US2378025A - Coating apparatus - Google Patents

Description

June 12, 1945. R. l.. MELTON ET Al.A 2,378,025 1 COATING APPARATUS s sheets-sheet lf'f* Filed May 9, 1942 INVENTORS /PoM/E l.. MELTON Havre Taeg/aso# A'IT RNEY.

June 12, 1945. R. L. MELTON ETAL COATING APPARATUS Filed May 9, 1942 3 Sheets-Sheet 55- www IIT H M, 5. .md f j .fw

T T ORNE v gated particles.

Patented June 12, 1945 coATiNG APPARATUS Rondell. Melton, and Aimer J. Thompson, Niagata Falls, N. Y., assignors. to The- Carbornndum Company, Niagara Falls, N.

tion of ADelaware Y., a corpora- Applioation Ma! 9, 1942, Serial No. 442,326

16 Claims. ('Cl. 91-18) This invention relates to improved apparatus for applying a coating of abrasive and other elongated particles to a web of such material as l paper, cloth, fiber,A and the like. It has for an object the provision of apparatus for the manufacture of a superior product. More particularly,

Ithe invention relates to. an improvement in apparatus for electrostatically projecting elongated particles onto an adhesively coated web which includes vibratory means for conveying the elongated particles into the electrostatic fleld.

Inthe coating of certain elongated particles,

such as abrasive particles, granular material,

fibrous materials, bristles and the like, it is desirable i most instances to apply such elongated particles in, an'orlented` or upstanding position with respect to the backing member. This is true, particularly, with coated abrasive webs since the cutting rate and grinding eillciency of such materials can be greatly increased by causing the individual abrasive particles deposited on the web to be so oriented that the longer dimension of each particle projects substantially normal to the surface of the web. Since abrasive particles, commonly employed in the manufacture of coated abrasive webs, are of irregular shape and have some surfaces or edges that are sharper than others and more suitable for abrading operations it is-desirable that these sharper surfaces, edges or points, be so oriented and positioned-as to engage the material being abraded.

Various suggestions have been made for the improvement of coating apparatus in an effort to produce an orderly orientation of the elon- 'Ihe usual "gravity method applying abrasive grain by dropping the granules from a hopper onto`a web has been superseded to a large extent by coating apparatus in which the particles are. projected upwardly against a downwardly facing adhesively coated web. Elecfor such upward projection as well as in modified apparatus for downward deposition and even sidewise projection.

One form of apparatus that has been found 45 to give satisfactory results is shown in the vpatent to Melton et al., 2,187,624. This includes relatively large and spaced apart upper and lower electrodes for producing an electrostatic field confronting relationship to the adhesive coating on the web. 'I'he granular particles receive sufcient electrostatic charge to cause them to -be oriented and forcibly driven upwardly through the strong electrostatic iield from the feed belt against the under side of the adhesive coatedl web.

In such device the bearings of the belt supporting and driving wheels are liable to become wornrapidly because of the iiltering into them of fine particles o'r granules with which they are constantly in contact. Because of the presence of the belt moving relative to the exciting grid or electrode there are variations in the gap potential gradient of the electrostatic iield. These in turn cause variations in thespeed with which the particles impinge on the adhesive coated web, and consequentlyvariations in the product. Because the particles lie on the belt in an undisturbed or dead layer until they are propelled toward the web by the electrostatic field, a field of high electrical potential is required to start the particles from rest and project them against the backing.

In the patent to Melton et a1., No. 2,254,016, a similar feed belt is employed, but a supplementary mechanical force is applied to the particles to assist the electrostatic'forces in lifting and propelling the particles toward the adhesive 3u coated web. In one modication a rotary beater wardly for a short distance. ofcation the feed belt is made l 40 These devices overcome the disadvantage of trostatic fields have been employed in apparatus therebetween, means for passing a downwardly facing adhesively coated web between the electrodes, a feed belt moving over the lower electrode, and means for feeding abrasive granules onto the top surface of the belt, whereby the granules are fed into the electrostatic iield in Il having the particles lie inert on the feed belt when fed into the electrostatic ileld and thus making the iield alone accomplish the projecting and orienting of the particles. 'I'hey do, however, retain the disadvantages' above shown to be inherent in themoving feed belt; furthermore,

