Log forming machine

A device that forms smooth cylindrical surfaces along a log being moved longitudinally past a cutting station. The device includes a feed conveyor that moves successive logs longitudinally past a cutting station. A planetary cutting head drive is situated at the cutting station. The drive rotates a cutting head about a first planetary axis spaced from the log axis. It also revolves the cutting head about a stationary second axis that is coaxial with the log axis. A smooth cylindrical cut is thus made about the periphery of the log as it is moved longitudinally parallel to its axis.

BACKGROUND OF THE INVENTION 
The present invention is related to log shaping machinery and more 
particularly to such machinery used to form substantially cylindrical logs 
as a construction material. 
Natural wood logs are regaining popularity as a building material. Log 
homes have a special aesthetic appeal and can be energy efficient if 
properly constructed. 
The insulative value of wood is not particularly high when values are 
measured through standard rectangular wooden boards. Logs, however, have a 
typical circular cross section that can lend a higher "R" value, depending 
upon the construction and type of wood. Conventional "R" values can vary 
not only with the thickness of wood, but also with its cross-sectional 
curvature. Annular rings and the cellular content of the wood add 
insulative qualities to the overall wood thickness. Escaping heat is 
trapped at successive circular barriers formed by the annular rings and 
within the tiny open cellular structure of the wood grain. The circular 
cross-sectional configuration of the logs forming a structure wall is 
therefore a very desirable feature. 
One prevalent problem with log construction has been the requirement of 
properly fitting logs together to obtain continuous, closed joints along 
their full length. Logs have a natural taper from one end to the other. 
Log taper can partially be corrected in construction by reversing lengths 
(end-for-end) of successive logs as the wall is being constructed. This 
technique, however, only solves the problem where tapers are nearly 
identical. Ideally, logs should be perfectly round, both for proper 
insulation value and for highest structural stability. 
It therefore becomes desirable to obtain a machine that will automatically 
form logs accurately with surfaces that are substantially cylindrical and 
centered about their longitudinal axes. The individual logs should be of 
uniform diameter to facilitate uniform construction of structural walls 
and to provide uniform insulative capacity.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
The device of the present invention is provided to operate on logs such as 
that shown at 10 in FIG. 5. The device functions to form cylindrical 
finished surfaces 11 along the length of the logs, the surfaces being 
centered about the longitudinal axis of the log. 
The cylindrical surfaces 11 are cut into the log as it is moved by a 
conveyor mechanism 16 (FIG. 1) longitudinally past a cutting station 
framework 17. Cutting heads 18 (FIGS. 2-5) at the cutting station 
framework rotate about planetary first axes, which in turn revolve about a 
stationary second axis coaxial with the log axis. Knives 53 about the 
periphery of the rotating cutting heads 18 trim the surfaces of the logs 
to the desired cylindrical shape. 
FIG. 1 illustrates the conveyor means 16 extending longitudinally on 
opposite sides of the cutting station framework 17. The conveyor 16 is 
basically divided, including a feed conveyor 20 and a tail conveyor 21. 
Both conveyors 20 and 21 include aligned upwardly facing working flights 
22. The flights 22 are simply lengths of endless chain situated within the 
base of V-shaped troughs 23. 
The troughs 23 receive and substantially center successive logs along a 
defined longitudinal path for movement relative to the cutting station 
framework and cutting heads. The troughs prevent rolling motion of the 
logs as they are moved past the cutting station. 
The logs are moved on the conveyors 20 and 21 by conventional electric or 
fluid powered drive motors 25. Removable dogs 24 mounted to the working 
flights of the conveyors 20 and 21, engage the ends of successive logs to 
move the logs along the length of the conveyor means past the cutting 
station and cutting heads 18. 
Opposite sides of the cutting station framework 17 mount means for holding 
the successive logs against the conveyors and for preventing rotation of 
the logs about their longitudinal central axes. The hold-down means 
includes lever arms 29 extending longitudinally from opposite sides of the 
cutting station framework 17. The lever arms 29 are pivoted to the 
framework and are selectively pivoted by means of cylinders 30 extending 
between the lever arms 29 and framework 17. The lever arm at the left in 
FIG. 1 is shown in an operative position. The arm 29 on the right side is 
raised to an inoperative position to demonstrate the pivoted extremes to 
which the arms can move. 
