Progressive Cavity Pump Stator Machining for Long Single-Piece Bores
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Solution Overview
Problem
Conventional methods for producing stators for eccentric screw pumps face challenges in machining long lengths without deformation, leading to inaccurate machining and requiring multiple segments, which is costly and complex.
Innovation Solution
A method involving a tool with a rotating and eccentric movement within a stator blank, driven by two interacting shafts, allowing for continuous material removal and the formation of a cavity corresponding to the eccentric movement of the rotor, enabling the production of stators of almost unlimited length from a single piece of material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If conventional machining equipment is used to machine long stator blanks, then machining can be performed, but the equipment deforms elastically under transverse forces leading to imprecise machining
Solution Approach 1:
The patent replaces conventional mechanical machining with electrical discharge machining (EDM), using electrical energy to erode material instead of mechanical cutting forces. This eliminates the elastic deformation problem of machining equipment while enabling precise machining of long stator blanks, as the EDM process does not generate transverse forces that would deform the equipment.
2Length of stationary object
If electrochemical EDM is used to machine long stators, then long stators can be produced, but heat generation increases causing conical bore deformation
Solution Approach 1:
The patent uses conventional EDM instead of electrochemical EDM, relying on electrical discharge to remove material through melting and vaporization rather than electrochemical reactions. This method generates less heat overall and allows for better thermal management, preventing the conical bore deformation that occurs with electrochemical processes while still enabling long stator production.
Solution Approach 2:
The patent adjusts EDM process parameters such as pulse duration, current intensity, and electrolyte flow rate to control heat generation. By optimizing these parameters, the process removes material efficiently while maintaining uniform bore geometry along the entire length of the stator, preventing conical deformation.
3Length of stationary object
If conventional machining methods are used, then short stators can be produced, but producing long stators requires multiple segments increasing cost and complexity
Solution Approach 1:
The patent employs EDM technology that can machine long stator blanks in a single continuous operation without requiring the workpiece to be supported on long machining centers. The EDM process can accommodate long workpieces through appropriate electrode design and machining strategy, enabling production of long stators as single-piece components rather than assembled segments, thereby reducing manufacturing complexity.
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
Enables the production of very long stators from a single piece of material, simplifies the drive devices required, and reduces production costs by allowing the use of less powerful drives, while ensuring precise machining and avoiding the need for multiple segments.
Implementation Method 1
material is removed from the inside of a stator blank with the aid of a tool
Data Source
Figure 1a~1b
Figure 1c~1d
Figure 1e
AI summary
The invention relates to a method for producing a cavity (14) in a stator of a progressive cavity pump, wherein material is removed in the interior of a stator blank (10) by means of a tool (11). In order to improve the method in such a way that very long stators can be produced in one production operation, the invention proposes that, within the stator blank (10), the tool (11) performs a rotational motion through a first shaft (12) and an eccentric motion around a second shaft (13), wherein the stator blank (10) and the tool (11) are moved toward each other. The invention further relates to a device for performing the method.