Reciprocating knife tool

The material forming the support surface 18 of the table is one which allows the knife of the cutter head to penetrate into it during a cutting operation. This material may vary widely, but preferably it consists of a plurality of bristle elements or blocks fitted together to form a continuous bristled bed, as disclosed in the aforementioned U. A tool mount 22, which forms a part of the cutter head 12, is supported on an X-carriage 24 by two guides bars 26, 26, for movement in the illustrated Y-coordinate direction.

At each of its opposite ends, the X-carriage 24 is guided for movement relative to the table 14 in the illustrated X-coordinate direction. Suitable drive motors and associated drive trains, under the control of the controller 16, move the tool mount 22 and X-carriage Thus, by combined movement of the X-carriage 24 in the X-coordinate direction and the tool mount 22 in the Y-coordinate direction the cutter head 12 may be made to follow any desired line of cut on the sheet 20 to cut pattern parts or other similar components from the sheet, one such line of cut being indicated at 28 and one such pattern piece being indicated at It should be understood, that while the cutting table 14 is shown in FIG.

As shown best in FIG. A knife frame 36 is carried by the base frame 32 for rotation relative to the base frame about a vertical axis The knife frame 36 in turn has affixed to it a guide 40 which engages the lower part 42 of an elongated knife 44 and restrains the knife to reciprocating motion along the longitudinal axis 45 of the knife see FIGS. A presser foot 46 is supported on the base frame 32 for vertical sliding movement relative to the base frame and is biased by one or more springs, such as the springs shown at 48 and 49, to its lowermost position.

When the frame 32 is lowered from its FIG. The motor 50 for driving the knife 44 is carried by the base frame 32 and is drivingly connected with an eccentric mechanism, indicated generally at 52, carried by the knife frame 36 through a pulley and belt drive train, indicated generally at This arrangement allows the knife frame 36 to rotate about the vertical axis 38 relative to the base frame 32 and motor 50 while, nevertheless, the motor 50 delivers power to the eccentric drive mechanism 52 at all angular positions of the knife frame about the axis The knife frame 36 is positioned about the axis 38 under the control of the controller 16 and by a motor 56 carried by the base frame The motor 56 is drivingly connected with the knife frame 36 through gears 58 and As those skilled in the art will recognize, the invention is not limited to this arrangement, and, although not illustrated, the motor 50 could have its shaft directly coupled to the eccentric.

Referring now to FIGS. The knife 44 also includes an upper or drive part 64 which is connected with the eccentric mechanism Preferably, the knife 44 is constructed as a single piece so that when making a knife replacement the entire knife, including both the lower part 42 and the upper part 64, is removed and replaced by a similar new, thin, one-piece knife.

The invention is not, however, limited to this particular construction, and in some cases the upper part 64 may be made as a separate member releasably connected to the lower part 42 which forms another separate member, thereby allowing the lower part to be removed and replaced without at the same time removing and replacing the upper part Turning now to the eccentric mechanism 52 and still referring to FIGS.

The crank member 66 is drivingly connected to the pulley and belt drive train 54 for rotation about horizontal eccentric drive axis The eccentric mechanism further includes a bearing 70 carried by the crank member 66 at a position spaced from the eccentric axis 68 so that the bearing has a given eccentricity. Eccentric drive pins 72 and 74 are supported within the bearing 70 so that the pins rotate with the bearing about eccentric drive axis 68 as the crank member is driven by the motor The drive pins 72, 74 extend outwardly from bearing 70 parallel to the eccentric drive axis 68 and through apertures formed in the upper end 76 of the knife's upper part Thus, the pins are drivingly connected to the knife 44 and reciprocate the knife in a plane perpendicular to the eccentric drive axis as the crank member rotates.

Preferably, the upper part of the knife is releasably connected to the pins so that the knife can be easily removed from the cutter head 12 and replaced.

In the illustrated embodiment, the apertures are sized so that the knife is simply pressed onto the pins manually. The knife is maintained in engagement with the pins by friction and by a retaining member 78 which is mounted to the knife frame 36 by screw 80 for rotation between a retaining position illustrated and a release position not shown.

