KR102626343B1 - Apparatus for superplastic forming of large-area plates - Google Patents

Abstract

A molding device for superplastic processing of large-area materials is introduced.
The superplastic forming device for large-area materials of the present invention includes a chamber provided with an openable door on at least one side; A mold unit including an upper mold accommodated in the chamber and installed to be able to be raised and lowered within the chamber, and a lower mold that enters and exits the chamber, is selectively joined with the upper mold within the chamber, and supports a material; a first heater unit that transfers heat to the material through the mold unit; a driving cylinder that elevates the upper mold; a gas supply unit that provides gas pressure to the material so that the material can be superplastically molded; and a plate unit coupled to one end of the driving cylinder to press the material to prevent vibration during superplastic processing of the material.

Description

{Apparatus for superplastic forming of large-area plates}

The present invention relates to an apparatus for superplastic forming a large-area material, and more specifically, to an apparatus for superplastic forming a titanium alloy material with a width of 1.0 m or more, preferably a titanium alloy material with a width of 1.5 m or more.

In general, titanium alloy is a representative lightweight metal and has high strength and excellent corrosion resistance, so it is widely used as aerospace material and chemical industry material. In particular, Ti-6Al-4V alloy is used to manufacture aircraft parts of complex shapes. is widely used.

This type of titanium alloy has excellent strength and corrosion resistance, but has the disadvantage of being difficult to process (difficult-to-machine material), so the superplastic forming (SPF) method is used to manufacture aircraft parts of various and complex shapes. do.

Superplastic processing is a processing method that freely molds difficult-to-process metals like plastic by slowly applying gas pressure at high temperatures. It is a processing method suitable for processing complex shapes or multi-layer structures.

Compared to general molding methods, this superplastic molding method has the advantage of making it easier to manufacture products with complex shapes, reducing manufacturing costs, and reducing assembly costs because parts can be integrated and manufactured.

Korean Patent No. 10-1676762 (2016.11.10) discloses a “superplastic forming device” used for the above-described superplastic forming.

The 'super plastic molding device' disclosed in prior literature is intended to solve the problem of taking a long time in the process of raising the temperature of the mold to the deformable temperature of the plate, and includes a main body unit equipped with a heating work chamber, and the upper side of the main body unit. It includes a driving cylinder installed through the molding chamber and a pressure pin unit that pressurizes the upper side of the molding chamber to prevent the repulsive force caused by the gas while the gas is supplied to form the molded product and fix the molding chamber.

The main body unit is equipped with a heating chamber, and when the material is introduced into the heating chamber, the temperature inside the heating chamber increases to the temperature at which superplastic forming is possible. In this process, gas is injected while the upper mold and lower mold are joined by the operation of the driving cylinder to form the product.

In this process, a repulsive force may occur due to gas injection, and in the prior art, a pressure pin unit is used to prevent vibration, thereby solving defective problems that may occur during the product molding process.

However, although the pressure pin unit can prevent vibration occurring during the gas injection process by supporting the upper mold locally, it has a problem in that it cannot prevent vibration transmitted to the entire mold.

In other words, when using a pressure pin unit, it is possible to prevent vibrations that occur during the production of titanium material with a width of approximately 40 cm. However, with the recent trend of integration and enlargement of parts, the width of titanium material that is ultraplasticized is limited. It reaches approximately 1m to 1.5m, and there is a limit to preventing vibration generated during the superplastic forming process of such large-area titanium material using a joining pin unit.

In addition, in the prior art, a single driving cylinder is used to move the upper mold and merge it with the lower mold, but when a single driving cylinder is applied to the above-mentioned large-area titanium material processing process, there is a disadvantage that product defects may occur. do.

That is, gas is usually injected in a completely sealed state by combining the upper mold and the lower mold. However, when a single driving cylinder is used when molding a large-area titanium material, the sealing power of the mold is reduced, which causes internal gas Since the pressure cannot be properly controlled, defects in the shape of the final product occur.

