US2152842A - Metal attenuating process and apparatus - Google Patents

Description

M. E. EVANS FiledA ug. 23, 1934 METAL ATTENUATING PROCESS AND APPARATUS 2 Sheets-Sheet 1 ig /Ff l 3: 17 2 3. y v

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M. E, EVANS v METAL 'ATTENUATING PROCESS AND APPARATUS Filed Aug. 23, 1934 2 Sheets-Sheet 2 \IJLEDW J PU E IN VENTOR.

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UUSmO wz] cwmzou uumtqIv urammwufl JEME *JLlD lw JVFUZ ZUFJOE wwu tl Patented Apr. 4, 1939 METAIi A TTENUATING PROCESS AND APPARATUS Martin E. Evans, Pittsburgh, Pa.

Application August 23, 1934, Serial No. 741,100

35 Claims.

This invention relates to an attenuated metal article and to the production thereof, and particularly to a duplex metal attenuated article comprising a relatively high melting temperature metal and a relatively low melting temperature metal and the method of assembling these metals whereby new and useful metal combinations are attained and new and useful production methods and apparatus are added to the art of attenuating metals.

It is proposed to produce a base metal strip of relatively high melting temperature and of relatively high tensile strength and to control its surface condition suitably to provide traction or attachment to another metal or alloy of relatively lower melting temperature positioned longitudinally therewith.

In another aspect this invention relates to the working of a cast metal or congealed metal of small tensile strength with a metal work piece of relatively high tensile strength to impart pliability to the former.

In another aspect this invention relates to the production of an attenuated metal work piece adapted to receiving an addition alloyed thereto of a different analysis of metal and to the methods and apparatus specially adapted to this pur- DOSE.

in contact with the former.

The surface condition of the base metal strip is controlled by new steps in the art of producing the strip from billetts by heating, rolling and cold working. The surface of both metalsin a combination is controlled as to chemical composition and shape.

The work piece is usually cut up into lengths and transported to various points for further working. Reheating the work piece being necessary, preliminary thereto and for the protection therefrom the workpiece surface is freed from scale by sandblasting or other means and then coated at 200 or 300 C. with a'paint of 3 parts powdered aluminum, 5 parts resin and 5 parts petroleum tar at 200 to 350 C. Also the coating may be of 70 parts powdered aluminum, 23 parts sal ammoniac and 7 parts zinc. "In reheating to the rolling temperature, the base metal alloys with the paint forming a protection against surface deterioration. The subsequent working and attenuation of the alloy with the heated base give the alloy a degree of pliability. Obviously the attenuated base workpiece with such surface preparation is adapted to uniting with aluminum or zinc subsequently placed thereon in much less time than when the surface is free from such pre-- liminary alloy. Since the iron zinc alloy is brittle and becomes thick and stiff in proportion to the time of heating above the melting point of zinc, this control factor is important. Further, the penetration of the zinc by the iron and of the iron by the zinc is controlled to a degree by the character of the surface given the work piece in the mold and by subsequent working. The attenuated work piece may be given an alloyed coating at other points in the reducing process 7 than as outlined. Thus, after hot rolling, the workpiece may be cleaned and alloyed with zinc, the said alloy attaining a degree of pliability with further working. With a suitable alloy surface on the workpiece it is proposed to unite thereto a second metal such as aluminum or zinc in strip form or by congealing progressively. Economy in manufacture whereby handling and processing are reduced to a minimum requires that the metal be progressively congealed upon the support strip to provide the combination workpiece for further attenuation to-impart pliability to the congealed metal. However, aluminum powder or flakes mixed with zinc powder and heated in a retort to a temperature 20 to F. below the melting point of the zinc by virtue of the vapor pressure of the zinc forms an aluminum zinc alloy suitable for union with the alloy on the work piece. After formation of this powdered alloy the powdered zinc is separated largely therefrom mechanically, and the alloy powder with the work piece is drawn through a heated die and therein united to the work piece progressively by residual zinc powder in the alloy powder thereby forming the metal combination.

The characteristic mobility of the coating metal provided by the molten condition or the powdered condition of the metal is utilized to provide the distribution of the metal around the core strip.

