Abstract:
A bend-angle measuring device used to measure the bend angle of bent tubular components. The bend-angle measuring device makes use of a combined linear and rotational motion of a movable arm to gain access to numerous bent configurations.

Description:
BACKGROUND-FIELD OF INVENTION  
         [0001]    The present invention relates to an inspection device to measure the bend angle of a formed component. The inventive machine uses a combined linear and rotational motion to measure numerous formed configurations.  
         BACKGROUND-DESCRIPTION OF THE RELATED ART  
         [0002]    Over the past years, manufacturers of bent tubular components have had a need to measure the bend angles produced on various bending machines. This is necessary for quality control. Good quality control can lead to good parts produced. The bend angle of a fabricated bent part is most often a critical aspect of a manufacturing process. Over the years, bend angles have been measured using many devices including dedicated fixtures, digital protractors, various four-bar linkages coupled to digital readouts, and optical techniques.  
           [0003]    Dedicated fixtures are quick and accurate yet do not lend themselves well to being useful for measuring other bent configurations. Because of their dedicated nature, a dedicated measuring device is designed to measure only one configuration and thus is not intended to measure numerous configurations.  
           [0004]    Digital protractors are accurate and can measure numerous shapes, yet do not lend themselves well to measuring bend angles as the bend angle approaches 180°. This is due to the fact that the pivot point on a commercial digital protractor is unable to transverse in a linear fashion and thus the range of useful motion is limited when attempting to measure numerous bent configurations.  
           [0005]    There have been several digital devices coupled with various four-bar linkage designs to overcome the above disadvantages. Four-bar linkage devices intended to measure most bend angles are flexible to accommodate numerous tubular configuration. Nevertheless, four-bar linkages, by design, are constructed from several moving parts. With several moving parts in an inspection device, the repeatability of such a device will be limited. This limitation is caused by the excessive number of moving parts in contact with each other. Interaction between moving parts produce friction, and friction in an inspection machine leads to results that are not accurate and repeatable over time.  
           [0006]    Optical techniques, as disclosed by Brinkman, et al., U.S. Pat. No. 6,268,912, require a vast amount of software and electronics to operate. These techniques are intended for the high end of the inspection market and do not address a low cost solution.  
         SUMMARY OF THE INVENTION  
         [0007]    Accordingly, several objects and advantages of my invention are:  
           [0008]    (a) to reduce the number of components in a bend-angle measuring machine;  
           [0009]    (b) to market a digital bend-angle measuring machine at a low cost;  
           [0010]    (c) to provide a bend-angle measuring machine that will quickly adjust to numerous bend angle configurations; and  
           [0011]    (d) to provide a simple mechanism, with few moving components, to minimize the amount of friction in the measuring system.  
           [0012]    Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.  
           [0013]    The foregoing and other objects and advantages can be achieved by providing a fixed arm and a movable arm connected to a common base. The fixed arm is fixed relative to the base and the movable arm is able to transverse in a linear and rotational fashion toward and away from the movable arm. Coupled to the rotational motion of the movable arm is a digital encoder. The encoder transmits the position of the rotational axis of the movable arm to a digital readout and thus displays the rotational position (angle) of the movable arm relative to the fixed arm.  
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0014]    These and other objects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:  
         [0015]    [0015]FIG. 1 shows an isometric view of an embodiment depicting the fixed and movable arms attached to the base;  
         [0016]    [0016]FIG. 2 shows a top view of the embodiment depicting both degrees of motion regarding the movable arm relative to the fixed arm and their relation to the top surface;  
         [0017]    [0017]FIG. 3 shows a top view of the embodiment depicting the movable arm in a new rotational and linear position relative to the movable arm shown in FIG. 2; and  
         [0018]    [0018]FIG. 4 shows a cutaway view of the movable arm assembly showing the relation between the movable arm and how it is coupled to the digital encoder. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]    Reference will now made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
         [0020]    With initial reference to FIG. 1, a bend-angle measuring device  10  is shown. A base  11  is constructed from as solid material such as wood or metal. Attached to base  11  is a fixed arm  12 . Fixed arm  12  is unable to move relative to base  11  and the two can be attached by common fasteners. Fixed arm  12  is supported by a top surface  21 . Top surface  21  is the topmost surface of base  11  and is adjacent to fixed arm  12 . Top plate  21  is mostly flat. Attached to base  11  is a linear rail  17 . Linear rail  17  is attached to base  11  using common fasteners. Located on linear rail  17  is a linear bearing  16 . Linear bearing  16  is able to slide along linear rail  17 . Linear rail  17  is parallel to axis B-B shown in FIG. 1 and thus linear bearing  16  moves along axis B-B.  
