Position adjustment conveyor

A positioning conveyor is incorporated in a conveyor system for adjusting the position of a sheet on the conveyor system. The positioning conveyor has two belt type conveyor sections that are independently movable transverse to the feed path and are utilized to adjust the position of the sheet. The sheet is scanned by a scanner and the data is input to a computer. A vacuum zone on each section provides spaced apart gripping points to establish a pivot axis to correct for skew. The computer controls the coordinated movement of the sections to pivot and side shift the sheet to a desired position.

FIELD OF THE INVENTION 
This invention relates to a conveyor that provides skew and side shifting 
adjustment of sheets conveyed on a conveyor. 
BACKGROUND OF THE INVENTION 
Veneer sheets are used to produce laminated veneer lumber such as plywood. 
A thin layer of wood veneer is peeled from a log, cut into sheets, 
arranged in stacks of, e.g., three or more sheets, and glued together to 
produce continuous laminations varying in length and thickness depending 
on the thickness of the sheets and the number of sheets in the 
construction. 
Stacking and gluing of the veneer sheets to produce laminated veneer lumber 
is largely accomplished by automated pressing machinery. As contemplated 
herein obtaining ideal efficiency of the automated pressing machinery 
depends on continuous feeding of the sheets and that such sheets be fed 
(conveyed) to the machinery in a precise or near precise skew and side 
position orientation. 
The present invention is directed to achieving a final skew adjustment and 
positioning of sheets to place them in the desired orientation for 
automatic stacking by the pressing machinery but without interrupting the 
feed rate of the sheets. 
BRIEF DESCRIPTION OF THE INVENTION 
In a preferred embodiment, a conventional conveyor for veneer sheets feeds 
the sheets onto a position adjusting conveyor including a pair of 
independent conveyor sections or carriages arranged in sequence. The 
adjusting conveyor carries the sheets onto a further conveyor or into the 
automatic pressing machinery. The combined length of the two carriages is 
at least as long as a sheet of veneer plus the distance traveled during 
the positioning process. Each carriage has a pair of side belts engaging 
and conveying a sheet in the direction of conveyance. Each section is an 
independent unit and includes a drive motor, belt pulleys and side mounted 
belts. Each carriage includes a plenum in which negative air pressure is 
created. An opening of about two feet in length is provided along the top 
of the plenum under one of the belts of each pair of belts which belt is 
provided with openings or perforations. The plenum openings are provided 
at the front end of the first carriage and the rear end of the second 
carriage. Additionally, each carriage in its entirety is mounted for 
lateral sliding movement by actuators controlled by a computer. 
As the perforated belt travels over the plenum opening, air is drawn into 
the plenum and through the belt perforations to draw the veneer sheet 
against the belt. Thus, the sheet is secured to the belt at the position 
of the plenum opening, i.e., the front end of the first carriage and the 
rear end of the following carriage. Each sheet is scanned as it enters the 
conveyor sections and a desired skew and side shifting adjustment is 
calculated for that sheet by the computer. At the point where the sheet 
extends along both carriages so that a small area at both ends of the 
sheet is effectively secured by vacuum pressure to the perforated belt 
traveling over the plenum opening, the computer directs shifting of the 
carriages. The areas of the veneer sheet overlying the plenum openings 
functions as pivot points (albeit a moving pivot point) and the proper 
side shifting of the carriages produces both skew correction and side 
shifting alignment as desired for feeding the sheets to the automatic 
pressing machine. 
Whereas the two foot opening in each plenum does not specifically define 
the pivot point as such, considering the center of the opening as the 
pivot axis and making the corrections accordingly produces acceptably 
close adjustments, if not truly exact adjustments, of the sheets. 
The invention will be more fully understood and appreciated upon reference 
to the following detailed description having reference to the accompanying 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 illustrates a conveyor system 10 for conveying veneer sheets 11 from 
an inventory source 12 to a laminating press 14. The conveyor system 10 
includes a position adjustment conveyor 16 that is arranged to adjust the 
position of the veneer sheet 11 on the conveyor system 10 so that the 
sheet 11 is delivered to the press 14 in a desired attitude and position. 
