Method of making blanks and clad parts

A composite blank is formed from an aluminum base blank and an aluminum brazing alloy clad material which is affixed to the base blank. Alternately, a multielement blank is formed by at least one base preform and at least one separate clad preform. The composite and multielement blanks are forged into required parts such that as the required parts are formed, the clad material forms an integral coating on the finished part in one or more positions which are to be clad. The composite blank may be formed by initially forming a base blank having one or more recesses on its surface into which clad material is inserted. Recesses can be formed in base blanks as slots during extrusion of the base blanks in a continuous form or otherwise. Clad material is then inserted into each slot on the continuous form with composite blanks being formed by cutting the resulting continuous form. Alternately, clad material can be extruded into each slot or the base blank and clad material can be co-extruded to fill each slot with clad material. A composite blank can also be formed by covering one or more continuous portions of the outer surface of a base blank with clad material.

BACKGROUND OF THE INVENTION 
The present invention relates in general to the preparation of brazeable 
metals for brazing and, more particularly, to the application of a brazing 
alloy to a part to be brazed during the formation of the part, for example 
by formation of a multielement blank or a composite blank including a 
parent metal and a braze alloy with the part then being formed from the 
multielement blank or the composite blank. 
Brazing alloy will be used herein to refer to materials used to braze or 
solder one metallic part to another. Conventionally, a brazing alloy is 
clad or permanently applied by mechanical or chemical processes to 
surfaces of parts which are to be joined to other parts to form an 
assembly. Once assembled, the parts are heated to a temperature which 
melts the brazing alloy to fuse the assembly. 
Parts can be preformed and then brazing alloy clad to the parts. More 
commonly, brazing sheet is formed by cladding a sheet of brazing alloy to 
a base sheet of a parent metal. The brazing sheet is then used to form 
clad parts. 
Unfortunately, cladding preformed parts requires special cladding baths or 
other apparatus which can add substantially to production time and 
expense. Forming parts from clad brazing sheet also has disadvantages. For 
example, the parts which can be formed from clad brazing sheet are limited 
since many parts cannot be formed to required shapes while keeping the 
clad surface complete and properly located to be joined to mating parts. 
Accordingly, there is a need for new techniques to fabricate clad parts 
quickly and inexpensively to supplement current fabrication techniques. 
SUMMARY OF THE INVENTION 
This need is met by the methods and apparatus of the present invention 
wherein clad material is formed onto a part during formation of the part. 
In one embodiment of the invention, a composite blank is initially formed 
from a parent metal, such as aluminum, and clad material, such as an 
aluminum brazing alloy. The composite blank is then used to form the 
required part. The clad material is positioned on the composite blank such 
that it forms an integral coating of the clad material on the parent 
material in the proper location on the finished part. Using composite 
blanks of the present invention permits clad parts to be quickly and 
inexpensively produced which could not be so produced using conventional 
methods. 
In another embodiment of the present invention, a multielement blank is 
utilized. The multielement blank is made up of at least one blank preform 
formed from a base material and having a defined size and shape, and at 
least one clad preform formed from clad material and having a defined size 
and shape corresponding to the blank preform. In the illustrated 
embodiment, a multielement preform comprises a two-part blank having one 
blank preform and one clad preform. The blank preform(s) and clad 
preform(s) are then inserted into a die which is operated, for example by 
forcing a punch thereinto, such that the clad material forms an integral 
coating on at least one portion of a surface of a clad part formed by 
forging the clad part from the multielement blank. 
In addition to composite and multielement blanks and use of such blanks to 
form clad parts, the present invention encompasses methods for forming 
composite blanks. For example, a base blank is initially formed from a 
parent metal with clad material being inserted into one or more recesses 
on the base blank to form a composite blank which can be formed into a 
clad part. Recesses can be formed in base blanks as slots during extrusion 
of the base blanks in a continuous form or otherwise. Clad material is 
then inserted into each slot on the continuous form with composite blanks 
then being formed by cutting the continuous form. Alternately, clad 
material can be extruded into each slot or the base blank and clad 
material can be co-extruded to fill each slot with clad material. 
