【０００１】
【発明の属する技術分野】
この出願は、逐次成形方法に関する。逐次成形とは棒状押圧部材を、金属製薄板等へ押し当てながら板材と棒状押圧部材を相対的に移動させることにより、シェル形状等の所定立体形状を成形する公知方法をいう。なお、本願発明においては、成形前の板材平面内における直交２軸方向をＸＹ、これらとそれぞれ直交する軸方向をＺとする。
【０００２】
【従来の技術】
このような逐次成形及び装置はＷＯ９９／３８６２７号等により公知であり、例えば、特開平５−４２３２８号には板材の四辺をシワ押さえにより水平に保持し、下方から凸型状をなす下押圧部材（押圧型）を押し上げて大まかな形状に全体成形し、上方から棒状の上押圧部材を押し当てながら板材をＸＹ方向へ移動させ、かつ押圧部材をＺ方向へ移動することにより所望の立体形状を成形するようになっている。
【０００３】
【発明が解決しようとする課題】
ところで、図２に示すような、リブ形状部１と抜き穴２を有する板状製品を選るには、図３に示すように、まだ抜き穴が形成されていない被加工板材３の一面側から押圧型４を押し上げて、その一部に形成されている突部５にて略製品形状を成形し、反対面側から棒状押圧部材６にて逐次成形して精密形状にし、その後成形部をブランクして抜き穴を形成することが考えられる。
【０００４】
しかし、このようにすると、成形部のうち突部５の先端に押し上げられる頂部７は最も残留応力が溜まり易い部分であって変形を生じ易い。また頂部７周囲で斜面部８との境界部９付近は成形時の材料が流れにくくなり、流入不足となりがちな斜面部８ではワレが発生し易くなる。さらに他の流入過剰な場所では材料余りによるシワが発生し易い。したがって、逐次成形方法における成形形状や精度に限界が生じていたので、この限界を突破することが求められていた。そこで本願発明は、このような要請の実現を目的とする。
【０００５】
【課題を解決するための手段】
上記課題を解決するため本願発明は、周囲を固定された被加工板材を棒状押圧部材による逐次成形により、リブ形状と抜き穴を有する製品を成形する方法において、予め抜き穴部分をブランクした被加工板材をセットし、その一面側から押圧型を押しつけて、予めその一部に形成されているリブ用突起の先端部で前記抜き穴部分を押すとともに、反対側から棒状押圧部材により逐次成形して抜き穴付きリブを形成することを特徴とする。
【０００６】
【発明の効果】
本願発明によれば、予め抜き穴が形成された被加工板材に対して押圧型の突部を押し当てて全体成形し、その後棒状押圧部材にて逐次成形するので、逐次成形時に被加工板材へ張力がかかると、抜き穴において拡大変形することにより容易に伸び、同時に不要な内部応力を解放できる。したがって突部先端の接触する部分における残留歪みが減少し、成形後の変形が減少するとともに、材料の流れがよくなるため、これまで流入量が不足しがちであった部分における流入が増大し、流入不足によるワレの発生を解消する。
【０００７】
このため、逐次成形における限界を突破して形状の自由度を高めることができるとともに、精度の向上も可能になる。
【０００８】
【発明の実施の形態】
以下、図面に基づいて一実施例を説明する。図１は逐次成形工程の概略図であり、図３と対応する。なお図２の製品は本実施例によって得られるものでもあって前記説明と共通する。また図３とは部分的に異なるだけであるから、共通符号を用い、重複部分の説明を省略する。
【０００９】
まず、図２において、この成形品は、自動車のボンネットに用いられる補強用の板金部材であって、全体が中央側を突出させた立体形状に成形されるリブ部材をなすフードスチフナーであり、略碁盤の目状にリブ形状部１と、これに囲まれた複数の抜き穴２が形成されている。抜き穴２は不要部分の肉抜きをするため任意数、設けられている。
【００１０】
図１は逐次成形工程を示し、被加工板材３の周囲を支持枠１０上に置いてクランプ１１で固定し、被加工板材３の下方に下押圧部材として押圧型４を配置してエアシリンダ等に連結された昇降軸１２により昇降自在とし、上昇時に被加工板材３を全体成形するようになっている。被加工板材３の上方には、上押圧部材である棒状押圧部材６を昇降自在に配置してあり、下降時に逐次成形による局部成形を行うようになっている。
【００１１】
棒状押圧部材６と押圧型４は、いずれか一方又は双方が同一平面内の直交２方向Ｘ・Ｙへ移動自在であり、かつ棒状押圧部材６及び押圧型４はこれらＸＹと直交するＺ方向へ移動（図示状態では昇降）自在である。これらの移動機構の詳細は省略するが、前記従来技術等により種々公知である。
【００１２】
なお、以下の説明では、押圧型４側が被加工板材３及び支持枠１０やクランプ１１と共にＸＹ方向へ自由に移動するとともに、押圧型４のみが被加工板材３及び支持枠１０やクランプ１１に対してＺ方向へ昇降自在になっているものとする。また、棒状押圧部材６はこれらとは独立して被加工板材３の上方空間にて適当な支持部材によりＺ方向へ昇降自在に支持されているものとする。
【００１３】
