CN113787306B - Flow control accurate thermal forming method for combustion chamber cap cover - Google Patents

Abstract

The invention discloses a flow control accurate thermoforming method for a combustion chamber cap, which combines multiple advantages of a vacuum technology, a thermoforming technology and a variable-pressure edge technology to form a part of the combustion chamber cap of an aero-engine in one step, dynamically regulates and controls an edge pressing force loading track in a thermal deformation process, realizes active control of material flow and internal stress, fundamentally solves the problems of oxidation and surface damage of the part and a mold in thermoforming, does not need heat treatment and shaping for the formed part, is a novel accurate forming method with low stress, less resilience and short flow, and is very suitable for accurate manufacturing of the cap part.

Description

Flow control accurate thermal forming method for combustion chamber cap cover

Technical Field

The invention belongs to the technical field of metal plate hot forming, and particularly relates to a flow control accurate hot forming method for an aero-engine combustion chamber cap.

Background

The cap is an important part on a flame tube of a combustion chamber of an aircraft engine, and the new-generation aircraft engines all adopt the integral cap with better structural rigidity. The thin wall of the integral hood of the flame tube is easy to deform, the structural stability is poor, the precision requirement is high, the molded surface is complex, and the used high-temperature alloy sheet has poor normal-temperature forming performance, large deformation resistance and serious unloading resilience, so that the technical process is complex. The current process route for manufacturing the integral cap cover is generally as follows: blanking → deep drawing forming → drilling/punching → annealing heat treatment → flanging → annealing heat treatment → shaping → cutting end face. In order to ensure the size precision of the diameters of the inner end and the outer end of the cap cover, the existing processing technology needs repeated annealing heat treatment and profile correction, and the manufacturing period is long. Because the high-temperature alloy sheet has high strength, large deformation resilience and strong anisotropy, the molded surface of the trimmed part is easy to distort, and the precision requirement can be barely met only by repeated heat treatment and shaping, so that the product has poor stability and low qualification rate. Meanwhile, the molded surface of the cap part often comprises local features, and the local feature size cannot be ensured by the cold forming process alone.

It can be seen that the existing cap part has large cold forming resilience, low precision, long flow, uneven wall thickness caused by lack of a material flow control method in hot forming and serious high-temperature oxidation problem.

Disclosure of Invention

In order to realize the accurate forming of the combustion chamber cap, the invention provides a flow control accurate hot forming method of the combustion chamber cap, which is characterized in that a vacuum technology, a hot forming technology and a variable blank holder force technology are combined, a blank holder force loading track is dynamically regulated and controlled in real time while a mould and a material are heated, the flow speed and the stress state of the material are actively controlled, and the integral cap with the geometric shape, the dimensional precision, the surface quality and the tissue performance meeting the use requirements of an aeroengine is obtained. The specific technical scheme of the invention is as follows:

a flow control precise hot forming method for a combustor cap comprises the following steps:

s1: the process design comprises the following steps: calculating the size of a blank, processing the blank and hot forming a die;

s2: flow-controlled thermoforming: combining vacuum, thermal forming and variable blank pressing, dynamically regulating and controlling a blank pressing force loading track in a thermal deformation process, and forming a combustion chamber cap part in one step;

s3: and (6) demolding.

Further, the step S2 includes:

s2-1: installing a hot forming die on hot forming equipment, and positioning and installing a blank;

s2-2: heating the blank and the hot forming die to a forming temperature, controlling the temperature error within a set range, and preserving heat;

s2-3: closing the blank holder, compacting the blank, starting feeding movement, drawing and forming, regulating and controlling the blank holder force according to a set blank holder force loading path, actively controlling material flow according to the requirement of a deformation stage, and controlling the temperature error in the hot forming period within a set range;

s2-4: and (5) finishing the forming of the combustion chamber cap cover part, and preserving heat and pressure.

Further, in step S2-1, the blank is placed in a vacuum environment together with a hot forming die for forming.

Further, in the step S2-2, the heating speed is 10-30 ℃/min, the forming temperature is 900 ℃, the heat preservation time is 10min, and the temperature error is within 5 ℃.

Further, in the step S2-3, the forming speed is 5mm/min, the forming temperature is 900 ℃, and the temperature error is within 5 ℃.