Alternately, a composite blank can be formed by covering one or more 
continuous portions of the outer surface of a base blank with clad 
material. For example, solid or hollow generally cylindrical base blanks 
can be covered with clad material which partially or totally surrounds 
cylindrical sections of the base blanks to form composite blanks which can 
then be used to form sections of clad tubing or tubing having clad 
cylindrical rings thereon. 
In accordance with one aspect of the present invention, a method for making 
a clad part comprises the steps of: forming a blank having clad material 
affixed to form at least one portion of an outer surface of the blank; 
and, forging the clad part from the blank to form an integral coating of 
the clad material on at least one portion of the outer surface of the clad 
part. 
In one embodiment, the step of forming a blank having clad material affixed 
to at least one portion of an outer surface of the blank comprises the 
steps of: forming a blank having a recess therein; forming clad material 
into a preform sized to be received within the recess; and, inserting the 
preform into the recess in the blank. In turn, the step of forming a blank 
having clad material affixed to at least one portion of an outer surface 
of the blank may comprise the steps of: forming a continuous strip of 
blank material having at least one slot extending into an outer surface of 
the strip; forming clad material into strips sized to be received into the 
at least one slot of the continuous strip of blank material; forcing one 
of the strips of clad material into each of the at least one slot of the 
continuous strip of blank material to form a composite strip; and, cutting 
the blank from the composite strip. 
In another embodiment, the step of forming a blank having clad material 
affixed to at least one portion of an outer surface of the blank comprises 
the steps of: extruding a continuous strip of blank material having at 
least one slot extending into an outer surface of the strip; extruding a 
strip of clad material into each of the at least one slot to form a 
composite strip; and, cutting the blank from the composite strip. 
In still another embodiment, the step of forming a blank having clad 
material affixed to at least one portion of an outer surface of the blank 
comprises the steps of: forming clad material into a tubular form; forming 
a cylinder of blank material sized to be frictionally received within the 
tubular form of clad material; and, inserting the cylinder of blank 
material into the tubular form of clad material. 
In yet another embodiment, the step of forming a blank having clad material 
affixed to at least one portion of an outer surface of the blank comprises 
the steps of: forming clad material into a tubular form; forming a tubular 
blank sized to be received within the tubular form; and, fixing the 
cylinder of blank material within the tubular form. 
In an initial application of the present invention, the blank is formed of 
aluminum and the clad is an aluminum brazing alloy. 
In accordance with another aspect of the present invention, a method of 
making a blank from which a clad part is formed comprises the steps of: 
forming a base blank having a defined size and shape; and, affixing clad 
material to the base blank to form at least one portion of an outer 
surface of the blank. The method may further comprise the step of forming 
at least one recess in an outer surface of the base blank; and, the step 
of affixing clad material to the base blank to form at least one portion 
of an outer surface of the blank comprises the steps of: forming clad 
material into a preform sized to be received within the at least one 
recess; and, inserting a preform into each of the at least one recess in 
the base blank. 
In accordance with still another aspect of the present invention, a method 
of making a blank from which a clad part is formed comprises the steps of: 
forming a base blank having a defined size and shape with at least one 
recess in an outer surface of the base blank; forming clad material into a 
preform sized to be received within the at least one recess; and, 
inserting a preform into each of the at least one recess in the base 
blank. 
In one embodiment, the step of forming a base blank comprises extruding 
blank material to have at least one slot extending into an outer surface 
of a resulting extrusion, the at least one slot defining the at least one 
recess. For this embodiment, the step of forming clad material into a 
preform may comprise the step of extruding at least one strip of clad 
material sized to be received within the at least one slot. 
A method of making a blank from which a clad part is formed as claimed in 
claim wherein the step of inserting a preform into each of the at least 
one recess in the base blank comprises the step of co-extruding the blank 
material and the clad material such that the clad material is extruded 
into the at least one slot. The step of inserting a preform into each of 
the at least one recess in the base blank may comprise pressing a strip of 
clad material into each of the at least one slot. Alternately, the step of 
inserting a preform into each of the at least one recess in the base blank 
comprises the step of rolling a strip of clad material into each of the at 
least one slot. 
In the noted initial application, the base blank is formed of aluminum and 
the clad material is an aluminum brazing alloy. 