さらに、棒状押圧部材６と押圧型４のいずれか一方又は双方は、被加工板材３を塑性変形させるに足るだけの押圧力を与えられるようになっている。以下の説明では、この押圧力を押圧型４側から与えられ、棒状押圧部材６はこの押圧力を十分に受け止めるように被加工板材３の上方で支持される構造とする。
【００１４】
被加工板材３は、鉄系又はその他の金属等からなる板状材料であり、例えば、０．数ｍｍ〜数ｍｍ程度の板厚を有する鉄製薄板である。但し、被加工板材３の材料はアルミなどの軽合金その他の金属等、塑性加工に適したものであれば任意に選択でき、その板厚も同様である。また、その表面には予め抜き穴２が形成されている。この抜き穴２は板材のうちにブランクされ、その寸法は製品時よりも若干小さめになっている。
【００１５】
支持枠１０は矩形状等の適宜枠形状をなし、その内側空間内に押圧型４が配置される。支持枠１０はクランプ１１とともに、押圧型４と共通の支持台（図示省略）に支持され、この支持台はＸＹ方向へ自由に移動自在である。押圧型４のみはこの支持台上で支持枠１０やクランプ１１と別にＺ方向へ昇降軸１２により昇降自在であり、押圧型４を押し上げると、被加工板材３の下面へ当接する。
【００１６】
押圧型４は全体が略台形状をなすように図の上方へ膨出する突部５を備える。突部５は、金型側頂部１３、金型側斜面部１４及びこれらの間に位置するアール状の金型側境界部１５を備える。金型側頂部１３は必ず抜き穴２のいくつかと対応する位置に設定される。さらに下部には金型側裾部１６を備え、この金型側裾部１６は押圧型４の基部へアール状に連続している。
【００１７】
まず、押圧型４を押し上げると、被加工板材３全体が突部５によって略同輪郭形状に全体成形される。次に、棒状押圧部材６を押し下げて、先端（図示下端、以下同）を例えば、境界部９近傍にて被加工板材３の上面へ当接させながら、押圧型４を押し上げて、棒状押圧部材６の先端が被加工板材３の接触部分を下方へ変形させて被加工板材３へ侵入するように、ＸＹＺ方向の各位置を調整する。
【００１８】
この状態で被加工板材３を押圧型４と共に横（ＸＹ）方向へ移動させ、棒状押圧部材６の先端が、例えば閉じた等高線を描くように相対移動させる。その後、棒状押圧部材６を略その太さ分程度ずれるように横へ相対移動し、かつ押圧型４をＺ方向へ移動させて高さを調節してから再び隣接して等高線を描くように被加工板材３をＸＹ方向へ移動させる。これにより、被加工板材３を突部５の表面に沿って塑性変形させる。これを繰り返せば、逐次成形による局部成形によって突部５の輪郭に倣った所定形状に成形できる。
【００１９】
このとき被加工板材３は、抜き穴２が金型側頂部１３上に位置するので、逐次成形に伴う張力がかかると、抜き穴２において拡大変形することにより容易に伸び、同時に内部応力を解放できる。したがって頂部７における残留歪みが減少し、成形後の変形が減少するとともに、境界部９の流れがよくなるため、斜面部８における流入が増大し、流入不足によるワレの発生を解消する。
【００２０】
このため、逐次成形における限界を突破して形状の自由度を高めることができるとともに、精度の向上も可能になる。
【００２１】
なお、本願発明は上記の各実施例に限定されるものではなく、発明の原理内において種々に変形や応用が可能である。例えば、押圧型は雌型であってもよい。また本願発明の方法による成形製品は、自動車用外板などの板金部材を初めとする、板状部材を成形した各種用途に適用可能である。
【図面の簡単な説明】
【図１】実施例に係る逐次成形方法の概略断面図
【図２】製品の外嵌図
【図３】従来例の図１に対応する図
【符号の説明】１：リブ形状部、２：抜き穴、３：被加工板材、４：押圧型、５：突部、６：棒状押圧部材、７：頂部、８：斜面部、９：境界部[0001]
TECHNICAL FIELD OF THE INVENTION
This application relates to a sequential molding method. The sequential forming refers to a known method of forming a predetermined three-dimensional shape such as a shell shape by relatively moving the plate material and the rod-shaped pressing member while pressing the rod-shaped pressing member against a thin metal plate or the like. In the present invention, two orthogonal axes in the plane of the plate material before forming are XY, and the axes perpendicular to these two directions are Z.