ing feed belt and the provision of a vibrating feed table between the electrodes. This feed table is vibrated in such a manner that particles of material to be coated onto the adhesive coated web, such as abrasive granules,V are fed gradually and in an evenly distributed layer into the electrostatic neld where they are projected, in oriented arrangement, onto the adhesive coated web. The table is driven by a vibratory motor;

and its amplitude of vibration is small. It has no rotary bearings eith r in its driving or supporting means, and th there is nothing to be worn by contact witnthe coating particles. Since the table moves olyrslightly, it does not introduce the variations in gap potentiahgradient which the belt does, and thus the potential im- `posed on the grain can be exactly determined.v

in a series of rapid forward hops, similar to saw teeth in outline. This hopping action keeps the granules in suspension, and there is no sliding contact with the table surface. Abrasive wear on the tableis therefore negligible. More .important than this is the fact that such motion imparted to the granules keeps them alive," gives them an initial motion and thus prevents electrostatic "sticking 'of such granules. As a consequence, an electrostatic ileld of much lower potential is required with the vibrating feed table than with the belt feeder .of the patent to Melton et al., 2,187,624. This both makes the equipment requiredmuch cheaper and decreases the chance of leakage in the electrostatic held. The hopping action of all the particles on the feed table is uniform, regardless of their position longitudinally in the eld, and thus the particles are coated on1 the web more uniformly than with the use ofthe apparatus ofthe patent to-Melton et al., 2,254,016.

2,378,025 vention consists ofthe elimination of the mov-Y sive roll i. Supporting rolls IB and Il guide the ladhesively.coated web la into the electrostatic coating means B. Y

This coating means comprises means for set" ting up an electrostatic held. means for guiding the adhesively coated web in a xed path in said eld, and vibrating table means' for-feeding the particles to be coated on said web into confronting relationship with the web. The web is fed,

adhesive side down, in contact with the upper electrode l2 which is of good electrical Yconductivity, and which is shown connected to the ground and to the positive side L1 of a source of electromotive force.' The eiective potential of this source may be 20,000 volts or more, depending on electrode spacing, type of particles to be projected, etc. The source of electromotive force may produce a continuous unidirectional current, an intermittent, unidirectional'current, or a pulsating current such -as that which commonly is called alternating current. When a pulsating current is employed, the duration of the pulsations should he great enough to project and orient the particles eiectively. Ordinarily, and for more eiiicient operation, the lower electrodes are Vconnected to the negative terminal and the .upper electrode is connected to the positive terminal of the source of high 'electromotive Yforce and is grounded alsohas a precautionary measure. The polarity of the electrodes may be reversed. however, if it is so desired.V Guide rolls Il andV I3 are vertically adjustable and provide a means of varying the spacing of the web from the lower electrode and also to maintain the web in the proper line of travel. Situated a. proper distance beneath the web, the distance depending upon the size of particles to be coated upon the web and the electrostatic potential employed, is a vibrating feed table l5 made of electrically 40 non-conducting material and having a deck or In order that the invention may be'more clearly set forth and made more understandable reference is made to the accompanying drawings in which:

Figure 1 is a diagrammatic side elevation of one form of coating apparatus embodying the present invention;

Figure 2 is a side elevation of another form of device for electrostatically applying the particle coating;

AFigure 3 is a cross-sectional View the line 3-3 of Figure 2; and Figure 4 is a cross-sectional view taken along the line 4-4 of Figure 2.

Referring to the embodiment of the invention illustrated in Figure 1, there is shown means A for supplying an adhesively coated web, means B for applying elongated particles to the adhesive side of the web, and means C for drawing the coated web through the coating apparatus and into a drying zone or chamber.

