Metal working – Method of mechanical manufacture – Heat exchanger or boiler making
Reexamination Certificate
1999-07-02
2001-04-03
Rosenbaum, I. Cuda (Department: 3726)
Metal working
Method of mechanical manufacture
Heat exchanger or boiler making
C029S890043
Reexamination Certificate
active
06209201
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat exchanging fin and a method of manufacturing the heat exchanging fin. More precisely, the present invention relates to a heat exchanging fin and a method of manufacutring the heat exchanging fin, in which collars are formed to respectively enclose tube holes, through which heat exchanging tubes will be inserted. Futhermore the collars respectively have flares at their front ends manufactuing the heat exchanging fin.
2. Description of the Related Art
The heat exchanging fin, which is employed in room air conditioners, car air conditioners, etc., includes: a rectangular metallic plate section, which is made of a metal, e.g., aluminum; and a plurality of collared tube holes provided in the metallic plate section with separations and having a prescribed height.
A heat exchanger is assembled by the steps of: piling the heat exchanging fins, in which the collared tube holes are coaxially arranged; inserting heat exchanging tubes, which are made of a metallic material having high heat conductivity, e.g., copper, through the coaxial tube holes; and expanding the heat exchanging tubes, which have been inserted through the tube holes, so as to integrate the heat exchanging tubes with the heat exchanging fins.
The conventional heat exchanging fin is manufactured by the above-mentioned steps by a drawing manner, which is shown in
FIGS. 14A-14F
, or a drawless manner, which is shown in
FIGS. 15A-15D
.
In the drawing manner, shown in
FIGS. 14A-14F
, a shallow projected section
106
, which has a columnar shape or a truncated cone shape, is formed in a thin aluminium plate section
100
(see FIG.
14
A). The diameter of the shallow projected section
106
is greater than that of the collared tube holes to be formed. The diameter of the shallow projected section
106
is then reduced and the height thereof is gradually increased by drawing the shallow projected section
106
(see FIGS.
14
B-
14
D).
A top face of the projected section
109
, which is formed by drawing the shallow projected section
106
until reaching a prescribed height, is opened and burred to make a cylindrical section
104
(see FIG.
14
E). Furthermore, a flare
105
is formed by bending a top end of the cylindrical section
104
(see FIG.
14
F).
In the drawless manner, shown in
FIGS. 15A-15D
, a base hole
101
, which is enclosed by a projected part
102
, is formed by boring and burring the metallic plate section
100
(see FIG.
15
A). The diameter of the base hole
101
is then made greater and the projected part
102
is squeezed until a cylindrical section
104
which has a prescribed height is formed (see FIGS.
15
B and
15
C).
The flare
105
is formed by bending the top end of the cylindrical section
104
(see FIG.
15
D).
The heat exchanging fins having collared tube holes, which include the cylindrical sections
104
and the flares
105
, are formed by the manner shown in
FIGS. 14A-14F
or
FIGS. 15A-15D
. When the heat exchanging fins are piled, the flares
105
of one heat exchanging fin contact a bottom face of the adjacent heat exchanging fin, so that the separation between the heat exchanging fins can be defined.
In the manner shown in
FIGS. 14A-14F
or
FIGS. 15A-15D
, the base hole, which is bored in the top face of the projected section
109
or in the metallic plate section
100
, is a circular hole. Furthermore, in the manner shown in
FIGS. 14A-14F
or
FIGS. 15A-15D
, the width of the flare
105
, which is formed to enclose a circular edge of the top end of the cylindrical section
104
, is fixed.
Heat exchanging fins of today must be made light in weight. Therefore, the thickness of the metallic plate section
100
must be made thinner.
On the other hand, tough heat exchanging fins are also required. Namely, heat exchanging fins, which are not only thin but also tough, are required. Therefore the metallic plate section
100
must be made of a thin and tough metallic material.
Extensibility of the thin and tough metallic material is less than that of a thick and soft metallic material. Therefore, it is improper for the thin and tough metallic material to be pressed to form heat exchanging fins. When the flare
105
is formed by bending the top end of the cylindrical section
104
, the flare
105
is outwardly pulled. When thin and tough material having a small extensibility is used, a crack
106
may be formed in the flare
105
(see
FIG. 16
) because the end of the flare
105
is extremely extended.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a heat exchanging fin capable of preventing cracks from forming in the flares of the collared tube holes, even if the metallic plate section is made of the thin and tough material.
Another object of the present invention is to provide a method of manufacturing said heat exchanging fin.
To achieve the objects, the inventor of the present invention has determined that forming cracks in the flares of the collared tube holes can be prevented by forming three radially extended sections as the flare.
The basic structure of the heat exchanging fin of the present invention comprises:
a metallic plate section having a plurality of tube holes;
a plurality of collars each of which is extended from an edge of each tube hole; and
a plurality of flares each of which is formed at a front end of each collar,
wherein each flare includes a plurality of radially extended sections, which are radially outwardly extended from the front end of each collar, and separation between the metallic plate section and each radially extended section is fixed.
In the heat exchanging fin of the present invention, a shape of an outer edge of each flare may be formed into a polygonal shape. The polygonal shape may be a triangle, a tetragon, etc.
In the heat exchanging fin of the present invention, the radially extended sections of each flare may be provided such that their apexes are located with regular separations in the circumferential direction.
In the heat exchanging fin of the present invention, a shape of an outer edge of each flare may be formed into a regular polygonal shape. The regular polygonal shape may be a regular triangle, a regular tetragon, etc.
In the heat exchanging fin of the present invention, each flare may include a plurality of narrow sections, which are radially outwardly extended from the front end of each collar with a width narrower than that of the radially extended sections.
In the heat exchanging fin of the present invention, the radially extended sections of each flare may be provided with regular separations in the circumferential direction.
The basic structure for performing the method of manufacturing the heat exchanging fin of the present invention includes: a metallic plate section having a plurality of tube holes; a plurality of collars each of which is extended from an edge of each tube hole; a plurality of flares having prescribed height, each flare being formed at a front end of each collar, the method comprising the steps of:
forming a cylindrical section, in which higher sections and lower sections are alternately formed at a front end, along the edge of each tube hole; and
forming the flare of each collar by radially outwardly bending the higher sections of the cylindrical section.
In the method of the present invention, the cylindrical section having the higher sections and the lower sections may be formed by the steps of:
forming a projected section, which is formed into a columnar or a truncated cone shape, in the metallic plate section by drawing the metallic plate section;
boring a base hole, which is formed into an elliptic or a polygonal shape, in the projected section; and
burring the base hole so as to form the cylindrical section, in which at least two higher sections are formed at the front end, along the edge of the tube hole.
In the method, the base hole may be formed into a triangle or a tetragon.
In the method of the present invention, the higher sections may be provided at the front end of the cylindric
Birch & Stewart Kolasch & Birch, LLP
Cuda Rosenbaum I.
Hidaka Seiki Kabushiki Kaisha
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