ADAPTIVE POSITIONING APPARATUS AND METHOD FOR THIN-WALLED NOZZLES

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of International Patent Application No. PCT/CN2025/147229, filed on December 30, 2025, which claims the benefit of priority from Chinese Patent Application No. 202511413546.4, filed on September 29, 2025. The content of the aforementioned application, including any intervening amendments thereto, is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] This application relates to machining technologies of thin-walled nozzles, and more particularly to an adaptive positioning apparatus and method for thin-walled nozzles.

BACKGROUND

[0003] A thin-walled nozzle is an indispensable structural component of an aerospace engine. However, due to characteristics such as small wall thickness, curved profile and poor rigidity, datum and contour errors are often inevitable in the thin-walled nozzles after stamping and forming. Direct machining on a machining center may cause deformation of the workpiece, making it difficult to meet design requirements. The existing supporting fixtures are highly specialized and unique in structure, with non-adjustable dimensions, such that they fail to be compatible with workpieces varying in dimension. Moreover, the clamping force is prone to cause deformation, which will result in non-uniform wall thickness, thereby failing to meet the requirements of machining accuracy and surface roughness.

SUMMARY

[0004] An object of the disclosure is to provide an adaptive positioning apparatus and method for a thin-walled nozzle, so as to address problems in the current machining of thin-walled nozzles, such as failure to meet design requirements for product accuracy and surface roughness, and uneven wall thickness. Simultaneously, the apparatus provided herein exhibits excellent universality and compatibility, thereby reducing the production costs and improving machining efficiency.

[0005] Technical solutions of the present disclosure are described as follows.

[0006] In a first aspect, this application provides an adaptive positioning apparatus for a thin-walled nozzle, comprising:

[0007]a mandrel:

[0008]a forming die; and

[0009]a positioning sleeve;

[0010]wherein the positioning sleeve is fixedly sleeved on the mandrel;

[0011]the forming die is configured to wrap the positioning sleeve, and is configured to slide with respect to the positioning sleeve;

[0012]an outer profile of the forming die is configured to fit an inner profile of a to-be-machined thin-walled nozzle;

[0013]an inner side of the forming die has a curved wall surface that is configured to converge;

[0014]an end of the positioning sleeve is provided with a protruding portion;

[0015]a root of the protruding portion is in contact with the curved wall surface of the forming die; and

[0016]in response to a case that relative sliding occurs between the forming die and the positioning sleeve, the protruding portion is configured to support the curved wall surface to enable the positioning sleeve to expand the forming die outwardly, thereby clamping the to-be-machined thin-walled nozzle.

[0017] In some embodiments, the forming die is circumferentially provided with a groove; an elastic member is provided in the groove; and the elastic member is configured to enable the forming die to wrap the positioning sleeve.

[0018] In some embodiments, the protruding portion has a truncated-cone shape.

[0019] In some embodiments, the mandrel and the positioning sleeve are circumferentially positioned by a key, and are axially positioned by a set screw.

[0020] In some embodiments, a first end of the forming die is axially clamped by a positioning nut, and a second end of the forming die is axially clamped by a retaining ring and a compression nut.

[0021] In some embodiments, the positioning nut is threadedly connected to the mandrel; and a calibration dial is provided adjacent to threads where the mandrel and the positioning nut are engaged to indicate an expansion degree of the forming die.

[0022] In some embodiments, the positioning nut is axially positioned with respect to the positioning sleeve via a set screw.

[0023] In some embodiments, the retaining ring is provided between the forming die and the compression nut; the compression nut is threadedly connected to the mandrel; and the compression nut is configured to be tightened to trigger relative movement between the forming die and the positioning sleeve, so as to expand the forming die.

[0024] In some embodiments, the forming die is made of copper.

[0025] In a second aspect, this application provides an adaptive positioning method for a thin-walled nozzle, the adaptive positioning method being performed based on the adaptive positioning apparatus described above, comprising:

[0026]sleeving and fixing the positioning sleeve onto the mandrel;

[0027]locating the forming die to wrap the positioning sleeve, such that a maximum diameter portion of the curved wall surface on the inner side of the forming die is in contact with the root of the protruding portion of the positioning sleeve;

[0028]sleeving the to-be-machined thin-walled nozzle onto the forming die;

[0029]mounting a retaining ring and a compression nut at a first end of the forming die;

[0030]tightening the compression nut, and simultaneously pushing the to-be-machined thin-walled nozzle and the forming die to move with respect to the positioning sleeve, so as to expand the forming die to make the forming die abut against the inner profile of the to-be-machined thin-walled nozzle;

[0031]fixing a positioning nut and a set screw on a second end of the forming die to secure the positioning sleeve, wherein the first end of the forming die is smaller than the second end of the forming die in size; and

[0032]after completion of machining the to-be-machined thin-walled nozzle, loosening the positioning nut and the compression nut, removing the retaining ring, and taking out a machined thin-walled nozzle.

[0033] Compared to the prior art, the present disclosure has the following beneficial effects.

