Method for improved deburring of an aeronautical part

Abstract

A method for deburring an aeronautical part with an articulated tooling including a plurality of axes of rotation, the aeronautical part including at least one edge to be deburred, the articulated tooling including a tool holder, holding a calibration tool and a machining tool, the calibration tool and the machining tool being fixed to the tool holder and being immovable relative to one another, the method including steps of calibrating the calibration tool and the machining tool, of parameterizing the aeronautical part, of deburring the at least one edge to be deburred with the machining tool moving along a predetermined trajectory, on the basis of the parameters obtained during the parameterization step.

Claims

1. A method for deburring a turbomachine disk comprising a plurality of slots with an articulated tooling, the articulated tooling comprising a plurality of axes of rotation, the turbomachine disk comprising at least one edge to be deburred, the at least one edge to be deburred being a bottom edge of a slot of the plurality of slots of the disk, the articulated tooling comprising a tool holder, the tool holder holding a calibration tool and a machining tool, the calibration tool and the machining tool being attached to the tool holder and being immovable relative to one another, the method comprising steps of: calibrating the calibration tool and the machining tool to determine the relative position of the calibration tool relative to the machining tool, parameterizing the turbomachine disk via the calibration tool, to determine the position of the turbomachine disk relative to the articulated tooling, deburring the at least one edge of the bottom of the slot to be deburred with the machining tool moving along a predetermined trajectory, on the basis of the parameters obtained during the parameterizing.

2. The method according to claim 1, wherein the at least one edge to be deburred comprises a plurality of edges to be deburred uniformly distributed around a central axis of the turbomachine disk.

3. The method according to claim 1, wherein the predetermined trajectory is a circular arc.

4. The method according to claim 1, wherein the calibration step is carried out via successive contacts between at least one calibration ball and the calibration tool, and between the at least one calibration ball and the machining tool.

5. The method according to claim 1, comprising, between the parameterizing and the deburring, a step of defining, via the calibration tool, a first reference point on a first edge of the at least one edge to be deburred, and on the basis of parameters determined at the parameterizing, said first reference point being a starting point of the predetermined trajectory during the deburring.

6. The method according to claim 5, wherein, after deburring the first edge to be deburred, a second reference point is determined, via circumferential projection of the first reference point, on a second edge of the at least one edge to be deburred, and wherein according too the parameters determined in the parameterizing, then the second edge to be deburred is deburred starting from the second reference point and along the predetermined trajectory.

7. The method of claim 6, wherein the deburring and projection steps of reference points are repeated over at least a portion of the circumference of the turbomachine disk.

8. The method according to claim 1, wherein the articulated tooling is a robot with six axes of rotation, and wherein a single axis among the six axes is used during the deburring, the other axes being substantially fixed.

9. The method according to claim 8, wherein said single axis is oriented parallel to a central axis of the turbomachine disk during the deburring.

10. The method according to claim 1, wherein the machining tool is a hemispherical tip milling tool, and the calibration tool is a touch probe.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and its advantages will be better understood upon reading the detailed description given below of different embodiments of the invention, given by way of non-limiting examples. This description refers to the appended pages of figures, in which:

(2) FIG. 1 shows a perspective view of a turbomachine disk,

(3) FIG. 2 shows a transverse section of a slot of the disk of FIG. 1,

(4) FIG. 3 shows a slot bottom edge before and after deburring, in a section in a plane perpendicular to the plane of FIG. 2,

(5) FIG. 4 shows a perspective view of an articulated tooling,

(6) FIGS. 5A and 5B show partial perspective views of a step of deburring the disk of FIG. 1,

(7) FIG. 6 shows an overall perspective view of the disk of FIG. 1, of the articulated tooling of FIG. 4, and of a calibration ball,

(8) FIG. 7 shows a side view of the disk of FIG. 1, and its position in space relative to the articulated tooling,

(9) FIG. 8 shows schematically the steps of a method for deburring according to the present disclosure,

(10) FIG. 9 shows schematically the detailed steps of the calibrations step of the deburring method of FIG. 8,

(11) FIG. 10 shows schematically the detailed steps of the parameterization step of the deburring method of FIG. 8.

