US3727505A

US3727505A - Brake mechanism for a reciprocating blade

Info

Publication number: US3727505A
Application number: US00231991A
Authority: US
Inventors: E Shaughnessy
Original assignee: Prentice Co E V
Current assignee: E V PRENTICE CO US; Prentice Co E V
Priority date: 1972-03-06
Filing date: 1972-03-06
Publication date: 1973-04-17
Anticipated expiration: 1990-04-17
Also published as: CA954802A

Abstract

A brake mechanism including a housing for attachment to a clipping machine with the housing serving to support both brake and clutch means with the latter coupled to the machines reciprocating blade by interconnecting arms. Rotational movement is imparted to a driving clutch member by said arms with the clutch being of the uni-directional type permitting unrestricted downward movement of the blade while in an opposite direction engaging a cooperating driven clutch member to ultimately initiate brake operation to accomplish a non-rebounding type return of the blade to its rest position.

Description

United States Patent 91 Shaughnessy 5] Apr. 17, 1973 [5 BRAKE MECHANISM FORA 3,416,392 12/1968 Rutz ..83/526X RECIPROCATING BLADE [75] Inventor: P. Shaughnesy, Portland, jzz g gfig ggi g' t [73] Assignee: E. V. Prentice Co., Portland, Oreg. 57] ABSTRACT Filed! 1972 A brake mechanism including a housing for at- Appl. No.: 231,991

[52] U.S. Cl ..83/526, 83/630 [51] Int. Cl. ..B26d 5/18 [58] Field of Search ..83/526, 615, 630

[56] References Cited UNITED STATES PATENTS 2,221,877 11/1940 Meyer ..83/526 2,783,843 3/1957 Seybold ...83/526 3,225,637 12/1965 Thumin ..-.83/526 tachment to a clipping machine with the housing serving to support both brake and clutch means with the latter coupled to the machines reciprocating blade by interconnecting arms. Rotational movement is imparted to a driving clutch member by said arms with the clutch being of the uni-directional type permitting unrestricted downward movement of the blade while in an opposite direction engaging a cooperating driven clutch member to ultimately initiate brake operation to accomplish a non-rebounding type return of the blade to its rest position.

15 Claim, 7 Drawing Figures PATENTEB APR 1 7 I973 SHEET 1 BF 2 TQM El NEED PATENTED 3 71975 3, 727. 505

SHEET 2 OF 2 36 OVR'N sue \QQ AGE BRAKE MECHANISM FOR A RECIPROCATING BLADE BACKGROUND OF THE INVENTION The present invention relates to a brake mechanism for braking a reciprocated blade during one direction of blade travel to precisely stop the blade at its rest position. While the brake mechanism is presently shown and described in conjunction with a wood veneer clipping machine such is not intended to imply its use is restricted to any particular type of blade equipped machine.

In the production of wood veneer destined ultimately for lay up into laminated plywood panels, the wood veneer ribbon passes a clipper which is intermittently operated to sever the veneer into desired lengths. Additionally, the clipper also sections out unsuitable veneer segments. Originally, a machine operator visually inspected the passing veneer actuating the clipper blade as necessary. More recently clipper operation is in response to automatic controls normally occurring at predetermined intervals to provide the dimensions sought or, if need be, removing pitch pockets, knots, cracks, etc.,.

characteristically, the veneer lathe peeling the veneer ribbon from the peeler log operated to produce veneer faster than a single clipper machine could handle same hence it is common practice to feed a pair of clipping machines from one lathe or alternatively store the veneer temporarily for later clipping both of which entail considerable equipment and man hour cost.

In an effort to reduce the restrictive effect of the clipping operation on a veneer production line recent developments have included the introduction of electronic scanning of the continuous veneer ribbon for defects with electronic components initiating asignal for blade operation. Accordingly, an increase in the speed at which the veneer ribbon could be presented to the clipper was realized, the speed presently being approximately 300 feet per minute or five feet per second. A limiting factor in veneer speed appears to be associated with the momentary obstruction of veneer ribbon travel during cutting contact with the blade.