Free outward ends of the lever arms 29 mount pneumatic wheels 31 which 
frictionally engage the successive logs. The rough peripheral surfaces of 
successive logs are engaged by the wheel 31 on the feed conveyor side of 
the framework while the wheel 31 on the opposite side engages and presses 
downwardly against the finished log as it engages the tail conveyor 21. 
Both wheels 31 serve to hold the logs firmly against the conveyors 20 and 
21 and therefore increase the frictional hold of the conveyor against the 
log. Furthermore, the wheels press downwardly against the log to resist 
rotation of the log about its longitudinal axis. 
Important features of the present invention are situated within the 
enclosure of the cutting station framework 17. The framework itself 
basically includes a circular track 34 and supportive elements that will 
hold the track stationary and centered coaxially with the longitudinal 
center of successive logs moving through the device. Preferably, the 
circular track 34 includes an inwardly facing gear ring 35 (FIGS. 3 and 
4). 
A spool 36 is rotatably mounted by bearings 37 for rotation within the 
circular track 34. The bearings 37 function to hold the spool 36 in 
position coaxial with the log axes and allow free rotation of the spool 
about the coaxial axes. 
The bearings 37 receive circular runners 38 formed at opposite longitudinal 
ends of the spool 36. The runners 38 are directly adjacent upright side 
plates 39 of the spool. The side plates 39 include central openings, 
preferably coaxial with the spool axis and large enough to allow free 
longitudinal passage of a log therethrough. 
The spool 36 is rotated by means of a drive motor 42. The drive motor 42 is 
mounted to the cutting station framework 17 and may be interconnected with 
an appropriate form of gear reduction unit. A sprocket 43 is provided with 
the drive assembly that is connected by a chain 45 to a considerably 
larger sprocket 44 mounted on the spool 36 (FIG. 3). Sprocket 44 has an 
outside diameter slightly less than that of the circular runners 38. It is 
centered on the spool axis to rotate the spool in response to operation of 
motor 42. 
Cutting heads 18 are shown in FIGS. 3 and 4. The cutting heads are mounted 
to shafts 50 that are journalled by bearings 51. The shafts 50 turn within 
the bearings 51 about first axes parallel to the central spool axis and 
parallel to the coaxial log axis. Shafts 50 have cutter heads 52 (FIG. 4) 
mounted at inward ends thereof. The heads 52 each mount a number of knives 
53. The knives will move about the axes of the shafts 50 to cut across the 
grain of the logs, removing successive oval shaped chips to produce a 
desired surface texture, resulting in the formation of a cylindrical 
surface configuration along the exposed peripheral log surfaces 11. 
It will be noted that there are three cutting head assemblies shown in the 
drawings. It is understood, however, that as few as one head may be 
utilized or more than three, depending upon requirements of the mill. For 
example, where relatively large diameter logs are to be trimmed to a 
subsequently smaller diameter, more cutting heads might be required. 
It may also be noted that the cutting heads 52 are spaced longitudinally 
along the center longitudinal axis. Successive cuts at different cutting 
depths can thus be made as the log is moved past the cutting station (FIG. 
5). A first cutting head may be radially spaced by a first distance from 
the central log axis to form a relatively rough initial cut about the log 
periphery. As the log progresses on, a second cutting head, situated 
somewhat closer to the central axis may complete a second, intermediate 
cut to further reduce the diameter of the log. Finally, the log will 
engage the third cutter which is placed precisely to cut the log to a 
desired constant diameter. A log moving past the cutting station will thus 
be reduced gradually by the cutting heads to the finished diameter. 
The knives 53 are adjustably mounted to the heads 52 for removal and 
replacement or resharpening. The cutting edge configuration of the knives 
can be selected to determine the surface texture of the finished log. The 
speed of revolution of the knives, the speed of revolution of spool 36 and 
the longitudinal speed of the logs driven past the cutting station also 
affects the final finish texture. Logs can be produced with cylindrical 
surfaces 11 having extremely smooth textures or with a "hand hewn" 
texture. 
The cutting heads 18 are movably mounted to spool 36 by means of pivoted 
adjusting brackets 56. The adjusting brackets 56 are each pivoted at 57 
(FIG. 4) on the spools. The pivot axes of the brackets are parallel to one 
another and to the central axis of the log. Turnbuckles 58 extend between 
the brackets 56 and spool 36 to allow selective adjustment or radial 
positioning of the cutting heads at fixed selected distances from the 
central log axis. Selective adjustment of the turnbuckles 58 can therefore 
determine the finished diameter of the log and the effective diameter of 
any cut made previously to the finish cut. The turnbuckles 58 can also be 
used after each blade sharpening to reposition the cutting heads, thereby 
compensating for blade material lost in the sharpening process. 
