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

A precise thermoforming method for flow control of combustor cap

technical field

The invention belongs to the technical field of hot forming of metal plates, and in particular relates to a flow control precise hot forming method of a combustion chamber cap of an aero-engine.

Background technique

The cap is an important part on the flame tube of the aero-engine combustor. The new generation of aero-engines all adopt the integral cap with better structural rigidity. The overall cap of the flame tube is thin-walled and easy to deform, poor in structural stability, high in precision requirements, and complex in shape, and the high-temperature alloy sheet used has poor formability at room temperature, high deformation resistance, and severe springback after unloading, resulting in a complex process. At present, the process route for the manufacture of integral caps is generally: blanking→deep drawing→drilling/punching→annealing heat treatment→flanging→annealing heat treatment→shaping→end face cutting. In order to ensure the diameter and dimension accuracy of the inner and outer ends of the cap, the current processing technology requires repeated annealing and heat treatment, as well as surface correction, and the manufacturing cycle is long. Due to the high strength of the high-temperature alloy sheet, large deformation rebound, and strong anisotropy, the profile of the part is easily distorted after trimming, and repeated heat treatment and shaping are required to barely meet the precision requirements, resulting in poor product stability and low pass rate. At the same time, the profile of cap parts often contains local features, and the cold forming process alone cannot guarantee the size of local features.

It can be seen that the current cold forming of cap parts has large springback, low precision, and long process. The lack of material flow control methods in hot forming leads to uneven wall thickness, and the problem of high temperature oxidation is serious.

Contents of the invention

In order to realize the precise forming of the combustion chamber cap, the present invention provides a precise thermoforming method for the flow control of the combustion chamber cap, by combining vacuum technology, thermoforming technology and variable blank holder force technology, while heating the mold and materials Real-time and dynamic adjustment of the blank holder force loading track, active control of the flow velocity and stress state of the material, and an overall cap that meets the requirements of the aero-engine in terms of geometric shape, dimensional accuracy, surface quality and organizational performance. Concrete technical scheme of the present invention is as follows:

A precise thermoforming method for flow control of a combustor cap, comprising the following steps:

S1: Process design: calculate blank size, process blank and thermoforming mold;

S2: Flow Control Thermoforming: Combining vacuum, thermoforming and variable blank holder, dynamically adjust the blank holder force loading trajectory during the thermal deformation process, and form the combustion chamber cap part in one step;

S3: demoulding.

Further, the step S2 includes:

S2-1: Install the thermoforming mold on the thermoforming equipment, and position and install the blank;

S2-2: Heat the blank and the thermoforming mold to the forming temperature, control the temperature error within the set range, and keep warm;

S2-3: The blank holder ring is closed, the blank is pressed tightly, the feed movement is started, and deep drawing is formed. At the same time, the blank holder force is adjusted according to the set blank holder force loading path, and the material flow is actively controlled according to the requirements of the deformation stage. Thermoforming During the period, the temperature error is controlled within the set range;

S2-4: The forming of the combustion chamber cap parts is completed, heat preservation and pressure are maintained.

Further, in step S2-1, the blank and the thermoforming mold are placed together in a vacuum environment for forming.

Further, in the step S2-2, the heating rate is 10-30°C/min, the forming temperature is 900°C, the holding time is 10min, and the temperature error is within 5°C.

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

Further, in the step S2-3, the loading path of the blank-holding force is: when the stroke is from 0 to 46%D, the pressure is the initial blank-holding force; when the stroke is from 46%D to 66%D, the pressure rises to the first Blank-holding force; when the stroke is from 66% D to 92% D, the blank-holding force rises to the second blank-holding force; when the stroke is from 92% D to 100% D, the pressure remains at the second blank-holding force; among them, D is The total stroke of the feed during the forming process.

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

Further, in the step S2-4, the pressure holding time is 10 minutes.

Further, the specific process of the step S3 is:

S3-1: Cool the combustion chamber cap parts to normal temperature with the furnace, and take them out;

S3-2: Obtain the final combustion chamber cap parts by laser cutting holes and edge trimming.

