US3121943A

US3121943A - Production of fibers

Info

Publication number: US3121943A
Application number: US29492A
Authority: US
Inventors: Karl F Braeuninger; John A Blaskiewicz
Original assignee: Dow Chemical Co
Current assignee: Dow Chemical Co
Priority date: 1960-05-16
Filing date: 1960-05-16
Publication date: 1964-02-25
Anticipated expiration: 1981-02-25

Description

United States Patent 3,]l2l,43 PRGDUCTION 9F FEBERS Karl F. Braeuninger, Ferguson, and John A. lllasltiewicz,

St. Louis, Mo assignors to The Dow Chemical Company, Midland, Mich a corporation of Delaware Filed May 16, 1960, Ser. No. 29,492

. Claims. ((31. 29-412) This invention relates to a method and device for producing fibers of a light metal material whose shear strength is less than its tensile yield strength. It more particularly concerns a method and apparatus for fiberizing magnesium and its alloys.

The formation of fiberized magnesium and magnesiumbase alloys heretofore has been accomplished by extruding a mixture of particulated magnesium or a magnesiumbase alloy with cupric acetate or an organic blue dye as disclosed in US. Patents 2,657,746, and 2,701,636. Bundles of easily separable fibers wherein the individual fibers each are from about 0.001 to about 0.003 inch thick and of varying lengths result from the processes disclosed in these references. Such fibers exhibit a high tensile strength which makes them useful as fibrous fillers, as for example, for rubber reinforcement and the like. Additionally, these small diameter fibers have a large surface area to weight ratio which renders them especially useful in flashlight work, for example, or in other applications where the ability of the material to undergo rapid oxidation may advantageously be utilized.

There are, however, certain disadvantages inherent in the production of fibers by these known methods, e.g., (1) the fibers so-produced are of non-uniform length and cross section, (2) a residual film of the non-metallic mix ingredients or by-products thereof may be deposited on the fibers during the extrusion and (3) the processes are relatively expensive. Now, unexpectedly it has been found that by using the method of the present invention, fibers of substantially uniform cross section and length can be obtained by a unique metal shaving operation wherein magnesium or a magnesium-base alloy is pulled or pus-i ed through a shaving die whose cutting edge is not perpendicular to the direction of material travel.

It is a principal object of the present invention to provide a method for the production of fibers of substantially uniform cross-section and length. It is a further object of the invention to provide magnesium-base metal fibers which, as produced, are substantially free from undesirable surface coatings. It is another object of this invention to provide an inexpensive method of producing magnesium and magnesium-base alloy fibers. An additional object of the invention is to provide fibers of a preselected length and cross-section.

Numerous other objects and advantages of the inventlon of the present application will become apparent from the detailed specification presented hereinafter and by referring to the accompanying drawings, in which similar characters of reference represent corresponding parts in each of several views.

In the drawings:

FIGURE 1 is a plan of a shaving die assembly useful for producing fibers by the method of this invention showing drawstock and fibers.

FIGURE 2 is a sectional View taken along line 22 of FIGURE 1.

FIGURE 3 is a front elevation of the having die of FIGURE 1.

FEGURE 4 is an enlarged sectional view of the die orifice and die cavity of the shaving die of FIGURE 3 through the upper and lower long sides of this orifice.

FIGURE 5 is a top view of a drawstock material which has been scored at two places parallel to its longitudinal axis, i.e. along the length of the drawstoek.

3,121,943 Patented Feb. 25, 1964 ice FIGURE 6 is an end view of the scored drawstock of FIGURE 5.

The shaving die assembly 115 shown in the drawings and illustrative of a useful means of producing fibers is a modified conventional drawing die assembly and is composed of a rectangular prismatic die plate holder 16 having a cavity 17 and an attached die plate 18. The die plate 18 can be attached to the die plate holder 16 by a variety of convenient means, e.g. silver soldering, common screws, clamp, welding, fitted into a pocket in the die holder etc. as is known and apparent to one skilled in the art. The leading or forward face 19 of the die plate 18 is not made parallel to the face 20 of the die plate holder 16, but is at an angle 21 to it. The die plate 18 has a substantially rectangularly shaped die orifice 22 approximately centered in this plate. This orifice 22 has its long axis extending in a horizontal direction across the die plate 13. The two cutting edges 23 of this die orifice 22 are the foremost point of short lands 24 ground at an angle of to the face 19 of the die plate 18. The two short ends of the orifice 22 are not cutting edges but are rounded or otherwise shaped to keep the drawstock from skewing sideways during the drawing operation. The remaining length of the die cavity 25 behind the lands 24 is machined at an angle on all walls 26 so that this cavity widens outwardly as it passes through the die plate 18. The die plate and die holder assembly are placed so that the die cavity 25 opens into the cavity 17 of the die plate holder.

