US1765064A

US1765064A - Building-block machine

Info

Publication number: US1765064A
Application number: US180638A
Authority: US
Inventors: Charles M Eberling
Original assignee: Individual
Current assignee: Individual
Priority date: 1927-04-04
Filing date: 1927-04-04
Publication date: 1930-06-17
Anticipated expiration: 1947-06-17

Description

' c. M. EBERLING I 1,765,034 BuiIJDNG BLOCK MACHINE June 1.7, 1930.

* Filed April 4, 1927 10 sheets-sheet 1 June 17, 1930. c. M. EBERLING nUILDINGr BLcK MACHINE Filed April 4, 1927 10 Sheets-fSheet 2 maries .12!6'80-'111'` a Inventor Attorneys June 17, 1930. C M EBERMNC;- J l 1,76A5,Q64V

I BUILDING BLocK MACHINE FII f r11 4Q 1927 1o sheetssheet 5 i .A ttoxfl'zzays 100617, 1930- c.l M7 BERLlN'G 1,755,064. f

BUILDING BLOCK MACHINE Filed April -4, 1927 10 Sheets-Sheet 4 11 -l l' f i lCbarls M felrln l Inf/sx1 or v Attorneys June 17, r1930. c. M. EBERLING ,1,7 65,064*

. BUILDING BLQCK MACHINE v Filed April 4, 1927 10 Sheets-Sheet 5 Charles M. ern

In ven 1 ZYMMM- At torzey June 17, 1.930. I C, M EBERUNG 1,765,064

BUILDING BLOCK MACHINE Filed April 4, 1927 10 Sheets-Sheet 6 C71 arles fzerlz'ng Inventor A torn ys June 17, 1930. C, M EBERQNG 1,765,064

BUILDING BLOCK MACHINE Filed Aprii 4, 1927 1o sheets-sheet 7 612a-ries Mferlng Inventor Atomeys June 17, 1930- c. M. EBERLINGA BUILDING BLOCK MACHINE Fled April 4, 1927 10 Sheets-Sheet 8 Trarba- M. 'Zrlz'ng Alfter-nays C. M. EBERLNG BUILDING'BLocK MACHINE:4

Filed Ap'ril 4, 1927 June 17, 19.30 v

10 Sheets-Sheet 9 Charlas A1. 53021132? Izvon r Ae torzzegs `une 17,1930. c. M. EBERLING BUILDING BLocx MACHINE Filed April 4, 1927:

flQ Sheets-Sheet k10 ing Inf/cantor Attorneys Patented June 17, i930 UNITED STATES summe-Bacci: inem :Application med prll 4,

T his'invention relates to concrete bloclic ments of maximum' 'size and minimumA weight combined with\adequ'ate strength for practical purposes' which shall have improved facilities for handling the md1ds and ejecting the completed articles; and which shall have improved provisions for timing the operation of the different lelements'; wh ile further objects and advanta es of the inventionA will become descri tion proceeds.

In t edrawings accompanyin thiss eciication and forming a part of t is app icavtion I"have shown lone embodiment of my invention, and in these drawings:

Figures 1 and- 2 are perspective views jof the preferred form ofmachlne;

Figure 3 is a side elevatiolrof the -machine drawn to larger scale;

Figure 4 is -a vertical sectional view corresponding to the line 4-4 of Figure 5;

Figure 5 is a central sectional view of the machine corresponding to the line 5-5 lof `Figurel; l

Figure 6 is a horizontal section on 'the line 6--6 of Figure 5; l Figures'7, 8, 9, and 10 are views of the operating parts of the. machine showing their relatlon at diiferent l.steps -of the operation; f I f Figure 11 is a transversesectionI showing application of a pallet tothe mold; I

Figure 12 is a-s e :tional` view throughs. tile ,containing the present improvements, while Figure 1 3 .is 'a diagram cycle of operations. improved machine 'comprises generapparent as t e 11 theA four sides illustrating the d ends of the arms 16 preferably rest upon the '(jto 10, so as tol PATENT- OFFICE enanas n. nnnmmagor cnnvnnann, onror 19er, semi no. 180,688.

all a rotating member which carries the di erent molds, a feeding device whereby a mixture of raw materials is fed to the molds, a tamping mechanism whereby such mixture is compressed in the molds, astripping mechanism whereby the compacted material is ejected from themolds, an off-bearing mechanism whereby the com leted articles are-removed from the mac ine, and timing' mechanism whereby all the foregoing activities are correlated. f

