WO2003011541A1

WO2003011541A1 - Knife and apparatus for clamping a knife

Info

Publication number: WO2003011541A1
Application number: PCT/US2002/022576
Authority: WO
Inventors: Loren R. Schuh; Tobias L. Simonsen
Original assignee: Key Knife Inc
Current assignee: Key Knife Inc
Priority date: 2001-07-30
Filing date: 2002-07-16
Publication date: 2003-02-13
Anticipated expiration: 2004-01-30
Also published as: NZ530756A; EP1414628B1; US20030019543A1; CA2451402C; US6968879B2; ATE422406T1; BR0211719A; CA2451402A1; DE60231126D1; EP1414628A1

Abstract

A knife (10) and apparatus for clamping the knife. The knife has front (12) and back sides (14) that, preferably, both include interlocking features adapted for interlocking engagement with corresponding inner and outer clamping members, to prevent slippage of the knife from the clamping members in orientations wherein the knife rests thereon in the chipping apparatus when the knife is unclamped. Preferably, the interlocking feature of the back side of the knife includes a semi-cylindrical groove, and the interlocking feature of the front side of the knife includes two spaced-apart deflector ridges (18A, 18B). Preferably the interlocking feature of the outer clamping member is a projection having a semi-cylindrical tip portion (27) wherein the semi-cylindrical shape is preferably half-cylindrical, and wherein the projection (32) extends from an inner surface (23) of the outer clamping member sufficiently far that most of the back side of the knife does not make contact therewith.

Description

KNIFE AND APPARATUS FOR CLAMPING A KNIFE

The subject matter of the present application is related to that of the assignee's companion application entitled METHOD AND APPARATUS FOR CLAMPING A

KNIFE, of Thomas Charles Hinchliff, incorporated by reference herein in its entirety.

Background of the Invention

The present invention relates to a knife and apparatus for clamping a knife in a

wood chipper, such as a disc, drum or conical head chipper for use in the commercial

processing of logs.

In wood chipping apparatus used in the forest products industry, a rotating member is provided for receiving replaceable knives for cutting chips from the log.

Each knife is typically clamped to the rotating member between an outer clamping

member and an inner clamping member or counterknife, wherein the knife and

counterknife together form a surface against which the log is forced to remove chips

from the log. The chips themselves have commercial value, and their removal shapes

the log into lumber and finishes its surface. The clamping members essentially form a

cassette for the knife, although the entire cassette is often referred to in the trade as a

knife. Herein, the term "knife" is used to refer to the blade that is clamped between the outer and inner clamping members.

The spacing between the outer and inner clamping members is adjustable for loading the knife into the apparatus, or unloading the knife from the apparatus, such as for replacing the knife or turning the knife end-to-end to position an alternative knife edge in the chipper. A preferred mechanism for adjusting the spacing between an outer clamping member an inner clamping member is described in U.S. Patent No. 5,979,522,

also incorporated herein by reference in its entirety.

As one example of a wood chipping apparatus, a chipper disc typically spins in a vertical plane. A number of identical knives are spaced around the periphery of the disc.

The knives are elongate, and their elongate axes are oriented along radial lines passing approximately through the center of the disc, the axis of each knife becoming horizontal at respective 9:00 and 3:00 positions of the disc. When undamped, the knives are typically unrestrained from sliding along these radial lines, so it is preferable to unclamp

the knives when they are at least approximately in one of these two level positions.

A shroud is typically provided that covers the disc to retain chips and to shield personnel, the shroud including a closeable opening in a predetermined angular position

of rotation of the disc, to provide access to a knife that has become aligned therewith.

The position of the opening is selected so that the heavy and sharp knife will not slip forwardly out of the apparatus when it is undamped; however, even so, the knife remains

free to slip backwardly into the apparatus and still presents some risk of injury or damage.

Such considerations are important as well to other types of wood chippers, such as the

drum and conical head chippers.

