A clamping tool for thin-walled curved surface parts and a thin-walled curved surface part machining method

Abstract

The embodiment of the application discloses a clamping tool for a thin-wall curved surface part and a thin-wall curved surface part machining method, relates to the technical field of machining, and comprises a male mold, a female mold and an adjusting block, the adjusting block is arranged on the fitting surface of the male mold, the height of the adjusting block is adjustable, and when a target part is wrapped between the fitting surfaces of the male mold and the female mold, the end of the adjusting block is in contact with the first surface of the target part. The male mold and the female mold are designed to match the shape of the fitting surface, the part to be machined is covered in the inner cavity after being buckled, and the two surfaces of the part are respectively fitted by the fitting surfaces of the male mold and the female mold. Since the fitting surface of the male mold located below is further provided with the adjusting block, the height of the adjusting block can be adjusted, the gap between the part and the male mold can be adjusted, the part can be stress-free clamped in the case that the part has uneven thickness and deformation, the clamping deformation of the part is reduced, and the machining precision of the part is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of machining, in particular to a clamping tool for a thin-walled curved part and a thin-walled curved part machining method. BACKGROUND

[0002] Materials represented by ceramics, composite ceramics and ceramic matrix composites are usually prepared into part blanks in a near-net shape. If the part is a thin-walled curved part, the thickness of the blank prepared by any process usually has a certain error, and the surface error is usually large. For hard and brittle material parts used in the field of aerospace, the size and shape accuracy of the parts are usually required to be high, and the directly formed blanks cannot meet the use requirements and must be machined.

[0003] However, the near-net forming process of the hard and brittle material part blank results in a small machining allowance, and the blank usually does not have a high-precision reference surface. The conventional way of directly clamping the blank on the tool with a pressing plate or a screw will cause a slight deformation of the blank under the clamping force, and at this time, directly machining the part surface will cause the part to deform after the clamping force is released. When machining the next surface, the machining error caused by the slight deformation will be further accumulated on the next surface, resulting in an increasingly large machining error of the part as the machining process proceeds. Finally, the thickness and surface accuracy of the machined part cannot be guaranteed, and high-precision machining cannot be achieved. SUMMARY

[0004] The main purpose of the present application is to provide a clamping tool for a thin-walled curved part and a thin-walled curved part machining method, which aims to solve the problem of low machining accuracy of the thin-walled curved part in the prior art.

[0005] To achieve the above-mentioned purpose, the technical solutions adopted by the embodiments of the present application are as follows:

[0006] In a first aspect, the embodiments of the present application provide a clamping tool for a thin-walled curved part, comprising a male die, a female die and an adjusting block, wherein:

[0007] The shapes of the mating surfaces of the male die and the female die are matched, so that when the male die and the female die are buckled, the target part is wrapped in the inner cavity between the mating surfaces of the male die and the female die, and the mating surface of the male die is matched with the first surface of the target part, and the mating surface of the female die is matched with the second surface of the target part. The first surface of the target part is a machining reference surface;

[0008] The adjusting block is arranged on the mating surface of the male die, and the height of the adjusting block is adjustable, so that when the target part is wrapped between the mating surfaces of the male die and the female die, the end of the adjusting block is in contact with the first surface of the target part.

[0009] In a possible implementation manner of the first aspect, the fitting surface of the male mold is provided with a first threaded hole, and the adjusting block is threadedly connected with the male mold through the first threaded hole.

[0010] In a possible implementation manner of the first aspect, the adjusting block comprises a sleeve and a stud, the sleeve is threadedly connected with the male mold through the first threaded hole, the first threaded hole is a through hole, and the stud is arranged in the sleeve and threadedly connected with the sleeve.

[0011] In a possible implementation manner of the first aspect, the female mold is provided with a medium injection hole, the medium injection hole is communicated with the inner cavity, and the medium injection hole is used for injecting the filling medium into the inner cavity from the outside.

