ROTARY VENEER CLIPPER
United States Patent 3808925
A rotary clipper for veneer and the like having a thin blade which cuts through veneer while moving in the same direction as the veneer while the latter moves over a supporting drum. The blade has an edge opposite its cutting edge which bears against a bracing drum while the blade cuts through the veneer. The drum and the blade are synchronized and rotated so that the cutting edge of the blade moves over the face of the drum at the same speed as the veneer moves over that drum.
US Patent References:
Clipper for sheet material
Robinson et al. - February 1945 - 2369253
Cutting device for making cuts in sheet material
Winkler et al. - October 1966 - 3276306
Clipper for sheet material
Robinson et al. - February 1945 - 2369253
Cutting device for making cuts in sheet material
Winkler et al. - October 1966 - 3276306
Application Number:
05/339746
Publication Date:
05/07/1974
Filing Date:
03/12/1973
View Patent Images:
Export Citation:
Assignee:
Durand Machine Company Ltd. (New Westminster, British Columbia, CA)
Primary Class:
Other Classes:
83/591, 83/343
International Classes:
B23D25/02
Field of Search:
83/346,347,343,591
Primary Examiner:
Meister J. M.
Attorney, Agent or Firm:
Fetherstonhaugh & Co.
Claims:
I claim
1. Apparatus for cutting veneer and like strip material into continuously varying lengths comprising a rotatable support drum over which veneer to be clipped is moved, a thin blade having at least one cutting edge rotatably mounted above the support drum and adapted to be rotated around a longitudinal axis extending parallel to the drum, said blade being so positioned relative to the drum that the cutting edge cuts through veneer on the drum when said edge passes the drum during rotation of the blade, a rotatable bracing drum above the blade and extending parallel therewith and positioned to be engaged by an edge of the blade opposite the cutting edge thereof while said cutting edge is cutting through veneer on the support drum, and means for rotating the blade on command to cut the veneer at a desired position.
2. Apparatus as claimed in claim 1 including means for stopping and braking the blade after the cutting edge thereof has completed a cut through the veneer.
3. Apparatus as claimed in claim 1 in which said edge of the blade opposite said cutting edge thereof also is a cutting edge.
4. Apparatus as claimed in claim 3 including means for stopping and braking the blade after each cutting edge thereof has completed a cut through the veneer.
5. Apparatus as claimed in claim 1 including means connected to an end of the blade for maintaining the latter under tension longitudinally of the blade.
6. Apparatus as claimed in claim 1 in which said means for rotating the blade comprises a clutch brake operatively connected to the blade, a power source operatively connected to the clutch brake, and means selectively to operate the clutch brake to cause said blade to rotate.
7. Apparatus as claimed in claim 1 including means for synchronizing the rotation of the support drum, the bracing drum and the blade to cause the cutting edge of the blade to move at the same speed as veneer moving over the support drum.
8. Apparatus as claimed in claim 1 including power means for moving the veneer over the support drum at the same speed as the blade cutting edge.
1. Apparatus for cutting veneer and like strip material into continuously varying lengths comprising a rotatable support drum over which veneer to be clipped is moved, a thin blade having at least one cutting edge rotatably mounted above the support drum and adapted to be rotated around a longitudinal axis extending parallel to the drum, said blade being so positioned relative to the drum that the cutting edge cuts through veneer on the drum when said edge passes the drum during rotation of the blade, a rotatable bracing drum above the blade and extending parallel therewith and positioned to be engaged by an edge of the blade opposite the cutting edge thereof while said cutting edge is cutting through veneer on the support drum, and means for rotating the blade on command to cut the veneer at a desired position.
2. Apparatus as claimed in claim 1 including means for stopping and braking the blade after the cutting edge thereof has completed a cut through the veneer.
3. Apparatus as claimed in claim 1 in which said edge of the blade opposite said cutting edge thereof also is a cutting edge.
4. Apparatus as claimed in claim 3 including means for stopping and braking the blade after each cutting edge thereof has completed a cut through the veneer.
