US3178770A - Variable orifice extruder die - Google Patents

Description

April 20, 1965 F..M.'wu |s VARIABLE ORIFICE EXTRUDER DIE 4 Sheets-Sheet 1 Filed Jan; 19, 1962 FIG. 1

INVENTOR FRANK I4. WILLIS ATTORNEY April 20, 1965 F. M. wu |s 3,

VARIABLE ORIFICE EXTRUDER DIE Filed Jan. 19, 1962 4 Sheets-Sheet 2 FIG.2 1 6 INVENTOR FRANK I. WILLIS BY- A ATTORNEY A ril 20, 1965 F. M. WILLIS 3,178, 70

VARIABLE ORIFICE EXTRUDER DIE Filed Jan. 19, 1962 4 Sheets-Sheet 3 FIG-5 INVENTOR FRANK M. WILLIS ATTORNEY April 20, 1965 F. M. WILLIS 3,178,770

VARIABLE ORIFICE EXTRUDER DIE Filed Jan. 19, 1962 4 Sheets-Sheet 4 R R O F. H? A02 4 "5 2 A2 L R s 0 L0 1. R J II A 5 rr. i I D L N L w R 5 VI N "M I H M a K N 2 NW G R s .r Cl RE w R R 0E 24 M PR (1 P 2 2 10 R m U L 6 m 0 o w m E N N O I m P c G um N. l 2 H.

SOURCE PNEUMATIC DIE POSITIONER ATTORNEY United States Patent 3,178,77t3 VARIABLE GREENE EXTRUDER DIE Frank M. Willis, Wenonah, Nd! assignor to E. H. du Pont de Nemours and Company, Wilmington, Del, a corporation of Delaware Filed Jan. 19, 1962, Ser. No. 167,269 flairne. (Ql. 1$-12) This invention is concerned with an extrusion die and more particularly with a controlled variable die extruder and a controlled variable die extruder system.

In many types of extrusion, the control of the cross section of the extruded material is of prime importance.

This is especially true in the production of extruded explosive cord wherein it is required that the cord shall have an exact Weight/ unit length. A problem encountered with the use of conventional fixed orifice dies is that various explosive formulations which are extruded through conventional dies grow in cross sectional area after they have passed through the die, making uniform cross sections impossible.

It has been determined that the final dimensions of the extruded explosive cord will vary depending upon (1) the extrusion temperature, (2) the extrusion pressure or rate, and (3) the physical characteristics of the explosive formulation being extruded. At present, for a given extrudable formulation and with fixed orifice dies, it is necessary to adjust either the extrusion temperature or pressure or both to obtain constant cross sectional dimensions. The extrusion rate is thus extremely slow and very impractical from a commercial standpoint.

As to the production of explosive cord having varying cross sectional diameter, no workable commercial means is known to the prior art for producing such tapered cord, save the tedious process of interchanging an infinite number of fixed orifice dies or the use of pulsation methods and devices.

It is, therefore, an object of the present invention to provide a variable orifice die.

Another object is to provide a variable orifice die capableof producing tapered extruded materials of varying cross sectional design.

A further object is to provide a controlled variable die extruder system.

A still further object is to provide means for producing extruded materials of desired cross sectional configuration and design.

Another object is to provide a device for the production of extruded explosive cord of controlled, tapering cross section.

Another object is to provide an apparatus for providing an extruded explosive cord of controlled cross sectional design and configuration.

These and other objects are accomplished by the instant invention which provides a variable extruder die and a variable extruder die system.

Generally, the extruder die comprises a support, twin cylinders rotatably mounted in rolling relationship on said support, at least one of said cylinders being provided with an orifice-defining, circumferentially extending groove of varying dimensions, drive means adapted to engage said cylinders, and means for feeding extrudable material communicating with said groove.

More particularly, this invention provides an extruder die comprising a housing, twin cylinders rotatably mounted in rolling relationship in said housing, at least one of said cylinders being provided with an orifice-defining, circumferentially extending groove of varying dimensions, said cylinders being provided intermediate their ends with circumferentially recessed spur gearing, die positioning drive means engaging said spur gearing, means for feeding extrudable material communicating with said groove, and an outlet from said groove through said housing.

It is given that the twin cylinders have spur gearing machined thereon and that this spur gearing be recessed. This, however, simply represents a preferred embodiment since the gearing need not be recessed and since such gearing might well be present near each extremity of each cylinder. In the latter case, at least one of each pair of geared ends of the twin cylinders, as they are positioned in the housing, would be of greater diameter than the largest diameter of that cylinder having it.

