SUPER SPEED VENEER CLIPPERS
United States Patent 3837250
This veneer clipper comprises a frame, infeed and outfeed veneer conveyor means, a reciprocable clipper blade, an anvil positioned so the blade will cut the moving veneer against it, pneumatic means for imparting cutting strokes to the blade at super speed, blade actuating means connecting the pneumatic means with the blade and spring means cooperating with the blade actuating means in such a manner as to make possible super speed cutting strokes of the blade, while at the same time, minimizing shock and vibration by cushioning retractile strokes of the blade.
US Patent References:
Veneer clippers
Michael et al. - December 1950 - 2532672
Veneer clippers
McFall - June 1955 - 2711792
SHEARING DEVICE FOR WEB STRIPS
Gesell - March 1971 - 3568556
Veneer clippers
Michael et al. - December 1950 - 2532672
Veneer clippers
McFall - June 1955 - 2711792
SHEARING DEVICE FOR WEB STRIPS
Gesell - March 1971 - 3568556
Application Number:
05/299040
Publication Date:
09/24/1974
Filing Date:
10/19/1972
View Patent Images:
Export Citation:
Assignee:
Globe Machine Manufacturing Co., Ltd. (Tacoma, WA)
Primary Class:
Other Classes:
83/659, 83/630, 83/639.700, 83/356.200, 83/223, 83/586
International Classes:
B27L5/08; B27L5/00; B27L5/08; B26D5/18; B26D5/12
Field of Search:
83/223,582,585,586,617,625,630,639,659,424,356.2
Primary Examiner:
Schran, Donald R.
Attorney, Agent or Firm:
Matheny, Fred C.
Claims:
I claim
1. A veneer clipper comprising a frame; a normally horizontal anvil supported by said frame; a clipper blade guided by said frame for reciprocable cutting and retractile movement toward and away from said anvil; conveyor means operable in feeding veneer between said anvil and said blade; a blade actuating bar supported for longitudinal reciprocating movement above said blade and approximately parallel to said blade; a plurality of upper swing links each having its upper end pivotally connected with said frame and its lower end pivotally connected with said blade actuating bar; bar moving means operable in longitudinally reciprocating said blade acutating bar; a plurality of lower swing links each having its upper end pivotally connected with said blade actuating bar and its lower end pivotally connected with said blade; and resilient torsion bar means operatively connected with at least one of said swing links operable in accelerating the cutting strokes and retarding the retractile strokes of said blade.
2. The veneer clipper as claimed in claim 1 in which at least one of said upper swing links with which torsion bar means is connected has a shank rigid with it and protruding from it coaxially of the pivot member which connects the upper end of said link with said frame; and in which the torsion bar means is a substantially straight resilient torsion bar aligned with saud shank and which has one end rigidly attached to said shank and the other end rigidly attached to the clipper frame, whereby angular movement of said shank by the link it is rigid with will torsionally stress said bar.
3. The veneer clipper as claimed in claim 1 in which the swing links and their pivotal connections to the frame and blade actuating bar and blade are relatively positioned so that when the swing links are vertical the blade is in its lowermost cutting position and will be retracted upwardly by angular movement of said links in either direction away from their vertical position, and in which each torsion bar and its connections with the clipper frame and upper swing link are positioned so that the torsion bar is destressed when the swing links are vertical, whereby said bar will be stressed by and offer resistance to angular movement of the links in either direction away from a vertical position and will resiliently urge said links toward a vertical position.
1. A veneer clipper comprising a frame; a normally horizontal anvil supported by said frame; a clipper blade guided by said frame for reciprocable cutting and retractile movement toward and away from said anvil; conveyor means operable in feeding veneer between said anvil and said blade; a blade actuating bar supported for longitudinal reciprocating movement above said blade and approximately parallel to said blade; a plurality of upper swing links each having its upper end pivotally connected with said frame and its lower end pivotally connected with said blade actuating bar; bar moving means operable in longitudinally reciprocating said blade acutating bar; a plurality of lower swing links each having its upper end pivotally connected with said blade actuating bar and its lower end pivotally connected with said blade; and resilient torsion bar means operatively connected with at least one of said swing links operable in accelerating the cutting strokes and retarding the retractile strokes of said blade.
