Centreless grinding setup: What is the typical surface speed range of the regulating (control) wheel that drives and guides the workpiece?
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A5 to 15 m/min
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B15 to 60 m/min
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C60 to 90 m/min
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D90 to 120 m/min
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E120 to 180 m/min
Answer
Correct Answer: 15 to 60 m/min
Explanation
Introduction / Context:In centreless grinding, the workpiece is supported between a high-speed grinding wheel and a slower, rubber-bonded regulating wheel. The regulating wheel sets work speed, provides axial feed (in through-feed mode), and ensures steady control for accuracy and roundness. Selecting the proper regulating wheel surface speed is essential for stability and surface finish.
Given Data / Assumptions:
- Conventional through-feed or in-feed centreless grinding machine.
- Typical industrial ranges for steel components.
- Rubber or resin-bonded regulating wheels with controllable inclination angle.
Concept / Approach:The regulating wheel must run much slower than the grinding wheel (which commonly runs in the range of 1800–3000 m/min or more). Practical handbooks specify a typical regulating speed window wide enough to maintain traction and allow controlled feed without burning or chatter.
Step-by-Step Solution:
Identify the slow, control function → regulating wheel sets work speed.Typical practice chooses tens of m/min for regulation, not hundreds.Hence, 15–60 m/min is the accepted practical range for many jobs.Verification / Alternative check:Machine tool manuals and process sheets list regulating wheel surface speeds in the tens of m/min, confirming the stated range.
Why Other Options Are Wrong:
- 5–15 m/min: often too slow, risks loss of control and productivity.
- 60–90 or 90–120 or above: too fast for regulating function; may cause instability and excessive feed.
Common Pitfalls:Confusing grinding wheel speed with regulating wheel speed; they differ by an order of magnitude.
Final Answer:15 to 60 m/min