US2418990A

US2418990A - Combined chipping machine and impact mill

Info

Publication number: US2418990A
Application number: US520151A
Authority: US
Inventors: William M Sheldon
Original assignee: PULVERIZING MACHINERY Co
Current assignee: PULVERIZING MACHINERY Co
Priority date: 1944-01-29
Filing date: 1944-01-29
Publication date: 1947-04-15
Anticipated expiration: 1964-04-15

Description

Apri! 15, 1947,. w. M. SHELDON COMBINED CHIPPING MACHINE AND IMPACT MILL Filed Jan. 29, 1944 3 Sheets-Sheet 1 Lu'INgENTOR. MMW

April 15, 1947.

W. M. SHELDON COMBINED CHIPPING MACHINE AND IMPACT MILL Filed Jan. 29, 1944 3 Sheets-Sheet 2 April 15, 1947. w. M. SHELDON 2,418,990

COMBINED CHIPPING MACHINE AND IMPACT MILL Filed Jan. 29, 1944 s Sheets-Sheet s w ML S m \l m a m w L, Nu M Q RS \& 1| 9 MN NMR INV m A HTTORNEY Patented Apr. 15, 1947 COMBINED CHIPPING-MACHINE AND IMPACT MILL William M. Sheldon, Elizabeth, N. L,

assignor to Pulverizing Machinery Company, Summit, N. J a corporation of New Jersey Application January 29, 1944, Serial No. 520,151

. This invention relates to a machine for reducing certain metals and other materials which are more or less ductile and tough, More particularly, the invention relates to a combined chipping and chip breaking, or pulverizing, machine.

The invention has been made especially for the purpose of reducing solid magnesium to a condition suitable to be fed to and pulverized, or further pulverized, in a hammer mill or other suitable pulverizing mill, and machines according to the invention have been used for this purpose. The invention is, however, suitable for, and is intended to be used for, reducing other materials the toughness and ductility of which has made their pulverization on a commercial scale difiicult and expensive. Among such other materials are certain other metals such as aluminum and tin, and certain alloys, and certain plastics and synthetic materials of various kinds.

The present reducing mill comprises a chipping machine which cuts from the end of a billet transversely curved and irregularly curled chips in the form of ribbon-like strips which have closely spaced fractures, and a hammer mill or other chip breaker to which the chips pass directly from the chipping machine and by which the ribbonlike chips or strips ar broken up into relatively small pieces. Because of their closely spaced fractures. the broken, or roughl pulverized, chips are capable of being reduced to a very fine powder in a suitable pulverizin mill, but the material as it comes from the chipping machine in the form of relatively long thin curled ribbons or strips is of such looseness and in such volume compared to its weight that it is not only difficult to handle becau-e of the space it occupies but it is not suitable for feeding to the pulverizing mill. After being broken up into relatively small pieces by the chip breaker, however, the product is in the form of a comparatively dense mass of material which is readily fed to a pulverizing mill having the usual means for feeding the material into its mill chamber.

It was found that when the hammer mill serving as the'chip breaker is located directly below the tool head of the chipping machine so that the chips as they are produced fall directly into a feed hopper from which they pass into the mill chamber of the hammer mill, there is a more or less frequent clogging of the passage between the tool head of the chipping machine and the mill chamber of the chip breaker, which puts a practical limit on the speed at which the machine can be run, and, therefore, on its production capacity. One of the objects of the present invention is to 1 Claim. (Cl. 241-50) provide a, combined chipping and chip-breaking, or pulverizing, machine of increased production capacity by reason of avoidance of the limitation on its speed of operation due to clogging of the passageway between the cutter head of the chipping machine and the chip breaker. Other objects of the invention are to provide a machine of more compact and cheaper construction and one in which the chip breaker parts are more easily accessible for repair or other reason.

To these ends, in a machine according to the present invention, the rotary head which carries the cutting tool or tools projecting from the face thereof, and which is most desirably in the form 'of a fiat disc, carries also or has otherwise associated with it a plurality of radially extending beaters, and a casing is provided enclosing the cutter head and the heaters and having a. pcripheral discharge opening, the casing being most desirably of volute form with a tangential discharge opening, and a screen havingholes' or openings of suitable size is provided within casing extending about the heaters and spaced from the peripheral wall of the casing, the screen being most desirably a 360 screen extending completely around the head and beaters. The boaters carried by the cutter head serve as fan blades so that the rotating cutter head with its associated heaters acts as a centrifugal fan to draw air in through the central opening past the end of the billet, and also, as it may be, through a central opening about the cutter head spindle, and discharge it through the discharge opening of the casing. There is thus provided a combined chipping machine and impact mill by which as the chips are cut from the end of the billet they move outward and are struck and broken up by the heaters into pieces or particles of comparatively small size which then escape through the screen and are discharged from the casing.

