Method and device for obtaining a determined flow resistance of a flow channel by means of a measuring bridge
The invention relates to a method and device for obtaining a determined flow resistance of a flow channel, especially an opening in a component. The method involves the following steps: a liquid flows through the flow channel; a characteristic depending on the flow resistance of the flow channel in the component is determined; and the flow channel is machined by means of a working method until said characteristic reaches a pre-determined nominal value.
1. A method to machine a flow channel of a component and to achieve a determined flow resistance of said flow channel, comprising the steps of:
a) pumping a fluid through the flow channel, wherein the flow channel is contained within a closed loop;
b) machining the flow channel with a working method;
c) pausing the machining and measuring a parameter which is a function of the flow resistance of the flow channel in the component; and
d) restarting the machining until the parameter has reached a specified set point, at which time the machining is stopped;
e) wherein the parameter is determined by means of a measuring bridge.
2. The method as claimed in claim 1 , wherein the step of machining the flow channel consists of one from the group of chemical machining, hydroabrasive machining, mechanical machining, electrochemical machining, electroerosion machining, electroplating, electroless plating, coating and vacuum metallizing.
3. The method as claimed in claim 1 , wherein the measuring bridge is constructed according to the principle of a Wheatstone bridge, in which the flow channel is connected by means of a first line with a first impedance and the flow channel to form a first series circuit and a second impedance is connected by means of a second line with a third impedance to form a second series circuit; and in which the first series circuit and the second series circuit are connected to form a parallel circuit; and whereby a fluid flows through the parallel circuit and the parameter, which is the pressure difference of the fluid between the first line and the second line, is determined, whereby the first line is connected with the second line.
4. The method as claimed in claim 3 , wherein at least one resistance from the group that includes the first impedance, the second impedance and the third impedance is variable and wherein the variable resistance is specified so that the measuring bridge is balanced as soon as the desired set point of the flow channel is reached.
5. The method as claimed in claim 4 , wherein the variable resistance is specified by means of a master object, by replacing the flow channel with the master object and balancing the measuring bridge by setting the variable resistance.
6. The method as claimed in claim 1 , wherein the set point is determined for a specifiable average flow rate or for a specifiable average pressure.
7. The method as claimed in claim 1 , wherein fluid is pumped through the channel at an average pressure of between 3 and 8 bar.
8. The method as claimed in claim 7 , wherein the average machining pressure is between 4 and 6 bar.
9. The method as claimed in claim 1 , wherein a measurement of said parameter is performed during a machining pause when the flow channel is free of an inserted cathode, or at least free of an applied electrical voltage.
10. The method as claimed in claim 1 , wherein the fluid comprises electrolytic solutions, corrosive fluids, dielectric fluids and/or carrier gases.