US3896559A

US3896559A - Machine for drying by contact veneers obtained by peeling or slicing wood

Info

Publication number: US3896559A
Application number: US455001A
Authority: US
Inventors: Jean-Marie Michel Martin
Original assignee: Individual
Current assignee: Phillips Drill Co Inc
Priority date: 1973-03-28
Filing date: 1974-03-26
Publication date: 1975-07-29
Anticipated expiration: 1992-07-29
Also published as: IT1011641B; DE2414654A1; DE2414654B2

Abstract

A veneer drying machine comprises coacting endless flexible conveyor belts between which the sheets of veneer are conveyed on a path that passes between superposed pairs of heating plates. The upper of the two heating plates is vertically movable to permit movement of the coacting conveyor belts therebetween. When the upper heating plate is lowered, the conveyor belts with the veneers between them are held stationary and veneers are then dried. An overhead hood withdraws steam emitted by the hot veneer.

Description

United States Patent Martin July 29, 1975 54] MACHINE FOR DRYING BY CONTACT 1,741,882 12/1929 Robinson 34/159 x I 0R 3,367,261 2/1968 Kashiwagi... 34/162 x gigg ggg BY PEEL NG 3,418,727 12/1968 Morris 34/162 x SL1 3,503,140 3/1970 Hildebrand 34/162 Jean-Marie Michel Martin, 23, rue de Turin, 75008 Paris, France Filed: Mar. 26, 1974 Appl. No.: 455,001

Inventor:

Foreign Application Priority Data Mar. 28, 1973 France 73.11060 Feb. 28, 1974 France 74.06808 U.S. Cl 34/162; 34/66; 34/161 Int. Cl. F26b 9/00 Field of Search 34/151, 161, 162, 62, 66,

References Cited UNITED STATES PATENTS Daly 34/162 X Primary Examiner-William F. ODea Assistant Examiner -Harold Joyce Attorney, Agent, or Firm-Young & Thompson [57] ABSTRACT A veneer drying machine comprises coacting endless flexible conveyor belts between which the sheets of veneer are conveyed on a path that passes between superposed pairs of heating plates. The upper of the two heating plates is vertically movable to permit movement of the coacting conveyor belts therebetween. When the upper heating plate is lowered, the conveyor belts with the veneers between them are held stationary and veneers are then dried. An overhead hood withdraws steam emitted by the hot veneer.

6 Claims, 4 Drawing Figures PATENTEU JUL 2 9 I975 SHEET mm QE Qw Qmm MACHINE FOR DRYING BY CONTACT VENEERS OBTAINED BY PEELING OR' SLICING WOOD This machine has bee'h-devisedfor putting" into application, on an industrial and rational scale, two methods which are known and already used separately in the manufacturing industry of veneers from peeled or sliced pieces of wood or timber, namely a method of contact drying and that method particularly known in the United States of America and in Canada under the name of Tray System.

The first basic method already employed in the art consists in drying veneers between two plates belonging to a heating press. This method has been and is still utilized at the present time in a haphazard manner, either for stabilizing veneers which have already been predried or for drying verythin veneers assembled in more or less thick stacks or alternatively for drying strong and fairly thick veneers grooved plates. l-leretofore, this method was very little used, due to the fact that a heatingplate press of known type has always proved to be ill-suited in itself for the drying of veneers, especially in the usual practice of the manufacturing processes for veneers and plywoods.

The primary object of the invention is to provide a remedy for these disadvantages.

The second basic method already employed and known under the name of Tray System is directed to the mechanized taking-on load of veneers for the purpose of storage at the outlet, for example of a woodpeeling or slicing machine for obtaining veneers in such manner as to enable these machines to work at their maximum speed and then to deliver the veneers thus stored to subsequent machines such as a guillotine or a continuous drying machine.

- This method, known as the Tray System, is generally carried out by a belt conveyor comprising one or several stages, driven machanically at speedscompati'ole both with the output of the leading machine and with the receiving device of the machine next following.

This known installation may also be equipped with lower and upper belts enabling the veneers to be continuously received, retained, stocked and conveyed between two conveyor belts.

This is always the case in particular for the so-called S-Tray System utilisable especially in conjunction in one of the methods of construction of the improved machine according to the invention.

A further object of the invention is, therefore, to enable a drying machine to be obtained for contact drying of so-called peeled or sliced veneers, this machine being so designed as to effect this drying operation in substantially shorter times, with a reduced expenditure of heat and power than in the veneer-drying methods carried out with hot air as employed up to the present time, while offering the advantage of obtaining dry veneers which are absolutely flat, properly stabilized and homogeneous.