In accordance with yet another aspect of the present invention, a blank 
from which a clad part is formed comprises a base blank having a defined 
size and shape with clad material affixed to form at least one portion of 
an outer surface of the blank. The base blank may comprise at least one 
recess in an outer surface thereof with the clad material being received 
within each of the at least one recess. Preferably, the at least one 
recess comprises at least one slot formed into the base blank, and the 
clad material comprises at least one strip of clad material. In the noted 
initial application, the base blank is formed of aluminum and the clad 
material comprises an aluminum brazing alloy. 
In accordance with yet still another aspect of the present invention, a 
method for making a clad part comprises the steps of inserting clad 
material and base material into a die, and operating the die to form a 
clad part from the base material and clad material by integrally coating 
the clad material on at least one portion of a surface of the clad part as 
the clad part is formed. In the forming methods of the present invention, 
the die may be operated such as by closing two or more parts of the die to 
form a clad part or the step of operating the die may comprise the step of 
forcing at least one punch into the die. The method may further comprise 
the steps of forming the clad material into a preform corresponding to the 
clad part to be made, and forming the base material into a blank 
corresponding to the clad part to be made. 
In accordance with a final aspect of the present invention, a multielement 
blank from which a clad part is formed comprises at least one blank 
preform formed from a base material and having a defined size and shape, 
and at least one clad preform formed from clad material and having a 
defined size and shape corresponding to the blank preform such that the 
clad material forms an integral coating on at least one portion of a 
surface of a clad part formed by forging the clad part from the two-part 
blank. 
It is thus an object of the present invention to provide an improved method 
and apparatus for quickly and inexpensively producing clad parts; to 
provide an improved method and apparatus for quickly and inexpensively 
producing clad parts by means of a composite blank from which the clad 
parts are formed; to provide an improved method and apparatus for quickly 
and inexpensively producing clad parts by means of a two-part blank from 
which the clad parts are formed; to provide an improved method and 
apparatus for quickly and inexpensively producing clad parts which are 
formed from a novel composite blank formed by combining a base blank of a 
parent material and clad material which is affixed to said base blank to 
form at least one portion of an outer surface of the composite blank; and, 
to provide an improved method and apparatus for quickly and inexpensively 
producing clad parts which are formed from a novel multielement blank 
including at least one blank preform of a parent material and at least one 
clad preform of a clad material which are inserted into a die which is 
thereafter operated to form a clad part having at least one portion of a 
surface thereof integrally coated with clad material.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention will now be described with reference to the drawing 
figures. While the present invention is generally applicable to the 
formation of a wide variety of clad parts, as will become apparent, a 
first embodiment will be described with reference to the clad part of FIG. 
2 which is formed from a composite blank 100 of FIG. 1. 
The composite blank 100 is made up of a base blank 102 formed from a parent 
material to which clad material 104 is affixed to form at least one 
portion of the outer surface of the composite blank 100. For the composite 
blank 100, the clad material 104 forms two portions or strips of its outer 
surface. In the application of the illustrated embodiment of FIGS. 1 and 
2, the parent material is aluminum and the clad material 104 is an 
aluminum brazing alloy. 
The base blank 102 can be formed in any manner; however, it is presently 
preferred to extrude the base blank 102 into a continuous form as 
indicated by the phantom lines of FIG. 1. Extrusion of the base blank 102 
is illustrated in FIG. 7 which shows co-extrusion of the base blank 102 
and the clad material 104 as will be described with reference to FIG. 7. 
In any event, the base blank 102 is formed to have at least one recess in 
its outer surface. In FIG. 1, two recesses are formed into the base blank 
102, a first recess 106 in the top of the blank and a second recess 108 in 
the bottom of the blank. 
To complete the composite blank 100, clad material 104 is formed into a 
preform sized to be received within the recesses 106, 108. In the 
illustrated embodiment of FIG. 1, the clad material 104 is formed into a 
strip 104s, one of which is shown in FIG. 5. The strip 104s of clad 
material 104 is then pressed or rolled into the recesses 106, 108. As 
shown in FIG. 5, a continuous run of the strip 104s is pressed into a 
single recess or slot 106s formed into an upper surface of a base blank 
102b as the base blank 102b and the strip 104s advance through rollers 110 
as indicated by the arrows 111. The resulting continuous composite blank 
strip is then cut to a required length for a given application, for 
example, the length L for the composite blank 100 of FIG. 1. 
