Assembly for producing a molding made of removable material of a turbomachine

Abstract

An assembly for producing a molding, made of removable material, of a turbomachine blade, includes an injection mold for the removable material in which a first core element and a second core element are mounted in a predetermined molding position, wherein the first and second core elements extend in a first direction. The mold includes a first face for molding a pressure-side face of the blade and a second face for molding a suction-side face of the blade and arranged facing the first face in a second direction perpendicular to the first direction. Retaining members hold the cores in position in the injection mold.

Claims

1. An assembly for producing a molding, made of removable material, of a turbomachine blade, comprising an injection mold for said removable material in which a first core element and a second core element are configured to be mounted in a predetermined molding position, the first and second core elements extending in a first direction, the mold comprising: a first molding face configured to mold a pressure-side face of the blade and a second molding face configured to mold a suction-side face of the blade and arranged facing the first face in a second direction perpendicular to the first direction, and retaining members configured to hold the cores in position in the injection mold, wherein at least a first retaining member extends from the first face of the mold in the second direction and extends at least partially through the first and second core elements, the first retaining member comprising a first support point at which the first retaining member bears against the first core element and a second support point at which the first retaining member bears against the second core element.

2. The assembly according to claim 1, wherein the first core element and the second core element are shaped so that the first support point of the first retaining member blocks movement of the first core element in a first directional orientation along a third direction perpendicular to the first and second directions, and the second support point of the first retaining member blocks movement of the second core element in a second directional orientation that is opposite to the first directional orientation along the third direction.

3. The assembly according to claim 1, wherein a second retaining member extends from the first molding face in the second direction, the second retaining member comprising a first support point at which the second retaining member bears against the first core element and a second support point at which the second retaining member bears against the second core element, said first support point and second point of support of the second retaining member being different from the first support point and the second support point of the first retaining member.

4. The assembly according to claim 3, wherein the first core element and the second core element are shaped so that the first support point of the second retaining member blocks movement of the first core element in the first directional orientation along a third direction perpendicular to the first and second directions and the second support point of the second retaining member blocks movement of the second core element in a second directional orientation that is opposite to the first directional orientation along the third direction.

5. The assembly according to claim 4, wherein the second retaining member comprises a spacing means between the first support point of the second retaining member and the second support point of the second retaining member, the spacing means ensuring, during production of the molding made of removable material, a spacing of a constant distance between said support points along the third direction.

6. The assembly according to claim 1, wherein the first retaining member comprises a spacing means between the first support point of the first retaining member and the second support point of the first retaining member, the spacing means ensuring, during production of the molding made of removable material, a spacing of constant distance between said support points along at least one among the first direction, the second direction, or the third direction.

7. The assembly according to claim 1, wherein the first retaining member and/or the second retaining member is movable between a retaining position, in which the second retaining member holds at least one core element, and a retracted position, the retaining member comprising a retraction mechanism configured to position the retaining member in the retaining position or in the retracted position.

8. The assembly according to claim 1, wherein the first retaining member and/or the second retaining member comprises an axis of rotation and a head that is eccentric relative to the axis of rotation and that cooperates with the first core element and the second core element.

9. A method for producing a molding, made of removable material, of a turbomachine blade, the method comprising: providing a first core element and a second core element, said core elements extending in a first direction; and providing an injection mold for said removable material, wherein the mold comprises: a first molding face configured to mold a pressure-side face of the blade and a second molding face configured to mold a suction-side face of the blade and arranged facing the first face in a second direction perpendicular to the first direction; and retaining members configured to hold the cores in position in the injection mold, among which at least a first retaining member extends from the first molding face in the second direction, the method further comprising the step of positioning the first core element and the second core element on the first molding face such that the first retaining member extends at least partially through the first and second core elements and comprises a first support point at which the first retaining member bears against the first core element and a second support point at which the first retaining member bears against the second core element.

10. The method according to claim 9, the mold further comprising a second retaining member extending from the first molding face in the second direction, the method further comprising the step of positioning the first core element and the second core element on the first molding face such that the second retaining member comprises a first support point at which the second retaining member bears against the first core element and a second support point at which the second retaining member bears against the second core element.

Description

DESCRIPTION OF THE DRAWINGS

(1) Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which:

(2) FIG. 1 shows a perspective view of a first and second core element placed on a first face of an injection mold for a removable material.

(3) FIG. 2 shows the view of FIG. 1 but without the first and second core elements, the first face of the injection mold comprising retaining members with support points for holding the leading and trailing cores.

