Cutters – for shaping – Rotary cutting tool – Including holder having seat for inserted tool
Reexamination Certificate
2002-03-28
2003-11-11
Wellington, A. L. (Department: 3722)
Cutters, for shaping
Rotary cutting tool
Including holder having seat for inserted tool
C407S047000
Reexamination Certificate
active
06644896
ABSTRACT:
TECHNICAL FIELD
This invention relates to a slotting milling cutter, more specifically to an improved slotting milling cutter typified, for example, by a finger joint cutter for cutting a plurality of fingers at end portions of wood planks.
BACKGROUND ART
Finger joint is widely put in practical uses as means for joining a plurality of wood planks at their ends. The finger joint refers to a technique of forming a plurality of mountain range portions
12
at an end portion of each wood plank
10
as shown in
FIG. 15
, and then opposing the mountain range portions
12
of one wood plank
10
to those of another wood plank
10
, followed by compression of these two wood planks
10
against each other to achieve fitting engagement, as shown in FIG.
16
. These mountain range portions
12
are called fingers because of their shapes, and a slotting milling cutter for forming such fingers is generally referred to as a finger joint cutter. Incidentally, a suitable adhesive is applied to the mountain range portions
12
of wood planks
10
before they are fitted to each other.
Generally, a finger joint cutter essentially consists of a cutter body to be inserted and fixed to a spindle of a finger cutting machine and a plurality of projected cutting blades arranged at intervals, for example, with a center angle of 90° on the circumference of the cutter body to protrude radially outward. The pluralities of projected cutting blades are arranged in the axial direction of the cutter body in a comb shape. Each projected cutting blade is composed of a pair of tapered faces. The projected cutting blades assuming a comb shape are designed to have a profile as a whole such that they can cut a fingered portion (mountain range portions)
12
as shown in FIG.
15
.
While the finger joint cutter described above is of the type where the projected cutting blades are fixed integrally to the cutter body, there is also practiced a blade replaceable type having projected cutting blades attached removably thereto.
FIG. 11
shows such blade replaceable type finger joint cutter, in which blade bodies
22
are arranged on the circumference of a cutter body
20
at predetermined pitches (at equal pitches or unequal pitches) and are removably fixed by bolts
23
respectively. Each blade body
22
has a plurality of projected cutting blades
24
formed in a comb shape parallel to the thickness, as shown in FIG.
12
. That is, in the blade replaceable type finger joint cutter, the blade bodies
22
having projected cutting blades
24
each formed in a comb shape are designed to be detached from the cutter body
20
for replacement. The replaceable blades include right-side blade bodies
22
and left-side blade bodies
22
which are used separately depending on the kind of finger joint cutter. Provided that the pitch between tips of two adjacent fingers in the fingered portion
12
(see
FIG. 15
) is p, projected cutting blades
24
are formed at pitches
2
p
in a right-side blade body
22
. While projected cutting blades
24
are also formed at pitches
2
p
in a left-side blade body
22
, the blades
24
in the left-side blade body
22
are shifted by
1
p
leftward parallel to the thickness of the cutter body
20
with respect to the right-side blade body
22
. Right-side blade bodies
22
and left-side blade bodies
22
are arranged alternately on the circumference of the cutter body
20
. However, in the finger joint cutters shown in
FIGS. 11 and 12
, the right-side blade bodies
22
and the left-side blade bodies
22
are of the same configuration, and the left-side blade bodies
22
are positioned on the circumference of the cutter body
20
to be shifted leftward by
1
p
(1 pitch) thicknesswise with respect to the right-side blade bodies
22
. In other words the blade bodies
22
shown in
FIGS. 11 and 12
serve both as left-side blade bodies and right-side blade bodies.
The present invention relates to a blade body structure for forming an excellent film by physical vapor deposition (PVD) on a blade body
22
in a finger joint cutter. First, problems inherent in the prior art and special terms frequently appear in detailed description of the invention will be described.
FIG. 13
is a perspective view of the blade body
22
viewed against the rotational direction thereof, and
FIG. 14
is a perspective view of the blade body
22
viewed in the rotational direction thereof. In
FIG. 13
, the reference number
26
denotes a cutting edge in a projected cutting blade
24
, and the reference number
28
denotes a rake face in the blade body
22
. Side faces of the projected cutting blades
24
excluding the cutting edges
26
and the rake faces
28
are referred to as side flanks
30
. Bottom edges
32
are formed at troughs present between one projected cutting blade
24
to be on the same plane as the rake faces
28
of the projected cutting blades
24
are formed. Further, slant bottom faces located at troughs of projected cutting blades
24
and formed contiguous to side flanks
30
of each opposing pair of cutting blades are referred to as major flanks
34
. It should be noted here that there are cases where the bottom edges
32
have no sharp cutting edges. For example, when end faces of finger tips are to be formed using a finger joint cutter, the bottom edges need cutting edges. However, cutting edges are not necessary in the bottom edges when end faces of wood planks are cut beforehand using a circular saw to form finger tip end faces without cutting end faces of the finger tips using the finger joint cutter.
While blade bodies
22
of finger joint cutters are generally made of a hard material such as a high speed tool steel and a cemented carbide, there is supposed those having steel materials as bases to which such hard materials are joined. A technique is recently put into practice in order to increase durability of cutting edges in projected cutting blades
24
. According to this technique, a hard film such as of titanium (Ti) compound and chromium (Cr) compound is formed by physical vapor deposition (PVD) on the flanks along the cutting edges. However, a blade body
22
having a complicated configuration with a plurality of projected cutting blades
24
in a comb shape as shown in
FIG. 12
involves a problem in that it is difficult to form an excellent film uniformly by means of PVD. That is, in
FIGS. 13 and 14
, films to be formed on the side flanks
30
located between every opposing two projected cutting blades
24
and on the major flanks
34
around intersections of the side flanks
30
with the major flanks
34
of the bottom edges are porous or very thin and have extremely low adhesion. This is because excellent films are formed on the tips of the projected cutting blades
24
to make ions to be deposited hard to run through the clearances between the projected cutting blades to reach to the vicinities of the intersections.
While the rake faces
28
of the blade body
22
are sharpened in order to sharpen the cutting edges
26
, there is pointed out a problem that the films come off during this treatment at such portions having films formed thereon with poor adhesion as described above. Even if a fingered portion
12
as shown in
FIG. 15
is machined with a finger joint cutter to which blade bodies
22
having such durable films with poor adhesion are attached, the blade bodies
22
do not show sufficient durability, and the cutting edges
26
near the trough of the blade bodies
22
or those of the bottom edges
32
are dulled soon. The portions near the troughs of the projected cutting blades
24
perform machining of portions around the tips on the tapered faces of the fingered portion
12
, and if such portions come to have poor cutting performance, the finger tips of the fingered portion
12
come to have finished thickness greater than a design specification, as shown in FIG.
17
. Such fingered portions
12
having inaccurate tapered faces involve a significant problem in that, when they are engaged with each other, as shown in
FIG. 18
, the finger tips of the fingered porti
Kanefusa Kabushiki Kaisha
Koda & Androlia
Ross Dana
Wellington A. L.
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