Abstract:
A system for measuring a profile of an object comprising a source creating a beam of electromagnetic energy. An electromagnetic beam receiver spaced from the source for processing an output signal proportional to the girth of the object being measured. A platform for providing rotational and vertical movement of the object being measured causing the object to obstruct a portion of the electromagnetic beam generated by the source. A processor for processing the output signal from the electromagnetic beam receiver to form a composite profile of the object measured.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/457,140 filed Mar. 24, 2003. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to measuring systems and more particularly to a laser system for measuring the profile of an object such as a container, for example.  
         [0004]     2. Description of the Prior Art  
         [0005]     The prior art systems have commonly included measuring the profile of an object utilizing manually operated micrometers. This typically requires a person to make manual measurements about a perimeter of the object, read the micrometer (whether digital or inscribed), and record the measurement data accordingly. A user then manually enters the measurement data into a computer. While such systems achieve the measurement objectives, the systems consumed rather substantial quantities of time and required manual dexterity.  
       SUMMARY OF THE INVENTION  
       [0006]     It is an object of the present invention to produce a system for measuring the profile of an object which is automatic.  
         [0007]     Another object of the invention is to produce a system for measuring the profile of a plurality of objects wherein the plurality of object to be measured may be delivered and removed from the system automatically.  
         [0008]     Another object of the invention is to produce a system for measuring the profile of an object utilizing a laser micrometer.  
         [0009]     Still another object of the invention is to produce a system for measuring the profile of an object and determine the displacement of the top of the object from a given point and the base thereof.  
         [0010]     Still another object of the invention is to produce a system for measuring the profile of the threaded finish portion of a container adapted to receive a threaded closure.  
         [0011]     The above as well as other object of the invention may be achieved by a system for measuring the profile of an object comprising a source creating a beam of electromagnetic energy. An electromagnetic beam receiver spaced from the source processes an output signal proportional to the girth of the object being measured. A platform for providing rotational and vertical movement of the object being measured causes the object to obstruct a portion of the electromagnetic beam generated by the source. A processor for processing the output signal from the electromagnetic beam receiver forms a composite profile of the object measured. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     Other objects and advantages of the invention will become manifest to those skilled in the art from reading the following detailed description of an embodiment of the invention when considered in the light of the accompanying drawings, in which:  
         [0013]      FIG. 1  is a block diagram illustrating a laser measurement system of the present invention.  
         [0014]      FIG. 2  is a schematic front view of a laser measurement system according to a first embodiment of the present invention; and  
         [0015]      FIG. 3  is a schematic top view of a portion of the laser measurement system illustrated in  FIG. 2 .  
         [0016]      FIG. 4  is a schematic front view of a laser measurement system profiling an object.  
         [0017]      FIG. 5  is a schematic top view of a portion of the laser measurement system illustrated in  FIG. 4 .  
         [0018]      FIG. 6  is a schematic side view of a vertical and rotational motion unit according to the present invention.  
         [0019]      FIG. 7  is a perspective view of a carousel unit according to the present invention.  
         [0020]      FIG. 8  is a flowchart illustrating a method for profiling a plurality of objects using a laser measurement system. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]     Referring to the drawings, there is illustrated a measuring system for measuring the outer profile of an object. It is has been surprisingly determined that the system is particularly useful for providing a quick and simple way of obtaining the profile parameters of PET bottles, filled or empty.  
         [0022]     The system illustrated in  FIG. 1  includes a block diagram of a laser measurement system. The laser measurement system includes a measuring device  10  which is a Takikawa Laser Micrometer (Model LDM-305H), purchased through DAS Distribution, Inc. (www.dasdistribution.com). The measuring device  10  includes a laser transmitter unit  18  and a laser receiving unit  20 . The laser transmitter unit  18  (i.e., source) transmits a primary beam of electromagnetic energy in the direction of the laser receiving unit  20  for profiling an object disposed within the primary electromagnetic beam. A processor  21  within the measuring device  10  processes measurement data received from the laser receiving device  20  and transmits the measurement data to a computer  16  for storage in a file. The measuring device  10  is mechanically coupled to a platform stand  26 . The platform stand  26  supports the measuring device  10 . A motion unit  14  is mechanically coupled to the platform stand  26  and provides vertical and rotational displacement of an object. The motion unit  14  includes a rotational platform  12  for supporting and rotating the object and a vertical drive device  15  for upwardly or downwardly moving the object positioned on a rotational platform  12 . The rotational platform  12  is rotationally coupled outward from the vertical drive device  15  for supporting and rotating the object within the primary electromagnetic beam about a vertical axis. The rotational platform  12  is rotatable 360° for profiling the entire circumference of the object in a respective plane.  