Accordingly, there is a need for a knife and apparatus for clamping the knife in a chipping apparatus that provides for more safely and securely preventing movement of an

undamped knife along a line of slippage extending into and out of the apparatus. Summary of the Invention

A knife and apparatus for clamping the knife according to the present invention solves the aforementioned problem and meets the aforementioned need by providing an elongate knife having front and back sides co-terminating in a cutting edge, and outer and

inner clamping members for clamping the knife therebetween adapted to receive,

respectively, the back and front side of the knife. The back side of the knife and the outer clamping member have mutually interlocking features to prevent slippage of the

knife from the outer clamping member in orientations wherein the knife rests thereon in

the chipping apparatus when the knife is undamped.

The front side of the knife and the inner clamping member preferably also have

mutually interlocking features to prevent slippage of the knife from the inner clamping member in orientations wherein the knife rests thereon in the chipping apparatus when the knife is undamped.

In one aspect of the invention, the interlocking feature of the back side of the

knife includes at least one semi-cylindrical groove, wherein the knife is preferably

bilaterally symmetric about a plane parallel to the elongate axis of the knife and wherein the semi-cylindrical shape is preferably half-cylindrical.

In another aspect of the invention, the interlocking feature of the outer clamping

member is a projection having a semi-cylindrical tip portion wherein the semi-cylindrical

shape is preferably half-cylindrical. In yet another aspect of the invention, the projection of the outer clamping member extends from an inner surface thereof sufficiently far that most of the back side of the knife does not make contact therewith, to better control the point of application of

clamping force.

Where the tip portion of the projection is semi-cylindrical, a degree of rotation of

the knife about the projection is permitted which facilitates installation of the knife and which accommodates a greater degree of dimensional variance in the mating parts, further

facilitating installation of the knife as well as reducing manufacturing costs.

Therefore, it is a principal object of the present invention to provide a novel and

improved knife and apparatus for clamping the knife.

It is another object of the present invention to provide a knife and apparatus for

clamping the knife that provides for more safely holding the knife in position in a

chipping apparatus when the knife is undamped therein.

It is yet another object of the present invention to provide a knife and apparatus

for clamping the knife that provides for more securely holding the knife in position in the

chipping apparatus when the knife is undamped therein.

It is still another object of the present invention to provide a knife and apparatus for clamping the knife that facilitates installation and removal of the knife from the chipping apparatus.

It is a further object of the present invention to provide a knife and apparatus for clamping the knife that provides for reduced manufacturing costs of the knife and clamping members.

It is still a further object of the present invention to provide a knife and apparatus for clamping the knife that provides for increased control over the application of clamping force to the knife.

The foregoing and other objects, features and advantages of the present invention

will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the following drawings.

Brief Description of the Drawings

Figure 1 A is a pictorial view of a knife according to the present invention,

showing a front side of the knife in perspective.

Figure IB is a pictorial view of the knife of Figure 1 showing a back side of the

knife in perspective.

Figure 2 A is an elevation of a disc chipper including a plurality of knives such as

that shown in Figures 1A and IB.

Figure 2B is a cross-section of the disc chipper of Figure 2A, taken through a

knife that is in the 3:00 position of the disc along a line 2B-2B, showing the knife

clamped in the disc chipper. Figure 3 A is a cross-section of the disc chipper of Figure 2B, taken through

another knife that is in the 9:00 position of the disc along a line 3A-3A thereof, showing the knife undamped in the disc chipper.

Figure 3B is a cross-section of the disc chipper and knife of Figure 2B, showing the knife in the 3:00 position undamped in the disc chipper.

Figure 4A is a partial cross-section, corresponding to the cross-section of Figure 3B in the 3:00 position, of a knife and outer clamping member according to the present invention.

Figure 4B is a partial cross-section of the knife and outer clamping member of Figure 4A, showing the knife clamped between the outer clamping member and an inner

clamping member.

Detailed Description of a Preferred Embodiment

Referring to Figures 1A and IB, a preferred knife 10 is shown modified according

to the present invention. The knife without modification has been widely available as

manufactured by Key Knife, Inc., of Tualatin, Oregon, and is described in detail in

Schmatjen, U.S. Patent No. 5,819,826, herein incorporated by reference in its entirety.

