Note: Descriptions are shown in the official language in which they were submitted.
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Blade assembly especially for an ice auger or like
The invention relates to a blade assembly, especially for
an ice auger or the like, comprising a shank and a bit head.
The shank is provided at least with elements for mounting
the bit head. The bit head, in turn, includes one or more
disk-shaped bit members, which rotate during a
drilling/boring operation and which have an outer rim
thereof working as an actual cutting face in
drilling/boring.
Traditionally, the ice auger consists of three components,
i.e. an actual auger element, a crank at its top end, and
a blade assembly at its bottom end, respectively. Such
traditional ice augers comprise generally a helical
structure and the blade assembly used therein comprises bit
members, which are mounted either fixedly or removably to
the auger element, yet absolutely immobilized when in use.
The bit members used in this context are generally metal
pieces of a parallelogram shape, having one of the long
sides thereof beveled to serve as a blade or bit . The blade
assembly of an ice auger is generally provided with two of
such bit members, which are inclined relative to the
auger' s centre axis . As a result of the inclination angle,
the auger is focused at a single point on ice as boring is
started. The incidence angle, on the other hand, is
important in terms of what is called engaging capacity or
"biting ability" of the auger.
The engaging capacity of a traditional fixed auger head
including two bit members depends essentially on the
acuteness of bit angles . The inner edge, in particular, is
exposed to high stress and is highly susceptible to wearing
and chipping in use. When this happens, the boring becomes
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unreasonably strenuous and, thus, the bits must be
sharpened. Accordingly, in the event that an auger has been
left lying on the ice, there is always a risk of a person's
foot hitting the exposed blade as the outer edges of a
traditional auger bit are particularly hazardous. In
practice, another hazardous operation is the placement of
a blade cover. In addition, the blade or bit head of a
traditional ice auger requires constant adjustment as the
composition of ice varies e.g. along with air temperature;
an excessively engaging edge, effective in terms of cutting
dry and hard ice, becomes stuck in sloshy soft ice. The only
way of adjusting such a traditional fixedly secured bit is
by grinding its beveled edge.
On the other hand, it is prior known from patents US
1, 719, 546 and US 2, 713, 993 to beneficially provide a blade
assembly with a disk-shaped bit member rotating during a
drilling operation and having its outer rim working as an
actual cutting face. The above-cited solutions are
intended specifically for ground boring or e.g. rock
drilling. In the cited solutions, the bit members or disks
are disposed in an almost vertical position against a
drilled surface, which is why, on the basis of experience,
such solutions are by no means applicable to ice
drilling/boring.
It is an obj ect of a blade assembly according to the present
invention to provide a decisive improvement regarding the
foregoing problems and thereby to raise substantially the
existing state of the art. In order to fulfil this objective,
a blade assembly of the invention is principally
characterized in that the rotating bit member included in
the bit head is disposed at an angle of less than 45°
relative to a drilled surface.
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As the most important benefits gained by a blade assembly
of the invention should be mentioned simplicity,
efficiency and safety with regard to its construction,
manufacture and operation. The inventive blade assembly,
which comprises a bit member circular in shape and rotating
in a drilling process, as well as disposed at a suitably
low angle relative to a drilled surface, makes a smooth
contact with the ice to be bored, as just a small portion
thereof is parallel to the radius of a bored hole. By virtue
of this, boring is quite effortless and the bit does not
get jammed in ice. On the other hand, the bit member
included in a blade assembly of the invention rotates
steadily in use, nor does it develop chipped edges or the
like defects. Even if the bevel of a bit member should
become damaged at some point, the biting performance shall
not be significantly impaired in practice since the bit
rotates continuously in a drilling operation and turns the
dull point quickly away from the cutting position. All in
a11, the inventive blade assembly is highly adaptable to
mass production, including even automated production.
Another major benefit gained by the inventive blade
assembly lies in the fact that the incidence angle of a bit
member can be adjusted e.g. by tightening or loosening
attachment of the bit or by having it mounted on the blade
assembly's shank preferably in a flexible manner.
Preferred embodiments for a blade assembly of the invention
are set forth in the relevant dependent claims.