Reducing the duration of contact between blade and veneer is desirable however, efforts to increase blade speed have been limited by objectionable rebounding of the blade by reason of its forceful return to its rest position. Efforts over the years to dampen rebounding have included pneumatic dampeners for the blade actuating air cylinders while still other efiorts have included a friction drag in contact with a blade bar of the clipper for a portion of blade travel which undesirably inhibited blade speed. Further, the results did not always provide uniforrn braking of the blade hence regular adjustment was required.

As the blade and associated moving linkage has considerable mass the instantaneous starting and stopping imparts impact blows to the machine and the blade linkage resulting in machine depreciation. With clipper blade operations occurring several hundred times during a work shift, a prime advantage of a blade braking system is the avoidance of such impacts to the machine permitting accelerated blade speeds on the cutting stroke.

With existing scanning systems a time delay must be provided to enable the scanned veneer to move under 0 As approximately nineteen percent of all peeled veneer is cut away at the clipper operation the accuracy of such clipping becomes important.

SUMMARY OF THE PRESENT INVENTION The present invention is adaptable for attachment to existing clipping machines or other types of machines where it is desirable to brake a reciprocating member in one direction. The present device is adapted for mounting on existing machines and includes a unidirectional, overrunning clutch component to impart motion in one direction only to a brake means.

Importantly the present device permits an unrestricted, high speed cutting stroke of a clipper blade with the braking action of the device being applied only during return of the blade to its rest position. Accordingly, an important advantage is realized in that blade speed at the instant of veneer cutting is not in any way diminished as is the case with former blade braking arrangements.

During the upstroke of the blade continuous braking is applied so as to dissipate blade inertia and allow the blade to uniformly return to its rest position with no rebound. A twofold benefit is realized, one being the avoidance of an impact blow to the associated blade linkage and machine frame while additionally the blade is quickly and precisely positioned for consecutive rapid cycling.

The suitable braking of a veneer clipper blade permits driving'of the blade at an accelerated speed since the rebound problem is overcome by the present brake mechanism. As blade speed is inversely proportional to the time the blade is in obstructive, cutting contact with the veneer ribbon, the greater the speed the less ribbon travel is impeded. As earlier mentioned this contact time is one of the limiting factors of the speed at which a veneer ribbon may travel past a clipper. The present ribbon speed with prior art braking devices is in the area of 300 feet per minute or five feet per second which speed may be increased substantially by clippers equipped with the instant brake mechanism.

The foregoing advantages of the brake mechanism are realized without jeopardizing acceptable cutting tolerances. Obviously the closer the cut to the optimum cutting line the greater the veneer saving with an acceptable cutting tolerance now beingapproximately one-half inch for current scanning and clipper equipment.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a front elevational view of a conventional wood veneer clipper machine equipped with a pair of the instant brake mechanisms,

FIG. 2 is a vertical elevational view taken along line 2-2 of FIG. 1 showing one side of a brake mechanism,

FIG. 3 is a view similar to FIG. 2 taken along line 3- 3 of FIG. 1 with fragments broken away for convenience of illustration,

FIG. 4 is a vertical elevational view taken along line 4-4 of FIG. 3 showing details of a clutch mounted lever in pivotal attachment with a pair of arm members,

FIG. 5 is an elevational view of the opposite end of the clutch taken along line 5-5 of FIG. 3 with a quadrant broken away,

FIG. 6 is a view of the clutch taken along irregular line 6-6 of FIG. 5, and

FIG. 7 is a side elevational view of a typical brake I component of the present invention with a quadrant broken away and parts positioned for purposes of illustration.

