Patent Publication Number: US-3874334-A

Title: Rotatable grid assembly

Description:
United States Patent 11 1 1111 3,874,334  
 Roberts [1 Apr. 1, 1975 [54] ROTATABLE GRID ASSEMBLY 3,329,125 7/1967 Grossteinbeck et a1. 118/638 [75] Inventor: Kenneth E. Roberts, Providence, 8/636 3,641,976 2/1972 Corneau ..ll8/624 [73] Assignee: lndev, Inc., Pawtucket, R.I.  
 . Primary ExaminerMerv1n Stem 122] Flled: 1973 Assistant Examiner-Leo Millstein [21] Appl. No.: 392,543  
  57 ABSTRACT 52 US. Cl 118/621, 118/627, 118/629, A rotatable assembly for an electrostatic flocking p- 11 3 paratus wherein the entire grid tube is rotated as a 51 1111.01. B050 5/02 body, and wherein spherically adjustable supporting [58] Field of Search 117/175, 93.4; 118/621, means&#39;ere Provided at both ends of the tube, p  
 1 3/ 24 627 29 30 3g 3 ating with a Slidably removalble conduit on the electrode side of the chamber, together with a drive means [56] References Cit d completely shielded from the flock within the cham- UNITED STATES PATENTS 2.976.339 3/1961 Okmu Ct 211. ll8/624 3 C a 6 rawing Figures ROTATABLE GRID ASSEMBLY BRIEF DESCRIPTION OF THE INVENTION This invention relates to a rotatable grid for an electrostatic flocking chamber of the type commercially used in the textile and paper industries, for example. In such electrostatic flocking chambers a base material such as fabric, paper, plastic or the like is conducted usually in a horizontal plane through an electrostatic field, and short length fibrous material is introduced into the chamber and fibers are caused to adhere in substantially vertical upstanding positions at random to an adhesive which has been previously placed on the surface of the base material. After the adhesive has been caused to dry, the resulting flocked sheet or fabric is admirably suited for uses such as synthetic suede, synthetic velvet, wallpaper, vacuum-drawn products and a variety of other uses.  
 BRIEF DESCRIPTION OF THE PRIOR ART In providing the electrostatic field for the foregoing process, it has been found that it is highly preferable to provide a series of horizontally spaced grids, each capable of generating an electrostatic field involving a very high voltage such as 25,000 to 60,000 volts, for example. Since such grids are disposed in a flocking field, the flock tends to build up in the course of time on top of each grid. After the accumulation has reached a certain point, a mass of accumulated flock tends to slide off the top of the grid and to deposit on the base of the material as a large lump. This, in the past, has been the cause of a substantial and expensive spoilage of product. Accordingly, grid assemblies have been designed for rotation in the past, the speed of rotation being relatively slow, such as I to rpm, for example, and this rotation has been found helpful in avoiding the aforementioned problem by avoiding the accumulation of large quantities of flock upon any point on the surface of the grid.  
  However, it has also been established that it is virtually impossible to provide a grid for an electrostatic flocking machine which has a substantial width of, say, 6 to 8 feet, for example, thus requiring an electrostatic grid of comparable length wherein such a tube has an indefinite life span. Using a rotatable grid assembly, the structure of the assembly necessarily provided for rotation has also interfered with the convenience and speed of removing and replacing a burned out electrostatic grid.  
 OBJECTS OF THE INVENTION It is accordingly an object of this invention to provide a rotatable grid assembly for an electrostatic flocking apparatus which rotates as a unit, which has a relatively long life span, which is readily removable in the event that the electrostatic grid should burn out, and which is replaceable with ease and with minimum interruption of the continuity of operation of the electrostatic chamber.  
  Another object of this invention is to provide a drive means for such a rotatable grid assembly, which drive means is completely sealed from the electrostatic chamber and from the damaging effects of the flock contained therein.  
  &#39;Another object of this invention is to provide a rotatable grid assembly in which a high voltage electrode is readily connectable and removable, all without interfering with the operation of other parts of the electrostatic flocking chamber.  
  Other objects and advantages of this invention, including its simplicity and economy, and the ease with which it may be adapted to existing electrostatic flocking chambers, will further become apparent hereinafter and in the drawings.  