"In the process of attenuating to a uniform cross section a duplex metal workpiece having a relatively low strength surface layer of metal over a relatively strong support strip, the surface layer has a tendency to spread and depart from the support strip under the pressure necessary to attenuate the support. strip. To overcome this tendency it is essential to provide means to restrain the movement of the low strength metal from more than its proportional movement with the support strip. To this end it is proposed to apply circumferential pressure to the low strength surface metal to restrain its lateral movement and to govern its longitudinal movement by engagement either frictional or bonded with the support strip. The circumferential restraint may be variously provided. Hydraulic pressure directly upon the workpiece is a preferred form;

engagement with an enveloping casing is another form in which instance the casing is close fitting and of a length that bonded metal cannot be sheared from the base strip but must travel with the strip through the casing and receive its proportionate reduction in a die and emerge from the die into a restraining casing and travel therein jointly with the base or support strip. Thus it is seen that the frictional or bonded engagement with the support strip should be of a length and intensity at the approach to the attenuating device suflicient to advance the weaker metal through the attenuating means and after the exit therefrom sumcient to restrain the weaker metal from longitudinal movement greater than that of the support strip. It is therefore evident,

that the restraint on the low strength material is complete circumferentially and longitudinally.

The apparatus chosen to effect the attenuation of the duplex strip comprises dies or rolls or a combination preferably mounted in a chamber adapted to withstand hydraulic pressure therein of an order up to 100,000 pounds per square inch. The passage of the workpiece through the chamber is effected by tension thereon, butit is intended that adaptations having driven rolls for duplex sheets are within the scope of this application, since the principle of restraint herein set forth is advantageously applicable thereto. The medium for applying the hydraulic pressure obviously may be of. a lubricating character, but since the pressure is on the approach and depart-ure sides of the die and rolls, the apparatus does not fall in the class of unbalancedpressure lubricating devices.v

The material worked upon involves preferably a support strip that has received the special operations previously outlined to provide a suitable surface condition which is progressively advanced with the molten duplex metal therearound through a congealing and working device for the duplex metal to an attenuatinghie or rolls. It is apparent that duplex metal in strip form may be advanced with the support strip and unattached thereto to a die or rolls.

Referring to the drawings,

Fig. 1 shows a sectional view of a die in a casing arranged to apply hydraulic pressure on strip material passing through the die.

Fig. 2 shows an end view of the entrance die and the casing arranged for receiving a rectangular shaped duplex metal strip section of Figure 1.

Fig. 3 shows an end view of an arrangement of rolls to replace the central die of Figure 1.

Figure 4 shows a sectional view of the rolls of Figure 3 with a duplex strip between the rolls and subjected to hydraulic pressure. I

Fig. 5 shows reducing rolls supported in backing rolls mounted in a pressure ring adapted to hydraulic pressure.

' Fig. 6 shows a sectional view ofrolls and mounting of Figure 5.

Fig. 7 shows another modification of the invention adapted to apply pressure upon strip material passing through the central die and to congeal (from a source not shown) metal upon a strip passing therethrough.

Fig. 8 shows an end view of a strip folded around a core strip.

Fig. 9 shows a schematic arrangement of sources of duplex metals and the agencies employed for their treatment.

Referring particularly to Fig. 9, the schematic arrangement shows a core strip of high strength strip is shown threaded through the congealing device and the reducing device to the drawing drum that provides traction.

Referring to Figure 1, within a cylindrical casing I is mounted a number of dies 2, 3 and 4 held in pressure rings 5, Sand I respectively, in alignment in a central cylindrical chamber 8 of the casing I. On the casing I a shoulder 9 at the exit end thereof and tapered passages I and II at the entrance end thereof accommodating a tapered key I2 with central eyelet I3 restrain the dies and pressure rings against axial movement within the central chamber 8. Between the respective pressure rings 5, 6, I, gaskets I4 and form seals for chambers I6 and I1 formed on either side of the central die 3 by longitudinal extension of the central die pressure ring 6. A gasket I8 on the shoulder 9 of the casing adds a further seal to exit chamber I! of the central die 3. In the pressure ring 6 of the central die 3 are provided passageways I9 and 20 leading from chambers I6 and I! and converging to a common conduit 2| screwed into the pressure ring 6 through a radial opening 22 in the casing I.

kept small, and the seals I4 and I5 may be of relatively low melting temperature metal adapted to unite under moderate heat with the walls forming a solid barrier. Around the central die 3 an electrical heating element 23 is provided in the central pressure ring 6 with a detachable connection 24 through a continuous passage 25 in the casing I and the central pressure ring 6. A thermocouple thermostat 26 extends through a continuous passage 21 in the casing I and the pressure ring 5 to contact the central die 3.

