US3812967A

US3812967A - Screening and comminuting device

Info

Publication number: US3812967A
Application number: US00329585A
Authority: US
Inventors: S Rudzinski
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-02-05
Filing date: 1973-02-05
Publication date: 1974-05-28
Anticipated expiration: 1991-05-28
Also published as: AU6508474A; CA1025414A; GB1463559A

Abstract

A device for comminuting and screening solids in a stream of fluid material having a conical rotary screen on which cutters are mounted for coaction with stationary cutters and which is formed for circular elements of sequentially increasing diameter and spacing therebetween supported on an axle by precut ribs and on which cam locks hold cutting elements at preset angles to the direction of rotation, the screen being driven at its largest diameter be a flexible belt and supported at both ends in a flow directing enclosure for unitary installation in a flow channel.

Description

United States Patent [1 1 Rudzinski [45] Ma 28, 1974 i 1 SCREENING AND COMMINUTING DEVICE Primary Examiner Roy Lake [76] Inventor: Stanley P. Rudzinski, l 156 S. Assismm ""P Jones Lombard Ave. Oak Park I. 60304 Attorney, Agent, or F1rm-Jarrett Ross Clark [22] Filed: Feb. 5, 1973 [57] ABSTRACT [2]] App! 329585 A device for comminuting and screening solids in a stream of fluid material having a conical rotary screen [52] U.S. CI. 210/174, 210/77 0" which Cutters are mounted for coactioh with [51 Int. Cl. C020 1/22 tionary cutters and which is formed f r ircul r ele- [58] Field of Search r. 210/174, 152, 77, 79 menls of sequentially increasing diameter and Spacing v therebetween supported on an axle by precut ribs and [5 R m- Cited on which cam locks hold cutting elements at preset angles to the direction of rotation, the screen being UNITED STATES PATENTS driven at its largestdiameter be a flexible belt and 2,336,069 12 1943 Chase 210/174 Supported at both ends in a how directing enclosure for unitary installation in a flow channel.

' 18 Claims, 10 Drawing Figures PATENTEDIAYZWH amass? I am 1. 0f 3 I IJJ l -f lllll thereof by large solid pieces.

1 SCREENING ANDCOMMINUTING DEVICE The present invention'relates to an improved device of the type described and claimed in my U. S. Pat. No. 3,074,555, issued Jan. 22, 1963, for screening and comminuting solids in a stream of fluid material such as the solids occurring in the fluid in sewage treatment plants and in drainage and other fluid treatment systems.

It is a general object of the present invention to provide an improved rotor construction and support for screening and comminuting devices of the type having a rotating cutting and screening assembly. A related object is to provide a more uniform distribution of solids to the cutting and screening elements and of fluid flow through the rotor.

A more detailed object of the invention is to provide an improved means for mounting individual cutters on the rotor to simplify adjustment and replacement. It is also a purpose of the invention to mount the cutters for better cutting action and for minimizing jamming A further aim of the present invention is to provide an improved drive for the rotor which is more flexible in application and permits easier maintenance.

It is also an object of the invention to provide an improved method of constructing the rotor to increase stability of rotation and alignment and to reduce the cost of manufacture.

The foregoing objects and others which will become apparent from the specification are intended toprovide a device adapted for unitary installation in fluid flow channels or conduits of various forms and construction and which is capable of efficient service and low cost maintenance under the adverse conditions of corrosion, widely varying levels of flow and diverse types of solids occurring in sewage treatment and other fluid treatment systems.

The following is a detailed description of the preferred embodiment of the invention taken in connection with the accompanying drawings in which:

FIG. 1 is a perspective of a screening and comminuting device embodying the present invention and positioned in a portion of an exemplary fluid flowchannel;

FIG. 2 is a side elevation of the device of FIG. 1; FIG. 3 is a rear elevation of the device of FIG. 1; FIG. 4 is a side elevation of the radial support for the screening elements showing the method of assembly;

FIG. Sis a front elevation of the structure of FIG. 4;

FIG. 6 is an exploded partial perspective ofa screening element with a cutter and locking device;

FIG. 7 is a partial top view of a screening element with a cutter and locking device assembled;

FIG. 8 is a side view of a locking element for the cutters;

FIG. 9 is a partial perspective of a stationary cutter bar, cutters and shield; and

FIG. 10 is a partial plan view of a modified cutter arrangement showing the relation of the movable and stationary cutters.

