Patent Application
20070039664
(1) Technical Field
This invention relates generally to an infeed method and apparatus for conveying individual lengths of woodpieces to wood cutting equipment, and more particularly, to improving the loading of woodpieces onto a servo-driven belt conveyor.
(2) Description of the Prior Art
The following 5 documents relate to apparatus for infeeding articles onto a conveyor for transport.
U.S. Pat. No. 6,305,525 issued Oct. 23, 2001 to Miller et al. describes a pressureless infeed conveyor for establishing a spacing between articles on a conveyor having reciprocating carriages driven by a reversible servo-motor.
U.S. Pat. No. 6,199,463 issued Mar. 13, 2001 to Quick describes an apparatus and methodology for infeeding workpieces to a saw.
U.S. Pat. Nos. 5,368,080 issued Nov. 29, 1994 to Hamel describes an apparatus and related method for a board edging infeed optimization system.
U.S. Pat. No. 4,874,080 issued Oct. 17, 1989 to Wroblewski describes a conveyor a plurality of parts in a desired orientation in a single line as they are received from an aligning device.
U.S. Pat. No. 4,163,491 issued Aug. 7, 1979 to Rock, et al. shows a holddown mechanism for veneer clipper infeed conveyors.
In operations involving the sawing of wood in, for example, sawmills, or in processing for the production of furniture, several considerations are taken into account in cutting wood economically. These include the timing with which the wood is fed to gang saws, the safety of the workers who are responsible for loading the wood onto the conveyor, and the number of workers required for the operation. For efficient operation, modern wood machining systems require substantially continuous processing of relatively large volumes of wood. Accordingly, gang saws, and other machining apparatus, capable of operating at high sawing rates have been developed. In order to fully utilize the high sawing speeds, however, wood delivery systems must be capable of providing such apparatus with wood at the relatively rapid rate at which the machining apparatus is processing the wood.
Another important consideration is the optimal way in which an incoming piece of wood stock of irregular shape can be cut to reduce waste. Typically, a log is first cut lengthwise along a number of parallel, axial planes to yield a number of irregularly shaped planks sometimes referred to as “cants”. Cants cut from the same log all have the same length. However, the height (or width, when later placed flat on its broad side) of each cant will vary depending upon where on the diameter of the log the cut is made. Furthermore, the thickness of each plank will be determined by the spacing of saw blades, if the log is cut in a gang saw. Usually, when cutting planks or cants from the same log, the blades are set equidistant from each other so that the resulting planks all have the same thickness. While the thickness of each cant is therefore the same in this arrangement of the blades, the height of each cant, will vary depending upon the particular section of the log is cut. For example, cants which are cut from sections close to the center of the log, as in a circle, will be higher than those cut near its outer periphery. Moreover, the cants will generally taper in one direction corresponding the lessening diameter of the tree toward its top.
The prior art also provides movable clamping devices for clamping and positioning boards from below. However, these devices have the disadvantage of having high maintenance needs because the longitudinal feeding chains used to propel boards into the saws have to follow a complicated path around and below each clamping device, Another example is U.S. Pat. No. 6,199,463 B1 (Quick), hereby incorporated by reference in its entirety, also assigned to the present assignee, discloses an automated infeed system. Referring to
The present invention has been developed to provide a novel approach for mechanically and manually loading a first conveyor means with a workpiece to be released and conveyed past a scanning means for identifying the dimensional characteristics of the workpiece, and on to a second conveying means for feeding the workpiece into fixed arbor gang rip saws without the complications associated with prior art workpiece loading apparatus and methods. The disclosed apparatus together with its new method of application bring much needed improvements to wood cutting operations, as discussed more in details below.
It is therefore an object of this invention to provide an improved apparatus for automated feeding of a workpiece to a fixed arbor gang rip saw.
It is another object of this invention to provide a manual loading system that is ergonomically efficient and safely situated for a single person to operate.
It is another object of this invention to provide an automated infeed system having a low labor cost by reducing the total operation to a single person.
It is still another object of this invention to provide an improved apparatus for optimizing the sawing of wood pieces.
It is yet another object of this invention to provide an apparatus and method for selecting and maintaining a board orientation for feeding of a gang rip saw.
It is still another object of the invention to provide an automated infeed system having a low cost simple method for selecting a board cutting pattern and advancing the board to a gang rip saw while maintaining a selected board orientation.
In accordance this the aforementioned objects, there is provided an apparatus for automatically infeeding workpieces to a saw, under control of a computer. A first workpiece is manually placed on a gravity roller conveyor then released to a first conveying means. The width of the first workpiece is measured, and the workpiece is advanced under a projected pattern, the pattern based on the workpiece width and on optomizing yield. An operator may select an alternative pattern by moving the workpiece under the alternative patterns. An operator may also skew the first workpiece. The first workpiece is submitted to the saw input while maintaining the desired skew.
a is a plan view showing a sawing system of the prior art.
b is a side elevation view of the prior art sawing system.
Referring now to the drawings, in particular to
It will be observed in
Considering now in more detail the operation of the auto infeed system of the present invention, boards 290 are input at load station 410 on a pivoted roller structure. Shown in
The advancing board is picked up simultaneously by belts 322 which is driven in the direction of 350. The belts are driven by a single servo motor 123 which is connected to a shaft 123 that is common to all the belts. Such mechanical connections are well known in the art and as they are not significant to the invention are not described here in detail.
