US2760533A - Wood slicing machine - Google Patents

Description

Aug. 28, 1956 D. E. BASS 2,760,533

woon SLICING MACHINE Filed June 10, 1955 x IO x 4 3%.

/ QAT- a QMEY/ United States Patent 2,760,533 wool) sucnso MACHINE Donald E. Bass, Rockford, Ill., assignor to Balsa Processing Company, Inc., Rockford, KL, a corporation of Illinois Application June 10, 1953, Serial No. 360,761

1 Claim. (Cl. 144-162) This invention relates generally to a wood slicing machine and, more particularly, to av machine in which a soft wood such as balsa is sliced into thin sheets by a knife blade mounted to reciprocate into and out of engagement with a workpiece and having a cutting edge spaced laterally from a metering board a distance equal to the thickness of sheets to be cut. The metering board reciprocates with the knife and limits the feeding movement of the workpiece after each sheet is cut therefrom. To avoid crushing of the soft wood, it is desirable to use a knife having a very sharp cutting. edge.

One object of the invention is to. construct a machine of the above character in a novel. manner to avoid dulling of the cutting edge of the knife and to insure that one sheet will be separated completely from. the workpiece during each reciprocation of the knife.

Another object is to avoid dulling ofv the knife blade through. the provision of a yieldable material which supports the workpiece adjacent the point where it is cut by the knife and which is mounted in a novel manner to maintain the material out of contact with the metering board.

A further object is to pull each sheet away from the workpiece and break. any fibres holding the two together during the retracting movement of the knife through the provision of novel gripping elements which permit movement of the sheet along the knife in the advance of the latter but hold the sheet frictionally against reverse movement relative to the knife during retraction thereof.

Other objects and advantages of the invention will become apparent from. the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a fragmentary perspective view of a wood slicing machine embodying the novel features of the present invention, some of the parts being shown in section.

Fig. 2 is an enlarged fragmentary sectional view taken 2 In the drawings, the invention is shown for purposes or illustration embodied in a wood slicing machine of the type in which an elongated knife 19 having a straight cutting edge 13 is reciprocated relative to and toward and away from a table Hand into and out of engagement with a workpiece 13 on the table to slice :1 thin sheet 14 from one end portion of the workpiece. In this instance, the table is stationarily supported as bya' suitable frame not shown) and has a hat horizontal top'15 defining a work supporting surface and terminating along one edge at a flat vetrically disposed end 16. The workpiece 13' is a generally rectangular block having one flat surface resting onthe table top.

The knife 10- is a fiat elongated generally rectangular blade whose cuttingedge 11 extends longitudinally of the blade and is defined by the intersection of a flat side 17, and a hollow ground surface E8 of the blade. Tov prevent is: in its raised position.

crushing. of the workpiece 13 when the latter is a soft wood such as balsa, the cutting edge 11 is made very sharp, the surfaces 1'7 and 18 defining the edge in this instance intersecting. at. an angle of between 14 degrees and 18 degrees. The knife is secured as by screws to an elongated horizontally disposed holder 19- which supports the knife in a vertical' plane above the table 12 with the cutting edge 11 pointing downwardly toward the table and disposed horizontally and parallel to the flat table end 16.

Supporting the knife 10' and its holder 19 for reciprocating movement relative to the table 12 is an elongated slide 21 connected rigidly at its opposite ends to the knife holder by bolts 22. The slide is suitably mounted for reciprocation of the knife in a vertical plane and back and forth between a raised position spaced above the workpiece as shown in Fig. 3 and a lower position (see Figs. 1 and 2) in which the cutting edge 11 engages the table top 15 along a line parallel to. and spaced from the flat table end 16. Such mounting of the slidev 21 may comprise stationary guides (not shown which are received in straight parallel slots 23 formed in the slide. To obtain a broad- Wise movement of the knife toward and away from the table 12 so that the cutting, edge 11 passes through the workpiece 1'3 with a slicing action, the guide slots 23, While lying in. a vertical plane, are inclined away from the vertical at an angle of approximately 35 degrees. With this mounting of the slide 21, the cutting edge 11 is shifted back and forth horizontally while it reciprocates in a vertical plane and maintains itsparallel relation with the table top 15. Reciprocation of the slide and the knife may be effected in any suitable manner as by a crank or hydraulic actuator whose. stroke may be adjusted to vary the stroke of the knife.

