Abrasive flow machine, method for ascertaining material removal on a workpiece, and method for determining the cutting power of a grinding medium

1 . An abrasive flow machine for moving abrasive media over a surface of a workpiece and/or through the opening of a workpiece, comprising

a media drive device which is adapted to move the abrasive medium over a surface of a workpiece and/or through the opening of the workpiece in a flow direction;

a workpiece holder for mounting the workpiece, having two parts adapted to be positioned on opposite sides of the workpiece;

a structure-borne sound sensor for measuring structure-borne sound generated in a workpiece when the latter is machined with an abrasive medium; and

an electronic evaluation unit on which software is stored which is configured such that the evaluation unit is configured to receive a raw signal of the structure-borne sound sensor and by means of the software to process the raw signal of the structure-borne sound sensor to determine a continuous value of the root mean square of the structure-borne sound measured by the structure-borne sound sensor over time and to integrate the root mean square of the structure-borne sound, wherein the evaluation unit is adapted to infer a cutting power of the abrasive medium and/or a rate of material removal on the workpiece, wherein the cutting power and/or material removal rate is evaluated based on the integrated measurand that is formed by the evaluation unit over the continuous value of the root mean square of the structure-borne sound measured by the structure-borne sound sensor over time,

wherein the integrated measurand of the root mean square of the structure-borne sound measured by the structure-borne sound sensor over time is specific to a particular material removal, and

wherein the material removal rate is calculated by dividing the value of the material removal by the machining time and/or the cutting power is ascertained by dividing the material removal by the media flow rate and

wherein the media drive device is further configured to change a flow velocity, fluid pressure, or back pressure of the abrasive medium based upon the material removal rate.

2 . The abrasive flow machine according to claim 1 , wherein the evaluation unit has a look-up table stored therein, from which a material removal on the workpiece and/or a cutting power of the abrasive medium can be read based on the integrated measurand of the root mean square of the measured structure-borne sound signal over time.

3 . The abrasive flow machine according to claim 1 , wherein the evaluation unit includes an amplifier for amplifying the signal measured by the structure-borne sound sensor.

4 . The abrasive flow machine according to claim 1 , wherein the evaluation unit includes at least one filter for filtering out machine frequencies from the signal measured by the structure-borne sound sensor.

5 . The abrasive flow machine according to claim 1 , wherein the structure-borne sound sensor is in direct or indirect contact with the workpiece during operation of the abrasive flow machine.

6 . The abrasive flow machine according to claim 1 , wherein the abrasive flow machine comprises a bypass duct that extends parallel to a fluid main channel, and in that the workpiece is a dummy workpiece arranged in the bypass duct, the fluid main channel extending over a surface and/or through an opening of an additional workpiece to be machined.

7 . The abrasive flow machine according to claim 6 , wherein the abrasive flow machine comprises two structure-borne sound sensors, wherein, during operation of the abrasive flow machine, a respective structure-borne sound sensor is positioned on the dummy workpiece in the bypass duct and also on the additional workpiece to be machined.