Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED CANTER CHIPPER HEAD AND KNIFE MOUNTING
FIELD OF INVENTION
This invention relates generally to canter chipper
heads and more particularly to precision and secure mounting
of the cutters and to refinements to the shape of the head.
BACKGROUND OF INVENTION
Chipper canters are know as are also canter heads with
cutting knives removably mounted thereon and by way of
example reference may be hand to applicants United States
Patent 5,915,429 ISSUED Jun.29,1999 and entitled "COMPACT
SMALL DIAMETER LOG SAWMILL".
Disclosed in applicants above patent (figures 12-23) is
a chipper canter head having chip discharge openings through
a truncated conical portion of the head and a pair of
cutting knives mounted adjacent each opening. The cutting
edge of one knife extends along an edge of the opening in
the conical portion of the head and the other knife cutting
edge extends along an edge of the opening in an outer
relatively flat end face of the head. The blades are
removably mounted by studs passing through the respective
blades and threaded into the head or by bolt and nut units.
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Blades must be kept sharp and to do this they must be
removed from the head. This can occur as often as each daily
shift of operation and thus it is necessary the mounting
means be readily accessible. In some prior art arrangements
the mount securement is a bolt and nut with the nut
accessible only from the rear face of the head. In such
cases it is often necessary to remove the head from the
canter drive shaft before attempting to remove the cutting
blade.
The quality of the chips and the cant face is
determined by not only by the sharpness of the cutting
knives but also the precision of the head, the precision in
positioning of the knives on the head and the rigidity of
the head and blades thereon.
In an attempt to obtain some degree of precision in
locating the cutting knives some are adjustably positionable
and in this regard reference may be had to the following
United States Patents:
5,709,255 issued Jan.20,1998 to W. Toogood
5,511,597 issued Apr.30,1996 to M. Shantie et al
5,439,039 issued Aug.8,1995 to J. Bradstreet Jr et al
5,2271,442 issued Dec.21,1993 to C. Carpenter
These references also disclose a knife unit in which a
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double edge replaceable blade is clamped between a backing
plate and a cover plate. This permits having only the blade
made of high quality material such as tool steel or the
like. The knife unit is removably mounted on a holder that
bolts onto a hub.
While the knife unit is an improvement positioning can
change from impact forces on the blades during use because
of the many assembled components.
SUMMARY OF INVENTION
An object of the present invention is to provide a
rugged precision mounting of cutting blades on a chipper
canter head.
A further principal object of the present invention is
to provide a knife mounting means that is readily accessible
from the front face of the canter head.
A still further object of the present invention is to
provide refinements to the shape of the one piece canter
head.
In keeping with the forgoing there is provided in
accordance with the present invention a chipper canter head
comprising a base member machine shaped from a monolithic
block of metal and having a truncated conical outer front
face terminating in an outer end face, a rear face, at least
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two spaced apart chip discharge passages through said
truncated conical portion and each having a continuous
outline in each of said front and rear faces, each said
passage extending into said outer end face, a pair of cutter
units for each respective passage, each said cutter unit
comprising a bottom plate, a top plate and a knife blade,
said knife blade being clampingly engagable between said
plates and having a longitudinally extending cutting edge
projecting therefrom and means detachably mounting said
cutter units on said canter head with the knife cutting
edges disposed adjacent and along an edge of the opening to
the discharge passage associated therewith, said mounting
means comprising a first bolt means passing through said
bottom plate detachably anchoring the same to said base
member and a second bolt means passing through said top
plate and said bottom plate anchoring the top plate to the
base member and clampingly engaging the knife blade between
said plates.
LIST OF DRAWINGS
The invention is illustrated by way of example in the
accompanying drawing wherein:
figures 1 and 2 are front face views of a pair of
base members of chipper canter heads, without the cutting
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knife units mounted thereon, and that are driven to rotate
respectively clockwise and counter clockwise during use;
Figure 3 is a rear view of figure 2;
Figure 4 is a side view of figure 1,
5 Figure 5 is a sectional view of the encircled
portion marked 5 in figure 1 but on a larger scale and
taken essentially along line 5-5 but with the principal
cutting knife unit mounted on the canter head base member;
Figure 6 is a sectional view of the encircled
portion marked 6 figure 1 but on a larger scale and taken
essentially along line 6-6 but with the secondary knife unit
mounted on the canter head base member;
Figure 7 is a plan view the bottom plate of the
knife unit shown in cross-section in figure 5;
Figure 8 is a plan view of the top plate of the
knife unit shown in figure 5;
Figure 9 is a plan view of the bottom plate of the
knife unit shown in figure 6;
Figure 10 is a plan view of the top plate of the
knife unit shown in figure 6;
Figure 11 is a front view of the canter chipper
head base member with only two chip discharge passages and
also illustrating a preferred recess for the principal knife
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unit; and
Figure 12 is a side view of figure 11.
PREFERRED E1~ODIMENT
In the process of squaring logs chipper canter units
operate in pairs chipping cants on opposite sides of the log
as the log is propelled endwise along a predetermined path.
One of the canter chipper heads rotates clockwise while the
other in that pair rotates counter-clockwise. Shown in
figure 1 is the base member l0A of a canter chipper head
for clock-wise rotation and in figure 2 a base member 10B
for counter-clockwise rotation with each having four chip
cutting areas. The two base members are the same except for
one being a mirror image of the other. In figure 11 is
illustrated the base member lOC for clockwise rotation and
having only two chip discharge passages and applicants
preferred recess for the principal cutter.
