BACKGROUND OF THE INVENTION A variety of different forms of insulating materials exist for insulating new and existing structures. Two types of materials that have been adopted by the construction industry are closed-celled foams and mineral fiber products such as fiberglass. The foam products are generally formed into rigid boards which can be cut to size and installed between studding, ceiling joists, etc. The fiberglass products can comprise fibrous mats or"batts"which can be cut to size for installation purposes or loose fibrous material suitable for being blown into a confined area of a structure ("loose-fill"insulation).

Both types of mineral fiber insulation have advantages and disadvantages. For example, special equipment is generally not required to install batt insulation. Batt or blanket installation is adapted to be cut to size and manually installed in place. Batt-type insulation is also generally more expensive to produce than loose-fill insulation.

The use of loose-fill insulation is increasing in popularity. Loose-fill insulation is not formed into a blanket or batt, but comprises smaller nodules of short fibers which are packaged in bags. Such insulation is installed by adding the loose-fill fibers to the hopper of a pneumatic blower which blows the insulation fibers into the desired area. U. S. Patent No. 5,590,984 to Assarsson discloses a system and method for installing loose-fill insulation. Such installation process eliminates the need for manually handling the fibers.

Loose-fill insulation is also a relatively low cost material. Thus, loose-fill insulation provides various advantages over blanket and batt-type insulation materials. A major problem associated with the installation of loose-fill material is the proliferation of dust during the blowing operation.

Mineral fibers of the type employed in batt and loose-fill insulation are usually formed from molten material using equipment known as"fiberizers."In the typical manufacturing operation, molten mineral material is introduced into a plurality of fiberizers from the forehearth and bushings of a melt furnace. The fiberizers centrifuge the molten material into fibers which are directed as a stream or veil to other apparatuses for forming a batt or for producing loose-fill fibers.

Various types of methods and apparatuses have been developed for producing loose-fill insulation fibers. One method for producing such insulation employs the use of equipment known as"flailers."The flailing method shreds or"flails"entangled fibers into smaller nodules or wool segments. These segments are then typically treated with a lubricant and/or anti-static material and transported to a bagging device. U. S. Patent No.

4, 852,219 to Demars, et al. discloses a method for forming mineral fiber flakes that employs a flailing device. When flailed materials are processed through a contractor's pneumatic installation device, they further break apart to form a loose blanket of insulation. For the flailing process to be effective, relatively short fibers must be employed. Longer fibers tend to clump, twist and bunch together which can result in the non-uniform distribution of insulation material which degrades the material's thermal performance. In addition, such flailing of material also tends to create excessive fiber dust which can be an irritant during installation.

Over the years, other methods for producing loose-fill insulation have also been developed. Such methods may employ cutting drums that have continuous cutting edges or have elongated cutting knives attached thereto. The cutting drum is typically arranged in confrontation with an anvil roller sueh that fibers are pinched and severed when they pass between the cutting edges or knives and the anvil roller.

U. S. Patent No. 4,184,643 to McCort discloses apparatus which employs hollow grid-like cutting cylinders which breaks up glass wool mat into small columns which can delaminate into blowing wool pieces. U. S. Patent No. 4,296,164 to Bemis, et al. also discloses a process whereby a blanket of fibrous glass wool is first slit into long columns and then fed into rolls having herringbone-shaped cutting edges for cutting the long columns into diamond-shaped smaller columns suitable for pneumatic installation. U. S.

Patent No. 4,682,523 to Johnson, et al. discloses apparatus for fabricating glass wool blowing insulation wherein a glass wool blanket is cut by a rotary cutting grid in

combination with a back up anvil roll. The grid spaces are closed at their radially inner ends and filled with elastomeric plugs. The cut product and the plugs are compressed between the closed inner ends of the grid spaces and the anvil roll and the product is ejected by the plugs as the cutting grid rotates past the area of contact with the anvil roll.

