US1984197A - Centrifugal molding machine - Google Patents

Description

Dec. 11, 1934. 1 F NE PAGE 1,984,197

CENTRIFUGAL MOLDTNG MACHINE Filed Aug. 2l, 1931 A. I W INVENTOR Patented Dec. 11, 1934 CENTRIFUGAL MOLDING MACHINE Justus F. Ne Page, Seattle, Wash., assigner to Ne Page McKenny Co., Seattle, Wash., a corporation of Washington Application August 21', 1931, Serial No. 558,529

11 Claims.

My invention relates to improvements in centrifugal molding machines .particularly for the manufacture of long reinforcedconcrete articlesv and to the method of manufacturing the same, with specialreference to the production of ornamental, reinforced concrete, street lighting standards having relatively large -diameter base portions and small diameter tapering shaft portions, and isl inthe nature of an improvement on my U. S. Patent No. 1,777,763 assigned to Ne Page McKenny Co.

The object of my invention is to provide improved means for increasing the rate of production and decreasing the cost of molding concrete articles.

A further object is to provide improved means for the manufacture of concrete articles from a high water-cement ratio fiuid mix whereby the same is'changed into uniformly low Water-cement ratio, high strength concrete during the process Aof manufacture.

Another object is to provide improved means whereby long, ornamental concrete articles, uniformly free from interior and surface defects, may be cast from a uid concrete mix.

A final object is to providean improved method of manufacturing high-strength concrete articles from a liuid concrete mix.

With the above and related objects in view, thev posed mold partly in section. 4

Fig. 2 is a plan View of the spinning and vibrating mechanism with the mold, spinning table, load rollers and gear box cover removed.

Fig. 3 is a sectional elevation of thespinning and vibrating mechanism, on broken line A-A of jig. 2, in operative combination with an elevation broken line B-B to a larger scale, showing one of the adjustablewheels mounted on the eccentric portion of the shaft.

Like numerals of reference indicate correspond'- ing parts in the different figures of the drawing.

(Cl. .Z5-30) The machine of my invention in its preferred form consists of a combination spinning and vibrating unit 1, an upright mold unit 2 removably mounted thereon, and a removable topconnection assembly 3 supported by a suitable tower structure, not shown, arranged to expedite the filling of the mold with fluid concrete.

The combination spinning and vibrating unit is assembled upon a main frame casting 4 providing a tapered circular track portion 5 and a base plate portion adapted to bear upon a suitable concrete foundation 7, to which the frame is secured by means of anchor bolts 8. A cover 9, removably secured to frame 4, provides an oil tight compartment which encloses a bevel gear speed reducer, the bevel gear Wheel l0 of which is xedly secured to a vertical shaft 11, rotatively mounted in step bearing l2, thrust bearing 13 and guide bearing 14 as shown clearly in Fig. 3 of the drawing. The pinion 15 of the speed reducer is xedly secured to a horizontally disposed shaft 16 rotatively mounted in bearing 17 provided in the frame casting. 'Ihe projecting end of shaft 16 may be directly .connected by means of a coupling 18 to a variable-speed electric motor 19 mounted on an extension of base plate 6.

A spinning table 20, having a beveled circular track portion 21 and hub 22, is revolvably supported by a plurality of tapered rollers 23 adapted to traverse said base track 5 and said table track 2l. Spinning table 20 is rotated and maintained in alignment by the upwardly projecting casehardened end of shaft 11, Which is squared as at 24 to form a slidable driving connection with hub 22 through the intermediacy of a hardened steel bushing 25, which is xedly secured in said hub and provided with a square aperture to receive said squared portion 24 of shaft 11.

Tapered rollers l23 preferably are composed ot' a resilient material such as vulcanized rubber, similar to that used for automobile fires, which may be molded aroundv bronze sleeve centers 23j.. rIfhis construction permits the mold to be vibrated at relatively high frequency and through the maximum amplitude required Without undue shock'to the moldor other parts of the equipment.

These support rollersare maintained in equiv distant positions around their circular tracks by means of a split, or two part, spider having hub ring portions 25 and appended arms 26, which may terminate in journal projections 27 on which rollers 23 are rotatably mounted and Secured in position by nuts 28 and keyed washers 29 abutting 1 suitable vshoulders on said'journals. Arms 26 are strengthened by annular rim halves 30. Both the hub ring and annular rim halves are connected by bolts (not shown) so the spider may be removed fromthe grooved portion 31 of spinning table hub 22, on which it is revolvably mounted. This construction maintains rollers 23 in proper relation to the tapered tracks and provides accessible means for their inspection and replacement.