At the exit end of the casing I is positioned a flexible hollow metal ring 28 connected by a valve 29 and a pipe 30 to a dynamometer gage 40, a liquid filling the passages of the members outlined.

Extending through the registering dies 2, 3 and 4 is shown a cylindrical duplex metal strip comprising a core 32 and a covering 33 and having a large section 34 and a reduced section 35 in chambers I6 and I1 respectively.

The large section 34 of the duplex strip contacts with the tapered entrance 36 to the central die 3 and is progressively reduced therein while hydraulic pressure in the chamber I6 introduced through passages I9 and 2| forces the covering 33 against the core 32 and insures the proportionate reduction of each.

Referring to Figure 2, a' cross section of a rectangular strip 31 with thinner rectangular strips 38 and 39 on the respective sides thereof is shown entering a die 40 fitting into a pressure ring 4| positioned in the entrance of the central chamber 8 of the casing I.

Referring to Figures 3 and 4, an embodiment of ,the invention substituting rolls for dies is are held in bearings 44 and 45 respectively in the pressure ring 46 which is a counterpart of the shrinkage ring 6 and adapted to replace the latter in the chamber 3 in the casing l shown in Figure 1.

Referring to Figures 5 and 6, an embodiment of the invention is shown having a pair of reducing rolls 41 and 46 provided with backing rolls 49 and 50 respectively mounted in cages 5| and 52 respectively and positioried against shoulders 53 and'54 respectively in a pressure ring 65 adapted to fit in the mid portion of the central chamber 8 of the casing l. The cages 5| and 52 are held in position by liners 56 and 51 respectively against radial movement, and the distance between the rolls 4! and 48 is adjusted in accordance with the thickness of said liners. Changes in the thickness of the liners 56 and 51 change the position of the reduction rolls and the consequent reduction of the strips 53 between the rolls.

Referring to Figure 7, an embodiment of the invention is presented showing a die 69 mounted in a pressure ring 60 having chambers 6| and 62 in the extensions of said ring with screwed plugs 63 and 64 respectively serving to position sleeves 65 and 66 respectively which isolate the chambers 6| and 62 from the strip material 61 passing through the die 59. The entering chamber 6| of the die 59 has passages 68 and 69 thereto and likewise the exit chamber 62 has passages I0 and II thereto, said passages being adapted to accommodate the flow of fluid therein in accordance with operating conditions. Around. the die 53 an electrical heating element 12 is positioned in the pressure ring 63 detachably connected through a passage 13 in the pressure ring to a source of electricity.

Referring to Figure 8, a core of strip metal I4 has thereabout a close-fitting envelope of metal 15 with an alloy of the same or different metals along the line of contact I6 adapted under operative conditions hereafter set forth to bond the combination into a solid body.

Referring to the dual purpose device illustrated in Figure '7, a support strip 61 progressively adexit chamber 62 through openings I0 and 1| v lowers the temperature sufliciently to permit the coiling of the combined strip without damage for transport to the attenuating apparatus. The

dual purpose device of Figure 7 and the attenuating device such as shown in Figure 1 may be in tandem so that the strip material may be divided by the central attenuating die 3 and supplied with liquid under pressure through pipe 2| and passages I 3 and 26. Thechambers l6 and II are of a length and the liquid therein of a pressure to restrain the surface strip 33 from undue lateral motion or accumulation in the reducing die entrance 36 regardless of the bond between the support strip and the surface strip. With the combined strip. tapered in accord with the attenuating die entrance 36 and backed out therefrom so that the taper bears against the confined fluid when the fluid acts as a die and the taper pressing thereagainst maintains a pressure in the chamber l6. The heater coil 23 regulated in accord with the thermostat, of which the thermocouple 26 is shown, 26 may be adjusted to heat the die 3to a temperature effecting a bond between the support strip and the surface strip, the die and pressure ring preferably being made of tungsten carbide to resist heat and abrasion.

The before mentioned pressure source. of molten metal may be of a character employed in die casting adaptedto continuous operation and particularly to die casting of zinc and zinc alloys and aluminum to a thickness of as thin as one one-hundredth of an inch. Obviously a pressure source for such molten metal is not essential but preferable because of the density of the congealed product thereof.

The heater ring temperature adjusted in connection with the'dynamometer 3| recording the pressure by the casing l on the flexible tube 26 and transmitted by liquid through valve 29 and tube 36 in consequence of the tension on the support strip may give most favorable attenuating operation.

