Patent Publication Number: US-6907908-B1

Title: Hopper apparatus and method for application of joint compound to corner beads

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates generally to drywall construction and is particularly concerned with a hopper apparatus and method for applying drywall mud or joint compound to corner beads or tape-on-trims prior to their attachment to joints or corners between adjacent drywall panels. 
   Corner beads are elongate, narrow strips of metal, plastic, or metal with a paper face on one side, or the like folded or angled along their longitudinal center line, or along a line offset from the center line in some cases, to produce a generally v-shaped cross-section. They are made in various angles and corner shapes, including sharp 90 degree angle corners, sharp corners at other angles, rounded or so-called “bullnose” corners of various angles, and offset or L-shaped corners. Corner beads are also designed for covering both inside (concave) and outside (convex) corners. For application to an inside corner, drywall mud is applied to the outside (convex) faces of an inside corner bead. For application to an outside corner, drywall mud is applied to the inside (concave) faces of an outside corner bead. Joint compound is applied to the appropriate faces of the bead, and the bead is then pressed against the corner, with the joint compound forming an adhesive joint between the bead and corner. 
   Although drywall mud or joint compound may be applied to corner beads by hand, this is a time consuming and inconvenient process. Hopper devices have been proposed in the past for applying joint compound to the inside faces of an outside corner bead. One such apparatus is described in U.S. Pat. No. 5,169,449 of Raught. The apparatus comprises a hopper with a V-shaped trough in its base, and triangular shaped end walls at opposite ends of the trough forming a generally V-shaped gap between the lower edge of each end wall and the trough. Removable end panels are adjustably secured to the end panels to adjust the height of the gap. A corner bead is fed through the base of the hopper from one end wall opening to the opposite end wall opening, and drywall mud in the hopper will be applied to the upwardly facing surfaces of the corner bead. All except a thin layer will be scraped off by the edge of the end panel as the corner bead exits the hopper. Removable liners may be placed into the hopper to define different trough cross-sectional shapes, corresponding to different shapes of corner bead, and associated with end panels with corresponding edge shapes. 
   The Convertible Hopper manufactured by Pla-Cor Incorporated, of Santee, Calif. has an open base across which a feeder is secured, the feeder having a V-shaped trough for receiving an outside corner bead. Removable panels or gates are secured to opposite end walls of the hopper for forming a V-shaped inlet and outlet opening with the opposing surface of the feeder at opposite ends of the feeder. The feeder can also be adjusted for different shapes of outside corner bead, by placing a feeder insert comprising a generally V-shaped trough over the main feeder. This requires removal of the feeder from the hopper, placement of the feeder insert over the feeder, and re-attachment of the feeder insert and feeder to the hopper. This hopper apparatus is designed to be converted between 90 degree corner beads, ¾ inch bullnose, and 1½ inch bullnose corner beads. 
   One problem with prior art hoppers having corner bead feeders for applying joint compound is that they can only be used for outside corner beads, i.e. corner beads that are applied over outside, or convex, corners in a building. However, a large number of the corner joints between adjacent drywall panels are inside corners. Up to now, there has been no effective and accurate means to apply drywall mud to inside corner beads. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a new and improved hopper apparatus and method for application of drywall mud or joint compound to corner beads. 
   According to one aspect of the present invention, a hopper apparatus for applying joint compound to corner beads is provided, which comprises a hopper for holding joint compound having an open upper end and a lower end, a feeder apparatus secured across the lower end of the hopper, the feeder apparatus comprising a tray or channel, a series of elongate feeder inserts for selectively securing in the tray, and a releasable fastener device for releasably securing a selected one of the feeder inserts in the tray. The feeder inserts comprise a first set of inserts each having a V-shaped indented cross section for guiding an outside corner bead under the lower end of the hopper with the concave face of the corner bead facing upwardly and a second set of inserts each having an inverted V-shaped cross section with the V-shape having an apex facing upwardly. 
