US 2306427 A
Description (OCR text may contain errors)
J.. B. CHRISTMAN ETAL 2,306,427U
GRAVEL TREATING DEVICE I Fil'ed Jan. 8, 1941 JUL/U513. CHe/sT/m/v m0 JUL/U5 5. 6112/3 TMAMJQ. INVENTORS 1 TTE/VEKS.
Patented Dec. 29, 1942 UNITED STATES PATENT OFFICE,
GRAVEL TREATING DEVICE Julius B. Christmanand Julius B. Christman, Jr.,' South Bend, Ind.
Application January 8, 1941, Serial No. 373,540
This invention relates to gravel treating devices, and more particularly to devices by means of which soft stone can be eliminatedfrom gravel aggregate.
Many gravel deposits include both hard and soft stones. Soft stone is of such a character that it maintains its individual identity and structural characteristics in normal gravel treating processes, such as crushing and screening. However, its presence in gravel in amounts exceeding certain low percentages renders the gravel unsatisfactory for certain uses, such as for roads. Therefore, soft stone must be eliminated from gravel aggregate to meet the specifications for high grade gravel. The most common method of eliminating soft stone is to employ hand pickers for manually removing the soft stone from the aggregate. This method is objectionable because of the time required for it and because of its expense.
Various attempts have been made to devise a machine which will satisfactorily-eliminate the soft stone from the gravel aggregate. These prior machines have proven unsatisfactory or unsuccessful for various reasons. One of these reasons is that considerable pressure .or heavy impact is required to break the soft stone. Previous devices have not been successfulin applying pressures sufliciently high to break the soft stone, and at the same time low enough to prevent the breaking of the hard stone in the aggregate. Another reason for the failure of previous devices has been that they have not been able to accommodate the variations in size of the hard stone of the gravel aggregate.
For example, devices which would permit all of the character having a driven metal roll provided with a corrugated or longitudinally grooved periphery, and an idling roll having a hard rubber peripheral layer.
A further object is to provide a device of this character utilizing a pair of juxtaposed crushing rolls, with gravel retaining flanges mounted on the ends, of one roll and spaced" apart sufficiently to clear the ends of the other roll when said rolls are positioned in crushing relation.
A further object is to providea device of this character wherein a driven metal roll having a longitudinally corrugated periphery and enlarged ends is journaled on a frame to rotate about a fixed axis, and a rubber covered idler roller shorter than said driven roll is journaled in bearings adjustably mounted on said frame.
Other objects will be apparent from the description and appended claims.-
In the drawing:
Fig. l is a top plan view of the device.
Fig. 2 is a vertical longitudinal sectional view taken on line 2+2 of Fig. l.
Referring to the drawing, ,which illustrates the preferred embodiment of the invention, the nu- .meral Hl designates the legs of a frame which hard stone of the aggregate to pass therethrough without breaking thereof, did not break a sufiicientproportion of the softstone to be successful for the intended purpose; while devices which would break the required proportion of the soft .stone could not permit the passage of hard stone therethrough unbroken.
Therefore, it is the primary object of this invention to provide a device of this character which compensates for the factor of size variation of the gravel aggregate, and which accurately gauges the pressure applied so that only the soft stone is broken.
A further object is to provide a device of this character comprising a pair of juxtaposed crushing rolls, wherein one of said rolls is formed of metal and the other has a hard rubber peripheral covering.
A further object is to provide a device of this also comprises side bars II preferably formed of metal channels, end bars I2, cross braces. l3, and lower longitudinal-frame bars l4.
A plate I5 is mountedupon the top of the frame at one end thereof and supports an electric driving motor 16. The shaft ll of motor 16 mounts a pulley [8 which is preferably provided with a plurality of V grooves therein. A
, plurality of drive belts l9, each mounted in one of the grooves of the pulley I8, extends to and around driven pulley 20. Pulley 20 is mounted upon a transverse shaft 2| journaled upon the frame elements II by bearings 22. At its opposite end, shaft 2l mounts a gear 23. Gear 23 meshes with a gear 24 mounted on one end of a shaft 25 which is journaled upon frame elements II by bearings 50. 'The opposite end of shaft 25 mounts a gear ZG which meshes with a gear 21. Gear 21 is mounted upon a shaft 28 which is journaled in bearings 29 fixedly carried by the frame elements H.
Shaft 28 fixedly mounts a metal roll or cylinder 30. R011 30 is preferably provided with a plurality of'longitudinally extending concave grooves 3| substantially equispaced around its periphery. Enlarged concentric end plates orflanges 32 are fixedly mounted on the opposite ends of the roll 30 for purposes to b hereinafter set forth.
Bearings 33 are adjustably mounted upon the 38 is threaded at its inner end for engagement with a portion 40 depending from bearing 33 and extending through slot 34 of member The outer end of each shaft 38 mounts a hand A transverse shaft 42 is suitably journaled on frame elements |4 below the roll 30. Shaft 42' mounts a pulley 43 over which a belt 44 is trained.
