BE628415A - - Google Patents

Description

       

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    "Spraying method and apparatus"
The present invention relates! an improved method and apparatus for spraying, in particular an improved method and apparatus for achieving grain or particle size reduction of high stretchable materials at room temperature.



   It has long been sought to create a method and apparatus for reducing the seed size of highly extensible materials such as polymers, in particular polymers.

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 thermoplastic polymers, ductile octals and the like * However, up to. At present, it was not possible to achieve this reduction in size at ordinary temperatures, for two main reasons:

   (1) the difficulty of giving the striking or impact element relative velocities high enough to ensure the breaking of the material to be treated and (2) the expenditure of large amounts of energy in the grinding process, which results in excessive heat generation to the point that the material to be treated is re-welded into unexpectedly large particles in the finished product or this material is deteriorated by heat.

   In the case of metallic materials, for which the heat is not sufficient to cause deterioration of the treated material, the significant deformation which accompanies the reduction in size of the particles resulted in work hardening which is often detrimental to end uses, for example in powder metallurgy and equivalent applications.



   It is true that the fact of having recourse to extensive refrigeration of the material to be ground, accompanied by additional cooling of the mill, in part makes it possible to facilitate the reduction of the grain size of the stretchable materials. * However , apart from the fact that they are prohibitively expensive, that they are characterized by low production flow rates and that they have other drawbacks, these measures remain ineffective for a large number of substances
A particular object of the present invention is to provide an improved process and apparatus for the spraying of highly extensible materials such as polymers. ductile metals and the like.

   A further object of the invention is to provide an improved spraying method and apparatus exhibiting the following advantages:

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 a very low amount of heat per unit weight of product processed; relatively high production rate; cost savings for the first establishment and maintenance; and producing a product exhibiting very good particle size uniformity.



   The description which will follow with regard to the appended drawing, given by way of non-limiting example, will make it clear how the invention can be achieved, the particularities which emerge both from the drawing and from the text being, of course, part of it. said invention.



   Fig. 1 is a graph showing the stretch rate (and percent elongation) versus tensile strength, based on the initial cross section for a nylon 6-6 polymer having a molecular weight of d. about 100,000, under the effect of shocks exerted in the air.



   Figure 2 is a vertical sectional view of a preferred embodiment of the spray apparatus according to the invention using a gaseous fluid as a carrier for the particles.



   Figure 3 is a plan view of the load directing rotor, (fan crown details removed) of a variant of the embodiment of Figure 2, this Figure 3 also showing the peripheral edge of the second rotor, cooperating with the first and which extends radially beyond the load direction rotor,
Figure 4 is a sectional view taken along the line 4 - 4 of Figure 3 *
FIG. 5 is a partial view, in section, taken along line 5-5 of FIG. 4.



   The fever 6 is a partial view, in section taken along the line 6 - 6 of FIG. 2, part of the rotor being supposed to be impact cut to better show the attachment of the / or striking elements.

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   Figure 7 is a partial schematic plan view showing five different forms of striking elements which may be used in practicing the invention.



   Figure 8 is a side elevational view of a preferred embodiment of the impactor used for the horizontal row of the apparatus of Figures 2 and 6.



   Figure 9 is a perspective view of a preferred embodiment of a striking element used as a vertical tooth in the apparatus of Figures 2 (and 6) of Figure 3 (and 4).



   Figure 10 is a side elevational view showing the aspect ratio of the hatch member of Figure 9.



   Figure 10a is a plan view. showing the aspect ratio of the impactor of Figure 9.



   Figures 11.12 and 13 are sectional detail views of various types of positive attachment mountings which may be employed for attachment of impactors to their rotors.



   Figure 14 is a perspective view of a preferred form of mounting for securing the horizontal impactors to the rotor in the apparatus of Figures 2 and 6,
Figure 15 is a vertical sectional view of a preferred embodiment of the spray apparatus according to the present invention for use with a liquid fluid as a carrier for the particles.



   Figure 16 is a sectional view. partially cut away, following line 16 - 16 of figure 15,
Figure 17 is a sectional view taken on line 17 - 17 of Figure 16.



   Figure 18 is a sectional view taken along line 18-18 of Figure 17,

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 Figure 19 is an elevational view of this' of a used
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 element of iopact / in the apparatus of figures 15 and 16 #
Figure 20 is a sectional view along the line 20 - 20 of Figure 19 *
Figure 21 is an elevational view taken from the outside of the dough retaining rotor of the apparatus of numbers 15 and 16.



   L. Figure 22 is a side elevational view taken * of the inner side of the back pressure reducing rotor of the apparatus of Figures 15 and 16.



   Figure 23 is a sectional view along line 23-23 of Figure 22.
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  Figure 24 is a vertical sectional view * of \ U1. another force of execution of the apparatus of pulvïrt3atlou eu1.ant the invention is intended to be used with a fluid 111. oosae carrier of the particles.
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 Figure 25 is a bottom view of a typing tool 414 of the apparatus of Figure 24.
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  Fig. 26 is a sectional view .loft at 21 26 - 26 of Fig. 25; Fig. 27 is a sectional view. 1 <* at 11,9 27 - 27 of Fig. 25.
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  Figure 29 is a sectional view along 1 * litm 28 28 of 14 Figure 25, Figure 29 * and a coup "ton view 14 1.1.



  29 - 29 of Fig. 250 Generally speaking, the present 1V8atl toiwtmb a method and an apparatus for the spraying - !. U.tm of nii% t.4Kr% 8 highly scalable, this method consisting of .ucaa1v. . mfrtl'V * suspended coarse particles of these uatt4nm 4 <Ma <<?? inert fluid to strike coarse particles **: a '\ J'f8lb 4 * impact cups which solicit materials ¯1 6m bzz

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 breaking the particles, faster than is possible for the stresses developed in the materials to dissipate by deformation of the molecular structure, and to remove the materials suspended in the inert fluid from the impact zone.