The means A for supplying an adhesively coated web* comprises a roll 2 of a. suitable web backing material l and supporting rolls 3, l and 5 for guiding the web to the adhesive applying rolls 6 and l. Adhesive roll 6 is positioned to dip into a pan 8 of adhesive 9, and roll 'l maintains contact between the web I andthe adhetaken along top I6 of non-conducting material such as dry knot-free wood, Bakelite, Micartaf and the like, and upstanding sides l l to keep the particles from escaping off the sides of the deck. Below the deck are located means for distributing a high potential charge substantially uniformly over deck i6. Such means may be a metal sheet or metal sheets, of good electrical conductivity, in contact with under side of deck I6, and con-4 nected to the side of the high potential` source of electromotive' force opposite from that to which the upper electrode is connected. In the device Y shown in Figure 1 this electrode is composed of three separate portions I6' connected by bus bar ll' supported in insulators I8, and flexible con'- nectors I9, for the purpose of allowing the length of the electrostatic eld to be changed by disconnecting any of the electrode portions IE'. The bottom electrode can, however, be'made in one piece, of the same length as the upper electrode l2 or shorter if desired. Flexible wire 20 con' nects bus bar Il' to the high potential lead wire In through a. terminal on insulating means 2| on the base of the device. l The electrostatic eld existing between top electrode l2 and the bottom electrode composed of the electrode portions i6' has lines of force which in the main extend between electrodes in the shortest possible line. Since the electrodes in this modification are parallel with the top of the feed table, the lines of force extend in a direction perpendicular to the top surface of the feed table. At the right and left hand ends of the iield. deiined roughly between the ends of upper electrode l2, the lines of force bulge outwardly for a magnetic driving unit 29 connected alternating current. Hopper 21 issupported on short distance beyond the ends of the upper electrode.

The feeding table i is supported for .'lbratory motion by sprlng'steel supports 22, which extend between the bottom of the table and base 2l at an angleto the vertical. as shown in Fig. l.l Base 22 is supported by resilient means such as rubber blocks 24, which isolate the vibration from the foundation. The table Il is vibrated by an electromagnetic vibrating device 2l, contained in subframe 26 bolted to base 2l. Such vibrating device is well-known, and comprises a reciprocating armature of magnetic material and a wound stator which, when connected to a source of alterhating' current, alternately pulls and releases the armature. The latter is connected to the table I 5. and thus vibrates it-longitudinally. By reason of the angle at which the spring supporting members 22 are disposed, the table on its momentary release by the stator travels to the left, in Fig. l. with a slight vertical component, whereby the material conveyed thereby is given the forward saw tooth motion beforerei'erred to. The particulate material on the feed table thus is given successive rapidly recurring positive feeding impulses in a direction at an acute angle to and across the lines of force of the electrostatic held between electrodes.

To feed the particles on to table I5 there is provided a vhopper 21 with a vibrating feed gate 22 disposed at an angle to the horizontal, as shown, and vibrated in a horizontal plane by the to a source of frame part 30; driving unit 29 is also supported thereon by the resilient rubber washers 22a and is made vertically adjustable by means of threaded rods 3l and nuts 32.

Electrical voltage control devices 2l and 34 are connected to a source of alternating current La, L4. The control devices regulate the amplitude of vibration of feed gate '2l and of table l5, respectively, and'thus govern-the rate and quantity of the particles or granular material delivered to the electrostatic eld. Switches I5 and 36 are provided to start and stop the magnetic driving units 29 and 25, respectively. A bin Lis provided to catch whatever particles remain on the feed table and are finally fed off the far end thereof.

The means C draws the particle coated web l-b from the coating apparatus into a drying chamber, not shown. Suchmeans comprises, as shown in the "drawings, a supporting roll M a suction drum 2l, an idler roll 25, a rack 4l for supporting the Vweb Ib, and an endless conveyor 4I for festooning and transporting loop's of the web to the rack 4I.

