FI92529C - Method for measuring a cylindrical piece - Google Patents

Description

92529

FIELD OF THE INVENTION from the surface of the body in a helical path at the desired measuring points.

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The invention relates to the measurement of cylindrical bodies which are difficult to rotate centrally. For example, the rotation of heavy cylindrical bodies in a central manner is generally not possible, because the body to be measured bends variably due to variations in gravity and bending stiffness, whereby the center line 15 of the body moves correspondingly variably. Also, parts that are rotated with their own bearings or with separately positioned bearings rotate so that they do not have a fixed center axis of rotation due to bearing defects.

Furthermore, measuring the diameter of a cylindrical body is often quite problematic because the measuring event is affected by incompleteness of rotation, errors in the feed movement of the measuring device, deflection due to gravity of the measured body, oscillations, etc. it is not possible to take into account the displacement of the center axis point during the measurement event in the measurement, the errors of the feed movement, the oscillations.

Measurements performed with a single sensor are known from the prior art, in which the sensor moves, for example, along a helical path on the surface of a cylindrical body. However, in measurements with one or two sensors, the measurement does not take into account 30 possible center offsets, in which case it cannot be deduced from the measurement result whether any change in the measured value is due to center offset or the shape of the object to be measured.

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A previously known solution using two distance sensors is shown in FI patent application 902497. In the method according to this reference for measuring the diameter and shape of a cylindrical body shell using non-contact distance sensors adapted to feel the distance between the cylindrical body being measured, the mutual distance vector is characterized in that measurement signals are taken out of said distance sensors, containing information about the distance of said sensors to a nearby jacket of the cylinder to be measured, and that the shape of the jacket of the cylinder to be measured

As is known, the cylindrical properties of cylindrical bodies have been measured in cross-sections as three-point measurements, in which the displacement of the center of the body can be taken into account. In this case, however, problems are caused by the slowness of the measurement and the fact that the accuracy of the 15 measurements is reduced by the stops caused by moving the measuring device to the next cross section to be measured. In this case, during the stop, the measuring device descends on top of the oil film, which causes a deviation in the trajectory of the measuring device. Furthermore, if the measurement results are used in the control of the work, e.g. grinding, the measurement path is different from the work path due to stops, in which case the work performed on the basis of the 20 measurement results may lead to an incorrect part.

With regard to the state of the art related to the invention, reference is also made to U.S. Patent 4,084,324, one embodiment of which discloses a measuring device having three sensors whose lines of action meet at a common point. The measuring device is supported so that three sensors can be used to measure the curved surface of the cylindrical body. The measuring device is held in place when the object to be measured is rotated in relation to it.

Referring to the prior art of the invention, reference is made to one of the inventors, Timo R. 30 Nyberg's dissertation "Dynamic Macro Topography of Large Slowly Rotating Cylinders", Acta Polytechnics Scandinavica, Mechanical Series no. 108, Helsinki

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3,92529 1993. In the present invention, the inventor has presented a method for measuring a cylindrical body by a three-point method in which the sensors used in the three-point method move in a helical path. The measurement method presented in this reference is a fast measurement method compared to the previously known ones discussed above, in which the measurement is performed as a continuous measurement along a helical path, whereby the problems of the prior art solutions described above are eliminated.

The object of the invention is to further develop the measurement method presented in this propeller and in particular to increase its accuracy, while maintaining the advantages already achieved.

In order to achieve the objectives set out above and later, the method according to the invention is mainly characterized in that, before starting the measurement, the sensors are placed in such a mutual inclined position that the measuring points on the same helical path are measured with the sensors.

In the invention, a remarkably high accuracy is achieved when, in a three-point measurement, the sensors traveling in a helical path are placed in such a mutual position that each sensor performs the measurement on the same helical path. The method 20 according to the invention makes it possible to measure the actual shape of the surface of a cylindrical body, which is a combination of diameter, roundness and straightness, as well as the movement of the central axis, while taking into account possible factors causing dimensional errors.

The multi-sensor method according to the invention uses three or more sensors. When using more than one sensor, several receivers of three sensors can be formed according to the measurement results, whereby the accuracy of the measurement results is further improved. According to the invention, the sensors are arranged so that when the measuring body travels at a constant feed rate and the object to be measured rotates at a constant rotational speed, the sensors follow the same helical path, i.e. the sensors are at an angle to the vertical direction of the cylindrical body 30.

