CH615990A5 - Apparatus for vacuum drying flat and flexible articles made from a porous material - Google Patents

Abstract

A cylindrical surface (6) used as a support for the articles (19) to be dried can rotate around its axis in order to allow the articles to be dried (19) to be spread out suitably. This support surface (6) is heated by heating means located inside the support surface (6). At least one lid comprising a flexible leaktight membrane (15) fits onto the support surface (6). On its internal surface, the membrane (15) is lined with a mat of a porous material (16), and is fitted on its periphery with a seal (17) intended to be applied onto the support surface (6). The lid (15) is used to enclose at least one article (19) to be dried which is laid down on the support surface (6) in a hermetically sealed space. Finally, means (20-23) are provided for connecting this hermetically sealed space to a vacuum source (24) when the lid is applied onto the support surface (6), which allows rapid drying at moderate temperatures. The apparatus described is used for vacuum drying flat and flexible articles made of a porous material. <IMAGE>

Description

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CLAIM so as to cooperate with the covers (15,31) for maintenance

1. Apparatus for vacuum drying flat parts and in the closed position all the covers minus one, the flexible position made of porous material, comprising an open serving surface of the said cover allowing the spreading of a support piece for the at least one part to be dried, means for drying (19) on the exposed part of the heating support surface placed on the opposite side of said support surface, to the cylindrical (6), said cover (15,31) being progressively less a cover comprising a waterproof membrane, flexi- closed by the action of the fixed rim (36) when the surface-

ble but not extensible, lined, on its face in contact with the support (6) is rotated by a surface-support motor-reducer-variator, a mattress of porous material and provided with speed (30), the valve sectioning (22) of each sound around a seal intended to be applied to the drying sector being open to create a vacuum under the support surface, each of said covers serving to enclose 10 membrane (15) of the cover (15,31) corresponding when this at least one piece to be dried deposited on the corresponding part is completely closed and being simultaneously closed between the support surface in an airtight space and upon release of the corresponding cover from the action of the rim means making it possible to connect said hermetic space to one (36) which allows said cover to open, releasing a source of vacuum, characterized in that the support surface (6) has a dry part, the speed of rotation of the surface-support cylin dri-

cylindrical in shape and is arranged so as to be able to rotate with (6) being adjustable according to the duration of the desired drying.

around its axis and that the membrane-cover (15) comes to fit on the support surface, cylindrical heated.

2. Apparatus according to claim 1, characterized in that

the cylindrical support surface (6) is associated with a single mem-.

rectangular bran-cover (15) the length of which corresponds to 20 The object of the present mvention is a device for substantially the length of the circumference of the surface- dried under the shape of flat parts and f, exlbles in cylindrical support material (6) and of which the peripheral seal.

that (17) is applied by one (17A) of its sides on a first In a first category of devices known to this generator (A-A ') of the cylindrical support surface (6), by 8enre'la surface serving as a support For the P, ècf to be dried, on its opposite side (17B) on a second generator (D-D ') of the 25 a flat heated space, in horizontal or inclined position, surface- cylindrical support (6) located very close to the first of relatively limited dimensions so that the generator operators (A-A ') and by its lateral sides (17C) on two powerful arcs spread out the parts to be dried suitably. However, the circumference of the support surface (6) each located at the minimum economically acceptable dimensions does not

in the vicinity of one end of the said support surface does not cause the operators to spread all of the drique properly (6) 30 Parts of the parts to be dried, some of which are not good

3. Apparatus according to claim 2, characterized in that carried to perform a good job, which results in one (15A) of the edges of the membrane-cover (15) is fixed Loss of surface dltes Parts and d ° nc an economic loss according to the first generator (A-A ') of the significant support surface. In addition, the limited dimensions of the supercylindrical surfaces (6) while the opposite edge (15B) of the membrane - Port Planes do not allow parts of large cover (15) to be dried is fixed according to a generator (C- C ') of a size which must therefore be divided, which makes them impro-drum (11) on which the membrane-cover (15) can be used for certain purposes and decreases their value.

roll in the opposite direction of its winding on the support surface ar elsewhere, the production obtained using a single cylindrical (6), the drum (11) being supported surface-heated surface is relatively low. A production

rotary, by an oscillating frame (9) placed under the action of at least the average industrial one requires several.

a spring (25), so that the drum (11) is pressed 40 In the case of known plane support surfaces this against the cylindrical support surface (6) according to a generative multiplication of individual devices or groups of common appliances (B-B ') are of a high cost and occupy an important place.

