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Round grinding chamfer

Using fast rotation mode of rotary axis

Some rotary axis support the option to switch from positioning to fast rotation mode. Using this mode it's possible to have a round grinding operation on the wire EDM machine.

ProfDia can be configured to output NC programs accordingly.

ProfDia Configuration

The file TechnoDB.ini in the ProfDia installation folder (e.g. c:\ProfDia ) needs to be adjusted using a text editor. It contains pre-prepared sections for this functionality. Because not being available on all machines, these parameters are commented out with leading ; characters by default.

Original content of TechnoDB.ini:

; Standard sequence round grinding
;[Techsequenz_10]
;s0=M82
;s1=G04X1.
;s2=M21 B1
;s3=M224P900
;s4=G04X1.

; Sequence Cut End round grinding
; Currently not in use
;[Techseq_Cut_End_10]
;s0=M42
;s1=M223

; Sequence Profile Section End round grinding
;[Techseq_PS_End_10]
;S0=M42
;s1=M223

To enable the functionally the comment signs ; have to be removed from the sections [Techsequenz_10] and [Techseq_PS_End_10] (except from the real comment text on top of each section). The section [Techseq_Cut_End_10] is defined for special purpose and should currently not be enabled.

In the pre-prepared section the command “M224P900” switches on the fast rotation with 900 RPM. If the axis should rotate with a different speed, the value can be adjusted (e.g. P1200 for 1200 RPM).

It is also possible to define additional sets of sections (copy and paste all three sections and replace the “_10” in the section names with “_11” for the next triple or “_12” for a third triple. In each triple the rotation speed can be defined as desired. After configuration the “_10” sections should look like this:

TechnoDB.ini file after adjusting the sequences:

; Standard sequence round grinding
[Techsequenz_10]
s0=M82
s1=G04X1.
s2=M21 B1
s3=M224P900
s4=G04X1.

; Sequence Cut End round grinding
; Currently not in use
;[Techseq_Cut_End_10]
;s0=M42
;s1=M223

; Sequence Profile Section End round grinding
[Techseq_PS_End_10]
S0=M42
s1=M223

Programming in ProfDia - Step 1

In ProfDia a separate profile section has to be created after the normal machining.

This section has: - To be a “Main profile section” (not shifted to the right as sub section) - Measuring has to be switched off in this section

Programming in ProfDia - Step 2

Create a specific cutting technology for round grinding

In this technology record the EDM data registers and the offset values have to be specified as usual. The values in the third column refer to the numbers at the end of the sections names in the configuration file TechnoDB.ini (See Configuration above). After enabling the pre-prepared sections only “10” can be specified in this column to select the parameters specified in this section. After adding sections with e.g. “_11” or “_12” the input 11 or 12 is also accepted in this column and enables the parameters specified in these additional sections.

Programming in ProfDia - Step 3

In the Round grinding profile section the following has to be specified:

  • Only one angular position

  • all relief angles set to zero

  • A local technology for round grinding has to be selected

  • A manually created measuring point list (Created using the button Create measuring point list)

Now the tool will be cut as usual. And prior to the round grinding profile, the technology will be loaded and the start sequence for the continuous rotation will be put out.

Caveats for the Fast Rotation approach

Due to the fast tool rotation the water inside the tank will be heavily swirled. This method should only be used on smaller tools (diameter < 20mm) with a streamlined design. Tools with many big tips will behave like a boat screw.

Pendulum grinding / eroding

Setup

To enable the pendulum grinding / eroding option in ProfDie the following values have to be added to PPFanuc.INI file.

[Parameter]
; Technologie-Register-Bereich, der für das Pendelschleifen der Rundschlifffase benutzt wird
; In Technologiebearbeitungsfolge müssen diese Register wie unten angegeben verwendet werden
;
; Technology register range for technologies used for pendulum grinding of round grinding chamfer
; These technologies have to be added to the ProfDia technology for pendulum grinding
Pendelschleif_regnr_anf=199
Pendelschleif_regnr_end=202

; Schrittweite/Intervall für Pendelbewegung entlang der Kontur
;
; width for one pendulum movement along the profile
Schrittlaenge=0.05

; Fasenhöhe für Überschwenken an Plattenoberseite
;
; chamfer height for swinging over at top of plate
Fasenueberlaufoben=0.2
; 
; Fasenhöhe für Berechnung des Schwenkwinkels an der Fase
;
; chamfer height for calculating the swivel angle at the chamfer 
Fasenbreiteunten=0.8
The technology registers need to be added to a technology inside ProfDia

Note

It's important to have a constant feedrate along the profile

Create Program in ProfDia - Step 1

First the diameter offset needs to be determined using a CAD system.

Parameter Value
Tool Radius R=10mm
Height for Chamfer 0.4mm
Radial Relief Angle 20°

The 20° radial relief angle are drawn below the 0.4mm chamfer area on the fly circle. The relief surface is tangentialy extended to the PCD surface.

The calculated radius offset for this tool example is 0.138mm => 0.276mm diameter offset

Highlighted in green is the surface which will be removed by the selected round grinding approach

Create Program in ProfDia - Step 2

Create the cutting profile as needed on regular radius (in example radius 10mm)

Create Program in ProfDia - Step 3

  • Add a new project to ProfDia and import the drawing

  • Add the cutting profile as main profile for probing and cutting with the desired radial relief angle

  • Open Enter additional parameters

  • set the diamter offset to the previously calculated value (here 0.276mm)

Note

When a value > 0.2mm can not be entered, the limit for fine adjustment has to be increased in IMCSDIA.INI file. Set the value to 0.5 or higher

[Parameter]
Offset_Feinkorrektur_limit=0.5

  • Add the profile for round grinding

  • No diameter offset
  • No relief angles
  • Save the profile

Back in Profile Section Management:

  • Make the RoundGrinding profile a sub profile of the cutting edge profile
  • Disable measuring for the RoundGrinding profile

Now measure and cut the tool as usual.

Caveats for Pendulum Grinding / Eroding approach

  • Machining of a round grinding chamfer using the pendulum grinding / eroding methods could be time consuming. For smaller tool batches this is a good option. When it comes to optimization of machining times a special machine for machining round grinding chamfers should be considered to be used
  • The machine needs to be very well prepared
  • Technologies need to be adjusted and tested prior to receive good results