Integral Cylindrical Bearing Nut Member Step Actuator
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Solution Overview
Problem
Conventional step actuators experience significant feeding errors due to axial gaps between the cylindrical bearing and the nut member, which also increase material and labor costs due to the number of parts required for assembly.
Innovation Solution
A cylindrical bearing is integrally formed with the nut member at the upper part, eliminating axial gaps by using grooves and protrusions for secure engagement and potentially undergoing swaging or ultrasonic treatment for enhanced coupling, and utilizing an insert injection molding process for construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cylindrical bearing is separately coupled to the nut member using conventional methods (stop ring, bearing support), then the bearing can be assembled and disassembled, but axial gaps are created at the coupled area causing feeding errors
Solution Approach 1:
The cylindrical bearing and nut member are merged into a single integral structure through insert injection molding, eliminating the axial gaps that cause feeding errors while reducing the total number of parts. The bearing is formed directly on the nut member without requiring separate coupling components.
Solution Approach 2:
The mechanical coupling system (stop ring, bearing support, multiple fastening points) is replaced with an injection molding process that creates an integral structure. This substitution eliminates the need for mechanical assembly and disassembly while preventing axial gaps.
2Ease of manufacture
If multiple separate parts (cylindrical bearing, nut member, stop ring, bearing support) are used for assembly, then flexibility and maintainability are improved, but material cost and labor cost increase
Solution Approach 1:
The cylindrical bearing and nut member are combined into one integrated component through insert injection molding, reducing the number of parts that need to be manufactured, stored, and assembled. This directly lowers material costs and assembly labor costs.
Solution Approach 2:
The integrated structure serves multiple functions simultaneously: the cylindrical bearing provides rotational support while the nut member provides the threaded engagement, eliminating the need for separate coupling components and reducing overall assembly complexity.
3Manufacturing precision
If conventional coupling methods are used to connect the cylindrical bearing and nut member, then the parts can be manufactured separately, but axial gaps remain causing significant feeding errors
Solution Approach 1:
The mechanical coupling process is replaced with injection molding that creates an integral structure, eliminating axial gaps. The molding process directly forms the bearing on the nut member, ensuring precise alignment and zero gap without complex mechanical fastening.
Solution Approach 2:
The manufacturing approach changes from mechanical assembly with tolerance stacks to a monolithic injection molded structure. This parameter change in the manufacturing process fundamentally eliminates axial gaps while maintaining ease of manufacture through standard injection molding techniques.
Data Source
AI summary
The invention relates generally to a step actuator, in which a lead screw coupled with a screw thread formed in a nut member is installed in a rotor magnet and moves back and forth in an axial direction responding to a rotation of the rotor to transmit power in an axial direction. A cylindrical bearing for rotatably supporting the nut member is disposed at an upper part of the nut member and integrally formed therewith, to fundamentally remove a gap in the axial direction in the coupled area between the cylindrical bearing and the nut member, thereby significantly reducing the feeding error of a rotator in the axial direction when the lead screw moves back and forth in the axial direction, and reducing the number of parts to be assembled to lower the material cost and the labor cost for assembly.