2. The veneer clipper as claimed in claim 1 in which at least one of said upper swing links with which torsion bar means is connected has a shank rigid with it and protruding from it coaxially of the pivot member which connects the upper end of said link with said frame; and in which the torsion bar means is a substantially straight resilient torsion bar aligned with saud shank and which has one end rigidly attached to said shank and the other end rigidly attached to the clipper frame, whereby angular movement of said shank by the link it is rigid with will torsionally stress said bar.
3. The veneer clipper as claimed in claim 1 in which the swing links and their pivotal connections to the frame and blade actuating bar and blade are relatively positioned so that when the swing links are vertical the blade is in its lowermost cutting position and will be retracted upwardly by angular movement of said links in either direction away from their vertical position, and in which each torsion bar and its connections with the clipper frame and upper swing link are positioned so that the torsion bar is destressed when the swing links are vertical, whereby said bar will be stressed by and offer resistance to angular movement of the links in either direction away from a vertical position and will resiliently urge said links toward a vertical position.
Description:
SUMMARY OF THE INVENTION
My invention relates to a veneer clipper of the type used in the plywood industry to clip veneer which is fed into it in a continuous sheet into pieces of variable widths and in so doing to make possible the removal of undesirable parts of the veneer which have in them flaws or defecte, such as knots, knot holes, pitch pockets and the like.
A primary object of my invention is to provide a highly efficient, durable and long lasting veneer clipper in which a reciprocable clipper blade is operated pneumatically, without objectionable vibration, at a super speed faster than the speed usually attained in the operation of pneumatically driven wood working devices of this class and faster than the speed at which ordinary veneer clippers now in common use are usually operated, thus making it possible to increase the capacity of plywood manufacturing plants by speeding up the veneer clipping operation.
Another object is to utilize the resiliency of spring means, preferably of the torsion bar type, to increase the operating speed of pneumatically driven blade reciprocating means in a veneer clipper.
Another object is to provide improved and highly efficient pmeumatic devices of the cylinder and reciprocable piston type which are capable of operating smoothly and without objectionable vibration at speeds higher than the speeds usually attained in pneumatic devices of this type.
Other objects of the invention will be apparent from the following description and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view in elevation showing the outfeed or offbearing side of a veneer clipper constructed in accordance with my invention.
FIG. 2 is a view in longitudinal section, with parts in elevation showing a super speed, pneumatic clipper blade actuator embodied in my invention.
FIG. 2A is a view in cross section, with parts in elevation, taken on line 2A--2A of FIG. 2.
FIG. 3 is a fragmentary perspective view showing pneumatically operated blade actuating devices together with parts of a blade and blade supporting and operating means and parts of an anvil and a torsion bar and mounting means for the bar.
FIG. 4 is a view partly in cross section and partly in elevation looking in the direction indicated by line 4--4 of FIG. 1.
FIG. 5 is a fragmentary view, partly in section and partly in elevation, showing an anvil supporting beam and eccentric shaft means adjustably supporting the same.
FIG. 6 is a fragmentary view, partly in section and partly in elevation and on a larger scale than FIG. 4, showing parts also shown in FIG. 4.
FIG. 7 is a fragmentary perspective view showing parts of an anvil and anvil indexing means.
Like reference numerals refer to like parts throughout the several views.
DESCRIPTION OF THE PREFERRED EMBODIMENT
This veneer clipper comprises a strong and rigid main frame, FIGS. 1 and 4, including two spaced apart, parallel, upright main end frame members 50 and 51 each of arch shape. A relatively large, upper cross frame member 7, which also serves as an air reservoir, extends between and rigidly connects the upper ends of the end frame members 50 and 51 and has an end part which overhangs the frame member 50, as shown in FIG. 1. Base frame parts 52 are rigid with the lower ends of end frame members 50 and 51. An extension frame extends outwardly from the main frame on the offbearing side of the main frame. This extension frame comprises two upright, spaced apart, parallel posts 53, an end frame member 54 connecting the upper ends of said two posts with each other and two side frame bars 55 connecting the upper ends of said posts 53 respectively with the said two main end frame members 50 and 51.
An anvil supporting beam 39 extends across the lower portion of the main frame between the two end frame members 50 and 51 and is supported for limited vertical adjustment on the two base frame parts 52. The respective end portions of the beam 39 rest on two eccentric shafts 38. Each end of each shaft 38 has an eccentric bearing part 38' which is supported in a clamp bracket 27. The eccentric parts 38' of each shaft 38 are axially aligned with each other and they can be locked in adjusted positions in the brackets 27, for instance by set screws 27'. The beam 39 is vertically adjusted by loosening the set screws 27' and rotatively moving the shafts 38. The brackets 37 are secured to base frame parts 52 and help in preventing sidewise movement of beam 39. A stop member 56 on each base frame part 52 can be used to prevent endwise movement of beam 39.
