US20040211067A1

US20040211067A1 - Rotary knife having suction adapter

Info

Publication number: US20040211067A1
Application number: US10/852,968
Authority: US
Inventors: Jeffrey Whited; Martin Niederhauser
Original assignee: Bettcher Industries Inc
Current assignee: Bettcher Industries Inc
Priority date: 2002-11-07
Filing date: 2004-05-25
Publication date: 2004-10-28
Also published as: US6857191B2; US20040088864A1; ES2277073T3; EP1558430B1; DE60309737D1; WO2004043655A1; US7107887B2; AU2003221956B2; DE60309737T2; US20050115082A1; AU2003221956A1; BR0303026A; EP1558430A1

Abstract

A rotary knife having a ring blade that defines a closed loop cutting surface for cutting material which the ring blade contacts during rotation. Materials cut using the blade such as meat cut from a carcass or trimmed from a piece of meat are suctioned away from the blade. The material is drawn into a blade housing which supports the ring blade. A housing body has a wall that defines a housing interior into which material separated by the cutting surface of the ring blade moves as it is cut. Alternate blade designs facilitate use of the knife for applications involving the separation of a spinal cord and possibly dangerous BSE material from a slaughtered animal.

Description

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part application having subject matter in common with U.S. patent application Ser. No. 10/289,635, filed Nov. 7, 2002, from which priority of the present application is claimed.[0001]

FIELD OF THE INVENTION

The present invention concerns a rotary knife having a ring blade supported by a blade housing. An attachment to the blade housing provides suction to the blade housing interior to remove material as the blade cuts the material from a product.

BACKGROUND ART

U.S. Pat. No. 4,170,063 to Bettcher discloses a knife having a removable blade. The '063 patent is assigned to Bettcher Industries, Inc., the assignee of the present invention. The '063 patent discloses a hand knife having a ring-like rotary blade that is supported by a handle that extends normal to an axis of rotation of the blade. The blade of the knife is rotatably supported in a housing that surrounds a part of the blade. The blade can be removed for sharpening or replacement of the blade. Other representative United States patents relating to rotary knives that are assigned to the assignee of the present invention are U.S. Pat. Nos. 4,439,924, 4,516,323, 4,509,261, and 6,655,033.

Published German Utility Model DE 295 12 854 U 1 entitled “Rotating Cutter with Suction Removal for Meat or Fat” concerns a rotary knife. Meat parts that have been cut from meat are removed by a suction apparatus. The disclosed suction removal apparatus includes a tubular connecting piece, one end of which exhibits an outside diameter that essentially corresponds to the inside diameter of a ring-shaped blade housing and a second end of which is configured for connection of a hose.

As depicted in FIG. 2 of this German Utility Model a connecting piece is coupled to a blade housing to provide a connection between the blade housing and a hose coupled to a connecting container. The connecting piece is fastened in the blade housing by means of two screws. The connecting piece exhibits slots through which the screws pass. The screws are loosened somewhat so that the connecting piece is no longer clamped by the screws and can then be separated from an outlet opening of the blade housing.

The rotating blade knife disclosed in co-pending U.S. patent application Ser. No. 10/289,635 has been used with success in removing tissue at risk for BSE (Bovine Spungiform Encephalopathy) from slaughtered animals. In the removal of BSE-risk material, the knife loosens BSE-risk material from the animal carcass and draws it into a suction channel before the risk material the is completely cut off the carcass by the cutting blade and sucked away via the suction channel.

To remove the BSE-risk material, the rotating blade knife is directed along the spinal canal from the top to the bottom, whereby the risk material that has been loosened by the vacuum suction is cut by the moving blade. In practice, the greater the vacuum pressure, the more effective the device is at removing the risk material. However, in practice there are limitations in the vacuum systems.

One of the major problems with the removal of spinal cords in pork is the fact that when a hog is split lengthwise along the backbone, the cut is often off center with respect to the spinal cord cavity due to the smaller size of the cavity as compared to beef animals, causing sections of the spinal canal to be closed. Such off center cuts effectively prevent portions of the spinal cord in such closed sections of the spinal canal from being drawn into the suction channel.

