CN116140450A - Superplastic air-expanding forming die capable of feeding and method - Google Patents

Abstract

The present invention is applicable to the field of mould-related technologies, and provides a feedable superplastic inflatable forming die and method, wherein the feedable superplastic inflatable forming die includes: an upper die and a lower die, and the lower die There is a mold cavity inside; the upper mold includes an inner ring and an outer ring, the inner ring is a feedable preforming mold with a sealing ring, and the outer ring is an inflatable forming mold with a sealing stem. The present invention does not require additional rigidity The mold uses gas to realize preforming under the premise of almost no thinning of the sheet metal, which saves the cost of mold manufacturing, avoids the local excessive thinning of direct superplastic inflation forming parts, and ensures the forming accuracy and surface quality requirements of the parts , improving the thickness uniformity of the part.

Description

A kind of feedable superplastic inflation forming mold and method

technical field

The invention relates to the technical field of moulds, in particular to a feedable superplastic inflation forming mold and method.

Background technique

Superplastic inflation forming parts are generally complex in shape or large in size, and the thickness of the formed parts is uneven, especially some box-shaped parts are prone to excessive thinning or even cracking defects. It will reduce the yield rate and increase the cost, and it is widely used in aerospace, rail transportation, weaponry and other fields.

At present, there are mainly the following methods to solve the problem of excessive thinning of superplastic inflation forming parts:

1. In terms of the original plate: by increasing the thickness of the original plate or designing an uneven plate thickness to compensate for the loss of thickness in the excessively thinned area;

2. In terms of technology: use pre-anti-inflating deformation to improve the initial material thickness distribution in final forming, or mechanical pre-forming to increase the volume of sheet metal participating in the superplastic inflating forming process.

There are certain deficiencies in the existing solutions: increasing the thickness of the original plate will increase the quality of the parts, which is contrary to the lightweight design requirements; the technical requirements for the production of unequal thickness billets are high, which will greatly increase the production cost; The way of bulging deformation will reduce the production efficiency of parts. Mechanical preforming may cause the sheet to break when it contacts the preforming mold, and the shape of the sheet after mechanical preforming is difficult to control, which increases the cost of mold manufacturing and also increases Risk of sheet cracking and wrinkling. Therefore, in view of the above status quo, it is urgent to provide a feedable superplastic inflation forming mold and method to overcome the shortcomings in current practical applications.

Contents of the invention

The purpose of the present invention is to provide a feedable superplastic inflation forming mold and method, aiming to solve the problems in the above-mentioned technical background.

The present invention is achieved in this way, a kind of feedable superplastic inflation molding die, this mold is installed on the double-action press, the described superplastic inflation molding mold that can feed includes:

an upper mold and a lower mold, the lower mold has a cavity;

The upper die includes an inner ring and an outer ring, the inner ring is a feedable preforming die with a sealing ring, and the outer ring is an inflatable forming die with a sealing stem.

As a further solution of the present invention: the preforming mold and the lower mold are respectively provided with an air inlet and an air outlet, the air inlet is provided with an air inlet, and the air outlet is provided with an exhaust pipe; the air inlet And the diameter of air outlet is 2-4mm.

As a further solution of the present invention: the inflatable forming mold is provided with an auxiliary groove for the air intake pipe for connecting the air intake pipe with the air intake device.

As a further solution of the present invention: the preforming mold is provided with a ring of grooves for placing the sealing ring.

As a further solution of the present invention: the sealing stem is located at 10-20 mm from the periphery of the part contour.

As a further solution of the present invention: multiple groups of weight-reducing grooves are provided on the lower die.

A method of feedable superplastic inflation forming, applied to the feedable superplastic inflation forming die described above, the method may further comprise the steps:

Step 1: Install the upper mold and the lower mold on the double-action press, the preforming mold and the inflation forming mold of the upper mold are respectively installed on the inner slider and the outer slider of the press, and the air inlet pipe is welded on the preforming mold ;

Step 2: Air pressure preforming. When the mold temperature reaches the superplastic forming temperature and the temperature is uniform, place the sheet between the lower mold and the preforming mold. After keeping warm for 5-10 minutes, open the intake valve and seal the ring to prevent gas leakage. , the sheet material is fed into the cavity of the lower mold under the action of gas;

Step 3: Superplastic inflatable forming. After the sheet material flows to form the basic shape of the part, the inflatable forming die moves down to crush the surrounding sheet material, increase the air pressure, and complete the superplastic inflatable forming by stretching the sheet material.

