Woodworking – Veneer lathe – Presser bar or roll
Reexamination Certificate
2002-09-16
2004-03-09
Bray, W. Donald (Department: 3725)
Woodworking
Veneer lathe
Presser bar or roll
C144S209100, C144S365000
Reexamination Certificate
active
06701983
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a peripherally driven veneer lathe and an improvement of a knife used therefor.
2. Prior Art
Recent years have witnessed so-called peripherally driven veneer lathes becoming the mainstream in the field of veneer lathes. The peripherally driven veneer lathe is designed such that at least part of the power required for peeling a log is supplied through the periphery of the log. Examples of this type of lathe are disclosed in, e.g., Japanese Patent Examined Publication (Kokoku) No. 59-28444, Japanese Registered Utility Model No. 2539258, Japanese Patent Examined Publication (Kokoku) No. 61-21808, and U.S. Pat. No. 6,357,496. The veneer lathe of this type comprises a peripheral-drive member having a plurality of drive members disposed at proper intervals along the axis, each drive member having on its periphery a number of piercing projections. The peripheral-drive member is disposed such that the piercing projections can pierce the periphery of the log immediately before the cutting edge of the knife. Thus, this type of lathe can transmit motive power to the log via the piercing projections in an extremely stable manner, resulting in its very wide use.
The peripherally driven veneer lathe of the above-described type will now be described by referring to an actual example shown in the drawings. As shown in FIG.
8
and
FIG. 9
, the latter being an enlarged view of a portion indicated by a circle B in
FIG. 8
, the peripherally driven veneer lathe comprises a knife
2
, a knife carriage
1
, a peripheral-drive member
4
, and a spindle
3
for supporting a log
5
. The knife
2
comprises a cutting face
2
a
and a flank
2
b
and is mounted on the knife carriage such that the flank is opposite the log. The peripheral-drive member
4
comprises a plurality of drive members
4
b
disposed at proper intervals along the axis, each drive member
4
b
being disposed substantially parallel to a cutting edge
2
c
of the knife
2
and having a number of piercing projections
4
a
on the periphery. Normally, the peripheral-drive member
4
is disposed at such a position that the piercing projections
4
a
can pierce the periphery of the log immediately before the cutting edge
2
c
of the knife
2
, which is mounted on the knife carriage
1
via a knife clamp
1
a.
A veneer
6
is produced by providing at least part of the motive power necessary for peeling the log
5
, held by a spindle
3
, from the peripheral-drive member
4
. This manner of supplying the power makes it possible to peel both an unusually hard and an unusually soft log with ease, which was very difficult for the conventional spindle-driven veneer lathes.
An improved example in practical use will be described by referring to FIG.
11
and
FIG. 12
, the latter showing an enlarged view of a portion of
FIG. 11
indicated by a circle C. In this example, the function of the piercing projections
4
a
is secondarily exploited. As shown, in addition to the features of the above-described example, this example includes a guide member
8
having a guide surface
8
a
mounted at the tip of the knife carriage
1
. The guide surface
8
a
substantially coincides with a part of a circle (to be hereafter referred to as a concentric arc) concentric with a rotation trajectory G of the piercing projections
4
a
but with a larger radius and therefore away from the rotation trajectory G by a predetermined distance. This example further includes a bending member
9
disposed between adjacent drive members
4
b,
by which the veneer
6
is forcibly bent toward the back side, thereby creating many surface cracks starting from the points pierced by the piercing projections
4
a
and providing the veneer
6
with flexibility. Another improved example (not shown) in practical use includes, in addition to the features of the above example, backup rolls for holding the periphery of the log from at least two directions, so that the log can be released from the spindle in the final stage of peeling and peeled until it becomes thinner than the spindle.
In this type of veneer lathe, the peripheral-drive member
4
is disposed such that the piercing projections
4
a
can pierce the periphery of the log immediately before the cutting edge
2
a
of the knife
2
mainly because at this position, a preferable engagement can be obtained between the piercing projections
4
a of the peripheral-drive member
4
and the log
5
. Specifically, in order to prevent the piercing projections
4
a
and the knife
2
from colliding with and damaging each other due to vibrations and the like of the peripheral-drive member
4
, the peripheral-drive member
4
must be disposed in such a manner as to ensure a gap S (see
FIGS. 9 and 12
) of more than a certain limit (generally, about 1 mm) between the rotational trajectory G of the piercing projections
4
a
and the knife
2
when the knife
2
and the peripheral-drive member
4
are most closely located (the peripheral-drive member may be fixedly secured to the knife carriage
1
, or it may be movably mounted thereon, as disclosed in the above-mentioned Japanese Registered Utility Model No. 2539258 or Japanese Patent Examined Publication (Kokoku) No. 61-21808). Also, the depth of piercing on the log
5
by the piercing projections
4
a
must be correspondingly controlled. Under these restrictions, the above position is preferable if the piercing projections
4
a
and the log
5
are to be satisfactorily engaged with each other as the log
5
is peeled and becomes smaller in diameter, as shown by the broken line in
FIGS. 8 and 9
. Another reason why the above position is selected is that positioning the peripheral-drive member
4
there enables the piercing projections
4
a
to pierce the veneer
6
as well, which facilitates the smooth delivery of the veneer
6
.
In other words, in order to obtain a satisfactory engagement between the piercing projections of the peripheral-drive member and the log, it is effective to set the position of the peripheral-drive member
4
such that an axis
4
d
of an axle
4
c
of the peripheral-drive member
4
is located on or near a line perpendicular to the cutting face
2
a
and passing at the cutting edge
2
c
of the knife
2
(the line passing at the edge of the knife and normal to the cutting face), as shown in
FIGS. 8 and 11
. While not shown, when the peripheral-drive member is movably mounted, too, as disclosed in the above-mentioned Japanese Registered Utility Model No. 2539258 or Japanese Patent Examined Publication (Kokoku) No. 61-21808, the peripheral-drive member is preferably positioned at the position as described above when the knife and the peripheral-drive member are most closely located with each other.
If the peripheral-drive member is disposed at a higher position than the above position, the piercing projections can be located further away from the knife and thus a collision can be reliably avoided and the piercing projections can more deeply pierce the log. However, in this case, the position at which the motive power is supplied will be further away from the cutting edge of the knife, and this creates a problem in the driving of the log. For example, if a part of the log is missing or the periphery of a non-cylindrical log is to be peeled, or if the log is to be peeled down to an extremely small diameter, it becomes difficult to perform peeling at the end portion of the veneer, i.e., the end portion may remain uncut and get stuck on the knife, thereby causing the veneer to be torn at an arbitrary, undesirable location, such as one on the extension of a crack (formed in the log) that already exists on the veneer.
In the above-described peripherally driven veneer lathe, the shape of the knife and the manner in which it is mounted on the knife carriage are the same as in the conventional spindle-driven veneer lathe. In the conventional example, as shown in
FIG. 11
, the knife
2
includes two parallel surfaces
2
a
and
2
d,
and a surface
2
b
which connects the two su
Bray W. Donald
Meinan Machinery Works Inc.
Westerman Hattori Daniels & Adrian LLP
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