5. Apparatus as claimed in claim 1 including means connected to an end of the blade for maintaining the latter under tension longitudinally of the blade.
6. Apparatus as claimed in claim 1 in which said means for rotating the blade comprises a clutch brake operatively connected to the blade, a power source operatively connected to the clutch brake, and means selectively to operate the clutch brake to cause said blade to rotate.
7. Apparatus as claimed in claim 1 including means for synchronizing the rotation of the support drum, the bracing drum and the blade to cause the cutting edge of the blade to move at the same speed as veneer moving over the support drum.
8. Apparatus as claimed in claim 1 including power means for moving the veneer over the support drum at the same speed as the blade cutting edge.
Description:
This invention relates to a rotary clipper particularly for wood veneers, but which may be used for clipping or cutting other material in strip form.
As this clipper is primarily designed for cutting wood veneers, it will be described in connection with these veneers.
Veneer is peeled off logs in a veneer lathe, and then it passes through a clipper which cuts out defects and cuts the veneer into desired lengths relative to the direction of movement thereof. Up to the present, a single veneer clipper could not operate fast enough to handle the output of a standard veneer lathe and so the latter has to be operated at reduced speed or several clippers are provided to handle the output of the lathe.
Most of the clippers used in plywood mills today are the guillotine type clipper, such as illustrated in U.S. Pat. No. 2,394,324, dated Feb. 5, 1946. In these, the knife operates in guillotine fashion on to a fixed anvil. As a result, the knife stops the veneer for a short time during every cut. The feed speed of these clippers is limited to something of the order of 300 feet per minute when clipping wide sheets, and in many mills they are operated at a much lower speed, something like 150 to 200 FPM is used when clipping narrow or random widths. Even at these lower speeds, one portion of the veneer is moving while another portion thereof is stopped by the cutting knife, and this can cause jamb-ups and bunch-ups that either cause stoppages or make it more difficult to handle the veneer pieces.
In the guillotine type clipper in common use, the stroke of the knife is powered by a very strong air cylinder, usually 8 inches in diameter with an 8 inch stroke. These cylinders require expensive, large valving so that they will accelerate quickly enough. The cylinder has to be large because of the mass of the knife and linkage to be moved. The high speed and large inertia causes serious cushioning and maintenance problems when the knife stops. The large cylinder requires a very constant air supply, or inaccuracies will result in the position of the cut. In order to reduce inertia, the linkages that are used between the air cylinder and the knife must be small, and as a result, these wear out frequently. In addition, as the knife travels upwardly after the cut is made, there is a tendency for the veneer which is being pushed against the knife to be pulled up with it, and the veneer can become broken or jambed if the infeed hold-downs are not working exactly correctly. These hold-downs must allow for some slippage, and this results in inaccurate cutting, and this type of clipper is very noisy.
It has long been the desire of mill operators to have a clipper, the knife of which moves with the veneer as it cuts. This type is generally known as the drum clipper, such as illustrated in U.S. Pat. 3,029,675 dated Apr. 17, 1962. The drum clipper has one knife or two diametrically opposite knives, but these will only clip fixed widths of veneer and, due to the high inertia of the drums, a clutch brake is not able to stop and start the drum fast enough to make random cuts.
The present rotary clipper greatly reduces and practically eliminates all of the above-mentioned disadvantages. It has the advantages of a drum clipper without the disadvantages thereof.
The disadvantages are overcome by using in the present clipper a thin cutting blade with its mass reduced to a point where the stopping and starting thereof is affected very little by inertia. Veneers for plywood are moved with the dimension thereof which will ultimately be the length of a plywood panel extending transversely of the direction of movement of the veneer. In other words, the veneers being clipped are over 8 feet wide, and this requires a cutting blade of corresponding length. In order to prevent the thin blade from wobbling or vibrating, it is maintained under considerable tension in the direction of the length thereof. The present apparatus also includes a supporting drum over which the veneer travels, and this drum is positioned so that the cutting edge of the blade at least touches the peripheral surface of the drum when it cuts through the veneer. The apparatus also includes a bracing drum so positioned that the edge of the blade opposite the cutting edge thereof engages the peripheral surface of this drum at the instant the veneer is being cut. This ensures the blade going completely through the veneer throughout the full width thereof. The speed of rotation of the support drum, the bracing drum and the blade are synchronized with the feed of the veneer so that the cutting edge of the blade is moving in the same direction as the veneer and at the same speed as the latter while it is cutting through the veneer.
