US 3557466 A
Description (OCR text may contain errors)
Jan. 26, 1911 1E; B B 3 551,
' some METNOEAN APPARATUS FOR DRYING SHEET VENEER AND THE LIKE Original Filed July 5, 1966 2 Sheets-Sheet l INVENTOR. 1448527 (1' Boo/ME Jan. 26, 1971 v A. G. BODINE 3,557,466
SONIC METHOD AND APPARATUS FOR DRYING SHEET VENEER'AND THE LIKE Ofiginal Filed July 5. 1966 2 Sheets-Sheet 2 INVENTOR.
United States PatentO Int. Cl. F26b /02 US. Cl. 34-4 Claims ABSTRACT OF THE DISCLOSURE Water laden material such as wood veneer is subjected to high level sonic energy to cause the water particles contained therein to how from the interior to an outside surface thereof. The water particles are removed from the material surface by means of a porous absorber and/or a drying agent such as an air stream.
This application is a division of my application Ser. No. 562,636, filed July 5, 1966, now Pat. No. 3,472,295.
A general object of the invention is provision of improved methods and apparatus for drying wood veneer, as well as the drying of other sheet stock, making use of sonic vibrations to improve the drying-out process, by which the veneer can be simply and expeditiously continuously dried out within a drying station of small compass as rapidly as it is received from the log. A further object, as intimated above, is to apply such sonic vibrational drying process not only to wettened wood veneer, but to other materials found to respond to the process.
, The invention is concerned with physical phenomena of mobility in fibrous structures such as those composed of wood, wherein grain structures, with the accompanying varying hardnesses and/or densities of different but immediately contiguous elements of the wood lead to differential mobilities of these elements. The invention is further concerned with certain effects of sonic wave activity on wettened wood structures by which the moisture which has been absorbed into the log is caused to become mobile and more easily and rapidly extracted from the cut veneer.
The commonly known process of manufacturing wood veneer heretofore has been first to water-soak a tree log, so as to give it added toughness and resiliency, and so prevent it against cracking or tearing too severely as the log is worked. The water-soaked log is then mounted in a lathe-type machine and rotated about its longitudinal axis from the power drive of the machine. A long sharp blade is thenbrought into engagement with the lateral After the wood veneer is cut from the water-soaked log, it has poor dimensional stability because the moisture leaving the .wood causes it to change dimension considerbefore sheets of the veneer are glued to one another in the manufacture of plywood, or otherwise utilized. The drying ovens must be very large because the exposure time necessary to satisfactory drying is very substantial. Moisture is generally removed from the veneer by applying heat to its outer surface, which dries thevery outside surface. Subsequently, the moisture in the center of the veneerworks to the outside surface." Ihus a moist ure 3,557,466 Patented Jan. 26, 1971 gradient is created, causing the moisture to tend to flow from the wet interior to the dried surface. The time factor involved in this process is so great that the drying ovens have to. be very large, taking into account the high speed with which the veneer comes from the veneering machine. The use of the invention described in my application Ser. No. 562,636, of which this application is a division, in cutting of the veneer accomplishes an initial drying-out effect by reason of the sonic vibrations set up in the veneer being cut by the vibrating veneer knife, which vibrations tend to fling the surface moisture from the veneer as it leaves the knife.
The veneer drying operation of the invention is further based upon the concept that the equilibrium condition of moisture entrainment by capillary forces can be shifted by a sonic energy field. The elastic vibrations of the veneer, or indeed of any similar matrix containing moisture-filled interstices, shift the equilibrium condition of the moisture in those interstices so that capillary fluid forces are affected by the cyclic change of dimensions of the interstices. This brings about mobility of the fibers or other substance of the matrix, as well as of the contained moisture. By this sonic process, it is thus possible to sonically work moisture out of the interstices of a moisture-laden matrix.
A further feature of the invention is to accelerate the rate of extraction of fluid from a matrix to an extraction or blotting membrane or element by elastically vibrating the matrix and/or the blotting membrane or element. For example, in the drying of veneer, I may pass the veneer between a sonic transducer and a fluid extraction membrane. The transducer and/or the extraction membrane can be in the form of a porous pad, with the veneer sliding thereon, or can be in the form of porous rollers over which the veneer travels. The sonic activation shifts the basic equilibrium condition of moisture retention, and in addition obtains a high degree of moisture mobility so that a porous absorbed or blotter can more readily extract the moisture from the veneer, or other matrix to be dried.
It may be observed here that moisture-laden items such as wood veneer and the like tend naturally to absorb substantial sonic power, thus reducing the Q factor of a sonically vibratory system. My aforementioned orbitalmass generators described hereinabove are especially applicable here because of their ability to furnish the vibratory system with a good Q factor, and thus a sharp resonant curve, as well as because of its frequency and power accommodating characteristics, as referred to hereinabove.