U. S. Patent No. 4,997,681 to Dockrill et al. discloses a nodulizing machine that includes a conduit that has a plurality of fiber cutting blades arranged in spaced-apart relationship on a rotating shaft. The fibers are pneumatically fed into the conduit and are cut by the rotating blades.

While such fiber cutting apparatuses can effectively produce loose-fill insulation, the anvil roll tends to quickly become worn through contact with the knives. Thus, such apparatuses require fairly frequent maintenance to maintain their cutting ability. Also, such processes often create an undesirable amount of dust during cutting which can ultimately be dispersed within a structure during installation. In addition, the knives do not always cut all of the fibers as they pass between the knives and anvil due to clumping of the fibers and anvil wear which can result in the production of fibers having non- uniform lengths.

Other devices known as"hammermills"have been advantageously used to cut fibers for loose-fill insulation purposes. In general, a hammermill comprises a series of rotating hammers provided in a casing for breaking up masses of fibrous glass wool and forcing the fibers through a plate having a plurality of orifices. Such a device is disclosed in U. S. Patent No. 3,584,796 to Earle. et al. Another method for fabricating loose-fill insulation is disclosed in U. S. Patent No. 4,366,927, U. S. Patent No. 4,756,957, and U. S.

Patent No. 4,842,928 to Kielmeyer. Sudh method employs a plurality of slitter discs mounted for rotation on a driven shaft for slitting a cured blanket of material. After the blanket has been cut into strips by the slitter discs. the strips enter a rotary cutter which includes a support member mounted to a rotary axle. Cutting blades are mounted to the support member and serve to cut the strips as they pass between the cutting blades and a stationary cutting bed. Although somewhat effective for producing loose-fill insulation, cutters of this type and hammermills tend to require a significant amount of maintenance due to the dulling of their cutting edges or knives. Such equipment also tends to produce a high level of dust. Also, because of the blade spacing arrangement employed in such

equipment the fibers can become bunched which can lead to the passage of some fibers through the machine without being cut.

Thus, there is a need for a method and apparatus for producing loose-fill fibers having uniform lengths suitable for installation in structures utilizing known installation techniques.

There is another need for a method and apparatus for producing loose-fill insulation materials that do not form clumps which can reduce its thermal insulation efficiency.

There is still another need for a method and apparatus for producing loose-fill insulation that produces a reduced amount of dust than is created by prior methods and apparatuses.

Another need exists for an apparatus for cutting fibrous insulation material into uniform lengths that does not require a level of maintenance commonly associated with prior cutting apparatuses.

Yet another need exists for a blade adapted for use on hammermills that has a longer useful life than prior hammermill blades and reduces the maintenance commonly associated with such equipment.

SUMMARY OF THE INVENTION In accordance with a particularly preferred form of the present invention there is provided an apparatus for cutting fibrous material. In a preferred form, the apparatus comprises a housing constructed to receive a continuous flow of fibrous material therein.

A driven rotary shaft and at least one stationary cutting member are supported within the housing. The apparatus also preferably includes a plurality of rotary cutting blades that are attached to the driven rotary shaft. Each rotary cutting blade has an arcuate leading edge and an arcuate trailing edge that converge to form a cutting surface and is mounted to the rotary shaft in abutting relationship with other rotary cutting blades to form at least one continuous row of cutting blades extending along the shaft. Each row of cutting blades is oriented relative to each stationary cutting member such that as the rotary shaft is rotated within the housing, the fibrous material that enters the housing is cut to a predetermined length as it passes between the rotary cutting blades and the stationary cutting members.

