Metal fusion bonding – With control means responsive to sensed condition
Reexamination Certificate
2001-07-18
2004-02-17
Dunn, Tom (Department: 1725)
Metal fusion bonding
With control means responsive to sensed condition
C228S009000, C228S056500
Reexamination Certificate
active
06691908
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a brazing apparatus, and particularly to a brazing apparatus capable of controlling temperature factors which influence the quality of brazing.
2. Description of the Background Art
FIG. 8
is a side view schematically showing a heating and brazing filler metal supply station in a conventional automatic brazing apparatus and
FIG. 9
is a plan view of the automatic brazing apparatus shown in FIG.
8
. Referring to these diagrams, the automatic brazing apparatus comprises a brazing jig unit A for clamping and accurately positioning articles to be joined together, a preheating burner unit B, a heating and brazing filler metal supply unit C, and a brazing filler metal wire and combustion gas supply unit D.
In the brazing jig unit A, a driving motor
38
and an index gear
37
are fixed under a brazing apparatus fixing table
51
; the driving motor
38
is for intermittently driving an index table
36
and the index gear
37
is connected to the driving shaft of the driving motor
38
to accurately position the index table
36
. An air pipe
73
for supplying compressed air to a driving source for driving the jig clamp etc. is vertically fixed in the center of the index table
36
provided on the jig table. The air pipe
73
is rotatably connected to the index table
36
through seal rings
35
, with O-ring seals fitted around the air pipe
73
.
A jig
75
for coaxially clamping articles
71
and
72
to be joined together is disposed on the index table
36
. The preheating burner unit B includes a preheating burner
39
which can move forward and backward toward and away from the center of the index table
36
. In the heating and brazing filler metal supply unit C, a driving cylinder
48
, fixed on the brazing apparatus fixing table
51
, and a brazing unit frame
47
are coupled together, and the brazing unit frame
47
is disposed on a pair of guide rails
76
so that it can move forward and backward toward and away from the center of the index table
36
.
A forked gas nozzle
43
having two prongs as a burner
42
, is connected to a gas pipe
77
and attached to the moving frame
50
to protrude toward the index table
36
. Plural pairs of heating torches
69
are attached to the prongs of the gas nozzle
43
, each pair of heating torches
69
facing toward each other. Nozzle driving cylinders
45
are attached to a mount fitting
59
on the brazing unit frame
47
in such a manner that they can be adjusted for angle. Brazing filler metal supply nozzles
44
are attached to the nozzle driving cylinders
45
, with their tips aimed at the central point of the pieces heated by the heating torches
69
.
In the brazing filler metal and combustion gas supply unit D, the nozzle driving cylinders (brazing filler metal wire cylinders)
45
are driven to move the brazing filler metal supply nozzles
44
toward the brazed portion of the articles
71
and
72
to be joined. Then given amounts of brazing filler metal wires are fed by a wire supply motor
52
from brazing filler metal wire reels
58
a
and
58
b
. A mixture of combustible gas and burning-supporting gas (oxygen) mixed in a given ratio is supplied as the combustion gas.
Next, the brazing operation is briefly described referring to
FIGS. 8 and 9
.
First, the articles
71
and
72
to be brazed together are introduced and held by the jig
75
, and then the index table
36
rotates 90°, clockwise in
FIG. 9
, to bring them to the stage of the preheating burner unit B. Then the preheating burner
39
moves forward to locate its prongs around the articles
71
and
72
and the preheating burner
39
preheats them. After preheating, the preheating burner
39
moves backward, and the index table
36
further rotates 90° clockwise to bring the preheated articles
71
and
72
to the stage of the heating and brazing filler metal supply unit C. Then the gas nozzle
43
is moved forward in given timing and starts heating the joined portion of the articles
71
and
72
with “high” flames.
The brazing filler metal supply nozzles
44
start moving forward somewhat after the gas nozzle
43
has began heating. Further later, the brazing filler metal wires
46
are supplied from the brazing filler metal supply nozzles
44
in given timing to the joined portion of the articles
71
and
72
and then brazing is performed. The gas nozzle
43
heats the joined portion for a given time period, and then the flames are changed from “high” to “low,” and the burner
42
retreats when the low flame period ends. The brazing operation thus ends. The brazing filler metal supply nozzles
44
are withdrawn around when the flames of the gas nozzle
43
are changed from “high” to “low.”
After brazing, the index table
36
further rotates 90° and the joined articles
71
and
72
are taken out as a brazed product. As explained so far, a set of articles to be brazed together are introduced each time the index table
36
rotates 90° and are brazed through the preheating, brazing, and exit stages. In practice, a plurality of sets of articles to be brazed are sequentially introduced each time the index table
36
rotates 90° and are brazed in parallel through the stages.
The conventional brazing apparatus shown above encounters no particular problem when the temperature of the articles introduced to be brazed and the temperature in the atmosphere stay constant. However, inferior brazing may be caused when such temperatures vary at changes of the season, or vary when the operation is started at the beginning of the working hours, during the operation, or when the operation is restarted after interruption. That is to say, when the articles to be brazed are heated with a constant amount of heating in the preheating and heating processes, variations of such conditions cause the articles to attain varied temperatures during brazing, which would result in unstable brazing quality.
Even if the amount of preheating and the amount of heating can be varied to control the heating depending on the articles to be brazed, it is still difficult to keep the temperature rise of the articles constant since accurate information for controlling the amounts of heating is not available.
Further, even if a system for controlling the amounts of heating has been experientially established about one combination of articles to be brazed together (one combination of articles of certain shapes and certain materials), a different combination of articles will be heated to a different temperature, which would also result in inferior brazing quality.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a brazing apparatus and a brazing method in which the brazing quality is not influenced by temperature conditions of the articles to be brazed etc.
To achieve the object shown above, a brazing apparatus according to a first aspect of the present invention comprises: preheating means for preheating articles to be brazed; detecting means for detecting the temperature of the preheated articles to be brazed; heating means for heating the preheated articles to be brazed; control means for controlling the heating means to heat the preheated articles to be brazed to a prescribed temperature on the basis of the detected temperature; and brazing means for brazing the articles to be brazed which have reached the prescribed temperature.
With this structure, the heating means is controlled on the basis of the temperature of the articles measured before they are heated by the heating means.
According to a brazing apparatus of a second aspect of the present invention, in the structure of the first aspect, the control means comprises calculating means for calculating the amount of heating required to heat the articles to be brazed to the prescribed temperature on the basis of their temperature, the calculating means calculating the amount of heating on the basis of conversion data obtained about each of different combinations of articles of different shapes or different materials, and wherein the control
Ishida Kazutaka
Takahashi Mitsuo
Cooke Colleen P.
Daishin Industrial Co., Ltd.
Dunn Tom
Rabin & Berdo P.C.
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