Instead of the liquid means in the pressure ring 6 for restraining the metal on the support strip from lateral movement, the device shown in Figure 7 with the tube 65 eliminated may be substituted in the casing I and aligned therein by a simple casing not shown to fit around the ring 63 and within the chamber 8 of the casing I. In that instance .the die 59 performs the attenuation andthe sleeves 65 and 66 restrain metal on the support strip against the lateral movement and accumulation in the die entrance. The inside passages of the sleeves 66 and 66 are of a length and relative diameter in contact withstrip therein adapted to insure the proportional flow of metal of the strip through the die 53. Where wide support strips are involved it is desirable in order to reduce friction and tension load to use rolls instead of dies and to this end the embodiment shown in Figures 2, 3 and 4 may be used advantageously. The support strip 31 grouped with outside strips 38 and 33 passes through an entrance die 46 in a pressure ring 4| mounted in a casing I, then through rolls 42 and 4,3 in a pressure chamber 46 and then through an exit I die the counterpart in reduced section of the entrance die shown in Figure 2. The two dies act as glands to retain the liquid within the pressure ring. The entranceqiie, the rolls and the exit die are mounted with registering orifices. The liquid pressure within the shrinkage ring 46 is exerted 'die, experiments show approximately 31% of the tension on the strip is due to friction and that if the strip is placed in tension approximating the elastic limit on both sides of the die and such tension maintained as relative motion between the die and strip is produced, the force against the die during attenuation is very materially reduced. Utilization of this principle in attenuating duplex metal strip very materially reduces the pressure of the attenuating die or rolls upon the metal and consequently reduces the tendency of the weaker metal to depart from proportionate reduction. Thus the congealing apparatus shown in Figure 7 operated on a duplex strip in tandem with the apparatus in Figure 1 employs the respective dies 59 and 2 as back tensioning means on the strip being attenuated by die 3. This tension reduces the pressure of the die 3 upon the covering 33 and the core 32, and the tendency of the covering metal 33 to depart from proportionateentrance with the core into die 3 is materially reduced. This important feature is equally exemplified in the application of rolls to reduction of duplex strip. Thus copper and aluminum or steel and aluminum or other combinations of metals not alloyed together may be reduced in cross section and separated, with the advantage of subjecting the weaker metal to pressing action in joint attenuation greater than the tensile strength of such weaker metal alone would provide,--an economy in. handlingand a superior product because of greater density thereof resulting. Thus Babbitt metal worked on a metal strip and separated therefrom is a new product.

To control the angle of contact between the rolls and material and to provide the necessary support bearing, the embodiment shown in Figures 5 and 6 provides attenuating rolls 4'! and 48' with backing rolls 49 and 50 respectively. The use of a confined liquid atmosphere around the various embodiments precludes the expansion of the workpiece beyond specified limits, limits which are prescribed by the uniformity of cross section v in the work piece.

Referring to Figure 7, the combination of die 59 and casings 65 and 66 is in effect a die having a confined approach and exit, thus providing the restrained atmosphere. The liquid substitute'in chambers l6 and ll of Fig. l for elements 65 and 66 is in effect a non-compressible atmosphere.

To roll or draw steel and lead or steel and aluminum or steel and zinc with more than a moderate dipped coating heretofore has not been commercially feasible because of the lack of restraint of the lower tensile strength metals mentioned. The new product from the steps outlined is a high tensile strength support strip and a lower strength surface strip jointly attenuated to a uniform cross sectio n. As an example of a new individual product Babbitt metal may be taken as congealed on a strip, attenuated with the strip to confer pliability thereon and then separated from the strip to be handled independently.

Further, the congealed metal around a high tensile strength strip may be used solely as a lubricant of a thickness to facilitate the passage of the strip through a greater number of dies than'any coating heretofore available. Thus, as shown in Figure 1, the outer metal 33 on the strip 32 may serve as a lubricant through an exceptional number of reductions in dies.

. Substantially, as set forth, the preparatory step in protecting the surface of -a relatively high strength metal against deleterious accumulations during heated attenuation as preparation for a work strip, accumulations that would tend to abrade'drawing dies and prevent alloying action and the product of these steps come within the scope of my invention.

Obviously this inventionis not limited to the specific embodiment of instrumentalities, but is capable of many variations and applications without departing from its spirit and scope as outlined in the following claims.