The angle 21 between the leading fac 19 of the die plate 13 and the face of the die plate holder 16 is from about 1 to about 10 with an angle of about 5 preferred.

The die orifice 22 shown in the illustrated embodiment is rectangular in shape. However, it is understood that this die orifice can be any of a variety of geometric shapes, e.g., trapezoidal, hexagonal, crescent, hemicircular and the like with the only limitations being (1) that there be two angular junctions of plane edges with a given cutting edge (2) that the shear angle between the cutting edges of the die orifice and the material being fiberized be from about 1 to about 10 and (3) the material of construction of the die cutting edge be of sufficient hardness and strength rating to satisfactorily cut the fibers from the drawstock.

In practicing the method of this invention, a shaving die assembly 15 having a substantially rectangular orifice 22; and an angle 21 of about 5 etween the die plate face 19 and die holder face 2% is mounted in a conventional drawbench apparatus (not shown) in the same position normally occupied by the drawing die of such apparatus. A light metal drawstock material 27 is selected for fiberizing whose shear strength is less than its tensile yield strength, for example; magnesium, wrought magnesium alloys such as the ASTM designated A231 (nominal composition 3 percent aluminum, 0.4 percent manganese, 1 percent zinc, balance magnesium), AZ63 (nominal composition 6 percent aluminum, 0.18 percent manganese, 3

ercent zinc, balance magnesium), A280 (nominal composition 8.5 percent aluminum, 0.18 percent manganese, 0.5 percent Zinc, balance magnesium), I-IM21A (nominal composition 0.6 percent manganese, 2 percent thorium, balance magnesium), HK31A (nominal composition 3 percent thorium, 0.7 percent Zirconium, balance magnesium), and ZK60A (nominal composition 5.5 percent zinc, 0.6 percent zirconium, balance magnesium) and the like, wrought aluminum alloys such as the Aluminum Association designated 5052 (nominal composition 2.2-2.8 per cent magnesium, 0.15-0.35 percent chromium, balance aluminum), 5056 (nominal composition 4.5-5.6 percent magnesium, 0.05-0.20 percent manganese, 0.05-0.20 percent chromium, balance aluminum), 6061 (nominal composition, 0.4-0.8 percent silicon, 0.15-0.40 percent copper, 0.08-12 percent magnesium, 0.150.35 percent chromium, balance aluminum), 6063 (nominal composition 0.20.6 percent silicon, 0.450.9 percent magnesium, balance aluminum) and the like and other materials of similar characteristics. The term magnesium alloys as used herein means metallic materials containing at least 75 percent magnesium, aluminum alloys as used herein means metallic materials containing at least 75 percent alumi num. The drawstoek 27 is formed to have the same rectangular shape as the die orifice 22 but will be thicker than the opening 28 between the cutting edges 2323 of the orifice 22 and will be somewhat narrower than the width of this orifice. To illustrate, with a rectangular orifice having a 0.100 inch opening between the two 3 inch long horizontal cutting edges, a magnesium or magnesiumbase drawstock of from about 0.102 to 0.120 inch thickness by about 2.90 inches or less in width will be utilized. The drawstock is pulled or pushed horizontally through the shaving die assembly in the same manner as is used in conventional drawing operations. The line of force applied to the material is normal to the vertical plane of the leading face 20 of the die plate holder 16 whereby a shear angle of is obtained. The substantially uniform fibers 29 released from the drawstock surface then may be collected.