 DRAWINGS FIG. I is a sectional view in plan, showing a plurality of rotatable grid assemblies extending across the space within an electrostatic flocking chamber, and this view is taken as indicated by the lines and arrows 1-1 which appear in FIG. 2.  
  FIG. 2 is a partial view of the face portion of an electrostatic flocking chamber showing a portion of a drive means which embodies features of this invention.  
  FIG. 3 is a sectional view taken substantially axially along a rotatable electrostatic grid embodying features of this invention, as indicated by the lines and arrows 33 which appear in FIG. 2, showing the manner in which the rotary grid is connected to and associated with the structural members of an electrostatic flocking chamber and with the electrical conduit which energizes the grid.  
  FIG. 4 is a view similar to FIG. 3, showing the electrical conduit disconnected from the electrostatic grid, and showing the grid itself displaced in a manner to permit its ready removal from the chamber for replacement with a fresh electrostatic grid, and  
  FIGS. 5 and 6 are sectional views taken as indicated by the lines and arrows 55 and 6-6, respectively, which appear in FIG. 3.  
 DETAILED DESCRIPTION OF THE INVENTION In the description which follows, specific terms will be used for the sake of clarity in describing the specific forms of the invention which are shown in the drawings. The use of these specific terms is not intended to limit the scope of the invention which is defined in the appended claims.  
  Turning now to FIGS. 1 and 2 of the drawings, the electrostatic flocking chamber 10 has therein a pair of spaced apart insulated grid supports ll, 12 between which the rotatable grids, which are comprehensively designated by the number 13, are extended. Means are provided for rotating the grids at a predetermined speed, including a drive worm 14, a driven gear 15, shaft 16, and drive sprocket 17 connected to drive a roller chain 20, which, as appears more clearly in FIG. 2, is trained over an idler sprocket 21 and then trained in an alternating manner below and above a plurality of driven sprockets 22 each of which is connected by means of a drive shaft 23 to a particular rotatable grid, for rotating the grid at a predetermined variable rate of speed. The number 24 designates a motor which is connected to the drive worm 14 to cause the rotation of the rotatable grids.  
  It will be apparent that the chain 20 is a continuous chain, and that it returns from the driven sprocket 22 at that end of the chamber which is remote from the drive worm 14 by passing over supporting idler sprockets 25, 26 and returning to the drive sprocket 17.  
  Referring particularly to FIG. 1, it will be apparent that the drive chain 20 and its associated components are completely enclosed within a space provided by an outer wall 30, end walls 31, 32 and the aforementioned support member 12 of the grids. Also, the motor 24 is mounted externally of the chamber and its associated drive worm 14 and driven gear 15 are enclosed in a housing which includes the walls 33, 34, 35, and 36, top 37 and bottom 38.  
  Turning now to FIG. 3, the numbers and 51 designate grid supports which are secured to the structure of the electrostatic chamber, by brackets, hangers or the like, and which support the rotatable grid assembly of this invention.  
  Referring to the drive side of the apparatus, shown at the left in FIG. 3, the number 52 designates a bushing through which drive shaft 23 extends. Mounted on the drive shaft 23 is the sprocket 22, preferably composed of fiberglass, and which sprocket is driven in rotation by the roller chain 20. The number 56 designates a bushing secured to channel 57 to support the end of the drive shaft 23, preferably composed of nylon or the like. The number 57 designates a channel which may preferably be composed of fiberglass which secures the foregoing assembly in position with respect to the grid support 50.  
  Mounted upon the inner end of the drive shaft 23 is a spherical ball 60 preferably composed of a plastic material which serves this end of the grid member as a selfaligning drive component. A drive pin 61 extends through the ball 60 and its ends extend into a bayonet slot 62 formed in an internal bushing 63 which is located within the rotating grid.  
  The rotating grid as disclosed in FIG. 3 has an outer, elongated tube 64 composed of an insulating plastic which extends substantially completely across the entire width of the electrostatic flocking chamber, and which serves as an outer body for the grid components to be referred to in further detail. As will be apparent from the left end of the drawing in FIG. 3, set screws 65 are provided for securing the outer tube 64 to the slotted bushing 63.  
  Spaced inwardly from the bushing 63 within the tube 64 is a split spacer tube 66. Both tubes 64 and 66 are preferably composed of butyrate tubing or the equivalent.  