Two wcrm and gear units 32 and 34, each provided with projecting shafts 35 having eccentric portions 36, are removably mounted on suitable extensions of base plate 6 with the rotational axes of shafts 35 in alignment and diametrically opposite shaft 11. Wheels 37, having tapered peripheries to conform to the taper of circular track 5, are rotatably mounted on the eccentric portions 36 of shafts 35, the inner ends of which are rotatively supported in suitable bearings in frame casting 4. Shafts 35 are flxedly secured to the worm wheels of gear units 32 and 34 which provide the other necessary bearing supports.

Suitable apertures 3S are provided in circular track 5 to allow wheels 37 to protrude varying distances above the surface of the track as the eccentric portions 36 are raised by the rotation of' shafts 35, on which the worm wheels of said'gear units are mounted in operative combination with the worm pinions thereof mounted on shafts. 39.

Power for this operation is supplied by a suitable electric motor 40 adapted to drive pinion 41 in gear box 42 through the intermediacy of coupling 43. Said pinion in turn drives gear 44 secured to shaft 45 journaled in bearings 46 of frame 4. Bevel gears 47 are so positioned and secured to shaft 45 that they drive bevel gears 48 on shafts 39 in opposite directions, and therefore turn shafts 35 in opposite directions at reduced speed through the intermediacy of worm and gear units 32 and 34.

When the eccentric portions 36 of shafts 35 are in their vertically downward positions, wheels 37, preferably provided with bronze bearing sleeves 37', are withdrawn slightly below the surface of track 5 as shown in Fig. 3. Upon energizing motor 40, it is apparent that eccentrics 36 and Wheels 37 will be moved upwardly through arcs, the radii of which are equal to the distance between the center of shafts 35 and the center 0f eccentric portions 36. By using identical worm and gear units, the arcs traversed by wheels 37 will be on the opposite sides of shafts 35, hence diametrically opposite rollers 23 approaching apertures 38 will engage wheels 37 at the same instant for their various raised positions, and will roll over corresponding protruding portions of said wheels, thereby coacting to impart a vertical vibration to spinning table 20 and mold unit 2.

The frequency per minute of this vibration is equal to one half the revolutions per minute of the spinning table times the numberl of support rollers employed. The nominal amplitude of the vibration is equal to the radial distance wheels 37 protrude above track 5. Therefore the fre'- quency of vibration may be varied by the `operator by varying the speed of drive motor 19, and the' Patent No. 1,831,128, issued Nov. 10, 1931 on application Serial No. 362,622, flled May 13, 1929, lay be supported by gear box 42 and connected by means of gears 50 and 51 to shaft 45, the arrangement being such that when the'operator control switches (not shown) are closed to operate motor 40 to raise wheels 37, said motor will be stopped automatically after completing the necessary number of revolutions required to raise wheels 37 to their maximum height. Likewise when the operator switches are closed to reverse motor 40 to lower wheels 37. the motor will be stopped automatically after completing the number of revolutions required Vto lower wheels 37 to their lowest position. Intermediate positions are secured by the operator by manual operation of the control switches.

Spinning table 20 is provided with a plurality of bosses 52 in which torque pins 53 are fixedly mounted. The lower shank portion of a flanged pivot block 54 is adapted to llt tightly in the square aperture of bushing 25 so that the flange portion bears directly on the hub of the spinning table. Block 54 provides a suitable socket to receive a large pivot ball 64, as shown clearly in Fig. 3. Ball 64 may be composed of a resilient material.

The vertical mold unit 2 is composed of a plurality of flanged longitudinal sections 55 and a base section 56, which are held in operative combination by means of bolts 57 passing through the flanges. The mold sections may be assembled around longitudinal reinforcing rods 58 and spiral 59, which preferably are secured at their points of contact by welding to form a reinforcing cage. This cage is positioned centrally within the mold by means of welded cross-bar spacers 6l, which may serve also to position a conduit pipe 62, preferably closed at its ends .by means of suitable plugs 63 that are readily removable after the mold is filled and the concrete has set.

The assembled mold is mounted for axial rotation on spinning table 20 through the inter- -mediacy of block 54 and pivot ball 64, which nts in a suitable socket in heavy hub 65 of mold base section 56. Loose fitting apertures'are provided in the annular flange at the base of the mold to receive torque pins 53, thereby providing a positive yet flexible driving connection between the spinning table and mold. This method of mounting assures satisfactory operation of the apparatus even when there is considerable variation in the vertical alignment of the axis of shaft 11 f with the axis of the mold.

