Note: Descriptions are shown in the official language in which they were submitted.
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TILT ~nT.~ R~RnOWN HOI8T
Field of the Invention
This invention relates to the field of saw mill
machinery and in particular to an apparatus for breaking down
stacked and stickered rough lumber between the saw mill kiln and
saw mill planer.
Background of the Invention
It is known in the art to breakdown a stack of stacked
and stickered lumber arriving on an infeed transfer chain by
placing the stack on a rotatable hoist frame which may be rotated
to incline the entire stack of lumber. The stack of lumber is
then pushed by support arms up the inclined surface formed by the
inclined hoist frame so as to discharge under the force of
gravity rows or tiers of individual pieces of lumber from the top
of the stack of lumber as the top of the stack of lumber is
pushed beyond the uppermost end of the frame.
It is also known to assist pushing the stack of lumber
towards the uppermost end of the frame so as to discharge tiers
of lumber from the stack by providing secondary lumber stack
support arms which at some intermediate transfer point take over
the upward translation of the stack of lumber from the primary
lumber stack support arms on the rotatable frame.
In particular, applicant is aware of United States
Patent No. 4,838,748 which issued on June 13, 1989 to Johnson for
a device entitled "Hoist and Accumulator Arm Apparatus". Johnson
teaches a rotatable hoist frame for rotating a stack of tiered
material, such as stacked and stickered lumber, from an upright
position into an inclined position flush with an accumulator arm
apparatus. Hoist frame horizontal support members translate up
the incline to slide the load of tiered material upwards onto a
similarly inclined frame surface on the accumulator arm appar-
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atus. Retracted accumulator arms in the accumulator arm
apparatus extend from the accumulator arm apparatus normal to the
inclined frame surface once the load of tiered material has been
slid from the hoist frame onto the accumulator arm apparatus.
The accumulator arms take the place of the hoist frame horizontal
supports and slide the stack of tiered material further upwards
to a discharge point at the uppermost edge of the accumulator arm
apparatus. The accumulator arms then retract and are
repositioned ready to accept the next stack of tiered material
which has been transferred onto the hoist frame, rotated, and
translated onto the accumulator arm apparatus.
Thus, it is an object of the present invention to
provide a breakdown hoist which may be relatively quickly cycled
so that delivery of lumber from stacks of lumber which have been
broken down approaches a constant supply onto an outfeed transfer
device, and incidental to this it is an object to provide an
apparatus which does not require the rotation or tilting of the
entire hoist frame. It is a further object to provide a
breakdown hoist which reduces the probability of stacking sticks
falling inside the hoist frame.
Summary of the Invention
A breakdown hoist for breaking down a stack of tiered
material has an inclined face such that a stack of tiered
material may be translated by sliding upwards over the inclined
face. A supporting frame supports the inclined face.
Tilt arms or other such rotatable stack receiving
cradle receives the stack of tiered material from a stack
transfer device such as an infeed chain. The tilt arms rotate
the stack of tiered material into slidable engagement with the
inclined face, that is, so that the stack of tiered material lies
flush on its side on the inclined face.
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A translatable hoist arm translates the stack of tiered
material by sliding the stack upwards over the inclined face in
a direction towards the upper edge of the inclined face. The
hoist arm is rotatable between a recessed position, wherein it
is recessed beneath the inclined face, and a stack translating
position, wherein the hoist arm is substantially perpendicular
to the inclined face. When in the stack translating position the
hoist arm engages the underside of the stack of tiered material
which has been inclined flush with the inclined face.
The stack of tiered material is translated over the
inclined face towards the upper edge of the inclined face. The
tiered material is thus deposited over the upper edge of the
inclined face onto an outfeed transfer device such as an outfeed
chain. The hoist arm is then rotated into its recessed position
and translated downwards along the inclined surface so as to
reposition beneath the stack receiving cradle ready to rotate
into its stack translating position so as to translate the next
stack of tiered material upwards over the inclined surface.
Brief Description of the Drawings
Figure 1 is a perspective partial cut-away view of the
tilt cradle breakdown hoist of the present invention.
Figure 2 is a left side elevation view of the present
invention with tilt arms upright and hoist arms discharging
lumber.
Figure 3 is a left side elevation view with tilt arms
in an inclined position and hoist arms recessed and positioned
beneath tilt arms.
Figure 4 is a partial cut-away front elevation view of
the breakdown hoist of Figure 1.
Figure 5 is a detailed view of a portion of Figure 4.
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Detailed Description of the Preferred Embodiment
As illustrated in Figure 1, breakdown hoist 10 is
positioned for breaking down lumber stack 12 when delivered to
face 14 of breakdown hoist 10 via infeed transfer chains 16 on
infeed transfer frame 18. It is the purpose of breakdown hoist
10 to break down lumber stack 12 into individual pieces of lumber
12a. Individual pieces of lumber 12a are transported away from
breakdown hoist 10 on outfeed transfer chains 20. Outfeed
transfer chains 20 are supported by an outfeed transfer frame
(not shown).