[0012] In a possible implementation manner of the first aspect, the clamping tool further comprises a latch, the female mold is provided with a medium outflow hole, the medium outflow hole is communicated with the inner cavity, and the latch is inserted into the medium outflow hole.

[0013] In a possible implementation manner of the first aspect, the clamping tool further comprises a film, the film is arranged between the target part and the fitting surface of the female mold, so as to separate the female mold from the filling medium.

[0014] In a possible implementation manner of the first aspect, the fitting surface of the female mold is provided with a second threaded hole, the second threaded hole is used for threadedly connecting with a screw, and the end of the screw is in contact with the second surface of the target part.

[0015] In a possible implementation manner of the first aspect, the end of the adjusting block is in a ball shape.

[0016] In the second aspect, the embodiments of the present application provide a processing method for a thin-walled curved surface part in a composite material bonding process, comprising the following steps:

[0017] According to the envelope condition of the reconstructed three-dimensional model of the part blank and the three-dimensional model of the target part, it is judged whether the target part can be processed, and in the case that the target part can be processed, the adjusting block of the clamping tool for the thin-walled curved surface part provided in any one of the first aspect is installed on the male mold, and the height of the adjusting block is adjusted;

[0018] After the first surface of the part blank is fitted with the fitting surface of the male mold, the female mold is buckled with the male mold, so that the second surface of the part blank is fitted with the fitting surface of the female mold;

[0019] The filling medium is injected into the inner cavity between the fitting surfaces of the male mold and the female mold, after the filling medium is solidified, the female mold and the part blank are separated from the male mold and placed upside down;

[0020] The part blank is fixed on the female mold, and the processing of the positioning surface of the first surface of the part blank is performed;

[0021] Separate the part blank from the female mold, and process other structural features of the part blank based on the positioning surface.

[0022] In a possible implementation manner of the second aspect, after the first surface of the part blank is attached to the attachment surface of the male mold, before the second surface of the part blank is attached to the attachment surface of the female mold, the method further includes:

[0023] Cover the second surface of the part blank with a film.

[0024] Compared with the prior art, the application has the following beneficial effects:

[0025] The clamping tool and the part machining method provided by the embodiments of the application can clamp the part without stress in the case that the part has uneven thickness or deformation, and reduce the clamping deformation of the part, so that the precision of the finally machined part is improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A structural schematic diagram of the clamping tool for the thin-walled curved surface part provided by the embodiments of the application is shown in the figure.

[0027] Figure 2 A structural schematic diagram of the male mold in the clamping tool for the thin-walled curved surface part provided by the embodiments of the application is shown in the figure.

[0028] Figure 3 A structural schematic diagram of the female mold in the clamping tool for the thin-walled curved surface part provided by the embodiments of the application is shown in the figure.

[0029] Figure 4 A structural schematic diagram of the part placed on the male mold in the clamping tool for the thin-walled curved surface part provided by the embodiments of the application is shown in the figure.

[0030] Figure 5 A structural schematic diagram of the part placed on the female mold in the clamping tool for the thin-walled curved surface part provided by the embodiments of the application is shown in the figure.

[0031] Figure 6 A flowchart of the part machining method for the thin-walled curved surface part provided by the embodiments of the application is shown in the figure.

[0032] Figure 7 A diagram of the height error of the adjusting block in the part machining method for the thin-walled curved surface part provided by the embodiments of the application is shown in the figure.

[0033] Figure 8 The flowchart of the thin-walled curved part machining method provided by the embodiment of the present application in one implementation is shown in the figure.