4. Apparatus according to claim 3, characterized in that In another category of known apparatus, the parts to

the drum (11), to be rotated, is connected to a dryer are deposited on a heated cylindrical support surface

reversible two-speed gearmotor (13) so as to be partially enveloped by an endless flexible band rotating, as a result of the pressure exerted intermittently following the turn. True drying can not generate common (B-B '), the cylindrical support surface (6) Not be practically carried out in an apparatus of this kind because:

and this at lower speed during the winding of the mem- ~ s endless flexible band is waterproof, there can be brane-cover (15) on the drum (11) on the surface- no evaporation of the liquid contained in the rooms to be dried:

cylindrical support (6) until the seal (17) so "51 the endless flexible band is porous, 1 occurs well is completely applied to the support surface (6), and to a tr® s slow evaporation of this liquid but 1 experiment at higher speed during the reverse winding of the mem- ber shows that pieces to be dried usually containing 60 bran-lid (15) on the drum (11). 100% of ll £ luide By dry matter report require

5. Apparatus according to claim 1, characterized in that drying time of about 30 minutes at a temperature the cylindrical support surface (6) is divided into several sec- 55.d'environ 90 C which is unacceptable for good quality of the teurs (CD, DE, EF, FC), each one equipped with a product cover. At a temperature below 50 C necessary for a key comprising a frame (31) connected by one of its sides, to maintain the quality of the products, drying lasts from 1 to 3

means of hinges (32) on a generator of the surface-hours.

cylindrical support (6), which frame (31) supports the mem- Production resulting from an apparatus of this kind is therefore brane-cover (15), each of these sectors thus equipped con- 60 reduced to a few pieces per day, which shows that this setting up a separate drying area linked individually to the design does not respond to actual use. In fact, the vacuum sources (24) by means of a section valve - devices of this kind are only used for ironing individual nements (22). parts and not for drying.

6. Apparatus according to claim 5, characterized in that the present invention essentially aims to put the cover (15,31) of each drying sector is placed under 65 available an apparatus for vacuum drying of parts action of springs of its hinges (32) in order to bring it into flat and flexible porous material, which avoids the inconve-an open position and in that the support surface (6) is nients mentioned above and facilitates the work of operators by partially surrounding them with at least one fixed rim (36) designed to always work in the same place located at a

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convenient height and at a suitably small distance in front of them. Another object of the invention is to create an apparatus which is of relatively compact construction and does not require much maneuvering space to open and close the cover (s).

The apparatus according to the invention comprises a surface serving as a support for at least one part to be dried, heating means placed on the opposite side of said support surface, at least one cover comprising a waterproof membrane, flexible but not extensible, filled , on its face in contact with the support surface, a mattress of porous material and provided on its periphery with a seal intended to be applied on the support surface, each of said covers serving to enclose at least a part to be dried deposited on the corresponding part of the support surface in an airtight space and means making it possible to connect said airtight space to a vacuum source, this apparatus being characterized in that the support surface has a cylindrical shape and is arranged so that it can rotate around its axis and the membrane-cover fits over the heated cylindrical support surface.

Thanks to this construction according to the invention, parts to be dried containing 60 to 100% of liquid relative to the dry matter can be dried in a period of between 1 and 5 minutes at a temperature below 50 ° C which perfectly respects the product quality. The production of such an apparatus according to the invention therefore satisfies real industrial use.

Thanks also to this construction according to the invention, the positioning and rotation of the support surface make it possible to present to the operator successively all the parts of the parts to be dried at a good distance in order to spread out said parts in the best conditions, and this whatever the dimensions of these parts, by adapting the length of the generator of the cylindrical support surface and its circumference to the dimensions of the largest parts to be dried.

For productions comprising smaller parts, the cylindrical support surface can be divided into several sectors, each covered by an independent membrane-cover, each sector thus constituting a separate drying unit, these drying units being presented successively at the operators, which makes it possible to produce a compact device, more economical and less bulky, while easily performing a perfect spreading of the parts to be dried in all their parts.

