Ball Screw Assembly With Pressed Return Channels for Low-Cost Production

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Solution Overview

Problem

The production of ball screw drives is complex and costly due to the extensive machining required for the transfer channel in the spindle nut, which involves drilling or milling, making mass production challenging.

Innovation Solution

The use of simultaneously pressed axially parallel channels in the lateral surface of the spindle nut, combined with a drive element that engages in these channels for torque transmission, reduces production complexity and cost through a cold forming process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional drilling or milling processes are used to create transfer channels in the spindle nut, then the channels can be formed, but the production complexity and cost increase significantly

Engineering Contradiction:

Improveproduction complexityVSAvoidchannel geometry precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the manufacturing parameter from thermal/mechanical removal (drilling/milling) to cold forming (pressing). The pressing process uses controlled material displacement to form the transfer channels, achieving the required geometric precision without the complexity and cost of traditional machining operations.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the complex mechanical machining system (drills, mills, multiple setup operations) with a simpler pressing mechanism. The pressing device forms the channels through controlled material flow, eliminating the need for complex machining equipment and multiple operational steps.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If traditional drilling or milling processes are used to create transfer channels in the spindle nut, then the channels can be formed, but the production cost increases

Engineering Contradiction:

Improveproduction costVSAvoidmachining time

Core Design Contradiction:

Ease of manufactureVSLoss of time

Solution Approach 1:

The pressing operation forms the transfer channels in a single preliminary action before final assembly. The cold forming process creates the channels and simultaneously prepares the material flow paths, eliminating the need for subsequent machining operations and reducing total production time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent merges multiple operations (channel formation, material compaction, and surface finishing) into a single pressing operation. This consolidation eliminates the need for separate machining steps, reducing both production cost and machining time while maintaining channel geometry precision.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If the transfer channel is created by drilling or milling, then the channel can be formed, but the production process becomes complex and time-consuming

Engineering Contradiction:

Improvemass production efficiencyVSAvoidproduction process complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The pressing process segments the formation of multiple transfer channels into simultaneous independent mold cavities or sequential pressing stages. This allows parallel production of channels without increasing overall process complexity, thereby improving mass production efficiency while keeping the device relatively simple.

Inventive Principle:

Principle #1Segmentation

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 approach simplifies the production process by integrating axial center and parallel channels through material displacement during pressing, allowing for efficient and cost-effective manufacturing of ball screw drives.

Implementation Method 1

This approach simplifies the production process by integrating axial center and parallel channels through material displacement during pressing

Methodology Applied

Scientific EffectMaterial displacement: Deformation

Data Source

PatentEP4361464A1Ball screw assembly and use of a ball screw as an actuating element in a brake booster system or as an actuating element in a brake

Publication Date: 2024.05.01 SFS GROUP INTERNATIONAL AG

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Figure 3

AI summary

A ball screw drive (100) comprises a threaded spindle (110) and a spindle nut (120) that coaxially encloses the threaded spindle (110), at least partially. At least two radially outwardly open channels (150, 150') are also provided, aligned parallel to the axis and produced by simultaneous pressing into the cylindrical surface. These channels (150, 150') are open to a common end face (160) of the spindle nut (120). A plurality of balls (140) circulate in a helical ball channel (170) in the space between the threaded spindle (110) and the spindle nut (120). At least one ball return (200) is provided, comprising two ball deflections (210, 210') and a transfer channel (220) running between them. Furthermore, there exists a drive element (300) which is coaxially connected to the spindle nut (120) and is designed to apply a torque to the spindle nut (120).According to the invention, the operative connection between the drive element (300) and the spindle nut (120) is formed at least by a contact surface (180) with a connection contour and a drive element (310) which is designed such that, in the assembled state, it engages in one of the channels (150, 150') of the spindle nut (120). Such a ball screw drive can be used, for example, as an actuating element in a brake booster system or as an actuating element in a brake.