(4) FIG. 3 shows a view of the leading core from its suction-side face, on which support points are schematically indicated.

(5) FIG. 4 shows a view of the trailing core from its suction-side face, on which support points are schematically indicated.

(6) FIG. 5 is a section view of FIG. 1 along axis A-A.

(7) FIG. 6 is a section view of FIG. 1 along axis B-B.

(8) FIG. 7 is a section view of FIG. 1 along axis B-B, illustrating a first example embodiment of a retaining member.

(9) FIG. 8 is a section view of FIG. 1 along axis B-B, illustrating a second example embodiment of a retaining member.

(10) FIG. 9 is a top view of the example shown in FIG. 8.

DETAILED DESCRIPTION

(11) The terms upstream and downstream used below are defined in relation to the direction of flow of gases through a turbomachine, indicated by arrow F in FIG. 1.

(12) FIG. 1 illustrates the arrangement of the core elements in an injection mold, only a first molding face 20 being illustrated. FIG. 1 illustrates that the core is in the form of a first core element and a second core element, hereinafter referred to as the leading core element 22 and the trailing core element 21.

(13) Paired core elements 21, 22 extend in three perpendicular directions, a first direction Z, hereinafter designated longitudinal direction Z corresponding in the final blade to the longitudinal direction connecting the root to the tip of the blade, a second direction Y, hereinafter designated transverse direction Y, passing through the pressure-side and suction-side faces of the blade, and a third direction X, hereinafter axial direction X, corresponding in the final blade to the upstream/downstream direction (arrow F). In FIG. 1, only the pressure-side face of leading core 23a and the pressure-side face of trailing core 23f are visible. The suction-side face of leading core 24a and the suction-side face of trailing core 24f, visible for each core in FIGS. 3 and 4, is arranged facing first molding face 20. Leading core element 22 and trailing core element 21 each comprise a head, respectively 25a, 25f, and a foot, respectively 26a, 26f, the head 25a, 25f being arranged at the opposite end from foot 26a, 26f along longitudinal direction Z. In the head area, each of the cores comprises a cutout 27a, 27f, meaning a portion with no material, which extends at least partially perpendicularly to longitudinal direction Z, along axial direction X. These cutouts also extend from pressure-side faces 23a, 23f towards suction-side faces 24a, 24f. These cutouts are intended to form a bottom wall of the squealer tip in the final blade. With reference to longitudinal direction Z and to FIG. 3, cutout 27a of leading core element 22 is delimited by an upper cutout wall 271a and a lower cutout wall 272a. Cutout 27a of the leading core extends over the entire width of the core, in axial direction X. With reference to longitudinal direction Z and to FIG. 4, cutout 27f of trailing core element 21 is delimited by an upper cutout wall 271f and a lower cutout wall 272f. Cutout 27f of trailing core extends over only part of the width of the core, along axial direction X. In particular, cutout 27f of trailing core extends from upstream edge 28 of the trailing core and ends in a longitudinal cutout portion 29 which extends longitudinally along longitudinal direction Z in the material of the core, and therefore without extending through the core to its downstream edge 30. Feet 26a, 26f further comprise a free end 31a, 31f, corresponding to a non-functional area of the core. Free ends 31a, 31f may at least partially overlap. For this purpose, free end 31f of the trailing core may comprise a tongue 33f. In addition, free end 31a of the leading core may comprise an indentation 33a. Indentation 33a is provided for receiving tongue 33f. The shapes are thus complementary between indentation 33a and tongue 33f. This overlap may allow hooking the two cores together in order to secure them to each other, for example by piercing the overlapping portion of material then inserting an aluminum rod.

(14) Trailing core element 21 further comprises a notch 32 in its downstream edge 30. Notch 32 is arranged in the area of head 25f. Notch 32 is substantially U-shaped, oriented so that the opening of the U-shaped concavity is oriented along axial direction X.

(15) FIG. 2 illustrates first molding face 20, without any core elements 21, 22. First molding face comprises retaining members P1a, P1f, P2a, P2f, P3a, P3f, P4, P5, P6a, P6f for holding the cores in position in the injection mold. Each retaining member holds leading core element 22 or trailing core element 21 or both core elements 21,22 in position, in one of the three directions X, Y or Z. In particular, and as detailed below, leading core element 22 is placed in the injection mold by a first positioning frame of reference, and trailing core element 21 is placed in the injection mold by a second positioning frame of reference. The first positioning frame of reference is formed by retaining members P1a, P2a, P3a, P4, P5 and P6a. The second positioning reference frame is formed by retaining members P1f, P2f, P3f, P4, P5 and P6f (or alternatively a point P6f). As a result, the injection mold comprises two different frames of reference, each intended for a different core, retaining members P4 and P5 being retaining members common to the two cores.