This improved machine for contact drying of veneers obtained from peeled or sliced pieces of wood comprises, in combination, an assembly of heating plates in stages, arranged in sets of two on the uprights of the supporting frame, and between which two movable conveyor belts are capable of performing an S circuit,

these belts being adapted to receive the veneers to 'bet dried, supplied at the outlet of thewoodpeeling or slicing machine, one of the heating plates o f each of these sets being so arranged as to move away from the associated fixed heating plate, and conveyor belts in order simultaneously to effect the drying of the veneers by contact.

According to a particular feature of the invention, the respective working faces of the heating plates in stages and arranged in sets of two are smooth or provided with grooves, striations of a lining.

According to another feature of the invention, each of the heating plates, arranged so as to move away from the fixed heating plate and from the conveyor belts, comprises devices associated with guiding slots formed in the uprights of the supporting frame, the fixed heating platesresting on members rigidly secured to these uprights.

in accordance with another characteristic feature of the invention, the machine comprises a device permitting through the intermediary of the heating plates, the application on the veneers of an effective adjustable pressure in identically the same way as that of a hydraulic press comprising heating plates.

According to another feature of the invention, one of the conveyor belts between which the veneers to be dried are placed when secured by the outlet of the wood-peeling or slicing machine is formed of a woven mesh of fine metal wire, the other conveyor belt being formed of a thin sheet or leaf of plastic material, these conveyor belts being driven and guided by a plurality of drums carried by the supporting frame.

According to a still further feature of the invention, the machine comprises a plurality of conveyor belts arranged in stages and in sets of two, driven by a number of drums carried by the supporting frame, these tiered conveyor belts first moving in a zone located outside an assembly of heating plates and then between these plates which are tiered and arranged in sets of two, of which one can be slipped from the tiered conveyor belts, the veneers to be dried and the associated fixed plate, these veneers being brought between the tiered conveyor belts by a device comprising a single conveyor belt, one of the driving drums of which is connected to an angularly movable arm permitting this conveyor belt to be brought level with each set of tiered conveyor belts for the purpose of their supply with veneers to be dried, which are collected after the drying operation by an identical device.

According to a still further feature of the invention, the angularly-movable arm permitting the feed of the conveyor belt supplying the machine with veneers to be dried, and also the mobile arm permitting the dry veneers to be collected on the receiving conveyor belt are ointly associated respectively with a guiding member made of spaced belts made of a plastic material, the veneers being collected after the drying operation on a conveyor belt of the same kind.

The following description, given by way of example and not in any limitative sense, will enable the invention to be more clearly understood, reference being made to the accompanying drawings, in which:

FIG. 1 shows a first embodiment of the machine for contact drying of veneers obtained by peeling or slicing wood in accordance with the invention;

FIG.2 shows another embodiment of this machine;

FIG. 3 is an alternative form of construction of a group of conveyor belts;

FIG. 4 shows another alternative form of construction of machine according to the invention.

The machine for contact drying of veneers obtained by peeling or slicing wood shown in FIG. 1 comprises a supporting frame provided with

uprights

1 and 2 coupled together at their upper end by cross-members 3 and on which is mounted a plurality of heating plates 4 movable in height and fixed plates 5, tiered and arranged in sets of two. These plates constitute an internal circuit through which flows a heating fluid in identically the same way as the plates of a hydraulic press equipped with heating plates.

The machine also comprises two

conveyor belts

6 and 7 provided at the outlet of the wood-peeling or slicing machine and intended to convey the veneers 8 to be dried towards the sets of

heating plates

4 and 5, these conveyor belts being respectively driven by

drums

9 and 10 carried by

bearings

11 and 12 supported by the uprights l3 and 14.

Two

intermediate drums

15 and 16 are supported by

bearings

17 and 18 so arranged that the

conveyor belts

6 and 7 are correctly tightened continuously. The conveyor belt 6 is composed of a woven mesh of fine metal wire while the conveyor belt 7 is formed either of a woven mesh of fine metal wire or a thin sheet of metal or a thin sheet of plastic material.

Between each set of

heating plates

4 and 5, the

conveyor belts

6 and 7 move along a circuit of S-form by means of driving drums l9 and 20 supported by

bearings

21 and 22 carried by the

uprights

23 and 24 which are connected to the uprights 13 and 14 by the

crossmembers

25 and 26.

The heating plates 4 are provided with studs 27 associated with guiding slots 28 formed in each of the 1 and 2 in order to enable said plates to be slipped from the fixed plates 5 which rest on elements 29 rigidly fixed to the uprights l and 2, and thus to be brought into a position in which they are applied against the veneers 8 to be dried and against the fixed plates 5, either by means of an adjustable pressure or by their own weight.