The complete canter chipper head comprises a base
member 10 with chip discharge passages 11 therethrough
arranged in pairs(one diametrically opposite the other and
equi-spaced for balance) and respective knife units 20 and
mounted on the base member adjacent the inlet to each
respective chip discharge passage 11.
The base member is a monolithic block of metal
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precision machined to shape to include a front frusto-
conical outer face 12 that terminates at an end face 13, a
rear face 14 with a recess therein, one or more pairs of
said chip discharge passages 11 and a pair of knife unit
recesses 15 and 16 adjacent an edge at the inlet to each
respective chip discharge passage. The recesses 15 are in
the conical outer face 12 and the recesses 16 are in the end
face 13. In the drawings figure 11 shows the preferred
recess 15 and which will be described in detail hereinafter.
The inlet to each chip discharge passage, with
reference to the direction of rotation, has a leading edge
11A along the conical surface with an inclined surface 11B
that extends therefrom to an edge 11C in the rear face of
the head. Opposite the leading edge 11A is a trailing edge
11D along which a cutting knife extends and there are
respective inner and outer ends 11E, 11F with the outer end
terminating in the outer rim. The surface 11B is inclined at
a relatively small angle relative to the plane of the outer
end face 13 so as to not imped the flow of chips or damage
the same. The inner end 11E of the opening is in the end
face 13 of the head providing an edge portion 11EF along
which a second cutting knife extends.
The recess 15 for the knife unit 20 is located in the
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conical surface of the head and has a bottom face 15A, a
rear edge face 15B and an inner edge face 15C. In the
preferred embodiment illustrated in figure 11 there is an
outer end edge face 15D at the outer rim of the head.
The recess 16 for the knife unit 30 is located in the
end face of the head and has a bottom face 16A, an end face
16B and opposed edge faces 16C and 16D.
The cutter units 20 and 30 have respective bottom
plates 21,31, top plates 22,32 and knife blades 23,33. Each
knife blade has a pair of longitudinally extending cutting
edges E, a top face TF and a back face BF with a centrally
located groove G therein. The bottom plates 21,31 have
respective upper surfaces 21A,31A with respective lips 21B,
31B that mate with the groove G in the knife blade
associated therewith.
The bottom and top plates 21 and 22 of the knife unit
are shown in detail in figures 5,7 and 8. The bottom
plate 21 has a front edge 21C along which the lip 21B
extends, a back edge 21D and respective opposite side edges
20 21E and 21F tapering inwardly toward the back edge 21D.
There are two spaced apart mounting holes 21G through the
plate.
The top plate 22,in outline shape, is the same as the
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bottom plate 21 and has a bottom face 22A, a front edge 22C,
a back edge 22D and respective opposite side edges 22E and
22F. There are two mounting holes 22G through the plate and
concentric with each are larger respective top and bottom
counter-sinks 22J and 22K.
The bottom and top plates 31,32 of the knife unit 30
are shown in figures 6,9 and 10. The bottom plate 31 has a
front edge 31C along which the lip 31B extends, a back edge
31D and respective parallel side edges 31E and 31F.
The top plate 32, in outline shape, is the same as the
bottom plate 31 and has a bottom face 32A, a front edge
32C,a back edge 32D and respective parallel side edges 32E
and 32F. There is one mounting hole 32G through the plate
and concentric therewith is a bottom counter-sink 32K
The top and bottom plates and the respective recesses
are of the same outline shape machined to a close fit
tolerance so that the side and back edges of the plates abut
the corresponding edges of the recess associated therewith.
This provides fixed accurate positioning of the cutting
edges of the knives.
The bottom plates 21,31 of the respective units 20 and
are detachably anchored to the base member by sleeve type
studs 50. There are two studs 50 threaded into respective
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ones of a pair of threaded holes 15T in the base member
anchoring the bottom plate 21 and one anchoring the bottom
plate 31. With longer cutters as in figure 11 there are
three threaded holes 15T anchoring studs. For anchoring the
5 cutter units 30 there is a threaded hole 16T in the base
member In each of the recesses 16.
Each stud 50 has a head 51 and a stem 52 that is
externally and internally threaded as indicated respectively
at 53 and 54. On the stem 52, between the head 51 and the
10 external threads 53, there is a smooth surface portion 55
machined to a close tolerance fit with the hole associated
therewith through the plate.
The top plates 22,32 are detachably anchored to the
base member by studs 60 that thread into the internal
threads in the stem of the sleeve studs 50. Each stud 60 has
a smooth neck portion 61 adjacent the head 62 thereof
machined for a close fit in the top plate through hole.
The head base member 10 has a central recess 17 in the
rear face 13 for receiving a centering plug on a drive shaft
of the canter. The flange on the drive shaft has threaded
holes for receiving studs that pass through a respective one
of 8 mounting holes 18. There's a center hole 19 that a
centering stud passes through and threads into a threaded
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hole in the power driven shaft.
The end face 13 has a centrally located rectangular
recess 13A that receives and end plate 13B secured to the
base member 10 by four studs that pass through a respective
one of four holes 13C and threaded into holes 13D .
The outer face of plate 13B tapers toward the center
of rotation sloping at about 0.5 degrees with the center
protruding beyond the lateral edges.
The truncated conical surface tapers inwardly
slightly, counter to the direction of rotation, from the
leading edge 15S of a recess 15 to the leading edge 11A of
the next chip passageway 11. With reference to figure 11 the
radius to point CA is greater than the radius to point CB
the difference being the distance from point CB to point CC.
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