US2607377A

US2607377A - Knife and knife holder assembly in veneer cutting machines

Info

Publication number: US2607377A
Application number: US46083A
Authority: US
Inventors: Ericsson H Merritt
Original assignee: SOLEM MACHINE CO
Current assignee: SOLEM MACHINE CO
Priority date: 1948-08-25
Filing date: 1948-08-25
Publication date: 1952-08-19
Anticipated expiration: 1969-08-19

Description

Aug. 19, 1952 E. H. MERRITT KNIFE AND KNIFE HOLDER ASSEMBLY IN VENEER CUTTING MACHINES Filed Aug. 25, 1948 w n f m, rm mm M I M N m. wp

A TTORNEX Patented Aug. 19, 1,952

KNIFE AND KNIFE HOLDER ASSEMBLY IN VENEER CUTTING MACHINES Ericsson H. Merritt, Lockport, N. Y.,'assignor, by

mesne assignments, to Solem Machine Company, Rockford, 111., a corporation of Illinois Application August 25, 1948, Serial No. 46,083.

- 5 Claims.

This invention relatestothe art of cutting and slicing wood veneer; more particularly it relates to an improved knife-andknife holder combination to be used with veneer cutting and slicing equipment.

In general practice rotary veneer is produced by revolving a log against a knife whose length is equal to or in excess of the length of the log being cut. Sliced veneer is produced by clamping a flitch to areciprocating table and moving the table with the-flitch"past the knife. 'Ateach stroke a sheet of veneer is cut from the iiitch. In each of the described veneer cutting opera? tions, to prevent the ,wood from splitting ahead of the knife, a pressure plate is provided to'apply pressure to the log just'ahead of the knife. Thus, the ribbon of veneer severed from the log by the knife is actually extruded through the slot formed by the knife and the pressure plate. The crosssection of this slot isslightly less than the thickness of veneer'being cut. To cut smooth uniform.

thickness veneer, the slot must be of uniform cross-section and have parallel edges. Furthermore, in the case of rotary veneer the bottom edge of the slot formed, by the edges of the knife must be in accurate parallel relationship to the axis of rotation of the logand the top of the slot formed. by the pressure plate must be in accurate parallel relationship to'the knife edge. is not unusual to cut veneer as thin as fifteen thousandths of an inch in thickness, 'it is obvious that the tolerances to which the knife must be set'are extremelynarrow. 1

Veneer knives are composite structures generally varying in sizefrom {2 inch to inch thick, usually 6 inches to? A; inches wide when new, and varyingin length from 24inches to 200 inches.

Since it i r Slots are usually provided for bolts used to at-' not to mention the loading incident to cutting.

As the knife becomes narrower due to grinding,

sharpening operation on the knife, due to the stresses introduced by the veneer cutting operation, it is often necessary to force the knife to .assume a straight line. The bevel of'the knifeis ground until a sharp cutting edge is produced which is a straight line within the limits of accuracy of the grinder and the perfection of the plane of the face of the knife. This grinding operation to a certain extent releases many of [the stresses which were formed in the knife during the .cutting operation. When the knife is released from the grinder clamps which hold the knife rigidly in place during'the grinding operation, it immediately assumes its natural shape and the cutting edge'is no longer a-true straight line. Accordingly'when this knife is attached to the knife carriage in the veneencutting machine, it must be adjusted higher to compensate for the width lost in the grinder and also it must :be forced by local adjusting screws provided in the knife, carriage, to take-such a shape that the cutting edge withbe a true straight line parallel to the axis of rotation of the log. This is a time consuming operation requiring a highdegree of skill. Thus, according to the method as practiced heretofore'of handling veneer cutting knives, a precision alignmentof theknife is the positioning of the knife in a veneer cutting machine so that precision alignment is obtained with a minimum amount of local adjusting.

Another object of this invention is to provide a veneer cutting knife and knife holder assembly which when precision ground will be in perfect alignment without. further adjustment when placed in the veneercutting machine.

