Patent Publication Number: US-2015074966-A1

Title: Electro-Mechanical Pipe Fusion Machine

Description:
BACKGROUND OF INVENTION 
     This invention relates generally to fusion of polyolefin pipes and more particularly concerns the machines used to perform the pipe fusion process. 
     Existing devices for butt fusion of ½″ to 2″ outer diameter polyolefin pipe are manually operated. As a result, from joint-to-joint and operator-to-operator, it is difficult to replicate with a high degree of consistency those conditions known to afford excellent joint quality. What consistency there is cannot be monitored because manually operated devices do not provide data that can be used to assess and record the quality of a fused joint. Hydraulics have thus far proven to be inadequate to the resolution of these small diameter pipe fusion issues. Furthermore, even manual devices require an electrical power source adequate to meet the energy demands of the fusion heaters. The need for hard wiring to a fusion heater limits the mobility of the manual devices. 
     It is, therefore, an object of this invention to provide a pipe fusion machine that is suitable for fusion of small diameter polyolefin pipes. It is also an object of this invention to provide a pipe fusion machine suitable for fusion of small diameter polyolefin pipes that is capable of providing data that can be used to assess and record the quality of a fused joint. A further object of this invention is to provide a pipe fusion machine suitable for fusion of small diameter polyolefin pipes that has unlimited mobility. 
     SUMMARY OF INVENTION 
     In accordance with the invention a machine for fusing polyolefin pipe includes a carriage and controls. 
     The carriage has a base on which two screws are journaled for rotation in spaced-apart parallel horizontal alignment. Fixed jaws are provided at one end of the base. The lower fixed jaw is seated between the screws. The upper fixed jaw is pivotally mounted on the lower fixed jaw. The upper and lower fixed jaws are co-operable to grip and hold a pipeline centered on a longitudinal axis parallel to the screws. Travelling jaws are mounted for reciprocal travel on the screws. The lower travelling jaw is threaded on the screws. The upper travelling jaw is pivotally mounted on the lower travelling jaw. The upper and lower travelling jaws are co-operable to grip and hold a pipe stick centered on the same longitudinal axis as the pipeline. The screws are electrically driven to selectively reciprocate the travelling lower jaw toward and away from the fixed lower jaw to bring the gripped pipes into and out of close proximity, respectively, for performance of fusion process tasks. 
     The controls include an electrical closed loop circuit that controls operation of the screws to transfer the travelling lower jaw to a base axial distance from the fixed  1  owner jaw for performance of a fusion process task. The controls a lso include an electrical load cell feedback circuit that controls operation of the screws to reciprocate the travelling lower jaw in relation to the base axial distance in response to feedback from the load cells so as to maintain a predetermined force between the pipes during performance of the fusion process task. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
         FIG. 1  is a perspective view perspective view of the carriage of an electro-mechanical fusion machine for small diameter polyolefin pipe; 
         FIG. 2  is a top plan view of the carriage of  FIG. 1 ; 
         FIG. 3  is a cross sectional view taken along the line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a cross sectional view taken along the line  4 - 4  of  FIG. 2 ; 
         FIG. 5  is a block diagram of the electronics contained in the carriage of  FIG. 1 ; 
         FIG. 6  is a block diagram of the electronics contained in the command module of the machine of  FIG. 1 ; 
         FIG. 7  is a flow chart illustrating the operation of the user interface software of the machine of  FIG. 1  for the collection of job and user data; 
         FIG. 8  is a flow chart illustrating the operation of the user interface software of the machine of  FIG. 1  for the preparation of the machine for the facing phase of the fusion process; 
         FIG. 9  is a flow chart illustrating the operation of the user interface software of the machine of  FIG. 1  for facing the pipes to be fused; 
         FIG. 10  is a flow chart illustrating the operation of the user interface software of the machine of  FIG. 1  for the preparation of the machine for the heating phase of the fusion process; 
         FIG. 11  is a flow chart illustrating the operation of the user interface software of the machine of  FIG. 1  for installation of the heater between the faces of the pipe to be fused; 
         FIG. 12  is a flow chart illustrating the operation of the user interface software of the machine of  FIG. 1  for heating the faces of the pipes to be fused; 
         FIG. 13  is a flow chart illustrating the operation of the user interface software of the machine of  FIG. 1  for the performance of the fusion phase of the process; 
         FIG. 14  is a sample of a joint report provided by the machine of  FIG. 1 ; and 
         FIG. 15  is a perspective view of the carriage and command module of the is machine of  FIG. 1  with a pipeline and a pipe stick gripped in the carriage fixed and travelling jaws. 