   This arrangement permits the same basic hopper and feeder apparatus to be used to coat the surfaces of both inside and outside corner beads. A series of end gates may be provided for selectively securing to the hopper above the respective ends of the selected feeder insert in the tray, each end gate having a lower edge shaped to match the cross-section of a respective feeder insert such that the lower edge of the end gate and upper face of the feeder insert together form a V-shaped or inverted V-shaped end slot for receiving a corner bead as it is fed through the feeder apparatus, the end gates including a first set of end gates having a convex V-shape with a downwardly directed apex for use with the first set of feeder inserts and a second set of end gates having an indented V-shape with an upwardly directed apex for use with the second set of feeder inserts. 
   The first and second sets of feeder inserts and associated end gates will be provided in a plurality of different angles and corner shapes, including sharp angled corners and rounded, bullnose corners. In this way, a single hopper and feeder apparatus can be used for an entire range of inside and outside corners, simply by removing and replacing the feeder insert and end gates each time a new corner bead is to be coated with joint compound. 
   In an exemplary embodiment of the invention, the feeder apparatus is secured beneath the hopper and the lower end or bottom wall of the hopper has an opening for supplying joint compound to the feeder apparatus. The feeder apparatus may have a pair of spaced vertical side walls and the tray is a generally U-shaped channel member secured between the upper ends of the side walls. The entire apparatus is secured to the bottom wall of the hopper. The tray or channel member has a flat base spaced from the bottom wall of the hopper, and interchangeable insert members with flat lower faces can be selectively positioned in the tray and releasably secured to it so that the selected insert member extends lengthwise between the end walls of the hopper and beneath the opening in the hopper bottom wall. Therefore, rather than having to remove the entire base feeder apparatus from the hopper every time a new feeder insert is to be used, all that is necessary is to release the previously installed feeder insert from the tray, slide it out, and slide in a new feeder insert before securing it in position in the base of the tray. Any suitable releasable fastener devices may be used to secure the selected feeder insert in the tray, such as bolts or the like. 
   In an exemplary embodiment of the invention, first and second sets of flexible panels are provided for selectively securing at opposite ends of the channel above the selected feeder insert and between the respective end gate and an end wall of the hopper, the first set of generally rectangular flexible panels having at least a first end edge with a convex, V-shaped projection, each first end edge angle and shape matching the angle and shape of respective feeder inserts of the first set, and a second set of generally rectangular flexible panels having at least a first end edge with an upwardly directed, generally V-shaped indent, the first end edge angle and shape of each flexible panel of the second set matching the angle and shape of respective feeder inserts of the second set. The flexible panels are positioned such that their end edges protrude slightly below the corresponding end edge of the matching end gate and into the end slot of the feeder apparatus, and the end edges will scrape excess drywall mud off the corner bead as it exits the feeder apparatus. Each flexible panel may have a second end edge opposite the first end edge of matching angle and shape to the first end edge. This allows the panel to be reversed when the first end edge becomes worn due to the abrasive effects of the drywall mud or joint compound. The end edges of the flexible panels may be serrated. 
   According to another aspect of the present invention, a hopper apparatus is provided, which comprises a hopper having an open upper end, a lower wall, opposite side walls, and opposite end walls, and an interior for holding a quantity of joint compound, the lower wall of the hopper having an opening, and a feeder apparatus secured beneath the lower wall of the hopper, the feeder apparatus comprising a generally rectangular, elongate channel having a flat base wall, the channel extending between opposite ends of the lower wall of the hopper, and a plurality of different elongate feeder inserts for selectively mounting in the channel for guiding corner beads of different angles and shapes through the channel. Each feeder insert has an upwardly facing surface of different cross-sectional shape from the other feeder inserts, and a flat lower portion for seating against the flat base wall of the channel, and a fastener device is provided for releasably securing a selected feeder insert in the channel. The apparatus further comprises a plurality of end gates for releasably securing to the opposite end walls of the hopper above opposite ends of the channel, each end gate having a lower edge shaped to match the cross-section of the upwardly facing surface of a respective feeder insert, whereby the lower edge of the end gate and the upper face of the selected feeder insert together form a slot of shape matching the cross-sectional shape of a selected corner bead for guiding the corner bead through the feeder apparatus with upper faces of the corner bead facing the opening in the lower wall of the hopper, such that joint compound flowing through the opening into the channel will be deposited on the upwardly facing surfaces of the corner bead. 
