US2899992A

US2899992A - Apparatus for making wood pulp chips

Info

Publication number: US2899992A
Authority: US
Publication date: 1959-08-18
Anticipated expiration: 1976-08-18

Description

Aug. 18, 1959 E. M. KEY

APPARATUS FOR'MAKING woon PULP CHIPS Filed Sept. 25, 1957 INVHVTOR. dWar'dMKey nite APPARATUS FOR MAKING WOOD PULP CHIPS Edward M. Key, McMinnville, reg., assignor of one-half to Herbert B. Fisehborn, Portland, Oreg.

Application September 23, 1957, Serial No. 685,491

3 Claims. (Cl. 144-162) not only excessive loss of high grade wood due to the.

initial cutting of the rough lumber to sizes substantially exceeding the finished dimensions, but also includes the waste of power which is required of the planer for removing this excess wood. Thus, the sawmill is burdened with the excessive expense of providing planer motors of excessive horsepower and accordingly excessive initial cost and operating expense, in order to reduce the excess dimensions of high grade lumber to shavings which are useful only as hog fuel or as low priced material for certain types of particle board.

On the other hand, it is recognized that wood chips of a specified character command a premium price for use in the manufacture of pulp and paper. However, the manufacture of wood pulp chips of the required specifications heretofore has been achieved by means of conventional wood chippers which function to consume the entire mass of wood fed to them. Thus, conventional chippers do not solve the problem of salvaging the excess dimensions of lumber in the form of high grade wood pulp chips.

' Accordingly, it is a principal object of the present invention to provide a method and apparatus by which the excess portion only of the dimensions of rough cut lumber may be reduced to wood pulp chips of high quality.

Another important object of this invention is the provision of apparatus for reducing a portion only of the dimensions of lumber to high quality wood pulp chips, which apparatus is adaptable for installation and operation immediately adjacent the iufeed end of a lumber planer.

A further important object of the present invention is the provision of apparatus which is adjustable to effect removal of varying proportions of the dimensions of lumber in the form of high quality Wood pulp chips of varying dimensions. I

Still another important object of this invention is to provide apparatus for producing wood pulp chips, which apparatus is of simplified and sturdy construction for eco nomical manufacture and long operating life, and which may be maintained and repaired with facility and speed.

The foregoing and other objects and advantages of this invention will appear from the following detailed description, taken in connection with the accompanying drawing, in which:

Figure l is a fragmentary foreshortened schematic view in side elevation of a sawmill planer having installed a djacent the infeed end thereof apparatus for making wood pulp chips, embodying thefeatures of the present invention;

States Patent Patented Aug. 18, 1959 chipper head assembly embodying the features of the present invention;

Figure 3 is a sectional view taken along the line 33 in Figure 2;

Figure 4 is a sectional view taken along the line 44 in Figure 2; and

Figure 5 is an enlarged fragmentary view in side elevation illustrating the chipping operation of the chipper head assembly illustrated in Figures 2, 3 and 4.

As indicated hereinbefore, the apparatus of this invention is particularly adaptable for use immediately adjacent the infeed of a sawmill planer. In the schematic view of Figure 1 there is illustrated a planer head 10 associated with a planer table 12, resilient hold-down members 14 and two pairs of infeed rolls 16, 18. Usually the planer head is driven from one source of power and the infeed rolls from another source of power, with all of the feed rolls interconnected in any desired manner, for synchronous operation. Lumber 20 is fed to the planer head from a conventional feed. table such as is illustrated by the plurality of driven rolls 22. The planer head rotates in the'direction opposite the direction of movement of lumber, as indicated by the arrow, to remove the excess Wood in the form of shavings.

In accordance with the present invention, the wood pulp chipping apparatus is interposed between the feed table rolls and the planer infeed rolls. Thus, as illustrated in Figure 1, there is provided a chipper head 24 associated with a chipper table 26, a resilient hold-down member 28 and a vacuum hood 30 for removing the chips to a place of storage. A pair of chipper infeed rolls 32 and a pair of chipper outfeed rolls 34 are located at appropriate opposite sides of the chipper head, as illustrated. These pairs of feed rolls preferably are connected to the planer infeed rolls for synchronous operation, to assure uniformity of feed of lumber through the assembly.

Referring now particularly to Figure 2 wherein'is illustrated one form of chipper head embodying the features of this invention, an elongated chipper knife support 36 is provided with end shafts 38 adapted to be mounted in bearings upon a suitable frame for axial rotation, being driven by a suitable source of power. The end shafts may be formed as an integral part of the knife support, or may constitute a single shaft extending through an axial bore in the knife support, with the latter being secured to the shaft by means of the key 40 illustrated, or by other conventional means.

The chipper head construction illustrated in the drawing is designed to accommodate removal of wood pulp chips from the top surface andone side surface of a piece of lumber. Accordingly, the chipper knife support 36 includes an end section 42 of larger cross-sectional dimension. In the embodiment illustrated, both sections of the knife support are square in cross section, although other shapes, e.g. triangular or polygonal, may be employed if desired, as explained more fully hereinafter.