What is claimed, is: 1. In the process of attenuating a duplex metal strip .one metal of which as a tendency to depart from a uniform cross section in advance of the attenuating operation the steps consisting of subjecting the duplex metal strip to an attenuating operation and constraining said duplex metal to a'path uniform in cross section at the beginning of said attenuating operation whereby both metals are proportionately reduced in said at-- tenuating operation.

2. In duplex metal attenuating apparatus the combination of a reducing die having an angular portion adapted to effect the reduction of duplex metal strip by reason of said angularity, and an entrance member to said angular portion the inner surface of which is adapted to exert lateral restraint upon an area of duplex metal strip passing therethrough sufficient to assure proportionate metal entrance to said angular portion thereby assuring proportionate reduction of the duplex metal, and means for drawing said duplex strip through said die.

3. In duplex metal attenuating apparatus the combination of attenuating means having an angular portion adapted to effect the reduction of duplex metal strip therein by reason of pressure of said angular portion thereon, means to exert lateral pressure circumferentially upon said strip approaching and departing from said angular portion and within said angular portion but not in contact therewith whereby said strip is constrained to proportionate entrance, attenuation, and departure from said angular portion, and means for effecting the longitudinal movement of said duplex strip through said angular portion.

4. In the process of attenuating a duplex metal strip the steps consisting of progressive drawing said strip through a die and progressively maintaining a back tension somewhat below the elastic limit of the higher strength metal of said strip while maintaining said progression through said die whereby pressure by said die upon said strip is sufficiently lowered to promote proportionate reductionof the metals of said duplex strip in said die.

5. In the process of attenuating a duplex metal strip the steps consisting of progressively passing said strip .through attenuating means and progressively maintaining a back tension somewhat below the elastic limit of the higher strength metal of said strip while maintaining said progression through said attenuating means whereby pressure upon the strip by said attenuating means issufflciently lowered to promote proportionate reduction of the metals of said duplex strip by said attenuating means.

6. In the process of attenuating a duplex metal a strip, the steps consisting of progressively passing said strip through a die having a tapered entrance section, progressively maintaining a back tension somewhat below the elastic limit of said strip while maintaining said progression through said die, and maintaining a lateral pressure on said strip at the entry to the tapered section .of said die suflic'ient to insure the uniform entry into said die of the weaker of the duplex metals, thereby attenuating said strip to a uniformcross section. ,r i

7. In attenuating apparatus the combination of a wire drawing die, means to progressively pull a duplex metal strip through said die, means to progressively maintain a tension on the strip entering said die, and means to guide the metal strip uniformly into the die, whereby duplex metal of said strip is attenuated to a uniform cross section, said guide means being adapted to prevent bunching up of the duplex metal in front of said die thereby assuring uniform entry of said duplex strip into said die.

8. In attenuating apparatus wherein duplex metal is attenuated proportionately through the layers thereof, the combination of a pressure chamber, a reducing di'e mounted in the mid portion thereof, a pair of dies, one on each side of said reducing die with openings in registry with openings of said reducing die and mounted as glands in the ends of said pressure chamber, a capstan adapted to progressively draw a strip of duplex metal through said dies, and means to maintain hydraulic pressure in said chamber, said members being co-ordinated in operation so that strip material is progressively attenuated to uniform cross section.

9. In attenuating apparatus, the combination of a tubular member with a heater ring mid section of uniform diameter, on each side of said mid section an'end section, a mounting for said tubular member forming with said end sections a chamber around said tubing adapted to, cool said tubular member, an extension of said tubuceive therein molten metal around a strip extend- "ing therethrough, and means to draw a strip through said tubular member,vwhereby metal is progressively congealed around said strip in said 5 tube.

10. In combination with the inner surface of a reducing drawing die, tubular means adapted to communicate with a source of mobile coating ,metal and located in advance of the drawing por- 5 tion of said die, said means having an inner surface adapted to be closely associated with the periphery of a wire which is pulled through said die, any coating metal which. passes through said means in the direction of movement of said wire being sufliciently free to pass to said die, so that the movement of said wire through said die accomplishes the working of said coating metal in said die and the adhesion of said coating metal to said wire.

11. In combination with the inner surface of a heated reducing drawing die, tubular means adapted to communicate with a source of mobile coating metal and located in advance of the drawing portion of said die, said means having an inner surface adapted to be closely associated with the periphery of a wire which is pulled through said die, any coating metal which passes through said means in the direction of movement of said wire being sumciently free to pass to said die, so that the movement of said wire through said die accomplishes the working of said core metal in said die and the adhesion of said coating metal to said wire.

