Metal working – Method of mechanical manufacture – Assembling or joining
Reexamination Certificate
2001-02-02
2004-06-08
Olms, Douglas (Department: 2661)
Metal working
Method of mechanical manufacture
Assembling or joining
C072S051000
Reexamination Certificate
active
06745448
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a pipe body having pair of edge sections which form closed end surface by means of contact with each other, wherein parts surrounding each edge section form a plane jointly in a state where each edge section is in contact with each other and a forming method of the pipe body.
BACKGROUND OF THE INVENTION
Conventionally, a technique forming a pipe body, for example, a prism pipe body by means of a bending process of a metal plate is disclosed in Japanese Patent Laid-Open No. Hei 11-290940.
According to the description disclosed in the gazette, a prism pipe body is formed of a metal plate of a rectangular shape by means of a press processing consisting of a plurality of processes.
That is, the processing method of the prism pipe body comprises a first bending step of bending end parts of width direction of the metal plate along a length direction at the right angle to form a first processed piece having a bottom part connecting the opposite flange parts to each other, a second bending step of forming a recessed curve surface of a predetermined width along the length direction at the bottom part of the first processed piece, and at the same time, bending both ends of the recessed curve surface toward the inside at the almost right angle to form a second processed piece of a U shape having a pair of sidewall parts facing each other, and a re-striking step of pressing the pair of sidewall parts of the second processed piece toward each other to make the end surfaces of a pair of flange parts contact with each other.
According to the processing method of the prism pipe body, the recessed curve surface formed at the bottom part of the second processed piece plays a role of suppressing spring back force generated by pressing the pair of sidewall parts toward each other in forming the second processed piece, and therefore, the prism pipe body of which a cross-section is a square shape and in which both end surfaces of the flange parts are closed to each other can be manufactured by means of only the press forming, without welding both end surfaces of the flange parts.
However, in the conventional processing method of the prism pipe body, even if the recessed curve surface formed at the bottom part of the second processed piece plays a role of suppressing back force generated by pressing the pair of sidewall parts toward each other in forming the second processed piece, the spring back force which serves to unfold the pair of sidewall parts remains in the pair of sidewall parts, and thus, it was difficult to manufacture the prism pipe body in which both end surfaces of the flange parts are closed to each other, stably without deviation in mass-producing.
That is, when inspecting whether both end surfaces of the flange parts in the prism pipe body manufactured by the processing method are closed to each other, there are pipe bodies in which both end surfaces of the flange parts are closed to each other, while there are pipe bodies in which a gap is generated between both end surfaces of the flange parts by the spring back force. Also, the gaps are not constant.
SUMMARY OF THE INVENTION
The present invention is made in order to solve the aforementioned problems.
An object of the present invention is to provide a pipe body in which both edge sections to be in close contact with each other are closed stably to each other by means of only a press forming without welding in mass-producing, a metal plate for the pipe body and forming method of the pipe body using the sheet metal for the pipe body.
In order to accomplish the above object, according to an aspect of the present invention, a method of forming a metal pipe by way of bending a flat metal plate, the method is carried out in steps of: forming male section on a first end of said metal plate and female section on a second end parallel to said first end, respectively; bending said metal plate so that said male section and said female section can be engaged with each other, and coupling said male section and said female section to be engaged with each other, is provided.
According to another aspect of the present invention, a method of forming a metal pipe by way of bending a flat metal plate, the method being carried out in steps of: previously forming male section on a first end of said metal plate and female section on a second end parallel to said first end, respectively; preliminarily bending said metal plate along an axis of said metal pipe which is a final forming body, at a position distant by an approximately half length of a predetermined side from both end of said metal plate to form a predetermined angle with said metal pipe; further bending said metal plate at predetermined positions to form predetermined angles with said preliminary bent position; and coupling said male section and said female section to be engaged with each other so as to form a plane, is provided.
According to another aspect of the present invention, a method of forming a metal pipe, wherein said both end surfaces are preliminary bent, sides of a plane opposite to a plane formed by way of close contact of said ends are bent more over said predetermined angle, and in this state, both ends of said opposite plane are further bent to form predetermined angles to be coupled, is provided.
According to another aspect of the present invention, a method of forming a metal pipe, wherein said plane opposite to said closely contacting plane is bent to be a concave plans toward a center of axis of said final metal pipe, is provided.
According to another aspect of the present invention, a method of forming a metal pipe having a desired angle by way of bending a flat metal plate, the method being carried out in steps of, previously forming male section at a first end of said metal plate and female section at a second end parallel to said it end, respectively; sequentially bending said metal plate in a desired angle at positions along sides of the final metal pipe from one of said both ends; and coupling said male section and said female section at said both ends to be engaged with each other, is provided.
In the methods of forming a metal pipe according to the above aspects of the present invention, both edge sections can be in close contact with each other stably with only a press forming without welding in mass-producing, by means of separation-prevented engagement due to deformation of at least one of said female engagement section and said male engagement section.
According to another aspect of the present invention, a pipe body having pair of edge sections that form closed end surface by way contact with each other, in which surroundings of said edge sections form a plane jointly when said edge sections are in contact with each other, wherein male engagement section and female engagement section engaged with each other are formed at said edge sections, respectively, and at the same time, said edge sections get in close contact with each other by means of separation-prevented engagement due to deformation of at least one of said female engagement section and said male engagement section.
In a pipe body according to the above aspect of the present invention, both edge sections can be in close contact with each other stably with only a press forming without welding in mass-producing, for separation-prevented engagement due to deformation of at least one of said female engagement section and said male engagement section absorbs the spring back in press forming.
According to another aspect of the present invention, a pipe body formed with closed end surface by mean of joint consisting of end surface of one edge section and a back surface of the other edge section in planes crossing each other, wherein male engagement section projected from said end surface of said one edge section engages with female engagement section formed at said other edge section, and at the same time, said edge sections get in close contact with each other in a state that separation of said male engagement section from said female engagement section
Ishino Keiji
Kondou Takafumi
Blount Steven
Cooper & Dunham LLP
Olms Douglas
Ricoh & Company, Ltd.
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