The embodiment-of my invention disclosed herein. comprises a frame having at one end, hereinafter denominated the front, a pair of spaced uprights 1 connected at the top by a cross bar 2 and at the bottom by a crossbar 3.- Horizontal channel members/1 connect the uprights 1 intermediate of' their height with rear vertical uprights 5 and the lower ends of the

uprights

1 and 5 are con; nected by bars 6. Journaled in the front ich is secured a four-sided carrier 8 consisting, of two longitudinal spaced spare between the uprights 1` Tightly bolted to rights is a massive horizontal shaft 7 on the carrier 8 are molds 11 which comprise essentially rectangular frames 12, constituting side walls, and a vbottom member 13 to which are generally with a vstripping plate 15, one for each tile 'i tends'jinwardlypast the Aadjacent frame `9 4and each stripping being provided at each end with an integral arm 16 which e1;-A

towards the shaft 7. In the present em-v i bodiment there are vtwo of these stripping plates for each mold, and consequently four z a arms .16 on each side of the carrierV 8 as shown in Figure 4.' These stripping plates 15 form in eifectV the bottom o the mold and `when in receiving, position the inner .shaft 7 as shownin Figures frames 9 having'hubs 10 secured to the s aft I fastened inside the mold frame 12 'a plureceive the ent-ire blow of the tampers. The ends of the arms 16 near the shaft 7 are formed with apertures 17 for the reception of rods 18 and the plates 9 are formed with radially extending slots 19 for the passage of the rods 18, thus guiding the stripper plates in their motion and preventing' them from completely leaving the mold space.

Carried by vthe outer end of the shaft 7 is a star wheel 20 having four radial slots 21' and cooperating with other parts of avGeneva movement serving to rotate the platen and its mold intermittently and hold the -same firmly with irst one and then 'another successively in locking relation. Suitable 24 into a slot 21 thus disengaging the roller i provisions are made for displacing the locking roller 26 at the instant the platen is to be advanced, and conveniently comprises a reciprocable rod 27 connected at one end to the free end oi the arm 25 and having its end 28 projecting into the path of the roller 24 in such manner as to be engaged thereby at the instant of the entrance of the roller 26 at the proper instant. If desired, I may emplo one of these star wheels 20 on each end o the shaftI 7 but for purposes of convenience of illustration I have omitted one of the same from the present drawings.

Secured to the inside faces of the uprights l are vertical rails 30 on which are slidably Vmounted the vertically reciprocable cross head 31. Thecross head 31 comprises in this case a horizontal rectangular bar 32 on which are loosely hung a plurality of massive tampers 33, each consisting of two parts split vertically andv bolted over the bar 32 in such manner as to be raised thereby, and fall therewith, yet to possess a certain amount of freedom of movement relative to the cross bar in order to minimize breakage. The lower ends 34-of the tamping members 33 are shouldered at 35, for the reception of the tamping heads 36 which are bolted thereto. This construction is adapted to enable the use of tamping heads of varying shapes .to conform to the particular shapes of the cores which vary with the shape of the mold, the nature of the concrete and the use to which the articles are to be put. Preferably a cushion spring device-37 is provided at the lower end of each rail, suiiiciently low down .not to be engaged bythe cross head in the ordinary operation of the device when the tamping heads are arrested by Contact with material in the mold, but in a position to arrest the movement of the cross headin case Y Carried by the uprights at one side of the crosshead 31 are brackets 38 in which is journaled the horizontal rockshaft 39 from which project the radial arms 40. articulated by links 41 to the cross head 31. Also projecting from one end vof this rockshaft is an operating arm 42 whose free end is articulated to a rod 43 whose opposite end vis pivoted at 44 to the upright projection. 45 of a lever 46 pivoted loosely on the shaft 7 and having at its free end Ma roller 47. Mounted on the shaft'22 is a massive gear wheel indicated generally at 49, and driven by a pinion 50 carried by the drive -shaft 51. Formed on the inner face of the gear wheel 49 are a plurality of

cams

52,53, and 54 Which cooperate with the roller 47 to thereby raise the arm 42 and with it the cross hea and allow it to drop periodically.

