US3516464A

US3516464A - Apparatus and method for removing wood defects

Info

Publication number: US3516464A
Authority: US
Inventors: Joseph F Cyr
Original assignee: US Plywood Champion Papers Inc
Current assignee: US Plywood Champion Papers Inc
Priority date: 1968-07-22
Filing date: 1968-07-22
Publication date: 1970-06-23
Anticipated expiration: 1987-06-23

Description

June 23, R v APPARATUS AND METHOD FOR REMOVING WOOD DEFECTS Filed July 22. 1968 m I! EW 3.

I'NVENTOR OSEPH F. C

BY WM ATTORNEY.

3,516,464 APPARATUS AND METHOD FOR REMOVING WOOD DEFECTS Joseph F. Cyr, Lebanon, reg., assignor to U.S. Plywood- Champion Papers Inc., a corporation of New York Filed July 22, 1968, Ser. No. 746,683 Int. Cl. B27d 5/00 U.S. Cl. 144309 14 Claims ABSTRACT OF THE DISCLOSURE An apparatus and method is provided for deknotting wood, particularly thin wood sections such as veneer, and includes a plurality of striking elements, such as rods positioned above the wood and means for periodically forcing the rods into contact with the wood to thereby loosen and dislodge wood defects. Each rod is separately regulated to strike the wood at predetermined intervals and each is provided with means to reciprocally move the rods in a plane substantially at right angles to the wood which is being processed.

FIELD OF THE INVENTION This invention relates to apparatus and method for removing defects from any plane surface and particularly for removing knots and other similar defects from wood. More particularly the invention relates to an apparatus and a method for removing knots from thin wood sections such as wood veneers without adversely affecting the strength or structure of the surrounding wood.

An apparatus and method is provided for deknotting wood, particularly thin wood sections such as veneer, and includes a plurality of striking elements, such as rods positioned above the wood and means for periodically forcing the rods into contact with the wood to thereby loosen and dislodge wood defects. Each rod is separately regulated to strike the wood at predetermined intervals and each is provided with means to reciprocally move the rods in a plane substantially at right angles to the wood which is being processed.

A common and continuing problem encountered during the manufacture of unsurfaced and overlaid plywood, veneer, and other similar products fabricated from thin sections of wood is the presence of defects such as knots, incipient decay, rot, pitch pockets, and the like which tend to fall out during the manufacturing process thereby impairing the quality and spoiling the utility and appearance of the wood. These defects are often characterized by being continuous between the plane surfaces of the thin sections of the wood and when the material from these defects falls from the wood it is frequently responsible for damage to equipment as well as harmful to the wood itself. For example, the rubber rolls of glue applicator machines can be damaged by hard pieces of knot. Furthermore, the glue in the applicator machines can be contaminated by the knots, rots and other material. In addition, if this undesirable material is present, it can be pressed into and mar the surface of a plywood panel, or the overlaid face of a composite panel during processing. Of ever greater importance, these materials can find their way bet-ween plies in plywood to prevent proper bonding, thereby causing total loss or at least reducing the value of the panel.

Wood veneer and plywood are overlaid with a variety of different materials, such as decorative wood veneegs, paper, cloth, etc. to produce desired products. Open de fects in the wood have to be filled with a type of wood putty so that they may present a better surface for gluing both in ordinary plywood and particularly in overlaid United States Patent 0 ice wood. Open, loose, and even solid knots present a particularly poor surface for glue bonding and it is also prior to processing the wood so that the best surface for bonding may be achieved by filling the vacant space with a better material.

In view of the importance to the industry of a process which will effectively remove all loose knots from the veneer early in the processing thereof, there is a continuous effort to develop such a process. A wide variety of .devices and processes have been employed but few have been successful. One such process requires the precise cutting of the knots or other defects from the Wood and then applying round or boat shaped patches to the' vacated area of the wood. Such a process is expensive and slow and is accompanied by serious waste of valuable patching material and the large cut of wood is taken from around the knot.