The knife 10 may be employed in any wood chipping apparatus, such as a disc, drum or

conical head wood chipper. The knife has an elongate- axis "L", a front side 12 and a

back side 14. The front side 14 of the knife 12 includes spaced deflector ridges 18a and 18b that project therefrom. The deflector ridges define a channel 34 having a channel surface 34a.

The channel 34 is effectively a recess in the front side of the knife, which may be

provided in other configurations, such as a keyway. The deflector ridges also define two

lower knife-edge-joining portions 38a and 38b that terminate in respective cutting edges 16a and 16b.

The back side 14 of the knife 10 includes a clamp-facing surface portion 14a that is substantially planar and parallel to the channel surface 34a, and two upper knife-edge- joining portions 35a and 35b that slope from opposite edges of the clamp-facing surface portion to the cutting edges 16a and 16b. The knife 10 is typically provided so that the lower knife-edge-joining portion 38a lies in the same plane as the lower knife-edge-

joining portion 38b (and the channel surface 34a); however, these faces can be ground or

otherwise provided according to the aforementioned companion application entitled

METHOD AND APPARATUS FOR CLAMPING A KNIFE so that the lower knife-

edge-joining portions are not coplanar.

As mentioned previously, the above features are described in the '826 Patent.

While the invention is believed to provide maximum advantage when used in connection with the preferred knife, the invention will provide an advantage when used with other

prior art knives as well, such as knives that do not have all of the aforementioned

features, or knives which include additional features. Referring to Figure 2 A, a disc chipper 20 is shown employing a plurality of the knives 10. While a disc chipper is used herein to illustrate use of particular embodiments

of the invention, the principles of the invention apply equally to other chipping apparatus

including that employing a drum or a "conical" head, and application of those principles to alternative configurations of chipping apparatus will be readily apparent to those of

ordinary skill in the art.

The knives are elongate, meaning herein that they have a shape in a cross- sectional plane that is maintained for some distance along an axis "A" that is

perpendicular to the plane. For use in a disc chipper, the length of the knives along the axis "A" is typically large in comparison to the cross-sectional dimensions of the knives;

however, the length of the knives may be small in comparison to these dimensions, such as where many discs are combined to form a drum in a drum chipping apparatus. In the

disc chipper, the elongate axes "A" extend radially, approximately from the center of the

disc. The disc spins in a vertical plane in the direction of the arrow, with an exposed

cutting edge 16a of each knife being visible.

Figure 2B shows a cross-section of the disc chipper 20 taken through a particular

knife 10a that is in the 3:00 position of the disc as it is shown in Figure 2A. The knife is shown clamped in the disc chipper between outer and inner clamping members 22a and

24a respectively, so that the disc is ready for use for cutting wood. The inner clamping

member is often referred to as a "counterknife." An insert 21 is received in a corresponding pocket in the disc chipper. The insert supports the outer and inner clamping members as well as means for adjusting the spacing between the clamping members for clamping and unclamping the knife. For clamping the knife as shown, at least a portion of the channel surface 34a (Figure 1 A) is

abuttably received by the inner clamping member 24a, and the clamp-facing surface

portion 14a of the back side 14 of the knife (Figure IB) is at least disposed proximate to

(Figure 4B) and may be abuttably received by an inner surface 23 (Figure 3 A) of the outer

clamping member 22a.

Preferably, the outer clamping member 22a is fixedly disposed with respect to the

insert 21 , and a threaded adjustment member 26a is received in a corresponding threaded

aperture through the outer clamping member which permits translating the adjustment

member in the directions indicated by the arrows, for adjustably pivoting the inner

clamping member 24a about a bearing surface 33 that is provided as part of the insert 21.

Alternatively, the position of the inner clamping member may be fixed and the outer

clamping member may be adapted to be adjustably spaced apart therefrom, and either or

both clamping members may be adjustably movable by any desired means without

departing from the principles of the invention.

Turning to Figure 3 A, a cross-section similar to that of Figure 2B shows another

knife 10b (see also Figure 2A) which is in the 9:00 position of the disc. By contrast to the knife 10a in Figure 2B, the knife 10b is undamped in the disc chipper. The inner

clamping member 24b for the knife 10b has been pivoted about the surface 33 to provide a spacing from the outer clamping member 22b that is sufficient for removing the knife

from, or installing the same knife or a different knife, between the clamping members.

