CA1152387A - Process for joining narrow width thin gage metal or alloy strip - Google Patents
Process for joining narrow width thin gage metal or alloy stripInfo
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- CA1152387A CA1152387A CA000379247A CA379247A CA1152387A CA 1152387 A CA1152387 A CA 1152387A CA 000379247 A CA000379247 A CA 000379247A CA 379247 A CA379247 A CA 379247A CA 1152387 A CA1152387 A CA 1152387A
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- metal
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Abstract
ABSTRACT OF THE DISCLOSURE
A process is disclosed for joining narrow width thin gage metal or alloy strip end to end to form an elongated coil. The trailing end of a first strip segment and the leading end of a second strip segment are cut so as to match when placed in a butting relationship and to establish a joint between the strips. A preselected gap is estab-lished between the butting ends and a braze material is inserted in the gap. After heating to braze the strip segments together, the brazed joint is hammered to reduce the joint geometry to that of the parent metal strip segments.
A process is disclosed for joining narrow width thin gage metal or alloy strip end to end to form an elongated coil. The trailing end of a first strip segment and the leading end of a second strip segment are cut so as to match when placed in a butting relationship and to establish a joint between the strips. A preselected gap is estab-lished between the butting ends and a braze material is inserted in the gap. After heating to braze the strip segments together, the brazed joint is hammered to reduce the joint geometry to that of the parent metal strip segments.
Description
goo5 ~ACKG~UN~ OF THE IN~NTI_N
Numerous industrial mass production processes utilize long coils of narrow width thin ga~e metal or alloy strip material. For example, long coils of narrow width thin gage copper alloy strip material frequently find use in the electronics industry in con~inuous mass production of con-tacts and in continuo~s for~.ation of connectors from moving strip material. It is frequently required, therefore, to provide long lengths of strip material of uniform geometry which are adapted to readily pass through mass production forming, stamping and assembling machinery.
In order to form such long coils of metal or alloy narrow width thin gage strip material, it is necessary to join a succession of lengths of strip material end to end and to subsequently wind the continuously-ioined strip ma~erial onto a large spool or storage reel. While the desire to quickly, efficiently and economically carry cut such joining is apparent, it nevertheless is essential that the ~oints between strip segments be uniform with the remainder of the strip material so that the stamping or other mass production machinery utilized in forming contacts and other products can operate without interruption and/or jamming due to cross-sectional variations in strip cross section.
While the welding of thick strips, that is strips ~reater than about 0.012 in. gage, poses no particularly excessive problem.s, the welding of narrow rridth thin ga~e strip, that is strips less than about 0.012 in. gage, poses several particularly troublesome problems. These problems include burn-through of the strip material while welding, explosion of the strip material, alignment and overlap 9005-~B
problerns associated with the hblding and heating of the narrGw width thin strip material, and the need for expensiYe welding equipment and/or welders possessing a high order of skill for operating the equipment and carrying out the welding processes.
Accordingly, it is the principal ob~ect of the present invention to provide a process and means for rapidly, simply, and efficiently joining a multiplicity of lengths of narrow width thin gage strips end to end to form a substantial continuous strip.
It is still a further object of the present invention to provide a process for rapidly and efficiently joining a muitiplicity of lengths of narrow width thin gage strips end to end to form a substantial continuous strip which process may be carried out by an inexperienced operator with a minimum of training.
It is still a further object of the present invention to provide a process for forming a continuous strip from a plurality of narrow width thin gage strips which eliminates the need for the use of expensive and/or complex apparatus in carrying out the joining process.
Finally, it is yet a further ob~ect of the present invention to provide a process and means for rapidly, simply, and efficiently joining a multiplicity of lengths of narrow width thin gage strips into a continuous strip whereby, although the joints between the lengths of stri~ ma~erial comprise or include a different material than the strip segments, the Joints are of the same gage and geometry of the continuous strlp elements, and are strong er.ough not to break when placed on a TWR (transverse winding reel).
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Further objects and advantages will appear hereinbelow.
P~IO~ ~T STA`TE~NT
It is known to form a continuous coil from thlck gage strip, i.e. strip formed from materials greater than about 0.012 in. gage, by resistance butt welding a series of relatively short length coils of strip and traverse winding these onto a large spool. This butt welding process is time-consuming and has frequently to be repeated to obtain a single Joint. Adhesion is often marginal, and application of tension and/or flexure to these joints often causes failure.
In thinner gage materials, that is strip material less than about 0.012 in., resistance butt welding is generally not useful since the application of welding current can cause arcing and expulsion of molten metal and/or will, because of the inability of the heated metal to support its own weight, lead to folded or excessively overlapped joints. The 12tter conditions are undesirable since in most cases the Joined coils are often required to pass between dies whose clearance is typically such that metal passing through the die cannot vary by more than + 0.0005 in.
TIG welding has been used to successfully join narrow width thin gage materials, but the capital outlay for this t~-pe of equipment is high. An even greater problem and limitation with this type of welding is that a relatively high order of skill is required to achieve successful joints.
Uni~ed States Patent No. 3,421J676 to Jenkins et al.
discloses a process of joining thin metal sheets wherein end portions of the sheets are cut, cleaned and held in butting relation. After butting the sheets together, the joint is sprayed with hot molten metal particles which are allowed to 9005~ 3 cool and solidify after which the joint is heated to proYide a fused ~oint. The joining of the sheets is f~llowed by a compressirg or planishing operation, preferably by planishing roll means. Such a process when utilized for the ~oining of narrow width thin gage metal st.ips suffers from several Zrawbacks. Wnen thin sheets are placed in butting relatior, they expand upon being heated, thereby causing foldover of the joint or severe overlap at the ~oint. When it is attempted to overcome such an overlap or foldover by compressing, severe metal flow causes doglegging of the strip and requires exces-sive effort ~nd time to overcome. In addition, spraying of molten metal particles along the joint leads to an overlap of material and high points across the area of the strips bridging the ~oint which again requires excessive and time-consuming wo~k to remove or reform in order to get the joint to the same geometry of the strips. Finally, compression by plan-ishing rolls tends to cause local inhomogeneity of deformation which can result in "oil can" effects and doglegging of the ~oined strip.
The establishing of a predetermined gap between strip ends prior to welding is shown in United States Patent Nos.
3,403,833 to Wheeler et al. and 3,771,215 to Williams et al.
The t 833 patent discloses a complex strip clamp assembly which is utilized to establish a predetermined spacing between trimmed ends of two strips to be joined. The '215 patent - utilizes an indexing means in conjunction with a gauge bar located at a welding station, the gauge bar and indexing means ser~ing to establish a predete-rmined gap bet~een the ends of the strips to be joined in the welding station.
Both these patents disclose complex and expensive spacing 5QC5--ilB
and weldin~ apparatuses, the need of which it is the purpose of the present invention to obviate. In addition, neither patent is directed specifically ro the joining of narrow width thin gage strips, which as stated hereinabove, are not economically and readily susceptible to welding operations.
The Metals Handbook, Volume 6 (T~elding ~nd Brazing) 3 8th .