SONIC DISCUSSION Certain acoustic phenomena disclosed in the foregoing and hereinafter, are, generally speaking, outside the experience of those skilled in the acoustics art. To aid in a full understanding of these phenomena by those skilled in the acoustics art, and by others, the following general discussion, including definition of terms, is deemed to be of importance.
By the expression sonic vibration I mean elastic vibrations, i.e., cyclic elastic deformations, such as longitudinal, lateral, gyratory, torsional, etc., generated in a struc ture, or which travel through a medium with a characteristic velocity of propagation. If these vibrations travel longitudinally, or create a longitudinal wave pattern in a medium or structure having uniformly distributed constants of elasticity and mass, this is sound wave transmission. Regardless of the vibratory frequency of such sound wave transmission, the same mathematical formulae apply, and the science is called sonics. In addition, there can be elastically vibratory systems wherein the esseential features of mass appear as a localized influence of paralumped constant can be a localized or concentrated elastically deformable element, affording a local effect referred to variously as elasticity, modulus, modulus of elasticity, stiffness, stiffness modulus, or compliance, which is the reciprocal of the stiffness modulus. Fortunately, these constants, when functioning in an elastically vibratory system such as mine, have cooperating and mutual influencing effects like equivalent factors in alternatingcurrent electrical systems. In fact, in both distributed and lumped constant systems, mass is mathematically equivalent to inductance (a coil); elastic compliance is mathematically equivalent to capacitance (a condenser); and friction or other pure energy dissipation is mathematically equivalent to resistance (a resistor).
Because of these equivalents, my elastic vibratory systems with their mass and stiffness and enery consumption, and their sonic energy transmission properties, can be viewed as equivalent electrical circuits, where the functions can be expressed, considered, changed and quantitatively analyzed by using well proven electrical formulae.
It is important to recognize that the transmission of sonic energy into the interface or work area between two parts to be moved against one another requires the above mentioned elastic vibration phenomena in order to accomplish the benefits of my invention. There have been other proposals involving exclusively simple bodily vibration of some part. However, these latter do not result in the benefits of my sonic or elastically vibratory action.
Since sonic or elastic vibration results in the mass and elastic compliance elements of the system taking on these special properties akin to the parameters of inductance and capacitance in alternating current phenomena, wholly new performances can be made to take place in the mechanical arts. The concept of acoustic impedance becomes of paramount importance in understanding performances. Here impedance is the ratio of cyclic force or pressure acting in the media to resulting cyclic velocity or motion, just like the ratio of voltage to current. In this sonic adaptation impedance is also equal to media density times the speed of propagation of the elastic vibration.
In this invention impedance is important to the accomplishment of desired ends, such as where there is an interface. A sonic vibration transmitted across an interface between two media or two structures can experience some reflection, depending upon differences of impedance. This can cause large relative motion, if desired, at the interface.
Impedance is also important to consider if optimized energization of a system is desired. If the impedances are adjusted to be matched somewhat, energy transmission is made very effective.
Sonic energy at fairly high frequency can have energy effects on molecular or crystalline systems. Also, these fairly high frequencies can result in very high periodic acceleration values, typically on the order of hundreds or thousands of times the acceleration of gravity. This is because mathematically acceleration varies with the square of frequency. Accordingly, by taking advantage of this square function, I can accomplish very high forces with my sonic systems. My sonic systems preferably accomplish such high forces, and high total energy, by using a type of orbiting-mass sonic vibration generator taught in my Pat. No. 2,960,314, which is a simple mechanical device. The use of this type of sonic vibration generator in the sonic system of the present invention affords an especially simple, reliable, and commercially feasible system.
An additional important feature of these sonic circuits is the fact that they can be made very active, so as to handle substantial power, by providing a high Q factor. Here this factor Q is the ratio of energy stored to energy dissipated per cycle. In other words, with a high Q factor, he sonic svstem can store a high level of sonic energy, to which a constant input and output of energy is respec- 4 tively added and subtracted. Circuit-wise, this Q factor is numerically the ratio of inductive reactance to resistance. Moreover, a high Q system is dynamically active, giving considerable cyclic motion where such motion is needed.
Certain definitions should now be given:
Impedance, in an elastically vibratory system, is, mathematically, the complex quotient of applied alternating force and linear velocity. It is analogous to electrical impedance. The concise mathematical expression for this impedance is where M is vibratory mass, C is elastic compliance (the reciprocal of stiffness, or of modulus or elasticity) and f is the vibration frequency.
Resistance is the real part R of the impedance, and represents energy dissipation, as by friction.
Reactance is the imaginary part of the impedance, and is the difference of mass reactance and compliance reactance.
Mass reactance is the positive imaginary part of the impedance, given by 21rfM. It is analogous to electrical inductive reactance, just as mass is analogous to inductance.