When the clamping members 22b and 24b are separated, the knife 10b in the 9:00 position rests on the inner clamping member 24b under the influence of gravity.

More particularly, one of the deflector ridges 18a is disposed outside a toe 19 of the inner clamping member 24b at one end of the toe, the other end of the toe being defined by a recess 28 shaped to receive the other of the other deflector ridge 18b. The

channel 34 as bounded by the deflector ridges defines a recess that, along with the relatively projecting toe of the inner clamping member, provide interlocking means which

cooperate to hold the knife 10b to the inner clamping member 24b against the influence

of gravity when the knife is undamped in the 9:00 position of the disc. Alternatively, a

keyway may be provided in the knife for receiving the toe. However, if the knife is

dislodged, it may fall outwardly from the disc chipper along a line of slippage "B," posing

a substantial risk of injury or damage.

Interlocking the knife to the inner clamping member also provides for locating and positioning the knife ("indexing") so that it is accurately disposed for cutting when

the clamping members are adjusted to clamp the knife therebetween.

Turning to Figure 3B, a cross-section similar to that shown in Figure 2B illustrates the knife 10a undamped in the disc chipper in the 3:00 position of the disc. The inner clamping member 24a has been pivoted about the surface 33 to provide a spacing from the outer clamping member 22a that is sufficient for removing the knife from, or installing the same knife or a different knife, between the clamping members. When the clamping members 22a and 24a are separated, such as by use of the adjustment

mechanism 26a, the knife 10a in the 3:00 position of the disc rests on the outer clamping member 24a under the influence of gravity as shown. It may be noted that the clamping members need not be maximally separated for this result to occur, the clamping members becoming separated at the point that the clamping force they exert on the knife is reduced to zero.

The knife 10a in the 3:00 position cannot be interlocked with the inner clamping

member 24, hence the safety and indexing features provided by the deflector ridges of the knife and the recess 28 of the inner clamping member are lost in this position. Thence,

the undamped knife in the 3:00 position of the disc will ordinarily slip backwardly into

the apparatus along the line of slippage "B," against interior portions of the outer and

inner clamping members. While the risk of injury to personnel is much reduced as

compared to that posed by slippage of the knife in the 9:00 position, such slippage may

cause damage to the knife or the apparatus, and may make removal of the knife somewhat

difficult. Moreover, installation of the knife is also difficult, and indexing the knife into

proper position while clamping the knife is very difficult.

With additional reference to Figure 1 A, to improve the safety and security of

holding the undamped knife in the 3:00 position of the disc as well as to provide for indexing of the knife, the knife and outer clamping members are provided with

interlocking features to prevent slippage of the knife into or out of the apparatus along the axis "B" (Figure 3B) when the knife is undamped, providing an outstanding advantage

over the prior art.

In a preferred embodiment of the invention, the otherwise substantially planar clamp-facing surface portion 14a of the back side 14 of the knife includes a recess 30 that is particularly a groove, and the outer clamping member 22 includes a complementary elongate projection 32 adapted to fit into the groove, where persons of ordinary skill will immediately recognize the equivalence of providing the knife with a projection and the outer clamping member 22 with a complementary and corresponding groove. According

to the invention, the interlocking features of the knife and outer clamping member may be

any interlockingly cooperating male or female structures that permit removing the knife

from the outer clamping member while preventing the aforementioned slippage.

Preferably, the interlocking features interlock or retain one another in the direction

or plane of slippage "B" while providing for free movement of the knife in one or both

perpendicular directions. As mentioned, the recess 30 and projection 32 are preferably

elongate, and at least a portion of each is preferably semi-circular as seen in a cross-

section perpendicular to the elongate axis "L" (Figure 1 A), to provide surfaces that are

semi-cylindrical. Most preferably and particularly as shown, the shape of the recess 30 and the shape of a distal tip 27 (best seen in Figure 4B) of the projection in cross-section

are half-circular, to provide surfaces that are half-cylindrical. These shapes are believed to be especially advantageous for easing installation of

the knife, by permitting the knife to pivot on the projection about the elongate axis of the knife which facilitates manipulating the knife into position, and by accommodating

greater manufacturing tolerances, which further reduces the effort required to place the knife into position as well as manufacturing costs.