     
    
    
     While the invention will be described in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the invention to that embodiment or to the details of the construction or arrangement of parts illustrated in the accompanying drawings. 
     DETAILED DESCRIPTION 
     An electro-mechanical machine for fusing polyolefin pipe includes a carriage  10  for performing the fusion tasks and controls for the operation of the carriage  10 . The controls are in the carriage  10 , a power base  100  and a command module  200 . 
     Carriage Structure 
     Turning to  FIGS. 1-4 , the carriage  10  includes a base  11  with upright left and right side portions  13  and  15 . As shown, front and rear screws  17  and  19  are journaled in the upper ends of the side portions  13  and  15  for rotation about spaced-apart, horizontal, parallel axes  21  and  23 . 
     A first approximately semi-circular lower jaw  25  is seated in the left side portion  13  between the screws  17  and  19  and a first approximately semi-circular upper jaw  27  is pivotally mounted on the rear of the upright left portion  13  for rotation into and out of closure on the lower jaw  25 . When closed, the jaws  25  and  27  define a circular opening  29  of diameter equal to the outer diameter of the pipeline to be fused. The left side lower and upper jaws  25  and  27  are co-operable to firmly grip and maintain the pipeline in a position centered on a longitudinal axis  31  parallel to the screw axes  21  and  23 . 
     A second approximately semi-circular lower jaw  35  is mounted for reciprocal travel on the screws  17  and  19  and a second approximately semi-circular upper jaw  37  is pivotally mounted on the rear portion of the lower jaw  35  for rotation into and out of closure on the lower jaw  35 . When closed, the jaws  35  and  37  define a circular opening  39  of diameter equal to the outer diameter of the pipe stick to be fused. The screw-mounted lower and upper jaws  35  and  37  are co-operable to firmly grip and maintain a pipe stick in a position centered on the longitudinal axis  31 . 
     An approximately semi-circular seat  41  is provided in the right side upright portion  15  between the screws  17  and  19 . The seat  41  is also centered on the longitudinal axis  31  so that the pipe stick can extend from the travelling jaws  35  and  37  beyond the right side upright portion  15  of the base  11 . 
     As best seen in  FIGS. 2 and 3 , the right end shafts  43  of the screws  17  and  19  are journaled through ball bearings  45 , load cells  49  and thrust bearings  51  to pins  53 . The left end shafts  55  of the screws  17  and  19  are journaled through bushings  57  to driven gears  59  mounted on the left end screw shafts  55 . The mid-portions  61  and  63  of the screws  17  and  19  are threaded through first travelling jaw bushings  65  in sleeves  67 , travelling jaw nuts  69  in the sleeves  67  and second travelling jaw bushings  71  in the lower travelling jaw  35 . Thus, the torque from the driven gears  59  rotating the screws  17  and  19  is converted into an axial force applied to the travelling jaw  35 . Rotation of the screws  17  and  19  in one direction causes the travelling jaw  35  to move closer to the fixed jaw  25  and in the other direction causes the travelling jaw  35  to move away from the fixed jaw  25  to bring gripped pipes into and out of close proximity for performance of fusion process tasks. 
     As best seen in  FIG. 4 , the forward driven gear  59  engages an idler gear  73  that engages a driving gear  75  on the shaft  77  of a dc motor  79 . The rear driven gear  59  engages an idler gear  81  that engages an encoder coupling gear  83  that engages another idler gear  85  that is also engaged to the driving gear  75  on the shaft  77  of the dc motor  79 . The encoder coupling gear  83  is mounted for rotation on the shaft  123  of a rotary encoder  125 , as is seen in  FIG. 5 . Since there are an odd number of gears  73  or  81 ,  83  and  85  between the driving gear  75  and the driven gears  59 , the screws  17  and  19  rotate in the same direction. 
