Method and device for checking workpieces

• US 20040003663A1
• Filed: 06/06/2003
• Published: 01/08/2004
• Est. Priority Date: 10/25/2001
• Status: Abandoned Application

• Current Assignee: Ecoclean GmbH (Durr AG)
• Original Assignee: Ecoclean GmbH (Durr AG)
• Inventors: Wuller, Karl-Heinz, Dibos, Thomas
• Application Number:
  US10/456,773
• Publication Number:
  US 20040003663A1
• Time in Patent Office: Days
• US Class Current: 73/587
• CPC Class Codes: G01N 2291/269 Various geometry objects
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 29/48 by amplitude comparison

Abstract

In order to create a method for checking workpieces with at least one interior space, which is easy and quick to carry out, it is proposed that the method comprises the following steps:

a. generating a flow of gas in the interior space of the workpiece;

b. detecting a noise generated by the flow of gas;

c. comparing a measured value derived from the noise with a desired value.

Claims

1. Method for checking workpieces (114) with at least one interior space (118), comprising the following method steps:

generating a flow of gas in the interior space (118) of the workpiece (114);

detecting a noise generated by the flow of gas;

comparing a measured value derived from the noise with a desired value.

2. Method according to claim 1, characterised in that the flow of gas generated is a flow of air.

3. Method according to one of claims 1 or 2, characterised in that a gas is supplied to the interior space (118) at an excess pressure of at least 50 mbar, preferably of at least 100 mbar.

4. Method according to one of claims 1 to 3, characterised in that the flow of gas is generated by a fan (108).

5. Method according to one of claims 1 to 4, characterised in that a gas is supplied to an inlet orifice (120) of the interior space via a supply line (110).

6. Method according to claim 5, characterised in that the supply line (110) is provided with an outlet widening towards the inlet orifice (120).

7. Method according to one of claims 5 or 6, characterised in that the supply line (110) is provided with a bush (112) comprising an elastic material.

8. Method according to one of claims 1 to 7, characterised in that the noise is detected by a microphone (106) or a structure-borne sound sensor.

9. Method according to one of claims 1 to 8, characterised in that a frequency spectrum of the noise is determined as measured value.

10. Method according to claim 9, characterised in that the frequency spectrum is determined in a frequency range between 0 and approximately 22,000 Hertz.

11. Method according to one of claims 1 to 10, characterised in that a frequency spectrum is determined as desired value.

12. Method according to one of claims 1 to 11, characterised in that the desired value is determined by averaging over measurements on a plurality of regular workpieces.

13. Method according to one of claims 1 to 12, characterised in that a desired frequency spectrum is determined as desired value and a measured frequency spectrum as measured value.

14. Method according to claim 13, characterised in that a workpiece (114) is rejected as irregular if the divergence between the measured frequency spectrum and the desired frequency spectrum at at least one frequency is greater than a preset tolerance value.

15. Method according to one of claims 13 or 14, characterised in that a workpiece (114) is rejected as irregular if the divergence between the measured frequency spectrum and the desired frequency spectrum is greater than a preset tolerance value over a preset frequency range.

16. Method according to one of claims 1 to 15, characterised in that at least one outlet orifice (122a to 122d) of the workpiece (114) is covered during detecting of the noise generated by the flow of gas.

17. Method according to claim 16, characterised in that the outlet orifice (122a to 122d) is covered by a covering element (138a to 138d) movable relative to the workpiece (114).

18. Method according to claim 17, characterised in that the covering element (138a to 138d) is moved relative to the workpiece (114) pneumatically and/or hydraulically.

19. Method according to one of claims 16 to 18, characterised in that the noise generated by the flow of gas is detected both when the outlet orifice (122a to 122d) is covered and when the outlet orifice (122a to 122d) is not covered.

20. Method according to claim 19, characterised in that there are several coverable outlet orifices (122a to 122d) and several noise-detecting steps are carried out, wherein a different subset of coverable outlet orifices (122a to 122d) is opened for each noise-detecting step.

21. Method according to claim 20, characterised in that precisely one of the coverable outlet orifices (122a to 122d) is opened for each noise-detecting step.

22. Method according to one of claims 1 to 21, characterised in that several noise-detecting steps are carried out in succession on the same workpiece (114).

23. Device for checking workpieces (114) with at least one interior space (118), comprising

a gas flow generating device for generating a flow of gas in the interior space (118) of the workpiece (114);

a noise-detecting device for detecting a noise generated by the flow of gas and

a processing device which derives a measured value from the noise and compares the derived measured value with a desired value.

24. Device according to claim 23, characterised in that the gas flow generating device comprises a fan (108).

25. Device according to one of claims 23 or 24, characterised in that the gas flow generating device comprises a supply line (110) for supplying a gas to an inlet orifice (120) of the interior space (118) of the workpiece (114).

26. Device according to claim 25, characterised in that the supply line (110) is provided with an outlet widening towards the inlet orifice (120).

27. Device according to one of claims 25 or 26, characterised in that the supply line (110) is provided with a bush (112) comprising an elastic material.

28. Device according to one of claims 23 to 27, characterised in that the noise-detecting device comprises a microphone (106) or a structure-borne sound sensor.

29. Device according to one of claims 23 to 28, characterised in that the device (100) comprises at least one covering element (138a to 138d) for covering at least one outlet orifice (122a to 122d) of the workpiece (114).

30. Device according to claim 29, characterised in that the covering element (138a to 138d) is movable relative to the workpiece (114).

31. Device according to claim 30, characterised in that the device (100) comprises a pneumatic and/or hydraulic movement device for moving the covering element (138a to 138d) relative to the workpiece (114).