JP6098246B2 - Burring punch and burring method - Google Patents
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本発明は、鋼板などのような金属製で板状の被加工部材に円筒状の伸びフランジを成形するバーリング加工において、加工用金型として用いられるパンチに関し、特に、伸びフランジの成形性の向上を図ったバーリング加工用パンチおよびバーリング加工方法に関する。 The present invention relates to a punch used as a processing die in a burring process in which a cylindrical stretch flange is formed on a plate-like workpiece made of metal such as a steel plate, and in particular, improvement of formability of the stretch flange. The present invention relates to a burring punch and a burring method.
通常、バーリング加工が施される被加工部材には、予め打ち抜き加工や切削加工により下穴が設けられ、バーリング加工は、そのように下穴が設けられた被加工部材に対して行われる。バーリング加工では、被加工部材の下穴にパンチを押し込み、これに伴って、被加工部材の下穴の周辺部分がパンチの押し込み方向に伸ばされながら径方向に拡大する。これにより、被加工部材には円筒状に突き出した伸びフランジ（以下、単に「フランジ」ともいう）が成形される。 Usually, a workpiece to be subjected to burring is provided with a pilot hole in advance by punching or cutting, and the burring is performed on the workpiece to be provided with such a pilot hole. In the burring process, the punch is pushed into the pilot hole of the workpiece, and accordingly, the peripheral portion of the pilot hole of the workpiece is expanded in the radial direction while being stretched in the punch pushing direction. Thereby, an elongated flange (hereinafter also simply referred to as “flange”) protruding in a cylindrical shape is formed on the workpiece.
このようにして成形されたフランジの肉厚は、厳密には、先端部分（穴縁）に近づくほど薄くなっている。フランジの先端部分は被加工部材の元々の下穴の周縁部に相当し、この部分に近いほど、バーリング加工の過程で加工度が大きくて、伸びおよび拡大の変形が著しくなるからである。 Strictly speaking, the thickness of the flange formed in this way becomes thinner toward the tip portion (hole edge). This is because the front end portion of the flange corresponds to the peripheral edge portion of the original prepared hole of the workpiece, and the closer to this portion, the greater the degree of processing in the process of burring, and the greater the deformation of elongation and expansion.
従来のバーリング加工用パンチとしては、下記のものがある。例えば、特許文献１には、下穴よりも小径の小径部と、下穴よりも大径で伸びフランジの仕上り内径と同じ直径を有する大径部と、小径部の直径から大径部の直径まで連続的に直径を拡大させながら小径部と大径部とを滑らかにつなぐ拡径部と、を備える先細りの円柱棒状のパンチが記載されている。同文献に記載される従来のパンチでは、より均一な肉厚のフランジを成形するために、拡径部の周面は、軸方向に沿った縦断面において曲率半径が１２ｍｍ以上で１８ｍｍ以下の外側に膨らむ曲線とされている。 Conventional burring punches include the following. For example, in Patent Document 1, a small diameter portion having a diameter smaller than that of the prepared hole, a large diameter portion having a diameter larger than that of the prepared hole and having the same diameter as the finished inner diameter of the flange, and a diameter of the large diameter portion from the diameter of the small diameter portion. A tapered columnar punch having a diameter-enlarged portion that smoothly connects a small-diameter portion and a large-diameter portion while continuously increasing the diameter is described. In the conventional punch described in the same document, in order to form a flange having a more uniform thickness, the peripheral surface of the enlarged diameter portion has an outer radius of curvature of 12 mm or more and 18 mm or less in a longitudinal section along the axial direction. It is said to be a curved curve.
バーリング加工では、上述した加工の原理により、成形された伸びフランジの先端部分の肉厚が他の部分よりも薄くなる。また、そのフランジ先端部分の肉厚は周方向で不均一になることがある。これらに起因し、しばしば、フランジ先端部分に割れが発生し、成形不良が生じることが問題となる。したがって、バーリング加工においては、フランジの成形性の向上が命題とされている。 In the burring process, the thickness of the tip end portion of the formed stretch flange is thinner than the other portions due to the above-described processing principle. In addition, the thickness of the flange tip may be uneven in the circumferential direction. Due to these problems, there is often a problem that cracks occur at the flange tip portion and molding defects occur. Therefore, in the burring process, improvement of the formability of the flange is a proposition.
本発明は、上記の実情に鑑みてなされたものであり、バーリング加工の際に伸びフランジの成形性を向上させ、伸びフランジの先端部分で割れの発生を抑制できるバーリング加工用パンチおよびバーリング加工方法を提供することを目的とする。 The present invention has been made in view of the above circumstances, and it is possible to improve the formability of the stretch flange during burring and to suppress the occurrence of cracks at the tip portion of the stretch flange and the burring method. The purpose is to provide.
本発明の要旨は、下記（Ｉ）のバーリング加工用パンチ、および下記（II）のバーリング加工方法にある。 The gist of the present invention resides in the following (I) burring punch and the following (II) burring method.
