Variable Pitch Screw Rolling Die Curved Non-Parallel Depressions

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Solution Overview

Problem

Manufacturing screws with continuous threads and variable pitch is inefficient due to significant material loss and extended machining time, limiting throughput.

Innovation Solution

A rolling die with curved non-parallel depressions is used to form screws, allowing for the creation of screws with variable thread pitches with minimal material transfer and low rolling pressure, and a second embodiment adjusts the slope of the depressions to compensate for volume defects by redistributing material along the axis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If milling is used to manufacture screws with variable thread pitch, then manufacturing flexibility is improved, but material loss increases and machining time extends

Engineering Contradiction:

Improvemanufacturing flexibilityVSAvoidmachining throughput

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent replaces the traditional mechanical milling process with a rolling process. Instead of removing material through cutting tools, the thread profile is formed by rolling a blank between two rolling dies with complementary profiles. This substitution of the mechanical system fundamentally changes the material removal mechanism to a plastic deformation process, enabling variable pitch threads to be formed without the material waste and time consumption associated with milling operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes parameter changes in the rolling process to achieve variable thread pitch. By varying the rolling speed, diameter, or profile of the rolling dies during the forming process, different thread pitches can be created along the length of the screw. This allows the same rolling process to produce threads with continuously varying pitch, maintaining manufacturing flexibility while dramatically improving productivity and reducing material loss.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If conventional rolling with straight parallel depressions is used, then manufacturing simplicity is maintained, but variable pitch thread formation becomes impossible

Engineering Contradiction:

Improverolling process simplicityVSAvoidthread pitch variation capability

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent applies curvature to the rolling die profiles to enable variable pitch thread formation. Instead of using straight parallel depressions, the rolling dies feature curved profiles where the spacing and orientation of the depressions vary along the rolling direction. This curvature allows the rolling process to imprint threads with varying pitch onto the blank, maintaining the simplicity of the rolling method while adding the capability to produce variable pitch threads.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Force

If volume transport in axial direction is avoided, then rolling pressure is reduced, but material distribution along the screw may become uneven

Engineering Contradiction:

Improverolling pressureVSAvoidmaterial distribution uniformity

Core Design Contradiction:

ForceVSManufacturing precision

Solution Approach 1:

The patent applies local quality by designing the rolling die profile to provide different functions at different locations. The rolling die is configured with varying depression patterns along its length, where the spacing, depth, and orientation of depressions are locally optimized to control material flow and distribution. This local variation in die geometry ensures that material is distributed evenly along the screw length while maintaining reduced rolling pressure, as each section of the die is tailored to the specific requirements of that region.

Inventive Principle:

Principle #3Local quality

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 method enables quick and economical production of screws with variable thread pitches, maintaining constant volume per unit length and reducing rolling pressure, while preventing tilting and ensuring high-quality thread formation.

Implementation Method 1

a blank (16) is rolled between two rolling dies (24, 52), wherein in each rolling die a rolling profile is formed that comprises a host of curved non-parallel depressions (34)

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentUS9017176B2Method and rolling die for producing a screw with a variable thread pitch

Publication Date: 2015.04.28 LUDWIG HETTICH

AI summary

Disclosed herein is a method for manufacturing a screw comprising a continuous thread with a variable thread pitch, in which method a blank is rolled between two rolling dies, wherein in each rolling die a rolling profile is formed that comprises a host of curved non-parallel depressions. The depressions are designed and arranged in such a manner that during rolling no volume transport, or as little volume transport as possible, in the axial direction takes place, or a volume transport from a region of the blank where a thread section with a larger thread pitch is to be formed, to a region in which a thread section with a smaller thread pitch is to be formed takes place.