Non-Round Grinding Machine Development (On-going Project)

Non-Round Grinding Machine Development (On-going Project)

Automobile cam-lobe grinding

Automobile cam-lobe grinding (Component – green | Grinding wheel – orange)

 

Introduction

The grinding of non-circular contours on a cylindrical grinding machine is known as non-round grinding. This is achieved by interpolation in the wheel-infeed (linear) – X-axis and the work-piece (rotation) – C-axis.

 

Need

The major need for non-round grinding is in the automotive sector. India, with an emerging 2-wheeler and 4-wheeler automotive segment is experiencing increasing demands for indigenous non-round grinding applications. Examples of non-round components primarily ground are camlobes of camshafts of various sizes. Many other non-symmetric and non circular parts are used in mechanical actuators, rotary pumps, punch and other tooling, etc. Especially in the developing economies, these are today made by a series of milling processes, with poor form accuracy and surface finish. Many of these can be made to higher accuracies for better performance using non-round grinding processes.

 

Project Definition and Organization

To do non-round grinding, there are two main components:

  • Capable machine tool:
    • High rigidity
    • Low moving mass
    • High acceleration
    • Zero backlash
    • Wheel diameter (limited by the part profile)
  • CNC Programming:
    • C-X (workhead rotation and wheelhead in-feed) interpolation profile generation
    • Optimization of feed profile based on the grinding process and drive constraints
    • GUI Development

3-lobed internal profile grinding

 

We organized the project into 4 sections:

  • Product Management
    • Identify the market’s needs and requirements.
    • Establish class of components to target and therefore, what specifications of machine to build.
  • Hardware development
    • Development of the machine tool capable of non-round grinding with:
      • Aluminum Oxide, and
      • Cubic Boron Nitride (CBN) wheels.
    • For both internal and external cam profiles.
  • Software development
    • Development of the software with a GUI package which will run on an Industrial PC on the machine.
    • It will act as a “pre-processor” and interfaced with the CNC system for machine control.
    • Functions of “pre-processor”:
      • Loading/ Generating non-round component profiles
      • Smoothing the loaded profiles
      • Enter the grinding process data
      • Generation of feed-profile and CNC code
      • Analysis of feed-profile and optimization
      • Corrections to the profile
  • Integration, Testing, and Part Prove-Out
    • CNC and Servo parameters – their role in achieving the desired motion profile
    • Knowhow of the non-round grinding process
    • Proving out the quality and cycle-time requirements for various components
    • Machine testing

 

My Role

I am responsible for the Software development and its integration into a “pre-processor” unit for the machine, interfacing with the CNC system, proving out of the part and overall project management.

Wheel tangents on work profile| To check interference

Wheel mapped as tangents to work-profile| To check interference

Radius of curvature of component profile

Radius of curvature of component profile

 

Major Areas of Learning

  •  Software Development
    • Algorithm development
      • Linear Algebra
      • Matrix Algebra
    • GUI Development
      • Parsing (converting to CNC code)
    • Optimization
      • Non-linear optimization
    • Languages
      • Python (Numpy + Scipy)
  • Grinding Process
    • Contribution of process parameters to the part quality
    • Creep feed grinding
  • CNC and Servo Parameters
    • Effect of various parameters in the motion profile
    • Compensations schemes
    • Feedback and Feed-forward controls
    • Servo Tuning

 

Accomplishments

  • Non-round grinding algorithm development
    • Load component profile in a variety of formats
    • Maximum diameter of wheel possible
    • Check interference
    • Smoothing of profile
    • Various grinding modes
  • Tested the algorithms on machine to verify the correctness of the profile.
  • This work has resulted in commercial impact to the company by getting orders for non-round grinding applications.
Evaluation of Drive Constraints in cam-lobe grinding

Evaluation of drive constraints in cam-lobe grinding | Constant work rpm grinding mode.

Current work

Software Development

  • GUI Development
  • Feed-rate optimization
  • Interfacing with CNC system
  • CNC and Servo Tuning and Parameter setting