Metal working – Method of mechanical manufacture – Heat exchanger or boiler making
Reexamination Certificate
1999-04-30
2001-07-17
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Heat exchanger or boiler making
C029S890052, C228S164000, C228S173100, C228S173200, C228S173400, C228S174000
Reexamination Certificate
active
06260271
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a tubular body having integral branch tubes and is made of a single sheet metal solely by a deformation process and a method for producing the same to be used for forming, for instance, a distribution tank having an inlet and an outlet for a conductive medium flowing therethrough.
A distribution tank D for a car air conditioner produced according to the conventional method is shown in
FIGS. 24-27
.
FIG. 24
is a front view,
FIG. 25
is a bottom view and
FIG. 26
is a rear view, respectively, of the distribution tank D. The main body
50
of the distribution tank D made of light metal is produced by an extrusion process. The main body
50
is formed with two main tubes
51
and
52
connected parallel with each other for flowing the cooling medium therethrough as shown by the
FIGS. 25 and 26
.
An inlet joint
53
for introducing the cooling medium in the tank D is connected to the left end of the main tube
51
, and an outlet joint
54
for flowing out the cooling medium is connected to the right end of the main tube
52
. Each end of the main tubes is blocked by stopcocks
55
. In order that the cooling medium meanders across these two main tubes, dividing members
56
prepared by a separate process are provided at a plurality of positions to divide the space in both of the main tubes into a plurality of compartments.
A number of protruding branch tubes
57
are provided on the outer surfaces of the two main tubes
51
and
52
at intervals of a predetermined distance. The branch tubes
57
are provided for connecting thereto the ends of a number of the meandering tubes (not shown) for heat exchange.
The conventional method of producing the branch tubes
57
is explained with reference to FIG.
27
. First, the main body
50
is extruded to form a shape the sectional view of which is shown in FIG.
27
(
a
). Small square pillar bodies
50
a
are provided on the upper surfaces of the two main tubes
51
and
52
throughout the whole length of the two main tubes.
Next, the small square pillar bodies
50
a
are cut such that the small circular pillars
50
b
are left in the longitudinal direction of the main tubes at intervals of a predetermined distance. Then, small penetrating holes are created at the axis of each small circular pillar.
Thereafter, branch tubes
57
having desired inside diameter and length are created by forging in which a deformation process is applied to each small circular pillar
50
b.
Since this forging process cannot be conducted to many small circular pillars simultaneously, it needs to be separately conducted by small numbers in a plurality of times. In addition, within the category of the deformation process, the productivity of such a forging process is inferior to that of a press working process.
Since the production of the distribution tank D in the conventional method involves inefficient operations, such as cutting the small circular pillars
50
b
and conducting discontinuous forging processes several times, the production cost of the distribution tank D inevitably becomes high.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a tubular body having integral branch tubes, such as a distribution tank of an automobile air conditioner, which is made of a single sheet metal and produced almost solely by a deformation process based on a press working technology.
It is another object of the present invention to provide a tubular body having a large number of integrally formed branches tubes to be used as a cooling medium distribution tank with low cost and high productivity.
It is a further object of the present invention to provide a production method for producing, with high efficiency and low cost, a tubular body having a large number of integrally formed branches tubes solely by a deformation process.
In order to achieve the above objects, the tubular body of the present invention comprises: a main tubular body formed by deforming a single sheet metal; and branch tubes integrally provided on the main tubular body wherein the branch tubes are created on the outer surfaces of the main tubular body by deforming a part of the sheet metal.
One example of the tubular body is a distribution tank of a heat exchanger of automobiles wherein an inlet and an outlet for heat conductive medium and dividers for distribution of such medium are provided. The main tubular body of the distribution tank is comprised of two main tubes connected parallel to each other. The main tubular body is squeezed at a plurality of positions to create dividers therein.
The production method of the present invention for producing a tubular body having integral branch tubes from a single sheet metal solely by a deformation process is comprised of:
a swelling step for creating a cylindrically swelled portion having a predetermined length and thickness at a predetermined position of the sheet metal through a plurality of processing stages, the top end of which being closed;
a boring step for boring the top end of the swelled portion;
a channel creating step for creating a mating channel extending throughout the whole length of the sheet metal at an optional position in the transversal direction of the sheet metal;
a rounding step for rounding the sheet metal in the transversal direction to form a tubular body having a desired sectional shape; and
a mating step for mating the end of the rounded sheet metal with the mating channel.
In order to divide the cavity of the tubular body into a plurality of compartments in the longitudinal direction, it is desirable to have a divider creating step for creating dividers at a plurality of predetermined positions by squeezing the tubular body.
Further, in order to increase the thickness of the portion where the mating channel is created, it is desirable to have a thickness increasing step by pressing the sheet metal toward an inner direction thereof.
Further, it is desirable to have a brazing step for sealing the gaps at the mating positions and dividing positions with melted wax.
According to the present invention, a tubular body having integral branch tubes with a complicated structure such as a distribution tank constituting a heat exchanger of a car air conditioner can be efficiently mass produced.
According to the present invention, the tubular body having integral branch tubes can be completed by press working with high productivity without using a forging process which cannot be continuously conducted in a single production process.
According to the present invention, since it does not require any large scale extruding molds or inefficient cutting processes, production cost can be substantially decreased than that of the conventional production method.
According to the present invention, the cross sectional view of the tubular body is not limited to circle but can be various shapes in cross section such as square, triangle, ellipse or other indefinite shapes.
According to the present invention, the space in the tubular body can be easily divided into a plurality of compartments by squeezing the tubes in the course of the continuous deformation process without requiring the step of inserting the dividing members separately prepared.
According to the present invention as applied to a process of producing automobile air conditioners, the existing facilities can be utilized almost as they are for a brazing process.
According to the present invention as applied to a process of producing distribution tanks of automobile air conditioners, the production cost can be reduced almost by half.
According to the present invention, a tubular body of different shape can be easily formed such as a one having a plurality of tubes bundled together.
REFERENCES:
patent: 2785542 (1957-03-01), Thomas
patent: 4663812 (1987-05-01), Clausen
patent: 4749033 (1988-06-01), Clausen
patent: 4770240 (1988-09-01), Dawson et al.
patent: 5190101 (1993-03-01), Jalilevand et al.
patent: 5337477 (1994-08-01), Waggoner
patent: 5419174 (1995-05-01), Waggoner
patent: 5642640 (1997-
Hughes S. Thomas
Muramatsu & Associates
Omgba Essama
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