DESCRIPTION OF THE EMBODIMENTS

(12) In the embodiment described below, the aeronautical part is an aeronautical turbine disk 1. FIG. 1 illustrates a turbine disk of this type comprising a plurality of slots 2 distributed uniformly around the disk. FIG. 2 illustrates the distribution of the different zones of a slot 2. The latter has successively a V-shape entry 2a, a neck 2b, a flank 2c, a lobe 2d and a bottom 2e. In the embodiment described below, the edge to be deburred is the slot bottom edge 2e. More precisely, the disk 1 comprises a plurality of slots 2, in other words a plurality of edges to be deburred, each slot comprising a bottom 2e of which the upstream end and the downstream end comprises an edge. FIG. 3 illustrates an edge of this type in a transverse section of the bottom 2e of the slot, before a corner cutting or deburring operation (left-hand illustration in FIG. 3) and after a corner cutting operation (right-hand illustration in FIG. 3), by means of a cutting or abrasive tool.

(13) The method according to the present disclosure described below uses an articulated robot 100 with six axes 101, 102, 103, 104, 105 and 106. The articulated robot can be connected to a control unit (not shown), the control unit controlling individually each of the six axes of the robot. In order to dispense with the problem linked with cumulative errors by all of axes of the robot, the deburring work is carried out only on one axis, in particular the sixth axis 106 arranged at one end of the robot 100. In fact, the bottom of the slot 2e is formed only by a spoked shape. This radius can for example be 19 mm. hence a simple trajectory in one plane can allow the machining (or deburring) of the slot bottom edge 2e.

(14) FIGS. 5A and 5B show a deburring operation of a slot bottom edge 2e by rotation of a tool around the axis 106.

(15) A tool holder 20 is integral with the end of the robot 100, and movable in rotation around the axis 106. A machining tool 30 is attached to the tool holder 20 immovably relative to the tool holder 20. In this example, the machining tool 30 is a hemispherical tip milling tool, allowing obtaining a chamfer by using only the axis 106 of the robot 100.

(16) A touch probe 40 is also attached to the tool holder 20 immovably relative to the tool holder 20. In other words, the machining tool 30 and the touch probe 40 are immovable relative to one another, regardless of the movements carried out by the robot 100. Moreover, the machining tool 30 and the touch probe 40 are arranged on the tool holder 20 so that the transition from a probing operation by the touch probe 40 to a deburring operation by the machining tool 30 can be carried out by rotation of the tool holder 20 by means of movements of the axes of the robot 100.

(17) The machining tool 30 and the touch probe 40 are also connected to the control unit. The data detected by the touch probe 40, particularly during the calibration and parameterization steps described below, are transmitted to the control unit. The control unit thus controls the articulated tooling 100 and the machining tool 30 according to the parameters detected by the touch probe 40.

(18) A method of this type for deburring slot bottom edges 2e will be described hereafter in the description, with reference to FIGS. 6 to 10.

(19) The first phase of the method allows calibrating the touch probe 40 and the machining tool 30. In fact, before accomplishing the deburring, it is necessary to know the exact position of the part in space. It is therefore necessary to accurately calibrate in advance the touch probe 40 and the machining tool 30.

(20) The first step (step S100) allows calibrating the touch probe 40. To this end, a fixed calibration ball 50 is used. The calibration ball 50 is for example attached to the support 200 to which the disk 1 is also attached. The calibration of the touch probe 40 on the calibration ball 50 can be carried out by different suitable methods. In this example, the calibration of the touch probe 40 is carried out according to an iterative method comprising the acquisition of three points in a plane passing through the center of the calibration ball 50, for example in orientations of 0°, 90° and 180° relative to the ball 50 (step S101) and a point on a plane offset from the first, ideally normal to the plane defined previously (step S102). Calculation allows determining the position of the center of the calibration ball 50 (step 103) and to deduce the gauge, i.e. the x, y and z coordinates of the center of the sphere at the end of the touch probe 40 relative to the attachment point of the robot (step S104). An iterative method allows converging and refining the result. The iterative procedure ends when the measurement gap obtained for each coordinate between two iterations is less than a predetermined threshold value, this threshold value depending on the application considered. According to this embodiment, this threshold value is 0.05 mm. The steps S101 to S104 are repeated as long as the determined value is greater than or equal to 0.05 mm (“N” in step 105). When the determined value is less than 0.05 mm (“Y” in step S105), the method continues to the next step.

