Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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JJ5aaLg~ h~nION
The invention relates to apparatus for sharpening
blades and particularly for sharpening blades while they are
mounted in drums.
S BACKGROUND AND PRIOR ART
There are numerous circumstances in which blades are
mounted on drums and in which it is desired to sharpen the blades
after protracted operation therewith.
As one suitable example, mention can be made of a wood
chipping machine in which branches and trunks of trees are
reduced to chips by means of cutting blades on a rotating drum.
Such chipping machines are relatively large and are powered,
for example, by engines of 100 to 200 horsepower. Such machines
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are conventionally trailer mounted and a plurality of cutting
blades, usually four, are mounted in slots in a steel drum
approximately twelve inches in diameter and from nine to
sixteen inches in width. The drum rotates at a high speed of
from 2000 to ~000 R.P.M.
In order to maintain the efficiency of the chipping
operation, the blades must be sharpened frequently. Conventionally,
this is undertaken by removal of the blades from the drum and
sharpening them while they are removed. Thereafter, the blades
must be reset into the drum. The total operation requires at
least two hours and it takes substantial skill to grind the
cutting surface of the blade.
- Attempts at hand grinding the blade have proved to be
unsatisfactory in practice, since it is virtually impossible
to maintain the necessary angle of the cutting surface on the blade.
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SUMMARY OF THE INVENTION
An object of the invention is to provide a sharpening
device which will allow sharpening of the cutting surface of the
blade while it remains mounted in the drum.
A further object of the invention is to provide such
sharpening apparatus which will be portable and readily securable
on the drum for effecting the sharpening of the blade cutting
surface.
A further object o the invention is to provide such
apparatus in which the sharpening of the cutting surface of the
blade is effected by manually displacing a support of a sharp-
ening member such that the sharpening member will travel along
the cutting surface of the blade.
; A critical feature of the invention is that the sharpening
surface of the sharpening member is constrained to maintain a
;~ preset angle corresponding to the angle of the cutting surface
with respect to the blade.
In accordance with the above and further objects and
features of the invention, there is provided blade sharpening
apparatus comprising mounting means for attachment to a support
carrying a blade whose cutting surface is to be sharpened, a
rotatable sharpening member having a flat sharpening surface
adapted for ~arpening the cutting surface of the blade, and
connèction means coupled to the mounting means and supporting
the sharpening member for displacement in a plane perpendicular
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~` to the plane of the flat sharpening surface and disposed such
that the sharpening surface can be brought into contact with
the cutting surface of the blade and be advanced thereby.
In further accordance with the invention, the connection
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means is constructed as a linkage assembly for moving the sharp-
ening member in said plane about ai~pivot axis perpendicular to
said plane.
The linkage assembly is composed of a plurality of link
members all of which are pivotably interconnected about axes
which extend perpendicular to said plane of movement of the
sharpening member.
The invention further contemplates the proviiion of
drive means coupled to the sharpening member for driving the
same in rotation about an axis perpendicular to said pivot
axis.
The drive means includes a flexible drive element to
permit the sharpening member to traverse the cutting surface of
the blade, while the sharpening member is driven in rotation.
In further accordance with the invention, the apparatus
; additionally comprises means for adjusting the linkage means on
- the mou~ting means in order to angularly adjust the position of
the sharpening surface of the sharpening member while the
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mounting means remains attached to the blade support. Thereby,
the angle of sharpening of the cutting surface of the blade can-..'1
be adjusted while the apparatus is clamped ~o the blade support.
Further features of the invention and additional
advantages provided thereby, will become apparent to those
~`~ skilled in the art from the following detailed description of
an embodiment of the invention. This description will be taken
in conjunction with the annexed drawings.
~i __ ___ T~E DRAWING
Figure 1 is a side elevational view OL the sharpening
apparatus according to the invention shown in operative position
to sharpen a blade,
Figure 2 is a top plan view thereof, showing the cutting
blade in one cutting position in solid lines and in a second
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cutting position in chain dotted lines, and
Figure 3 shows a modified arrangement of a portion of
the apparatus of Fig. 1.