Referring to the drawings in more detail, an improved comminuting and screening apparatus 10 embodying the present invention is shown adapted for use in a rectangular liquid flow channel 11 which may carry sewage or other fluid having solids which must be comminuted or removed prior to treatment or discharge, As shown in FIG. 1, the apparatus comprises a rotor 12, a support structure 13, a drive mechanism 14 and flow directing means. Carried by the rotor 12 and support structure 13 are cooperating movable and stationary cutting units l7, 18 for cutting and comminuting solids contained in fluid flowing in the channel. In the assem- FIG. 1, the fluid flow i s [1311 left to right and for convenience in describing the mechanism hereinafter,

the upstream or left end of the assembly will sometimes .be'referred to as the front and the downstream or right end will be referred to as the rear of the assembly.

The apparatus of the present invention has a single driven part which is the rotor 12. To provide a durable and solid mounting for the rotor, front and rear bearings or

journals

19, 20 carry a rotor axle or shaft 211. for rotation on an axis that is substantially parallel to the direction of liquid or fluid flow. The support structure is formed by a fore and aft base plate '22 extending for approximately the length of the rotor shaft 2], and in the form shown in the drawings for a square or rectangular channel is a flat plate lying on the bottom wall of the channel. Mounted on the front and rear portions of the base 22 and aligned with the midline of the base are front and rear

vertical support columns

24, 25. At the upper ends of the columns, flat horizontalsurfaces are formed by cross members or plates 26. To these horizontal surfaces are attached the

bearings

19, 20 for re ceiving the front and rear end portions of the rotor shaft 21. The bearings are secured to the support columns by bolts 27 or other suitable fastening means.

The rotor 12, as further described in US. Pat. No. 3,074,555, is of conical shape but may be of other shapes formed as surfaces of revolution which increase in diameter from one end to the other. In practicing the present invention, the rotor 12 is constructed to in crease its resistance to distortion from impact and uneven fluid flow and to reduce the cost of manufacture. For these purposes, the rotor is supported on the shaft 21 which extends from the front to the rear of the rotor with portions projecting from each end for insertion into the front and

rear bearings

19, 20. Assembled on the axle shaft 21 are radial ribs 29 pf generally triangul'ar shape and which on their outer sloping edge have been formed with steps 30 for receiving circular screening bars 31. As'best seen in FIGS. 4 and 5, the ribs 29 are spaced at equal angles around the circumference of the axle shaft 21, being four in number in the illustrative embodiment and spaced at ninety degree angles around the shaft. Preferably, the ribs 29 are cut from steel plate, stacked together and machined as a unit to provide accurate alignment of the edge configurations. The ribs 29 are then placed in their respective radial positions around the shaft 21 and are held in position by appropriate fixtures 32. As shown in FIGS. 4 and 5, the fixtures 32 may be triangular plates which extend between adjacent ribs 29 with their edges generally parallel to the sloping outer edges of the ribs. Outwardly bent flanges 33 on the edges of the fixtures have holes which mate with holes in the ribs for receiving bolts 34 to hold the ribs and fixtures in a fixed position about the axle shaft.

In the preferred form of the rotor, the circular screening bars 31 are also cut or formed from flat steel plate as rings or annuli and are then machined on their inner diameter to match the radial spacing of the respective steps 30 on the ribs 29. For use with the form of ribs of FIGS. 4 and 5, the inner circular face of the bars is formed as a cylinder to mate with the corresponding axially directed steps 30 of the ribs while the outer circular faces may be formed either as cylindrical surfaces or as frusto-conical surfaces. An example of screen rings 31 with cylindrical outer surfaces is shown in FIG. while frusto-conical surfaces are shown in FIGS. 2 and 6. At this time, slots 37 are cut in the outer surfaces of the screen bars for receiving cutter bits 17 and suitable holes 38 and counterbores 65' adjacent each slot are made for locking means to hold the bits 17 in place as will be described in more detail hereinafter. After machining, the screen bars 31 are placed on their respective steps. The ribs and screen bars are then fastened in place, as by welding, with the inner edges of the ribs 29 fixed to the axle shaft 21 and the bars 31 fixed to the stepped edges of the ribs. When the welding is completed the fixtures 32 are removed and the rotor is ready for insertion in the

bearings

19, 20.