By the term orifice-defining is meant that the groove or grooves, as the case may be, in one, or both, cylinders, defines an opening of a desired cross section adapted to transform the extrudable material entering the die from its shapeless form to a form having a cross section conforming substantially to that defined by the groove or grooves. In the case where each cylinder is provided with a groove, each cylinder is positioned within the housing such as to permit one groove to complement the other and thus define the orifice.

This invention also provides a controlled die extruder system comprising (A) an extruder die comprising a housing, twin cylinders rotatably mounted in rolling engagement in said housing, at least one of said cylinders being provided with an orifice-defining circumterentially extending groove of varying dimensions, said cylinders being provided, intermediate their ends, with recessed, circumferential spur gearing, die positioning drive means engaging said spur gearing, means for feeding extrudable material communicating with said groove, and an outlet from said groove through said housing, (B) take-up means adapted to receive extruded material from said die, (C) gear means rotatably engaging said take-up means, (D) a camshaft engaging said gear means, said gear means being dapted to provide a high reduction ratio from said take-up means to said camshaft, (E) an orifice-controlling cam mounted on said camshaft, said cam being provided with a programed surface, (F) means for driving said gear and take-up means, (G) a precision regulator means connected to said die positioning drive means, (H) a camrider pivotally connected to said regulator means, said rider contacting the orifice-controlling surface of said cam and said rider being adapted to transmit variations therein to said regulator means, said regulator means being adapted to receive said transmission and to relay said transmission to said die positioning means for regulation of said extruder die orifice.

The cam used herein is machined, or so constructed, as to define the desired predetermined cord cross section with respect to the extruded length thereof, whether the cross section be of uniform or variable dimension, and to reflect this change on its outermost edge or along its circumference. The cam is read by the cam-rider and the reading is transmitted to the precision pressure regulator means.

T he above-described system is adapted to the production of varying diameter, i.e., tapered, extruded material, the

'AAof FIGURE 1. V V e FIGURES 3, 4 and show various cross sectional cuts .7 L 25 FIGURE 6 depicts asystem adapted for the production 7 of variable diameter extrudable material.

cross sectional diameter of which can be tapered accord ing to a predetermined pattern. Theabove system is V easily modified to provide a'control' adapted to maintain the programed cross section of the extruded material within given dimensional limits simply by inserting a dimension-sensing device in a position in the system where v in inspection of the extruded material after it has under-- gone maximum growth is provided. Such a device would then transmit dimensional variations which exceed presetx tolerances directly to a pneumatic, or to someother suitably operated controller device which matche'sthe meas- 15 to prevent the flow. of extrudable material into other parts of the housing 3. A cleaner follower 17 resiliently mounted in the housing (see FIGURE 3) is provided and so positioned in the housing 3, as to provide cleaning ,means for each of said grooves 14 and 15. To provide axial orientation of the cylinders 4 and 5 and of their complementary orifice-defining grooves 14 and 15, axial adjusting means 18 is mounted in the housing contiguous to the extremity of each cylinder to enable fine adjustment ured cord dimension with the desiredprogramed dimen-i sion and makes any correction necessary. The correction made by the controller transmits thecorrection to the 7 die positioning drive means to adjust 'the positioning of the die cylinders to compensate for any undesired 'variances in crossgsection...

, The instant invention will be more readily understood by reference to the accompanying drawings.

FIGURE 1 shows the variable extruderrdie connected to apneumatic positioner. V I 7 FIGURE 2 isa cross sectional cut'taken' alongline of the die depicted in FIGURE 2.

FIGURE ,7 shows various cross sections capable of and the other left-handed.

FIGURE lOfshows the die' cylinder bearings having opposed flat segments connected by a differential adjust ing screw 'for "adjusting and maintaining Zero clearance between said cylinders. v 1 Referring now to FIGURE is a out along line AA ofFIGURE' 1, metal breast plate 1 and metal butt plate 2'areseen'as defining the die block ,or housing -3 wherein two parallel holes of equal, bore designed to containtwincylinders 4 and 5' are machined so that each holeis madeto break through th'eyother ftangentially to provide no clearance between the 'cylinders 4 and Srotatably mountedjin the, housing 3. To be certain that the cylinders 4 and 5 cannot rub on the housing 3 the cylinders are provided" with journal'extremities'e contained'bytwosets of paired sleeve bearings 7 and 8, machined slightly leargerin" diameterithan the diameter of the cylinders .4' and 5, I To insure that the bearings inl'apair do not interfere with one another and that they are capable of'keeping the cylinders 4' and 5 rolling togetherfwith no clearance, flat segments, 9 ,(see