Referring to Figures 4A and 4B, the preferred form of the interlocking features

provides that the projection 32 extends far enough from the inner surface 23 of the outer clamping member so that a "three-point" contact is provided for clamping the knife, wherein the projection 32 provides one of the points of contact. In Figure 4A, the inner clamping member 24 has been moved away from the outer clamping

member 22, and the knife 10 is held loosely by the projection 32. In Figure 4B, the

clamping member 24 has been pivoted to receive the front side 12 of the knife and

clamp the knife to the projection 32 of the clamping member 22, wherein the projection 32 has sides 32a and 32b that are substantially perpendicular to the inner surface 23 of the clamping member 22, terminating in a tip 27 having the semi¬

circular cross-section, and extending far enough from the surface 23 so that the knife

can rotate (compare Figures 4A and 4B) about its elongate axis at the tip 27, and so

that the back side of the knife is not otherwise in contact with the surface 23 when the knife is clamped (Figure 4B).

Permitting a minimal but significant ("substantial") degree of rotation of the

knife on the projection facilitates installation of the knife while not defeating the

purpose of the projection to interlock with the recess 30 to prevent slippage. The

semi-cylindrical surface of the projection may extend over an arc that is greater or less than a half-cylindrical 180 degrees, while the semi-cylindrical surface of the recess 30

should have an arc that is about 180 degrees or less, to prevent the recess 30 from pinching or capturing the projection, which would decrease the efficacy of the

connection between the parts and make both removal and installation of the knife difficult.

As mentioned, providing that most of the back side of the knife does not

contact the surface 23 when the knife is clamped provides for a "three-point" contact, i.e., a point of contact "Al" at the tip 27 falls between, with respect to a line "PI," two other points of contact "A2" and "A3," so that contact is not being made, and force is not being transmitted, between most of the back side of the knife 14 and the clamping

member 22. This provides a means for applying the clamping force that is consistent

in spite of manufacturing variations in the dimensions of the parts.

The semi-cylindrical shapes for the projection and recess 30 are also believed

to decrease manufacturing cost by rendering the capability to index the knife accurately to the outer clamping member less sensitive to manufacturing tolerances in

these features. While in the preferred embodiment these features extend over the entire length

of the knife (determined in the direction of the axis "L"), this is not essential, and it may provide some additional indexing capability to limit the lateral extent of the interlocking features, so that the knife is retained laterally (into and out of the plane of

Figure 3A) as well as with respect to slippage in the direction or plane "B." However,

the knife may be freely moved away from the inner clamping member 22a along the

perpendicular direction "C," for changing the knife.

Preferably, the interlocking feature of the knife is located so that the knife is or remains bilaterally symmetric with respect a plane "P" (Figure IB) that is parallel to the elongate axis of the knife, so that the knife may be turned end-to-end in a perpendicular plane, rather than rotated about the elongate axis, such as is required in

Valo, U.S. Patent No. 4,271,882 or Svensson, U.S. Patent No. 4,047,670, for example,

to obtain a fresh cutting edge from the knife. In view of the sharp edges of the knives

and their great weight, it is believed that the foπner operation is easier to perform than

the latter as it can be performed without touching the cutting edges, without holding both sides of the knife, and without requiring a rotation of the wrist.

It should be noted that to provide such symmetry does not require a single

interlocking feature that is centered on or in the back side 14 of the knife such as

shown in Figure IB. For example, bilateral symmetry with respect to the plane "P"

may be obtained by providing an interlocking feature of the knife consisting of two, or

any even number of recesses 30 that are symmetrically disposed with respect to the plane, either alone or in combination with a recess 30 that is centrally disposed in the

plane. This provides the option of applying clamping force to the back side of the knife off its center.

To permit the aforementioned pivoting of the knife about the projection, it is preferable that only one projection is provided that is adapted to be received in just one of the one or more recesses 30 that are provided. However, providing this

advantage is not essential, and additional projections may be provided without departing from the principles of the invention.