As a further scheme of the present invention: in step 2, before blanking, all spray graphite lubricant on both sides of the sheet;

The gas pressure for preforming is 0.1-1MPa;

The upper mold and the lower mold are installed on the heating platform, and the temperature of the heating platform is controlled by 8-16 groups of temperature control units, and the temperature is transferred to the upper mold and the lower mold through heat conduction. After reaching the predetermined temperature, keep it warm for 20-30min to ensure The mold temperature is uniform.

As a further solution of the present invention: in step 3, when the inflation forming mold goes down, use the sealing stem to fix the surrounding of the sheet material;

When the air pressure is increased, small and complex local shapes are formed. When the exhaust pipe is basically free of gas, the pressure is kept for 3-5 minutes, and the forming is completed.

Compared with prior art, the beneficial effect of the present invention:

The feedable superplastic inflatable forming mold does not require additional rigid molds, and uses gas to realize preforming under the premise of almost no thinning of the sheet metal, which saves the cost of mold manufacturing and avoids direct superplastic inflating The local excessive thinning of the formed parts ensures the forming accuracy and surface quality requirements of the parts, and improves the thickness uniformity of the parts;

Compared with the reverse inflation preforming technology, this method can save the cost of mold manufacturing, shorten the production time of products, and can form products with more complex shapes or deeper depths, and the forming yield is high;

Compared with mechanical preforming, this method can save mold manufacturing costs and reduce the risk of cracking and wrinkling;

Since this method is carried out under relatively low air pressure, the sealing effect of the rubber sealing ring on the gas is remarkable, and the sheet can be pushed into the cavity without substantially reducing the thickness, so as to provide sufficient sheet volume for inflatable forming , greatly improve the average thickness of the molded product, improve the excessive thinning of the parts, and improve the physical properties of the parts;

In this method, after preforming by pressure feeding, superplastic inflation forming is carried out. The main shape of the part is formed by the sheet metal flow, and the complex shape that is difficult to form is formed by thinning the sheet metal, which greatly improves the freedom of product design;

The present invention has a degree of freedom of forming that is incomparable to the existing metal forming process, product design can be more diversified in terms of shape complexity and size, and the application field is also wider.

Description of drawings

Fig. 1 is a schematic diagram of the state of putting the blank into the mold according to the embodiment of the present invention.

FIG. 2 is a partially enlarged view of part A in FIG. 1 .

Fig. 3 is a schematic diagram of the state at the end of the feed preforming of the embodiment of the present invention.

FIG. 4 is a partially enlarged view of part B in FIG. 1 .

Fig. 5 is a schematic diagram of the state at the end of the superplastic inflation forming of the embodiment of the present invention.

FIG. 6 is a partially enlarged view of part C in FIG. 1 .

Fig. 7 is a cloud diagram of the thickness distribution of the direct superplastic inflation forming simulation sheet according to the embodiment of the present invention.

Fig. 8 is a cross-sectional view of the sheet at D-D in Fig. 7 along the diagonal.

Fig. 9 is a cloud diagram of the thickness distribution of the simulated sheet material for preforming with feed air pressure according to the embodiment of the present invention.

Fig. 10 is a cross-sectional view of the sheet at E-E in Fig. 9 along the diagonal.

Fig. 11 is a cloud diagram of the thickness distribution of the simulated sheet material for preforming with feed air pressure according to the embodiment of the present invention.

Fig. 12 is a cross-sectional view of the sheet at F-F in Fig. 11 along the diagonal.

Fig. 13 is a comparison diagram of sheet material lines between direct superplastic inflation forming and the forming method of the present invention.

In the accompanying drawings: 1-preforming mold, 2-inflatable forming mold, 3-sheet material, 4-lower mold, 5-weight reduction groove, 6-exhaust pipe, 7-sealing ring, 8-sealing stem, 9 - Intake duct, 10 - Intake duct auxiliary groove.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention. The specific implementation of the present invention will be described in detail below in conjunction with specific embodiments.

Please refer to Fig. 1-Fig. 6, a kind of feedable superplastic inflatable forming mold provided by the embodiment of the present invention, the mold is installed on a double-acting press, and the described feedable superplastic inflatable forming mold includes:

An upper mold and a lower mold 4, the lower mold 4 has a cavity;

The upper die includes an inner ring and an outer ring, the inner ring is a feedable preforming die 1 with a sealing ring 7 , and the outer ring is an inflatable forming die 2 with a sealing stem 8 .