During the advance of the knife 10 toward the table 12 the workpiece 13" is held against movement relative to the table top 15 by a veiticall'y reciprocable clamping member 24 which is suitably mounted for reciprocationverticall'y into and outof engagement with the workpiece and which is raised in timed relation toand after retraction of the knife to its-raised position to permit the workpiece to be advanced. under the knife and toward the flat tableend 16. Such advance may be' eifected in any suitable manner as by a pressure bar 25' engaging the rear end of the workpiece and acting under continuous pressure derived from springs or the like to urge the work continuously toward the fiat table end 16.. As the knife descends in its advancing movement, the clamping member 24 isactuated to hold the workpiece against the table top;

Feeding movement of the workpiece 1-3 is limited by a flat elongated metering board or stop member 26 which reciprocates vertically with the knife 10 and back and forth across the Hat table end 16 and which is positioned below the knife to project above the table top 15 and engage the workpiece as shown in Fig. 3 when the knife in this instance, the board is mounted on the knife: slide 21 through the medium of guides 27 rigid with: the slide. and slidably receiving two spaced. horizontalguide rods: 28 secured at opposite ends to arms 29 projecting rigidly from the side of the board opposite the table. With this construction, movement of the board may be. limited to vertical reciprocation while the knife 10 andv the knife slide 21 shift horizontally,

endwise movement of the board being prevented by rollers equal to the desired thickness of sheets to be cut, herein approximately of an inch. If desired, the work engaging surface of the board may be covered with a thin sheet (not shown) of stainless steel to facilitate movement of this surface across the adjacent end of the workpiece 13.

To prevent dulling of the knife cutting edge 11 resulting from its engagement with the table top 15, it is desirable to support the workpiece 14 adjacent the flat table end 16 on a strip 32 of yieldable and preferably resilient material such as rubber which the cutting edge enters as shown in Fig. 2 in the lower position of the knife. spreads the yieldable material thereof laterally of the knife and toward the closely adjacent reciprocating metering board 26 which, when it contacts the yieldable material, tends to curl and break off the edge of the latter due to the friction and relative movement between the two.

In accordance with one aspect of the invention, the strip 32 of yieldable material is mounted in the table 12 in a novel manner to avoid the foregoing difficulty and permit the use of the material where, as in the present instance, the spacing between the cutting edge 11 and the reciprocating metering board 26 is very small. This is accomplished by interposing between the strip and the metering board a very thin plate 33 of material, preferably metal, which is harder than the yieldable strip 32 and maintains the latter out of engagement with the metering board. To insure that the cutting edge 11 of the knife always engages the strip of yieldable material, the metal plate 33 is made much thinner than the spacing between the cutting edge and the board and herein is from .032 to .040 of an inch thick. The plate extends along and defines the upper part of the fiat table end 16 and, along its upper edge, defines the edge of the table top 15 and provides a rigid backing for each sheet being cut.

It has been found in service use that the strip 32 of yieldable material requires frequent replacement. To facilitate such replacement, the strip and the metal plate 33 are formed as parts of a removable backing unit 34 which fits into a recess 35 of right angular cross section cut into and extending along the flat table end 16. In the form shown in Fig. 2, this unit 34 comprises a wooden rectangular base 36 adapted to fit into the bottom of the table recess 35, the plate 33 which is secured to one side of the base 36 by screws 37 and projects above the base, and the strip 32 of yieldable material which is a rectangular block of rubber bonded to the plate and the base and flush on its outer surface with the top edge .of the plate and the fiat table top 15 to constitute a part of the latter. The unit is suitably secured to the table 12 as by screws (not shown) threaded into the base 36 and extending upwardly through the underside of the table. In this instance, the plate 33 is made of a metal such as brass which is softer than the steel work engaging surface of the metering board 26 so as to avoid scratching this surface. The rubber strip 32 is one quarter of an inch thick.

If desired, the backing unit 34 may be constructed as shown in Fig. 3 with two of the metal plates 33 disposed parallel to each other and extending along opposite sides of the unit to enable the latter to be reversed to provide a new section of the yieldable strip 32 for the knife cutting edge 11 when the portion of the strip adjacent one of the plates becomes worn. In this instance, the two plates are the parallel leg portions of a channel 38 of U-shaped cross section filled with the yieldable material 32 molded in the channel and bonded to the inner sides of the metal plates. To strengthen the bottom wall of the channel for attachment to the table 12 as by screws 39, a thin steel plate 41 lies along the bottom wall between the latter and the yieldable material. In this form of backing unit, the channel walls are each .032 of an inch thick, the yieldable material 32 is rubber one quarter of an inch thick,

Such entry of the cutting edge into the strip '4. and the bottom plate 41 is made of steel one eighth of an inch thick.

When the cutting edge 11 of the knife 10 is protected by a yieldable backing material as described above, it has been found that some sheets 14 being cut from the workpiece 13 remain attached to the latter after the cutting movement of the knife by a few fibers which are pushed into the backingand thus are not completely severed by the cutting edge. As a result, the sheet being cut, instead of moving upwardly with the knifeand the metering board 26 in the retracting movement of the knife, remains against the table top 15 and prevents feeding movement of the workpiece toward the metering board.