It is important to note here that in the retaining position, the retaining member 78 is in sliding engagement with the upper part 64 of the knife 44 as the knife is reciprocated. Thus, the retaining member also serves to dampen vibrations that tend to develop in the knife during reciprocation. As illustrated in the drawings, the guide 40 is located vertically below the eccentric drive mechanism 52 and has a slot 82 formed therein for receiving the knife The slot 82 is dimensioned such that when the knife is received therein, the guide and knife are in engagement.

The knife and guide are constrained by this engagement to slide relative to one another along the longitudinal axis 45 of the knife as the knife is reciprocated. To accommodate this arrangement regardless of the position of the knife during its reciprocation, the guide 40 is pivotally mounted to the knife frame 36 by guide pin 84 for oscillation about pivot axis 86 which extends parallel to eccentric drive axis Thus, as shown in FIGS.

From the foregoing description, it will be understood that the knife 44 does not present an attack angle which is perpendicular to the sheet material 20, as is the case with prior art cutters wherein the knife is restricted to reciprocation along a vertical axis. Instead, as the cutter head 12 is caused to move along a line of cut on the sheet material in the direction indicated by arrow A, the cutting edge 62 of the knife follows an arcuate path, wherein during the knife's downward stroke the cutting edge moves and forward with respect to the line of cut, and during the knife's upward stroke the cutting edge moves rearward with respect to the line of cut.

Thus, the reciprocating knife accomplishes substantially more cutting of the sheet material on its downstroke when the cutting edge is moving forward with respect to the line of cut than it does on the upstroke when the cutting edge is moving rearwardly with respect to the line of cut. This being the case, the knife's arcuate cutting path significantly reduces the tendency of the knife to lift the sheet material during its upstroke; accordingly, much less vacuum is required to hold the sheet material 20 in place against the support surface 18 during a cutting operation.

In some cutting operations, particularly where only one or two plys of heavier sheet materials are being cut, little or no vacuum is required to hold the sheet material in place during the cutting operation. Accordingly, the action of the knife can be reversed by simply reversing the direction in which the eccentric crank member rotates.

In the illustrated embodiment this is accomplished by reversing the direction of rotation of the motor Thus, as the knife 44 is reciprocated and the cutter head moves along a line of cut, the edge 62 is moved rearwardly with respect to the line of cut on its downstroke and forwardly with respect to the line of cut on its upstroke.

When the cutting head is operated in this manner, the cutting edge of the knife cuts the sheet material primarily on its upstroke. A second embodiment of a cutter head constructed according to the invention is illustrated in FIG. As shown in FIG. The block 88 is slidably mounted on the knife frame 36 for horizontal movement with respect to the vertical axis 38 between a first position, which is the position illustrated in FIGS.

When the block 88 is in the full line position, the pivot axis 86 is no longer located vertically below the eccentric drive axis Accordingly, the cutting edge 62 of the knife is caused to adopt a more perpendicular attack angle with respect to the sheet material on the downstroke of the knife.

Conversely, the rearward movement of the cutting edge 62 is increased as compared with that provided when the pivot axis is located vertically below the eccentric drive axis. Of course, the invention is not limited to horizontal movement of the block 88 between the first and second positions illustrated in FIG.

In fact, the cutter head 12 is constructed so that the block 88 is moveable horizontally among an infinite number of positions with respect to the vertical axis Thus, the arcuate path of the cutting edge 62 can be precisely adjusted to meet the demands of each particular cutting operation.

Of course, further modifications of the arcuate path of the cutting edge can be obtained by constructing the cutter head so that the block 88 may be positioned on the frame at any angle with respect to the vertical axis As mentioned previously, the present invention also provides a cutting apparatus having a knife sharpener. This aspect of the invention will be described in connection with the cutting apparatus However, it should be understood that the invention is in no way limited in this regard and that this aspect of the invention encompasses cutting apparatus of the general type wherein sheet material is supported on a cutting table during a cutting operation, and a carriage supports a cutting head including a knife above the cutting table for relative movement therewith in at least two coordinate directions.