Further, in step S2-3, the blank holder force loading path is: the stroke is from 0 to 46 percent (D), the pressure is the initial blank holder force; stroke from 46% to 66% by weight, the pressure is raised to the first clamping force; the clamping force is increased to the second clamping force when the stroke is from 66% to 92%; the pressure is maintained at the second clamping force when the stroke is from 92% to 100% by weight; wherein D is the total feed stroke in the forming process.

Further, in the step S2-3, the initial blank holder force is (3000 ± 100) N; the first blank holder force is (5000 +/-150) N; the second blank holder force is (50000 +/-500) N.

Further, in the step S2-4, the dwell time is 10min.

Further, the specific process of step S3 is:

s3-1: cooling the combustion chamber cap part to normal temperature along with the furnace, and taking out;

s3-2: and finally obtaining the combustion chamber cap cover part by laser hole cutting and edge cutting.

A combustor cap part, the combustor cap part made by any one of the preceding.

The invention has the beneficial effects that:

1. the invention adopts hot forming to replace the traditional cold forming, can greatly reduce the forming resistance and the unloading resilience, improve the forming precision of parts, reduce the subsequent repeated shape correction procedures, shorten the process period, and the formed parts can meet the precision requirement without heat treatment and shaping.

2. The invention adopts the vacuum technology, and the forming is carried out in the vacuum environment, thus fundamentally solving the problems of oxidation and surface damage of parts and dies in the hot forming, prolonging the service life of the dies and reducing the cost of the dies.

3. The invention adopts the variable-pressure edge technology, dynamically adjusts the edge pressure loading path in the thermal deformation process, realizes the active control on the material flow and the internal stress, can effectively avoid the defects of wrinkling, cracking and the like, and improves the wall thickness uniformity of parts.

Drawings

In order to illustrate embodiments of the present invention or technical solutions in the prior art more clearly, the drawings which are needed in the embodiments will be briefly described below, so that the features and advantages of the present invention can be understood more clearly by referring to the drawings, which are schematic and should not be construed as limiting the present invention in any way, and for a person skilled in the art, other drawings can be obtained on the basis of these drawings without any inventive effort. Wherein:

FIG. 1 is a schematic diagram of the forming method of the present invention;

FIG. 2 is a diagram of the shape of the cap parts according to an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of a thermoforming mold of the present invention;

FIG. 4 is a process flow diagram of the present invention;

FIG. 5 is a temperature profile for a flow controlled thermoforming process of the present invention;

FIG. 6 is a schematic view of the blank holder force loading path of the present invention.

The reference numbers illustrate: 1-female die, 2-blank holder and 3-male die.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced otherwise than as specifically described herein and, therefore, the scope of the present invention is not limited by the specific embodiments disclosed below.

The invention provides a flow control accurate thermoforming method based on variable blank pressing and vacuum thermoforming. The method combines multiple advantages of a vacuum technology, a thermal forming technology and a variable-pressure edge technology, dynamically regulates and controls an edge pressing force loading track in a thermal deformation process, realizes active control on material flow and internal stress, fundamentally solves the problems of part and mould oxidation and surface damage in thermal forming in a vacuum environment, can meet the precision requirement of a formed part without heat treatment and shaping, is a novel precise forming technology with low stress, less resilience and short flow, and is very suitable for precise manufacturing of a cap part.

As shown in figure 1, the forming method of the invention combines the vacuum technology, the hot forming technology and the variable pressure edge technology, and the blank is subjected to the flow control hot forming process to form the required part shape in one step without subsequent heat treatment and shaping processes.

Concretely, the flow control accurate hot forming method for the combustor cap comprises the following steps:

s1: the process design comprises the following steps: calculating the size of a blank, and processing the blank and a hot forming die;

s1-1: according to the size of the cap part, the three-dimensional model is unfolded into two dimensions to obtain a two-dimensional annular blank size; determining the allowance of the blank size according to the size of the die, determining the geometric size of the cap blank, and performing line cutting on the high-temperature alloy plate to process the cap blank;

s1-2: and designing and processing a hot forming die according to the size of the combustion chamber cap cover part.

In step S1-1, the determined shape of the cap part blank is annular;

in step S1-2, the thermoforming mold is spring-back compensated and thermally compensated.

S2: flow-controlled thermoforming: combining vacuum, thermoforming and variable blank pressing, dynamically regulating and controlling a blank pressing force loading track in the thermal deformation process, and forming a combustion chamber cap part in one step;

s2-1: installing a hot forming die on hot forming equipment, positioning and installing a blank, and vacuumizing;

preferably, in step S2-1, the blank and the hot forming die are placed together in a vacuum environment for forming.