FIGURE 10) are provided on their periphery: The paired bearings 7 and '8 are then positioned within the housing 1 arid to FIGURE 2 which truded material 21.

of the axial alignment of the grooves and to reduce the axial motion of both cylinders to zero. An outlet, 31 in the housing 3 is provi ed to'allow an exit for the ex- FIGURE 3 is a out along line BB er FIGURE 2 and shows the circumferentially varying depth of the grooves Hand together with the positioning of cleaning followers 17 in the housing 3 and. abutting the cylinder grooves. V d V FIGURE-4, which is a cutalong line CC of FIGURE '2, shows the engagement of the double square rack 12 with'the spur gearing 11 of cylinders4and 5. 7 FIGURE 5, which is a cut along'line EE'. of FIGURE 3, shows the"positioning of the axial alignment screws 7 18' contiguous to the paired bearings 7 and 8. Each of the alignment means 18 consistsot a slotted eccentrically positioned metal head attached to a shanl; which fits in a hole drilled in breast-plate 1 in adirection vertical radially f'from the center lineof'the axis of the corresponding diecylinder, said shank being held in fixed position by set screw 34. V 1

FIGURE-6 is a schematic representation of a variable die extruder' system of. this invention. The die; assembly I in FIGURE 6 is attached to pneumatic die positioner ldwith doublesquare rack drive 12'engaging the spur' gearing 11 0f the cylinders 4 and 5 (see FIGURE 2'). A

source of material to be extruded and an extruderare positioned above thedie-housingfiand' said material is channeled from ,the'extruder to the die orifice by supply tube 29. The extruded material 21 .coming from the die orifice is led through a dimensionlsensing device which is positionedinthe system at a point beyond where ;rnaximum growth ofthe extruded'material 21 .has'taken pla'ce. H

traverse guide 32 and attachedjto rotating drum 22 which The extruded material 21jis then led through a is driven by a. tension motor (not.shown).- The axle 28 of the drum 22 engages re'duction'gear means from which a rotatabl'e'camshaft 24 extends. A cam 25 secured to .the camshaft 24 is provided'with a programed surface 'on its edge which is continuously engaged by cam-rider 27 attached to lever" 33 which is 'pivotally mountedrunder some tension a to the precision pressure regulator; A power pressure regulator, or power source, is connected 1 to the precision pressurefregulator and both of these 3 so that, as between each pair, these fiat segmentsi9' face each other. Each bearing is drilled and tapped 'through the flat segment 9 with lefitand right-handed threads, respectively, anda differential adjusting screw 10 with left and right-handed threadslon either end is 'fitted into, and joins, each pair of bearings. 'The differential adjusting screw'10 is used to adjust the center-tocenter distance between a given pair of bearings. I Thus,

the distance between the longitudinal surfaces of cylinders 4 and 5 may be easily adjusted to zero. Circumferentially,

are connected by flexible connections 29 to the pneumatic die positioner 13. A pneumatic controller is connected to the dimension sensing device through line 35 and is inserted in the system between the precision pressure regulator and the. pneumatic die positicner.

FIGURE 7 depicts someof he various cross sectional configurations of the extruded material which are possible.

Each isproduced by the corresponding groove or complementary grooves machined into the twin cylinders 4 and recessed spur gearing 11 is engaged by reciprocating double square rack drive 12 projecting from pneumatic, die positioner13'engages the spur gearing 11 on the cylinders to maintain rotational angular orientation of the cylinders. simultaneously in opposite directions; Gircumferentially 'extending grooves 14 and 15, of varying predetermined shape and dimensions, are'machined-in each of. the cylinders. O-rings' 16 are provided adjacent grooves 14 and Thus, cylinders 4 and 5 are adapted to rotate 5. Of course, many other cross sectional shapes are possibleand those depicted are only representative.

FIGURE 8 shows a cut away view of twin cylinders having unsymmetrical circumferentially extending shaping means 14 and 15 formingthe orifice 30. In this figure one cylinder carries a projecting tonguewhich is in axial alignment with a groove inits: oppositely paired cylinder togiveia grooved cross section to the extrusion (see FIGURE '7) .For a cylinder ofsuch, adesign a mating groove is machined in the housing formed by plates 1 V and 2, so that the tongue of the rotatable die forming cylinder does not engage the surface of the housing within the limits of rotation of said die forming cylinder.