（Ｉ）板状の被加工部材に設けられた下穴を押し拡げて伸びフランジを成形するバーリング加工に用いられるパンチであって、
当該パンチは、
バーリング加工の初期に前記下穴の周縁部に接触する先端部と、
前記伸びフランジの仕上り内径と同じ直径を有する円柱状の大径部と、
前記先端部と前記大径部とを滑らかにつなぎ後端側ほど直径が拡大する円錐台状の拡径部と、を備え、
前記先端部の開き角が９０°以上で、前記拡径部の開き角が６０°以下であり、前記先端部の後端の直径ｄ1が前記下穴の直径ｄ0との関係で下記（１）式の条件を満たすことを特徴とするバーリング加工用パンチ、である。
ｄ0＜ｄ1≦１．２×ｄ0 …（１）
(I) A punch used for burring processing for forming an elongated flange by expanding a pilot hole provided in a plate-shaped workpiece,
The punch is
A tip that contacts the peripheral edge of the pilot hole in the initial stage of burring;
A cylindrical large diameter portion having the same diameter as the finished inner diameter of the stretch flange;
The tip portion and the large-diameter portion are smoothly connected, and a frustoconical diameter-enlarged portion whose diameter increases toward the rear end side,
The opening angle of the tip portion is 90 ° or more, the opening angle of the enlarged-diameter portion is 60 ° or less, and the diameter d 1 of the rear end of the tip portion is as follows in relation to the diameter d 0 of the pilot hole ( 1) A burring punch that satisfies the condition of the expression (1).
d 0 <d 1 ≦ 1.2 × d 0 (1)
このパンチは、前記先端部と前記拡径部との間にこれらの両者を滑らかにつなぐ肩部を備え、この肩部の周面は、軸方向に沿った縦断面において曲率半径が３０ｍｍ以下の円弧状であることが好ましい。 The punch includes a shoulder portion that smoothly connects both the tip portion and the diameter-expanded portion, and a circumferential surface of the shoulder portion has a curvature radius of 30 mm or less in a longitudinal section along the axial direction. An arc shape is preferred.
（II）板状の被加工部材に設けられた下穴を押し拡げて伸びフランジを成形するバーリング加工方法であって、
当該バーリング加工方法に用いられるパンチは、
バーリング加工の初期に前記下穴の周縁部に接触する先端部と、
前記伸びフランジの仕上り内径と同じ直径を有する円柱状の大径部と、
前記先端部と前記大径部とを滑らかにつなぎ後端側ほど直径が拡大する円錐台状の拡径部と、を備え、
前記先端部の開き角が９０°以上で、前記拡径部の開き角が６０°以下であり、前記先端部の後端の直径ｄ1が前記下穴の直径ｄ0との関係で下記（１）式の条件を満たすことを特徴とするバーリング加工方法、である。
ｄ0＜ｄ1≦１．２×ｄ0 …（１）
(II) A burring method for forming an elongated flange by expanding a prepared hole provided in a plate-shaped workpiece,
The punch used in the burring method is
A tip that contacts the peripheral edge of the pilot hole in the initial stage of burring;
A cylindrical large diameter portion having the same diameter as the finished inner diameter of the stretch flange;
The tip portion and the large-diameter portion are smoothly connected, and a frustoconical diameter-enlarged portion whose diameter increases toward the rear end side,
The opening angle of the tip portion is 90 ° or more, the opening angle of the enlarged-diameter portion is 60 ° or less, and the diameter d 1 of the rear end of the tip portion is as follows in relation to the diameter d 0 of the pilot hole ( 1) A burring method characterized by satisfying the condition of equation (1).
d 0 <d 1 ≦ 1.2 × d 0 (1)
この加工方法で用いられるパンチは、前記先端部と前記拡径部との間にこれらの両者を滑らかにつなぐ肩部を備え、この肩部の周面は、軸方向に沿った縦断面において曲率半径が３０ｍｍ以下の円弧状であることが好ましい。 The punch used in this processing method includes a shoulder portion that smoothly connects both the tip portion and the enlarged diameter portion, and the peripheral surface of the shoulder portion has a curvature in a longitudinal section along the axial direction. An arc shape with a radius of 30 mm or less is preferable.
本発明のバーリング加工用パンチおよびバーリング加工方法によれば、被加工部材の下穴周縁部において、延性低下の軽減と周方向での肉厚の均一化を同時に図ることができ、バーリング加工の際に伸びフランジの成形性を向上させ、フランジ先端部分で割れの発生を抑制することが可能になる。 According to the burring punch and the burring method of the present invention, the reduction in ductility and the uniform thickness in the circumferential direction can be simultaneously achieved at the peripheral edge of the prepared hole in the workpiece. Thus, it is possible to improve the formability of the flange and suppress the occurrence of cracks at the flange tip.
本発明者は、上記目的を達成するため、割れが発生する伸びフランジの先端部分、すなわち被加工部材の元々の下穴周縁部に着目した。そして、その下穴周縁部を含む下穴周辺部分のバーリング加工時における変形挙動についてパンチ形状の影響を把握すべく、種々の解析および試験を実施し、鋭意検討を重ねた。その結果、下記の知見を得た。 In order to achieve the above-mentioned object, the present inventor has focused on the tip end portion of the stretch flange where cracking occurs, that is, the original peripheral edge of the prepared hole of the workpiece. And in order to grasp the influence of a punch shape about the deformation | transformation behavior at the time of burring of the pilot hole periphery part including the peripheral part of the pilot hole, various analyzes and tests were carried out and earnest examination was repeated. As a result, the following knowledge was obtained.