(16) In particular, retaining members P1a, P1f, P2a, P2f, P3a and P3f allow leading core 22 element or trailing core element 21 of both core elements 21, 22 to be held in position along transverse direction Y. Retaining members P1a, P2a, and P3a are provided for holding leading core element 22 in position along transverse direction Y. Retaining members P1f, P2f, and P3f are provided for holding trailing core element 21 in position along transverse direction Y. Each of retaining members P1a, P1f, P2a, P2f, P3a and P3f extends from first molding face 20, in transverse direction Y. Each of these members bears against one of the two cores, which prevents movement of the cores along transverse direction Y.

(17) In particular, retaining members P1a, P2a, P2f and P1f are arranged in the area of foot 26a, 26f of the cores. Retaining members P1a, P2a, P2f and P1f are aligned along axial direction X. Retaining members P1a, P2a, P2f and P1f are arranged near the free end 31a, 31f of the cores. In other words, retaining members P1a, P2a, P2f and P1f are arranged outside the free end of the cores, but in the area of foot 26a, 26f of the cores. Retaining members P1a, P2a, P2f and P1f end in a support surface for the respective core, each of these support surfaces being substantially flat. In addition, each of these support surfaces is substantially perpendicular to transverse direction Y. These surfaces are located outside the functional area.

(18) Retaining members P3a and P3f are arranged in the area of head 26a, 26f of the cores. Retaining member P3a and retaining member P3f are offset along longitudinal direction Z. In other words, retaining members P3a and P3f are not aligned along axial direction X. Retaining members P3a and P3f end in a support surface for the respective core, each of these support surfaces following the shape of the area of contact with the core. In other words, for optimal support, the support surfaces of retaining members P3a and P3f follow the shape of the surface of the core area with which they are in contact.

(19) Additionally and alternatively, the second molding face may comprise retaining members similar to the retaining members described above, so as to lock the cores in position along transverse direction Y.

(20) First molding face 20 may further comprise retaining members P6a and P6f. Retaining members P6a and P6f allow leading core element 22 or trailing core element 21 to be held in position along longitudinal direction Z, for example. Each of these members respectively bears against leading core element 22 and trailing core element 21, which prevents movement of the cores along longitudinal direction Z. Retaining member P6a is provided for example to retain leading core element 22 in position along longitudinal direction Z. Retaining member P6a extends from the first molding face, in transverse direction Y. Retaining member P6a bears against lower cutout wall 272a of leading core element 22. Retaining member P6f is provided, for example, for holding trailing core element 21 in position along longitudinal direction Z. Retaining member P6f extends from the first molding face, in axial direction X, in the downstream to upstream directional orientation. Retaining member P6f comes to rest in notch 32 of downstream edge 30 of trailing core element 21.

(21) Alternatively, a retaining member P6f may be provided instead of retaining member P6f. Retaining member P6f is provided for holding trailing core element 21 in position along longitudinal direction Z. Retaining member P6f extends from first molding face 20, in transverse direction Y. Retaining member P6f bears against lower cutout wall 272f of trailing core element 21. In addition, retaining members P6a and P6f are arranged so that the cutouts of the two cores are substantially aligned along axial direction X.

(22) Only one of the two retaining members P6f and P6f is used for the production of the wax molding, to position trailing core element 21 in longitudinal direction Z. Depending on the retaining member used, P6f or P6f, the retaining member not in use is removed from the molding surface so as not to create a hyperstatic system. The choice of which point to use depends on the distribution of the desired expansion of the two cores during casting of the alloy.