The pivoting of roller conveyor 315 and belts 322 are commanded from an operator controlled console 401 shown in
After leaving stops 313, a selected wood piece is smoothly accelerated by the belt system past a sensor area 430, where the board width is measured accurately by means of, for examply, a thru-beam type of optical sensor, coupled with position feedback operation from the servo motor driving the belts. One such sensor is the Omron (TM) model E3S-AT91.
As the board 290(a) is smoothly accelerated and then decelerated toward projection area 440, the measured width of the board is compared with all possible rip patterns, for example fifty such patterns, that are stored in the computer memory of console 401 and which correspond to the existing arbor gang saw configuration 370. For purposes of illustration, gang saw 370 is comprised of nine blades which are spaced arbitrarily. It will be appreciated that many different combinations of rip patterns can be achieved with the given blades. Only two simple patterns (A) and (B) are presented here as shown in
Assuming, for example, board 290(c) is automatically positioned for the optimum pattern (A) that will result in maximum yield (i.e., least scrap) as shown in
The actual rip pattern (A) is shown to the operator by means of visible projected lines on the board at the projection area 440 (and on the computer screen at console 401, though the operator would typically rely on the projected pattern). Various systems known in the woodworking industry may be used to project lines on the boards, such as a shadowbox ( in which a bright light is projected against a series of strings to create line shadows) or a laser system having one laser per line. A preferred laser unit is Lumber Line Lasers by John McCormick & Sons.
For each board, the operator is able to choose from many alternate rip patterns. For example, if a different pattern (B) appears preferable to the operator, perhaps to avoid ripping through a knot which would have resulted from using pattern (A), then he can choose that pattern and direct the system to align the board and present it to the saw accordingly as board 290(b) with pattern (B) in
In one key aspect of the invention, the operator may also manually skew the board at an angle other than perpendicular to the belts to, for example, avoid a knot or split in the board. Once the desired rip pattern and skew are determined, the operator advances the board to area 460 for pick-up by the pinch rollers 361 and 362. The friction belts 322 maintain the skew angle, and smoothly position the board for the desired rip pattern. This is in contrast to the related art systems which use a fence (thus providing for perpendicular orientations only) or a complex arrangement of alignment pins.
For each board 290, therefore, two moves are commanded by the automated infeed system. The first move positions the visible board 290(a) at the projection area 440 to show the operator the computer solution for the optimum yield. The second move posiitons the same board 290(b) in the pinch rollers 361 and 362 to match the arbor configuration with the chosen pattern.
It will be appreciated by those skilled in the art how several important attributes of the present invention add to its simplicity. Firstly, given the sequence of operation, the use of a two position roller structure, pivoted by a linear actuator to a first load position, such that a board 290 placed on it will slide roll (assisted by gravity) squaring against stops, and then pivoted to a second position to release the board to a first belt conveyor. The use of the two position roller conveyor is ergonomically designed for an operator to single handedly load the boards 290 from a supply pile 280 and to control the automatic infeed operation. Secondly, by the use of an industrial servo motor 123 which quickly and accurately positions the boards on the disclosed auto infeed system. In the preferred embodiment, the servomotor is a Kollmorgen # M605D-A. The servo motor allows the disclosed system to feed the rip saw without using a fence, as noted above. This allows lumber to be fed in any orientation resulting in increased yield.
The control system of console 401 shown in
Once the various measurements such as width and length of boards are received by the computer, the software program calculates useful parameters such as yield, lineal feed and board length. While processing lumber, the computer constantly displays the yield data for the board being processed as well as the entire batch of lumber. As stated herein, the width measurement is accomplished by means of a sensor and is recorded by a counter. The length may be determined by various means, as is known in the art, such as through the use of another roller (not shown), subjacent to the pinch roller 362, that is used to calculate the board length by counting roller rotations as the board is being fed to the gang rip saw.
Other parameters that are determined by the computer include the optimum use of the board based on current value of different board sizes. The value data for lumber can be periodically fed into the computer and used to optimize the desired cut. The operation of the automated infeed system disclosed in this invention is a fully integrated system comprising the computer, feed-back instrumentation on the floor, and the operator's console 401.
The invention offers advantages over the prior art in providing a low-cost, simplified method and apparatus for the loading and cutting of wood pieces using a gang rip saw, that provides additional flexibility in the manufacturing environment for optimizing yield. A wood piece is placed by hand onto a raised roller structure to slide to a stop located on a lower end of the roller structure. The roller structure is made up of a series of interconnected rectangular members disposed contiguous a matching series of friction belt conveyors that form the first conveyor. The roller structure has a pivot end and a movable end. Each rectangular member has a raised step member on its top surface proximate the pivot end for stopping the wood piece from advancing beyond the ramped roller structure. A linear actuator is used to raise and lower the movable end. Raising the moveable end forms a ramp, lowering releases the wood piece to the first conveyor. The sliding action is assisted by a linear array of roller bearings affixed to an upper edge of each of said rectangular members so that once a wood piece is placed on the ramp it will slide, assisted by gravity, in the direction on the first conveyor while squaring up against each raised step.
When the roller structure is lowered, the raised step member declines below the top surfaces of the moving friction belts forming the first conveyor. The workpiece is released and conveyed transversly past a scanner to determine its dimensional characteristics. The workpiece is then moved to a second conveyor to feed the workpiece to a saw.
While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention.