図１は、従来の一般的なパンチを用いたバーリング加工の状況を模式的に示す図であり、同図（ａ）は加工前の状態を、同図（ｂ）は加工初期の状態を、同図（ｃ）は加工完了時の状態をそれぞれ示す。なお、同図および以降のバーリング加工の状況を説明する図では、理解を容易にするため、基本的にパンチおよび被加工部材のみを図示し、ダイ、ブランクホルダー等（これらは通常と同様でよい。）の図示は省略する。同図に示す従来のパンチ１０１は、例えば前記特許文献１に記載のパンチに相当する。このパンチ１０１は、先端が被加工部材１０の下穴１１の直径ｄ0よりも小さくて後端側ほど直径が拡大する円錐状の拡径部１０３と、この拡径部１０３に滑らかにつながり伸びフランジ１３の仕上り内径と同じ直径ｄ2を有する大径部１０４と、を備える。以下、このパンチ１０１を、その拡径部１０３の円錐形状にならって、円錐パンチと称する。 FIG. 1 is a diagram schematically showing a state of burring processing using a conventional general punch, where FIG. 1 (a) shows a state before processing, FIG. 1 (b) shows an initial state of processing, FIG. 2C shows the state when the machining is completed. In the figure and the subsequent figures for explaining the burring process, for the sake of easy understanding, only the punch and the workpiece are basically shown, and a die, a blank holder, etc. (these may be the same as usual). .) Is omitted. The conventional punch 101 shown in the figure corresponds to the punch described in Patent Document 1, for example. This punch 101 has a conical diameter-expanded portion 103 whose tip is smaller than the diameter d 0 of the pilot hole 11 of the workpiece 10 and whose diameter increases toward the rear end side, and is smoothly connected to the diameter-expanded portion 103 and extends. A large-diameter portion 104 having the same diameter d 2 as the finished inner diameter of the flange 13. Hereinafter, the punch 101 is referred to as a conical punch, following the conical shape of the enlarged diameter portion 103.
従来の円錐パンチ１０１は拡径部１０３の開き角αが鋭角である。このため、従来の円錐パンチ１０１では、バーリング加工の初期に、図１（ｂ）に示すように、拡径部１０３が被加工部材１０の下穴１１の周縁部１２と急峻な角度で接触する。そして、そのままパンチ１０１が下穴１１に押し込まれることにより、被加工部材１０の下穴１１の周辺部分は、開き角αが鋭角の拡径部１０３の周面に沿って急激に伸び変形するとともに拡大変形する。 In the conventional conical punch 101, the opening angle α of the enlarged diameter portion 103 is an acute angle. Therefore, in the conventional conical punch 101, as shown in FIG. 1B, the enlarged diameter portion 103 comes into contact with the peripheral edge portion 12 of the prepared hole 11 of the workpiece 10 at a steep angle in the initial stage of burring. . Then, when the punch 101 is pushed into the pilot hole 11 as it is, the peripheral portion of the pilot hole 11 of the workpiece 10 is rapidly stretched and deformed along the peripheral surface of the enlarged diameter portion 103 having an acute angle α. Enlarge and deform.
図２は、図１に示す従来の円錐パンチの一例として開き角αを３０°とした場合の被加工部材の下穴周辺部分の変形挙動を表す図である。同図に示す下穴周辺部分の変形挙動は、被加工部材として板厚が３．２ｍｍの高強度熱延鋼板を採用し、直径ｄ0が１０ｍｍの下穴に対し、開き角αが３０°の円錐パンチを用いたバーリング加工を想定してＦＥＭ解析を行った結果であり、穴拡げ率が５０％に達した時点の状態を例示している。ここでいう穴拡げ率とは、下穴の元々の直径ｄ0に対するその直径の拡大変化量のことを意味する。同図では、下穴周辺部分に生じる相当塑性ひずみの大きさを濃淡で表示しており、濃淡が濃い領域ほど相当塑性ひずみが大きいことを表す。 FIG. 2 is a diagram showing the deformation behavior of the peripheral portion of the prepared member when the opening angle α is 30 ° as an example of the conventional conical punch shown in FIG. The deformation behavior of the peripheral portion of the pilot hole shown in the figure employs a high-strength hot-rolled steel plate having a thickness of 3.2 mm as a workpiece, and the opening angle α is 30 ° with respect to the pilot hole having a diameter d 0 of 10 mm. This is a result of FEM analysis assuming a burring process using a conical punch, and illustrates a state at the time when the hole expansion rate reaches 50%. The hole expansion rate here means the amount of expansion change of the diameter with respect to the original diameter d 0 of the pilot hole. In the figure, the magnitude of the equivalent plastic strain generated in the peripheral portion of the pilot hole is displayed in shades, and the darker shade region indicates that the equivalent plastic strain is greater.
上述のとおり、従来の円錐パンチ１０１は、バーリング加工の初期に、拡径部１０３が被加工部材１０の下穴１１の周縁部１２と急峻な角度で接触し、そのまま押し込まれる（図１（ｂ）参照）。このため、図２に示すように、被加工部材の下穴の周辺部分は、その周縁部が著しく潰れて相当塑性ひずみが大きくなり、その結果として、その周縁部に限って加工硬化が著しく、延性が過度に低下する。このような延性の低下は、被加工部材の板厚が厚いほど、また、パンチの拡径部と被加工部材の下穴の周縁部との接触角度が急峻であるほど、顕著に起こる。そして、下穴周縁部で延性の低下が過度になるので、バーリング加工後、その下穴周縁部に相当する伸びフランジの先端部分に、割れが発生する。 As described above, in the conventional conical punch 101, at the initial stage of burring, the enlarged diameter portion 103 comes into contact with the peripheral edge 12 of the pilot hole 11 of the workpiece 10 at a steep angle and is pushed in as it is (FIG. 1B). )reference). For this reason, as shown in FIG. 2, the peripheral portion of the pilot hole of the workpiece is significantly crushed in the peripheral portion, resulting in considerable plastic strain, and as a result, the work hardening is remarkable only in the peripheral portion, Ductility decreases excessively. Such a decrease in ductility occurs more markedly as the plate thickness of the workpiece is thicker and as the contact angle between the punch diameter-expanded portion and the peripheral edge portion of the pilot hole of the workpiece is steeper. And since a ductility fall becomes excessive in a pilot hole peripheral part, a crack generate | occur | produces in the front-end | tip part of the extending flange corresponded to the peripheral hole peripheral part after burring.
