Angular Ball Bearing Groove Geometry for Low-Heat Spindle Operation
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Solution Overview
Problem
Existing angular ball bearings used in machine tool spindles experience increased heat generation and reduced durability due to high surface pressure and centrifugal forces at high rotation speeds, leading to issues like bearing seizure and thermal displacement, which affect machining accuracy.
Innovation Solution
The angular ball bearing is designed with specific groove curvature radius ratios for the inner and outer rings (54% to 57% and 51% to 58%, respectively) and uses alloy steel with controlled compositions of carbon, silicon, manganese, chromium, and other elements to stabilize the martensite structure, reducing heat generation and preventing inclusion-initiated flaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the groove curvature radius ratios of the outer ring and inner ring are set to be large (50.5%-60%), then the heat generation is reduced, but the surface pressure of the contact portion increases and the stress near the raceway surface increases, leading to inclusion-initiated flaking and reduced durability
Solution Approach 1:
The invention optimizes the groove curvature radius ratios to specific ranges (inner ring: 54%-57%, outer ring: 51%-58%) rather than using uniformly large values. This parameter optimization balances heat generation reduction with surface pressure control, preventing inclusion-initiated flaking while maintaining low heat generation. The precise parameter ranges resolve the contradiction by finding the optimal compromise point.
Solution Approach 2:
The invention employs alloy steel with specific compositional ranges (C: 0.85%-1.15%, Si: 0.40%-0.90%, Mn: 0.55%-1.20%, Cr: 1.30%-1.90%, Mo: ≤0.30%, Ni: ≤0.30%, Cu: ≤0.20%, S: ≤0.025%, P: ≤0.020%, O: ≤15 ppm) to enhance material strength and resistance to inclusion-initiated flaking. This composite material approach allows the bearing to withstand higher surface pressures without flaking, resolving the durability issue while maintaining the heat-reducing groove geometry.
2Productivity
If the rotation speed of the angular ball bearing is increased to improve machining efficiency, then the productivity increases, but the heat generation and centrifugal forces increase, leading to bearing seizure and thermal displacement
Solution Approach 1:
The optimized groove curvature radius ratios (inner ring: 54%-57%, outer ring: 51%-58%) reduce spin slip and heat generation at high rotation speeds. This allows the bearing to operate efficiently at high speeds (dmn ≥ 800,000) without excessive heat generation, resolving the contradiction between productivity improvement and heat control.
3Loss of energy
If the groove curvature radius ratios are set to large values to reduce heat generation, then the heat generation amount decreases, but the stress generated in the portion near the surface of the raceway surface increases, causing inclusion-initiated flaking
Solution Approach 1:
The invention specifies precise groove curvature radius ratio ranges (inner ring: 54%-57%, outer ring: 51%-58%) that optimize the balance between heat generation reduction and stress distribution. These parameter changes ensure low heat generation while maintaining sufficient strength to prevent inclusion-initiated flaking.
Solution Approach 2:
The alloy steel composition (C: 0.85%-1.15%, Si: 0.40%-0.90%, Mn: 0.55%-1.20%, Cr: 1.30%-1.90%, Mo: ≤0.30%, Ni: ≤0.30%, Cu: ≤0.20%, S: ≤0.025%, P: ≤0.020%, O: ≤15 ppm) enhances the material's resistance to inclusion-initiated flaking through controlled alloying. This allows the use of optimized groove geometry that reduces heat generation without compromising strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively reduces heat generation and prevents flaking, ensuring a long service life and low manufacturing costs, making it suitable for high-speed machine tool spindle applications.
Implementation Method 1
at least the inner ring or the outer ring is made of alloy steel containing 0.85 mass% to 1.15 mass% of C, 0.40 mass% to 0.90 mass% of Si, 0.55 mass% to 1.20 mass% of Mn, 1.30 mass% to 1.90 mass% of Cr, 0.30 mass% or less of Mo, 0.30 mass% or less of Ni, 0.20 mass% or less of Cu, 0.025 mass% or less of S, 0.020 mass% or less of P, and 15 mass ppm or less of O
Implementation Method 2
a plurality of balls rollably provided between the inner ring raceway groove and the outer ring raceway groove
Data Source
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AI summary
Provided is an angular ball bearing that reduces the amount of heat generated, suppresses separation originating from inclusions even if surface pressure at contact sites becomes high, is low in cost, and has long life. This angular ball bearing comprises: an inner race that has an inner raceway groove with a circular-arc-shaped cross-section in an outer peripheral surface; an outer race that has an outer raceway groove with a circular-arc-shaped cross-section in an inner peripheral surface; and a plurality of balls disposed so as to be able to roll between the inner raceway groove and the outer raceway groove. The groove curvature radius ratio Ri of the inner raceway groove to the ball diameter is 54-57%, the groove curvature radius ratio Ro of the outer raceway groove to the ball diameter is 51-58%, and at least the inner race and the outer race comprise alloy steel that includes 0.85-1.15% by mass of carbon, 0.40-0.90% by mass of silicon, 0.55-1.20% by mass of manganese, 1.30-1.90% by mass of chromium, 0.30% by mass or less of molybdenum, 0.30% by mass or less of nickel, 0.20% by mass or less of copper, 0.025% by mass or less of sulfur, 0.020% by mass or less of phosphorus, and 15 ppm by mass or less of oxygen, with the remainder being iron and unavoidable impurities.