Metal deforming – By deflecting successively-presented portions of work during... – By use of deflectors arranged to bend work longitudinally of...
Reexamination Certificate
2000-03-07
2001-07-03
Crane, Daniel C. (Department: 3725)
Metal deforming
By deflecting successively-presented portions of work during...
By use of deflectors arranged to bend work longitudinally of...
C072S168000, C072S173000, C072S307000
Reexamination Certificate
active
06253591
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for bending a metallic flanged member such as an aluminum alloy flanged hollow extruded material.
2. Description of the Related Art
When trying to bend a channel steel in such a manner that a flange thereof is situated on an inner side of a bending process, the flange buckles and then deforms in a wavy fashion. This causes such drawbacks as the channel steel looks poor, it becomes difficult to bring a member into tight contact with the flange so deforming, and the bending rigidity is largely reduced. Conventionally, in order to cope with these drawbacks, there is made a V-shaped cut in the flange from the edge thereof, and after the channel steel is bent, the V-cut edges are welded together directly or via a V-shaped piece. However, this increases bending processes and hence reduces the productivity, leading to high production costs. Moreover, it reduces the reliability in terms of strength.
Described as an improvement to the aforesaid conventional method in Japanese Patent Unexamined Publication No. SHO 51-123760 is a channel steel bending method comprising the steps of forming holes in the root portion of the flange, and thereafter bending the channel steel along the surface of the flange in such a manner that the flange is situated on an inner side of a bending process.
According to the bending method described in Japanese Unexamined Patent Publication No. SHO 51-123760, since holes are formed in the root portion of the flange, the bending rigidity along the flanged surface of the channel steel is reduced, and when trying to bend the channel over a long range with a large radius of curvature, man-hours are increased to form holes to make it possible to thereby lower the productivity. Moreover, reduction in bending rigidity of the channel steel is inevitable.
SUMMARY OF THE INVENTION
The present invention relates to an improved method and apparatus for bending a metallic flanged member that can solve the above problem.
According to a first aspect of the invention, there is provided a method for bending a metallic flanged member comprising the steps of applying a compressive force to a flange of a metallic flanged member in a direction that intersects a longitudinal direction of the metallic member for compression plastic deformation of the flange, and thereafter bending the metallic flanged member along a flanged side thereof in such a manner that the flanged side of the metallic flanged member is situated on an inner side of a bending process.
Accordingly, a tensile force is imparted to the flange in the longitudinal direction of the metallic member to thereby cause therein a large tensile strain, and there is caused in the flange a tensile plastic deformation in the longitudinal direction of the metallic member.
Due to this, following this, when trying to the metallic flanged member along the flanged side in such a manner that the flanged side is situated on the inner side of a bending process, there is caused a compressive force to be applied to the flange in a direction opposite to the aforesaid tensile plastic deformation, and the flange is then made subject to a low yield compression stress to thereby cause a compression plastic deformation of the flange (normally referred to as Bauschinger effect). As a result of this, the flange is prevented from deforming in a wavy fashion and therefore the metallic flanged member can easily and securely be bent with the flange being kept nearly flat. Consequently, no post process is needed to restore the flatness in the flange and a component such as a weather strip rubber can directly be attached to the flange with high accuracy and efficiency, thereby making it possible to reduce the production costs.
In addition, the compressive force may be directed in a thickness direction of the flange being a direction perpendicular to the flange surface. Accordingly, the flange can easily and securely be subject to a compression strain and thereafter it can easily be bent utilizing the Bauschinger effect.
Further, the amount of the compression plastic deformation may be increased as the bending radius of the metallic flanged member decreases. Thus, a compression plastic deformation can be generated which conforms to the bending deformation amount of the metallic flanged member, whereby the metallic flanged member can be bent rationally efficiently without causing any wavy deformation in the flange in the thickness direction thereof.
According to a second aspect of the invention, there is provided an apparatus for bending a metallic flanged member including: a receiving member slidably supporting the metallic flanged member and abutting against one surface of a flange of the metallic flanged member; a press member integrally fixed to the receiving member, the press member having an abutment surface abutting against the other surface of the flange to thereby form a gap between the abutment surface and an abutment surface of the receiving member abutting against the one surface of the flange, the gap being gradually reduced from one end of the flange to the other end thereof; and a slidably driving unit slidably moving the metallic flanged member from a side where the gap formed between the abutment surface of the receiving member and the abutment surface of the press member is wider toward a side where the gap is narrower.
With thus structure, a series of compression plastic deformation and bending can be carried out simultaneously, whereby bent metallic flanged members with high accuracy and quality can be produced with efficiency at low costs.
REFERENCES:
patent: 1158294 (1915-10-01), Robinson
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patent: 2093933 (1937-09-01), Sinclair
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patent: 3782164 (1974-01-01), Felker
patent: 4266417 (1981-05-01), Imamura
patent: 4624121 (1986-11-01), Kitsukawa
patent: 5119533 (1992-06-01), Shimokata
patent: 5156036 (1992-10-01), Michaels
patent: 5884517 (1999-03-01), Yogo
patent: 51-123760 (1976-10-01), None
patent: 8-257643 (1996-10-01), None
Ihara Shin
Okada Kazuya
Sayama Mitsuru
Yokoyama Toshiyuki
Armstrong Westerman Hattori McLeland & Naughton LLP
Crane Daniel C.
Honda Giken Kogyo Kabushiki Kaisha
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