DESCRIPTION OF THE PREFERRED EMBODIMENT With continuing reference to the accompanying drawings wherein applied reference numerals indicate parts similarly identified in the following specification, the reference numeral 10, in FIG. 1, indicates generally a veneer clipping machine, termed a clipper by those in the art, and shown located transversely of the path of a veneer ribbon to be severed by the machine.

Typically, a veneer ribbon, subsequent to being cut from a peeler log, is dimensioned in its travelling direction by passage through a clipper machine as at 10. The ribbon is continuously presented to the machine by a series of powered conveyor belts with suitable hold down means bearing on the veneer ribbon holding same in planar contact with said belts. Additionally, existing clippers include wheel means or the like in contact with the passing veneer ribbon for the purpose of initiating a signal for clipper operation after the passage of a predetermined length of veneer with said means being settable according to the desired length. More recently, and in addition to the above, veneer clippers have been operated in conjunction with infra-red and other type scanning systems which detect unsuitable veneer segments and initiate a signal for clipper operation.

The clipper machine 10, as shown in FIG. 1, includes a reciprocally mounted blade 11 adjustably secured to a blade bar 12 the latter comprising part of the machines toggle linkage which mounts blade 11 for reciprocative movement. The ends of the blade bar 12 mount sleeves l3 slidably engaging guides 14 which serve to assure the blade moving in parallel with a cutting anvil 15 over which the veneer ribbon at V continuously moves.

- appropriate electrical signal to a solenoid valve 18,

results in the toggle linkage moving from its position shown through a center position wherein toggle linkage is aligned resulting in a cutting stroke of blade 11 with continuing linkage movement past center resulting in the upstroke of blade 11 to complete one cycle. The

. present brake mechanism, as it will become evident, is

equally adaptable to clippers using other types of blade linkage arrangements and is not dependent upon the particular linkage shown. The foregoing description of a clipper and associated equipment is well known and is provided in the interest of background material only and does not constitute part of the present invention.

With attention now directed to the present invention, a pair of brake mechanisms are indicated generally at 20 in FIG. 1 with each mechanism being identical except as later noted. A weldment type housing serves jointly as a base for securement to a clipper frame member 10A and to mount a pair of brake components, indicated generally at 25, on opposite housing members 22. Each member 22 is apertured at 22A. As seen in FIGS. 2 and 3, members 22 are spaced by a mounting block 23 which is suitably secured to machine frame member 10A. In instances where the brake mechanism is to be incorporated into a clipper machine frame, the housing may be dispensed with and instead, later described brake components directly mounted to the clipper.

Disposed intermediate the housing members 22 are clutch means indicated generally at 24 carried by a shaft 26 interconnecting the clutch with brake components 25 of a single brake mechanism.

With specific attention to clutch means 24, as best disclosed in FIGS. 2 through 6, the particular clutch means shown and described is of the type termed a cam clutch in that in one direction internal clutch elements move to interengage the clutch members for torque transmission while in an opposite direction said clutch elements will disengage to permit clutch overrunning. Such clutches operate in similarity to a ratchet and pawl mechanism with the exception that the number of engaged relationships between the driving and driven clutch members are infinite. On such suitable clutch, later described, is that manufactured by the Morse Corporation and termed a PB series cam clutch.

For translating and reciprocating motion of blade 1 1 into rotational clutch motion I provide a pair of arms 30 pivotally attached to the clipper blade bar 12. Said arms terminate upwardly in pivoted attachment to a clutch mounted lever 32 as best seen in FIG. 4. The arms 30 straddle linkage 17 in a spaced manner. A bolt assembly 33 and bushing 33A pivotally couples the upper ends of arms 30 to lever 32 which in turn is integral with a clutch mounted collar 34. Collar 34, milled at 34A for toggle linkage clearance, is in keyed engagement as at 35 with one end 36A of a clutch driving member 36. A bearing sleeve 36B permits independent rotation of said driving member and shaft 26. Interiorly of cup shaped driving member 36 are a series of cam elements 37 which serve to permit overrunning movement in one direction of driving member 36 relative to a driven clutch member at 38 while rotation of cup member 36 in an opposite direction imparts a rocking action to the cam elements 37 causing same to interengage said clutch members for transmitting rotary motion to driven member 38. The directional arrows applied to FIG. 5 indicate overrunning and engagement directions as noted. Such clutches are available with the cam elements 37 arranged so as to reverse the overrun and engaged directions as would be the case for the clutch component of the brake mechanism at the right hand side of the clipper as viewed in FIG. 1.