Edition, describes in part the cost benefits of ~lanual torch brazing of parts and establishes typical joint clearances for use with filler metals commonly employed in jGining copper and copper alloys. ~hile such clearances might be of importance in the jcining of certain metal parts, no con-sideration has been given ro coefficients of expansion and consequent joint o-~erlap or curling in the joining of strips in end to end relation. Moreover, clearances which relate to the filler metal utilized do not recognize considerations and problems which relate to the joining of narrow width thin gage strip material.
United States Patent Nos. 2,761,208 to ~itchell and 3,110,101 to Kieffer et al. disclose reducing welded joints between joined strips by mechanical processing. The '208 patent teaches cold working an overlapped-welded joint, preferably by drawing the joined strip through finishing dies, while the 'lQl patent teaches high frequency hammering of the welded junction between two strips consisting of a metal selected from the group consisting of molybdenum, tungsten and alloys thereof. Neither of these two patents sol~Je any of the problems enumerated in the background section hereinabove, and deal with a treatment of joints which effects excessi~e metal deformation unsuitable for reduction of joints in narrow width thin gage strip products.
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The present.invention overcomes the deficiencies described aboYe and pro~ides an efficient, speedy, and economical process for joining narrow width thin gage metal or alloy strips which can be carried out without the need for expensive apparatus and/or highly skilled operators.
SU~MARY OF TH~ INVENTION
The process of this invention ~s unique in that butt joining of narrow width thin gage strip material is accom-plished via a brazing process which enables quick, efficient, and inexpensive joining of the strip material into a continuous coil of geometrically uniform narrow width thin gage strip material.
In practicing the instant joining process, metal buildup at ~oints is minima~ and joint strength has been found to be approximately 80% that of the annealed parent metal strips.
Because of the heating required to braze the uoint, softening of the strip occurs on either side of the brazed joint and thus in flexing, the bending forces are not concentrated at the brazed ~unction. In a further aspect of the present invention, any excess braze metal present at the ~oint can be readily reduced to the parent gage of the strip by a specific hammering operation which takes into account the fact that the braze metal is typically softer than the parent metal.
In accordance with the present invention, cooperating end portions of two n.~rrow width thin gage strip segments are cut, aligned and held together with a predetermined gap therebetween, and ~oined by a brazing operation forming a ~oint therebetween. The brazed ~oint is subsequently reduced so as to have substantially the same geometric cross section 9005-.T~B
as the parent metal strip segments.
BRIEF_~ESCRIPTIO~ OF_THE DRAWINGS
Figures l(a) and l(b) are partial top and side views, respectively, showing a finished brazed joint between two narrow width thin gage s~rips joined together in accordance with the process Gf this invention.
Figure 2 is a partial perspectiYe view of a guillotine-type cutter adapted to carry out a strip cutting step in accordance with this invention.
Figure 3 is a perspective view of a brazing fixture adapted to carry out multiple strip segment gaging, holding, and aligning steps in accordance with the process of the present invention.
~ igure 4 is a partial side view illustrating another step in the process of the present invention wherein a torch is shown melting braze ma-terial placed in the joint between two narrow width ~hin gage strips.
Figure 5 is a perspective view of a ha~mering device utilized in hammering the joint area of two narrow width thin gage strips to gage in accordance with another aspect of the present invention.
~ igure 6 is a partial view in section of a completed joint produced in accordance with the process of the present invention.
Figures 7(a) and 7(b) are partial views, respectively, in section of an undesirable brazed and hammered joint formed when brazing of the joint is carried out on excessively over-lapped narrow width thin gage strip end~ and excessive hammering of the ~oint is required to reduce the joint to parent metal or alloy gage.
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DETAILED DESCPIIPTION OF ~REF~R~ED EMBCDIMENT
While Yarious features of this invention are described herein as being adaptable for joining of copper and copper alloy narrow width thin gage strips, it is to be understood that the various features of this ~nvention can be utilized singly or in any combination thereof to join other metal and alloy strip elements-as desired.
Figures l(a) and l(b) are top and bottom views showing portions of a continuous narrow wi~th thin gage strip 1 made up in part of strip segments 4 and 5. The strip segments 4 and 5 are joined together at a joint 7 via a brazing material 8. The joint 7 is shown to be of the same geometrical cross section as that of the parent metal of strip segments 4 and 5. It is, of course, to be understood that any number of strip segments may be ~oined end to end to make up a continuous strip 1 of any desired length.
The term narrow width thin gage s~rip is used herein to include any metal or alloy strip material which has a width of about 3 in. or less and a thickness of about 0.012 in. or less.
In one aspect of the present invention, the strip segments ~ and 5 have their respective ends 10 carefully cut or trimmed so as to insure that the cut ends 11 (shown as dotted lines in Figure 2) will match on subsequent brazing. Figure 2 depicts one suitable apparatus for carrying out the strip segment end preparation in accordance with the brazing process of the present invention. In Figure 2, strip segments 4 and 5 are aligned on base elements 12. To facilitate lateral alignment of the strip segments 4 and 5, base elements 12 are provided w th vertical guide walls 13. When an operator has placed the gO O 5-~B
~$~7 strip ele~,ents 4 and 5 upon b~se elements' 12 in abutting ~elationship with guide walls _3,-he 'need merely activate guillotine cutter 15 to shear off respective ends 10 and ~hereby assl~re that the now cut ends 11 of strip segments 4 and 5 match on subseauent brazing.
After providing cut ends''ll on strip segments 4 and 5, the segments are aligned in abutting relationship with a pre-determined gap therebetween for subsequent brazing of the ~oint 7. Figure 3 depicts a brazing fixture 20 particularly suitable for alignment and securing of the strip segments 4 and 5 for subsequent brazing operations. Brazing fixt~re 20 is shown provided with alignment steps 22 having machined faces 24 for providing alignment of the edges of strip segments 4 and 5. Also secured to or forming part of the brazing fixture is a pair of clamps 26. ~lamps 26 are utilized to hold strip segments 4 and 5 via clamping screws 27 down on the upper surface 28 of anvils 29. The anvlls 29 are machined so tnat the upper surfaces 28 thereof provide effective alignment of the strip segments 4 and 5 in a single plane at least in the area of the joint to be brazed.
Also mounted to the body of brazing fixture 20 is a movable feeler gage 32. Feeler gage 32 is shown between the cut ends 11 of strip segments 4 and 5 which abut flush therewith, and is adapted via shaft 34 to be rotated out of the Joint area during actual brazing operations.
Various modifications could, of course, be made to holding fixture 20. For example, flat platens could be provided at the tip of clamping screws 27 so as to prevent dama~e to secured strip segments 4 and 5. Moreover, any of a variety of clamping devices could be used, as for example _g _ , $ ~ ~
spring activated, single action, and other types of clamps.
While anvils 29 might be constructed of various materials such as for example transite, anvils constructed of a fired ceramic material such as "Lava" manu~actured by 3M Company have been found to be more suitable for use in conjunction with the process of the present invention, exhibi-ting excellent wear characteristics while simultaneously functioning to limit the heat transferred from the brazing zone.
