US2795990A

US2795990A - Vibratory packing machine

Info

Publication number: US2795990A
Application number: US431336A
Authority: US
Inventors: Walter S Bohlman; Jr Jack D Hayes
Original assignee: Hercules Powder Co
Current assignee: Hercules Powder Co
Priority date: 1953-04-01
Filing date: 1954-05-21
Publication date: 1957-06-18
Anticipated expiration: 1974-06-18

Description

. June 18, 1957 w. s. BOHLMAN ETAL 2,795,990

VIBRATORY PACKING MACHINE Original Filed April 1, 1953 3 Sheets-Sheet 1 FIG.

INVENTORS WALTER S. 80 HLMAN BY JACK o. HAYES,J|:;

AGENT fime'is, 1957 W. S. BOHLMAN ET AL 3 Sheets-Sheet 2 Il'k WALTER S. BOHLMAN JACK D. HAYESJP.

INVENTORS M 9 RM AGENT June 38, 1957 w. s. BOHLMAN ET AL 2,795,990

VIBRATORY PACKING MACHINE Original Filed April 1, 1953 3 Sheets-Sheet 3 330 2' I; 304 303 ig; 307 3;; 22 i; 2| ,,.j

3 B2 FEG. 8

WALTER s. BOHLMAN JACK 0. HAYES):

INVENTORS BY W VIBRATORY PACKING MACHINE Walter S. Bohlman and Jack D. Hayes, Jr., Wilmington,

DeL, assignors to Hercules Powder Company, Wilmington, Del., a corporation of Delaware Original application April 1, 1953, Serial No. 346,115. and this application May 21, 1954, Serial No.

5 Claims. (CI. 86-20) This invention relates to a vibratory packing machine and more particularly to a vibratory packing machine especially adapted to the packing of large size explosive cartridges.

Packing by vibration is, in most cases, a very desirable and easy method of packaging loose, pulverulent materials. As long as it is only necessary to fill the container or to settle a predetermined weight of a particular material in a container, it has been found that vibration can usually be employed quite readily. Problems, of course, arise in the determination of the particular type of vibrator or the particular frequency of vibration which will give optimum performance and power economy with a given material. For example, it has been found with known vibratory packing equipment that a high-speed vibration does not lend itself to the packing of light, fiuify materials such as soap chips or aluminum leafing powder. With heavier materials it has been found that with known equipment high vibration frequency and greater force of each oscillation are necessary. The solution of these problems has been found in the designing of specific electric or fluid-actuated vibrators for particular applications at considerable expense. As a result, the actual use of vibratory packing has been relatively limited despite its overall attractiveness.

A problem of even greater magnitude has been encountered in attempting to pack an entire container to a uniform density. In the packing of most materials, a subsatntially uniform density is not important as long as a certain weight of the material is packed in a prescribed space. In such applications as the packing of explosive cartridges, however, it is very often essential that the entire cartridge be packed as near as possible to a uniform density. Further, it is equally important and desirable to pack successive cartridges to substantially the same density in order to obtain the same brisance and detonation velocity in successive cartridges of the same type. In the past, various types of vibratory packing machines employing various sources of vibration have been tried but to the present time no successful vibratory packer for explosive cartridges has ever been developed.

The first attempts to pack explosive cartridges by vibration were directed to the use of eccentric wheels and cam mechanisms which imparted a jolting motion to the shuttle holding the cartridge. It was also attempted to employ fluid-operated jolters similar to those used in founding machines in packing sand around molds. Both of these types were completely unsuccessful. The speed of vibration of each was relatively slow with the result that the bottom portion of the cartridge was of greatest density with a progressive diminution in density toward the top. Furthermore, neither type of device was satisfactory in packing explosives from the safety standpoint.

There are now available many types of high speed vibrators, but none of these have proved successful in explosive packers. Electric vibrators cannot be safely used because of the undesirability of having an electrical device in close proximity with explosive materials. Currently 2,795,990 Patented June 18, 1957 available fluid-actuated vibrators are characterized by vibration frequencies which are either too high or too low and are further unsatisfactory in that they do not combine a satisfactory power delivery with a satisfactory frequency. While their frequency can be varied by varying the pressure of the actuating medium, the changed speed of vibration is accompanied by a corresponding change in the power of the vibration.

As a result, the manufacturers of explosives are universally packing large size explosive cartridges by hand and are employing the well known Hall-type or Kimber-type packing machine for smaller cartridges. Packing with the Hall-type or Kimber-type machine is achieved by forcing explosive into the shells by means of reciprocable tamping rods. While leaving much to be desired in speed and uniformity of packing, these packers do an acceptable job with the smaller explosive cartridge. Consequently, most of the improvements in explosive packers have centered around this type of machine. However, the Hall-type machine has not been found feasible for cartridges of above two inches in diameter. A few Kimbertype machines have been rebuilt to pack cartridges up to five inches in diameter but have not been used to any great extent.

Now in accordance with the present invention, large size explosive cartridges may be quickly packed to a high and uniform density by vibration. Furthermore, in accordance with an additional embodiment of the vibratory packing machine of the invention, the power of the vibration and the vibration frequency may be independently and positively controlled to achieve the optimum packing efliciency for any given material at the lowest possible power expenditure.

Generally described, the present invention comprises a platen having rigidly attached thereto a pneumatic vibrator having a unidirectional power stroke upwardly and substantially parallel to the vertical axis of the platen, support means for the platen, and resilient mountings connecting the platen to its support means. According to various embodiments of the invention, the unit of a platen vibrator, resilient mountings and platen support means is, by suitable supporting members, mounted in combination with means for introducing the materials to be packed into the containers and means for raising and lowering the platen assembly with relationship thereto. According to an additional embodiment of the invention, means are provided for rigidly positioning the cartridges on the platen during the packing operation. According to still further embodiments of the invention, various pneumatic vibrators having a unidirectional power stroke are employed in conjunction with the platen and/ or the means for introducing the material into the containers.