これに対し、拡径部１０３の開き角αが大きい円錐パンチでは、バーリング加工の初期に、拡径部１０３が被加工部材１０の下穴１１の周縁部１２と緩やかな角度で接触する。そして、そのままパンチ１０１が下穴１１に押し込まれることにより、被加工部材１０の下穴１１の周辺部分は、開き角αが大きい拡径部１０３の周面に沿って緩慢に伸び変形するとともに拡大変形する。 On the other hand, in the conical punch in which the opening angle α of the enlarged diameter portion 103 is large, the enlarged diameter portion 103 comes into contact with the peripheral edge portion 12 of the prepared hole 11 of the workpiece 10 at a moderate angle in the initial stage of burring. Then, when the punch 101 is pushed into the pilot hole 11 as it is, the peripheral part of the pilot hole 11 of the workpiece 10 is slowly extended and deformed along the peripheral surface of the enlarged diameter part 103 having a large opening angle α. Deform.
図３は、図１に示す円錐パンチにおける開き角αを９０°とした場合の被加工部材の下穴周辺部分の変形挙動を表す図である。同図に示す下穴周辺部分の変形挙動は、前記図２の場合と同様の被加工部材に対し、開き角αが９０°の円錐パンチを用いたバーリング加工を想定してＦＥＭ解析を行った結果であり、穴拡げ率が５０％に達した時点の状態を例示している。 FIG. 3 is a diagram illustrating the deformation behavior of the peripheral portion of the workpiece hole when the opening angle α of the conical punch shown in FIG. 1 is 90 °. The deformation behavior of the peripheral portion of the pilot hole shown in the figure was FEM analyzed on the same workpiece as in the case of FIG. 2 assuming burring using a conical punch with an opening angle α of 90 °. It is a result and has illustrated the state at the time of the hole expansion rate reaching 50%.
図３に示すように、開き角αが９０°の円錐パンチを用いた場合、開き角αが３０°である従来の円錐パンチを用いた場合（前記図２参照）と比較し、被加工部材の下穴の周縁部に生じる相当塑性ひずみが小さくなり、その結果として、その下穴周縁部での延性の低下が軽減される。したがって、バーリング加工の初期に被加工部材の下穴の周縁部とパンチとが緩やかな角度で接触するように、パンチの開き角を大きくすれば、下穴周縁部での延性低下の軽減に伴って、延性低下に起因したフランジ先端部分の割れの発生を抑制することができる。 As shown in FIG. 3, when using a conical punch with an opening angle α of 90 °, compared to a conventional conical punch with an opening angle α of 30 ° (see FIG. 2), the workpiece The equivalent plastic strain generated at the peripheral portion of the pilot hole is reduced, and as a result, the reduction in ductility at the peripheral portion of the pilot hole is reduced. Therefore, if the punch opening angle is increased so that the peripheral edge of the prepared hole and the punch come into contact with each other at a gentle angle in the initial stage of burring, the reduction in ductility at the peripheral edge of the prepared hole is reduced. Thus, it is possible to suppress the occurrence of cracks at the flange tip portion due to the ductility reduction.
ただし、パンチの開き角αが大きいままでパンチの押し込みを継続すると、被加工部材の下穴周辺部分の伸びおよび拡大の変形が緩慢に行われるため、特に、加工度が大きくなる下穴周縁部の肉厚、すなわちフランジ先端部分の肉厚が周方向で不均一になり、その結果として、周方向での肉厚が薄い部分に割れが発生する。この点、パンチの開き角αが鋭角であると、被加工部材の下穴周辺部分の伸びおよび拡大の変形が急激に行われるため、フランジ先端部分における周方向での肉厚の不均一は生じにくい。 However, if the punch push-in is continued with the punch opening angle α being large, the expansion and expansion of the peripheral hole portion of the workpiece to be processed will be performed slowly. , That is, the thickness at the tip of the flange becomes uneven in the circumferential direction, and as a result, cracks occur in the portion where the thickness in the circumferential direction is thin. In this regard, if the punch opening angle α is an acute angle, the peripheral portion of the workpiece hole is abruptly expanded and enlarged, so that the thickness of the flange tip is uneven in the circumferential direction. Hateful.
これらのことから、被加工部材の下穴周縁部において、延性低下の軽減と周方向での肉厚の均一化を同時に図り、フランジ先端部分の割れの発生を抑制するには、バーリング加工の初期段階では、パンチの開き角を大きくし、被加工部材の下穴周辺部分の伸びおよび拡大の変形を積極的に行う段階では、パンチの開き角を鋭角とするのが有効であるといえる。 From these facts, in order to simultaneously reduce the ductility reduction and make the wall thickness uniform in the circumferential direction at the peripheral edge of the prepared hole in the workpiece, to suppress the crack at the flange tip, the initial stage of burring In the stage, it can be said that it is effective to increase the punch opening angle and to make the punch opening angle an acute angle in the stage of positively expanding and enlarging deformation of the peripheral portion of the prepared member.
本発明は、上記の知見に基づき完成させたものである。以下に、本発明のバーリング加工用パンチ、およびこのパンチを用いたバーリング加工方法について、その好ましい態様を説明する。 The present invention has been completed based on the above findings. Below, the preferable aspect is demonstrated about the punch for burring processing of this invention, and the burring processing method using this punch.