SUMMARY OF THE INVENTION

The invention concerns a rotary knife having a ring blade that defines a closed loop cutting surface for cutting material which the ring blade contacts during rotation. Materials cut using the blade, such as meat cut from a carcass or trimmed from a piece of meat, are suctioned away from the blade.

One embodiment of a circular cutting blade includes a reduced cross section in a region a blade cutting surface. This causes an increase in removal velocity and negative pressure at the entrance point of the blade. The increase in the negative pressure causes a greater pull on the spinal cord and the BSE-risk material. The knife can cut further into the dorsal ganglia to extract more BSE-risk materials, including dorsal root ganglia.

One alternate circular cutting blade is designed to have a portion that will go into a hollow section of the spinal canal for suctioning away the spinal cord. On an outer surface this alternate circular cutting blade includes a series of cutting or milling blades around the outer diameter of the blade. These outer cutting or milling blades will cut open closed sections of the spinal canal as the blade is moved along the canal thereby permitting more complete removal of the spinal cord.

Alternate exemplary embodiments of the invention are described with a degree of particularity in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a rotary cutting knife constructed in accordance with an exemplary embodiment of the invention; [0013]
FIG. 2 is an exploded perspective view of a distal end of the rotating blade cutting knife shown in FIG. 1; [0014]
FIG. 3 is a plan view of a distal end of the [0015] knife 10 shown in FIG. 1;
FIG. 4 is a view as seen from the plane defined by the line [0016] 4-4 in FIG. 3;
FIG. 5 is a plan view of an adapter that engages the knife and connects to a tube for routing severed material away from the knifes cutting blade; [0017]
FIG. 6 is a view as seen from the plane defined by the line [0018] 6-6 in FIG. 5;
FIG. 7 is a perspective view of a first embodiment of a cutting blade used with the knife of FIG. 1; [0019]
FIG. 8 is a top plan view of the first embodiment of the cutting blade; [0020]
FIG. 9 is a section view as seen from the plane defined by the line [0021] 9-9 in FIG. 8;
FIG. 10 is a perspective view of a second embodiment of a cutting blade used with the knife of FIG. 1; [0022]
FIG. 11 is a plan view of the second embodiment of the cutting blade of FIG. 10; [0023]
FIG. 12 is a top plan view of the second embodiment of the cutting blade of FIG. 10; [0024]
FIG. 13 is a section view of the second embodiment as seen from the plane defined by the line [0025] 13-13 in FIG. 12;
FIG. 14 is a view of the cutting blade of FIG. 11 as seen from the plane defined by the line [0026] 14-14 in FIG. 11;
FIG. 15 is a view of the cutting blade as seen from the plane defined by the line [0027] 15-15 in FIG. 11;
FIG. 16 is a perspective view of an alternate adapter for engaging a blade housing; [0028]
FIGS. 17 and 18 are side and top views of the adapter of FIG. 16; [0029]
FIG. 19 is a section view as seen from the plane defined by the line [0030] 19-19 in FIG. 17; and
FIG. 20 is a perspective view showing an exemplary embodiment of the knife in use.[0031]