An anvil 9 and mounting and indexing means for said anvil are supported on the beam 39. Said anvil 9 is preferably a steel tube having on it a coating of "POLYURATHANE." It is supported of beam 39, for rotary indexing movement, by bearings 34 and forms a rigid support for the veneer at the location where the blade 22 cuts it. Preferably said anvil 9 is supported about mid way between its two ends by two rollers 28, FIGS. 1 and 4. The "POLYURATHANE" coating on the anvil 9 and the indexing of said anvil after each cutting stroke of blade 22 minimizes damage to both the anvil and the blade.
The anvil indexing means includes a clutch 35 connected with the anvil 9, a lever arm 37 adapted to operate the clutch 35 when it is angularly moved and an air cylinder 36 connected with the lever arm 37 and with a source of supply of compressed air through solenoid valves 1 and 2 so that the operation of either of said solenoid valves will bring about indexing of the anvil after each cutting stroke of the blade 22. This indexing of anvil 9 equalizes wear throughout its entire circumference. The indexing means can be in duplicate at each end of anvil 9.
Driven infeed belts 31 and outfeed belts 32 operating on rollers 33 are provided to convey a continuous sheet of veneer to the anvil 9 and blade 22 and to take away the cut pieces of veneer. Also hold down rolls 49 for the veneer which is moving toward the anvil 9 and blade 22 can be provided. The clipper blade 22 and parts of the mounting and actuating means for the same are shown in FIGS. 1 to 4. The balde 22 is secured to a blade carrying bar 21 which extends across the machine above the anvil 9. The blade 22 and bar 21 are guided for vertical reciprocation by preferably three guide members 5 which are rigid with the upper frame member 7 and extend downwardly therefrom through tubular bearing members 4 that are rigid with the blade carrying bar 21. Stop members 6, preferably of "POLYURATHANE" are provided on guide members 5 for bearings 4 to bump against to prevent overtravel and to cushion impact on the upward stroke of blade 22. The guide bars 5 also prevent endwise movement in both directions of the blade carrying bar 21 and blade 22.
The blade carrying bar 21 is supported by a plurality of pairs of side by side, lower swing links 24 which have their lower ends pivotally connected with the blade carrying bar 21 and their upper ends pivotally connected with a longitudinally reciprocable horizontal blade actuating bar 23. The bar 23 is supported from the upper main transverse frame member 7 by a plurality of side by side, upper swing links 25 which have their upper ends pivotally connected by brackets 26 with the said main frame member 7. When the blade actuating bar 23 is longitudinally reciprocated a toggle action is imparted to the links 24 and 25 and vertical cutting and retractile strokes are imparted to blade 22. Preferably the pivot members which connect the adjacent ends of each set of swing links 24 and 25 with the blade actuating bar 23 are vertically aligned with each other.
The anvil 9 is positioned so the cutting edge of the blade 22 will be in engagement with it when the four pivot members of each set of links 24 and 25 are in line with each other. At this time the bar 23 will be mid way between the two end limits of its stroke and the blade 22 will be in its lowermost position and in cutting relation to the anvil 9. Movement of the bar 23 in either direction from this mid position to the end of its stroke will cause the links 24 and 25 to assume an inclined position relative to each other and will lift the blade 22 above the anvil and clear of the path of the veneer.
To accelerate the cutting stroke of the blade 22 and to decelerate, soften and render more smooth its retractile or upward stroke 1 provide spring means which will exert a boosting or accelerating force on the cutting stroke and a retarding force on the retractile stroke of the blade. Preferably this spring force is applied by one or more torsion bars 8 which are connected with the blade actuating means in such a way as to cause each torsion bar 8 to be stressed or loaded during each retractile stroke of the blade and blade actuating means and to be de-stressed or unloaded and to recoil and exert a boosting force during each cutting stroke. Three of the torsion bars 8 are shown in the drawings but it will be understood that a greater or lesser number of said bars may be used. Each torsion bar 8 can be formed of a single piece of steel or it can be formed of a plurality of pieces of steel, either with or without having resilient material disposed between the several pieces. Each torsion bar 8 has its inner end rigidly connected by a hub 45 and fitting 46 with the upper end portion of one of the upper swing links 25. The hub 45 is rigid with and perpendicular to the link 25 and is coaxial with the uppermost pivot of said link. The outer end of each torsion bar 8 is rigidly connected by a fitting 47 and bracket 48 with the end frame bar 54 of the extension frame of the machine. When swing links 24 and 25 are vertical the torsion bars 8 will not be under stress but if said links are moved in either direction from the vertical said bars 8 will be torsionally stressed in such a way as to cause them to tend to return the links to a vertical position.
