Abstract:
A measuring device for measuring the finish height of a container is provided. The measuring device includes a base having a first surface for receiving a rim of a container finish, a support member, a gauge, and a counterweight to balance the measuring device on the finish. The support member is movably attached to the base and adjacent the first surface. A side surface of the support element is in engagement with the container finish. The gauge is attached to the base and a gauge actuator of the gauge is operatively associated with the gauge. The gauge actuator measures a vertical distance between the rim of the finish and a bottom end of the container finish as the gauge actuator moves along the bottom end of the container finish.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to measuring devices and, more particularly, to a device for measuring height of container finishes. 
     2. Description of the Related Art 
     In the manufacture of containers, certain dimensions are required to be within predetermined tolerance limits in order for the containers to function properly. In particular, the upper surface of the container, commonly known as the finish, must be maintained within certain manufacturing tolerances in order to provide adequate cap retention for a liquid tight seal to be formed between the container finish and the container cap. 
     Variations in the dimensions of containers, particularly plastic containers, may occur during molding or trimming operations due to many factors, including differences in the molds used to form the containers, shrinkage of the containers after molding, materials used, curing temperatures, and trimming operations. 
     In order to determine whether produced containers are within predetermined dimensional tolerances, generally a sampling of the containers being produced is measured to determine actual dimensions. This is especially true for the finish height of the containers. For containers which will hold fluids, including consumer products such as detergents and bleaches, it is important that the finish height of the container be within the predetermined dimensional tolerances so that a cap will be retained properly on the finish and leaks will be prevented. 
     The height of a container finish can be determined by manual measurement with a caliper. However, such measurements will include inaccuracies which vary depending on the expertise of a particular user. The inaccuracies occur due to the manual placement of the caliper, variations in the manual force applied to the caliper, and the caliper blades cutting into the soft material of the bottle finish, such as when the bottle is made of a blown thermoplastic. If the calipers are tilted just a slight amount, the reading will fluctuate. Therefore, the measurements are very difficult to repeat. 
     As an alternative to manual measurement with a caliper, container finishes may also be measured by an optical comparator. The optical comparator takes an enlarged shadow-graph of the bottle finish to provide a highly accurate measurement of the finish diameter. However, optical comparators are quite expensive and are generally not available at the location where the bottles are made. Therefore, when using an optical comparator, bottles often must be shipped to a laboratory for measurement, providing a very delayed determination of dimensional tolerances. As a result, a large number of reject bottles may be made before the error is corrected by adjustments to the blow molding and/or trimming processes. 
     In view of the above drawbacks of the known methods for measuring height of a container finish, it would be desirable to provide a measuring device for accurately measuring the height of a container finish rapidly and with minimal user error. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, a measuring device for measuring a finish height of a container includes a base comprising a first surface for receiving a rim of a container finish, a support member movably attached to the base, a gauge, and a counterweight attached to the base. The support member is attached adjacent the first surface. A side surface of the support member is in engagement with the container finish. A gauge actuator is operatively associated with the gauge. The gauge actuator measures a vertical distance between the rim of the finish and a bottom end of the container finish as the gauge actuator moves along the bottom end of the container finish. Further, the counterweight balances the measuring device on the container finish. 
     A process for measuring a height of a container finish comprises the steps of positioning a first surface of a measuring device on an upper end of the container finish; moving a support member of the measuring device in engagement with a side wall of the container finish; contacting a gauge actuator with a lower end of the container finish wherein the gauge actuator is operatively connected to a gauge having a display; and moving the gauge actuator along the lower end of the container finish so as to measure a vertical distance between the upper end of the container finish and the bottom end of the container finish. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a fluid container having a finish portion; 
     FIG. 2A is a detail schematic view of the finish portion shown in FIG. 1; 
     FIG. 2B is a top view of the finish portion shown in FIG. 2A; 
     FIG. 3A is a side view of the gauge system of the present invention that is mounted on a bottle finish for inspection; 
     FIG. 3B is a cross-sectional view of the gauge system shown in FIG. 3A; 
     FIG. 4 is a bottom view of the gauge system of the present invention shown in FIG. 3A; and 
     FIG. 5 is a perspective view of the gauge system of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made to the drawings wherein like numerals refer to like parts throughout. FIG. 1 illustrates an exemplary plastic container  100 , such as a bottle, to hold fluids such as detergent or bleach, or the like. The bottle may be manufactured by combining a first half  102  and a second half  104  through a molding part line  106  using well known processes in the art of container manufacturing. In the preferred embodiment, the bottle may be made of high-density polyethylene. The bottle  100  may comprise a top portion  108  with a bottom portion  110 , and a body  112  of the bottle  100  is configured to retain fluids. A finish portion  114  formed as an opening shaped as a neck or a short tube where the fluids are filled into or dispensed out of the bottle  100 . 