' A plurality of chipper knives are adapted to be mounted securely upon the elongated section 36 of the knife support. In the illustrated embodiment each knife includes a cutting section 44 and a shank section 46 provided with a longitudinal slot 48 adapted to receive one or more securing bolts 49 which may be threaded into tapped openings in the knife support. Although the knives may be arranged in various patterns upon the support, the arrangement illustrated is as follows: Two knives are positioned on the elongated section 36 immediately adjacent the enlarged end section 42, diametrically opposite each other. A second pair of knives is positioned on the elongated knife support adjacent the first pair, diametrically opposite each other and displaced from the first pair. -Additional pairs of knives are mounted on the elongated section of the support successively toward the end of the latter opposite the'enlarged end section 42 and displaced 90 from the preceding pair.

Each of the knives mounted on theelongated support is bent obliquely-intennediate itslends and is-provided with a cutting edge 50. The back'edge oft'heknife tapers;

cuttingedge ground to permit engagement of the cutting edge with the wood progressively from one side tothe other. Thus, the width of the knife varies to achieveithis result, but the side edges generate parallel planes during rotation and-the cutting edge generatesa cylinder during] rotation. 7

Referring particularly to Figure .4 ofthe drawing, .the knives supported on the elongated section 3.6 are arranged in such manner that a radial line .drawnfr'om the axis .of. rotation .of the cutter head to the cutting edge of the blade forms with the adjacent surface'of the blade an acute angle A not substantially less than 50. This is an important requirement of the present invention for the production of wood pulp chipsof acceptable quality. If this angle is substantially less than 50 the trailing end of the chip becomesbroken as it is removed from the-lumber, thencby fracturing the wood'fiber and rendering the chips use: less for pulp purposes. The angleimay be increased as the ratio of lumber feed rate to chipper head speed is increased, in order .to prevent pressure contact ofithe back surface of the knife against the adjacent wood surface}, as explained more fully hereinafter.

It has been determined that the most suitable pulp. chips .are produced. when the aforementioned angle is about 58. Although the manner in which saidchips are produced is not completely understood, it isbcl'ieved that as each knife is driven .arcuately into the -=,woo,d by.

rotation of the cutter head-the knife edge .cuts arcuatel-y downward and forward while the leading surface of the. knife adjacent the cutting edge functions as a wedge to pry ioitlthe wood in front of the knife. ln any ev n it has heendetermiued. hat the pera i n of the, u ter head fun tions to vproduce thin wo d chips Si el insbeveled ends and .a maximum width equal to the width of the knife. The thickness of the h p s dependent somewhat upon the thi kness of wo e ng mov d from thelumber; When the thickness of wood being removed is ',less than about /8 inch, the chip is the same thickness. On the, other hand, when the thickness of wood being removed is greater than about /8 inch, the chips are removed in layers of about /a inch, as is illustrated in Figure 5.

' A critical requirement for wood pulp chips is that they be of a predetermined length, .i.e. the length between-the beveled ends. Since this length varies for different types of ,pulp products, means is provided in the method and apparatus of this invention for adjusting the length ,of chipsto be produced. The preferred manner of adjustment involves the variation of the rate .of speed with which the lumber 2.0 is fed past the chipper head 24, with the latter being rotated at ,aconsta-nt speed. lhisnnay @be accomplished conveniently ,by providing a variable speed source of power :for the feed rolls. It will be understood that, with-the chipper head being .driven .at a constant speed, the length of the chips will varyin proportion to the rate of .feedof lumber past the chipper head ii Alternatively, it will .be apparent that the lerigthiof chips .may be varied by maintaining the rate of speed of lumber past thechipperhead at a constant .rate, .and

varying the rotational speed .of the chipper head.- Further variation may he ma y prov ng the ch ppe head with fewer .or greater numbers of knives, as for e tample :by provi ing a;knif.e:support having triangular cross section or a polygonal cross section, with each face supporting a knife.

It is important further to the production of high quality wood pulp chips that the forward feed rate of the lumber past the chipper head be less than the speed with which the chipper knife travels forwardly through the wood. It is apparent that if the rate of lumber feed is greater than the forward travel of the knife through the wood, the

wood will be forced against the trailing surface of the knife with suflicient pressure to compress and damage the leading beveled end of the subsequent wood chips. It is preferred that theforward rates of speed of the lumber and the chipper knife be such that a space he maintained between the trailing surface of the knife and the adjacent surface of wood. is accomplished in part by maintaining the forward rate of speed of the knives greater than the forward rate of lumber feed, and in part by the angle A. Obviously the greatest circle generated by rotation of the-knives must be at the cutting edge 50,-and

this determines the-maximum magnitude of the angleA. As explained hereinbefor-e, it may be desirable also to reduce'the width of lumber approximately toits finished dimension, in which case there is provided the enlarged i end section 42 of the knife support and the plurality of knives mounted thereon, there heing two such illustrated inthe drawing. These knives are arranged to out completely through the thickness of the lumberfland to remove such excess wood in the form of pulp chips.

r These'kni-ves .eatend radially outward from the axis of rotation of the knife support, .adistance greater than the knives supported on the elongated section 36. Each .of the kni-ves is-provided with a cutting section 54 and a shank section 56 having (a longitudinal slot 5:8 for the securing bolt 59. Each knife is provided with a cutting V edge 6.0 along a. portion of the inner longitudinal edge, and a forward cutting edge 62', as illustrated. As explained hereinbefone, these latter knives function to reduce the excess dimension .of lumber along .one longitudinal:

, edge ,to high quality wood pulpichips, and hencethe knives are bent to the angular requirement explained heteinhee: fore.