The outer face of theI gear wheel 49 is formed with irregularly shaped cams 55 and 56 adapted to engage a roller 57 mounted on one end of a rockshaft 58 pivoted to the frame members 4 and the other end 59 of which is connected by a link 60 to a. pinion' 61 engaging between a rack bar 62 mounted onthe machine frame and a similar rack bar 63 carried by a sliding material charger 64 by means of which the charger 64 is reciprocated from a position under the material hopper 65 to a position over the mold box l2. The cams 55 and 56 are so shaped and arranged that with each revolution of the gear wheel 49 the charger is carried from a position under the hopper 65over the mold box 12 and partly retractedv over the mold box 12 then fully retracted under the hopper 65 and again projected over the mold box 12 pausing over the mold box during each passage, and finally retracted to a position under the hopper 65.

The movements of the sliding charger 64 and of the tamper cross head 31 are so timed that each time the charger 64 is positioned over the mold box 12 the cross head 31 and its depending tampers 33 descend and force aportion of the material in the charger 64 downwardly into the mold box 12.- In each movement in the filling of the moldbox 12 the irst descent of the tamper is on a charger entirely filled with material, -the second descent of the tamper 33 takes place after the return of the charger 64 from the full projected portion when the molds are only partly full and the third descent of the tamper 33 takes place after the charger 64 has been again entirely filled and'advanced. The charger, when first advanced, is entirely filled with a continuousfiat sheet of the damp, plastic, cement-mixture, and the first blow of the tam ers carries the preponv derating quantity o .thisv mixture linto the mold,'a small portion of such mixture being excluded by reason of the obstruction offered by the core prints. As soon as the tamper is withdrawn, the charging frame is also with-- drawn, leaving in the mold all the mixture not previously forced therein by the tamper. Durlng the tlme that this charger is wlthdrawn the tampers again fall, and inasmuch as their force is this time expended upon the comparatively small amount of cement mix- ,ture the same is'compacted more densely.

tutes its forward edge removes surplus material from the top of the mold leaving the i block in a finished but rough-surfaced condirial in the mold box 12 so closelyasl does ifghts are spaced to overlap tion. Consequently, the weight of the vcross head and tampers being constant the force of the first blow does not compact the mate'- that of the second blow which is applied to a thinner' layer of material and the third blow of the tamper being applied to a full charger doesnot produce asgreat a compression of the'laSt layer as is given to the intermediate layer. This results in producing a building block having relatively porous surfaces where porosity is most desired land an intermediate band. ofV more highly compressed and consequently stronger material where strength is most needed.

When the mold has thus been lilled with compressed material the charger is retracted which causes the front gate 64 ofv the charger 64 to cut -oE any excess material projecting from the mold anddraw the same beneath the hopper' for the next char e. lArt this time the arm 23 carried by the s aft 22 is in position to enter 'a slot 21 of the star wheel 20 and further rotation of the shaft 22 'carries the star wheel and its connected to the lfront of the machine where it is in position to have a pallet 67 applied over the` open face of the mold box 12. This pallet consists of a bottom board 67 and an upright 67b at each end thereof. These u the end wa ls 'the mold box 12 and thelr edges are enagcd by pads 69. carried byv a pair ofspring ars 68 secured at their centers tothe side lwalls of the mold box12 and extending beyond the ,ends thereof, best shown in Figure 11; this holds the bottom of the allet securely against-the face of the tile. he attendant has ample timeto apply this allet during the filling ofthe next mold ox and upon the next succeeding quarter turn of the completed block is disposed directly beneath the shaft 7.

Loosely journaled on the rockshaft 58 are a 'pair of arms 70 carrying lcounterweights platen thel moldfcarrying the 66 and extending forwardly one on each side of the platen, and adapted to engage the ends of the rod 18 carried by the arms 16 of the stripper plates 15 when the mold is disposed below the shaft 7. These arms pass l below the shaft 22 which is provided with two cams 70a, one for each stripper arm,

preferably vhaving anti-friction rollers at their ends, 'and swinging at'the desired instant to depress the arms 70 and with it 4the rod 18 and -stripper plate and completed tile, the pallet being forced out from between the springs 68 at the Sametime. This movement brings the pallet into contact with two supports 72, carried by upright rods 73 as shown in Figures 7-10, or a plurality of rods 74, 75 as shown in Figure 5, mounted to slide in brackets 7 6 carrled by the front uprights 1 of the machine frame and normally maintained in raised position by counterweights 77.