A gap of approximately 9/16 in. between the anvil edges 30 has been found to be quite suitable, being small enough to provide sufficient support for the overhanging end portion of the strip segments 4 and 5 while at the same time being wide enough to permit the carrying out of the gap setting and brazing steps of the present invention.
Figure 4 shows the use of a torch 36 to apply heat to a brazing paste or material 8 located in the joint between the two strip segments 4 and 5~ It has been found that for some alloys and gages, such as o.oo8 in. gage copper alloy C26000 strip, a simple hand-held propane torch with a wide cone tip was ade~uate to carry out brazing. However~ an air-acetylene or similar hotter flame might be more versatile if a varlety of metal alloys and gages are to be joined. Strip widths of about 1 in.
or less are preferred when utilizing hand-held propane torches since it becomes more difficult to apply uniform heat across the width of the strip segments as the width increases.
~ eferring now to Figure 5, there is depicted therein a vertically-mounted pneumatic hammer 40 provided with a striker head 42 specifically designed to uniformly reduce the joint 7 with minimal distortion of the adjacent strip areas. The striker head 42 and anvil 44 present flat faces to the strip so reduction becomes self-limiting as base metal gage is approached. Pneumatlc hammer 40 is connected to a source of high pressure air (not shown) via inlet _.
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~ xcessiYe hammering and metal flow when reducing a brazed and dressed ~oint to parent metal gage will often result in metal cracking, doglegging, excessive wcrk hardening, and "oil can" effects. Thus, excessiYe hammering and the use of opposed convex hammer/anvil faces in reducing brazed ~oints in narrow width thin gage strip is highly undesirable. It has been found in accordance with another aspect of the present invention that by establishing the diameter of striker head 42 to be approximately twice the width of the metal strip and by controlling the hammer pressure in accordance with the properties of the strip material a self-shimming effect takes place upon hammering of the joint.
~ pon brazing, the areas of the strip segments adjacent the joint are subjected to a moderate annea~ and both these areas and the joint are softer than the parent metal of the remainder of the strips. When hammering is carried out for short periods of time at pressures lower than would deform the parent metal of the strip segments and striker head 42 extends to the parent metal areas, excessive work hardening and metal flow is avoided and a self-shimming effect takes place--with the parent metal of the strip segments acting as ~ shim.
It should be apparent that striker head 42 need not be of a round configuration, the only requirements being that the face thereof be flat and of a longitudinal dimension or extent approximately twice the strip width. The aforementioned striker head geometry and size relatiQnship has been found to eliminate ~ost of the inhomogeneity of deformation which often resulted in "oil can" effects.
Another important aspect of the present invention lies in the establishing of an appropriate gap bet~een the cut ~005-r;~B
~$~;~7 ends 11 of strip segments 4 and 5 prior to bra~ing of the ~oint. During heating of the braze material the metal cr alloy strip segments being ~oined will expand. If the gap between the strip segment ends is too great, brazing becomes quite d~fficult and excessive amounts of braze material would be required. If the gap is too small, excessive overlap of the strips occurs~ requiring excessive reduction ope-ations which cause doglegging and "oil can" effects in the metal or alloy strip as discussed hereinabove. These problems are particularly severe in joining of narrow widt~. thin gage strip material since it is intended to carry out the brazing opera-tion as quickly, inexpensively, and efficiently as possible.
When using a hand-operated torch on thin gage strip, excessive heating would occur rapidly where a wide gap exists, and difficulty in completing an effective joint would occur.
Excessive reduction problems would exist where too narrow a gap and resultant overlap of strip segment ends exist.
Since it is not precise as to ~ust exactly what amount of heat will be applied to just what total area and for how long, it is necessary to approximate by calculation a gap size which for a particular metal or alloy strip will be most likely to result in successful ~oints. A sample calculation in accordanoe with the present invention for copper alloy C26000 follows:
(1) The coefficient of thermal expansion ~ for alloy C26000 is about 2 X lO 5/ C.
~ 2) Utilizing the equation t QO (l + ~T), where Qt is length at final temperature in cm;
QO is original length in cm;
T is final temperature, C.
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~23~7 (3) Assuming that the heated area of the strip segments ad~acent the ~oint to be approximately 1.5 cm C9/16 in.) and that the te~per~ture within this re~ion to exceed the melting point of braze metal, typically 600-650C by approximately 100C. Therefore, the average final temperature can be taken as about 700 C. Hence:
Qt = unknown QO = 1.5 cm T = 700C
Using the equation above, Qt = 1.5 (1 + 2 X 10-5 (700C)) ~t = 1.52, and ~t - QO = 0.02 cm or.2 mm = desired gap Figure 6 depicts a joint wherein upon the setting of a gap in accordance with the above calculation the cut ends of strip segments 4 and 5 just "kiss'1 after brazing and reduction.
This is the ideal ~oint inasmuch as a minimum amount of brazi~
material 8 is required for ~oining and excessive metal removal or deformation to reduce the ~oint to parent metal gage is unnecessary. Figures 7(a) and 7(b) on the other hand depict a resulting joint where no gap or an insufficient gap between strip segments 4' and 5' was provided. As can be seen from Figure 7(a), excessive amounts of braze material were required to fill the interspace between the strip segments 4' and 5' rendering the brazing process more difficult and expensive.
Moreover, as can be readily seen from Figure 7(b) excessive metal and braze material flow has resulted from the reduction operation carried out to reduce the ~oint to parent metal gage. This excessive hammering typically results in unacceptable product processing, poor strip edge geometry, 9005-i~B
S~7 dog legs, splits, etc.
Having thus described the various aspects of and means which collld be utilized to carry out the process of the present invention, such a process will be described for joining a particular strip m~terial:
(1) Assuming the two strip segments to be jGined to be 3/4 in. X o.oo8 in. copper alloy C26000, a desired gap of 0.02 cm is established in accordance with the hereinabove calculation.
t2) 5ach strip segment is placed in the cutting device depicted in Figure 2. This involves placing each strip against guide walls 13 and flat on the upper surface of base elements 12 so that ends 10 project into the cutting zone of guillotine cutter 15. The str~p segments 4 and 5 are cut by lowering cutter 15 to produce matched cut ends 11.
(3) A 0.02 cm feeler gage (32) is selected and placed on shaft 34 of brazing fixture 20 and rotated midway into the gap between edges 30 of anvils 29.
(4) One strip segment is clamped in fixture 20 (Figure 3) on one side of feeler gage 32 using surface 28 of anvil 29 and machined faces 24 of alignment steps 22. The end of this strip should abut flush against feeler gage 32. Similarly, the second strip segment is clamped into place on the other side Or and butting against feeler gage 32. Clamping is carried out by rotating screws 27 till they secure the strip segments against surface 28 of an~vil 29.
(5) Feeler gage 32 is then rotated out of the joint area bet~een the two butting strip segments.
(6) A strip of brazing paste is applied across the gap bet~Jeen strip segment cut ends 11 being sure to get material ~005~
into the gap using a minimum of paste. (One preferred way o~
applying brazing paste in such a Joint would be ~ith the use of a syringe which results in a somewhat precise amount of paste being laid into the gap between the butted strip ends without the need for skilled labor or expensive devices.) (7) Flame from a torch (preferably har.d-held) is applied from the underside of the butting strip segments. The flame is played along the ~oint or braze line only long enough to assure complete melting of the braze material.