In order to be operable as the shuttle vibrator in the vibratory packer of the invention, the vibrator must have a unidirectional power stroke. Preferably, the vibrators used in the invention will also be equipped with frequency control valves which will enable the operator to employ a vibration of the necessary force and frequency to give optimum packing efliciency. The preferred vibrator has in combination a casing forming a cylinder, at reciprocable piston disposed in the cylinder, exhaust ports located in the casing adjacent the opposite ends of the cylinder, an air inlet for pressurized air leading to one end of the cylinder, an air exit passage for air compressed by the piston leading from the opposite end of the cylinder, and a valve assembly; said valve assembly having in combination a first passageway therethrough which is in com air; a second passageway therethrough, one end of which is in communication with the air exit passage in the vibrator casing and the other end of which leads to the atmosphere, said second passageway having a check valve -at the end thereof which registers with the air exit passage and a metering means for air at the end thereof leading to the atmosphere; and slidable means disposed within the valve assembly which is movable in one direction to close the first passageway under the force exerted by the compressed air admitted to the second passageway through the check valve and'which is movable in the opposite direction to open the first passageway under the force exerted by the pressurized air when suflicient of the compressed air is released to the atmosphere through the metering means.

Ifa vibrator is employed which does not have a frequency control valve assembly, the vibrator preferred has in combination a casing forming a cylinder, a reciprocable piston mounted in the cylinder, an annulus formed inthe of; a passage extending longitudinally into the piston at a point which registers with the annulus in the cylinder wall when the piston is in the down position and which remains in communication with saidannulus during a substantial portion of" the pistons upward power stroke, a duct leading from said passage and opening into the cylinder from the bottom ofthe piston, and exhaust ports locatedin the casing adjacent the opposite ends of the cylinder, the distance between the exhaust ports being substantially equal to the length of the piston.

Also includedin the present invention is aprocess or system for packing pulverulent materials to a high and uniform density which comprises introducing the pulverulent material into a container, intermittently imparting a plurality of vertical upwardly applied impulses to the container and allowing the container to fall freely after each upwardly applied impulse. In one specific em bodiment of this process, the upward movement of. the container continues until the inertia supplied by the upward impulse is dissipated. Then the container is allowed to fall-freely until the next upward impulse is applied. This type of motion is obtained'with the apparatus of the invention when the containers. are not secured to the platen. In a further embodiment of this process, the upward motion of the container is gradually arrested and the free fall of the container is gradually decelerated prior to application of the next upward impulse. This type of motion is obtained with the apparatus of the invention when the containers are secured to the platen. In either type bf vibratory movement, there is no force other than gravityapplied during the downward travel of the container withthe result that packing accomplished: by the upwardforce applied is not undone by a reverselyapplied force.

' Having generallydescribed' the present invention, further andmore specific illustration is given with reference to the accompanying drawings wherein referencesymbols refer to like parts wherever they occur. In the drawings, Fig. 1 is an elevational plan viewof a vibratory packing machine in accordance withan embodiment ofthe invention. Fig. 2 is a side, part elevational, part sectionalview of the device of Fig. 1.- Fig. 3 is a plan view of the device of-Figs. l and 2 taken along line 3-3 of Fig. 2; Fig. 4 is -a part elevational, partsectional view of the device of Figs. 1, 2, and 3 taken along line 4-4 of Fig. 1 or Fig. 2. Fig. 5 is a plan view of an embodimentof the preferred platen vibrator. Fig. 6 is a part elevational, part sectional view of the vibrator of 'Fig. 5. Fig. 7 is a part elevational, part sectional view of "an alternate portion ofa vibrator valve assembly which may be substituted for the correspending portion of the valve assembly of the vibrator shown in Fig. 6., Fig. 8 is an elevationalendview of the vibrator of Fig. 6. Fig. 9 is a part elevational, part sectional-view of a vibrator whichmay beused for either the feed hopper or platen vibrator. Fig. 10 is a partelevational, part sectional view of an alternatehopper vibrator. Fig. 11 is a sectional view. of one of the resilient hopper mountings shown in Figs. 2 and 4.' Fig. 12 isa sectional view of one of the resilient platen mountings shown in Figs. 2 and 4. Fig. 13 is a sectional view of a feed hopper nipple shown in Fig. 4. Fig. 14 is a part sectional, part elevational view of the shuttle box positioning means shown in Fig. 4.

Referring now to the drawings, and more particularly to Figs. 14, a vibratory packing machine is shown in which a steel base plate 10 is secured by bolts 11 to a hardwood base 12 over a pit 13.1.inedwith concrete 14. Secured to the base plate 10-011 cast brass. bases 15 are three stanchions 16.formed from. heavy brass pipe. Cast brass caps 17 with vertically extending projections 18 are secured to the upper ends of the stanchions 16. Secured to the vertical projections 18' of the stanchion caps 17 is an aluminum hopper supporting frame 19. Attached to the hopper supporting frame 19- by brass cap screws 20 are hopper mounting plates 21 containing stepped bores 22. Fitted into the bores 22 are bronze casings 306 shown in detail in Fig. 11. A feedhopper 24 is connected to the feed hopper supporting frame 19 by studs. 25' and tube-form resilient mountings 26, which supporting assembly will be specifically described with reference to Fig. I l.