The details and advantages of some embodiments of the apparatus according to the invention will emerge from the description which follows, given by way of nonlimiting examples, with reference to the appended drawings, in which:

fig. 1 is a schematic transverse section of an example of an apparatus according to the invention, with a single drying sector for large parts;

fig. 2 is a schematic perspective view of the same example of apparatus according to the invention showing a part to be dried during spreading, before drying;

fig. 3 is a partial section along the plane of a generator of the cylindrical heated support surface of the same example of apparatus according to the invention;

fig. 4 is an alternative embodiment of FIG. 3 in which the seal is integral with the cylindrical heated surface instead of being integral with the membrane-cover;

fig. 5 is a schematic cross section of another example of an apparatus according to the invention, with several drying sectors;

fig. 6 is a perspective view of one of the drying sectors of the apparatus according to FIG. 5;

fig. 7 is a rear view showing a mode of driving the apparatus in rotation according to FIG. 5.

An exemplary embodiment of an apparatus according to the invention, shown in FIGS. 1 to 4, comprises a stationary base 1 to which are fixed, at each end, two frames 2 interconnected by spacers 3, the whole delimiting a volume in the form of a rectangular parallelepiped.

Towards the ends of the base 1 are arranged two pairs of rollers 4 and 5 freely rotating on their axes. On these four rollers rests a double-walled cylinder formed of an outer ferrule 6 metallic or plastic, not subject to corrosion or protected against corrosion, of a second ferrule 7, concentric inside the ferrule 6 and with the same characteristics. These two ferrules are connected by end flanges 8 in the form of a crown, the assembly forming a closed volume filled with a fluid maintained by all known means and i5 not shown at a constant temperature which can be adjusted and controlled by thermostat.

The inner surface of the shell 7 is covered with thermal insulation 7a.

A profiled frame 9, articulated at 10 on the upper crossbars 2o of the frames 2 supports a drum 11 which can rotate around its shaft 12 by means of a reversible two-speed gearmotor 13 connected to the drum by a transmission means 14.

A rectangular membrane 15 (fig. 1 and 2), waterproof, flexible but not extensible, preferably made of synthetic material, is fixed, by its edge 15 A, to the ferrule 6 along a generator AA 'and envelops said ferrule 6 up to to its generator BB 'in contact with the drum 11, from which the membrane 15 is wound on said drum 11 to which it is 3o fixed, by its opposite edge 15B, along a generator C — C. The length of this membrane 15 corresponds substantially to that of the circumference of the shell 6, while the width of the membrane is little less than the axial dimension of the shell 6.

The membrane 15 (fig. 1,2,3) is lined, on its face in contact with the ferrule 6, with a mattress of porous material 16, which is located inside the perimeter formed by a gasket. seal 17, which is tightly fixed around the periphery and near the edges of the membrane 15. On the outer face of the membrane 15 is fixed a flexible 4o insulating material 18 (fig. 3) to avoid heat loss.

It is thus seen that, when the simultaneous rotation of the ferrule 6 and the drum 11 have brought the edge 15B of the membrane 15 along the generator CC 'of the drum 11 in contact with a generator DD' of the ferrule 6 in the common position B -B ', the membrane 15 completely envelops the ferrule 6, and the seal 17 is applied, by its sides 17A and 17B, to the two generators AA' and DD 'of the ferrule 6 and, by the sides lateral 17C, on two arcs of circumference of the ferrule 6, thus delimiting, between the ferrule 6 and the waterproof membrane 15 a hermetically closed space intended to enclose a piece to be dried 19 previously spread out on the ferrule 6, as can be seen in fig. 3 which represents a section along the radial plane of a generator of the ferrule 6.

One or more tubes 20 (fig. 2), passing through the inner ferrule 55, 7 emerge through orifices such as 21 on the outer surface of the outer ferrule 6, inside the perimeter circumscribed by the gasket 17- The tube or tubes 20 are connected to a vacuum source 24 by means of a rotary joint (not shown).

60 Between the upper crosspieces of the frames 2, on the one hand, and the ends of the frame 9 supporting the drum 11, on the other hand, are placed two strong springs 25, respectively, for pressing the drum 11 towards the outer shell 6.