     The upper jaws  27  and  37  have threaded clamp knobs  87  and  89  that engage the lower jaws  25  and  35  to draw the jaws  25  and  27  and  35  and  37  tightly against the pipeline and the pipe stick. As shown the upper jaws  27  and  37  also have downwardly depending curved tongues  91  and  93  which seat in mating grooves  95  and  97  in the lower jaws  25  and  35  to strengthen the mating relationship of the jaws. An emergency stop power button  99  is mounted on the front of the carriage  10  and a cable connector  101  is mounted on the right side of the carriage  10  for coupling the carriage  10  with the command module  200 . 
     Carriage Electrical System 
     Looking at the carriage block diagram of  FIG. 5 , the carriage power base  100  is in two way communication with a transceiver  113  via a communication bus  115  and with a power distribution module  117  via a power bus  119 . An H-bridge driver  121  connected to the power distribution module  117  applies polar variable voltage to the dc motor  79  to move the traveling jaw  35  closer to or away from the fixed jaw  25 . The shaft  123  of the rotary encoder  125  is coupled to the encoder coupling gear  83  which is in turn coupled to the shaft of the dc motor  79  by the idler gear  85  and the motor driving gear  75  as seen in  FIG. 4 . The rotary encoder  125  provides angular displacement feedback to a digital input module  127 . Continuing to look at the carriage block diagram of  FIG. 5 , the outputs of the load cells  49  are fed through load cell conditioners  131  to an analog input module  133 . A pulse width modulation module  135  provides the feedback signals to the H-bridge driver  121  to control the voltage applied to the dc motor  79 . A universal asynchronous receiver/transmitter  137  is in two-way communication with the transceiver  113 . The UART module  137 , PWM module  135 , digital input module  127  and analog input module  133  are part of the carriage microcontroller  140 . The microcontroller  140 , the transceiver  113 , the power distribution module  117  the H-bridge driver  121  and the load cell conditioners  131  and  133  are on the carriage circuit board  150 . The circuit board  150  is mounted in the carriage base  11 . 
     Command Module Electrical System 
     Looking at the command module block diagram of  FIG. 6 , a pocket PC  201  is in two-way a communication with a transceiver  203  and a carriage PCB  204  is in two-way communication with another transceiver  205 . The heater element  207  is powered through the power distribution module  209  via the heater power switch  211 . The power distribution module  209  receives electrical power from a pair of batteries  213  and  215  via a battery selector latching relay  217 . The power distribution module also distributes power to a 12V regulator  219  serving the pocket PC  201 , to a relay driver  221  with an output controlling the battery selector latching relay  217  and a battery monitor  223 . Heater element data is communicated by RTD drivers  225  and  227  and battery data communicated by the battery monitor  223  to an analog input module  229 . The relay driver  221  and the heater power switch  211  are controlled by the outputs of a digital output module  231 . The transceivers  203  and  205  are in two-way communication with universal asynchronous receivers/transmitters  233  and  235 . The UART modules  233  and  235 , the digital output module  231  and the analog input module to  229  are part of the control module microcontroller  240 . The microcontroller  240 , the transceivers  203  and  205 , the power distribution module  209 , the heater power switch  211 , the relay driver  221 , the RTD drivers  225  and  227 , the 12V regulator  219  and the battery monitor  223  are on the control module circuit board  250 . The microcontroller  240 , the circuit board  250 , the batteries  213  and  215  and the battery selector latching relay  217  are in the command module  200 . 
     Operation of the System 
     The controls of the machine include an electrical closed loop circuit that controls operation of the screw drives  59  to transfer the travelling lower jaw  35  to a base axial distance from the fixed lower jaw  25  for performance of a fusion process task. The controls also include an electrical load cell feedback circuit that controls operation of the screw drives  59  to reciprocate the travelling lower jaw  35  in relation to the base axial distance in response to feedback from the load cells  49  so as to maintain a predetermined force between the pipeline and pipe stick during performance of the fusion process task. 
     Considering  FIGS. 5 ,  6  and  15 , the command module  200  rests in a cradle on the power base  100 , is powered by the charging cable from the power base  100  and communicates via serial cable to the power base circuit  150  board. It provides a graphical interface for the operator. It calculates the appropriate time and force values based on information provided by the operator. It executes the fusion procedure by requesting actions in the feedback over a serial communication interface. 