During movement of blade 11 downwardly the pair of arms follow to partially rotate or index clutch member 36 the latter moving in an unrestricted manner freely about shaft 26. The reversal of blade 11, as it initiates its upstroke, imparts opposite rotational movement to the immediately above mentioned components causing cam members 37 to rock into clutch locking engagement for conjoint rotation of its driving and driven members.

Driven clutch member 38 is provided internally with a keyway at 40 receiving an elongate key 41 carried by shaft 26 which extends to the outer end of shaft 26 to thereat provide keyed engagement at 42A of shaft 26 with a friction plate 42 of brake component 25. The same key arrangement also pertains to the opposite end of shaft 26 and the opposite brake component 25.

The following description of a single brake component 25 is equally applicable to both brake components 25. One suitable brake component is that manufactured by the Horton Corporation identified as model no. LWB-8212. With joint reference to FIGS. 2 and 7 a typical brake component of the present mechanism includes a stationary annular brake ring 43 which at all times is in biased braking engagement with a coacting annular surface 44 of the ribbed friction plate 42. Air pressure is admitted to the interior of a brake mounting plate 45 via a port 46 served by a pressure conduit 47. A pressure regulator at 48 (FIG. 1) permits the air pressure to be set as desired which in turn determines the internal pressure exerted against a pressure plate 49 and ultimately the degree to which brake ring 43 is biased against surface 44 of the friction plate 42. During clipper machine operation the brake ring 43 and surface 44 are at all times in biased surface contact. The setting of pressure regulator 48 would be made to best suit the specific clipper machine.

Completing the brake description, retainer means at 50 in conjunction with helical springs 51 bias the pressure plate 49 to a brake release or open position in the absence of system air pressure within the brake. Suitable bearing means at 52 serve to rotatably support the friction plate 42 which in turn supports the outer end of shaft 26.

The operation of the instant brake mechanism has been set forth in conjunction with the foregoing description hence further operative description is believed unnecessary. In some clipper installations the use of one brake mechanism 20 may be adequate.

While but one embodiment of the present invention has been set forth it is not intended to so restrict the scope of the protection but rather that such extend to all forms of the invention coming within the breadth of the appended claims.

What I claim and desire to secure under a Letters Patent is:

1. A brake mechanism for the braking of the return stroke of an intermittently operated reciprocative blade of a cutting machine, said mechanism comprisclutch means having a driving. member and a driven member and including means permitting said driving member to overrun in one direction while interengaging said members during rotation of said driven member in an opposite direction,

brake means associated with the cutting machine and including a movable friction plate,

means interconnecting said driven member of the clutch component and the movable friction plate for imparting rotational movement to the latter, and

means extending intermediate the driving clutch member and the blade and actuated by the latter to impart rotational movement to said driving clutch member, movement of the last mentioned means during the return of the blade resisted by said brake means whereby the inertia of the blade and moving machine parts is dissipated to prevent rebound motion of the blade from its rest position.

2. The brake mechanism as claimed in claim 1 wherein said brake means comprises a pair of brake components each having a movable friction plate, said interconnecting means comprising a shaft in engagement adjacent its opposite ends with each of said friction plates.

3. The brake mechanism as claimed in claim 2 wherein said firction plates are at all times in surface engagement with stationary brake members with the latter resisting friction plate movement.

