Abstract:
A method is provided for setting up a tube bender having a bend die, a clamp die, a pressure die and a wiper die. The method includes providing a test-piece having an outer surface defined by a length and a substantially round cross-section. The method also includes arranging the pressure die, the clamp die, and the wiper die relative to each other in the tube bender, and arranging the test-piece relative to the pressure die, the clamp die, and the wiper die. The method further includes applying a force by the tube bender to clamp the test-piece, and determining whether the applied force is within a predetermined range of forces. Additionally, the method includes adjusting the arrangement of at least one of the pressure die, the clamp die, and the wiper die to apply a force to the test-piece that is within the predetermined range of forces.

Description:
TECHNICAL FIELD 
     The present invention relates to tube and pipe bending, and, more particularly, to setting up a tube bender. 
     BACKGROUND OF THE INVENTION 
     Horizontal rotary draw bending is a commonly employed method utilizing tube bending machines for bending and shaping metal pipes and tubing. Horizontal rotary draw bending machines typically include a bend die, a pressure die, and commonly also a wiper die for restraining the subject tubing in a particular orientation during the bending operation. 
     Generally, the wiper die is employed for holding tubing in tension, with the aim of preventing possible wrinkling or creasing of the tube wall due to the stress encountered during the operation. Proper setting of the wiper die, the wiper die&#39;s fore and aft position and angular orientation, i.e. rake angle, with respect to a bend die, is highly important to the quality of resultant bent tubing. Traditionally, however, wiper die set-up is an iterative trial and error process, which may lead to production inefficiencies, as well as result in damage to the wiper die itself. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, a method is provided for setting up a tube bender having a bend die, a clamp die, a pressure die and a wiper die. The method includes providing a test-piece having an outer surface defined by a length and a substantially round cross-section. The method also includes arranging the bend die, the clamp die, the pressure die and the wiper die relative to each other in the tube bender, and arranging the test-piece relative to the bend die, the clamp die, the pressure die and the wiper die. The method further includes applying a force to the test-piece by the tube bender to clamp the test-piece, and determining whether the force applied to the test-piece is within a predetermined range of forces. Additionally, the method includes adjusting the arrangement of at least one of the bend die, the clamp die, the pressure die and the wiper die to apply a force to the test-piece that is within the predetermined range of forces. 
     The method may also include arranging a sensor relative to the outer surface, wherein the sensor is configured to sense application of a force to the test-piece. According to the method, arranging of the test-piece may include clamping the test-piece between the bend die, the clamp die, the pressure die and the wiper die. Determining whether the force applied to the test-piece is within a predetermined range of forces may be accomplished by sensing the force applied to the test-piece via a sensor arranged on the outer surface of the test-piece. Determining whether the force applied to the test-piece is within a predetermined range of forces may be further accomplished by communicating a signal representative of the sensed force to a processor. Determining whether the force applied to the test-piece is within a predetermined range of forces may be additionally accomplished by displaying the force via the processor to thereby compare the sensed force to the predetermined range of forces. Furthermore, determining whether the force applied to the test-piece is within a predetermined range of forces may be accomplished by displaying via the processor a suggested adjustment to the arrangement of at least one of the bend die, the clamp die, the pressure die and the wiper die. Displaying of the suggested adjustment via the processor may be accomplished on a monitor. 
     An apparatus for performing the above method in a rotary bender for bending a tube is also provided. The apparatus employs a test-piece having an outer surface defined by a fixed length and a substantially round cross-section corresponding to a cross-section of the tube. The apparatus also employs a first sensor array having at least one sensor arranged relative to the outer surface configured to sense forces applied to the test-piece via the bender. The apparatus additionally employs a second sensor array having at least one sensor arranged relative to the wiper die configured to sense the forces applied to the test-piece via the bender. Furthermore, the apparatus includes a processor in electronic communication with the first and the second sensor arrays, wherein the processor is arranged relative to the bender and configured to receive and process electronic signals representing the sensed forces. Additionally, the apparatus may include a monitor in electronic communication with the processor in order to display the sensed forces. 
     The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is schematic illustration of a plan view of a rotary tube bender having a bend die, a clamp die, a pressure die and a wiper die; 
         FIG. 2A  is a schematic illustration of a plan view of the wiper die of the rotary tube bender shown in  FIG. 1 ; 
         FIG. 2B  is a schematic illustration of a front view of the wiper die of the rotary tube bender shown in  FIG. 1 ; 
         FIG. 2C  is a schematic illustration of a side view of the wiper die of the rotary tube bender shown in  FIG. 1 , shown with an array of sensors positioned on its surface; 
         FIG. 3A  is a schematic illustration of a plan view of a test-piece having an array of sensors positioned on its surface; 
         FIG. 3B  is a schematic illustration of a side view of the test-piece, shown in  FIG. 3A , having an array of sensors positioned on its surface; 
         FIG. 4  is schematic partially cut-away illustration of a plan view of the rotary tube bender with the test-piece, shown in  FIGS. 3A-B , arranged therein; and 
         FIG. 5  schematically illustrates, in flow chart format, a method for setting up the tube bender by employing the test-piece shown in  FIGS. 3A-B . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in which like elements are identified with identical numerals throughout,  FIG. 1  illustrates a rotary tube bender  10 . The tube bender  10  includes a bend die  12 , a clamp die  14 , a pressure die  16 , and a wiper die  18 , as known by those skilled in the art. The tube bender  10  is commonly employed in the metal working industry to generate quality bends of a predetermined radius in pipes or tubes that are typically formed from high strength, but malleable materials such as steel or aluminum. 