[0034] The figure is marked: 1-male die, 2-female die, 21-medium outflow hole, 22-second threaded hole, 23-medium injection hole, 3-female die male die bolt, 4-bolt, 5-adjusting block, 51-theoretical position of adjusting block, 52-actual position of adjusting block, 53-height error of adjusting block, 6-blank part, 7-film, 8-fixture clamping screw, 9-fixture clamping screw gasket, 10-screw, 11-screw gasket. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0036] It should be noted that all directional indications, such as up, down, left, right, front, back, etc., in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0037] In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixation", etc. should be understood broadly, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be direct connection, or indirect connection through intermediate medium; can be internal connection of two elements or interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0038] In addition, if the description of "first", "second" and the like is involved in the embodiments of the present application, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the technical features indicated or implicitly indicating the number of technical features. Therefore, the features limited by "first", "second" can be explicitly or implicitly included at least one of the features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. For example, "A and / or B" includes A scheme, or B scheme, or A and B scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0039] The materials represented by ceramics, composite ceramics and ceramic matrix composites are usually prepared into part blanks by near-net-shape forming. If the part is a thin-walled curved surface part, the thickness of the blank prepared by any process usually has a certain error, and the surface error is usually large. For hard and brittle material parts used in the field of aerospace, the part size and shape accuracy are usually required to be high, and the directly formed blanks cannot meet the use requirements and must be machined.

[0040] However, the near-net-shape forming process of hard and brittle material part blanks results in small machining allowance, and the blank usually does not have a high-precision reference surface. The conventional way of directly clamping the blank on the tool with a press plate or a screw will cause a small deformation of tens of microns of the blank under the action of clamping force. At this time, directly machining the part surface, the part will appear springback deformation after the clamping force is released. When machining the next surface, the machining error caused by the small deformation will be further accumulated on the next surface, resulting in the machining error of the part becoming larger and larger with the development of the machining process. Finally, the thickness precision and surface precision of the machined part cannot be guaranteed, and high-precision machining cannot be achieved.

[0041] As the invention application with application number CN202110571734.5 and title "A flexible tool for aircraft skin part machining and its using method", a flexible tool is proposed, which includes a bottom plate, a base plate, a buckle, a flexible auxiliary component and a foam groove. The flexible auxiliary component and the foam groove are respectively arranged between the bottom plate and the base plate. The flexible auxiliary component is used to support the skin part and limit its position. The foam groove matches the edge profile of the skin part, and encloses the non-machining surface of the skin part to form a cavity for pouring PCL plastic. Through the flexible tool and its using method, the shape of the skin part can be self-adapted, the problem of insufficient adhesion of flexible support and parts can be effectively solved, and stable support and holding of the skin part with great elasticity can be realized. However, this scheme only solves the problem of how to make the skin part completely adhere to the tool, and does not provide an effective method for adjusting the blank pose, so it cannot realize high-precision machining of near-net-shaped hard and brittle material thin-walled curved surface parts.

[0042] For example, the invention application with application number CN201210306821.9 and title "Auxiliary tool for high-precision thin part", the end face of the thin-walled part in the non-working area is milled into a chamfer, and the thin-walled part is clamped in the auxiliary tool. The clamping end of the auxiliary tool is provided with a reverse chamfer matched with the chamfer on the thin-walled part, so as to realize high-precision grinding machining of the easily deformed non-ferrous metal thin-walled part. However, this method is suitable for plastic non-ferrous metal parts, and the necessary chamfer can be machined on the part. It is not suitable for near-net-shaped hard and brittle material thin-walled curved surface part machining.

[0043] The above-mentioned methods are all special machining methods for special structure parts. The part material is usually a material with good plasticity, and the part usually has a rough reference or positioning surface. For near-net-shaped hard and brittle material curved surface parts with both part thickness precision requirements and part surface precision requirements, the above-mentioned methods cannot meet the high-precision machining requirements.

[0044] Therefore, the embodiments of the present application provide a clamping tool for thin-walled curved surface parts, as shown in the accompanying drawings Figure 1 -attached Figure 5 As shown, it includes a male die 1, a female die 2 and an adjusting block 5, wherein: the shapes of the mating surfaces of the male die 1 and the female die 2 are matched, so that when the male die 1 and the female die 2 are buckled, the target part is wrapped in the inner cavity between the mating surfaces of the male die 1 and the female die 2, and the mating surface of the male die 1 is matched with the first surface of the target part, and the mating surface of the female die 2 is matched with the second surface of the target part. The first surface of the target part is the reference surface to be machined; the adjusting block 5 is arranged on the mating surface of the male die 1, and the height of the adjusting block 5 is adjustable, so that when the target part is wrapped between the mating surfaces of the male die 1 and the female die 2, the end of the adjusting block 5 is in contact with the first surface of the target part.