     As shown in FIG. 2A, the finish portion  114  of the bottle  100  may be integrally connected to the body  112  through a shoulder portion  116  or shelf at a lower end  118  of the finish  114 . In this embodiment, the shoulder portion  116  forms a lower reference line of the finish height. An outer circumferential side wall  120  extends between the lower end  118  and an upper end  122  of the finish  114 . On the side wall  120 , the bottle finish  114  may have threads  124  for retaining a cap (not shown). 
     As shown in FIG. 2B, in a top view of the bottle  100 , the finish  114  may also comprise an upper surface  126  or rim and inner circumferential side wall  128  defining a finish opening  130 . In this embodiment, the upper surface forms an upper reference line of the finish height. Thus, the distance between the shoulder  116  and the upper surface  126  of the finish  114  is defined as the finish height. 
     As previously mentioned, for containers which will hold fluids, including consumer products such as detergents and bleaches, it is important that the finish height of the container be within predetermined dimensional tolerances so that a cap will be retained properly on the finish and leaks will be prevented. Therefore, the finish height must be routinely inspected to determine whether the distance between the upper surface  126  and the shoulder  116  is in predetermined manufacturing limits. A gauge system  200  of the present invention provides an effective tool to facilitate this inspection process. 
     FIGS. 3A and 3B show the gauge system  200  of the present invention which is placed on the finish portion  114  of the bottle  100  during the measurement process. The gauge system  200  of the present invention may comprise a base  202 , a gauge  204  and a counterweight  206 . The counterweight  206  comprises a cylindrical weight member that allows the system  200  to be balanced on the finish portion  114 . The base comprises a first side  208 , a second side  210 , a top surface  212  and a bottom surface  214 . The counterweight  206  is attached to and extends from the second side  210  on which the gauge  204  is positioned. 
     The gauge system  200  of the present invention can conveniently be custom manufactured for measuring the heights of various bottle sizes with differing finish opening diameters. In this embodiment the gauge system  200  is adapted to operate on bottles having 33 and 38 millimeter finish diameters (FIG.  5 ). The gauge  200  may weight 855 grams. An exemplary gauge  200  may have 6.5″ length and 2.75″ width. The base  202  may have a 1″ height, and the overall height (including top of gauge  204 ) may be 5.25″. All machined pieces are made from anodized aluminum except support member  242  made from delrin plastic, and the thumb screw is made of brass. 
     During the measuring process, a first region  216  of the bottom surface  214  is placed on the finish surface  126  of the finish  114 . A gauge actuator  218  of the gauge  204  is then extended to contact the shoulder portion  116  of the bottle  100 , and next the gauge system  200  is rotated 360° to record the finish height. As the gauge system  200  is rotated, the gauge  204  records the minimum and maximum heights of the finish  114  based on the vertical displacement of the gauge actuator  218   
     As illustrated in FIG. 3A, the gauge  204  comprises a front side  220  having a digital display  222 , and control buttons  224  and  226  to control the gauge  204 . The control buttons  224  and  226  may serve to perform a variety of functions to control the gauge  204 , such as turning on and turning off the gauge  204 , setting the zero readout, as well as changing the measurement mode between different units, for example between millimeters and inches. The gauge  204  may have a memory to hold the height measurements as it is rotated. However, measurements may be read off the digital display  228  by a user as well. The gauge  204  may be available from the Fred V Fowler Co, Newton, Mass. and sold under the brand name Ultra Digit Mark V. 
     As shown in FIG. 3B in cross-section, the gauge actuator  218  may comprise a gauge rod  230  extending through a hole  232  formed in the body of the base  202 , and a contact member  234 , preferably a disc shaped member, having an edge  236  to engage or contact the shoulder portion  116  of the bottle  100 , as in the manner shown in FIGS. 3A and 3B. The contact member  234  may be perpendicularly secured to a first end of the gauge rod  230 . The second end of the gauge rod  230  has a tip  238  for manually controlling the vertical position of the gauge rod  230  As an example, the diameter of the contact member may be ⅝″ and the diameter of the rod  230  may be {fraction (5/32)}″. Overall gauge weight may be 130 grams. The rod  230  and the contact member  234  may be made of hardened and ground stainless steel. 