   The terms used in this description can be defined as night
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 coarse particles! * 1 d to particles which have a maximum diameter of about 12 <7 mi - 0 highly stretchable materials ": materials which exhibit an elongation of 30% or more before breaking all application of tensile stresses
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 * "inert fluid If any fluid, liquid or mangy, which does not enter into a significant chemical reaction with the material being sprayed and which, moreover, does not dissolve the material in an excessive proportion.
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  The physical studies which form the basis of the present invention have revealed that different materials react to the application of stress in characteristic ways which suggest a fundamental difference in structure. Thus, brittle materials fail when they are subjected to stress. 'they are stressed at the breaking point. this phenomenon appearing to us relatively moderate shocks or impacts which are sufficient to cause cracks. the latter then spreading easily with a low expenditure of energy, melon des plana de
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 lesser r0ti, at now that existing between the oounheo of Atoms in the atomic lattice of fragile materials.

   Cos planes exist in all dinumsiona of the aorta network that cracks and propagate simultaneously along the three axes, under the effect of energies which are only slightly higher than the necessary energies.
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 necessary to cause the rupture in the direction of the impacts This trtaxal rupture along regular planes produces fragments whose geometric shape is characteristic of the

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 breakage of fragile materials.



   There are also lower resistance planes in stretch materials. However. the cohesive forces which exist between the atomic layers are such that the layers slide in a way which decreases the applied stress instead of breaking as in the case of brittle materials. As the rate of application of the constraint grows;

   the relative resistance to plastic sliding also increases due to the effects of interatomic inertia, interatomic friction and interatomic viscoelasticity. Thus, at extremely high stress application rates, that is, at high impact velocities, the stress reaches maximum stress levels before appreciable slippage can occur. so that the stretchable material breaks by triaxial rupture using the same mechanism as in the case of a fragile material.



   The object of the present invention is to pulverize a material following a predominantly brittle fracture process. that is, grain size reduction occurs with an elongation less than 30% or less of the elongation at break of the material and at ambient temperatures above about -40 C.



   It has been found that high stretchable materials require work to break which is a function of the rate of elongation at which breakage takes place * The relationship between the absorbed work and the rate of elongation for a high stretchable material type is shown in Figure 1.



   The material chosen as an example for the breakage tests of FIG. 1 is a representative thermoplastic material, namely the polyamide referred to as Nylon 6-6, this designation designating a reaction product of hexame. thylene diamine (which has six carbon atoms) and acid

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   adipic (which also has six carbon atoms);

   in the case considered, said material has a molecular weight of approximately
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 IOOÈOOO The graph shows the failure of three samples having substantially identical physical properties, its differ- ent shear rates which vary respectively between a
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 Very high shear rate As of about 350 t / a and a relatively low shear rate Os of about 60 m / a passing through an upper limit shear rate Bo of about 160 m / m In all camps the point of rupture of the sample is indicated and it has been observed by very numerous test experiments that the rupture occurs along a curve D which connects the points of rupture of the different samples.

   The hatched areas above the three curves A,
B and C are a direct measure of the work required to shear the samples and this work amounted to approximately 1670 calories / kg at speed A, 3.340 calories / kg at speed A.
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 speed B and 6,600 calories / kg at speed Ce The temperature rise as a result of the dissipation of 6.b $ 4 calories / kg (ie for speed 0) corresponds under the usual circumstances. 1 ie at the heat transfer rate and at about 0 ° C, which is much too high for Nylon 6-6 because the polymer softens and. at the same time it undergoes degradation by heat at this temperature.

   On the other hand, the shear rate B corresponds approximately to a temperature rise of only in-
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 about 75 ° Cf which can be tolerated at a product flow rate of about 161 to 453 kg / hr for the gas phase embodiment described herein) which is a cost effective flow rate.



   With certain types of materials, it may be advantageous
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 to carry out the size reduction at even higher oil speeds and approaching the practical limit; constituted by the speed A and, in general, the spraying: tteo.

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 killed at any point of the licit zone by the equivalent curves of A and B is entirely satisfactory from the point of
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 view of heat release as a function of ciaail speed. of course.

   Naturally, it goes without saying that the necessary work
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 for breaking down particular polymers varies slightly with different polymers and. also, that the permissible rise in temperature in each case depends on the nature of the material being sprayed. However, in general we can say that the reduction in dimension operated at impact speeds
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 in the range of from about 10 m / s to 760 n / s is satisfactory for most thermo-oplitic materials such as, for example, polyesters, polyamides and polyesters. unsaturated polymers * In addition,

    certain metallic materials which may be either pure metals or alloys and which present
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 High ductilities included in the xono which starts from about 30% elongation before fracture and more have also shown fracture characteristics which place them in the fault of the highly extensible materials to which this presents
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 The invention thus applies. The object of the invention is thus the spraying of highly extensible materials at shear rates which ensure the rupture of the particles A at elongations less than) 0 of the maximum intrinsic alloy of the elongation material which, in the case of i,

  y.on 6-6 corresponds to an elongation of about 150%, the maximum elongation being about 500 l or corresponding to an d'tir8 {'o level of about 2.5.



  It goes without saying that the impact speeds at which we
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 referred to above are the actual relative velocities of impact or strike to the material being processed and not the absolute velocities of the imput elements.



  These Braids, are therefore, in the case where one uses as a fluid, 7..daa, of the order of Kaeh 0.1 more than lach 1.0 (or dea 4 v, ets higher when s 'acts of gases) and these speeds

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 are obtained only by the future and the special arrangement of the striking elements, the staves and the other parts of the machine.



  Careful selection of the materials of construction of the spray apparatus is also necessary since operation is carried out in a range of speeds which imposes stresses close to the strength limits. However, an equally important consideration,

   consists in the fact that the impact feeders must have an aerodynamic shape capable of reducing to a minimum the shock waves which would reduce the relative displacement between striking elements and particles and at the same time able to reduce the caloric doors by friction under the pressure. 'effect of contact with the inert fluid forming the support or vehicle of the materials *
A preferred embodiment of the apparatus for spraying highly expandable materials suspended in air, taken as the inert fluid, is shown in Figures 2-14.

   This apparatus comprises two elements which rotate in the opposite direction so as to obtain the very high impact speeds used according to the invention, the upper element being the load directing rotor, designated as a whole by 10 while the element lower is the rotor 11 which carries the striking elements.



   The rotor 10 is rigidly connected by its hub 12 to the lower end of a drive shaft 15 mounted in support bearings 16, 16 'and driven by a motor, not shown, keyed at its upper end. Likewise, rotor 11 is rigidly fixed to a drive shaft 18, carried by support bearings 19, $ 19 'and driven by a second motor, not shown, keyed at its lower end.