EXEMPLARY EMBODIMENTS FOR PRACTICING THE INVENTION

FIGS. 1 and 2 depict a [0032] rotary knife assembly 10 having a ring blade 12 that cuts material with which it comes in contact. The ring blade 12 has a closed loop cutting surface 14 (FIG. 9) for cutting material that the ring blade contacts during use of the knife 10. In accordance with one use of the rotary knife, the blade 12 is used to separate a spinal cord from the carcass of an animal after the animal has been slaughtered. Another application of the rotary knife is to clean meat or fat from an animal that has been partially processed using other knives. In this application, the meat that is removed is collected and processed into a consumable meat product.
FIG. 20 is a depiction of a use of the [0033] knife 10 for removing a spinal cord 22. from a animal carcass. The spinal cord 22 is cut away from a cavity or canal 23 spaced between the animal's vertebrae 24. By skilled manipulation of the cutting surface 14, the user can separate the spinal cord from the carcass in one piece. Removal of the spinal cord 22 is desirable because it is BSE-risk material.
The rotary knife depicted in FIG. 1 has a [0034] handle assembly 20 that is manipulated by a user and which supports a blade housing 30 at a distal end. The blade housing 30, in turn, rotatably supports the ring blade 12. The blade housing 30 has a housing body having an inner wall 34 (FIGS. 2 and 4) that defines a generally cylindrical housing interior into which material separated by the cutting surface 14 (FIG. 9) of the ring blade 12 moves as it is cut. The blade housing 30 includes a circumferential bearing surface that is defined by the wall 34 at an engagement end where the blade 12 engages the housing 30. The bearing surface supports the ring blade 12 while allowing the ring blade to rotate with respect to the blade housing 30.
A notch (not shown) in the [0035] body wall 34 allows the bearing surface to be expanded outwardly for separating the ring blade 12 from the blade housing 30. Should the ring blade need to be sharpened or replaced, the bearing surface is expanded and the ring blade slips out of the housing through an expanded or widened opening in one end of the blade housing 30.
At an end of the [0036] blade housing 30 spaced from the bearing surface, the housing body defines a coupling portion for coupling the housing to a suction tube 52 (FIG. 1) that withdraws material from the blade housing interior away from the ring blade 12.
FIG. 2 illustrates components of a distal portion of a [0037] drive assembly 60 that provides motive power to rotate the ring blade 12. The drive assembly 60 is commercially available as part of a Model Series II rotary knife sold by Bettcher Industries, Inc. The drive assembly 60 includes a drive shaft 62 that is coupled to a gear 64 that engages gear teeth 66 of the ring blade 12. A user actuated lever 59 extends outwardly from a bottom of the handle 20 (FIG. 1). When the lever is pivoted toward the handle 20, a valve inside the handle routes pressurized air through into the handle 20 routed through an air hose 130 coupled to an air source external to the handle to activate an air motor 61 (FIG. 4) mounted inside the handle 20. A rectangular end 65 of the drive shaft engages an output shaft of the air motor 61. The drive shaft 62 extends into and rotates a pinion assembly 63 that supports the gear 64. With the drive assembly 60 assembled, the gear 64 engages or meshes with a gear 66 at one end of the blade 12. Selective activation of the air motor by the user thereby causes the ring blade 12 to rotate. Additional details of operation of the air motor are contained in U.S. Pat. No. 6,655,033 which is assigned to the assignee of the present invention and is incorporated herein in its entirety by reference.
As seen in FIGS. 1 and 2, the [0038] drive assembly 60 is supported by the handle assembly 20 including a handle frame 68 and a head portion 67 that extends from the frame member 68. The head portion 67 also supports the blade housing 30 in such a way that the gear 64 aligns with the gear teeth 66 of the blade 12. The frame 68 also supports an interchangeable handle grip 71 (FIG. 4) that can be removed from the frame 68. Different size grips are provided for use by different individuals and are chosen to match the size of the user's hand.
During assembly of the knife, the [0039] air motor 61 is inserted into position within the handle assembly 20 from one end into the handle frame 68 and a screw 73 having a throughpassage to accommodate the drive shaft 62 is inserted into an opposite end of the frame 68. The screw 73 has a threaded exterior surface that engages an inner threaded surface of the handle assembly. With the air motor 61 secured within the handle assembly 20, the drive shaft 62, a bearing 75 (FIG. 2) for the pinion assembly 63 and the pinion and attached gear 64 are inserted into the handle frame 68. The knife assembly 10 is completed by attaching the blade 12 and blade housing 30 to the frame head portion 67 as described below. A lubricant is supplied to the interface between the pinion 63 and the bearing 75 by means of a fitting 116 (FIG. 2) which routes lubricant into the frame member 68. The lubricant passes through a hole 75 a in the body of the bearing 75 to lubricate the bearing interior.