In Figs. 2, 3, and 4 there is shown a modification of the means for feeding and applying the particles to an adhesively coated web. In such modiiicatlon a web lf-'a with van adhesive coating on the top 'face thereof is fed over guide roll 42 l in the direction of the arrow. The web then progresses around guide roll 43, supported by bracket 44 on frame 45 of the device, so that the adhesive coating faces downwardly. The uncoated back of the web ls maintained in contact with the top electrode (shown in F18. 2. by way of illustration only, as composed of two portions Il and I4) of the electrostatic coating means. and. after is made in any conventional manner as, for exbeing coated with the granular material in the ample. by welding together channel o r I beams.

It is constructed generally inthe shape of a parallelopiped, but has the top surface slanted oil', at one side, as shown at 45 in Fig. 2. 0n this slanted portion of the frame are secured a plurality of bosses 41; in the modiilcation shown there are four such bosses one at each corner of such slanted portion 46 of the frame. There is .provided a central hole-48 through each boss and an alined hole through the frame for the purpose of allowing an elongated nut 4l to nt therein. This nut is provided at the bottom .thereof with a i'iange Il, and at the top has a bearing member 5| keyed thereto, as at 52. Sprocket 53 is secured to member 5I, as by projections on the upper end ofl member 5I fitting in holes in the sprocket. A nut 54 is provided to screw on to the top of elongated nut 49 to retain bearing 5| in adjusted position and sprocket 5l in place. The elongated` rod l5 is likewise screw threaded, and projects through a hole in the top of the electrode supporting frame 5l, which is made of welded angle iron. Top and bottom nuts 51 and 58 secure rod 55 to frame 5. and make possible individual adjustment of the 'carrier relative to ,each rod, and therefore'allow initial alinement of the electrode carrier. Turning oi' sprocket 52 rotates elongated nut 43 and thus advances or retracts 'od 55. To allow the quick adjustment ofthe carrier 55 to diierent parallel planes, all sprockets 53 of the adjusting means are connected by a chain 59. A hand wheel is connected to one nut 4l',

which in this case is made long enough for that purpose, as by key 5| and nut 52 screwed to the upper end of nut 49'.

The` upper electrode is made of material of good electrical conductivity, such as a metal, and in this modification is composed, for reasons of convenience, of two parts 03 and 64. Each part has secured'on its upper face, near eachv end thereof, an upstanding `Lshaped bracket 65. 'I'he brackets 65 are securely held in position on the frame carrier 58 by virtue of being clamped between portions of brackets 8B, secured to electrode carrier near the ends thereof, portions of T bracket 61, secured near'the center of electrode carrier 56, and eccentric clamping means 68, located, as shown, at each bracket. 'I'he upper electrode is connected through the machine frame to the grounded side of a, high potential source of electromotive source by means not shown.

The inclined particle feeding table 59 is parallel to the upper electrode a d supported on similarly inclined'frame 10. This frame is supported at its lower end on a cross channel member of main frame 45 and at the upper end on a channel member supported by a pedestal 1I within the main frame. Frame 10 is carried on resilient supports such as blocks oi' rubber 12 held by top and bottom cup-like members 13. secured respectively. to frame 10 and frame 45. .For the purpose of vibrating table 09 in such manner that the particles fed thereby describe a saw tooth movement, it is driven by electromagnetic vibrator means, indicated generally by the character 14. In the particular device shown. two such means are employedv with their stators connected to the same alternating current source', so that they vibratev to Francis, No. 2,161,342, comprises a wound stator 15 connected to a source of alternating currenil (not shown), adjustably supported on vertical plate 18, which is attached to frame and braced thereon by gussets 11, by means of four bolts 18 which pass freely through holes in plate 18 Aand are screw threaded into bosses on the frame of the stator. Horizontal adjustment of the stator is accomplished by loosening nuts 19 (see Fig. 4) on bolts 18 moving the stator to the desired position, and then tightening the nuts to lock the stator in position. An amature 80 of laminated magnetic material is alternately attracted and released by the stator 15. The arma- .ture is secured to the centers of a plurality of spring leaves or vibrator bars 8|, the ends of which are clamped rigidly between plates 82 and 83 by means of bolts 84. Plates 83 are attached to frame 10, and are braced thereon by gussets 85. Between adjacent leaves 8| at their ends and at the center are located thin spacer members 88, to eliminate sliding friction between leaves when the spring vlbrates horizontally.