   The rotors are mounted inside a housing in three parts, an upper part 22, a middle part 23 and a bottom 24, which are joined together by flanges incorporated in these parts and placed.

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 face to face and by machine screws 25. your part 22 is internally united by a separation skirt 26 held in position by machine screws 27. The supply inlet connector 28 opens near the internal periphery of the skirt 26 while the cooling air arrives through the inlet connection 29 which opens to the outside of the separation skirt.



   The middle part 23 constitutes the external wall of a cooling jacket or jacket 32, the internal wall of this jacket being a solid metal crown 33. formed from a wear-resistant alloy (for example, 5% Cr. .



  2.5% C, 0.5% Si, appreciable amounts of V or Mo, the remainder Fe) or which, alternatively, may be of high-strength alloy steel sheathed, on all its internal surfaces which are opposite the rotors 10 and 11 by a coating of stolite or other extremely hard protective material. Inside the jacket 32 is mounted a directing spiral of the coolant flow, 34, which can be made of metal and joined to both parts 23 and 33 to form an integral unit. The inlet and outlet ports 35 and 36 respectively, of the cooling water communicating with the jacket 32.

   Finally, there is provided an annular solid metal ring, 35, tightening to restrict the flow of air, and which extends radially inwardly from the upper surface of the ring 33 and which is welded at its periphery to this upper surface
The lower part or bottom 24 is shaped so as to constitute a passage 40 for evacuating the product carrier; this passage, in the form of a volute, is internally sheathed with a wear-resistant metallic coating 41 and part 24 also has an opening leading to an orifice 42 for discharging the product.

   This part 24 supports, by screws 44 which cooperate with the internal flange 45, a base plate @@ -

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 nular 46 which is machined to conform to the shape of the lower surface of rotor 22 at a short distance from this surface and opposes the delivery of substantial quantities of product carried with the stream of inert gas forming the vehicle.

   A central closing part 47, attached to the lower part @ 4, closes the spray chamber and this part is provided with a gas inlet port 48, through which gas under pressure is introduced to clean the gap. between the rotor 11 and the base plate 46 and rid this space of particles which, by accumulating therein, could hinder the rotation,
Although Figure 2 gives only one embodiment of the apparatus with respect to which Figures 3, 4 and 5 constitute a variant, the construction of all the directing rotors of the load 10 is identical. and we will therefore describe it with regard to all these figures taken together.

   The steering rotor 10 consists of a solid plate 51, flared down to about 10% of the diameter of the rotor from its periphery in a direction oriented radially outward from the center of the rotor. shaft 15. at an angle of about 15 and is provided with a large number of blades 53 directed upwards (sixteen in the present example).

   The blades 53 are rigidly fixed, along their base surface, to the plate 51 and they are further fixed at their outer ends. to the fan crown 54 which is provided on its upper face with a large number of fan blades 55 of short length (not shown in Figures 3 and 4) which are adapted to attract the cooling air through the orifice 29, if it is advantageous to provide additional cooling or air sweeping of the product for the discharge of the spray chamber.



   To improve their mechanical resistance, the fan blades 55 can be braced, by a crown.

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 upper annular 56 # aouds to these pal s the crown 56 being adjacent to the crown 39 with a very low bracing so that the principle of air inlet ofettoctue through the annular orifice 57.



   As shown in figure 5, it is preferable
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 to equip the pointa of the blades 53 with striking elements' 6. r4a ,. lie4b in attllitt or equivalent material and presenting a tranIVel'I {41t $ aeotion which orott towards the outside of the rotor 101 these impact Alimenta being contracted by soldering or brazing, in cavities of oorraspondantos shape machined in the outer ends of the blades.
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 The hub 12 of the rotor 10 * and provided, 6 its upper part, with a charge distributor 61, fixed to this means by means of
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 machine screw 62t oe distributor being usually provided with qra blades 63 4quidittan'- "and offset from each other by 90 *.



  As for the construction of the rotor 11 employed in the apparatus of Figures 2 and 6, a preferred device comprises two rows of impactors, both mounted on the lower rotor which cooperates with the rotor 10. The first row consists of teeth. 66 upright and which are
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 evenly distributed over the periphery of the rotor II # at intervals of about 6%, the clearance between the trailing edge and the leading edge being usually equal to 03 times the width of a tooth. The teeth 66 protrude perpendicularly to the radii of the rotors 10 ot 11, over the entire height of several passes of the load, defined by the blades 53 at a distance
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 radial of the periphery of the pluquo $ 1 equal to about 6 35 mm.



  The second row of impactors is made of teeth 67, located on the same general radial lines of rotor 11 as teeth 66 but oriented perpendicular to the latter in a general horizontal direction. Teeth 67 can
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 have the same height as the teeth 66 months they have a different design, as described in detail below and they

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 fit tightly (with approximately 6.35mm clearance)

   compared to 4 the adjacent face of the crown 33 The internal face of the crown 33 is preferably machined to present an upper curvilinear 68 in front of the teeth 66 so as to redirect the solid particles which pass through. through the first row of striking elements in a line substantially perpendicular to the path of which 67 and the terminal edge. lower 69 of the surface 68 is disposed radially inside the rotor Il @ on slightly overlapping

  ends have teeth 67 so as to prevent the material from passing in derivation and relative to the second row of striking elements and not avoiding this row, The lower edge of the crown 33 is hollowed out at 70 (see this' of figure 2) to form an anvil against which the particles are projected by the teeth 67.



   The arrangement of the striking elements in the construction of figures 3-5 differs from the arrangement of figures 2 to 6 only in that a row of additional teeth, designated by the reference numeral 74, is shown on the underside of the crown 54 of the fan, which is an integral part of the rotor 10 ', these teeth being directed from top to bottom, this row being inserted with the two rows of teeth 75 facing upwards, of identical design and which are carried by the rotor 11 '.

   It is preferable to hollow out the upper part of the rotor 11 'at its periphery to form a concave groove 76 at a short distance and opposite the teeth 74 to enhance the spraying action. In this embodiment, the horizontal teeth such as the teeth designated 67 in Figures 2 and 6 are omitted and all the teeth employed can be of the same size as those designated 66.