(8) The joined strip material is unclamped and flux from the brazed joint is wiped off. The ~oint is inspected for complete attachment. If incomplete oining has occurred, the st~ip may be reclamped after which a small amount of brazing paste can be applied to the open area and gently torched till melted. If the ~oint is bad, the entire section can be cut out and the process repeated.
(9) Both sides of the Joint are dressed with a flat file paying attention to remove only excess braze. To facilitate dressing, the joined coil section can be clamped to any s~itable dressing fixture. This operation serves to minimize the hammering needed to achieve parent metal thickness at the ~oint area.
~ 10) Hammer the ~oint area to gage by placing the strip ~oint on anvil 44 and activating hammer 40 with a foot pedal or the like (not shown) while at the same time moving the joint back and forth under striker head 42. Movement should be in the longitudinal direction of the coil, and hammering should preferably be carried out for a duration in the range of about 5-10 seconds. In hammering narrow width thin gage copper alloy strips, hammer air pressures in the range of about 900,-i~B
20-4Q psi have been found to ~e satisfactory. ~ny increase cr slight widening of the strip at the ~oint loca~ion can easily be eiiminated by edge filing of the joined strip.
Various means and methods can, of course, be utilized to carry out the various steps of the afore~entioned process of brazing s'rip segments end to end. For example, instead of placing a braze paste in the jo nt between the strip se~ments it would be possible to paint the strip segment ends with a suitable flux and then heat to brazing temperature. Upon attaining brazing temperature, a thin wire of brazing alloy can be touched to the joi~t in order to accomplish joining of the two strip segments. This particular method of applying braze material provides for very good control of the actual amount of braze material applied to the ~oint and helps to avoid the need for excessive hammerirg or metal reduction of the brazed joint.
In accordance with the concepts of the present invention~
pairs of brass strip 0. oo8 in. gage by 1/2 in. l~ide were placed end to end in a clamping fixture with a separation between the strips governed as disclosed herein by the linear coefficient of expansion of brass. Both ends of the strip segments were painted with a fluxing agent and heated with an oxy-acetylene torch. Upon attaining a suitable temperature, a thin wire of brazing alloy was touched to the joint in order to accomplish ~oining of the strip scgments. Tensile prop-erties of a group of such brazed ~oin's using several brazing alloy types are shown in Table I and compared with the tensile strength of the parent metal strip in bcth the as-rolled and the annealed conditionsO
~3~5Z;~B7 TABLE I
TENSILE PROPERTIES OF ~UTT BRAZED
0.008" GAGE ALLOY 260 BRASS STRIP
0.2% Ultimate Yield Tensile Elongation Strength Strength in 2"
_ Sample (ksi) (ksi)(Pct.) Notes A 24 48 6 Cu-Sn-P braze metal B 21 44 6 Cu-Sn-P braze metal C 23 49 7 Cu-~n-P braze metal D . 20 30 9 Ag-Cd-Cu-~n braze metal E 22 33 7 Ag-Cd-Cu-Zn braze metal F 24 37 4 Ag-Cu-P braze .
metal Alloy 260 103 109 2 Parent metal for extra spring above samples Alloy 260 22 45 . 40 Typical values annealed-Several additional brazed ~oints were made in accordance with the process utilized in production of the samples in Table I with the difference that the brazed joints ~ere purposefully made using excess braze metal and then hammered in order to reduce the joint thickness to that of the parent metal strip. Tensile properties of these additional samples are shown in Table II.
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TABL~ II
TENSILE PROPERTIES ~F BUTT BRAZED AND HAi~MERED
TO RAGE 0.008" ALLOY 260 BRASS STRIP
0.2% Ultimate Vield Tensile Elongation Strength Strength in 2"
S.~mpIe (ksi) (ksi) ~ ) Notes G 27 52 9 Cu~Sn-P braze metal H 32 54 8 Cu-Sn-P braze metal I 29 53 6 5u-Sn-P braze metal J 47 55 8 Ag-Cd-Cu-Zn br~ze metal K -- 40 2.5 Ag-Cu-P braze metal It is apparent that there has ~een provided with this invention a novel process for economical, efficient~ and fast ~oining of narrow width thin gage strip segments which fully satisfy the objects, means, and advantages set forth herein before. While the invention has been described in combination with specific embodi~.ents thereof, it is evident that many alt.ernatives, modifications, and variations will be apparent to thcse skilled in the art in ligh~ of the foregoing description. Accordingly, it`is intended to embrace all such alternatives, modifications, and variations as fall wi~hin the spirit and broad scope of the appended claims.
Numerous industrial mass production processes utilize long coils of narrow width thin ga~e metal or alloy strip material. For example, long coils of narrow width thin gage copper alloy strip material frequently find use in the electronics industry in con~inuous mass production of con-tacts and in continuo~s for~.ation of connectors from moving strip material. It is frequently required, therefore, to provide long lengths of strip material of uniform geometry which are adapted to readily pass through mass production forming, stamping and assembling machinery.
In order to form such long coils of metal or alloy narrow width thin gage strip material, it is necessary to join a succession of lengths of strip material end to end and to subsequently wind the continuously-ioined strip ma~erial onto a large spool or storage reel. While the desire to quickly, efficiently and economically carry cut such joining is apparent, it nevertheless is essential that the ~oints between strip segments be uniform with the remainder of the strip material so that the stamping or other mass production machinery utilized in forming contacts and other products can operate without interruption and/or jamming due to cross-sectional variations in strip cross section.
While the welding of thick strips, that is strips ~reater than about 0.012 in. gage, poses no particularly excessive problem.s, the welding of narrow rridth thin ga~e strip, that is strips less than about 0.012 in. gage, poses several particularly troublesome problems. These problems include burn-through of the strip material while welding, explosion of the strip material, alignment and overlap 9005-~B
problerns associated with the hblding and heating of the narrGw width thin strip material, and the need for expensiYe welding equipment and/or welders possessing a high order of skill for operating the equipment and carrying out the welding processes.
Accordingly, it is the principal ob~ect of the present invention to provide a process and means for rapidly, simply, and efficiently joining a multiplicity of lengths of narrow width thin gage strips end to end to form a substantial continuous strip.
It is still a further object of the present invention to provide a process for rapidly and efficiently joining a muitiplicity of lengths of narrow width thin gage strips end to end to form a substantial continuous strip which process may be carried out by an inexperienced operator with a minimum of training.
It is still a further object of the present invention to provide a process for forming a continuous strip from a plurality of narrow width thin gage strips which eliminates the need for the use of expensive and/or complex apparatus in carrying out the joining process.
Finally, it is yet a further ob~ect of the present invention to provide a process and means for rapidly, simply, and efficiently joining a multiplicity of lengths of narrow width thin gage strips into a continuous strip whereby, although the joints between the lengths of stri~ ma~erial comprise or include a different material than the strip segments, the Joints are of the same gage and geometry of the continuous strlp elements, and are strong er.ough not to break when placed on a TWR (transverse winding reel).