Hydraulically actuated tilt arms 22 have lower arms 22a
and upper arms 22b. Lower arms 22a and upper arms 22b form a
rigid L-shaped cradle pivotally mounted about tilt arm pivot 24.
Tilt arms 22 may be hydraulically actuated by hydraulic ram 26
via linkage 28a and 28b so as to pivot tilt arms 22 about tilt
arm pivot point 24. Tilt arms 22 may thereby be rotated between
an upright position, wherein lower arms 22a are horizontal and
upper arms 22b are vertical, and an inclined position, wherein
upper arms 22b are, as illustrated in Figure 1, flush with face
14 and lower arms 22a protrude perpendicularly from face 14.
Infeed transfer frame 18 and infeed transfer chains 16
are arranged in proximity to breakdown hoist 10 so that the
lumber engaging surfaces 16a of infeed transfer chains 16 are
substantially aligned with the upper surfaces of lower arms 22a
when tilt arms 22 are in the upright position. As illustrated
in Figure 2, infeed transfer chains 16 may thus transfer lumber
stack 12 onto lower arms 22a so as to abut lumber stack 12
against upper arms 22b when tilt arms 22 are in the upright
position.
Once lumber stack 12 is transferred from infeed
transfer chains 16 onto tilt arms 22, hydraulic ram 26 may be
actuated to rotate rigid linkage arms 28a in direction "A" about
axle 30 on transfer frame 18. Rotating rigid linkage arms 28a
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in direction "A" drives connecting rods 28b against lower arms
22a so as to rotate tilt arms 22 from the upright position illus-
trated in Figure 2 to the inclined position illustrated in
Figures 1 and 3. Hydraulic ram 26, rigid linkage arms 28a, and
connecting rods 28b are pivotally connected at their ends. Axle
30 and tilt arm pivot 24 are mounted to the ends of longitudinal
supporting members 18a extending from infeed transfer frame 18.
When tilt arms 22 and lumber stack 12 are in the
inclined position, rotatable hoist arms 32 may be translated
downwards along inclined supporting member 34 so as to position
rotatable hoist arms 36 beneath tilt arms 22 as illustrated in
Figure 3. Rotatable hoist arms 36 rotate about pins 38 on
trolleys 40. Inclined supporting member 34 may be an I-beam or
channel member and trolleys 40 may travel within the channel
running the longitudinal length of the I-beam or channel member.
Trolleys 40 are translated downwards along inclined
supporting member 34 until rotatable hoist arms 36 may be rotated
in direction "B" from a position substantially parallel to face
14 to a position substantially perpendicular to face 14. Cables
42a and 42b, better seen in Figure 4, control the position of
trolleys 40 along inclined supporting member 34. Cables 42a and
42b may be tensioned to snug rotatable hoist arms 36 against the
underside of lumber stack 12 being supported by lower arms 22a.
That is, cables 42a and 42b may be tensioned to translate
trolleys 40 upwards along inclined supporting member 34 thereby
translating rotatable hoist arms 36 upwards against the underside
of lumber stack 12. Cables 42 may be further tensioned to raise
trolleys 40 upwards along inclined supporting member 34 thereby
translating lumber stack 12 upwards along face 14.
As the upper tier of lumber stack 12 is raised past the
top edge 14a of face 14, individual pieces of lumber 12a slide
from lumber stack 12 along inclined discharge members 44.
Discharge members 44 extend substantially perpendicular from face
14 downwards from top edge 14a. Discharge members 44 discharge
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individual pieces of lumber 12a onto outfeed transfer chains 20
so that individual pieces of lumber 12a may be transported away
from breakdown hoist 10 on outfeed transfer chains 20. Figure
2 illustrates this result. Rotatable hoist arms 36 have been
rotated from their position illustrated in Figure 3 so as to be
perpendicular to face 14 and then translated upwards along
inclined supporting member 34 so as to engage and translate
upwards lumber stack 12 thereby discharging individual pieces of
lumber 12a from the tier of lumber stack 12 raised above top edge
14a.
As illustrated in Figure 4, rotatable hoist arms 36 are
rigidly mounted to a transverse member 46 extending between
trolleys 40. Transverse member 46 and rotatable hoist arms 36
may be rotated about pins 38 by hydraulic ram 48. Transverse
member 46 rotates against stops 50, better illustrated in Figure
5. When transverse member 46 is rotated against stops 50,
rotatable hoist arms 36 are substantially perpendicular to face
14.