     Obviously, it is possible to plan more than one game

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   impactors overlap each other, mounting several rows of teeth 74 directed up and down on the upper rotor 10, to cooperate with adjacent rows of teeth 75 on the lower rotor.

   However, the research carried out by the Applicant has shown that it is seldom advantageous to use more than four rows of impactors. It is also possible to provide a row of horizontal teeth such as teeth 67 in the figures. 2 and 6, on the periphery of the lower rotor, these rows comprising teeth which are inserted between them but, usually, this additional expenditure remains without counterpart.



   It is possible to provide a wide variety of shapes for the striking teeth in an apparatus constructed according to the invention. However, these teeth must be carefully profiled in order to present, in relation to the fluids contained in the spraying zone, a minimum aerodynamic resistance in order to conserve the driving power, to eliminate the heat of friction, and to obtain a real contact speed which approaches the speed of the rotor, by eliminating the shock waves which would result from a flow along non-deep surfaces and, which is of great importance, to resist shock stresses:

  , important to which they undergo in the collisions with the particles at the high extreme velocities which are developed. In general, profiling should be efficient enough that the power input is less than about Ot2g CV / cm of blade face width for movement in particulate free air and at a speed of 305 m / s. or less than about 0.6 CV / cm for moving through water at a speed of 75 M / s.



   When moving in the direction of the arrow, the elements relatively thin and having a transverse cross-section which varies between the general rectangular shape and the rectangular shape.

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 diamond-tipped, as shown in Figure 7, exhibiting aerodynamic characteristics which make them at least partially effective for the application of the invention.

   Among the shapes shown, it is preferable to use the variant shown in 7d for teeth 66 of flower 2 as well as for teeth 74 and 75 of figures 3 and 4, while it is preferable to use blades of rectangular cross section with an elevation profile such as that shown in figure 8, for teeth 67 (figure 6),
In general, it has been found that the aspect ratio L / T (i.e. the length divided by the thickness) should be greater than about 6: 1 to avoid having high losses per. frontal friction.

   It is necessary to impose an upper limit of about 15: 1 in order to safely avoid the rupture of the flow lines on the trailing edges of the impactors and also to avoid the local overheating associated with this rupture. The preferred aspect ratio is about 12: 1.



   It is essential that the angle of incidence (that is, the inclination of the front edge of the impactor relative to the instantaneous direction of speed) is less than about 15 ( preferably zero) to avoid an excessive pumping effect and accompanying friction losses.

   The angle of incidence, in geometric terms, is formed by the angle between a plane which passes through the leading edge and the trailing edge of the impactor and a plane tangent to the radius from the rotors to the center of the impactor,
In addition, the impactors must have the correct geometrical shape to withstand the large impact forces which are inherent in the spraying process, this due to the fact that it develops in the materials being processed. of maximum tension and that these

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 are close to the maximum tensile strength of any construction material that can be used. So,

   a geometry which multiplies the stresses in the region of the attachment of the impactor to the driving member must be avoided. The following general limits apply: (1) the h / L ratio (i.e. height divided by length) must be
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 less than about 2 and, preferably, equal to about 0 8 d (2) the projection overhead of the tooth crest on the sur-
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 base face must be c: 8oe less than about 2 and pre- ± 6ronce equal to about 0 8. Cos two ratios can be increased if a special geometry is provided for the top and bottom edge provided that the overall drawing of the a6ro profile ... l :. nurl. <ui is not destroyed.



   Applying these principles a preferred design of impactors for teeth 66, 74 and 75 is obtained, such as that shown in perspective in Figure 9 and, in which
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 relates to dimensional ratios # on flowers 10 and 10a @ the direction of drive during spraying is indicated by the arrows drawn at cati of each of these views. It can be seen that this tooth has, in cross section, the fane form
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 rale of a half-point of diamond which is tapered pro-actively to have a section reduced to the crest, the flat side of the tooth being oriented in the direction of the entry of the material, comas shown in figures 3 and 6 one particular.

   What is the value of
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 compromise necessary to obtain the highest mechanical resistance, we have chosen a ratio L / TA the base étal at the maximum limit of 6 t 1, co ratio gradually decreasing to reach the ideal value do 12: you The er8te, All striking lights must be constructed of metals or alloys capable of working at n.oin3 at 56 k- / m, 2 cL, preferably at around 105 ka / = 2 and the manufacturing technique employed must t be specific to aasurar a homogeneous distribution in

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 mechanical properties in the entire volume of the elements.



   The striking elements are preferably made in one piece with back bases, 77 and 78, as shown in Figures 8 and 9 respectively and these bases can be machined in a wide variety of cross sections to be adapted to form. a positive connection with correspondingly shaped grooves which are provided in the rotors which support these teeth.

   Thus as shown in Figure 11, the bases may have a trapezoidal cross section 81 or an inverted trapezoidal section comprising an internal extension as shown at 82 in Figure 12. Assembly is facilitated by providing in the rotors, a region hollow -of length slightly greater than a base length * so that the teeth can be engaged one after the other in this recess and slide them lo along the fixing groove until that the row is fully lined, after which the inlet passage is closed by welding or other process.



   Another type of attachment is shown in Figure 13. The base has a steeply sloping edge on surface 83 which is directed toward the center of rotor 11 and an opposing face 84 which is nearly vertical. This construction is designed to allow the teeth to be welded to the rotor along the surface 83 and the groove 85 which receives the elements is open to the dimension shown around its entire circumference so that all can be placed. the elements in place by simply sliding them into the groove at any point on the periphery of the rotor.



   It seems preferable to use a different type of attachment for the horizontal impactors 67, this type consisting of a locking piece 88 shown in Fig. 14 and to which tooth 67 is attached by welding or fabrication.

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 in one piece. This locking part fits into a horizontal groove machined over the entire periphery of the rotor 11, the fixing being provided by two machine screws passing through holes 89 drilled in the part 88.



   The following tests were carried out on a spray apparatus constructed according to Figures 2 and 6 but in which the horizontal teeth 67 were omitted, the rotor 11 having a diameter of 686 mm and being provided with 59 impactors spaced at a spacing. pitch of about 35.6 mm. The height, from the base to the point, of the striking elements 66 is 25.4 mm, the thickness ranging from 3.18 mm at the base and 1.98 mm at the crest and the length being 25.4 mm,
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 The load is driven by a coural ('at a flow rate of 0 # 25 kg of material ool.dos / kg duir / min and?:, ..' supplied to the apparatus at solids flow rates of Ç'07 ',,' 1 ,. z * In all cases, the speed of rotor 10 is 3,500 rpm, tandi7 z, glue of rotor 11 is 6,000 rpm.