The cutting heads are driven to rotate in response to rotation of the spool 
by means interconnecting the spool and frame. As described above, the 
spool 36 is rotated by the spool drive motor 42 and associated sprockets 
and chains. The rotational movement imparted by the motor 42 is 
transmitted to the cutting heads through the circular track 34. As briefly 
indicated above, the circular track 34 is stationary on the cutting 
station framework 17. 
The track 34 preferably includes an inwardly facing annular rack or "ring 
gear" 35 that is formed in a circle coaxial with the central spool and 
coaxial log axes. 
The wheel means as used herein is defined broadly as including any 
appropriate rolling device that will engaage and roll against the track 34 
as the spool is rotated about the stationary axis. Pneumatic tires, for 
example, have been used with some success. It is preferred, however, that 
the wheel means be supplied in the form of spur gears 60 for more positive 
engagement with the track 34 via the rack 35. 
Gears 60 are affixed to shafts 61. The shafts 61, in turn, are rotatably 
journalled within the spool 36. Bearings 62 mount the shafts 61 for free 
rotation within the spool about parallel longitudinal axes. The spur gears 
60 are designed to mesh with the ring gear on the circular hub 34. 
Therefore, rotation of spool 36 will cause corresponding rotation of the 
spur gears 60 and shafts 61. 
Outward ends of the shafts 61 mount first sheaves 63. These sheaves 63 are 
individually connected to second sheaves 64 on the outward ends of shafts 
50. Endless flexible driving members such as belts 65 interconnect the 
sheaves 63 and 64. Sheaves 63 and 64, and the belts 65 function as motion 
transfer means for rotating cutting heads 18 about their planetary first 
axes in response to rotation of the wheel means relative to spool 36. It 
should be noted here that the motion transfer means may also take other 
forms including for example sprockets and chains. 
The pitch diameters of the spur gears 60 and the effective diameters of 
sheaves 63 can be selected to produce a desired rotational velocity of the 
cutting heads for a prescribed rotational velocity of the spool. It is 
preferable to have the cutting heads rotating at a substantially higher 
rotational velocity than that of the spool. For example, if the spool 
rotates at 100 rpm. the cutting heads should be rotating at several 
thousand rpm. 
It may be noted that the shafts 61 and pivots 57 for the adjusting brackets 
56 are coaxial (see FIG. 4). In fact, it is desirable to journal the 
brackets 56 directly on the shafts 61. By doing so, pivotal movement of 
the cutting heads may be accomplished without changing the effective 
distance between sheaves 63 and 64. Therefore, no adjustment of the belts 
65 is required when the turnbuckles are adjusted to reset the radial 
distance from the central log axis to the cutting heads. 
It is believed from the above technical description that operation of the 
present invention may now be easily understood. 
Prior to beginning operation, the desired cross-sectional diameter of a 
desired finished log is determined by selectively adjusting the 
turnbuckles 58. The final diameter is determined by the last cutting head 
in the path of the forwardly moving log. However, the first two cutting 
heads may be adjusted through their turnbuckles 58 to take cuts of 
sufficient depth to progressively reduce the log diameter before the 
surface is engaged by the final, finishing blades of the last cutting 
head. 
The adjustments are accomplished simply by turning the turnbuckles 58 to 
correspondingly pivot the cutting heads on their brackets 56 in or 
outwardly with respect to the central log axis. 
When such adjustments have been completed, a log is placed on feed conveyor 
20. It is preferred that the log previously be slabbed, to form converging 
flat sides complementary to the V-shaped troughs 23. The slabbed sides of 
the log will engage the sides of the troughs and prevent rotation of the 
log as it is moved toward the cutting station framework 17. 
When the log is in position on the infeed conveyor, the drive motor 42 may 
be activated. The motor will function through the sprockets and chain to 
rotate the spool 36 about its central axis. As the spool rotates, so do 
the cutting heads. The cutting heads are rotated about the first axes of 
their mounting shafts 50 while the heads and shafts are being revolved 
about the second central rotational axis for the spool and coaxial log 
axis. 
The sprocket and chain assembly serve to rotate the spool on the log axis. 