[0045] In this embodiment, the male die 1 and the female die 2 are designed to match the shape of the fitting surface to cover the part to be processed in the inner cavity after buckling. Since the blank part needs to be processed to obtain the desired part, the target part in this embodiment is the blank part 6 as shown in the accompanying drawings. The fitting surfaces of the male die 1 and the female die 2 are respectively fitted to the two surfaces of the part. Since the fitting surface of the male die 1 located below is also provided with an adjusting block 5, the height of the adjusting block 5 can be adjusted to adjust the gap between the part and the male die 1. In the case of uneven thickness and deformation of the part, the part can be clamped without stress, which reduces the clamping deformation of the part and improves the precision of the finally processed part. Figure 4

[0046] In one embodiment, an adjusting block 5 is provided to adjust the height. A first threaded hole is formed in the fitting surface of the male die 1, and the adjusting block 5 is threadedly connected to the male die 1 through the first threaded hole. The depth of the threaded connection between the adjusting block 5 and the male die 1 is adjusted by rotating, thereby achieving the adjustment of the height. Further, in order to facilitate the adjustment, the adjusting block 5 is provided in the form of a sleeve and a stud. The sleeve is threadedly connected to the male die 1 through the first threaded hole, the first threaded hole is a through hole, and the stud is arranged in the sleeve and threadedly connected to the sleeve. As in the above embodiment, after the installation of the adjusting block 5 is completed, the position of the stud and the sleeve can be adjusted from the back of the male die 1 to achieve the adjustment of the height of the adjusting block 5.

[0047] In one embodiment, as shown in the accompanying drawings, Figure 3 A medium injection hole 23 is formed in the female die 2, the medium injection hole 23 is in communication with the inner cavity, and the medium injection hole 23 is used to inject the filling medium into the inner cavity from the outside. The filling medium is used to eliminate the gap between the part and the female die 2 caused by uneven thickness and deformation of the part. The filling medium requires to be a fluid before injection, has a certain fluidity, solidifies after injection, has a certain supporting property, and will not be crushed and broken during the processing of the part. A low-melting-point metal or a low-melting-point alloy can be selected. After the processing of the part, the filling medium can be recovered by heating the tooling to be reused. The medium injection hole 23 is arranged in an array, and the number can be adjusted according to the size of the tooling. The female die 2 is provided with a tool setting block at the upper end for tool setting before processing.

[0048] Further, the clamping tool also includes a plug 4. A medium outlet hole 21 is formed in the female die 2, the medium outlet hole 21 is in communication with the inner cavity, and the plug 4 is inserted and matched with the medium outlet hole 21. As in the above embodiment, the medium outlet hole 21 is formed in the fitting surface of the female die 2 and the male die 1 in four directions of front, back, left and right, and is provided with a plug. When the filling medium is injected from the medium injection hole 23, if it flows out from the medium outlet hole 21, the plug 4 is used to plug it, which is used to assist in judging the filling condition of the filling medium between the female die 2 and the part.​

[0049] In one embodiment, as shown in the appendix Figure 5 As shown, the clamping fixture also includes a thin film 7, which is placed between the mating surfaces of the target part and the female mold 2 to separate the female mold 2 from the filling medium. The thin film 7 covers the side of the part facing the female mold 2, separating the female mold 2 and the blank part from the filling medium to facilitate demolding in subsequent stages. The film thickness is generally 10μm, and should not exceed 20μm, and a film with a temperature resistance higher than 120℃ should be selected.

