Bending mandrel

Details Bending mandrel Bending mandrel

1999-07-14

2001-06-12

Larson, Lowell A. (Department: 3725)

Metal deforming

Tool and/or tool holder

Including flexible or yieldable tool or support

C072S466000

Reexamination Certificate

active

06244092

ABSTRACT:

The present invention relates to a bending device for bending composite tubes, comprising at least two bending mandrels, wherein;
each of said mandrels is arranged to enter one of the channels of the composite tube,
each of said mandrels comprises a main body and a string of elements connected to said main body, and
each of the elements of said string is connected to the preceding element, the main body respectively for pivoting in two mutually perpendicular planes relative to the preceding element, the main body respectively.
BACKGROUND OF THE INVENTION
Such a bending device is known from the Patent Abstract of Japan No. 06170449.
This known bending device is used for bending composite pipes, wherein the presence of the bending mandrels in both channels of the pipe prevents the outer wall of the respective channel for bending from being distorted inward during the bending. The presence of the bending mandrel prevents the outer wall of the channel being subjected to bending from displacing inward.
On the inside the effect is the reverse; the material is buckled so that it tends to displace inward as a result of the excess of material.
These problems are obviated by the use of a bending mandrel, in particular a pivotable bending mandrel.
The bending mandrel known from JP 06110449 comprises cylindrial elements. The axes of the elements extend perpendicular to the bending radius and to the axial direction of the pipe. This implies that only on discrete: points the pipe walls are supported during bending, so that the pipe walls will be buckled.
SUMMARY OF THE INVENTION
The aim of the invention is to avoid this problem.
The aim is reached in that the elements each have a substantial cylindrical shape of which the axis is substantially parallel to the axes of the channel. Additionally the axial length of each of said elements is longer than the maximal distance between adjacent elements when the pivoting angle between adjacent elements is maximal.
The first characterizing feature provides a better support for the pipe walls over longer distances than known from said prior art. It is however noted that this feature is known per se from DE-A-30 00 170. This concerns, however, a bending device fit for bending a singel channel pipe.
The second characterizing feature provides in mutual support of the elements in different channels, so that each of the elements in the outer channel is supported by at least one of the elements in the inner channel, so that distorsion of the inner walls between the channels is avoided.


REFERENCES:
patent: 2825386 (1958-03-01), Fuchs, Jr.
patent: 2962077 (1960-11-01), Condiff
patent: 4378689 (1983-04-01), Molz
patent: 4671096 (1987-06-01), Crosby, Jr.
patent: 3000170 (1981-07-01), None
patent: 2097854 (1982-11-01), None
patent: 6-170449 (1994-06-01), None
patent: 6-234022 (1994-08-01), None
patent: 585898 (1977-12-01), None

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