Fibers resulting from the shaving operation are substantially uniformly square in cross section both along the length of each fiber as well as are consistently uniform from fiber to fiber. The cross section width of the fiber is a function of, and is essentially equal to, the depth of the shaving cut taken from the drawstoek surface in the drawing operation. The length of the fiber is determined by the width of the die orifice cutting edges and/or that of the material being shaved. Using the present method with those materials whose shear strength is less than their tensile strength, fibers are sheared from the width of the drawstock which fibers have their longest length substantially equal to the width of this drawstock; i.e. a large number of fibers are formed substantially parallel to the cutting edges of the die orifice as the drawstock is pulled through the die rather than one continuous foil or roll being removed from the length of the drawstock as might be expected.

The rate of drawing is not critical and is dependent only on the power and drawspeed of the drawbench facility utilized.

It is understood that in this method a multiplicity of such fiberizing die assemblies can be mounted in series each having the die plate mounted concentrically about the geometric centerline of the perimeter of the drawstock. Further the die orifice of each die plate is of the same shape but each succeeding die orifice has a thinner opening between the cutting edges than its preceding neighbor. If desired, one shaving die can be prepared which has infinite adjustments of the cutting edges in towards the centerline of the material being shaved so that after the drawstock has been passed through the die orifice and the finished fibers have been released from the surface the die orifice opening can be made thinner to accommodate a succeeding pass of the material through the same die. Alternatively, a die can be prepared having only one cutting edge. The material can be repeatedly passed through this die using a backing member, for example, shim stock, to compensate for the surface metal removal in each pass. These above listed procedures can be followed on a given drawstock material until the cross-sectional area of the material being shaved becomes too small to withstand the tensile forces required to move the stock through the tool.

Fibers of varying preselected lengths can be prepared by this method by scoring the drawstock parallel to the longitudinal axis of the material. The depth of the score mark, or serration, is at least equal to the thickness of the fiber producing cut and is made prior to pulling the material through the shaving die. Spaced serrations 4 across a drawstock will determine the ultimate length of the finished fiber.

Additionally, it will be recognized that the serrating and fiberizing operations of this method can be carried out either independently or simultaneously.

The following examples will illustrate further the present invention but are not meant to be construed as limiting it thereto.

Example 1 A rectangular orificed (0.124 inch thick by 5 inch wide) shaving die assembly having a die plate face-die holder face angle of about 5 was mounted into a conventional drawbench. The die orifice had cutting edges along both the top and bottom of its 5 inch width. Two 10 feet lengths of 0.064 inch thick by about 5 inches wide of ASTM designated AZ31 magnesium alloy sheet nominal composition 3 percent aluminum, 1 percent zinc and balance magnesium, were placed back to back and pulled through the shaving die in a horizontal direction and with the drawing force normal to the perpendicular face of the leading edge of the die plate holder thereby giving a shear angle of about 5. The rate of shaving was about feet per minute. Magnesium alloy fibers from both the top and bottom cutting edges, which were substantially 0.002 inch on a side and about 5 inches long formed at the entrance face of the die and were removed.

As a control, the die plate was positioned so that the leading face containing the cutting edges of the die orifice was parallel to the vertical faces of the die holder. A second set of similar AZ31 plates were pulled through the die orifice, the shear angle now being 0. The shavings produced were in the form of a continuous foil of about 0.002 inch thickness, and about 5 inches wide.

Example 2 A shaving die assembly similar to that used in Example 1, except that the leading face of the die plate made a shear angle of about 2 with the line of force applied to the drawstock, was mounted in the drawbench apparatus. The die orifice was rectangular and its opening measured 0.200 inch thick by 4 inches wide. A five foot length of magnesium drawstock 0.220 inch thick by about 4 inches wide was serrated to a depth of .01 inch along its length on both sides of the 4 inch stock using a conventional scoring tool. Three serrations were made, which divided the width of the stock into four substantially equal sections. The bar stock was then drawn through the shaving die at about feet per minute whereby substantially square uniform shavings of about .010 inch on a side and 1 inch in length were released from both sides of the stock by the cutting edge of the die orifice.

Example 3 A shaving die assembly and drawbench apparatus as in Example 1, except that the leading face of the die plate made a shear angle of about 8 with the line of force applied to the drawstock, was mounted in the drawbench apparatus. An AZ31 wrought magnesium alloy drawstock 12 feet long and 0.134 inch thick by about 5 inches wide was drawn through the shaving die at about feet per minute, and the .005 inch square by about 5 inches long fibers, which formed on both sides of the stock at the die face entrances, were removed.

