US3774853A

US3774853A - Pulping apparatus for waste material

Info

Publication number: US3774853A
Application number: US00220950A
Authority: US
Inventors: P Seifert
Original assignee: Black Clawson Fibreclaim Inc
Current assignee: Black Clawson Fibreclaim Inc
Priority date: 1972-01-26
Filing date: 1972-01-26
Publication date: 1973-11-27
Anticipated expiration: 1990-11-27
Also published as: CA969521A; FI54564B; SE398306B; IT976792B; FR2169240A1; DE2302341A1; FI54564C; GB1412173A; JPS4884348A; NL7300681A; FR2169240B1

Abstract

A pulper or similar device for comminuting solid materials includes a vaned rotor having some of its vanes equipped with cutter bars arranged to move past complementary stationary cutter bars in shearing relation. The device is particularly designed to select and cut flexible materials by causing them to fold over the leading edge of each moving cutter and its associated vane, and each of these vanes is equipped on the surface opposite the cutter with one or more fins arranged to hold the folded over pieces of flexible material against centrifugal travel outwardly of the vane and thereby to retain such material in folded over position over the leading edge of the vane and its cutter until the moving cutter reaches the next stationary cutter where the folded over material is cut into two pieces.

Description

United States Patent 1191 Seifert 1451 Nov. 27, 1973 1' PULPING APPARATUS FOR WASTE MATERIAL [75] inventor: Peter Seifert, Middletown, Ohio [73] Assignee: Black Clawson Fibreclaim, Inc.,

New York, NY.

22 Filed: Jan. 26, 1972 [56] I References Cited UNITED STATES PATENTS 2,674,927 4/1954 Wicksell 241/4611 Primary Examiner-Granville Y. Custer, Jr. Assistant Examiner-H0ward N. Goldberg Att0rneyLawrence B. Biebel et a1.

[57] ABSTRACT A pulper or similar device for comminuting solid materials includes a vaned rotor having some of its vanes equipped with cutter bars arranged to move past complementary stationary cutter bars in shearing relation. The device is particularly designed to select and cut flexible materials by causing them to fold over the leading edge of each moving cutter and its associated vane, and each of these vanes is equipped on the surface opposite the cutter with one or more fins arranged to hold the folded over pieces of flexible material against centrifugal travel outwardly of the vane and thereby to retain such material in folded over position over the leading edge of the vane and its cutter until the moving cutter reaches the next stationary cutter where the folded over material is cut into two 10 Claims, 12 Drawing Figures 3,073,535 1/1963 Vokes 241/46 3,339,851 9/1967 P611611 61 a1 241/46 3,595,488 7/1971 Blakley et a1. 241/4608 Pleces' 1 sum-1 0: 11'

FIG-3 FIG-l PATENTEDuuvzmra SHEET 3 OF 3 PULPING APPARATUS FOR WASTE MATERIAL BACKGROUND OF THE INVENTION This invention is concerned with the disposal of solid waste materials, and especially with the disposal of solid waste of the types commonly generated by establishments and institutions such as office buildings, hospitals, hotels and the like. Such institutional wastes commonly typically include not only large quantities of paper and paper products, but also frangible materials such as glass and relatively tough stringy or sheet material such as flexible tubing, rags, rope, wire and sheet plastic.

All of these types of materials, as well as considerable quantities of metal trash, commonly occur in municipal refuse, and the apparatus shown in U.S. Pat. No. 3,595,488, which includes swing hammers on the rotor and cooperating stator attrition bars, has proved to be highly successful for reducing municipal refuse to pulpable consistencies while selectively separating the infrangible materials. That apparatus is accordingly most successful for uses requiring heavy duty equipment, but equipment of such heavy duty capabilities is usually not needed for smaller installations such particularly as for the disposal of office or hospital waste.

SUMMARY OF THE INVENTION The present invention provides pulping apparatus which is especially designed for use in the disposal of solid wastes wherein there may be a wide variety of materials of the types outlined above but which do not usually contain large metal objects such as commonly occur in municipal refuse. The apparatus of the invention is especially useful for pulping solid wasteswhich contain substantial quantities of relatively tough stringy or sheet material, typical examples being string, wire, plastic sheet and tubing, leather and cloth.

