Patent Application
20130032017
The present application relates to ripsaws for ripping a wide board into a plurality of narrower boards for uses such as flooring, moldings, furniture, and the like. The application more particularly relates to a power ripsaw having multiple circular saw blades (referred to herein as a “multi-blade ripsaw”) spaced apart on a common drive shaft or arbor.
Multi-blade ripsaws of the above-indicated type are commonly used for ripping wide boards into narrower boards for uses such as flooring or a host of other uses. Some multi-blade ripsaws also have the ability to variably position the saw blades at selected positions along the shaft or arbor. There are a number of basic approaches to such adjustment of the positions of saw blades. In some cases, an operator must manually adjust the saw blade positions. Manually adjustable multi-blade ripsaws can include some sort of radially expandable elements in the arbor that are controlled by a knob at the end of the arbor, the expandable elements engaging the inner surface of the central aperture in each saw blade to fix the saw blades in position. To adjust the saw blades to selected positions along the arbor, the knob is turned to retract the expandable elements, which allows the blades to be moved along the arbor to the desired positions. The knob is then turned in the opposite direction to extend the expandable elements to fix the blades in position. Alternatively, each of the blades can be connected to a collar that can be loosened on the arbor and moved to a desired position and then tightened on the arbor to fix the blade in the selected position.
Another approach to the adjustment of saw blades in multi-blade ripsaws is automated positioning through the use of either a rotary electric servomotor or the like, or a pneumatic or hydraulic cylinder arrangement. Automatically adjustable multi-blade ripsaws known to the present inventors tend to be mechanically complex and are not particularly fast at adjusting the blade positions.
The present disclosure describes a multi-blade ripsaw having an automated blade position adjustment system that is faster and mechanically simpler than known systems. In one embodiment as described herein, the ripsaw comprises an arbor mounted in bearings for rotation about an axis thereof, a motor and drive assembly coupled to the arbor for rotating the arbor about the axis, and a plurality of blade assemblies mounted on the arbor. Each blade assembly comprises a spindle having a saw-mounting portion, and a saw blade mounted on the saw-mounting portion. Each of the saw-mounting portions defines a central aperture for receiving and engaging the arbor in a manner permitting the spindle to slide along the arbor while preventing relative rotation between the saw-mounting portion and the arbor, so that rotation of the arbor causes the saw-mounting portions and the saw blades to be rotated. The blade assemblies can be slid to any selected positions along the arbor.
The ripsaw further comprises a blade-positioning mechanism operable to position each of the blade assemblies at a selected axial position on the arbor and hold the blade assembly in said position during sawing. The blade-positioning mechanism comprises a plurality of blade-positioning units respectively engaged with the spindles and mounted on a rail assembly extending parallel to the arbor. The blade-positioning units are movable along the rail assembly to position the respective blade assemblies at desired positions along the arbor. The blade-positioning units and respective blade assemblies are divided into a first group and a second group arranged in interleaved fashion along the rail assembly and arbor, such that a blade-positioning unit and blade assembly of the first group is followed by a blade-positioning unit and blade assembly of the second group, which is followed by a blade-positioning unit and blade assembly of the first group, and so forth.
The blade-positioning mechanism further comprises first and second linear motors respectively arranged on opposite sides of the rail assembly, each linear motor comprising a platen extending parallel to the rail assembly and a plurality of forcers movable along the platen. The forcers of the first linear motor are respectively fastened to the blade-positioning units of the first group, and the forcers of the second linear motor are respectively fastened to the blade-positioning units of the second group.
With the described blade-positioning mechanism, it is possible to make rapid adjustment of the saw blades' positions along the arbor because the linear motors are capable of high-speed movement of the forcers and thus of the blade-positioning units. Furthermore, the linear motors enable highly accurate positioning of the forcers and hence of the blade-positioning units and associated blade assemblies. The blade-positioning mechanism is mechanically much simpler than the automated blade-positioning mechanisms of which the present inventors were aware prior to the present invention.