  Spaced within the tube 64, at a distance a from the end of the tube, is a metallic tube 67 having its end enclosed by a semi-spherical metallic plug 70 which bears against the inner end of the tube 66. The tube 67 and plug 70 are preferably composed of aluminum. Tube 67 is arranged to extend substantially completely across the working width of the flocking chamber, within the outer plastic tube 64, spaced from the end of the grid tube by the distance d which provides an air gap insulator and prevents high voltage from arcing over from the aluminum tube 67 to the outside walls of the electrostatic flocking chamber.  
  Referring now to the right-hand portion of FIG. 3, which is referred to as the electrode&#34; side of the flocking chamber, this end of the aluminum tube 67, held in position by a second split spacer 66, is provided with a plug 71 having a hole 68 centrally located in its end and receiving a banana plug 72 which engages a rotating steel plug 69 held captive in hole 68 by a bronze bushing 73 which is electrically conductive and rotatably transmits to the aluminum tube 67 the high voltage electricity that is necessary in the operation of the grid. The banana plug 72 is connected to a covered high voltage cable 74 which is energized from an outside source, not shown. The banana plug 72 is carried within a flexible hose section 75 which extends longitudinally within a rigid plastic tube 76 which extends through the support member of the electrostatic flocking grid and has a gooseneck curvature at 77 for ease of manipulation as will more readily become apparent. The outer electrode tube 76 is preferably composed of plastic, for example polyvinyl chloride tubing, and is securable in position with respect to the grid support 5] by means of a set screw 80 threaded into a plastic reinforcing collar 81 which is cemented to the grid support 51.  
  The outer electrode tube 76 is fitted tightly within an inner race 82 of a spherical bearing having an outer race 83 maintained in position by a cap 84 which is preferably made of plastic material such as polyvinyl chloride, for example. Cap 84 is secured against the outer grid tube 64 by set screws 85, here shown as three in number, which are also preferably composed of plastic material. These exert the required holding force on the outer race 83.  
  In the operation of the apparatus appearing in FIG. 3, it will be apparent that movement of the roller chain 20 drives the sprocket 22 in rotation, and that this motion is transmitted through the shaft 23 and the pin 61 to the stops within the slots 62 causing rotation of the tube 64 and all of the components contained within it, including the end plug 71 of the aluminum inner tube. The bronze bushing 73 is free to rotate with the tube and to rotate with respect to the stationary steel plug 69 and banana plug 72. Thus, the members 69, 72, 74, 75 and 76 remain stationary as does the inner race 82 of the spherical bearing. However, the outer race 83 of the spherical bearing together with its cap and the outer tube 64 are all free to rotate under the influence of the drive which is actuated by the roller chain 20. The high voltage electrostatic energy is supplied to the aluminum tube through the high voltage cable contained within the outer electrode tubed 76 and is transmitted through the rotating bronze bushing 73 and steel plug 69.  
  In the event that an electrostatic grid in accordance with this invention should burn out or otherwise fail in any way, it can be removed quite readily and replaced with a fresh electrostatic grid tube. After having deenergized the high voltage calbe 74, the operator opens a door (not shown) in the wall of the electrostatic flocking chamber and loosens the set screws 85 and the set screw 80. He then withdraws partially the entire structure contained within the outer tube 76 from the grid support 51 located on the electrode side of the machine, thus withdrawing the entire structure including the spherical bearings 82, 83, the cap 84, the neoprene hose 75, and the banana plug 72 from its steel plug 69. The operator then turns the tube 64 to a slight angle in order to align the ends of drive pin 61 with the longitudinal bayonet slot contained within the bushing 63. He then pulls the entire tube 64 and its contents to the electrode side of the machine, sliding the end of the tube off of the ends to drive pin 61 and beyond the periphery of the spherical ball 60. Then, taking advantage of the loose relationship existing between the neoprene hose 75 and the inside diameter of the spacer tube 86 at the electrode side of the tube and the flexibility of thehose 75, the end of the tube at the drive side can be swung downwardly into free space, and then withdrawn from the high voltage cable by pushing the entire tube in the direction of the drive side and out the door of the flocking chamber. This completely frees the tube and enables the operator to remove it conveniently and quickly through the door for repairs and replacement.  
  in inserting a fresh electrostatic grid tube, the operator merely reverses the steps just disclosed, first inserting the tube into the chamber, displacing it toward the electrode side of the chamber, drawing the end of the tube over the neoprene hose, swinging the opposite end into position over the spherical ball 60, aligning the slots within the bushing 63 with the drive pin 61, displacing the tube toward the drive sprockets to reach the position shown in FIG. 3, inserting the high voltage cable tube 76 so that the banana plug 72 fits within the steel plug 69 and rotating bushing 73, tightening the set screws 85 and then tightening the set screw 80. At this stage to rotation of the sprocket 22 acts through the ends of pin 61 and causes rotation of the entire grid assembly, and the high voltage cable may be reenergized, the rotatable grid assembly is accordingly put into normal operation.  