In one embodiment, as shown in FIGS. The strip is formed from any abrasive material suitable for sharpening the cutting edge 62, such as, for example, sandpaper or abrasive cloth.

When sharpening is needed, the cutter head 12 is moved to a position on the X-carriage 24 so that when the base frame 32 is adjusted vertically on the guide rods 34, 34, the cutting edge of the knife contacts the abrasive strip The X-carriage is then moved in the X coordinate direction along the table 14 while the knife is reciprocated to achieve the desired sharpening.

Accordingly, as shown in FIG. For example, the foam layer is adhesively mounted on the wall , and the abrasive strip is adhesively attached to the foam layer.

Thus, as the knife is moved along the strip and is reciprocated against it, the foam layer compresses and provides the required resiliency. Of course, reciprocation of the knife 44 while in contact with the abrasive strip is not required.

As those skilled in the art will recognize, simple linear movement of the knife in contact with the strip provides sufficient abrasion for sharpening.

In a second embodiment of such a sharpener, the X-carriage is held stationary and the strip is oscillated back and forth in contact with the knife 44 to effect sharpening. This is accomplished, for example, by providing a rigid backing which supports the foam layer and the abrasive strip and coupling the backing to a vibrator which is mounted on or within the vertical side wall In such an arrangement, the knife remains stationary as the strip is oscillated, or sharpening may be accomplished by combined oscillation of the strip and reciprocation of the knife Alternatively, the strip is provided as an endless abrasive belt which is advanced by suitable drive pulleys and a drive motor mounted on the side wall As in the above embodiment, the knife remains stationary as the strip is oscillated, or sharpening may be accomplished by combined movement of the abrasive belt and reciprocation of the knife In order to reduce down time of the apparatus 10, the cutting edge 62 is sharpened between cutting operations as a fresh piece of the sheet material 20 is placed in a spread condition on the support surface 18, or when necessary.

In the case of a conveyorized cutting table, additional sharpening is accomplished as the conveyor moves an un-cut segment of the material in place beneath the cutter head between successive cutting operations. In the illustrated embodiment a sharpener is mounted on both ends of the X-carriage; however, the invention encompasses an arrangement wherein a sharpener is mounted on one end of the carriage. The sharpener, generally designated , is mounted on a support bracket extending horizontally from the X-carriage.

The sharpener includes an arm rigidly fixed to a hub supported on the bracket for rotation about a vertical axis Supported on the outer end of the arm for rotation relative to it about a second vertical axis is a sharpening wheel consisting of a body having a drive groove intermediate its top and bottom ends and an abrasive grit bonded to the outer surface of the body.

The sharpening wheel is driven in rotation about the second vertical axis by a motor through a pulley and an O-ring drive belt engaging the wheel's drive groove A tension spring normally holds the arm in a retracted position against a stop as shown in the broken lines of FIG. From this position, the arm is moveable to an active sharpening position shown by the solid lines of FIG. To effect this movement of the arm , the sharpener further includes a rotary solenoid actuator having an output member rotatable about a vertical axis and carrying a vertically extending pin When the solenoid is de-energized, the pin is biased by an internal spring not shown to the position shown by the broken lines in FIG.

When the solenoid is energized, the pin rotates clockwise about the axis from the broken line position to the full line position illustrated in FIG. In the course of this movement the vertical pin engages a horizontal pin fixed to the hub thereby rotating the arm from its retracted to its active position. During a sharpening operation, which preferably takes place between cutting operations, the controller 16 directs the cutter head 12 to a position on the X-carriage adjacent the sharpener , and, if required, the base frame 32 is adjusted vertically on the guide rods 34, 34 to the appropriate position.

