US2858011A - Material propelling arrangement - Google Patents

Description

Oct. 28, 1958 E. A. WAHL MATERIAL PROPELLING ARRANGEMENT Filed 000. 18. 1954 United States Patent MATERIAL PROPELLING ARRANGEMENT Eugene A. Wahl, Glen Ridge, N. J. Application October 18, 1954, Serial No. 462,860 9 Claims. (Cl. 198-64) This invention relates to apparatus forthe propulsion of material between two points and more particularly to an improved construction of a rotatable auger useful in material extruding devices and in volumetric metering apparatus.

In my co-pending United States Patent application, Serial No. 416,794, filed March 17, 1954, now Patent No. 2,800,252, and entitled Powder-Feeding Apparatus, I disclose apparatus for continuously feeding powdered and granular materials into a medium or containerat a predetermined volumetric rate. material, such as powder, is carried by a storage hopper from which it is fed to a dispensing tube housing an auger rotated at a predetermined, constant rate of speed. The dispensing tube and anger are vibrated by suitable means. Under the simultaneous action of auger rotation and vibration the powder is discharged from an open end ofthe dispensing tube at a positive, predetermined, volumetric rate. Such apparatus has an operating accuracy and reliability factor far exceeding that possible with prior apparatus of this class.

The present invention is directed to an improved construction of the rotatable auger affording numerous advantages which will be explained hereinbelow.

An object of this invention is the provision of an improved auger adapted for use in propelling powdered or granular material in a direction along the auger axis.

An object of this invention is the provision of an anger for propelling material axially thereof, said auger comprising an open helix formed of a rigid material and having a substantially rectangular or square cross'section, means secured at one end of the helix whereby the helix may be rotated, a shaft fitting snugly into the other end of the helix, and means securing said shaft in fixed position whereby said shaft forms a bearing member about which the helix may rotate.

An object of this invention is the provision of apparatus for propelling material said apparatus comprising a tube having a discharge opening at one end and an intake opening intermediate the tube ends, a helical coil disposed within the tube said coil extending substantially the length of the tube, a shaft secured in fixed position at the discharge end of the tube and extending into one end of the helical coil, and a drive shaft secured to the other end of the helical coil and-extending out wardly of the tube.

An object of this invention is the provision of apparatus for dispensing powdered or granular material at a predetermined volumetric rate and comprising a storage hopper for the material, a tube having a discharge openingat one end and an intake opening adapted to receive material from the hopper, a helical coil disposed within the tube, a drive shaft secured to one end of the'helical coiland extending outwardly from the other end of the tube, means to rotate the drive shaftat a predetermined; constant rate, a shaft secured to the said one" end of the tube and extending into the other end of the' helical In such apparatus the 2,858,011 Patented Oct. 28, 1958 coil, and means imparting a controlled vibration to the tube, coil and rod assembly.

These and other objects and advantages will become apparent from the following description when taken with the accompanying drawings illustratingseveral embodiments of the invention. It will be understood the drawings are for purposes of description and are not to be construed as defining thescope or limits of the invention, reference being had for the latter purpose to the appended claims. In the drawings wherein like reference characters denote like parts in the several views:

Figure l is a fragmentary side elevation, with parts in section, showing a powder-feeder incorporatingan improved auger construction in accordance with this invention; and

Figure 2 is a side elevation, with parts in section, of an auger made in accordance with another embodiment of this invention.