Elastic compliance reactance is the negative imaginary part of impedance, given by 1/21rfC. Elastic compliance reactance is analogous to electrical capacitative reactance, just as compliance is analogous to capacitance.
Resonance in the vibratory circuit is obtained at the operating frequency at which the reactance (the algebraic sum of mass and compliance reactances) becomes zero. Vibration amplitude is limited under this condition to resistance alone, and is maximized. The inertia of the mass elements necessary to be vibrated does not under this condition consume any of the driving force.
A valuable feature of my sonic circuit is the provision of enough extra elastic compliance reactance so that the mass or inertia of various necessary bodies in the system does not cause the system to depart so far from resonance that a large proportion of the driving force is consumed and wasted in vibrating this mass. For example, a mechanical oscillator or vibration generator of the type normally used in my inventions always has a body, or carrying structure, for containing the cyclic force generating means. This supporting structure, even when minimal, still has mass, or inertia. This inertia could be a force-wasting detriment, acting as a blocking impedance using up part of the periodic force output just to accelerate and decelerate this supporting structure. However, by use of elastically vibratory structure in the system, the effect of this mass, or the mass reactance resulting therefrom, is counteracted at the frequency for resonance; and when a resonant acoustic circuit is thus used, with adequate capacitance (elastic compliance reactance), these blocking impedances are tuned out of existence, at resonance, and the periodic force generating means can thus deliver its full impulse to the work, which is the resistive component of the impedance.
Sometimes it is especially beneficial to couple the sonic oscillator at a low-impedance (high-velocity vibration) region, for optimum power input, and then have high impedance (high-force vibration) at the work point. The sonic circuit is then fuctioning additionally as a transformer, or acoustic lever, to optimize the effectiveness of both the oscillator region and the work delivering region.
For very high-impedance systems having high Q at high frequency, I sometimes prefer that the resonant elastic system be a bar of solid material such as steel. For lower frequency or lower impedance, especially where large amplitude vibration is desired, I use a fiuid resonator. One desirable specie of my invention employes, as the source of sonic power, a sonic resonator system comprising an elastic member in combination with an orbiting-mass oscillator or vibration generator, as above mentioned. This combination has many unique and desirable features. For example, this orbiting-mass oscillator has the ability to adjust its input power and phase to the resonant system so as to accommodate changes in the work load, including changes in either or both the reactive impedance and the resistive impedance. This is a very desirable feature in that the oscillator hangs on to the load even as the load changes.
It is important to note that this unique advantage of the orbiting-mass oscillator accrues from the combination thereof with the acoustic resonant circuit, so as to comprise a complete acoustic system. In other words, the orbiting-mass oscillator is matched up to the resonant part of its system, and the combined system is matched up to the acoustic load, or the job to be accomplished. One manifestation of this proper matching is a characteristic whereby the orbiting-mass oscillator tends to lock in to the resonant frequency of the resonant part of the systerm.
The combined system has a unique performance which is exhibited in the form of a greater effectiveness and particularly greater persistance in a sustained sonic action as the work process proceeds or goes through phases and changes of conditions. The orbiting-mass oscillator, in this matched-up arrangement, is able to hang on to the load and continue to develop power as the sonic energy absorbing environment changes with the variations in sonic energy absorption by the load. The orbiting-mass oscillator automatically changes its phase angle, and therefore its power factor, with these changes in the resistive impedance of the load.
A further important characteristic which tends to make the orbiting-mass oscillator hang on to the load and continue the development of effective power, is that it also accommodates for changes in the reactive impedance of the acoustic environment while the work process continues. For example, if the load tends to add either inductance or capacitance to the sonic system, then the orbiting-mass oscillator will acommodate accordingly. Very often this is accommodateby an automatic shift in frequency of operation of the orbiting-mass oscillator by virtue of an automatic feedback of torque to the energy source which drives the orbiting-mass ocillator. In other words, if the reactive impedance of the load changes this automatically causes a shift in the resonant response of the resonant circuit portion of the complete sonic system. This in turn causes a shift in the frequency of the orbiting-mass oscillator for a given torque load provided by the power source which drives the orbiting-mass ocilla- I01.
All of the above mentioned characteristics of the orbiting-mass oscillator are provided to a unique degree by this oscillator in combination with the resonant circuit. As explained elsewhere in this discussion the kinds of acoustic environment presented to the sonic source by this invention are uniquely accommodated by the combination of the orbiting-mass oscillator and the resonant system. As will be noted, this invention involves the application of sonic power which brings forth some special problems unique to this invention, which problems are primarily a matter of delivering effective sonic energy to the particular work process involved in this invention. The work process, as explained elsewhere herein, presents a special combination of resistive and reactive impedances. These circuit values must be properly met in order that the invention be practiced effectively.