The respective working faces of the

heating plates

4 and 5 are either smooth or provided with grooves, striations or a lining for the same purpose.

A suction hood 30 is arranged at the upper part of the machine in order to permit evacuation of the steam which is evolved during the course of the drying operations hereforward on the veneers.

The veneers 8 to be dried are picked up at the outlet of the wood-peeling or slicing machine and brought to the conveyor belt 6 in the direction indicated by the arrow 31, the heating plates 4 then occupying the position shown in FIG. 1, that is to say, they are moved apart from the veneers 8 to be dried and from the fixed plates 5.

At a definite moment, the drive of the conveyor belts is stopped and simultaneously the heating plates 4 are lowered by virtue of the action of the studs 27 in cooperation with the guiding slots 28, which makes it possible to carry out contact-drying of the veneers 8. When the conveyor belts are stopped, the veneers are held motionless between the

heating plates

4 and 5.

The plates 4 are then lifted and simultaneously the conveyor belts are again started up in order that the veneers to be dried, which were outside the heating plates, may pass between the latter. At that moment, the conveyor belts are again stopped and the heating plates are once more lowered, the veneers thus trapped being completely dried, whereby after final lifting of the plates 4, the veneers are directed towards a guillotine cutting device as indicated by the arrow 32.

During the course of each veneer-drying operation,

the evacuation of the steam in the zone corresponding to the

heating plates

4 and 5 is effected through the conveyor belt 6, while the instananeous transmission of the heat permitting the rapid discharge of the water contained in the veneers is effected through the conveyor belt 7 and by direct contact, another portion of the heat being transmitted by the conveyor belt itself.

This machine makes it possible to reduce the drying time to a considerable extent due to the face that the coefficient of heat transmission is higher than that of transmission by hot air (from the beginning to the end of the drying cycle). The temperatures which can be used are furthermore definitely higher and may even reach 200 to 300C.

The drying time thus obtained varies between 5 and 60 seconds. It may be reduced to 5 seconds for example for a veneer of walnut of 0.6 mm. in thickness, to 15 seconds for a mahogany veneer of 1 mm. in thickness, and to 20 seconds for a veneer of pine interior or poplar interior of 2.5 mm. in thickness.

In the alternative form of construction shown in FIG. 2 in which the conveyor belts and the veneers to be dried move first of all in a Zone located outside the heating plates, the machine for contact-drying of socalled peeled or sliced veneers comprises, as in the previous examples, a supporting

frame including uprights

33 and 34 connected at their upper portion by cross members 35, and on which is mounted an assembly of heating plates 36 movable in height and fixed plates 37, tiered and arranged in sets of two.

The machine also comprises a series of tiered belt conveyors arranged in sets of two, each of these sets 38-39, 38a39a and 38b-39b being associated with one of the sets of heating plates, the conveyor belts being driven by drums 40 and supported by

bearings

44 and 45 carried by the

uprights

46 and 47 coupled together at their upper portion by cross-members 48.

As in the previous example, the heating plates 36 are provided with studs 49 co-operating with guiding slots 50 provided in each of the

uprights

33 and 34 in order to enable these plates to move away from the fixed plates 37 which rest on elements 51 rigidly fixed to the

uprights

33 and 34 and thereby to be brought, as in the previous example, to a position in which they will apply on the veneers to be dried 52 and on the fixed plates 37, either an adjustable pressure or the action of their own weight.

The veneers to be dried 52 are brought between each set of belt conveyors 38-39, 38a-39a and 3812-39!) by a single supply belt conveyor 53 driven by drums of which one, 54, which is normally present in the immediate vicinity of the drums 40, is coupled to angularly movable arm 55 provided with an a slot 56 in which is engaged the shaft 57 of this drum also engaged in a guiding slot 58 formed in an element 59 coupled to one of the uprights 46 carrying the bearings 44 of the drums.

This machine operates in the following manner:

The veneers to be dried 52 are brought to the outlet of the wood-peeling or slicing machine-(as indicated by the arrows 60) by the supply belt conveyor 53 which may be presented, by virtue of the moving arm 55, either as shown in full lines in FIG. 2 or as drawn in broken lines at 53a or at 53b in such manner as alternately to supply the veneers to be dried to the sets of conveyor belts 3839, 3811-390 and 38b39b, the contact-drying taking place during the lowering of the heating plates 37 as in the previous example.

