Metal deforming – By application of fluent medium – or energy field – With actuated tool engaging work
Reexamination Certificate
1999-12-20
2001-03-20
Jones, David (Department: 3725)
Metal deforming
By application of fluent medium, or energy field
With actuated tool engaging work
C072S062000
Reexamination Certificate
active
06202460
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority to French Application No. 98 16053 filed Dec. 18, 1998.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and to a device for producing a y-fitting having a y-branch from a metal tube by hydroforming. In many fields, use is made of tubular metal parts which comprise a main portion to which a y-branch is connected. These parts are commonly used, for example, to form connections or branches in pipes in which a fluid flows.
2. Description of the Related Art
To manufacture this kind of part it is known to use a method called hydroforming which consists in placing a straight, or curved, metal tube in a cavity of a die comprising a branch corresponding to the desired shape of the y-branch that is to be produced and in gradually causing the metal to flow into this y-fitting by applying pressure to the inside of the metal tube.
For this purpose, a fluid is injected at high pressure into the tube and at the same time pistons, which can move in the die, are applied in a sealed manner to each end of the tube so as to exert thrust on these ends and force the metal to flow into the branch of the die. Then, the free end of the y-branch is cut off so as to open the tapping.
The flow of metal into the branch is controlled by a counter-plunger arranged in the branch and moving in translational movement at the same time as the metal gradually forms the y-branch under the effect of the pressure exerted on the inside of the tube. The counter-plunger is connected to an element which exerts resistance to, or a force which opposes, the flow of metal during the displacement of this counter-plunger in the branch so as to allow the metal to flow uniformly.
However, the known devices used for producing a y-fitting from a metal tube have drawbacks. Specifically, the counter-plunger can be moved in translational movement in the branch of the die between a first position located close to the region where the cylindrical portion and the branch meet and a second position away from this region and separated by a distance which corresponds to the length of the y-branch that is to be produced. Depending on the device used, the counter-plunger extends into the branch either at a right angle with respect to the axis of the branch or parallel to the axis of the cylindrical portion of the die cavity.
When the counter-plunger extends at a right angle with respect to the axis of the branch, an empty space remains, when the counter-plunger is in the first position, between the counter-plunger and that portion of the tube facing the branch. This free space prohibits or impedes the control of the metal flow at the start of the deformation of the branch, which creates a risk that the metal bursts.
When the counter-plunger extends parallel to the axis of the cylindrical portion of the die cavity, the y-branch produced by the flow of metal into the branch has an end wall which also extends parallel to the axis of the tube. The free end of the y-branch is cut off in a direction at a right angle with respect to the axis of this y-branch so that part of the y-branch is removed, thus reducing its length.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a hydroforming method and device, for producing a y-fitting from a metal tube, that avoids the aforementioned drawbacks.
In a first embodiment, the present invention provides a hydroforming method for producing an inclined y-branch from a metal tube, in this method the tube is placed in a die comprising a cavity formed of a cylindrical portion configured to take the tube and of a branch corresponding to the desired shape of the y-branch. A fluid is injected at high pressure into the tube and at the same time thrust is exerted on each end of the tube to force the metal to flow into the branch. The frontal surface of the metal in the branch is first restrained along a surface parallel to the axis of the tube and, as the metal flows into the said branch, the frontal surface of the metal is oriented along a surface perpendicular to the axis of the branch.
According to different embodiments of the present invention, the frontal surface of the metal is oriented at a right angle with respect to the axis of the branch either:
while the metal is flowing in the branch, or
as the metal starts to flow into the branch, or
as the metal finishes to flow in the branch.
Another embodiment of the present invention is a device for producing a straight and inclined y-branch from a metal tube by hydroforming, including:
a die comprising a cavity formed of a cylindrical portion, configured to take the tube, and of a branch, opening into the cylindrical portion and of a shape that corresponds to the y-branch,
opposed pistons configured to move inside the die to exert thrust on each end of the tube,
an injection mechanism configured to inject a fluid into the tube at high pressure so as to force the metal to flow into the branch,
a counter-plunger arranged in the branch and in contact with that portion of the tube which is facing the branch, and
a displacement mechanism configured to drive the translational and rotational movement of the counterplunger so as to displace the counter-plunger between a first position parallel to the axis of the tube as the metal starts to flow into the branch, and a second position at a right angle with respect to the axis of the branch while the metal is flowing in the branch.
According to another embodiment of the present invention, the displacement mechanism includes a ram which can be rotated through 180° and which comprises a piston rod connected to the counter-plunger by a crank.
In another embodiment, the axis of the piston rod of the ram forms, with the vertical, an angle equal to half the angle of inclination of the tapping.
According to another embodiment, the axis of the piston rod of the ram passes through a point located on the axis of the y-branch and at the mid-point of the distance separating 1) the center of the area of contact between the counter-plunger and the tube portion before the metal flows and 2) the center of the area of contact between the counter-plunger and the frontal surface of the metal after this metal has flowed into the branch.
According to another embodiment, the projection, onto the axis of the tube, of the distance between the point of intersection of the axis of the piston rod and the axis of the y-branch, and the center of the area of contact between the counter-plunger and the tube portion before the metal flows, is equal to the projection, onto the axis of the tube, of the distance between this point of intersection and the center of the area of contact between the counter-plunger and the frontal surface of the metal after this metal has flowed into the branch.
REFERENCES:
patent: 2238037 (1941-04-01), Cornell, Jr.
patent: 3216092 (1965-11-01), Arbogast
patent: 3681960 (1972-08-01), Tadokoro
patent: 4051704 (1977-10-01), Kimura
patent: 5765420 (1998-06-01), Schaefer
patent: 6029487 (2000-02-01), Genin et al.
patent: 0 497 438 (1992-08-01), None
patent: 0 633 075 (1995-01-01), None
patent: 2 535 987 (1984-05-01), None
Jones David
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tubes Et Formes
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