CN110434217B - Method for improving local anti-swelling height of complex thin-wall part in hydroforming - Google Patents

Abstract

The invention provides a method for improving the local anti-expansion height in liquid-filled forming of complex thin-walled parts, belonging to the field of aerospace manufacturing. The method includes the steps of designing and manufacturing a mold, designing and manufacturing a detachable edge blanking block, installing and debugging a mold tool, a process of liquid-filling a plate, and laser cutting of a process supplementary part. On the basis of the traditional passive liquid-filling forming method, this method changes the local blank holder into a detachable insert design, which is suitable for forming deep cavity thin-walled parts with different depth requirements, and solves the problem of forming such parts. The problem of local breakage that occurs when it occurs. In this way, in the initial stage of liquid filling, a higher anti-expansion height can be achieved locally, and a large amount of sheet material can be supplemented, which overcomes the shortcomings of excessive local deformation caused by excessive thinning or even rupture in the later stage of forming. This method can be appropriately changed according to the material used for the plate, the thickness of the plate and the structural characteristics of the parts, and has good applicability.

Description

A method for increasing the height of local anti-expansion in liquid-filled forming of complex thin-walled parts

technical field

The invention belongs to the field of aerospace manufacturing, and particularly relates to a liquid-filled forming method for complex thin-walled and deep-cavity shaped parts.

Background technique

With the rapid development of my country's aerospace industry, how to minimize the overall weight of the aircraft and seek a more reasonable space layout has become the top priority in the current aerospace manufacturing field. In this context, some complex thin-walled aerospace parts demand has greatly increased. However, the traditional method requires higher labor when forming complex thin-walled parts and some special-shaped curved parts, the yield is low, and the degree of mechanization is not enough. high.

Based on the above problems, the present invention makes some improvements to the blank holder on the basis of the traditional passive liquid-filling forming method, so as to solve the problem of local easy rupture when forming complex special-shaped curved surfaces and thin-walled and deep-cavity parts. Traditional passive liquid-filled forming refers to replacing the rigid die with the pressure of the liquid chamber, and forming the required parts under the liquid. Although the traditional liquid-filled forming solves the shortcoming that ordinary rigid mold forming is easy to scratch the surface of the part, it is easier to increase the local thinning rate for the area with excessive local deformation. In the present invention, by improving the blank holder device, the partial blank holder ring is changed into a detachable insert design, so as to be suitable for forming deep cavity thin-walled parts with different depth requirements. In this way, a higher anti-expansion height can be achieved locally in the initial stage of liquid filling, and then a large amount of sheet material can be replenished, which overcomes the shortcomings of excessive local deformation caused by excessive thinning or even rupture in the later stage of forming. This method can be appropriately changed according to the material used for the plate, the thickness of the plate and the structural characteristics of the parts, and has good applicability.

SUMMARY OF THE INVENTION

The method provided by the present invention for improving the height of local anti-swelling in the liquid-filled forming of complex thin-walled parts comprises the following steps in sequence:

(1) Install the forming die on the liquid-filled forming equipment for installation and debugging.

(2) Install the required specification of the blank holder in the specific position of the original blank holder according to the forming depth requirements.

(3) Place the sheet on the mold liquid chamber, and use the positioning device to locate it.

(4) After the preparation is completed, the blank holder goes down to press the sheet material, and the blank holder gap is guaranteed by a number of limit blocks evenly distributed on the mold. (5) Start the booster pump and start filling the liquid chamber with liquid until the liquid does not overflow from the edge of the liquid chamber.

(6) At the beginning of forming, the punch goes down to the surface of the sheet.

(7) Given a small initial anti-expansion pressure, partially anti-expand the sheet to the position of the removable edge blanking block.

(8) Increase the hydraulic pressure according to the predetermined loading curve, and at the same time, the punch starts to descend at a predetermined speed (stroke), and the sheet is deformed against the punch under the liquid package to form the desired shape.

(9) Release the pressure and open the mold, and take out the formed parts.

(10) Wipe the liquid remaining on the surface of the part, and cut off the excess flange and process supplementary surface to obtain the final part.

In the step 1, the mold is composed of a punch with a surface of the part, a liquid chamber, a blank holder, a matching removable blank holder, a sealing ring and a limit block.

The angle between the blank holder and the horizontal plane designed in the step 2 is preferably 10° to 15°. If the angle is too small, the height of the reverse expansion will be insufficient and the forming effect will be affected. burst directly.

The material used for the sheet material in the step 3 is 5A02 aluminum alloy, and the thickness is 1 mm.

The blank holder gap in the step 4 is 1.1 times the thickness of the sheet metal.

The method of the invention improves the blank holder on the basis of the traditional passive liquid-filling forming technology. By increasing the local anti-bulging height, it plays a role of feeding material in the later stage of forming, thereby greatly reducing the thinning rate of thin-walled parts.

The invention is a method with strong adaptability, and the method has great reference significance when forming thin-walled parts with a large local drawing ratio. For thin-walled parts of different shapes, after designing the corresponding mold, the bevel angle and size of the blank holder insert can be adjusted according to the shape and depth of the forming to meet the forming effect requirements of different parts.

Description of drawings

Fig. 1 is a schematic diagram of a part of a complex thin-walled deep cavity shaped part formed by the method for improving the local anti-expansion height in the liquid-filled forming of the complex thin-walled part provided by the present invention.

FIG. 2 is a cross-sectional view of a blank holder of a complex thin-walled deep cavity shaped part formed by the method for increasing the local anti-expansion height in the liquid-filled forming of the complex thin-walled part provided by the present invention.

3 is a top view of a blank holder of a complex thin-walled deep cavity shaped part formed by the method for increasing the local anti-bulging height in the liquid-filled forming of the complex thin-walled part provided by the present invention.

