Threaded Nut Recess Forming for Ball Screw Drive Production

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Solution Overview

Problem

Existing methods for producing threaded nuts for ball screw drives are not economically viable, especially for large quantities, due to the need for precise machining and the use of peripheral stops which require complex and costly manufacturing processes.

Innovation Solution

A method involving non-cutting forming processes like cold extrusion and warm forging to create a recess with a stop surface on the threaded nut, eliminating the need for additional components and allowing for precise production of complex geometries with reduced material usage and processing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If machining is used to produce the projection on the threaded nut, then manufacturing precision and strength are improved, but productivity decreases and processing costs increase

Engineering Contradiction:
Improvedimensional accuracy of projectionVSAvoidproduction rate
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent replaces traditional mechanical machining processes with a cold extrusion forming process. The projection is formed by plastic deformation of the material under high pressure in a die, rather than by removing material through cutting tools. This substitution maintains manufacturing precision while dramatically improving productivity and reducing processing costs.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state and parameters of the material during forming. By applying high pressure and controlled deformation parameters during cold extrusion, the material flows to form the precise geometric shape of the projection. The forming parameters (pressure, temperature, deformation rate) are optimized to achieve both precision and efficiency.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If additional components like pins are used to form the stop surface, then ease of manufacture is improved, but device complexity increases

Engineering Contradiction:
Improvemanufacturability of stop surfaceVSAvoidnumber of components
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges the stop surface formation into the main body of the threaded nut by forming it as an integrated feature during the cold extrusion process. The stop surface is created as part of the die cavity geometry, eliminating the need for separate pins or additional components. This reduces device complexity while maintaining ease of manufacture through a single-forming operation.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If cold extrusion is used to form the recess and stop surface, then productivity is improved and processing costs decrease, but manufacturing precision may be compromised

Engineering Contradiction:
Improveproduction rateVSAvoiddimensional accuracy of recess and stop surface
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent replaces traditional machining operations with cold extrusion forming. The high-pressure plastic deformation process allows for precise replication of the die cavity geometry in the formed part. This substitution achieves both high productivity through rapid forming and high manufacturing precision through accurate die design and material flow control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent incorporates the precision requirements into the preliminary die design. The die cavity is precisely manufactured to the required dimensional tolerances before the forming process. By preparing the tooling in advance with high precision, the subsequent high-volume forming operations automatically produce parts with consistent precision, maintaining both productivity and manufacturing accuracy.

Inventive Principle:
Principle #10Preliminary action

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 method enables the economical production of threaded nuts with high dimensional accuracy and surface quality, particularly suitable for large quantities, by forming the stop surface and recess in a single process, enhancing the precision and load-bearing capabilities of the stop surface.

Implementation Method 1

a blank is formed in a forming process by forming material to form the recess, the bottom and the stop surface and the peripheral wall being connected to one another in one piece

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Implementation Method 2

Cold extrusion is suitable for the invention. According to DIN 8583, impact extrusion is part of pressure forming. Solid forming enables the production of hollow and solid bodies through a single-stage or multi-stage manufacturing process. In this process, the material is made to flow under the influence of high pressure.

Methodology Applied
Scientific EffectCold extrusion: Cold-forming

Implementation Method 3

Warm forging is carried out in a temperature range from 600 °C to 950 °C. Warm forming is characterized by high dimensional accuracy and surface quality, similar to cold forming. Warm forging enables the production of complex geometries, whereby the forming forces can be reduced compared to cold forging.

Methodology Applied
Scientific EffectWarm forging:

Data Source

PatentEP2464895B1Method for producing a threaded nut of a ball screw drive
Publication Date: 2018.10.03 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP2464895B1 patent drawingFigure 1
  • EP2464895B1 patent drawingFigure 2~3
  • EP2464895B1 patent drawingFigure 4

AI summary

A method for producing a threaded nut (10, 26) of a screw drive, in particular of a ball screw drive (7, 24), which threaded nut (10, 26) has, at one axial end, a recess (45) which is open on the front side and extends over a circumferential section, wherein said recess (45) is radially delimited by a circumferential wall of the threaded nut (10, 26), and wherein said recess (45) is axially delimited by a bottom (54) which is formed on the threaded nut (10, 26), and wherein said recess (45) is delimited in the circumferential direction by a stop surface (47) for a projection (44), which stop surface (47) is formed on the threaded nut (10, 26), produced according to the following steps: a blank is formed in a forming process by forming of material with the formation of the recess (45), wherein the bottom (54) and the stop surface (47) and the circumferential wall are connected integrally to one another.