Reference is now directed to the following detailed description of certain illustrative embodiments of the invention, and to the drawings, in which:
FIG. 1 is a perspective view showing a veneer machine in accordance with the invention;
FIG. 2 is a detail plan view taken in the aspect of the arrows 22 on FIG. 1;
FIG. 3 is a detail elevational view taken in the aspect of the arrows 3--3 on FIG. 2;
FIG. 4 is a detail section through an illustrative orbitalmass vibration generator, taken in accordance with the section line 44 of FIG. 1;
FIG. 5 is a schematic view showing a layer of veneer being peeled from a log and showing, in vertical medial section, a drying means for the cut veneer;
FIG. 6 is a section taken on line 6-6 of FIG. 5, showing a drying roller means for the veneer;
FIG. 7 is a transverse section taken on line 7-7 of FIG. 6;
FIG. :8 is a view similar to FIG. 7, but showing the use of an additional vibration generator for vibrating the roller;
FIG. 9 is a view taken in the aspect of the arrows 9--9 on FIG. 8;
FIG. 10 is a view similar to FIG. 5 but showing an alternative drying system;
FIG. 11 is a transverse section taken on line 1111 on FIG. 10; and
FIG. 12 is a standing wave diagram representative of vibratory action imparted to the veneer knife in accordance with the invention.
FIG. 1 shows somewhat diagrammatically a veneer cutting machine 15. This machine has lathe-type arrangements for rotating a log 16 from which the veneer is to be cut, and includes shafts such as 17 for engaging 0r clutching to the two ends of the log, these shafts being supported in suitable bearings in frame members 18, and one of which is rotated by conventional power gear and a prime mover, not shown, for the purpose of rotating the log.
A veneer knife 20 has a tapered blade 21 leading to a sharp edge which engages the log somewhat tangentially, and this blade 21 is provided with mounting arrangements enabling it to be properly positioned, and then fed radially inward as the veneer is cut from the log. As here shown, the blade 21 is supported at its rear edge by two flexible mounting devices 22, located preferably at some point between twenty and twenty-five precent of the length of the knife from each of its two ends. In the present instance, the flexible mounting device generally designated by numeral 22 comprises a mounting block 23 secured to the rearward edge of the knife, a pair of parallel, flat, flexible springs 24 fastened at one end to opposite sides of the block 23, and a mounting block 25 to which the opposite ends of the springs 24 are fastened, the block 25 of the two mounting devices being secured to an adjustable and continuously fed platen or slab 26. The platen 26 is formed in the bottom with a dovetailed way 28, extending generally perpendicular to the log, and which slidably receives a dovetail 29 on the top of a vertically movable mounting slide block 30, the platen being supported by said slide block 30, as indicated. The latter is vertically movable in a vertical slot 32 in a sub-frame block 34, which is rigidly mounted in the frame of the machine by any suitable mountingstructure. The slide block 30 is here shown to be formed with a vertical V- shaped guide 35 slidably receivable in a complemental way 36 formed within the vertical slot 32 in the aforementioned sub-frame block 34. Arrangements are made for adjusting the platen 26, and therefore the knife 20, horizontally toward and from the log by sliding on the slide block 30, guided by dovetail 29, and such arrangements may involve a hand wheel 40 and a suitable or conventional leadscrew device, not shown. Also, means are provided for vertical movement of the slide block 30 with reference to the stationary sub-frame block 34, and while in practice, for precision of work, suitable conventional power-operated feed mechanism can best be used for this purpose, I have here conventionally indicated simply a hand wheel 40 on a shaft journalled in platen 34 and which will be understood to be connected to any suitable gearing and leadscrew arrangements to the slide block 30 to permit gradual vertical downward feeding of the slide block 30, table 26, and therefore the knife 20, as the veneer is progressively cut from the log.
T'wo orbital-mass vibration generators 44 and 46 are shown mounted on and thus sonically coupled to the vibratory knife 20, the former being secured to an end of the knife, and the latter, in this example, to the rearward edge of the knife at substantially the mid-point thereof. These may be used alternatively, and in some cases together The generator 44 at the end of the knife is to be understood as positioned appropriately for setting up in the knife .a resonant standing wave vibration pattern extending longitudinally of the knife, and the generator 46 at the back edge of the knife is positioned to set up in the knife a resonant standing wave. pattern in a lateral mode, the vibration taking place in the plane of the blade. Reference being directed to 'FIG. 12, the longitudinal-type standing wave pattern, shown in a typical one-wavelength mode, is diagrammed at the bottom of the figure, while the lateral standing wave pattern, also of one wavelength, is diagrammed at the top of the figure. As stated hereinabove, the generators 44 and 46 can be used alternatively or together, and the patterns shown in FIG. 12 may thus occur either alternatively, or superimposed over one another.
