US 2273772 A
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Description (OCR text may contain errors)
Feb. 17, 1942. H. c. PQLUTZ 2,273,772
Filed April 2, 1940 INVENTQR. /7'I4ROLD C. POLL/TZ 7 ArraR/yfx Patented Feb. 17, 1942 UNITED STATES PATENT OFFICE CRUSHER Harold C. Pollitz, Cedar Rapids, Iowa, assignor to Iowa Manufacturing Company, Cedar Rapids, Iowa, a corporation of Iowa Application April 2, 1940,, serial No. 227,379y
4 claims. v(ci. :za- 12) This invention relates to material crushing devices and has particular relation to means for protecting such devices against distortion or breakage because of overloading or like stresses.
An overload release means' constructed in accordance with the invention hereinafter described is particularly well adapted for use in connection with the type of device known as a roll crusher, in which a pairof rock crushing rolls are supported for rotation on a pair of parallel shafts and in which one'roll is biased toward the other by means of heavy springs bearing against one of the shafts.
In devices of this character, when an overload is placed on the machine, as for example, if a piece of rock, iron, or other foreign material of such hardness or size as to be beyond the capacity of the crusher to handle, is fed into the crusher, the heavy compression springs may be compressed to their fullest extent or bottomed with each coil bearing against the next. The springs are so heavy that the available space between coils is small, on the order usually of one to two inches. When this point is reached or exceeded, deformation or breakage of the axles, the spring backing plates, the crusher frame, or some other parts of the machine results.
A principal object of my invention is to provide means, in a roll crusher, for concentrating the thrust of the rolls on one or two inexpensive, readily replaceable elements and to so design, place and form these elements that the stress concentrated thereon is one pure stress only as, for instance, a shearing stress, which may be readily computed under overload conditions.
Another object of my invention is to provide, in connection with the stress concentrating means above mentioned, one or more inexpensivc, readily replaceable elements the total shearing stress of which' may be readily computed and determined. i
Another important object of my invention is to provide a roll crusher structure in which a safety link is employed and in which breakage of the safety link will permit a relatively large movement of the rolls to permit any oversize aggregate or unusually hardlaggregate to pass between the rolls without injury to the machine.
A further object of my invention is the provision, in a safety device for a crusher, of a shearable or breakable member of such construction as to permit ready replacement with one or more other similar shearable members having an ultimate strength suitable for use on the particular job to which the crusher is being applied.
Still another object of my invention is to provide, in a roll crusher,-new and improved adjustable spring compressing means. I
Other and further features and objects of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawing and vfollowing specifications, wherein is disclosed a single exemplary embodiment of the invention, with the understanding, however, that such changes may be made therein as fall within the scope of the appended claims, without departing from the spirit of the invention.
In said drawing:
Figure 1 is a view in elevation of a roll type crusher embodying' as stress concentrating and Overload release means or 'safety `device constructed in accordance with one embodiment of my invention.
Figure'2vis a view inperspective in exploded relation illustrating the parts of the overload release means shownin Figure 1, and
Figure 3 is a fragmentary view, partly in side elevation and partly in section, illustrating the various parts of the overload release structure shown in Figure 2 as they appear when assembled.
Referring now to the drawing:
I have illustrated, in Figure 1, a more or less representative type of roll crusher to which a stress concentrating and safety release means, constructed in accordance with one embodiment of my invention, has been applied. I
Such a structure comprises, in general, a base IU and a pair of crusher rolls Il and l2. One of these crusher rolls is mounted on a shaft |3 which is, in, turn, rotatably mounted in a pair of fixed journal boxes I4. I The other roll is mounted on a shaft l6 which is also supported for rotation in journal boxes ll, which boxes are slidably mounted above the main frame in accordance with usual practice.
Replaceable shims, shown at [8, are disposed between Spacer members 20 mounted above the frame and the slidable journal boxes. These shims act as stops and permit ready adjustment of the rolls to produce an aggregate of the desired size. A hopper 2I is mounted in fixed position above the rolls for receiving rock to be` crushed.
One of the crusher rolls is provided with a sprocket wheel (not shown) or a pulley or the like for applying power to the roll. The other roll may be driven from the first mentioned roll by any conventional means, such as a chain and sprockets, or by meshed gears mounted on the roll shafts.