The matters described as the above background art are only for the purpose of improving the understanding of the background of the present invention, and should not be taken as an acknowledgment that they correspond to prior art already known to those skilled in the art.

KR 10-1676762 B1(2016. 11. 10)

The present invention was developed to solve the above problems, and provides a superplastic forming device for large-area materials that can prevent defects in the final workpiece by preventing vibration during the superplastic processing of large-area materials. There is a purpose.

In addition, the purpose is to provide a super plastic molding device for large-area materials that can minimize temperature deviation depending on the location of the chamber and save energy by selectively operating the heater unit.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description of the present invention.

The superplastic forming device for large-area materials of the present invention includes a chamber provided with an openable door on at least one side; A mold unit including an upper mold accommodated in the chamber and installed to be able to be raised and lowered within the chamber, and a lower mold that enters and exits the chamber, is selectively joined with the upper mold within the chamber, and supports a material; a first heater unit that transfers heat to the material through the mold unit; a driving cylinder that elevates the upper mold; a gas supply unit that provides gas pressure to the material so that the material can be superplastically molded; and a plate unit coupled to one end of the driving cylinder to press the material to prevent vibration during superplastic processing of the material.

The plate unit may include a case formed to be more than the width and length of the material, the interior of which is formed as an empty space, and a plurality of load support bars installed to support the load transmitted to the case during superplastic processing of the material. You can.

The load support bar is installed in plural pieces at regular intervals in the longitudinal direction of the case, and is installed long in the vertical direction inside the case, and the empty space inside the case may be filled with an insulating material.

The first heater unit may be installed inside the case, but one surface may be exposed from the case.

The plate unit and the first heater unit may be installed as a pair, facing each other at a certain distance in the vertical direction with the mold unit in between.

A plurality of driving cylinders may be installed at regular intervals in the width direction of the material, and the first heater unit may include a heating block with a slot, and a cartridge heater inserted into the slot.

A second heater unit is installed on the inner wall of the chamber, and a plurality of second heater units are installed in the height direction of the chamber and can be individually controlled according to the temperature of each location of the inner space of the chamber.

The material may be a titanium alloy plate with a width of 1 m or more.

According to the present invention, by preventing vibration during superplastic processing of large-area materials, defects in the final workpiece can be prevented, temperature deviation depending on the location of the chamber can be minimized, and energy can be saved by selectively operating the heater unit. There is an effect.

1 is a configuration diagram of the superplastic forming device for large-area materials of the present invention;
Figure 2 is a schematic plan view of the superplastic forming device for large-area materials of the present invention;
Figure 3 is a view showing the installed state of the second heater unit, which is an essential part of the present invention;
Figure 4 is a detailed view of the second heater unit, which is an essential part of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited or limited by the embodiments. For reference, in this description, the same numbers refer to substantially the same elements, and under these rules, the description can be made by citing the content shown in other drawings, and content that is judged to be obvious to those skilled in the art or that is repeated can be omitted.

The present invention prevents vibration during superplastic processing of large-area materials, thereby preventing defects in the final workpiece, minimizing temperature deviation depending on the location of the chamber, and saving energy by selectively operating the heater unit. This relates to a superplastic forming device for large-area materials.

As shown in Figures 1 to 4, the superplastic forming apparatus for large-area materials of the present invention includes a mold unit 200 including a chamber 100, an upper mold 210, and a lower mold 220. 1Includes a heater unit 300, a driving cylinder 500, a gas supply unit (not shown), and a plate unit 600.

The chamber 100 is a space in which the mold unit 200 is accommodated and the material is molded, and an openable door D is provided on at least one side thereof. This chamber 100 may be formed in various shapes in consideration of material entry and exit, convenience of door installation, etc.

Additionally, a separate hydraulic mechanism (H) may be installed outside the chamber 100 to maintain the airtightness of the chamber 100 during the molding process.

