Screw Compressor Rotor Grinding for Variable-Pitch Helical Profiles

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Solution Overview

Problem

Existing methods for producing screw compressor rotors with helical profiles struggle to achieve precise machining when the pitch varies over the axial extent, leading to inefficiencies in profiling precision.

Innovation Solution

A grinding method using a grinding wheel with a Gothic profile and multiple axis movements (radial, axial, and combined) ensures precise machining of groove-shaped recesses with variable pitch, allowing for point contact and precise control of the abrasive surface, enabling machining of rotors with changing gradients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a profile grinding wheel with a grinding profile corresponding to the section through the profiling is used, then standard grinding can be performed, but precise machining is no longer possible when the gradient of the profiling changes over the axial extent

Engineering Contradiction:
Improveprofiling precisionVSAvoidadaptability to variable pitch
Core Design Contradiction:
Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The grinding tool is designed with a Gothic profile in radial section, which allows dynamic adaptation to variable pitch profiles through point contact grinding. The tool geometry and movement path are configured to accommodate changing gradients along the axial extent, enabling precise machining of rotors with variable pitch without requiring multiple specialized tools.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention transitions from traditional line contact grinding to point contact grinding by using a Gothic profile tool. This dimensional change in the contact interface allows the grinding process to adapt to three-dimensional variable pitch profiles, enabling precise machining of complex helical surfaces that cannot be achieved with conventional profile grinding wheels.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If a grinding tool with Gothic profile and point contact is used, then precise machining of variable pitch is achieved, but the device complexity increases

Engineering Contradiction:
Improvevariable pitch profiling precisionVSAvoidgrinding tool complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The Gothic profile tool combines specific geometric parameters (radial section profile, point contact configuration) with controlled movement parameters (radial feed, axial feed, rotational speed) to achieve precise variable pitch machining. By optimizing these parameters, the system accomplishes complex profiling tasks with a relatively simple tool design that does not require multiple specialized components.

Inventive Principle:
Principle #35Parameter changes

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 allows for precise machining of rotors with variable pitch, ensuring accurate profiling and efficient grinding by allowing for complex movements of the grinding tool, ensuring collision-free machining and maintaining precision over the rotor's surface.

Implementation Method 1

a grinding tool in the form of a grinding wheel being used, with the abrasive section of the grinding wheel having a Gothic profile in radial section

Methodology Applied
Scientific EffectAbrasion: Abrasion

Data Source

PatentEP4028215B1Method for producing a rotor of a screw compressor or a workpiece with a helical profile
Publication Date: 2023.12.06 KAPP NILES GMBH & CO KG
  • EP4028215B1 patent drawingFigure 1~2
  • EP4028215B1 patent drawingFigure 3
  • EP4028215B1 patent drawingFigure 4

AI summary

The invention relates to a method for producing a rotor (1, 2) of a screw compressor or a workpiece with a helical profile, the rotor (1, 2) or the workpiece with a helical profile having a number of profiles in the form of groove-shaped recesses (3, 4) running in a spiral manner on the outer periphery thereof, the groove-shaped recesses (3, 4) being fine-machined using a grinding tool (5) for the purpose of generating a precise profile. To be able to produce, in particular, rotors and workpieces having variable pitch along the axial extent of the rotor or the workpiece as precisely as possible, according to the invention, the groove-shaped recesses (3, 4) are fine-machined with a grinding tool (5) which only touches the surface of the groove-shaped recess (3, 4) at one point (P) during the grinding process, the entire surface to be machined being machined by the grinding tool (5) through line-by-line traversing of the surface to be machined.