Armature 80 is attached to a member 81 which .is C-.shaped in vertical section to provide parallel vertical members 88 and 89. Member 88 contacts the spring on one side thereof, whereas the other side is contacted by abutment member 9|, held in clamped position by bolt 90 which has threaded engagement with portion 89 of member 81. Lock nut 92 secures bolt 90 in clamping position. The spring leaves 8| aremade of a strong, resilient material such as spring steel. For a'given distance between the spring supports 82, the width and thickness ofthe spring leaves and the total number of spring leaves in each of the two spring assemblies employed is so chosen that when the feed table is mounted on the two spring assemblies, as shown in Figure 4, and stator winding has impressed upon it the operating alternating current, the armatures 80 intermittently approach but do not strike their respective stators 14. Thus the table vibrates smoothly and silently, and the mechanism is free from self-destructive jarring. Part 88 terminates in a flange 93, to which is secured, by means of bolts 94, plate 95, which is attached to a projection 98 of table 89by conventional means such as screws or bolts. In the modication employing two vibrator units, as shown in Figs. 2, 3 and 4, the weight of the table 69 is carried entirely by the leaf springs 8|.

Table 89 is constructed of a suitable electrically insulating material, such as dry seasoned knot-free hard wood, suitably braced longitudinally and laterally. A deck 91 is secured to the upper surface of table by bolts 98 located along the edges of the deck, and is provided with upstanding edge members 99 of insulating material. Deck 91 is made of a material which is so poorly conducting that not enough current can flow along or through it to cause arcing between the bottom and top electrodes, yet is sumciently conducting to allow a small leakage current to supply negative charges to the granular material in order that the particles may be repulsed from the table across the electrostatic field toward the grounded upper electrode. Such materials include dry knot-free wood, and fibrous material bonded with an insulating resin such as Bakelite or Micarta. A thin layer |00 of a metal of good electrical conductance is provided on the under surface of the deck, for the purpose of spreading the charging current evenly over the deck or electrode 91. Such layer may be a preformed plate or, conveniently, may be sprayed on as with a Y electrode is connected, by means of bus bar |0I,

metal spray gun. In'the modification shown the metal layer is divided at the lateral table braces; the separate parts of the 1ayer are electrically connected with the side of the high potential source of current, opposite to that to which'the upper which is supported bysuitable insulators |02 and fed by the supply cable |08. The supply cable and bus bar are insulated at points where they are near metallic parts4 of the device. Flexible electrical leads |04 are connected by suitable means to the bus bar 10| and to the sections of the metal layer |00 under the table deck. The 1ayer of metal on the bottom surface of the bottom electrode may, if desired be made in'one' piece instead of separate parts as shown.

As in the case of the apparatus shown in Figure l, the electrostatic field between upper electrode 88, 84 and lower electrode |80 has its lines of force throughout its extent with the exception of the'ends of the field disposed directly across the electrodes. Thus, in the main, the lines of force are substantially perpendicular to the top surface of the feed table, since both the upper and lower electrodes are parallel to such surface. As was explained in connection with Figure l, and as set out below in the discussion of the func tion of baille H5, the lines of force at the edge of the field defined roughly by the ends of upper electrode 83, 84 bulge outwardly somewhat in a direction away from the field. The feed table gives the particulate material thereon successive rapidly recurring positive feeding impulses in a horizontal direction. Such direction is at an acute angle to and across the lines of force of the electrostatic eld.

To feed the particles on to the-table 89 there is provided a hopper |04 located in an upper extension frame |05 supported on the main frame 45. The bottom of the hopper is provided with an inclined feed gate |08, which is vibrated in a horizontal plane by thefmagnetic driving unit indicated generally at |01, which is similar to units 14 for vibrating table 89. Wound stator |08 of driving unit |01 is connected to a suitable source of alternating current, of a frequency, for instance, of 25 or 60 cycles per second, and alternately attracts and releases armature |09, which is connected to the. center of leaf spring H0, and which carries atits left end (Fig. 2) the feed gate |08.