     The requests from the command module  200  travel over a serial link of the transceiver  203  to the microcontroller  240  in the power base circuit board  250 . Firmware running on the power base circuit board  250  interprets messages from the command module  200 . Any requests for carriage action are forwarded over a serial link of the transceiver  205  to the microcontroller  140  in the carriage  10 . 
     The carriage  10  responds to messages with an acknowledgment message that contains sensor and status data. The power base  100  gathers this information from the carriage  10 , combines it with heater and battery feedback data and sends it all back to the command module  200  over the link of the transceiver  205 . 
     Requests for battery switching, alarm activation or heater temperature target adjustment are acted upon by the power base control firmware and are not forwarded to the carriage  10 . The digital output module  231  is used to activate the alarm and to switch between the two batteries  213  and  215  so that operation can continue when one battery to  213  or  215  is drained. 
     The power base circuit board  250  regulates heater temperature by monitoring the resistance of the RTDs in the heater  207 . The resistance is measured by driving a constant electrical current through the RTDs and measuring the resultant voltage. Voltage from each RTD is channeled into an input pin on the analog input module  229  of power base circuit board microcontroller  240 . A feedback loop in the software compares the heater feedback temperature to the target temperature set by the command module  200  and uses the digital output module  231  to drive the solid state switch  211  that controls the power flow to the heater  207 . By adjusting the duration and frequency of power flow to the heater  207 , the power base feedback loop maintains that target temperature set by the command module  200 . 
     The firmware in the carriage microcontroller  140  implements two feedback loops that use at the dc motor  79  as an output. These feedback loops respond to requests from the command module  200 . Requests from the command module  200  are relayed through the power base circuit board  250  and arrive over the communication bus of the transceiver  113 . The transceiver  113  converts the differential transceiver signals to single-ended signals that can be read by the UART module  137  of the carriage microcontroller  140 . The UART module  137  decodes the messages and firmware in the microcontroller  140  interprets the messages. 
     The dc motor  79  is the prime mover for the carriage  10 . The carriage microcontroller  140  controls the direction of rotation and amount of applied torque by manipulating the inputs of the H-bridge module  121  that drives the motor  79 . Two wires from the digital input module  127  set the direction of rotation and two wires from the pulse width modulation module  135  set the average applied voltage which controls top speed and torque. 
     Rotation of the motor shaft translates through a set of gears and screws and the results in linear movement of the pipe clamps. This linear motion is necessary for positioning the pipe and is for insertion and removal of leader and facer. Due to the plastic nature of the pipe material, small adjustments in linear motion can&#39;t be used to control the oppressive force applied to the pipe and other objects held in compression between the moving and fixed jaws  35  and  37  and  25  and  27 . 
     The load cells  49  in the fixed jaws  27  provide feedback about the intensity of the applied force. These load cells  49  have a Whetstone bridge output that is fed into the load cell conditioners  131  that amplify the differential voltage from the load cells  49  and past the resultant voltage to the microcontroller analog input module  133 . A force feedback loop runs in the software. This loop monitors the so feedback values from the load cells  49  and watches for force-related commands from the microcontroller  140 . When activated by the microcontroller  140 , this loop will make small discrete adjustments of the motor in order to affect very small linear movements of the travelling jaws  35  and  37 . Do to the plasticity of the pipe, the small changes in position can be used for precise control of the inter-facial force between two pieces of pipe. 
     The incremental quadrature-type rotary encoder  125  in the rear train provides relative position feedback that is used to carry out position-related commands for opening and closing the distance between the jaws  25  and  35  of the carriage  10  by a fixed distance. This feedback is used during the critical bead-up phase of the fusion process. During bead-up this sensor precisely monitors the amount of plastic displaced against the heater  207  for a bead of molten plastic. 
     User Interface Software Flow Chart 
     Turning to  FIGS. 7-13 , the inter-action of the user with the machine can be understood. 