Various modifications can be made in the present invention without departing from the spirit or scope thereof for it is understood that we limit ourselves only as defined in the appended claims.

We claim:

1. A method for producing fibers of a light metal material whose shear strength is less than its tensile yield strength which comprises;

(a) providing a shaving die assembly, said shaving die assembly having a rectangular die orifice, and a light metal material whose shear strength is less than its tensile strength, said light metal material having the same shape as said die orifice but being of a preselected thickness greater than the opening of said die orifice,

|(b) passing said light metal through said die orifice of said shaving die assembly at a shear angle between said die orifice and the line of force applied to said metal of from about 1 to about 10 thereby to remove as fibers by each cutting edge of said die orifice a pre-selected amount of from about 0.001 inch to about 0.010 inch of surface of said light metal, and

(c) shaving from said light metal material fibers having a length substantially the same as the width of said light metal material.

2. The method of prducing fibers as defined in claim 1 wherein the light metal is magnesium and alloys thereof and the shear angle between the die orifice and the line of force applied in passing the metal through said orifice is about 5.

3. The method of producing fibers as defined in claim 1 wherein a wrought aluminum alloy is utilized as fiberizing material.

4. A method :for producing fibers of magnesium and alloys thereof which comprises;

(a) providing a shaving die assembly mounted in a 5 drawbench apparatus, said shaving die assembly having a rectangular die orifice, and a drawstock material selected from the group consisting of magnesium and magnesium based alloys, said drawstock material having the same shape as said die orifice but of a preselected thickness greater than the opening of said die orifice,

(b) drawing said drawstock material through said die orifice at a shear angle between said die orifice and the line of force applied in drawing said metal through said orifice of from about 1 to about 10 thereby to remove as fibers by each cutting edge of said die orifice a preselected amount of from about 0.001 inch to about 0.010 inch of surface of said drawstock, and

(a) shaving from said drawstock material fibers having a length substantially the same as the width of said light metal material.

5. The method as defined in claim 4, and including the step of serrating the faces of the drawstock exposed to the cutting edges of the die orifice along the length of the longitudinal axis of said drawstock, these serrations being of substantially the same depth as the preselected depth of cut taken from said faces by said cutting edges of said die orifice thereby to prepare fibers the length of which are substantially the same as the width of the drawstock between said serrations.

References (fitted in the file of this patent UNITED STATES PATENTS 644,978 Greaser Mar. 6, 1900 1,009,688 Peterson et a1. Nov. 21, 1911 2,233,928 Weaver Mar. 4, 1941 2,323,700 Bailey July 6, 1943 2,694,400 Brock Nov. 16, 1954

Claims

1. A METHOD FOR PRODUCING FIBERS OF A LIGHT METAL MATERIAL WHOSE SHEAR STRENGTH IS LESS THAN ITS TENSILE YIELD STRENGTH WHICH COMPRISES; (A) PROVIDING A SHAVING DIE ASSEMBLY, SAID SHAVING DIE ASSEMBLY HAVING A RECTANGULAR DIE ORIFICE, AND A LIGHT METAL MATERIAL WHOSE SHEAR STRENGTH IS LESS THAN ITS TENSILE STRENGTH, SAID LIGHT METAL MATERIAL HAVING THE SAME SHAPE AS SAID DIE ORIFICE BUT BEING OF A PRESELECTED THICKNESS GREATER THAN THE OPENING OF SAID DIE ORIFICE, (B) PASSING SAID LIGHT METAL THROUGH SAID DIE ORIFICE OF SAID SHAVING DIE ASSEMBLY AT A SHEAR ANGLE BETWEEN SAID DIE ORIFICE AND THE LINE OF FORCE APPLIED TO SAID METAL OF FROM ABOUT 1* TO ABOUT 10* THEREBY TO REMOVE AS FIBERS BY EACH CUTTING EDGE OF SAID DIE ORIFICE A PRE-SELECTED AMOUNT OF FROM ABOUT 0.001 INCH TO ABOUT 0.010 INCH OF SURFACE OF SAID LIGHT METAL, AND (C) SHAVING FROM SAID LIGHT METAL MATERIAL FIBERS HAVING A LENGTH SUBSTANTIALLY THE SAME AS THE WIDTH OF SAID LIGHT METAL MATERIAL.