HOBBING MACHINE

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• Q1: What is a Hobbing Machine?
  Ans: A Hobbing Machine is a specialized machine used to cut gears, splines, and sprockets. It uses a rotating cutter called a hob to progressively cut teeth into a rotating workpiece.
• Q2: Write four uses of Hobbing Machines.
  Ans: Uses of Hobbing Machines:

  • ➔ Cutting spur gears
  • ➔ Cutting helical gears
  • ➔ Cutting splines and shafts
  • ➔ Producing sprockets and worm wheels
• Q3: Briefly discuss the working principle of the Hobbing Machine.
  Ans: The Hobbing Machine works on the principle of generating gear teeth by continuous relative motion between the rotating hob and the workpiece. The hob cuts progressively as both rotate, producing precise teeth.
• Q4: Briefly discuss the construction of the Hobbing Machine.
  Ans: The Hobbing Machine is built with the following main parts:
  1. Bed
  2. Column
  3. Hob Head
  4. Work Table
  5. Gear boxes (Speed, Feed, and Indexing gears)
  6. Hob Slide and Slide Mechanisms
  7. Flywheel and Drive System
  These parts work together to ensure precise gear cutting.
• Q5: Name the accessories of a Hobbing Machine.
  Ans: Accessories of a Hobbing Machine include:

  • ➔ Crank Handle
  • ➔ Speed Change Gears
  • ➔ Indexing Change Gears
  • ➔ Grease Gun
  • ➔ Hob Head
  • ➔ Flywheel
• Q6: What is a Crank Handle in a Hobbing Machine?
  Ans: A Crank Handle is a manually operated lever used to adjust or rotate parts of the Hobbing Machine, such as moving the work table or setting the hob position.
• Q7: What are Speed Change Gears in a Hobbing Machine?
  Ans: Speed Change Gears control the rotation speed of the workpiece and hob, allowing the machine to cut gears at the required rate for different sizes and modules.
• Q8: What are Indexing Change Gears in a Hobbing Machine?
  Ans: Indexing Change Gears are gears that control the rotation ratio between the hob and the workpiece, ensuring accurate spacing of gear teeth.
• Q9: What is a Grease Gun in a Hobbing Machine?
  Ans: A Grease Gun is a lubrication tool used to apply grease to moving parts of the machine to reduce friction and wear.
• Q10: What is a Bed in a Hobbing Machine?
  Ans: The Bed is the base of the Hobbing Machine. It provides support and rigidity for all other parts of the machine.
• Q11: What is the Main Drive Box in a Hobbing Machine?
  Ans: The Main Drive Box houses the main gears and shafts that transmit power from the motor to the hob and workpiece.
• Q12: What is a Feed Change Gear Bracket in a Hobbing Machine?
  Ans: The Feed Change Gear Bracket holds gears that control the feed movement of the work table, determining how much the table moves per hob rotation.
• Q13: What is a Speed Change Gear Bracket in a Hobbing Machine?
  Ans: The Speed Change Gear Bracket supports gears that control the rotational speed of the hob and workpiece.
• Q14: What is an Indexing Change Gear Bracket in a Hobbing Machine?
  Ans: The Indexing Change Gear Bracket holds gears used to accurately divide the workpiece rotation for correct tooth spacing.
• Q15: What is a Hob Head in a Hobbing Machine?
  Ans: The Hob Head holds the hob cutter and can rotate and move to cut the teeth on the workpiece at the correct angle and depth.
• Q16: What is a Fly Wheel in a Hobbing Machine?
  Ans: The Flywheel stores rotational energy to maintain smooth rotation of the workpiece and hob, helping to reduce speed fluctuations.
• Q17: Briefly discuss the Column and its importance in a Hobbing Machine.
  Ans: The Column is the vertical support structure of the Hobbing Machine. It holds the hob head and gear boxes in place, providing stability during cutting operations.
• Q18: Briefly discuss the Hob Slide and its importance in a Hobbing Machine.
  Ans: The Hob Slide is a moving part that carries the hob and allows precise adjustment of its position. It ensures accurate tooth depth and helix cutting.
• Q19: How to cut Spur Gear on a Hobbing Machine?
  Ans: Steps to cut a Spur Gear:
  1. Mount the workpiece on the table.
  2. Fix the hob in the hob head.
  3. Set the hob and table alignment for parallel axes.
  4. Adjust speed and feed using change gears.
  5. Rotate hob and workpiece simultaneously to cut teeth.
  6. Complete one revolution per tooth until gear is finished.
• Q20: How to cut Helical Gear on a Hobbing Machine?
  Ans: Steps to cut a Helical Gear:
  1. Mount the workpiece at an angle on the table according to the helix angle.
  2. Fix the hob in the hob head.
  3. Set the table to move at the lead rate for helix cutting.
  4. Adjust speed and feed using change gears.
  5. Rotate hob and workpiece while moving the table to generate the helical teeth.
  6. Complete the process until all teeth are cut.