For the purpose of insuring accurate alignment of the bearings 19, and the rotor 12 on the base support the bearings are placed on the projecting end portions of of the rotorv shaft 21, and the bearings and rotor are then placed on the receiving surfaces 26,0f the rotor support columns 24, as a unit. Holes are now made in the mounting plates 26 on the columns for receiving fasteners 27, orif desired, locating pins may be used in addition to the fasteners 27. By this procedure, the comminuting and screening apparatus can be delivered and installed as a unit without the necessity of adjusting the bearings at the time of installation.

In another aspect of the present invention, an .improved drive mechanism has been provided for driving the rotor. In the form shown in the drawings, means are provided for directly driving the rotor 12 through a drive mechanism attached to the circumference of the rotor at its largest diameter. In the preferred form, the drive mechanism includes a sprocket ring 39 which together with seal and

spacer rings

40, 41 are fastened by bolts 42 to the rear of the last screening bar 31 for unitary rotation. To obtain the desired driving forces, the outside diameters of the sprocket ring 39 and largest screening bar 31 are substantially the same. Unobstructed outlet flow from the rotor is obtained since the inner diameters of the three

rings

39, 40, 41 are the same or slightly larger than the inner diameter of the last screening bar 31. The seal ring 40, however, has a slightly larger outer diameter than the other circular elements to permit its coaction with surrounding baffle means while the outer diameter of the spacer ring 41 is somewhat smaller to give clearance for the teeth on the sprocket ring 39. By the foregoing construction, the drive mechanism including the sprocket ring 39 is shielded from the direct force and flow of the fluid. The drive sprocket ring 39 and its associated mounting rings 40, 41 may be attached to the rotor before the assembly fixtures 32 are removed from the ribs so that alignment is accurately maintained. As shown in FIG. 2 of the drawings, the drive sprocket ring 39 is placed inboard, that is, in front, of the rear rotor support column 25 to further minimize any tendency for the rotor to be drawn out of alignment by driving forces or shocks from cutting hard materials.

Surrounding the drive sprocket ring 39 is a drive chain 44 which leads upwardly to an overhead drive transmission 45 and source of power, such as an electric motor 46. The output shaft of the transmission 45 carries a sprocket gear'47 around which the upper portion of the chain 44 is trained'to complete the drive. To maintain tension on the chain 44', an idler sprocket 49 engages the outer side of the chain 44 at a point between theringsprocket 39 and the sprocket gear 47 and above the top of the rotor 12 to keep'the sprocket 49 out of the flow of fluid. The idler sprocket 49 is journaled on a short arm 50 which is pivoted at its lower end to a vertical rear baffle plate 60. A spiral spring, not shown, located around the pivotal mounting for the idler arm 50 presses the idler sprocket 49 against the chain 44 to take up any slack in the chain and provide ,the desired chain tension. The idler sprocket 49vis placed in the return flight of chain, that is, the portion of the chain that is moving downwardly from the transmission sprocket gear to the ring sprocket. If it is desired to have the rotor direction reversible, two idler sprockets, one on each flight of chain can be used to maintain tension in either direction of rotation. To protect the rotor and drive mechanism in case of shock or jamming of the rotor, it is desirable to limit the maximum driving force by means of a preset overload clutch in the transmission or an electrical overload cutout in the motor circuit.

With the present drive mechanism, great flexibility and protection in installation and use is achieved. The apparatus of the present invention may be easily adapted for many different mounting positions of the drive motor 46 and transmission 45. The mounting illustrated in the drawings is formed by a pair of vertical side supports or legs 51 extending upwardlyfrom the bottom base plate 22 at the respective sides of the apparatus out. of the way of the stream of fluid. A cross plate 52 on the top of the legs 51 forms a platform on which the motor 46 and transmission 45 are mounted. It is apparent that depending on the requirements of a particular installation, the legs 51 may be made longer or shorter to raise or lower the drive transmission 45 to the appropriate height without changing any other portion of the apparatus except for the use of a drive chain 44 of suitable length. The motor 46 and transmission 45, if necessary, can also be mounted entirely separate from the remainder of the apparatus, such for example, as on the upper ends of the channel side walls.