The removable top assembly 3 consists of several parts which coact to position the mold in an upright position on the spinning table so it may be rotated and vibrated thereby, and facilitates the work of the operatorin mounting, lling and removing the mold. Referring particularly to these parts, a. tubular top journal 66, having a flange 67, is secured to the flanged top of the assembled mold by means of bolts 68, and is rotatively mounted in bearing 69 supported by cross members 70 removably secured to the tower structure, not shown, which also supports a platform 7l for the convenience of the operator.

Tubular journal 66 is made of sufficient length to project through a loose-fitting cylindrical aperture provided in the bottom of discharge basin 72 removably supported by cross members 70, and provided with a spout 73 connecting with a trough 74 which in turn connects with a suitable waste pipe, not shown. A horizontally disposed, internally threaded, annular disc 75 is screwed onto the threaded top of journal 66 after the discharge basin is placed in position. A trough 76, having a funnel-like end 77 and suitably supported as at 78, is used to facilitate pouring the fluid concrete into the rotating mold.

This construction permits the use of molds of various lengths and shapes. The one here shown for simplicity has been made of circular cross section, but the mechanism and process may be used for molding a wide variety of articles by merely substituting other properly constructed mold.

When a spiral reinforcing element is employed, the rotation of the mold should be opposite to the direction traced in following down the convolutions of the spiral, as this has been found to assist in the elimination .of voids by tending to force the concrete downward as it is poured into the mold. Whena series of horizontal rings are used in the construction of the reinforcing cage, the mold may be rotated in either direction.

In carrying out the process of manufacture with the mold illustrated, the apparatus is assembled as shown in Fig. l, motor 19 is energized and the mold brought up to the speed required to produce the centrifuging action and frequency of vibration desired while filling the lower, largef diameter, sectional portion of the mold. Fluid concrete, normally having a high water-cement ratio, may then be poured into the mold, preferably in a small rapidly flowing stream, and motor 40 energized to raise wheels 37 sufficiently to vibrate the mold through the desired amplitude. These vibrations prevent the inowing concrete from choking the mold above the fill, pack the concrete quickly and firmly at the center of the ll, and tend to flatten the paraboloidal basin formed at the top of the ll.

When the mold is rotated without vibration, the surface of the heavy particles constituting the fill assumes the shape of a paraboloidal basin due to the combined action of the centrifugal and gravitational forces, which are indicated by the letters C and G respectively in the force diagrams of Fig. 4, at various points along curve 8l. This curve represents the surface of the fill as seen by taking a vertical section through a diameter ofthe mold. Forces'C and G combine to form a resultant which is normal to the tangent T of the curve at any-given point. The gravitational force G obviously is constant, but the centrifugal force C varies directly as the square of the distance from the center, for a given speed of rotation.

When the mold is vibrated by forcing rollers 23 to roll over the protruding portion of wheels 37 ink traversing track 5, the mold is suddenly moved upward at a rate gradually diminishing to zero, thereby using the inertia of the ll to pack the same downward in the mold. Likewise when the mold is stopped suddenly while moving downward at a rate gradually increasing from the aforesaid zero the momentum of the fill is used to again pack the same downward in the mold.

As these impulses are rapidly recurring and the.

ll is a plastic, cohesive and ponderous mass, the effect on the fill is the same as though another force V was added to forces C and G. As force V is in the same direction as force G, it is evident .that they combine to increase the value and change the direction of the resultant R, as indicated for the point 80 of Fig. 4. Point:80 is the same radial distance from the center of rotation as point 79 and therefore has the same value of C, butv due to the change in the direction of R the curve 82 representing the surface of the basin is fiattened as compared with curve 81, which repre- -sents said surface without the vibration. It is 3 therefore permissible for a given shape of basin to use higher, speeds of rotation when the mold is vibrated.- This in turn reduces the time re-v quired to squeeze the excess water and air from the fill into the basin, in which they are carried upward in the mold in the form of suds.

Since the rotation and vibration of the mold combine to reduce the time required to extract the excess water and air from the fill, it is apparent that the fluid concrete may be fed into the mold at a higher rate, thus reducing the molding time for a given article and increasing the production capacity of the machine. To this end I prefer to feed a small rapidly flowing stream of the mix instead of a slow moving stream of large section, as the small stream distributes the material more evenly in the mold.