4. The brake mechanism as claimed in claim 2 wherein said brake components each include a pressure plate and a brake ring, said pressure plate biasing said ring into engagement with said friction plate, said brake components adapted to receive pressurized air from a regulated source to act upon said pressure plate whereby the biased engagement of said brake ring with the pressure plate may be set to achieve the braking action desired.

5. The brake mechanism as claimed in claim 2 wherein said shaft is supported at its ends within said friction plates, said driving and driven members carried by said shaft with said driven member mounted for rotation independent of said shaft, said driven member including a clutch mounted collar having a lever appendage for pivoted engagement with the upper end of said means extending intermediate the driving clutch member and the blade.

6. A brake mechanism for braking a reciprocative blade of a clipping machine during the blades return to a position of rest, the blade having a cutting stroke and a return stroke constituting one cycle of blade operation, said brake mechanism comprising,

clutch means having a driving member and a driven member and including means intermediate said clutch members permitting overrunning of said driving member during one direction of rotation and serving to engage said clutch members during rotation in an opposite direction,

brake means supported by a machine and including coacting stationary and movable members,

means interconnecting said driven member of the clutch means with the movable member of said brake means,

means coupling said blade to the driving member of the clutch means for imparting movement to said driving member in an overrunning direction during the cutting stroke of the blade and oppositely imparting opposite clutch engaging movement to said driving member during the return stroke of the blade, and

the movable member of said brake means cooperating with said stationary brake member to dissipate inertia of the blade and associated machine structure throughout the return stroke of the blade so as to prevent rebound motion of the blade from its rest position.

7. The brake mechanism as claimed in claim 6 additionally including a housing secured to a machine frame member, said brake means comprising a pair of brake components mounted on said housing and each having a movable friction plate, said interconnecting means comprising a shaft in engagement adjacent its opposite ends with said friction plates.

8. The brake mechanism as claimed in claim 7 wherein said friction plates are at all times in surface engagement with stationary brake members with the latter resisting friction plate movement.

9. The brake mechanism as claimed in claim 8 wherein said brake components each include a pressure plate and a brake ring, said pressure plate biasing said ring into engagement with said friction plate, said brake components adapted to receive pressurized air from a regulated source to act upon said pressure plate whereby the biased engagement of said brake ring with the pressure plate may be set to achieve the braking action desired.

10. The brake mechanism as claimed in claim 7 wherein said shaft is supported at its ends within said friction plates, said driving and driven members carried by said shaft with said driven member mounted for rotation independent of said shaft, said driven member including a clutch mounted collar having a lever appendage for pivoted engagement with the upper end of said coupling means.

11. In a wood veneer clipper machine having a reciprocative blade intermittently operated through a cutting cycle including a cutting stroke and a consecutive return upstroke to a rest position, linkage intermediate the blade and a frame member of the machine, a power source for blade operation, the improvement comprising a brake mechanism having,

clutch means supported by said housing and including a driving member and a driven member,

means coupling said driving member to said blade and imparting rotation in opposite directions to said driving member during reciprocative blade movement,

brake means mounted on said machine,

means operatively connecting the driven clutch member with said brake means,

said clutch component including means disengaging said clutch members during rotation of said driven member in one direction and interengaging said members during opposite rotation of said driving member, and

said opposite direction of the driving member coincident with the upstroke of the blade whereby the upstroke of the blade and associated machine linkage is braked to dissipate inertia of blade and linkage to assure a non-rebound return of the blade to its uppermost rest position.

12. The brake mechanism as claimed in claim 11 additionally including a housing mounting said brake means to a machine frame member, said brake means comprising a pair of brake components each having a movable friction plate, said interconnecting means comprising a shaft in engagement adjacent its opposite ends with each of said friction plates.

. The brake mechanism as claimed in claim 12 wherein said friction plates are at all times in surface engagement with stationary brake members with the latter resisting friction plate movement.

