Abstract:
A pipe cutting apparatus includes a machine base having a first machine table slidably secured for moving with a pipe during the extrusion thereof. The apparatus includes a rotary base table with a cutting arrangement attached at a periphery thereof such that the cutting arrangement orbits about the pipe during cutting thereof. The cutting arrangement includes a cutting tool supported on a pivoting support arm. The support arm includes an independent powered gear drive train for pivoting the support arm to accommodate different sizes of pipe and to allow cutting. Preferably the cutting apparatus has a second slidable table to allow precision cutting of multiple cuts of the pipe while the pipe is clamped or held.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a pipe cutting apparatus for cutting of extruded pipe. 
       BACKGROUND OF THE INVENTION 
       [0002]    Various arrangements have been used and proposed with respect to cutting of pipe, and in particular, inline cutting of pipe as the pipe is being extruded. Such pipe cutting arrangements can use a number of different drives such as hydraulic drives, pneumatic drives or electric drives for moving of a cutting blade to cut through the wall of the pipe, typically as the cutter is rotated about the pipe. 
         [0003]    One of our earlier pipe cutting structures is shown in U.S. Pat. No. 5,605,083 incorporated herein by reference. This pipe cutting apparatus includes a first rotational drive for rotating a collar having one or more cutters mounted on the collar. As the collar rotates, the cutters rotate around the pipe as the pipe passes through the centre of the device. 
         [0004]    The cutter includes a separate drive including a ring gear bearingly supported on the collar. This ring gear engages with a drive gear of the cutter and the cutter is moved in a radial manner into or out of the pipe. The ring gear is also rotatably driven and the speed of the ring gear is controlled relative to the collar. A slight change in speed of the ring gear relative to the collar will cause the cutter to move into or out of the pipe. If the ring gear and the collar rotate at the same speed there is no radial movement of the knife. 
         [0005]    The pipe cutting apparatus shown in this patent is mounted on a slidable table to allow cutting of the pipe as the pipe continues to be extruded. Basically, the pipe is clamped and once the pipe is clamped the cutting apparatus continues to move with the extruded pipe due to the slide mount of the table. If this arrangement is used to perform a second cut of the pipe, the pipe is released by the clamp arrangement and there is movement of the pipe relative to the cutting apparatus and the pipe is then subsequently clamped and cut. 
         [0006]    The prior art pipe cutting arrangements, including our own earlier U.S. Pat. No. 5,605,083, are difficult to adjust for wide variations in the diameter of the pipe being extruded, and the degree of control with respect to the cutting process and cutting speeds is not as precise as would be desired. Furthermore these arrangements are difficult to precisely locate a first cut relative to a second cut. The present invention seeks to overcome a number of these problems. 
       SUMMARY OF THE INVENTION 
       [0007]    A pipe cut-off apparatus comprises a machine base having a first machine table slidable in a predetermined direction for moving with a pipe during the extrusion thereof. The first machine table rotatably supports a base tube with the base tube positioned to allow a pipe to pass therethrough. A pipe clamp arrangement is aligned with and to one side of the base tube for clamping of the pipe during a pipe cutting procedure. A rotatable drive for the base tube rotates the base tube about a longitudinal axis thereof. At least one cutting arrangement is provided. Each cutting arrangement includes a mounting bracket attached to the base tube at a peripheral position, a support arm having a pivot shaft connecting the support arm to the mounting bracket and a drive gear secured on the pivot shaft. Each support arm includes a pipe cutting tool at an end of the support arm spaced from the pivot shaft. A drive arrangement is provided in engagement with the drive gear of the support arm for controlling pivoting movement of the support arm in a pipe cutting procedure coordinated with the rotation of the base tube to cause the cutting tool to cut the pipe into two pipe segments. 
         [0008]    In an aspect of the invention the gear drive for the support arms includes a ring gear rotatably mounted and coaxial with the base tube. The ring gear includes a separate motor drive driven to pivot the support arms and to move the cutting tools during the pipe cutting procedure from the clear position to a pipe cut position and returning said cutting tools to the clear position. 