Other forms and shapes of the interlocking features may be provided also without departing from the principles of the invention. For example, the one or more

projections could be formed as pins and the one or more recesses as complementary apertures, holes or cavities providing for free movement along the axis "C" even though sliding the knife laterally is not permitted without first separating the pins from the holes by movement of the knife along the axis "C." A similar effect is obtained,

as mentioned above, by forming the preferred groove so that it does not extend the

entire length of the knife.

Provision of the recesses 30 (Figure 3A) and projections 32 makes it

particularly advantageous to access the knife for changing or other purposes at the

3:00 position of the disc. According to the invention, then, the opening in the shroud

is preferably situated at this position. Moreover, providing the interlocking features of

the knife and outer clamping member in combination with the interlocking features of

the knife and counterknife provides for safely holding the knife in the apparatus as

well as indexing the knife to the apparatus in either or both the 9:00 and 3:00

positions of the disc, resulting in outstanding flexibility.

It is to be recognized that, while a specific method and apparatus for clamping a knife has been shown and described as preferred, other configurations could be utilized, in addition to configurations already mentioned, without departing from the principles of the invention.

The terms and expressions which have been employed in the foregoing

specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions to exclude equivalents of the

features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.

Claims

Claims:

1. A knife for a wood chipping apparatus, comprising opposed front and back sides co-terminating in at least one cutting edge, the knife having an elongate

axis, wherein said back side includes at least one groove having a semi-circular cross- section in a plane perpendicular to said elongate axis.

2. The knife of claim 1, wherein said front and back sides co-terminate in

two cutting edges and the knife is bilaterally symmetric about a plane parallel to said

elongate axis.

3. The knife of claim 1, wherein said back side includes only one said groove.

4. The knife of claim 3, wherein said front and back sides co-terminate in

two cutting edges and the knife is bilaterally symmetric about a plane parallel to said elongate axis.

5. The knife of claim 1, wherein said front side includes at least one deflector ridge proj ecting therefrom.

6. The knife of claim 5, wherein said front and back sides co-terminate in two cutting edges, wherein said front side includes two deflector ridges, and the knife is bilaterally symmetric about a plane parallel to said elongate axis.

7. The knife of claim 1 , wherein said groove has a substantially half-

circular cross-section in said plane.

8. The knife of claim 7, wherein said front and back sides co-terminate in two cutting edges and the knife is bilaterally symmetric about a plane parallel to said

elongate axis.

9. The knife of claim 7, wherein said back side includes only one said

groove.

10. The knife of claim 9, wherein said front and back sides co-terminate in

elongate axis.

11. The knife of claim 7, wherein said front side includes at least one

deflector ridge projecting therefrom.

12. The knife of claim 11, wherein said front and back sides co-terminate in two cutting edges, wherein said front side includes two deflector ridges, and the

knife is bilaterally symmetric about a plane parallel to said elongate axis.

13. A knife for a wood chipping apparatus, comprising opposed front and

back sides co-terminating in two cutting edges defining a plane wherein said front side

is below said plane and said back side is above said plane, the knife having an

elongate axis, wherein said front side includes at least two points of maximum distance from said plane and a surface therebetween of lesser distance from said plane to define a recess between said two points, and wherein said back side includes at

least one of (a) at least two points of maximum distance from said plane and a surface therebetween of lesser distance from said plane to define a recess between said two

points of said back side, and (b) a surface of maximum distance from said plane and at least two points of lesser distance from said plane that bound said surface to define a

projection between said two points of said back side, wherein said knife is bilaterally

symmetric about a plane parallel to said elongate axis.

14. The knife of claim 13, wherein said back side includes (a).

15. The knife of claim 14, wherein said back side does not include (b).

16. The knife of claim 15, wherein said surface defined in (a) is semi-

cylindrical.

17. The knife of claim 16, wherein said surface defined in (a) is substantially half-cylindrical.

18. A clamp for a knife having a back side for use in a wood chipping apparatus, comprising a back surface including a projection extending therefrom that

includes a tip portion having a semi-circular cross-section in a plane perpendicular to

said axis.