The blade 44 is then rotated by the motor 56 to the proper position about the axis 38 for sharpening and the sharpening wheel is brought into contact with the cutting edge 62 by swinging the arm During sharpening, the wheel is rotated while the knife 44 is reciprocated to insure that the sharpening wheel engages the full extent of the cutting edge While preferred embodiments have been shown and described, various modifications and substitutions may be made without departing from the spirit and scope of the invention.

For example, the sharpener could be mounted on either or both of the vertical end walls of the cutting table Those skilled in the art will readily appreciated that to perform a sharpening operation with such an arrangement, the controller 16 directs the X-carriage to the appropriate end of the table and directs the cutter head 12 to a location on the carriage so that the sharpening wheel contacts the cutting edge 62 of the knife 44 when the wheel is swung into its active position.

The wheel is then rotated and the knife reciprocated, as described above, to effect sharpening of the cutting edge. Accordingly, it is to be understood that the present invention has been described by way of example and not by limitation. I claim: 1. A reciprocating knife cutter comprising: a frame;.

The knife cutter of claim 1 wherein said guide pivotally supports the lower part of the knife for oscillation about a pivot axis disposed parallel to the eccentric drive axis and fixed relative to the frame at a position vertically below the drive axis. The knife cutter of claim 2 wherein the guide oscillates about the pivot axis in the plane perpendicular to the eccentric drive axis, and the knife and the guide are engaged to slide relative to one another along the longitudinal axis of the knife.

The knife cutter of claim 3 wherein said guide and knife are constrained by said engagement to slide relative to one another along the longitudinal axis of said knife as said upper part of said knife is rotated by said eccentric drive member.

The knife cutter of claim 1 wherein said block is movable relative to said frame in the plane perpendicular to said eccentric drive axis. Preferably, the lower slot 46 is sized to accommodate the reciprocation limits of the ends of the springs 64 and 65 which are fastened to the blade.

The spring ends fastened to the blade 12 may be secured to the screws Preferably, screws 66, which threadably engage holes 67, are provided for securing the springs 64 and 65 to the lower guide member While extension springs are shown as the preferred biasing means, it is understood that other biasing means such as compression springs or elastic bands will be evident to those skilled in the art and are included within the scope of this invention.

The blade drive 48 of the improved reciprocating knife 10 must be mounted such that the shaft 50 is free to rotate in its position adjacent to the blade guide 24, and that rotation of the shaft 50 results in the desired blade reciprocation.

The mounting means of the preferred embodiment, as shown in FIG. A cap 70 is positioned to limit the extent to which the shaft 50 may be inserted through the first bearing aperture A second bearing 72 is preferably secured to the blade guide 24 and has a second bearing aperture 74 which receives a portion of the shaft rearward of shaft rearward of the cam plate A collar stop 75 is secured to the blade guide 24 and has a channel 76 through which the shaft 50 passes without obstruction; and an adjustable collar 78 is reversibly secured by means of set screw 80 to the shaft 50 between the cap 70 and the collar stop The collar 78 is sized such that it is unable to pass through the channel Thus, the collar 78 may be advanced to the collar stop 75 to adjust the fit of the shaft 50 between the collar stop and the cap Moreover, should the forward end 57 of the shaft 50 become worn, the collar 78 may be repositioned along the shaft until the desired fit is again attained.

Any of the bearings 68 and 72, and the cap 70 and the collar stop 75 may be integrally formed with the upper guide member 32 or, alternatively, as shown for the collar stop in FIG.

When separately formed as shown in FIG. The collar stop 75 in FIG. However, it will be understood that various drive shafts can be used in this improved knife with each of such drive shafts having a cam plate inclined at a different angle such that the stroke of reciprocation of the blade 12 can be selectively varied as desired.

It is understood that the front 14 of the blade 12 may be elongated and provided with a cutting edge. However, the improved reciprocating knife 10 preferably has a cutting blade section 89 which may be selectively affixed to and removed from the front of the blade Such reversible assembly may be accomplished using fitted screws 90 as shown in FIG.

A casing shown generally at 91 is preferably provided for protecting the operator of the improved reciprocating knife and for providing a grasping surface for a knife operator to hold. As seen in FIG. The forward portion 92 is fixedly engaged to the body 94 and is enlarged somewhat beyond the outer limits of the body in order to act as a safety stop for the operator's hand.