Heavy compression springs |9 are preferably provided to bias the movable crusher roll |2 toward the fixed roll ll, and it Will be apparent that the entire crushing load or force eXerted on the crushing rolls will be concentrated in these springs and that this force is substantially unidirectional. this point in the structure, the load concentrating and safety overload releasing device, indicated generally at 22 in Figure 1 and in detail in Figures 2 and 3, for concentrating the load in one area and producing a uni-directional stress which may be resolved into pure shear.
This overload concentrating and releasing structure includes a shearing plate 23 against which one of the springs is adapted to bear. This plate is provided with an opening 24 in which a shear block such as the nut, shown at 26, is slidably received. The nut or shear block is peripherally slotted or recessed, as at 21, to receive a plate-like or annular shearable member 28-28. This shearable member is preferably in the form of a split washer and it is desirable that the shear plate be recessed, as at 29, to receive the washer and thus hold it in its proper position.
A pressure adjusting rod 3l is threadedly received in the shear nut 26. This adjustment red is mounted in an opening 32 drilled through a cross member 33 of the main frame, and is provided with a shoulder 34 to bear against the cross member. A head 36 for turning the rod, is aflixed to the rod by means such as the pin 31', and the pressure on the springs may, of course, be regulated as desired by turning the rod.
It will be obvious, now, that the washer 28--28 will be subjected to the concentrated load or thrust on the rolls, and this load will be transmitted to the washer in the form of practically pure shearing stress. Cbnsequently, the thickness and nature of the material from which a shear washer may be made may be readily computed for protecting a device of this nature against any given overload.
It should be noted, in the device herein described, that the adjusting screw or rod 3| does not extend beyond the end of the frame at any time. This is a distinct advantage over the usual structure since, for practical purposes, it shortens up the device as well as removes the danger of catching the clothes of passing workmen.
Although I have described a specific embodiment of my invention, it is apparent that modifications thereof may be made by those skilled in the art. For example, it may be desirable to utilize lighter springs and still operate a crusher under a heavy pressure. In such case, a plurality of lighter springs may be placed in multiple I have, accordingly, provided, at
relation with a single shearable member so disposed as to be subjected to the entire load on all the springs. Such modications may be made without departing from the spirit and scope of my invention as set forth in the appended claims.
I claim as my invention:
l. In a rock crushing device, an overload release means including an adjusting screw, a shear nut threadedly received on the adjusting screw, a shear plate having an opening therein for slidably receiving the shear nut, and a replaceable plate-like shearable member adapted to be received between the shear nut and the shear plate.
2. In a rock crushing device, an overload release means including an adjusting screw, a shear nut threadedly received on the adjusting screw, the shear nut having a circumferentially extending slot, a shearable member received in the slot and extending beyond the edges of the shear nut, a shear plate having an opening extending therethrough, said opening adapted to slidably receive the shear nut, and means for retaining theV shearable member in position in the slot of the nut.
3. In a rock crushing device, an overload release means including an adjusting screw, a shear nut threadedly received on the adjusting screw, the shear nut having a circumferentially extending slot, a shearable member received in the-slot and extending beyond the edges of the shear nut, a shear plate having an opening extending therethrough, said opening adapted to slidably receive the shear nut and to prevent rotation thereof, and means comprising a recess in the face of the shear plate for receiving the shearable member and holding it in position in the slot of the nut.
4. In a rock crushing device having a pair of rolls mounted in a frame, means for resiliently biasing the rolls together, for adjusting the operating pressure and for releasing the rolls under over-pressure, comprising an adjustment screw mounted for rotation in the frame but held against movement longitudinally thereof, a spring member disposed opposite the adjusting screw, a shear plate having an opening therethrough and bearing against the spring means, a combined shear and adjusting nut slidably but non-rotatably mounted in the said opening, the said nut having a peripherally extending slot therein, and a split washer-like shearable member disposed in the peripheral slot and bearing against the shear plate on the side thereof opposite the spring, the rotation of the adjustment screw thus adapted to adjust the shear nut and thereby the operating pressure without placing any additional new stress on the shearable member other than pure shear.
HAROLD C. POLLITZ.