According to an alternative embodiment shown in FIG. 4, the 65 joint 17 is tightly fixed on the ferrule 6 instead of on the membrane 15.

At the start of an operational cycle, the membrane 15 is completely wound on the drum 11, leaving complete

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ment released all the outer surface of the shell 6, the generator A-A 'being merged with the generator B-B'. The operators begin by spreading one end of a piece to be dried 19 on the ferrule 6, as close as possible to the generator B-B '. From this moment, the geared motor 13 is started so that it begins to rotate the drum 11 counterclockwise (fig. 1), at slow speed. As a result of the action of the springs 25 on the ends of the frame 9, the drum 11 strongly presses the membrane 15 and its seal 17 against the ferrule 6 along the generator B-B ', which has the effect of driving in rotation cylinder 6 to 8 clockwise. During this rotation, the part to be dried 19 develops progressively on the ferrule 6, which allows operators to easily ensure perfect spreading of all the parts of the part to be dried 19 on said ferrule 6. In addition, the pressure exerted by the springs 25 and the tension of the membrane 15 on the ferrule 6 keep the part to be dried 19 strongly pressed on the ferrule 6, which prevents any retraction of said part to be dried while the spreading operation continues .

When the membrane 15 is completely unwound from the drum 11, the generator C — C 'having come into position B-B', the piece to be dried 19 is completely enclosed within the hermetic space delimited by the ferrule 6 , the membrane 15 and the seal 17.

The vacuum source 24 is then activated to create a vacuum in said hermetic space and extracts the liquid impregnating the part to be dried 19, which liquid is vaporized under vacuum as a result of the heat supplied by the fluid located in the 'space between the ferrules 6 and 7. When the desired degree of desiccation is reached, the vacuum is cut and the geared motor 13 is put in reverse, driving the drum 11 at high speed clockwise (fig . 1), which has the effect of winding the membrane 15 on said drum 11 and releasing the piece dries quickly.

When the membrane 15 is completely wound on the drum 11, the generator A-A 'of the shell 6 is again in position B-B' and the apparatus is ready for a new operation.

Another embodiment of an apparatus according to the invention, shown in FIGS. 5 to 7, comprises a stationary base 1 towards the ends of which are mounted two pairs of rollers 4 and 5 rotating freely on their axes. On these four rollers rests a double-walled cylinder formed by an outer ferrule 6 metallic or plastic, not subject to corrosion or protected against corrosion, a second ferrule 7 concentric inside the ferrule 6 and of the same characteristics. These two ferrules are connected by end flanges 8 in the form of a crown, the assembly forming a closed volume filled with a fluid maintained by any known means and not shown at a constant temperature which can be adjusted and controlled by thermostat. The inner surface of the shell 7 is covered with thermal insulation 7a.

At one end of the cylinder 6 to 8 (fig. 7) the ferrule 7 has a length slightly greater than that of the ferrule 6, this protrusion forming the rim 27 of a pulley for driving the cylinder in rotation on the rollers 4 and 5 by means of a toothed belt 28, itself driven by the toothed pulley 29 of a variable speed motor reducer 30.

In the present embodiment of an apparatus according to the invention, the outer surface of the shell 6 is divided into four equal sectors C-D, D-E, E-F and F-C, this number being neither limiting nor more nor less.

Each of the four sectors (FIGS. 5 and 6) is equipped with a cover comprising a frame 31 made of profiles or tubes or else a shell made of sheet metal or plastic, the profile of which corresponds to a quarter of the circumference of the ferrule 6 and can be opened and closed by means of the hinges 32, one of the arms of which is fixed to the shell 6 so that the hinge axis of the hinges 32 is parallel to a generator A — A 'of the shell 6 These hinges are fitted with a helical spring strong enough to always return the cover 5 to the open position when it is left free.

The frame 31 serves as a support for a rectangular, waterproof, flexible but non-stretchable membrane 15, preferably made of synthetic material, which is fixed, by one 15A of its edges, to the ferrule 6 along the generator A-A ', and , by its opposite edge 15B, on the uri side 31B of the frame 31. The two lateral edges 15C of the membrane 15 remain free and their length corresponds to the length of the arc of circumference of the ferrule 6 covered by the frame 31.