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Further objects and advantages will appear hereinbelow.
P~IO~ ~T STA`TE~NT
It is known to form a continuous coil from thlck gage strip, i.e. strip formed from materials greater than about 0.012 in. gage, by resistance butt welding a series of relatively short length coils of strip and traverse winding these onto a large spool. This butt welding process is time-consuming and has frequently to be repeated to obtain a single Joint. Adhesion is often marginal, and application of tension and/or flexure to these joints often causes failure.
In thinner gage materials, that is strip material less than about 0.012 in., resistance butt welding is generally not useful since the application of welding current can cause arcing and expulsion of molten metal and/or will, because of the inability of the heated metal to support its own weight, lead to folded or excessively overlapped joints. The 12tter conditions are undesirable since in most cases the Joined coils are often required to pass between dies whose clearance is typically such that metal passing through the die cannot vary by more than + 0.0005 in.
TIG welding has been used to successfully join narrow width thin gage materials, but the capital outlay for this t~-pe of equipment is high. An even greater problem and limitation with this type of welding is that a relatively high order of skill is required to achieve successful joints.
Uni~ed States Patent No. 3,421J676 to Jenkins et al.
discloses a process of joining thin metal sheets wherein end portions of the sheets are cut, cleaned and held in butting relation. After butting the sheets together, the joint is sprayed with hot molten metal particles which are allowed to 9005~ 3 cool and solidify after which the joint is heated to proYide a fused ~oint. The joining of the sheets is f~llowed by a compressirg or planishing operation, preferably by planishing roll means. Such a process when utilized for the ~oining of narrow width thin gage metal st.ips suffers from several Zrawbacks. Wnen thin sheets are placed in butting relatior, they expand upon being heated, thereby causing foldover of the joint or severe overlap at the ~oint. When it is attempted to overcome such an overlap or foldover by compressing, severe metal flow causes doglegging of the strip and requires exces-sive effort ~nd time to overcome. In addition, spraying of molten metal particles along the joint leads to an overlap of material and high points across the area of the strips bridging the ~oint which again requires excessive and time-consuming wo~k to remove or reform in order to get the joint to the same geometry of the strips. Finally, compression by plan-ishing rolls tends to cause local inhomogeneity of deformation which can result in "oil can" effects and doglegging of the ~oined strip.
The establishing of a predetermined gap between strip ends prior to welding is shown in United States Patent Nos.
3,403,833 to Wheeler et al. and 3,771,215 to Williams et al.
The t 833 patent discloses a complex strip clamp assembly which is utilized to establish a predetermined spacing between trimmed ends of two strips to be joined. The '215 patent - utilizes an indexing means in conjunction with a gauge bar located at a welding station, the gauge bar and indexing means ser~ing to establish a predete-rmined gap bet~een the ends of the strips to be joined in the welding station.
Both these patents disclose complex and expensive spacing 5QC5--ilB
and weldin~ apparatuses, the need of which it is the purpose of the present invention to obviate. In addition, neither patent is directed specifically ro the joining of narrow width thin gage strips, which as stated hereinabove, are not economically and readily susceptible to welding operations.
The Metals Handbook, Volume 6 (T~elding ~nd Brazing) 3 8th .
Edition, describes in part the cost benefits of ~lanual torch brazing of parts and establishes typical joint clearances for use with filler metals commonly employed in jGining copper and copper alloys. ~hile such clearances might be of importance in the jcining of certain metal parts, no con-sideration has been given ro coefficients of expansion and consequent joint o-~erlap or curling in the joining of strips in end to end relation. Moreover, clearances which relate to the filler metal utilized do not recognize considerations and problems which relate to the joining of narrow width thin gage strip material.
United States Patent Nos. 2,761,208 to ~itchell and 3,110,101 to Kieffer et al. disclose reducing welded joints between joined strips by mechanical processing. The '208 patent teaches cold working an overlapped-welded joint, preferably by drawing the joined strip through finishing dies, while the 'lQl patent teaches high frequency hammering of the welded junction between two strips consisting of a metal selected from the group consisting of molybdenum, tungsten and alloys thereof. Neither of these two patents sol~Je any of the problems enumerated in the background section hereinabove, and deal with a treatment of joints which effects excessi~e metal deformation unsuitable for reduction of joints in narrow width thin gage strip products.
9005-~B
~$~
The present.invention overcomes the deficiencies described aboYe and pro~ides an efficient, speedy, and economical process for joining narrow width thin gage metal or alloy strips which can be carried out without the need for expensive apparatus and/or highly skilled operators.
SU~MARY OF TH~ INVENTION
The process of this invention ~s unique in that butt joining of narrow width thin gage strip material is accom-plished via a brazing process which enables quick, efficient, and inexpensive joining of the strip material into a continuous coil of geometrically uniform narrow width thin gage strip material.
In practicing the instant joining process, metal buildup at ~oints is minima~ and joint strength has been found to be approximately 80% that of the annealed parent metal strips.
Because of the heating required to braze the uoint, softening of the strip occurs on either side of the brazed joint and thus in flexing, the bending forces are not concentrated at the brazed ~unction. In a further aspect of the present invention, any excess braze metal present at the ~oint can be readily reduced to the parent gage of the strip by a specific hammering operation which takes into account the fact that the braze metal is typically softer than the parent metal.
In accordance with the present invention, cooperating end portions of two n.~rrow width thin gage strip segments are cut, aligned and held together with a predetermined gap therebetween, and ~oined by a brazing operation forming a ~oint therebetween. The brazed ~oint is subsequently reduced so as to have substantially the same geometric cross section 9005-.T~B
as the parent metal strip segments.
BRIEF_~ESCRIPTIO~ OF_THE DRAWINGS
Figures l(a) and l(b) are partial top and side views, respectively, showing a finished brazed joint between two narrow width thin gage s~rips joined together in accordance with the process Gf this invention.
Figure 2 is a partial perspectiYe view of a guillotine-type cutter adapted to carry out a strip cutting step in accordance with this invention.
Figure 3 is a perspective view of a brazing fixture adapted to carry out multiple strip segment gaging, holding, and aligning steps in accordance with the process of the present invention.
~ igure 4 is a partial side view illustrating another step in the process of the present invention wherein a torch is shown melting braze ma-terial placed in the joint between two narrow width ~hin gage strips.
Figure 5 is a perspective view of a ha~mering device utilized in hammering the joint area of two narrow width thin gage strips to gage in accordance with another aspect of the present invention.
~ igure 6 is a partial view in section of a completed joint produced in accordance with the process of the present invention.
Figures 7(a) and 7(b) are partial views, respectively, in section of an undesirable brazed and hammered joint formed when brazing of the joint is carried out on excessively over-lapped narrow width thin gage strip end~ and excessive hammering of the ~oint is required to reduce the joint to parent metal or alloy gage.
~$Z~
DETAILED DESCPIIPTION OF ~REF~R~ED EMBCDIMENT
While Yarious features of this invention are described herein as being adaptable for joining of copper and copper alloy narrow width thin gage strips, it is to be understood that the various features of this ~nvention can be utilized singly or in any combination thereof to join other metal and alloy strip elements-as desired.