The orbital-mass generators 44 and 46 are identical, and FIG. 4 shows a medial sectional view through one of the generators, in this instance the generator 46. The generator comprises a cylindric case or housing 50 having on one side a mounting plate 51 secured to the knife 20, and the housing 50 contains a cylindrical cavity 52 receiving an orbital-mass rotor 53, in this instance in the form of a metal disc of a diameter somewhat less than that of the cylindrical cavity 52. Air under pressure is supplied via a hose 54 leading to a nozzle or jet 55 which opens tangentially into the peripheral region of the cylindrical cavity 52 in housing 50, such that the injected air impinges upon the orbital-mass rotor 53 and causes it to gyrate in an orbital path around the inside of the chamber 52. A better or more complete design of such an orbital-mass generator appears in FIGS. 9 of my Pat. No. 2,960,314, and may be referred to for a more detailed showing of such a generator. The air pressure to hose 54 is controlled so as to bring about a driving force on the rotor 53 such as will cause its spin frequency, i.e. number of trips around cylindric cavity 52 per second, into the range of the resonant frequency of the knife 20 for the particular standing wave pattern to be produced.
It will be clear that the orbital-mass rotor 53, running around the inside of the housing 50, will, by virtue of centrifugal force, produce a rotating force vector intersecting the axis of the cylindric housing chamber 52 and exerted against the housing 50, and thus against the blade 20 to which the housing 50 is secured and coupled. A force rotating about the axis of the cylindric rotor chamber 52 is thus applied to the knife 20.
Consider now the generator 44 coupled to one end of the knife 20, with the axis of the cyindric rotor chamber 52 vertical, as indicated in FIG. 1, or in other words, at right angles to the plane of the knife 20. The rotating force vector generated by this generator 44 will be seen to be applied to the end extremity of the knife, and in the orientation illustrated, this rotating force vector turns in the plane of the knife. It will be seen that this rotating force vector will have components longitudinally of the knife, and also transversely thereof, both acting in the plane of the blade. Assuming the cyclic frequency of rota tion of the rotor '53 to correspond to the frequency of the knife 20 for a full wavelength longitudinal standing wave pattern, the component of alternating or cyclic force exerted by the generator 44 in the direction longitudinally of the blade will then set up a one-wavelength resonant standing wave pattern in the knife, as earlier mentioned, and as diagrammed at s1 in FIG. 12. A substantial component of vibration amplitude will then be developed at 8 the antinodal regions of the standing wave in the blade, as at V in FIG. 12. Also, nodes N, which are regions of zero or minimized vibration amplitude, will occur at points twenty-five percent inwardly from each end of the standing wave diagram. T o explain the diagram s1 somewhat further, it is to be understood that this diagram represents by the vertical distance between the two sinusoidal lines the vibration amplitude at different points along the length of the knife, the points V being at the two extremities of the knife and at the mid-point thereof, with the points N at twenty-five percent of the length of the knife inwardly from each of its ends. The knife 20 thus vibrates by elastic deformation movements taking place in the longitudinal direction of the knife, and with amplitudes as represented by the diagram. The component of force applied to the knife by the generator 44 in directions transversely of the blade are not at a resonant frequency of the blade, and hence are blocked by the reactance of the blade from developing material vibration amplitude in directions laterally of the blade. It should also be pointed out that the vibration generator 44 need only be oriented so as to develop a component of cyclic force longitudinally of the blade, and it is therefore immaterial 'whether the axis of the cylindric rotor chamber 52 is transversely of the knife 20, as illustrated, or in the plane thereof. In other words, the generator 44 could be rotated through ninety degrees about the horizontal axis longitudinally of the blade from the position illustrated in FIG. 1, and the necessary cyclic or alternating force longitudinally of the knife would still be applied.
Considering now the generator 46 mounted to the rearward edge of the blade, and oriented with the axis of the rotor chamber vertical, i.e., transversely of the blade, it will be seen that the rotor 53 of the generator 46 will r similarly develop a rotating force vector which will be applied by the rotor housing 50 to the rearward edge of the blade, with components of this force extending both laterally of the blade, and longitudinally thereof. The air pressure in this case is controlled to be such as to drive the orbital-mass rotor 53 at the resonant standing wave frequency for a lateral rather than a longitudinal mode of standing wave vibration. Thus, the component of force developed longitudinally of the blade will not be near a longitudinal resonant frenquency, and will produce only negligible amplitude vibration in the longitudinal direction. The lateral component of vibration, on the other hand, at the resonant frequency for a lateral mode of standing wave vibration, will develop substantial amplitude in a lateral wave mode, and for the full wave preferred pattern, the resulting standing wave pattern is as indicated at s1 in FIG. 12. [be space between the two curved lines of this diagram again are proportional at every point along the diagram to the corresponding amplitude of lateral vibration of the blade, and there are velocity antinodes V at the ends and at the mid-point, as diagrammed, while there are velocity nodes N at points which in this case are at approximately twenty percent of the length of the blade inwardly from each of its two ends.
