Peripheral chipper cutting bit holder

Abstract

A rotating chipping drum carrying a spiral row of bits is mounted in a hollow body with a portion of its periphery exposed to a chipping chamber for holding log sections to be chipped. Each bit includes side plate portions arranged at dihedral angles to a central plate portion and is clamped between bit-holding blocks received in apertures in the drum with the bit-cutting edge projecting beyond the periphery of the drum. The outer block is stationary and the inner block engages the cutting bit to press it against the outer block by a bolt extending through the outer block and screwed into a tapped aperture in the inner block.

Parent Case Text

This is a continuation of application Ser. No. 249,705, filed May 2, 1972, now abandoned. That application is a division of application Ser. No. 883,038, of Thomas W. Nicholson, Ray B. Jorgensen and Stanley Donald Vanek, filed Dec. 8, 1969, for Peripheral Chipper for Round Log Sections, which resulted in U.S. Pat. No. 3,661,192, issued May 9, 1972.

Description

A principal object of the invention is to provide a chipper which can chip small log sections and particularly very short log sections, such as wheels, which are difficult to hold for chipping by conventional chippers.

A further object is to provide a chipper which will enable small log sections of various sizes and shapes to be fed to it automatically.

Another object is to accomplish chipping of small log sections quickly and completely.

It is also an object of the present invention to provide such a chipper which will produce chips of substantially uniform size and shape, and such object can be accomplished by providing an arrangement of chipping bits which will effect overlapping cuts.

An additional object is to facilitate removal of chips from the interior of the chipper drum.

It is also an object to provide chip-cutting bits which can be held securely in the periphery of a chipping drum, yet which can be removed, sharpened and replaced quickly.

FIG. 1 is an end elevation of one form of chipper, and FIG. 2 is a side elevation of such chipper with parts broken away.

FIG. 3 is a transverse section through the chipper taken on line 3--3 of FIG. 2.

FIG. 4 is a plan of a portion of the chipping drum on an enlarged scale, and FIG. 5 is a section of such drum portion taken on line 5--5 of FIG. 4. FIG. 6 is a section through the same drum portion, taken along line 6--6 of FIG. 5. FIG. 7 is a further section taken on line 7--7 of FIG. 5. FIG. 8 is a top perspective of a cutting bit of the type shown in FIGS. 4, 5, 6 and 7.

FIG. 9 is a top perspective of an alternative type of cutting bit, and FIG. 10 is a fragmentary radial section through a portion of the chipper drum in which a bit of the type shown in FIG. 9 is mounted. FIG. 11 is a section on line 11--11 of FIG. 10. FIG. 12 is an exploded top perspective of the holding structure for a bit of the type shown in FIG. 9.

The chipper of the present invention is adapted for cutting small log sections into chips and for this purpose includes a hollow body 1 in which a chipping drum 2 is housed. Such drum is mounted for rotation on an axle 3 carrying a pulley 4 which can be rotated by one or more belts 5, shown in FIGS. 1 and 2, driven by a motor 6. Small log sections, and particularly those of short axial length such as the log wheel L shown in FIG. 2, can be delivered to the chipper by a supply conveyor 7.

The supply conveyor 7 will dump the log wheel L into the chipping chamber 8 in the upper portion of the hollow chipper body 1 in an attitude such that the axis of the log section extends generally parallel to the axis of the chipping drum. The axial extent of the log section is less than the corresponding width of the chipping chamber, as indicated in FIG. 2, in which the log section is shown in broken lines. Consequently, the periphery of the log wheel will substantially engage the periphery of the chipping drum. As shown in FIG. 2, the axle 3 may be tilted to incline the axis of the drum 2 so that movement of the drum periphery in contact with the periphery of the log wheel will tend to urge the log round to move down to the broken line position shown in FIG. 2 in which it is supported by the lower end wall of the chipping chamber, and consequently cannot tip over.

The chip-cutting bits 9 are arranged in a spiral row around the chipping drum 2, as shown best in FIG. 2. Adjacent bits are arranged in sufficiently overlapping relationship so that as the drum turns chips are cut from the log wheel in successive layers. As shown in FIG. 6, each bit overlaps circumferentially the major portion of the width of each adjacent bit in an axial direction.