[0050] In one embodiment, as shown in the appendix Figure 3 Appendix Figure 5 As shown, a second threaded hole 22 is provided on the mating surface of the female mold. The second threaded hole 22 is used for threaded connection with the screw 10, and the end of the screw 10 contacts the second surface of the target part. After the blank is clamped, the female mold 2 also serves as a tool for blank milling. The shape of the mating surface between the female mold 2 and the blank is consistent with the shape of the theoretical digital model of the part. A second threaded hole 22 is provided around the mating surface between the female mold 2 and the blank. The second threaded hole 22 can be a stepped hole. The upper end of the hole is a clearance hole, which is used to avoid the drill bit when drilling the blank clamping hole after clamping. The lower end of the hole is a threaded hole, which is used to cooperate with the screw 10 to clamp the blank before milling the profile. A shim 11 can be added during clamping to avoid damage to the part.

[0051] In one embodiment, the end of the adjusting block 5 can be configured as shown in the attached figure. Figure 2 The adjusting block 5 is spherical in shape. It supports the part and can also be a cuboid with a threaded hole in the center, connected to a screw for height adjustment. The adjusting block 5 is typically 10mm x 10mm. If the blank has a large curvature or complex structure, the size of the adjusting block 5 can be appropriately reduced. If necessary, the shape of the end of the adjusting block 5 can be changed to a spherical shape, such as a sphere or hemisphere, to reduce the contact area between the adjusting block 5 and the blank. The height of the adjusting block 5 is generally set to 5mm, with its axis in the vertical direction. The number and arrangement of the adjusting blocks 5 are determined by the shape and size of the blank, usually four. If the blank size exceeds 300mm x 300mm, the number of adjusting blocks 5 is increased as needed, but all four adjusting blocks 5 are still adjusted when calculating and adjusting their height. Furthermore, if there are special structures, such as large holes or cavities, adjusting blocks 5 are arranged in necessary positions as needed.

[0052] Based on the same inventive concept as in the foregoing embodiments, as shown in the appendix Figure 6 - Appendix Figure 8 As shown, embodiments of this application also provide a method for processing thin-walled curved surface parts, using the clamping fixture for thin-walled curved surface parts provided in embodiments of this application, including the following steps:

[0053] S10: judging according to the envelope condition of the reconstructed three-dimensional model of the part blank and the three-dimensional model of the target part, in the case that the target part can be machined, installing the adjusting block of the clamping tool for the thin-walled curved surface part provided by the embodiment of the application on the male die, and adjusting the height of the adjusting block.

[0054] S20: after the first surface of the part blank is attached to the attaching surface of the male die, the female die is buckled with the male die, so that the second surface of the part blank is attached to the attaching surface of the female die.

[0055] S30: filling medium is injected into the inner cavity between the attaching surfaces of the male die and the female die, after the filling medium is solidified, the female die and the part blank are separated from the male die and are placed upside down.

[0056] S40: the part blank is fixed on the female die and the machining of the positioning surface of the first surface of the part blank is performed.

[0057] S50: the part blank is separated from the female die, and other structural features of the part blank are machined based on the positioning surface.

[0058] In the embodiment, the male die 1 refers to the tooling element attached to the reference surface of the blank to be machined. The male die 1 is only used in the process of clamping the blank, the shape of the attaching surface of the male die 1 is consistent with the shape of the reference surface of the theoretical model of the part, but has an inward shrinkage δ1 in the normal direction of the surface. δ1 = T + h + Δ1, T is the theoretical maximum thickness of the blank, h is the thickness of the adjusting block 5, Δ1 is the gap between the attaching surface of the adjusting block 5 and the male die 1, and is generally 5-10 mm. A certain number of adjusting blocks 5 are arranged on the attaching surface of the male die 1, and the back surface of the male die 1 is simplified according to the current situation of the blank, and the thickness of the male die 1 is generally controlled to be greater than 20 mm.

