Ball Screw Grease Sealing for Clean Circulation Path Filling
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Solution Overview
Problem
Existing lubricant application methods for ball screw devices result in grease extrusion to exposed screw shaft portions, leading to dust and foreign matter adhesion, limited process flexibility, and inconsistent grease supply, making it difficult to adjust the application amount accurately.
Innovation Solution
A method and device that covers the screw shaft protruding from the nut with a covering member, supplies grease to the nut inner side, and rotates the screw shaft and nut to transfer grease to the infinite circulation path while preventing adhesion to the screw shaft, using a support unit and rotation mechanism to stabilize the nut.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If grease is supplied to the trajectory path by pushing with the screw shaft end portion, then grease can be transferred to the trajectory path, but grease extrudes to the exposed screw shaft portion and adheres dust and foreign matter
Solution Approach 1:
The patent divides the grease supply process into two independent stages: (1) supplying grease to the nut inner side, and (2) transferring grease to the trajectory path through relative rotation. This segmentation allows grease to be supplied without direct contact with the exposed screw shaft, preventing dust adhesion while ensuring adequate lubrication.
Solution Approach 2:
The patent applies grease to the nut inner side before performing the relative rotation that transfers grease to the trajectory path. This preliminary action ensures grease is positioned inside the nut where it will be naturally distributed to the trajectory path through rotation, rather than attempting to push grease directly to the trajectory path which causes extrusion to the exposed shaft.
2Reliability
If grease supply amount is increased to ensure grease reaches the trajectory path, then grease can reach the trajectory path even with high viscosity or small pressing force, but grease extrudes from the nut end surface on the opposite side
Solution Approach 1:
The patent uses dynamic relative rotation between the screw shaft and nut to transfer grease from the nut inner side to the trajectory path. This dynamic approach replaces the need for large pressing forces or excessive grease quantities, as the rotation naturally distributes grease along the trajectory path without causing extrusion from the opposite end.
Solution Approach 2:
The patent changes the grease transfer mechanism from static pressing to dynamic rotation, fundamentally altering how grease is distributed. This parameter change allows precise control over grease distribution, ensuring adequate lubrication without the harmful extrusion that occurs when excessive grease is supplied through pressing methods.
3Quantity of substance
If grease is transferred through clearance to the trajectory path inside the nut, then grease can reach the trajectory path, but the process cannot be separated from housing assembly and manufacturing flexibility is restricted
Solution Approach 1:
The patent separates the grease supply process from the housing assembly process by enabling grease to be supplied to the nut inner side independently. The grease is then transferred to the trajectory path through relative rotation of the screw shaft and nut, which can be performed as a standalone operation. This segmentation provides manufacturing flexibility and allows the same grease supply method to be applied to various products regardless of housing configuration.
4Manufacturing precision
If pressing force is small or grease viscosity is high, then grease may not reach the trajectory path with minimum amount, but increasing grease amount causes extrusion from opposite end
Solution Approach 1:
The patent employs dynamic relative rotation between the screw shaft and nut to transfer grease efficiently. This rotational mechanism generates centrifugal force and mechanical action that distributes grease along the trajectory path, enabling minimum grease quantities to reach the trajectory path effectively without causing extrusion, regardless of grease viscosity or pressing force variations.
Solution Approach 2:
The patent replaces the static pressing mechanism with a dynamic rotation-based grease transfer system. This substitution allows grease to be distributed through rotational motion rather than relying solely on pressing force, achieving reliable grease delivery to the trajectory path with minimal grease quantity and without causing extrusion from the opposite end.
Data Source
AI summary
A grease filling method for a ball screw device includes the steps of covering an outer periphery of a screw shaft protruding from one end portion of a nut with a covering member, supplying grease to a portion between a nut inner peripheral surface on one end portion side of the nut and the screw shaft, inserting the protruding screw shaft into a nut inner side while being covered with the covering member, bringing a tip of the covering member in an insertion direction closer to an end portion of an infinite circulation path on the one end portion side of the nut, and sending the grease supplied to the nut inner side to a region of the infinite circulation path, pulling out the covering member together with the screw shaft from the one end portion of the nut, and taking out the covering member from the screw shaft.