It is also an object of this invention to provide an improved knife and knife holder assembly for a veneer cutting machine which eliminates all but a small fraction of the time required to change this deflection materially increases. Thus, the

a knife in a veneer lathe or a veneer slicer.

Further objects will become apparent from the description of the invention and the claims.

These objects are accomplished by means of the applicants invention which provides an accurately machined rigidsteel beam, called the holder, to which a cutting knife is adjustably attached. The veneer cutting knife and knife holder are removable as a unit from the veneer cutting machine. The holder'is so constructed as to have a moment of inertia sufficiently great with respect to the knife to resist deflection of the knife caused by unbalanced stresses therein.

Slots are provided in the holder for rbolts which are threaded into the knife holding the knife rigidly in place. Holes are also provided in both the holder and the knife attached thereto for the purpose of securely bolting the unit to the veneer cutting machine. Push and pull adjusting screws are provided in thebottom of the holder to facilitate adjustment of the knife in the holder. The machined surfaces of the holder and their cooperative machined surfaces on the veneer cutting machine are so constructed as to maintain a fixed relationship between the surfaces and the line of contact between the cutting ed eof' the knife and the log or fiitch.

With such a construction, during the sl'iarpe'ning operation, the dull or nicked knife, together A with its holder, are 'removed'as a unit from the lathe or the slicer. At the grinding wheel, the

. knife is adjusted with respect to the holder to a distance equal to the amount of knife which must be ground away to produce a new perfect edge.

Thfebfevel' of the knife while rigidly clamped in its holder; is ground until the distance from the new 7 edge 'to' the locating. surfaces on the holder is the correct distance to bring the knifehdge to the proper position in the veneer lathe or slicer. The knife and: knife holder are then removed from the grinder, and, due to the moment of inertia of I thek'nife holder; the knife edge remains a straight I line and does'not bow or otherwise deflect due to the internal stresses in the. knife. On replacing the resharpened knife and its holder in the veneer cutting or. slicing machine so that the 10- eating surfaces of theiknife holder are in contact with their cooperative locating surfaces in the cuttingmachin'e, the knife edge is automatically in correct adjustment requiring no further manual local adjusting.

5 The'invention' will be more clearly understood from the following description wherein:

- Figure 1 isthe front "elevation of a fragmentary length of the knife and knife holder assembly'of thisinvention.

Figure 2 is a transverse section of the knife and knife holder assembly of this invention taken on line 2 -2 of Figure l, supported in a conventional 'mannerin a veneer lathe. I

' Figure 3 is a transverse section of the knife and knife holder of thisinvention taken on line 33 of Figure 1.

- The knife holder' l is an accurately machined rigid steel beam to which the adjustable veneer knife 5 is attached. Surface 6 of the knife holder and surface 1 of the knifeholder seat are accumating with a plurality of oval shaped slots I4.

The holes l3 are so ledged to accommodate clamping bolts I5 whereby the knife holder 3 and knife 5 may be rigidly attached to back plate I 6 in such a manner that surface 6 is exactly positioned on surface 7. Veneerknife 5 contains a plurality of slots I! so positioned and of such a size to permit an unobstructed passage of bolt l5. Alternating with'slots ,I'! onkm'fe 5 are a plurality of rows of threaded holes l8, each row of holes consisting of three and being on a center line perpendicular to the length of knife edge, and

. 4 each hole being of such a size to accommodate bolt 19 when placed through slot IA of the knife holder, with slot 14 being so ledged to permit knife 5 to be rigidly attached to holder 4 by tightening bolt [9, and adjusting by means of push screw 20 or pull screw 2|, for which a. threaded hole and a clear hole are provided in holder 4, respectively. Screws 20 and 2 l are so constructed that they do not extend beyond surface 6 of holder 1.