Figures l(a) and l(b) are top and bottom views showing portions of a continuous narrow wi~th thin gage strip 1 made up in part of strip segments 4 and 5. The strip segments 4 and 5 are joined together at a joint 7 via a brazing material 8. The joint 7 is shown to be of the same geometrical cross section as that of the parent metal of strip segments 4 and 5. It is, of course, to be understood that any number of strip segments may be ~oined end to end to make up a continuous strip 1 of any desired length.
The term narrow width thin gage s~rip is used herein to include any metal or alloy strip material which has a width of about 3 in. or less and a thickness of about 0.012 in. or less.
In one aspect of the present invention, the strip segments ~ and 5 have their respective ends 10 carefully cut or trimmed so as to insure that the cut ends 11 (shown as dotted lines in Figure 2) will match on subsequent brazing. Figure 2 depicts one suitable apparatus for carrying out the strip segment end preparation in accordance with the brazing process of the present invention. In Figure 2, strip segments 4 and 5 are aligned on base elements 12. To facilitate lateral alignment of the strip segments 4 and 5, base elements 12 are provided w th vertical guide walls 13. When an operator has placed the gO O 5-~B
~$~7 strip ele~,ents 4 and 5 upon b~se elements' 12 in abutting ~elationship with guide walls _3,-he 'need merely activate guillotine cutter 15 to shear off respective ends 10 and ~hereby assl~re that the now cut ends 11 of strip segments 4 and 5 match on subseauent brazing.
After providing cut ends''ll on strip segments 4 and 5, the segments are aligned in abutting relationship with a pre-determined gap therebetween for subsequent brazing of the ~oint 7. Figure 3 depicts a brazing fixture 20 particularly suitable for alignment and securing of the strip segments 4 and 5 for subsequent brazing operations. Brazing fixt~re 20 is shown provided with alignment steps 22 having machined faces 24 for providing alignment of the edges of strip segments 4 and 5. Also secured to or forming part of the brazing fixture is a pair of clamps 26. ~lamps 26 are utilized to hold strip segments 4 and 5 via clamping screws 27 down on the upper surface 28 of anvils 29. The anvlls 29 are machined so tnat the upper surfaces 28 thereof provide effective alignment of the strip segments 4 and 5 in a single plane at least in the area of the joint to be brazed.
Also mounted to the body of brazing fixture 20 is a movable feeler gage 32. Feeler gage 32 is shown between the cut ends 11 of strip segments 4 and 5 which abut flush therewith, and is adapted via shaft 34 to be rotated out of the Joint area during actual brazing operations.
Various modifications could, of course, be made to holding fixture 20. For example, flat platens could be provided at the tip of clamping screws 27 so as to prevent dama~e to secured strip segments 4 and 5. Moreover, any of a variety of clamping devices could be used, as for example _g _ , $ ~ ~
spring activated, single action, and other types of clamps.
While anvils 29 might be constructed of various materials such as for example transite, anvils constructed of a fired ceramic material such as "Lava" manu~actured by 3M Company have been found to be more suitable for use in conjunction with the process of the present invention, exhibi-ting excellent wear characteristics while simultaneously functioning to limit the heat transferred from the brazing zone.
A gap of approximately 9/16 in. between the anvil edges 30 has been found to be quite suitable, being small enough to provide sufficient support for the overhanging end portion of the strip segments 4 and 5 while at the same time being wide enough to permit the carrying out of the gap setting and brazing steps of the present invention.
Figure 4 shows the use of a torch 36 to apply heat to a brazing paste or material 8 located in the joint between the two strip segments 4 and 5~ It has been found that for some alloys and gages, such as o.oo8 in. gage copper alloy C26000 strip, a simple hand-held propane torch with a wide cone tip was ade~uate to carry out brazing. However~ an air-acetylene or similar hotter flame might be more versatile if a varlety of metal alloys and gages are to be joined. Strip widths of about 1 in.
or less are preferred when utilizing hand-held propane torches since it becomes more difficult to apply uniform heat across the width of the strip segments as the width increases.
~ eferring now to Figure 5, there is depicted therein a vertically-mounted pneumatic hammer 40 provided with a striker head 42 specifically designed to uniformly reduce the joint 7 with minimal distortion of the adjacent strip areas. The striker head 42 and anvil 44 present flat faces to the strip so reduction becomes self-limiting as base metal gage is approached. Pneumatlc hammer 40 is connected to a source of high pressure air (not shown) via inlet _.
soos~
~z~
~ xcessiYe hammering and metal flow when reducing a brazed and dressed ~oint to parent metal gage will often result in metal cracking, doglegging, excessive wcrk hardening, and "oil can" effects. Thus, excessiYe hammering and the use of opposed convex hammer/anvil faces in reducing brazed ~oints in narrow width thin gage strip is highly undesirable. It has been found in accordance with another aspect of the present invention that by establishing the diameter of striker head 42 to be approximately twice the width of the metal strip and by controlling the hammer pressure in accordance with the properties of the strip material a self-shimming effect takes place upon hammering of the joint.
~ pon brazing, the areas of the strip segments adjacent the joint are subjected to a moderate annea~ and both these areas and the joint are softer than the parent metal of the remainder of the strips. When hammering is carried out for short periods of time at pressures lower than would deform the parent metal of the strip segments and striker head 42 extends to the parent metal areas, excessive work hardening and metal flow is avoided and a self-shimming effect takes place--with the parent metal of the strip segments acting as ~ shim.
It should be apparent that striker head 42 need not be of a round configuration, the only requirements being that the face thereof be flat and of a longitudinal dimension or extent approximately twice the strip width. The aforementioned striker head geometry and size relatiQnship has been found to eliminate ~ost of the inhomogeneity of deformation which often resulted in "oil can" effects.
Another important aspect of the present invention lies in the establishing of an appropriate gap bet~een the cut ~005-r;~B
~$~;~7 ends 11 of strip segments 4 and 5 prior to bra~ing of the ~oint. During heating of the braze material the metal cr alloy strip segments being ~oined will expand. If the gap between the strip segment ends is too great, brazing becomes quite d~fficult and excessive amounts of braze material would be required. If the gap is too small, excessive overlap of the strips occurs~ requiring excessive reduction ope-ations which cause doglegging and "oil can" effects in the metal or alloy strip as discussed hereinabove. These problems are particularly severe in joining of narrow widt~. thin gage strip material since it is intended to carry out the brazing opera-tion as quickly, inexpensively, and efficiently as possible.
When using a hand-operated torch on thin gage strip, excessive heating would occur rapidly where a wide gap exists, and difficulty in completing an effective joint would occur.
Excessive reduction problems would exist where too narrow a gap and resultant overlap of strip segment ends exist.
Since it is not precise as to ~ust exactly what amount of heat will be applied to just what total area and for how long, it is necessary to approximate by calculation a gap size which for a particular metal or alloy strip will be most likely to result in successful ~oints. A sample calculation in accordanoe with the present invention for copper alloy C26000 follows:
(1) The coefficient of thermal expansion ~ for alloy C26000 is about 2 X lO 5/ C.