S2-2: heating the blank and the hot forming die to a forming temperature, controlling the temperature error within a set range, and preserving heat;

preferably, in step S2-2, the heating rate is 10-30 ℃/min, the forming temperature is 900 ℃, the heat preservation time is 10min, and the temperature error is within 5 ℃.

S2-3: closing the blank holder, compacting the blank, starting feeding movement, drawing and forming, regulating and controlling the blank holder force according to a set blank holder force loading path, actively controlling material flow according to the requirement of a deformation stage, and controlling the temperature error in the hot forming period within a set range;

preferably, in step S2-3, the forming speed is 5mm/min, the forming temperature is 900 ℃, and the temperature error is within 5 ℃.

In step S2-3, the blank holder force loading path is: the stroke is from 0 to 46 percent (D), the pressure is the initial blank holder force; the pressure is raised to the first clamping force when the stroke is from 46% D to 66% D; the blank holder force is increased to the second blank holder force when the stroke is from 66% to 92% by weight; the pressure is maintained at the second clamping force when the stroke is from 92% to 100%; wherein D is the total feed stroke in the forming process.

Preferably, in step S2-3, the initial blank holder force is (3000 ± 100) N; the first blank holder force is (5000 +/-150) N; the second clamping force was (50000. + -. 500) N.

S2-4: and after the forming of the combustion chamber cap cover part is finished, preserving heat and maintaining pressure.

Preferably, in step S2-4, the dwell time is 10min.

S3: and (6) demolding.

S3-1: cooling the combustion chamber cap part to normal temperature along with the furnace, and taking out;

s3-2: and finally, obtaining the combustion chamber cap part by laser hole cutting and edge cutting.

For the convenience of understanding the above technical aspects of the present invention, the following detailed description will be given of the above technical aspects of the present invention by way of specific examples.

Example 1

As shown in FIG. 2, the combustor cap component in this embodiment is made of GH3625 high temperature alloy, has a wall thickness of 1.6mm, is an annular thin-walled curved surface component, and has 12 groups of holes distributed in a circumferential array on the curved surface, and the axisymmetric interface of the component is formed by connecting multiple sections of curves, and has an outer diameter of 258.88mm and an inner diameter of 176.19mm.

As shown in fig. 3, the thermoforming mold in this embodiment includes a female mold 1, a blank holder 2, and a male mold 3, the female mold 1 is directly mounted on the thermoforming apparatus through screws, and the blank holder 2 and the male mold 3 are directly connected to the thermoforming apparatus.

As shown in FIG. 4, the adopted flow control precise hot forming method for the combustor cap part comprises the following steps:

s1: the process design comprises the following steps: calculating the size of a blank, processing the blank and hot forming a die;

s1-1: selecting proper allowance according to the size of the combustion chamber cap cover part, and determining the geometric size of the cap cover blank; unfolding according to the size of the part to obtain blank with the inner diameter of 171mm and the outer diameter of 271mm, and performing linear cutting on a GH3625 plate with the diameter of 1.6mm to process a blank of the cap part of the combustion chamber; selecting proper allowance according to forming equipment, and determining the geometric dimension of the cap blank to be an annular shape with an outer diameter of 306mm and an inner diameter of 120 mm;

s1-2: designing and processing a thermal forming die according to the size of the combustion chamber cap cover part, and performing springback compensation and thermal compensation; designing a thermal forming die according to the size of a combustion chamber cap part, wherein the clearance between a female die 1 and a male die 3 is 1.76mm, the die resilience compensation quantity at the inner diameter of the part is 0.10mm, the die resilience compensation quantity at the outer diameter of the combustion chamber cap part is 0.10mm, and the thermal compensation coefficient of the die is 0.99825;

s2: flow-controlled thermoforming: combining vacuum, thermal forming and variable blank pressing, dynamically regulating and controlling a blank pressing force loading track in a thermal deformation process, and forming a combustion chamber cap part in one step;

s2-1: mounting the hot forming die on hot forming equipment in a vacuum environment, positioning the blank, and vacuumizing;

s2-2: according to the temperature curve shown in FIG. 5, the blank and the hot forming die are heated to 900 ℃ together at the speed of 10 ℃/min in the OA stage, the temperature error is controlled within 5 ℃, and the temperature is kept for 10min in the AB stage to obtain uniform hot forming temperature;