The apparatus of the invention typically comprises a pulper of the general characteristics of the apparatus disclosed in Felton et al. U.S. Pat. No. 3,339,851 which is equipped with a vaned rotor construction generally shown in Vokes U.S. Pat. No. 3,073,535 and which is intended to be charged with a suspension of solid waste in 'a liquid carrier. Certain of the rotor vanes are equipped with a cutter mounted on the under side which cooperate with stationary cutters to cut into smaller pieces the stringy or sheet materials which fold over their leading edges while the vanes reduce the pulpab'le materials by a combination of mechanical action and hydraulic shear. In addition, each vane which carries a cutter is, also equipped on its upper surface with one or morefms which retain the folded over stringy materials against outward movement along the vane until they are cut between the movable and stationary cutters but without requiring metal to metal contact of the cutters.

It is a principle of the invention that in operation, the rotor vanes have a tendency to be self-cleaning with respect to materials which might injure the cutters, because metal and other heavy pieces are not held by the fins but tend to be urged away from the cutting area, both by centrifugal action and by the scissor-like action of the cutters. At the same time, however, stringy or sheet materials which require cutting are held on the vanes and carried directly into position to be cut to the range of particle sizes desired for further processing. The invention accordingly provides pulping apparatus BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a somewhat diagrammatic view in vertical section illustrating a pulper constructed in accordance with the invention;

FIG. 2 is afragmentary plan view on a larger scale of the pulper of FIG. 1;

FIG. 3 is a fragmentary section generally on the line 3-3 of FIG. 2;

FIG. 4 is a detail of the outer end of one of the rotor vanes looking in the direction indicated by the line 4-4 of FIG. 2;

. FIG. 5 is a detail view of the outer end of another vane taken as indicated by the line 5-5 of FIG. 2;

FIG. 6 is a fragmentary view of the leading face of the vane of FIG. 5, as indicated by the: line 6-6 of FIG. 2;

FIG. 7 is a fragmentary view in radial section of another form of rotor arrangement in accordance with the invention;

FIG. 8 is a fragmentary section on the line 8-8 of FIG. 7;

FIG. 9 is a somewhat diagrammatic view illustrating the application of the invention to a shredding device for air-carried materials;

FIG. 10 is a view taken as indicated by the line 10-10 of FIG. 9; and

FIGS. 11 and 12 are diagrammatic views illustrating the application of the invention to another form of shredding device, FIG. 12 being; taken on the line 12-12 of FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 11 and a frustoconical bottom wall section 12.. The remainder of the bottom wall comprises a perforate extraction plate 13 which forms a partition between the interior of the tub and chamber 15 for receiving a slurry of particles sufficientlysmall to pass through the perforations in plate 13, which are commonly in the range of one-fourth inch to 1 inch in diameter. A conduit 16 carries this slurry away from chamber 15. The wall section 12 also has an outlet 17 for receiving infrangible items, which pass bygravity through outlet 17 to a chute 18 for collection and removal, for example by means of the junk remover shown in U.S. Pat. No. 3,549,092. r r

A rotor 20 is mounted on the upper end of a shaft 22 extending through the extraction plate 13 to support the rotor for rotation just above the extraction plate, a drive for shaft 22 being shown diagrammatically at 23. The rotor 20 is generally of the construction disclosed in Vokes U.S. Pat. No. 3,073,535 and it comprises a rotor body 24 and a plurality of vanes projecting outwardly therefrom in overlying relation with the perforations in the extraction plate 1.3. Two of these vanes 25 are of essentially the same configuration shown in U.S. Pat. No. 3,073,535, each of them having a leading face portion 26 and smooth upper and

lower surfaces

27 and 28 trailing the leading portion 26. As best shown in FIG. 4,the face 26 is inclined at a small angle forwardly toward the extraction plate 13 to urge a liquid suspension within the tub toward the surface of plate 13 as the rotor revolves.

The other two vanes 30 are generally similar to vanes 25, and each includes upper and

lower surfaces

31 and 32 trailing from a leading edge portion 33, which, however is inclined upwardly rather than downwardly as in the case of leading portions 26. instead of a smooth upper surface, however, each vane 30 has on its upper surface a pair of ribs or'fins 35 which extend generally tangentially in spaced relation defining a slot 36 therebetween, and which are provided with hard surface coatings 37, such as stellite on their leading edge surfaces. In addition, each vane 35 has a cutter bar 40 mounted by bolts 41 in its under surface generally in alignment with its leading edge 33. Two complementary stationary cutter bars 42 are mounted on the upper surface of the extraction plate 13 along a common diameter of the plate as best seen in FIG. 2.