FIGURE 9 shows a cut away view of twin cylinders, only one of which has provided thereon a circumferentially extending groove 14. Together they define the orifice 30.

FIGURE 10 shows a pair of sleeve bearings 7, each having a flat segment provided thereon and each provided with a threaded bore 23. Differential adjustment screw 10 provided with rightand left-handed threads is adapted to be received by each member of the paired bearings to adjust their center-to-center distance. Hexagonally faced surface 19 permits access of a wrench for adjusting screw 10.

In actual operation, the die assembly of FIGURE 1 may be a part of a system similar to that depicted in FIGURE 6. Material to be extruded is forced by a conventional extruding means such as a ram type or screw type extruder through the orifice defined by the complementary grooves 14 and in twin cylinders 4 and 5, and out through outlet 31 in the housing 3. The double square rack 12 extends through the housing and engages the spur gearing 11 of the cylinders 4 and 5 and is driven by the pneumatic positioner 13 which causes the cylinders to rotate in clockwise, counterclockwise directions respectively. The O-rings 16 positioned on either side and adjacent to the grooves 14 and 15 insure that material to be extruded is confined to a zone above the die orifice. The cleaning followers 17, which are optional, clear the respective grooves 14 and 15 when the cylinders 4 and 5 are made to rotate by die positioner 13. Signals transmitted from the precision pressure regulator to the pneumatic positioner 13 cause the pneumatic positioner 13 to move the reciprocating double square rack 12 which in turn causes rotation of the cylinders 4 and 5. This changes the dimensions of the orifice defined by orificeshaping rolls 4 and 5. The extruded material 21 is fed through a dimension sensing device which is positioned in the system at a point wherein maximum growth of the extruded material 21 has taken place. The dimension sensing device is preset to record the variations in the cross sectional diameter of the extruded material. These variations are transmitted to the pneumatic controller which matches the measured dimensions with the desired program dimension and makes the necessary correction in the signal transmitted to the pneumatic positioner 13 thereby maintaining desired dimensions of the cord. The extruded material, after passing through the dimension sensing device, is received by a drum or mandrel 22 which is rotated by a constant tension mechanical motor (not shown) which is adjustable and provides constant tension on the extruded material 21. As the material is extruded, each revolution of the mandrel or drum 2.2 provides an exact measure of the extruded length. The

drum or mandrel 22 is mounted on an axle 28 which is connected to a gear means, e.g., to a worm and Wheel gear. A camshaft 24 engaging the gear mechanism has, mounted thereon, a circular cam 25 having a predetermined set program cut into its circumference. As the mandrel or drum 22 rotates, the axle 28 is driven into the reduction gearing which has a reduction ratio such that a number of revolutions of the axle 28 are required to obtain one revolution of the camshaft 24 on which the circular cam 25 is mounted. The variations in the programed circumferential surface of the cam 25 are transmitted through a cam-rider 27 and lever arm 33 to a precision pressure regulator which adjusts the control pressure to the die I by transmitting signals to the pneumatic positioner 13 which in turn controls the positioning of cylinders 4 and 5 and thus the die orifice defined by grooves 14 and 15.

Thus, the cross sectional dimensions of the extruded cord are controlled according to a predetermined program machined into the control surface of the circular cam and are continuously adjusted within predetermined tolerances. A continuous extruded cord of substantially uniform cross section is produced, or optionally the extruded cord has a predetermined tapered cross section, the taper appearing periodically in a head-to-tail, tail-to-head relationship as the dies are rotated by rack drive 12 from a first position to a second position in one direction, and then are reversed to the first position in conformance with the preset program. The dimension sensing device operates simultaneously to maintain tolerance limits on the dimensions of the tapered cord. Both the dimension sensing device and the pneumatic controller can be omitted from the system and variable diameter extruded material will still be produced; however, in such a situation exact control of the fluctuations in the diameter of the extruded material will be missing. It is understood that while a pneumatic controller is preferred in this system, other controllers well known to the art may be substituted and may provide suitable replacements.

