US3749323A

US3749323A - Method and apparatus for forming pulpwood chips

Info

Publication number: US3749323A
Application number: US00192037A
Authority: US
Inventors: J Keating
Original assignee: Rader Companies Inc
Current assignee: Beloit Corp
Priority date: 1971-10-26
Filing date: 1971-10-26
Publication date: 1973-07-31
Anticipated expiration: 1990-07-31

Abstract

A wood chipper has a guiding tunnel from a rotating chipper disc to a fanwheel spaced from the disc for guiding chips into the path of blades of the fanwheel in substantial parallelism with the path of the blades and at a velocity not greatly different from that of the blades.

Description

United States Patent [191 Keating I 1 July 31, 1973 [54] METHOD AND APPARATUS FOR FORMING 3,661,329 5/1972 Smith 244/176 X PULPWOOD CHIPS 3,635,410 l/l972 Smith 3,384,311 5/1968 Eklund et al. 144/176 X [75] Inventor: James L. Keatlng, Milwaukie, Oreg.

73 Assi nee: R derC l l P l d l 1 8 ot g on an Primary Eqqminer-Donald R. Schran Attorney-Stephen W. Blore, Kenneth S. Klarquist [22] Filed: Oct. 26, 1971 et a1.

[21] Appl. No.: 192,037

[57] ABSTRACT [52] US. Cl 241/28, 144/176, 241/56,

8 R A wood chipper has a guiding tunnel from a rotating [51] Int. Cl B271 11/02 chi er disc to a fanwheel spaced from the disc for [58] Field of Search 144/176, 162 R; guiding chips into the path of blades of the fanwhee i 241/56, 51, 278 R, 92, 28 substantial parallelism with the path of the blades and at a velocity not greatly different from that of the [56] References Clted blades.

UNITED STATES PATENTS Smith 241/56 9 Claims, 4 Drawing Flgures PAIENIEB M 3.749.323

SHEET 1 OF 2 JAMES L. KEATING INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS PATENIED m3] ms SHEET 2 0F 2 FIG. 2

JAMES L. KEATING INVENTOR BUCKHCRN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS METHOD AND APPARATUS FOR FORMING PULPWOOI) CIIIPS BACKGROUND OF THE INVENTION In the making of paper pulp from wood, and particularly in utilizing a chemical pulping process, it is desirable that the wood chips be uniform in size both in width and length as well as in thickness, and that the chips have a minimum content of slivers or pins and sawdust-like particles that will pass, for example, a three-eighth inch screen.

To obtain wood chips of the desired size it is conventional practice to pass logs or wood scraps through a chipper which comprises a massive rotating disc having radially extending knives arranged to cut off the ends of the wood or logs fed into the chipper so that chips of predetermined length are formed. The disc on which the knives are mounted is provided with passageways so that the severed chips may pass to the rear of the disc. For practical reasons chippers are constructed so that the knives impact upon the log or wood as the knives are rotating substantially downwardly. The chips will have high velocity imparted to them by reason of the impact of the knife upon the wood being cut and their trajectory will be in a generally downward and rearward direction. Chippers are in two general classes with respect to their discharge, namely bottom discharge and top discharge, the terms being descriptive of the location at which chips are taken from the chipper housing. In a top discharge chipper it is necessary to change the direction of the chips from their general downward direction and cause them to be moved upwardly and through the outlet at the top of the housing. Such change of direction is generally done by placing blades upon the back and periphery of the cutter disc for engaging and propelling the chips. The geometry of prior chippers has been such that the blades have engaged the chips at a relatively high differential velocity with substantial damage to the chips and production of large amounts of slivers and pins and sawdust-like particles. In addition to their impingement upon the blades, the prior chippers have presented surfaces such as the fanwheel itself, for example, against which the chips can impact at a high velocity and at a large incidence angle resulting in further breakage of the chips.'

BRIEF DESCRIPTION OF THE INVENTION It is an object of the present invention to provide a configuration for a top discharge chipper wherein the chips are introduced into a discharge air stream substantially in parallel to the air stream.

The chipper of the invention comprises a rotary cutter disc with the usual substantially radial knives for cutting chips from a log or wood pieces fed to the disc. Mounted rearwardly of the cutter disc is a fanwheel having impeller blades on the periphery for engaging and propelling chips. The cutter disc and fanwheel are surrounded by suitable housing means enclosing and providing protection of each, the housing portion about said fanwheel forming a centrifugal fan with the fanwheel and having a chip discharge opening in the top. The housing means has a funnel-like tunnel for intercepting and gathering the chips from the chipper and directing the chips into the blade path of the fanwheel in near parallelism with the blade path.