Thus, by virtue of the longitudinal standing wave pattern s1 set up in the blade by the orbital-mass generator 44, longitudinal or slicing-type motion occurs along the cutting edge of the knife, this taking place by elastic deformation movements set up in the blade by the described longitudinal standing wave action. Also, by virtue of the lateral standing wave pattern set up in the blade by the orbital-mass generator 46, cyclic movements of the blade of an impacting or chopping type, i.e. toward and from the line along which the log is engaged by the knife edge, are set up in the knife, these being elastic deformation movements of the knife taking place in accordance with the lateral wave pattern s1 in FIG. 12. Two types of vibratory cutting action are thus available, and can be used alternatively or simultaneously, depending upon requirements of particular woods to be veneered.
It is to be noted that the mountings 22 of the knife 20 are located in the general regions of the nodes N and N of the two wave patterns posible, and thus the flexible mounting strap 24 need undergo only'minimized' vibration amplitude while supporting the knife during either of its modes of vibration. It will be further seen that the spring straps 24 can easily flex laterally or longitudinally to accommodate the small vibration amplitude of the knife in the regions where the straps are connected to the knife.
In operation, the knife is adjusted preliminarily to in the art, and only diagrammatically suggested here by i the slide block working up and down inside the frame component 34, under a feed control merely suggested by the hand wheel 40. The action of the elastic standing wave vibration set up in the knife by either one or both of the two vibration generators 44 and 46, and the improvement in veneer cutting obtained thereby, has been described in full detail in the introductory portion of the specification, and need not be repeated at this point.
Also, the virtue of the orbital-mass type of vibration generator in cutting of veneer has been described fully in the introductory portion of the specification. At this point it will only be necessary to recall that variations 'in the fiber structure of the log from point 'to point, such as changes in hardness and density, as well as contained moisture, result in corresponding changes in im-' pedance from point to point, and that these point-topoint changes in impedance can'take place not only along the log, but also around the log, and stillfurther,
from the initial periphery of the log to its center. All
such changes in impedance are accommodated bythe orbital-mass generator utilized in the practice of the invention, to the end of maximized power output'und'er changing conditions 'of impedance, and the incorporation of theorbital-mass type of vibration generator is deemed by me to be 'a major feature of the veneer cutting process and apparatus of the invention. This subject was exhaustively treated in the introductory portion of the specification.-
9 Illustrative examples of the sonic veneer drying process ment here suggested, are rotated from opposite ends in 'order to avoid interference between the driving pulleys 'for the two rollers. With reference to FIG. 6, the roller 62 will be seen to have a'hollow axle or sleeve" member 63, with a reduced extremity 64 mounted in bearings 65 on supports 66, and furnished, inside the bearings Iv 65, with tightly'mounted end plates 68. The endplates 68 are rotatable relatively to 'the -bearings 65 and the gap therebetween is eflectively closed by-seals such as indicated at 70. Between the end plates'68, and forming the periphery of the roller 62, aremounted porous cylinders 72, composed of a suitable porous' material with intercommunicating interstices formed therewithin and forming passageways therethrough. Suitable materials for the cylinders 72 are sintered metal, porous ceramic, a fibrous matrix, microporous absorbent plastic felt, or the like. As here shown, the cylinder 72 is further supported by radial webs or spokes 74. The end plates 68 are provided inside the location of the seals 70 with arcuate passages 75 providing communication between the interior space 76 of the roller and passageways 78 formed in the bearing 65, the ends of these passages 78 having coupled thereto inlet and outlet conduits 79 and 80 respectively, for intake and discharge of drying air. As shown, the end plates 68 are spaced somewhat from the adjacent bearings 65, permitting free communication from the arcuate passageways 75 to the passageways 78. As shown in FIG. 6, the length of the exterior porous cylinder or sleeve 72 is somewhat wider than the width of the veneer 60 cut from the log, as clearly shown in FIG. 6.
To accomplish vibration of the roller 62, I employ preferably a special form of vibration generator arrangement of the previously described orbital-mass type, and comprising in this instance an orbiting-mass roller 82 inside and of somewhat lesser diameter than the bore of sleeve 63, and positioned, in this illustrative instance, near the center of the sleeve 63. This roller 82 is driven rotatably through a universal joint at 86, and an axial shaft 88 rotatably mounted in an end bearing 89 fixed in one extremity of the sleeve 63, together with a driving pulley 90 on the outer extremity of shaft 88 and driven by a suitable belt and prime mover, not shown. On the end of the roller sleeve 63 is mounted a drive pulley 92, driven by a belt and prime mover, not shown. The pulley 92 is preferably driven at such a rate of rotation that the peripheral speed of the external porous sleeve 72 of the roller 62 is as closely as possible equal to the linear speed of travel of the veneer 60 coming from the veneering machine 15.