The door (D) opens when the material (M) is introduced or withdrawn, and closes when the material (M) is introduced and molding is in progress. This door (D) may be installed to be sliding to open and close, or may be installed to be rotatable about one side.

To facilitate the insertion or withdrawal of the material (M), the material (M) can be loaded into and out of the lower mold (220). For convenience of work, the material (M) is placed in the lower mold (220). A transport rail system may also be installed.

The superplastic forming device of the present invention relates to a device for superplastic processing of large-area materials. The material (M) may be a titanium alloy material with a width of about 1.0m or more, preferably 1.5m or more, and aluminum if necessary. You can also select and use alloy materials.

The titanium material described above may be Ti-6Al-4V alloy, which is a large-area titanium alloy used in aircraft parts, etc., and the demand for it has recently been increasing for aircraft parts.

In the process of manufacturing aircraft parts using titanium alloy material, the inside of the chamber 100 may be created in an inert atmosphere to prevent the occurrence of alpha cases due to oxidation of the material. After the final part is manufactured, it is separately pickled or shot blasted to remove the alpha case formed on the surface of the part. However, if the alpha case is prevented during the molding process, there is a need for a post-processing process. can be reduced.

Various gases can be supplied to create an inert atmosphere.

The gas supplied to the mold during superplastic molding is also an inert gas to prevent oxidation of the material. The gas supplied at this time is mainly argon (Ar) gas, which is supplied to create an inert atmosphere inside the chamber 100. The gas used may also be the argon gas described above, and helium (He) or neon (Ne) gas may be used as needed.

The mold unit 200 includes an upper mold 210 and a lower mold 220, and the shape of the cavity formed by the upper mold 210 and the lower mold 220 varies depending on the shape of the part to be manufactured. The upper mold 210 and the lower mold 220 can be manufactured using various mold steels depending on the designer's selection.

The upper mold 210 is selectively joined to the lower mold 220 while being raised and lowered by the operation of the driving cylinder 500, which will be described later, and the lower mold 220 is placed on a rail with the material M loaded as described above. After traveling on the table and being drawn into the chamber 100, it is selectively joined with the upper mold 210 that moves up and down.

In a state where the upper mold 210 and the lower mold 220 are combined, the material M begins to deform as an inert gas is supplied by the gas supply unit. In this process, if a fine gap occurs between the upper mold 210 and the lower mold 220 and the inert gas leaks, it will cause product defects, so an O-ring ( It is desirable to install various sealing devices such as O-RING).

The first heater unit 300 transfers heat to the material M through the mold unit 200.

For superplastic deformation of the material (M), the inside of the chamber 100 must maintain a constant temperature, and the material (M) must also be heated to a temperature at which superplastic deformation is possible.

When performing superplastic forming of Ti-6Al-4V alloy, a titanium alloy material, the material (M) must be heated to over 850°C, and if the material (M) is AA5083 aluminum alloy material, it must be heated to 450-520°C. It must be heated, and when a certain gas pressure is applied under these temperature conditions, superplastic deformation of the material (M) occurs.

The first heater unit 300 and the second heater unit 400, which will be described later, function to heat the material M to the above-mentioned temperature range.

Meanwhile, during the process of superplastic forming the material M using the inert gas supplied by the gas supply unit, certain vibrations occur due to gas pressure, and these vibrations can become a fundamental cause of defects in the final parts.

In the present invention, this problem was solved by using the plate unit 600.

A pair of plate units 600 are installed facing each other at regular intervals in the vertical direction with the mold unit 200 in between.

That is, with the plate unit 600 supporting the lower mold 220 retracted into the chamber 100, the plate unit 600 coupled to the end of the driving cylinder 500 presses the upper mold 210. Afterwards, superplastic forming is performed, and the vibration generated by the gas pressure is transmitted to the plate unit 600 and dissipated, thereby preventing defects in the final product.

