The present invention relates to a ring slicer having an easily removable knife and knife assembly, particularly for use in slicing or flaking logs, refuse lumber, chips, or other articles of wood in a lumber mill.
Ring slicers, also termed ring flakers or stranders, are generally used in manufacturing facilities for manufacturing particle board, oriented strand board, and fiberboard such as MDF. They convert logs, refuse lumber, chips, or other articles of wood into flakes, wafers or strands for the manufactured board products. The ring slicer includes a cylindrical ring assembly for revolution about an axis of rotation. The ring assembly typically includes a large number of elongate knife assemblies, commonly 49 but which may be as many as 72. The knife assemblies support elongate knives having cutting edges extending parallel to the axis of rotation captured between annular end plates. The ring assembly rotates within a chamber into which pieces of wood to be cut or chipped are introduced.
The knives are subject to wear from the wood, and in addition rocks, metal objects and other hard foreign material carried by or with the wood also wear the knives, and may damage or break the knives as well as the knife assemblies. Accordingly, it is routinely required to remove the knives to repair or replace them, or to turn them to expose fresh cutting edges. Moreover, it is episodically required to remove and replace some or all of the knives, the knife assemblies, or both, as a result of “crashes” of the ring slicer apparatus. The machine downtime and the labor required to effect maintenance and repair are costly and desirably kept to a bare minimum.
As described in U.S. Pat. No. 5,313,696, the knives may be mounted to a portable knife assembly that slides radially into slots in the end plates of the ring assembly. Once in place, bolts are inserted through holes in the end plates into threaded holes in the knife assembly to hold the knife assembly in place. In turn, the knife is similarly mounted to the knife assembly with bolts extending through holes in the knife into threaded holes in the knife assembly.
One problem with this approach is that the bolt holes require a tolerance that permits the knife or knife assemblies to move or creep within the ring assembly and thereby to become misaligned or to loosen as a result of the large cutting forces encountered during operation. Moreover, removing the knife from the ring slicer requires both removing the knife assembly from the ring assembly and removing the knife from the knife assembly.
To hold the knife assembly more securely to the ring assembly, the knife assembly may be provided with protruding keys that extend axially into corresponding keyholes in the end plates. The keys and keyholes can be provided with a minimal tolerance of fit that maintains the positional integrity of the knife assembly. However, a major disadvantage of this approach is that the knife assemblies may no longer be simply slid radially away from the ring assembly for maintenance or repair. Rather, the end plates must be axially spaced apart a sufficient amount to permit the projecting keys to clear the end plates, requiring that the entirety of at least one end plate be decoupled from all of the knife assemblies.
It is often necessary to remove a knife from the knife assembly under conditions where it is not otherwise necessary to remove the knife assembly from the ring assembly. U.S. Pat. No. 5,937,923 addresses this problem by providing a clamp for the knife that is biased outwardly by springs disposed in spring holes in the knife assembly, for unclamping the knife without requiring removal of the clamping bolts.
A disadvantage of the mechanism is that it requires the clamp to move radially, and while a necessary indexing of the clamp is provided to seat the clamp into proper position when it is tightened, this is provided in the form of sliding surfaces that wear over time so that the position of the clamp and, therefore, the knife are permitted to wander. Another disadvantage of the mechanism is that it is difficult to remove cut wood fibers introduced into the spring holes when the clamp is loosened. It is yet another disadvantage of the mechanism that the spring forces produced by the multiple compression springs must be well matched to prevent binding of the clamp.
Accordingly, there is a need for a ring slicer having an easily removable knife and knife assembly that provides for positive maintenance of the position of the knife in the ring slicer as well as easy removal of the knife and knife assembly therefrom.
The invention disclosed herein is a ring slicer having an easily removable knife and knife assembly. According to one aspect of the invention, there is an assembly for clamping a knife, the knife having two sides, the assembly comprising a base and a clamp for clamping the knife to the base. The clamp includes an upper clamping member for mounting to the base so that a portion of the upper clamping member is cantilevered from the base. The upper clamping member includes provision for at least one bolt extending through the portion into the base such that tightening the bolt elastically deflects the upper clamping member against one side of the knife.
According to another aspect of the invention, there is an assembly for clamping a knife, comprising a base and a clamp. The clamp includes an upper clamping member for mounting to the base and a wearshoe for separately mounting to the base. The clamp is adapted for clamping the knife between the upper clamping member and the wearshoe. The wearshoe and the base include cooperatively interlocking portions adapted to resist relative motion between the wearshoe and the base in a first direction. Alternatively or in addition, the wearshoe and the base include cooperatively ramping portions adapted to resist relative motion between the wearshoe and the base in one direction.
According to yet another aspect of the invention, there is an apparatus for cutting an article of wood, comprising a ring assembly and a plurality of knife assemblies. The ring assembly comprises two end plates for rotation about an axis of rotation. Each of the knife assemblies comprises an elongate knife having a cutting edge extending along an elongate axis, a base, and a clamp for clamping the knife to the base. The knife assemblies are adapted for installation between the end plates such that the shoulder portions of at least two shoulder bolts extend through one of the end plates into the base. Preferably the knife has dual cutting edges.
Referring to
The ring slicer 12 is particularly adapted to manufacture particle board; however, with suitable adaptation the ring slicer may be used to manufacture oriented strand board as well. While either of these are preferred contexts for the present invention, the principles of the invention may be applied to any cutting apparatus, particularly any cutting apparatus for processing articles of wood.