[0059] The female die 2 refers to the tooling element buckled on the blank during clamping of the blank, and attached to the other surface of the reference surface of the blank to be machined. The female die 2 and the male die 1 are buckled to wrap the blank part. The female die 2 also serves as the tooling for milling the blank after the clamping of the blank is completed. The shape of the attaching surface of the female die 2 is consistent with the shape of the theoretical model of the part, but has an inward shrinkage δ2 in the normal direction of the surface, and δ2 is generally set to 5-10 mm. After the male die 1 and the female die 2 are buckled, the female die 2 is fixed on the machine tool table through the cooperation of the tooling clamping screw 8 and the tooling clamping screw gasket 9, and the female die 2 and the male die 1 are positioned and connected through the female die male die pin 3.

[0060] In the embodiment as shown in the accompanying drawings, the application is further described as follows: Figure 8

[0061] ​Firstly, the blank state of the thin-walled curved surface part is analyzed: the blank surface data is measured by three-coordinate measurement or blue light scanning and other measurement methods. The three-dimensional model of the blank is reconstructed through the measurement results, and compared with the three-dimensional model of the part to be processed to determine whether the blank can be processed into the part. If the deformation δP and the thickness error δT of the blank have caused the blank to be unable to envelope the geometry of the part, it is determined that the blank cannot be processed into the part. If the part can be enveloped by the blank, the part can be processed.

[0062] Determination of key parameters of stress-free tooling: The key parameters of stress-free tooling include the male die shrinkage δ1, the thickness of the adjusting block, the number of adjusting blocks, and the female die shrinkage δ2. Other design parameters of the clamping tooling and the design of other tooling are based on actual needs and general tooling design criteria.

[0063] Tooling processing: After completing the tooling design, the stress-free tooling and other tooling are processed by mechanical processing.

[0064] Blank pose adjustment: In the three-dimensional software, the real blank reconstruction model and the theoretical part model are placed in the appropriate position, so that the real blank reconstruction model can completely envelope the theoretical part model, and the residual amount of each part is as uniform as possible. The point position of the adjusting block corresponding to the real blank reconstruction model is the basis for adjusting the adjusting block, and the blank measurement point is determined according to the height of the adjusting block corresponding to the real blank reconstruction model, and the measurement program is compiled. Install the adjusting block on the male die, and adjust the height by rotating the screw, and cooperate with the dial indicator, so that the initial distance from the upper surface of each adjusting block to the male die bonding surface is δ1-Δ1, and the error is controlled within ±0.005. Place the blank on the adjusting block, and use the online measurement probe to measure by using the compiled measurement program, to determine the error of each adjusting block point position, and adjust the height by rotating the adjusting block screw according to the error size, and then measure again to ensure that the error measured by each adjusting block point position is not greater than ±0.05. As shown in FIG. 2, wherein the dashed line represents the part theoretical model position, the solid line represents the real blank reconstruction model position, the adjusting block actual position 52 is the adjusting block represented by the dashed line, the adjusting block theoretical position 51 is the adjusting block represented by the solid line, and the adjusting block height error 53 is the height difference at the same position of the two, as shown in FIG. 3, wherein the top point position of the adjusting block is taken. Figure 7 Figure 7

[0065] Modulation of filling medium: The filling medium is adjusted according to the actual needs of part processing, and the filling medium is usually a low-melting-point metal or a low-melting-point alloy.

[0066] Film lamination and filling medium: that is, after the first surface of the part blank is bonded to the bonding surface of the male die, the female die is buckled with the male die, so that the second surface of the part blank is bonded to the bonding surface of the female die, and the method further comprises: ​​

[0067] Covering the second face of the part blank with a film.

[0068] Covering the face of the blank part towards the cavity mold with a film 7, and then placing it on the adjusting block 5 of the punch mold 1, and then buckling the cavity mold 2 on the punch mold 1, and using the tool clamping screw 8 to fix and clamp the punch mold 1 and the cavity mold 2. The prepared filling medium is injected into the gap between the cavity mold 2 and the blank through the medium injection hole 23 of the cavity mold 2.