Angers of the class contemplated by this invention are used in screw conveyors, extruding devices and volumetric powder-feeding apparatus. Heretofore, angers have been constructed as a flight helically wound around, and attached to, a central shaft'or simply. as a flight of suflicient thicknessand stiffness so as notto require the support of thecentral, attached shaft. A familiar form of the first type is the carpenters bit while the latter type is known as a ships auger or electricians bit. In both types, when used for the propulsion of a powdered, granulated or etc., material, the propulsion of the material along the lengthof the auger depends, in some measure, uponthe relative slip between the material and auger on the one hand and between the material and the walls of the tubular enclosure surroundingtheaug'er on the other hand; In certain applications, as where the auger runs full and the propelled material is subjected to pressure, as in a screw-typeextruder, the slip of the material on the auger must exceed the slip of the material on the tubular housing in order to achieve any propulsive effect from the auger. Ideally, the surrounding tube should hold the material stationary against the rotational drag of the rotating auger. An auger made in accordance with my invention approaches more closely the ideal condition in that there are two elements retarding rota tion of the material as it propels along the auger axis; namely, the conventional enclosing tube wall and the surface of a solid rod that extends into the flight but remains stationary at all times. This construction greatly enhances the pushing power of the auger, an important feature in extruding devicesand in certain types of screw conveyors. More specifically, my novel auger construction is especially advantageous for'use as a volumetric metering device, as in an apparatus for continuously feeding powdered, or granular materialsinto a medium at a predetermined, constant rate.

Reference is now made to Figure 1 wherein I show a powder-feeder incorporating my improved auger construction. Here I show a storage hopper 10 containing a quantity of a powdered material 11 and provided with a suitable cover 12. The hopper is supported on a suit able base, not shown, by means of a pair of upright sup ports 13 which straddle a rectangular receiving chamber, or'trough, 14 that issecured to, and supported solely by, a soft-iron frame 15 of an electromagnetic vibrator 16. Such vibrator is of conventional construction and includes a solenoid 17 carried by a soft-iron core 18 that is aligned with and normally spaced from a soft-iron plug 19"secured to the frame 15. As disclosed in detail in my referenced co-pending application, Serial No. 416,794, the electro-magnetic vibrator is securedto a relatively heavy base whereby energization of the solenoid by a pulsating current imparts a mechanical vibration to the tained within the trough.

3 trough 14 and all parts secured thereto or in physical contact therewith. It is here pointed out that the hopper may be completely isolated from the vibrator 16 and vibrated by a second electromagnetic vibrator 20 at an intensity appreciably less than that produced by the vibrator 16. Alternatively, the hopper may be only partially isolated from the vibrator 16 whereby such single vibrator will impart to the hopper vibrations of an intensity appreciably less than those applied to the components directly supported by the vibrator frame 15. Such lower level of vibration of the hopper results in a flow of the powder out of the hopper and into the trough, as indicated by the numeral 11a, whenever the hopper outlet, or discharge opening, is uncovered by the level of the powder in the trough. Whenever the level of the powder 11a, in the trough, rises to the hopper opening, the flow of the powder from the hopper effectively is stopped. Consequently, during operation of the device a substantially constant level of material is main- It will be apparent that the level of the material within the trough may be altered by adjusting the position of the hopper on the supports 13 as by means of screws 21 operating in the slots 22.

A tube 24 extends through the trough and may be secured thereto as by welding. The upper wall of the tube is cut away in the vicinity of the hopper opening to form an intake opening 25 and the lower wall of the left hand end of the tube is cut away to form a discharge opening 26. The auger unit consists of a helical coil C preferably formed of a metal ribbon having a square or rectangular cross section, the convolutions of the coil having a uniform outside diameter such that the coil fits snugly within the tube 24, as shown. Attention is here directed to the fact that the helical coil is open, that is, the convolutions thereof are not secured to a supporting shaft that extends throughout the coil length. At one end of the coil, several convolutions thereof are secured to a drive spindle 27, as by brazing or soldering, which spindle has an integral thrust collar 28 and a drive shaft 29. The drive shaft passes through a flanged bushing 30, preferably of the self-oiling, bronze class, and is connected to the output shaft 31 of a variable speed drive unit 32 by a pair of flexible couplings 33. A washer 34, disposed between the machined end of the tube 24 and the collar 28, serves as a thrust bearing and preferably is made of a material similar to the bushing 30. A metal end cap 35 serves to retain the bearings 30, 34 and the collar 28 in proper aligned and abutting relation, said end cap being secured to the tube 24 by a set screw 36'. It will be apparent that rotation of the shaft 31 imparts a rotation to the helical coil through the couplings 33 and the auger drive shaft 29 and that axial displacement of the coil is prevented by the collar 28 disposed between the thrust bearing 34 and the combination thrust and radial bearing 30.

