Method for positioning an object having an angular scale

Abstract

The invention relates to a method for positioning an object with an angle scale, which object has an outer side (3.1) running along an arc of a circle, the method having the following steps: fixing the object (3) at a pivotable machine part (4); arranging a first distance meter (1) which is stationary in position; arranging a second distance meter (2) which is stationary in position; determining three first distance values (x1a, x1b, x1c) and three second distance values (z2a, z2b, z2c) at three defined angular positions of the machine part which are different from one another; calculating a first offset value (O1) on the basis of the three first distance values and the associated angular positions and a second offset value (O2) on the basis of the three second distance values and the associated angular positions; translating the object relative to the machine part until the first offset value is determined by the first distance meter and the second offset value is determined by the second distance meter within an admissible deviation.

Description

Technical Field

[0001] The present invention relates to a method for positioning or centering an object with an angle scale, the object being particularly useful as a measuring entity in an angle measurement system.

[0002] This type of angle measurement system is particularly used to measure the rotational motion or position of machine parts, such as shafts. Here, the rotational motion is detected incrementally or absolutely. The output measurement value is, for example, a sequence of counting pulses, a counter value, or a code word. The corresponding angle measurement system is especially used in machine tools for measuring pivotal motion, where the absolute accuracy of the measurement results is important. Therefore, the measurement results can be used in calibration methods, for example, executed in the machine tool's controller.

[0003] The accuracy of angle measurement is mainly affected by the quality of the angle scale and the eccentricity of the angle scale relative to the actual rotating shaft. Background Technology

[0004] A method for concentrically positioning two machine parts at a machine tool is described in published document EP 3 453 487 A1. This method uses a separate measuring gauge that pivots around an axis to multiple measuring positions. The measurements obtained at these positions are calculated to provide information on how to translate or pivot the sleeve until it is centered about the axis.

[0005] The disadvantage of this method is that the measuring instrument must move along a concentric circle around the axis. Summary of the Invention

[0006] The purpose of this invention is to create a method for positioning an object with an angle scale, characterized in particular by the ability to assemble the object simply and accurately even if the object or angle scale cannot be fully rotated 360° during adjustment.

[0007] The objective is achieved by the method of the present invention.

[0008] Therefore, the object has an angular scale and an outer surface extending along an arc. The method according to the invention is used to position an object and includes the following steps:

[0009] The object is fixed to a machine part that can pivot about a fixed axis.

[0010] A first rangefinder is positioned or installed in a fixed location, enabling the determination of a first distance value between a point on the outer surface of an object and a first fixed point.

[0011] A second rangefinder is positioned or installed in a fixed location, enabling the determination of a second distance value between another point on the outer surface of the object and the second fixed point. Here, the first rangefinder is arranged such that the outer surface of the reference object is offset at an angle in the circumferential direction relative to the second rangefinder.

[0012] Three first distance values ​​and three second distance values ​​are determined at three distinct angular positions of the machine component. (In particular, simultaneously) three second distance values ​​are determined at the three angular positions of the machine component. In this method step, the machine component is pivoted in a defined manner to the corresponding angular position to measure the distance values ​​between three pairs of points on the outer surface.

[0013] A first offset value is calculated based on three first distance values ​​and the associated angular position, and a second offset value is calculated based on three second distance values ​​and the associated angular position.

[0014] The object is translated relative to the machine parts, or more precisely, translated until it is within the allowable deviation, with a first offset value output or determined by a first rangefinder, and a second offset value output or determined by a second rangefinder.

[0015] The attribute "fixed position" here means immovable. "Fixed position" can in particular indicate the relative immovability of the machine base of the reference machine part.

[0016] The distance value represents the distance between a fixed point and a point on the outer surface. Specifically, the outer surface of a cylindrical object can be understood as its outer side. In the case of hollow cylindrical or ring-shaped objects, the inner concave surface extending along the arc can also be understood as the outer side.

[0017] The object is advantageously constructed as a ring. In the following text, the object does not necessarily have to have an outer surface that wraps around the entire surface in 360°. Rather, the object can have an open shape, for example, constructed as a ring segment, so that the outer surface is not completely ring-shaped.

[0018] In another embodiment of the invention, the object has an angle scale on its outer surface.

[0019] This method can be advantageously used when the pivoting capability of machine parts is limited to an angular range of less than 360°, especially less than 270°, and especially less than 180°.

[0020] In another design of this method, the three corner positions of the machine component are located in angular segments that extend at least 33% of the pivotable angular range. Therefore, the three corner positions are selected such that they are located in angular segments that extend at least 33% of the angular range. Advantageously, the angular segments can extend at least 50% of the angular range.

[0021] Advantageously, the three corner positions of the machine parts are located in angular segments that extend less than 180°, and particularly less than 100°.

[0022] Advantageously, the outer surface of the reference object of the first rangefinder is offset relative to the second rangefinder by an angle of at least 20° in the circumferential direction, and advantageously at least 30° or at least 45°.

