Abstract:
An inspection station for checking the correct placement of a lid on a filled plastic container that is traveling on a conveyor that includes: a detector plate assembly ( 16 ) that has a flat surface ( 32 ) and an inclined surface ( 44 ); a support assembly ( 18 ); a mounting assembly ( 22 ) for attaching the detector plate assembly ( 16 ) to the support assembly ( 18 ) for holding the flat surface ( 32 ) in a predetermined parallel relationship with a top or conveying surface ( 30 ) of the conveyor ( 12 ) while simultaneously allowing vertical displacement thereof; a first sensor ( 54 ) for detecting the presence of a plastic container ( 20 ) to be checked or inspected; a second sensor ( 56 ) for sending a signal when the detector plate is within a selected range of vertical displacement. In operation the plastic container traveling horizontally on the conveyor first contacts the inclined surface thereby vertically displacing the detector plate assembly ( 16 ) sufficiently for subsequently allowing the flat surface ( 32 ) to contact a top surface of the plastic container for allowing the second sensor ( 56 ) to cooperate with a notched bar ( 58 ) to determine whether the vertical displacement is outside of the selected range.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    With regard to the classification of art, this invention is believed to be found in the general class entitled Package Making and more particularly to those subclasses pertaining to an apparatus for checking the placement of lids on pails.  
           [0003]    2. Description of Related Art  
           [0004]    Lid checking or detecting apparatus are well known in the prior art. Some examples of the known prior art disclosing lid checking or detecting devices are: U.S. Pat. No. 2,883,810 that issued to Gieskieng on Apr. 28, 1959; U.S. Pat. No. 3,411,621 that issued to Gerben on Nov. 19, 1968; U.S. Pat. No. 3,460,314 that issued to Keas on Aug. 12, 1969; U.S. Pat. No. 3,477,197 that issued to Budz on Nov. 11, 1969; U.S. Pat. No. 4,773,204 that issued to Rydstrom on Sep. 27, 1988; U.S. Pat. No. 4,872,300 that issued to Luke on Oct. 10, 1989; U.S. Pat. No. 4,724,384 that issued to Castovilly et al on Feb. 9, 1988; U.S. Pat. No. 4,852,745 that issued to Lemaire et al on Aug. 1, 1989; and U.S. Pat. No. 5,438,814 that issued to Lovett et al on Aug. 8, 1995. It has ben determined that there is still a need for a lid checking and detecting apparatus that simultaneously detects the existence of a lid and/or the correct seating of the lid on a pail or container. It has also been determined that this needed apparatus must also operate when and while the pail or container is moving continuously on an associated conveyor and at package line speeds. The present invention solves the above identified needs while checking all seating conditions along the peripheral edge of the pail or container.  
         SUMMARY OF THE INVENTION  
         [0005]    One embodiment of the present invention may be briefly described as: an apparatus for checking the correct placement of a lid on a filled plastic container that is traveling on a conveyor that includes: a). a detector plate assembly that has a flat surface and an inclined surface; b) a support assembly c) a means for mounting the detector plate assembly to the support assembly whereby the flat surface of the detector plate is held in a predetermined parallel relationship with a top or conveying surface of the conveyor while simultaneously allowing vertical displacement thereof; d) a first sensor for detecting the presence of a plastic container to be checked or inspected; a second sensor for sending a signal when the detector plate is within a selected range of vertical displacement; and wherein the plastic container traveling horizontally on the conveyor first contacts the inclined surface thereby vertically displacing the detector plate assembly sufficiently for subsequently allowing the flat surface to contact a top surface of the plastic container and the second sensor also determines and sends a different signal whether the vertical displacement is outside the selected range .  
           [0006]    The present invention may also include the following additional features individually or in combination: 1) a detector plate assembly having a flat surface that is momentarily overlapping at least 80 percent of the area interior of the peripheral outline of the top surface of the container as and when the container is traveling in a horizontal direction on the conveyor; 2) the means for mounting the detector plate to the support assembly includes a pair of elongated shafts that are selectively spaced in a predetermined parallel relationship on the support assembly; 3) the support assembly includes a pair of low friction ball bushing assemblies that are selectively spaced in a predetermined parallel relationship on the detector plate assembly for vertical movement on the pair of elongated shafts, 4) at least one adjusting assembly for selectively aligning the flat surface with the top surface of the plastic container prior to their contact; 5) the second sensor being a proximity switch that is mounted and carried on the adjusting assembly for sending the signal by detecting a notched portion of the detector plate assembly.  
           [0007]    In addition to the above summary, the following disclosure is intended to be detailed to insure adequacy and aid in the understanding of the invention. However, this disclosure, showing particular embodiments of the invention, is not intended to describe each new inventive concept that may arise. These specific embodiments have been chosen to show at least one preferred or best mode for an apparatus of the present invention. These specific embodiments, as shown in the accompanying drawings, may also include diagrammatic symbols for the purpose of illustration and understanding. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0008]    [0008]FIG. 1 represents a front elevation of a an apparatus for checking the correct placement of a lid on a filled plastic container traveling on a conveyor  
         [0009]    [0009]FIG. 2 represents a right side elevation thereof.  