The embodiment of the invention depicted in FIG. 1 includes the [0040] flexible suction tube 52 that fits over an adapter 110 (FIGS. 2 and 4) that engages the blade housing 30 at an end removed from the housing's bearing surface. A vacuum source (not shown) connected to an opposite end of the tube 52 creates a suction inside the blade housing 30 in the vicinity of the ring blade 12. The suction tube 52 has a smooth inner surface to allow the tube to be slipped over the adapter 110. Suction applied by the tube 52 attracts material cut by the blade 12 that enters the housing 30. In one use, the knife 10 is used to cut meat so that meat trimmings pass through the tube 52 into a collector or container for the material removed from the carcass. A second use is to collect a spinal cord and accompanying BSE-risk material from a carcass. This additional use is illustrated in the FIG. 20 depiction. The suction tube 52 is constructed from polyeurethane and has an inside diameter of approximately 1½ inches and is commercially available from a number of sources.
The [0041] blade housing 30 is generally cylindrical in shape and is machined to form the depicted housing shape. The housing 30 has interior surfaces defined by the wall 34 that extends from a region of the bearing surface where the housing supports the blade to a top or coupling portion 50 of the housing 30 that engages the adapter 110. An outer surface of the blade housing 30 between the bearing and the coupling portion 50 has two cutouts 70 (FIG. 2) machined into the housing 30 to increase the flexibility of the housing. As noted above, the housing 30 is expanded outwardly to allow the blade 12 to be removed from the housing 30.
The [0042] housing 30 defines a bead B (FIG. 4) that defines a bearing surface for rotatably supporting the ring blade 12. A semi-circular gap 80 (FIG. 2) in the housing coincides with a position of the gear 64 so that the gear meshes with the teeth 66 of the blade when the blade housing 30 is attached to the head portion 67. During assembly of the knife 10, the blade housing 30 is attached to the head 67 by means of an arcuate mounting plate 84 (FIG. 2). The mounting plate 84 is a trapezoidal shaped metal plate that has a bend that conforms generally to a radius of curvature of the blade housing's interior wall surface. With the air motor 61 installed, the gear 64 extends into the gap 80 in the housing 30 and the plate 84 is connected to the head 67 by two screws 86 a, 86 b that pass through the plate 84 and an appropriately aligned slot 89 in the wall 34 of the blade housing 30. The screws 86 a, 86 b thread into openings 71 (one of which can be seen in FIG. 2) in the head 67 and are tightened by a screwdriver that is inserted into the housing through openings 90 that extend through the housing wall 34.
The [0043] blade 12 is attached to the housing 30 after the housing is attached to the head 67. To attach the blade 12, one must widen a bottom diameter of the housing 30. To expand the opening at the bottom of the housing 30 wide enough to slip the blade 12 into the housing, the user tightens the screw 86 a which passes through the slot 89 while leaving the second screw 86 b which extends through a slot (not shown) loosely threaded into the head 67. The wall 34 has three lands 91 (FIG. 2) that extend outwardly in a line along the side of the housing 30. With the housing 30 attached to the head portion 67 the user can insert a flat bladed screwdriver or the like into a slot or recess between two adjacent lands 91 and pry the screwdriver blade against the side of the head portion 67 to enlarge or widen an opening surrounded by the bead B so that the largest diameter part of the ring blade passes through the opening. To affix the blade in place, the user releases the flat blade of the screwdriver and the flexed wall 34 returns to its normal shape and the bearing surface of the bead B fits into a groove 94 (FIG. 9) that extends circumferentially around the ring blade 12 in the region of the gear teeth 66. With the blade 12 secured to the housing 30, the second of the screws 86 b is tightened to securely hold the housing 30 in place against the head portion 67.
As best depicted in FIG. 2, an [0044] interior wall 34 of the housing 30 has a knurled surface 34 a. This surface 34 a engages a similarly knurled convex surface 84 a of the arcuate plate 84 that covers the gear 64. The frictional engagement between the arcuate plate 84 and the housing 30 is increased due to the presence of these conforming knurled surfaces 34 a, 84 a and this avoids inadvertent loosening of the engagement between the blade 12 and the housing 30 during operation of the knife 10.
First Blade Embodiment [0045]
The particular shape of a first embodiment of the [0046] blade 12 is seen in greater detail in FIGS. 7-9. The blade 12 (machined from bearing steel, has inner and outer walls 100, 102 that define a blade body of varying thickness in a region that extends between the groove 94 that engages the housing bead B and the cutting surface 14. The outer wall 102 tapers inwardly along two stepped circumferential portions 102 a, 102 b.