The purpose of the

cutters

40 and 42 is to cut tough or stringy material as the rotor rotates, and the purpose of the ribs 35 is to cause such materials to be presented to these cutters in the best position for repeated cutting action. Thus as the rotor rotates, the vanes and cause vortical circulation of the liquid within the tub 10, and solid materials suspended in this liquid follow a pattern of movement in which they are thrown centrifugally outwardly by the rotor until they climb the wall 1 l and then fall back into the center of the vortex. The rotor in turn has a selective action on these materials, subjecting them to cutting or to mechanical force and hydraulic shear depending upon whether they are rigid or flexible.

Rigid materials are struck by the leading edge faces of the vanes so that frangible materials such as glass are shattered, while infrangible items such as pieces of metal are circulated until they drop through the outlet 17 to the chute 18. Soft materials like garbage, wood andpaper products are shredded and/or defibered by the combination of mechanical and hydraulic shear imparted to the suspension by the

vanes

25 and 30.

Flexible materials, such particularly as string, wire, and plastic sheet and tubing, are treated differently.

Whenever a piece of such material is encountered by one of the vanes 30, the split in the slurry flow into two portions, which travel above and below the vane respectively, will cause such material to fold or wrap itself around the leading edge of the vane and the cutter 40. When this occurs on one of the vanes 25, the folded over material will travel out to the end of the vane and return to the flow, but when it occurs on a vane 30, the ribs will hold the stapled material on the vane so that it will cut when the cutter passes the next stationary cutter 42. This action will be repeated as the flexible materials circulate in the tub until sufficient cuts have been made to reduce the flexible material to particles small enough to pass through the perforations in the extraction plate 13.

It is also advantageous that the action of the rotor and cutters will tend to cause pieces of flexible material to be aligned generally parallel with the surface of the extraction plate after cutting so that they will usually not pass through a hole in the extraction plate unless their longest dimension is smaller than the diameter of the hole. As a result, long and stringy material tends to be retained in the pulper until it has been cut into relatively small pieces.

The construction and operation of the vanes 30 and the ribs 35 thereon thus provides the major part of the selective action of the rotor in cutting flexible materials while at the same time protecting the

cutters

40 and 42 from rigid materials which might damage their cutting edges. Thus as best seen in F IG. 6 the fins 35 are sufficiently rounded in radial section to minimize any tendency they might have to catch and hold hard materials traveling along the surface of the rotor under the influence of centrifugal force, and the upwardly inclined leading edge portions 33 will also act to deflect hard materials upwardly. Hard materials will therefore continue to circulate until they have all comminuted or have dropped through the outlet 17, and they will ordinarily not come in contact with the cutters, but the flexible materials are restrained from outward movement long enough to expose them to the cutting action described.

Two other factors also contribute to selectivity and to protection of the cutting edges of the

cutters

40 and 42. One factor is the clearance between the under side of each cutter 40 and the upper surface of the extraction plate 13, which establishes a limit to the thickness of flexible material which can fold over the leading edge of each vane 30. Satisfactory results have been obtained when this clearance is in the range of onefourth inch to one-half inch.

The other factor referred to above is the shearing angle defined by the cooperating cutting edges of the

cutters

40 and 42. Preferred results have been obtained with this angle of the order of 30, as shown by the dotted outline of the cutter 40 superimposed on the cutter 42 in FIG. 2. This relationship is provided by mounting the cutters 40 tangentially on the rotor and at an angle of approximately 30 to a radius intersecting therewith. With shearing angles of this order, if metal pieces like nails or bolts should enter into shearing position, the cutters will tend to urge them outwardly without being sheared, thereby protecting their cutting edges. Another practical advantage is that the cutters are simple rectangular bars of metal which are easy to produce, to maintain and to adjust.