As the two rolls or drums rotate all the time, they are not affected by inertia. The tensioning of the blade keeps it suitably rigid at all times, and the bracing drum braces the blade at the moment of cut. In the preferred form of the invention, the edge of the blade opposite the cutting edge mentioned above also is a cutting edge. In addition, the normal or at-rest position of the blade is when the blade is in a horizontal position, and the cutting takes place when the blade is in the vertical position. Thus, the blade has to make only a half turn for each cut. This, and the light weight of the blade, enables very narrow strips to be cut out of the travelling veneer. In other words, a very small defect can be removed without wasting very much wood. The guillotine type and drum type of clippers of the prior art cannot function fast enough to cut such narrow strips out of the veneer so that a great deal of wood is wasted.
The present clipper has been operated at high speeds, and speeds up to 600 FPM can be attained. This will enable many mills to get considerable production increases from existing lathes, and it will enable other mills to eliminate costly belt systems between the lathe and a multiplicity of clippers. The fact that the knife can be synchronized accurately with the veneer flow will practically eliminate jamb-ups, automatic and manual veneer handling will be facilitated, and hold-downs can be simplified. It is now possible to accurately meter the veneer through the clipper at a constant rate by clamping it tightly at the holddowns since the latter do not have to allow for any slippage. Small electrically-, hydraulically-or pneumatically-operated clutch brake units can be used, and these are much more consistent than the large air cylinders of the commonly used clippers of the prior art, thus allowing for much more accurate clipping. In addition, the noise of the crashing air cylinder and loose linkages has been eliminated. Furthermore, other different control units can be used in place of the clutch brake unit, such as, for example, a semi-revolution clutch, stepping electric motor, and the like.
Apparatus for cutting veneer and the like strip material into continuously varying lengths, in accordance with the present invention, comprises a rotatable support drum over which veneer to be clipped is moved, a thin blade having at least one cutting edge rotatably mounted above the support drum and adapted to be rotated around a longitudinal axis extending parallel to the drum, said blade being so positioned relative to the drum that the cutting edge cuts through veneer on the drum when said edge passes the drum during rotation of the blade, a rotatable bracing drum above the blade and extending parallel therewith and positioned to be engaged by an edge of the blade opposite the cutting edge thereof while said cutting edge is cutting through veneer on the support drum, and means for rotating the blade on command to cut the veneer at a desired position therein.
A preferred form of the invention is illustrated in the accompanying drawings, in which
FIG. 1 is a plan view of the rotary veneer clipper,
FIG. 2 is a longitudinal vertical section taken on the line 2--2 of FIG. 1,
FIG. 3 is a vertical cross-section taken on the line 3--3 of FIG. 2,
FIG. 4 is an enlarged vertical section taken on the line 4--4 of FIG. 1, and
FIG. 5 is a vertical section taken on the line 5--5 of FIG. 4.
Referring to the drawings, 10 is a rotary veneer clipper including a pair of spaced apart end frames 11 and 12 between which a support drum 15, a brace drum 16 and a thin clipper blade 18 extend.
Drums 15 and 16 have shafts 20 and 21, respectively, journalled in frames 11 and 12 and extending through frame 11. Blade 18 is very thin, narrow and relatively long in the direction transversely of the apparatus. This blade has shafts 25 and 26 projecting from its opposite ends and on the axis thereof, shaft 25 extending through frame 11, and shaft 26 being journalled in frame 12. Blade 18 has a cutting edge 29 along one edge thereof, and although not absolutely necessary, it is preferable to provide a second cutting edge 30 along the opposite edge of the blade.