Hydraulic cylinder 52 may be retracted to tension
cables 42 thereby translating trolleys 40, transverse member 46
and rotating hoist arms 36 upwards along inclined supporting
members 34. In particular, cable 42a is affixed at one end to
transverse member 46, is threaded over single pulley 54, under
tensioning pulley 56, over double pulleys 58 and is affixed at
its distal end to upper transverse frame member 60. Cable 42b
is affixed to the end of transverse member 46 opposite the end
to which cable 42a is attached. Cable 42b is also threaded over
double pulleys 58 and is affixed to the end of upper transverse
frame member 60 to which is affixed cable 42a. Retraction or
extension of hydraulic cylinder 52 respectively elevates or
lowers trolleys 40, transverse member 46, and rotatable hoist
arms 36 along inclined supporting members 34.
As illustrated in Figures 1 and 4, face 14 may be
composed of parallel plates or sheeting supported by underframe
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members 62. The parallel plates or sheeting forming face 14 are
spaced apart so as to allow translation therebetween of rotatable
hoist arms 36 and rotation of tilt arms 22. Face 14 serves to
deflect sticks that might otherwise fall into supporting
S underframe members 62. Sticks may thus be collected for re-use.
In operation, lumber stack 12 is transported by infeed
transfer chains 16 onto tilt arms 22 when tilt arms 22 are in
their upright position. Tilt arms 22, and lumber stack 12
supported thereon, are then rotated into an inclined position
whereby lumber stack 12 is on its side flush against face 14.
Substantially simultaneously rotatable hoist arms 36 are rotated
from a position substantially perpendicular to face 14 to a
position substantially parallel to and beneath face 14 and then
translated downwards by trolleys 40 so as to descend along
inclined supporting members 34 beneath tilt arms 22 and lumber
stack 12.
Once positioned beneath tilt arms 22 and lumber stack
12, rotatable hoist arms 36 are rotated back into a position
substantially perpendicular to face 14 and translated upwards
along inclined supporting members 34, by tensioning cables 42a
and 42b, so as to engage rotatable hoist arms 36 against the
bottom surface of lumber stack 12 resting in tilt arms 22. That
is, when cables 42a and 42b are tensioned by cylinder 52,
trolleys 40 are translated upwards along inclined supporting
members 34 to thereby engage rotatable hoist arms 36 against the
bottom surface of lumber stack 12. Upon further tensioning of
cables 42a and 42b trolleys 40, transverse members 46 and
rotatable hoist arms 36 are translated further upwards, thereby
translating lumber stack 12 upwards by sliding lumber stack 12
over face 14.
As the top tier of lumber stack 12 is slid past top
edge 14a on face 14, individual pieces of lumber 12a are
discharged onto outfeed transfer chains 20 from inclined
discharge members 44. As individual pieces of lumber 12a are
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discharged in this manner from lumber stack 12, a tier at a time,
rotatable hoist arms 36 are translated further upwards along
inclined supporting members 34.
Once hoist arms 36 have been translated upwards beyond
the uppermost ends of upper arms 22b on tilt arms 22, tilt arms
22 are rotated back into their upright position ready to receive
another lumber stack 12 from infeed transfer chains 16. Thus a
cycle is established for the rapid breakdown of lumber stack 12.
Tilt arms 22 are receiving and inclining a second lumber stack
12 ready for upwards translation by rotatable hoist arms 36 while
individual pieces of lumber 12a are being discharged from a first
lumber stack 12 as the first lumber stack 12 is being translated
upwards by rotatable hoist arms 36. Once the first lumber stack
12 has been completely discharged, sensors (not shown) or a
sequence timer (not shown) or like cycle regulating machinery
actuate the rotation of rotatable hoist arms 36 from their
position perpendicular to face 14 to their position retracted
beneath face 14 and rotatable hoist arms 36 are translated
downwards for repositioning beneath the second stack of lumber
12 resting inclined against face 14 in tilt arms 22. Rotatable
hoist arms 36 are, once positioned beneath the second stack of
lumber 12 resting in tilt arms 22, rotated back into their
extended position perpendicular to face 14 and translated upwards
to thereby slide the second stack of lumber 12 upwards over face
14 to begin discharging individual pieces of lumber 12a from the
second stack of lumber 12. Once the rotatable hoist arms 36 and
the second stack of lumber 12 are clear of the uppermost ends of
upper arms 22b on tilt arms 22, then tilt arms 22 are rotated
back into their upright position ready to receive and incline a
third lumber stack 12.
The cycle may be continuously repeated. The result of
the timed or sequenced simultaneous co-operative movement of tile
arms 22 and rotatable hoist arms 36 is an almost continuous
breakdown of lumber stack 12 from breakdown hoist 10, only
interrupted by the time it takes to reposition rotatable hoist
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arms 36 beneath the next lumber stack 12 in tilt arms 22 and to
slide that stack upwards over face 14 to top edge 14a.
As will be apparent to those skilled in the art in the
light of the foregoing disclosure, many alterations and modifica-
tions are possible in the practice of this invention without
departing from the spirit or scope thereof. Accordingly, the
scope of the invention is to be construed in accordance with the
substance defined by the following claims.