Another embodiment of the present invention comprises a system for producing loose-fibrous mineral material. In a preferred form, the system includes at least one fiberizer for producing a plurality of mineral fibers and a first conveyor for conveying the plurality of mineral fibers. The system also includes a cutting apparatus for cutting the plurality of mineral fibers into predetermined lengths. The cutting apparatus has a housing constructed to receive the plurality of mineral fibers from the first conveyor. In addition, at least one stationary cutting member is mounted within the housing. A driven rotary shaft is mounted within the housing and has a plurality of rotary cutting blades affixed thereto. Each rotary cutting blade has an arcuate leading edge and an arcuate trailing edge that converge to form a cutting surface and is mounted to the rotary shaft in abutting relationship with the other rotary cutting blades to form at least one continuous row of cutting blades that extends along the shaft. Each row of cutting blades is oriented relative to each stationary cutting member such that as the rotary shaft is rotated within the housing, the mineral fibers entering the housing are cut to a predetermined length as they pass between the rotary cutting blades and a stationary cutting member.

The present invention also comprises a blade for a rotary cutting machine that has a housing, a stationary cutting member affixed within the housing and a driven rotary shaft mounted within the housing. In a preferred form, the blade includes an attachment portion for non-rotatable attachment to the shaft. In addition, the blade preferably has an arcuate leading edge and an arcuate trailing edge spaced from the leading edge. The leading and trailing edges extend from the attachment portion and converge to form a cutting surface. The blade also preferably has an orientation means on the attachment portion for orienting the blade on the rotary shaft relative to the stationary cutting member such that as a material is passed between the blade and the stationary cutting member, the material is severed therebetween.

It is a feature of the present invention to provide a method and apparatus for forming insulation fibers of uniform length that are suitable for installation into structures utilizing conventional loose-fill installation techniques and equipment.

It is another feature of the present invention to provide a method and apparatus for forming loose-fill insulation material that creates less emissions and dust that is commonly associated with prior apparatuses and methods for forming loose-fill insulation.

Another feature of the present invention is to provide an apparatus for cutting fibrous insulation material into uniform lengths that has longer blade lives than prior fiber cutting equipment.

Accordingly, the present invention provides solutions to the shortcomings associated with prior methods and apparatuses used to produce loose-fill insulation.

Those of ordinary skill in the art will appreciate, however, that these and other details, features and advantages will become further apparent as the following detailed description of the preferred embodiments proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying Figures, there are shown present preferred embodiments of the present invention wherein: Fig. 1 is a diagrammatic representation of a preferred process of the present invention for fabricating loose-fill insulation; Fig. 2 is a cross-sectional elevational view of a preferred fiber cutting apparatus of the present invention; Fig. 3 is a front elevational view of the fiber cutting apparatus of Fig. 2; Fig. 4 is a side elevational view of the fiber cutting apparatus of Figs. 2 and 3; Fig. 5 is an end view of the cutter assembly of the cutting apparatus of Figs. 2-4 with some of the cutting blades thereof omitted; Fig. 6 is a cross-sectional view of the cutter assembly of Fig. 5 taken along line VI-VI in Fig. 5; and Fig. 7 is a side view of a preierretl cutting blade of the present invention.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE PRESENT INVENTION Referring now to the drawings for the purposes of illustrating the preferred embodiments of the present invention only and not for purposes of limiting the same, Fig.

1 is a diagrammatic depiction of a preferred system 10 for manufacturing loose-fill fiberglass capable of being installed with conventional wool blowing equipment to a light blown density (e. g., 0.500 PCF). As can be seen in Fig. 1, streams 16 of molten glass are supplied from the forehearth 14 of a furnace 12 to conventional rotary fiberizers 18 to

form veils 20 of glass fibers which are collected on a conveyor 22 to form a fibrous glass blanket 24. While only two rotary fiberizers 18 are shown, in actual practice, many fiberizers may be employed.

The individual fibers of the veils 20 assume generally horizontal positions on the <BR> <BR> <BR> <BR> conveyor 22 and are approximately 1/2''long. The fiber entanglement length can reach 6"- 8". The fibers are preferably coated with a lubricant after they are formed. In this embodiment, rings or a series of nozzles 26 are positioned around each veil 20 of fibers which supplies lubricant from a source 28 to the fibers. The supply of lubricant is controlled by a rotary valve 27, which regulates the amount of lubricant and length of time it is applied to the fibers. By opening and closing the valve 27 intermittently, different sections of fibers become coated while other sections remain uncoated. A commercially available lubricant is used and is preferably applied to the fibers at a rate of 0.10% by weight. Also, the fibers created by the subject invention are binderless. By 'binderless,"it is meant that binder materials comprise less than or equal to one percent by weight of the product. The reader will appreciate, however that the term"binder"does not encompass materials employed for dust suppression or lubrication.