Disposed in the bottomof the feed hopper 24 is a bronze nipple plate 27 having nipples 28 extending downwardtherefrom. Each of the nipples 28 has a constriction 29 formed" immediately adjacent to its egress orifice as shown specifically in Fig. 13. A pneumatic vibrator 30 is secured to the hopper support frame 19 at an angle of about 20 below the horizontal. The vibrator 30 has a unidirectional power stroke inthe direction away from the hopper 24 and will be subsequently described in detail.

Disposed below the hopper assembly and over the base plate 10,is a rectangular aluminum platen 31 having rigidly attached'thereto and suspended therefrom a pneumatic vibrator 32,,various embodiments ofwhich will be specifically described hereinafter with reference to Figs. 5-9; The platen is secured to a platen support frame 33 by means of resilient mountings 3 4 which will be subsequently described with reference to Fig. 12 Disposed in one side of the platen 31 are rubber-capped positioning studs 35. Secured to the opposite side. of the platen 31 is a fluid-actuated gripping piston assembly 36 which will be subsequently described with reference to Fig. 14. Disposed on the platen 31. between the positioning studs 35 and gripping piston assembly 36 is a shuttle box 37. Theshuttle box 37 may. loosely hold the container to be loaded so as to allow. free vertical movement or may hold the containers rigidly and thus transmit the movement, of'the platen 3 1l directly to the, containers. An air delivery. pipe 38', which is connected to a power line (not shown) by arubber hose 39, supplies air to both the vibrator 32;andalso to the gripping piston assembly 36'by means ofja passage 40 in the platen as shown in Fig. 14.

A cylinder 41, maintained in position by guy rods 42, is disposed below theplaten assembly and extends downward into the pit 13. Within the cylinder 41 is mounted an elongated piston 43 which is actuated by a fluid medium admittedto the bottom of the cylinder through an inlet 44. The upper end of thepiston 43 is connected to the platen support frame 33-by means of bolts 45. The distance to which theplaten 31 can be raised by the piston 43 is determined by the setting of'the lock nuts 46 on guide rods 47. The guide rods 47 pass through bushings 48 disposed in orifices in the-base plate 10 and are connected to'the platensupport frame 33 midway between theresilient mountings 34. A. bellows 49 is secured to thetop of the basejplate 10 and the bottom of. the platen31 and prevents the material being packed or foreign matter from gaining access to the area enclosed therein.

In Figs. 5 6, and 8 is shown anembodiment of the preferred pneumatic vibrator having a unidirectional power strokefor use on the platen-as shown in Fig; 4.

In this preferred pneumatic vibrator a reciprocable piston is positioned in cylinder 51 formed by a casing 52. An air inlet 53 to the cylinder is located in one end of the casing 52 and

exahust ports

54 and 55 are positioned in the casing 52 at points equidistant from the ends of the cylinder. The distance between

exhaust ports

54 and 55 is such that during reciprocation one end of the piston begins to cover one port as the other end of the piston begins to uncover the other port. An additional air exit passage 56 from the cylinder 51 is situated in the casing 52 at the end opposite the air inlet port 53. A threaded plug 57 seals the bottom of the vibrator casing 52 and is of a size which enables insertion and withdrawal of the piston 50.

Aflixed to the side of the vibrator casing 52 by bolts 58 and sealing gasket 59 is a valve assembly having a casing 60 which forms a chamber 61 having two portions of different diameter. A recess 62 is located in the valve casing 60 and is in communication with the air exit passage 56 in the vibrator casing 52. A thread 63 is formed in valve casing 60 and extends into the chamber 61. A recess 64 is formed in the wall of casing 60 opposite the thread 63. A threaded spring-actuated check plug 65 threadedly engages the thread 63 with the base of the plug being retained in the recess 64. Check plug 65 has ports 66 and 67 located respectively in the upper and lower walls thereof. A valve 68 in check plug 65 allows the passage of compressed air through ports 66 and 67 into the chamber 61 from the recess 62 but prohibits a reverse flow. Above the check plug 65 the casing 60 is threaded to receive a threaded, adjustable exhaust valve 69. The valve 69 is adjusted by screw 70 and whenever the valve 69 is partially or fully open, chamber 61 is in communication with the atmosphere through the ports 66 and 67 in the check plug 65 and through the valve 69.

An air inlet 71 is located in the valve casing 60 near the closed end of the portion of chamber 61 having the smaller diameter. A passage 72, formed by a recess in the valve casing 60, is in communication with inlet port 53 in the vibrator casing 52. In communication with recess 72 is a passage 73 which opens into chamber 61 above the air inlet 71. Recess 74 in the casing 20 is a continuation of passage 73 across chamber 61 and into the casing 60. Also in communication with the recess 72 is a passage 75 which opens into the chamber 61 at a point above passage 73. Passage 76 is a continuation of passage 75 across chamber 61 and through casing 60 to the atmosphere.

A reciprocable piston 77 is disposed in slidable, substantially air-tight relationship in the portion of the valve chamber 61 having the smaller diameter. An annular groove 78 is cut in the piston 77 at a point which causes the groove 78 to register with passages 75 and 76 when, as shown, the piston is fully within the portion of the chamber having the smaller diameter. The distance to which the piston 77 may extend into this portion of the chamber is governed by the projection 79 of the threaded plug 80 disposed in the threaded opening 81 of the valve casing 60 at the base of the chamber 61.