The pneumatic means for imparting reciprocation to the blade actuating bar 25 comprises a cylinder 3, shown at the left in FIG. 1 as being supported from an overhanging part of the frame member and air reservoir 7, and shown on a larger scale in FIGS. 2 and 2A. The cylinder 3 has two rigidly attached similar cylinder heads 18, and 18A each of substantial thickness, which cooperate with the cylinder 3 in forming a chamber 17 for a reciprocable piston 16. A piston rod 40 extends through and is rigid with the piston 16 and extends through and is slidably guided in combined packing and bearing members 30 and 30A in the two cylinder heads 18 and 18A. One end of said piston rod 40 has a rigidly attached fitting 41 which is connected, preferably gy a short link 42, FIG. 1, with the blade actuating bar 23.
A double tapered element composed of two outwardly convergent cone shaped end parts 14 and 15 extending in opposite directions from a medial cylindrical part 20, is rigid with the piston rod 40 at one side of the piston 16 and a similar double taper element composed of two conically tapered parts 14A and 15A and a cylindrical medial part 20A is rigid with said piston rod 40 at the other side of the piston 16. Two cylindrical cavities 11 and 11A are provided in the respective cylinder heads 18 and 18A to receive the respective taper elements or sleeves as the piston 16 reciprocates. Said taper elements operate as air control members as they move into the cavities 11 and 11A, as hereinafter described. Two sealing rings 19 and 19A are provided in the inner walls of the respective cylinder heads 18 and 18A at the inner ends of the respective cavities 11 and 11A for sealing engagement with the medial cylindrical parts 20 and 20A of the double conically tapered air control members.
The cylinder head 18A has two ports 10A, FIG. 2A, in opposite walls thereof, both of which communicate with the cavity 11A and each of which is connected by a conduit 44 with a solenoid valve 2, shown in FIG. 1. The cylinder head 18 has two similar ports 10, one of which is indicated by dotted lines in FIG. 2. Which communicate with cavity 11 and are connected by two conduits 43, FIG. 1, with a solenoid valve 1. The provision of two air conduits between each cavity 11 and 11A and the solenoid valve with which it is connected insures that an ample supply of compressed air at maximum pressure will be delivered instantly to the cavity as soon as the solenoid valve connected with it is operated. This insures instant and fast acceleration of the piston 16. Also the two conduits connected with each cavity 11 and 11A provides ample conduit area for the exhaust of air.
Suitable control means is provided to control the energizing of the solenoid valves 1 and 2 and bring about each clipping and retractile stroke of the blade 22. This control means is conventional and is not shown in the drawings. It can be a light responsive veneer grader or scanner of a type available on the market, which is positioned at the infeed side of the anvil 9 and blade 22 in operative relation to the continuous sheet of veneer which is being moved toward said anvil and blade. This veneer grader or scanner controls the operation of the solenoid valves 1 and 2 in such a manner as to bring about the cutting out, at high speed, of strips of veneer having flaws or defects in them and, at the same time, holds to a minimum the waste of non-defective veneer. It also controls the valves 1 and 2 in such a manner as to cause the blade 22 to cut the veneer into pieces of predetermined width when there are no defects in the veneer to make necessary the cutting of narrower and random width strips. The solenoid valves 1 and 2 are of conventional construction and can be similar and they operate as a pair to the extent that when electrical energy is supplied to both of them the two valves move simultaneously and oppositely one from an air pressure supply position to an exhaust position relative to one end of cylinder 3 and the other from an exhaust position to an air pressure supply position relative to the other end of said cylinder 3.