As shown best in FIGS. 4 to 7 the cutting bits 9 are received in apertures in the periphery of the drum 2, and the cutting ends of the bits project outward beyond the periphery of the drum and are spaced from the adjacent walls of the apertures to provide passages through the circumferential drum wall for chips cut from a log section. Consequently, it is necessary to remove the chips from the interior of the drum. For this purpose chip-removing means are disposed within the drum which in the chipper shown in FIGS. 1, 2 and 3 is a chip-deflector plate 10, shown best in FIG. 3 as being inclined axially of the chipping drum for scooping the chips endwise out of the drum during its rotation. Such deflector plate is supported and positioned by struts 11 and 12 secured to the chipper body.

As shown best in FIG. 3, the left wall of the chipping chamber 8 toward which the periphery of drum 2 turns is disposed in convergent relationship to the adjacent portion of the drum periphery. Rotation of the drum in the direction indicated by the arrow tends to move the log section in the direction of rotation of the drum periphery and to press the log section against such wall. Continued rotation of the drum engaging one location of the log section will cut successive layers of such location into chips so that such location of the log section will become concave complemental in curvature to the curvature of the chipping drum periphery. As more layers are removed from the log section, such section will move farther into the angle between the converging chipping chamber wall and the chipping drum periphery. If the log section initially is round, it eventually will assume a crescent shape in cross section, as shown in broken lines in FIG. 3.

Because of the direction of rotation of the chipping drum and the effect of such direction of rotation on the movement of the log section, any chips and debris which do not pass through the apertures in the drum periphery will tend to accumulate in the angle between the converging chipping chamber wall and the drum periphery. If excessive material collects in such angle, it can be removed through an opening closed by an access door 13 pivotally mounted on the hollow body by a pivot 14 to swing between the solid-line closed position shown in FIG. 3 and open position.

The spiral path around the drum 2 in which the bits 9 are mounted is delineated by a spiral groove 24 in the drum wall and opening into the interior of the drum, as shown best in FIG. 5. The apertures 24' in the wall of the drum in which the bits are mounted are located in the bottom of this groove. The bits 9 are received in these apertures and extend through them at an angle to the drum periphery so that the cutting ends of the bits project outward beyond the drum wall, as shown best in FIGS. 5 and 7.

The cutting bits 9 are of dihedral cross section, including a first plate portion 25 and at least one other plate portion disposed at a dihedral angle to the first plate portion. In the cutting bit shown in FIG. 8 two planar side plate portions 26 are disposed in similar dihedral relationship to the central planar plate portion 25 between such side plate portions. One end of the central plate portion 25 is beveled to form a cutting edge 27, and the corresponding end portions of the side plate portions 26 have similar bevels 28 to form cutting edges. The central cutting edge portion formed by bevel 27 and the side cutting edge portions formed by bevels 28 are disposed in a plane which is substantially perpendicular to the central plate portion 25 and also to the side plate portions 26 of the cutting bit. When the cutting bits are mounted in the drum apertures as shown in FIG. 4, the side cutting edge portions are in advance of the central cutting edge portion in the direction of rotation because of the disposition of the cutting edge portions in a plane perpendicular to the plate portion 25 as stated above. Consequently a side cutting edge portion will slice into the wood to cut an end of an incipient chip at an angle ahead of the central cutting edge portion which cuts the portion parallel to the grain of the wood. The cutting action is therefore made smoother by such slicing action instead of being simply a simultaneous chopping impact of the entire cutting edge in cutting a particular chip.

In the bit 9 shown in FIG. 8 a deep notch 29 is provided in the butt end of the central plate portion 25 opposite its cutting edge end. When the bit is placed between an outer bit-holding block 30 and an inner bit-holding block 31, such notch will straddle a bolt 32 connecting the bit-holding blocks. In the construction shown in FIGS. 4, 5 and 6 such bolt extends through a shouldered aperture 33 in the outer bit-holding block 30 and is screwed into a threaded aperture in the inner bit-holding block 31.

The pair of bit-holding blocks 30 and 31 are of a size to fit into an aperture 24' in the drum periphery, and one of such blocks is anchored permanently in a drum aperture such as by being welded in place. In the bit installation shown in FIGS. 4, 5 and 6 the outer bit-holding block 30 is welded in the drum aperture, and the inner bit-holding block 31 can be pulled toward the outer block into clamping engagement with a bit 9 between such block, by tightening rotation of the bolt 32. Such structure facilitates construction of the assembly by enabling the blocks to be machined separately and then integrated with the drum by welding. By such permanent bonding it is assured that the block assembly cannot fall out of the drum, yet the cutting bit can be secured or released without removing the entire bit-clamping assembly and bit and without working inside the drum.