In the drawings:

FIG. 1 is a perspective view of a chipper constructed in accordance with the invention;

FIG. 2 is a horizontal section taken substantially along line 2-2 of FIG. 1;

FIG. 3 is an enlarged fragmentary elevation of a chipper taken substantially along line 33 of FIG. 2; and,

FIG. 4 is a schematic view of the chipper of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION The illustrated chipper comprises a chipper disc 12 mounted on a horizontal shaft 14 driven from a suitable motor (not shown). The shaft 14 is shown as supported in trunnions 16 mounted on a suitable supporting base 18 and is otherwise suitably supported. The illustrated chipper is of the horizontal infeed type and is illustrated as having an infeed spout 20 extending through an opening 22 in the base 18. As will be apparent, the invention is equally applicable to chippers having a vertically inclined feed spout.

The cutter disc I2 is enclosed within a protective coaxial housing 24, the front wall 26 of which is provided with an opening 28 communicating with the spout 20. One wall of the opening 28 defines a vertical anvil 30 and the bottom edge defines a horizontal anvil 32 against which a log or board 33 is pressed as it is engaged by the knives on the cutter disc.

The chipper disc 12 may be of any conventional construction and is provided with a plurality of removably mounted knives 36 which project from the front face thereof, the disc having openings or slots 38 adjacent to each of the knives through which severed chips may pass from the front to the back of the disc 12. The knives 36 of the illustrated chipper are offset from but parallel to radii of the disc 12, but, as will be apparent, the invention is equally applicable to chippers using the more conventional arrangement wherein the knife edges extend along radii of the disc.

Mounted on the shaft 14 rearwardly of the disc I2 with respect to the position of the spout 20 is a fanwheel 40 provided with a plurality of impeller blades 46. The fanwheel 40 is surrounded by a housing 42 defining a scroll case having a tangential outlet 44 at the top thereof. Extending between and communicating with the disc housing 24 and the fanwheel housing 42 is a guide or tunnel which intercepts, gathers and directs the chips from the cutter disc 12 into the housing 42 in substantial parallelism with the path of the blades 46, which is the path of the air stream created by the blades.

The tunnel 50 has a bottomwall or surface 52 to receive and direct the chips almost tangentially into the air stream created by the blades. The entrance portion 53 of surface 52 is planar and horizontal and the discharge end portion 55 is upwardly curving. The tunnel 50 also has a side wall 54 including a planar portion 47 almost parallel to the path of the log at the entrance end of the tunnel and a curved discharge end portion 49 which at its end is substantially parallel to the plane of the fanwheel at discharge opening 56 of the tunnel. A stiffening flange 57 is provided at the upper edge of the planar portion, and stiffeners 59 and 61 secure the tunnel rigidly in the housing. The chips are discharged from the knives 36 in a stream impinging against the bottom surface 52 and the side surface 54 at angles less than 45 so that there is little or no fracturing of the chips and the velocity of the chips is reduced very little. The tunnel directs the stream of chips into the air stream of the fanwheel at a small angle with the air stream and with the chips having a velocity almost as great as that of the fan blades 46, for example, within about fifteen per cent of the speed of the fan blades. As a result, the air stream and momentum of the chips takes most of the chips out of the housing without engagement with the fan blades and those chips which are engaged by the fan blades are engaged at such a low differential velocity that there is substantially no fracturing of the chips. Also, as best shown in FIG. 3, the almost tangential entrance direction of the chips causes them to impinge against the periphery of the fanwheel housing 42 at such a small angle that the chips are not fractured and are not slowed appreciably.

The chips are discharged through the outlet 44 which may be connected to any suitable conveying system. The velocity of the chips as they discharge from the outlet 44 will be such that they are transported by the air stream a substantial distance.

What is claimed is:

1. In a top discharge chipper,

a shaft,

a chipper disc mounted on the shaft and rotated thereon for slicing chips crosswise of the grain from the ends of a log fed thereto and discharging chips in a predetermined path,

a fanwheel mounted on the shaft at the discharge side of the chipper disc and spaced from the chipper disc, and intersecting said chips path,

a fan housing having a discharge opening and defining a centrifugal fan with the fanwheel, whreby the fan creates a generally peripheral air stream flowing to and through the discharge opening,

first deflecting means fixed relative to the fan housing, arranged to intercept said chips at an impact angle less than about 45 and directing the chips substantially radially outwardly to prevent impingement of the chips against the fanwheel,

and second deflecting means fixed relative to the fan housing, arranged to intercept said chips at an impact angle less than about 45 and deflecting the chips substantially tangentially into the air stream' 2. The top discharge chipper of claim 1 wherein the first deflecting means is a first wall in a position positioned between the chipper disc and the fanwheel to prevent impingement of the chips on the fanwheel.

3. The top discharge chipper of claim 2 wherein the first wall curves from a direction extending acutely relative to the fanwheel to a direction extending substantially parallel to the fanwheel proceeding away from the entrance end of the wall toward the discharge end of the wall.