The supports 72 are provided with verti cally extending bars 78 which also engage with the free ends of the arms 70 whereby the supports are forced downwardly.

The purpose of these counterweights is to restrain the tile against fallin coming broken .and their weight 1s preferablyy greater than that of the tile and pallet. The travel of the arms 7 0 is necessarily restricted by the fact that the rod 18 is limited by the ends of slots 19, and this motion is not enough to carry the tile completely out of contact with the rotor;

To accom- 10Bv l plish this I provide a pair of arms79 carried by a rockshaft 80 secured between the cross bars 4 of the machine and having an arm 81 arranged to cooperatejwith a cam 82 carried by the shaft 22 and against which it is held by means of a contractile spring 84 whereby thev supports -72 car pallet l67 and the completed bloc 71 are carried further downwardly until the pallet is disposed upon an endless carrier 85` by which it is conveyed away. Thereupon the platen is rotated one step while the arms 'ng the 9 are still vdepressed to hold 'the carriers 72l out of the way, after which both the arms 79 and carrier 72 are raised by the counterweights 7 7 .y

Plvotally secured to arm 59 of the -rock- 64 by frangible vpins 64b which brealr if any considerable pressure is applied to suoli front gate.

As shown in Figure 13 the cycle of operation is-as follows: The advance of the mold occurs during a 90 movement of the main shaft 22 while the tampers and strippers` are both elevated. After a 101 dwell a forward movement of the charger begins oocupying a second 90 turn of the shaft, the tamper being dropped once between the advance and retraction of the charger. The charger is now retracted during of rotation of said shaft and the tampers are dropped a second time, the strippers also being actuated vduring this interval..l The charger is again advanced during 70 of rotation, and the tampers dropped through the charger a' second time, making three tiines in all 'dwell of 20 completes the cyc e.

VFrom the above disclosure it will be obvious to those skilled in the art that I have provided a new and improved concrete block machine of very large capacity in which the movements necessary to turn out a completed block are carried on practically automatically and one in which the completed block has a porous surface where porosity is most desired and has a central band of greater density thereby providing a block having greater strength at the point where most needed.

It therefore will be apparent to those skilledy in the art that the embodiment of my invention herein shown and described accomplishes not only the principal object vof my invention but many others 'From the above disclosure it also will be obvious to those skilled in the art that the embodiment of my invention Aherein shown and described may be variously changed and .of any one size, shape, or material, since various sizes and shapes of mold box can be used and other plastic materials charged therein.

I claim:

l. In a concrete block'machine: the com- 1oination of a quadrilateral rotatable carrier, four radial molds on said carrier, four stations about said carrier, for filling, palletmenaces in the order named, and means for intermittently rotating said carrier by steps to present each mold successively to said four stations.

2. In 'a concrete block machine: a rotatable shaft, a mold, a charger, a tamper, and a single wheel on said shaft having cams on different parts thereof, whereby said charger, and tamper are presented to said mold in synchronized relation, one intermediate of the other.

3. In a concrete block machine: the coinbination of a mold, a reciprocable charger movable back and forth over. the same, and

adapted to deliver unequal amounts of conremoving it from, said charger and tamper,

means for operating saidtamper both through said frame, and after the withdrawal of said frame.

5. In a concrete block machine: the comhination of a rotatable shaft, a radially extending mold carried by said shaft, a pallet having upstanding end portions, end spring bars carried by saidmold for engaging the end portions of said, pallet to maintain the face portion of said,y pallet in position over said mold.

6. In a concrete block machine: the combination of a polygonal carrier, a mold on each face of said carrier, stations for lling, pallet-applying block-ejecting, and moldrestoring, to which said carrier moves s uccessively; a stripper, means for operating said stripper at a station removed from said filling station, and means operating at a station intermediate the stripping and lilling station to restore the stripper.

` 4. In a concrete block machine: the coinbination of a rotatable shaft, a radially extending mold carried by said shaft; a pallet having upstanding end portions, and means carried by said mold for engaging the end portions of the pallet, to maintain said pallet in position over said mold.

8. In a concrete block machine: the comioo bination of a mold, and means for tamping concrete mixture material in said mold, and means for feeding such mixture into said mold intermediately of the strokes of said tamping means, and meanscausmg the feeding of mixture in smaller increments to the mold when half full than at other times whereby the density of the block is varied at different points.

