Circular saw blade assembly

The present invention concerns a circular saw blade assembly for a saw mill or similar apparatus used for sawing boards from logs, said circular saw blade assembly comprising at least two circular saw blades attachable to and axially transferrable on a saw blade spindle as well as one or several edge milling cutters for shaping the board to a correct width. The circular saw blade assembly in accordance with the invention is implemented so that the edging cutter is formed by edge cutter elements adapted to adjacent circular saw blades, whereby the cutter elements are axially adjustable in relation to each other along with the spacing adjustment of the circular saw blades and each cutter element is comprised of one or several cutter knives and a block section having a recess machined to its face opposing the adjacent cutter element and having a penetrating hole for the saw spindle to pass, whereby the knives of the adjacent cutter elements are aligned to rotate along a single circle with an axial displacement of the elements at the different points along the cutting circle.

FIELD OF INVENTION 
The present invention concerns a circular saw blade assembly for a saw mill 
or similar apparatus used for sawing boards from logs, said circular saw 
blade assembly comprising at least two circular saw blades attachable to 
and axially transferrable on a saw blade spindle as well as one or several 
edge milling cutters for shaping the board to a correct width. 
BACKGROUND OF THE INVENTION 
Known in the art is a method for placing several circular saw blades 
axially transferrably on a common shaft (U.S. Pat. No. 3,630,244). This 
arrangement has a drawback in that the gap between the adjacent circular 
saw blades does permit the placement of edge shaping cutters to correct 
width for the trimming of the boards, but instead, the milling of the edge 
must be performed as a separate workphase. 
Also known in the art is an arrangement in which the edging of the log 
prior sawing is unnecessary and which makes the axial adjustment of 
spacing between the saw blades possible. One such implementation is 
disclosed in FI patent application 881402. The system described in the 
application comprises a circular saw blade assembly which has two circular 
saw blades on a spindle and the spindle hubs are further designed to act 
as cutters, whereby the cutter attached to the inner circular saw blade is 
formed into a cage supporting by its end side an inner circular saw blade, 
and the inner cutter supporting an outer circular saw blade by its end 
side is located axially transferrable inside the cage-like cutter and 
extends through the center hole of the inner circular saw blade. 
Such an axially adjustable circular saw blade assembly has only two 
circular saw blades, whereby only a wane and a slab can be cut from a log. 
The construction of the circular saw blade assembly is complicated, 
thereby leading to high costs. One of the cutters has constantly a maximum 
width, which causes wasteful use of log material, and correspondingly, to 
unnecessary growth of expenses. In addition, the diametrical difference of 
the cutters is small, which limits their useful operating range. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to achieve a circular saw blade 
assembly capable of overcoming the above-described drawbacks. The assembly 
in accordance with the invention is characterized in that the edging 
cutters are formed by cutter elements adapted to adjacent circular saw 
blades so that the elements are axially adjustable in relation to each 
other and the cutter elements are comprised of one or several cutter 
knives and a block section having a recess machined into the face opposing 
the adjacent cutter element and having a penetrating hole for the saw 
spindle to pass, whereby the knives of the adjacent cutter elements are 
aligned to rotate along a single circle with an axial displacement of the 
elements at the different points along the cutting circle. 
A preferred embodiment of the assembly in accordance with the invention is 
characterized in that both cutter elements are comprised of two 
diametrically oppositely placed cutter knives and that the adjacent cutter 
elements are phase-shifted by a 90.degree. angle. 
Another preferred embodiment of the method in accordance with the invention 
is characterized in that both cutter elements are comprised of three 
cutter knives diametrically spaced at 120.degree. angle and that the 
adjacent cutter elements are phase-shifted by 60.degree. angle. 
A further preferred embodiment of the method in accordance with the 
invention is characterized in that the cutter elements are attached to the 
circular saw blade by screw clamps and that the surface of the cutter 
element facing the circular saw blade is flat. 
The circular saw blade assembly in accordance with the invention offers an 
improved support of the blade between the flanges. All circular saw blades 
of the assembly are axially movable, whereby the edge cutter elements are 
simultaneously adjusted correspondingly, thus making it easy to alter the 
thickness of the board to be sawn without a need for changing the edge 
cutter elements. The construction of the assembly is simple and the edge 
cutter elements are replaceable, whereby the operation and maintenance of 
the assembly becomes advantageous. The diameter of an edge cutter element 
is not dependent on that of the other edge cutter elements, thus allowing 
for a free alteration of the element diameters. The number of the circular 
saw blades in the circular saw blade assembly in accordance with the 
invention is not limited, but instead, the same saw spindle can have 
several circular saw blades and independently operating edge cutter 
elements placed on it.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows a circular saw blade assembly comprising three circular saw 
blades 2, 5, 8 mounted on a saw spindle 1. Attached to the circular saw 
blades 2, 5, 8 are edge cutter elements 3. The pair of adjacent cutter 
elements 3, 4 forms an edge cutter. The edge cutter is axially adjustable 
along with the variable spacing of the circular saw blade 2, 5. An 
essential characteristic of the invention is that the cutter knives 6 of 
the edge cutter elements 3, 4 rotate axially coincidingly aligned along 
the same circle when the edge cutter is adjusted for minimum width, while 
the side edge of the cutter knife 6 of the cutter element 3 facing the 
cutter element 4 rotates axially coincidingly aligned with the side edge 
of the cutter knife 6 of the cutter element 4 facing the cutter element 3 
when the edge cutter is adjusted for maximum width. Thus, for instance, 
when thicker boards are to be sawn, the circular saw blade 5 is moved 
farther away from the circular saw blade 2. Then, the edge cutter element 
4 moves along with the circular saw blade 5, whereby the cutting width of 
the edge cutter is altered correspondingly. The cutter illustrated in the 
diagram between the circular saw blades 2 and 5 is shown adjusted to a 
nearly maximum width. Conversely, the cutter between the circular saw 
blades 5 and 8 is shown adjusted to a nearly minimum width. 
FIG. 2 shows the circular saw blade 2, the edge cutter element 3 and the 
edge cutter element 4 attached to the adjacent circular saw blade in 
partially sectional view. The cutter knives 6 of the edge cutter elements 
3, 4 are diametrically opposed on the same circle and the two cutter 
elements are phase-shifted by 90.degree.. 
For those versed in the art, it is obvious that the invention is not 
limited to the exemplifying embodiments described above; by contrast, the 
invention can be varied within the claims disclosed herein.