The underside of the outer block 30 and the outer side of the inner block 31 are of complemental shape conforming substantially to the cross-sectional shape of the bit 9. The outer surface of the inner block 31 has in it a recess 34 of a depth slightly less than the thickness of the bit. Consequently, when the bolt 32 is tightened with the bit received in such recess and with the notch 29 straddling the bolt, the bit will be clamped firmly between the blocks. In order to locate the blocks accurately relative to each other longitudinally, a key 35 is engaged in registering keyways in the inner end portions of the blocks.

In installing a bit 9 the key 35 is located in the keyway of inner block 31, and such block is inserted within the drum and the key engaged in the keyway of block 30. Then the bolt 32 is inserted through the aperture 33 in block 30 and screwed into the threaded aperture of block 31 to draw it outward. When the block 31 has been moved to a position close to block 30 while affording sufficient clearance between the blocks for reception of bit 9, the bit can be slid butt first through the aperture 24' between the blocks until it has been located with the desired degree of cutting end projection. The bolt 32 is then tightened to secure the bit firmly in this position.

While the bit 9, shown in FIGS. 4 to 8, has cutting edges at only one end, FIGS. 9 to 12 show a bit of similar cross-sectional shape but having cutting edges at both ends. If the cutting edges at one end should become dull the bits can simply be reversed end-for-end to present sharpened cutting edges 27' and 28' for engaging the log sections. Such a double-ended bit can be secured between the blocks 30 and 31 described in connection with FIGS. 4 to 7. It is preferred, however, that such a bit be mounted by the blocks 30' and 31', shown in FIGS. 10, 11 and 12.

In general the structure, mounting and function of the bit-clamping blocks 30' and 31' are similar to that of blocks 30 and 31. In this instance, however, the blocks 30' project farther beyond the periphery of the drum 2 to provide better backing for the projecting end portion of the bit 9'. The cutting edges 27 and 28 will still project beyond the end of block 30'. The opposite cutting edges 27' and 28' will be received in the cavity 34' at the outer side of bolt 32. The corners of the projecting portion of block 30' are chamfered, as shown best in FIG. 12, to avoid contact with the log wheel.

The inner block 31' is thicker than the block 31 to provide greater rigidity. Also, in place of the key 35 a fulcrum block 35' is secured to the underside of the outer block 30', such as by being welded, and such fulcrum block is thicker than the bit. Consequently, as the bolt 32 is tightened, the outer tip of block 31' will be pressed against the underside of the bit to concentrate the clamping pressure near the tip of the bit and provide clearance 34" between the inner block 31' and the inner end portion of the bit. Such block assembly clamps the bit more securely than the assembly of FIGS. 4 to 7.

Claims

We claim:

1. In a chipper, a hollow rotary cylindrical chipping drum including a plurality of bits having cutting edges projecting generally tangentially outward from its periphery, each of said bits being a bent plate including a central plate portion and two opposite side plate portions at dihedral angles to said central plate portion and having a cutting edge at an end including a central section and two side sections, said central plate portion and said side plate portions being of equal thickness, said three cutting edge sections being disposed substantially in a plane perpendicular to said central plate portion.

2. In a chipper, a hollow rotary chipping drum having a cylindrical shell with apertures extending through said shell and arranged in a spiral row around said shell, a plurality of bits received in said apertures of said shell, respectively, and having cutting edges projecting generally tangentially outward beyond the exterior of said shell, a pair of inner and outer bit-holding blocks received in each of said drum shell apertures and clamping therebetween the bit in its shell aperture, each of said outer blocks being permanently anchored to said drum shell, such as by being welded to said drum shell, and having an aperture therethrough, and means securing the corresponding inner block to said permanently anchored outer block and including a bolt extending through said outer block aperture, threadedly engaging said inner block and accessible from the outer side of said outer block for manipulation to enable said inner block to be moved relative to said permanently anchored outer block for releasing from said blocks a bit clamped between said blocks.

3. The chipper defined in claim 2, and a key engaged between the bit-holding blocks of each pair.

4. In a chipper, a hollow rotary cylindrical chipping drum including a plurality of bits having cutting edges projecting generally tangentially outward from its periphery, each of said bits being a bent plate having a cross section of substantially constant width and shape throughout the major portion of the length of said plate, each bit including a main plate portion and a side plate portion disposed at a dihedral angle which portions are of equal thickness, corresponding ends of said main plate portion and said side plate portion having cutting edges.