Modular conical chipper/canter head and method

FIELD OF THE INVENTION

The present invention relates to a conical chipper/canter head, such as is typically employed for cutting and chipping logs in a sawmill, for processing the logs into lumber for use in construction.

BACKGROUND

In sawmills, logs are cut into slab sided articles of wood in the process of converting the logs into useable lumber. For this purpose, the log is fed into a device referred to as a chipper or canter (hereinafter “chipper/canter”). The chipper/canter has a rotating cutting head incorporating a plurality of cutting members, typically removable knives, saws, or combinations thereof. The cutting head is variously referred to as a chipper head, canter head, slabbing head, or conical head. The term “chipper” refers to one function of the chipper/canter, i.e., to produce chips that are used to form other wood products, such as pulp, paper, and particle board. The term “canter” refers to another function of the chipper/canter, i.e., to cut a piece from the log, referred to as a “cant,” having at least two parallel, substantially flat or slab sides, and the term “slabbing” refers to producing one or more of these sides. All of these heads are termed “conical” heads due to their geometry; the cutting surface defined by rotation of the head is actually frustoconical in shape.

The cutting head rotates about its axis of symmetry and the log is translated toward the head in a direction that is aligned with the longitudinal axis of the log and perpendicular to the axis of rotation of the head, causing the log to interfere with the cutting surface of the head and thereby cutting the log to produce elongate, slab sided articles of wood, and chips.

There are typically two opposed cutting heads operating on the log at substantially the same time to produce, during one pass of the log, two sided cants, and often there are four cutting heads for producing four sided cants from the log in a single cutting operation.

As the cutting surface defined by the rotating conical cutting head is actually frustoconical, it includes a flat annular portion as well as a conical portion that flares outwardly from the annular portion. The plane of the annular portion of this cutting surface is in the plane of the slab sides of the articles of wood and produces a finish on these sides. However, the log first encounters the conical portion of the cutting surface of the rotating cutting head, which cuts and tears chips from the log in preparation for the finishing provided by the annular portion as translation of the log in the direction just indicated is continued.

The annular portion of the cutting surface defined by the rotating conical cutting head is typically produced either by a plurality of circumferentially spaced knives, or a disk-saw. Any such structure is referred to hereinafter as a “facing” portion of the cutting head because it produces a “facing” cut on the log that defines the slab sides of the lumber.

The conical portion of the cutting surface is typically produced by a plurality of staggered knives that are often arranged in spaced apart circular patterns, or alternatively in a spiral pattern, so as to trace a frustoconical surface as the head rotates. Any such structure is referred to hereinafter as a “chipping” portion of the cutting head because it cuts chips from the log.

It will be appreciated that a significant volume of the log must be removed as chips because the log is roughly circular and the lumber produced therefrom is rectilinear. So the chips are a waste product of the conversion of the log to lumber, but they are at the same time useful as constituents of manufactured wood products. They are particularly useful where their dimensions are controlled, and a dimensional parameter of the chip that is particularly important to control is the chip length.

The knives of the chipping portion are attached to a body of the head either directly or through intermediate members, and the body of the head may or may not itself be essentially frustoconical in shape. The body is often referred to in the art as “solid.”

FIG. 1 shows schematically a log 2 being processed, i.e., cut, chipped, or sawn into lumber by a pair of opposed chipper/canter cutting heads rotating about an axis of rotation “L.” Each cutting head includes chipping knives having cutting edges that define a chip cutting surface indicated as 3, and facing knives, or alternatively saw teeth, having cutting edges that define a face cutting surface indicated as 4. The cutting heads establish a depth of cut “d” between the slab sided faces “f” of the cut lumber, the location being indicated with a reference line “REF,” and the original, curved outer surface “s” of the log.

To adjust the depth of cut, the heads are moved in and out, i.e., axially, in the direction of the arrows, in the direction of the axis of rotation L.

FIG. 2 shows a prior art cutting head 5 in isometric view, and FIG. 3 shows the same head looking down the axis “L,” in the plane of head rotation. The conical chip cutting surface is 6 and the annular facing surface is 7. The chip cutting surface is defined by chipping knives 8, namely 8a and 8b, having cutting edges 9. The knives 8 are separated by an angular distance θ, and the head rotates at an angular velocity ω. Also shown is the log 2 about to be fed into the cutting head at a feed speed “v.”

The chip length is the distance the log travels in the time that the head turns sufficiently to move a knife (e.g., 8b) into the same position that a preceding knife (e.g., 8a) was in. Thus the chip length is equal to v·θ/ω.