A piston 82 is disposed in slidable, substantially airtight relationship below check plug 65 in the portion of the chamber having the greater diameter. The length of the piston 82 is such that when it is forced upward by the piston 77, the lower end of the piston 77 is able to clear the upper edge of passage 73 and recess 74, thus bringing air inlet 71 and passage 72 into communication. An annulus 83 is formed in the wall of chamber 61 at the point where the piston 82 meets the piston 77 when the piston 77 is resting on the projection 79 of the plug 80. An orifice 84 is provided in the valve casing 60 which leads from the annulus 83 to the atmosphere, thus allowing air to enter the large portion of the chamber 61 under the piston 82 when said piston is forced up- Ward by the piston 77. When the piston 82 returns to 6 the position shown in Fig. 6, the air admitted on the upstroke exhausts to the atmosphere.

Threaded sockets 85 are provided in the top of the vibrator casing 52 for securing the vibrator to the platen. Sockets 86 are provided in the plug 57 to receive a spanner for securing the plug 57 in place.

Referring particularly to Fig. 7, a portion of a valve assembly is shown which may be substituted for the corresponding portion of the valve assembly shown in Fig. 6. A chamber 61' is formed in a casing 60' and is closed at its lower portion by a threaded plug 80' having a projection 79'. An air inlet 71' is disposed in the casing 60' and opens into the chamber 61' at a point substantially opposite the projection 79' of the threaded plug 80. A recess 72 is formed in the casing 60'. A passage 73 leads from the recess 72' and opens into the chamber 61' at a point above the air inlet 71. The passage 73' is extendedacross the chamber 61' and extends a short distance into the opposite cylinder wall to form a recess 74'. A reciprocable cylindrical piston 87 is disposed in slidable, substantially air-tight relationship within the chamber 61'. It is at once apparent that the structure shown in Fig. 7 diflEers from the corresponding portion of the valve assembly shown in Fig. 6 only in that the exhaust passages 75 and 76 and annular groove 78 in the piston 77 of Fig. 6 have been omitted. The substitution of the portion of the valve assembly of Fig. 7 for the corresponding portion of the valve assembly of Fig. 6 results only in a slightly shorter power stroke of piston 50 since less air is able to escape from the cylinder 51 during the exhaust stroke of the piston 5'0. The structure shown in Fig. 6 is preferred although the increased air cushion below the piston inherent in the structure of Fig. 7 gives quieter operation.

The vibrator illustrated in Figs. 5, 6, and 8 operates as follows: Pressurized air is admitted through air inlet 71 of the valve assembly. Pistons 77 and 32 are forced upward by the pressure of the incoming air and the pressurized air flows through passage 73, passage 72, and air inlet 53 to cylinder 51 at the base of the vibrator piston 50. Vibrator piston 50 is forced upward and once the piston has closed exhaust port 55, the remaining air in the top of the cylinder 51 is compressed and forced through air exit passage 56, recess 62 and the check plug 65 into the chamber 61 above the piston 82. Due to the fact that the area of the end of the piston 82 is greater than the area of the end of piston 77, the air compressed in the valve assembly above piston 82 is able to force pistons 82 and 77 downward, whereupon the lower end of the piston 77 shuts off the flow of incoming air through air inlet 71. Depending upon the setting of the needle valve 69, a certain period of time is required for sufiicient of the pressure above the piston 82 to be bled to the atmosphere. Once sutficient of the pressure above the piston 82 has been released, the pressure of the incoming air through air inlet 71 is able to force the piston 77 upward once more and allow the pressurized air to fiow to the vibrator cylinder 51 at the base of the vibrator piston 50. While the piston 82 is depressed, however, the vibrator piston 50 falls due to the force of gravity and the expansion of the air cushion at the top of the cylinder 51. When the vibrator piston 50 falls, the air below the piston is exhausted through exhaust port 55 and backward through air inlet 53 to passage 72 from which it is bled to the atmosphere through passage 75, the annular groove 78 in the piston 77, and passage 76. Once the exhaust port has been covered by the falling vibrator piston 50, the passage provided through the valve assembly is the only means of exhaust from the lower part of the vibrator cylinder 51.

It is at once apparent that the frequency of the vibrator described can be altered at will merely by adjusting needle valve 69 to vary the rate at which the air is released to the atmosphere from above piston 82. This variation in vibration frequency is achieved without any 7 diminution whatsoever in the force of the individual power stroke of the vibrator piston 50. Consequently; itis possible to var-y both the force of 'theindividualpower stroke andthe vibration frequency to suit the demands of the particular material being packed with the vibratory packing machine of this invention.

In Fig. 9 is'shown a-partsectional, part elevational view of a pneumatic vibrator having; a unidirectionali power stroke which may be easily converted for use-as aplaten vibrator or as the hopper-vibrator in the vibratory packing machine inaccordance with the invention. A reci rocable piston 90 is disposed in a cylinder 89- formed by a casing 91 The lower portion of thecasing 91 is formed by a cylinder head 92 which is held in air-tight relationship to the remainder of the casing 91 by a gasket 93 and studs 94. An annulus 95 is formed in the wall ofthe cylinder at apoint equidistant from the ends thereof. Passages 96 and-'97 are formed in the outer periphery ofpiston 90 at points which register with the center of annulus 95 when the piston 90 is alternately at the end. of either its exhaust or power stroke. A duct 98' leads from the passage 96 through the piston 90- to the bottom of piston 90. A duct 99 leads from the passage 97 through the piston 90 to the topof the piston 90. Duct 98 is plugged with a threaded plug 100; Exhaust ports 1-01 and 102 are disposed in the wall of the cylinder at-a point equidistant from the ends ofthe cylinder. The distance-between the exhaust ports 101 and 102 is such that during reciprocation one end of the piston-begins to cover one exhaust port just as the-opposite end of the piston begins-to uncover the other xhaust port. A threaded air inlet-port 103 is'disposed in one side of the casing 91 and-leads into the annulus 95. A threaded air-inlet port 104'is-disposed in the-opposite side of the casing 91 and also leads into the annulus 95. A threaded plug- 105 is disposed in the air inlet port 104. A stepped aperture 106 is formed in the cylinder head 92 and disposed thereinis a length of pipe 107 havinga flange which registers with the shoulder of the aperture 106. A reciprocable piston 109 is mounted in the boreof the pipe 107 in slidable, substantially air-tight relationship. The lower portion of the bore of the pipe 107 is threaded to receive an air hose 110: from a compressed air line or a sealing plug (not shown). Thebore-of'thepipe' 107 is constricted and forms a shoulder 111 which limits the downward movement of the-pist-on109-toits own length;

