A method and apparatus for splitting a log substantially along the grain into a plurality of sector-shaped segments are described. The apparatus comprises at least one sector splitter ring having a plurality of blades, a support for locating the splitter ring in a log movement path, means for pushing the log axially along a log movement path, a rotating backplate for supporting one end of the log being pushed along, which backplate is adapted to tilt and allow the backplate-supported end of the log to rotate as the log is pushed through the splitter ring, and guide means adapted to retain the floating backplate in the log movement path. The process comprises forcing one end of a log axially against and through at least one splitting blade, the other end of said log being in contact with a backplate that can tilt, and permitting relative rotation between the log and the splitting blade so that a split occurring in the log from the splitting blade substantially tends to follow the grain in the log.

This invention relates to splitting logs into segments. More particularly, 
this invention relates to a device and a method for splitting a log 
substantially along the grain of the wood. 
There are two basic methods for splitting logs. The first method is impact 
splitting which is carried out with an axe or the like. The splitting 
occurs suddenly and completely due to the impact force of the axe head 
striking the end of a log. This method is generally only applicable to 
short logs; the axe or cutting head tends to stick in long logs. The 
second type of splitting is pressure splitting wherein a blade or wedge is 
pushed into one end of a log, or vice versa, such that a split or crack 
occurs in front of the blade and travels along the log as the blade 
continues to be pushed through the log. The present invention relates to 
pressure splitting and more specifically, splitting a log substantially 
along its grain. 
In the past, logs have primarily been split for use as fire wood so that 
the quality of the split wood sections has not been important. In 
contrast, this invention comprises splitting logs substantially along the 
grain to maintain the grain integrity of the split sections. The present 
invention is concerned with the preparation of long wood strands for 
structural lumber products. An example of one type of structural lumber 
product fabricated from strands oriented along their length is disclosed 
in U.S. Pat. No. 4,061,819 issued Dec. 6, 1977. 
One method for producing long wood strands with longitudinal grain 
extending along their length may involve radially splitting logs 
substantially along the grain into a plurality of sector-shaped segments. 
The segments are then processed further to produce long relatively thin 
strands, for example, by further splitting of the segments. Methods of 
producing wood strands by further splitting of wood segments are disclosed 
in copending U.S. patent application Ser. No. 199,191, entitled "Process 
for Preparation of Long Wood Strands", and copending U.S. patent 
application Ser. No. 199,190, entitled "3-Step Process for Preparation of 
Long Wood Strands", both filed concurrently herewith. 
In the splitting of a log, the crack or split occurs in front of the blade. 
In many cases, the grain is not necessarily parallel to the axis of the 
log but follows a helical course and this causes the log to attempt to 
twist while being split. If the log cannot freely twist, the internal 
splitting forces become great and unwanted splits may occur. In some cases 
breaks may occur across the grain, thus resulting in slivers, splinters 
and undesirable short segments. 
The types of logs which can be split into strands are conventional saw logs 
and pulp logs that have grain extended generally in line from end to end 
of the logs. Logs with interlocking spiral grain are, of course, difficult 
to split. 
An object of the present invention is to provide a device and a method for 
splitting a log wherein the log is allowed to rotate so that the split 
tends to follow the grain in the wood. 
Another object is to provide a splitting device having an end plate which 
can tilt to apply an even force to the end face of a log and which can 
rotate when the log is being split. 
The present invention provides an apparatus for splitting a log 
substantially along the grain into a plurality of sector-shaped segments, 
comprising at least one sector splitter ring, having a plurality of 
blades, support for locating said splitter ring in a log movement path, 
pressure means for pushing the log axially along the log movement path, a 
rotating backplate for supporting one end of the log being pushed axially 
along the log movement path, said backplate adapted to tilt and allow the 
one end of the log to rotate while the log is pushed through the splitter 
ring, and guide means adapted to retain the floating backplate in the log 
movement path while the log is pushed through the splitter ring. 
There is also provided in the present invention a method of 
pressure-splitting a log comprising the steps of: forcing one end of a log 
axially against and through at least one splitting blade, the other end of 
said log being in contact with a backplate which can tilt, and 
simultaneously permitting the log and the splitting blade to rotate 
relative to each other so that a split occurring in the log from the 
splitting blade substantially tends to follow the grain in the log. 
This invention permits the unsplit portion of the log to rotate freely as 
it approaches the splitting blades during the splitting operation. In 
addition, the backplate tilts to press evenly upon the back of the log 
thereby maintaining a centered forward thrust on the log. By use of the 
backplate according to this invention, the power requirements of the 
splitter and internal machine forces are reduced.

Logs suitable for splitting are generally straight and meet normal 
requirements for conventional saw logs or pulp logs. Knots in a log 
generally pass through a sector splitter without causing problems. 