As can also be seen in Fig. 1, the conveyor 22 conveys the glass blanket 24 to a preferred cutting apparatus 30 of the present invention. The glass blanket 24 is approximately one foot high as it forms on the conveyor 24 and it is preferably compressed to an approximate height of 3"by an upper conveyor 29 prior to entering the cutting apparatus 30. A preferred cutting apparatus 30 has a housing assembly 31 that includes an upper housing portion 32 and a lower housing portion 34. Upper housing 32 portion is preferably arcuate in shape aKd defines an upper arcuate cutting chamber 36.

Housing 31 is preferably fabricated from steel and, to facilitate easy assembly and disassembly, is of bolted construction. However. other materials and constructions could be successfully employed. Lower housing 34 is preferably configured as shown in Figs. 1 and 2 and forms a lower vacuum chamber 38. A collection duct 40 is preferably attached to the lower housing for receiving the cut fibers therein and transporting them through an exit blower 112 and exit ducts as will be discussed in further detail below.

Housing portions 32 and 34 cooperate to define an entry passage 50 through which the fiber blanket 24 is permitted to enter the housing 31. To facilitate cutting of the fibers as they pass into the cutter 30, two stationary cutting bars 52 extend the length of the

cutter 30. Preferably, stationary cutting bars 52 are fabricated from hardened steel and are retained within the lower housing portion 34 by bolts. Also supported within the vacuum chamber 38 in lower housing portion 34 are a series of arcuate screens 60. Arcuate screens 60 extend the length of the cutter 30 and are retained in the lower housing portion 34 by the two stationary cutting bars 52. As can be seen in Fig. 2, screens 60 serve to define a lower arcuate cutting chamber 62 within housing 31. In a preferred embodiment, screens 60 have a plurality of uniformly distributed apertures 64 therethrough that are of equal diameters. Preferably, approximately fifty percent of each screen's surface area is open. In a preferred embodiment, apertures 64 are each 2"in diameter. However, other aperture diameters could be successfully employed.

Rotatably supported within the housing assembly is a rotary cutter bar assembly 70. Cutter bar assembly 70 is rotatably supported by commercially available bearings 72 affixed to the exterior of housing assembly 31. As can be seen in Figs. 2 and 6. cutter bar assembly 70 comprises a cutter bar shaft 74 and a plurality of spacer rings 76 axially received on the shaft 74 in abutting relationships. Rotary cutter bar assembly 70 is rotated in a clockwise direction (represented by arrow"A"in Fig. 2) by a commercially available variable speed electric motor (now shown) that is coupled to the cutter bar shaft 74 by a chain and sprocket arrangement (not shown). Spacer members 76 each have a central bore 78 therethrough for receiving cutter bar shaft 74. The spacer members 76 are preferably retained on shaft 74 by collars 79 that are threaded onto the shaft 74 as shown in Fig. 6. As will be discussed in further detail below, each spacer member 76 has a plurality of bores 80 therethrough for facilitating attachment of rows 91 of rotary cutting blades 90 to the shaft 74.