To direct the flow of fluid to and through the rotor screen an arrangement of baffles and shields surrounds the rotor assembly 12. To this end, provision is made for not only controlling fluid flow but also for providing ready access to the mechanism for maintenance and adjustment and for safety in the event of unexpected upstream pressure on the rotor screen. For this purpose, upright side walls 54, 55 are fixed to the longitudinal edges of the bottom base plate 22. They extend upwardly therefrom to above the seal ring 40 and rearwardly from forward of the front rotor bearing 19 to at least the rear one of the rotor screen bars 31 for channeling fluid flow along the sides of the rotor. The side walls 54, 55 may also provide added support for the drive mechanism by fastening the support legs 51 to the rear edges of the sidewalls. Preferrably at least one of the side walls 55- has a removable upper portion which as shown in FIG. 1 is a sliding panel 56 engaged at its front and rear ends by pairs of horizontally spaced apart vertical bars 57 forming vertical slideways. Additional flow control is provided by front and rear transverse

vertical baffle panels

59, 60 which are attached at their bottom edges to the front and rear edges, re-

spectively, of the bottom base plate 22 and at their vertical edges to the adjacent vertical end edges of the side walls 54, 55 and to the vertical slideway bars 57. The center portion of each end baffle has a circular opening 61, 62 which defines respective fluid inlet and outlet openings of a diameter corresponding to the largest diameter of the rotor 12. The rear baffle panel 60 is positioned such that it is aligned with the seal ring 40 on the rotor and forms a relatively close fit therewith to prevent or reduce flow around the outside of seal ring 40 and hence to prevent or reduce the bypassing of fluid around the rotor screen and cutters. interposed between the front and

rear baffles

59, 60 is a semicylindrical baffle 63 extending longitudinally of, and below, the rotor 12. The concave side of the baffle 63 faces upwardly enclosing the lower portion of the rotor and has an inner diameter substantially equal to that of the flow openings 61, 62 in the end baffles. This fore and aft baffle 63 serves to smooth out the fluid flow and reduce turbulence which would otherwise exist in the lower part of the space enclosed by the baffles.

Enclosing thetop of the apparatus is a cover panel 65 which is fastened to the front baffle plate 59 by hinges 66 at its front edge for upward swinging movement of its rear portion. in the closed position, the edges of the cover panel 65 rest on the top edges of the side and end panels. The cover panel serves both to protect the mechanism from solid objects which might be dropped on it and to prevent persons from contacting the moving rotor and being injured. In addition, it provides a safety escape for fluid should an excessive pressure develop within the baffle enclosure. in such a case the rear portion of the cover panel 65 willrise and permit excess fluid to spill over the rear baffle 60 to the downstream side of the apparatus. The hinged cover panel 65 and the removable side panel 56 also permit ready inspection and access to the rotor and cutting mechanism for repair and adjustment.

It is a feature of the present invention that the baffle plates, particularly the front and

rear plates

59, 60 can be shaped to fit various channel shapes without changing the basic rotor construction. Where a flow channel is unusually wide, two or more units may be placed side by side and appropriately shaped front and rear baffle plates to fit across the entire channel may be used. Separate flow openings would be provided in the baffle plates for each of the rotors required to handle the flow volume of the channel. The apparatus of the present invention may also be adapted for other shapes of channels than rectangular. A V-shaped channel, for ex-. ample, would merely require a matching bottom support plate 22 and front and

rear baffle plates

59, 60 having V-shaped bottom edges. Similarly, the base plate 22 can be formed as a semi-cylinder for round bottomed channels and in appropriate instances, the semi-cylindrical baffle plate 63 may become the base plate Should a particular installation involve a tubular conduit. flanges can be provided at the front and rear ends of the apparatus for attachment to mating flanges on the conduit. ln this instance, the upper portion of the enclosure can also be semi-cylindrical to correspond to the shape of the conduit.