9. In a concrete block machine: the combination of a rotatable shaft, a radially extending mold carried by said shaft, means for intermittently rotating saidpshazft, a pallet having upstanding end portions, and means on said mold for engaging s aid upstanding portions and thereby to hold t e face portion of said pallet disposed over the lopen face of said mold.

- upstanding portions and thereby to ho d the face portion of said pallet disposed over the open face 'of said mold. 11. In a concrete block machine: the combination of a polygonal carrier,rmeans for rotatably 'mounting the same, a mold carried by eachI face of said carrier projectin radially therefrom, means for rotating sai carrier step by step for advancing said molds therearound, means for charging plastic material into one of said molds, and means for simultaneously dischar ing a completed block from another of said molds, and means for causing a dwell of each mold at a point between the charging, and discharging stations, to permit the application of a pallet Y thereto.

12. In a concrete block machine: the combination of a rotatable polygonal platen, a radially extending mold carried by each face of said platen, means for intermittently rotating said shaft, a sliding charger for feedfor appl 'n ina? ing material to said mold a tamper for compressing material in said mold, a station a pallet to said mold after the filling o d molda stri per to discharge a completed block onto said pallet, a station for restoring said stripper after such disand means operative during the charging, dwel o said mold at that station to restore layers and a central more compact layer is produced. v

14. In a concrete block machine: the combination o f a rotatable shaft, a radially exgo tending mold carried by said shaft; a tamper for compressing material in said mold; a' sliding charger synchronized to make a first f pause above said mold when said charger isA n filled with material, .a second pause beside Said mold after having dischargedthe resifor locking sai due of the rst charge of material into said mold, and a third pause when said charger is filled with material; tamper actuatin means for causing said `tamper to descend during each pause, whereby a block having outer less compact layers and a central more compact layer is produced, and means for:

stripping said block from'said-mold.

15.v In a concrete'block machine: the combination of a rotatable shaft; a radially eX- tending mold carried lby said shaft; means rotating said shaft; means shaft against rotation, a tamper for compressing material in said mold; asliding charger synchronized to make a first pause above saidmold when said charger is filled with material, a second pause beside said mold after having discharged the residue ofthe first charge of material into said mold, and a third pause for intermittently when said charger is 'iilled with materials l tamper actuatin means for causinggsaid tamper to descend during each pause, whereby a block having outer less compact layers and a central more compact layer is produced, and means for removing said block vfrom said mold.

16. Ina concrete block machine; the comf bination of a rotatable shaft; a radially. eX-

:tending mold carried by said shaft; means for removing a completed block from saidmold: and means for depositing said block on an endless carrier comprisin rods slidable in brackets affixed to t e machine.

frame, means for receivin Aa pallet carrying said block supported y said rods and downwardly slidable with said rods, and counterwei hts toreturn said supports after said pallet ias been disposed on said carrier.

17. In a concrete block machine: the com- -bination of a rotatable shaft; radially eX- tending mold carried by saidy shaft; means for intermittently rotating said shaft; means for removing a completed block from said mold; and means for depositing said block 1 on an endless carrier comprising: rods slidable in brackets vafliXed to the machine frame, means for receiving a pallet carrying said block su ported by said rods and downwardly slidah) weights t0 return said supports after said pallet has been disposed on said carrier,

18. In a concrete block machine: the combination of a rotatable shaft; a radially extending mold carried by said shaft; means for intermittently rotating said shaft; means for feeding material to said mold; means for-removing a completedv block from said mold; and means for depositing said lblock on an endless carrierv comprising: rods slidable in brackets affixed to the machine frame,.means forreceiving a pallet carrying said block supported by said `rods and vdownwardly slidable with said rods andv counterweights to return said supports after le with' said rods,`and countersaid pallethas been disposed on said carrier.

19. In a concrete .block machine: the combination of a rotatable shaft; a radially extending mold carried by said shaft; means for intermittently rotating said shaft; means for feeding material to said mold; means for tamping material into said mold, means for removing a completed block from said mold; and means for depositing said block' on an endless carrier comprisin rods slidable in brackets aiiixed to t e machine frame, means for receiving a pallet carrying said block supported by said rodsand downwardly slidable with said rods, and counterweights to return said supports after said pallet' has been disposed on said carrier.