The [0047] blade 12 has an elongated blade body 101 that defines a throughpassage 101 a to allow severed material to move away from the region of the cutting surface 14. The throughpassage 101 a is bounded by a first inner wall portion 103 having a generally cylindrical wall surface of a first diameter D1, a second inner wall portion 104 that extends into the blade body 101 to form a concave surface of greater diameter D2 than the first diameter D1. Near the cutting surface 14, the concave surface curves back toward a blade centerline to a cutting surface diameter D3 that is less than the first diameter D1. The blade body 101 has an additional inner wall portion 105 that forms a convex surface that widens outwardly from the generally cylindrical wall surface 103 to a radially inner side of the gear 66. Note, the diameter D3 is the smallest diameter of the blade and use of this reduced diameter has an advantage in creating adequate suction in the region of the cutting surface 14. The small diameter creates a maximum air flow toward the blade housing 30 (and the suction tube 52 and vacuum source connected to the tube 52) in the region of the cutting surface 14 and, hence, greatly enhances the sucking action of the knife 10 in the vicinity of the cutting surface 14. Representative dimensions for the three diameters D1, D2, and D3 are 0.77, 0.81, and 0.69 inches respectively.
[0048] Adapter 110
The [0049] knife 10 is coupled to a vacuum source by the tube 52. The generally cylindrical adapter 110 is constructed from aluminum and is removably connected to the blade housing 30. As seen in FIGS. 2 and 4-6 the housing 30 includes a flange 112 that overhangs a groove 113. The flange 112 and groove 113 extend along a semicircular arcate portion 50 a that extends around only part of the top portion 50 of the housing 30. The arcuate portion 50 a is spaced from the frame head 67 with the housing 30 coupled to the frame 68. The adapter 110 has a corresponding groove 115 and lip 116 (FIG. 5) that mate with the flange 112 and groove 113 of the housing 30. With the housing 30 spaced from the head 67, a user can manually connect the adapter 110 to the housing 30 by sliding the adapter lip 116 into the groove 113 of the housing 30. The combined adapter/housing is then attached to the head 67. As seen in the section view of FIG. 6, in one embodiment of the knife 10, the adapter 110 has a necked down interior defined by a minimum diameter portion 117. Both above and below this necked down interior diameter 117, the interior flares outwardly along portions 118, 119. In use, the tube 52 slips over the adapter 110 and is secured in place by a hose clamp 118. Further details of the operation of the adapter 110 are found in German patent DE 102 17 195 C1.
An [0050] alternate adapter 110′ for use with the present knife is depicted in FIGS. 16-19. The adapter 110′ has an interconnection with the housing identical with the interconnection of the adapter 110. A cylindrical throughpassage 119 however for sucking materials away from the knife is uniform along the length of the adapter 110′ In the illustrated embodiment this diameter is 0.9 inches.
Attached to the [0051] knife 10 at an end of the handle assembly 20 removed from the blade housing 30 is a generally cylindrical hose guide 120 (FIG. 1) supported by a bracket 122 that extends outwardly away from the handle 20. A collar 124 supports the bracket 122 and fits over a handle assembly portion 126. The collar 124 slides over the end portion 126 and is secured to the frame by two set screws 128 at ninety degrees with respect to each other (only one of which is seen in FIG. 1). The guide 120 is sized to allow the hose to be slipped through the guide before the hose is attached to the adapter 110. The guide 120 prevents the suction tube 52 from getting in the way as the user manipulates the knife. The guide keeps the tube 52 from rubbing against the users hand and prevents the tube 52 from exerting a twisting force that would impede proper operation of the knife. The guide causes the tube 52 and a flexible air hose 130 to approach a region of the handle assembly 20 along generally parallel paths so that any torques they exert against the user as he or she manipulates the knife are of the same direction.
[0052] Alternate Blade 150
FIGS. 10-15 illustrate an [0053] alternate cutting blade 150 for use with knife 10. The blade 150 has an elongated blade body 151 that includes a first, lower inner wall portion 152 (FIG. 13) having a generally cylindrical wall surface of a first diameter and a second inner wall portion 154 that meets the first wall portion and widens or flares outwardly from said first wall portion to a region of the gear 66. As seen most clearly in FIGS. 10 and 11, the blade 150 has flutes 160 (integral with the blade body) that form cutting surfaces in addition to a cutting surface 162 at a bottom of the blade 150. The flutes or splines 160 have an undercut portion 164 that bites into the animal tissue with which it comes in contact as the blade rotates. This design blade has particularly utility with cutting a pork spinal cord out of a slaughtered pig or hog. The flutes 160 are brought into contact with the relatively narrow spinal cord cavity to widen the cavity as the spinal cord is removed. As seen in the plan view of FIG. 15 and the elevation view of FIG. 11, the flutes 160 are wider at the top and taper down to a thinner portion near the cutting surface 162. At the top, the flutes 160 extend outwardly away from the generally cylindrical outer surface 165 of the blade 150 a distance of 0.06 inches. The flutes 160 taper inwardly and at their end near the cutting surface 162 they are not quite flush with the outer surface of the blade but extend only 0.01 inches.
While alternate exemplary embodiments of the invention have been described with a degree of particularity, it is the intent that the invention include all alterations and modifications from the alternate embodiments falling within the spirit or scope of the appended claims. [0054]