Passages-112 and114, sealedby-threaded plugs 113 and 115-, respectively,- are provided for the attachment of the vibration frequency control valve assembly similar to that shown in- Fig. 6; Toadapt. the control valve assembly shown in-Fig; 6lto'the vibrator of Fig. 9, it is only necessary to extend the recess 72upwardly inthe direction of recess 62 for a'distance sufficient to bring recess 72 intocommunication with air-inlet 103' when recess 62 is in communication with either of-passages112 and 114, respectively. Suitable threaded holes must be formed in casing 91' toaccommodate bolts 58. When fitted with the control valveassembly, the frequency of the vibrator of Fig. 9 may be positively controlled while maintaining a stroke ofuniform power.

As shown thevibrator of Fig. 9 is adapted for use as the hopper vibrator and operates as follows: Compressed air is admitted'through hose 110 to the bore of the pipe-107 below-thepiston 109 at a pressure necessary to raise the piston 109 and thus force the piston 90'upward. The rising-piston 90 causes the air to exhaust through the exhaustport 102. Once the piston 90 has closed the exhaust port 102, the air in the end of the cylinder is compressed to form a cushion which prevents piston-90=from strikingthe top of thecylinder. When the piston90-has-been raised to the up position, compressed-air is admitted through air inlet 103'w hich flows through the annulus-95, passage 97; and theduct 99 to the cylinder above the-piston 90: The piston-90 is" 8 forceddownward to the bottom of the cylinder; As the passage 97- in the piston passes the lower edge of the annulus theair to the topof the cylinder 89 is shut 0th andas the upper edge of'the piston 90=uncovers the 7 exhaust port 102; the air above the piston begins to exhaust to the atmosphere.- Meanwhile as the piston 90 is forced downward; the air below the piston is exhausted throughexhaust port 101, and the piston 109 is forced downward intothepipe 107 by the base of the piston 90: The piston 109 in the bore of pipe 107 is prevented front entering pipe 107 beyond its own'length by the shoulder 1-11. A cushion of air is also formed on-the lower part of the-piston which prevents the piston from striking the cylinder head 92. Due to the cushions of air formed at the ends of the cylinder during the exhaust stroke and the power-stroke of the piston 90, the

vibratorillustrated ischaracterized by a relative quietness in operation.

To adapt the vibrator asshown in Fig. 9 for use as the shuttle vibrator in the vibratory packing machine of the invention, the air hose 110. is detached from the pipe 107 and replaced by a suitable sealing plug. The plug-105is removed from air inlet 104 and is placed in air inlet 103; The hose from the air lineis then connected'toair inlet-104. The plug -is removed from the duct 98 and placed-in theduct 99; When compressed air is now admittedthrough air inlet 104, the operation of the vibrator: is identical to-that shown in Fig. 9 except-that the-power stroke of the piston 90 is up instead of down. Since the piston will fall by' gravity when the flow of pressurized air tothe base of the piston is shut off, no means for returning the piston to its original position is necessary.- Consequently,' when the vibrator is used as the shuttle vibrator,- the pipe 107 may be removed from cylinder head 92 and replaced by a suitable plug.

In Fig. 10 is shown an alternate embodiment of a vibrator which may be used as the-hopper vibrator in the vibratory packing machine of the invention. A cylin der 200 is formed by a casing 201 and a cylinder head 202' threadedly'engagedin one end thereof. A reciprocable pistorr203-is mounted'in the cylinder 200. Exhaustports- 204 and 205 are-located in the cylinder wall equidistant from the ends of the cylinder and are separated by a distance such thatone end of the piston 203- begins to uncover oneof the exhaust ports as its opposite end hegins tocover the-other. An airinlet port 206-"in the casing opens into one end ofthe cylinder while an air exit passage 207'- leads'from the opposite end of thecylinder. A stepped orifice 208 is formed in the cylinder head 202, and disposed therein is a-flanged'pipe 209 having acentrally disposed stepped bore 210. The lower end of the pipe 209 is threaded-to receive an air hose 211 leading to an air line (notshown); A- reciprocable piston 212 is mounted inthe-bore,- 210 of the pipe 209. The travel of the piston 212 into the bore 210 of the pipe is limited to its own length' by the shoulder-213formed by the constriction of the steppedbore 210'.

Afii'xed toithe side. of. the vibrator casing 201 by a gasket 220'andstuds 221v is avalve assembly having a casing 223 which forms a chamber 224 having sections of different diameters. A.recess:225 is locatedin the valve casing 223 and-isincommunication with the air. exit passage 207 in-the vibratorqcasing 201. A thread 226 is formed in the..valve casing 223'andextends .into the chamber 224. A recess; 227jis formedin the. wall of the case ing.201 opposite the thread'226'. A threaded spring-actuatedv check:p'lug:228 threadedlly engages the thread 226 with thebase ofythe. plug. being retained in the recess 227.

