Ball Screw Grease Filling for Clean, Precise Circulation Path Lubrication
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Solution Overview
Problem
Existing grease filling methods for ball screw devices often result in grease adhesion to exposed screw shafts, incomplete lubrication, and limited flexibility in grease application amounts, restricting product variability and manufacturing efficiency.
Innovation Solution
A grease filling method and device that uses a covering member to apply grease directly to the infinite circulation path within the nut, preventing adhesion to the screw shaft and allowing precise control over grease quantity, with features like inclined nozzle discharge and a sleeve with a thin side wall to ensure efficient and uniform lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If grease is supplied to the trajectory path by assembling the housing to the ball screw assembly, then the grease can reach the trajectory path, but the process cannot be separated and degree of freedom in step setting is restricted
Solution Approach 1:
The invention separates the grease supply process from the housing assembly process by introducing a temporary grease supply hole in the housing and a grease supply port in the nut. This allows grease to be supplied independently before final assembly, enabling process separation and flexible step setting while maintaining manufacturing ease.
Solution Approach 2:
The grease is supplied to the nut in advance through the grease supply port before the housing is assembled. This preliminary action allows the grease application step to be completed independently, providing flexibility in process sequencing while ensuring proper lubrication before final assembly.
2Quantity of substance
If grease is transferred by using a clearance to the trajectory path inside the nut, then the grease can reach the trajectory path, but it is not possible to complete the application with a minimum required amount of grease
Solution Approach 1:
The invention extracts the grease supply function from the housing assembly process by providing a dedicated grease supply port in the nut and a separate grease supply hole in the housing. This allows precise control of grease quantity and placement directly at the trajectory path without relying on clearance-based transfer, minimizing grease usage while ensuring complete coverage.
3Reliability
If the screw shaft is rotated to push out grease, then the grease can enter the trajectory path, but grease may be extruded to the exposed portion of the screw shaft causing poor appearance
Solution Approach 1:
The invention introduces a grease supply port in the nut as an intermediary mechanism to deliver grease directly to the trajectory path. This eliminates the need to rotate the screw shaft for grease extrusion, ensuring reliable grease delivery to the balls while preventing grease from reaching the exposed screw shaft portion and causing appearance issues.
Data Source
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AI summary
According to one embodiment, 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 by relatively rotating the screw shaft and the nut, 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 by relatively rotating the screw shaft and the nut in an opposite direction, and taking out the covering member from the screw shaft.