     Referring to now to FIGS. 3A and 3B, the first side  208  of the base  202  comprises an inner cavity  240  to movably retain a support member  242  on a cavity floor  244 . The cavity floor  244  is a lateral extension of the bottom surface  214  and is in the plane of the bottom surface  214 . During the calibration of the gauge system  200 , the support member  242  is contacted with the threads on the finish  114  thereby confining the finish  114  between the contact member  218  and the support member  242 . This, in turn, prevents lateral movement of the gauge system  200  but allows rotational movement of the gauge system  200  during the measurements. As will be described in detail below, the support member  242  may be moved into a first position to permit the gauge system  200  to operate on a 38 millimeter finish or it may be moved into a second position to permit the gauge system  200  to operate on a 33 millimeter finish. 
     The support member  242  may be moved in the cavity  240  and on the cavity floor  244  by moving a button  246  or a thumb nut which is placed on the top surface  212  of the base  202 . The thumb nut  246  is connected to the support member  242  by a pin  248 . The pin  248  is placed through a second hole  250  formed through the body of the base  204 . The second hole  250  may be a rectangular hole allowing the button  246  to switch between the two predetermined positions and hence moving the support member  242  between these predetermined positions. Once the position is selected, the thumb nut  246  may be temporarily locked at that position by tightening the thumb nut  246 . 
     As shown in FIG. 4 in a bottom view, the cavity  240  is surrounded by a rectangular-U shaped side wall  252  or lip projecting perpendicularly from the bottom surface  214  and extending along an outer wall  254  of the first side  208  of the base  202 . The support member  242  is generally rectangular in shape and in engagement with the correspondingly shaped side wall  252 . Depending on the diameter of the finish being tested, the support member  242  may be laterally moved in the cavity  240  in a first direction  258  and in a second direction  260  by moving the button  246  (FIGS. 3A-3B and  5 ). A rear end  262  of the support member  242  contacts a rear wall portion  264  of the side wall  252  when the support member is moved in the first direction  258  and into the first position as shown with dashed lines. A front end  266  of the support member  242  comprises a V-shaped recess  268  having side walls  270  to contact the finish  114  when the first area  216  of the gauge  200  is placed on top of the finish  114 . In this respect, when the larger diameter finish is measured (i.e., the finish diameter of 38 millimeters), the support member  242  is moved in the first direction  258  to provide sufficient space on the first region  216 . Accordingly, when the smaller diameter finish is measured (i.e., finish diameter of 33 millimeters), the support member  242  is moved in the second direction  260  to provide enough space on the first region  216  for the finish. 
     As illustrated in FIG. 5, the gauge system  200  of the present invention may also comprise two reference lines  272 ,  274  or scores positioned on a reference surface  276  of the base  202 . During a test, and depending on the finish diameter of a bottle, one of the reference lines is aligned with a common feature that is on the bottles. This common feature or reference feature may be the part line  106  (FIG.  1 ). This reference feature allows an operator to visually determine where the height measurement is begun and terminated. As an example, the reference lines may also include numerical markings. 
     The calibration and measurement of the finish height with the gauge system  200  may be exemplified with reference to FIG.  5 . As shown, a user may grasp the entire gauge system  200  and place it on the bottle finish  114  as in the manner described above. Then, the gauge  204  is calibrated by turning it on by the on/off button  224 . Next, the gauge  204  is zeroed with the zeroing button  224  while retracting and holding the contact disc  234  against the bottom surface  214  of the base  202 , and then releasing the contact disc  234 . After calibrating the gauge  204 , the measurement process is initiated. Accordingly, the thumb nut  246  is loosened and aligned with the desired finish diameter. The thumb nut  246  is tightened at the desired diameter which is, in this example, 33 millimeters. The contact disc  234  is then placed on the shoulder  116  of the left side of the finish  114  when viewed from FIG.  5 . The part line  106  on the bottle  100  is then aligned with the 33 millimeter reference line  272 . At this point, the bottle  100  is rotated counter clockwise while holding the finish against the gauge system  200 . The bottle  100  is rotated and again aligned with the reference line  272 . As it will be appreciated, the measurement can alternatively be done by holding the bottle and rotating the gauge system  200 . The digital display  222  will display the height of the finish  114  on the display  222 . After completing the measurement, the on/off button  224  is pressed and the gauge system  200  is turned off. The gauge system of the present invention may have a measurement range of 0-1″ with 0.00005″ accuracy, 0.0002″ repeatability and 0.0001″ resolution. 
     It should be understood, of course, that the foregoing relates to preferred embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.