Claims

1. A rotary knife comprising:

a) a ring blade comprising a closed loop cutting surface for cutting material which the ring blade contacts during rotation of the ring blade;

b) a housing that supports the ring blade and includes a housing body having a wall that defines a housing interior into which material separated by the cutting surface of the ring blade moves as it is cut, said housing body including a bearing surface that is defined by a wall portion of the housing body for rotatably supporting the ring blade;

c) a drive assembly mounted to a knife handle for providing motive power to rotate the ring blade during operation of the rotary knife; and

d) a source of suction in fluid communication with said housing interior;

e) said ring blade having a blade body including a drive gear at one end that engages the drive assembly and a cutting surface at an opposite end, said elongated body including an interior surface bounding a passageway in fluid communication with the source and that extends between the cutting surface and the drive gear for moving material cut by the cutting surface through the blade body and into blade housing.

2 The apparatus of claim 1 additionally comprising a suction tube that engages the housing body to create a suction region in passageway of the blade body to attract material that is cut during operation of the rotary knife into the passageway.

3. The apparatus of claim 1 wherein the elongated blade body has a first inner wall portion having a generally cylindrical wall surface of a first diameter, a second inner wall portion that forms a concave surface that extends into the blade body to form a concave surface of greater diameter than said first diameter and that curves inwardly near a cutting surface to form a inner surface having a reduced cutting surface diameter that is less than the first diameter.

4. The apparatus of claim 3 wherein the blade body has an additional wall portion that forms a convex surface that widens outwardly from the generally cylindrical wall surface to a diameter of said gear.

5. The apparatus of claim 1 wherein the elongated blade body has a first inner wall portion having a generally cylindrical wall surface of a first diameter, a second inner wall portion that meets the first wall portion and widens outwardly from said first wall portion to a region of the gear; and includes an outer surface having raised cutting surfaces.

6. The apparatus of claim 5 wherein the raised cutting surfaces are formed form a spaced array of flutes that extend outwardly from the outer surface of said elongated blade body.

7. The apparatus of claim 6 wherein the flutes are elongated raised portions that extend away from the blade body and include an undercut portion that define cutting surfaces that engage material as the blade rotates.

8. The apparatus of claim 1 wherein the source of suction comprising a flexible tube for removing material from the blade housing and additionally comprising a bracket attached to the handle that orienting said flexible tube in the region of said knife.