The feed gate |08 and driving unit |01 are adjustably mounted on frame 45 by means of threaded rods and nuts ||2 and resillently supported by the rubber washers H8. Means are provided to vary the voltage and consequently the current supplied to the `two table driving units |4 and the feed gate vibrating unit |01. Such means is similar in each case to that shown diagrammatically in Fig. l, at 38 and 84, for controlling the table vibrating means and the hopper feed gate. Of course, in` the present modification, the two units 14 are connected in parallel and are controlled by the same means. The voltage control means are conveniently located in frame |05. One suchmeans, au auto-transformer or Variac H3, with hand wheel ||4, is shown in Fig. 2. Two such controls ||3 are employed in the device of Fig. 2, one for unit |01 and one for both units 14.

A curved baille plate member H5, of Micarta or other poorly conducting material, is mounted 'on the side rails 99 of the vibrating feed table and extends the full width thereof. This baille cooperates with the table top 91. and side Walls 99 to form an enclosed duct which conflnesthe movement of the granular particles until after they have passed through the curved edge of the g electrostatic field and reached a point of maximum field intensity. Thus the projection of the particles is prevented untill after they have become fully charged and conditioned for maximum velocity of projection and orientation. Precoating of the adhesively coated web I-a before it enters the zone beneath the electrode 84 is also prevented.

The baille also overcomes the tendency of the granules to be repelled outwardly as they enter the margin of the electrostatic neld which is caused by the edge effect or natural bulging of the electrostatic lines of force along the edge of the electrode members. Without such a baille face of the particle carrying table and the web.

2.' Apparatus for the manufacture of particle v surfaced webs comprising a particle projector which includes a feeding means having a particle downward positioned above said particle carrying the granules are repelled to such an extent, particularly when high voltages are employed, that they are not carried into the field but build up a ridge or mound along the entrance thereto. This diillculty is completely overcome by the bafile member H since the particles are in fact fed through an electrically charged duct and not subjected to the attraction of the oppositely charged electrode 64 until after passage through the edge of the electrostatic field.

A hopper H8 is provided adjacent the lower end of table 69 to receive the particles which have not been deposited on the web by the electrostatic field.

The two modifications of the device disclosed,

age control means for its driving unit. The amv plitude of vibration of the feed table remains constant for a given setting of the voltage control means for its driving unit or units. Thus for diiferentmaterials fed onto the table the optimum amplitude of vibration can be chosen to convey the said table substantially the particles, distribute them evenly over the table deck, and to present them in the best condition for being propelled against the web by the electrostatic field.

Other advantages will be apparent from the foregoing disclosure to those skilled in the art, and while specific embodiments have been used to illustrate our invention, it is to be understood that the invention is.not limited to those embodiments but is defined by the appended claims.

We claim:

1. Apparatus for the manufacture of particle surfaced webs comprising a particle projector which includes a feeding means having a particle carrying table whose top surface lies substantially in a plane, means to vibrate the particle carrying table in a direction at an acute angle tothe plane of the top surface thereof substantially uniformly throughout its extent, -said angle being measured between the top surface of the table and the path of its vibration in the direction of feeding of the particles, whereby the particles carried thereby are moved progressively over said surface, means for supporting an adhesive coated web with an adhesive surface downward positioned above said particle carrying member, and means to create and maintain a high tension electrostatic ileld in the space between the top surmember, an electrode positioned above the web being surfaced, and means for applying a potential diilerence tosaid electrodes.

3. Apparatus Yfor the manufacture of particle surfaced webs comprising a particle projector whichl includes a vibrating feed table to carry and cause particles to move thereover progressively, means for vibrating all portions of said table uniformly, means for. supporting and traversing an adhesive coated web with an adhesive surface downward positioned above said feed table, means to create and maintain a high tension electrostatic eld in the space between the feed table top surface and the web, means to feed particles on to the infeeding end of the feed table, and means cooperating with the top of the feed table to formy an enclosed duct through which the particles are fed until they have reached a point of high intensity of the electrostatic field.