図４は、本発明のパンチを用いたバーリング加工の状況を模式的に示す図であり、同図（ａ）は加工前の状態を、同図（ｂ）は加工初期の状態を、同図（ｃ）は加工完了時の状態をそれぞれ示す。同図に示す本発明のパンチ１は、先端側から順に、先端部２と、拡径部３と、伸びフランジ１３の仕上り内径と同じ直径ｄ2を有する円柱状の大径部４とを備える。 FIG. 4 is a diagram schematically showing the state of burring processing using the punch of the present invention, where FIG. 4 (a) shows the state before processing, FIG. 4 (b) shows the initial state of processing, and FIG. (C) shows the state when the machining is completed. Punch 1 of the present invention shown in the figure includes in order from the distal side, the distal end portion 2, and the enlarged diameter portion 3, and a cylindrical large diameter portion 4 having the same diameter d 2 and finish the inner diameter of the stretch flange 13 .
先端部２は、開き角φが９０°以上であり、バーリング加工の初期に被加工部材１０の下穴１１の周縁部１２に接触するものである（図４（ｂ）参照）。また、先端部２は、その後端の直径ｄ1が被加工部材１０の下穴１１の直径ｄ0との関係で下記（１）式の条件を満たすものである。
ｄ0＜ｄ1≦１．２×ｄ0 …（１）
The front end portion 2 has an opening angle φ of 90 ° or more, and contacts the peripheral edge portion 12 of the pilot hole 11 of the workpiece 10 at the initial stage of burring (see FIG. 4B). Further, the distal end portion 2 satisfies the following expression (1) in relation to the diameter d 1 of the rear end thereof being related to the diameter d 0 of the pilot hole 11 of the workpiece 10.
d 0 <d 1 ≦ 1.2 × d 0 (1)
先端部２の開き角φが９０°以上である場合、その後端直径ｄ1が１．２×ｄ0を超えると、被加工部材１０の下穴１１の周縁部１２、すなわち成形されたフランジ１３の先端部分における周方向での肉厚の不均一が顕著になり、割れが発生し易くなるからである。要するに、先端部２の後端直径ｄ1は、フランジ先端部分における周方向での肉厚の均一化の観点からは小さい方が望ましい。このため、先端部２の後端直径ｄ1は、好ましくは１．１×ｄ0以下であり、より好ましくは１．０５×ｄ0以下である。 When the opening angle φ of the distal end portion 2 is 90 ° or more, when the rear end diameter d 1 exceeds 1.2 × d 0 , the peripheral edge portion 12 of the prepared hole 11 of the workpiece 10, that is, the molded flange 13. This is because unevenness in the thickness in the circumferential direction at the front end portion of the steel becomes prominent and cracking is likely to occur. In short, the rear end diameter d 1 of the front end portion 2 is desirably smaller from the viewpoint of uniform thickness in the circumferential direction at the front end portion of the flange. For this reason, the rear end diameter d 1 of the front end portion 2 is preferably 1.1 × d 0 or less, and more preferably 1.05 × d 0 or less.
先端部２の開き角φは、９０°以上であれば、バーリング加工の初期に被加工部材１０の下穴１１の周縁部１２に接触する限り、特に限定はない。すなわち、先端部２の開き角φは最大で１８０°としてもよく、この場合、先端部２の周面は単なる平坦面となる。先端部２の開き角φを９０°以上とすれば、バーリング加工の初期に被加工部材１０の下穴１１の周縁部１２とパンチ１（先端部２）とが緩やかな角度で接触するので、下穴周縁部１２での延性の低下が軽減され、延性低下に起因したフランジ先端部分の割れの発生を抑制することができる。 If opening angle (phi) of the front-end | tip part 2 is 90 degrees or more, as long as it contacts the peripheral part 12 of the pilot hole 11 of the to-be-processed member 10 at the initial stage of burring processing, there will be no limitation in particular. That is, the opening angle φ of the distal end portion 2 may be 180 ° at the maximum. In this case, the peripheral surface of the distal end portion 2 is simply a flat surface. If the opening angle φ of the tip 2 is 90 ° or more, the peripheral edge 12 of the pilot hole 11 of the workpiece 10 and the punch 1 (tip 2) come into contact with each other at a moderate angle in the initial stage of burring. A decrease in ductility at the peripheral edge 12 of the pilot hole is reduced, and the occurrence of cracks in the flange tip portion due to the decrease in ductility can be suppressed.
拡径部３は、先端部２と大径部４とを滑らかにつなぎ後端側ほど直径が拡大する円錐台状であり、その開き角θが６０°以下である。拡径部３の開き角θを６０°以下とすれば、先端部２によって延性低下が軽減された被加工部材１０の下穴周縁部１２の変形に続いて、その下穴周縁部１２を含む被加工部材１０の下穴１１の周辺部分で伸びおよび拡大の変形が急激に行われるので、加工度が大きくなる下穴周縁部１２、すなわちフランジ先端部分において周方向での肉厚を均一にすることができる。 The enlarged diameter portion 3 is a truncated cone shape that smoothly connects the distal end portion 2 and the large diameter portion 4 and increases in diameter toward the rear end side, and has an opening angle θ of 60 ° or less. If the opening angle θ of the enlarged diameter portion 3 is set to 60 ° or less, following the deformation of the lower hole peripheral portion 12 of the workpiece 10 in which the decrease in ductility is reduced by the distal end portion 2, the lower hole peripheral portion 12 is included. Since the deformation of expansion and expansion is abruptly performed in the peripheral portion of the pilot hole 11 of the workpiece 10, the circumferential thickness of the pilot hole peripheral portion 12, that is, the flange tip portion where the degree of processing becomes large, is made uniform. be able to.