   This apparatus allows drywall mud or joint compound to be applied quickly and easily either to the inside faces of an outside corner bead, or the outside faces of an inside corner bead, and allows joint compound to be applied to any shape of corner bead using the same basic apparatus, only requiring changing out of a feeder insert and end panels to accommodate any new inside or outside corner shape or angle. The hopper apparatus can be converted quickly and easily to coat inside or outside corner beads of various shapes and angles, simply by removing and replacing the feeder insert and associated end gates and panels. This will make corner finishing of drywall joints faster and more efficient, and will reduce equipment costs, since only one basic hopper apparatus is required. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be better understood from the following detailed description of an exemplary embodiment of the invention, taken in conjunction with the accompanying drawings in which like reference numerals refer to like parts and in which: 
       FIG. 1  is an end elevation view, partly broken away, of a hopper apparatus according to an exemplary embodiment of the present invention; 
       FIG. 2  is a perspective view of the hopper apparatus of  FIG. 1 ; 
       FIG. 3  is an end elevation view similar to  FIG. 1 , illustrating a selected feeder insert and matching end panel and gate installed in the feeder apparatus for guiding a drywall tape or corner bead through the feeder apparatus beneath the hopper; 
       FIG. 4  is a perspective view similar to  FIG. 3  schematically illustrating the feeding of a corner bead through one end of the feeder apparatus and drywall mud applied to the bead when it exits at the opposite end of the feeder apparatus; 
       FIG. 5  is a top plan view, partially broken away, of the bottom wall of the hopper with the feeder apparatus beneath; 
       FIG. 6  is a top plan view of an end gate for use in the feeder apparatus; 
       FIG. 7  is a top plan view of a flexible end panel for use with the end gate of  FIG. 6 ; 
       FIG. 8A  is a top perspective view of an inside feeder insert for use in the hopper apparatus of  FIGS. 1 to 5  together with the end gate and end panel of  FIGS. 6 and 7 ; 
       FIG. 8B  is an end elevation view of the feeder insert of  FIG. 8A ; 
       FIG. 8C  is a top plan view of the feeder insert of  FIGS. 8A and 8B ; 
       FIG. 8D  is a cross-sectional view on the lines  8 D— 8 D of  FIG. 8B ; 
       FIG. 9A  is a bottom perspective view of an outside feeder insert for use in the hopper apparatus of  FIGS. 1 to 5 ; 
       FIG. 9B  is an end elevation view of the feeder insert of  FIG. 9A ; 
       FIG. 9C  is a top plan view of the feeder insert of  FIGS. 9A and 9B ; 
       FIG. 10  is a top plan view of an end gate for use with the outside feeder insert of  FIGS. 9A to 9C ; 
       FIG. 11  is a top plan view of a flexible end panel for use with the end gate of  FIG. 10 ; and 
       FIGS. 12 to 17  are end elevation views of alternative feeder inserts with different guide face shapes and angles for guiding different inside and outside corner beads through the feeder apparatus. 
   

   DETAILED DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 to 14  illustrate a hopper apparatus  10  for applying drywall mud or joint compound to corner beads of various shapes and sizes. The basic hopper apparatus is illustrated in  FIGS. 1 to 6 , and comprises a hopper or bucket  12  and a base feeder apparatus  14  secured across the lower wall  15  of the hopper. The hopper is of plastic or similar material and has an open upper end, spaced side walls  16 , 18 , and spaced end walls  20 , 22 . An elongate opening  24  is provided in the lower wall of the hopper for supplying drywall mud from the hopper into the feeder apparatus below. 