   This corresponds to a shear speed of 335 m / s, this speed being well in the region of FIG. 1 which is limited by the Jazz curve. The p \ lt! '.' \ C6 eonsommâQ per kg of product is about 0, CV for you to try them $ In Figures 15 to 23 is shown an embodiment of the apparatus for spray the IlUtt. iru'o aors a liquid fluid.



  This variant comprises a drive shaft -inique 93, which rotates in bearings 95 and 96 portas by 1 ('; \ 15 ..,.:,;,. Designated as a whole by the reference 97. The; -. 1. 'lt .., of the strike are fixed by a key 94; mr 1 tE: xtrmi tJ in,' 'i: ur' of the shaft 93 and they include three structures 98 provided <# -, mes of identical dimensions (the outside diameter being a typical construction of 203.2 mm) a r01 ,,.;: "-> laughing 99 is provided (the outside light of this rotor being 152.4 c, x ,; ,:,

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 a typical construction) to reduce the back pressure on the shaft seal which will be described below.

   A suspension retainer rotor, 103, is mounted on the outside of the impactors and the assembly is held firmly in place by a nut 104 which is screwed onto the threaded end of the shaft 93. strike and the rotors are separated from each other by washers 100 of approximately 3.18 mm thick which ensure an equal axial spacing apart from these elements.



   The spray chamber is formed by a housing, generally designated by 105 and which is formed of two parts assembled by bolted flanges to allow the mounting of the impactors. The chamber is provided with a lower seal 106 which opposes leakage along the shaft 93 and, in contrast to this seal, it is provided with an inlet tubing 107 serving to introduce load in the device in the direction of the axis of the drive shaft.

   A sub-assembly formed of a wear plate 111 and a screen 112 surrounds the spray head over its entire periphery, any part of the charge possibly escaping from the spray zone being vented through a lower manifold. 115 which opens into a free annular space 116 situated, in the radial direction, outside the plate 111 and the screen 112. The output of the sprayed product takes place through the outlet pipe 108.



   The detailed structure of the impactors 98 are shown in Figures 19 and 20, these elements being constituted by unit rotors comprising two opposing arms in diameter. which are circularly curved along their ridge line and which are provided on both sides with aerodynamically profiled cutting edges, having a cutting angle of about 30 ', as shown in figure 20. The leading edges of the rotor are those which are designated by the numeral 117 on the edges 19 and these edges are inclined. from an angle a (45 being a

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 typical angle) in the direction of rotation, measured from the midpoint of the radius contained in the diameter D.

   Likewise, the position angle b of the tapered trailing edges 18 with respect to the same diameter d is that which is measured in the reverse direction and, in
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 a typical construction it may be about 1: 5. The length of the edges 117 is, in a typical construction, 12.7 ma while
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 that the length of the edges 118 may be 25r t mm.

   To ensure fixing, two keyways are provided in each rotor.
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 vette 9t, e and 94f, which are offset from each other by 90 *
As shown in Figure 21, the rotor for retaining the suspension is a circular rotor provided, on its outer face with two sets each comprising four lamas 121 and 122 of cross section.
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 rectangular transverse (the slats 121 having by tx nple 6 "Smsn of width and 63.6 mm of length and the slats 122 having for example
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 ple, 6.35 mm wide and 2594 rom long) these lance being arranged at regular angular intervals around the circumference and projecting radially on the periphery by 9.52 mm in a typical construction. There are 94g and 94h keyways to fix this rotor on the abre 93.



   The internal rotor 99 is a disc of generally planar shape provided with several (eight in this case) radial grooves 123. distributed at equal angular intervals, which open out at the tip.
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 riphérie of the disc and whose length (50.8 stsu being a typical rent) is approximately equal to three-quarters of the radius of the disc. The
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 the depth of the grooves 123 can be 3 # 18 ma, and their width about 6.35 mm. These grooves, when facing away from the direction of the load in the device, have the effect of
 EMI21.8
 effect of relieving the sealing ring 106 of the excess pressures a- si vas by centrifugal discharge of the material towards the: and8 of this region. The rotor 99 is fixed on the shaft 93 rr at c'a- vettea and via keyways & vettes ytt and? <#;,.



  As shown in Figures 16 to 18 inclusive, the

 <Desc / Clms Page number 22>

 wear plate 111 and sizing screen 112 may be of cylindrical construction, the screen being mounted radially on the outside of the plate and these two elements being generally coaxial with the shaft 93, with a clearance of approximately 3.18 mm from the impactors 98.

   The two walls of the casing 105 are provided with shoulders 126, machined around the periphery of these walls and against which can be applied a cage 127 which serves as a support for the wear plate-screen sub-assembly. This cage is held in place by rings 128 and 129 which are pressed firmly against the internal walls of the housing by a certain number of bolts 130 arranged around the circumference at regular intervals. An additional bracing is provided by a split crown 132 ( figure 16) which is provided with a number of solid plates 133 arranged radially, which form an integral part of this ring but which apply to the sieve 112 at frequent intervals around the circumference of the cage,

   at points opposite to the solid struts defining the openings of the wear plate 111, as shown in figure 18. The edges of the plates 133 are adapted to fit for sliding in the radial grooves 134 cut. in the cage 127 and in the rings 128 and 129 to avoid any defect in angular centering with respect to the wear plate 111. By tightening the tensioning bolt 135, the circumference of the crown 132 is reduced and the plates are applied 133 tightly against screen 112 and wear plate 111. Screen 112 may be, in a typical construction, 0.37 mm mesh size and the wear plate may be machined to have rectangular openings measuring approximately 25.4 mm. x 25.4 mm.



   An alternative embodiment of the apparatus, working in the liquid phase and not comprising a retaining screen or plates is shown in Figures 24 to 29 *
The drive shaft 139, is, in this case * arranged

 <Desc / Clms Page number 23>

 and journalled vertically in bearings 140 and 141 which are carried by the frame, the latter being designated as a whole by 142.

