DE202005021107U1 - Device for testing the surface of a rotational symmetrical workpiece comprises a rotating unit for rotating the workpiece about an axis of rotation and ultrasound emitting/receiving units for testing for deviations and defects - Google Patents

Abstract

Device for testing the surface of a rotational symmetrical workpiece comprises a rotating unit for rotating the workpiece (1) immersed in a liquid about an axis of rotation (R), a first ultrasound emitting/receiving unit (5) directed onto the axis of rotation for testing for deviations (3) from a geometry of the surface of the workpiece and a second ultrasound emitting/receiving unit (6) directed tangentially onto the axis of rotation for testing for defects (4) extending from the surface to the inside of the workpiece. Preferred Features: A third ultrasound emitting/receiving unit is also provided for testing for defects extending from the surface to the inside of the workpiece. The second and third ultrasound emitting/receiving units are arranged parallel to the workpiece.

Description

The The invention relates to a device for testing the surface of a rotationally symmetrical workpiece.

To In the prior art, the surface becomes more rotationally symmetric Workpieces, For example, of piston rods for the production of shock absorbers and Like., checked for errors. After a first method, an eddy current test is carried out first. In order to become superficial Error detected, which is greater than 50 microns are. The tested workpieces become subsequently subjected to a visual inspection. To carry out a reliable visual inspection trained staff required. Although the visual inspection of trained personnel a mistake can be overlooked.

Of Further will be for examination the surface of workpieces a so-called magnetic powder or flux test method performed. To do this the ones to be tested workpieces magnetized and containing a fluorescent dye Iron powder brought into contact. The iron powder adheres in particular on from the surface inside the workpiece extending errors, such as cracks, which then because of the fluorescent dye can be seen during a visual inspection. Also in In this case, the visual inspection requires trained and experienced Staff. Nevertheless, it can also happen that misses a mistake becomes.

task The invention is to the disadvantages of the prior art remove. It should be specified in particular a device with the waiver of a visual inspection safe and reliable error at the surface and / or near the surface Error in rotationally symmetrical workpieces can be found.

These The object is solved by the features of claim 1. Expedient refinements result arising from the features of the claims 2 to 12.

In a method for testing the surface of a rotationally symmetrical workpiece, the following steps are provided:
Rotating the liquid immersed workpiece about an axis of rotation,
Check for deviations from a geometry of the surface of the workpiece with a directed to the rotation axis first ultrasonic transmitting / receiving device and
Testing for defects extending from the surface into the interior of the workpiece with at least one second ultrasonic transmitting / receiving device directed tangentially onto the surface.

Under the term "deviations of a geometry of the surface "becomes particular understood a deviation from a rotationally symmetric geometry of the workpiece. It is in particular of a circular geometry deviating flattenings, dents or elevations.

Under the term "of the surface inside the workpiece extending errors " especially cracks, eruptions, slag inclusions and the like understood.

With the first ultrasonic transmitting / receiving device is ultrasound coupled substantially perpendicular to the axis of rotation in the workpiece. The ultrasound goes through radially the workpiece and will be at the opposite Page reflected. If the workpiece the predetermined rotationally symmetric Has geometry, only a reflection signal with a low intensity measured. If the rotationally symmetric geometry of the workpiece is disturbed, For example, has a flattening is that of the first Ultrasound transceiver sent ultrasound to one considerable part of the surface reflected in the area of the error, such as the flattening. Such a deviation from the rotationally symmetric geometry is detectable as a comparatively intense reflection signal.

With the second ultrasonic transmitting / receiving device is a along the inner and outer surface of the workpiece radially rotating surface wave generated. If in the workpiece no error is included, runs this surface wave and loses its intensity. It is not or only one low reflection signal observable. If in the workpiece an error, for example a crack is contained, the surface wave is reflected and the Error is as a comparatively intense reflection signal with the second ultrasonic transmitting / receiving device detectable.

to exam elongated rotationally symmetrical workpieces expediently finds a Relative movement between the first and second ultrasonic transmitting / receiving device and the workpiece in a direction parallel to the axis of rotation of the workpiece. This can be the surface of the workpiece on its entire length checked become.

The proposed method is extremely precise. It is especially superior to the visual inspection method used in the prior art. Using the proposed Method can be dispensed with visual inspection method for detecting superficial errors.