A preferred cutter bar assembly 70 of the present invention also employs unique and novel cutting blades 90 to cut the fibers entering the housing assembly 31 into uniform lengths. Preferably, each cutting blade 90 is cast from a cast iron alloy and is heat treated and tempered throughout the entire blade mass to provide each blade with a Brinell hardness of approximately 700-715. As can be seen in Fig. 7, each blade 90 preferably has an attachment portion 92. an arcuate leading edge 94 and an arcuate trailing edge that converges with the leading edge 94 to form a cutting surface 98. The attachment portion 92 of each blade preferably has a pair of arcuate mounting shoulders 100 for orienting the blade 90 in a predetermined orientation relative to the adjacent

spacer members 76. In addition, a pair of mounting holes 102 are provided through the attachment portion 92 of each blade 90. The blades 90 are preferably attached between the spacer member 76 by rods 106 that are inserted through holes 80 in the spacer members 76 and holes 102 in the blades 90. The rods 106 are retained in position by corresponding nuts 108 that are removably attached to the outermost spacer members 76 as shown in Figs. 5 and 6. Nuts 108 are preferably removably attached to the spacer members by cap screws 110. To prevent fibers from becoming entangled, or to pass through uncut, between adjacent blades 90, it is desirable to minimize the amount of space (represented by arrow"B"in Fig. 6) between each adjacent blade 90. In a preferred embodiment, we have found that a space size of 1/8"or less prevents fibers from becoming entangled between blades 90 while facilitating easy assembly of the blades 90 to the shaft 74. As the fibers enter the entry channel 50 in the housing assembly 31, they are cut to a preferred length when they pass between the blades 90 and the stationary cutting bars 52. In a preferred embodiment, a clearance of 3/16"is provided between the cutting surface 98 of each blade 90 and the stationary cutting bars 52. A clearance of 3/16"is also preferably provided between the cutting surfaces 98 of the blades 90 and the arcuate screens 64. Acceptable results can be achieved with clearances (between the cutting surfaces 98 of the blades 90 and the cutting bars 52 and between the cutting <BR> <BR> <BR> <BR> <BR> surfaces 98 of the blades 90 and the screens 64) that range from 1/8"to'/4".<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <P> Preferably, the entangled fibers are cut into 1/2"lengths. Preferably a plurality of blade rows 91 are employed and are spaced at equal angles relative to each other.

However, the skilled artisan will appreciate that the lengths of the fibers can be varied by adjusting the rate at which conveyor 22tffeeds the fibers into the cutting assembly 30, the number of blade rows 91 provided on the cutter bar assembly 70, and/or the speed at which the cutter bar assembly 70 is rotated. For example, we have found that by feeding the fibers at a rate of 15 feet per minute and employing two rows 91 of blades (oriented at 180 degrees relative to each other) and rotating the cutter bar assembly 70 at 1200 rpm, uniform entangled fiber lengths of'/2"can be achieved while producing a considerable less amount of dust than is typically created by prior fiber cutting apparatuses. However. other blade orientations, fiber feed rates and cutter bar assembly speeds can be successfully employed.

As can be seen in Figs. 1 and 2, a collection duct 40 is affixed to the lower end of the lower housing portion 34. A vacuum blower 112 is operably attached to the collection duct 40 for creating a suction within the housing assembly 31. The skilled artisan will appreciate that the vacuum blower 112 causes the cut fibers to be drawn through the screens 64 and discharged through the blower 112 into an exit duct 114. The exit duct 114 carries the cut fibers to a conventional bagging assembly 11-6 which bags the fibers for shipment to the construction site. If desired, the fibers are sprayed utilizing conventional equipment (represented by"118"in Fig. 1) with a dust suppressant and/or an anti-static agent and/or a dye after cutting. Preferably, the dust suppressant is a mineral oil, quaternary ammonium salt or combinations thereof. If a quaternary ammonium salt is employed, the dust suppressant/anti-static agent is preferably a modified fatty dimethyl ethylammonium ethosulfate. Suitable quaternary ammonium salts are disclosed in U. S.

Patent No. 4,555,447 to Sieloff, et al., the disclosure of which is herein incorporated by reference. To aid in coating ability, the quaternary ammonium salt may be mixed with a non-ionic lubricant material. A suitable dust suppressant/anti-static agent is available from PPG Industries, Inc. of Pittsburgh, Pennsylvania. The dust suppressant/anti-static agent may be applied by traditional means such as dilution with water, followed by spraying onto the cut loose-fill insulation.