After drying, the veneers are directed on to a single receiving conveyor belt 61 driven by drums of which one, 62, which is normally in the immediate vicinity of the drums 41, is coupled to an angularly-movable arm 63 identical with the arm 55, and which is provided with a slot 64 in which is engaged the shaft 65 of this drum, also engaged in a guiding slot 66 formed in an element 67 coupled to one of the uprights 47 carrying the bearings 43 of the drums 41, the single conveyor belt for receiving the dry veneers being able to be presented either as indicated in full lines in FIG. 2, or as shown in broken lines at 61a or 61b, so as to receive alternately the dry veneers coming from the sets of tiered belt conveyors in order to direct these veneers towards a guillotine cutting device, for example, as indicated by the arrow 68.

In this way, by utilizing this form of the machine, it is possible to supply veneers to be dried successively by means of a single belt conveyor 53 to each set of tiered conveyor belts intended to bring these veneers between the

heating plates

36 and 37. It is also possible to transfer the veneers by means of a single conveyor belt 61, after drying.

In this embodiment of the invention, the

conveyor belts

38,38a and 38b are composed of a woven mesh of fine metal wire while the

conveyor belts

39, 39a and 39b are formed of a thin sheet of metal or a thin sheet of plastic material.

A suction hood 69 is arranged at the upper portion of the machine above the sets of

heating plates

36 and 37 in order to permit the evacuation of the steam which evolved during the drying operations of the veneers.

For the sake of clearness, there has not been shown in FIGS. 1 and 2 the alternative form in which the machine would comprise a device enabling the application, through the intermediary of the heating plates 4 and'5 and 36 and 37, on the

veneers

8 and 52 to be dried, of an effective pressure variable in identically the same manner as that of a hydraulic press comprising heating plates of a type known per se.

There has been shown in FIG. 3 a particular arrangement of the conveyor belts. The latter move in this case between the heating plates formed by parallel adjacent belts 70 consisting of a woven mesh of fine metal wire or a thin sheet of metal or a sheet of plastic material, the veneers to be dried being brought on these parallel juxtaposed belts by a conveyor belt composed of ordinary spaced-apart belts 71 of plastic material, the veneers being collected for example after drying, on a conveyor belt also constituted by ordinary belts spaced apart, these belts 72 being advantageously made of plastic material.

In FIG. 4 of the drawings is shown another embodiment of the improved machine which involves several improvements over the aforesaid combination.

According to a first improvement, the

belt conveyors

6 and 7 as illustrated in FIG. 1 and the

conveyor belts

38 and 39 as illustrated in FIG. 2 may be both made of woven metal fabric, thus permitting them both on the two faces of the veneer to achieve adequate transmission of heat and local evacuation of steam due to the drying.

According to a second improvement, each mobile heating plate 36 of the embodiment shown in FIG. 2 may be so provided as to have a raising and lowering movement independent of the movement of the other moving plates. This means that the plate 36 of the upper tier of the dryer may be in the raised position while the plates 36 of the lower tiers are in the lower position. Under these conditions, the

raisable conveyor belts

53 and 61 assume the

positions

53b and 61b, corresponding to the upper tier. The whole of this tier is in a position for conveying veneers while the lower tiers of the dryer are in the position for drying the veneers, with the plates 36 in their bottom position.

Under these circumstances, the assembly of the

belts

53b, 38b, 39b and 61b moves forward over a path equal to the length of the heating plates. The dry veneers located between the

plates

36 and 37 of the upper tier are then extracted from the dryer and replaced by the same length of moist veneers. The plate 36 of this upper tier is then lowered so as to begin the drying of the veneers at this tier, the two

belts

53 and 61 are lowered to the

positions

53a and 61a and the plate 36 of this second tier of the dryer is raised.

The entirety of the second tier thus occupies the conveying position of the veneers, while the other tiers, including the upper tier, are in the drying position, and

so on. Each upper plate 36 has an independent lifting device with hydraulic or pneumatic jacks (not shown) enabling each tier to operate independently of the others and successively.

In the embodiment shown in FIG. 4 of the drawings, there are provided two assemblies or stacks of plates: a first vertical stack of

heating plates

36 and 37 and a second stack of cooling plates 36a and37a. The second stack of plates is absolutely identical to the first one in all respects except for the fact that the

plates

36 and 37 belonging to the first stack are traversed by a cooling fluid. The raising and lowering motion of the heating plate 36 and of the cooling plate 36a of one tier are effected at the same time. They may even be fixed together with of course the interposition of the heatinsulating member 73.

The fixed

plates

37 and 37a of each tier may also be secured together with the interposition of a heatinsulating member 73.

During the conveying period of the veneers, the heating plate 36 and the cooling plate 36a of the tier considered are therefore raised, the belts move forward by the length of one plate and itfollows that a length of moist veneers is introduced between the heating plates 36-37, a length of dry and hot veneer is introduced between the cooling plates 36a-37a, and a length of dry and cool veneers is extracted from the dryer.