[0023] In another embodiment of the invention, the first rangefinder is constructed as a contact measuring device. Alternatively or additionally, the second rangefinder is constructed as a contact measuring device. The contact measuring device can particularly be constructed as a measuring meter or measuring probe. Such a device typically has a measuring pin, which is repositionably supported within the housing of the rangefinder or measuring meter. The placement or mounting of the two rangefinders is carried out such that the longitudinal axis of the measuring pin is oriented along a direction about a second pivotal axis of the machine component.

[0024] Instead of contact measuring devices, the first and / or second rangefinders can be configured as non-contact distance measuring devices.

[0025] When the method according to the invention is completed, the object with the angle scale is precisely adjusted or centered so that the assembly at these positions meets the prerequisite of high-quality angle measurement.

[0026] This invention is not limited to objects with cylindrical or ring-shaped structures. For example, an object may also be constructed as a ring segment, especially since the rotational position of a machine part is generally not measured by the complete rotation of the machine part.

[0027] The present invention has the particular advantage of significantly simplifying the positioning for users of such angle measuring devices, especially when the pivoting capability of machine parts is limited to a relatively small angular range, so that the corresponding users do not need to have complex installation equipment.

[0028] Advantageous implementations of the method according to the invention can be derived from the design of the invention. Attached Figure Description

[0029] Further advantages and details of the method according to the invention will become apparent from the following description of embodiments with reference to the accompanying drawings.

[0030] Figure 1 The image shows a view of the rangefinder and the object at the start of the positioning process.

[0031] Figure 2 A graph showing the measured distance values ​​and calculated offset values.

[0032] Figure 3 This shows a view of the rangefinder and the object at the end of the positioning process. Detailed Implementation

[0033] according to Figure 1 The object 3, constructed as a ring, is fixed and centered at the machine component 4. The object 3 is precisely manufactured by turning or grinding, such that its outer surface 3.1 extends with extreme precision along an arc surrounding the first axis A3. An angle scale is applied to the outer surface 3.1. In the described embodiment, this angle scale is an optically readable angle scale with reflective and non-reflective fringes. The object 3 belongs to a modular angle measurement system in which the angle scale can be scanned and a high-precision value of the angular position can be obtained.

[0034] Machine component 4 can be, for example, the axis of a machine tool's pivot table. Machine component 4 can pivot about the second axis A4 by an angle. In this embodiment, the machine component 4 can only be deflected within a maximum angle range of 90°. ( Figure 2 The pivoting motion is centrally rotated. As defined, the second axis A4 is fixed in position. The accuracy of the pivoting motion should be checked and quantitatively tested using an object 3 with an angle scale. Unrelatedly, the machine tool has an angle measuring device that can measure the angular position of the machine part 4 relative to the second axis A4.

[0035] During the installation of object 3, object 3 is first secured to the pivotable machine component 4. Here, object 3 is fixed to machine component 4 by elastically loaded bolts (not shown in the accompanying drawings), ensuring reliable fastening relative to machine component 4 while still allowing for relatively small force-consuming translation in a plane perpendicular to axis A4. After this initial fastening, the first axis A3 and the second axis A4 are typically not coincident, allowing object 3 to be arranged with a certain degree of eccentricity relative to the second axis A4 or machine component 4. When assembling this modular angle measurement system, the user must ensure that object 3 is accurately positioned at the machine component 4 designated for this purpose.

[0036] In the next step, the first rangefinder 1 is fixedly positioned near the outer surface 3.1, thereby allowing the determination of a first distance value x between the outer surface 3.1 of the object 3 and the first fixed point P1. In this embodiment, the first rangefinder 1 is a measuring instrument or a so-called measuring probe. With the aid of this rangefinder 1, distance or distance changes can be determined with a resolution in the micrometer range.

[0037] A second rangefinder 2 is fixedly positioned on the outer surface 3.1 of the reference object 3, offset by an angle α (where α = 90°) in the circumferential direction and staggered relative to the first rangefinder 1. The second rangefinder 2 is configured such that a second distance value z between the second fixed point P2 and the outer surface 3.1 of the object 3 can be determined. In this embodiment, the second rangefinder 2 is also constructed as a measuring instrument and has the same high measurement accuracy as the first rangefinder 1.

[0038] In the following text, object 3 will be placed according to... Figure 1 The position. Therefore, it can also be accessed via the angular position. At this defined position, the distance x1a between the first fixed point P1 and point 1a on the outer surface 3.1 is determined by the first rangefinder 1. Simultaneously, the distance z1a between the second fixed point P2 and another point 2a on the outer surface 3.1 is determined by the second rangefinder 2. Then, the machine component 4, together with the object 3, pivots around the second axis A4 by a predetermined angle, which is 30° in this case. For example, the pivot angle can be determined with sufficient accuracy using an angle measuring device inherent in the machine tool. Second corner position The distances x1b and z2b from points 1b and 2b are obtained. Then, machine part 4 and object 3 pivot again around the second axis A4 by a predetermined angle, which is 30° in this embodiment. At this position, machine part 4 and object 3 are located at the third angle. Also determine the distance values ​​x1c and z2c at this location.