[0069] Curing and demolding: the filled tooling is left to stand for a period of time, and generally the filling medium is a low-melting-point metal or a low-melting-point alloy, and it can be left to stand for 3-5 hours. After the filling medium is cured, the tool clamping screw 8 is removed, and the cavity mold 2 and the blank are separated from the punch mold 1 and are placed upside down.

[0070] Blank pressing hole processing: the blank is clamped on the cavity mold 2 using a pressing plate, and a special drill bit matched with the material processing characteristics is used to process the pressing hole.

[0071] Blank positioning surface processing: the blank clamping screw 10 is screwed into the second threaded hole 22 on the cavity mold 2 through the blank pressing hole, so as to realize the fixed clamping of the blank. The pressing plate is removed, a special milling cutter matched with the material processing characteristics is used, and a prepared positioning surface processing numerical control program is called to process the positioning surface.

[0072] Part other structural feature processing: after the positioning surface processing is completed, the blank is disassembled from the cavity mold 2, and other toolings are used to process other structural features of the part based on the positioning surface.

[0073] Taking the SiCf / SiC composite material part with a theoretical size of 200mmx200mmx4mm as an example, the embodiments of the present application are further described:

[0074] Firstly, the blank is scanned by a blue light scanning technology, and a three-dimensional numerical model of the blank is reconstructed. The maximum thickness of the blank is 4.23mm, the minimum thickness is 3.87mm, and the deformation of the blank is 0.24mm. By comparing the reconstructed numerical model of the blank and the theoretical numerical model of the part, it is determined that the blank can envelope the geometric shape of the part, and the part can be processed.

[0075] The key parameters of the stress-free tooling are determined, wherein the male die inner shrinkage is 14.23 mm, the adjusting block thickness is 5 mm, the adjusting block number is 4, and the female die inner shrinkage is 5 mm. The other design parameters of the stress-free tooling and the design of other toolings are based on the actual requirements and general tooling design criteria. After completing the tooling design, the stress-free tooling and other toolings are processed by machining. The real blank reconstruction model and the theoretical model of the part are placed in a reasonable position in the three-dimensional software, so that the real blank reconstruction model can completely envelop the theoretical model of the part, and the residual amount of each part is as uniform as possible. The blank measurement points are determined according to the adjusting block height corresponding to the real blank reconstruction model, and the measurement program is compiled.

[0076] The adjusting block is installed on the male die, and the height is adjusted by rotating the bolt. The initial distance from the upper surface of each adjusting block to the male die bonding surface is 7.5 mm, and the error is controlled within ±0.005. The blank is placed on the adjusting block, and the prepared measurement program is used to measure the height error of the four adjusting block points, which are +0.172, -0.201, -0.148, and -0.339, respectively. According to the error size, the adjusting block bolt is rotated for height adjustment. After adjustment, the measurement is performed again to ensure that the error measured by each adjusting block point is not greater than ±0.05.

[0077] Tin-bismuth alloy is selected as the filling medium. The blank is protected by covering the front and back surfaces with a film, and then placed on the adjusting block of the male die. The female die is then buckled onto the male die, and the tool clamping screw is used to fix and clamp the male die and the female die. The prepared filling medium is injected into the gap between the female die and the blank through the medium injection port of the female die. The filled tooling is left for 5 hours. After the filling medium solidifies, the tool clamping screw is removed, and the female die and the blank are separated from the male die and placed upside down.

[0078] The blank is clamped on the female die using a pressing plate, and a special drill bit with matching material processing characteristics is used to process a pressing hole. The blank clamping screw is inserted through the blank pressing hole and screwed into the threaded hole on the female die to achieve fixed clamping of the blank. The pressing plate is removed, a special milling cutter with matching material processing characteristics is used, and a prepared positioning surface machining numerical control program is called to process the positioning surface. After the positioning surface is processed, the blank is disassembled from the female die, and the positioning surface is used as a reference to process other structural features of the part using other toolings. The final machined part surface machining precision meets the surface precision requirement of ±0.075 mm.