   The shaft is sealed by a stuffing box 143 and the outer end of the shaft is enclosed in a cylindrical housing, generally designated 144, which is internally sheathed with a wear-resistant liner 145 and it is provided with a plurality of dividers 146 which are superimposed and fixed annulus rings which extend radially inward for a distance equal to about one third of the gauge of the crankcase. These dividers define a succession of eight spray compartments 147 inside each of which one of the striking elements 148 is arranged in a central position.



  A charge inlet pipe 149 opens into the lower compartment 147 and a prose outlet pipe, 150, extends from the top of the housing 144.



   Each of the impactors 148 is secured, for example, by an interference fit on the shaft 139 and sleeves 154 are provided which separate each impactor from its neighbors; the assembly being held in place on the shaft by a locking nut 156.



   The striking elements 148 are preferably of the form shown in Figures 25 - 29. In this case, they are formed by thin structures (of about 1.6 mm in a typical case) with twelve teeth and in which the teeth are inclined out of the plane of the rotor, alternately to the right and to the left, as shown in figure 26, and by an angle e of about 15.

   The leading edges 157, rectilinear, are sharpened by forming a bevel over their entire width * and over a length of approximately 50.8 mm with a cutting angle of @ approximately 30, as shown in the figures. 28 and 29 and the lower side of each element is provided with four cut-out strips 158 and arranged at equal intervals and which are in @@

 <Desc / Clms Page number 24>

 born about 30 relative to the direction of rotation to ensure. a pumping effect inside each of the compartments 147.



   The operation of the materialization of Figures 24-29 is analogous to that described above for the apparatus of Figures 15 to 23, the operating speed being, in a typical construction, 2,700 rpm for striking elements. 148 having an overall diameter of 508 mm.

   However, the tabs 158 help to provide a rooidal pumping effect which preferentially advances the small dimension particles from the bottom upwards to pass them from the lower compartment 147 to the upper compartment, the spraying of the particles at high temperatures. finer dimensions occurring successively in each of the eight compartments 147, each time material has passed through one of these compartments and a new compartment presents itself to it in its flow & through the apparatus. This alternative construction has the advantage of making it easy to obtain additional cooling by providing the casing 144 with an external cooling jacket.



   It should be noted that the same critical proportions)) which are applicable for the teeth 66, in the example of a materialization by gas phase, are also applicable to the striking elements 98 and 148 of the apparatus working in the liquid phase. . However, a certain simplification can be made for the latter apparatus since the striking edges lie in radial planes of the drive shaft, so that there is no centrifugal bending moment and the elements may be flat and may be an integral extension of the rotor.

 <Desc / Clms Page number 25>

 
 EMI25.1
 EXHALE 1, The material sprayed was Nylon 6 6 # o 't' - & '' say a polymer obtained from the condensation of h.xamethyltne.

     diamine and adipic acid (molecular weight approximately 100,000), it was introduced into the device in the form of: granules
 EMI25.2
 having an average diameter of 6.35 mm, 0% passing through a 0.633 mm mesh sieve. The gradual reduction in dimension inoicated below has been observed s
Particle size analyzes of the products expressed in% by weight passing through sieves of a given mesh width.
 EMI25.3
 



  Mesh width of the sieves! 0.833 0.37 0.246 j /, 75 0.147 mm mm mm * ITJI1 rt ........... IJJ1II1M '.i ... I! IIMf1t..Ll a) first pass through the apparatus starting temperature!
 EMI25.4
 3? r "G; temperature at the end: rr9iC; flow rate of solids 22.68 kg. 26.6 6o2 2.1 z, 1, 2.1 b) second pass through the device starting temperature:
 EMI25.5
 37 C; end temperature t 46.1 C flow rate of solids: 20.41 kg. 59 # 3 29.2 9.2? 'R 505 c) third passage through the appliance: flow temperature
 EMI25.6
 37t8oC temperature at the end: k3 u C; flow rate of solids: 16.14 kg. zur * 1. 4091 14eg 7.4 3t7 d) fourth passage through the flow temperature device
 EMI25.7
 3? N G; temperature at the end 43.3 * 0; flow of solid materials 15.87 k 79.6 46.3 14 7.4 3? EXAMPLE 2.
 EMI25.8
 



  The material sprayed was Nylon 6, i.e. a polymer by addition of caprolact. ') 8 which prepared bzz

 <Desc / Clms Page number 26>

 
 EMI26.1
 opening the nucleus of oaprolactamo and coupling it to a long chatno structure (molecular weight about 73 * 000). This material was translated in the apparatus in the form of granu-
 EMI26.2
 them having an average diameter of about 9 # 52 mm of which 0% passed through a sieve & mesh of 0.833. The following progress was observed in the reduction in size of the granules: Particle size analyzes of the product, expressed as% by weight passing through sieves of a given mesh width.
 EMI26.3
 



  Mesh width of the sieves: 0o833 0.37 0.246 0.175 0.147 mm mm mm mm mm a) first pass through the apparatus: de-
 EMI26.4
 part 1 37t8 ° C; end temperature 9 48 <9 * 0 solids flow! 1 22.68 kg 48 # 8 11.6 - * # b) second passage through the appliance leaving temperature:
 EMI26.5
 37.8 * 0; end temperature t 46.1C; material flow .0- lidos 20.41 kg. 66 # o 26.0 10.0 6.0 4 * 0 0) third pass in the appliance: flow temperature t
 EMI26.6
 37 8 * C; temperature at the end k3v3 "C; flow rate of solids: 18.14 kg. 74.1 3 eye 14.9 7 # 4 3.7 d) fourth passage through the apparatus: starting temperature
 EMI26.7
 37.8 * 0; temperature at the end f r3'C; solids flow:

   1 ', 87 kg. 80.0 44.0 16.0 8.0 4.0 EXAMPLE 3.
 EMI26.8
 



  The pulverized material was a polyacetal resin which was a condensation polymer of enol (dihydroxy form of trsnaldehyde (molecular weight about 45,000); this material was introduced into the apparatus in the form of granules having

 <Desc / Clms Page number 27>

 
 EMI27.1
 average diameter of about l76mm, 0gb passing through a 00933mm mesh sieve. The following progression was observed in the reduction of the particle diameter
Particle size analyzes of the product, expressed in% by weight passing through sieves of a given mesh width.