In the embodiment of the present invention, the sealing ring 7 is made of high-temperature-resistant rubber. With the assistance of the high-temperature-resistant rubber sealing ring 7, the gas is used to drive the sheet material 3 to move to realize air pressure preforming; , the sealing stem 8 restricts the flow of the sheet material 3, and the complex and small shapes are formed by inflation. The double-action structure of the upper mold (ie, the preforming mold 1 and the inflation forming mold 2) can not only form complex parts with high shape precision, but also It can also effectively improve the uniformity of the wall thickness of the parts, reduce the superplasticity requirements of the superplastic inflation forming on the original plate, and has a broad application space; compared with the existing technology, the superplastic inflation forming mold that can be fed , no need to make additional rigid molds, and use gas to realize preforming under the premise of almost no thinning of the sheet metal, which saves the cost of mold manufacturing, avoids the local excessive thinning of direct superplastic inflatable forming parts, and ensures the parts Forming accuracy and surface quality requirements improve the thickness uniformity of parts.

In one embodiment of the present invention, referring to Fig. 1, the preforming mold 1 and the lower mold 4 are respectively provided with an air inlet and an air outlet, the air inlet is provided with an air inlet pipe 9, and the air outlet is provided with There is an exhaust duct 6; the diameters of the air inlet and the air outlet are 2-4mm, and the air inlet is located at the center of the preforming mold 1, and the air outlet is arranged at the position where the sheet material 3 of the lower mold 4 is finally pasted. ;

The inflatable forming mold 2 is provided with an auxiliary groove 10 for an air intake pipe connected to an air intake device;

The preforming mold 1 is provided with a groove for placing the sealing ring 7, so that after the sealing ring 7 is placed in the groove, it is still higher than the lower surface of the preforming mold 1 by 3-5mm;

The sealing stem 8 is located at 10-20mm from the periphery of the part contour;

Multiple groups of weight-reducing grooves 5 are also provided on the lower mold 4 .

Please refer to Fig. 1-Fig. 13, a kind of method of superplastic inflation forming that can be fed is applied to the superplastic inflation forming mold that can feed as described above, and the method comprises the following steps:

Step 1: Install the upper mold and the lower mold 4 on the double-acting press, the preforming mold 1 and the inflation forming mold 2 of the upper mold are respectively installed on the inner slider and the outer slider of the press, and the air inlet pipe 9 is welded on the On the preforming mold 1;

Step 2: Air pressure preforming, when the mold temperature reaches the superplastic forming temperature and the temperature is uniform, place the sheet material 3 between the lower mold 4 and the preforming mold 1, open the intake valve after keeping warm for 5-10 minutes, and the sealing ring 7 prevents At the same time as the gas leaks, the sheet material 3 is fed into the cavity of the lower mold 4 under the action of the gas, as shown in Figure 3 and Figure 4, the preforming of the sheet material 3 is basically not reduced; the sealing ring 7 The type and model of the preforming mold are determined according to the superplastic forming temperature and the size of the parts. The preforming die 1 goes down until the sealing ring 7 contacts the upper surface of the sheet material 3, and the sealing ring 7 is in a compressed state to ensure that the sheet material 3 can flow and the gas does not will overflow;

Step 3: superplastic inflatable forming, after the sheet material 3 flows to form the basic shape of the part, the inflatable forming die 2 descends, presses the surrounding sheet material 3 to death, increases the air pressure, and completes the superplastic inflatable forming by stretching the sheet material 3;

In step 2, graphite lubricant is sprayed on both sides of the sheet 3 before blanking to facilitate feeding during preforming and demoulding after forming;

The gas pressure for preforming is 0.1-1MPa;

The upper mold and the lower mold 4 are installed on the heating platform, and the temperature of the heating platform is controlled by 8-16 groups of temperature control units, and the temperature is transferred to the upper mold and the lower mold 4 through heat conduction. After reaching the predetermined temperature, keep warm for 20-30min , to ensure uniform mold temperature;

In step 3, when the inflation forming die 2 descends, use the sealing stem 8 to fix the surroundings of the sheet material 3;

When the air pressure is increased, small and complex local shapes are formed. When the exhaust pipe 6 is basically free of gas, the pressure is maintained for 3-5 minutes, and the forming is completed.