         [0009]    According to an aspect of the invention, the ring gear is rotatably mounted on the base tube. 
         [0010]    In yet a further aspect of the invention each drive gear of the support arm includes a gear box reduction arrangement in mesh with the ring gear for controlling the pivoting of the support arm. 
         [0011]    In a further aspect of the invention the motor drive of the ring gear and the rotatable drive of the base tube are coordinated and the relative speeds of the motor drive of the ring gear and the rotatable drive of the base gear are intermittently varied to cause the pivoting of each support arm during the cutting procedure. 
         [0012]    In an aspect of the invention the rotatable drive of the base tube and the motor drive of the ring gear are driven to generally synchronize the rotational speed of the ring gear and the base tube with intermittent controlled variation in these rotational speeds causing the pivoting of each support arm. 
         [0013]    In an aspect of the invention the pipe clamp arrangement is supported by the first slidable table. 
         [0014]    In a further aspect of the invention the pipe cutting apparatus includes a second slidable table mounted on the first slidable table and moveable in the direction of the longitudinal axis of the pipe. The second slidable table has said pipe clamp arrangement mounted thereon. 
         [0015]    In a further aspect of the invention a pipe locating device is provided for positioning the pipe in the pipe cutting apparatus for cutting of the pipe in at least one predetermined position. The pipe locating device determines the position of the device relative to the pipe cutting tool for cutting in at least one predetermined position. 
         [0016]    In a further aspect of the invention the pipe locating device is mounted on the second slidable table and said first slidable table is moved relative to the second slidable table for cutting of said pipe in a second predetermined position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Preferred embodiments of the invention are shown in the drawings, wherein: 
           [0018]      FIGS. 1 and 2  are perspective views of the pipe cutting apparatus; 
           [0019]      FIG. 3  is a horizontal sectional view through the pipe cutting apparatus showing a first cutting position of the pipe cutter; 
           [0020]      FIG. 4  is a horizontal sectional view through the pipe cutting apparatus similar to  FIG. 2  where the pipe has been cut at a second predetermined position. 
           [0021]      FIG. 5  is a side view of the pipe cutting apparatus; 
           [0022]      FIG. 6  is an end view of the pipe cutting apparatus; 
           [0023]      FIG. 7  is a perspective view of a support arm of the cutting mechanism of the pipe cutting apparatus; and 
           [0024]      FIG. 8  is a partial side view of an alternate drive arrangement. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    The inline pipe cutoff apparatus  2  is shown in  FIGS. 1 and 2  and includes a pipe clamping arrangement  4 , a rotating cutter  6  and a support tube  8 . The pipe cutting apparatus  2  is mounted on a machine base  10  and includes a first slidable table  14  and preferably a second slidable table  16 . The second slidable table  16  supports the pipe clamping arrangement  4 . With this arrangement there can be relative movement between the pipe clamping arrangement  4  and the rotating cutter  6 . This ability to alter the position of the rotating cutter  6  relative to the pipe clamping arrangement  4  allows for precision placement with respect to locating a first cut in the pipe followed by locating a second cut while the pipe remains clamped. 
         [0026]    As can be appreciated, this cutting arrangement is preferably used as an in-line pipe cutting apparatus and the pipe that is being cut continues to advance at the extrusion speed. The second slidable table  16  is effectively secured to the pipe by the pipe clamping arrangement  4 . Thus the pipe clamping arrangement  4  will move at the production speed of the pipe. The first slidable table  14  is initially set relative to the second slidable table  16  such that the pipe cutting arrangement  6  is at a desired position relative to the pipe clamping arrangement  4 . After completing a first cut at a desired location, typically the rotating cutter  6  is moved towards the pipe clamping arrangement  4  and a second cut is performed. The use of two slidable tables allows for two spaced cuts while maintaining the pipe clamped. As can be appreciated more than two cuts can be completed. 