20. vIn a concrete block machine: the coinvbination of a rotatable shaft, a radially eirtending mold carried by saidv shaft, means for intermittently rotating said shaft, means for feeding materialto said mold, a recip vrocable cross head carrying a tamper for compressing material in said mold, a camnied wheel and rockshaft operatively connected to said crosshead for reciprocatin said crosshead, and means for stripping said block from said mold.

21. In a concrete block'machine: the coin-A f bination vof a rotatable shaft, a radially extending mold carried by said shaft, means for intermittently rotating said shaft, a tamper for compressing material in said mold, a sliding charger synchronized to make a iirst pause above said mold when said charger is filled with material, a second pause when said charger is partially filled with material, and a third pause when said charger is filled with material; and tamper actuatingmeans for causing said tamper to descend during. each pause, whereby a block having outer less compact layers and a central more compact layer is pro- Y duced.

22. In a concrete block machine: the combination of a mold, a tamper for compressing material in said mold, a sliding charger synchronized to-make a rst pause above said mold when said char er is filled` with material, a second pause eside said mold after having discharged the residue of the rst charge of material into said mold, and a igeaoca mold and tamper actuating means synchroi 24. In a concrete block machine: the coini bination of a rotatable shaft, a radially extending mold carried by said shaft, means for intermittently rotating said shaft, a sliding charger for feeding material to said mold, a gear wheel for intermittently rotating said shaft,l cams carried by one face of said gear wheel for recipro/cating said charger a plurality of times during each rotation of said wheel, and other cams carried by the other face .of said gear wheel for causin a descent of said tamper a plurality of times during each rotation of said gear wheel.

25. In a concrete block machine: the combination of a rotatable shaft, a radially extending mold carried by said shaft, tamper means for successively tamping the mixture carried in said mold, a sliding charger for supplying the mixture to said mold, and means for sliding said charger so constructed and arranged that said charger pauses twice above said mold for permitting said tamper means to tamp said mixture in said mold through said charger, and said charger pauses once beside said mold for permitting said tamper means to tamp said mixture in said mold independently of said charger.

26. In a concrete block machine: the combination of a rotatable shaft, a radially extendingmold carried by said shaft, tamper means for successively tamping the mixture carried in said mold, a sliding charger for supplying the mixture to said meld, anda cam and rockshaft means for slidin said charger so constructed andvarrange that saidv charger pauses a plurality of times above said mold for permitting said tamper i means to tamp said mixture in said mold through said charger, and said charger pauses once beside said mold for permitting said tamper means to tamp said mixture in said mold independentl of said charger.

27. In a concrete bloc machine: the combination of a rotatable shaft a radially extending mold carried by said shaft, tamper means for successively tamping the mixture carried in said mold, means for intermittently rotating said shaft, a sliding charger for supplying the mixture to said mold, andr means for sliding said charger so constructed and arranged that said charger pauses twice above said mold for permitting said tamper means to tamp said mixture in said moldthrough said charger, and said charger pauses once beside said mold for permitting said tamper means to tamp said mixture in said mold independentlyof said charger.

28. In a concrete block machine: the combination of a rotatable shaft, a radially extending mold carried by said shaft, tamper means for successively tampin the mixture in said mold, means for intermittently rotatling said shaft, a sliding charger for supplying the mixture to said mold, and cam and rock shaft -means for slidingv said charger so constructed and arranged that said charger pauses twice above said mold for permitting said tamper means 1totamp said mixture in said mold through said charger, and said charger pauses once beside said mold for permitting said tamper means to tamp said mixture in said mold independently of said charger. Y 29. In a concrete block machine: the combination of a rotatable shaft, a radiall extending mold carried on said shaft, a sliding charger for sup lying material to said mold tamper means or tamping materialin said mold a plurality ofv strokes, said tamperA means bein so positioned rand arranged that the first a Vance of said tamper means is through said charger, the second advanceof said tamper means is directly into said mold, 4while the third advance of said tamper l means is through said charger, whereby a block having its outer layers of relatively lporous material and a central la er of relawhi e the third advance of said tamper means is through said' charger, whereby a block having its outer layers ofrelatively porous material and a central layer 'of relatively dense materialis roduced.

In testimony whereo I hereunto ax signature,y

CHARLES M. EBERLING.