DE102014018688A1 - Device for processing a metallic component by means of an electrochemical removal method - Google Patents

Abstract

The invention relates to a device for processing surfaces of a metallic component by means of an electrochemical removal method (ECM), comprising: an electrically insulating base body for receiving the metallic component, an electrical anode arranged in the electrically insulating base body for making electrical contact with the metallic component, a electrically insulated base body arranged electrical cathode, which is opposite to the surface to be machined of the metallic component and separated by an electrolyte gap from this surface, wherein the electrolyte gap is delimited by a surface of the cathode and the surface to be machined of the metallic component, a supply for an electrolyte , which is arranged in the base body and connected to the electrolyte gap, wherein the base body and the electrodes are firmly connected to each other and machined in one clamping.

Description

Field of the invention

The invention relates to a device for deburring a metallic component by means of an electrochemical removal method (ECM).

In particular, the invention relates to a device for deburring a thread on a metallic component of a spindle motor with fluid dynamic bearing system.

State of the art

In the electrochemical machining of components of spindle motors, it was previously known to receive and position the components in a component or parts holder.

The electrode for electrochemical machining (ECM electrode) was then mechanically aligned with respect to the parts holder and the surface of the component to be machined. For the alignment and centering of the ECM electrode, a great deal of effort was necessary because the electrode had to be aligned very precisely with respect to the component to be machined and the parts holder in order to obtain a satisfactory and reproducible machining result.

Due to inaccurate positioning and handling errors, defects have repeatedly occurred due to mechanical collision of the electrode with the components or electrical short circuits, which rendered the electrode and the components unusable.

Disclosure of the invention

The object of the invention is therefore to provide an apparatus for processing a metallic component by means of electro-chemical removal method, which operates more effective and reliable than previous comparable devices.

This object is achieved by a device with the features of claim 1.

Preferred embodiments of the invention and further advantageous features are specified in the subclaims.

The device according to the invention comprises an electrically insulating basic body which is used as a part holder for receiving the metallic component, an electrical anode arranged in the electrically insulating base body for electrical contacting of the metallic component, an electric cathode arranged in the electrically insulating base body, that of the surface to be machined metallic component and is separated by an electrolyte gap from this surface, wherein the electrolyte gap is delimited by a surface of the cathode and the surface to be machined of the metallic component, a supply for an electrolyte, which is arranged in the base body and connected to the electrolyte gap.

According to the invention, the base body and the electrodes are firmly connected to one another and machined in one clamping.

Preferably, the base body and the electrodes consist of individual turned parts, which are firmly connected to each other after manufacture, for example by a press connection and / or adhesive connection.

The main body and the associated electrodes are then reworked to size in one setting. As a result, the alignment of the electrodes is ensured relative to the base body and very accurate to manufacture.

Also, the required distance between the cathode and the component to be machined, which is referred to here as the electrolyte gap, is ensured by the common fine machining of the components. In particular, the active surface of the cathode opposite the workpiece to be machined can be machined with respect to highly accurately machined positioning surfaces or points so that the positioning of the machined component at these positioning surfaces or points automatically results in accurate alignment of the component to be machined given to the cathode of.

The device described may preferably be designed for deburring a thread on a metallic component, preferably for deburring a thread on a metallic hub of a spindle motor.

The device is designed in this case so that preferably an end face of the hub rests against the electrical anode and is centered there on positioning surfaces. According to the invention, both the base body and the electrical anode can have positioning surfaces for the component to be processed. The component to be machined has corresponding mating surfaces which are brought into contact with the positioning surfaces.

Preferably, the thread to be deburred on the hub is an external thread. The cathode is positioned in the body so that it is too Deburring thread surrounds with intended positioning of the inserted component.

The electrolyte gap between the electrical cathode and the surface to be deburred of the metallic component is preferably between 20 and 100 microns wide, but more preferably 30 to 60 microns.

The device according to the invention comprises a holding-down device for holding the metallic component on the base body, wherein the holding-down device rests against the metallic component and is electrically insulated from it.

Hereinafter, a preferred embodiment of the invention with reference to the drawing 1 described.

From the drawings and their description further features and advantages of the invention will become apparent.

1 shows a schematic section through the device according to the invention, for example for processing a metallic hub 30 a spindle motor.

The device comprises a base body 10 which consists of an electrically insulating material, at least in the areas which come into contact with current-carrying parts.

The main body 10 has a central opening in which an electrical anode 12 is attached. The electrical anode 12 is preferably concentric with the main body 10 and to an electric cathode 14 arranged. The electric cathode 14 is annular and formed in a recess of the body 10 held. In the example, the main body is formed in two parts, wherein the cathode 14 between a central part 10a and a border part 10b of the basic body 10 is arranged.

According to the invention, the main body 10 and the two electrical electrodes 12 . 14 made as separate parts and then connected together, for example by a press connection and / or an adhesive connection. The anode 12 for example, in the central opening of the body 10 pressed in, and the annular cathode 14 is also in a matching recess of the body 10 pressed. In the example, the recess for pressing in the cathode is between the central part 10a and the edge part 10b formed of the main body.

After connecting the electrodes 12 . 14 with the main body 10 the basic body is clamped in a processing machine and processed together with the two electrodes in this setup to measure. In particular, for example, positioning surfaces 12a at the anode 12 machined on which the component to be machined in the form of the hub 30 is positioned.