     In  FIG. 7 , at the start of operation the user is prompted to enter task information such as the operator ID, the job number and the joint number. The user is next prompted to enter machine information such as the machine ID, the model number, the fusion type and the applicable fusion specifications and standards. The user is then prompted to enter pipe information such as pipe material, pipe size and pipe wall thickness. The machine microcontrollers then compute and save fusion forces and times based on pipe size and the applicable fusion specifications and standards. The user is then prompted to enter optional notes about the job site and other notable information relative to the application. 
     In  FIG. 8 , after the necessary information has been entered and calculated, the user is prompted to prepare the pipe for auto-facing, including loading the pipeline and pipe stick into the jaws and installing the facer between them. When the user indicates completion of these tasks by tapping “next,” the machine sends a command to sound a warning alarm and resets the process timer. The machine then displays the message “Closing carriage . . . ”. 
     In  FIG. 9 , after the message display, the user is told to face the pipe manually while the pipe is fed automatically by the machine. When the user indicates completion of these tasks by tapping “next,” the machine sends a command to close the carriage and maintain low force to face the pipe. The machine then waits for the user to signal that the facing operation is completed. After the machine receives the signal, the machine closes/bumps the carriage, forcing the pipe ends against the facer. In this position, the machine displays the “final trimming” message and operates the facer to feather off the pipes. When the user signals that feathering is completed, The machine sends commands to sound the warning alarm, reset the process timer and display “opening carriage.” The machine then sends a command to open the carriage so that the operator can remove the facer. Once the carriage is opened, the machine displays the message “remove facer.” After removing the facer, the user signals the machine that the task is completed. 
     In  FIG. 10 , after the machine commands the heater to the specified temperature per the selected fusion standard. The machine then displays “carriage will close automatically for alignment check . . . ” and soundness warning alarm. The machine and then sets a low force, closes the carriage and displays “closing carriage . . . ”. The machine then waits for a spike in force indicating that the pipe bands have touched. The machine then displays the “alignment check” message. Once the alignment is checked, the user signals completion to the machine. The machine then sounds the alarm and displays “carriage will close automatically.” The machine sends a command to set the fusion force and displays “closing carriage” and waits for a spike in force indicating the pipe ends touched and starts the slip check timer. 
     In  FIG. 11 , the machine displays the “performing slip check . . . ” message and begins counting down to zero. When the time lapsed machine checks to see if the pipe has slipped. If so, the machine displays the message “Pipe slipped!” and waits for the user to confirm receipt of the message, after which the machine returns to the “0” position of  FIG. 8 . If the pipe has not slipped, the machine sends the command to open the carriage to the heater insertion point. The machine then displays the heater temperature range per the selected fusion standard and waits for the heater temperature to be in range. The machine then prompts the user to clean the heater, install the heater and signal when the tasks are completed. When the machine receives the signal, it records the heater temperature. 
     In  FIG. 12 , the machine displays the messages “tap ‘Fuse&gt;Start’ to begin fusion process” and “Carriage will move automatically!” When the user has tapped “Fuse&gt;Start” the machine and send a command to sound the alarm and displays “Carriage will move automatically!” At the end of the alarm, the machine displays “closing carriage . . . ” and sends commands to set bead-up force and to close pipes on the heater. When the pipe ends are against the heater the machine computes the bead displacement from the pipe size and sends commands to reset the timer and position the counter. The machine then displays “bead-up” and the current placement value and waits until the required displacement is achieved. The machine then displays “heat soak” and the cycle time remaining and waits until the timer count down to zero, sounding the warning alarm twice during the countdown. The machine then sends the command to open the carriage to the “heater removal point” and waits for the carriage to open to that position. 
     In  FIG. 13 , the machine displays “closing carriage” and closes the carriage to fuse the pipe at fusion force. When machine displays “Fuse” and cycle time remaining as the timer counts down to zero. This completes the fusion process and the machine saves the process data to report file and displays the report content. Turning to  FIG. 14 , a sample report is illustrated. 
     As seen in  FIG. 15 , the machine, including the carriage  10  and the power base  100  carrying the command module  200 , the facer  206  and the heater  207 , is illustrated with a pipeline L and a pipe stick S gripped in the fixed jaws  25  and  27  and the travelling jaws  35  and  37  and the carriage in its closed condition. 
     Thus, it is apparent that there has been provided, in accordance with the invention, an electro-mechanical pipe fusion machine that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art and in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit of the appended claims.