   The feeder apparatus  14  includes a base having a generally rectangular feeder tray or channel having a base wall  25  and spaced side walls  26 , and a pair of outer side support walls  28  spaced outwardly on each side of the channel. The side support walls are designed for seating on top of a bucket or a raised stand, as described in my co-pending application entitled “Hopper Stand”, which was filed on even date herewith, the contents of which are incorporated herein by reference. The feeder base is secured to the bottom wall of the bucket via bolts  30  which extend through openings in the bottom wall  15  and aligned openings in the upper rims  32  of the base on each side of the channel. When secured to the hopper, the channel runs between the opposite end walls  20 , 22  of the hopper and beneath the elongate opening  24 . 
   The feeder apparatus further comprises any one of a plurality of feeder inserts, for example any of the feeder inserts illustrated in  FIGS. 8 ,  9  and  12  to  17 , which are designed to be releasably mounted in the base wall  25  of the channel, as well as a pair of matching end gates and a pair of matching flexible end panels. One example of an inside feeder insert  36  and matching end gate  34  and panel  35  is illustrated in FIGS.  6 , 7  and  8 , and the same components are shown mounted on the hopper and feeder channel in  FIGS. 3 and 4 . The feeder insert  36  of  FIGS. 8A to 8D , and the matching end gate  34  and panel  35  are designed for guiding a 90 degree inside corner bead  38  through the feeder apparatus so as to coat a layer  40  of mud onto the outer or convex faces  42  of the bead, as will be described in more detail below. 
   The feeder insert  36  is an elongate member of generally V-shaped or triangular vertical cross section having an apex or ridge  44  extending along its length, the apex forming a relatively sharp, 90 degree angle, as best illustrated in  FIGS. 8A to 8D . The insert has opposite side walls  43  and end walls  47 , and a flat lower face or lower portion  49 . It may be formed of plastic material or the like, and may be a solid rectangular block with a flat lower wall. However, in the exemplary embodiment, in order to save material, the insert is generally hollow, with an open lower face. Transverse webs  45  are provided in the hollow interior of the insert, with at least two of the webs having centrally located, threaded bores  46  at their lower ends. The lower edges of the side walls, end walls, and webs of the insert together define a flat end face  49  of the insert for seating against the flat base wall of the channel. The base wall  25  of the channel has openings  48  positioned for alignment with the bores  46  when the insert is positioned in the channel as shown in  FIGS. 3 and 4 . Fastener screws  50  extend through the openings  48  and into the threaded bores  46  in order to secure the insert  36  in position. Although the insert is secured in the channel via bolts or screws extending through the base of the channel in the illustrated embodiment, other fastener devices may be used in alternative embodiments, such as spring loaded clamping jaws or snap lock formations in the base of the channel itself, or a mating groove and projection arrangement, with the insert sliding in from one end of the channel so as to engage the groove or projection, which may have snap locking devices to releasably hold the insert in position in the channel. 
   Each end gate  34  has a lower edge comprising an indented V-shape  52  of matching angle to the apex  44  of the feeder insert  36 , as best illustrated in  FIGS. 3 and 6 . A pair of rigid end gates  34  are mounted at the opposite end walls  20 , 22  of the hopper such that the V-shaped indent  52  faces downwardly and is located above the apex of the feeder insert. A generally U-shaped mounting bracket  54  is secured to each end wall via bolts  55  (see FIGS.  1 , 2  and  5 ), to form a mounting slot between the outer face of the respective end wall and the bracket. A threaded central bore  56  is provided in each bracket, for engagement with a matching threaded clamping bolt  58  to secure the end gate in a selected position, as indicated in  FIGS. 3 and 4 . A pair of matching, flexible end panels  35  of rubber material or the like are provided for mounting behind the respective end gates. As best illustrated in  FIG. 7 , each flexible end panel  35  has a matching V-shaped indent  60  at each end, which is a sharp angle of 90 degrees matching the indent on the end gate  34 , as well as the angle of the apex  44  of the feeder insert, as indicated in FIGS.  6 , 7  and  8 . The edges of the indents  60  are serrated to form sharp teeth  64  for scraping excess mud off the corner bead, as will be described in more detail below. Drywall mud or joint compound is relatively abrasive, so that the serrated scraper edge of the flexible end panel, which is normally made of rubber or the like, will become worn relatively rapidly. The lifetime of the flexible end panel is doubled by providing a scraper edge at both ends of the panel, such that the panel can simply be inverted when the first end edge becomes worn. 