The rearward casing hole 97 is centered with respect to the rearward portion 96 to allow rotation of the rearward portion with the shaft extended therethrough. In assembling the knife components of the preferred embodiment wherein the bearings 68 and 72 and the cap 70 are integrally formed with the upper guide member 32 as shown in FIG.

The collar stop 75 is also secured to the upper guide member 32 with the screws The rearward blade section 16 is placed within the track 26 created by the assembled guide members 27 and 32 and the reinforcing drive disks 20 are fastened to the blade 12 using screws The biasing springs 64 and 65 are secured to the lower guide member 27 using screws 66 and to the blade 12 using the adjacent ends of the screws The collar 78 is suitably placed on the shaft 50 rearward of the cam plate 56 with the set screw 80 loosened.

The rearward end 52 of the shaft 50 may then be inserted through the second bearing aperture 74 and the forward end 57 inserted through the first bearing aperture 69 and advanced to the cap The positioning of the shaft 50 within the bearing apertures 69 and 74 is done while inserting a portion of the cam plate 56 into the guide aperture 42 between the ears 19 of the blade opening 17; and while inserting the shaft 50 within the collar stop channel The collar 78 may then be advanced along the shaft to the collar stop 75 and the set screw 80 tightened.

The blade front 14 is then inserted through the forward casing hole 93 with the body 94 of the casing 91 surrounding the blade guide 24, the cam plate 56, the bearings 68 and 72, and the cap The rearward casing hole 97 is placed around the shaft 50 and the rearward casing portion 96 is then threaded to the rearward end 95 of the casing body The cable 54 may then be threaded onto the rearward shaft end The cutting blade section 89 is secured to the blade 12 near its front 14 using screws The cable 54 extends from a suitable conventional power supply means such as an electric motor not shown.

When the power supply means is operated it imparts a rotational movement to the cable Rotation of the cable 54 will in turn impart rotational movement to the drive shaft 50 and hence to the cam plate Since the cam plate is disposed at an angle within the reinforced rim 18 of the blade opening 17, the plate surfaces 58 and 60 engage the rim upon rotation of the cam plate and alternately move the blade 12 forwardly and rearwardly within the track Such movement is by the springs 64 and 65 alternately aided and resisted during the reciprocating cycle as the blade position moves toward and away from a position generally midway between the forwardmost and rearwardmost position of the blade The improved reciprocating knife 10 is preferably formed of stainless steel or some other noncorrosive and rustproof material.

The bearings 68 and 72 may alternatively be formed of brass or other suitable materials. To increase bearing efficiency a solid lubricant such as powdered graphite or self-lubricating plastic may be impregnated into the walls of the bearing apertures 69 and As will be apparent, there are a minimum number of cooperating parts within the casing 91 and accordingly, operation of the improved reciprocating knife 10 is greatly simplified.

Parts such as the drive disks 20, the springs 64 and 65, and the cutting blade section 89 may be easily replaced without substantial loss of time. Moreover, even if moisture were to work its way into the casing 91, the knife would still continue to function in a satisfactory manner.

It will also be seen that the entire knife 10 can be easily cleaned by merely immersing it in water. The materials, parts, and methods of assembly disclosed above are those preferred by the inventor. It is understood that the present invention is not limited to the particular materials, construction, arrangement of parts, and methods illustrated and disclosed above.

Instead, it embraces all such modified forms thereof as come within the scope of the following claims. What is claimed is: 1. An improved reciprocating knife comprising:.

The improved reciprocating knife of claim 1 wherein the elastic members are balanced to bias the blade to a position generally midway between its forward position and its rearward position. The improved reciprocating knife of claim 1 wherein the two opposed elastic members are springs, the first spring biasing the blade toward its forward position and the second spring biasing the blade toward its rearward position.