DETAIL ~ DESCRI~TION
Referring to the drawing, therein is seen a rotatable drum
1 which supports a plurality of cutting members or blades 2.
By way of example, the drum and blades can be part of a chipping
machine which is intended to form chips from tree parts. In
general, four blades are mounted in diametric opposition on the
drum and two of such blades are illustrated in the drawing to
facilitate an understanding of the manner in which the apparatus
of the invention is intended to be employed.
The blades 2 are mounted in corresponding slots in the
drum 1 and are secured in position therein by means of wedges 3
which in turn are secured in the drum by lock bolts 4. An
adjustment means is conventionally provided to regulate the
degree of projection of the blades from the surface of the drum
` but such means is not sho-~n herein as this is not essential to
the invention and is not required for an understanding thereof.
In the course~of operation of the chipping machine, the
cutting surfaces 5 of the blades become dull and it is necessary
to sharpen the blades in order that they satisfactori~y carry out
the chipping operation. For this purpose, the invention contem-
plates the provision of a portable sharpening apparatus
generally indicated at 10 which is capable of being secured to
the drum 1 in a fixed position for ~arpening the cutting surface
5 of the blades.
The cutting surface 5 of the blade generally lies in a
plane at an angle of 45 with respect to the longitudinal axis of
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the blade. It is essential that the apparatus of the invention
when mounted on the drum exactly follow this cutting surface to
effect sharpening thereof. An essential requirement and
characterizing feature of the sharpening apparatus is that once
S it has been mounted on the drum and secured in place the edge 11
of the sharpening surface of a grinding or sharpening member 12
of the apparatus will maintain a fixed grinding angle with respect
to the cutting surface ~ of the blade as will be explained in
greater detail later.
The sharpening apparatus of the invention essentially
comprises a mounting meaas 13 for attachment to the drum 1, a
linkage means 14~supported on the mounting means and in turn
carrying the grinding or sharpening member 12, so that the
sharpening surface thereof can be brought into operative contact
with the cutting surface 5 of the blade.
The mounting means 13 comprises a rod 15 and a base plate
16 which enables the sharpening apparatus to be mounted on the
drum.
The rod lS has a hook 17 at one end which is adapted to
engage the blade adjacent to the one whose cutting surface is
to be sharpened. As shown in Fig. 1, this blade is designated
by S'. At the end of rod 15 opposite hook 17, a threaded portion
18 is threadably engaged in a cylinder 19 and extends beyond the
cylinder to threadably receive a locking knob 20. In operation,
after the hook has been engaged on the blade 5' and the mounting
means secured on the drum in a manner to be explained later, the
knob 20 is advanced on threaded portion 18 of rod 15 so as to
bear against cylinder 19 and lock the mounting means on the drum.
The base plate 16 is fixedly secured to the ends of
cylinder 19 and has an upper edge 22 of pointed shape which is
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adapted to bear against the wedge 3 which holds the blade 2 in
the drum. The base plate 16 carries two adjusting screws 23
(only one being visible in Fig. 1), extending from the rear
face 21 of the base plate, and the screws 23 are intended to bear
against the drum 1. The drum is provided with reference marks
for engagement of the pointed edge 22 and the adjusting screws 23.
By adjusting screws 23, exact correspondence can be made between
the contact points of the screws and the pointed edge 22 with
the ~cference marks on the drum.
It is to be noted that the dn~m 1 is provided with a
recess 24 at which the wedge and blade is mounted within the
,;~ drum. It is in this recess that the adjusting screws 23 engage
the drum in order for the entire assembly to be tightly clamped
on the drum 1.
,' 15 The linkage means 14 is secured to the base plate 16
by means of a clevice 30 which receives a sealed bearing 31 and
'' a pivot shaft 32. A first link member 33 is pivotably mounted on
pivot shaft 32 and is secured to a clevice 34 at the end remote
~' from shaft 32. Clevice 34 supports a pivot shaft 35 in sealed
,~' 20 bearings 3~ and a second link member 37 is pivotably mounted on'~ shaft 35. A lock nut 38 serves to hold the pivot shaft 35~ in
,;', place, and a handle 39 extends downwardly from link member 33
;~, and is secured thereto.