It is obvious, therefore, that there is still a need for an apparatus and process which can effectively and economically dislodge knots and other wood defects for the subsequent filling of the hole by a suitable wood filler composition to a plane surface, and for final overlaying with expensive surfacing veneers or abrasive resistant resin impregnated papers.

DESCRIPTION OF THE INVENTION Broadly, the present invention is directed to an apparatus for deknotting wood comprising a support member for supporting the wood, a plurality of striking elements, for example, rods positioned above the wood, and means to move the rods such that they are caused to strike the upper surface of the wood to thereby loosen and dislodge the knots and other defects. Rods are used to denote all types of striking elements. In the preferred embodiment, each rod is independently reciprocated and periodically strikes the wood. The rods, which are generally raised and lowered in a plane substantially at right angles to the wood passing beneath them, are arranged such that they extend, at spaced intervals, across substantially the entire width of the wood. With this arrangement, all of the knots in the veneer are subjected to the force of the striking rods.

Since the rods can be individually controlled, they may be timed to strike the wood with varying frequencies and at various intervals, that is other than simultaneously. Several rows of aligned rods may be positioned together, and with individual rod timing, the force applied to the veneer is such as to cause it to vibrate and release virtually all releasable knots and defects. This effect is accomplished without damage to the veneer due to the strike' of the rod since a large force is not required.

A further important feature of the invention is the means employed to raise and lower the rods in a reciprocal manner. In the most desired embodiment, several spring coils are positioned about each rod and are separated by a flanged member which is secured to the rod. When a force is applied to the flanged member to raise or lower the rod, the upper or lower coil is placed in compression and upon release of the pressure, the coils serve to cause the rod to oscillate slightly, thereby permitting the rod to strike the wood several times in quick succession. The result is that the wood is subject to the several rod forces in the same area, thus further increasing the effective deknotting force of the apparatus.

DESCRIPTION OF THE DRAWINGS The invention will be more readily understood by referring to the drawings, wherein FIG. 1 is an isometric view of the apparatus of the invention; and

FIGS. 2, 3 and 4 are enlarged views of a rod employed in the apparatus of FIG. 1, in various positions during a single cycle; and

FIG. is a side view in cross section of the rod assembly illustrated in FIG. 2.

Referring to the drawings, in FIG. 1 there is shown a deknotting apparatus designated generally by the numeral including a base support member 12 which supports the wood to be deknotted such as veneer strip 14. As shown, the veneer is marked by a number of knots and other defects which are indicated by the numeral 15. A plurality of rods 16, positioned above the support member 12, are held in a substantially vertical position by frame means 18 comprising an upper segment 20 and a lower segment 22. The segments are each provided with a plurality of openings such as at 24, 26 through which the rods 16 project and which aid in the alignment of the rods. The frame is fixed above the support member by means of

bars

28, 30 which are secured at their base to the support member 12. The rods are surrounded by spring means 32 and each rod is equipped with a flanged segment 34 which is secured to the rod such as by welding. In each rod assembly, the flanged segment is in direct contact with the spring means. A shaft 36, which is caused to rotate by motor means 38, is positioned above the support member 12 and adjacent the rods 16. A plurality of cams are firmly attached to and spaced along the shaft 36, and are positioned such that one cam is proximate each flanged segment 34. The cams are spirally mounted along the shaft 36, that is, the projecting portion 42 of each cam 40 is displaced slightly about the shaft relative to the position of the projecting portion of the adjacent cam. In this manner, the various flanged segments 34 are contacted by the cams at diffeernt times during the revolution of the shaft 36. .A receptacle 44 for receiving the dislodged knots is placed in the support member 12 directly beneath the rods.