In this embodiment, the finite element simulation method is used to calculate the forming process of the direct superplastic inflation forming method in this example. The thickness distribution of the sheet material 3 is shown in Figure 7 and Figure 8, and D-D is the thickness of the sheet material 3 along the diagonal Cross-sectional view; for this example, the initial thickness of sheet 3 is 2mm, and it is formed by direct superplastic inflation forming method, and serious thinning occurs at the bottom fillet, the minimum thickness is 0.84mm, and the product quality is unqualified;

Adopt finite element simulation means to calculate the forming process that this example adopts the method for the present invention, the thickness distribution of sheet material 3 after air pressure preforming is shown in Figure 9 and Figure 10, and E-E is the sectional view of sheet material 3 along the diagonal line; After preforming , the sheet material 3 flows into the cavity to form a basic shape, and the sheet material 3 is hardly thinned;

The thickness distribution of the sheet material 3 after the superplastic air expansion final forming is shown in Figure 11 and Figure 12, F-F is the cross-sectional view of the sheet material 3 along the diagonal; compared with the direct air expansion forming method, the method of the present invention can further The final sheet material 3 formed by the superplastic inflation forming method of the material is less thinned, and the thickness distribution of the sheet material 3 is more uniform;

As shown in Figure 13, the sheet material line for direct superplastic inflation forming is a solid line G, and the sheet material line is fixed at the initial position, while using the method of the present invention, the final sheet material line is as dotted line H, and the feeding is obvious, which directly Affects the final thickness distribution.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (9)

1. A feedable superplastic inflation forming mold, the mold is installed on a double-action press, comprises a patrix and a lower die, has a cavity in the described lower die, is characterized in that, the described patrix includes an inner Ring and outer ring, the inner ring is a feedable preforming mold with a sealing ring, and the outer ring is an inflatable forming mold with a sealing stem. 2. The superplastic inflation molding die that can be fed according to claim 1 is characterized in that, the preforming mold and the lower mold are respectively provided with an air inlet and an air outlet, and the air inlet is provided with an inlet and an air outlet. An air duct, an exhaust duct is arranged at the air outlet; the diameters of the air inlet and the air outlet are both 2-4mm. 3. The feedable superplastic inflatable forming die according to claim 2, characterized in that, the inflatable forming die is provided with an auxiliary groove for an air intake pipe connected to an air intake device. 4. The feedable superplastic inflation forming die according to claim 1 or 2, wherein a groove for placing a sealing ring is provided on the preforming die. 5. The feedable superplastic inflation forming die according to claim 1, wherein the sealing stem is located at 10-20 mm from the periphery of the part contour. 6 . The feedable superplastic inflation forming die according to claim 1 , wherein a plurality of groups of weight-reducing grooves are provided on the lower die. 7 . 7. A method for superplastic inflation molding that can be fed is characterized in that, it is applied to the superplastic inflation molding die that can feed as described in any one of claims 1 to 6, the method Include the following steps: Step 1: Install the upper mold and the lower mold on the double-action press, the preforming mold and the inflation forming mold of the upper mold are respectively installed on the inner slider and the outer slider of the press, and the air inlet pipe is welded on the preforming mold ; Step 2: Air pressure preforming. When the mold temperature reaches the superplastic forming temperature and the temperature is uniform, place the sheet between the lower mold and the preforming mold. After keeping warm for 5-10 minutes, open the intake valve and seal the ring to prevent gas leakage. , the sheet material is fed into the cavity of the lower mold under the action of gas; Step 3: Superplastic inflatable forming. After the sheet material flows to form the basic shape of the part, the inflatable forming die moves down to crush the surrounding sheet material, increase the air pressure, and complete the superplastic inflatable forming by stretching the sheet material. 8. the method for the superplastic inflation forming that can feed according to claim 7 is characterized in that, in step 2, all sprays graphite lubricant at sheet metal both sides before blanking; The gas pressure for preforming is 0.1-1MPa; The upper mold and the lower mold are installed on the heating platform, and the temperature of the heating platform is controlled by 8-16 groups of temperature control units, and the temperature is transferred to the upper mold and the lower mold through heat conduction. After reaching the predetermined temperature, keep it warm for 20-30min to ensure The mold temperature is uniform. 9. the method for the superplastic inflatable forming that can feed according to claim 7 is characterized in that, in step 3, when the inflatable forming mold descends, utilize sealing stem to fix around the sheet material; When the air pressure is increased, small and complex local shapes are formed. When the exhaust pipe is basically free of gas, the pressure is kept for 3-5 minutes, and the forming is completed.

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