4. Apparatus for the manufacture of particle surfacedwebs comprising a particle projector which includes a vibrating feed table having a substantially plane top surface to carry and cause the particles to move thereover progressively, means for feeding particulate material on to the infeeding end of the table, means for vibrating 5. Apparatus for the manufacture of particle surfaced webs comprising a particle projector which includes a vibrating feed table having a substantially plane top surface to carry and cause particles to move thereover progressively, means for feeding particulate material on tothe infeeding end of the table, means for vibrating the feed `table substantially uniformly throughout its extent in a direction at an acute angle to the table top measured in a direction away from the in` feeding end of the table, means for supporting and traversing an adhesive coated web with an adhesive surface downwardly positioned above said feed table, and means to create and maintain a high tension electrostatic eld in the space between the feed table top surface and the web, said last named means comprising an electrode positioned below the top surface of the table and an upper electrode above the adhesive coated web, the upper electrode being so positioned that the uniformly through- I out its extent in a direction at anacute angle distance beyond it.

6 a infeeding end of the table projects a substantial 6. Apparatus for e manufacture of particle surfaced -webs comprising a particle projector which includes a vibrating feed table torcarry and cause particles to move thereover progressively, said feed table having a substantially plane top surface, means for feeding particulate material on to the infeeding end of the table, means for vibrating the feed table substantially uniformly throughout its extent in a direction at an acute angle to the table top measured in a direction away from the nfeeding end of the table, means for supporting d traversing an adhesive coated web with an sive surface downwardly positioned above sai ed table, and means to create and maintain a gh tension electrostatic field in the space betw Q the feed table top surface and the web, said last named means comprising a bottom electrode integral with the feed table and an upper electrode positioned above the adhesive coated web, the. bottom and top electrodes being so positioned with respect to the table and to each other that the electrostatic field between them extends over the feed table for a substantial part of its length but does not extend over the infeeding end of the feed table.

1. Apparatus for the manufacture of particle surfaced webs comprising a. particle projector which includes a vibrating feed table to carry and cause particles to move thereover progressively, said feed table having a substantially plane top surface which is positioned substantially horizontally, resilient supports for the feed table which allow it to vibrate substantially solely at an acute angle to the table top measured in a, direction away from the infeeding end of the table means for vibrating the feedtable, means for feeding particulate material on to the lnfeeding end of the table, means for supporting and traversing an adhesive coated web with an adhesive surface downwardly positioned above said feed table, and means to create and maintain a high tension electrostatic eld in the space between the feed table top surface and the web, said electrostatic eld covering a substantial part of the length of the feed table but being so positioned that the infeeding end of the table is substantially outside the field.

8. Apparatus for the manufacture of particle surfaced webs comprising a particle projector which includes a vibrating feed table to carry and cause particles to move thereover progressively, said feed table having a substantially plane top surface which is located at an acute angle to the horizontal, resilient supports for the feed table which allow it to vibrate in a substantially horizontal plane 4but restrain it from substantially all other movement. means for vibrating the table in a horizontal plane, means for feeding particu-- late material on to the upper end of the table, means for supporting and traversing an adhesive coated web with an adhesive surface downwardly positioned above said feed table, and means to create and maintain a high tension electrostatic field in the space between the feed table top surface and the web, said electrostatic eld covering a substantial part of the length of the feed table but being so positioned that the upper infeeding end of the table is substantially outside the eld.

9. Apparatus for the manufacture of particle surfaced webs comprising means to create and maintain a high tension electrostatic eld having traversing an adhesive coated web'with' an adhesive surface downwardly positioned above said feed table. Y

10. Apparatus for the manufacture of particle' surfaced webs comprising means to create and maintain a high tension electrostatic eld of substantial extent, the lines of force of which vare in Y, the main parallel to each other, a vibrating feed d table having substantially a plane top surface so located that a substantial part thereof lies in the eld so that the lines of force are substantially normal to the said top surface, the feed table hav ing an infeeding end so located that the field strength at that point is substantially ineffective, means for supporting the feed table so that it may vibrate substantially solely in a direction at an acute angle to the lines of force of the eld, means for vibrating the feed table whereby the material is fed into and through at least part of the field in a series of saw-tooth shaped hops,

lthe'material being given repeated positive impulses in a direction across the lines of force of the field, means for feeding material on to the infeeding end of the table, and means for supporting and traversing an adhesive coated web with an adhesive surface downwardly positioned above said feed table.V