Among the many dimension sensing devices which could be inserted in the above-described system to provide the desired modification, three examples offering excellent results are:

(A) A pneumatic gage device which measures diameters or changes in diameter by the pressure drop of air flowing through orifices directed toward the measured diameter and the gage could be defined as the dimensional sensing device. It would be used to continuously sense exact diameter as the extruded cord passed through the device. Variances in the cord diameter would be sensed as pressure variations and would be converted to a die correction signal transmitted to a pneumatic controller.

(B) A pair of rollers mounted on a cantilever arm, the pivot of which is connected to a pneumatic position sensing device, could be adapted to having the extruded cord pass between the rollers, i.e., engaging both rollers, as it proceeded to the take-up means. Variations in diameter would then be transmitted to a pneumatic controller which, in turn, would correct the die positioning drive means accordingly.

(C) A television camera, using close-up lens attachments, could be positioned to project a large image of the diameter of the extruded cord on a television monitor screen. Variations from the desired diameter would be sensed as go or no go signals which would, through a controller, adjust the variable extruder die.

It is necessary that the leftand right-handed paired cylinders rotate together in an exact angular relationship so that the orifice defined by the grooves or groove and alternate die-forming structure will maintain the desired cross section configuration. Thus, the parallel holes of the housing which contain the cylinders are equally spaced in the housing. For proper operation, the cylinders must be positioned and held to provide no clearance between their contacting longitudinal periphery. To accomplish this, the parallel holes in the die housing are machined so that they are each breaking through the other tangentially. This is accomplished by keeping the parallel center-to-center distance exactly equal to the diameter of the cylinder while each bore of the parallel holes is several thousandths larger. To be certain that the cylinders do not rub on the housing, the sleeve bearings are machined slightly larger in diameter than the cylinders and slightly smaller than the diameter of the holes. Axial alignment of the die-forming surfaces is provided, as mentioned above, by axial alignment means mounted in the housing contiguous to the extremities of each cylinder. Clearance between the cylinders is controlled by the adjusting screw 19 inserted between each pair of sleeve bearings. The mating groove or other shaping surface machined in each of the twin cylinders extend circumferentially and are of varying dimensions. Preferably, they extend from substantially zero dimensions at zero degrees rotation to maximum dimensions at about of cylinder rotation. The depth of the circumferentially extending groove can vary from substantially zero to a depth substantially equal to the radius of the cylinder containing it. This depth will be governed to some extent by the composition of the cylinder since with a soft construction material in 'thecylinder, strength might be sacrificed providing a groove of such depth as would amount to one-half of the diameter of the cylinder.

The pneumatic positioner shown in FIGURE 1 is produced by the Cono-flow Corporation. It, is capable of V called for by the controlair signal. This device -represents a mechanism which is preferred, yet it is by no means limiting since other suitable devices couldbe sub-' stituted for'it to provide the same function.

For the proper operation of the die at normally high.

extrusion pressures (e.g., 1000 p.s.i.), it is necessary that The control air ac- .3; The device of claim 2 wherein each of said cylindersis provided with a complementary orifice-defining surface, and wherein said surfaces vary from substantially zero dimensions at of cylinder rotation to maximum "dimensioned about 180' of cylinder-rotation.

7 "4. The device of claim 3. wherein O-rings are mounted on, said cylindcr adjacent to and on either side of, said orifice-defining surfaces for limiting the flow of extrusion material. 1 i

'5. The. device of claim 4 wherein each cylinder is pro- ,vided'withjournal extremities; wherein four sleeve bearings are mounted in said housing, each of'said bearings being adapted to receive one' of said journal extremities,

the cylinders rotate together'with essentially no clearance 7 between their cylindrical surfaces. As mentioned earlier,

this is accomplished by machining the parallel holes in the die housing so that they each break through the other tangentially. The sleeve type bearing with differential or reducing valves as used hereimaresimply devices 0 I which take. suppliedair pressure (generally: 100 to 1 25 I p.s.i .ga.) and reduce it to the desired working limits;

The precision control pressure regulator ,is designedto 3 to psi.