~ 2) Utilizing the equation t QO (l + ~T), where Qt is length at final temperature in cm;
QO is original length in cm;
T is final temperature, C.
9005-i~B
~23~7 (3) Assuming that the heated area of the strip segments ad~acent the ~oint to be approximately 1.5 cm C9/16 in.) and that the te~per~ture within this re~ion to exceed the melting point of braze metal, typically 600-650C by approximately 100C. Therefore, the average final temperature can be taken as about 700 C. Hence:
Qt = unknown QO = 1.5 cm T = 700C
Using the equation above, Qt = 1.5 (1 + 2 X 10-5 (700C)) ~t = 1.52, and ~t - QO = 0.02 cm or.2 mm = desired gap Figure 6 depicts a joint wherein upon the setting of a gap in accordance with the above calculation the cut ends of strip segments 4 and 5 just "kiss'1 after brazing and reduction.
This is the ideal ~oint inasmuch as a minimum amount of brazi~
material 8 is required for ~oining and excessive metal removal or deformation to reduce the ~oint to parent metal gage is unnecessary. Figures 7(a) and 7(b) on the other hand depict a resulting joint where no gap or an insufficient gap between strip segments 4' and 5' was provided. As can be seen from Figure 7(a), excessive amounts of braze material were required to fill the interspace between the strip segments 4' and 5' rendering the brazing process more difficult and expensive.
Moreover, as can be readily seen from Figure 7(b) excessive metal and braze material flow has resulted from the reduction operation carried out to reduce the ~oint to parent metal gage. This excessive hammering typically results in unacceptable product processing, poor strip edge geometry, 9005-i~B
S~7 dog legs, splits, etc.
Having thus described the various aspects of and means which collld be utilized to carry out the process of the present invention, such a process will be described for joining a particular strip m~terial:
(1) Assuming the two strip segments to be jGined to be 3/4 in. X o.oo8 in. copper alloy C26000, a desired gap of 0.02 cm is established in accordance with the hereinabove calculation.
t2) 5ach strip segment is placed in the cutting device depicted in Figure 2. This involves placing each strip against guide walls 13 and flat on the upper surface of base elements 12 so that ends 10 project into the cutting zone of guillotine cutter 15. The str~p segments 4 and 5 are cut by lowering cutter 15 to produce matched cut ends 11.
(3) A 0.02 cm feeler gage (32) is selected and placed on shaft 34 of brazing fixture 20 and rotated midway into the gap between edges 30 of anvils 29.
(4) One strip segment is clamped in fixture 20 (Figure 3) on one side of feeler gage 32 using surface 28 of anvil 29 and machined faces 24 of alignment steps 22. The end of this strip should abut flush against feeler gage 32. Similarly, the second strip segment is clamped into place on the other side Or and butting against feeler gage 32. Clamping is carried out by rotating screws 27 till they secure the strip segments against surface 28 of an~vil 29.
(5) Feeler gage 32 is then rotated out of the joint area bet~een the two butting strip segments.
(6) A strip of brazing paste is applied across the gap bet~Jeen strip segment cut ends 11 being sure to get material ~005~
into the gap using a minimum of paste. (One preferred way o~
applying brazing paste in such a Joint would be ~ith the use of a syringe which results in a somewhat precise amount of paste being laid into the gap between the butted strip ends without the need for skilled labor or expensive devices.) (7) Flame from a torch (preferably har.d-held) is applied from the underside of the butting strip segments. The flame is played along the ~oint or braze line only long enough to assure complete melting of the braze material.
(8) The joined strip material is unclamped and flux from the brazed joint is wiped off. The ~oint is inspected for complete attachment. If incomplete oining has occurred, the st~ip may be reclamped after which a small amount of brazing paste can be applied to the open area and gently torched till melted. If the ~oint is bad, the entire section can be cut out and the process repeated.
(9) Both sides of the Joint are dressed with a flat file paying attention to remove only excess braze. To facilitate dressing, the joined coil section can be clamped to any s~itable dressing fixture. This operation serves to minimize the hammering needed to achieve parent metal thickness at the ~oint area.
~ 10) Hammer the ~oint area to gage by placing the strip ~oint on anvil 44 and activating hammer 40 with a foot pedal or the like (not shown) while at the same time moving the joint back and forth under striker head 42. Movement should be in the longitudinal direction of the coil, and hammering should preferably be carried out for a duration in the range of about 5-10 seconds. In hammering narrow width thin gage copper alloy strips, hammer air pressures in the range of about 900,-i~B
20-4Q psi have been found to ~e satisfactory. ~ny increase cr slight widening of the strip at the ~oint loca~ion can easily be eiiminated by edge filing of the joined strip.
Various means and methods can, of course, be utilized to carry out the various steps of the afore~entioned process of brazing s'rip segments end to end. For example, instead of placing a braze paste in the jo nt between the strip se~ments it would be possible to paint the strip segment ends with a suitable flux and then heat to brazing temperature. Upon attaining brazing temperature, a thin wire of brazing alloy can be touched to the joi~t in order to accomplish joining of the two strip segments. This particular method of applying braze material provides for very good control of the actual amount of braze material applied to the ~oint and helps to avoid the need for excessive hammerirg or metal reduction of the brazed joint.
In accordance with the concepts of the present invention~
pairs of brass strip 0. oo8 in. gage by 1/2 in. l~ide were placed end to end in a clamping fixture with a separation between the strips governed as disclosed herein by the linear coefficient of expansion of brass. Both ends of the strip segments were painted with a fluxing agent and heated with an oxy-acetylene torch. Upon attaining a suitable temperature, a thin wire of brazing alloy was touched to the joint in order to accomplish ~oining of the strip scgments. Tensile prop-erties of a group of such brazed ~oin's using several brazing alloy types are shown in Table I and compared with the tensile strength of the parent metal strip in bcth the as-rolled and the annealed conditionsO
~3~5Z;~B7 TABLE I
TENSILE PROPERTIES OF ~UTT BRAZED
0.008" GAGE ALLOY 260 BRASS STRIP
0.2% Ultimate Yield Tensile Elongation Strength Strength in 2"
_ Sample (ksi) (ksi)(Pct.) Notes A 24 48 6 Cu-Sn-P braze metal B 21 44 6 Cu-Sn-P braze metal C 23 49 7 Cu-~n-P braze metal D . 20 30 9 Ag-Cd-Cu-~n braze metal E 22 33 7 Ag-Cd-Cu-Zn braze metal F 24 37 4 Ag-Cu-P braze .
metal Alloy 260 103 109 2 Parent metal for extra spring above samples Alloy 260 22 45 . 40 Typical values annealed-Several additional brazed ~oints were made in accordance with the process utilized in production of the samples in Table I with the difference that the brazed joints ~ere purposefully made using excess braze metal and then hammered in order to reduce the joint thickness to that of the parent metal strip. Tensile properties of these additional samples are shown in Table II.