As previously stated herein, provision is made in the annular screen bars 31 of the rotor for holding movable cutters which coact with cooperating stationary cutters 18. The movable cutters 17 for the rotor are rectangular bits of cutting material such as hardened steel and have a width toform a cutting edge which is substantially as long as the width of the screen bar. In accordance with an aspect of the invention, an improved locking means is provided for securely holding the cutter bits in the rotor but at the same time permitting ready release of the bits for reversing them to present a new cutting edge or for replacement. To this end the screen bar 3i has an aperture 38 in its outer surface adjacent to each cutter slot 37 as best seen in F E68. 6 and 7. Surrounding the aperture 38 is a eounterbore 68 which has a portion of one side opening into the receiving slot 37. Received in the aperture 38 is a locking element or pin 69 which has a cylindrical shank 70 for in sertion into the aperture 38 and an enlarged, flat head 71 having a height equal to or slightly less than the depth of the eounterbore 68 so that the top surface of the head 71 is generally level with, or slightly below, the outer surface of the screen bar 31. The periphery of the head 71 is cam shaped, having a flat portion 72 that extends approximately to the adjacent side edge of the bit receiving slot 37. The remaining periphery 73 of the head 71 gradually increases from a radius equal to the distance of the flat portion 72 from the shank axis to a. radius greater than the distance of the shank axis to the slot so that the edge of the head 71 at the larger radii overlaps the adjacent edge of the receiving slot 37. Centrally of the head 71 is a slot or other means, such as polygonal opening '74 for receiving an Allen wrench, for manually rotating the lock pin 69 between release and lock positions. 0

Although the locking means of the invention is simple to manufacture, it securely holds the cutter bit and does not have the tendency to corrode and freeze in place as happens with ordinary screw and nut fasteners. Any tendency of the locking element 69 to bind can be overcome by extending the shank receiving aperture 38 entirely through the screen bar 3i so that a rod or other suitably sized tool can be pushed against the bottom end of the shank 70 to force the locking element 69 axially out ofthe bar. In operation, the locking element 69 is first turned with its flat head portion 72 toward the cutter receiving slot 37 to give clearance for insertion of the bit. The element isthen turned on its axis in the direction of the arrow in H6. 7 to engage the cam portion of its head with the side of the bit. Further turning of the locking element in the same direction presents sections of the head having greater radii toward the cutter bit which moves the cam portion 73 over the adjacent edge of the receiving slot 31 and firmly cams the bit against the opposite side of the receiving slot locking it in place. The bit is released by simply returning the locking element to its original position with a fraction of a turn in the reverse direction. 7

Cooperating with the movable cutters E7 on the rotor are stationary cutters 18 supported on the base support structure 13 in fixed positions relative to the rotor cutters. As best shown in H6. l of the drawings, a horizontal support shelf or ledge 77 is fixed to the solid lower portion of one of the side wall panels 55 for holding the stationary cutter bits. The shelf 77 is of triangular shape with an inner sloping edge or bar portion substantially parallel to, and spaced from, the outer surface of the rotor 12. The cutter support shelf is positioned generally at the vertical level of the rotor axis and the forward enlarged section of the shelf is connected as by bolts or welding to the front rotor support column 24 to provide lateral support for the column 24 and to insure that accurate alignment is maintained even through the front column 24 and the shelf 77 may in operation be struck by heavy pieces of solid material carried by the fluid. If desired a similar support shelf or ledge may be provided on the second side of the rotor for additional stationary cutters should it be desired to have periodic reversal of rotor rotation.

Considering the stationary cutter bits 18, two forms are illustrated in FIGS. 9 and 10, respectively. The form of bit 18A shown in FIG. 9 is preferred for use with rotor screen bars 31 having beveled or tapered outer faces. The working edge of the cutter bit 18A is L-shaped to provide a longer cutting edge 78 for coacting with the end cutting edge of the rotor bits 17 and a shorter cutting edge 79 extending'radially toward the rotor for coacting with a portion of the side edge of the rotor bits. By this configuration, the active cutting edge length is increased and any material such as string which may encircle or be draped around the rotor bits is cut. The opposite end of the stationary bit 18A has a simlarL shape so that the bit may be turned over to expose a second set of cutting edges if the original set requires replacement. in FIG. 10, stationary cutter bits 183 of similar shape are shown for use with screen bars 36 having their outer surfaces parallel with the axis of the rotor 12. The cutting edges differ only in that the second set of edges has the foot of the L-shaped edge projecting from the opposite side of the bit 188 rather than from the same side as in the form of FIG. 9. The bits 188 of FIG. 10 are positioned on the stationary cutter shelf or bar with their longer and shorter edges, respectively, parallel and perpendicular to the axis of the rotor 12 to correspond to the respective positions of the edges of the rotor cutters, rather than angled with respect to the axis as in fIG. 9.

