Ball Screw Return Path Sealing Against Grease Leakage
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Solution Overview
Problem
Existing ball screws face issues with grease leakage and foreign matter entry due to gaps between the circulation component and the through hole in the nut, which can contaminate the surroundings and reduce service life.
Innovation Solution
A ball screw design featuring a sealing member made of resin or rubber that seals the gap between the nut's through hole and the circulation component, preventing grease leakage and foreign matter entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a circulation component made of metal is used to improve heat resistance and strength, then heat resistance and strength are improved, but grease leakage occurs from the gap between the circulation component and the through hole
Solution Approach 1:
A sealing member made of resin is introduced as an intermediary component between the metal circulation component and the through hole. This sealing member fills the gap and prevents grease leakage while allowing the metal circulation component to maintain its strength and heat resistance properties.
Solution Approach 2:
The solution combines different materials (metal circulation component and resin sealing member) to achieve both strength/heat resistance and grease leakage prevention. The composite structure leverages the advantages of each material type.
2Object-generated harmful factors
If an O-ring groove is processed in the nut to attach an O-ring for sealing, then grease leakage is prevented, but manufacturing cost increases due to additional processing
Solution Approach 1:
The sealing function is extracted from the nut structure itself and transferred to a separate sealing member. This eliminates the need for additional processing of the nut (such as O-ring groove machining) while maintaining effective grease leakage prevention.
Solution Approach 2:
A separate sealing member acts as an intermediary that provides the sealing function without requiring modifications to the existing nut structure, thereby avoiding additional manufacturing costs.
3Productivity
If the circulation component is formed along the tangential direction of the load raceway to improve ball circulation, then ball circulation is improved, but a gap must be maintained between the circulation component and the through hole which allows grease leakage
Solution Approach 1:
The sealing member serves as an intermediary that allows the circulation component to be positioned in the optimal location for ball circulation while simultaneously preventing grease leakage from the gap between the circulation component and the through hole.
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
The design effectively prevents grease leakage and foreign matter ingress, improving heat resistance and enabling high-speed operation by ensuring smooth ball circulation.
Implementation Method 1
a sealing member made of resin or rubber and configured to seal at least a part of a gap between an inner peripheral surface of the through hole of the nut and an outer peripheral surface of the circulation component
Data Source
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AI summary
A ball screw (10) comprises: a screw shaft (20) formed with a screw shaft-side raceway groove (21); a nut (30) formed with a nut-side raceway groove (31) and having a through-hole (32) communicating an outer peripheral surface (33) with the nut-side raceway groove (31); a plurality of balls (26) that roll on a load raceway (25); and a circulating part (40) that is attached to the through-hole (32) to form a ball returning path (48) for circulating the balls (26). The ball screw (10) has a sealing member (50) made of resin or rubber that seals at least a part of a gap between an inner peripheral surface of the through-hole (32) of the nut (30) and an outer peripheral surface of the circulating part (40). This makes it possible to prevent leakage of grease through the gap between the circulating part and the through-hole formed on the nut, and entry of external foreign matter through the gap.