[0002]
[Prior art]
Such a sequential molding and apparatus are known from WO99 / 38627 and the like. For example, Japanese Unexamined Patent Publication No. 5-42328 discloses a lower pressing member which holds four sides of a plate horizontally by wrinkle holding and forms a convex shape from below. (Pressing die) is pushed up to form a whole in a rough shape, the plate material is moved in the X and Y directions while pressing the rod-shaped upper pressing member from above, and the pressing member is moved in the Z direction to form a desired three-dimensional shape. It is designed to be molded.
[0003]
[Problems to be solved by the invention]
By the way, in order to select a plate-shaped product having a rib-shaped portion 1 and a hole 2 as shown in FIG. 2, as shown in FIG. The pressing die 4 is pushed up from above, a substantially product shape is formed by a protrusion 5 formed on a part of the pressing die 4, and a rod-shaped pressing member 6 is sequentially formed from the opposite surface side to a precise shape. It is conceivable to form a punched hole by blanking.
[0004]
However, in this case, the top portion 7 of the molded portion, which is pushed up to the tip of the protrusion 5, is a portion where residual stress is most likely to accumulate and is likely to be deformed. In addition, the material at the time of molding becomes difficult to flow in the vicinity of the boundary portion 9 with the slope portion 8 around the top portion 7, and cracks easily occur in the slope portion 8 where inflow tends to be insufficient. Furthermore, wrinkles due to excess material are likely to occur in other places where excess inflow occurs. Therefore, there has been a limit in the molding shape and accuracy in the sequential molding method, and it has been required to break through the limit. Then, this invention aims at realization of such a request.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is directed to a method of forming a product having a rib shape and a punched hole by sequentially forming a plate material to be processed whose periphery is fixed by a rod-shaped pressing member. Set the plate material, press the pressing die from one side, press the punched hole portion with the tip of the rib projection formed on a part of it in advance, and sequentially mold with the rod-shaped pressing member from the opposite side A rib with a hole is formed.
[0006]
【The invention's effect】
According to the invention of the present application, since the entire shape is formed by pressing the projection of the pressing die against the plate material on which the punched hole has been formed in advance, and then sequentially formed by the rod-shaped pressing member, the plate material to be processed at the time of the sequential forming is formed. When tension is applied, it is easily expanded by expanding and deforming in the hole, and at the same time, unnecessary internal stress can be released. Therefore, the residual strain in the contact portion of the tip of the protrusion is reduced, the deformation after molding is reduced, and the flow of material is improved. Eliminates cracks caused by shortage.
[0007]
For this reason, it is possible to increase the degree of freedom of the shape by breaking through the limit in the sequential forming, and to improve the accuracy.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment will be described with reference to the drawings. FIG. 1 is a schematic view of the sequential forming step, and corresponds to FIG. The product shown in FIG. 2 is obtained by the present embodiment, and is common to the above description. Also, since it is only partially different from FIG. 3, common symbols are used, and description of overlapping parts is omitted.
[0009]
First, in FIG. 2, this molded product is a hood stiffener that is a reinforcing sheet metal member used for an automobile bonnet, and is a rib member that is entirely formed into a three-dimensional shape with a central side protruding. A rib-shaped portion 1 and a plurality of holes 2 surrounded by the rib-shaped portion 1 are formed in a grid pattern. An arbitrary number of holes 2 are provided to remove unnecessary portions.
[0010]
FIG. 1 shows a sequential forming step, in which the periphery of the plate material 3 to be processed is placed on a support frame 10 and fixed with a clamp 11, and a pressing die 4 as a lower pressing member is arranged below the plate material 3 to be processed by an air cylinder or the like. The plate 3 is formed so as to be able to move up and down freely by an elevating shaft 12 connected thereto. A bar-shaped pressing member 6, which is an upper pressing member, is disposed above and below the workpiece plate 3 so as to be able to move up and down.
[0011]
Either or both of the rod-shaped pressing member 6 and the pressing die 4 are movable in two orthogonal directions XY in the same plane, and the rod-shaped pressing member 6 and the pressing die 4 are moved in the Z direction orthogonal to these XY. It can be moved (elevated and lowered in the illustrated state). Although the details of these moving mechanisms are omitted, various known ones are known from the above-mentioned prior art and the like.