The device according to this modified construction is especially advantageous when, in spite of starting with a ribbed variety of wood, it is desired to obtain, for facilitating the subsequent treatments of the veneers, dry, cool and absolutely flat veneers.

In addition, the veneers thus treated pass out of the dryer without having undergone any shrinkage and therefore without any fissure, split or tear inherent with such shrinkage. They are, furthermore, very flexible.

The joint action of the heating and cooling plates which has just been described is applicable to the construction shown in FIG. 1.

The method of using the machine as above described may be varied as regards one or more possible lifting operations of the upper heating plates 36 during the course of the drying position of the veneers of the corresponding tier.

According to this modification, the upper heating plate 36 of a given tier occupying the bottom position, that is to say, the position for drying the veneers may, instead of remaining in this lower position during the whole period of drying, be raised once or several times during this period of drying, the number of lifts and the exact cycle of these lifts being variable and previously adjustable in dependence of the purpose to be fulfilled.

In fact, by leaving these plates in the bottom position during the entire drying period, there is obtained a dry veneer which is practically devoid of shrinking or as a maximum by about 1%. This is not a disadvantage for a number of given varieties of wood (poplars and gaboons for example) and for future applications of these veneers.

For other varieties of wood, micro-fissures then appear and may be incompatible with subsequent uses of these veneers with visible faces. This is the case for example with woods such as beech or ash and with many veneers obtaines from sliced wood.

The utilization of lifting devices such as those which have been shown at 49 and 50 in H0. 2 of the drawings enables these lifting operations of the heating plates (FIG. 2) to be carried out, which has the consequence of removing these possible disadvantages by permitting shrinkage of the veneers while preserving furthermore all the properties which form the advantage of this new machine, namely: flatness, very short drying time, large economy of total power consumption, very low and uniform final moisture content. Shrinkage is furthermore effected in this case without the appearance of any tearing on the complete strip of veneers.

According to another modification, each of the

heating plates

36 and 37 may be constituted, not by a single plate formed by a thick steel sheet grooved with channels for the circulation of the heating fluid, but with plates of this type of small size and arranged alongside each other so as to form a plate of large size, the construction of which, in a single piece, would be more costly.

It is envisaged that, according to another modification of the invention. these heating plates could be constituted by tubes of square or rectangular section inside which the heating fluid circulates and which are simply juxtaposed so as to reconstitute a heating plate. The advantages of such an improvement are to permit construction at a lower production cost, to permit evacuabe arranged in the interior of each square tube in order. to eliminate this difference in temperatures. These.

tubes may be juxtaposed according to the dimensions of the machine, either in the transverse direction or in the longitudinal direction.

According 'to a still further modification, the .conveyor belts may be made of a special woven metallic fabric utilizing especially stainless steel wire or aluminum alloy wire for example,'so as to avoidany possible reaction'between the sap of the green veneer and an ordihary steel wire, which reactions might be the cause of stains on these veneers.

Minor constructional details may be varied without departing from the scope of the subjoined claims.

I claim:

1. A machine for drying by contact veneers obtained from peeled or sliced wood, comprising in combination a frame, a plurality of pairs of heating plates supported on the frame, the plates of each said pair being vertically superposed and said pairs being disposed one above the other, the upper heating plate of each pair being vertically movable on and relative to the frame toward and away from the lower heating plate of each pair, a plurality of endless flexible conveyor belts, means positioning a pair of runs of two said belts between each said pair of heating plates to move between said plates veneers disposed between said runs when said upper plates are raised and to retain said veneers motionless between said plates when said upper plates are lowered into contact with the upper of said runs, and a hood above said heating plates for removing steam emitted by said veneers.

2. A machine as claimed in claim 1, at least one of said belts being of woven metal wire.

3. A machine as claimed in claim 1, said upper plates being mounted for vertical movement on said frame by means of cooperative stud and slot means carried on said frame and upper plates.

4. A machine as claimed in claim 1, there being two said endless conveyor belts individual to each said pair of plates.

5. A machine as claimed in claim 1, there being two said conveyor belts common to a plurality of said pairs of plates and extending in zigzag fashion between said pairs of plates. I

6. A machine as claimed in claim 1 and cooling plates between which said runs pass after passing between said heating plates.

Claims

5. A machine as claimed in claim 1, there being two said conveyor belts common to a plurality of said pairs of plates and extending in zigzag fashion between said pairs of plates.

6. A machine as claimed in claim 1, and cooling plates between which said runs pass after passing between said heating plates.