Electrochemical machining method for rotors or stators for moineau pumps

Patent metadata

Field	Value
Publication number	US-9976227-B2
Application number	US-201414278220-A
Country	US
Kind code	B2
Filing date	May 15, 2014
Priority date	May 15, 2014
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

An ECM method involves the use of a thin hollow electrode assembly that carries the electrolyte within and that is advanced relatively to the workpiece. The small profile of the electrode results in a minimal removal of metal in forming the desired rotor or stator shape. The electrode profile allows significant power consumption reduction or increased machining speed for a given rate of power input. The electrode can be a unitary ring shape or can be made of segments that are placed adjacent each other so that a continuous shape is cut. Not all the lobes of the stator or rotor have to be cut in the same pass. Electrode segments can be used to sequentially provide the desired lobe count in separate passes. The lobe shapes in the electrode can be slanted to get the desired rotor or stator pitch or they can be aligned with the workpiece axis.

First claim

We claim:

1. An electrochemical manufacturing method, comprising:
providing at least one continuously extending closed shaped electrode defining an opening therethrough and further comprising at least one lobe skewed with respect to an axis of a relative axial movement of said closed shaped electrode with respect to a workpiece, a relative rotation of said closed shaped electrode relative to said workpiece coupled with said relative axial movement results in the production of at least one continuous lobe that has a desired pitch on the workpiece, said opening being smaller at least in part than an initial outermost workpiece periphery such that relatively rotating and relatively axially moving said electrode within the initial outermost workpiece periphery to make a continuous axial cut along a longitudinal axis of the workpiece removes from an outermost initial peripheral portion of the workpiece at least one separable excess piece located outside said closed shaped electrode thus defining a finished outermost workpiece periphery which is smaller than said initial outermost workpiece periphery; or
providing at least one continuously extending closed shaped electrode defining an opening therethrough and further comprising at least one lobe skewed with respect to an axis of a relative axial movement of said closed shaped electrode with respect to a tubularly shaped workpiece, a relative rotation of said closed shape electrode relative to said workpiece coupled with said relative axial movement results in the production of at least one continuous lobe that has a desired pitch on said workpiece, said opening being larger at least in part than an initial innermost workpiece periphery of a tubularly shaped workpiece such that relatively rotating and relatively axially moving said electrode outside the initial innermost workpiece periphery to make a continuous axial cut along a longitudinal axis of the workpiece removes from an innermost initial peripheral portion of the workpiece at least one separable excess piece located inside said closed shaped electrode thus defining a finished innermost workpiece periphery which is larger than said initial innermost workpiece periphery of the tubularly shaped workpiece; or
providing at least one continuously extending closed shaped electrode defining an opening therethrough and further comprising at least one lobe skewed with respect to an axis of a relative axial movement of said closed shaped electrode with respect to a workpiece, a relative rotation of said closed shape electrode relative to said workpiece coupled with said relative axial movement results in the production of at least one continuous lobe that has a desired pitch on the workpiece, said opening being smaller than at least in part than an initial outermost workpiece periphery such that relatively rotating and relatively axially moving said electrode within the initial outermost workpiece periphery to make a continuous axial cut along a longitudinal axis of the workpiece removes from within an outermost initial peripheral portion of the workpiece at least one separable excess piece located inside said closed shaped electrode thus creating a tubular shape with a finished innermost workpiece periphery;
delivering power to said electrode, and electrolyte to said electrode with an electrolyte delivery system;
allowing said electrolyte to cut into said workpiece in a manner that allows the electrode to advance into said cut.

2. The method of claim 1 , comprising:
making a rotor or stator for a progressing cavity pump or a mud motor from said workpiece.

3. The method of claim 2 , comprising:
creating a rotationally symmetrical rotor or stator with said electrode.

4. The method of claim 1 , comprising:
supporting said electrode with a hollow support;
providing power to said hollow support.

5. The method of claim 1 , comprising:
making said electrode from two or more segments configured to machine lobes in said workpiece.

6. The method of claim 5 , comprising:
making at least one of said segments hollow;
abutting said segments to create a segmented electrode.

7. The method of claim 5 , comprising:
making multiple passes of relative movement between said workpiece and said electrode to obtain said machined workpiece.

8. The method of claim 1 , comprising:
making multiple passes of relative movement between said workpiece and said electrode.

9. The method of claim 1 , comprising:
shaping said electrode to machine lobes in said workpiece;
producing stator or rotor lobes.

10. The method of claim 9 , comprising:
producing parts of machines to transform flow energy into mechanical energy or vice versa with said electrode.

11. The method of claim 9 , comprising:
orienting lines on said electrode connecting the radius maxima along individual lobes either parallel or skewed to the axis of said movement.

12. The method of claim 1 , comprising:
supporting said electrode with hollow supports;
making said electrode hollow;
supplying electrolyte to said hollow electrode through said hollow supports extending from a shaft located within an electrode holder.

13. The method of claim 12 , comprising:
sealing between a portion of the workpiece that has yet to be machined and said shaft or said electrode holder to contain said electrolyte for recirculation.

14. The method of claim 1 , comprising:
removing at least a portion of said excess piece before said cut is finished.

15. The method of claim 1 , wherein:
providing an electrode thickness no greater than a thickness of the excess piece to be cut.

16. An electrochemical manufacturing apparatus, comprising:
at least one continuously extending closed shaped electrode defining an opening therethrough and further comprising at least one lobe skewed with respect to an axis of a relative axial movement of said closed shaped electrode with respect to a workpiece, a relative rotation of said closed shaped electrode relative to said workpiece coupled with said relative axial movement results in the production of at least one continuous lobe that has a desired pitch on the workpiece, said opening being smaller at least in part than an initial outermost workpiece periphery such that relatively rotating and relatively axially moving said electrode within the initial outermost workpiece periphery to make a continuous axial cut along a longitudinal axis of the workpiece removes from an outermost initial peripheral portion of the workpiece at least one separable excess piece located outside said closed shaped electrode thus defining a finished outermost workpiece periphery which is smaller than said initial outermost workpiece periphery; or
at least one continuously extending closed shaped electrode defining an opening therethrough and further comprising at least one lobe skewed with respect to an axis of a relative axial movement of said closed shaped electrode with respect to a tubularly shaped workpiece, a relative rotation of said closed shape electrode relative to said workpiece coupled with said relative axial movement results in the production of at least one continuous lobe that has a desired pitch on said workpiece, said opening being larger at least in part than an initial innermost workpiece periphery of said workpiece such that relatively rotating and relatively axially moving said electrode outside the initial innermost workpiece periphery to make a continuous axial cut along a longitudinal axis of the workpiece removes from an innermost initial peripheral portion of the workpiece at least one separable excess piece located inside said clo

Assignees

• Baker Hughes Inc
• Baker Hughes A Ge Co Llc

Inventors

• Wangenheim Christoph
• Michaelis Gunnar
• Huber Witali
• Uhlenberg Thomas
• Wolters Hans H

Classifications

• F04C2/107

  with helical teeth · CPC title

• B23H3/04

  Electrodes specially adapted therefor or their manufacture (B23H9/00 takes precedence) · CPC title

• B23H9/04

  Treating surfaces of rolls · CPC title

• B23H9/00

  Machining specially adapted for treating particular metal objects or for obtaining special effects or results on metal objects (heat treatment by cathodic discharge C21D1/38) · CPC title

• C25F7/00

  Constructional parts, or assemblies thereof, of cells for electrolytic removal of material from objects (for both electrolytic coating and removal C25D); Servicing or operating · CPC title