         [0010]    [0010]FIG. 3 represents a top elevation thereof, this view being shown in an enlarged scale.  
         [0011]    [0011]FIG. 4 represents an isolated view of the second sensor, this view is taken in the same direction as FIG. 2 and in an enlarged scale.  
         [0012]    [0012]FIG. 5 represents an isolated view of the second sensor, this view is taken in the same direction as FIG. 4 and showing a no lid condition.  
         [0013]    [0013]FIG. 6 represents an isolated view of the second sensor, this view is taken in the same direction as FIG. 4 and showing either a high, or cocked, or unseated lid condition. 
     
    
       [0014]    In the following description and in the appended claims, various details are identified by specific names for convenience. These names are intended to be generic in their application while differentiating between the various components. The corresponding reference numbers refer to like members throughout the several figures of the drawing.  
         [0015]    The drawings accompanying and forming a part of this specification disclose details of construction for the sole purpose of explanation. It is to be understood that structural details may be modified without departing from the concept and principles of the invention as claimed. This invention may be incorporated into other structural forms than shown.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    Referring to the drawings FIGS. 1 through 6, an apparatus or assembly for checking the correct placement of a lid on a filled plastic container is generally identified as  10 . The assembly  10  is removable attached to a conveyor  12  by way of a plurality of threaded fasteners  14 . The assembly  10  includes a detector plate assembly  16  and at least one support assembly  18 . It has been found that mounting the assembly  10  to the conveyor  12  in cantilever fashion, as more clearly seen in FIG. 2, provides an arrangement for allowing easy removal of a container  20  if and when necessary. Of course the support assembly  18  must be sufficiently sized and shaped for supporting the anticipated cantilever loading. One non-limiting example of a support assembly  18  is a channel shaped upright member  24  that is removably attached to the side rail  26  of the conveyor  12 . In this example, spacer blocks  28  may be required for positioning a center of the detector plate assembly  18  over the center of the conveyor. However it is to be noted that the assembly  10  may also include front and rear support assemblies  18  that are arranged for straddling the conveyor  12 .  
         [0017]    The assembly  10  further includes a means for the mounting, identified as  22 . The means for mounting  22  attaches the detector plate assembly  16  to the support assembly  18 . This means for the mounting  22  must provide vertical guidance for the detector plate assembly  16  during any movement and/or adjustment in the direction of arrow A. The vertical guidance must maintain a predetermined parallelism in two directions between the conveying surface  30  of the conveyor  12  and a flat surface  32  of the detector plate assembly  16  during any movement in the direction of arrow A. One direction of the predetermined parallelism is in the direction of container travel that is depicted by arrow B and a second direction that is transverse to arrow B and parallel to the axis of conveyor rollers. One non-limiting example of a means for mounting  22  is a pair of elongated shafts  34  that are selectively spaced and supported in a predetermined parallel relationship on the channel member  24  of the support assembly  18 . A pair of end blocks  38  supports each end of the elongated shafts  34 . The detector plate assembly  16  is guided on the elongated shafts  34  by commercially available linear anti-friction ball bushings  40  that are housed in bushing blocks  42 . In this example, it is preferred that the elongated shafts  34  be of the precision type and have a hardened surface for resisting premature wear.  
         [0018]    The detector plate assembly  16  further includes an inclined surface or ramp  44 . The connection of the inclined surface or ramp  44  to the flat surface  32  should be a smooth transition absent any raised welds and the like. The inclined surface  44  is formed at a predetermined included angle C with respect to the flat surface  32 . One non-limiting example of a range for the included angle C is between 25 and 35 arc degrees. The detector plate assembly  16  preferably is made of a welded sheet metal construction that includes; an end gusset  46 , at least one intermediate gusset  48 , a front flange  50 , a rear flange  52 , and an end flange  53  that must be of sufficient size and thickness for minimizing any deflection thereof during use while also minimizing it&#39;s weight.  
         [0019]    The assembly  10  includes a first sensor  54  and second sensor  56 . The first sensor  54  is employed for sensing a container  20  or pail that is to be checked for the proper placement and seating of its lid. One non-limiting example of a first sensor  54  is a commercially available photocell. The second sensor  56  is employed for detecting the proper placement of the lid on the container  20 .  
         [0020]    When the assembly  10  of the present invention is to be used with containers having a fixed or constant height, the first sensor  54  and the second sensor  56  may be removably attached to the channel member  24  by and with a common bracket member  57  One non-limiting example of a second sensor  56  is a commercially available proximity switch that senses a metallic object and then sends a signal. In this non-limiting example the second sensor  56  senses the presence of an elongated metallic bar  58  that is removably and adjustably mounted to the rear flange  52  of the detector plate assembly  16 . The elongated metallic bar  58  has a notched area  60  formed therein. The notched area  60  should be larger than the diameter of the sensing face of the second sensor by a predetermined amount. The elongated metallic bar  58  is attached to the rear flange  52  by at least two elongated through apertures  62  or slotted holes for allowing the proper adjustment of the notched area  60  with respect to the second sensor  56 . The adjustment will be discussed below.  