As shown schematically in FIG. 6, the strip 104s of clad material 104 can 
also be extruded into the slot 106s of the base blank 102b by means of a 
ram 112. The ram 112 moves in the direction of the arrow 114 to extrude a 
billet 116 of cladding material from a die/extruder 118 into the preformed 
slot 106s of the base blank 102b as the base blank 102b moves in the 
direction of the arrow 120 in synchronism with the ram 112. 
The base blank 102b and the strip 104s of clad material 104 can also be 
co-extruded as shown schematically in FIG. 7. In FIG. 7, a first ram 122 
moves in the direction of an arrow 124 to extrude a billet 126 of parent 
material, such as aluminum, from a die/extruder 128 to form the base blank 
102b. A second ram 130 moves in the direction of the arrow 132 to extrude 
a billet 134 of cladding material, such as an aluminum brazing alloy, from 
the die/extruder 128 into the slot 106s of the base blank 102b as the base 
blank 102b is being extruded. 
Other methods of forming composite blanks and other composite blank forms 
in accordance with the present invention will be apparent to those skilled 
in the art in view of the teachings of the present application. For 
example, a composite blank 136 as shown in FIG. 8 can be used to form a 
section of clad tubing 138 as shown in FIG. 9. 
The composite blank 136 comprises a tubular section 140 of clad material 
104 and a cylinder 142 of blank material sized to be received within the 
tubular section 140. The composite blank 140 is formed by fixedly 
inserting the cylinder 142 into the tubular section 140. The cylinder 142 
and the tubular section 140 are fixedly secured to one another by friction 
or otherwise. 
The composite blank 140 is then forged or extruded to become the section of 
clad tubing 138 shown in FIG. 9 wherein a tube 144 is clad with a thin 
layer 146 of the cladding material 104. As shown by the dash-dot lines in 
FIG. 8, the cylinder 142 can be tubular to assist in forming the section 
of clad tubing 138 or determining the thickness of the tube 144. 
It should also be apparent that the tubular section 140 of cladding 
material does not have to completely cover the outer cylindrical surface 
of the cylinder 142 but can be limited to only portions of the cylindrical 
surface of the cylinder 142. This is indicated by the dotted lines 148, 
150 of FIGS. 8 and 9, respectively. Such partial cladding could be used, 
for example, to braze one or both ends of the section of clad tubing 138. 
Where only portions of the cylindrical surface of the cylinder 142 are 
covered, it is presently preferred to form annular recesses to receive the 
clad material, although such recesses are not necessary. 
The formation of clad parts using composite blanks will now be described 
with reference to FIGS. 1-4. As shown schematically in FIG. 3, one 
composite blank 100 is placed into a receiving cavity of a die 152 and 
supported upon an ejector 154 which is maintained in its retracted 
position shown in FIGS. 3 and 4. A forming punch 156 is then forced into 
the cavity of the die 152 to forge or extrude the composite blank 100 into 
a manifold fitting 158 shown in perspective view in FIG. 2. The punch 156 
is then withdrawn from the cavity of the die 152 and the fitting 158 is 
ejected from the cavity by operation of the ejector 154. 
As can be seen in FIGS. 2 and 4, during this operation the clad material 
104 forming part of the composite blank 100 forms an integral coating 104c 
on the sides of the fitting 158 (or top and bottom of the fitting 158 as 
shown in FIG. 2) in the proper locations for brazing the manifold fitting 
158 into a manifold assembly. 
For the manifold fitting 158 of FIG. 2, associated plates (not shown) are 
positioned on the top and bottom of the generally rectangular portion 158r 
and the assembly is heated to melt the integral coating 104c of clad 
material 104 to fuse the parts together. Openings in both sides of the 
generally rectangular portion 158r of the manifold fitting 158 for 
communicating the fitting with passageways in the associated plates is 
later formed by punch operation or other well known procedures which are 
not important to the present invention. 
A second embodiment will now be described with reference to FIGS. 10-15 
which illustrate use of a multielement blank of the present invention. 