When the clipper is in operation and piston 16 is at rest against cylinder head 18, as shown in FIG. 2, blade 22 will be raised and the torsion bars 8 will be under maximum stress, the cavity 11 in cylinder head 18 will be open to exhaust through conduit 43 and solenoid valve 1 and the chamber 17 in cylinder 3 will be supplied with compressed air through conduits 44 and solenoid valve 2. If, under these conditions, the solenoid valves 1 and 2 are energized and their positions as respects supply and exhaust of air are reversed the air in chamber 17 will be free to exhaust through ring 19A, cavity 11A, ports 10A, conduits 44 and solenoid valve 2. and pressure in chamber 17 will drop rapidly and will offer little resistance to movement of piston 16 toward head 18A during the first half of the piston stroke. This allows said piston to be accelerated rapidly by air under pressure entering cavity 11 in head 18 through conduits 43 during the time it is imparting a cutting stroke to the blade. This air entering cavity 11 operates in three ways, as follows, to impart super speed movement to piston 16. It opens both of the spring loaded check valves 12 in cylinder head 18 and passes through ports 13 into chamber 17 and exerts pressure against piston 16. AT the same time it moves past double taper air control member 14, 15, 20 and through ring 19 and adds to the pressure in chamber 17 against piston 16. Also it exerts pressure directly against the outer end of part 15 of said air control member further tending to accelerate movement of piston 16 in the first half of its troke. The air pressure is thus applied to the piston in three ways during the part of its travel in which it is imparting a cutting stroke to the blade 22. When the rapidly moving piston reaches a point approximately mid way of its travel the leading end of the double tapered air control member 14A, 15A, 20A begins to enter cavity 11A of cylinder head 18A through ring 19A. At this time the two check valves 12A will be closed and this will begin to restrict the exhaust of air from chamber 17 and back pressure will begin to build up between pistion 16 and cylinder head 18A. As air control member or part 15A moves farther into cavity 11A back pressure against piston 16 continues to increase and when cylindrical part 20A of the air control member passes through ring 19A the escape of exhausting air will be greatly restricted momentarily and will then increase slowly as part 14A moves into ring 19A. The result is that the piston 16 is brought to a gradual and easy stop without objectionable vibration or shock. The resistance to piston movement applied by the torsion bars 8 through the blade actuating mechanism in the last half of each stroke of the piston also aids greatly in bringing the piston and other reciprocating parts to an easy stop without objectionable vibration or shock.
The next time the solenoid valves 1 and 2 are energized the steps just hereinbefore described will be repeated in reverse order, piston 16 will be moved, at super speed, back to the position in which it is shown in FIG. 2 and another complete cutting and retractile stroke will be imparted to blade 22.
The accelerating and the decelerating forces applied by the torsion bars 8 and the tapered air control members on the piston rod 40, operating in and out of the air inlet cavities 11 and 11A in the two cylinder heads 18 and 18A all contribute to super speed operation of the clipper, and in so doing, make possible an increase in the output of said clipper.
My invention relates to a veneer clipper of the type used in the plywood industry to clip veneer which is fed into it in a continuous sheet into pieces of variable widths and in so doing to make possible the removal of undesirable parts of the veneer which have in them flaws or defecte, such as knots, knot holes, pitch pockets and the like.
A primary object of my invention is to provide a highly efficient, durable and long lasting veneer clipper in which a reciprocable clipper blade is operated pneumatically, without objectionable vibration, at a super speed faster than the speed usually attained in the operation of pneumatically driven wood working devices of this class and faster than the speed at which ordinary veneer clippers now in common use are usually operated, thus making it possible to increase the capacity of plywood manufacturing plants by speeding up the veneer clipping operation.
Another object is to utilize the resiliency of spring means, preferably of the torsion bar type, to increase the operating speed of pneumatically driven blade reciprocating means in a veneer clipper.
Another object is to provide improved and highly efficient pmeumatic devices of the cylinder and reciprocable piston type which are capable of operating smoothly and without objectionable vibration at speeds higher than the speeds usually attained in pneumatic devices of this type.
Other objects of the invention will be apparent from the following description and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a view in elevation showing the outfeed or offbearing side of a veneer clipper constructed in accordance with my invention.
FIG. 2 is a view in longitudinal section, with parts in elevation showing a super speed, pneumatic clipper blade actuator embodied in my invention.
FIG. 2A is a view in cross section, with parts in elevation, taken on line 2A--2A of FIG. 2.
FIG. 3 is a fragmentary perspective view showing pneumatically operated blade actuating devices together with parts of a blade and blade supporting and operating means and parts of an anvil and a torsion bar and mounting means for the bar.
FIG. 4 is a view partly in cross section and partly in elevation looking in the direction indicated by line 4--4 of FIG. 1.