9. The apparatus of claim 8 additionally comprising a sleeve through which the flexible tube extends for orienting and routing the tube away from the vicinity of the blade.

10. A rotary knife comprising:

a) a ring blade comprising a cutting surface surrounding a blade opening for cutting material which the ring blade contacts during rotation of the ring blade;

b) a blade housing having a housing body that defines an interior throughpassage into which material separated by the cutting surface of the ring blade moves as it is cut, said blade housing body including a bearing surface for engaging the ring blade to allow the ring blade to rotate with respect to the blade housing;

c) a handle assembly including a head member which extends outwardly from the handle assembly for supporting the blade housing; and

d) an adapter having an adapter throughpassage for connecting a vacuum source to the blade housing interior throughpassage;

e) said blade opening, blade housing interior throughpassage and adapter throughpassage forming a combined knife throughpassage having a constriction of least cross section at the blade opening near the cutting surface that reduces the pressure in a region of the cutting surface to attract materials into and through the knife throughpassage.

11. The knife of claim 10 wherein the ring blade comprises an elongated blade body that has a generally cylindrical blade throughpassage having a diameter that is greater than a diameter at the constriction at the blade opening.

12. The knife of claim 11 wherein the adapter throughpassage is generally cylindrical and has a diameter that is greater than a diameter of the generally cylindrical blade throughpassage.

13. The knife of claim 10 wherein the blade includes a blade body that widens outwardly to a region of the drive gear of said blade body.

14. The knife of claim 10 wherein the adapter throughpassage is generally cylindrical and of a uniform cross section.

15. A method for suctioning a spinal cord from an animal carcass with a rotary knife having a handle and a drive system supported by the handle comprising:

a) connecting a blade housing having a blade housing body that defines a generally cylindrical body throughpassage to the handle;

b) rotatably supporting a ring blade comprising a closed loop cutting surface that circumscribes an opening having a diameter less than a body throughpassage diameter for cutting material and gear teeth for rotating the ring blade to a bearing surface of the housing body;

c) attaching a suction tube to a coupling body wall portion of the housing body spaced from the ring blade;

d) rotating the ring blade and applying suction to the suction tube to move meat cut by the ring blade into the throughpassage of the blade housing body and subsequently into the suction tube as a user manipulates the closed loop cutting surface relative the carcass.

16. The method of claim 15 wherein the ring blade includes an elongated ring blade body having an outer surface with raised cutting surfaces and additionally comprising moving the blade from side to side to separate material from the carcass for subsequent removal through the opening circumscribed by said cutting blade.

17. The method of claim 15 wherein the suction tube is ridgid and additionally comprising connecting a flexible tube to the suction tube for routing material away from said knife.

18. A cutting blade for use with a rotary knife comprising an elongated blade body having gear teeth at one end for rotating said blade and a closed loop cutting surface at an opposite end and defining a throughpassage bounded by a first inner wall portion having a generally cylindrical wall surface of a first diameter, a second inner wall portion that forms a concave surface that extends into the blade body to form a concave surface of greater diameter than said first diameter and that curves inwardly near the cutting surface to form a inner surface having a reduced cutting surface diameter that is less than the first diameter.

19. The cutting blade of claim 18 wherein the throughpassage of the blade body is bounded by an additional wall portion that forms a convex surface that widens outwardly from the generally cylindrical wall surface to a diameter of said gear.

20. A cutting blade for use with a rotary knife comprising an elongated blade body having gear teeth at one end of said body for rotating said blade and a cutting surface at an opposite end and further having a first inner wall portion having a generally cylindrical wall surface of a first diameter, a second inner wall portion that meets the first wall portion and widens outwardly from said first wall portion to a region of the gear teeth; said body having an outer surface having raised cutting surfaces.

21. The cutting blade of claim 20 wherein the raised cutting surfaces are formed from a spaced array of flutes that extend outwardly from the outer surface of said elongated blade body.

22. The cutting blade of claim 21 wherein the flutes are elongated raised portions that extend away from the blade body and include an undercut portion that define cutting surfaces that engage material with which the blade comes in contact as it rotates.