s2-3: closing a blank holder, compacting the blank, starting feeding motion of a male die 3 at the speed of 5mm/min, performing deep drawing forming, and controlling temperature change according to the BC stage shown in figure 5 during hot forming, wherein the hot forming temperature is 900 ℃, and the temperature error is controlled within 5 ℃; meanwhile, the blank holder force is regulated according to the blank holder force loading path shown in figure 6, the material flow speed and direction are actively controlled, wherein, F ₁ Is 3000N, F ₂ Is 5000N, F ₃ Is 50000N, D ₁ 10.60mm, D ₂ Is 15.26mm, D ₃ 21.20mm, D ₄ Is 22.96mm;

s2-4: the part after molding was kept for 10min while maintaining the molding temperature at 900 ℃ in the CD stage shown in FIG. 5.

S3: and (6) demolding.

S3-1: cooling the part to normal temperature along with the furnace according to the DE stage shown in figure 5, and taking out;

s3-2: and cutting the cut hole and the inner and outer edges on the profile by laser to obtain the final cap part.

In conclusion, the invention can effectively form the combustion chamber cap meeting the dimensional precision and the use requirement by utilizing the combustion chamber cap flow control accurate hot forming method, realizes the active control of material flow and internal stress, fundamentally solves the problems of oxidation and surface damage of parts and hot forming dies in hot forming, does not need heat treatment and shaping for the formed parts, is a novel accurate forming technology with low stress, less resilience and short flow, and is very suitable for the accurate manufacture of cap parts.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (8)

1. A flow control precision thermoforming method for a combustor cap is characterized by comprising the following steps:

s1: the process design comprises the following steps: calculating the size of a blank, processing the blank and hot forming a die;

s2: flow-controlled thermoforming: combining vacuum, thermoforming and variable blank pressing, dynamically regulating and controlling a blank pressing force loading path in the thermoforming process, and forming a combustion chamber cap part in one step;

s3: demolding;

the step S2 includes:

s2-1: installing a hot forming die on hot forming equipment, and positioning and installing a blank;

s2-2: heating the blank and the hot forming die to a forming temperature, controlling the temperature error within a set range, and preserving heat;

s2-3: closing the blank holder, compacting the blank, starting feeding movement, drawing and forming, regulating and controlling the blank holder force according to a set blank holder force loading path, actively controlling material flow according to the requirement of a deformation stage, and controlling the temperature error in the hot forming period within a set range;

s2-4: after the forming of the combustion chamber cap cover part is finished, heat preservation and pressure maintaining are carried out;

in the step S2-3, the blank holder force loading path is: the stroke is from 0 to 46 percent (D), the pressure is the initial blank holder force; stroke from 46% to 66% by weight, the pressure is raised to the first clamping force; the clamping force is increased to the second clamping force when the stroke is from 66% to 92%; the pressure is maintained at the second clamping force when the stroke is from 92% to 100%; wherein D is the total feed stroke in the forming process.

2. The method of claim 1 wherein in step S2-1 the blank is formed in a vacuum environment with a hot forming tool.

3. The method for flow-controlled precise thermoforming of a combustor cap as claimed in claim 1, wherein in step S2-2, the heating speed is 10 to 30 ℃/min, the forming temperature is 900 ℃, the holding time is 10min, and the temperature error is within 5 ℃.

4. The combustion chamber cap flow control precision hot forming method as claimed in claim 1, wherein in the step S2-3, the forming speed is 5mm/min, the forming temperature is 900 ℃, and the temperature error is within 5 ℃.

5. The combustion bowl cap flow control precision thermoforming process of claim 1, characterized in that in said step S2-3, said initial blank holder force is (3000 ± 100) N, said first blank holder force is (5000 ± 150) N, and said second blank holder force is (50000 ± 500) N.

6. The method of claim 1, wherein the dwell time of step S2-4 is 10min.

7. The method for flow-controlled precise thermoforming of combustor cap as claimed in claim 1, wherein said step S3 is performed by the specific process of:

s3-1: cooling the combustion chamber cap part to normal temperature along with the furnace, and taking out;

s3-2: and finally, obtaining the combustion chamber cap part by laser hole cutting and edge cutting.

8. A combustor cap part characterized by being made according to any one of claims 1 to 7.

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