Spindle Device Radial Clearance Thermal Compensation
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Solution Overview
Problem
In spindle devices with double row cylindrical roller bearings, excessive reduction of radial inner clearance on the thrust load supporting bearing side leads to lubrication deterioration and improper rotation, particularly due to temperature differences caused by built-in motor drive systems and outer jacket cooling.
Innovation Solution
The spindle device employs a double row cylindrical roller bearing with a larger radial inner clearance on the thrust load supporting bearing side, achieved through a clearance fit between the outer ring and the housing, which allows radial expansion and maintains equal radial inner clearances between the roller row portions, thereby preventing lubrication deterioration and ensuring proper rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the radial inner clearance is reduced to increase spindle rigidity, then the rigidity is improved, but the cylindrical rollers may skid and cause abnormal contact and premature failure
Solution Approach 1:
The invention changes the clearance parameter by providing different radial inner clearances for different roller row portions. Specifically, the roller row portion on the thrust load supporting bearing side is designed with a larger clearance than the roller row portion on the counter side, allowing each portion to operate within optimal clearance ranges for both rigidity and reliability
2Productivity
If a built-in motor drive system is used to compactize the device and provide high output, then the device complexity is reduced and productivity is improved, but the temperature difference between inner ring and outer ring increases causing excessive radial inner clearance reduction
Solution Approach 1:
The invention applies local quality by differentiating the clearance characteristics for different roller row portions based on their thermal environments. The roller row portion on the thrust load supporting bearing side, which experiences greater temperature differences, is given a larger initial clearance to compensate for thermal contraction and maintain adequate operating clearance
Solution Approach 2:
The invention changes the clearance parameter to account for thermal effects. By providing a larger radial inner clearance on the thrust load supporting bearing side, the design compensates for the excessive clearance reduction caused by temperature differences from the built-in motor and outer jacket cooling
3Reliability
If the radial inner clearance is reduced to suppress skidding, then skidding is suppressed, but the lubrication deteriorates and improper rotation occurs
Solution Approach 1:
The invention changes the clearance parameter by providing different radial inner clearances for different roller row portions. The roller row portion on the thrust load supporting bearing side is designed with a larger clearance to maintain adequate lubrication film thickness and prevent lubrication deterioration, while still preventing skidding through the overall clearance control
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 configuration maintains the rigidity and operational stability of the spindle device by preventing excessive radial inner clearance reduction, minimizing thermal influences, and ensuring consistent lubrication across the bearing, thus avoiding issues like improper rotation.
Implementation Method 1
the temperature difference between the inner ring and the outer ring in the bearing tends to become large... excessive reduction of the radial inner clearance in the roller row portion on the thrust load supporting bearing side
Data Source
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AI summary
This invention is applied to a spindle device used in, for example, a machine tool. The spindle device includes a double row cylindrical roller bearing (4) and a thrust load supporting bearing (5F, 5R) both interposed between a front side portion of a spindle (1) and a housing (2) and arranged from a front side end in this order. An amount of clearance of the roller row portion (4B) on the thrust load supporting bearing side is larger than that of the roller row portion (4A) on the counter thrust supporting bearing side. Engagement between the outer ring (42) of the double row cylindrical roller bearing (4) and a housing (2) is performed by clearance fit employed at the roller row portion (4B) on the thrust load supporting bearing side.