The invention will be described in detail in the following
specificationwith reference to the accompanying drawings,
in which
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fig. 1
shows a traditional auger bit member (t),
provided with a beveled edge (v) and an attachment
hole (R) ,
fig. 2
shows a pair of traditional bit members for an ice
auger in operative position seen from above,
fig. 3
shows both a section at 1-1 in fig. 2, depicting
an inclination angle formed by each bit member,
and a section at 2-2 in fig. 2, depicting a
cutting/incidenCe angle formed by each bit
member,
fig. 4
shows a bit member included in a blade assembly
of the invention, in a plan view and in a side
view,
fig. 5
shows a pair of bit members included in a blade
assembly of the invention, in a plan view, as well
as in side views depicting an inclination angle
and a Cutting/incidence angle,
fig. 6
shows a blade assembly of the invention, having
bit members coupled by a cotter pin, a fastening
screw and nut to a shank of the blade assembly,
fig. 7
shows a side view of a blade assembly alternative
to fig. 6, having each bit member coupled by a
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separate connecting member to substantially
horizontally extending arm elements of the shank,
fig. 8
5 shows an integrally built body element included
in the shank of a blade assembly of the invention,
in a plan view, a front view, and a side view,
fig. 9
shows a bit member alternative to fig. 4, in views
depicting especially one preferred way of
manufacturing the same, and
fig. 10
shows an embodiment alternative to the blade
assembly of figs. 6 and 7, comprising a single
rotary bit member.
The invention relates a blade assembly, especially for an
ice auger or the like, comprising a shank 1 and a bit head
2. The shank 1 is provided at least with elements 3 for
mounting the bit head 2. The bit head 2, in turn, includes
one or more disk-shaped bit members 2a, which rotate w
during a drilling/boring operation and which have an outer
rim 2a' thereof working as an actual cutting face in
drilling/boring. The rotary bit member 2a included in the
bit head is disposed, as depicted e.g. in fig. 5, at an angle
of less than 45° relative to a drilled surface A.
The blade assembly's shank 1 comprises preferably a
structure, which projects in two or more directions and
which has the bit members 2a included in the bit head 2
mounted on its arm elements in a dismountable fashion, such
as by using a screw connection or the like. Arm elements
1a, projecting laterally from the shank 1 in a
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substantially horizontal plane, are shaped, as depicted
a . g . in figs . 6 , 7 and 8 , such that the angle a of each bit
member 2a, such as its inclination angle a1,
incidence/cutting angle a2 and/or the like, lies within the
range of 5-30° relative to the drilled surface A.
Fig. 10 illustrates a solution alternative with respect to
what is described above, comprising just one rotary bit
member 2a which is mounted on the arm element 1a projecting
from the shank 1. In this solution, the alignment of a blade
assembly and the drilling of a pilot hole are performed by
means of a central drill CD present at an end of the shank
element 1. Also in this solut~.on, the rotary bit member 2a
is provided with angular settings as described above, yet
having its inclination in the opposite direction so as to
perform its drilling action by the outer edge of the rotary
bit member 2a as opposed to performing it with the inner
edge of the rotary bit member 2a, as in the solutions of
figs. 6 and 7.
In the solution shown in fig. 10, a pilot hole is drilled
by the twist bit CD used as a central drill and the outer
rim for a hole to be bored/drilled is in turn drilled by
the rotary bit member 2a. A solution like this enables a
very neat drilling result. In addition, it is highly
suitable for a motor-driven auger as it can be used for
making holes side by side quite close to each other, the
central drill CD being effective in blocking lateral
slipping.
In a further preferred embodiment, one or more bit members
2a included in the bit head 2 are provided with means 4 for
enhancing the drilling action, such as a corrugation, a
serration andlor the like, present on its cutting face 2a' ,
as depicted e, g. in fig. 9 . On the other hand, in yet another
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preferred embodiment, each bit member 2a included in the
bit head is made of tempered steel, at least in its cutting
face 2a'.
Especially in reference to fig. 5, the bit member 2a
included in the bit head 2 has an inclination angle a; a1
preferably of 14,5° and/or respectively an
incidence/cutting angle a; a2 preferably of 15°.
In a further preferred embodiment, the blade assembly has
its shank 1 provided with means 5 for adjusting the distance
of one or more bit members 2a with respect to a centre axis
k of the shank 1. In practice, the bit members have an
adjusting range which is preferably about 25 mm, whereby
an auger of e.g. 110 mm has a maximum capacity of making
135 mm holes.