The extraction of excess water from the mix reduces the water content of the fill in the mold and produces a uniformly low-water-cement ratio, high-strength concrete for a wide variation in the water-cement ratio of the mix. This assures a uniform product, yet permits the use of a mix sufficiently fluid to flow readily into the mold. By vibrating the mold, the density of the fill at the center of the mold and the amount of water extracted are increased, both of which operate `to produce a more uniform and stronger product in a shorter length of time than is possible without vibrating the mold.

As the mold is filled and the diameter of the basin decreases, the operator may increase the speed of rotation by increasing the speed of motor 19; This also increases they frequency of vibration. As the frequency is increased the amplitude of the vibration may be decreased by decreasing the raise of wheels 37 by controlling motor 40, thus securing the most advantageous proportions for the basin throughout the length of the mold.

As the paraboloidal basin rises the suds are carried upward in the mold and spilled from the top of tubular journal 66 over annular disc 75 from which it is centrifuged into discharge basin 72. From there it flows away from the apparatus through spout 73, trough '74 and the connected Waste pipe.

After the mold is filled, motor 40 may be energized to withdraw Wheels 37 which are stopped in their lowest position by the operation of limit switch 49. The rotation of the mold may then be continued at the same or at other speeds to further set the ll into the intricacies of the mold as the judgment of the operator may dictate.

The rotation of the mold is then stopped, trough 76 and appended funnel 77 are removed and disc is unscrewed from tubular journal 66, thus permitting the removal of bearing 69 and discharge basin 72. The mold may then be removed frorn the spinning table by a crane or other suitable means, after which tubular journal 66 is unbolted and removed from the mold and the concrete smoothed ofi level with the top of themold thus exposing conduit pipe 62. When the material has set, bolts 57 are removed and the mold sections stripped from the finished article.

The adjustable rotation and vibration features of my invention are amenable to a wide variety of combinations during the molding process, which may be readily adapted to meet the requirements `for the rapid, economical and satisfactory molding of concrete articles having various sizes, proportions and embellishments within the load capacity of the machine.

In general, the slower rotational speeds and greater amplitudes of vibration are used in molding articles having relatively large lateral sectional dimensions, or in molding those sectional portions of an article having such dimensions; and the higher rotational speeds and smaller amplitudes of vibration are used in molding articles having relatively small lateral dimensions, or in molding those portions of an article having such dimensions.

. For example, when molding short slender articles such as concrete posts, a relatively high constant speed and small amplitude of vibration may be used to maintain the top of the concrete ll in the form of basin desired, and at the same time centrifuge the outer portion and pack the center portion of the ll.

When molding relatively long. slender articles such as concrete poles and street lighting standards, I prefer to start filling the mold at a relatively slow speed and relatively large amplitude of vibration. The larger diameter at the lower end assures the proper centrifuging of the outer portion of the iill against the sides of the mold,

and the larger amplitude of vibration assures the packing of the fill at the center of the mold While maintaining the'ascending top of the ll in the form of a basin into which the suds are effectively squeezed. As the mold is lled and the diameter decreases, the speed may be increased and the amplitude of the vibrations decreased, care being taken to maintain the basin in the top of the ll to receive the suds and nally spill it from the top of the mold. With the mold filled and the excess water and air removed in the suds, the mold may then be rotated to further pack the periphery of the ll into the small spaces of the mold, thus assuring a hard smooth surface and fully formed embellishments free from surface defects.

It will be apparent to those skilled in the art that various changes may be made in the mech- Vco anism of the machine and in using the principles of the process without departing from the spirit and intent of the invention.

For example, the spinning table element may be eliminated and the base of the mold adapted to engage the vertical driving shaft direct and to be supported directly by the rollers. This requires precision construction of the mold and precise positioning ofthe mold with reference to the actuating mechanism, Whereas in the form herein illustrated and described, quite large inaccuracies in construction and alignment do not affect the satisfactoryoperation of the device.

` While I have shown two adjustable wheels 37, it is apparent that three or morev such Wheels could be used. This might be desirable Where higher frequency vibrations are required. Obviously non-rotating arcuate projections could be substituted for wheels 37 as means for vibrating the mold through the intermediacy ofthe rollers as they traverse the base track. The number of support rollers, however, should be a multiple of the number of wheels or arcuate projections used.

