係をグラフにしたものである。条件としては、被加工軸部の外径が９ｍｍであり、第１及び第２転造ダイス７０、７１のねじ山の高さが０．７ｍｍで、しかも、第１転造ダイス７０は、そのねじ山の頂部の一部が０．１５ｍｍ欠けた状態である。   Therefore, it will be described based on the graph shown in FIG. 5 that the turning-up 55 does not appear at the screw bottom portion of the incomplete screw portion 5 by adopting the manufacturing method as described above. FIG. 5 shows the amount of cut (the distance that the second rolling die 71 shown in FIG. 6 moved to the first rolling die 70 side after contacting the outer peripheral surface of the shaft to be machined) and the screw bottom. This is a graph showing the relationship between the amount of cracking (crack depth). As the conditions, the outer diameter of the shaft to be processed is 9 mm, the thread height of the first and second rolling dies 70 and 71 is 0.7 mm, and the first rolling die 70 is A part of the top of the thread is missing 0.15 mm.

そして、この条件において、切り込み量とまくれ込み量との関係を検証してみると、図５から解るように、切り込み量が０．６〜０．６５ｍｍの範囲、すなわち、被加工軸部に形成されたねじ山の高さが正規の高さ（０．７ｍｍ）にまで達していないねじ山断面形状が略台形状となる不完全ねじ部５の状態では、まくれ込み５５は現出していない。しかしながら、切り込み量が０．７ｍｍの時、すなわち、被加工軸部の形成されたねじ山の高さが正規の高さに達し、ねじ山断面形状が略三角形状となる完全ねじ部４が形成された時に、まくれ込み５５が現出している（まくれ込み量：０．０２７ｍｍ）。
このように、ねじ山の頂部の一部が欠けた転造ダイス７０、７１によりねじ転造加工されたとしても、ねじ山断面形状が略台形状となる不完全ねじ部５のねじ底部には、まくれ込み５５が現出されないことが解る。
また、参考ではあるが、切り込み量が０．７ｍｍよりも大きくなると、完全ねじ部４の外径が転造前の軸径９ｍｍよりも小径となり、過転造が進むことから完全ねじ部４のねじ底部に現出されたまくれ込み量も次第に増加する。 Then, when the relationship between the cut amount and the turn-up amount is verified under this condition, as shown in FIG. 5, the cut amount is in the range of 0.6 to 0.65 mm, that is, formed in the shaft portion to be processed. In the state of the incomplete thread portion 5 in which the thread cross-sectional shape in which the height of the thread thread has not reached the regular height (0.7 mm) is substantially trapezoidal, the turn-up 55 does not appear. However, when the cutting depth is 0.7 mm, that is, the height of the thread formed with the processed shaft portion reaches a normal height, and the complete thread portion 4 is formed in which the thread cross-sectional shape is substantially triangular. When it is done, the turnover 55 appears (the turnover amount: 0.027 mm).
As described above, even if the thread rolling process is performed by the rolling dies 70 and 71 in which a part of the top of the thread is missing, the thread bottom portion of the incomplete thread portion 5 in which the thread cross-sectional shape is substantially trapezoidal is formed. It turns out that the turnover 55 is not displayed.
For reference, when the cutting depth is larger than 0.7 mm, the outer diameter of the complete thread portion 4 becomes smaller than the shaft diameter 9 mm before the rolling, and the over rolling progresses. The amount of turning up that appears at the bottom of the screw also gradually increases.

次に、疲労試験により本コンロッドボルト１と従来のコンロッドボルト５１との耐疲労特性を比較した結果を説明する。
本コンロッドボルト１と従来のコンロッドボルト５１とを疲労試験機に同一条件、すなわち、本コンロッドボルト１は完全ねじ部４の全範囲を拘束した状態、また、従来のコンロッドボルト５１は、その完全ねじ部５３の先端部分で、本コンロッドボルト１の完全ねじ部４の長さ相当分を拘束した状態で設置して、それぞれのコンロッドボルト１、５１に同一の曲げ荷重を繰り返し付与して、破断回数についての比較検証を行った。
その結果、従来のコンロッドボルト５１は、略１０6回目で破断したのに対して、本コンロッドボルト１では疲労試験における合否基準となる１０7回目でも破断には至らなかった。このように、耐疲労特性において、本コンロッドボルト１が、従来のコンロッドボルト５１よりも高い強度を有していることが解る。 Next, the results of comparing the fatigue resistance characteristics of the connecting rod bolt 1 and the conventional connecting rod bolt 51 by a fatigue test will be described.
The connecting rod bolt 1 and the conventional connecting rod bolt 51 have the same conditions in the fatigue testing machine, that is, the connecting rod bolt 1 is in a state in which the entire range of the complete threaded portion 4 is constrained. At the tip of the portion 53, the length corresponding to the length of the complete threaded portion 4 of the connecting rod bolt 1 is constrained, and the same bending load is repeatedly applied to the connecting rod bolts 1 and 51. A comparative verification was conducted.
As a result, the conventional connecting rod bolt 51 broke at the approximately 10 6th time, whereas the connecting rod bolt 1 did not break even at the 10 7th time as a pass / fail criterion in the fatigue test. Thus, it can be seen that the fatigue strength of the present connecting rod bolt 1 is higher than that of the conventional connecting rod bolt 51.