拡径部３の開き角θは、６０°以下であれば特に限定はない。もっとも、拡径部３の開き角θが小さ過ぎると、パンチ１の押し込みストロークが長くなる。このため、拡径部３の開き角θは、実用的には３０°以上とするのが好ましい。 The opening angle θ of the enlarged diameter portion 3 is not particularly limited as long as it is 60 ° or less. However, if the opening angle θ of the enlarged diameter portion 3 is too small, the pushing stroke of the punch 1 becomes long. For this reason, it is preferable that the opening angle θ of the enlarged diameter portion 3 is practically 30 ° or more.
大径部４の直径ｄ2（伸びフランジ１３の仕上り内径）は、１．３×ｄ0以上であるのが好ましく、より好ましくは１．５×ｄ0以上である。これらの１．３、１．５といった値は、穴拡げ率としては３０%、５０％であり、従来の技術を用いる実際の現場では、穴拡げ率がこれくらいの値以上のバーリング成形から前述の割れが問題になることが多い。言い換えると、本発明は、このように従来技術では割れが発生しやすい穴拡げ率の大きな成形において適用されることで、技術的・実用的意義を大きく発揮することができる。 The diameter d 2 of the large diameter portion 4 (finished inner diameter of the elongated flange 13) is preferably 1.3 × d 0 or more, more preferably 1.5 × d 0 or more. These values of 1.3 and 1.5 are 30% and 50% as the hole expansion rate, and in the actual site using the conventional technology, the above-mentioned burring molding with a hole expansion rate of more than this value is described above. Often cracks are a problem. In other words, the present invention can exert a great technical and practical significance by being applied to molding with a large hole expansion rate in which cracking is likely to occur in the prior art.
したがって、本発明のパンチ１によれば、被加工部材１０の下穴周縁部１２において、延性低下の軽減と周方向での肉厚の均一化を同時に図ることができ、バーリング加工の際に伸びフランジの成形性を向上させ、フランジ先端部分で割れの発生を抑制することが可能になる。 Therefore, according to the punch 1 of the present invention, it is possible to reduce the ductility and make the wall thickness uniform in the circumferential direction at the pilot hole peripheral portion 12 of the workpiece 10 at the same time, and to extend during burring. It is possible to improve the formability of the flange and suppress the occurrence of cracks at the flange tip.
図５および図６は、本発明のパンチの変形例を示す要部の拡大図である。これらの図に示すパンチ１は、前記図４に示すパンチ１の構成を基本とし、以下の構成を付加したものである。特に、図６に示すパンチ１は、先端部２の開き角φを１８０°にした構成を基本としている。 FIG. 5 and FIG. 6 are enlarged views of essential parts showing a modification of the punch of the present invention. The punch 1 shown in these drawings is based on the configuration of the punch 1 shown in FIG. 4 and is added with the following configuration. In particular, the punch 1 shown in FIG. 6 has a basic structure in which the opening angle φ of the tip 2 is 180 °.
図５、図６に示すパンチ１は、先端部２と拡径部３との間にこれらの両者を滑らかにつなぐ肩部５を備える。肩部５を備えるパンチ１は、被加工部材１０の下穴周辺部分の変形を先端部２によるものから拡径部３によるものに移行する際に、その移行を滑らかに行うことができる。 The punch 1 shown in FIGS. 5 and 6 includes a shoulder portion 5 between the tip portion 2 and the enlarged diameter portion 3 that smoothly connects both of them. The punch 1 provided with the shoulder portion 5 can smoothly perform the transition when the deformation of the peripheral portion of the prepared hole in the workpiece 10 is shifted from the tip portion 2 to the enlarged diameter portion 3.
ただし、肩部５の周面は、軸方向に沿った縦断面において曲率半径Ｒが３０ｍｍ以下の円弧状である。肩部５の曲率半径Ｒが３０ｍｍを超えると、肩部５が実質的に先端部２の延長部として機能するため、被加工部材１０の下穴１１の周縁部１２、すなわち成形されたフランジ１３の先端部分における周方向での肉厚の不均一が顕著になり、割れが発生し易くなるからである。要するに、肩部５の曲率半径Ｒは、フランジ先端部分における周方向での肉厚の均一化の観点からは小さい方が望ましい。このため、肩部５の曲率半径Ｒは、好ましくは１５ｍｍ以下であり、より好ましくは５ｍｍ以下である。 However, the circumferential surface of the shoulder portion 5 has an arc shape with a curvature radius R of 30 mm or less in a longitudinal section along the axial direction. When the radius of curvature R of the shoulder 5 exceeds 30 mm, the shoulder 5 substantially functions as an extension of the tip 2, so that the peripheral edge 12 of the pilot hole 11 of the workpiece 10, that is, the molded flange 13 This is because unevenness in the thickness in the circumferential direction at the front end portion of the steel becomes prominent and cracking is likely to occur. In short, it is desirable that the curvature radius R of the shoulder portion 5 is small from the viewpoint of uniform thickness in the circumferential direction at the flange tip portion. For this reason, the radius of curvature R of the shoulder 5 is preferably 15 mm or less, and more preferably 5 mm or less.