The improved reciprocating knife of claim 1 further including a cutting blade section which has a cutting edge and may be selectively affixed to and removed from the front of the blade. The improved reciprocating knife of claim 4 wherein the cutting blade section is affixed to the blade by screws. The improved reciprocating knife of claim 1 further comprising reinforcing means for reinforcing the rim of the blade opening. The improved reciprocating knife of claim 6 wherein the blade opening is generally H-shaped with a pair of rounded ears projecting longitudinally toward each other; and wherein the reinforcing means comprises a pair of drive disks mounted to the blade such that the disk circumferences reinforce the ear portions of the rim.

The improved reciprocating knife of claim 1 wherein said mounting means includes a first bearing which is secured to the blade guide and has a first bearing aperture which receives a portion of the shaft forward of the cam plate; a cap for limiting the extent to which the shaft may be inserted through the first bearing aperture; a second bearing secured to the blade guide and has a second bearing aperture which receives a portion of the shaft rearward of the cam plate; a collar stop which is secured to the blade guide and has a channel through which the shaft passes without obstruction; and an adjusting collar which is unable to pass through the channel and is reversibly secured to the shaft between the cap and the collar stop such that the fit of the shaft between the cap and the collar stop may be adjusted.

The improved reciprocating knife of claim 1 further comprising a casing which substantially encloses said blade guide, said mounting means, and said blade drive so as to provide a grasping surface for a knife operator to hold, said casing having a forward casing hole through which the blade extends and a rearward casing hole adapted to allow connection of the shaft to the drive means.

An improved reciprocating knife comprising: a an elongated blade having a front, a rear, and a rearward blade section having a blade opening with a rim of selected shape;. The improved reciprocating knife of claim 10 wherein the blade opening is generally H-shaped with a pair of rounded ears projecting longitudinally toward each other; wherein the rim of the blade opening is reinforced by a pair of drive disks reversibly mounted to the surface of the blade facing the blade drive such that the disk circumferences reinforce the ear portions of the rim; and wherein the upper slot is sized to allow the drive disks to move therein as the blade reciprocates.

The improved reciprocating knife of claim 10 wherein the springs are extension springs and the ends of the first spring are respectively fastened to the lower guide member forward of the lower slot and to the blade forward of the blade opening, and the ends of the second spring are respectively fastened to the lower guide member rearward of the lower slot and to the blade rearward of the blade opening.

The improved reciprocating knife of claim 12 wherein the rim of the blade opening is longitudinally reinforced by forward and rearward replaceable drive disks, each disk reversibly secured by a screw to the surface of the blade facing the blade drive; wherein the upper slot is sized to allow the drive disks to move therein as the blade reciprocates; wherein the end of the first spring fastened to the blade is attached to the screw securing the forward drive disk, and the end of the second spring fastened to the blade is attached to the screw securing the rearward drive disk; and wherein the lower slot is sized to accommodate the reciprocation limits of the spring ends fastened to the blade.

The improved reciprocating knife of claim 10 wherein said mounting means includes a first bearing which is secured to the blade guide and has a first bearing aperture which receives a portion of the shaft forward of the cam plate; a cap for limiting the extent to which the shaft may be inserted through the first bearing aperture; a second bearing which is secured to the blade guide and has a second bearing aperture which receives a portion of the shaft rearward of the cam plate; a collar stop which is secured to the blade guide and has a channel through which the shaft passes without obstruction; and an adjusting collar which is unable to pass through the channel and is reversibly secured to the shaft between the cap and the collar stop such that the fit of the shaft between the cap and the collar stop may be adjusted.

The improved reciprocating knife of claim 10 further including a cutting blade section which has a cutting edge and may be selectively affixed to and removed from the front of the blade. The improved reciprocating knife of claim 15 wherein the cutting blade section is affixed to the blade by screws.

The improved reciprocating knife of claim 10 further comprising a casing which substantially encloses said blade guide, said mounting means, and said blade drive so as to provide a grasping surface for a knife operator to hold, said casing having a forward casing hole through which the blade extends and a rearward casing hole adapted to allow connection of the shaft to the drive means.

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