(21) A step complementary to step S100 can be carried out (step S200) and allows improving the accuracy of the calibration of the touch probe 40. This complementary step can be carried out or not depending on the application and on the accuracy expected of the system. It consists of accomplishing the same operations as those mentioned in step S100 with a second calibration ball (not shown) said to be movable (steps S201 to S205), which allows refining the calibration of the touch probe 40 obtained during step S100 with the fixed calibration ball 50.

(22) Step S300 comprises operations similar to those carried out in steps S100 and S200, applied to the machining tool 30. At the end of this step, the gauge, i.e. the position of the center of the hemispherical ball at the end of the machining tool 30 relative to the attachment point of the robot, is known. The relative position of the machining tool 30 relative to the touch probe 40 can thus be deduced.

(23) The following steps aim to determine the position of the disk 1 in space, relative to the robot 100. These steps allow a maximum reduction in localization errors and an increase in the accuracy of positioning. To this end, it is necessary to define the relative position of the disk 1 in space relative to the reference frame of the robot 100, more precisely relative to the reference frame of the tool holder 20, along the axis X, Y, Z, Rx, Ry and Rz.

(24) Firstly, a plane on an upper face of the disk 1 is probed by the touch probe 40 in order to define the positioning of the part along the reference axes Z, Rx and Ry (step S400). The plane thus determined serves as the first reference plane, or principal plane, of the part.

(25) After an offset of the touch probe 40 parallel to this first reference plane, three points are probed on the circumference of the disk 1, the touch probe 40 being oriented so as to extend parallel to the reference plane (step S500). This step allows defining the central axis A of the disk 1, and thus the positioning of the disk 1 along the reference axes Y and X. In other words, this step allows determining the position of the center of the disk 1 and its radius, according to the reference frame of the robot 100.

(26) The following positioning step (step S600) of the disk 1 allows defining the angular position of the disk 1 along axis Rz. This angular position is defined relative to the slots 2. The touch probe 40 probes the plane surface adjacent to the slots 2, in other words the rim of the disk 1, in order to defined whether a slot 2 is present or not and to iterate this probing until it probes a bottom point 2e of a slot 2. This operation allows roughly defining the positioning of the disk 1 and of the slots 2 along the axis Rz.

(27) The accurate positioning of the slots 2 and, more accurately, of the slot bottom 2e, is determined during the step S700. The accurate determination of the orientation of the disk 1 is carried out by the acquisition of a point on one upper face or one lower face of the rim at one end of the slot 2 (step S701). This probing allows creating a plane at the rim parallel to the reference plane defined in step S400.

(28) The touch probe 40 then carries out the acquisition of two points belonging to the plane defined in step S701 and arranged on the active flanks 2c on either side of the axis of the slot 2 (step S702).

(29) These two points allow deducing the center of the slot 2. This point is then measured by the touch probe 40 on the bottom of the slot 2e (step S703).

(30) This new point corresponds to the reference point x0, y0, z0 from which the machining tool 30 accomplishes the machining or deburring of a bottom edge 2e of the slot along a predetermined trajectory (step S800). This deburring is thus carried out starting from this reference point, along the predetermined reference trajectory, by rotation of the tool holder 20 around the axis 106 of the robot 100.

(31) Said predetermined reference trajectory accomplishes only the deburring of one slot bottom edge 2. To deburr the other slots 2, the reference point of this trajectory is projected circularly along the central axis A of the disk 1 determined in step S500 and on the basis of the parameters determined in steps S400 to S700.

(32) Moreover, step S703 can be carried out on three slots. For example, if the disk includes thirty slots, step S703 is carried out on the first, the fifteenth and the thirtieth slot. These three points obtained are on a circle with center A′ and radius R′, calculated on the basis of these three points. This center and this radius are substantially different from the center A and the radius R found in steps S500 and S703, because they take into account the geometric errors of the robot. In this case, the geometric projection calculated relative to A′ and R′ will integrate the errors of the robot.

(33) This method allows accomplishing these calculations and these positionings of the reference points, not relative to theoretical values, but relative to values detected by the robot.

(34) Although the present invention has been described by referring to specific exemplary embodiments, it is obvious that modifications and changes can be carried out on these examples without departing from the general scope of the invention as defined in the claims. In particular, individual features of the different embodiments illustrated/mentioned can be combined into additional embodiments. Consequently, the description and the drawings must be considered in an illustrative, rather than a restrictive sense.

(35) It is also clear that all the features described with reference to a method are transposable, alone or in combination, to a device, and conversely all the features described with reference to a device are transposable, alone or in combination, to a method.