The pulley 90 for driving the orbital-mass rotor 62 around the inside of the sleeve 63 is driven at a rate of speed sufficient that the roller 82, gaining rolling traction against the inside surface of the sleeve 63, rolls around the inside of the latter, with centrifugal force holding the roller in tight pressural contact with the inside of the sleeve throughout the trip around. Further,
the pulley 90 and roller 82 are driven at such a frequency, in orbital trips, or cycles, per second, relative to the rotating sleeve 63, such as to correspond to a resonant standing wave frequency for the tube 63 for a lateral mode of resonant standing wave vibration. In the present -a radially oriented force vector which turns relative to the sleeve 63 at the resonant standing wave frequency for a full-wavelength lateral mode of standing wave vibration. In result, there is created in the sleeve 63 a gyratory type'of elastic deformation movement, which .is, in effect, the resultant of two linear vibrations taking place in planes at'right angles to one another, with a phase difference of ninety degrees. This type of gyratory standing 'wave vibration was described in my Pat. No. 2,960,317, in connection with FIGS. 1-4 thereof, and for a further description, reference may be had to said ,patent. It will sufiice herein to state merely that a gyratory type of wave action, in a pattern akin to that lnthe upper portion of FIG. 12, is set up in the sleeve -63, and that corresponding gyratory vibratory action is transmitted from the sleeve 63 through the webs or spokes 7! to the veneer engaging external cylinder 72. Such sonically vibrataory gratory action is thus applied tothe veneer 60. The roller 61 above the veneer has a similar action, which may be phased with that of the lower roller in any way desired for example such that the plywood is alternately squeezed between two rollers,
and the sonic vibration thus applied to the plywood works the moisture therein to the surfaces thereof, from which it is then absorbed in the porous external cylinders 72 of the two rollers 61 and 62. Drying air is continuously introduced via the tubing 79, travels longitudinally through the roller adjacent the inside surface of the porous sleeve 72, and is discharged via tubing 80, and this drying air picks up the moisture on the inside surface of the porous sleeve and carries it out. Thus a moisture gradient is established in the veneer by which the moisture, mobilized by the vibratory action against the surfaces of the veneer, is moved out of the veneer to the porous cylinders 72, inwardly through the latter, and then out with the current of drying air as described.
FIG. 8 shows a modification, wherein an orbital-mass generator 93 of the air-driven type described hereinabove is mounted on a support 93A with its housing 93B in engagement with the periphery of a veneer drying roller, such as the roller 62. The support 93A has sufficient flexibility to permit sonic vibratory action of the generator housing against the roller 62, and thus imparts sonic vibrationto the porous cylinder 72 of this roller, with corresponding improvement in moisture extraction as described hereinabove.
In FIG. is shown a further drying unit 94 which may be used with the drying rollers 61 and 62, in series therewith or alone. At this station, the plywood 60 passes over a porous pad or slab 95, under which is a perforated mounting plate 96 for the slab. Moisture draining from the porous blotter or slab 95 through the perforations in plate 96 may be caught by a tank 97 and carried away by pipe line 98.
Engaging the upper surface of the veneer 60, above and substantially coextensive with the slab 95, is a vibratory foot 100 on the lower end of an elastic bar or beam 102, at the top of which is mounted an orbital-mass vibration generator 104 of the general character heretofore described. Thus, the generator 104 may comprise a housing 105 having a cylindrical chamber 106 therein, disposed with its axis horizontal, and in which is an orbital-mass roller 106 driven by any suitable means as an air jet, illustrated more particularly, for instance, in FIG. 4, but omitted, for simplicity, from FIG. 5. The air pressure is again so regulated as to cause a cyclic output force from the generator housing such as Will set up in the structure a longitudinal half-wavelength standing wave, of a longitudinal type, such as diagrammed in FIG. 5, the standing wave in this instance having a node at N, and velocity antinodes V at the top and V at the bottom, i.e. at the foot 100. Because of the mass of the foot, the node is displaced downwardly from the mid-point of the standing wave pattern, and there is a reduced amplitude of vibration at the lower velocity anode V, i.e. at the foot, as compared with that at the upper velocity antinode V, where the vibration generator is coupled in. The lower face of the foot 100 is thus vibrated against the veneer, setting up conditions within the veneer which are generally equivalent to those produced by the two vibratory rollers 61 and 62. The action again is to mobilize the moisture within the veneer, causing it to flow from or be squeezed from the veneer, and absorbed by the porous blotter or slab 95. The porous material of the slab 95 may again be sintered metal, porous ceramic, a fibrous matrix, microporous absorbent plastic felt, or the like.
Preferably, and in the present instance, the foot 100 has a cavity 110 therein and perforations 111 in its bottom through which fluid within the cavity 110 may pass to the upper surface of the veneer 60. A pipe 113 is coupled to chamber 110, and may be used to convey to said chamber a volatile liquid, which, under the influence of the vibrating foot 100, is worked into the veneer, forcing the Water out ahead of it and down into the porous plate 95. This volatile liquid subsequently evaporates from the veneer. As an alternative, a non-evaporative liquid, such as a preservative, can be used in this system, and will then stay in place.