9005-i;lB
TABL~ II
TENSILE PROPERTIES ~F BUTT BRAZED AND HAi~MERED
TO RAGE 0.008" ALLOY 260 BRASS STRIP
0.2% Ultimate Vield Tensile Elongation Strength Strength in 2"
S.~mpIe (ksi) (ksi) ~ ) Notes G 27 52 9 Cu~Sn-P braze metal H 32 54 8 Cu-Sn-P braze metal I 29 53 6 5u-Sn-P braze metal J 47 55 8 Ag-Cd-Cu-Zn br~ze metal K -- 40 2.5 Ag-Cu-P braze metal It is apparent that there has ~een provided with this invention a novel process for economical, efficient~ and fast ~oining of narrow width thin gage strip segments which fully satisfy the objects, means, and advantages set forth herein before. While the invention has been described in combination with specific embodi~.ents thereof, it is evident that many alt.ernatives, modifications, and variations will be apparent to thcse skilled in the art in ligh~ of the foregoing description. Accordingly, it`is intended to embrace all such alternatives, modifications, and variations as fall wi~hin the spirit and broad scope of the appended claims.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for joining the trailing end of a first narrow width thin gage metal or alloy strip segment to the leading end of a second narrow width thin gage metal or alloy strip segment, said first and second strip segments being of approximately the same gage, and being of a width of about 3 in. or less and a gage of about 0.012 in. or less, comprising:
cutting off at least a portion of said leading and trailing ends to produce a trailing edge on said first strip segment and a leading edge on said second strip segment;
aligning said first and second strip segments so that said leading and trailing edges and at least a portion of said leading and trailing ends adjacent said leading and trailing edges are in a single plane, said leading and trailing edges matching in abutting relation and defining a joint therebetween;
applying a braze material to said joint;
applying heat to said joint so as to melt said braze material and join said first strip segment to said second strip segment; and simultaneously hammering said joint and at least a portion of said leading and trailing ends for a time and at a pressure such that portions of the parent metal or alloy of said first and second strip segments act as a shim; whereby said joint is reduced to approximately the same geometrical cross section as that of the parent metal or alloy of said first and second strip segments with a minimum of metal flow and deformation at said joint and said leading and trailing ends.
cutting off at least a portion of said leading and trailing ends to produce a trailing edge on said first strip segment and a leading edge on said second strip segment;
aligning said first and second strip segments so that said leading and trailing edges and at least a portion of said leading and trailing ends adjacent said leading and trailing edges are in a single plane, said leading and trailing edges matching in abutting relation and defining a joint therebetween;
applying a braze material to said joint;
applying heat to said joint so as to melt said braze material and join said first strip segment to said second strip segment; and simultaneously hammering said joint and at least a portion of said leading and trailing ends for a time and at a pressure such that portions of the parent metal or alloy of said first and second strip segments act as a shim; whereby said joint is reduced to approximately the same geometrical cross section as that of the parent metal or alloy of said first and second strip segments with a minimum of metal flow and deformation at said joint and said leading and trailing ends.
2. The process according to claim 1 wherein said step of hammering is carried out by actuating a hammer having a flat striker surface whose longitudinal extent along said first and second narrow width thin gage metal or alloy strip segments is at least approximately twice the width of said first and second strip segments.
3. The process according to claim 2 wherein said first and second narrow width thin gage metal or alloy strip segments comprise a copper alloy material of a width of about 1 in. or less, and wherein said time is of about 5 to 10 seconds-duration and said pressure is in the range of about 20-40 psi.
4. The process according to claim 1 including the step of removing excess braze material at said joint by dressing at least one side of said joint with a flat file after said step of applying heat and prior to said step of hammering.
5. The process according to claim 1 including pre-determining a gap value between said leading and trailing edges such that upon brazing of said first strip segment to said second strip segment overlap of said trailing end and said leading end is substantially absent; and securing said first and second strip segments during said aligning step so as to maintain the distance between said joint defining leading and trailing edges equal to said predetermined value.
6. A process for brazing the trailing end of a first narrow width thin gage metal or alloy strip segment to the leading end of a second narrow width thin gage metal or alloy strip segment, said first and second strip segments being of approximately the same gage and being of a width of about 3 in. or less and a gage of about 0.012 in. or less comprising:
cutting off at least a portion of said leading and trailing ends to produce a trailing edge on said first strip segment and a leading edge on said second strip segment;
aligning said first and second strip segments so that said leading and trailing edges and at least a portion of said leading and trailing ends adjacent said leading and trailing edges are in the same plane, said leading and trailing edges matching in abutting relation and defining a joint therebetween;
predetermining a gap value between said leading and trailing edges such that upon brazing of said first strip segment to said second strip segment overlap of said trailing end and said leading end is substantially absent;
securing said first and second strip segments during said aligning step so as to maintain the distance between said joint defining leading and trailing edges equal to said predetermined value;
applying a braze material to said joint; and applying heat to said joint so as to melt said braze material and join said first strip segment to said second strip segment.
cutting off at least a portion of said leading and trailing ends to produce a trailing edge on said first strip segment and a leading edge on said second strip segment;
aligning said first and second strip segments so that said leading and trailing edges and at least a portion of said leading and trailing ends adjacent said leading and trailing edges are in the same plane, said leading and trailing edges matching in abutting relation and defining a joint therebetween;
predetermining a gap value between said leading and trailing edges such that upon brazing of said first strip segment to said second strip segment overlap of said trailing end and said leading end is substantially absent;
securing said first and second strip segments during said aligning step so as to maintain the distance between said joint defining leading and trailing edges equal to said predetermined value;
applying a braze material to said joint; and applying heat to said joint so as to melt said braze material and join said first strip segment to said second strip segment.
7. The process according to claim 5 or 6 wherein said step of predetermining a gap value is carried out according to the formula gap value = ?t - ?o where ?t is the strip length at final temperature T and is determined according to the formula ?t = ?o (1 + ? T) ?o is the original strip length, and ? is the coefficient of thermal expansion of the strip segments.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379247A CA1152387A (en) | 1981-06-08 | 1981-06-08 | Process for joining narrow width thin gage metal or alloy strip |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379247A CA1152387A (en) | 1981-06-08 | 1981-06-08 | Process for joining narrow width thin gage metal or alloy strip |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1152387A true CA1152387A (en) | 1983-08-23 |
Family
ID=4120172
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000379247A Expired CA1152387A (en) | 1981-06-08 | 1981-06-08 | Process for joining narrow width thin gage metal or alloy strip |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1152387A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107185651A (en) * | 2017-07-17 | 2017-09-22 | 河南黎明重工科技股份有限公司 | Segmented thrower head and its application process for vertical shaft impact crusher rotor |
-
1981
- 1981-06-08 CA CA000379247A patent/CA1152387A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107185651A (en) * | 2017-07-17 | 2017-09-22 | 河南黎明重工科技股份有限公司 | Segmented thrower head and its application process for vertical shaft impact crusher rotor |
| CN107185651B (en) * | 2017-07-17 | 2024-03-15 | 河南黎明重工科技股份有限公司 | Sectional type material throwing head for rotor of vertical shaft impact crusher and application method thereof |
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