Turning to
To remove the knife 23 from the knife assembly 16 when it is installed between the rings 18 requires complete removal of all of the bolts 15a of the knife assembly. To remove the knife assembly 16 from the ring assembly 10 requires removing the bolts 15b, and moving the rings 18 axially far enough apart so that the projecting keys 27 clear the inside faces 29 of the rings 18 so that the knife assembly can be slid outwardly from the ring assembly. This latter step requires at least loosening and typically completely removing the bolts 15b for every knife assembly in the ring assembly. Where there are typically 49 or as many as 72 knife assemblies in the ring assembly, this is an objectionably laborious and time consuming process.
Turning to
The ring assembly 30 includes two end plates 32a, 32b which are preferably but not necessarily annular in shape. Captured between the two end plates 32 are a plurality of individual knife assemblies 34. There are typically 49 knife assemblies, but the number of knife assemblies may vary considerably. For example, ring slicers are available with as few as 32 knife assemblies and as many as 72 knife assemblies.
The knife 36 is clamped to the base 40 by the clamp 38. Particularly, the knife is held between the upper clamping member 38a and the wearshoe 38b. The upper clamping member is bolted to the base 40 by use of a bolt 45a, and the wearshoe is bolted to the base by use of a bolt 45b (
Particularly, the base has a raised support portion 42 (
Preferably, there is about a 0.004″ to 0.008″ clearance between the upper clamping member 38 and the knife when the clamp bolt 45c is fully loosened and, therefore, the upper clamping member 38 is in its relaxed, undeflected, state. Multiple instances of the clamp bolt 45c are preferably provided such as shown in
The wearshoe 38b and the base 40 advantageously include cooperatively interlocking portions 41 and 43 respectively, that function to index, strengthen and secure the attachment of the wearshoe to the base. Particularly, the interlocking portions 41 and 43 prevent movement of the wearshoe with respect to the base in the direction indicated as “A,” and thereby ensure that the distance “d” is and remains fixed.
Referring to
Preferably, slots 44 corresponding to a particular knife assembly 34 are provided on both end plates 32a and 32b (
Turning to another aspect of the invention,
In the ring assembly 30, the dowel pins are ordinarily positioned to extend from the dowel holes, into or through the plates 32, to locate the base 40 to the plates 32. However, to remove the knife assembly 34 from the ring assembly, the dowel pins on at least one end of the knife assembly may be pressed or punched into the dowel holes so that the knife assembly is free to slide radially out of the ring assembly. It is an outstanding advantage of the ring assembly 30 that the knife assembly can be removed from the ring assembly simply by removing the bolts 45d and pressing or punching the dowel pins on at least one end of the knife assembly into their respective dowel holes.
The wearshoe 62b and the base 64 advantageously include cooperatively interlocking portions 71 and 73 respectively, that function to index, strengthen and secure the attachment of the wearshoe to the base. Particularly, the interlocking portions 71 and 73 prevent movement of the wearshoe with respect to the base in the direction indicated as “A.” The cooperatively interlocking portions are preferably angled at an angle φ of about 45-60 degrees defined as shown.
In addition, the wearshoe and base include cooperatively ramping portions 75 and 77 respectively, that function to further prevent movement of the wearshoe relative to the base. Particularly, the ramping portions are oriented at an angle θ defined relative to the longitudinal axes “LA” of bolts 74 and 76 that secure the wearshoe to the base; particularly with respect to the perpendicular to these axes which in the embodiment shown is parallel to the direction “A.” The angle θ is positive (defined as shown) and shallow, preferably about 5 degrees. In response to the force exerted by the bolts, the positively angled ramping portions tend to prevent movement of the wearshoe with respect to the base in the direction perpendicular to the axes “LA”, which is indicated as “B.”
Turning back to
The holes 66 and 68 provide a close tolerance clearance fit, e.g., 0.002″, to shoulder portions 70a and 72a of the shoulder bolts, for aligning the knife assembly to the ring assembly. The holes 66 and 68 terminate in threaded portions (not shown) that receive the corresponding threaded portions 70b and 72b of the shoulder bolts, for bolting the knife assembly to the ring assembly. Head portions 70c and 72c of the shoulder bolts are preferably received by and seat in counterbored holes 80 in the ring 18a, though this not essential.
Each shoulder bolt provides the advantage of both aligning and attaching the knife assembly to the ring assembly. The two (or more) shoulder bolts together provide a greater degree of alignment and strength with less installation effort than prior art attaching means comprising separate alignment pins and bolts. While the shoulder bolts are shown for use with the knife assembly 60, they may be used in place of the dowel pins of the knife assembly 10 as well, and may be used to equal advantage in other alternative knife assemblies.
It is to be recognized that, while a particular ring slicer having an easily removable knife and knife assembly has been shown and described as preferred, other configurations and methods could be utilized, in addition to those already mentioned, without departing from the principles of the invention.
The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions to exclude equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
This is a continuation-in-part of U.S. No. 10/280,278, filed Oct. 25, 2002, now U.S. Pat. No. 6,757,952.
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Number | Date | Country | |
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20040168745 A1 | Sep 2004 | US |
Number | Date | Country | |
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Parent | 10280278 | Oct 2002 | US |
Child | 10789268 | US |