The position adjustment conveyor 16 will rotate (pivot) and laterally 
shift the veneer sheet 11 as required to properly deliver the sheet to the 
press 14. The position adjustment conveyor 16 has independent carriages 
(sections) 20 and 22 that are positioned adjacent to each other and are 
independently movable. A scanner 24 is provided to scan the veneer sheet 
as it enters the position adjustment conveyor 16. The scan data is input 
to a computer and the computer will determine the skew and offset of the 
veneer sheet. The computer 26 will control movement of the carriages 20, 
22 as required to adjust the position of the veneer sheet 11. A vacuum 
system 28 supplies negative air pressure to a portion of each of the 
carriages 20, 22 which will later be explained. 
The inventory source 12 typically has stacks of sheets 11 that are 
sequentially placed on the first conveyor 13 and are transported toward 
the laminating press equipment 14 as indicated by arrow 30. The sheets 11 
are transported in sequence on the first conveyor 13 and may not be 
properly aligned with the press 14. The sheet 11 as it is delivered onto 
the positioning adjustment conveyor 16 will, if required, be adjusted for 
skew and offset by the carriages 20, 22. 
The scan data input from the scanner 24 to the computer 26 will establish 
the offset and the skew orientation of the sheet 11 on the conveyor system 
10 as it progresses onto the position adjusting conveyor 16. The computer 
utilizes the scan data to control the movement of the carriages 20, 22 to 
effect the pivoting and side shifting of the veneer sheet 11 on the 
position adjusting conveyor 16. 
The position adjustment conveyor 16 is further illustrated in FIGS. 2 and 
3. The position adjustment conveyor 16, as previously mentioned, has two 
independently movable carriages 20, 22. The carriages 20, 22 are of the 
belt type and each has a belt 34 on one side of the carriage and a 
perforated belt 36 on the opposite side of the carriage. The belts 36 of 
the carriages 20, 22 are of the perforated type which allows air to pass 
there through. A known vacuum system 28 provides a vacuum zone for each of 
the carriages 20, 22 with the vacuum zone of carriage 20 being indicated 
by arrow 38 and the vacuum zone of the carriage 22 being indicated by 
arrow 40. The vacuum zone 38 is essentially at the leading edge of the 
carriage 20 and the vacuum zone 40 is essentially at the trailing edge of 
the carriage 22. A plenum 39 is mounted beneath the belt 36 at each of the 
vacuum zones 38, 40 of the carriages 20, 22. Each plenum 39 is connected 
to the vacuum system 28. The vacuum system 28 is not detailed since such 
vacuum systems are known in the industry. The vacuum system 28 will 
withdraw air through the belts 36 in the zones 38, 40 and a veneer sheet 
11 in contact with the belt 36 within the zones 38, 40 will be forced 
downward against the belt 36 due to the differential air pressure. 
The carriages 20, 22 each have a separate drive motor for driving the belts 
34, 36 in unison. Further, the belts 34, 36 of carriage 20 are driven at 
the same rate as the belts 34, 36 of carriage 22. Carriage 22 has a master 
drive motor 44 and the carriage 20 has a slave drive motor 46 that is 
coupled to the master drive motor 44 in a conventional manner. The 
carriages 20, 22 are movable transverse to the feed path (indicated by 
arrow 30) of the conveyor system 10 as indicated by arrows 52, 54. A 
servo-cylinder (actuator) 48 is coupled to the carriage 20 and a 
servo-cylinder (actuator) 50 is coupled to the carriage 22. The 
servo-cylinders 48, 50 are controlled by the computer 26 to move the 
carriages 20, 22 in either direction as indicated by directional arrows 
52, 54. The carriages 20, 22 are independently movable in each direction 
and are further movable in unison. 
The carriages 20, 22 are mounted on guide ways 60 as best seen in FIG. 3. 
In this embodiment, the guide ways are ball bearing rails which provide 
minimum resistance to motion which facilitates the rapid and accurate 
positioning of each of the carriages 20, 22 by their respective 
servo-cylinders 48, 50. 
Refer now to FIG. 4 of the drawings which illustrates a veneer sheet 11 
being conveyed on the first conveyor 13 and being transferred to the 
position adjusting conveyor 16. Typically the sheet 11 when placed on the 
first conveyor 13 is not in proper alignment and thus may be skewed and/or 
offset. As shown in FIG. 4, the sheet 11 is skewed such that the 
longitudinal axis 70 of the veneer sheet 11 is not parallel to the center 
line 72 of the conveyor system 10 and in particular the press 14. Further, 
an edge 74 of the sheet 11 is not aligned with the zero line 76 of the 
press 14. 