Belt 44 extends to any suitable discharge point.
A feed hopper 45 is suitably supported above the device in vertical alignment with the adjacent peripheries of the rolls 3B and 36-3'|.
The operation of the device is as follows:
Gravel is fed in a controlled flow from hopper 45 to the rolls 30 and 363'|. The gravel so fed is retained in desired relation to the rolls by the flange 32 of the roll 35 which prevents the gravel from escaping at the ends of the rolls. Roll 31' is an idler while the roll 3|] is positively driven. As the roll 30 rotates, it carries the gravel therewith between itself and roll 31. The roll 31, being formed of rubber, has a certain degree of compressibility and this is sufiicient to permit hard stones to pass between the two rolls without being broken thereby. However, the rubber 31 is hard enough to coact with the roll 3|] for the purpose of crushing soft stone passing between said rolls. Hence, the use of the rubber 31 of the character described automatically permits the application by the device of a pressure sufficient to break the soft stone but not sufficient to break the hard stone.
The grooves 3| in the face of roll 35 are important for several reasons. lar purposes of these grooves is to form a seat for receiving large stones, so that the same are positively impelled between the two rolls. Also, when large stones seat within the grooves 3|, the
pressure applied thereto is substantially reduced to prevent breaking thereof and to prevent undue wear upon the rubber. It will be understood that the particular size, contour, and number of.
grooves 3| may be varied substantially as desired and in accordance with the predominant characteristics of the gravel which is to be treated thereby. Thus, where gravel contains a large proportion of large stones, it will be desirable to make the grooves 3| deeper and wider than is necessary where the stones are smaller and more uniform in size. In cases where substantial uniformity of size of the stone occurs, it may be necessary to provide only very shallow grooves in the roll 39, primarily for the purpose of roughening or contouring said periphery to insure a positive feed of the gravel thereby between the two rolls.
It will .be observed-that when the gravel is discharged from the rolls 35 and 31, it may fall upon the belt 44 to be conveyed thereby to a suitable discharge point, such as to a scrubber or a screener. The scrubber will serve to eliminate the dirt which may adhere to the hard stones and On of the particuwhich may consist in part of the broken soft stone.
It will be understood that the percentag of soft stone which is retained in the gravel aggregate after it has passed through the device will depend in some measure upon the character of the grooves 3| in the roll 30. Thus, it will be obvious that the larger and deeper the grooves 3| in the roll 30, the more soft stone of smaller size will be permitted to pass through the device without being broken. For this reason, it will be desirable to limit the depth of the grooves 30 to the shallowest depth which will permit passage of larger stones through the device.
As seen in the drawing, the driving connection between the motor and the shaft 33 substantially reduces the speed at which the roll 33 rotates. Thus, it will be noted that gears 23 and '26 are each much smaller than the gears 24 and 27 respectively, which mesh therewith Likewise, the pulley'ZD is substantially larger than the pulley I8 of the motor |6. In this way, any suitable motor, for example a 15 H. Pl motor operating at 1200' R. P. M. may be utilized to drive the device, and the driving connection will reduce the speed of operation so that the roll 35 will rotate 'very slowly, as is essential to prevent throwing of the gravel.
A certain degree of adjustability is provided in the device by virtue of the operative association of the shafts 38 with the portion 49 of the bearing 33 which journals the shaft 35 mounting the idler roller 363'|. It will be obvious that rotation of the shaft 38 in one direction will urge the roll 33-3! toward, and press it tightly against, the roll 30; while the reverse operation of the shaft will shift the roll 36-31 away from the roll 36. This movement of the roll is guided by the guide slots 34 in the frame member IL This adjustability permits the device to be conditioned for the particular characteristics and predominant size of the gravel aggregate to be passed therethrough.
The selection of rubber of proper hardness to crush soft stone, and of sufficient compressibility to permit hard stone to depress the same is important. However, the conditions to which the rubber is subject are quite similar to those for which automotive tires, and especially solid truck tires, are designed; and, hence, the rubber may be selected by comparing it with the properties of the rubber of such tires. When the proper rubber is employed, and the device is properly adjusted for its work, the wear of the rubber will be slight and the rubber will not be cut or gouged by the gravel.
VJ e claim:
A gravel treating device comprising a supporting frame, a pair of parallel crushing rolls journaled transversely of said frame, one of said rolls having a longitudinally corrugated metal periphery and the other having a hard rubber peripheral covering, said metal roll having circular flanges of a diameter larger than said roll projecting therefrom in concentric relation at the ends thereof and spaced apart a distance slightly greater than the length of the other roll, means for driving said metal roll, and means for laterally shifting and locking said rubber covered roll on said frame in selected position relative to said metal roll, said rubber covered roll being an idler.
JULIUS B. CHRISTMAN. JULIUS B. CHRISTMAN, JR.