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

The beneficial effects of the present invention are:

1. The present invention adopts hot forming instead of traditional cold forming, which can greatly reduce forming resistance and springback after unloading, improve the forming accuracy of parts, reduce subsequent repeated shape correction procedures, shorten the process cycle, and the formed parts do not need heat treatment and shaping Meet the precision requirements.

2. The present invention uses vacuum technology to form in a vacuum environment, which can fundamentally solve the problems of oxidation and surface damage of parts and molds in thermoforming, prolong the life of the mold, and reduce the cost of the mold.

3. The present invention adopts variable blank holder technology, dynamically adjusts the loading path of blank holder force during thermal deformation, realizes active control of material flow and internal stress, can effectively avoid defects such as wrinkling and cracking, and improves the uniform wall thickness of parts Spend.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the embodiments, and the features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings , the accompanying drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained according to these drawings without creative work. in:

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

Fig. 2 is the shape diagram of the cap parts of the embodiment of the present invention;

Fig. 3 is a schematic sectional view of a thermoforming die of the present invention;

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

Fig. 5 is the temperature change curve of the flow control thermoforming process of the present invention;

Fig. 6 is a schematic diagram of the loading path of the blank holder force in the present invention.

Description of the accompanying figures: 1-die, 2-binder ring, 3-punch.

detailed description

In order to understand the above-mentioned purpose, features and advantages of the present invention more clearly, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described here. Therefore, the protection scope of the present invention is not limited by the specific details disclosed below. EXAMPLE LIMITATIONS.

The invention proposes a flow control precision thermoforming method based on variable pressure edge and vacuum thermoforming. This method combines the multiple advantages of vacuum technology, thermoforming and variable blank holder technology, dynamically adjusts the loading trajectory of blank holder force during thermal deformation, and realizes the active control of material flow and internal stress. Oxidation and surface damage of parts and molds during forming. The formed parts can meet the precision requirements without heat treatment and shaping. It is a new precision forming technology with low stress, less springback and short process, which is very suitable for the precision of cap parts. manufacture.

As shown in Figure 1, the principle of the forming method of the present invention is to combine vacuum technology, thermoforming technology and variable blanking technology. The blank is formed into the desired part shape in one step through the flow control thermoforming process, without subsequent heat treatment and shaping processes.

Specifically, a precise thermoforming method for flow control of a combustor cap, comprising the following steps:

S1: Process design: calculate blank size, process blank and thermoforming mold;

S1-1: According to the size of the cap part, the three-dimensional model is expanded into two dimensions to obtain a two-dimensional ring blank size; according to the size of the mold, the margin of the blank size is determined, and the geometric size of the cap blank is determined. For superalloy plates Wire EDM to machine cap blanks;

S1-2: According to the size of the combustion chamber cap parts, design and process the thermoforming mold.

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

In step S1-2, the thermoforming mold undergoes springback compensation and thermal compensation.

S2: Flow Control Thermoforming: Combining vacuum, thermoforming and variable blank holder, dynamically adjust the blank holder force loading trajectory during the thermal deformation process, and form the combustion chamber cap part in one step;

S2-1: Install the thermoforming mold on the thermoforming equipment, position and install the blank, and vacuumize;

Preferably, in step S2-1, the blank and the thermoforming mold are placed together in a vacuum environment for forming.

S2-2: Heat the blank and the thermoforming mold to the forming temperature, control the temperature error within the set range, and keep warm;

Preferably, in step S2-2, the heating rate is 10-30°C/min, the forming temperature is 900°C, the holding time is 10min, and the temperature error is within 5°C.

S2-3: The blank holder ring is closed, the blank is pressed tightly, the feed movement is started, and deep drawing is formed. At the same time, the blank holder force is adjusted according to the set blank holder force loading path, and the material flow is actively controlled according to the requirements of the deformation stage. Thermoforming During the period, the temperature error is controlled within the set range;

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

In step S2-3, the loading path of blank holder force is: when the stroke is from 0 to 46% D, the pressure is the initial blank holder force; when the stroke is from 46% D to 66% D, the pressure rises to the first blank holder force; From 66%D to 92%D, the blank-holding force rises to the second blank-holding force; when the stroke is from 92%D to 100%D, the pressure remains at the second blank-holding force; where, D is the progress during the forming process Give the total itinerary.