         [0023]      FIG. 2  and  FIG. 3  illustrate a schematic front view and top view of the laser measurement system, respectively. The platform stand  26  is affixed to a bottom surface of the measuring device  10  for supporting the measuring device  10 . The measuring device  10  includes the transmitter unit  18  disposed on a first side of the measuring device  10  and a receiving unit  20  disposed on a second side of the measuring device  10 . The transmitter unit  18  and the receiving unit  20  are spaced a predetermined distance apart from one another. The vertical drive unit  15  and the rotational platform  12  are disposed therebetween. The transmitting unit  18  transmits a 7″ wide electromagnetic laser beam  22  (i.e., primary) in the direction of the receiving unit  20  for profiling the object. The electromagnetic laser beam  22  is a class II laser light source from a visible red semiconductor laser (670 nm) with a 1 mW maximum output. In alternative embodiments, other laser light sources may be utilized.  
         [0024]     The measuring device  10  includes the processor  21  (shown in  FIG. 1 ) for maintaining measurement data polled from a profiled object. The processor  21  communicates with the computer  16  via a communication line  24  (e.g., RS232 cable) for transmitting measurement data between the processor  21  and the computer  16 . Alternatively, other types communication lines may be used such as a USB cable or firewire.  
         [0025]      FIG. 4  illustrates the object disposed within the laser measurement system for profiling. A plastic container  28  is disposed on the rotational platform  12 . An advantage of the present invention is that the laser measurement system may profile the plastic container  28  whether filled, empty, or partially filled with a substance. The plastic container  28  may be measured prior to and after the substance has been added. This allows for statistical quality control and inspection of the plastic container  28 . After the plastic container  28  is positioned on the rotational platform  12 , depending on its initial position, the vertical drive unit  15  is indexed upward or downward to an initial measurement position. Software is provided for transmitting control signals to the motion unit  14  for controlling the motion of the vertical drive device  15 . The software also provides control signals for controlling the rotary motion of the rotational platform  12 . As a result, the software raises, lowers, and rotates the plastic container  28  to align a respective plane of the plastic container  28  with the electromagnetic laser beam  22 .  
         [0026]     The vertical drive device  15  utilizes a linear screw drive to produce the vertical displacement. The linear screw drive is rotated either clockwise or counterclockwise under software control to move the rotational platform  12  upward or downward.  
         [0027]     When the plastic container  28  is moved between the transmitter unit  18  and the receiving unit  20 , the electromagnetic laser beam  22  is obstructed thereby reducing it to two smaller beams (i.e., secondary beams). That is, the electromagnetic laser beam  22  will be split into two smaller laser beams as seen by the receiving unit  20 .  
         [0028]      FIG. 5  illustrates the splitting of the electromagnetic laser beam  22 . A dark area  30  is shown generally indicating a region where no laser radiation is received by the receiving unit  20  as a result of the plastic container  28  blocking the electromagnetic laser beam  22 . A first smaller beam  32  includes a portion of the electromagnetic laser beam received by the receiving unit  20  that is unobstructed by the plastic container  28 . The width of the first smaller beam  32  is dependent on the obstruction of the plastic container  28  and the passage of the portion of the unobstructed electromagnetic beam from a first exterior surface of the plastic container  28  to a first adjacent edge of the electromagnetic laser beam  22 . Likewise, a second smaller beam  34  received by the laser receiving unit  20  is a portion of the electromagnetic laser beam that is unobstructed by the plastic container  28 . The width of the second smaller beam  34  is dependent on the obstruction of the plastic container  28  and the passage of the portion of the unobstructed electromagnetic laser beam from a second exterior surface (i.e., 180° opposite the first exterior surface) to a second adjacent edge of the electromagnetic laser beam  22 . The resulting signals are received and measured by the receiving unit  20 . These resulting signals include a first smaller beam  32  having a first width, a void of a darkened area  30 , and a second smaller beam  34  having a second width. The profile of a respective plane of the plastic container  28  (i.e., girth) is directly proportional to the void of the darkened area  30 . The profile of a respective plane of the plastic container  28  may be determined by directly measuring the void of the darkened area  30 . Alternatively, the profile a respective plane of the plastic container  28  may be determined by the difference between the width of the electromagnetic laser beam  22  and the first and second smaller beams  32  and  34  received by the receiving unit  20 .  