For preferred results over extended periods, the

cutters

40 and 42 are preferably in closely spaced but noncontacting relation, a clearance of the order of 0.003 to 0.020 inch having been found satisfactory for the handling of instiutional wastes. H6. 3 illustrates an adjustable mounting for the rotor shaft 22 for the purpose of establishing preferred spacing for the cutters. As shown, the lower end of the shaft 22 is held axially in a cup-shaped retainer 44 by means of. bearings 45 and a lock-ring 46. The retainer 44 is threaded in the bottom end of the bearing housing 47, and it can therefore be threaded in and out of the housing to move the rotor shaft and rotor up and down and thereby to adjust the relative spacing of the movable cutters.

While the construction described is preferred, considerable variation in design is possible within the scope of the invention. For example, the number of vanes and the number of fins on each vane 30 can be changed, but preferably the vane arrangement isv always symmetrical to avoid out of balance conditions. Similarly the number of cutters can be increased or decreased as desired,

' and the relative angles of the cutters can be changed so long as the protective result described above is maintained.

FlGS."7-d illustrate the application of the invention to another construction of pulper in. which a relatively flat rotor 59 having abrasive or pumping projections 51 on its upper surface is supported for rotation in a tub within a cylindrical perforate extraction ring 52. The rotor 59 also carries adjacent its outer edge an upwardly projecting vane 53 having its leading edge 54 inclined upwardly and away from its direction of movement to act as a cutter in combination with one or more stationary cutter bars 55 mounted on the inner surface of the extraction ring 52, the clearance between these cutters being exaggerated in FIG. 8. Material which folds around the leading edge of vane 53 would ordinarily tend to travel up and back into the liquid flow, but this is prevented by one or more ribs 56 on the radially inner surface of vane 59, which act like the ribs 35 to retain folded material on the leading edge 54 in position for cutting by the stationary bars 55.

While the principles of the invention are especially applicable to a pulper operating on solid materials in liquid suspension, the same principles are applicable to the shredding of air-borne materials, and FIGS. 9 and illustrate apparatus for that purpose. As shown in FIG. 9, the pieces 60 of material to be cut are conveyed through a chute 61 to the upper surface of a rotor 62 similar in construction to the rotor and carried by -a shaft 63 driven by a motor 64. The rotor 62 includes a pair of symmetrically spaced vanes 65 having ribs 66 on their upper surfaces, and carrying cutter bars 67 on their lower surfaces which cooperate with four stationary cutter bars 68.

The apparatus shown in FIGS. 9 and I0 is essentially a shredder for paper or other flexible material, and the ribs 66 operate in the same manner as described for the fins 35 in that they tend to hold folded over pieces of flexible material from outward movement along the rotor vanes 65 long enough to cause such pieces of material to be cut between the movable and stationary cutters 67-69 While apparatus of this type would ordinarily be used on material which is essentially free of hard pieces, if any such hard pieces are present, the vanes will tend to throw them centrifugally clear of the cutting area, in a manner similar to that described for the rotor 29.

FIGS. 19 and Ill show another type of shredding apparatus in which there are multiple rotors 70 mounted on a common shaft 71 and each comprising a pair of vanes 72 having ribs 73 on one surface and cutters 75 on the opposite surface for cooperating with stationary cutters 77. In this apparatus, the material to be shredded drops down a chute ht) into the space wherein therotors 70 cooperate, and the cut pieces continue their downward movement through the outlet 81. The operation of the ribs 72 in this form of the invention is essentially the same as in the other forms already described.

The apparatus shown in FIGS. 9-12 illustrates the fact that although the invention is especially useful in connection with the treatment of solid waste materials,

it is also applicable to other operations involving the cutting of flexible stringy materials. For example, apparatus like that shown in FIGS. 9-10 could readily be proportioned to cut long filaments, e.g., Nylon or the 6 like, mto short pieces. All advantages of the invention as described above would be available for such purposes, including the rejection of and protection of the cutters from any hard materials which might be present.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. Apparatus of the character described adapted to comminute pieces of relatively flexible material, comprising a. a chamber for receiving a charge of such flexible material,

b. a rotor including a rotor body mounted for rotation on an axis within said chamber,

c. at least one vane projecting from said body and having a leading edge portion,

d. meansforming a cutter on said vane extending generally in alignment with said leading edge portion thereof,

e. means forming at least one cutter fixedly mounted in said chamber in position for cooperative cutting action with said cutter on said vane as said rotor rotates,

f. means for rotating said rotor to cause said pieces of flexible material to fold over said leading edge portion of said vane, and

g. means on said one vane for holding said folded pieces of flexible material against travel along said vane in order to retain such pieces folded over said leading edge portion of said vane and said cutter thereon for cutting by said cutters.