In one embodiment, each blade-positioning unit engages the respective spindle in a releasable fashion. Each blade-positioning unit can include a user-operable engage-disengage mechanism that is movable between a spindle-engaged position in which the engage-disengage mechanism engages the spindle such that movement of the blade-positioning unit along the rail assembly causes movement of the spindle along the arbor, and a disengaged position in which the engage-disengage mechanism is disengaged from the spindle such that the spindle is movable along the arbor independently of movement of the blade-positioning unit. In a particular embodiment as described herein, each spindle defines an engagement recess in a radially outer surface of the spindle, and each engage-disengage mechanism includes a spindle-engaging portion that is engaged in the engagement recess in the spindle-engaged position and is disengaged from the engagement recess in the disengaged position. Each engage-disengage mechanism can include a detent mechanism that holds the engage-disengage mechanism in the spindle-engaged position and requires manipulation (e.g., pressing on a detent member) to allow the engage-disengage mechanism to be moved to the disengaged position.
In an exemplary embodiment, each engage-disengage mechanism has the spindle-engaging portion at one end thereof and a knob or handle on an opposite end thereof to facilitate a user grasping the knob or handle and pulling the engage-disengage mechanism so as to disengage the blade-positioning unit from the respective spindle. This engage-disengage mechanism is advantageous in that it allows a user to quickly change/replace a blade assembly without the use of hand tools.
Advantageously, one of the bearings supporting the arbor is located on one end of the arbor and is arranged to be removable and replaceable to allow blade assemblies to be slid on and off the end of the arbor for changing the blade assemblies.
Advantageously, the blade-positioning mechanism is configured such that the spindles can be positioned substantially abutting each other on the arbor so as to achieve a minimum possible spacing distance between adjacent saw blades. As an example, the blades can be spaced as close as 2.5 inches apart, although the invention is not limited to any particular spacing distance.
The rail assembly in one embodiment comprises a first rail unit on which the blade-positioning units of the first group are slidable, and a second rail unit on which the blade-positioning units of the second group are slidable. Each rail unit can comprise a pair of spaced parallel rails received through respective spaced linear bearings defined in each of the blade-positioning units of the respective group.
The arbor can be of sufficient length to accommodate any desirable number of blade-positioning units and associated blade assemblies.
Advantageously, each of the blade-positioning units is coupled to its own absolute position encoder read head that travels adjacent to a linear scale attached to the respective linear motor for the purpose of positional feed back to each linear motor controller. Unlike the standard incremental encoders most commonly used (which require a startup homing procedure), the absolute position encoders provide instant positional data when the ripsaw is started from a powered-down condition. This feature greatly reduces machine startup time.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present invention now will be described more fully hereinafter with reference to the accompanying drawings in which some but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
The outfeed unit 130 is generally similar to the infeed unit, and includes an outfeed drive motor 132 connected through suitable drive arrangements to a bottom outfeed roll 134 and a top outfeed roll 136. The top outfeed roll 136 is arranged above the bottom outfeed roll 134 with a spacing distance between their peripheral roll surfaces, the spacing distance being approximately equal to the thickness of a board B being fed through the outfeed unit. The outfeed rolls 134 and 136 are driven by the outfeed drive motor 132 to rotate in opposite directions about their respective axes, thereby discharging a board B that has passed through the saw unit 120 of the machine. The outfeed unit includes provisions for adjusting the spacing distance between the outfeed rolls so as to accommodate boards of various thicknesses. Again, these provisions are not described herein.
The saw unit 120 is shown in isolation in
One exemplary construction of a spindle 140 is shown in
The saw unit 120 also includes a blade-positioning mechanism 160. The function of the blade-positioning mechanism 160 is to position the spindles 140 at any selected axial positions along the arbor 124, without requiring manual intervention by a person operating the ripsaw. The blade-positioning mechanism 160 is now described with reference to
Thus,
Affixed to a side of the carriage 172 facing away from the support plate 182 is a user-operable engage-disengage mechanism 190 having an axis extending perpendicular to the length directions of the rails 184 and perpendicular to the axis of the arbor. The engage-disengage mechanism 190 has an outer housing that is rigidly affixed to the carriage 172, and a slide portion that extends through a vertically extending passage defined through the outer housing. The slide portion has an upper end that projects up from the outer housing and has a knob or handle 192 affixed thereto, and has a lower end that projects down from the outer housing and defines a spindle-engaging portion 194. The knob 192 allows an operator to grasp and pull upward or push downward on the slide portion, thereby raising or lowering the spindle-engaging portion 194. The engage-disengage mechanism 190 can include a spring-loaded ball detent mechanism or the like to keep the slide portion in its lowered spindle-engaging position, such that manipulation of the detent mechanism is required in order to be able to raise the slide portion.