As it is desirable to keep blade 18 under tension during operation, the outer end of shaft 25 is connected through a suitable bearing 34 to a bar 36, the opposite ends of which are connected to piston rods 39 and 40 of fluid cylinders 41 and 42 which are supported by a wall 43 forming part of frame 11. Fluid, preferably air, is directed into and out of cylinder 41 by hoses 44, and similarly, fluid is directed into and out of cylinder 42 by hoses 45. As the controls for fluid systems of the type to be used with cylinders 41 and 42 are well known, they have not been described or illustrated herein. In any case, pressure is normally maintained through hoses 44 and 45 which tends to draw bar 36 outwardly relative to the machine and thereby maintain blade 18 under tension. Any other suitable means may be used for this purpose.
Suitable means is provided for rotating drums 15 and 16, and blade 18, and one desirable way of doing this is illustrated in FIGS. 3, 4 and 5. An electric motor 50 mounted on a bracket 51 projecting from support 11 has a drive shaft 53 upon which a sprocket 54 is fixedly mounted. This sprocket is drivingly connected by a chain 55 to another sprocket 56 fixedly mounted on shaft 21 of drum 16. Another sprocket 58 fixedly mounted on shaft 21 is connected by a chain 59 to a sprocket 60 fixedly mounted on shaft 20 of drum 15.
A second sprocket 64 is fixedly mounted on motor shaft 53 and is connected by a chain 65 to a sprocket 66 of an electrically-, hydraulically- or pneumatically-operated clutch brake 67. The clutch brake is operatively connected to a gear 70 meshing with another gear 71, on a shaft 72. A sprocket 73 mounted on this shaft is connected by chain 75 to a sprocket 76 mounted on shaft 25 of blade 18.
With this arrangement, motor 50 drives drums 15 and 16 continuously while the apparatus is in operation, and rotates blade 18 intermittently through clutch brake 67. This clutch brake is operated by signals received from a sensor 80 mounted above the infeed conveyor 82 of the apparatus. The sensor is located ahead of apparatus 10 with respect to the direction of movement of the veneer, which is indicated by arrow 84 in FIGS. 1 and 2.
When the sensor detects a fault in the veneer being directed towards apparatus 10, a signal is sent, and after a suitable delay, clutch brake 67 is operated to rotate blade 18 to cut the veneer at the correct spot across the width thereof. The sensor and delay mechanisms are those used in this field in the guillotine type of clipper and so are well known in the trade, and do not need description therein. The detecting and timing apparatus also includes means for operating the blade to cut the veneer into predetermined lengths relative to the direction of movement thereof. If the veneer is a little over 8 feet across the width of conveyor 82, the blade is usually operated to cut the veneer into widths of a little over 4 feet in the direction of movement. This control also is standard equipment.
The sizes of the various sprockets and gears in the drive system between motor 50 and drums 15 and 16, and said motor, clutch brake 67 and blade 18, are such that the speed of movement of the cutting edges 29 and 30 of the cutting blade in their circular paths is the same as the peripheral speed of drums 15 and 16. These speeds are also synchronized with the movement of the veneers over the surface of drum 15 so that the veneer moves at the peripheral speed of the drum.
A standard type of hold-down is illustrated at 90 in FIGS. 1 and 2. It will be noted that infeed conveyor 82 is made up of a plurality of laterally spaced endless belts 92, and there is a hold-down belt 94 above and in contact with each belt 92. Each hold-down belt 94 travels around pulleys 96 and 97, one of which is driven in synchronization with the speed of conveyor belts 92. Drives may be taken from motor 50 to drive conveyor 82 and the hold-down apparatus 90, or the conveyor and hold-down apparatus may be driven by a separate motor 98, see FIG. 1, synchronized with motor 50. In this example, motor 98 drives conveyor 82 through a chain drive 102, and drives hold-down belts 94 through chain drive 104 reversing gears 105 and chain drive 106.