  Screen mesh width: 0.033 0.37 0.246 0.175 0.147
 EMI27.2
 mm mm mm mm min a) first pass through the appliance: flow temperature:
 EMI27.3
 7, $ 'C; temperature at the end! 48.9 * 0; solid material flow rate 22 # 68 kg. 43.2 19i7 ir? 7 Ô 3 # 9 b) second passage through the appliance: flow temperature
 EMI27.4
 37 r 'C; temperature at the end tr6, ï.

   VS ; flow rate of solids 20.41 kg. 59.3 26.0 11.1?, Tu 3.7 c) third passage through the appliance: flow temperature
 EMI27.5
 37i8 * C j temperature at the end i 43.3 * 0; flow rate of solids le, 14 kg. ? 2ruz 37. ' 19.7 11.6 7.9 d) fourth pass through the device
 EMI27.6
 rei7. starting temperature 3'i $ C; temperature at the end: 3, C; solids flow rate: 15 # rl kg. 77. 44.5 22.3 l4p9 11.2
EXAMPLE 4.



   The material sprayed was a saturated polyester resin, consisting of the reaction product of ethylene.
 EMI27.7
 glycol and terephthalic acid (molecular weight approximately 60,000} this material is introduced into the apparatus in a prior state
 EMI27.8
 ground and whose particle size analysis is indicated on ..1 '\ line "initial state". The following progression was observed; * of the reduction in size of the granules:

 <Desc / Clms Page number 28>

 
Particle size analyzes of the product, expressed as% by weight passing through sieves of a given mile width.



  Mesh width of the sieves 0.833 0.37 0.246 0.175 0.147 mm mm mm mm mm Analysis of the starting material 76.0 36.0 12.0 4.0 4.0 a) first pass through the apparatus: temperature starting
37.8 C; temperature at the end:
48.9 C: flow rate of solids: 22.68 kg. 84.0 48.0 16.0 8.0 4.0 b) second pass through the appliance: leaving temperature:
37.8 C; temperature at the end, 46.1 * 0; flow rate of solids: 20.41 kg. 88.0 56.0 24.0 16.0 8.0 c) third passage through the appliance: flow temperature
73.8 C; temperature at the end:
43.3 C; flow rate of solids:

   18.14 kg. 92.2 68.7 31.4 19.6 11.8 d) fourth pass through the appas. reil: starting temperature:
37.8 C; temperature at the end:
43.3 C; flow rate of solids s 15.87 kg. 90.0 64.0 30.0 20.0 12.0
Further tests were carried out on the apparatus described above in order to obtain comparative performance in the spraying of polymers, elastomers and metals, these results being summarized in the following table:

 <Desc / Clms Page number 29>

 
 EMI29.1
 
<tb> Materials <SEP>: <SEP> Polymer <SEP>: <SEP> Elastomer <SEP>: <SEP> Metal
<tb>
<tb>
<tb>
<tb>: <SEP> Polyamide <SEP> polyester <SEP>: <SEP> polymer <SEP> from ad- <SEP>:

   <SEP> ductile
<tb>
<tb>
<tb>
<tb> Nylon <SEP> 6-6 <SEP> product <SEP> sa- <SEP> edition <SEP> of <SEP> the <SEP> foam <SEP> of
<tb>
<tb>
<tb>
<tb> weight <SEP> mo- <SEP> tured <SEP> of <SEP> the <SEP> ethylene <SEP> titanium <SEP> pu-
<tb>
<tb>
<tb>
<tb> lecular <SEP> reaction <SEP> of <SEP> (weight <SEP> moléou- <SEP> re, <SEP> Hardness
<tb>
<tb>
<tb>
<tb> 100,000 <SEP> ethylene <SEP> will yield <SEP> approximately <SEP> Brinnell,
<tb>
<tb>
<tb>
<tb> glycol <SEP> on <SEP> 50.000)

   <SEP> which <SEP> has <SEP> around <SEP> 80
<tb>
<tb>
<tb>
<tb> the acid <SEP> t- <SEP> summer <SEP> chloro-
<tb>
<tb>
<tb>
<tb> rephthalic <SEP> sulfonated <SEP> by <SEP> the
<tb>
<tb>
<tb>
<tb> weight <SEP> mole- <SEP> continued
<tb>
<tb>
<tb> cular
<tb>
<tb>
<tb> 60,000
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Dimension
<tb>
<tb>
<tb>
<tb> of the <SEP> grains
<tb>
 
 EMI29.2
 from the load 6.35 mm 3, the mm 6.3;

   mm i2 ,? mu
 EMI29.3
 
<tb> Resistance <SEP> to
<tb>
<tb>
<tb> the <SEP> traction
<tb>
<tb>
<tb>
<tb> (kg / cm2) <SEP> 703 <SEP> 560 <SEP> 210 <SEP> 3.500
<tb>
<tb>
<tb>
<tb>
<tb> Fluid <SEP> support
<tb>
<tb>
<tb>
<tb> (vehicle) <SEP> air <SEP> air <SEP> air <SEP> argon
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> RPM <SEP> from
<tb>
<tb>
<tb>
<tb> rotor <SEP> 10 <SEP> 3.400 <SEP> 3.400 <SEP> 3.400 <SEP> 3.400
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> RPM <SEP> from
<tb>
<tb>
<tb>
<tb> rotor <SEP> 11 <SEP> 6.000 <SEP> 6.000 <SEP> 6.