To an advantageous embodiment is for testing on from the surface ins Interior of the workpiece Errors extending tangentially to the surface third ultrasonic transmitting / receiving device provided. Conveniently, send the second and third ultrasonic transceivers in parallel Alignment ultrasound on the surface of the workpiece. The allows with high reliability finding especially triangular errors. Such mistakes can only in the provision of the second ultrasonic transmitting / receiving device u. U. not be detected if they are, for. B. in the manner of a Triangle, in the propagation direction of the surface wave broaden.

To a particularly advantageous embodiment is provided that the one sent by the second ultrasonic transmitting / receiving device Ultrasonic coupled in the direction of rotation of the workpiece and the of the third ultrasonic transmitting / receiving device sent ultrasound is coupled against the direction of rotation of the workpiece. The allows safe and reliable in particular the finding of triangular errors.

To In another embodiment, the first and second and optionally the third ultrasonic transmitting / receiving device operated simultaneously. This allows a particularly time-saving test the workpieces. Using the pre-proposed method workpieces with routinely on a high throughput the presence of surface defects checked become.

To a further advantageous embodiment is for testing of on the surface radially encircling faults, a fourth ultrasonic transmitting / receiving device provided, which is directed to the axis of rotation and opposite to a perpendicular to the axis of rotation extending radial plane around a Angle of 10 to 30 °, preferably 15 to 25 °, is tilted. This is an axially extending surface to the surface wave generated. The intensity this surface wave decreases, unless an error is found. In case of presence a superficial Error, this surface wave reflected and by means of the fourth ultrasound transmitting / receiving device as an intensity peak detected. The provision of the fourth ultrasonic transmitting / receiving device allows a finding of all in practice occurring surface defects and / or nearer to the surface Error with rotationally symmetrical workpieces, in particular with piston rods.

To In another embodiment, the workpiece is aligned in two parallel, arranged with a gap between them and with a Drive connected rollers placed and rotated. The rollers are taken up in a pool, which is filled with a liquid, for example, oil, filled so that's the one to be tested Workpiece during the exam Completely submerged in the liquid is. The proposed rotation of the workpiece to be tested by a simple laying on two parallel spaced at a distance rotatable rollers, makes the proposed method special easy. In particular, it is not necessary to use elaborate gripping devices provide, with which the workpiece to be tested on the Roll is to be set up. The workpiece to be tested can for example by means of a feed chute or a differently simple designed feeder supplied become.

advantageously, become the first, second, possibly third and possibly fourth ultrasound transmitting / receiving device moved on a carriage parallel to the axis of rotation along the surface. In this case, the workpiece must merely rotated, but not relative to the ultrasonic transceivers to be moved. This allows a particularly compact embodiment of a for carrying out the Method suitable test device.

Of course it is it also possible the workpiece relative to fixed arranged first, second, possibly third and possibly fourth ultrasonic transmitting / receiving devices in one Move direction parallel to the axis of rotation. That can for example be effected by a feed device, with which the workpieces continuously or also cyclically shifted on the rollers in a transport direction become.

To Another embodiment provides that the first, second, possibly third and possibly fourth ultrasonic transmitting / receiving device supplied signals are evaluated by means of a computer. It can compared the delivered signals with previously defined intensity limits become. For example, if the measured signals are stored Exceed intensity limits, may output a signal indicating the detection of an error and possibly the corresponding workpiece automatically rejected become.

To A further embodiment provides that the workpieces to be tested on each other following fed automatically and be dissipated. This allows the exam a variety of workpieces automated with a high throughput.

According to the invention, a device for testing the surface of a rotationally symmetrical workpiece is provided with
a rotating device for rotating the liquid-immersed workpiece about an axis of rotation,
a directed on the rotation axis first ultrasonic transmitting / receiving device for checking for deviations from a geometry of the surface of the workpiece, and
a second ultrasonic transmitting / receiving device directed tangentially onto the surface for testing errors extending from the surface into the interior of the workpiece.

Because of the advantages and advantageous embodiments of the device Reference is made to the preceding remarks. These described features are mutatis mutandis, on the device applicable.

following The method and the device will be described with reference to the drawings explained in more detail. It demonstrate:

1 a schematic sectional view through a workpiece and arranged relative thereto ultrasonic probes,

2 a section along the section line AA 'in 1 and

3 a further embodiment of the arrangement of the ultrasonic probes relative to the workpiece.