Instead of mounting rollers 23 on a spider so spinning table 20 rests on the periphery of the rollers, they could be axially mounted directly on the base section of the mold or on the spinning table.` The speed of revolution around track 5 would then equal the, speed of rotation of the mold, whereas it is half that speed with the arrangement shown. Furthermore the bearing sleeves of the rollers would have to be larger to carry the entire Weight of the mold,and only the resiliency of the lower halves of the rollers would be effective.

While I have specied the use of uid concrete, other concretious materials may be used. In using the process, many variations may be made in the way the material is introduced, and in the use of the spinning and vibrating features in lling the mold to manufacture a given article.

Having thus described my invention what I claim as new and desire to protect by Letters Patent, is:

1. In a centrifugal molding machine, the combination of an annular base track, a plurality of rollers adapted to traverse said track, a rotatively driven upright mold supported by said rollers and arcuate means projecting above said base track for vibrating said mold through the intermediacy of said rollers.

2. In a centrifugal molding machine, the combination of an annular base track, a plurality of resilient rollers adapted to traverse said track, a rotatively driven upright mold supported by said rollers, and adjustable arcuate means projecting above said base track for vibrating said mold through the intermediacy of said rollers.

' 3: In a centrifugal molding machine, the combination of an annular base track, a plurality of rollers Iadapted to traverse said track, revolvable spider means adapted to rotatively mount said rollersin xed space relation around said track, an upright mold rotatably mounted on said rollers, and adjustable arcuate means projecting above said base track for vibrating said mold through the intermediacy of said rollers.

4. In a centrifugal molding machine, the combinationof an annular base track, a plurality of rollers adapted to traverse said track, a spinning table revolvably supported on said rollers, a rotatively driven upright shaft Apositioning said spinning table coaxial of said base track and providing a sliding positive driving connection therewith, and adjustable arcuate means projecting above said base track for vibrating said spinning table through the intermediacy of said rollers.

5. In a centrifugal molding machine, the combination of an annular base track, a plurality of spaced rollers adapted to traverse said track, a revolvably driven spinning table supported by said rollers, a plurality of apertures in said track in i the traverse of said rollers, eccentrics rotatively mounted below said apparatus, wheels revolvably mounted on said eccentrics and adapted to protrude through said apertures, worm gear means actuating said eccentrics thereby positioning said wheels to intercept said rollers and vibrate said spinning table, and worm pinion means actuating said worm gear means.

6. In a centrifugal molding machine, the combination of an annular base track, a plurality of spaced rollers adapted to traverse said track, a revolvably driven spinning table supported by said rollers, a plurality of apertures in said track in the traverse of said rollers,eccentrics rotatively mounted below said apertures, wheels revolvably mounted on said eccentrics and adapted to protrude through said apertures, worm and gear means actuating said eccentrics whereby said wheels may be adjustably positioned to intercept said rollers and vibrate said spinning table, power means actuating said Worm-and gear means, and motion limit control means in rotative connection with said power means whereby s aid power means is stopped automaticallywhen said wheels, being raised, protrude their maximum distance above said base track, or, being. lowered, are withdrawn the maximum distance below said track.

7. The method of molding concrete articles, which consists of mounting a mold in an upright position, pouring uid concrete into the upper end thereof, rotating said mold concurrent with said pouring to form a basin at the top of the ascending ll, and repeating the sequence of suddenly moving said mold upwardly at a suitable rate gradually diminishing to zero, then sudden- 1y stopping the mold While moving downward at a rate gradually increasing from said zero to pack the ll in said mold concurrent with said pouring 'and said rotating.

8. In a centrifugal molding machine, the combination of an annular base track, a plurality of rollers adapted to traverse said track, a revolvably driven spinning table supported by said rollers, resilient means on said spinning table, an upright mold pivotally supported on said resilient means and positively driven by said spinning table, and arcuate means projecting above said track y for vibrating said mold through the intermediacy of said rollers, said spinning table and said resilient means.

9. 'I'he method of manufacturing concrete articles, which consists of mounting a mold in an upright position for axial rotation and longitudinal vibration, concurrently pouring fluid concrete into the mold and rotating and vibrating the same .to form a basin at the top of the fill, then varying the speed of said rotation to maintain a said basin while filling the different cross-sew tional space portions of the mold.

10. The method of manufacturing concrete articles, which consists of mounting a mold in an upright position for axial rotation and longitudinal vibration, concurrently pouring fluid concrete into the mold and rotating and vibrating the same to form a basin at the top of the ll, then varying the amplitude of said'vibration to maintain a sa-id basin vwhile lling the different cross-sectional space portions of the mold.

11. The method of manufacturing concrete ar-

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