11; Apparatus for the manufacture of particle surfaced webs comprising means to create and maintain a high tension electrostatic iield having lines of force which in the main are parallel to each other, said. means comprising tcp and bottom electrodes of substantial extent, said electrodes being parallel to each other, a vibrating material feeding'table lying within the electrostatic fleld so that the top material feeding surface is parallel to the top and bottom electrodes, means to vibrate the table substantially solely in a direction atan acute angle to the lines of force togive the material thereon successive forward feeding impulses in a direction across the lines of force,.means for feeding particulate material on to the table at the infeeding end thereof and means for supporting and traversing an adhesive coated web with an adhesive surface down-` wardly positioned above the feed table.

l2. Apparatus for the manufacture of particle surfaced webs comprising means to create and maintain a high tension electrostatic field having lines of force which in the main are parallel to each other, said means comprising top and bottom electrodes of substantial extent which in the main are parallel to each other, a vibrating material feeding table lying within the electrostatic iield so that the top material feeding surface thereof lies substantially normal to the lines of force, said feeding table having an infeeding end which lies substantially outside the effective field, means to vibrate the table substantially solely in a direction at an acute angle to the lines of force to give the material thereon successive forward feeding impulses in a direction at an acute angle to the lines of force, means for feeding particulate material onto the table at the infeeding. end thereof, and means for supporting horizontal and substantially normal to the lines.

of force, said table having an infeeding end. means to vibrate the table substantially solely in a direction at an acute angle to the lines of force to give the material thereon successive forward feeding impulses in a direction across the lines of force, means for feeding particulate material on to the table at the infeeding end thereof, and means for supporting and traversing an adhesive coated web with an adhesive surface downwardly positioned above said feed table.

14. Apparatus for the manufacture of particle surfaced webs comprising means to create and maintain a high tension electrostatic field having lines of force which in the main are parallel 1 to each other, said means comprising top and bottom electrodes of substantial extent which lie i parallel to each other and which incline to the horizontal at an acute angle, the vibrating material feeding table lying within the electrostatic fleld so that the top materia1 feeding surface thereof lies substantially'parallel to the electrodes and substantially normal to the lines of force, means to vibrate the table substantially solely in a horizontal direction to give the material thereof successive forward feeding impulses in a direction across the lines of force. means for feeding particulate material on to the table at the upper end thereof, and means for supporting and traversing an adhesive coated web with an adhesive surface downwardly positioned above said feed table. r

15. Apparatus for the manufacture of particle surfaced webs comprising a particle projector ,which includes a feeding means having a particle carrying top surface. means to vibrate the feeding means in a direction at an acute angle to the top. surface thereof, said angle being measured between the top surface of the feeding means andthe path of its vibration in the direction of feeding of the particles whereby the particles carried thereby are moved progressively over said top surface, -means for supporting an adhesive coated web with the ladhesive surface downward positioned above said particle carrying member, and means to create and maintain a high tension electrostatic eld in the space between the top surface of the feeding member and the web.

16.`\Apparatus for the manufacture of particle surfaced webs comprising a particle projector which includes a feeding means having a particle carrying top surface. means to vibrate the feedingmeansin a direction at an acute angle to the plane of the top surface thereof. said angle being measured between the top surface of the feeding means and the path of its vibration in the direction of feeding of the whereby the particles carried thereby are moved pvely over said top surface, means for supporting an adhesive coated web with the adhesive surface downward positioned above said particle carrying member, and means to create and maintain a high tension electrostatic eld in the space between the top surface of the feeding member and the web, 'said last named means comprising a high tension electrode attached to thefeeding means as an'integral part thereof.

Riom L. neuron. AIMER J. THOMPSON.

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