4. The top discharge chipper of claim 3 wherein the second deflecting means is a second wall substantially perpendicular to the first wall.

5. The top discharge chipper of claim 4 wherein the second wall curves to a direction almost tangential to the peripheral portion of the fanwheel at the discharge end of the second wall.

6. The top discharge chipper of claim 5 wherein the walls define a trough substantially L-shaped in transverse cross-section.

7. In a top discharge chipper,

a shaft,

a chipper disc mounted on the shaft and rotated thereby for slicing chips crosswise of the grain from the end of a log fed thereto and discharging the chips in a predetermined path,

a fanwheel mounted on the shaft at the discharge side of the chipper disc and spaced from the chipper disc, and intersecting said path,

a fan housing having a discharge opening and defining a centrifugal fan with the fanwheel, whereby the fan creates a generally peripheral air stream flowing to and through the discharge opening, and a generally funnel-like guide leading from the discharge area of the chipper disc substantially to the air stream providing impact surface for said chips at an angle less than about 45 and directing chip flow substantially tangentially into the air stream.

8. In a top discharge chipper,

a fanwheel having a peripheral blade portion,

a fan housing enclosing the peripheral blade portion of the fanwheel and also having a discharge opening to define a centrifugal fan,

a chipper disc having blades for slicing chips crosswise of the grain from the end of a log fed thereto and discharging chips toward the fanwheel,

first deflector means fixed relative to the fan housing, positioned adjacent the fanwheel for intercepting the discharged chips at an angle less than about 45 and directing the chips radially outwardly away from the fanwheel,

and second deflecting means fixed relative to the fan housing, intercepting the discharged chips at an angle less than about 45 and for directing the chips at a small angle into the path of the fanwheel.

9. The method of producing wood chips comprising:

slicing chips crosswise of the grain from the end of a log, whereupon the chips are discharged at least partially toward a portion of a centrifugal fanwheel positioned radially inwardly from the blade portions of the fanwheel at a high velocity,

and intercepting the discharged chips at a small angle and guiding the chips along a fixed path radially outwardly relative to the fanwheel and into the path of the blade portions in a direction substantially parallel to the direction of movement of the blade portions, whereby breakage of the chips is minimized.

i It i I t

Claims

2. The top discharge chipper of claim 1 wherein the first deflecting means is a first wall in a position positioned between the chipper disc and the fanwheel to prevent impingement of the chips on the fanwheel.
3. The top discharge chipper of claim 2 wherein the first wall curves from a direction extending acutely relative to the fanwheel to a direction extending substantially parallel to the fanwheel proceeding away from the entrance end of the wall toward the discharge end of the wall.
4. The top discharge chipper of claim 3 wherein the second deflecting means is a second wall substantially perpendicular to the first wall.
5. The top discharge chipper of claim 4 wherein the second wall curves to a direction almost tangential to the peripheral portion of the fanwheel at the discharge end of the second wall.
6. The top discharge chipper of claim 5 wherein the walls define a trough substantially L-shaped in transverse cross-section.
7. In a top discharge chipper, a shaft, a chipper disc mounted on the shaft and rotated thereby for slicing chips crosswise of the grain from the end of a log fed thereto and discharging the chips in a predetermined path, a fanwheel mounted on the shaft at the discharge side of the chipper disc and spaced from the chipper disc, and intersecting said path, a fan housing having a discharge opening and defining a centrifugal fan with the fanwheel, whereby the fan creates a generally peripheral air stream flowing to and through the discharge opening, and a generally funnel-like guide leading from the discharge area of the chipper disc substantially to the air stream providing impact surface for said chips at an angle less than about 45* and directing chip flow substantially tangentially into the air stream.
8. In a top discharge chipper, a fanwheel having a peripheral blade portion, a fan housing enclosing the peripheral blade portion of the fanwheel and also having a discharge opening to define a centrifugal fan, a chipper disc having blades for slicing chips crosswise of the grain from the end of a log fed thereto and discharging chips toward the fanwheel, first deflector means fixed relative to the fan housing, positioned adjacent the fanwheel for intercepting the discharged chips at an angle less than about 45* and directing the chips radially outwardly away from the fanwheel, and second deflecting means fixed relative to the fan housing, intercepting the discharged chips at an angle less than about 45* and for directing the chips at a small angle into the path of the fanwheel.
9. The method of producing wood chips comprising: slicing chips crosswise of the grain from the end of a log, whereupon the chips are discharged at least partially toward a portion of a centrifugal fanwheel positioned radially inwardly from the blade portions of the fanwheel at a high velocity, and intercepting the discharged chips at a small angle and guiding the chips along a fixed path radially outwardly relative to the fanwheel and into the path of the blade portions in a direction substantially parallel to the direction of movement of the blade portions, whereby breakage of the chips is minimized.