The membrane 15 is lined, on its face in contact with the shell 6, with a mattress of porous material 16, which is located inside the perimeter formed by a seal 17, which is fixed in a leaktight manner on the periphery and near the edges of the membrane 15. On the outer face of the membrane 15 is fixed a flexible insulating material (not shown) to 2o avoid heat loss.

We see that, when the frame 31 is brought into the closed position against the ferrule 6, the seal 17 is applied along its four sides to the ferrule 6 thus delimiting, between the ferrule 6 and the membrane 15, a hermetically closed space intended for hell -25 sea a room to dry 19 previously spread on the ferrule 6, as can be seen in fig. 3, which represents a section along the radial plane of a generator of the shell 6.

Several tubes 20 pass through the inner ferrule 7 open out through orifices 21 on the outer surface of the ferrule 6, inside the perimeter circumscribed by the seal 17. The tubes 20 are connected first to each other, then to a shut-off valve 22 and finally to a manifold 23 to which all the tubes coming from the other sectors of the apparatus are connected, the manifold 23 itself being connected to a vacuum source 24 by means of a rotary joint (not shown).

Two rollers 34 and 35 are mounted on each of the lateral sides 31 c of the frame 31, one 34 of these rollers being located in the middle, approximately, and the other 35 at the far end of the hinge 32 associated with the envisaged side . The rollers 34 and 35 40 rotate freely on their axes which are parallel to the generatrices of the ferrule 6. The ends of the ferrule 6 are partially surrounded by two fixed rims 36 (fig. 5) located radially outside the lateral sides 31C of the frame 31 so that the rollers 34 and 35 can roll inside the 45 rims 36. These rims 36 are of small width and each have the shape of a semicircle HI — J with a GH rectilinear and tangential elongation at one of these ends. By means not shown, the rims 36 are made integral with the base 1.

At the start of an operational cycle, the cover formed by the frame 11 and the membrane 13 of the first sector CD of the apparatus (fig. 5) is opened by the action of the springs of the hinges 32, as shown in dotted lines at fig. 5.

The operators start by spreading on the CD sector of the ferrule 6 one end of a part to be dried 19, as close as possible 55 to the generator A-A '. From this moment the gear motor 30 begins to rotate the cylinder 6 to 8 clockwise (fig. 5). Simultaneously, the two rollers 34 mounted on the lateral sides 31C of the frame 31 begin to roll inside the two fixed rims 36. fio During the rotation of the ferrule 6, the part to be dried 19 develops progressively on the outside surface of said ferrule 6, which allows operators to easily ensure perfect spreading of all the parts of the part to be dried 19 on the ferrule 6. At the same time the rollers 34 gradually close the cover by rolling on the straight portion GH fixed rims. When the rollers 34 have reached point H, the sector C-D has come to position F-C and the cover 15, 31 is completely closed. At this time, the shut-off valve

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22 relating to this sector opens, the vacuum is created under the membrane 15 and drying begins in this sector. The cover 15, 31 is then kept closed both by the action of the vacuum and by the action of the two rims 36.

Simultaneously, the sector which was initially in position D-E came into position C-D. The rollers 35 which held the corresponding lid 15, 31 closed are released from the rims 36 which terminate in J and the lid opens by itself by the action of the springs of the hinges 32. The operators then begin to spread another part to be dried on this second sector of the shell 6 and the cycle of operations described above is repeated on the second, third and fourth sectors until the first sector returns to its initial position CD, the automatic opening of its cover 15, 31 thus releasing the first dry part 19.

The speed of the gearmotor-variator 30 is adjusted so that the time necessary to obtain the desired desiccation corresponds to the rotation of 3/4 of a turn of the cylinder 6 to 8, that is to say that the vacuum valve 22 of the sector closes and cuts the vacuum s in this sector substantially when it returns to its initial position CD. The control of the vacuum valves 22 can advantageously be automated using known means. Continuous operation is thus obtained with the highest productivity because the operators have no intervention to perform for operation and therefore devote all their time to work on the parts to be dried.

The diameter and length of the ferrule 6 and the number of sectors can vary depending on the dimensions of the parts to be dried and the production to be carried out.

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3 sheets of drawings