FIG. 4 is a schematic diagram of the mold tooling of the complex thin-walled deep cavity shaped part formed by the method for improving the local anti-expansion height in the liquid-filled forming of the complex thin-walled part provided by the present invention.

5 is a schematic diagram of the forming of a complex thin-walled deep cavity shaped part formed by the method for increasing the local anti-swelling height in the liquid-filled forming of the complex thin-walled part provided by the present invention.

In the figure: 1 is the part profile; 2 is the blank holder; 3 is the punch; 4 is the removable blank holder; 5 is the sealing ring; 6 is the limit block; 7 is the liquid chamber inlet hole; 8 is the plate 9 is the liquid chamber; FP is the downward force of the punch; FB is the blank holder force.

Detailed ways

The complex thin-walled shaped parts formed by the complex thin-walled deep-cavity shaped parts formed by the method for improving the local anti-swelling height in the liquid-filled forming of the complex thin-walled parts provided by the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in Fig. 1-Fig. 5, the complex thin-walled special-shaped part formed by the method for improving the local anti-expansion height in the liquid-filled forming of the complex thin-walled part provided by the present invention comprises the following steps:

(1) Design the corresponding mold according to the part profile diagram in Figure 1.

(2) After installing the mold, install the corresponding blank holder insert 4 on the specific position of the blank holder ring 2 .

(3) Place the sheet material 8 on the liquid chamber 9, and use the positioning device to locate it.

(4) The blank holder goes down, and the blank holder gap is guaranteed by the limit block 6.

(5) Start the booster pump, and fill the liquid chamber with liquid through the liquid chamber inlet hole 7 until the liquid does not overflow from the edge of the liquid chamber.

(6) At the beginning of forming, the punch 3 goes down to the top of the sheet material 8, and a small initial anti-expansion pressure is given in the liquid chamber 9 by the booster pump, and the sheet material 8 is anti-expanded until it is close to the edge pressing. Location of block 4.

(7) The pressure of the liquid chamber is increased according to the predetermined hydraulic loading curve, and at the same time, the punch 3 starts to descend at a predetermined speed (stroke), and the sheet 8 is deformed against the punch under the wrapping of the liquid to form the desired shape.

(8) Release the pressure to open the mold and take out the parts.

(9) After cleaning the surface of the part in step 8, use a wire cutting machine to remove the process supplementary surface to obtain the final part.

In the step 1, the mold is composed of a punch 3 with a part surface, a liquid chamber 9, a blank holder 2, a matching removable blank holder insert 4, a sealing ring 5 and a limit block 6.

The angle between the edge holder insert 4 designed in the step 2 and the horizontal plane is preferably 10° to 15°. If it is too small, it will cause a shortage of the height of the reverse expansion and affect the forming effect. If it is too large, the plate will be in the reverse direction. In the early stage of expansion, it bursts directly.

The material used for the sheet 8 in the step 3 is 5A02 aluminum alloy, and the thickness is 1 mm.

The blank holder gap in the step 4 is 1.1 times the thickness of the sheet metal.

The method of the invention improves the blank holder on the basis of the traditional passive liquid-filling forming technology. By increasing the local anti-bulging height, it plays the role of feeding material in the later stage of forming, thereby greatly reducing the thinning of complex thin-walled and deep-cavity shaped parts. Rate.

The process of the invention has strong adaptability, and the method has great reference significance when forming thin-walled parts with a large local drawing ratio. For thin-walled parts of different shapes, after designing the corresponding mold, the bevel angle and size of the blank holder insert can be adjusted according to the shape and depth of the forming to meet the forming effect requirements of different parts.

The above descriptions are only specific embodiments of the present invention so that those skilled in the art can understand the present invention, but the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, equivalent changes, adjustments and modifications made without departing from the spirit and essence of the present invention shall fall within the protection scope of the present invention.

Claims (2)

1. A method for improving the local back expansion height of a complex thin-wall part in hydro-forming is characterized in that: the forming method of the complex thin-walled part comprises the following steps in sequence:

(1) mounting a forming die on a liquid-filling forming device for mounting and debugging;

(2) installing the blank holder insert with the required specification at a specific position of an original blank holder according to the forming depth requirement;

(3) placing the plate on a liquid chamber of the die, and positioning the plate by using a positioning device;

(4) after the preparation is finished, the blank holder descends to press the plate, and the blank holder gap is ensured by a plurality of limiting blocks uniformly distributed on the die;

(5) starting a booster pump, and starting to fill liquid into the liquid chamber until the liquid does not overflow from the edge of the liquid chamber;

(6) in the beginning stage of forming, the male die descends to the surface of the plate;

(7) giving a smaller initial reverse expansion pressure, and locally reversely expanding the plate to the position of the detachable edge pressing insert;

(8) increasing hydraulic pressure according to a set loading curve, enabling the male die to move downwards at a set speed and according to a set stroke, enabling the plate to be tightly attached to the male die under the liquid wrapping to deform until the required shape is formed;

(9) releasing pressure and opening the die, and taking out the formed part;

(10) wiping the liquid remained on the surface of the part, and cutting off redundant flanges and process supplement surfaces to obtain a final part;

the angle between the edge pressing insert and the horizontal plane is 10-15 degrees;

the material used by the plate is 5A02 aluminum alloy, and the thickness is 1 mm;

the blank pressing gap is 1.1 times of the thickness of the plate.

2. A method of increasing the localized backswelling height of a complex thin-walled part as set forth in claim 1, wherein: the die consists of a male die with a part surface, a liquid chamber, a blank holder, a detachable blank holder insert, a sealing ring and a limiting block which are matched.

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