   Once the selected feeder insert  36  has been installed in the channel of the feeder apparatus, the matching end gates and end panels will be mounted on the opposite end walls of the hopper, by inserting them through the slot formed by each end bracket  54 . The gate and end panel are lowered until they are at the desired spacing from the insert  36 , with the serrated edge  64  of indent  60  projecting below the edge  52  of end gate  34 , as illustrated in  FIGS. 3 and 4 . This forms a V-shaped inlet or outlet feed slot  65  for guiding the corner bead. The bolts  58  are then tightened until the ends of the bolts bear against the end gate to secure the end gate and panel in position. Unlike prior art arrangements, the end panels in this case have no openings or slots to receive a bolt or screw fastener projecting through the mounting bracket, but the bolt ends simply bear against the end panels, providing a greater range of height adjustment. 
   Once the feeder apparatus is assembled with the desired feeder insert, end gate, and end panel which match the shape of the corner bead  38 , the hopper  12  can be filled with drywall mud, and the corner bead  38  is fed into the feeder apparatus through the end slot  65  at end wall  20 , in the direction of the arrow in  FIG. 4 . It will be understood that the assembly of the feeder insert, matching end gate, and matching end panel at the end wall  20  will be identical to that illustrated in  FIGS. 3 and 4  for the end wall  22 . The corner bead will engage over the feeder insert  36  and will be guided along the insert and out through the end slot  65  at the opposite end of the feeder apparatus. At this point, the corner bead can be pulled through the feeder apparatus until a desired length of the bead has been coated. Drywall mud in the hopper will fall down through opening  24  and onto the upwardly facing surfaces  42  of the corner bead. As the corner bead is pulled out through the slot  65  at the opposite end of the feeder apparatus, excess mud will be scraped off by the teeth  64 , leaving a thin layer  40  of drywall mud coating the outer faces of the bead. The corner bead is then ready to be applied to an inside corner joint between adjacent drywall panels. 
   Corner beads are made for both inside corners and outside corners, and in various angles and corner shapes. Inside corner beads are of generally v-shaped, convex cross section, i.e. the outer faces of the beads are designed to be placed against adjacent faces of an inside corner joint. Outside corner beads are of generally v-shaped, concave cross section, i.e. the inner or concave faces of the beads are designed to be placed against adjacent faces of an outside corner joint. In addition to V-shaped inside and outside corner beads, there are also L-shaped or offset corner beads. Both inside and outside corner beads are made in various shapes, sizes and angles to fit against corners of a corresponding variety of shapes and angles. The hopper apparatus  10  will be provided with a corresponding variety of inside and outside feeder inserts and matching end gates and end panels, so that the hopper apparatus can be readily adapted for applying mud to the surfaces of any desired inside or outside corner bead.  FIGS. 9 and 12  to  14  are some examples of different feeder inserts for use with different types of corner beads. 