(23) In fact, retaining member P6 allows distributing the expansion of trailing core element 21 along longitudinal direction Z, towards head 25f and towards foot 26f, while avoiding too much of a difference in length compared to leading core element 22, particularly in the event of very different expansions between the two cores. On the other hand, retaining member P6f is advantageously used to control the dimensions of a so-called bottom wall of a squealer tip present in the final blade. The bottom wall of the squealer tip is physically realized by cutouts 27a, 27f of the cores, which form a portion filled with material in the final blade. The bottom of the squealer tip is substantially planar, and extends in transverse direction Y and axial direction X. Due to the fact that the cores do not touch one another, meaning that they are not in contact, a portion of material referred to as a residual wall of the squealer tip bottom, separates the squealer tip bottom into two parts arranged at different levels along longitudinal direction Z. Residual wall 26 extends in longitudinal direction Z, from the bottom of squealer tip. The height of the residual wall, in longitudinal direction Z, is a characteristic which must be controlled in order to meet the aerodynamic performance of the blade. Indeed, it is desirable that the height of the residual wall be as low as possible, so as to avoid, to the extent possible, too significant of a difference in level between the portions of the squealer tip bottom. Consequently, retaining member P6f, associated with retaining member P6a, places cutouts 27a and 27f in the same plane in the cores, which makes it possible to obtain two parts of the squealer tip bottom which are substantially in the same plane perpendicular to longitudinal direction Z.

(24) The first molding face further comprises retaining members P4 and P5. Retaining members P4 and P5 allow leading core element 22 or trailing core element 21 or both core elements 21,22 to be held in position along axial direction X. Retaining members P4 and P5 are retaining members common to the two cores, leading core element 22 and trailing core element 21. To this end, retaining members P4 and P5 each comprise a first support point at which it bears against the leading core and a second support point at which it bears against the trailing core. Retaining members P4 and P5 together prevent rotation of the cores around transverse axis Y. Each of retaining members P4 and P5 extends from the first molding face, in transverse direction Y.

(25) FIGS. 7, 8 illustrate example embodiments of a retaining member, in a section view in axial direction X. FIG. 9 is a top view of the example in FIG. 8. These example embodiments may apply for example to either of retaining members P4, P5 or to both retaining members P4 and P5. In these examples, the retaining member comprises a base 34 and a head 31. Base 34 is cylindrical. Base 34 is further arranged in the mold, and can pivot around its axis of rotation R which is coincident with its axis of revolution. Head 31 is a rod which extends in transverse direction Y, from base 34. In the example illustrated in FIG. 7, head 31 is aligned with the axis of rotation R. Consequently, the rotation of base 34 of the retaining member around the axis of rotation R does not cause any offset of head 31, i.e. no translational movement within the plane defined by the transverse Y and longitudinal Z directions. In the example illustrated in FIGS. 8 and 9, head 31 is eccentric relative to base 34. In other words, head 31 is not aligned with the axis of rotation R of base 34. Consequently, head 31 has, in this example, an eccentric function: head 31 moves in a plane defined by the transverse Y and longitudinal Z directions. This example advantageously makes it possible to move leading core element 22 and trailing core element 21, in order to adjust their position in the mold, leading core element 22 and trailing core element 21 cooperating with the retaining member as detailed further below in the description.

(26) Retaining member P4 (or first retaining member) may be arranged in the area of head 25a, 25f. Retaining member P5 (or second retaining member) may be arranged in the area of foot 26a, 26f at the connection to free end 31a, 31f. Retaining members P4 and P5 may further be aligned in longitudinal direction Z. Retaining members P4 and P5 are arranged in a non-functional zone, meaning external to the part.

(27) Retaining member P4 can be seen in FIG. 5, corresponding to a section view along axis A-A of FIG. 1. One can see that retaining member P4 comprises a first support point at which it bears against leading core P4a, and a second support point at which it bears against trailing core P4f. First support point P4a blocks movement of leading core element 22 from upstream to downstream in direction F1. Also, second support point P4f blocks movement of the trailing core from downstream to upstream in direction F2, meaning a direction that is opposite to the direction in which the leading core is blocked. Retaining member P4 may further be a through-member. Through-member is understood to mean that retaining member P4 extends from first molding face 20 to pressure-side face 23f of trailing core, respectively passing through the suction-side face of leading core 24a, the pressure-side face of leading core 23a, and the suction-side face of trailing core 24f.

(28) Retaining member P5 can be seen in FIG. 6, corresponding to a section view along axis B-B of FIG. 1. One can see that retaining member P5 comprises a first support point at which it bears against leading core P5a, and a second support point at which it bears against trailing core P5f. The first support point of retaining member P5a blocks movement of leading core element 22 from upstream to downstream in direction F1. Also, the second support point of retaining member P5f blocks movement of trailing core element 21 in direction F2 from downstream to upstream, meaning in a direction that is opposite to the direction F1 in which the leading core is blocked. Retaining member P5 may further be a through-member. Through-member is understood to mean that retaining member P5 extends from first molding face 20 towards pressure-side face 23a, 23f of the trailing core and leading core, and beyond suction-side face 24a, 24f of the cores, in transverse direction Y. However, as can be seen in FIG. 6, in transverse direction Y, retaining member P5 only extends through an alignment defined by suction-side faces 24a, 24f of the two cores, without extending through the cores. In other words, retaining member P5 is arranged between the two cores, and extends beyond their suction-side face 24a, 24f but without extending beyond their pressure-side face 23a, 23f. Alternatively, retaining member P5 may extend beyond their pressure-side face 23a, 23f.