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The invention is well suited for measuring large cylindrical bodies, e.g. paper machine rolls, rollers, film making cylinders, printing press cylinders, large shafts and generator and rotor shafts. The invention is also particularly well suited for measuring cylindrical bodies which are pressed by their own bearings.

The invention will now be described in more detail with reference to the figures of the accompanying drawing, in which Figure 1 schematically shows a measuring arrangement according to the invention in the longitudinal direction of a cylindrical body and Figure 2 shows a corresponding transverse direction of a cylindrical body.

Figures 1 and 2 show diagrammatically the measurement of a cylindrical body according to the invention. Object to be measured is designated by reference numeral 10 and measured sylinterimåinen piece 10 for attaching the device påadyiståån 11, wherein it further rotated in the direction of arrow S. Three sensors 22, 23 and 24 are attached to the measuring frame 20 on the support arm 21. Fig. 2 schematically shows a fourth sensor in the form of a broken line-20. The measuring points are denoted in the figure by the reference numeral P and the sensors 22, 23 and 24 are arranged such that their angle α is a multiple of the angle β between the measuring points P. When the measuring device 20 is fed from one end of the body 10 to be measured at a constant feed rate v to the other end when the body 10 to be measured rotates at a constant speed in the direction S, the measuring points P form a helical path T. so that they are at an angle γ with respect to the vertical transverse direction R of the body 10 to be measured.

If the sensor 22 is placed at the zero point Px on the transverse direction R, the next sensor 23 is inclined in this direction by a distance E23 and the sensor 24 by a distance E24 of 11 5 92529, respectively. The angle γ is determined by the rotational speed of the body 10 to be measured and the feed rate and distances E23 and E24 of the measuring device 20.

Referring to Figures 1 and 2, the measurement is performed as follows. In the first step of the method 5, the zero point Px of the measurement is selected, which is preferably horizontal, thus corresponding to, for example, the starting position of the grinding wheel used in the finishing work. A single sensor 22 is then placed at the zero point Px. , at several different points P, which can be several hundred, even thousands in one revolution, whereby the measuring points P settle on the helical path T. , e.g. an angle γ is formed between the line passing through the measuring points P. The angle a between the sensors 22,23,24 corresponds to a multiple of the angle β between the measuring points P.

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From the measurement results, the shape of the cylindrical body, the movement of the center point and the position of the cylindrical body, i.e. the alignment with respect to the guides, are calculated, whereby the dimensions of the cylindrical body have been measured in three dimensions.

25 Before starting the measurement, the rotation speed, the power used, the rotation time before the measurement, the surface temperature of the object to be measured and the positions of the sensors are determined as is known per se. On the basis of the measurement results obtained from the measuring points, the shape of the cylinder is determined, which consists of a cylindricality comprising thickness variation, straightness deviations and non-porosity, as well as dynamic components comprising the radial misalignment of the deflection motion. With regard to the handling of measurement data and the determination of their cylindricality, reference is made to the aforementioned Timo R. Nyberg impeller.

The invention has been described above only with reference to some of its preferred application examples, the details of which, however, are in no way narrowly limited, but many modifications and variations are possible within the scope of the inventive idea defined by the following claims.

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Claims (4)

A method of measuring a cylindrical piece, in which the method (10) to be measured is rotated and the sensors (22, 23, 24) attached to a measuring frame (20), of which there are at least three, are displaced by constant feed rate from one spirit of the piece (10) to be measured to the other spirit, whereby with the sensors (22.23.24), the distance to the sensor from the surface of the piece (10) to be measured is fed on a helical path at desired measurement points (P), characterized in that the sensors (22,23,24) before the measurement are started are placed in the inclined position of such an inboard, so that the sensors (22,23,24) measure points (P) on the same helical path (P). T). Measurement method according to claim 1, characterized in that one (22) of the sensors (22,23,24) used in the method is placed in a zero point (Px) and the other sensors (23,24) are placed vertically obliquely on a distance (E23, E24) from the zero point (Px), whereby a vertical transverse direction (R) of the piece (10) to be measured and a line passing through, respectively. measuring points (Px> P23, P24) of the givama (22.23.24) form an angle (γ). 3. A method according to claim 1 or 2, characterized in that, as angle (a) between the sensors (22,23,24), a plurality of angles (β) is selected between the measurement points (P). Method according to any one of the preceding claims, characterized in that the inclining layer embedded on the sensors (22,23,24) is determined on the basis of the rotational speed of the piece (10) to be measured and the feeding speed of the measuring device (20). . • · II