図７は、図６に示す本発明のパンチによる被加工部材の下穴周辺部分の変形挙動を表す図である。同図に示す下穴周辺部分の変形挙動は、前記図２の場合と同様の被加工部材（板厚が３．２ｍｍで、下穴直径ｄ0が１０ｍｍの高強度熱延鋼板）に対し、下記の諸寸法を有する図６に示すパンチ１を用いたバーリング加工を想定してＦＥＭ解析を行った結果であり、穴拡げ率が５０％の時点の状態を例示している。
・先端部の開き角φ：１８０°
・先端部の後端直径ｄ1：１０．２ｍｍ
・拡径部の開き角θ：３０°
・肩部の曲率半径Ｒ：２ｍｍ
FIG. 7 is a diagram showing the deformation behavior of the portion around the prepared hole by the punch of the present invention shown in FIG. The deformation behavior of the peripheral portion of the pilot hole shown in the figure is the same as that in the case of FIG. 2 (high-strength hot-rolled steel plate having a plate thickness of 3.2 mm and a pilot hole diameter d 0 of 10 mm). FIG. 6 is a result of FEM analysis assuming a burring process using the punch 1 shown in FIG. 6 having the following dimensions, and illustrates a state when the hole expansion rate is 50%.
・ Opening angle φ at the tip: 180 °
-Rear end diameter d 1 of the front end: 10.2 mm
・ Opening angle θ of the expanded part: 30 °
-Shoulder radius of curvature R: 2 mm
図７に示すように、上記の諸寸法を有する図６に示すパンチを用いた場合は、開き角αが鋭角である従来の円錐パンチを用いた場合（前記図２参照）と比較し、被加工部材の下穴の周縁部に生じる相当塑性ひずみが小さくなり、その結果として、その下穴周縁部での延性の低下が軽減される。 As shown in FIG. 7, when the punch shown in FIG. 6 having the above dimensions is used, compared with the case of using a conventional conical punch having an acute angle α (see FIG. 2), The equivalent plastic strain generated at the peripheral edge of the prepared member is reduced, and as a result, the decrease in ductility at the peripheral edge of the prepared hole is reduced.
本発明のパンチを用いてバーリング加工が施される被加工部材としては、自動車用部品や電化製品用部品などのあらゆる金属製板状部品が該当し、その材質に特に限定はない。また、被加工部材の板厚も特に限定はないが、実用的な板厚は０．７〜６．０ｍｍ程度である。 As a workpiece to be subjected to burring using the punch of the present invention, all metal plate-like parts such as automobile parts and appliance parts are applicable, and the material is not particularly limited. The plate thickness of the workpiece is not particularly limited, but the practical plate thickness is about 0.7 to 6.0 mm.
本発明の効果を確認するため、前記図６に示すパンチ（先端部の開き角φ：１８０°）を用いてバーリング加工試験を実施した。供試用の被加工部材としては、板厚が１．６ｍｍ、２．４ｍｍ、および３．２ｍｍの３水準の７８０ＭＰａ級高強度熱延鋼板を準備し、それぞれに直径ｄ0が１０ｍｍの下穴を予め設けた。また、比較のために、前記図１に示す円錐パンチを用いた。そして、各バーリング加工試験において、伸びフランジの先端部分に割れが発生した時点の穴拡げ率を調査した。 In order to confirm the effect of the present invention, a burring test was performed using the punch shown in FIG. 6 (opening angle φ of the tip portion: 180 °). As a workpiece to be tested, three levels of 780 MPa high strength hot-rolled steel sheets having a thickness of 1.6 mm, 2.4 mm, and 3.2 mm were prepared, and a pilot hole having a diameter d 0 of 10 mm was prepared for each. Provided in advance. For comparison, the conical punch shown in FIG. 1 was used. And in each burring process test, the hole expansion rate when the crack generate | occur | produced in the front-end | tip part of the stretch flange was investigated.
＜実施例１＞
本発明例１のパンチは、前記図６に示す拡径部の開き角θを３０°とし、先端部の後端直径ｄ1を１０．２ｍｍ、肩部の曲率半径Ｒを２ｍｍとした。また、比較例１の円錐パンチは、前記図１に示す開き角αを本発明例１のパンチと同じ３０°とした。試験結果を下記の図８に示す。
<Example 1>
In the punch of Invention Example 1, the opening angle θ of the enlarged diameter portion shown in FIG. 6 was 30 °, the rear end diameter d 1 of the tip portion was 10.2 mm, and the curvature radius R of the shoulder portion was 2 mm. Further, in the conical punch of Comparative Example 1, the opening angle α shown in FIG. The test results are shown in FIG.
図８は、実施例１のバーリング加工試験結果として被加工部材の板厚ごとの穴拡げ率をまとめた図である。同図に示すように、いずれの板厚でも、本発明例１の方が比較例１よりも穴拡げ率が高くなり、とりわけ、板厚が厚い場合は本発明例１の穴拡げ率の上昇度合いが著しくなり、本発明のパンチを用いることによりフランジの成形性が向上することが明らかとなった。 FIG. 8 is a table summarizing the hole expansion rate for each plate thickness of the workpiece as a burring test result of Example 1. As shown in the figure, the hole expansion rate of Invention Example 1 is higher than that of Comparative Example 1 at any plate thickness. In particular, when the plate thickness is thick, the hole expansion rate of Invention Example 1 is increased. The degree became remarkable, and it became clear that the formability of the flange was improved by using the punch of the present invention.