FIG. 5 is a fragmentary view, partly in section and partly in elevation, showing an anvil supporting beam and eccentric shaft means adjustably supporting the same.
FIG. 6 is a fragmentary view, partly in section and partly in elevation and on a larger scale than FIG. 4, showing parts also shown in FIG. 4.
FIG. 7 is a fragmentary perspective view showing parts of an anvil and anvil indexing means.
Like reference numerals refer to like parts throughout the several views.
DESCRIPTION OF THE PREFERRED EMBODIMENT
This veneer clipper comprises a strong and rigid main frame, FIGS. 1 and 4, including two spaced apart, parallel, upright main end frame members 50 and 51 each of arch shape. A relatively large, upper cross frame member 7, which also serves as an air reservoir, extends between and rigidly connects the upper ends of the end frame members 50 and 51 and has an end part which overhangs the frame member 50, as shown in FIG. 1. Base frame parts 52 are rigid with the lower ends of end frame members 50 and 51. An extension frame extends outwardly from the main frame on the offbearing side of the main frame. This extension frame comprises two upright, spaced apart, parallel posts 53, an end frame member 54 connecting the upper ends of said two posts with each other and two side frame bars 55 connecting the upper ends of said posts 53 respectively with the said two main end frame members 50 and 51.
An anvil supporting beam 39 extends across the lower portion of the main frame between the two end frame members 50 and 51 and is supported for limited vertical adjustment on the two base frame parts 52. The respective end portions of the beam 39 rest on two eccentric shafts 38. Each end of each shaft 38 has an eccentric bearing part 38' which is supported in a clamp bracket 27. The eccentric parts 38' of each shaft 38 are axially aligned with each other and they can be locked in adjusted positions in the brackets 27, for instance by set screws 27'. The beam 39 is vertically adjusted by loosening the set screws 27' and rotatively moving the shafts 38. The brackets 37 are secured to base frame parts 52 and help in preventing sidewise movement of beam 39. A stop member 56 on each base frame part 52 can be used to prevent endwise movement of beam 39.
An anvil 9 and mounting and indexing means for said anvil are supported on the beam 39. Said anvil 9 is preferably a steel tube having on it a coating of "POLYURATHANE." It is supported of beam 39, for rotary indexing movement, by bearings 34 and forms a rigid support for the veneer at the location where the blade 22 cuts it. Preferably said anvil 9 is supported about mid way between its two ends by two rollers 28, FIGS. 1 and 4. The "POLYURATHANE" coating on the anvil 9 and the indexing of said anvil after each cutting stroke of blade 22 minimizes damage to both the anvil and the blade.
The anvil indexing means includes a clutch 35 connected with the anvil 9, a lever arm 37 adapted to operate the clutch 35 when it is angularly moved and an air cylinder 36 connected with the lever arm 37 and with a source of supply of compressed air through solenoid valves 1 and 2 so that the operation of either of said solenoid valves will bring about indexing of the anvil after each cutting stroke of the blade 22. This indexing of anvil 9 equalizes wear throughout its entire circumference. The indexing means can be in duplicate at each end of anvil 9.
Driven infeed belts 31 and outfeed belts 32 operating on rollers 33 are provided to convey a continuous sheet of veneer to the anvil 9 and blade 22 and to take away the cut pieces of veneer. Also hold down rolls 49 for the veneer which is moving toward the anvil 9 and blade 22 can be provided. The clipper blade 22 and parts of the mounting and actuating means for the same are shown in FIGS. 1 to 4. The balde 22 is secured to a blade carrying bar 21 which extends across the machine above the anvil 9. The blade 22 and bar 21 are guided for vertical reciprocation by preferably three guide members 5 which are rigid with the upper frame member 7 and extend downwardly therefrom through tubular bearing members 4 that are rigid with the blade carrying bar 21. Stop members 6, preferably of "POLYURATHANE" are provided on guide members 5 for bearings 4 to bump against to prevent overtravel and to cushion impact on the upward stroke of blade 22. The guide bars 5 also prevent endwise movement in both directions of the blade carrying bar 21 and blade 22.