         [0029]     The plastic container  28  may also be rotated by the rotational platform  12  for profiling at least one view within a respective plane. The rotational platform  12  includes a rotational drive device  17  for rotating the plastic container  28  supported by the rotational platform  12 , as shown in  FIG. 6 . In the preferred embodiment, the rotational drive device  17  includes a gear driven mechanism. A motor (such as a stepper motor) may be used to drive the gears of the rotational drive unit. In another embodiment, a belt driven mechanism may be utilized to rotate the rotational platform  12 . Position encoders may also be utilized for determining the rotational position of the rotational platform at any given degree of rotation. As a result, the plastic container  28  may be moved vertically to profile any respective plane and rotationally to profile a respective view.  
         [0030]     At any point, the software can poll the position of the vertical drive unit  15  and the rotational platform  12  relative to the plane of the electromagnetic laser beam  22  and retrieve a resulting data measurement. By entering minimal initial information to the software program such as heights at which to measure, incremental degrees by which to rotate the object, and a mode in which to scan (see Bulge/Pinch infra), an object specific program can be built in a matter of seconds. After the initial information is entered, the plastic container  28  is placed on the rotational platform  12  and a scan operation is initiated. The measuring device  10  will profile the plastic container  28  given the operating parameters of the initial information entered and transmit the measurement data to a file stored in the computer  16  via the communication line  24 . To scan a second plastic container of an identical size and shape, the first plastic container  28  is removed from the rotational platform  12  and the second plastic container is positioned on the rotational platform  12 . The scan operation is thereafter initiated. Measurement data retrieved from each plastic container profiled is stored in one or more files in the computer  16 .  
         [0031]     The motion unit  14  is positioned relative to the measuring device  10  such that an upper bounds of the motion unit  14  places the top support surface of the rotational platform  12  flush with the plane of the electromagnetic laser beam  22 . This is considered the zero reference point for all vertical motion measurements with respect to objects of this same form. Any polling by the computer  16  for position and measurement data are relative to the zero reference point.  
         [0032]     In addition to measuring an object at a specific height and degree requested by the user, the measuring device  10  can scan a region of the object, search for the maximum (bulge) or minimum (pinch) diameter measurement in that area, and then take measurement data around the object at that location.  
         [0033]     This is advantageous to users tracking changes between an unfilled plastic container and a filled plastic container. Such measurements may be utilized for quality or statistical process control (SPC) at critical locations.  
         [0034]     Furthermore, an entire exterior surface of a plastic container may be profiled thereby creating a visual profile of the plastic container as a whole.  
         [0035]     The preliminary information entered into the computer  16  can be saved in an object profile. The next time the object (or same formed object) is measured, the saved object profile may be retrieved and utilized for profiling as opposed re-entering the preliminary information manually by the user.  
         [0036]     The software further has a built-in calibration feature that will calibrate the vertical motion of the laser measurement system. When an object of a known height is placed onto the rotational platform  12 , the height of the object is entered into the software by the user. The software will provide commands to scan for the top of the object. The rotational platform  12  is then moved up the height of the object and re-zero the value for the vertical motion.  
         [0037]     The present invention further has the advantage of measuring the perpendicularity of an object (i.e., a bottle). Perpendicularity is important where alignment is critical between the opening of the bottle and a filler adapter of a dispensing unit dispensing a substance into a bottle. Vertical alignment between the opening of the bottle and the filler adapter must be achieved to allow spill-free dispensing from the dispensing unit to the bottle.  
         [0038]     The object is placed on the rotational platform  12  and centered thereon. The system will then determine the displacement of the top of the object (i.e., center of the bottle opening) to the center of the table, which constitutes the measure of the perpendicularity of the object.  
         [0039]     Furthermore, the laser measurement system may be used to measure and verify detailed information in regards to the thread finishing for proper alignment with a mating threaded end cap. The bottle is placed on the rotational platform  12  and scanned at various planes of the threaded portion for determining significant dimensional information from the finished threads.  