The spindle-engaging portion 194 of the engage-disengage mechanism is configured to be received in the engagement recess 148 of the spindle bushing 144 of the blade assembly 145 associated with the blade-positioning unit 170, as best seen in
With primary reference to
Each forcer 204 is connected, via a mounting bracket 206, to the carriage 172 of an associated one of the blade-positioning units 170. In this regard, the support plate 182 has a slot 183 extending along its length, and the mounting bracket 206 has a portion that passes through the slot 183 to connect to the carriage 172. Accordingly, as the forcer 204 is moved along the platen 202 by the linear motor's electronic controller (not shown), the blade-positioning unit 170 attached to the forcer 204 is moved along its rail unit 180.
The linear motor 200 also includes a linear encoder track 207 affixed to the platen 202 and extending parallel thereto. The mounting bracket 206 for each forcer 204 supports an absolute position encoder read head 208 for that forcer. Interaction between the encoder read head 208 and the encoder track 207 enables the linear motor's electronic controller to detect precisely where the encoder read head 208 (and, hence, the forcer 204) is located along the encoder track 207. The controller employs closed-loop control, based on signals from the encoder, to precisely position the forcer 204 at a desired location along the platen 202. Thus, each of the forcers 204, and hence their associated blade-positioning units 170, can be positioned as desired.
It will be understood that there are various linear motor technologies (e.g., brushless, brush-type, permanent magnet, induction, stepper-type, etc.) known in the art. In a preferred embodiment, each linear motor 200 comprises a brushless, cog-free linear motor in which the forcers 204 comprise primary coils and the platen 202 comprises a magnet track (secondary); however, any of the other technologies noted above can be used in embodiments of the present invention.
With reference to
Operation of the saw unit 120 and associated blade-positioning mechanism 160 is now explained with primary reference to
As an example, the ripsaw 100 can be equipped with a system of optical scanners (not shown) that scan an incoming board to determine its width, among other characteristics of the board. The ripsaw's controller can be programmed with logic to determine how to achieve an optimum yield from the board, given its detected width. The optimum yield may entail, for example, sawing the board into a determined number of equal-width boards, or it may entail sawing the board into a determined number of boards differing in width from one another. The controller commands the blade-positioning mechanism 160 to position the saw blades as needed in order to optimize the yield for each board fed into the ripsaw.
Boards can be fed into the ripsaw one after another, with a gap between them. An important advantage of the invention is that the time required to adjust the saw blades to new positions can be significantly shorter than has been possible with any other variably positionable ripsaw known to the inventors prior to the invention. This is due largely to the speed with which the linear motors 200 can move the blade-positioning units 170 and blade assemblies 145. As a result, when a blade position adjustment is needed between consecutive boards being fed into the ripsaw, the gap between the boards can be significantly reduced relative to what has been required with prior ripsaws.
The invention also enables blade assemblies 145 to be removed and replaced (e.g., if the blades become excessively worn, if a tooth breaks, if the blades are to be replaced by a different blade configuration, etc.) in a quick and simple manner. This is described with reference to
The arbor 124 can be designed to accommodate any number of blade assemblies 145. As illustrated in the drawings (see particularly
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. For example, the spindles 140 described herein have a construction in which the saw-mounting portion 142 rotates with the arbor while the spindle-bushing 144 does not rotate. This construction allows the spindle-engaging portion 194 of the engage-disengage mechanism 190 to be a simple fixed structure. Alternatively, however, it is within the scope of the invention to employ a simpler spindle construction in which the entire spindle rotates with the arbor and defines a circular track in which the spindle-engaging portion of the engage-disengage mechanism rides as the spindle rotates with the arbor. In this case, it may be necessary or desirable to construct the spindle-engaging portion to be rotatable, and/or it may be necessary or desirable to provide a low-friction coating on the circular track of the spindle and/or on the spindle-engaging portion. Accordingly, references herein to a blade-positioning unit 170 being engaged with a “spindle” will be understood to mean any suitable engagement that allows the saw-mounting portion of the spindle (whether the saw-mounting portion makes up only part of the spindle or all of the spindle) to rotate with the arbor while the blade-positioning unit is engaged with the spindle. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