A full understanding of the invention can best be given by a detailed description of a machine embodying the invention in the form new considered best, and such a description will nowbe given in connection with the accompanying drawings which illustrate such a machine. In said drawings:

Fig. 1 is a. side view partly in section of the machine:

Fig. 2 is a transverse sectional view taken on line 2-2 of Fig. 1 looking toward the left;

Fig. 3 is a similar view taken on-line 3-3 of Fig. 1 looking toward the right;

Fig. 4 is a side view on a larger scale of the cutter head and associated parts and showing the the casing surrounding the cutter head in section on line 44 of Fig. 5;

Fig. 5 is a sectional view taken on line 5-5 of Fig. 4;

Fig. 6 is a full size perspective view of one of the cutting tools shown in Fig. 5; and

Fig. 7 is a face view-of a tool head having six cutting tools.

Referring to the drawings, the operative part of the machine are mounted on a main body or frame [6 carried by legs H, the frame having parallel side walls and strengthening cross walls. The tool head I5 is carried by a spindle l6 journaled in bearings 11 and I8 mounted on pedestals l9 and 26 extending upward from the frame. The spindle is driven by a main motor 25 through a belt 26, a multiple V-belt as shown, which runscn a pulley on the motor shaft and on a pulley on the spindle. Thesepulleys may be proportioned to drive the spindle at a different speed, either lower orhigher, than the motorshaft as required or found most desirable according to the metal being chipped and the thickness of the chips and the speed of the motor. The motor is mounted on a base 30 carried by arms 3| and 32 extending upward from thepedestals l5 and 20. 'The metal or other solid material to be reduced is secured in a holder 35 mounted on a carriage 36. The material should be in the form of elongated pieces or bars which in the operation of the machine are fed slowly toward the tool head, and usually in the form of short round bars or billets, and the, term "billet as used herein is to'be understood as including any such short bars whether round or -of other cross-section and of a size and length suitable for the machine, and whether the material is "as cast or has been extruded or otherwise worked. The carriage 36 is mounted to slide on ways 31 which extend outward and upward from the side walls of the main frame and is held to the ways by adjustable rolls 38. The carriage is fed forward to the tool head end of the machine by a feed screw 40 which is driven by a small motor 4| through a sprocket chain 42. The carriage is connected to the feed screw by a split nut 43 mounted at'the rear end of the carriage, the nut being of any suitable construction whichcan be opened or closed, as by turning the hand lever 44. The nutis opened to permit the carriage to be moved to carry the billet holder toward or away fromthe tool head at will. When the nut is opened the carriage may be moved in any direction by turning a hand wheel 45 journaled ,in a bracket 46 extending downward from one side edge of the carriage. Fast on the shaft of wheel 45 is a pinion 41 which meshes with a gear 48 on a shaft which is also journaled in the bracket 46 and which carries a pinion 49 engaging a rack 50 on the under side of one of the ways 31.

The billet holder 35 in the particular embodiment of thelinvention illustrated is made to hold one billet. The billet is held endwise to the tool head and positioned concentrically with the axis of the spindle l6 and tool head. The billet holder comprises a frame 55 extending vertically upward from th carriage 36 and rigidly secured thereto, two

vise members

56 and 58, and a hydraulic jack 59 for applying downward pressure to the upper vise member 58'which is secured .to a cross piece .60 onwh'ich the hydraulic jack is seated and the en'dsofwhichextend into slideways formed by channels in the inner sides of the vertical side pieces of theframe- 55. The lower vise member is seated on thecarriage. The

lower member has a groove in its upper side and the upper member has a matching groove in its under side, the recessed billet seats formed by these grooves being of such depth that the vise members close on the billets while still otherwise somewhat separated from each other. Springs 6| are provided between the vise members for raising the upper member when the pressure of the hydraulic jack thereon is released to permit billets to be positioned in the vise and to release the billets for removal therefrom. The ends of the springs extend into sockets formed in the opposing faces of the vise members. The billet should be positioned in the tool holder with its forward end extending only so far forward from the vise members that it will be so rigidly presented to the cutting tools as to prevent shattering.

When the machine is in operation, the split nut 43 is closed on the feed screw 40 and the screw then gives the carriage slow forward feeding movement. Before the end of the billet has been cut back to the vise members, the feeding movement is stopped, preferably by the circuit to the feed motor 4| being opened by a limit switch 62 which is actuated by rod 63 extending from the carriage. The split nut is then opened and the carriage is moved backward by turning the hand wheel 45 to move the billet holder away from the tool head. The hydraulic jack is then operated to open the vise and the billet is moved forward a suitable distance through the vise and again secured by operation of the hydraulic jack. The carriage may then be moved forward to bring the front end of the billet quickly close to the tools, and the split nut is closed on the feed screw-to cause the carriage to be again fed slowly forward to feed the billet to the cutting tools, the motor circuit having been closed.