I have also shown in FIG. 5 the use of a pipe 119 leading into the porous plate 95, and which can be used for introduction to the porous plate of a salt solution for improvement of desired osmotic action in the porous plate.
Reference is next directed to FIG. 10, showing an alternative drying system 120. In this case, the veneer 60, after typically passing through rollers soch as the rollers 61 and 62 of FIG. 5, passes through a long rectangular chamber 122 defined by a pair of parallel resonator plates or sounding boards 124 and 125 at the top and bottom, and at the sides or edges by overlapping edge plates such as 126 and 127 (FIG. 11). The upper resonator plate is spring supported at points located approximately twenty-five percent from each of its ends by means of suspension springs 128. The lower plate 125 is spring sup ported at positions approximately twenty-five percent inward from each of its ends by means of rubber insulation supports 129. Orbital-mass generators 130 and 132, of the general type previously described, are mounted on the ends of the plates 124 and 125, and are oriented such as to produce sonic resonant standing wave vibration of the resonator plates, the wave pattern being preferably a lateral type, such that the plates 124 and 125 move toward and from the veneer 60 passing therebetween. Hot air nozzles 134 introduce hot drying air into the chamber 122 between the resonator plates 124 and 125 and this air travels longitudinally through the chamber 122 and out the front end thereof. The sonically vibrating resonator plates 124 and 125 acoustically couple to the hot drying air, which is thus set into sonic vibration, so that a sonic wave train is established at the interface between the hot drying air and the veneer. The sonically vibratory air at this interface then couples to the veneer, producing sonic pressure pulses therealong and resultant vibration in the veneer such as contribute to mobilizing the moisture in the veneer and bringing it to the surface to be dried and carried away by the circulated hot air. A moisture gradient is thereby established in the veneer, between its medial plane and each of its two outside surfaces, such as leads to accelerated travel of moisture from the interior to the outside. Improved drying is thereby obtained.
The invention should now be understood from the several illustrative embodiments thereof described and illustrated, and from the discussion of the basic principles of the invention contained in the introductory portion of the specification. It will now be entirely evident to those skilled in the art how the theoretical discussion given preliminarily applies to each of the several illustrative physical embodiments of the invention.
1. The process of drying a water-containing matrix, such D as a strip of wood veneer or the like, that comprises:
sonically vibrating said matrix by transmitting elastic vibrations through a solid structure to said matrix, said vibrations being directed so as to provide a vibrational component normal to the surface of the matrix so as to subject the matrix to cyclic elastic squeezing action, whereby to mobilize the water contained therein and promote its flow from the interior to an outside surface thereof; and
removing the expressed water from the outside surface of the veneer.
2. The subject matter of claim 1, including removing said expressed moisture by transmitting along said surface of said matrix a stream of drying air.
3. Apparatus for drying a water-containing matrix such as a strip of wood veneer or the like, that comprises:
a drying medium applied to a surface of said matrix;
means for vibrating the matrix while exposed to said drying medium, said means including a solid elastic structure and oscillator means for generating in said structure elastic vibration normal to the surface of the matrix so as to cyclically squeeze said matrix.
4. The process of drying a water-containing matrix, such as a strip of wood veneer or the like, that comprises:
sonically vibrating said matrix, whereby to mobilize the water contained therein and promote its flow from the interior to an outside surface thereof; and removing the expressed water from the outside surface of the veneer by applying thereto a porous blotting element adapted to absorb said expressed water.
5. The subject matter of claim 4, wherein said matrix is sonically vibrated by setting up sonic vibrations to be transmitted therefrom into said matrix.
6. Apparatus for drying a water-containing matrix such as a strip of wood veneer or the like, that comprises:
a drying medium applied to a surface of said matrix, said drying medium comprising a porous blotting element adapted to be contacted by the matrix, and including means for elastically vibrating said porous blotting element, and
means for vibrating the matrix while exposed to said drying medium.
7. The subject matter of claim 6 wherein said porous clement includes a porous guide roller for a longitudinally traveling strip of the matrix.
8. The subject matter of claim 7, including means for elastically vibrating said roller.
9. The subject matter of claim 7, wherein said porous roller is hollow, and including also means for circulating a drying gas through said porous roller.
10. The subject matter of claim 8, wherein said means for elastically vibrating said roller is arranged for setting up resonant elastic standing wave vibration in said roller.
References Cited UNITED STATES PATENTS 2,740,202 4/1956 Fowle 34-164X 2,939,223 6/1960 Smith 34-164X 2,960,314 11/1960 Bodine, Jr l65-l 3,175,299 3/1965 Boucher 34--4 FREDERICK L. MATTESON, Primary Examiner R. A. DUA, Assistant Examiner us. c1. X.R. 34-18, 14, 164