' The link member 37 carries a pivot shaft 40 at the end
remote from pivot shaft 35 and a hand piece 41 is mounted on the
pivot shaft 40 for pivotal movement. The hand piece 41
rotatably carries a drive shaft 42 at the end of which is
affixed the sharpening me,mber 12. The sharpening member is in
the form of a cup wheel with an annular sharpening surface 43.
A flexible shaft 44 is connected to the drive shaft 42 and in turn
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is driven by a motor (not shown) so that the cup wheel can be
drivenin rotation about the axis of shaft 42.
In order for the plane passing through the sharpening sur-
face 43 of the cup wheel 12 always to make contact with the blade
S 2 in the planar relation ~th the cutting edge 5 thereof, it is
essential that the linkage constrain the wheel to move in a plane
perpendicular to the cutting edge 5 of the blade. In order to
achieve this, it is necessary that the axes passing through pivot
shafts 32,35 and 40 are all parallel to one another and parallel
to the cutting edge 5 of the blade. In this way, the rotational
axis of the cup wheel designated by XX in Fig. 1 will be constrained
to travel in a plane perpendicular to the cutting edge S of blade 2.
In operation, it is only necessary for a workman to hold
hand piece 41 and move the cup wheel along the cutting edge 5 of
; 15 blade 2 in order to effect sharpening of the blade edge. It is not
~i necessary for the ~o~kman to exercise any degree of skillful hand
operation as the cup wheel will automatically be positioned~/grind
the surface of the cutting edge of blade 2. Usually, the drwm is
locked in rotation during the grinding of the cutting surface of
the blade~ however, even if the drum should slip or rotate slightly,
- the cup wheel still remains in its fixed geometrical relation
with the blade.
As can be seen from Fig. 2, the cup wheel can be displaced
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along the blades in a fixed angular orientation to effect sharp-
ening of the cutting surface. The particular angular relation
`~ which the cup wheel makes iniplan view relative to the curring sur-
face of the blade will determine the degree of hollow grinding of
the cutting surface 5. Namely, as shown in Fig. 2, the left edge
of the cup wheel contacts the grinding surface and will form
a hollow grind in said surface. By increasing the angle between
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link members 33 and 37, it becomes possible to increase the
degree of hollow grinding. Alternatively, by diminishing the
angle between the two link members, the degree of hollow grinding
can be reduced and even eliminated. In the latter case, the
axis will be perpendicular to the edge of blade 2. In general~
the cup wheel will be held in a fixed angular position with
respect to the edge of the blade as it traverses the length
of the blade as seen in Fig. 2.
; Referring to Fig. 3~ herein is shown a modification which
enables adjustment of the grinding angle while the mounting
means is fixed to the drum. All elements of the construction
which are similar to Fig. 1 are given the same numerals and will
-1 not be described further.
3 Refèrring to Fig. 3, it is seen that a second base plate
50 Ls pivotably connected by pivot 51 to the base plate 16 and
the clevice 30 is fixed to the second plate 50. An adjusting screw
52 is rotatably mounted in base plate 16 and restrained against
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axial movement and the second base plate 50 is threaded on
l ~ adjusting screw 52 such that by rotating the adjusting screw,
; 20 the base plate 50 can be made to pivot about pin 51 with
respect to base plate 16. Thereby, the angular position of the
pivot shafts 32,35 and 40 can be adjusted relative to base plate
16 in order to bring the plane of the sharpening surface 43 of the
cup wheel into exact correspondence with the angle of the
operative cutting surface of blade 2.
Although the invention has been described in relation to
a specific embodiment thereof, numerous modifications and
variations will become apparent to those skilled in the art
without departing from the scope and spirit of the invention.
Thus, instead of a linkage assembly as shown, it may be also
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possible to employ a slide which is mounted on the base plate 16
~: and which constrains the cup wheel to move in a p ~ ~ parallel
to the cutting surface S of the blade 2. It is to be noted,
: however, that the linkage arrangement is preferred over the
sliding device~ since the bearings can be easily sealed against
grinding debris.
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