The blade carrying bar 21 is supported by a plurality of pairs of side by side, lower swing links 24 which have their lower ends pivotally connected with the blade carrying bar 21 and their upper ends pivotally connected with a longitudinally reciprocable horizontal blade actuating bar 23. The bar 23 is supported from the upper main transverse frame member 7 by a plurality of side by side, upper swing links 25 which have their upper ends pivotally connected by brackets 26 with the said main frame member 7. When the blade actuating bar 23 is longitudinally reciprocated a toggle action is imparted to the links 24 and 25 and vertical cutting and retractile strokes are imparted to blade 22. Preferably the pivot members which connect the adjacent ends of each set of swing links 24 and 25 with the blade actuating bar 23 are vertically aligned with each other.
The anvil 9 is positioned so the cutting edge of the blade 22 will be in engagement with it when the four pivot members of each set of links 24 and 25 are in line with each other. At this time the bar 23 will be mid way between the two end limits of its stroke and the blade 22 will be in its lowermost position and in cutting relation to the anvil 9. Movement of the bar 23 in either direction from this mid position to the end of its stroke will cause the links 24 and 25 to assume an inclined position relative to each other and will lift the blade 22 above the anvil and clear of the path of the veneer.
To accelerate the cutting stroke of the blade 22 and to decelerate, soften and render more smooth its retractile or upward stroke 1 provide spring means which will exert a boosting or accelerating force on the cutting stroke and a retarding force on the retractile stroke of the blade. Preferably this spring force is applied by one or more torsion bars 8 which are connected with the blade actuating means in such a way as to cause each torsion bar 8 to be stressed or loaded during each retractile stroke of the blade and blade actuating means and to be de-stressed or unloaded and to recoil and exert a boosting force during each cutting stroke. Three of the torsion bars 8 are shown in the drawings but it will be understood that a greater or lesser number of said bars may be used. Each torsion bar 8 can be formed of a single piece of steel or it can be formed of a plurality of pieces of steel, either with or without having resilient material disposed between the several pieces. Each torsion bar 8 has its inner end rigidly connected by a hub 45 and fitting 46 with the upper end portion of one of the upper swing links 25. The hub 45 is rigid with and perpendicular to the link 25 and is coaxial with the uppermost pivot of said link. The outer end of each torsion bar 8 is rigidly connected by a fitting 47 and bracket 48 with the end frame bar 54 of the extension frame of the machine. When swing links 24 and 25 are vertical the torsion bars 8 will not be under stress but if said links are moved in either direction from the vertical said bars 8 will be torsionally stressed in such a way as to cause them to tend to return the links to a vertical position.
The pneumatic means for imparting reciprocation to the blade actuating bar 25 comprises a cylinder 3, shown at the left in FIG. 1 as being supported from an overhanging part of the frame member and air reservoir 7, and shown on a larger scale in FIGS. 2 and 2A. The cylinder 3 has two rigidly attached similar cylinder heads 18, and 18A each of substantial thickness, which cooperate with the cylinder 3 in forming a chamber 17 for a reciprocable piston 16. A piston rod 40 extends through and is rigid with the piston 16 and extends through and is slidably guided in combined packing and bearing members 30 and 30A in the two cylinder heads 18 and 18A. One end of said piston rod 40 has a rigidly attached fitting 41 which is connected, preferably gy a short link 42, FIG. 1, with the blade actuating bar 23.
A double tapered element composed of two outwardly convergent cone shaped end parts 14 and 15 extending in opposite directions from a medial cylindrical part 20, is rigid with the piston rod 40 at one side of the piston 16 and a similar double taper element composed of two conically tapered parts 14A and 15A and a cylindrical medial part 20A is rigid with said piston rod 40 at the other side of the piston 16. Two cylindrical cavities 11 and 11A are provided in the respective cylinder heads 18 and 18A to receive the respective taper elements or sleeves as the piston 16 reciprocates. Said taper elements operate as air control members as they move into the cavities 11 and 11A, as hereinafter described. Two sealing rings 19 and 19A are provided in the inner walls of the respective cylinder heads 18 and 18A at the inner ends of the respective cavities 11 and 11A for sealing engagement with the medial cylindrical parts 20 and 20A of the double conically tapered air control members.
The cylinder head 18A has two ports 10A, FIG. 2A, in opposite walls thereof, both of which communicate with the cavity 11A and each of which is connected by a conduit 44 with a solenoid valve 2, shown in FIG. 1. The cylinder head 18 has two similar ports 10, one of which is indicated by dotted lines in FIG. 2. Which communicate with cavity 11 and are connected by two conduits 43, FIG. 1, with a solenoid valve 1. The provision of two air conduits between each cavity 11 and 11A and the solenoid valve with which it is connected insures that an ample supply of compressed air at maximum pressure will be delivered instantly to the cavity as soon as the solenoid valve connected with it is operated. This insures instant and fast acceleration of the piston 16. Also the two conduits connected with each cavity 11 and 11A provides ample conduit area for the exhaust of air.