The carriages 20, 22 of the position adjusting conveyor 16 are arranged to 
reposition the sheet 11 such that the longitudinal axis 70 of the sheet 11 
will be parallel to the center line 72 of the press 14 and further that an 
edge 74 of the sheet 11 will be in alignment with the zero line 76 of the 
press 14. 
FIG. 4 illustrates a sheet 11 just progressing onto the carriage 20 of the 
position adjusting conveyor 16. The belts 34, 36 of the carriages 20, 22 
are driven at a rate such that the sheet 11 will maintain its rate of 
travel without alteration as the sheet progresses from the first conveyor 
13 onto the position adjusting conveyor 16 and into the press 14. The 
belts 34, 36 of the carriages 20, 22 frictionally engage the sheet 11 to 
propel the sheet 11. 
FIG. 5 illustrates a sheet 11 progressing further on the position adjusting 
conveyor 16 and is advancing to a position where the carriages 20, 22 will 
both pivot the sheet 11 such that the center line 70 of the sheet 11 will 
be parallel to the center line 72 of the press 14 and will further move 
the sheet 11 in either direction as required to align the edge 74 with the 
zero line 76 of the press 14. As shown in FIG. 5, the sheet 11 has 
progressed on the position adjusting conveyor 16 such that a portion of 
the sheet 11 on the belt 36 is within the vacuum zones 38, 40 of the 
carriages 20, 22. The vacuum system 28 is arranged to withdraw air through 
the perforations of the belts 36 and thus the sheet 11 will be forced 
against the belt 36 due to the differential air pressure. The frictional 
engaging force between the sheet 11 and the belt 36 in the zones 38, 40 is 
greater than that of the engaging force between the sheet 11 and the belt 
36 outside of the vacuum zones 38, 40 and that between the sheet 11 and 
the belt 34. 
The sheet 11 is thus essentially gripped at two points with one of the 
points being the belt 36 in the vacuum zone 38 of carriage 20 and the 
other point being the belt 36 in the vacuum zone 40 on carriage 22. Two 
gripping points thus determine a pivotal axis about which the sheet 11 may 
be rotated or pivoted to align the longitudinal axis 70 in a parallel 
attitude with the center line 72 of the press 14. It will be appreciated 
that the gripping points established on the sheet 11 by the vacuum zones 
38, 40 will vary depending on the position of the sheet 11 on the position 
adjusting conveyor 16. In any event, two points are essentially 
established on the sheet 11 and thus the sheet 11 may be pivoted by 
movement of one or both of the carriages 20, 22. 
FIG. 6 illustrates the carriage 22 being moved in the direction as 
indicated by arrow 80 to thus pivot the sheet 11 on the carriages 20, 22 
to align the longitudinal axis 70 of the sheet 11 in a parallel attitude 
with the center line 72 of the press 14. The pivotal motion of the sheet 
11 is accomplished without altering the rate of travel of the sheet 11 on 
the conveyor system. As shown in FIG. 6, the sheet 11 has been moved to 
have its longitudinal axis parallel to the center line of the press 14. 
However, the edge 74 of the sheet 11 is not in alignment with the zero 
line 76 of the press 14. FIG. 7 illustrates the carriages 20, 22 being 
moved in the direction as indicated by arrows 82 to align the edge 74 of 
the sheet 11 with the zero line 76 of the press 14. 
The repositioning of the sheet 11 on the position adjusting conveyor 16 has 
been illustrated as a stepped process in FIGS. 4, 5, 6 and 7. However, it 
will be appreciated that the coordinated movement of the carriages 20, 22 
are moved directly to their end positions as shown in FIG. 7 from the 
initial positions as shown in FIGS. 4 and 5 to accomplish both the 
pivoting and the side shifting of the veneer sheet 11 to accurately 
position the sheet for the press 14. 
The sheet 11 is then fed directly into the press 14 or is transferred onto 
an infeed conveyor 17 which feeds the sheet 11 into the press 14. 
Those skilled in the art will recognize that modifications and variations 
may be made without departing from the true spirit and scope of the 
invention. The invention is therefore not to be limited to the embodiments 
described and illustrated but is to be determined from the appended 
claims.