'tremely sensitive and accurate. The power pressure regulater is designed for a wider range to 100 p.s.i.), and is a less accurate pressure regulator which supplies the power cylinder air pressure to the precisionpressure regulater and cushions air pressure. a

The va'riablediameter die and the extruder system are especially adapted to the extrusion of explosive cord; however, they would be operable in other than explosive service. For example, they might be used in extruding synthetic materials, i.e., nylon, etc.,' in the form of'tapered filaments. .A similar die which would be operated in an oscillating manner could varythe diameter from a preset lower limit to a preset upper limit. It would also bepossible to use a piercing mandrel fOrProducingtubings which would have tapering features of O.D., 1. D., with either dimension constant, or both changing. Such a piercing mandrel could be mechanically integrated to the roll adjustment orindependently controlled through its own mechanical adjusting system. i l

provided to regulate the center-to-centcr spacing between i said bearing pairs;

. 6. The 'deviceof claim 5 wherein axial alignment means are mounted on saidhousin'g, said axial alignmentmeans (T contacting'each extremity of said cylinders to provide operate .at the conventional pneumatic control range. of

Through this range, the regulator is exaxial alignment of said die-forming surfaces.

I *7. In an extrusion system providingcontrolled-cross sectional-dimensions; an extrusion die comprising a housing, twin cylinders "rotatably'mounte'd in rolling relationship insaidhousin'g, at least one of said cylinders being tially'recessed'spur gearing, drive 'meansengaging said spur gearing, meansifor feeding extrudable' material'com- :mu'nicating with said groove, and an outlet from said groove through said, housing.

The invention has been described in detail in the foregoing; however, it will b apparent to those skilled in the art that many variations are possible Without departing from the scope of the invention. The intent is,;therefore,

:to be limited only by the following claims.

What is claimed is: 1. Anextruder die comprising a support,

2. An extruder die comprising a housing, twin cylin-' v twin cylinders rotatably mounted'in rolling relationship in said sup- '60 port,'at'least one of said cylinders beingprovided with ders rotatably mounted in rolling relationship in said hous- 5 ing, at least'one ,of said cylinders being provided withan orifice-defining, circumferentially extending groove of varying dimensions, said cylinders bing'provided, inter mediate their ends, with circumferentially recessed spur gearing, drive means engaging said spur gearing, means for feeding extrudable materialcommunicating' with said 8. In an extrusion systemhavinga preset programing device andan automatic die positioner, a die comprising a liousifigytwin cylinders rotatably mounted in rolling extending groove of varying dimensions, said cylinders being provided,fintermediate their ends, with circumferentially' recessed spurgearing, drive means engaging, said spur-gearing, means for feeding extrudable material communicating 'with' said :groove, and an outlet from said groove through said housing. q

9. A controlled variable die 'extruder system comprismg i a a (A) An extruder die comprising a housing, twin cyliniders rotatably mounted in rolling relationship in said housing','- atleast one of said cylinders being provided "with an orifice-defining,'circumferentiallyfextending groove'of'varying dimensions, said cylinders being provided, intermediate their ends, with circumferentially recessed spur gearing, drive means engaging said'spur gearing, means for feeding extrudable material 'commu'nicating with said groove, and an outletfrom the said groove through said housing,

(B) Take-up means adapted to receive. extruded material from said .die', said take-up means being provided'with an axle therethrough,

(C) Gear mean engaging one extremity of said axle,

(D) 'A cams'haft engaging saidgear means, said gear means being adapted to provide a high reduction V ratio'from'said axle to'said camshaft,

(E) .A cam mounted on said camshaft, said cam being provided with a programed surface,

(F) Means for driving'said gear and said take-up means,' 4 J Y (G) A precision pressure regulatorconnected to said die positioning drive means;f

said rider contacting said cam surface and being adaptedto transmit variations in saidsurface to said 1 regulator means, said regulator means being adapted to receive, said transmissions and to relay said trans- 9 missions to said die positioning means for regulation of said die orifice. 10. The system of claim 9 wherein a transmission guide is inserted adjacent to said take-up means to position the extruded material on said take-up means.

References Cited by the Examiner UNITED STATES PATENTS 1,919,361 7/33 Farrington 18-12 -Wyler 149-2 Pearsall 149-2 Grimes 1812 Montross et a1. 189

Cheney et a1. 18-12 Smith 18-13 XR Lemelson 182 Halverson et a1. 1812 7/40 Fitzgerald 222 503 10 MICHAEL V. BRINDISI, Primary Examiner.

Claims (1)

1. AN EXTRUDER DIE COMPRISING A SUPPORT, TWIN CYLINDERS ROTATABLY MOUNTED IN ROLLING RELATIONSHIP IN SAID SUPPORT, AT LEAST ONE OF SAID CYLINDERS BEING PROVIDED WITH AN ORIFICE-DEFINING, CIRCUMFERENTIALLY EXTENDING GROOVE OF

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