         [0040]     This is different from the typical measurements generated above because the threads are not in the same plane, but rather the threads spiral downward around the filler neck of the bottle. Measured thread dimensions includes a “T” dimension (i.e., thread crest diameter), an “E” dimension (i.e., thread root diameter), an “A” dimension (i.e., tamper evident bead diameter), and a “Z” dimension (i.e., maximum diameter on support ledge). Furthermore, by knowing the location of a plurality of “T” dimensions, the thread pitch is determined.  
         [0041]     In the illustrated embodiment, the user has to manually place and remove the objects being measured in the laser measurement system. In an alternative embodiment, an indexing station is provided similar to a carousel system, as shown in  FIG. 7 . An indexing station shown generally at  36  is disposed above the measuring device  10 . The rotational platform  12  is vertically moved to a respective position by the drive unit  15  such that the top surface of the rotational platform  12  is aligned horizontally with a stationary track floor  40  of the indexing station  36 . The user would place a plurality of objects  38  on the indexing station  36 . A plurality of separator guides  44  separate the plurality of objects  38  from one another. The plurality of separators guides  44  are “V-shaped” so that each of the plurality of objects  38  may be properly retained and moved along the track floor  40  while being indexed. When the scan operation is commenced, the first object is moved along the track floor  40  and displaced onto the aligned top surface of the rotational platform (i.e., loading position) by a first separator guide. The motion unit is then moved downwardly to commence profiling of the first object.  
         [0042]     After the measurement laser system has completed profiling and retrieving measurement data from the first object, the vertical drive unit  15  moves the rotational platform  12  upward to the loading position. The indexing station is advanced, so that the first object is displaced off the top surface of the rotational platform and onto the track floor  40  by the first separator guide. A second object is simultaneously moved along the track floor  40  and is displaced onto the top surface of the rotational platform  12  by a second separator guide. The second object is thereafter vertically moved and rotated for retrieving measurement data. The software controls the indexing of indexing station  44  so that each of the plurality of objects  38  are profiled and measurement data retrieved. Measurement data from each profiled object will be stored in a same file for data processing and retrieval. Alternatively measurement data may be stored in a plurality of files.  
         [0043]      FIG. 8  illustrates a method for measuring an object using the laser measurement system. In step  50 , data is entered into a computer software program containing the preliminary information of the plastic container. Such preliminary information may include height of the object, heights and locations which to measure, incremental degrees by which to rotate the object, scan mode, and the number of objects to profile. If the preliminary information for a respective object has been previously entered and stored, the preliminary information may be directly retrieved from a stored file in the computer&#39;s memory. After the preliminary information is manually entered by the user or retrieved from the stored file, a scan operation is initiated in step  51 . In step  52 , the indexing unit is advanced. A respective separator guide guides a respective plastic container onto the top surface of the rotational platform. Proximity sensors may be positioned in the indexing unit for determining the presence of a plastic container on the rotational platform to commence profiling. In step  53 , optional tooling may be used to center the plastic container on the top surface of the rotational platform, if desired.  
         [0044]     In step  54 , the zero reference point is established by vertically descending the rotational platform to the position where the bottom plane of the plastic container is inline and obstructing the electromagnetic laser beam. In step  55 , the plastic container is vertically moved to at least one vertical position as predetermined from the preliminary information entered into the software program. In step  56 , the plastic container is rotated a respective number of degrees for profiling at least one respective view within a respective plane. In step  57 , the measurement data of a respective profile is transmitted to the computer via a communication line and stored in a file.  
         [0045]     In step  58 , the plastic container is returned to the load position. In step  59 , a determination is made whether all of the plastic containers have been profiled by the laser measurement system. The software programs keeps track of whether all plastic containers have been profiled based on a number of plastic containers entered as part of the preliminary information for profiling versus the number of times the indexing table is indexed. If the determination is made in step  59  that more plastic containers require profiling, a return is made to step  52  to advance the indexing unit for profiling of the next plastic container. If the determination is made in step  59  that all plastic containers have been profiled, then the scan operation is terminated in step  60 .  
         [0046]     From the above description, it will be apparent that the described and illustrated system has produced a quick and simple method and apparatus for measuring the outer profile of an object. The system has been found to be particularly useful for measuring PET bottles, empty or filled, as well as preforms and associated tooling.  
         [0047]     In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be understood that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.