In operation, log 8 is rotated against knife edge 22 cutting a. sheet of veneer which is extruded through. the slot one side of which is formed by the edge of pressure plate 23, which is held in place by pressure plate holder 24, and the other side of" which is formed by the cutting edge 22 of veneer =knife'5. 0n requiring sharpening, bolts l5 are removed and knife holder 4 and veneer sharpened knife edge 22'wi1l be equal tofthe preciselyset and predetermined 'distance' on the lathe. Inasmuch as the knife holder 4 has a sufiicient moment of inertiawith respect to the knife to resist deflection ofthe knife due to the stressesand' strains setup in the knife during the cutting and grinding operations, when the knife holder and the knife which has been accurately aligned at the grinding operation is repositioned in the lathe, no further adjustment of the knife 5 is required. Therefore, since the distance from surface 1 to knife edge 22' is constant, and since this distance is accurately set in the grinding op- I eration, and since the holder is of such a size to resist deflections of the knife due to strains, all

that remains after the grinding operation ismerely the repositioning of the knife and knife holder assembly in the veneer lathe. Thus, in-

' stead of the procedure aspracticedheretofore of requiring'two accurate alignments of the knife, one during the grinding operation and another during the repositioning of'the sharpened: knife in the lathe, only one alignmentisneces'sary, thereby greatly reducing the requirements of highly skilled techniques;

According to heretofore practiced techniques, a dull or nicked veneer knife requiring resharpen ing is removed singly from the cutting machine. An experienced grinder then grinds or resharpens the knife forcing the knife edge by local adjustment to assume a true straight line. The grinder then releases the knife from the grinder carriage and. returns the knife to the slicer or veneer lathe. However, on releasing the knife from the grinder; due to the unbalanced stresses in the knife and the lack of rigidity of the knife blade, the true straight cutting edge is lost due todeflec- Consequently, when this knife is again tions. positioned in the cutting lathe or slicer, realign ment by local adjusting'of the knife is again necessary toforce the cutting edge of the knife intoa" true straight line. Such an aligning and adjusting operation requires a skilled craftsman. With the knife and knife holder assembly of this -inven tion, it is this second local adjustment of the knife that is eliminated. Inasmuch as the cut ting edge has been properly aligned during the grinding operation and is rigidly held in place'by f the holder that has a sufficient moment of inertia to resist subsequent deflections of the knife and that such holder is so constructed with regard to the veneer cutting machine as to maintain a fixed relationship with the line of contactbetween the cutting edge'of the knife and the log or flitch, further adjustment of the knifeis unnecessary whenthe knife and its holder is repositionedin theveneer cutting machine. I

' What is claimed is: i

1;,In a veneer cutting machine comprising a carriage adapted for rigidly supporting the holder of a veneer cutting knife, said carriage including a back plate, a knife and knife holder combination assembly installable and removable as a unit on and from the carriage respectively, means adjustably attaching said knife to said knife holder on that side of the holder adapted to face the back plate, said knife holder having a moment of inertia sufiiciently great to resist defiection of the attached knife, said knife holder having accurately machined locating surfaces cooperative with accurately machined locating sur faces On the knife holdercarriage whereby the distance of the cutting edge of said knife from the said locating surfaces on the knife holder carriage may be accurately set and maintained by said adjustable attaching means before said assembled knife holder and knife is positioned on the carriage, and means fastening said assembled knife holder and knife to the back plate on the carriage comprising bolts extending from said knife holder to the back plate through aligned apertures in said knife and which also serve to clamp said knife between said knife holder an back plate.

2. In a veneer cutting machinacomprising a,

of a veneer cutting knife, the carriage including an elongated back plate, the improvement consisting of a knife and knife holder combination assembly installable and removable as a unit on and from the carriage respectively, said knife and knife holder being both elongated, like the back plate, said knife holder having accurately machined locating surfaces arranged for abutment with accurately machined locating surfaces on the carriage, a plurality of bolts, each of which extends through aligned apertures in said knife holder and knife, one of said aligned apertures being slotted for adjustably securing said knife to said holder on that side thereof adapted to face the back plate, and a plurality of other bolts each of which extendsthrough aligned apertures in said knife holder and knife and into the back plate for rigidly securing the assembled knife and knife holder to the back plate and clamping the knife between the holder and back plate.