The operation of a preferred system 10 will now be reviewed with reference to Fig. 1. As the fibers 20 exit the fiberizers 18, they pass through rings or lubrication sprays 26 which apply a lubricant thereto. The fibers then fall onto a conveyor 22 and form a glass blanket 24. Conveyor 22 carries the glass blanket 24 to the entry passage 50 of the cutter assembly 30. Just prior to entering entry passage 50, the glass blanket 24 is compressed to a desired height by conveyor 29. As the fibers enter the housing assembly 31 of the cutter assembly 30, the entangled fibers are sheared to desired lengths between the rotating cutters 90 and stationary cutting bars 52. If the fibers are not initially cut as they enter the housing 31, the cutter bar assembly 70 carries the uncut fibers in an orbit around the upper arcuate cutting chamber 36 and the lower arcuate cutting chamber 62 until they are eventually cut to a desired length. The cut fibers are then drawn through the screens 64 into the collection duct 40. The blower 112 discharges the fibers into an exit duct 114 which carriers the cut fibers to a bagging apparatus 116. Dust suppressant, dye, and anti-static agents may be applied to the cut fibers prior to entering the bagging

assembly for packaging into bags for shipping to the installation site. Once at the installation site, the loose-fill insulation fabricated by the present invention may be unpackaged and installed by hand or preferably by blowing. Where the insulation is blown, the insulation is added to the hopper of a standard blowing device and blown into position. Such pneumatic installation process can be performed by any known blowing technology known in the art.

The unique and novel blade design of the present invention provides significant improvements over prior blades employed in hammermills and other fiber cutting apparatuses. In prior cutters that utilize rotary blades that have non-arcuate leading and trailing edges in combination with stationary cutter blades, those blades are typically mounted with an amount of clearance therebetween that often results in the bending (and not severing) of the fibers as they pass between the blades resulting in the production of fibers that do not have uniform lengths. We have found that by using blades with arcuate leading and trailing edges that converge to form cutting surfaces, the amount of clearance between such blades and a stationary blade can be maintained as the blades wear. That is, as a blade 90 wears, the clearance or gap between the cutting surface 98 of a blade 90 and the stationary cutters 52 and the screens 60 is maintained due to the arcuate shaped leading and trailing edges. Such unique and novel blade configuration contributes to blade life and precision cutting capabilities. Thus, the present invention overcomes that problem associated with prior fiber cutters.

The present invention also employs rotary cutters that are used in connection with two stationary cutters that are located within the housing such that, should the fibers not be cut to the desired length when they initially enter the housing, the rows of arcuate or "hook-shaped"blades carry the uncut fibers in a circuitous path until they are eventually severed between the rotary and stationary blades. Thus, the present invention provides an improved method for producing loose-fill fibers having uniform lengths. Because the present invention quickly cuts the fibers to desired lengths, less dust is created due to the pulverization of uncut fibers within the machine. We have also determined that by casting the blades from cast iron alloy and heat treating and tempering them throughout their entire mass, along with providing them with arcuate leading and trailing edges that converge to form a cutting surface, improved blade lives can be achieved. For example, blades employed on prior cutters generally have a useful life of 12-20 weeks. We believe

that the blades of the present invention will last at least two years in continuous service.

Also, because the subject invention provides the flexibility of cutting fibers at a variety of different lengths and speeds by adjusting the feed speed, the cutter speed, and altering the number of blade rows, the fiberizer gas and air mixture can be optimized to reduce the amount of emissions created thereby.

Accordingly, the present invention provides solutions to the aforementioned problems associated with prior apparatuses and methods for producing loose-fill insulation. Those of ordinary skill in the art will appreciate that various changes in the details, materials and arrangements of the parts which have been herein described and illustrated in order to explain the nature of the invention may be made by the skilled artisan within the principle and scope of the invention as expressed in the appended claims.