As the spool rotates, the cutting head assemblies are revolved by the 
spool about the log axis. The revolving spur gears 60 are in meshing 
engagement with the stationary ring gear 35. The gears 60 must therefore 
rotate on their shaft axes in planetary motion as the shafts are revolved 
about the log axis. Rotational motion of the gears 60 is transmitted to 
the cutting heads through the belts 65 and sheaves 63 and 64. Gear and 
sheave ratios are selected to relate the speed of revolution of the spool 
to the desired speed of revolution of the cutting heads. 
Forward motion of the log is initiated as a dog 24 mounted to the working 
flight of the conveyor 20 comes into abutment with the rearward log end. 
The conveyor therefore pushes the log forwardly and longitudinally toward 
the revolving, rotating cutting heads. As the log progresses forwardly, 
its upper peripheral surface comes into contact with a wheel of the 
hold-down mechanism. The engaged wheel 31 will urge the log against the 
conveyor and trough and, prevent rotational movement of the log about its 
longitudinal axis as it progresses past the cutting station. 
The forward end of the log finally leaves engagement with the working 
flight of the feed conveyor 20 and enters through the opening of the spool 
36. The log is then engaged by the first cutter of the three. It cuts the 
first, rough circular swath about the log as the spool continues to 
rotate. This reduces the log to a first, rough cross-sectional diameter. 
The forwardly progressing log then comes into contact with the second 
cutter. The second cutter has been spaced radially inward with respect to 
the coaxial log and spool axes to cut a second circular swath about the 
log, removing material from the first diameter and reducing the log to a 
second, intermediate diameter. Finally, the log is moved into engagement 
with the third cutter which produces the final, finished diameter of the 
log before it exits through the opposite side of the spool and becomes 
engaged on the tail conveyor 21. The three progressive cuts are best shown 
in FIG. 5. 
A finished surface of the log is engaged by a second wheel of the hold-down 
mechanism as it moves beyond the cutting station and onto the tail 
conveyors 21. This wheel serves to hold the log firmly against the tail 
conveyor so its working flight can move frictionally against the log to 
pull it through the spool and operating cutting heads. Therefore, the log 
is held securely by the first conveyor until enough of the log has 
progressed through the cutters to be received on the tail conveyor and 
engaged by the remaining hold-down wheel. The rearward end of the log can 
then pass from the feed conveyor since the tail conveyor will pull the 
rearward log end through the spool while maintaining its coaxial 
relationship with the central spool axis. 
Special advantages are gained through the present device by moving the log 
past a relatively stationary cutting station and by moving the cutters in 
the described epicyclic motion. 
First, this allows smaller mill dimensions since logs can move 
longitudinally and successively from storage on one side of the device to 
storage on the opposite side. The device can be placed in line along with 
several other devices for performing other operations, such as cut-off 
saws, groove-forming machines, notch cutters and the like that can operate 
efficiently in an "in-line" arrangement with the longitudinal conveyors. 
Another advantage is that the present device does not require heavy, 
complicated equipment previously used to center and turn heavy logs in 
fixed position while a cutter is moved longitudinally to form the 
cylindrical surface. 
Still another advantage in moving the log longitudinally relative to a 
cutting station is that the log can be held rigid, directly adjacent 
opposite longitudinal sides of the cutter mechanisms. Thus, bending does 
not become a factor for gauging accuracy of the cutting tools. Previously, 
lathe type operations have been involved where the lateral forces of the 
cutting tool exerted between widely spaced points of suspension at 
opposite ends of the log caused bending of the log and correspondingly 
adversely affected the accuracy of cut. 
Moving the successive cutters in the described planetary motion has 
distinct advantages especially in mechanical simplification of the device. 
A single drive motor 42 can be used both to rotate the cutting heads about 
their own shaft axes and to revolve the cutting heads and shafts about the 
central log axis. The relatively high rotational speeds of cutting knives 
required to produce a smooth textured surface along the length of the log 
can be easily accomplished through the planetary arrangement. 
Log feed rate can be selectively adjusted relative to the rotational speed 
of the cutter heads and spool in order to achieve special textured quality 
of the resulting cylindrical surfaces. For example, if a roughed texture 
is desired, the feed rate of the conveyors may be stepped up while 
maintaining a normal or slower rotational speed for the spool and cutter 
heads. If a smooth surface is desired, the conveyor feed may be reduced 
while cutter head speed may remain the same or be increased. 
It is pointed out that the above description and drawings are given by way 
of example to set forth a preferred form of the present invention. The 
following claims, however, are intended to more particularly point out and 
distinctly define the invention.