     FIGS. 9A to 9C  illustrate an outside feeder insert  70  of similar hollow construction to the inside feeder insert  36 , but having an upper face comprising a generally V-shaped indent or channel  72  rather than a V-shaped ridge or protrusion. Again, the insert  70  is an elongate member with opposite end walls  74  and side walls  75 , and an open lower face  77  with a hollow interior, as best illustrated in  FIG. 9A . Transverse strengthening webs  76  are provided across the interior of the insert, and, as in the case of the inside feeder insert  70 , a pair of downwardly facing threaded bores  46  are provided at the center of two of the webs, for securing the insert  70  in the base of the feeder channel with screws  50 . The feeder insert  70  is for a 90 degree bullnose corner bead, and has a rounded or bullnose shape rather than a sharp angled shape. It will be understood that matching end gates and end panels will be provided for use with the 90 degree bullnose outside insert  70 , as illustrated in FIGS.  10  and  11 .  FIG. 10  illustrates an end gate  78  which is similar to end gate  34  of  FIG. 6  but which has a lower end comprising a 90 degree bullnose projection  80  rather than an indent. Similarly,  FIG. 11  illustrates a flexible end panel  82  of rubber or the like which is similar to the end panel  35  of  FIG. 6  but has a 90 degree bullnose projection  84  at each end. When the outside insert  70  is mounted in the channel of the feeder apparatus in place of insert  36 , and an end gate  78  and end panel  82  are secured at each end of the hopper via mounting bracket  54  and bolt  55 , a V-shape inlet and outlet slot will be provided between the opposing faces of the feeder insert and end gate and panel at each end of the feeder apparatus. The slot will be of a shape generally matching that of a 90 degree bullnose outside corner bead. The corner bead can then be fed through the feeder apparatus with its inner or concave faces facing upwardly to be coated with mud, and the mud will be scraped off to a desired layer thickness by the end panel at the exit end of the apparatus. 
     FIGS. 8 and 9  are just two examples of many different possible feeder insert contours, with  FIGS. 12 to 17  illustrating some other examples. It will be understood that, for each of the feeder inserts of  FIGS. 12 to 17 , a corresponding set of end plates and end panels will be provided with mating lower edges, with convex or protruding lower edges for the outside feeder insert and concave or indented lower edges for mating with inside feeder inserts.  FIG. 12  illustrates a 90 degree bullnose inside feeder insert  90 , while  FIG. 13  illustrates a 135 degree bullnose inside feeder insert  92 , and  FIG. 14  illustrates a 135 degree, sharp corner or standard inside feeder insert  94 .  FIG. 15  illustrates a 135 degree sharp corner or standard outside feeder insert  95 , while  FIG. 16  illustrates a 90 degree sharp corner or standard outside feeder insert  96 , and  FIG. 17  illustrates a 135 degree bullnose outside feeder insert  98 . 
   Although all of the feeder inserts are of hollow construction in the illustrated embodiment, it will be understood that they may alternatively be of solid block construction in alternative embodiments, again with threaded bores positioned for alignment with the holes  48  in the base  25  of the channel. The feeder inserts may be formed of plastic, metal, or equivalent materials. Additionally, although the feeder apparatus is secured beneath the lower wall of the hopper in the illustrated embodiment, with an opening in the hopper lower wall for supplying drywall mud or joint compound into the feeder apparatus, it may alternatively extend through the lower portion of the hopper itself, with openings in the opposite end walls of the hopper and the gates and end panels positioned above the openings, while the feeder insert extends a short distance out through the opposite end walls on each side to provide the inlet and outlet slots with the opposing end edges of the end gates and end panels. 
   With the hopper apparatus of this invention, the same feeder apparatus can be modified quickly and easily so that drywall mud can be applied to any type and shape of corner bead, and to both inside and outside corner beads. It will be understood that additional feeder inserts, end plates, and end panels may be provided to cover a wide range of different inside and outside corner bead shapes. All that is required to change to a different type of corner bead is to remove the end gates and panels by loosening one bolt  58  at each end of the hopper, and to remove the current feeder insert by removing two fastener screws  50  from beneath the feeder channel. The new feeder insert is then selected and inserted in the channel and secured in position with the screws, while the matching end gates and panels are secured in the end mounting brackets at the desired position. The height of the end gates and panels may be adjusted for different coating thicknesses. Thus, the hopper apparatus can be modified quickly and easily to accommodate any desired inside or outside corner bead. 
   Although an exemplary embodiment of the invention has been described above by way of example only, it will be understood by those skilled in the field that modifications may be made to the disclosed embodiment without departing from the scope of the invention, which is defined by the appended claims.