3. In a veneer cutting machine, comprising a carriage adapted for rigidly supporting the holder of a veneer cutting knife, the carriage including an elongated back plate, the improvement consisting of a knife and knife holder combination assembly installable and removable as a unit on and from the carriage respectively, said knife and knife holder being both elongated like the back plate, said knife holder having accurately machined locating surfaces arranged for abutment with accurately machined locating surfaces on the carriage, a plurality of bolts, each of which extends through aligned apertures in said knife holder and knife, one of said aligned apertures being slotted for adjustably securing said knife to said holder on that side thereof adapted to face the back plate, said bolts when loosened engaging said knife-forlocal adjustment of mage;

tudinally spaced portions of theknife'in'th-plane thereof, and 'a plurality of other-"bolts each of which extend through alig'ned? apertures m said knife holder and knifeand -into* "the' back plate for rigidly securing the assembled knifea nd knife holder to the back plate and clamping the knife between the holder and 1 back plate.

4. In a veneer cutting machine, comprising a carriage adapted for rigidly supporting the holder of a veneer cutting knife, the carriage including an elongated back plate, the improvement consisting of a knife and knife holder combination assembly installable and removable as a unit on and from the carriage respectively, said knife and knife holder being both elongated like the back plate, said knife holder having accurately machined locating surfaces arranged for abutment with accurately machined locating surfaces on the carriage, a. plurality of bolts, each of which extends through aligned apertures in said knife holder and knife, one of said aligned apertures being slotted for adjustably securing said knife to said holder on that side thereof adapted to face the back plate, said bolts when loosened permitting adjustmentas to elevation of the knife relative to the holder as a whole, a plurality of parallel push screw disposed in the plane of and behind the knife and threaded in the holder at longitudinally spaced points and abutting the plane of the push screws entered with freedom to turn in holes provided therefor in the holder and threaded in holes provided therefor in the knife at longitudinally spaced points between the push screws for local adjustments of longitudinally spaced portions of the knife in the opposite direction to that of the adjustments afforded by said push screws, and a plurality of other bolts each of which extends through aligned apertures in said knife holder and knife and into the back plate for rigidly securing the assembledknife and knife holder to the back plate and clamping the knife between the holder and back plate.

5. Ina veneer cutting machine, comprising a carriage adapted for rigidly supporting the holder of a veneer cutting knife, the carriage including an elongated back plate, the improvement consisting of a knife and knife holder combination assembly installable and removable as a unit-on and from the'carriage respectively, said knife and knife holder being both elongated like the back plate, said knife holder having accurately machined locating surfaces arranged, for-abutment with accurately machined locating surfaces on the carriage, a plurality of bolts, each of which extends through aligned apertures in said knife holder and knife, one of said aligned apertures being slotted for adjustably securing said knife to said holder, said bolts when loosened permitplane of the push screws entered with freedom to turn in holes provided therefor in the holder andthreafied iniholes'iprovfided therefor in the Y e 1 knife at Jang-itudinamrspaced points 'between'the l FERENCES CITED P screws mal'fidjustments longitudi" The following references are 01' record in the nally spaced portions of theknife in the opposite m f this patent;

tobhagb the adjustments affordedby- 5 said push screws,; and a plurality of'other bolts, N E STATES PATENTS extending through'apertures in said knife holder' N m r Name Date into the back plate'for, rigidly securin'githe, as- 835,156 Fitts Nov. 6, 1906 sembled knife and knife holder to the back plate. 1,890,532 7 K058, 1386- 3, 1932 e I r v n h 1 V Y 10 1,957,166 Hartzell "May1.',1934

,' 1 ERICSSONiH. MERRITT. 2,337,407 Otterslgnd Dec. 21,1943