The check plug 228, hasports- 229 and 230 located respectively in therupperand lower'walls thereof. A valve.231 in the. check plug 228iallows the passage. ofv compressed air through ports 229 and 230into the chamber 224.-

adjustable exhaust-valve 232: The valve 232 is-adjusted by screw 233 and whenever the valve 232 is partially or fully opened, the chamber 224 is in communication with the atmosphere through

ports

229 and 230 in the check plug 228 and through the valve 232.

An air inlet 234 is located in the valve casing 223 near the closed end of the portion of the chamber 224 having the smaller diameter. A passage 235 is formed by a recess in the valve casing 223. In communication with the recess 235 is a passage 236 which opens into the chamber 224 below the air inlet 234. Recess 237 in the casing 201 is a continuation of passage 236. Also in communication with the recess 235 is passage 238 which opens into the chamber 224 at a point below the passage 236. Passage 239 is a continuation of passage 238 across the chamber 224 and through casing 223 to the atmosphere.

A reciprocable piston 240 is disposed in slidable, substantially air-tight relationship in the portion of the valve chamber 224 having the smaller diameter. An annular groove 241 is cut in the piston 240 at a point which causes the groove to register with the

passages

238 and 239 when the piston 240 is fully within the portion of the chamber having the smaller diameter. The distance to which the piston 240 may extend upwardly into this portion of the chamber is governed by the projection 242 of the threaded plug 243 disposed in the valve casing 223 in the top of the chamber 224.

A piston 250 is disposed above the check plug 228 in slidable, substantially air-tight relationship in the portion of the chamber 224 having the greater diameter. The

length of the piston-250 is such that when it is forced downward by the piston 240, the upper end of the piston 240 is able to clear the lower edges of the passage 236 and recess 237, thus bringing air inlet 234 and passage 235 into communication. An annulus 251 is formed in the wall of the cylinder 224 at the point where the piston 250 meets the piston 240 when both are at the limit of their upward movement and when the piston 240 is in contact with the projection 242. A passage 252 is provided in the valve casing 223 which leads from the annulus 251 to the atmosphere, thus allowing air to enter the large portion of the chamber 224 above the piston 250 when said piston is forced downward by the piston 240. When the piston 250 is again forced to the up position, the air admitted on the down stroke exhausts to the atmosphere.

Threaded sockets 260 are provided in the top of the vibrator casing 201 for securing the vibrator to the hopper. Sockets 261 are provided in the cylinder head 202 to receive a spanner for securing the cylinder head in place.

It will be seen that the operation of the vibrator shown in Fig. 10 is similar to that of the vibrator shown in Figs. 5-8, the only diiferences being that the valve assembly has been inverted to give a power stroke in the down direction, and means have been provided at the bottom of the cylinder for returning the vibrator piston to the up position in preparation for each power stroke. As in the case of the vibrator shown in Figs. 5-8, the vibration frequency may be positively controlled by adjusting the me..- dle valve 232 and thus regulating the period necessary for the air line pressure to overcome the pressure below the piston 250.

In Fig. 11 is shown one of the resilient mounting assemblies employed to connect the feed hopper 24 to the bracket 21 of the feed hopper support frame 19. An elongated threaded stud 25 is equipped with an enlarged stop nut 300 approximately midway from the ends thereof and a small stop nut 301 on the lower extremity thereof. A tube-form resilient mounting 302 is disposed between stop nut 300 and stop nut 301 and comprises concentrically disposed

steel tubes

303 and 304 having a resilient rubber mass 305 bonded therebetween in shear. The outer tube 303 is shorter than the inner tube 304 and is disposed equidistant from the ends of the inner concentrical 1y disposed tube 304. A stepped bore 22 is formed in the hopper mounting plate 21 and is lined with a bronze casing 306 machined to fit the stepped bore 22 in the hopper mounting plate 21. The inner diameter of the casing is also stepped to form an annular shoulder 307. The lower end of the outer tube 303 of tube-form resilient mounting 26 is disposed upon the shoulder 307. The portion of the elongated stud extending above the stop nut 300 is disposed in a recess formed in the body of the hopper 24. Four similar mountings are disposed as shown in Fig. 1.

In Fig. 12 is shown in detail one of the resilient mounting assemblies employed to connect the platen 31 to the platen support frame 33. .This particular assembly comprises two plate-form resilient mountings 34 mounted in a series on a brass cap screw 310 and separated by a brass washer 311. Each of the plate-form mountings shown consists of a steel sleeve 312 having bonded about its periphery in shear a mass of rubber 313. An annular plate 314 is disposed in the outer edge of the mass of rubber 313 and protrudes therefrom. The plate 314 is secured in the annular orifice of a cup-shaped support member 315 by a crimp 316. The cup-shaped support member has an annular flange 317. The annular flange 317 of the upper mountings is secured to the underside of the platen 31 while the annular flange of the lower mounting is secured to the upper surface of the platen support frame 33. A recess 318 is provided in the underside of the platen 31 and a recess 319 is provided in the upper side of the platen support frame 33 to allow the ends of the brass cap screw 310 to reciprocate without touching the platen or the platen support frame.

In Fig. 13 a feed nipple 28 is shown which comprises a bronze tube having an annular projection 330 and an annular flange 331 near the upper end thereof to secure the nipple in the nipple plate 27. An annular constriction 29 is formed around the inner periphery of the egress orifice of the nipple 28. The size of the individual nipple and the number of nipples employed depend upon the size and number of the explosive cartridges or other containers being filled. Once the containers become filled, the material being introduced can no longer pass into the containers and cores are formed in the feed nipples. When the vibration of the hopper and shuttle is stopped and the nipples are disengaged from the mouths of the containers, the constriction 29 causes the nipples to retain the cores. When the nipples are then lowered into empty containers, the cores are removed when vibration is resumed. While it is preferred to form a constriction in a cylindrical bore as shown, similar results can be obtained by employing a nipple with a tapered bore. Coring can only be uniformly obtained with straight bores when the material being packed is characterized by extremely poor flowing qualities.