         [0027]    Additional details of the two slidable tables are described with respective  FIGS. 3 and 4 . The first slidable table  14  includes two opposed slide rails  15  and  17  having slide slots on their bottom surfaces and these rails are secured to the machine base  10  by a series of securing blocks  19 . In this way the first slidable table  14  can move relative to the machine base  10 . 
         [0028]    The first slidable table  14  and the second slidable table  16  typically include an adjustable and programmable actuator secured therebetween that controls the relative position of the tables. This actuator is used to move the rotating cutter  6  towards or away from the pipe clamping arrangement  4  and allows for precision cutting of the pipe at two or more locations while the pipe remains clamped within the clamping arrangement  4 . 
         [0029]    The adjustable actuator located between the two slidable tables can be a numeric controlled activator programmed for specific cuts for different sizes of pipe. For example the cutting of a coupler, as shown in  FIG. 4 , is known for each size of pipe being manufactured. The position of the cuts can be preprogrammed for different pipe sizes such that an operator merely selects the pipe size and thereafter adjustment of the cutter can occur. Although two predetermined cuts are described further cuts may also be made. 
         [0030]    In some cases it is desirable to make 4 cuts with the first two cuts for removing scrap portion  126  (shown in  FIG. 4 ) and two further cuts associated with pipe section  122  for removing a quality control section for testing. 
         [0031]    The second slidable table  16  includes opposed slide tracks  18  fixedly secured to the first slidable table  14  and slide blocks  20  secure the pipe clamping arrangement  4  to the first slidable table  14 . 
         [0032]    The alternate manual adjustment arrangement  24  allows adjustment of the end positions of a positioning cylinder actuator  28 . This allows the operator to adjust the respective movements of the first and second tables between two precise end positions. These end positions typically change between different pipe sizes. 
         [0033]    The pipe clamping arrangement  4  includes a moveable bottom clamp guide  40  and a moveable upper clamp  46 . These members effectively move towards or away from one another by rotation of the screw shafts  48 .  FIG. 1  shows a number of different inserts  42  that are selectively secured to the clamping arrangement  4  for engaging different sizes of pipes. These inserts are easily inserted or removed from the clamp arrangement in accordance with the size of the pipe being produced. The screw shafts  42  cooperate with the support blocks  50  and  51  secured to the upper clamp  46  and the bottom clamp  40  respectively. Pins  52  and  53  of the support blocks engage the screw shaft and position the clamp members in accordance with the position of the screw shaft  48 . The rotational position of the screw shaft  48  is controlled by the linkage  56  that is in engagement with the positioning cylinder  54 . This provides an effective arrangement for engaging the pipe. The screw shafts have two thread shapes to move the clamps towards or away from each other. 
         [0034]    The rotating cutter  6  includes a rotating base tube  80  that extends through the opposed support plates  60  and  62  secured to the first slidable table  14 . The rotating base tube  80  is supported by the bearing arrangement  64  and as such can be rotated at a relatively high speed. The rotational drive for the rotating base tube  80  is provided by the large drive gear  66  secured to the periphery of the rotating base tube  80 . The large drive gear is in mesh with a smaller gear  68  that is driven by the belt drive  70  which in turn is driven by the motor  72 . Therefore the motor  72  precisely controls the rotational speed of the rotating base tube  80 . 
         [0035]    A mounting bracket  82  is fixed on the rotating base tube  80  and supports the cutting arrangement  84 . The rotating base tube  80  extends through the two support plates and also supports the independent ring gear  90  on the rotating base tube  80  by means of bearings. Thus the position of the independent ring gear  90  relative to the base tube  80  is easily changed and there is no mechanical connection causing the ring gear  90  to rotate with the base tube  80 . In fact, in one embodiment, independent ring gear  90  includes its own drive arrangement and this drive arrangement is controlled to provide a desired rotational relationship between the rotating base tube  80  and the independent ring gear  90  used to control the cutting arrangement  84 . A computer controller can be used to control the two drives. 