As the veneer is not stopped during the cutting action in this apparatus, the hold-down apparatus may firmly grip each piece of veneer so that there is no slippage between the time a given portion of the veneer passes beneath sensor 80 and the time that portion arrives at cutting blade 18. Thus, the veneers will always move the same distance between the time sensor 80 signals the defect and the time blade 18 cuts the veneer.
When sensor 80 detects a defect in the veneer passing therebeneath, the cutting signal is generated, and when that defect reaches drum 15, clutch 67 causes blade 18 to make a half revolution. This causes cutting edge 29 (when the elements of the apparatus are in the position shown in FIG. 2) to swing down and cut through the veneer along the desired line thereof as said line moves over drum 15. As the blade, the veneer and drum are all moving at the same speed, there is no holdback of the veneer at this time. If a second signal is sent immediately after the first one, cutting edge 30 is swung through the veneer. Therefore, this apparatus can cut very narrow strips out of the veneer, the minimum width of these strips being determined by the time it takes to rotate blade 18 through a half turn. This time interval is very short since blade 18 is very thin and therefore inertia has very little effect or delaying action on the blade. This very thin blade can be used to cut through veneer because it is maintained under tension at all times during operation. In addition to this, as cutting edge 29 or 30 cuts through the veneer on support drum 15, cutting edge 30 or 29, respectively, is bearing against brace drum 16. Therefore, the blade can be made much thinner and lighter than would otherwise be the case. The surfaces of drums 15 and 16 are made of replaceable material, such as a suitable plastic. For example, drum 15 may have a relatively soft surface so that the cutting edges of the blade sink a little into this surface as the edges move by it, thus insuring that the blade cuts clearly through the veneer. The surface of drum 16 may be a little harder than that of drum 15 in order firmly to brace the blade each time one of its edges is cutting through the veneer.
As drums 15 and 16 are constantly rotating, there is no inertia to overcome relative to these drums for a cutting operation. The lightness of the blade makes it possible to use a clutch brake, which is much more constant and quiet than the large air cylinders of the clippers of the prior art, and this also adds to the accuracy of the cutting. Each cut is made while the cutting edge of the blade, the veneer and the peripheral surface of the support drums are moving in the same direction and at the same speed. As the movement of the veneer is not stopped by the cutting action of the blades, the holddowns can grip the veneer very firmly, thereby increasing the accuracy of the apparatus.
As this clipper is primarily designed for cutting wood veneers, it will be described in connection with these veneers.
Veneer is peeled off logs in a veneer lathe, and then it passes through a clipper which cuts out defects and cuts the veneer into desired lengths relative to the direction of movement thereof. Up to the present, a single veneer clipper could not operate fast enough to handle the output of a standard veneer lathe and so the latter has to be operated at reduced speed or several clippers are provided to handle the output of the lathe.
Most of the clippers used in plywood mills today are the guillotine type clipper, such as illustrated in U.S. Pat. No. 2,394,324, dated Feb. 5, 1946. In these, the knife operates in guillotine fashion on to a fixed anvil. As a result, the knife stops the veneer for a short time during every cut. The feed speed of these clippers is limited to something of the order of 300 feet per minute when clipping wide sheets, and in many mills they are operated at a much lower speed, something like 150 to 200 FPM is used when clipping narrow or random widths. Even at these lower speeds, one portion of the veneer is moving while another portion thereof is stopped by the cutting knife, and this can cause jamb-ups and bunch-ups that either cause stoppages or make it more difficult to handle the veneer pieces.
In the guillotine type clipper in common use, the stroke of the knife is powered by a very strong air cylinder, usually 8 inches in diameter with an 8 inch stroke. These cylinders require expensive, large valving so that they will accelerate quickly enough. The cylinder has to be large because of the mass of the knife and linkage to be moved. The high speed and large inertia causes serious cushioning and maintenance problems when the knife stops. The large cylinder requires a very constant air supply, or inaccuracies will result in the position of the cut. In order to reduce inertia, the linkages that are used between the air cylinder and the knife must be small, and as a result, these wear out frequently. In addition, as the knife travels upwardly after the cut is made, there is a tendency for the veneer which is being pushed against the knife to be pulled up with it, and the veneer can become broken or jambed if the infeed hold-downs are not working exactly correctly. These hold-downs must allow for some slippage, and this results in inaccurate cutting, and this type of clipper is very noisy.