In the operation of the apparatus, the veneer strip 14 is passed along the surface of the support member 12 by means (not shown) such as a conveyor belt or the like. The rods 16 are normally positioned slightly above the surface of the veneer strip 14. However, as the shaft 36 is rotated, cams 40 apply a force to the flanged segments 34 through the projecting portions 42. Each cam trips the associated rod as it is rotated into contact with the flanged segment on the rod and because of the spiral arrangement of the cams, each rod is moved at a time different than the rod adjacent to it. Of course, the cam positions may be arranged in virtually any configuration along the shaft to obtain the most suitable timing for a given system. As the flanged segment is forced upward by the cam, the rod is lifted a short distance and pressure is applied to the coil spring 32. Upon further rotation of the shaft, the cam force is released from the flanged segment and the upper coil spring pressure urges the rod downward causing it to strike the passing veneer strip. A damping as well as an oscillating effect is achieved by the presence of lower spring coil 46 (shown in FIG. 2) which is positioned about the rod below the flanged segment. This action is repeated for each rod at least once for each revolution of the shaft and the resultant effect is to vibrate the veneer strip as it passes, thereby dislodging the various wood defects which are then collected in the receptacle 44.

The operation of the rods is more clearly illustrated in FIGS. 2, 3 and 4. In FIG. 2, the projecting portion 42 of the cam 40 is shown lifting the flanged segment 34 and thus the rod 16 as the shaft 36 rotates. The coil spring 32 is placed in compression by the force of the flanged segment as it is lifted. FIG. 3 shows the rod assembly immediately after the cam is rotated out of contact with the flanged segment. The rod 16 is in a position ot strike the veneer, that is, at the lowest point in its path of travel due to the pressure released by coil spring 32. However, the FIG. 4 illustrates the same rod assembly as the shaft 36 continues to rotate. The rod 16 is now forced upward by lower coil spring 46 after striking the veneer. The

oscillating motion of the rod continues for a brief period until dampened by the coil spring friction. During the oscillation period, the rod strikes the veneer several times as hereinbefore explained.

FIG. 5 illustrates the rod assembly in cross section. As theer shown, the upper coil spring 32 is positioned between flanged segment 34 and frame member 20 and is connected to both while lower spring coil 46 is connected to flanged segment 34 and frame member 36.

Openings

24, 26 align rod 16 and aid in maintaining the direction of movement of the rod. The upper spring coil 32 is preferably somewhat stronger than the lower coil 46 in order that the above-described oscillating motion of the rod can be more readily effected.

The rods can be constructed of any sturdy material which will Withstand the frequent striking of the Wood. Steel rods approximately 8 inches long and inch in diameter have been employed quite successfully for prolonged operating periods without requiring replacement. The cycle frequency of the rods is a function of several variables such as spring tension, size of cam projecting portion which would also control the length of rod movement, rate of veneer travel and speed of shaft rotation. By way of example, a shaft speed of 700 revolutions per minute for a one inch. diameter shaft with cam and rod assemblies spaced one inch apart, together with a veneer speed of 50 feet per minute have resulted in a desirable cycle frequency. Obviously, variations of these parameters is well within the mechanical skill of an operator.

Many modifications of the apparatus of the invention are readily apparent and are intended to be within the purview of this invention. For example, while the abovedescribed cam-shaft arrangement is believed to be a simple, inexpensive and effective means for imparting the desired motion to the rods, mechanical equivalents such as overhead drive devices can also be employed. In addition, the rods may be dispersed over a greater area of the veneer to provide a greater operating force. Several rows of rods, staggered laterally, would ensure that various portions of knots to be removed would be struck by the rods. The rods can also assume various shapes, particularly at the end which strikes the veneer. This lower end can be equipped with shoes to soften the blow to the wood, if desired, although this expedient has not been found to be necessary. An enlarged lower rod portion designed to strike a greater area of passing veneer is also a feature which is readily incorporated into the apparatus.

The term rod as used herein and in the appended claims is intended to include within its meaning any instrument which will impart the necessary force to the Wood to loosen and dislodge the wood defects therein in the manner described.