Referring particularly to Fig. 14, a sectional view of a portion of the platen assembly is shown to illustrate the operation of the shuttle box gripping piston assembly 36 which holds the shuttle box in position on the platen during the packing operation. The gripping piston assembly 36 shown in Figs. 3 and 4 has a casing formed by a base member 333, a cylinder head 334 and a piston guide member 335. The base member 333 and the cylinder head 334 are maintained in tight sealing relationship by means of gaskets 336 and 337 and studs 338. The piston guide member 335 is held in forced fit by the flange 339 of the base member 333. The casing so formed defines a cylinder 340. A piston 341 having an enlarged head 342 is concentrically maintained in the cylinder 34% by the piston guide member 335. The enlarged piston head 342 is grooved to receive a packing ring 343. The small opposite end of the piston 341 extends from the guide member 335. A rubber cap 344 is secured to the end of the piston 341 extending beyond the piston guide member 335 by a pin 345.

One end of a bellows 49 is secured to the piston guide member 335- and the other end-of=the-bellows 49" i's'secured to therubbercap-344: The-piston 341 has a bore- 346 extending from the end protruding fromthe-pistonguide member 335 to the enlarged piston head342. The bore 346 is in communication with the inside of the bellows 49 through apassage 347. The bore 346 is also in communication with the cylinder 340 through a passage 343. The enlarged piston head 3420f the piston 341 is normally held in the position shownby the coil spring 349. Air from the power line is deliveredto the cylinder 340 on the opposite'side of the enlarged piston head 342 through a passage 40 which passes through the platen 31, the base member 333 and the cylinder head334.

Whenair is supplied through passage 4% to the endof the cylinder 340, pressure is exertedon the enlarged piston head 342-ciusifig1thefpiston 341""to mbve through the piston guide member -335.'until the rubber cap 344'engages the shuttle box 37 'and secures it in position against the positioning studs on the opposite side of the platen Sl.

The spring 349 is compressed by the movement of the piston and when the airpressure on the piston head .342.

is removed, the piston 341' is returned to the. position shown by the action of the spring 349, and theshuttle box 37 is released.

The packing of large size explosive. cartridges on the vibratory packing machine of the invention willnow be described with reference to the drawings andparticularly to Fig. 4. A shuttle box 37 containing thedesired number.

of explosive cartridges of the desired sizev is placed upon the platen 31 and positioned securely against the stop studs 35'. A nipple plate 27' containing the desired number of nipples of the size desired to correspond with the number and size of cartridges of the shuttle box 37 is attached to the feed hopper. Fluid medium is then admitted to cylinder 41 at the base of the piston 43 and the platen is raised on its support by the piston 4-3 until the nipplesz enter the top of the empty shells to the desired distance. The explosive material to be packed is then introduced into the hopper 24. Pressurized air is admitted to the platen vibrator 32, the shuttle box gripping piston assembly 36, and the hopper vibrator 30. The explosive material is then continuously introduced into the right side of the hopper as shown in Fig. 4 and is conveyed to the left as a result of the vibratory movement of the hopper being downward and to the right. The explosive material therefore flows through the nipples and into the shells below. The particular type of vibration induced in the platen 31 by the pneumatic vibrator 32; causes the explosive to be packed in the shells to a high and uniform density. and degree, and a core has formed in the nipples, the supply of air to the hopper vibrator 3%), the platen vibrator 32 and the gripping piston assembly 36 is shut oil. The pressure of the fluid medium beneath the piston 44 in cylinder 42 is released, and the platen 31 is allowed to settle to its down position. Due to the annular constriction 29 at their egrees orifice, the cores are maintained within the nipples. The shuttle box offilled shells 38 is removed for crimping and scaling, is replaced by a box of empty shells and the operation is repeated. When vibration of the hopper is resumed, the cores are dislodged into the empty containers. If desired, the cartridges can be loosely filled with explosive prior to initiating vibration in the platen. As previously indicated, the shells themselves may be loosely contained in the shuttle box or may be rigidly secured in the box so that the movement of the box is transmitted directly to the shells.

While it is not intended that the following theory of operation of the vibratory packing machine in accordance with this invention should in anyway restrict the actual scope of the invention, it is believed its success in packing explosive materials to their necessarily high and-uniform density is due to a number of cooperating features. The

When the shells are filled to thedesircd density 5 unidirectional-powerstroke of the platen-vibrator iman' upward direction forces the material to be packed-ii1to bottom of its fall by an air cushion in the bottomofthe" cylinder together with the cushioning provided by the resilient mountings, allows, successive packing strokes without any appreciableintermediateloosening. There siliency of the platen mountings also-causes agrelatively. gradual deceleration of the upward movement of the platen, of the shuttle 'box, ofithecartridge, and of the explosive and consequently, does notundo any substantial portion of the packingaccomplished by the upward thrust of each power stroke. Furthermore, since the fall of the vibrator piston is cushioned by the air beneath the piston andsince the. fall'ofihe platen following the power stroke is also cushionedby the resiliency of the mount: ings, no substantial jarring takes place which would tend to loosen the material.in the cartridge. When the.pre-. ferred controllable speed' vibrator is employed as the platen vibrator, the optimum vibration frequency. can be obtained for each materialto be packed.