   <SEP> 000 <SEP> 6.000
<tb>
<tb>
<tb>
<tb>
<tb> Speed <SEP> of
<tb>
<tb>
<tb>
<tb> shears-
<tb>
<tb>
<tb>
<tb> ment <SEP> m / s <SEP> 335 <SEP> 335 <SEP> 335 <SEP> 335
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Power
<tb>
<tb>
<tb>
<tb> consumed
<tb>
<tb>
<tb>
<tb> CV / kg <SEP> 0, <SEP> 22 <SEP> 0, <SEP> 22 <SEP> 0.44 <SEP> 0.22
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Number <SEP> of
<tb>
<tb>
<tb>
<tb> passages
<tb>
<tb>
<tb>
<tb> in <SEP> the ap- <SEP> circuit
<tb>
<tb>
<tb>
<tb> same <SEP> 4 <SEP> 4 <SEP> 1 <SEP> Hold <SEP> (+)
<tb>
<tb>
<tb>
<tb>
<tb>
<tb> Analysis <SEP> gra-
<tb>
 
 EMI29.4
 nullometric
 EMI29.5
 
<tb> (openings
<tb>
<tb> of <SEP> meshes
<tb>
<tb> in <SEP> mm)
<tb>
 
 EMI29.6
 passing passing C 1 (b.833 80 90 60 100 passing, ô 95 to 0037 46 64 from 0,, 541 from 0.541
 EMI29.7
 
<tb>% <SEP> passing
<tb>
<tb> to <SEP> 0,

  246 <SEP> 15 <SEP> 30 <SEP> 75
<tb>
<tb> Temperature
<tb>
e- final <tb> <SEP>
<tb>
 
 EMI29.8
 equilibrium 54.4 572 62.0 51.5 (+) The "closed circuit" here consisted of collecting the output of the apparatus in a cyclone collector. to pass it on to
 EMI29.9
 sieve with a mesh of O | Ô33 mm and to return the refusal of this case continuously to the feed port. On average, the material being processed passed about six times through the apparatus.

 <Desc / Clms Page number 30>

 



   EXAMPLE 5.



   The apparatus described above (with reference to Figures 15 to 23) was employed to spray poly / ethylene (molecular weight approximately 50,000) with an average diameter of 6.35 mm and using water at 21%. 1'C as the vehicle fluid. The polyethylene had a tensile strength of 140 kg / cm2 and an elongation at break of 400%. The impactors 98 were driven at a speed of 7,000 rpm which gave a shear rate of 106.7 m / o with a power input of 2.2 hp / kg.

   The product supplied by the apparatus after passago had a particle size analysis of 95% passing through the 0.633 mm sieve, 85% passing through the 0.37 mm sieve, 50% passing through the 0.246 mm sieve, with maximum rise. with the temperature in the spray chamber reaching the final temperature of 65.6 C. It was believed that in this spray there was an amount of material retention time in the spray. approximately 0.001 seconds, this time naturally varying with the nature of the material treated.



   The fluid-to-solid ratio used in the pastry of this invention is not critical. It is necessary to have a minimum ratio of about 0.5 kg of fluid per 1 kg of solids in the feed to avoid excessive friction between the particles which gives off harmful heat in the region. spray. When it is desired to obtain the transport of solids by the fluid stream, the fluid-solid ratio is increased in the necessary proportion. It is generally preferable to use a ratio greater than about 2 kg of fluid / kg of solid filler for reduce the average temperature rise in the appliance.

   When using the transport of the solid charge by the fluid, it has been found that fluid-to-solid ratios of 30: 1 and even higher ratios are absolutely permissible.

 <Desc / Clms Page number 31>

 



   The material loaded into the apparatus is prepared in the usual way and it is desirable to limit the particle size to about 12.7 mm or less to avoid any sticking or physical jamming. Product handling is also of the usual type. because the pulverized solids can be separated from the accompanying fluids by decantation, cyclone separation, ultrasound or the like.

   It is often advantageous to use auxiliary devices to separate the coarse or oversized product and to return these materials to the feed, and for this purpose sieves, grading apparatus, sieves and the like can be employed. . It is sometimes advantageous to incorporate devices for classifying the fluids as integral parts of the apparatus and it is possible, according to various variants) to provide purifiers disposed at the periphery in the wall of the spray chamber to ensure automatic removal of oversized particles ot to return them to the inlet while allowing the particles to escape through the product collection duct.



   In general, it has been found to be advantageous: to use thin striking elements. knife-shaped, for spraying polymeric materials or substances with polymer-like properties while thicker impactors have been used for metals,: It should be noted that the spray efficiency decreases with As the impactor wears out and deformation becomes apparent during operation of the device and it is ultimately necessary to reshape or replace the elements, considerable freedom is available in the choice to the carrier finid.

   So if we want to obtain a product without a suspension - ¯ liquid it is advantageous to use a carrier fruit in liquid phase% Conversely, if we can obtain

 <Desc / Clms Page number 32>

 a dry product, it is preferable to use a gaseous carrier fluid. On the other hand. the lubricating characteristics inherent in liquids sometimes allow the spraying of materials such as viscous or sticky substances; of which otherwise would be very difficult.



   It goes without saying that it is possible to make modifications to the methods of the embodiments which have just been described, in particular by substituting equivalent technical means without departing for this from the scope of the present invention.

** ATTENTION ** end of DESC field can contain start of CLMS **.


    

Claims (1)

SUMMARY The present invention comprises in particular! the. A method of spraying highly stretchable materials. which consists in suspending coarse particles of these materials in an inert fluid medium, & hitting these coarse particles with impact speeds causing stress on the materials beyond the breaking point of the particles. faster than the dissipation of the stresses developed in these materials by plastic deformation of the molecular structure of said materials and in evacuating the materials suspended in the inert fluid medium of the striking region * 2. Embodiments of the method specified all 1, having the following features, taken separately or in combination; a) spraying gives a product the particle size of which is between about 0.8 and about 0.04 mm, the impact speed being such as to cause the particles to elongate in a proportion of less than about 30 % of the elongation at break of the particles; b) impact speeds vary between approximately 180m / s and approximately 750m / s. <Desc / Clms Page number 33> 3. A very extensible material spraying apparatus which comprises one or more rotors driven by motors mounted to rotate at high speed in an enclosure which forms a particle size reduction chamber, these rotors being provided with a large number of impactors profiles. mounted at their periphery, means for introducing the charge to be sprayed in a direction substantially radial with respect to the profiled impactors and means for evacuating from this enclosure the material which has passed beyond the impacting elements profiles. 4. Embodiments having the following peculiarities, taken separately or in the various possible combinations: a) the striking elements have a length / width ratio of between about 6: 1 and 15: 1; b) the striking elements have an angle of attack less than about 15; c) the impactors have a height / length ratio and a projection area to tooth crest / area to base ratio of less than about 2; d) the apparatus comprises means for introducing the charge to be sprayed in a substantially radial direction, which starts from the center of the driven rotor (s) in the direction of the region where these profiled impactors are located.