From the foregoing, it will be appreciated that the apparatus and process of the invention provide a simple, economical and eflicient solution to the long standing problem of removing defects from wood. The apparatus has been successively employed in removing defects from wood of various thicknesses quickly and without injury to the surrounding wood.

The embodiments of the invention in which an exclusive property or privilege is claimed are as follows:

1. An apparatus for removing defects from wood comprising (a) a base support member for supporting the wood;

(b) a plurality of rods positioned above the wood on said support member; and

(0) means for reciprocating said rods to periodically contact said wood, thereby causing said wood to be continuously subjected to the force of said moving rods whereby the defects in said wood are loosened and dislodged.

2. The apparatus of claim 1 wherein said rods are positioned substantially at a right angle to said wood.

3. The apparatus of claim 1 wherein said rods are arranged such that they extend at spaced intervals across substantially the entire width of said wood and are aligned in at least one row.

4. The apparatus of claim 3 wherein means for regulating the movement of each rod independently of any other rod are included.

5. The apparatus of claim 1 wherein means for receiving the dislodged defects are provided below said wood and directly below said rods.

6. An apparatus for removing defects from wood comprising (a) a base support member for supporting the wood;

(b) a plurality of rods positioned above and substantially at right angles to the wood on said support member;

(c) spring means aflixed to each of said rods;

((1) means for periodically applying a force to said spring means substantially along the longitudinal axis of said rods whereby said rods are alternately raised and lowered, said force being sufficient to cause said rods to contact said wood when lowered to thereby loosen and dislodge the defects in the wood.

7. The apparatus of claim 6 wherein means for regulating the movement of each rod independently of any other rod is provided.

8. The apparatus of claim 6 wherein said spring means on each rod is divided into an upper spring coil and a lower spring coil, a flanged segment is secured to each rod and positioned between said upper and lower spring coils, and said force is applied to said flanged segment.

9. An apparatus for removing defects from wood, comprising (a) a base support member for supporting the wood;

(b) frame means secured to said base support member, said frame means having spaced substantially parallel upper and lower segments positioned above said support member, each of said segments having a plurality of openings therein;

(c) a plurality of rods secured to said frame means,

said rods extending through said openings, and positioned above and substantially at right angles to the wood to be processed;

(d) a flanged segment secured to each rod;

(e) spring means affixed to each rod, said spring means being positioned between said flanged segment and 45 said frame segments; (f) a rotatable shaft secured to said base support member and positioned adjacent to said rods;

(g) a plurality of cams aflixed to said shaft and placed thereon such that upon rotation of said shaft, said cams contact said flanged segments on Said rods; and

(h) means to rotate said shaft whereby said flanged segments are contacted by said cams to reciprocate said rods intocontact with the wood to thereby loosen and dislodge the defects therein.

10. The apparatus of claim 9 wherein said cams are spirally mounted about the axis of said shaft such that said rods are reciprocated at different periods during the revolution of the shaft.

11. The apparatus of claim 9 wherein said spring means is divided into an upper spring coil and a lower spring coil, each coil being in communication with said flanged segment.

12. The apparatus of claim 9 wherein said rods are arranged such that they extend across substantially the entire width of the wood to be processed and are aligned in at least one row.

13. A method for removing wood defects from wood, comprising passing said wood over a supporting surface;

applying a plurality of forces to the upper surface of said wood, said forces being applied at substantially right angles to said upper surface and at spaced intervals across substantially the entire width of said Wood;

regulating the application of said forces such that each force is cyclically applied and less than all of said forces are simultaneously applied whereby said wood is caused to vibrate to thereby loosen and dislodge the defects therein.

14. The method of claim 13 wherein the step of oscillating said forces during the application thereof is added.

References Cited UNITED STATES PATENTS GERALD A. DOST, Primary Examiner U.S. c1. X.R.