14. The brakemechanism as claimed in claim 13 wherein said brake components each additionally include a pressure plate and a brake ring, said pressure plate adapted to be biased by pressurized air within said brake components to urge said brake ring into forceful contact with said friction plate whereby said contact may be varied for brake adjusting purposes by regulating the air pressure.

15. The brake mechanism as claimed in claim 12 wherein saidshaft is supported at its ends within said friction plates, said driving and driven members carried by said shaft with said driven member mounted for rotation independent of said shaft, said driven member including a clutch mounted collar having a lever appendage for pivoted engagement with the upper end of said coupling means.

Claims

1. A brake mechanism for the braking of the return stroke of an intermittently operated reciprocative blade of a cutting machine, said mechanism comprising, clutch means having a driving member and a driven member and including means permitting said driving member to overrun in one direction while interengaging said members during rotation of said driven member in an opposite direction, brake means associated with the cutting machine and including a movable friction plate, means interconnecting said driven member of the clutch component and the movable friction plate for imparting rotational movement to the latter, and means extending intermediate the driving clutch member and the blade and actuated by the latter to impart rotational movement to said driving clutch member, movement of the last mentioned means during the return of the blade resisted by said brake means whereby the inertia of the blade and moving machine parts is dissipated to prevent rebound motion of the blade from its rest position.

3. The brake mechanism as claimed in claim 2 wherein said friction plates are at all times in surface engagement with stationary brake members with the latter resisting friction plate movement.

6. A brake mechanism for braking a reciprocative blade of a clipping machine during the blades return to a position of rest, the blade having a cutting stroke and a return stroke constituting one cycle of blade operation, said brake mechanism comprising, clutch means having a driving member and a driven member and including means intermediate said clutch members permitting overrunning of said driving member during one direction of rotation and serving to engage said clutch members during rotation in an opposite direction, brake means supported by the machine and including coacting stationary and movable members, means interconnecting said driven member of the clutch means with the movable member of said brake means, means coupling said blade to the driving member of the clutch means for imparting movement to said driving meMber in an overrunning direction during the cutting stroke of the blade and oppositely imparting opposite clutch engaging movement to said driving member during the return stroke of the blade, and the movable member of said brake means cooperating with said stationary brake member to dissipate inertia of the blade and associated machine structure throughout the return stroke of the blade so as to prevent rebound motion of the blade from its rest position.

11. In a wood veneer clipper machine having a reciprocative blade intermittently operated through a cutting cycle including a cutting stroke and a consecutive return upstroke to a rest position, linkage intermediate the blade and a frame member of the machine, a power source for blade operation, the improvement comprising a brake mechanism having, clutch means supported by said housing and including a driving member and a driven member, means coupling said driving member to said blade and imparting rotation in opposite directions to said driving member during reciprocative blade movement, brake means mounted on said machine, means operatively connecting the driven clutch member with said brake means, said clutch component including means disengaging said clutch members during rotation of said driven member in one direction and interengaging said members during opposite rotation of said driving member, and said opposite direction of the driving member coincident with the upstroke of the blade whereby the upstroke of the blade and associated machine linkage is braked to dissipate inertia of blade and linkage to assure a non-rebound return of the blade to its uppermost rest position.

13. The brake mechanism as claimed in claim 12 wherein said friction plates are at all times in surface engagement with stationary brake members with the latter resisting friction plate movement.

14. The brake mechanism as claimed in claim 13 wherein said brake components each additionally include a pressure plate and a brake ring, said pressure plate adapted to be biased by pressurized air within said brake components to urge said brake ring into forceful contact with said friction plate whereby said contact may be varied for brake adjusting purposes by regulating the air pressure.

15. The brake mechanism as claimed in claim 12 wherein said shaft is supported at its ends within said friction plates, said driving and driven members carried by said shaft with said driven member mounted for rotation independent of said shaft, said driven member including a clutch mounted collar having a lever appendage for pivoted engagement with the upper end of said coupling means.