     The bend die  12  has a largely circular shape with an outer radius R 1 , and is rotationally moveable with respect to an axis A. The bender  10  additionally has a circular guide surface  20  mounted on the axis A, concentrically with respect to the bend die  12 . The guide surface  20  has an outer radius R 2 , with which it serves to position the wiper die  18  in the bender  10 . The clamp die  14  mounts relative to bend die  12 , and includes a replaceable block  14   a  and an adjustable block  14   b . The clamp die  14  is configured to move concurrently with the bend die  12  during a pipe bending operation. The pressure die  16  is an adjustable component that moves together with the bend die and clamp die  14  during the pipe bending operation, as understood by those skilled in the art. The pressure die  16  typically includes a controlling mechanism (not shown) that produces a time delay, a.k.a. “boost delay”, in the movement of the pressure die with respect to the movement of the bend die  12  and clamp die  14  during the bending operation. Such boost delay is employed to prevent collision between the clamp die  14  and the pressure die  16  during the pipe bending operation. 
     The wiper die  18  includes a radius R 2  (shown in  FIG. 2A ) which corresponds to the outer radius R 2  of the guide surface  20 . Wiper die  18  also includes a radius R 3  (shown in  FIG. 2B ) which corresponds to the outer radius of a pipe that is desired to receive a formed bend. During the bending operation, a pipe slides past the wiper die  18 . The wiper die  18  functions primarily to keep a pipe in tension during the bending operation, in order to maintain shape and surface quality of the work-piece being subjected to processing stress. The wiper die  18  includes a permanent portion or holder  22 , and a wearable and replaceable portion  24 . The wearable portion  24  is typically formed from a relatively soft metal alloy, such as brass or aluminum to avoid scratching or damaging the material being bent. The wiper die  18  also typically includes a mechanism  26  for rapid adjustment and repositioning of the wiper die on the bender  10 . The wiper die  18  is an adjustable component that, once positioned, remains stationary with respect to non-moving features of the bender  10 , as understood by those skilled in the art. 
     A pipe work-piece is typically installed in the bender  10  by being lain along line X and clamped between block  14   a  and block  14   b  of the clamp die  14 . The position of the block  14   a  and block  14   b  is typically adjusted in order to align and restrain the pipe in the bender  10 . In order to properly restrain and support the pipe, it is additionally clamped between the pressure die  16  and the wiper die  18 , by adjusting the position of the wiper die, as well as, at times, the position of the pressure die. Once the pipe is secured in the bender  10 , and the bending operation is initiated, the bend die  12  and clamp die  14  are rotated in tandem about the axis A. While the bend die  12  and clamp die  14  are rotated, the pressure die  16  presses against the wiper die  18 , thereby advancing the pipe. 
     The commencement of motion of the pressure die  16  is delayed briefly relative to the motion of the clamp die  14 , to avoid collision between the pressure die and the clamp die during the bending operation. Following the brief delay, however, the pressure die  16  is kept in motion along with the pipe in order to avoid excessive tensile loading on the outside radius of the pipe bend that may cause a rupture. While in motion, the pressure die  16  additionally exerts pressure against the wiper die  18  in order to prevent wrinkling of the pipe surface on the inside of the bend. Throughout the operation, the wiper die  18  remains stationary. Such action of the bender  10  permits the forward part of the pipe that is clamped between blocks  14   a  and  14   b  to be horizontally drawn around the perimeter of the bend die. After the bending operation is completed, the pipe is left with a generally uniform bend having its inside radius correspond to the inner radius of the bend die  12 . 
     During the bending operation, while sliding past the wiper die  18 , the work-piece exerts significant stress on the wiper die. The amount of stress experienced by the wiper die  18  is directly related to the positioning of the wiper die in the bender  10 , with respect to the bend die  12 , the clamp die  14 , and the pressure die  16 . Consequently, a service life of the wiper die  18 , as well as the quality of the bent pipe is directly proportional to the positioning of the wiper die. Typically, however, proper positioning of the wiper die  18  with respect to the bend die  12 , the clamp die  14 , and the pressure die  16  is a trial and error process, during which the wiper die and/or the work-piece may become damaged by forces applied by the bender  10 . 