[0034](1) The disclosure innovatively proposes an adjustable forming die for a thin-walled nozzle, where an expansion degree of the forming die is adjustable to make the forming die abut against the inner profile of the to-be-machined thin-walled nozzle, thereby eliminating fit clearance, ensuring wall thickness uniformity of the thin-walled nozzle, increasing a clamping contact area, and reducing clamping deformation caused by clamping forces. In addition, alignment can be achieved using a single apparatus for machining thin-walled nozzles having the same inner profile. Accordingly, the apparatus provided herein exhibits excellent universality and compatibility, thereby significantly reducing the production costs.

[0035](2) The disclosure relies on automatic self-centering between an arcuate surface of the forming die and a corresponding arcuate surface of the workpiece, such that the adjustment process is simple and requires no special operating skills from an operator, thereby increasing the clamping speed, improving machining efficiency, and reducing operator workload.

[0036](3) The disclosure employs a modular design, such that clamping of different thin-walled nozzles can be achieved by merely replacing different forming dies, and the modular design further allows replacement of only worn components, thereby reducing maintenance costs.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037]FIG. 1 schematically shows a clamping state of an adaptive positioning apparatus according to an embodiment of the present disclosure; and

[0038]FIG. 2 is an exploded view of the adaptive positioning apparatus according to an embodiment of the present disclosure.

[0039]In the figures: 1-positioning nut; 2-second set screw; 3-spring; 4-mandrel; 5-forming die; 6-first set screw; 7-positioning sleeve; 8-retaining ring; 9-compression nut; 10-thin-walled nozzle; 11-groove; and 12-protruding portion.

DETAILED DESCRIPTION OF EMBODIMENTS

[0040] To better understand the technical solutions of the disclosure, the embodiments of the disclosure are described below.

[0041]As shown in FIGS. 1-2, an embodiment of the present disclosure provides an adaptive positioning apparatus, including a positioning nut 1, a spring 3, a mandrel 4, a forming die 5, a positioning sleeve 7, a retaining ring 8 and a compression nut 9. The forming die 5 is sleeved on the mandrel 4. The forming die 5 is configured to wrap the positioning sleeve 7 through the spring 3. The spring 3 is an anti-disengagement spring. The forming die 5 is configured to slide with respect to the positioning sleeve 7. The forming die 5 is axially clamped by the positioning nut 1, the retaining ring 8, and the compression nut 9.

[0042]The forming die 5 is made of copper. An outer profile of the forming die 5 is configured to fit an inner profile of the thin-walled nozzle 10. The forming die 5 is formed into four uniform segments by wire cutting. An inner side of the forming die 5 has a curved wall surface, which is configured to converge from an end away from the retaining ring 8 to an end close to the retaining ring 8. An end of the positioning sleeve 7 is provided with a truncated-cone portion. A root of the truncated-cone portion of the positioning sleeve 7 is in contact with the curved wall surface on the inner side of the forming die 5. When the forming die 5 moves leftward, the truncated-cone portion of the positioning sleeve 7 radially expands the forming die 5.

[0043]The positioning nut 1 is threadedly connected to the mandrel 4. A calibration dial is provided adjacent to threads where the mandrel 4 and the positioning nut 1 are engaged, such that an expansion degree of the forming die 5 can be directly indicated, thereby facilitating adjustment. The mandrel 4 and the positioning sleeve 7 are circumferentially positioned by a key, and are axially positioned by a first set screw 6. The positioning nut 1 and the positioning sleeve 7 are axially positioned by a second set screw 2. The mandrel 4 is threadedly connected to the compression nut 9.

[0044]In use, the positioning sleeve 7 is sleeved onto a middle portion of the mandrel 4, and is fixed by tightening the first set screw 6. The spring 3 is configured to enable the forming die 5 to wrap the positioning sleeve 7, such that a maximum diameter portion of the curved wall surface on the inner side of the forming die 5 is in contact with a bottom surface of the root of the truncated-cone portion of the positioning sleeve 7.

[0045]The thin-walled nozzle 10 is sleeved onto the forming die 5 from a right end thereof, after which the retaining ring 8 and the compression nut 9 are installed. The compression nut 9 is tightened, the thin-walled nozzle 10 and the forming die 5 are simultaneously pushed to move leftward with respect to the positioning sleeve 7, thereby expanding the forming die 5 to make the forming die 5 abut against the inner profile of the thin-walled nozzle 10 to complete internal support. Subsequently, the positioning nut 1 and the positioning sleeve 7 are fixed by the second set screw 2.

[0046]The hexagonal positioning nut 1 at the left-end of the thin-walled nozzle 10 is clamped by a four-jaw chuck of the machine tool, and the right end of the thin-walled nozzle 10 is cantilevered, after which the outer profile of the thin-walled nozzle 10 is finish-machined. Upon completion of machining, the positioning nut 1 at the left end of the thin-walled nozzle 10 and the compression nut 9 at the right end of the thin-walled nozzle 10 are loosened, the retaining ring is removed, and the finish-machined thin-walled nozzle 10 is taken out.

[0047] Described above are merely illustrative, and are not intended to limit the scope of the present disclosure. It should be understood that various modifications, changes and replacements made by those skilled in the art without departing from the spirit of the disclosure shall fall within the scope of the present disclosure defined by the appended claims.

[0048] Any content not specifically described in the present disclosure is considered to be well known to those skilled in the art.