A Tool-Changeable Robotic Part Manipulator A Tool-Changeable Robotic Part Manipulator Corey Stevens

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Transcript of A Tool-Changeable Robotic Part Manipulator A Tool-Changeable Robotic Part Manipulator Corey Stevens

  • A Tool-Changeable Robotic Part Manipulator Corey Stevens (RBE)

    Advisors: Craig Putnam (CS), Stephen Nestinger, PhD (ME)

    Abstract

    The goal of this project was to design and produce a robotic part manipulator to be

    used in a Vertical Machining Center. Project deliverables include a tool which is

    capable of being swapped in and out of a Vertical Machining Center’s spindle, able to

    flip a part over for a secondary machining operation, and operate autonomously to

    enable continuous machine operation. A prototype tool was developed capable of

    fulfilling each of these requirements as well as programming code to also handle a

    variety of machine errors.

    Project Goals

    • Demonstrate successful tool changes in and out of the spindle

    • Demonstrate part pickup and fixturing

    • After one side of the part has been machined, pick up the partially-completed part

    and flip it over for a secondary machining operation

    • Provide robot software capable of handling errors and improperly placed parts

    • Provide appropriate software and hardware documentation, including a user’s

    guide

    Mechanical Design Three initial designs were considered for the rotation and gripper functionality: electric

    motor, pneumatic gripper and bevel gear driven by spindle orientation. The pneumatic

    design was chosen because electric motors in a wet environment could lead to

    electrical shock and fire, and bevel gears would prove too difficult to integrate

    effectively. The chosen design features a rotary union, pneumatic coupling and

    fastening to provide pneumatic logic control over a rotary gripper module.

    Manufacturing • Nearly all components of the MQP required manufacturing

    • Solid modeling using SolidWorks allowed simulation of entire

    system prior to manufacturing

    • Components machined on the WPI VF-4SS, VM-3 VMCs and

    the SL-20 Turning Center

    • Turning of the custom 2.5”-16 thread required precision single

    point threading

    • Focus on Geometric Design and Tolerancing to ensure parts

    mate correctly when compared against the solid model

    Programming To ensure that the robot does not crash, or cause the machine tool to

    crash during operation, the program which controls the movement of

    the robot must be robust, capable of handling a variety of unforeseen

    circumstances, including, but not limited to:

    • Part misalignment

    • Out of parts

    • Loss of air pressure resulting in a dropped part

    • Broken tools

    Analysis • Force analysis conducted on the gripper with a 5lb force yielded

    0.0001” deflection downward

    • Acceptable value because estimated part weight would never

    exceed 5lbs

    • The tool weighs approximately 10.5lbs, which does not exceed

    12lbs, a weight restriction of the machine tool’s carousel

    Offset Verification & Error Detection • Uses the Haas Wireless Intuitive Probing System (WIPS)

    • Allows custom probing cycles to be designed such that the entire

    process may be automated using macro programming.

    • Verification of the X,Y,Z work coordinate offset to minimize error

    and maximize total accuracy of the system

    • Allows small errors present in the robot’s construction to be

    corrected for before the manufacturing process begins

    Rotary Union • Allows tool to rotate while the air supply remains

    stationary

    • Channels seal using PFTE (Teflon) O-rings

    • Low duty cycle (estimated 10%) allows excellent

    service life due to high o-ring lubricity and low

    wear

    • Custom 2.5”-16 thread design allows high

    clamping force to compress o-rings and ensures

    no rotation of the union’s free half while in the

    tool carousel

    Gripper • AGI Automation gripper unit AGM-10 allows

    180°rotary movement and gripping motion in one unit

    • Compact form factor reduces weight and overall

    tool diameter

    • Future improvements could include wireless

    sensor input to detect condition of the gripper

    and/or rotary movement with proximity or similar

    sensors

    Toolholder • Turned in the Haas VF-4 Vertical Machining

    Center to a custom 2.5”-16 thread

    • Maximizes rigidity and reduces error

    Offset Verification Using the

    Haas Wireless Intuitive

    Probing System

    Offset Verification Using the

    Haas Wireless Intuitive

    Probing System

    Prototype Gripper Modeled in

    SolidWorks

    Prototype Gripper Modeled in

    SolidWorks

    Rotary Union to Carry Sealing O-Rings Rotary Union to Carry Sealing O-Rings

    Gripper Design to Grip 1” Round Bar Stock Gripper Design to Grip 1” Round Bar Stock

    Sponsors Acknowledgements

    • William Weir, PhD

    • Torbjorn Bergstrom

    • Adam Sears

    • Peter Farkas

    • Michael Gibney

    • James Loiselle

    • Alexander Segala

    • Michael Fagan

    Prototype Robot as of 4/12/12 Prototype Robot as of 4/12/12

    Force Analysis Showing Maximum

    Deflection Area

    Force Analysis Showing Maximum

    Deflection Area