The moisture content of the logs is preferably maintained at not less than 
fiber saturation during splitting. Fiber saturation represents 
approximately 30% moisture content, varying slightly from one type of wood 
to another. High moisture content does not present a problem in pressure 
splitting but dry logs tend to resist pressure splitting and more force is 
needed to push dry logs through a splitter. 
In some cases it is preferable to debark the logs before the splitting 
step. The decision to debark depends on the type of wood being split and 
the use to which the resulting product is to be put. The debarking step 
has no bearing on the splitting step which can be carried out on barked or 
debarked logs. 
Referring now to FIGS. 1 and 2, a log 10 is shown being pushed by a 
hydraulic cylinder 11 through a sector splitter ring 12. The sector 
splitter ring 12 has splitting blades 13 arranged to split the log 10 into 
eight sector shaped segments 14. The arrangement of blades shows the 
center of each blade extending forwards to form a central tip 13A. This 
configuration aids in the commencement of splitting a log, but is not 
essential. The hydraulic cylinder 11 has a link connection 15 at the end 
of the piston rod 11A joined to the support plate 16. The support plate 16 
forms the forward plate of a carriage 17 having arms 17A extending back on 
each side with two support rollers 18 resting on the flanges of side 
channels 19 which form part of the frame 20 for the splitter. Side rollers 
18A attached to the sides of the support plate 16 guide the carriage 17 
and run on the inside web of the side channels 19. Thus, the hydraulic 
cylinder 11 moves the carriage 17 horizontally forwards and backwards in a 
log movement path. The hydraulic cylinder 11 is attached to a support 
bracket 20A which in turn is rigidly attached to the side channels 19 and 
the frame 20. Similarly, the splitter ring 12 is mounted on a backing 
plate 21 rigidly attached to the side channels 19 and the frame 20. The 
carriage assembly 17, shown more clearly in FIGS. 3 and 4, has a rotating 
backplate 22 which is held to the support plate 16 by means of a base clip 
23 and two side clips 24. The backplate 22 has a button or disc 22A 
attached to the back thereof. The button 22A has a domed back surface to 
aid in allowing the backplate to tilt thus enabling the backplate to press 
evenly over the end surface of the log which may not be square with the 
log axis. The backplate 22 is a circular disc and is held in the three 
clips 23 and 24 merely by its own weight. The lower clip 23 provides 
limited space for the backplate 22 to tilt. Similarly the two side clips 
24 also allow the backplate 22 to tilt in either direction. The distance 
between the two side clips 24 is sufficiently larger than the diameter of 
the backplate 22 to allow limited sideways movement of the backplate 22. 
Thus, the backplate 22 may rotate on the button 22A within the clips 23 
and 24, it may tilt about the button 22A within the clips 23 and 24 and 
has a sideways movement which is limited by the location of the two side 
clips 24. This movement is preferably limited to between one quarter and 
one half inch. In a preferred embodiment a pin 25 is provided at the 
center of the front face of the rotating backplate 22. The pin 25 is used 
to engage the log prior to splitting. 
Another embodiment of an arrangement between the support plate 16 and the 
backplate 22 is shown in FIG. 5 wherein only two side clips 30 are 
provided to hold the backplate 22 in position. The side clips 30 allow the 
backplate 22 to rotate and tilt. They also allow the backplate to be 
raised and, if necessary, removed from the carriage 17. 
When a long log is to be split, at least one axial support 26 as shown in 
FIGS. 1 and 2 is preferably used to support the log 10 for the first 
portion of the push through the splitter ring 12. Although only one axial 
support 26 is shown, several may be used and they should be removed as the 
log 10 is slowly pushed through the splitter ring 12. 
A log 10 preferably is positioned such that one end has its growth center 
at the central tip 13A of the blades 13 in the splitter ring 12. Axial 
supports 26 may be placed under the log 10 resting on the frame 20. The 
hydraulic cylinder 11 pushes the carriage assembly 17 along the log 
movement path. Pin 25 on the rotating backplate 22 is optional because the 
pressure between the backplate and log is generally great enough to 
support the log. If the end of the log is not perpendicular, the backplate 
22 tilts about the button 22A to ensure that the pressure is spread evenly 
over the end of the log. The hydraulic cylinder 11 then proceeds to push 
the log 10 through the splitter ring 12 to produce segments 14. As the 
blades 13 of the splitter ring 12 enter the end of the log 10, a split or 
crack 27 as shown in FIG. 2 commences at each blade and extends backwards 
along the log for a considerable distance. The split may extend backwards 
for any length up to the complete length of the log. This causes the 
segments 14 to spread outwards, so the apparent diameter of the 
arrangement of segments 14 leaving the splitter ring 12 is considerably 
larger than the diameter of the log 10. As the log is pushed by the 
hydraulic cylinder 11 the grain in each log does not follow a straight 
line, but may twist in the log. The rotating backplate 22 with the button 
22A at the back thereof allows the other end of log 10 to follow this 
twisting movement so that the split 27 follows and extends along the grain 
rather than being forced across the grain. If a long log 10 is being 
split, the axial supports 26 should be removed as the carriage 17 moves 
along the side channels 19. 