Means are also provided for positively positioning and protecting the stationary cutter bits 18. Preferrably the bits 18 are set on a downwardly offset ledge 80, the inner edge of which is located with respect to the movable cutters so that it abuts the inactive edge of the stationary bit 18 to position it in operative relation with the movable bits 17. A bolt 82 through a central hole in the bit and received in a threaded hole in the support shelf 77 is provided for securing the stationary bits in place. Protecting the bits 18 and their fasteners is an inverted U-shaped shield 83 extending for the length of the support shelf 77 and having a width sufficient to cover the bits except for the protruding cutting edge portions. Lugs 84 on the back side of the shield 83 are apertured to receive bolts 84 which are threaded into holes in the upper surface of the support shelf 77 for fastening the shields in place.

Additional protection for both the movable and the stationary bits is given by angling the cutter receiving slots 37 in the rotor screening bars 31 with respect to the axis of the rotor and direction of movement for the cutters 17. As shown in FIG. 7, the slots 37 and consequently the cutting edges of the bits 17 are angled such that the cutting corner of the bit, the corner that mates with the junction of the radial and longitudinal stationary cutting edges ofthe bits 18, leads slightly as the cutting engagement is made. An angle A as shown in FIG. 7 of around five to ten degrees is preferred. By so angling the cutting bits, hard solids tend to be rejected or pushed out of contact with the cutters to minimize sudden shock on the cutters nd possible jamming of the rotor.

To further enhance the screening and cutting action of the rotor 12, means are provided for more uniform distribution of solid matter in the fluid flow and for cleaning the upstream facing portions of the support structure. To accomplish this, means are mounted on the front end of the rotor axle 21 in the form of a distributing and cutting arm 87. In the illustrative embodiment this means comprises a rigid bar 87 extending radially outwardly from the rotor axle 21. The inner end of the bar 87 has an enlarged hub portion 88 which is apertured for the front projecting end portion of the axle shaft 21. The hub 88 may be split so that it can be expanded to slide into place over the shaft. Fastening lugs 90 are attached to each of the split hub sections for compressing the hub opening by means of a bolt and nut to clamp the hub to the shaft. The arm 87 sweeps through the fluid entering the front baffle plate'59 to assist in breaking up any entangled masses of solids and in moving solids generally around the surface of the rotor. The leading edge of the distributing arm 87 is provided with a cutting blade 91 or set of cutting bits in the preferred form. The blade 91 extends along the length of the arm and projectsbeyond the rear side of the arm 87 for coaction with a stationary cutting means mounted in fixed relation to the path of revolution of the blade 91. As illustrated in FIG. 1, the stationary cutting'means is a blade 92 bolted to the top side of the support shelf 77 with a front cutting edge extending forwardly of the shelf into coacting position next to the path traversed by the cutting edge of the blade 91 on the distributing arm 87. If desired a similar blade or set or cutting bitsmay be mounted on the forward edge of the front rotor support column 24. These cutting edges assist in keeping the forward sections of the apparatus free'of stringy materials which otherwise become entangled around the support column and cuttershelf.

In view of the foregoing, it will be seen that by the present invention an improved comminuting and screening device is obtained. The improved device is intended to provide the screening action described in US. Pat. No. 3,074,555 in which the screen bars are spacedaxially from each other and in which the outer diameter of each ring is greater than the inner diameter of the next larger ring screening bar. The fluid must thus bend radially inwardly as it flows through the screen to enchance the screening action. It is another feature of the present invention that the spacing between the screen bars will be varied axially from the small end to the large end of the rotor for more uniform and effective flow. As an example of such variation in spacing,.the screen bars at the small end of the rotor maybe spaced apart axially by an amount approximately 50 greater than the spacing of the screen bars at the large end. The improved flow in one form of rotor may be obtained by spacing about one-third of the rotor length at the small end with around threeeighths of an inch between screening bars and the remaining two-thirds of the rotor length at the large end of the rotor with about one-quarter of an inch betweenv bars.

I claim as my invention:

1. A device for screening and comminuting solids in a stream of fluid having rotor means including a series of axially spaced apart annular screening bars of sequentially increasing diameter in the direction of fluid flow, movable cutting means on said rotor and coacting stationary cutting means, wherein the improvement comprises in combination driving means positioned out of the direct flow of fluid for rotating said rotor, means for supporting said screening bars including an axle shaft and means extending outwardly from said shaft for positioning each of said screening bars concentrically therewith, and means for supporting said shaft including a base member and support members extending upwardly therefrom for engaging the front and rear portions of said shaft for rotation thereof on an axis substantially parallel to the direction of fluid flow.