It has long been the desire of mill operators to have a clipper, the knife of which moves with the veneer as it cuts. This type is generally known as the drum clipper, such as illustrated in U.S. Pat. 3,029,675 dated Apr. 17, 1962. The drum clipper has one knife or two diametrically opposite knives, but these will only clip fixed widths of veneer and, due to the high inertia of the drums, a clutch brake is not able to stop and start the drum fast enough to make random cuts.
The present rotary clipper greatly reduces and practically eliminates all of the above-mentioned disadvantages. It has the advantages of a drum clipper without the disadvantages thereof.
The disadvantages are overcome by using in the present clipper a thin cutting blade with its mass reduced to a point where the stopping and starting thereof is affected very little by inertia. Veneers for plywood are moved with the dimension thereof which will ultimately be the length of a plywood panel extending transversely of the direction of movement of the veneer. In other words, the veneers being clipped are over 8 feet wide, and this requires a cutting blade of corresponding length. In order to prevent the thin blade from wobbling or vibrating, it is maintained under considerable tension in the direction of the length thereof. The present apparatus also includes a supporting drum over which the veneer travels, and this drum is positioned so that the cutting edge of the blade at least touches the peripheral surface of the drum when it cuts through the veneer. The apparatus also includes a bracing drum so positioned that the edge of the blade opposite the cutting edge thereof engages the peripheral surface of this drum at the instant the veneer is being cut. This ensures the blade going completely through the veneer throughout the full width thereof. The speed of rotation of the support drum, the bracing drum and the blade are synchronized with the feed of the veneer so that the cutting edge of the blade is moving in the same direction as the veneer and at the same speed as the latter while it is cutting through the veneer.
As the two rolls or drums rotate all the time, they are not affected by inertia. The tensioning of the blade keeps it suitably rigid at all times, and the bracing drum braces the blade at the moment of cut. In the preferred form of the invention, the edge of the blade opposite the cutting edge mentioned above also is a cutting edge. In addition, the normal or at-rest position of the blade is when the blade is in a horizontal position, and the cutting takes place when the blade is in the vertical position. Thus, the blade has to make only a half turn for each cut. This, and the light weight of the blade, enables very narrow strips to be cut out of the travelling veneer. In other words, a very small defect can be removed without wasting very much wood. The guillotine type and drum type of clippers of the prior art cannot function fast enough to cut such narrow strips out of the veneer so that a great deal of wood is wasted.
The present clipper has been operated at high speeds, and speeds up to 600 FPM can be attained. This will enable many mills to get considerable production increases from existing lathes, and it will enable other mills to eliminate costly belt systems between the lathe and a multiplicity of clippers. The fact that the knife can be synchronized accurately with the veneer flow will practically eliminate jamb-ups, automatic and manual veneer handling will be facilitated, and hold-downs can be simplified. It is now possible to accurately meter the veneer through the clipper at a constant rate by clamping it tightly at the holddowns since the latter do not have to allow for any slippage. Small electrically-, hydraulically-or pneumatically-operated clutch brake units can be used, and these are much more consistent than the large air cylinders of the commonly used clippers of the prior art, thus allowing for much more accurate clipping. In addition, the noise of the crashing air cylinder and loose linkages has been eliminated. Furthermore, other different control units can be used in place of the clutch brake unit, such as, for example, a semi-revolution clutch, stepping electric motor, and the like.