Depending on these positioning surfaces 12a also becomes the inner circumference of the cathode 14 machined, that of the surface of the hub to be machined 30 opposite, in the present example a thread 32 ,

The two electrodes 12 . 14 are connected to an electrical voltage source (not shown) which provides the needed current for the electrochemical ablation process.

The machined component of a spindle motor in the form of the hub 30 is approximately cup-shaped in cross-section and has an outer thread on the outer circumference 32 which is deburred after tapping by means of the described ECM method.

The hub 30 includes a central area that serves as a bearing bush 30a is formed and in which a bearing bore 34 is introduced.

In the bearing bore 34 a shaft (not shown) of the spindle motor is introduced, wherein between the shaft and the bearing bore 34 a bearing gap remains along the fluid dynamic bearings are arranged. The fluid dynamic bearings include bearing groove structures 36 , preferably on the circumference of the bearing bore 34 are arranged.

At the hub 30 are positioning surfaces 38 , for example in the form of a groove 38 present with corresponding positioning surfaces 12a at the anode 12 interact. The positioning surfaces 12a the anode 12 For example, are formed as a peripheral edge, which in the as a positioning surface 38 trained groove of the hub 30 intervenes.

If the hub 30 in the recess provided in the body 10 is used, so is by the positioning surfaces 12a respectively. 38 the hub 30 exactly in relation to the position of the anode and thus also the cathode 14 centered and positioned.

This results between the inner circumference of the cathode 14 and the outer circumference of the hub 30 in the area of the thread to be machined 32 a defined electrolyte gap 18 with a defined width, for example in the range between 20 to 100 micrometers, preferably 40 to 50 micrometers.

The hub 30 is made by an axially acting on the hub hold-down 20 held in position by means of an insulating component 22 from the hub 30 is disconnected.

The electrolyte is supplied via an appropriate feeder 16 supplied to the device which with the electrolyte gap 18 is connected, at which the cathode 14 borders.

By doing that, the hub 30 on the anode 12 is pressed, there is the electrical contact between the anode 12 and the electrically conductive hub 30 so the hub 30 itself becomes the anode.

By the in the electrolyte gap 18 existing electrolyte is the circuit between the anode (hub 30 ) and the cathode 14 closed, taking a material removal in the area of the thread 32 by anodic dissolution of the material of the electrically conductive hub 30 he follows.

In this deburring process, for example, 3 to 5 microns of material from the thread 32 the hub 30 removed and also loose chips and particles from the thread 32 away.

As the electrolyte, for example, a sodium nitrate or a sodium chloride solution can be used.

The electrolyte flows from the feeder 16 in the direction of the arrow 24 through a channel to the electrolyte gap 18 and leaves the device in the direction of the arrow 26 , is then collected and returned to the circuit.

LIST OF REFERENCE NUMBERS

10

body

10a

Central part of the body

10b

Edge part of the body

12

Electrode - anode

12a

positioning surfaces

14

Electrode - cathode

16

Feeding electrolyte

18

electrolyte gap

20

Stripper plate

22

insulation material

24

flow direction

26

flow direction

30

hub

30a

bearing bush

32

thread

34

bearing bore

36

groove structures

38

positioning surfaces

Claims (10)

Device for processing surfaces of a metallic component ( 30 ) by means of an electrochemical removal method (ECM), which comprises: an electrically insulating base body ( 10 ) for receiving the metallic component ( 30 ), one in the electrically insulating body ( 10 ) arranged electrical anode ( 12 ) for electrical contacting of the metallic component ( 30 ), one in the electrically insulating body ( 10 ) arranged electrical cathode ( 14 ), the surface of the metallic component to be machined ( 30 ) and through an electrolyte gap ( 18 ) is separated from this surface, wherein the electrolyte gap ( 18 ) through a surface of the cathode ( 14 ) and the surface to be machined of the metallic component ( 30 ), a feeder ( 16 ) for an electrolyte that is in the body ( 10 ) and with the electrolyte gap ( 18 ), the basic body ( 10 ) and the electrodes ( 12 . 14 ) are firmly connected and machined in one setting. Device according to claim 1, characterized in that the basic body ( 10 ) and the electrodes ( 12 . 14 ) consist of individual parts that were firmly connected before processing. Device according to one of claims 1 or 2, characterized in that the electrolyte gap ( 18 ) is between 20 and 100 microns wide. Device according to one of claims 1 to 3, characterized in that the electrolyte gap ( 18 ) is between 30 and 60 microns wide. Device according to one of claims 1 to 4, characterized in that it comprises a hold-down ( 20 ) for holding the metallic component on the base body. Device according to one of claims 1 to 5, characterized in that the hold-down ( 20 ) an insulating material ( 22 ), which on the metallic component ( 30 ) is present. Device according to one of claims 1 to 6, characterized in that the basic body ( 10 ) and / or the electrical anode positioning surfaces ( 12a ), on which the component to be machined ( 30 ) by means of corresponding positioning surfaces ( 38 ) is positioned. Device according to one of claims 1 to 7, characterized in that it for deburring a thread ( 32 ) on a metallic hub ( 30 ) is formed of a spindle motor. Apparatus according to claim 8, characterized in that an end face of the hub ( 30 ) on the base body ( 10 ) or at the electrical anode ( 12 ) rests and is positioned there. Device according to one of claims 8 or 9, characterized in that the thread ( 32 ) is an external thread and from the electric cathode ( 14 ) is surrounded.

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