2.. Apparatus of the character described adapted to pulp solid waste material containing a substantial quantity of pieces of relatively flexible material such as tubing, rope, wire and/or sheet plastic, comprising a. a tub for receiving 'a suspension of such waste material in a carrier medium,

b. a rotor including a rotor body mounted adjacent a wall of .said tubfor rotation on an axis,

0. at least one vane projecting from said rotor body in spaced relation with said tu b wall and having a leading edge portion,

d. means for rotating said rotor to cause vertical circulation of said suspension within said tub and centrifugal movement of said suspension with respect to said rotor and to cause pieces of flexible material to fold over said leading edge portion of said vane,

e. means forming a cutter fixedly mounted on said tub wall opposite said vane,

f. means forming a cutter on said vane extending generally in alignment with said leading edge portion of said vane for cooperativecutting action with said fixed cutter as said rotor rotates, and

g. at least one rib on said vane and having the length thereof extending generally tangentially of said rotor body to hold folded over pieces of flexible material against travel along said vane and thereby to retain such material folded over said leading edge portion of said vane and said cutter thereon for cutting by said cutters.

3. Apparatus according to claim 1 comprising a plurality of said vanes arranged on said rotor in equally angularly spaced relation, there being one of said cutters on each of said vanes, and further comprising a plurality of said fixed cutters arranged in angularly spaced relation around said rotor axis.

- 4. Apparatus as defined in claim 2 comprising a plurality of said vanes arranged on said rotor in equally angularly spaced relation, there being one of said cutters on selected equally angularly spaced ones of said vanes, the others of said vanes having pumping surfaces thereon contributing to said vortical circulation of said suspension, and said apparatus further comprising a plurality of said fixed cutters arranged in angularly spaced relation around said rotor axis.

5. Apparatus as defined in claim 2 comprising at least two of said ribs mounted in generally radially spaced relation on each of said selected vanes.

6(Apparatus as defined in claim 2 comprising-a drive shaft for said rotor extending through said wall of said tub to the exterior thereof, means securing said rotor on said shaft, and means accessible from the exterior of said tub for moving said shaft axially to adjust the relative spacing of said cutters.

Apparatus as defined in claim 2 wherein said cutters have substantially straight cutting edges and wherein said cutters are so arranged that said edges define relatively large shearing angles as each said movable cutter passes over each said stationary cutter such that hard objects which come therebetween are urged outwardly thereof.

8. Apparatus as defined in claim 7 wherein said shearing angles are of the order of 30.

9. Apparatus as defined in claim 2 comprising means maintaining said rotor with each said vane in predetermined spaced relation with said tub wall establishing a maximum size of flexible material capable of being folded over said leading edge portion of said vane and said cutter thereon.

10. Apparatus of the character described adapted to pulp solid waste material containing relatively infrangible items as well as pieces of relatively flexible material such as tubing, rope, wire and/or sheet plastic, compris- 8 ing a. a tub for receiving a suspension of such waste material in a carrier medium,

b. a rotor including a rotor body mounted adjacent the bottom of said tub for rotation on a substantially vertical axis,

c. a plurality of vanes projecting from said rotor body transversely of said axis in overhanging spaced relation with said tub bottom and each having a leading edge portion and upper and lower surfaces trailing said edge portion,

d. means forming an outlet in the bottom of said tub located radially outwardly of said vanes for receiving by gravity relatively infrangible items from said suspension,

e. means for rotating said rotor to cause vortical circulation of said suspension within said tub and centrifugal movement of said suspension with respect to said rotor and to cause pieces of flexible material to fold over said leading edge portions of said vanes,

f. means forming a cutter fixedly mounted on the bottom of said tub below said vanes,

g. means forming a cutter on said lower surface of at least a selected one of said vanes extending generally in alignment with said leading edge portion of said vane for cooperative cutting action with said fixed cutter as said rotor rotates,

h. means on each said selected vane for holding such folded pieces of flexible material against travel along said outer vane surface in order to retain such material folded over said leading edge portion of said vane and said cutter thereon for cutting by said cutters, and

i. means on the others of said vanes for urging relatively infrangible items radially outwardly of said cutters for reception in said outlet.