The other end of the helical coil may extend to a point proximate to the discharge opening 26 in the tube 24. Extending into this end of the tube is a rod 40. This rod is secured in fixed position relative to the tube 24 by means of a set screw 41 that passes through. a threaded hole in the tube and through a radial hole in centering bushing 42. Alternatively, the bushing 42 may be attached to the rod 40, as by welding or soldering, and such unit may be secured to the tube by the set screw passing into a radial, threaded hole in the bushing, as is well known. In any case, the rod fits snugly within the convolutions of the helical coil and remains stationary at all times.

In this specific embodiment of the invention, the inner end of the rod 40 is pointed primarily to facilitate insert-- ing the rod into the end of the helical coil. Also, the inner end of the rod terminates substantially at the edge of the tube wall defining the intake opening 25, that is, this tube end extends only slightly into the reservoir fiom which the auger is filled. This feature, coupled with the constant vibration of the trough, tube and auger, assures a complete filling of the anger at that point in the reservoir where the coil convolutions enter the left side of the tube 24. Between this point and a point further back, that is, to the right, where the powder enters between the coil convolutions and where there is no inner rod, the auger is filled more or less but always in excess of the amount required to fill the space between adjacent coil convolutions at that portion of the auger contiguous to the rod 40. Therefore, at that point where the flight of the auger enters into the tube 24 the excess of powder is plowed back and upward as indicated by the pile-up of powder 111;. Two important advantages are realized by reason of such construction; namely,

(1) The space between the coil convolutions within the left hand portion of the tube is completely filled; and

(2) The degree of compacting of the powder at this point is constant.

Both of these factors are important in a powder-feeding machine in which the volumetric quantity of powder discharged per unit of time must be accurately maintained within say, a variation of better than 1 percent. As the auger rotates, the upward movement of the excess powder at the entrance to the tube assures the full weight of the powder (standing in the trough at this point) being effective to exert its full downward pressure on the powder entering into the auger tube. Without such action the powder at this point may bridge across the coil convolutions even though the auger and trough are vibrated whereupon there would be no compacting pressure exerted upon the powder entering the auger tube thereby cancelling out the advantage of maintaining a constant level of powder Within the trough, as has already been described.

It will now be apparent that in the illustrated auger construction there are two friction surfaces retarding rotation of the powder within the convolutions of the helical coil; namely, the inner wall of the tube 24 and the outer surface of the stationary rod 40. This increases to a maximum extent the pushing power of the auger and promotes a constant volumetric propulsion of the powder from the trough and out of the discharge opening 26.

A further important function of the stationary rod 40 is to prevent the outward flow of material from the reservoir, or trough, through the auger by the vibratory action employed in the feeder. This is particularly true in the case of granular materials. Still further, the inner rod allows the use of a much steeper helix than is practical with conventional augers and such steep incline tends further to prevent outward flow of the material by vibration alone. In short, my improved auger must rotate to provide a discharge of the material from the machine.

Attention is again directed to the fact that the auger is assembled into operative condition from both ends of the enclosing tube 24, that is, the helical coil and the attached drive shaft constitute one unit insertable into one end of the tube and held in a rotatable position by the end cap 35, and the rod 40 and bushing 42 insertable into the other end of the tube and held in fixed position by the set screw 41. Obviously,'other helical coils having a closer or wider spacing between convolutions can be utilized with a given enclosing tube 24 provided the outside and inside diameters of the convolutions are just slightly less than the inner diameter of the tube and the outer diameter of the fixed rod 40, respectively. In practice, it is quite simple to form the helical coil convolutions to precise diameters, as by a spring winding machine whereby the clearance between the helix and the inner tube wall on the one hand, and between the helix and the stationary rod on the other hand, is so small as to preclude the passage of even finely powdered material therebetween.