         [0021]    In a preferred non-limiting arrangement, the present invention is adapted for handling a range of heights of the container  20 . In this preferred arrangement the assembly  10  of the present invention further includes an adjusting assembly  64 . One non-limiting example for an adjusting assembly  64  includes a jacking screw  66  that is journalled in pair of bearing blocks  68 . A jacking block  70  is sized and threaded for vertical advancement as and when the jacking screw  66  is turned in a clockwise or counter-clockwise direction by handle  72 . It is preferred that the adjusting assembly  64  include a locking device  74  for maintaining a desired set position during operation of the packaging line. A stop block  76  is mounted to the detector plate assembly  16 . The stop block  76  rests on top of the jacking block  70  so that a desired lower limit is provided for the detector plate assembly  16 . This arrangement allows the detector plate assembly  16  to move upwardly a predetermined vertical distance when a container  20  is passing thereunder and in sliding abutment with the flat surface  32 . The operation of this adjusting assembly will be also discussed below.  
         [0022]    The set up of the assembly  10  having an adjusting assembly  64  includes the steps of: First, placing a container  20  having a properly placed lid seated thereon on the conveying surface of a stopped conveyor  12  so that the flat surface  32  is slightly below the raised portions of the top surface  78  of container  20 ; Second, manually lifting the detector plate assembly  16  and placing the container  20  between the conveying surface of the stopped conveyor  20  and the detector plate assembly  16  so that a least 80 percent of the area within the perimeter outline of a top surface  78  of the container  20  and the area of the flat surface  32  are overlapping and while having any portions of the top surface  78  to be checked abutting the flat surface  32 ; Third, rotating the handle  72  of the adjusting assembly so that the center axis of the second sensor  56  is aligned with the center of the notched area  60  of the elongated metallic bar  58 , more clearly seen in FIG. 4, so that a change of signal occurs at the switching contacts of the second sensor  56 . Fourth, locking the adjusting assembly  64  at the desired position by tightening the locking device  74 .  
         [0023]    In operation, the containers or pails  20  travel on the conveying surface  30  of the conveyor  12  in a substantially horizontal direction, as depicted by arrow B. A leading edge of the top surface  78  of the container  20  contacts the inclined surface  44  of the detector plate assembly  16 . This contact creates a cam-like action that lifts the detector plate assembly  16 , in the direction of arrow A, sufficiently to allow the container to pass under the flat surface  32  while maintaining a parallel relationship with the conveying surface  30  of the conveyor  12 . It is preferred that the area of the flat surface  32  and at least 80 percent of area with the peripheral outline of the top surface  78  momentarily overlap when and while the container is continuously moving thereunder. As the first sensor  54  detects the container  20 , the control circuit begins to look for a signal from the second sensor  56 . The second sensor  56  will provide an “ACCEPT” signal if the lid is proper seated on the container  20  and centered with the notched area  60 , more clearly seen in FIG. 4, The second sensor will send a “REJECT” signal when either no lid is present, more clearly seen in FIGS. 2 and 5 or if the lid in not properly seated on the container  20 , more clearly seen in FIG. 6. The present invention will also detect a lid that is either cocked or a lid that has only a small portion that is not seated properly. It has been found that the present invention will reliably detect lid height variations that are as little as 1.6 mm (0.063 in.) beyond the “ACCEPT” range. The “REJECT” signal is a result of the second sensor detecting the raised surface  80  on either side of the notched area  60  of the elongated metallic bar  58 . The output signal from second sensor  56  may be either connected to an alarm device or used by a packing line control circuit sequencer for removal or inspection of any rejected containers.  
         [0024]    The steps for the set-up of the present invention when the containers to be inspected are always the same height include: First, manually lifting the detector plate assembly  16  and placing the container  20  between the conveying surface of the stopped conveyor  20  and the detector plate assembly  16  so that a least 80 percent of the area of a top surface  78  of the container  20  and the area of the flat surface  32  are overlapping and with the raised portions of the top surface  78  abutting the flat surface  32 ; Second, loosening the fasteners  82  that mount the elongated metallic bar  58 ; Third, slide the elongated bar  58  along the elongated apertures  62  so that the second sensor  56  and the notched area  60  are aligned as discussed above; Fourth, tighten the fasteners  82  so that the elongated bar  58  is locked in place. The operation thereafter is similar to that described above.  
         [0025]    It is anticipated that sensing means other than the particular type described in connection with the first sensor  54  and the second sensor  56  may be used. It is also anticipated that the mounting locations for the first sensor  54  and the second sensor may be altered to suit a particular application.  
         [0026]    It is to be noted that the present invention may also be used with intermittent motion or indexing conveyors.  
         [0027]    Directional terms such as “front”, “back”, “in”, “out”, “downward”, “upper”, “lower” and the like may have been used in the description. These terms are applicable to the embodiments shown and described in conjunction with the drawings. These terms are merely used for the purpose of description in connection with the drawings and do not necessarily apply to the position in which the present invention may be used.  
         [0028]    While these particular embodiments of the present invention have been shown and described, it is to be understood that the invention is not limited thereto and protection is sought to the broadest extent that the prior art allows.