Claims

1. Apparatus of the character described adapted to comminute pieces of relatively flexible material, comprising a. a chamber for receiving a charge of such flexible material, b. a rotor including a rotor body mounted for rotation on an axis within said chamber, c. at least one vane projecting from said body and having a leading edge portion, d. means forming a cutter on said vane extending generally in alignment with said leading edge portion thereof, e. means forming at least one cutter fixedly mounted in said chamber in position for cooperative cutting action with said cutter on said vane as said rotor rotates, f. means for rotating said rotor to cause said pieces of flexible material to fold over said leading edge portion of said vane, and g. means on said one vane for holding said folded pieces of flexible material against travel along said vane in order to retain such pieces folded over said leading edge portion of said vane and said cutter thereon for cutting by said cutters.

2. Apparatus of the character described adapted to pulp solid waste material containing a substantial quantity of pieces of relativelY flexible material such as tubing, rope, wire and/or sheet plastic, comprising a. a tub for receiving a suspension of such waste material in a carrier medium, b. a rotor including a rotor body mounted adjacent a wall of said tub for rotation on an axis, c. at least one vane projecting from said rotor body in spaced relation with said tub wall and having a leading edge portion, d. means for rotating said rotor to cause vertical circulation of said suspension within said tub and centrifugal movement of said suspension with respect to said rotor and to cause pieces of flexible material to fold over said leading edge portion of said vane, e. means forming a cutter fixedly mounted on said tub wall opposite said vane, f. means forming a cutter on said vane extending generally in alignment with said leading edge portion of said vane for cooperative cutting action with said fixed cutter as said rotor rotates, and g. at least one rib on said vane and having the length thereof extending generally tangentially of said rotor body to hold folded over pieces of flexible material against travel along said vane and thereby to retain such material folded over said leading edge portion of said vane and said cutter thereon for cutting by said cutters.

4. Apparatus as defined in claim 2 comprising a plurality of said vanes arranged on said rotor in equally angularly spaced relation, there being one of said cutters on selected equally angularly spaced ones of said vanes, the others of said vanes having pumping surfaces thereon contributing to said vortical circulation of said suspension, and said apparatus further comprising a plurality of said fixed cutters arranged in angularly spaced relation around said rotor axis.

6. Apparatus as defined in claim 2 comprising a drive shaft for said rotor extending through said wall of said tub to the exterior thereof, means securing said rotor on said shaft, and means accessible from the exterior of said tub for moving said shaft axially to adjust the relative spacing of said cutters.

7. Apparatus as defined in claim 2 wherein said cutters have substantially straight cutting edges and wherein said cutters are so arranged that said edges define relatively large shearing angles as each said movable cutter passes over each said stationary cutter such that hard objects which come therebetween are urged outwardly thereof.

8. Apparatus as defined in claim 7 wherein said shearing angles are of the order of 30*.

10. Apparatus of the character described adapted to pulp solid waste material containing relatively infrangible items as well as pieces of relatively flexible material such as tubing, rope, wire and/or sheet plastic, comprising a. a tub for receiving a suspension of such waste material in a carrier medium, b. a rotor including a rotor body mounted adjacent the bottom of said tub for rotation on a substantially vertical axis, c. a plurality of vanes projecting from said rotor body transversely of said axis in overhanging spaced relation with said tub bottom and each having a leading edge portion and upper and lower surfaces trailing said edge portion, d. means forming an outlet in the bottom of said tub located radially outwardly of said vanes for receiving by gravity relatively infrangible items from said suspension, e. means for rotating said rotor to cause vortical circulation of said suspension within said tub and centrifugal movement of said suspension with respect to said rotor and to cause pieces of flexible material to fold over said leading edge portions of said vanes, f. means forming a cutter fixedly mounted on the bottom of said tub below said vanes, g. means forming a cutter on said lower surface of at least a selected one of said vanes extending generally in alignment with said leading edge portion of said vane for cooperative cutting action with said fixed cutter as said rotor rotates, h. means on each said selected vane for holding such folded pieces of flexible material against travel along said outer vane surface in order to retain such material folded over said leading edge portion of said vane and said cutter thereon for cutting by said cutters, and i. means on the others of said vanes for urging relatively infrangible items radially outwardly of said cutters for reception in said outlet.