  When reference is made to a tube&#34; in this specification or in the claims, it is intended to cover an elongated hollow member of any cross-section, including round, square, rectangular, or any other polygon.  
  When reference is made to self-aligning drive and electrode end support herein, this is advantageous because it eliminates binding due to possible imperfect installation of grid assembly or imperfect axial alignment of the grid member assembly itself.  
  Although this invention has been shown and described with reference to certain specific embodiments thereof, it will be apparent that various changes may be made without departing from the spirit and scope of the invention. For example, certain parts of the electrostatic grid assembly can be used independently of others and parts may be reversed, and equivalent elements may be substituted for those specifically disclosed, all without departing from the spirit and scope of the invention as defined in the appended claims.  
 I claim:  
  1. in a rotatable grid assembly for an electrostatic flocking apparatus, the combination which comprises: a grid tube extending across said chamber and having a driven end and an electrode end, drive means at the driven end of said grid tube, for rotating said tube, an electrical socket within the electrode end of said grid tube, an electrical conduit connected to an external source of electricity and extending into said chamber and constructed to extend into said electrical socket to make an electrical connection, said connection including a rotatable contact which is shaped to form a relatively rotatable electrical connection, support means including a self-aligning bearing supporting said electrode end of said grid tube including an inner race carried by said electrical conduit and an outer race securable to said grid tube and means for maintaining said outer race in position on said grid tube.  
  2. The rotatable grid assembly defined in claim 1, wherein a plurality of said grids extend at spaced locations across said chamber, and wherein a common drive means is provided for rotating said grids.  
  3. The rotatable grid assembly defined in claim 2, wherein said drive means is essentially completely enclosed and sealed from contact with the flock in said chamber.  
  4. The rotatable grid assembly defined in claim 1, wherein said drive means is self-aligning.  
  5. The rotatable grid assembly defined in claim 1, wherein the means for securing the outer race in posi tion is a cap which is releasable from said grid, and wherein space is provided for such release.  
  6. The rotatable grid assembly defined in claim 1, wherein said electrode end includes a self-aligning connection whereby said grid is tiltable relative to the axis of the drive for installation or removal.  
  7. The rotatable grid assembly defined in claim 1, wherein said electrical conduit is carried in a rigid carrier which engages a rotatable electrically conductive bushing for electrical contact with a metallic portion of said grid.  
  8. The rotatable grid assembly defined in claim 1, wherein said rotatable bushing is engaged by a plug carried by a flexible hose and connected to the electrical wire which carries said electricity.  
  9. The rotatable grid assembly defined in claim 6, wherein said self-aligning connection includes a substantially spherical plastic ball, a drive means on said ball, and a bushing within the: driven end of said grid tube having a slotted portion to accommodate said drive means and securing device securing said bushing within said tube.  
  10. The rotatable grid assembly defined in claim 1, wherein said grid tube includes an elongated conductor tube extending across a major port of said grid tube, and wherein spacer tubes extend from the ends of said conductor tube providing an electrostatically insulating air gap between said metallic conductor tube and walls of said chamber.  
  11. The rotatable grid assembly defined in claim 1, wherein said conduit is carried in a rigid tube extending through an insulated support for said grid and wherein means are provided for securing said tube to said support.  
  12. The rotatable grid assembly defined in claim 1, wherein said grid tube includes an internally arranged electrically conductive tube and nonconductive spacer tubes extending endwise from both ends of said conductive tube, all within said grid tube, all of said inner tubes being maintained for rotation together as a unit with said grid tube.  
  13. The rotatable grid assembly defined in claim 1, wherein said drive means is isolated from the interior of the chamber thus preventing contamination and interference with the drive, and facilitating cleaning of the chamber during fiber changes and preventing lubricants from contaminating the flock within the cham-