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

S2-4: After the combustion chamber cap parts are formed, keep warm and pressurized.

Preferably, in step S2-4, the pressure holding time is 10 minutes.

S3: demoulding.

S3-1: Cool the combustion chamber cap parts to normal temperature with the furnace, and take them out;

S3-2: Obtain the final combustion chamber cap parts by laser cutting holes and edge trimming.

In order to facilitate the understanding of the above-mentioned technical solution of the present invention, the above-mentioned technical solution of the present invention will be described in detail below through specific examples.

Example 1

As shown in Figure 2, the material of the combustion chamber cap part in this embodiment is GH3625 superalloy, and the wall thickness is 1.6mm. The axisymmetric interface is formed by connecting multiple curves, with an outer diameter of 258.88mm and an inner diameter of 176.19mm.

As shown in Figure 3, the thermoforming mold in this embodiment includes a die 1, a blank holder 2 and a punch 3, the die 1 is directly installed on the thermoforming equipment through screws, and the blank holder 2 and the punch 3 Direct connection to thermoforming equipment.

As shown in Fig. 4, the flow control precise hot forming method of the combustor cap part includes the following steps:

S1: Process design: calculate blank size, process blank and thermoforming mold;

S1-1: Based on the size of the combustion chamber cap parts, select the appropriate margin to determine the geometric dimensions of the cap blank; according to the size of the part, the blank size is 171mm in inner diameter and 271mm in outer diameter, and the 1.6mm GH3625 plate is Wire cutting is used to process the blank of the combustion chamber cap; select the appropriate margin according to the forming equipment, and determine the geometric size of the cap blank as a ring with an outer diameter of 306mm and an inner diameter of 120mm;

S1-2: According to the size of the combustion chamber cover part, design and process the thermoforming mold for springback compensation and thermal compensation; design the thermoforming mold according to the part size of the combustion chamber cover part, and the gap between the die 1 and the punch 3 is 1.76 mm, the springback compensation amount of the mold at the inner diameter of the part is 0.10mm, the springback compensation amount of the mold at the outer diameter of the combustion chamber cap part is 0.10mm, and the thermal compensation coefficient of the mold is 0.99825;

S2: Flow Control Thermoforming: Combining vacuum, thermoforming and variable blank holder, dynamically adjust the blank holder force loading trajectory during the thermal deformation process, and form the combustion chamber cap part in one step;

S2-1: Install the thermoforming mold on the vacuum environment thermoforming equipment, position the blank, and vacuumize;

S2-2: According to the temperature curve shown in Figure 5, the blank and the thermoforming mold are heated to 900°C at a speed of 10°C/min in the OA stage, and the temperature error is controlled within 5°C. The AB stage is kept for 10 minutes to obtain uniform heat Forming temperature;

S2-3: The blank holder is closed, and the blank is pressed tightly. The punch 3 starts to feed at a speed of 5mm/min for deep drawing. 900°C, and the temperature error is controlled within 5°C; at the same time, the blankholder force is regulated according to the blankholder force loading path shown in Figure 6, and the material flow speed and direction are actively controlled. Among them, F ₁ is 3000N, F ₂ is 5000N, and F ₃ is 50000N, D ₁ is 10.60mm, D ₂ is 15.26mm, D ₃ is 21.20mm, D ₄ is 22.96mm;

S2-4: Hold the parts after forming for 10 minutes, during which the temperature change is shown in Figure 5 in the CD stage, and maintain the forming temperature at 900°C.

S3: demoulding.

S3-1: Cool the part to room temperature with the furnace according to the DE stage shown in Figure 5, and take it out;

S3-2: Use laser cutting to cut holes and inner and outer edges on the contour to get the final cap parts.

To sum up, the present invention can utilize the flow control precision thermoforming method of the combustion chamber cap to effectively form the combustion chamber cap that meets the dimensional accuracy and use requirements, realizes the active control of material flow and internal stress, and fundamentally solves the problem of thermoforming Oxidation and surface damage of medium parts and thermoforming molds. The formed parts do not need heat treatment and shaping. It is a new precision forming technology with low stress, less springback and short process, which is very suitable for the precise manufacture of cap parts.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within 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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