         [0021]    Linear bearing  16  may be of the type described by Teramachi in U.S. Pat. No. 4,040,679. In U.S. Pat. No. 4,040,679, Teramachi teaches about a linear bearing that employs recirculating ball bearings. The ball bearings recirculate in a track while the bearing block advances in a linear fashion along a linear rail. The grooves in the linear rail help capture the ball bearings as the ball bearings recirculate within the bearing block. This technique results in rolling friction as the linear bearing moves relative to the linear rail.  
         [0022]    With reference to FIGS. 1, 2,  3 , and  4 , a block  15  is attached to linear bearing  16 . Free to rotate about an axis A-A (See FIG. 4) is a shaft  14 . Shaft  14 , constructed from metal, is supported by roller bearings  22 . Roller bearings  22  are supported by block  15 . Attached to shaft  14  is movable arm  13 . Attached to block  15  and shaft  14  is a digital encoder  18 . Digital encoder  18  is powered by a low voltage electrical source and outputs electrical pulses that are proportional to the rotational displacement of shaft  14 . Shaft  14  connects movable arm  13  to digital encoder  18  while shaft  14  rotates about axis A-A. From FIG. 1, digital encoder  18  is connected to a digital display  20  by a multi-conductor electrical cable  19 . Multi-conductor electrical cable  19  is passed thru base  11  via a slot  33  connecting encoder  18  to digital display  20 . The electrical pulses received by digital display  20  from digital encoder  18  are converted by digital display  20 . The converted pulses allow a user to view the real-time bend angle in large numerals on digital display  20 .  
         [0023]    From FIG. 1, a bent tube  30 , typically constructed from a hard material such as metal, is located above top surface  21  in preparation for inspection. Tangent to fixed arm  12  is tube  30  and more specifically the section of tube  30  in contact with fixed arm  12  is a tube leg  31  located on tube  30 .  
         [0024]    Tangent to movable arm  13  is tube  30  and more specifically the section of tube  30  in contact with movable arm  13  is a tube leg  32  located on tube  30 .  
         [0025]    From FIG. 2, a rotational arrow  34  and a linear arrow  35  show the two motions available to movable arm  13 . Linear bearing  16  travels along axis B-B which is in the same direction as linear arrow  35 . Shaft  14  rotates in a plane defined by rotational arrow  34 . Therefore movable arm  13  takes the rotational motion of rotational arrow  34  and the linear motion of linear arrow  35 .  
         [0026]    From FIG. 2, a tube  36  is located on top surface  21 . Tube  36  is formed at a greater bend angle than tube  30  as shown in FIG. 3. The position of movable arm  13  is adjusted differently for both bent configurations as shown in FIGS. 2 and 3.  
         [0027]    From FIG. 2, a bend angle  37  defines the bend angle between fixed arm  12  and movable arm  13 .  
         [0028]    In operation, with reference to FIGS.  1  thru  4 , tube  30  is placed on top surface  21 . Tube leg  31  is placed adjacent to fixed arm  12 . Once tube leg  31  is flush against fixed arm  12 , movable arm  13  is moved into positioned by hand until tube leg  32  is adjacent to movable arm  13 . An operator can then review the exact bend angle  37  by viewing digital display  20 .  
         [0029]    Movable arm  13  is able to move to numerous bend configuration via the combined rotational and linear motion of block  15  and shaft  14  as shown by rotational arrow  34  and linear arrow  35 . Linear rail  17  along with linear bearing  16  and guide block  15  move in a precision linear fashion along axis B-B. Independent of the linear motion of block  15  is the rotational motion of shaft  14  about axis A-A. Bearings  22  guide shaft  14  about axis A-A and thus permit a precision rotational motion as movable arm  13  rotates about axis A-A.  
         [0030]    As movable arm  13  rotates about axis A-A, digital encoder  18  outputs pulses proportional to the angular displacement of shaft  14  and thus the rotational position of movable arm  13  relative to fixed arm  12 . Digital display  20  always shows the bend angle  37 . The output of digital encoder  18  is transmitted via multi-conductor electrical cable  19  to digital display  20 . Multi-conductor electrical cable  19  connects encoder  18  to digital display  20 . As movable arm  13  rotates about axis A-A, its angular position (bend angle  37 ) is displayed via digital display  20 .  
         [0031]    Accordingly, the scope of the invention should be determined not by the embodiment illustrated, but by the appended claims and their legal equivalents.