19. The clamp of claim 18, wherein said projection includes at least two

parallel sides connecting to said tip portion.

20. The clamp of claim 18, wherein the knife has an elongate axis, and wherein said tip portion has a substantially half-circular cross-section in a plane

perpendicular to said axis.

21. The clamp of claim 20, wherein said projection includes at least two

parallel sides connecting to said tip portion, at least one of which is substantially

perpendicular to a surface of said clamp that is immediately adjacent said projection.

22. The clamp of claim 18, including a threaded aperture extending

through the clamp for receiving a threaded member providing for an adjustable amount of translation of the threaded member with respect to the clamp.

23. The clamp of claim 22, wherein said tip portion has a substantially half-circular cross-section in said plane.

24. A clamp for clamping a knife having a back side for use in a wood

chipping apparatus, comprising an inner surface for disposition proximate the back

side of the knife including a projection extending therefrom, the clamp having a

tlireaded aperture extending through the clamp for receiving a threaded member that

provides for an adjustable amount of translation of the threaded member with respect

to the clamp.

25. A clamp for clamping a knife having a back side for use in a wood chipping apparatus, comprising an inner surface for disposition proximate the back

side of the knife including a projection extending therefrom, said projection having at least two sides that are substantially perpendicular to said inner surface, each

connecting to a tip portion of said projection.

26. A wood chipping apparatus, comprising:

a knife having an elongate axis and a side terminating in a cutting edge; and a clamp for clamping the knife, the clamp having an inner surface for disposition proximate said side of said knife, wherein said side includes an interlocking feature adapted to interlockingly engage a complementary

interlocking feature of said surface of said clamp to prevent the knife from slipping with respect to said clamp along a first direction that is perpendicular to said

elongate axis while freely permitting separation of the

knife from said outer clamping member along a second

direction that is substantially perpendicular to said

elongate axis and to said first direction, said interlocking feature of said surface of said clamp extending sufficiently from said inner surface so that

most of the back side of said knife does not make

contact with said outer clamping member when the

knife is clamped thereby.

27. The apparatus of claim 26, wherein said interlocking features are

adapted to permit rotation of said knife about said elongate axis.

28. A wood chipping apparatus, comprising: a knife having an elongate axis, front and back sides co-

terminating in a cutting edge, the knife being bilaterally symmetric with respect to a plane parallel to said elongate axis; and

a clamp for clamping the knife, the clamp having an inner

surface for disposition proximate the back side of said

knife, wherein the back side of said knife includes an interlocking feature adapted to interlockingly engage a

complementary interlocking feature of said surface of

said clamp to prevent the knife from slipping with

respect to said clamp along a first direction that is perpendicular to said elongate axis while freely

permitting separation of the knife from said outer

clamping member along a second direction that is

substantially perpendicular to said elongate axis and to

said first direction.

29. The apparatus of claim 28, wherein said interlocking features are adapted to permit rotation of said knife about said elongate axis.

30. A wood chipping apparatus, comprising: a knife having an elongate axis and front and back sides co- terminating in a cutting edge;

an outer clamping member for clamping the knife, the outer clamping member having an inner surface for

5 disposition proximate the back side of said knife, wherein the back side of said knife includes an interlocking feature adapted to interlockingly engage a complementary interlocking feature of said surface of

said outer clamping member to prevent the knife from

10 slipping with respect to said clamp along a first

direction that is perpendicular to said elongate axis

while freely permitting separation of the knife from said outer clamping member; and

an inner clamping member for clamping the knife against said

15 outer clamping member, the inner clamping member

having an outer surface for disposition proximate the front side of said knife, wherein the front side of said knife includes an interlocking feature adapted to

interlockingly engage a complementary interlocking 20 feature of said surface of said inner clamping member to prevent the knife from slipping with respect to said inner clamping member along a first direction that is perpendicular to said elongate axes while freely

permitting separation of the knife from said inner clamping member.

31. The apparatus of claim 30, wherein said interlocking features of said back side of said knife and said inner surface of said outer clamping member are adapted to permit rotation of said knife about said elongate axis.