2. The device of claim 1 in which said means extending outwardly from said axle shaft include a plurality of ribs equally spaced around said shaft, each of said ribs having an edge portion extending axially along said sbaft a distance equal to the axial length of said series of bars and having an outer sloping edge portion for receiving and positioning said series .of bars.

3. The device of claim 1 in which said driving means includes an annular driving member having a diameter substantially equal to the diameter of the largest of said screening bars and drivingly affixed to the rear thereof, power means positioned above said rotor and above the level of fluid flow, and flexible belt means trained around said driving member for interconnecting said power means and said driving member.

4. The device of claim 3 in which said annular driving member is a ring sprocket and said flexible belt means is a power transmitting chain.

5. The device of claim 3 in which fluid baffle means surrounds said rotor adjacent the largest of said screen bars and forwardly of said annular driving member for minimizing flow bypassing said rotor and shielding said drive means from direct flow of fluid.

6. The device of claim 5 in which upright side panels extend forwardly from the side portions of said fluid baffle means to the front of said rotor and a second baffle means having an opening for fluid flow extends transversely between said side panels at their forward portions for directing fluid to said rotor.

7. The device of claim 1 in which said shaft supporting means includes rigid means extending laterally from an upper portion of the front one of said upwardly extending support members and connected to said base member for resisting sideward movement of said rotor shaft.

8. The device of claim 7 in which said rigid means also extends rearwardly along the outer face of said rotor and means for mounting said stationary cutting means thereon.

9. The device of claim 1 in which a front projecting portion of said axle shaft has a radially extending arm attached thereto for rotation with said rotor for distributing solids in said fluid to said screening bars.

10. The device of claim 9 in which said arm has movable cutting means and a forward facing portion of said shaft support means has coacting stationary cutting means for removing solids carried by the fluid against said forward facing portion.

11. A device for screening and comminuting solids in a stream of fluid having rotor means including a series of axially spaced apart annular screening bars of sequentially increasing diameter. movable cutting means on said rotor and coacting stationary cutting means, wherein the improvement comprises in combination an axle shaft extending lengthwise of said series of annular screening bars and concentric therewith, a plurality of ribs equally spaced around said shaft and extending radially therefrom, said ribs each having a series of stepped recesses in their outer edge portions, said stepped recesses being at sequentially increasing distances from the axis of said shaft corresponding to the sequentially increasing inner diameters of said screening bars for receiving and holding said series of screening bars on said ribs in axially spaced apart relation, said ribs being affixed to said shaft at least at points substantially perpendicular with respect to the end portions of said series of screening bars, and upright sup- -port means having bearings means at the upper portions thereof for receiving projecting end portions of said shaft for rotation about the axis thereof.

12. The device of claim ill in which the spacing between annular screening bars of large diameter is less than the spacing between annular screening bars of small diameter.

13. The device of claim ill in which the spacing be tween adjacent screening bars increases as the diameters of the bars decrease.

14. A device for screening and comminuting solids in a stream of fluid having rotor means including a series of axially spaced apart annular screening bars, movable cutting means on said rotor and coacting stationary cutting means wherein the improvement comprises in combination flat sided movable cutter bits having at least one cutting edge, said screening bars defining transverse slots in their outer surfaces having a width substantially equal to the thickness of said bits and having a depth less than the length of said bits for receiving said bits with the'cutting edge thereof projecting be yond the outer surface of said bars, the outer surface of said screening bars having an aperture therein adjacent each of said slots, and a locking element having a cylindrical shank portion received in said aperture and a cam shaped head portion the radius of which increases from an amount less than the distance of the axis of the shank portion from the adjacent side of a cutter bit in said slot to an amount greater than said dis tance for releasably locking said cutter bits in said slots upon rotation of said locking element about said shank axis to force said head portion into clamping egagement with said cutter bits.

15. The device of claim M in which the outer surface of said screening bars also has a recess surrounding said aperture, said recess having a depth at least as great as the thickness of said locking element head portion and opening into said bit receiving slot, said head portion being received in said recess.

' 16. The device of claim 14 in which said cutter bit receiving slots are angled with respect to the central axis of said screening bars such that one corner of the cutting edge of said cutter bit engages the coacting stationary cutter in advance of the remainder of the said cutting edge.