A “limiter” structure 10 is typically provided between adjacent knives 8. The limiter has an outer surface (hereinafter “limiting surface”) 10a that limits radial movement of the log, holding the log in place, to prevent or at least minimize surging and bucking. The limiting surface is, overall, at a somewhat lower radial elevation “r” than that of the adjacent knives, and in addition its radial elevation smoothly curvilinearly decreases over the angular distance between the adjacent knives from its elevation proximate the first knife to contact the wood, e.g., the knife 8a, to the next knife, e.g., the knife 8b. This change in radial elevation of the limiter surface is best seen in FIG. 4 (compare the radial elevations “r₁” and “r₂”) showing the limiter surface by itself.

The amount of overall elevation drop, or “relief,” provided for the limiting surfaces relative to the knife cutting edges is dictated by the same parameters that determine chip length. Therefore, adjusting the chip length requires changing this elevation. More particularly, decreasing the chip length, e.g., by decreasing the log feed speed or by increasing the angular velocity of the cutting head, requires increasing the radial elevation of the limiting surfaces, to move the limiting surfaces closer to the elevation of the cutting edges of the chipping knives.

The shape of the curve defining how the elevation of the limiting surfaces drops in-between adjacent knives is also dictated by the same parameters that determine chip length.

The limiter 10 as shown in FIGS. 2-4 is formed in a continuous ring which is not typical, though it best illustrates the aforementioned elevation variation. However, typically, the limiting surface is provided as discrete, modular limiter elements that are individually mounted between the associated chipping knives. In that case, adjustments require dismounting, repositioning or replacing, and finally re-mounting the limiter elements. As there are typically a number of the limiter elements, this is a time consuming procedure. While the continuous ring eliminates the need to individually adjust or replace a number of limiter elements to adjust chip length, the adjustment requires replacing the ring. Since there may be a number of different chip length adjustments required, this exacts a penalty in the cost and inconvenience of obtaining, storing, and maintaining a number of different rings.

Accordingly, an improved chipper/canter head of modular design according to the present invention provides for quicker and easier adjustment of chip length, as well as other advantages.

SUMMARY

A modular conical chipper/canter head and method is disclosed herein. A preferred method is described for adjusting the head to accommodate a change in chip length. The method includes the steps of providing an annular facing module, providing a conical, solid hub module for mounting one or more chipping knives, and at least one of (a) installing one or more control plates between the facing module and the hub module, and (b) removing the one or more control plates from between the facing module and the hub module, for spacing the facing and hub modules apart a selected amount.

A preferred modular chipper/canter head includes an annular facing module and a conical, solid hub module for mounting one or more chipping knives. The facing module includes one or more limiters providing a limiting surface corresponding to the one or more chipping knives. The limiting surface intersects a plane which is perpendicular to the axis of rotation of the cutting head and which also intersects the one or more chipping knives. The facing module and the hub module are adapted to be detachably mounted to each other. Preferably, one or more control plates are utilized for spacing the facing module and the hub module apart.

It is to be understood that this summary is provided as a means of generally determining what follows in the drawings and detailed description and is not intended to limit the scope of the invention. Objects, features and advantages of the invention will be readily understood upon consideration of the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view a log being processed into lumber by a generalized pair of opposed chipper/canter cutting heads.

FIG. 2 is an isometric view of a prior art cutting head.

FIG. 3 is a front view of the cutting head of FIG. 2.

FIG. 4 is a front view of a limiter portion of the cutting head of FIG. 2, shown removed from the cutting head.

FIG. 5 is a schematic isometric view of a wood cutting system in which four instances of a modular conical chipper/canter head according to the present invention are provided for chipping and facing a log.

FIG. 6 is a schematic isometric view of one of the cutting heads of FIG. 5 chipping and facing the log.

FIG. 7 is an exploded isometric view of a preferred modular conical chipper/canter head according to the present invention.

FIG. 8 is schematic plan view of a single modular chipper/canter head according to the present invention chipping and facing a log.

FIG. 9 is a schematic, plan view of the cutting head of FIG. 8 showing a first relative axial position of faceplate and hub according to the present invention.

FIG. 10 is a schematic, plan view like FIG. 9 showing a second relative axial position of the faceplate and hub.

FIG. 11 is an isometric view of a preferred embodiment of the modular chipper/canter head with a faceplate and hub in a relative axial position corresponding to that shown in FIG. 9.

FIG. 12 is an isometric view of the modular chipper/canter head of FIG. 11 with the faceplate and hub in a relative axial position corresponding to that shown in FIG. 10.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made in detail to specific preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.