.In the event a given powder-feeding machine, or comparable device, is designed to accept angers of difierent diameters, the enclosing tube 24 would have an inside diameter suflicient to accept the auger having the largest outside diameter. The use of the smaller diameter angers would then require the use of separate, additional tubes to fill the space between the inner wall of the tube 24 and the particular helical coil. Alternatively, the auger and enclosing tube, shown in Figure 1, may be removably secured to the trough 14, whereby angers and associated tubes of any desired diameter may be used interchangeably in association with a given trough.

Figure 2 illustrates my improved auger construction as designed for use in a conveying or extruding machine as distinguished from a powder-feeding machine. Here the stationary rod 40' extends substantially the full length of the helical coil C stopping just short of the spindle 27'. In such applications, accuracy of metering is less important than the pushing power available to propel the material axially of the auger. By extending the rod 40 beyond the intake opening 25' additional pushing power is applied to the material in the region where the auger enters the left hand portion of the tube, that is, a maximum propelling force is applied to the material toward the discharge opening of the device.

While the drawings illustrate a helical coil having a substantially square cross-section it will be apparent that other sectional forms may be used to form the helix as, for example, round or triangular.

Having now described my invention in detail in accordance with the requirements of the patent statutes what I desire to protect by Letters Patent of the United States, is set forth in the following claims.

I claim:

1. A rotatable auger for propelling material axially thereof and comprising a tube having a discharge opening at one end and an intake opening intermediate the tube ends, a rod extending into the said one end of the tube and co-axially of the tube axis, means securing the rod in fixed position relative to the tube, a helical coil disposed axially within the tube with the end convolution of the coil snugly encircling the said rod, a drive shaft secured to the other end of the helical coil and extending outwardly from the other end of the tube, and means for deliberately and controllably vibrating the said coil during rotation.

2. The invention as recited in claim 1 wherein the said rod has a tapered end that terminates at the adjacent tube Wall defining the said intake opening.

3. The invention as recited in claim 1 wherein the said rod extends through the helical coil and throughout the axial extent of the said intake opening.

4. The invention as recited in claim 1 wherein the convolutions of the helical coil have a substantially square cross section.

5. In a powder-feeding machine of the type comprising a trough receiving powder from a storage hopper and means to dispense the powder from the trough at a pre determined volumetric rate, the combination comprising a tube extending through the trough said tube being provided with a discharge opening at one end and external of the trough and an intake opening communicating with the trough, a rod extending axially into the tube at the said one end, means securing the rod in fixed position relative to the tube, a helical coil disposed Within the tube said coil having one end snugly disposed over the said rod, a drive shaft secured to the other end of the coil and extending outwardly of the tube, means rotating the drive shaft at a constant speed, and means for deliberately and controllably vibrating the said coil during rotation.

6. The invention as recited in claim 5 wherein the inner end of the rod terminates substantially at the said intake opening of the tube.

7. The invention as recited in claim 6 wherein the said rod extends beyond the said intake opening of the tube.

8. The invention as recited in claim 5 in combination with means continuously vibrating the said tube and helical coil at a selected amplitude and frequency.

9. Apparatus for dispensing powdered material or the like comprising a container adapted to receive the material, a tubular member extending through and secured to the container said member having a discharge opening at one end external of the container and an intake opening communicating with the container and extending to a point proximate to an inner wall of the container; a helical coil axially disposed within the tubular member and having one end terminating near the said discharge opening; a rod extending axially into the tubular member at the discharge end thereof said rod also snugly extending into the said one end of the helical coil and terminating substantially near the proximate end of the intake opening; means securing the said rod in fixed position relative to the tubular member; a drive shaft secured to the other end of the helical coil and extending outwardly of the tubular member; means imparting vibration to the container; and means rotating the drive shaft at a predetermined constant speed.

References Cited in the file of this patent UNITED STATES PATENTS 690,841 Degenhard Jan. 7, 1902 2,323,864 Weyandt July 6, 1943 2,533,331 Skinner Dec. 12, 1950 2,563,496 Schmidt Aug. 7, 1951 FOREIGN PATENTS 558,768 Great Britain Jan. 19, 1944

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