[0012]
In the following description, the pressing die 4 side freely moves in the X and Y directions together with the workpiece 3 and the support frame 10 and the clamp 11, and only the pressing die 4 moves with respect to the workpiece 3 and the support frame 10 and the clamp 11. To be able to move up and down in the Z direction. Further, the rod-shaped pressing member 6 is independently supported by the appropriate supporting member in the space above the plate material 3 to be able to move up and down in the Z direction.
[0013]
Further, one or both of the rod-shaped pressing member 6 and the pressing die 4 can apply a pressing force sufficient to plastically deform the plate material 3 to be processed. In the following description, the pressing force is applied from the pressing die 4 side, and the rod-shaped pressing member 6 is configured to be supported above the workpiece 3 so as to sufficiently receive the pressing force.
[0014]
The plate material 3 to be processed is a plate-like material made of an iron-based material or another metal. It is an iron thin plate having a thickness of about several mm to several mm. However, the material of the plate material 3 to be processed can be arbitrarily selected as long as it is suitable for plastic working, such as a light alloy such as aluminum or another metal, and the plate thickness is the same. In addition, a punched hole 2 is formed on the surface in advance. The hole 2 is blanked out of the plate material, and its size is slightly smaller than that of the product.
[0015]
The support frame 10 has an appropriate frame shape such as a rectangular shape, and the pressing die 4 is disposed in an inner space thereof. The support frame 10 is supported together with the clamp 11 on a support base (not shown) common to the pressing die 4, and this support base is freely movable in the XY directions. Only the pressing die 4 can be moved up and down in the Z-direction by the raising and lowering shaft 12 separately from the support frame 10 and the clamp 11 on this support base. When the pressing die 4 is pushed up, it comes into contact with the lower surface of the plate material 3 to be processed.
[0016]
The pressing die 4 includes a protrusion 5 bulging upward in the drawing so as to form a substantially trapezoidal shape as a whole. The protrusion 5 includes a mold-side top 13, a mold-side slope 14, and an R-shaped mold-side boundary 15 located therebetween. The mold side top 13 is always set at a position corresponding to some of the holes 2. Further, a lower portion 16 of the mold is provided at the lower portion, and the lower portion 16 of the mold is continuous with the base of the pressing die 4 in an R-shape.
[0017]
First, when the pressing die 4 is pushed up, the entire plate material 3 to be processed is entirely formed into substantially the same contour shape by the projection 5. Next, the rod-shaped pressing member 6 is pushed down while the tip (lower end in the figure, hereinafter the same) abuts on the upper surface of the plate material 3 to be processed, for example, near the boundary portion 9. The positions in the XYZ directions are adjusted so that the tip of the workpiece 6 deforms the contact portion of the workpiece 3 downward and enters the workpiece 3.
[0018]
In this state, the plate 3 to be processed is moved in the horizontal (XY) direction together with the pressing die 4, and the tip of the rod-shaped pressing member 6 is relatively moved so as to draw, for example, a closed contour. Thereafter, the rod-shaped pressing member 6 is relatively moved sideways so as to be displaced approximately by the thickness thereof, and the pressing die 4 is moved in the Z direction to adjust the height. The work plate 3 is moved in the XY directions. As a result, the workpiece 3 is plastically deformed along the surface of the projection 5. By repeating this, it is possible to form a predetermined shape following the contour of the protrusion 5 by local forming by sequential forming.
[0019]
At this time, since the punched hole 2 is located on the mold side top 13, the workpiece 3 is easily expanded by expanding and deforming in the punched hole 2, and at the same time, the internal stress is released. it can. Therefore, the residual strain at the top 7 is reduced, the deformation after molding is reduced, and the flow at the boundary 9 is improved, so that the inflow at the slope 8 is increased and the occurrence of cracks due to insufficient inflow is eliminated.
[0020]
For this reason, it is possible to increase the degree of freedom of the shape by breaking through the limit in the sequential forming, and to improve the accuracy.
[0021]
It should be noted that the present invention is not limited to the above embodiments, and various modifications and applications are possible within the principle of the invention. For example, the pressing mold may be a female mold. Further, the molded product according to the method of the present invention is applicable to various uses in which a plate-like member is molded, such as a sheet-metal member such as an automobile outer plate.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a sequential molding method according to an embodiment. FIG. 2 is an external fitting view of a product. FIG. 3 is a view corresponding to FIG. 1 of a conventional example. Drilled hole 3: Plate material to be processed 4: Pressing type 5: Protrusion, 6: Bar-shaped pressing member, 7: Top portion, 8: Slope portion, 9: Boundary portion