Suitable control means is provided to control the energizing of the solenoid valves 1 and 2 and bring about each clipping and retractile stroke of the blade 22. This control means is conventional and is not shown in the drawings. It can be a light responsive veneer grader or scanner of a type available on the market, which is positioned at the infeed side of the anvil 9 and blade 22 in operative relation to the continuous sheet of veneer which is being moved toward said anvil and blade. This veneer grader or scanner controls the operation of the solenoid valves 1 and 2 in such a manner as to bring about the cutting out, at high speed, of strips of veneer having flaws or defects in them and, at the same time, holds to a minimum the waste of non-defective veneer. It also controls the valves 1 and 2 in such a manner as to cause the blade 22 to cut the veneer into pieces of predetermined width when there are no defects in the veneer to make necessary the cutting of narrower and random width strips. The solenoid valves 1 and 2 are of conventional construction and can be similar and they operate as a pair to the extent that when electrical energy is supplied to both of them the two valves move simultaneously and oppositely one from an air pressure supply position to an exhaust position relative to one end of cylinder 3 and the other from an exhaust position to an air pressure supply position relative to the other end of said cylinder 3.
When the clipper is in operation and piston 16 is at rest against cylinder head 18, as shown in FIG. 2, blade 22 will be raised and the torsion bars 8 will be under maximum stress, the cavity 11 in cylinder head 18 will be open to exhaust through conduit 43 and solenoid valve 1 and the chamber 17 in cylinder 3 will be supplied with compressed air through conduits 44 and solenoid valve 2. If, under these conditions, the solenoid valves 1 and 2 are energized and their positions as respects supply and exhaust of air are reversed the air in chamber 17 will be free to exhaust through ring 19A, cavity 11A, ports 10A, conduits 44 and solenoid valve 2. and pressure in chamber 17 will drop rapidly and will offer little resistance to movement of piston 16 toward head 18A during the first half of the piston stroke. This allows said piston to be accelerated rapidly by air under pressure entering cavity 11 in head 18 through conduits 43 during the time it is imparting a cutting stroke to the blade. This air entering cavity 11 operates in three ways, as follows, to impart super speed movement to piston 16. It opens both of the spring loaded check valves 12 in cylinder head 18 and passes through ports 13 into chamber 17 and exerts pressure against piston 16. AT the same time it moves past double taper air control member 14, 15, 20 and through ring 19 and adds to the pressure in chamber 17 against piston 16. Also it exerts pressure directly against the outer end of part 15 of said air control member further tending to accelerate movement of piston 16 in the first half of its troke. The air pressure is thus applied to the piston in three ways during the part of its travel in which it is imparting a cutting stroke to the blade 22. When the rapidly moving piston reaches a point approximately mid way of its travel the leading end of the double tapered air control member 14A, 15A, 20A begins to enter cavity 11A of cylinder head 18A through ring 19A. At this time the two check valves 12A will be closed and this will begin to restrict the exhaust of air from chamber 17 and back pressure will begin to build up between pistion 16 and cylinder head 18A. As air control member or part 15A moves farther into cavity 11A back pressure against piston 16 continues to increase and when cylindrical part 20A of the air control member passes through ring 19A the escape of exhausting air will be greatly restricted momentarily and will then increase slowly as part 14A moves into ring 19A. The result is that the piston 16 is brought to a gradual and easy stop without objectionable vibration or shock. The resistance to piston movement applied by the torsion bars 8 through the blade actuating mechanism in the last half of each stroke of the piston also aids greatly in bringing the piston and other reciprocating parts to an easy stop without objectionable vibration or shock.
The next time the solenoid valves 1 and 2 are energized the steps just hereinbefore described will be repeated in reverse order, piston 16 will be moved, at super speed, back to the position in which it is shown in FIG. 2 and another complete cutting and retractile stroke will be imparted to blade 22.
The accelerating and the decelerating forces applied by the torsion bars 8 and the tapered air control members on the piston rod 40, operating in and out of the air inlet cavities 11 and 11A in the two cylinder heads 18 and 18A all contribute to super speed operation of the clipper, and in so doing, make possible an increase in the output of said clipper.