FIG. 5 shows a wood cutting system 18 in which one or more instances of a modular conical chipper/canter cutting head 20 (“cutting head”) according to the present invention may be used, four orthonormally disposed cutting heads 20 being indicated as would be typical. The system 18 would typically be provided in a sawmill for cutting raw logs, such as the log 2, and and processing the logs into lumber. However, it should be understood that while the cutting head 20 would typically be used for cutting lumber from logs, the cutting head 20 may be used to cut substantially plane surfaces from any other material or object desired.

The system 18 has an in-feed table 15 for supporting the log 2, which travels horizontally on the table. As a result of rotation of the cutting heads 20 about respective axes of rotation “R,” (the directions shown are arbitrary), in conjunction with travel of the log 2 relative to the cutting heads in a direction “T” aligned with the elongate axis of the log, each cutting head cuts a corresponding planar surface on the log.

FIG. 6 shows a log as it is being cut by one of the heads 20. The cutting head 20 has a facing portion 20a and a chipping portion 20b. The facing portion 20a produces facing cuts on the log in the region “A” to produce the substantially planar facing surface “S_F,” and the chipping portion 20b cuts chips from the log in the region “B,” which produces a relatively rough, substantially conically shaped chipped surface “S_CH.”

FIG. 7 shows the preferred cutting head 20 exploded for clarity. The cutting head 20 is modular in that the facing portion 20a is provided as a unit, the chipping portion 20b is provided as a separate unit. The two units, or modules, are removably mounted together, such as by the use of mounting bolts 21, to provide a complete conical cutting head. However, it would be possible to use each of the modules 20a and 20b alone, since they are detachable and provide separate functions. The chipping portion 20b will be referred to hereinafter as a “hub” using industry parlance, and would be further classified in the industry as being “conical,” and “solid.”

The hub 20b includes a plurality of chipping knives 14, though it should be understood that a single knife could in principle be used. Each knife is clamped by one or more removably mounted clamping members 19 to the hub. The clamping members typically comprise upper and lower portions for clamping the knives 14 between the upper and lower portions, but clamping members may be single portions that clamp the knives directly to the hub 20b. Discussion of the details of the clamping members is omitted as such clamps are well known in the art, and any known clamping methodology could be used. The hub includes holes 22 for receiving the mounting bolts 21.

The facing portion 20a will be referred to hereinafter as a “faceplate.” The faceplate is substantially annular, as contrasted with the substantially frustoconical configuration of the hub 20b. Neither the terms “annular” nor “conical” are intended to be strictly construed.

The faceplate 20a preferably includes a plurality of facing knives 30, each clamped by a corresponding one or more clamping members 29 to the faceplate, though it should be understood that a single facing knife, or a saw-blade or plurality of saw-blade segments, could be used. As for the clamping members 19 of the hub 20b, the clamping members typically comprise upper and lower portions for clamping the knives 30 between the upper and lower portions, but clamping members may be single portions that clamp the knives directly to the hub 20a. The faceplate includes holes 23 for receiving the mounting bolts 21.

The faceplate 20a further includes one or more limiting structures (together hereinafter “limiter”) 32. The limiter 32 defines a limiting surface 32a that is associated with each chipping knife 14 of the hub 20b. The limiting surface 32a establishes a limit on the radial movement of the log as mentioned above.

It will be understood that, where there are a plurality of chipping knives as is standard practice, the limiting surface or a portion thereof is disposed angularly between adjacent chipping knives as shown.

The limiter 32 is preferably provided integrally with the faceplate 20a as shown, but it may be separately removably attached to the faceplate, e.g., by bolts, or it may be provided, either integrally with or removably attached to, segments which themselves may be removably attached to the faceplate. In any case, it is an outstanding feature of the invention that all of the facing knives 30, as well as the limiter 32, may be removed from the hub 20b together as a modular unit, simply by removing the mounting bolts 21.

Moreover, one or more “control plates” 40 are preferably provided according to the invention. A control plate is generally a spacing element that is specially adapted for spacing two particular parts relative to each other a selected, controlled amount. It will have at least two holes for receiving bolts used to mount the parts together and is therefore installed or removed into or from a position between the parts by dismounting the parts. The control plate has a thickness in the range 0.040″ to 0.250,″ and more preferably in the range 0.060″-0.125″. Since the control plate is used in a manufacturing environment, it should be sturdy enough to withstand ordinary abuse without deforming or tearing, and it is believed that if provided to be at least 0.040″ thick, and preferably at least 0.060″ thick, this objective will be met. The thickness of different control plates used for spacing the same parts may vary within the defined ranges.

FIG. 7 shows a control plate 33 for installation between the clamping members 29 and the faceplate 20a to adjust the axial position of the facing knives, and therefore the position of the facing cut.