The tool head l5 in the machine shown, in which the billet holder 35 holds only a single billet, carries two cutting tools 65 set on diametrically opposite sides of the axis with their cutting edges in alignment. Each tool has a cutting edge of a length a little greater than half the radius of the face of the billet, that is, for a billet 4" in diameter each tool should have a cutting edge a little over an inch long, and one of the tools is mounted on the tool head with its cutting edge extending radially from the axis of rotation or just slightly across the axis, and the other, or outer, tool is mounted so that its inner edge will be at a distance from the axisjslightly less than the distance from the axis to the outer end of the inner tool and with its outer end a little more than 2" from the axis. The inner tool will thus sweep over a central zone of the end face of the billet the diameter of which is about or a little more than half the diameter of the billet, and the outer diametrically opposite tool' will sweep over an outer zone of the end face of the billet which overlaps slightly the central zone swept by the inner tool. .-The tool-head may, however, carry more than two cutting tools whether the billet holder holds only one billet or more than one, the cutting tools being positioned to sweep over slightly overlapping zones of the end face or faces of the billet. or billets. For example, the tool head may have six cutting tools arranged as shown by Fig."7'." The cutting tools may be of conventional form as shown in Fig. 6, in that each tool has a base portion 66 from which extends a somewhatreduced cutting end, or tool proper, 61 the end'face 68 of which, that is, the face, whichzfaces the billet, is beveled inward from the cutting edge. The tool has, however, a sinuate cutting ed e formed by shaping one of the faces of ,the tool adjacent the cutting edge with a plurality of closely adjacent furrows extending from the cutting edge. Most desirably, the end face 68 is a plane face and the furrows 69 are formed-in the front side face 10 of the tool, and the furrows are most desirably part circular in cross-section and each separated from the adjacent one by a narrow fillet, as shown in Fig. 6, A tool so formed sweeping at suitable speed over the end of a billet of magnesium or other material of suitable characteristics as to ductility and toughness which is being fed toward the plane of rotation of the tool at a very low rate with relation to the rate of rotation of the tool head will cut the metal or other material from the end of the billet in transversely curved and irregularly curled chips in the form of ribbon-like strips having closely spaced fractures extending bothleng'thwise and crosswise thereof,'all--or most of the fractures being through fractures.

The furrows in the front side face of the tool need not be of just the part-circular shape in cross-section as shown. Tools with this form of furrowed, or fluted, front side face have been used with excellent results and are nowconsidered-best, but good results, and possibly equally good results, may be obtained-with tools having a fluted face in which the furrows are not of this precise form. The face'may, for example, be sinuous or serpentine in cross-section, or with furrows which are more or less, but suitably, angular in cross-section. The machine may also be fitted with tools having a plane cutting edge. The tools may be secured in the front plate of the tool head in any suitable manner with their cutting edges extending radially of the spindle axis as stated. As shown in Fig. 5, each tool is held with its body portion between two jaws H of a tool holder extending from the plate.

The tool head I is formed by a metal disc of suitable thickness secured to a smaller disc or head on the end of the spindle l6, and it carries a plurality, four as shown, of beater blades 15 which may be of any suitable kind and connected in any suitable manner to the tool head disc. As shown, the blades are flat plates carried by arms which are pivotally connected to the disc, the plates extending beyond the periphery of the disc and being of a width considerably greater than the thickness of the disc so as to extend outward from each face of the disc and are tapered inward toward their inner ends to the thickness of the disc.

The cutter head and heaters are enclosed by a casing 80 the dimension of which in the direction of the spindle axis is somewhat greater than the width of the beaters and which is most desirably of volute form, having a tangential discharge passage 8| which in the machine shown extends vertically downward. The casing is formed of sheet metal or other suitable material, and is made up of a side plate 82 which is mounted on the pedestal 20, as by means of supports or brackets 83 of which one is shown in the drawings,

and an opposite side member comprising a fiat side plate 84 and a curved peripheral plate 85 which is extended to form opposite sides of the discharge passage 8|, the other two sides of the discharge passage being formed by extensions of the

plates

82 and 84. The plate 84 has an opening for the end of the billet large enough to provide an annular air inlet opening about the billet.