In a preferred practical embodiment, referring
particularly to fig. 8, the above-mentioned means 5 are
established by means of elongated attachment holes 3a
present in a shank element 1; 1a", included in, the shank
and comprising two integrally built arm elements.
In still another preferred embodiment, one or more bit
members 2a included in the bit head 2 are adapted to have
a flexible attachment to the shank 1, specifically for
enabling self-adjustment of its cutting angle a; a2 . In the
solution of fig. 7, for example, the arrangement like this
is feasible by providing the bit members 2a with a recess,
in which a fastening screw, for example of the cap bolt type,
is countersinkable by fitting e.g. a spring washer between
its head and the bottom of the recess included in the bit
member. This is followed by securing the bit member in a
hole R present in the shank's arm element 1; 1a by using
for example a spacer member 3; 3b of the type shown in fig.
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7 and by locking e.g. a clamping screw or a locking stud
e.g. by means of a nut, a cotter pin, a wingnut and/or the
like . The spring washer, fitted as described above between
the bit member and the head of a clamping screw or a suitable
locking stud, allows for the bit member a small clearance.
Thus, with a high pressure applied to the bit member, e.g.
in the process of boring thick or sloshy ice, the result
is a shade smaller cutting angle for the bit member and a
reduced thickness for cuttings, the boring becoming
lighter towards the end of hole-making as opposed to what
happens in traditional boring.
As an option to the bit member shown in fig. 4, which is
made from a block of metal with equal all-round thickness,
the bit member 2a included in the bit head 2 is feasible
to manufacture in 1,5-3,5 mm gauge sheet steel, which is
formed with the cutting face 2a' and/or the means 4 for
enhanced drilling by die cutting or the like manner and in
which a bevel for the bit member's cutting face 2a' is
surface ground to an angle c preferably of about 25°.
It is possible to manufacture the above type of bit member
in the principle shown e.g. in fig. 9, such that the sheet
metal is first cut for a circular bit panel 2a~ , which is
then punched for the edge serration 4, the central hole R,
as well as an edge bevel X. This is followed by surface
grinding a bit member panel 2ao over its bottom surface for
providing a bit member 2a with a sharp cutting edge 2a'.
It is obvious that the invention is not limited to the
embodiments illustrated or described above, but a
multitude of most diverse variations can be made therein
within the scope of the basic inventive concept. Thus,
first of all, it is evident that the shank element, which
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is an integral part of the blade assembly, is feasible for
being manufactured from the most diverse of materials by
applying the most diverse of manufacturing techniques.
Furthermore, the number of arm elements included therein
can be more than presented above, which are nevertheless
preferably arranged symmetrically due to the intended
application. Still further, the embodiment with a single
rotary bit member, as described above as an option, can also
be naturally implemented so as to include several arm
elements. In this solution, it is also possible, instead
of a solution integrated with the blade assembly's shank
as depicted in a view of principle in fig. 10, to implement
the central element used for drilling a central hole by
applying appropriate quick-action couplings, such as e.g.
locking stud and cotter pin arrangements, a threaded
connection, a bayonet coupling or the like separate
connectable bit member, which due to its intended
application is preferably of a helical type but may also
be of some other type. Furthermore, the coupling of a blade
assembly to an ice auger can be implemented, as depicted
in fig. 7, simply by means of a through-bore present in its
attachment shaft, whereby it is connectable to the shank
of the ice auger's helical element e.g. with a locking
stud-cotter pin arrangement, a wingnut locking, or
generally by means of any "quick coupling" arrangement . The
coupling of a bit member rotatably to a shank element can
also be implemented in a plurality of ways, whereby the bit
member can have a . g . its central area made thicker than the
rest of it, which enables the head of a coupling-effecting
cap bolt or fastening stud to be countersunk completely
therein. It is further possible to make the bit member e.g.
disposable by using sheet metal therefor, whereby it
requires no sharpening in use, being always readily
replaceable with a new one. Naturally, instead of a spring
washer, the adjustment of bit members can be accomplished
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by flexible or other attachments enabling a slight tilting
movementfor the bit member. Respectively, the arrangement
used for the distance of bit members can also be implemented,
instead of an elongated hole, a . g. by means of a string of
5 holes.