The ability to remove the faceplate 20a as a unit from the hub 20b provides the capability to use one or more of the control plates 40 to advantage. The control plates allow adjustment, in discrete increments, of the axial position of the faceplate relative to the hub 20b. Providing for this, the control plates 40 have holes 24 corresponding to the holes 23 of the faceplate 20a and the holes 22 of the hub 20b, for receiving the bolts 21.

Axial adjustment of the faceplate relative to the hub axially adjusts the limiter 32, which is carried by the faceplate, relative to the chipping knives 14, which are carried by the hub. The present inventor has recognized that this effectively provides for radial elevation adjustment of the limiter 32, enabling quick and easy adjustment of the limiting surface for changes in chip length.

FIG. 8 shows, schematically, one cutting head 20 cutting a log 2. The log is fed in the direction “A1” and the cutting head turns about axis L, perpendicular to A1. The cutting head 20 is shown with the faceplate 20a and hub 20b. The hub 20b carries a chipping knife 14 having a cutting edge 14a. The cutting edge 34a forms the chipped surface S_CH.

FIG. 9 shows, schematically, the upper half of the cutting head 20 as it is seen in FIG. 8. The faceplate 20a and the hub 20b carry respective limiters, referenced as 32 and 36, respectively. The limiters have their ordinary functions; however, the limiter 36 of the hub is not considered, for purposes herein, particularly important, because the depth of cut is typically such that the limiter 36 does not come into contact with the log. The limiter 32 has an outer, limiting surface 32a which establishes a limit on the radial movement of the log as mentioned above.

A reference line “REF” is shown that indicates the location of the face cutting surface of the cutting head. The same reference line is shown in FIG. 1. Also, a plane “P” is shown in side elevation that intersects both the chipping knife 14 and the limiting surface 35a.

FIG. 10 shows the same half-section of the cutting head 20 as shown in FIG. 9, with a control plate 40 inserted between the faceplate 20a and the hub 20b. Relative to the reference line REF, the hub 20b must move back, away from the face cutting surface, in the direction “A2” by an amount equal to the thickness of the control plate. To provide for this movement, the cutting head is caused to be axially repositioned as if a depth of cut adjustment is being made. To compensate for this movement, the knife 14 is also slid toward the reference line REF so that it retains its original axial position relative to the reference line, as can be seen by comparing FIGS. 9 and 10.

Still comparing FIGS. 9 and 10, it can be seen that there is a gap “g,” namely “g₁” (FIG. 9) and “g₂” (FIG. 10), between the cutting edge 14a of the chipping knife and the limiter 35, and that the gap has been decreased as a result of installation of the control plate 40. This difference in the gap g is effectively a change in the radial elevation r of the limiting surface provided by the limiter 32 relative to the chipping knives, and is appropriate for adjusting the limiting surface for a decrease in chip length even though the limiting surface has not moved relative to either the reference line REF or the axis of rotation L. To adjust the limiting surface for increasing chip length, i.e., to increase the gap g, one or more control plates that have already been installed can be removed.

FIGS. 11 and 12 show the cutting head of FIG. 7 in two states of adjustment by use of the control plates 40, FIG. 11 corresponding to FIG. 9 and FIG. 12 corresponding to FIG. 10. FIG. 11 shows the faceplate 20a closely spaced to the hub 20b, which provides a wide gap g such as the value g₁in FIG. 10. FIG. 12 shows the faceplate spaced out farther from the hub, which narrows the gap to the value g₂of FIG. 10.

The relatively close spacing shown in FIG. 12 between the limiter 35 of the faceplate 20a and the limiter 36 of the hub 20b, resulting from the use of fewer control plates, having the larger gap g₁between the limiting surface 35a and the cutting edge 14a shown schematically in FIG. 7, and FIG. 10 corresponds to the smaller gap g₂shown in FIG. 8.

The above-described mechanism for adjusting the limiting surface is simple, because it requires a minimum of manipulations of the cutting head, and it is economical because it does not require the purchase, storage and replacement of expensive or heavy parts. It therefore allows for quick and easy adjustment of chip length. Modular chipper/canter heads according to the present invention may be employed with any prior art chipping knife, and any prior art facing knife or saw.

It is to be understood that, while a specific modular conical chipper/canter head 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. It should be understood that there is no intention to indicate, in describing particular features in a particular combination, that all of the features must be present together in that combination to be in accordance with the invention. Rather, it should be understood that features may be omitted from the combinations shown to the extent that the remaining features having the relationships described herein are deemed useful.

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.

Modular conical chipper/canter head and method

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