以上説明したように、本発明の実施の形態では、本コンロッドボルト１を製造する際、まず、コンロッドボルト１の軸部３に、転造加工により、その先端部、すなわち、コンロッド６１の雌ねじ部６４との螺合部位に大径軸部４ａを形成すると共に、その中間部、すなわち、コンロッド６１の貫通孔６３及びキャップ６０の貫通孔６３の大半部分に位置する部位に小径軸部５ａを形成する。次に、ねじ転造加工により、大径軸部４ａにねじ山断面形状が略三角形状となる完全ねじ部４を形成すると共に、小径軸部５ａにねじ山断面形状が略台形状となる不完全ねじ部５を形成する。
そして、このように本コンロッドボルト１が製造されることで、ねじ転造加工の際、ねじ山の頂部の一部が欠けた転造ダイス７０、７１により転造された場合でも、不完全ねじ部５の範囲では、転造ダイス７０、７１の各ねじ山間のねじ溝に、小径軸部５ａの材料が完全に充填されず過転造の状態にならないために、不完全ねじ部５のねじ底部にまくれ込み５５が現出されることはない。 As described above, in the embodiment of the present invention, when the connecting rod bolt 1 is manufactured, first, the shaft portion 3 of the connecting rod bolt 1 is rolled to the tip portion thereof, that is, the female thread portion of the connecting rod 61. The large-diameter shaft portion 4a is formed at the screwed portion with the 64, and the small-diameter shaft portion 5a is formed in the middle portion thereof, that is, the portion located in the most part of the through hole 63 of the connecting rod 61 and the through hole 63 of the cap 60. To do. Next, the thread rolling process forms the complete thread portion 4 having a substantially triangular thread cross-sectional shape on the large-diameter shaft portion 4a, and the small-diameter shaft portion 5a has a substantially trapezoidal thread cross-sectional shape. A complete thread portion 5 is formed.
In addition, since the connecting rod bolt 1 is manufactured as described above, even when the rolling is performed by the rolling dies 70 and 71 in which a part of the top portion of the thread is missing at the time of thread rolling, the incomplete screw In the range of the portion 5, the screw groove between the screw threads of the rolling dies 70 and 71 is not completely filled with the material of the small-diameter shaft portion 5 a, so that the over-rolling state does not occur. The curl-in 55 does not appear at the bottom.

その結果、本コンロッドボルト１によりキャップ６０をコンロッド６１に取り付け、本コンロッドボルト１に曲げ荷重が繰り返し作用し、その応力がコンロッド６１の雌ねじ部６４と貫通孔６３との境界部分（図３及び図４参照）に位置する本コンロッドボルト１の不完全ねじ部５のねじ底部に集中しても、応力はねじ底部の全体に分散されるために、本コンロッドボルト１は、従来のコンロッドボルト５１に比べて、耐疲労特性及び耐遅れ破壊特性等が向上する。   As a result, the cap 60 is attached to the connecting rod 61 by the connecting rod bolt 1, and a bending load is repeatedly applied to the connecting rod bolt 1, and the stress is a boundary portion between the female threaded portion 64 of the connecting rod 61 and the through-hole 63 (FIGS. 3 and 3). 4), the stress is distributed over the entire bottom of the threaded bottom portion of the incomplete threaded portion 5 of the present connecting rod bolt 1, so that the connecting rod bolt 1 is connected to the conventional connecting rod bolt 51. In comparison, fatigue resistance, delayed fracture resistance, and the like are improved.