     Accordingly, load sensors  28  (shown in  FIGS. 2C-4 ), such as, for example, strain gauges, are employed to sense a force or forces that are applied by the bender  10  to a work-piece during the bending operation. The sensed force data is subsequently used to adjust the positioning of the wiper die  18  with respect to the bend die  12 , the clamp die  14 , and the pressure die  16 . A test-piece  30  is provided having an outer radius R 3 , corresponding to the radius of the work-piece, that is instrumented with one or more of the load sensors  28 . Sensors  28  may also be arranged on the wiper die  18  (shown in  FIG. 2C ), preferably at the interface between the holder  22  and the replaceable portion  24 , to provide additional data regarding the force applied to the test-piece  30 . The load sensors, such as strain gauges, may be arranged in an array, in order to effectively determine direction, as well as magnitude of the applied forces (as shown schematically in  FIGS. 2C-4 ). 
     Thus, the test-piece  30  is employed to sense a force that would be applied to the work-piece during the actual work-piece processing with a particular adjustment of the bender  10 . According to the embodiment, test-piece  30  is arranged or set-up in the bender  10  relative to the bend die  12 , the clamp die  14 , and the pressure die  16 , thus being secured by the bender, and then the bender is activated to apply a force to the test-piece. The load sensors  28  sense the applied forces and communicate a signal representing such forces, either via a wired or a wireless connection  32 , to an electronic processor  34  (shown in  FIG. 4 ). 
     The electronic processor is programmed to determine whether the force applied to the test-piece  30  is within a predetermined acceptable range of forces. The predetermined range of forces that is programmed into the electronic processor signifies the conditions required to generate a desired quality bent tube without inflicting damage to the work-piece or to the bending equipment. Such a range of forces is typically predetermined during design and development of the bender  10 , the corresponding dies  12 - 18 , and heuristically during test runs with representative tubing. 
     Accordingly, if the processor  34  determines that the sensed force is outside the predetermined acceptable range of forces, the processor displays on a monitor  36  a suggested adjustment to the positioning of at least one of the bend die  12 , the clamp die  14 , the pressure die  16  and the wiper die  18  in order to achieve the desired force on the test-piece  30 . An operator of the bender  10  is then tasked with performing the adjustment of the appropriate dies  12 - 18  according to the monitor display. Following the adjustment, the test-piece may be processed by the bender  10  once again, in order to verify that the adjustment was successful. If the adjustment is verified, an actual work-piece may then be processed through the bender  10 . If, on the other hand, the processor determines that the sensed force falls within the predetermined acceptable range of forces, the processor displays a message to such effect, thereby signifying that an actual work-piece may be processed through the bender  10 . 
       FIG. 5  depicts a method  38  for setting up the tube bender  10 , described above with reference to  FIGS. 1-4 . The method  38  is initiated in frame  40 , and then proceeds to frame  42 , where the test-piece  30  with load sensors  28  is provided. From frame  42 , the method proceeds to frame  44 , where the bend die  12 , the clamp die  14 , the pressure die  16  and the wiper die  18  are arranged and adjusted in the bender  10 . From frame  44 , the method proceeds to frame  46 , where the test-piece  30  is arranged in the bender  10  relative to the bend die  12 , the clamp die  14 , the pressure die  16  and the wiper die  18 . The method then proceeds to frame  48 , where a force is applied to the test-piece  30  by the bender  10 . 
     Following frame  48 , the method proceeds to frame  50  where it is determined by the processor  34  whether the force applied to the test-piece  30  is within the predetermined range of forces, as described above with respect to  FIG. 4 . If in frame  50  it is determined that the force is outside the predetermined range of forces, the method proceeds to frame  52 . In frame  52 , according to the method a recommendation is displayed on the monitor  36  as to the adjustment required to the bender  10  in order to bring the forces within the predetermined acceptable range. At this point, an operator of the bender is tasked with performing the required adjustments. 
     From frame  52 , the method proceeds to frame  54  where the test-piece  30  is used to verify whether the adjustment to the bender  10  has been successful. If the adjustment to the bender  10  was not successful, the method will return to frame  52  in order to repeat bender adjustment. If, on the other hand, the adjustment to the bender  10  was successful, the method may display on the monitor  36  that the bender is properly set-up, and will proceed to frame  56 , where the method is completed. 
     If in frame  50  it is determined that the force is within the predetermined range of forces, the method may display on the monitor  36  that the bender  10  is properly set-up, and proceed directly to frame  56 , where the method is completed. Following the proper set-up of the tube bender  10 , an actual pipe work-piece may be processed. The method and the apparatus, therefore, enable the tube bender  10  to generate consistent, quality bent pipes and tubing without damaging or prematurely wearing out the wiper die  18 . 
     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.