12. In combination with the inner surface of a drawing die, tubular means adapted to communilar member-beyond said casing adapted to recatc with a source of mobile coating metal and located in advance of the drawing portion of said die, said means having an inner surface adapted to be closely associated with the periphery ofa wire which is pulled through said die and to guide said coating metal entrained by said wire in the direction of movement of said wire. 50 that the movement of said wire through said die accomplishes the proportionate working ofsaid coating metal and said wire in said die and the adhesion of said coating metal to said wire.

13. In attenuating apparatus, the combination comprising a die with a tapered entrance adapted to accommodate a work piece extending therethroughwith a heavy coating of relatively softer, metal, means in advance of said tapered die entrance adapted to exert a lateral restraint upon coating metal on a work piece for a distance suiiicient to insure longitudinal movement of said coating metal with said work piece into said die, and means to advance said work piece in said die, whereby proportionate reduction of said work piece and its coating is obtained.

14. In attenuating apparatus, the combination comprising a die with a tapered entrance adapted to accommmodate a workpiece extending therethrough with a relatively heavy coating of softer metal, means in advance of said tapered die entrance adapted to exert a lateral restraint upon a work piece for a distance suflicient to insure longitudinalmovement of said coating metal with said work piece into said die, means to conand means to advance said workpiece through said congealing means and said die.

15. In attenuating apparatus, the combination comprising a casing, an exit reducing die and an entering positioning die in said casing in alignment, between said dies a chamber, a liquid in said chamber under pressure, the length of said chamber and the pressure of said liquid being so arranged as to exert a pressure upon a coating on a work strip possing tightly through said dies sufficient to insure uniform reduction in' section. of said coating and work strip as advanced in said reducing die, and means to advance the strip through said dies.

16. In attenuating apparatus, the combination comprising a casing, a pair of chambers in said casing, between said chambers a reducing die, in the outer. ends of said chambers gland-diesin alignment with said reducing die and adapted to fit a work piece extending through said dies, fluid in said chambers and adapted to prevent lateral movement of coating metal on the work piece moving through the reducing die, means to advance the work piece through said dies, and means for applying pressure to said fluid effective to force the coating against said work piece.

17, In duplex metal attenuating apparatus the combination of attenuating means having an angular portion adapted to efieot the reduction of duplex metal strip by reason of pressure of said angular portion thereon, means to exert lateralrestraint upon said strip approaching said angular portion whereby said strip is constrained to proportionatev entrance into said angular portion, means for effecting the longitudinal movement a of said strip through said angular portion and strip with a relatively soft circumscribing metal tending to bunch up at the entrance to a reducing die, the combination comprising a die, a mounting for said die, and an entrance tube to said die forming therewith a continuous passage into said die of a size adapted to hold said relatively soft metal of the strip against bunching at said die entrance.

19. In attenuating apparatus for duplex metal strip with a relatively soft circumscribing metal tending to bunch up at the entrance to a reducing die, the combination comprising a die, a mounting for said die, an entrance tube to said die forming therewith a continuous passage into said die of a size adapted to hold said relatively soft metal of the strip against bunching up at said die entrance, and means to adjust said tube in position to form said continuous passage with said die.

20. In attenuating apparatus for duplex metal strip with a relatively soft circumscribing metal tending to bunch up at the entrance to a reducing die, the combination comprising a die, a mounting for said die, an entrance tube to said die forming therewith a continuous passage into said die of a size adapted to hold said relatively soft metal of the strip against bunching up at said die entrance, the ratio between the diameter of said entrance tube and the exit diameter of said die regulating the percentage of reduction of said strip by said die.

21. In attenuating apparatus for duplex metal strip with a relatively soft circumscribing metal tending to bunch up at the entrance to a reducing die, the combination comprising a die, a mounting for said die, an entrance tube to said die forming therewith a continuous passage into said die of a size adapted to hold said relatively soft metal of the strip against bunching up at said die entrance, and means to adjust said tube in position to form said continuous passage with said die, said independent tube by its diameter and adjustment determining the size of duplex wire to be attenuated.

combination of a die, an entrance tube to said die adapted to prevent lateral movement of a.

duplex metal work strip drawn through said members, means to draw said duplex metal work strip through said members, and means accommodating the adjustment of said entrance tube relative to said die whereby the said tube may be replaced as wear may require in front of said die.