なお、本発明の実施の形態では、ねじ部材をコンロッドボルト１に限定して説明したが、自動車で使用される他のボルト、例えば、ヘッドボルト、クランクキャップボルト、フライホイールボルト、ボールジョイントボルト、ユニオンボルト、プーリボルト等にも採用することができる。   In the embodiment of the present invention, the screw member is limited to the connecting rod bolt 1, but other bolts used in an automobile, for example, a head bolt, a crank cap bolt, a flywheel bolt, a ball joint bolt, It can also be used for union bolts, pulley bolts, and the like.

図１は、本発明の実施の形態に係るコンロッドボルトによりキャップをコンロッドに取り付けた状態の図である。FIG. 1 is a view showing a state where a cap is attached to a connecting rod by connecting rod bolts according to an embodiment of the present invention. 図２は、本コンロッドボルトの製造工程を段階的に示した図である。FIG. 2 is a diagram showing the manufacturing process of the connecting rod bolt in stages. 図３は、本コンロッドボルトが、キャップの貫通孔を貫通して、コンロッドの雌ねじ部に螺合している図であるFIG. 3 is a view in which the connecting rod bolt penetrates the through hole of the cap and is screwed into the female thread portion of the connecting rod. 図４は、図３のＡ部を拡大した図である。FIG. 4 is an enlarged view of part A in FIG. 図５は、切り込み量とまくれ込み量の関係を示した図である。FIG. 5 is a diagram showing the relationship between the cutting amount and the turning amount. 図６は、ねじ転造加工の様子を示した図である。FIG. 6 is a view showing a state of thread rolling. 図７（ａ）は、従来のコンロッドボルト全体図で、（ｂ）は（ａ）のＢ部の拡大図である。FIG. 7A is an overall view of a conventional connecting rod bolt, and FIG. 7B is an enlarged view of a portion B in FIG. 図８は、従来のコンロッドボルトのねじ底部に現出されたまくれ込みの発生過程を段階的に示した図である。FIG. 8 is a diagram showing step-by-step the process of turning up appearing at the screw bottom of a conventional connecting rod bolt.

符号の説明Explanation of symbols

１ コンロッドボルト（ねじ部材），３ 軸部，４ａ 大径軸部，５ａ 小径軸部，４ 完全ねじ部，５ 不完全ねじ部，６４ 雌ねじ部
1 connecting rod bolt (screw member), 3 shaft part, 4a large diameter shaft part, 5a small diameter shaft part, 4 complete thread part, 5 incomplete thread part, 64 female thread part

Claims (3)

雌ねじ部に螺合されるねじ部材の製造方法であって、
前記ねじ部材の軸部を、小径軸部と大径軸部とに形成する工程と、
同一の転造ダイスによるねじ転造加工により、前記小径軸部にねじ山断面形状が略台形状となる不完全ねじ部を形成すると同時に、前記大径軸部にねじ山断面形状が略三角形状となる完全ねじ部を形成する工程と、
を含むことを特徴とするねじ部材の製造方法。 A method of manufacturing a screw member to be screwed into a female screw part,
Forming a shaft portion of the screw member into a small-diameter shaft portion and a large-diameter shaft portion;
The thread rolling process by the same rolling die, the same time the thread cross-section forms the incomplete thread portion becomes a substantially trapezoidal shape on the small diameter shaft portion, wherein the thread cross-section on the large-diameter shaft portion substantially triangular A step of forming a complete thread portion to be shaped;
The manufacturing method of the screw member characterized by including. 前記軸部を前記小径軸部と前記大径軸部とに形成する前記工程では、前記小径軸部と前記大径軸部とが転造加工によって形成されることを特徴とする請求項１に記載のねじ部材の製造方法。 2. The method according to claim 1 , wherein in the step of forming the shaft portion in the small diameter shaft portion and the large diameter shaft portion, the small diameter shaft portion and the large diameter shaft portion are formed by rolling. The manufacturing method of the screw member of description. 前記不完全ねじ部は、前記雌ねじ部との非螺合部位に形成されると共に、前記完全ねじ部は、前記雌ねじ部との螺合部位に形成されることを特徴とする請求項１または２に記載のねじ部材の製造方法。 The said incomplete thread part is formed in the non-screwing site | part with the said internal thread part, and the said complete thread part is formed in the threading site | part with the said internal thread part, The Claim 1 or 2 characterized by the above-mentioned. The manufacturing method of the screw member of Claim 2.
JP2006195660A 2006-07-18 2006-07-18 Manufacturing method of screw member Expired - Fee Related JP5036238B2 (en)

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