＜実施例２＞
本発明例２のパンチは、前記図６に示す拡径部の開き角θを６０°とし、先端部の後端直径ｄ1、および肩部の曲率半径Ｒを本発明例１と同じにした。また、比較例２の円錐パンチは、前記図１に示す開き角αを本発明例２のパンチと同じ６０°とした。試験結果を下記の図９に示す。
<Example 2>
In the punch of Invention Example 2, the opening angle θ of the enlarged diameter portion shown in FIG. 6 was set to 60 °, and the rear end diameter d 1 of the tip part and the curvature radius R of the shoulder part were the same as those of Invention Example 1. . Further, in the conical punch of Comparative Example 2, the opening angle α shown in FIG. 1 was set to 60 °, the same as that of the punch of Example 2 of the present invention. The test results are shown in FIG. 9 below.
図９は、実施例２のバーリング加工試験結果として被加工部材の板厚ごとの穴拡げ率をまとめた図である。同図に示すように、いずれの板厚でも、僅かではあるが、本発明例２の方が比較例２よりも穴拡げ率が高くなり、本発明のパンチを用いることによりフランジの成形性が向上することが明らかとなった。 FIG. 9 is a table summarizing the hole expansion rate for each plate thickness of the workpiece as a burring test result of Example 2. As shown in the same figure, the hole expansion rate is higher in Example 2 of the present invention than in Comparative Example 2 at any plate thickness, and the formability of the flange is improved by using the punch of the present invention. It became clear that it improved.
本発明は、バーリング加工に有効に利用できる。 The present invention can be effectively used for burring.
１：パンチ、 ２：先端部、 ３：拡径部、 ４：大径部、 ５：肩部、
１０：被加工部材、 １１：下穴、 １２：周縁部、 １３：伸びフランジ、
φ：パンチ先端部の開き角、 θ：パンチ拡径部の開き角、
ｄ0：被加工部材の下穴の直径、 ｄ1：パンチ先端部の後端の直径、
ｄ2：パンチ大径部の直径
1: punch, 2: tip, 3: enlarged diameter, 4: large diameter, 5: shoulder
10: Work piece, 11: Pilot hole, 12: Peripheral part, 13: Stretch flange,
φ: Opening angle of the punch tip, θ: Opening angle of the expanded diameter part of the punch,
d 0 : Diameter of the pilot hole of the workpiece, d 1 : Diameter of the rear end of the punch tip,
d 2 : Diameter of punch large diameter part
Claims (1)
当該バーリング加工方法に用いられるパンチは、
バーリング加工の初期に前記下穴の周縁部に接触する先端部と、
前記伸びフランジの仕上り内径と同じ直径を有する円柱状の大径部と、
前記先端部と前記大径部とを滑らかにつなぎ後端側ほど直径が拡大する円錐台状の拡径部と、を備え、
前記先端部の開き角が９０°以上で、前記拡径部の開き角が６０°以下であり、前記先端部の後端の直径ｄ1が前記下穴の直径ｄ0との関係で下記（１）式の条件を満たし、
前記パンチの前記先端部と前記拡径部との間にこれらの両者を滑らかにつなぐ肩部を備え、この肩部の周面は、軸方向に沿った縦断面において曲率半径が３０ｍｍ以下の円弧状であることを特徴とするバーリング加工方法。
ｄ0＜ｄ1≦１．２×ｄ0 …（１）
A burring method for forming an elongated flange by expanding a pilot hole provided in a plate-shaped workpiece,
The punch used in the burring method is
A tip that contacts the peripheral edge of the pilot hole in the initial stage of burring;
A cylindrical large diameter portion having the same diameter as the finished inner diameter of the stretch flange;
The tip portion and the large-diameter portion are smoothly connected, and a frustoconical diameter-enlarged portion whose diameter increases toward the rear end side,
The opening angle of the tip portion is 90 ° or more, the opening angle of the enlarged-diameter portion is 60 ° or less, and the diameter d 1 of the rear end of the tip portion is as follows in relation to the diameter d 0 of the pilot hole ( 1) satisfies the condition of the formula,
A shoulder portion is provided between the tip portion of the punch and the diameter-expanded portion to smoothly connect both of them, and a circumferential surface of the shoulder portion is a circle having a curvature radius of 30 mm or less in a longitudinal section along the axial direction. A burring method characterized by being arcuate.
d 0 <d 1 ≦ 1.2 × d 0 (1)
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| JP6552468B2 (en) * | 2016-10-13 | 2019-07-31 | 株式会社アーク | Burring tool and burring machine |
| CN107952852A (en) * | 2017-12-08 | 2018-04-24 | 繁昌县速诚智能设备科技有限公司 | A kind of hole flanging mechanism |
| CN107999627A (en) * | 2017-12-08 | 2018-05-08 | 繁昌县速诚智能设备科技有限公司 | A kind of lathe punch |
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| JPS6297719A (en) * | 1985-10-21 | 1987-05-07 | Agency Of Ind Science & Technol | Flange forming method from metallic thick plate |
| JPH0172917U (en) * | 1987-10-29 | 1989-05-17 | ||
| JPH05344A (en) * | 1990-08-23 | 1993-01-08 | Tannami Kogyo Kk | Method and device for manufacturing top plate for metallic drum can |
| JPH0966318A (en) * | 1995-08-30 | 1997-03-11 | Nisshin Steel Co Ltd | Burring of covered metal plate |
| JP2918859B2 (en) * | 1996-12-27 | 1999-07-12 | 日東精工株式会社 | Burring caulking device |
| JP4458541B2 (en) * | 2005-12-16 | 2010-04-28 | ボッシュ株式会社 | Backup ring manufacturing method, backup ring, and fuel injection valve seal structure |
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