In 1 is a workpiece 1 , here a cylindrical piston rod made of metal, shown. The workpiece 1 points to its surface 2 a first mistake 3 and a second error 4 on. At the first mistake 3 it is a deviation from a rotationally symmetric geometry of the workpiece 1 , At the second mistake 4 it is one of the surface 2 inside the workpiece 1 reaching crack. An axis of rotation of the workpiece 1 is denoted by R.

A first ultrasonic probe 5 is arranged in a plane perpendicular to the axis of rotation R radial plane E so that its ultrasonic transmitting / receiving device is directed to the axis of rotation R. The arrangement of the ultrasonic probe 5 may slightly deviate from the radial plane E, up to 5 °.

A second ultrasonic probe 6 is preferably also arranged in the radial plane E, wherein the ultrasonic transmitting / receiving device tangentially to the surface 2 of the workpiece 1 is directed.

As if in agreement with 2 shows is a third ultrasonic probe 7 provided, the ultrasonic transmitting / receiving device also tangential to the surface 2 of the workpiece 1 is directed. Also the third ultrasonic probe 7 can be arranged in the radial plane E. The second 6 and the third ultrasonic probe 7 are suitably arranged so that the second ultrasonic probe 6 transmitted ultrasonic waves in a rotation direction indicated by the arrow P on the surface 2 impinge and that of the third ultrasonic probe 7 transmitted ultrasonic waves counter to the direction of rotation P on the surface 2 incident.

In 1 is also a fourth ultrasonic probe 7 shown which is tilted at an angle α of 17.5 ° with respect to the radial plane E tilted.

The ultrasonic probes 5 . 6 . 7 and 8th are arranged in a suitable distance for ultrasonic testing of the workpiece. They are connected to an evaluation device (not shown here) for generating ultrasound and for evaluating the signals detected thereby. The evaluation device can be a computer.

It has proved to be useful as the first ultrasonic probe 5 to use a point-focused ultrasonic probe. It is advantageous as a second 6 and third ultrasonic probe 7 each to use a line-focused ultrasonic probe. Furthermore, it is advantageous to use a punctiform or line-focused ultrasound probe as the fourth ultrasound probe. The proposed special ultrasonic probes allow a particularly secure and complete area coverage when testing the surface. The aforementioned secure area coverage is given in particular when the ultrasonic probes 5 . 6 . 7 and 8th in a direction parallel to the axis of rotation R relative to the workpiece 1 to be moved. Such a movement can be done because by that the ultrasonic probes 5 . 6 . 7 and 8th on a relative to the workpiece 1 movable carriage (not shown here) are mounted.

3 shows a further embodiment of an arrangement of ultrasonic probes 5 . 6 and 7 relative to the workpiece 1 , Here are the second 6 and the third ultrasonic probe 7 again aligned parallel to each other and tangential to the surface 2 of the workpiece 1 directed. The first ultrasonic probe 5 is substantially perpendicular to the orientation of the second 6 and the third ultrasonic probe 7 arranged. Also in this embodiment, a fourth ultrasonic probe 8th be provided, which - similar to in 1 shown - to an angle of 10 to 20 ° tilted to the radial plane E adjacent to the first ultrasonic probe 5 is arranged. For rotating the workpiece 1 this is on two rollers 9 mounted, which are connected to a drive device. By a rotation of the rolls 9 becomes an opposite rotation of the workpiece 1 causes.

For checking the workpiece 1 on the presence of first errors 3 comes with the first ultrasonic probe 5 Ultrasound on the surface 2 Posted. The first ultrasonic probe 5 is oriented substantially perpendicular to the axis of rotation R. In particular, when using a point-focused ultrasonic probe, it has surprisingly been found that thus first errors, ie deviations from the rotational symmetry, are safe and reliable detectable. This is attributed to a reflection, in particular due to flattening or elevations on the surface.

To find second errors, ie from the surface 2 inside the workpiece 1 reaching cracks and the like., Be with the second ultrasonic probe 6 along the surface 2 extending ultrasonic waves in the workpiece to be tested 1 coupled. If a second mistake 4 is present, those on the surface 2 reflected along the longitudinal ultrasonic waves. The reflected ultrasonic waves can with the second ultrasonic probe 6 be recorded.