         [0036]    The planetary gear  96  of the cutting arrangement  84  is in mesh with the independent ring gear  90 . As can be appreciated, planetary gear  96  is forced to rotate about the independent ring gear  90  with rotation of the base tube  80 . If the independent ring gear  90  is rotated at the same speed as the rotating base tube  80  there will be no rotation of the planetary gear  96 . By controlling of the rotation of the independent ring gear  90  relative to the base tube  80 , the rotation of the planetary gear  96  is controlled. This planetary gear rotates the pivot shaft  108  that is attached to a gear box reduction arrangement  110  and eventually controls rotation of the support arm  112  about the pivot shaft  108 . With this arrangement, the position of the cutting tool  114  relative to the pipe is controlled. These elements are best shown in  FIGS. 5 and 7 . 
         [0037]    In a second embodiment shown in  FIG. 8 , an alternate drive arrangement  200  is disclosed. This drive arrangement  200  includes a drive motor  72  connected by drive shaft  201  to the variable differential drive  202 . The variable differential drive  202  includes a driven gear  205  in mesh with ring gear  90 . A stepper motor  204  is used to control rotation of ring gear  90  relative to drive gear  66 . Variation in the relative rotation of gears  66  and  90  is used to control pivoting of the support arm  112  and thus the cutting process. Ring gear  90  and drive gear  66  generally rotate at the same speed. The stepper motor is controlled to advance or retard rotation of ring gear  90  relative to drive gear  66  to thereby control the position of the support arms of the cutting arrangement. The variable differential drive  202  used in the second embodiment is less expensive than the second drive motor used in the first embodiment. 
         [0038]      FIGS. 3 and 4  illustrate the precision achieved between two cuts of the pipe while the pipe remains clamped. In  FIG. 3 , the cutting tool  114  is about to cut the pipe to produce the cut line  116 . This will allow pipe section  120  to be separated from the pipe section  122 . The pipe section  120  includes the bell mouth connector  124 . The rotating base drum  80  is rotated at the desired speed to perform a cut with the cutting tool  114 . The advancement of the cutting tool  114  through the pipe is effectively controlled by the speed of the independent ring gear  90  relative to the rotating speed of the base tube  80 . Once this cut  116  has been accomplished, pipe section  120  is essentially free. Often, on the downstream end of this section there is a pipe puller which will cause a separation of section  120  from section  122 . Section  122  continues to move at the production speed of the extrusion device. 
         [0039]    In  FIG. 2 , a second cut line has been completed to remove the scrap portion  126 . The second cut line is generally shown as  128 . In  FIG. 4  it can be seen that the rotating cutter  6  has been moved towards the pipe clamp arrangement  4  while the pipe clamp arrangement  4  maintains engagement with the pipe section  122 . This change in position is possible due to movement of the first slidable table  14  relative to the second slidable table  16  controlled by the actuator cylinder  139  connected therebetween. Once the rotating cutter is positioned at the second position it can go through its normal cutting function to force the cutting tool  114  to produce a second cut. This arrangement provides excellent control on the position of the two cuts in the pipe as the pipe section  122  continues to be clamped. With this arrangement, it can be seen that the bell mouth connector  124  is effectively formed and the pipe section  122  has been cut to expose an insert end portion  129  that can now be received within a bell mouth connector  124 . 
         [0040]    Actuator cylinder  139  is one example of an activator for positive control of the relative position of the first and second slidable tables. This activator is preferably connected to a controller  141 . The controller  141  is also connected to a pipe feed sensor  143  that monitors the speed of pipe as it is advanced towards the pipe cutting apparatus  2 . This sensor  143  preferably also identifies a pipe coupling. In corrugated pipe, the sensor recognizes each corrugation and the absence of corrugations indicates a pipe coupling. This information is used by the controller to appropriately adjust the slidable tables and thereby determine the cut positions. The controller  141  can include preprogrammed cut procedures for different diameter of pipes and locations of couplers. The controller can also adjust the motor drives for appropriately positioning and controlling the cutting arrangement including the support arm. As can be appreciated, the position of pipe couplings is typically known by the overall extrusion system. 