'6 The opening in plate 82'for the'spindle I8 is also large enough to provide an annular air inlet opening about the spindle.-

'A screen 90 having holes or openings of suitable size is mounted within the casing spaced from the peripheral wall of the casing and extending about the heaters, and is most desirably a 360 screen extending completely around the cutter head and heaters. The screen is positioned by annular ribs 91 secured to the side walls of the casing. A plurality, four as shown, of bars 92 extend across the screen against its inner surface at circumferentially spaced intervals. The bars are thin in the radial direction, preferably not much over /8" thick, so as not to necessitate too much space between the ends of the beaters and the screen. The edge of the bars toward which the beaters move is beveled. The bars serve as impact bodies against which the broken chips are hurled by the heaters and serve also to deflect back into the path of the beaters particles which are too large to pass out through the screen. The bars, as shown, extend between rings 93, the rings and bars forming a cage which fits within the screen so that it may he slid into and out of the screen.

The means provided for receiving the pulverized material discharged through the passage 8|, should be such that there will be no development of any considerable back pressure. A cyclone collector will serve, but a simple porous container, such as the bag 95, serves well. For discharging into such a bag, the discharge passage should most desirably he directed vertically downward, but, obviously, the discharge passage might extend in any desired direction to suit the particu lar receiving means used.

In the operation of the machine, the ribbonlike chips cut from the end of the slowly advancing billet by the rapidly revolving cutting tools are thrown outward into the zone of travel of the heaters by the centrifugal forces set up in the chips and are immediately broken up by impact of the heaters and by being hurled against the screen and the deflecting impact bars. The beaters act also as fan blades, inducing a powerful flow of air which enters through the central inlet openings and flows spirally through the space within the casing and out through the discharge passage 8!, by which the particles of the broken chips which are small enough to pass through the screen are carried through the screen and discharged through the passage 8| into the porous bag or whatever is provided for receiving them.

The size of the casing and the dimensions of the parts within the casing may vary considerably and will necessarily vary according to the diameter of the billets to be chipped or the number of billets held by the billet holder. In a machine such as shown, for chipping a concentrically positioned 4" billet, the outer edge of the heaters may be about 4" from the axis of the cutter head and the cutter head disc I5 should be of a diameter such that the heaters will extend three quarters of an inch or so beyond the periphery of the disc. The screen should be fairly close to the path of the outer edge of the heaters, most desirably somewhat less than a quarter of an inch therefrom, and should extend all the way across between the side walls of the casing. The peripheral wall of the casing, starting from one side of the discharge outlet close to the screen, recedes gradually from the screen so that where the tangential discharge outlet begins it may be as much as 2" or more from the screen. With the '7 partsso proportioned, the discharge outlet has een made4'fzsquare.

The machine may be operated at comparatively high speed without any trouble from cloggin y the ribbon-dike chips. A machine such as referred to in the preceding paragraph operating on magnesium has been operated with the cutter head driven at nearly 5000 R. P. M. and the billet fed at a rate to produce chips averaging about .00035" in average thickness, producing pulverized metal at the net rate of about 65 lbs. per hour. By net rate of production per hour is meant the production in-an hour of elapsed time part of which is taken in changing billets.

. Among the materials other than magnesium which have been successfully pulverized in the new machine are aluminum, castiron, cold rolled steel, roll forged stainless steel, hard and soft solder, and Lucite.

, What is claimed is:

- A machine for comminuting tough and ductile material, comprising a high-speed rotary cutter head, a plurality of cutting tools extending from the face of the cutter head, each tool being formed with a grooved cutting face, a billet holder for holding a billet of tough and ductile material in such position with relation to the axis of rotation of the cutter head that its entire end is swept by one or other of the tools to produce curls of the material forming the billet, means for feedingthe billet holder toward the cutter head, a plurality of beater blades rotating at high speed in a path around the cutter head and concentrically with respect thereto to break up the curls into fine chips, such blades being located in the path of such curlswhen thrown outwardly by the centrifugal-force resulting from the rotation of said head and the tools carried thereby, and a circular partition mounted concentrically with respect to said cutter head surrounding the beater blades, at least part of said partition being a screen to hold back the curls but pass the chips.

WILLIAM M. SHELDON REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS I Date Number Name 666,211 Shortt Jan. 15, 1901 679,046 De Camp July 23, 1901 1,039,441 Ray Sept. 24, 1912 187,303 Parmelee Feb. 13, 1877 1,758,702 Jacobson May 13, 1930 2,322,306 McLaren June 22, 1943 1,714,080 Craig May 21, 1929 384,763 Hayes June 19, 1888 500,986 Wilson July 4, 1893 2,368,870 Pagendarm Feb. 6, 1945 1,201,135 Barwell Oct. 10, 1916 2,248,640 Miller July 8, 1941 1,934,180 Fischer eta1 NOV. 7, 1933 FOREIGN PATENTS Number Country Date 54,772 Norse Jan. 7, 1935 45,164 Swedish Mar. 19, 1919 141,052 German May 5, 1903.