Similarly, with the third ultrasonic probe 7 along the surface 2 running ultrasonic waves in the workpiece 1 coupled, the ultrasonic waves here opposite to the direction of rotation P of the workpiece 1 to run. Also in this case, those along the surface 2 running ultrasonic waves from into the workpiece 1 reaching second errors 4 reflected. The reflected ultrasonic waves may be from the third ultrasonic device 7 be recorded. The provision of the second 6 and the third ultrasonic probe 7 allows, in particular in the proposed arrangement, a reliable and reliable finding of second errors 4 , It has proved to be particularly advantageous that the second ultrasonic probe 6 and the third ultrasonic probe 7 coupled surface waves in opposite directions along the surface 2 of the workpiece 1 to run. In particular triangular errors can thus be found.

With the fourth probe 8th As a result of the tilting relative to the radial plane E by the angle α an ultrasonic wave in the workpiece 1 generated, which parallel to the direction of rotation R along the surface 2 running. This can in particular radial circumferential errors and / or second error 4 be recognized.

In the context of the present invention, it is of course possible, an automatic device for feeding and discharging the workpieces 1 provided. This allows a test for surface defects with a high throughput.

1

workpiece

2

surface

3

first error

4

second error

5

first ultrasonic probe

6

second ultrasonic probe

7

third ultrasonic probe

8th

fourth ultrasonic probe

9

roller

R

axis of rotation

α

angle

e

radial plane

P

direction of rotation

Claims (12)

Device for testing the surface of a rotationally symmetrical workpiece with a rotation device ( 9 ) for rotating the workpiece submerged in a liquid ( 1 ) about an axis of rotation (R), on the rotation axis (R) directed first ultrasonic transmitting / receiving device ( 5 ) to check for deviations ( 3 ) of a geometry of the surface ( 2 ) of the workpiece ( 1 ), and one tangential to the surface ( 2 ) second ultrasonic transmitting / receiving device ( 6 ) for testing on from the surface ( 2 ) into the interior of the workpiece ( 1 ) extending errors ( 4 ). Apparatus according to claim 1, wherein for testing on the surface ( 2 ) into the interior of the workpiece ( 1 ) extending errors ( 4 ) a tangential to the surface ( 2 ) directed third ultrasonic transmitting / receiving device ( 7 ) is provided. Device according to one of the preceding claims, wherein the second ( 6 ) and the third ultrasonic transmitting / receiving device ( 7 ) in parallel alignment with the workpiece ( 1 ) Send ultrasound to the surface of the workpiece. Device according to one of the preceding claims, wherein the second ultrasonic transmitting / receiving device ( 6 ) with respect to the workpiece ( 1 ) is arranged so that the ultrasound transmitted in the direction of rotation (P) of the workpiece and the third ultrasonic transmitting / receiving Facility ( 7 ) is arranged so that the ultrasound transmitted against the direction of rotation (P) of the workpiece ( 1 ) can be coupled. Device according to one of the preceding claims, wherein means for simultaneously operating the first ( 5 ) and second ( 6 ) and optionally the third ultrasonic transmitting / receiving device ( 7 ) is provided. Device according to one of the preceding claims, wherein for testing on the surface ( 2 ) radial circumferential error a fourth ultrasonic transmitting / receiving device ( 8th ) directed towards the axis of rotation (R) and perpendicular to the axis of rotation (FIG. 8th ) extending radial plane (E) by an angle of 10 to 30 °, preferably 15 to 25 °, tilted. Device according to one of the preceding claims, wherein the first ultrasonic transmitting / receiving device ( 5 ) is arranged in the radial plane (E). Device according to one of the preceding claims, wherein the rotation device comprises two parallel-aligned rollers (with a gap therebetween and connected to a drive). 9 ). Device according to one of the preceding claims, wherein the first ( 5 ), second ( 6 ), possibly third ( 7 ) and optionally fourth ultrasonic transmitting / receiving device ( 8th ) on a plane parallel to the axis of rotation (R) along the surface ( 2 ) are mounted movable carriage. Device according to one of the preceding claims, wherein a device for moving the workpiece in a direction parallel to the axis of rotation (R) relative to the stationary arranged first ( 5 ), second ( 6 ), possibly third ( 7 ) and possibly the fourth ultrasound transceiver ( 8th ) is provided. Device according to one of the preceding claims, wherein a computer for evaluating the of the first ( 5 ), second ( 6 ), possibly third ( 7 ) and possibly the fourth ultrasound transceiver ( 8th ) provided signals is provided. Device according to one of the preceding claims, wherein a device for the successive automatic feeding and discharging of the workpieces to be tested ( 1 ) is provided.