In accordance with another aspect of the invention, complete severance of each sheet from the workpiece 13 is insured by frictionally gripping each sheet 14 in a novel manner and pulling the same away from the workpiece in the upward movement of the knife 10 and the metering board 26. For this purpose, gripping elements 42 are mounted on the metering board 26 and project toward the knife and to a position spaced from the latter a distance less than the thickness of each sheet 14. The gripping elements 42 are yieldably urged toward the knife to clamp each sheet against the latter and prevent downward movement of the sheet relative to the knife while permitting the sheet to pass upwardly between the elements and the knife.

In this instance, the gripping elements 42 are the free squared ends of a series of-flat spring fingers 43 fixed as by screws at their other ends to the metering board 26 at spaced points along the latter and each projecting upwardlytoward the hollow ground knife surface 18. The'latter faces downwardly toward the metering board and cooperates with the board to define achannel through which each sheet 14 being cut advances in the downward movement of the cutting edge 11 through the workpiece 13. The intermediate body portions of the fingers are curved inwardly from the metering board toward the knife 10 to position the free ends 42 closely adjacent the ground knife surface 18 and provide tensioning means yieldably urginglthe free ends toward the knife. The force exerted by the spring fingers 43 on the free gripping ends 42 is sufficient to clamp each sheet 14 against the knife to prevent reverse movement of the sheet downwardly along the knife while permitting these gripping ends to move outwardly away from the knife for movement of each sheet upwardly along the latter. When the knife shifts horizontally relative to the metering board 26 during vertical movement of the two together, the sheet and the outer ends 42 of the fingers 43 tend to shift horizontally with the knife as permitted by the'flexibility of the fingers.

During downward movement of the knife 10 and metering board 26 in the operation of the machine, the workpiece 13 is held stationary against the table top 15 by the clamping member 24 and the cutting edge 11 slices from the workpiece a sheet 14 equal in thickness to the spacing between the cutting edge and the metering board. This sheet moves upwardly relative to and along the hollow' ground knife surface 18 and between the latter and the free ends 42 of the spring fingers 43 as permitted by flexing of the fingers outwardly away from the knife. As the knife reaches the bottom of its stroke, the cutting edgeenters the yieldable strip 32 and tends to spread the latter. toward the metering board. Due to the confining action of the metal plate 33, however, the strip isprotected from contact with the board.

As the knife 10 and metering board 26 move upwardly relative to the table 12,'the free ends 42 of the fingers 43 hold the sheet against and in frictional engagement with the adjacent knife surface 18 so that the sheet is pulled away from the workpiece 13 to break any fibres still connecting the two and not cut by the knife. When the knife and the board reachytheir upper positions, the clamping member. 24 is released and the workpiece is permitted to slide along the table top 15 toward and into abutting engagement with the board under the action of the pressure bar 25. As the knife begins to descend out before the cutting edge engages the workpiece, the clamping member 24 is actuated to hold the workpiece against the table top 15. The sheet 14 just cut off is retained between the knife and the gripping finger ends until the knife begins its next advancing movement and then is engaged by the upper edge of the next sheet which forces the preceding sheet upwardly and out from between the knife and the finger ends. The freed sheet may then be transferred away from the machine either manually or by a conveyor moving behind the metering board.

I claim as my invention:

In a wood slicing machine, the combination of a table having a flat work supporting surface, an elongated flat metering board extending along and mounted to reciprooate back and forth across one end of said table in a plane extending transversely of said fiat table surface, a knife mounted to reciprocate with said board in a plane parallel to said plane of board reciprocations and having a straight cutting edge disposed parallel to and spaced from the side of said board adjacent said table and movable toward and away from the table during reciprocating movement of the knife to cut ofi sheets from the end portion of -a workpiece advanced along said table surface and into engagement with said board, each of said sheets passing between said board and said knife during the cutting operation, and a plurality of spring fingers secured to said board at spaced points along the latter and projecting from the board toward said knife and to positions spaced from the knife shorter distances than the spacing between said cutting edge and said board to engage each sheet passing between the board and the knife and hold the sheet frictionally against the knife whereby the sheet is pulled away from the workpiece in the retracting movement of the knife.

References Cited in the file of this patent UNITED STATES PATENTS 958,395 Helm May 17, 1910 1,123,386 Russell Jan. 5, 1915 1,815,670 Haworth July 21, 1931 2,007,731 Tomlin July 9, 1935 2,532,672 Michael Dec. 5, 1950 2,592,782 Zweifel Apr. 15, 1952

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