In order to obtain an explosive cartridge having a high and uniformdensity, it has further been found that a pneumatic vibrator having a unidirectional power stroke in the upward direction must be rigidly attached to the platen. Ifthe vibratoris not so attached, satisfactory packing is only obtained directly over the point where the vibrator strikes the platen. Consequently, the packing efficiency diminishes towardthe edge'ofthe platen.

It is realized that many modifications. of the vibratory packing machine which are within the. scope of they invention will become. apparent to, those. skilled in theart of vibratory packing and to those skilled in theart of manufacturing pneumatic vibrators. and overall structure of all' the parts ofthe particular. machine described and illustratedare obviously not essential to its success. the platen other than thefluid-actuated cylinder. disclosed could be substituted.which-mightprove equally desirable. The support'stanchionsand support frames could obvious.- ly be arranged in a manner dilferent from that specifically illustrated, and any suitable materials of construction could be substituted for those employedin the-structuresillustrated.

While the specific design of resilient mountings illustrated is rubber bonded in shear to metal, and is preferred and has been found to give best results, other types of resilient mountings are operable. as long as they permit or cause the platen to have. the critical movement above described. Such means would include some types of,hy--

draulic cylinders or dash pots and systems of counterweighted levers. to be unsatisfactory since a relatively more rapid'change in strength takes place which brings about a. substantial change in the movement of'the platen overa period .of, time. Furthermore, coil springs are most undesirablein the packing of explosives from the. safety standpoint, since coil springs are known to snap. The breaking of a coil spring is often accompanied by sparksuwhich might possibly cause an explosion despite the, act that the platen,

its support frame and the resilient mountings arepreferably surrounded bye. protective-bellowsas shownin the drawings. The specific type of mounting illustratedis greatly preferred since. it is very easy to installor to. replace, gives exceptionally long wear; and has been found toimpart the most'effective motion to the platen;

The. specific design;

For. example, .means, for elevating.

Coil springs have generally beenjound It is preferred that the exhaust ports of the vibrators of the invention be spaced evenly from the ends of the vibrator cylinders and that these ports be separated by a distance substantially equal to the length of the piston. With this arrangement the best results are achieved both from the standpoint of smoothness of operation and economy of air. However, this preferential arrangement is not essential to the operation of the vibrator. As long as the port being uncovered by the piston during the power stroke is located far enough from the end of the cylinder to enable the piston to gain sufiicient velocity, the momentum of the piston will insure completion of the stroke even though the port is open during the last portion of the stroke. When the piston is returned to its starting point, either by gravity or other means, the port should be located close enough to the end of the cylinder to allow most of the air to exhaust and thus give a substantially full stroke. The auxiliary exhaust means shown in the drawings is helpful in this regard.

The exhaust port bein covered by the piston during the power stroke should be placed close enough to the opposite end of the cylinder to allow the piston to make a substantially full stroke but should be located far enough from the end of the cylinder that enough air is trapped and compressed in the end of the cylinder to fully depress the valve piston or other slidable means in the Valve assembly. All of these factors must be coordinated to give optimum results in each particular design and size of vibrator in accordance with the invention.

It is preferred that two separate but coacting pistons be employed in the valve assembly as illustrated in the drawings. A single piston having two different diameters is operable, but is not preferred because the single piston is more difficult to lap to the substantially air-tight fit necessary to satisfactory operation of the valve assembly.

In view of the fact that many modifications of the invention are possible, it is to be understood that the invention is to be limited only by the scope of the appended claims.

This application is a division of copending application Serial No. 346,115, filed April 1, 1953.

What we claim and desire to protect by Letters Patent is:

1. A process for packing pulverulent materials in a container to a high and uniform density which in combination comprises introducing the pulverulent material into a vertically situated container, intermittently imparting a plurality of vertically upwardly applied impulses to the container, gradually arresting the upward movement of the container after each impulse, allowing the container and its contents to fail freely after arresting 34 their upward movement, and gradually decelerating the fall of the container and its contents prior to applying each successive impulse.

2. A process for packing pulverulent materials in a container to a high and uniform density which in combination comprises vertically positioning the container, intermittently imparting a plurality of vertically upwardly applied impulses to the container, gradually introducing the pulverulent material into the container, gradually arresting the upward movement of the container after each impulse, allowing the container and its contents to fall freely after arresting their upward movement, and gradually decelerating the fall of the container and its contents prior to applying each successive impulse.

3. A process for packing pulverulent materials in a container to a high and uniform density which, in combination, comprises introducing the pulverulent material into an upright container, intermittently imparting a plurality of upwardly applied impulses to the container, gradually arresting the upward movement of the container after each impulse, allowing the container and its contents to fall freely after arresting their upward movement, and gradually decelerating the fall of the container and its contents prior to applying each successive impulse.

4. A process for packing a pulverulent explosive material in a cartridge to a high and uniform density which comprises introducing such explosive material into said cartridge maintained in an upright position, intermittently imparting a plurality of upwardly applied impulses to the said cartridge, gradually arresting the upward movement of the cartridge after each impulse, allowing the cartridge and its contents to fall freely after arresting their upward movement, gradually decelerating the fall of the cartridge and its contents prior to applying each successive impulse, and rigidly supporting said cartridge for response to each said impulse.

5. A process of claim 4 wherein said explosive is a dynamite.

References Cited in the file of this patent UNITED STATES PATENTS 868,605 Heybach Oct. 15, 1907 1,052,086 Mumford Feb. 4, 1913 1,605,096 Campbell Nov. 2, 1926 2,379,230 Griflin June 26, 1945 2,447,312 Burt Aug. 17, 1948 FOREIGN PATENTS 492,940 France Apr. 10, 1919 808,489 France Nov. 14, 1936