[0079] It should be noted that, in this text, the terms "comprising", "containing" or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article or system that includes a series of elements not only includes those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such a process, method, article or system. Without more limitations, the element defined by the statement "includes a" does not exclude the presence of other identical elements in the process, method, article or system that includes the element.

[0080] The above-mentioned sequence numbers of the embodiments of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0081] The above is only the preferred embodiment of the present application, and does not limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A fixture for clamping a thin-walled curved part, characterized by, The clamping tool comprises a male mold, a female mold and an adjusting block, wherein: the shape of the fitting surface of the male mold matches that of the fitting surface of the female mold, so that when the male mold and the female mold are buckled, the target part is wrapped in the inner cavity between the fitting surfaces of the male mold and the female mold, the fitting surface of the male mold is fitted with the first surface of the target part, the fitting surface of the female mold is fitted with the second surface of the target part, and the first surface of the target part is the reference surface to be machined; the adjusting block is arranged on the fitting surface of the male mold, and the height of the adjusting block is adjustable, so that when the target part is wrapped between the fitting surfaces of the male mold and the female mold, the end of the adjusting block is in contact with the first surface of the target part; a medium injection hole is arranged on the fitting surface of the female mold, the medium injection hole is in communication with the inner cavity, and the medium injection hole is used for injecting the filling medium into the inner cavity from the outside; a second threaded hole is arranged on the fitting surface of the female mold, the second threaded hole is used for threaded connection with a screw, and the end of the screw is in contact with the second surface of the target part; the filling medium is a low-melting-point metal or a low-melting-point alloy, and is in a fluid state before injection, has fluidity, and is solidified after injection, has supporting property. A first threaded hole is arranged on the fitting surface of the male mold, and the adjusting block is threaded connected with the male mold through the first threaded hole.

2. The clamping tool for thin-walled curved parts according to claim 1, wherein The adjusting block comprises a sleeve and a stud, the sleeve is threaded connected with the male mold through the first threaded hole, the first threaded hole is a through hole, and the stud is arranged in the sleeve and is threaded connected with the sleeve.

3. The fixture for clamping thin-walled curved parts according to claim 2, wherein The clamping tool further comprises a latch, a medium outflow hole is arranged on the female mold, the medium outflow hole is in communication with the inner cavity, and the latch is inserted into the medium outflow hole.

4. The fixture for clamping thin-walled curved parts according to claim 1, wherein The clamping tool further comprises a film, the film is arranged between the target part and the fitting surface of the female mold, so that the female mold is separated from the filling medium.

5. The fixture for clamping thin-walled curved parts according to claim 1, wherein The end of the adjusting block is in a ball head shape.

6. The fixture for clamping thin-walled curved parts according to claim 1, wherein The method comprises the following steps:

7. A method for machining a thin-walled curved part, wherein the thin-walled curved part is clamped by the clamping tooling for thin-walled curved parts according to any one of claims 1 to 6, characterized in that, judging the envelope condition of the reconstructed three-dimensional model of the part blank and the three-dimensional model of the target part, installing the adjusting block on the male mold when the target part can be machined, and adjusting the height of the adjusting block; after the first surface of the part blank is fitted with the fitting surface of the male mold, the female mold is buckled with the male mold, so that the second surface of the part blank is fitted with the fitting surface of the female mold; filling medium is injected into the inner cavity between the fitting surfaces of the male mold and the female mold, and after the filling medium is solidified, the female mold and the part blank are separated from the male mold and are placed upside down; the part blank is fixed on the female mold, and the first surface of the part blank is machined to form a positioning surface; the part blank is separated from the female mold, and other structural features of the part blank are machined based on the positioning surface. Before the first surface of the part blank is fitted with the fitting surface of the male mold, and the female mold is buckled with the male mold, so that the second surface of the part blank is fitted with the fitting surface of the female mold, the method further comprises:

8. The thin-walled curved part machining method according to claim 7, wherein the second surface of the part blank is covered with a film. ​

Images