FIGS. 10-12 illustrate generically formation of clad parts from two-part 
blanks. As shown in FIGS. 11 and 12, a two-part blank can be used to clad 
either at least a portion of an interior surface of a clad part or at 
least a portion of an exterior surface of a clad part. It is also noted 
that if both clad preforms are utilized to define a multielement blank 
having three parts, the resulting three-part blank can be used to clad at 
least a portion of an interior surface of a clad part and at least a 
portion of an exterior surface of a clad part. 
While a simple rectangular part having a rectangular cavity formed therein 
is illustrated in FIGS. 11 and 12, it is apparent that a great variety of 
parts can be formed by shaping the die, punch and multielement blanks in 
correspondence with parts to be formed. With this understanding, the 
formation of the rectangular clad parts 160 and 162, shown respectively in 
FIGS. 11 and 12, from two-part blanks will now be described. 
In FIG. 10, clad material, either a clad preform 164 or a clad preform 166, 
and base material, a blank preform 168, are inserted into a cavity 170 of 
a die 172. While the die 172 could be a two-part die which is operated or 
closed to forge a part from a two-part blank contained therein, in the 
illustrated embodiment a punch 174 is forced into the cavity 170 of the 
die 172. 
If the clad preform 166 and the blank preform 168 are inserted into the 
cavity 170 of the die 172, the clad part 162 results from operation of the 
punch 174. As shown in FIG. 12, the clad part 162 has clad material 176 
integrally coating its lower outside surface. The bottom 162b of the clad 
part 162, the upper portion 162u and a rectangular cavity 178 are not 
coated with clad material. The clad preform 166 and blank preform 168 are 
properly located within the die 172 for forging by the cavity 170. 
If the clad preform 164 and the blank preform 168 are inserted into the 
cavity 170 of the die 172, the clad part 160 results from operation of the 
punch 174. As shown in FIG. 11, the clad part 160 has clad material 180 
integrally coating the lower inside portion of its internal rectangular 
cavity 182 with the remainder of the clad part 160 not being coated with 
clad material. The blank preform 168 is properly located within the die 
172 for forging by the cavity 170. The clad preform 164 is positioned by 
placement into the cavity 170, by a shallow indentation 168i shown in 
dotted lines on the blank preform 168, by structure (not shown) on the 
punch 174, by thin ribbed extensions (not shown) from the clad preform 168 
or otherwise as will be apparent to those skilled in the art. 
It should also be apparent that the blank preform 168 and both clad 
preforms 164 and 166 can be utilized as a three-part multielement blank. 
In that event, the result is a clad part which would be the combination or 
merging of the clad parts 160 and 162. Such a part would have clad 
material integrally coating its lower outside surface as in the clad part 
162 and clad material integrally coating the lower inside portion of its 
internal rectangular cavity as in the clad part 160. 
While FIGS. 10-12 generically illustrate formation of clad parts using a 
two-part blank in accordance with the present invention, FIGS. 13-15 
illustrate formation of a specific clad part, a connector tube 184 for use 
in a heat exchanger of an air conditioning system. As shown in FIG. 4 a 
two-part blank comprises a generally cylindrical or, more accurately, 
annular blank preform 186 formed, for example from aluminum, and a 
circular clad preform 188 formed, for example from an aluminum brazing 
alloy. 
For production of the connector tube 184 shown in FIG. 15, the clad preform 
188 is placed into a cavity 190 of a die 192. Next, the blank preform 186 
is inserted into the cavity 190 on top of the clad preform 188. A punch 
194 and surrounding sleeve 196 are next forced into the cavity 190 to form 
the connector tube 184 from the two-part blank comprising the blank 
preform 186 and the clad preform 188. The resulting structure includes an 
upper cylindrical extension 198 and a lower, more narrow cylindrical tube 
200. The extension 198 is joined to the tube 200 by an annular flange 202 
and a frustoconical extension 204. As shown in FIG. 15, the lower portion 
of the annular flange 202 is integrally coated by clad material 206 during 
the forging operation described. The connector tube 184 is used by having 
its tube 200 inserted into a receiving part to a point where the lower 
portion of the annular flange 202 rests against a matching surface. The 
parts are then heated to a temperature which melts the clad material 206 
to fuse the connector tube to the receiving part. 
Having thus described the methods and apparatus of the present invention in 
detail and by reference to preferred embodiments thereof, it will be 
apparent that modifications and variations are possible without departing 
from the scope of the invention defined in the appended claims.