         [0041]    With this arrangement adjustment of the cutting apparatus by the operator is simplified and the cutting apparatus can also be adjusted as part of the overall production control. For example, cutting extruded pipe to specific lengths is easily programmed and executed. The need for the operator to have significant setup expertise is reduced. 
         [0042]      FIGS. 5 ,  6  and  7  provide additional details with respect to the rotating cutter  6 . 
         [0043]    The independent ring gear  90 , as shown in  FIG. 5 , is controlled due to engagement with drive gear  100  controlled by the motor drive  98 . The rotational speed of the rotating drum  80  is determined by the motor  72  that through a belt drive and gear arrangement, controls the speed of the large drive gear  66 . It can also be seen that the first slide table  14  is secured above the machine base  10  by the slide block  19 . 
         [0044]      FIG. 5  also shows the positioning plunger  130  that has an end portion  132  for engagement between two corrugations of a corrugated pipe. This plunger can be used to initially engage and align with a particular pipe corrugation and thereby effectively indexes the pipe on the plunger. The clamping arrangement then clamps the precisely located pipe and holds the pipe in this desired indexed position. The subsequent controlled movement of the first and second tables allows for precise cutting of the corrugated pipe or the corrugated pipe with a coupling segment, at precision locations. Additional details of this arrangement are shown in  FIG. 6 . 
         [0045]      FIG. 6  perhaps provides the best view of the slidable first table and second table. 
         [0046]      FIG. 7  illustrates a number of components of the cutting arrangement  84  including the support arm  112  that is pivotally mounted to the mounting bracket  82 . As previously described, the planetary gear  96  is in mesh with the independent ring gear  90  and depending upon the direction of rotation of planetary gear  96  about the pivot shaft  108 , the position of the support arm  112  will change. To provide improved accuracy and control with respect to the position of the support arm  112  relative to the mounting bracket, a reduction gear box  110  is provided, whereby a rotation of gear  96  causes a much reduced rotation of the support arm  112 . The support arm  112  also acts as a lever with the cutting tool  114  being provided at the end of the lever. A gear reduction of at least 15 to 1 and preferably 50 to 1 or greater can be used. 
         [0047]    The initial position of the lever and the cutting tool  114  is easily adjusted for different sizes of pipe merely by rotation of the independent ring gear with the rotating base tube remaining stationary. Thus, the initial position of the cutting tool relative to a particular diameter of pipe is easily adjusted. In the preferred embodiment as shown in the drawings, only one cutter is rotated about the pipe for cutting through the pipe. This provides excellent control of the location of the cut line and better control of the cutting process. In addition, the actual speed of rotation of the rotating base tube  80  can be adjusted for providing a desired cutting speed of the cutting tool  114 . This is helpful to controlling the cutting speed for different pipe sizes. 
         [0048]    The rate of advancement of the cutting tool  114  into the pipe is also controllable in a precise manner due to the reduction gear box and the ability to control the relative rotation of the base tube  80  and the independent ring gear  90 . The relative speeds are intermittently varied to pivot the support arm of the cutting arrangement. When the speeds are equal there is no pivoting of the support arm. Changing of the relative speeds is similar to a phase change. It has been found that the cantilevered support arm  112  and the use of a reduction gear box within the support arm provides excellent control of the position of the support arm and also allows effective adjustment of the cutting arrangement for cutting of extruded pipe over a large range of diameters. 
         [0049]    Although various preferred embodiments of the present invention have been described herein in detail, it will be appreciated by those skilled in the art, that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.