17. The method of making a rotor for use in screening and comminuting devices of the type having a rotor means including a series of axially spaced apart annular screening bars of sequentially increasing diameter and movable cutter means on said rotor, comprising in combination cutting a series of annular bars of sequentially increasing diameters from metal plate material, machining the inner diameters of said bars parallel with the axis thereof and machining the outer diameters such that the outer diameter of one bar is larger than the inner diameter of the next larger bar, cutting a plurality of triangular ribs from metal plate material,

the shaft and the bars to the said ribs, and removing the fixture elements thereafter.

18. The method of claim 17 in which the step of machining the annular screening bars includes machining transverse slots in the outer surfaces of the bars for receiving said movable cutter means before mounting the bars on the steps of the ribs.

Claims

2. The device of claim 1 in which said means extending outwardly from said axle shaft include a plurality of ribs equally spaced around said shaft, each of said ribs having an edge portion extending axially along said sbaft a distance equal to the axial length of said series of bars and having an outer sloping edge portion for receiving and positioning said series of bars.

11. A device for screening and comminuting solids in a stream of fluid having rotor means including a series of axially spaced apart annular screening bars of sequentially increasing diameter, movable cutting means on said rotor and coacting stationary cutting means, wherein the improvement comprises in combination an axle shaft extending lengthwise of said series of annular screening bars and concentric therewith, a plurality of ribs equally spaced around said shaft and extending radially therefrom, said ribs each having a series of stepped recesses in their outer edge portions, said stepped recesses being at sequentially increasing distances from the axis of said shaft corresponding to the sequentially increasing inner diameters of said screening bars for receiving and holding said series of screening bars on said ribs in axially spaced apart relation, said ribs being affixed to said shaft at least at points substantially perpendicular with respect to the end portions of said series of screening bars, and upright support means having bearings means at the upper portions thereof for receiving projecting end portions of said shaft for rotation about the axis thereof.

12. The device of claim 11 in which the spacing between annular screening bars of large diameter is less than the spacing between annular screening bars of small diameter.

13. The device of claim 11 in which the spacing between adjacent screening bars increases as the diameters of the bars decrease.

14. A device for screening and comminuting solids in a stream of fluid having rotor means including a series of axially spaced apart annular screening bars, movable cutting means on said rotor and coacting stationary cutting means wherein the improvement comprises in combination flat sided movable cutter bits having at least one cutting edge, said screening bars defining transverse slots in their outer surfaces having a width substantially equal to the thickness of said bits and having a depth less than the length of said bits for receiving said bits with the cutting edge thereof projecting beyond the outer surface of said bars, the outer surface of said screening bars having an aperture therein adjacent each of said slots, and a locking element having a cylindrical shank portion received in said aperture and a cam shaped head portion the radius of which increases from an amount less than the distance of the axis of the shank portion from the adjacent side of a cutter bit in said slot to an amount greater than said distance for releasably locking said cutter bits in said slots upon rotation of said locking element about said shank axis to force said head portion into clamping egagement with said cutter bits.

15. The device of claim 14 in which the outer surface of said screening bars also has a recess surrounding said aperture, said recess having a depth at least as great as the thickness of said locking element head portion and opening into said bit receiving slot, said head portion being received in said recess.

16. The device of claim 14 in which said cutter bit receiving slots are angled with respect to the central axis of said screening bars such that one corner of the cutting edge of said cutter bit engages the coacting stationary cutter in advance of the remainder of the said cutting edge.

17. The method of making a rotor for use in screening and comminuting devices of the type having a rotor means including a series of axially spaced apart annular screening bars of sequentially increasing diameter and movable cutter means on said rotor, comprising in coMbination cutting a series of annular bars of sequentially increasing diameters from metal plate material, machining the inner diameters of said bars parallel with the axis thereof and machining the outer diameters such that the outer diameter of one bar is larger than the inner diameter of the next larger bar, cutting a plurality of triangular ribs from metal plate material, stacking and machining said ribs in unison to form a straight side on said ribs having a length at least as great as the axial length of said series of screening bars and a sloping side having a series of steps for receiving said series of screening bars, equally spacing said ribs around a cylindrical axle shaft, removably fastening like fixture elements between adjacent ribs for maintaining said spacing, mounting said series of bars on said series of steps, permanently fastening said ribs to the shaft and the bars to the said ribs, and removing the fixture elements thereafter.

18. The method of claim 17 in wbich the step of machining the annular screening bars includes machining transverse slots in the outer surfaces of the bars for receiving said movable cutter means before mounting the bars on the steps of the ribs.