Apparatus for cutting veneer and the like strip material into continuously varying lengths, in accordance with the present invention, comprises a rotatable support drum over which veneer to be clipped is moved, a thin blade having at least one cutting edge rotatably mounted above the support drum and adapted to be rotated around a longitudinal axis extending parallel to the drum, said blade being so positioned relative to the drum that the cutting edge cuts through veneer on the drum when said edge passes the drum during rotation of the blade, a rotatable bracing drum above the blade and extending parallel therewith and positioned to be engaged by an edge of the blade opposite the cutting edge thereof while said cutting edge is cutting through veneer on the support drum, and means for rotating the blade on command to cut the veneer at a desired position therein.
A preferred form of the invention is illustrated in the accompanying drawings, in which
FIG. 1 is a plan view of the rotary veneer clipper,
FIG. 2 is a longitudinal vertical section taken on the line 2--2 of FIG. 1,
FIG. 3 is a vertical cross-section taken on the line 3--3 of FIG. 2,
FIG. 4 is an enlarged vertical section taken on the line 4--4 of FIG. 1, and
FIG. 5 is a vertical section taken on the line 5--5 of FIG. 4.
Referring to the drawings, 10 is a rotary veneer clipper including a pair of spaced apart end frames 11 and 12 between which a support drum 15, a brace drum 16 and a thin clipper blade 18 extend.
Drums 15 and 16 have shafts 20 and 21, respectively, journalled in frames 11 and 12 and extending through frame 11. Blade 18 is very thin, narrow and relatively long in the direction transversely of the apparatus. This blade has shafts 25 and 26 projecting from its opposite ends and on the axis thereof, shaft 25 extending through frame 11, and shaft 26 being journalled in frame 12. Blade 18 has a cutting edge 29 along one edge thereof, and although not absolutely necessary, it is preferable to provide a second cutting edge 30 along the opposite edge of the blade.
As it is desirable to keep blade 18 under tension during operation, the outer end of shaft 25 is connected through a suitable bearing 34 to a bar 36, the opposite ends of which are connected to piston rods 39 and 40 of fluid cylinders 41 and 42 which are supported by a wall 43 forming part of frame 11. Fluid, preferably air, is directed into and out of cylinder 41 by hoses 44, and similarly, fluid is directed into and out of cylinder 42 by hoses 45. As the controls for fluid systems of the type to be used with cylinders 41 and 42 are well known, they have not been described or illustrated herein. In any case, pressure is normally maintained through hoses 44 and 45 which tends to draw bar 36 outwardly relative to the machine and thereby maintain blade 18 under tension. Any other suitable means may be used for this purpose.
Suitable means is provided for rotating drums 15 and 16, and blade 18, and one desirable way of doing this is illustrated in FIGS. 3, 4 and 5. An electric motor 50 mounted on a bracket 51 projecting from support 11 has a drive shaft 53 upon which a sprocket 54 is fixedly mounted. This sprocket is drivingly connected by a chain 55 to another sprocket 56 fixedly mounted on shaft 21 of drum 16. Another sprocket 58 fixedly mounted on shaft 21 is connected by a chain 59 to a sprocket 60 fixedly mounted on shaft 20 of drum 15.
A second sprocket 64 is fixedly mounted on motor shaft 53 and is connected by a chain 65 to a sprocket 66 of an electrically-, hydraulically- or pneumatically-operated clutch brake 67. The clutch brake is operatively connected to a gear 70 meshing with another gear 71, on a shaft 72. A sprocket 73 mounted on this shaft is connected by chain 75 to a sprocket 76 mounted on shaft 25 of blade 18.
With this arrangement, motor 50 drives drums 15 and 16 continuously while the apparatus is in operation, and rotates blade 18 intermittently through clutch brake 67. This clutch brake is operated by signals received from a sensor 80 mounted above the infeed conveyor 82 of the apparatus. The sensor is located ahead of apparatus 10 with respect to the direction of movement of the veneer, which is indicated by arrow 84 in FIGS. 1 and 2.