'The operation of the chipper head is heat illustrated by being indicated by arrows. As the knife penetnatesfurther'into the wood :the. front surface-of the knifelfuno ion s :a wedge to .pry off the wood in front of thekn f the rate of-forwardtravel of the knife being atleast as great and preferably greater than the speed of forward travel-:of the lumber. .Sincetthoknife :Pfifletrates the lumbfer to a depth greater than about Ms inch, thechip 5, 21 areformed by splitting .of the wood in front of the kn fe,

successive layers of;about 4/8 inch thickness.

:The cut ing edg t knife P eferab y i sli ly dulled, to prevent removal of wood at the final depth of the cutin the form of a thi zshau ng :vrh hs unsui ab f -h a wBv so cull ng t nife ed e. t q te s e over the-surface of the l m er w tho remov ng he. fi a thickness thereof. Although the surface of .the lumber thus acted upon by the knives has a slightly rippled surface, this is removed during the subsequent planing oporation wherein the lumber is reduced to itsdesifed finished dimensions with a minimum loss of .wood in the form .of shavings. a V

, Io illustrate the foregoing, a typical installation was made wherein (the radius of rotation of the cutting edges 1( 0f the knives was 2- /2 the angle A was 58 ..and.the.

rotational speed of the cutter head. 2.4 was :set at 13,600 rpm. I lustrated in the drawing, tie. in .pairs ,positionedrdiametrically opposite each other, high quality wood pulp chips 42" in -.le ng'th were produced with atlumber feed 'rateof 300 lineal :feet per minute. With a triangular knife sup- With chip per knives spaced in the manner .il-

port and three knives positioned 120 apart, the feed rate of the lumber was increased to 450 feet per minute to provide the same chip. With four knives spaced 90 apart, the /2" chip was produced with a lumber feed rate of 600 feet per minute, and a proportionate increase in lumber feed rate is required with the use of additional knives. The angle A also was increased as lumber feed rate was increased, in order to maintain clearance between the back surface of the knife and the adjacent wood.

Thus, the present invention provides simplified apparatus by which to produce wood pulp chips of high quality and uniform standard. Although it may be utilized to produce wood pulp chips by consuming the entire board, it is particularly adaptable for use immediately adjacent the infeed end of a planer, for producing high quality wood pulp chips from the excess dimensions only of rough cut lumber, thereby effecting a considerable saving in sawmill operation.

It will be apparent to those skilled in the art that various changes in size, shape and other details of construction described and illustrated herein may be made without departing from the scope and spirit of the invention. Accordingly, it is to be understood that the foregoing description is primarily illustrative of the invention and is not to be considered as limiting the scope thereof.

Having now described my invention and the manner in which the same may be used, what I claim as new and desire to secure by Letters Patent is:

1. Apparatus for making chips of predetermined length from wood, comprising feed means for feeding wood 30 along a line at a predetermined rate of speed, a rotary chipper head having a chipper knife mounted thereon, the knife being arranged with its leading face forming with the radial line of rotation of the cutting edge of the knife an included angle of at least 50, the chipper head being mounted relative to the feed means such that a predetermined thickness of WOOd is intercepted by the knife through an arc of rotation of the latter, the chipper head being rotatable in the direction for movement of the knife through said are in the direction of said feed of wood and at a speed of rotation for movement of the knife through said are at a predetermined speed greater than said feed of Wood.

2. Apparatus for making chips of predetermined length from a portion of the dimensions of lumber, comprising feed means for feeding lumber along a line at a predetermined rate of speed, an elongated rotary chipper head having a plurality of longitudinally spaced knives mounted thereon, each knife being arranged with its leading face forming with the radial line of rotation of the cutting edge of the knife an included angle of at least 50, the chipper head being mounted relative to the feed means such that a predetermined thickness of lumber is intercepted by the knife through an arc of rotation of the latter, the chipper head being rotatable in the direction for movement ofthe knife through said are in the direction of said feed of lumber and at a speed of rotation for movement of the knife through said arc at a predetermined speed greater than said feed of lumber.

3. The apparatus of claim 2 including an end knife section on the chipper head arranged to cut entirely through the lumber adjacent one longitudinal edge and to remove said lumber in the form of chips.

References Cited in the file of this patent FOREIGN PATENTS 131,335 Australia Nov. 28, 1946