[0039] Instead of using an angle measuring device, marks can be applied to object 3 or machine part 4 at defined and known angular intervals, and then these marks can be continuously approached.

[0040] Therefore, at each corner position Determine a pair of distance values: x1a, z2a; x1b, z2b; x1c; z2c.

[0041] After measurement, at three distinct angular positions of machine part 4. Three first distance values ​​x1a, x1b, x1c and three second distance values ​​z2a, z2b, z2c are determined. According to this embodiment, the following information is particularly relevant:

[0042]

[0043] The three corner positions of machine part 4 Located in the angle section In the middle, this angular segment extends through 60° (see...). Figure 2 In other words, angular position. The maximum difference between the two corner positions in the middle is the difference. The difference is 60°. Furthermore, smaller than As described above, the pivoting capability of machine component 4 is limited to an angular range. This angle range is based on Figure 2 At the end corner position and Extending between The three corner positions of machine part 4 Located in the 60° angle section In the middle, this angular segment extends through the angular range. 66.67%

[0044] Based on the first distance values ​​x1a, x1b, x1c and the angular position The first sine function F1 is determined by regression calculation. Figure 2 Similarly, based on the second distance values ​​z2a, z2b, z2c and the angular position... The second sine function F2 is determined using the same method. A first offset value O1 can be calculated for the first sine function F1, and a second offset value O2 can be calculated for the second sine function F2. Offset values ​​O1 and O2 correspond to the zero lines of the two sine functions F1 and F2, respectively. Therefore, sine functions F1 and F2 enclose areas of equal size above and below their respective offset values ​​O1 and O2, where... Offset value As shown, this consideration can be applied to the complete period of the corresponding sine functions F1 and F2.

[0045] In this embodiment, the following offset values ​​O1 and O2 are obtained:

[0046] O1 = 1511 μm O2 = 2009 μm ​

[0047] Now, object 3 is translated relative to machine part 4 (e.g., by tapping with a suitable tool) so that the displays of rangefinders 1 and 2 show values ​​close to offset values ​​O1 and O2. In this method, the direction of translation toward the target can be identified relatively easily by the operator. Once the two current distance values ​​correspond to offset values ​​O1 and O2 within permissible deviations due to the translation of object 3, the object is centered with sufficient accuracy relative to the second axis A4. At this position, object 3 is now fixedly and immovably connected to machine part 4, for example, by bolts.

[0048] Finally, the rangefinders 1 and 2 can be removed again, and the movement of the machine tool can be precisely measured at the location of the machine part 4 using an object 3 with a precise angular scale.

Claims

1. A method for positioning an object (3), said object having an outer surface (3.1) extending along an arc, and said object including an angle scale, said method comprising the steps of: The object (3) is fixed to a machine part (4) that can pivot about a fixed axis (A4); A first rangefinder (1) is fixed in position, so that a first distance value can be determined between the outer surface (3.1) of the object (3) and the first fixed point (P1); A second rangefinder (2) is fixed in position, enabling the determination of a second distance value between the outer surface (3.1) of the object (3) and the second fixed point (P2), wherein, The first rangefinder (1) is arranged such that the outer surface (3.1) of the object (3) is offset by an angle (α) in the circumferential direction relative to the second rangefinder (2); At three distinct angular positions of the machine component (4) a, b, c) Determine three first distance values ​​(x1a, x1b, x1c) and three second distance values ​​(z2a, z2b, z2c); Based on the three first distance values ​​(x1a, x1b, x1c) and the associated angular position ( a, b, c) Calculate the first offset value (O1), and based on the three second distance values ​​(z2a, z2b, z2c) and the associated angular position ( a, b, c) Calculate the second offset value (O2); The object (3) is translated relative to the machine part (4) until it is within the allowable deviation, the first offset value (O1) is determined by the first rangefinder (1), and the second offset value (O2) is determined by the second rangefinder (2).

2. The method according to claim 1, wherein, The pivoting capability of the machine component (4) is limited to an angular range of less than 360°. S).

3. The method according to claim 2, wherein, The pivoting capability of the machine component (4) is limited to an angle range of less than 270°. S).

4. The method according to claim 1, wherein, The pivoting capability of the machine component (4) is limited to a certain angular range. S), and the three angular positions of the machine component (4) a, b, c) is in an angle segment ( In m), the angle segment extends at least through the angle range ( 33% of S).

5. The method according to claim 1, wherein, The three angular positions of the machine component (4) a, b, c) is in an angle segment ( In m), the angle segment extends less than 180°.

6. The method according to claim 1, wherein, The angle (α) is at least 20°.

7. The method according to claim 1, wherein, The first rangefinder (1) and / or the second rangefinder (2) are configured as contact measuring devices.

8. The method according to claim 1, wherein, The object (3) is constructed in a ring shape.

9. The method according to any one of claims 1 to 8, wherein, The object (3) has the angle scale on the outer side (3.1) of the object.

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