When the sensor detects a fault in the veneer being directed towards apparatus 10, a signal is sent, and after a suitable delay, clutch brake 67 is operated to rotate blade 18 to cut the veneer at the correct spot across the width thereof. The sensor and delay mechanisms are those used in this field in the guillotine type of clipper and so are well known in the trade, and do not need description therein. The detecting and timing apparatus also includes means for operating the blade to cut the veneer into predetermined lengths relative to the direction of movement thereof. If the veneer is a little over 8 feet across the width of conveyor 82, the blade is usually operated to cut the veneer into widths of a little over 4 feet in the direction of movement. This control also is standard equipment.
The sizes of the various sprockets and gears in the drive system between motor 50 and drums 15 and 16, and said motor, clutch brake 67 and blade 18, are such that the speed of movement of the cutting edges 29 and 30 of the cutting blade in their circular paths is the same as the peripheral speed of drums 15 and 16. These speeds are also synchronized with the movement of the veneers over the surface of drum 15 so that the veneer moves at the peripheral speed of the drum.
A standard type of hold-down is illustrated at 90 in FIGS. 1 and 2. It will be noted that infeed conveyor 82 is made up of a plurality of laterally spaced endless belts 92, and there is a hold-down belt 94 above and in contact with each belt 92. Each hold-down belt 94 travels around pulleys 96 and 97, one of which is driven in synchronization with the speed of conveyor belts 92. Drives may be taken from motor 50 to drive conveyor 82 and the hold-down apparatus 90, or the conveyor and hold-down apparatus may be driven by a separate motor 98, see FIG. 1, synchronized with motor 50. In this example, motor 98 drives conveyor 82 through a chain drive 102, and drives hold-down belts 94 through chain drive 104 reversing gears 105 and chain drive 106.
As the veneer is not stopped during the cutting action in this apparatus, the hold-down apparatus may firmly grip each piece of veneer so that there is no slippage between the time a given portion of the veneer passes beneath sensor 80 and the time that portion arrives at cutting blade 18. Thus, the veneers will always move the same distance between the time sensor 80 signals the defect and the time blade 18 cuts the veneer.
When sensor 80 detects a defect in the veneer passing therebeneath, the cutting signal is generated, and when that defect reaches drum 15, clutch 67 causes blade 18 to make a half revolution. This causes cutting edge 29 (when the elements of the apparatus are in the position shown in FIG. 2) to swing down and cut through the veneer along the desired line thereof as said line moves over drum 15. As the blade, the veneer and drum are all moving at the same speed, there is no holdback of the veneer at this time. If a second signal is sent immediately after the first one, cutting edge 30 is swung through the veneer. Therefore, this apparatus can cut very narrow strips out of the veneer, the minimum width of these strips being determined by the time it takes to rotate blade 18 through a half turn. This time interval is very short since blade 18 is very thin and therefore inertia has very little effect or delaying action on the blade. This very thin blade can be used to cut through veneer because it is maintained under tension at all times during operation. In addition to this, as cutting edge 29 or 30 cuts through the veneer on support drum 15, cutting edge 30 or 29, respectively, is bearing against brace drum 16. Therefore, the blade can be made much thinner and lighter than would otherwise be the case. The surfaces of drums 15 and 16 are made of replaceable material, such as a suitable plastic. For example, drum 15 may have a relatively soft surface so that the cutting edges of the blade sink a little into this surface as the edges move by it, thus insuring that the blade cuts clearly through the veneer. The surface of drum 16 may be a little harder than that of drum 15 in order firmly to brace the blade each time one of its edges is cutting through the veneer.
As drums 15 and 16 are constantly rotating, there is no inertia to overcome relative to these drums for a cutting operation. The lightness of the blade makes it possible to use a clutch brake, which is much more constant and quiet than the large air cylinders of the clippers of the prior art, and this also adds to the accuracy of the cutting. Each cut is made while the cutting edge of the blade, the veneer and the peripheral surface of the support drums are moving in the same direction and at the same speed. As the movement of the veneer is not stopped by the cutting action of the blades, the holddowns can grip the veneer very firmly, thereby increasing the accuracy of the apparatus.