(29) In addition, retaining member P4 and/or retaining member P5 may be movable between a retaining position and a retracted position. In the retaining position, visible in FIGS. 4 and 5, which may also be called the deployed position, the retaining member is in contact with at least one of the cores. In the retracted position, the retaining member is withdrawn relative to the cores, its length being less than its length in the retaining position. The mobility of the retaining member(s) makes it easy to unmold the obtained part. Indeed, when the retaining member, in its deployed position, is arranged along an axis different from the demolding axis, its retracted position allows the retaining member not to oppose the demolding. The retaining member further comprises a retraction mechanism, ensuring mobility between the retracted position and the retaining position.

(30) Alternatively, retaining member P4 and/or retaining member P5 may further comprise a spacing means D4, D5 between their first and second support points. The spacing means ensures a separation (or spacing) of a constant distance between the first and second support points, the separation distance being measured for example in axial direction X. More precisely, spacing means D4, D5 keeps the two cores spaced apart from each other without them being in contact, meaning without the cores touching each other. Given that the cores extend in the three spatial directions, the separation distance may be measured in longitudinal direction Z or in transverse direction Y. A spacing means is for example physically realized by the diameter of the retaining member. The retaining member may for example have a constant diameter along its entire length. According to another example, the retaining member may have a smaller diameter towards its free end, and a larger diameter towards its base (meaning towards the first molding face).

(31) Alternatively, retaining member P4 and/or retaining member P5 may further comprise adjustment means for adjusting the position of the cores in the first molding face. For example, the adjustment means is an eccentric, which may be rotated around transverse direction Y in order to shift the two cores in the plane formed by the transverse and axial directions.

(32) In another alternative, first molding face 20 may further comprise counter-braces, as illustrated in FIG. 2. One can thus see that first molding face 20 comprises, for leading core element 22, a first counter-brace 41a and a second counter-brace 42a. For trailing core element 21, first molding face 20 also comprises a first counter-brace 41f and a second counter-brace 42f. The counter-braces help retain the cores in the mold, as well as maintaining contact of the cores with the support points. For example, as can be seen in FIG. 6, first counter-brace 41a of leading core element 22 presses the leading core against retaining member P4. In addition, first counter-brace 41f of trailing core element 21 presses trailing core element 21 against retaining member P4. Also, as can be seen in FIG. 5, second counter-brace 42a of leading core element 22 presses the leading core against retaining member P5. In addition, first counter-brace 41f of trailing core element 21 presses trailing core element 21 against retaining member P5. As also can be seen in FIGS. 5 and 6, first counter-braces 41a, 41f and second counter-braces 42a, 42f respectively extend in axial direction X. Furthermore, first counter-braces 41a, 41f and second counter-braces 42a, 42f may be aligned along axial direction X with respective retaining members P4 and P5.

(33) Alternatively, although not illustrated, the elements described above for retaining member P4 may be applied to retaining member P5, and conversely the elements described above for retaining member P5 may be applied to retaining member P4. For this purpose, the first retaining member may be retaining member P5 and the second retaining member may be retaining member P4. Thus, the first support point and the second support point of first retaining member P5 may respectively be points P5a and P5f, and the first support point and the second support point of second retaining member P4 may respectively be points P4a and P4f.

(34) We now describe a method for producing a molding, made of removable material, of a turbomachine blade, the method comprising: providing leading core element 22 and trailing core element 21; providing the injection mold for the removable material; positioning leading core element 22 and trailing core element 21 on first molding face 20. In this position, the first retaining member has a first support point at which it bears against a first support surface of a core element, the first bearing surface extending against the core in order to hold the core element in position along the second direction. Furthermore, in this position, retaining member(s) P4, P5 at least partially extend(s) into leading core 22 element and trailing core element 21.

(35) Alternatively, the method may comprise: closing the mold while positioning on the core elements the second molding face, with at least one complementary retaining member.