In practice it has been found that permitting limited sideways movement of 
the backplate is not an essential feature of the present invention but 
only one embodiment. The configuration shown in FIGS. 3 and 4 allows 
limited sideways movement of the backplate, but the embodiment shown in 
FIG. 5 does not. Both embodiments provide a rotatable connection allowing 
the backplate to rotate as required by the grain in the log, and to pivot 
to conform to the end face of a log so that the hydraulic cylinder 11 
applies a force evenly over the end face of the log. 
When the rotating backplate 22 is within a short distance of the splitter 
ring 12, provision should be made to complete passage of the log through 
the splitter ring 12 without allowing the backplate 22 to press against 
the splitter ring 12, which may damage the splitter ring. The direction of 
travel of the hydraulic cylinder 10 is reversed and the carriage 17 is 
moved back. If another log is to be split, then after the carriage 17 is 
moved back to its starting position, a second log is positioned with one 
end resting against the end of the first log still in front of the 
splitter ring 12, and the other end of the second log is placed with its 
grain center on the centering pin 25 of the backplate 22. The hydraulic 
cylinder 11 is then activated so the second log pushes the end of the 
first log through the splitter ring 12. The second log is then split in 
the normal manner. Alternatively, if there are no more logs to be split, 
then a special device (not shown) is rigidly mounted on the support plate 
16 of the carriage 17. The special device has fingers or probes that 
extend between the blades 13 of the sector ring 12. The hydraulic cylinder 
11 is then activated so that the special device pushes the end of the log 
10 completely through the splitter ring 12. Other devices such as one 
which grips the split ends of the log and pulls the log completely through 
the splitting ring may also be employed. 
An alternate embodiment of the splitter ring is shown in FIG. 6 wherein a 
leading horizontal blade 41 extends across the face of the splitter ring 
40 and has trailing edges from a center point 42. A vertical blade 43 
extends across the splitter ring 40 behind the leading blade 41 and two 
sets of blades 44 between the horizontal blade 41 and the vertical blade 
43 are set back from the vertical blade 43. This embodiment reduces the 
instant load at commencement of splitting because the horizontal split 
commences followed by the vertical split and the two angled splits. 
The splitter ring 12 preferably has eight blades as shown in FIGS. 6 and 7, 
which split a log into eight substantially equal sector-shaped segments. 
However, in another embodiment a different splitter ring 60 as shown in 
FIG. 8 has thirty-two blades 61. The number of blades is dependent upon 
the number of segments required. It will be apparent to those skilled in 
the art that employing a single splitting blade extending across the 
diameter of the log would be the simplest splitting operation, requiring 
application of the smallest amount of force to effect the splitting. On 
the other hand, when more than thirty-two blades are used, considerable 
force must be applied to the end of the log and a certain amount of 
crushing or splintering of the wood may occur. 
FIG. 9 shows another embodiment wherein three separate splitter rings and 
two spacers are combined. A first splitter ring 70 has blades 71 and is 
followed by a spacer ring 72 which also acts as a guide to ensure that the 
segments of wood retain their position and do not move either too far 
radially outward or twist out of their initial location. A second splitter 
ring 73 has blades 74 positioned so that they split the segments which 
have been first split in the first splitter ring 70. Following the second 
splitter ring 73 is a further spacer ring 75 which ensures that the split 
segments retain their position, and then finally a third splitter ring 76 
with blades 77 to split the segments yet a further time. The three 
splitter rings 70, 73 and 76 produce narrow segments. In a preferred 
embodiment the first two splitter rings each have eight blades and the 
third splitter ring has sixteen blades, thus producing thirty-two wood 
segments. It will be understood that both the splitter rings and the 
spacer rings are mounted on the side channels 19. In other embodiments 
with fewer blades in the splitter rings, the spacer rings may be omitted. 
It will be apparent to those skilled in the art that various changes may be 
made in the details of the splitter device shown in the drawings without 
departing from the scope of the present invention which is limited only by 
the claims. For instance, the end plate may be attached to and supported 
from the piston rod by, for example, a ball bearing and socket arrangement 
that allows the plate to rotate and tip. In addition, the hydraulic 
cylinder may operate from the opposite end of the apparatus and push the 
splitter ring through the log. The rotating backplate still allows the 
free end of the log to rotate. In another embodiment the splitter ring or 
the assembly of several splitter rings may be allowed to rotate to aid in 
splitting a log along the grain. The backplate in this embodiment may or 
may not rotate but is capable of tipping. 
Whereas a hydraulic cylinder has been described herein as the only pressure 
means for pushing the log through the splitter ring assembly, other types 
of pressure means such as air cylinders or mechanical chain systems may 
also be employed.