23. In the process of manufacturing an attenuated duplex metal strip comprising a core strip and a coating of softer metal thereon, the steps consisting of progressively forming a uniform cross section of coating metal on said core strip, reducing the said core and coating proportionately by drawing them through 'a reducing die,

.and maintaining the proportionate reduction of said core and coating by progressively guiding a 'uniform cross section of said core and coating into the said reducing die.

24. In the process of manufacturing an attenuated duplex strip comprising a core strip and a coating of softer metal-thereon, the steps consisting of progressively 'congealing a uniform cross section of coating metal on saidcore strip, reducing said core and coating metal proportionately by drawing them through a die, and maintaining the proportionate reduction of said core and coating by guiding a uniform section thereof into said reducing die.

22. In duplex metal attenuating apparatus, the

25. In the process of manufacturing an attenuated duplex metal strip comprising a core and a coating of softer metal thereon, the steps conmetals with temperature regulation thereof to effect the adhesion in permanent union of said metals.

26. In combination with the innersurface of a drawing die, means adapted to' communicate with a source of mobile coating metal located in advance of the drawing portion of said die, means to draw a wire through said communicating means and said die progressively, the inner surface of said communicating means being positioned to guide a uniform perpiheral shape of coating metal entrained by said wire into said die entrance, and means to regulate the temperature of said die, whereby the coating metal and the wire are progressively joined and worked in said die.

27. In combination with a drawing die an entrance guide adapted to exert lateral restraint for a distance upon coating metal being propelled by a core wire into said die suitable to assure a uniform supply of said coating metal to said die, means to supply coating metal to said guide, and means to exert a back tension upon said core wire whereby pressure upon said coating metal is sufficiently reduced so that said coating metal and said core strip in reduced section emerge from said die at the same lineal rate.

28. In combination with a drawing die an entrance guide of a length adapted to exert lateral restraint for a distance upon coating mate- 'rial being propelled by a core strip into the die suitable to assure a uniform supply of said coating material to said die, said guide preventing intermittent bunching up of said coating material adjacent said die thereby assuring regular entrance of said material to said die.

29. In combination with a drawing die an entrance guide of a length adapted to exert lateral ,restraint for a distance upon coating material being propelled by a core strip into said die suitable to assure auniform supply of said coating material to said die, said guide preventing intermittent bunching up of said coating material adjacent said die thereby assuring regular entrance of said material to said die, and pressure means supplying coating material to said guide.

30. In combination with a drawing die an entrance guide of a length adapted to exert lateral restraint for a distance upon mobile coating metal being propelled with a core strip into said die suitable to assure a uniform supply of said metal to said die, said guide preventing intermittent. bunching up of said coating material adjacent said die therebyassuring regular entrance of said material to said die.

31. In combination with a drawing die an entrance guide adopted to exert lateral restraint for a distance upon coating material being propelled by a strip into said die suitable to assure a uniform supply of said coating material to said die and an 'eidt guide adapted to exert lateral restraint for a distance upon coating material suitable to assure a uniform exit of said coating material from said die, and intermediate the outer ends of said guides means to heat treat said coating material, whereby said propelling core is uniformly coated and heat treated.

32. In combination with a drawingdie heated to a temperature adapted to treat: coating metal being propelled by a core strip into said die,an entrance guide adaptgd to keep coating metal from bunching up in front of said die and pressure means supplying coating metal to said guide.

33. In combination with mounted attenuating means such as a die abr'acpair oirolls, means adapted to prevent intermittent bimcbing before said mounted means of coating metal accompanying a core strip being propelled through said mounted means, whereby uniform attenuation of said coating metal and core strip is assured.

34. In combination with mounted attenuating means such as a die or a pair of rolls, means adapted to prevent intermittent bunching before said mounted means of coating metal accompanying a core strip being propelled through said mounted means, and means adapted to hold said coating material to said core strip upon their departure from said attenuating means, whereby said coating metal and core are uniformly attenuated.

35. In combination with mounted attenuatin means such as a die or a pair of rolls, means adapted to prevent intermittent bunching before said mounted means of coating material accompanying a core strip being propelled through said mounted means, and means adapted to hold said coating material to said core strip upon their departure from said attenuating means whereby said coating material and core are uniiormly attenuated.

MARTIN E. EVANS.

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