The material (M) applied to the present invention is a material with a width of 1.0 m or more, preferably a width of 1.5 m, which can sufficiently prevent vibration transmitted to the mold unit 200 just by locally pressing the upper mold 210. I can't. That is, in the molding process, the entire width direction of the material M and the mold unit 200 must be pressed to achieve the desired purpose. In the present invention, the plate unit 600 is introduced to achieve this purpose. .

In addition, there is a need to apply a plurality of driving cylinders 500 to transmit a predetermined pressure to the plate unit 600, and in the present invention, a plurality of driving cylinders 500 are applied to the upper mold 210 side.

Through various experiments, a total of six driving cylinders 500 were applied by arranging three driving cylinders 500 in two rows in the width direction. As a result, it was possible to minimize the vibration transmitted to the mold unit 200, and it was possible to minimize the vibration transmitted to the mold unit 200. In the embodiment, six driving cylinders 500 were applied as described above.

The plate unit 600 may include a case 610, a load support rib 620, and an insulating material 630, between the plate unit 600 and the upper mold 210, and between the plate unit 600 and the lower mold. The above-described first heater unit 300 may be interposed between 220 .

Case 610 may be manufactured to have a length greater than the width of the material M, and its interior may be formed as an empty space.

The plurality of driving cylinders 500 described above are installed on the plane of the case 610, and a separate bracket B may be formed on the plane of the case for convenience of coupling the driving cylinder 500 and the case 610.

The inside of the case 610 may be formed as an empty space, and a load support beam 620 may be installed inside the empty space.

The load support rib 620 is formed to be long in the vertical direction, and its upper and lower ends are respectively coupled to the inner wall of the case 610. As an example, these load support ribs 620 may be manufactured and installed in the form of an iron block, and a plurality of load support ribs 620 may be installed at regular intervals in the longitudinal direction of the case 610.

Therefore, since the load support rib 620, which has a significant weight, supports the upper mold 210 and the lower mold 220 during the molding process, the vibration generated due to gas supply is caused by the case 610 and the load support rib 620. ) is absorbed and dissipated, making it possible to prevent final product defects due to vibration.

Meanwhile, during the process of forming the material (M), the temperature of the material (M) must be maintained at a temperature that can be changed to superplasticity. The first heater unit 300 and the second heater unit 400 are used to heat the material and maintain the temperature, and an insulating material 630 is used in the empty space between the load support ribs 620 inside the case 610 for insulation. is filled.

As described above, the first heater unit 300 transfers heat to the material through the upper mold 210. This first heater unit 300 includes a heating block 310 and a cartridge heater 320. can do.

The heating block 310 is built into the case 610, and is installed so that one side of it is exposed to the outside through the bottom of the case 610. A slot 310a is formed in this heating block 310, and the cartridge heater 320 is inserted into the slot 310a formed in the heating block 310 in a sliding manner.

In addition, the shape of the slot 310a is formed to correspond to the shape of the cartridge heater 320, and in the present invention, the slot 310a and the cartridge heater 320 are formed in a “T” shape.

The second heater unit 400 is installed on the inner wall of the chamber 100 and functions to heat the inner space of the chamber 100 to the temperature required for superplastic forming and maintain the temperature.

When the chamber 100 is formed in a hexahedral shape, the second heater unit 400 is preferably installed on each of the four walls forming the inner wall of the chamber 100.

During the heating and forming process, the inside of the chamber 100 is maintained at a high temperature, and the high-temperature gas rises and the low-temperature gas falls, resulting in a temperature difference depending on the height and a temperature difference depending on the location of the internal space. .

In order to resolve this temperature difference by location, it is preferable to install a plurality of second heater units 400 in the height direction of the chamber 100 to individually control the temperature.

That is, it is preferable that the internal space of the chamber 100 be divided into an upper area, a central area, and a lower area, and a second heater unit 400 and a temperature sensor (not shown) corresponding to each area are installed, respectively, and the control unit In step 700, it is desirable to control the temperature deviation by controlling the output of the second heater unit 400 based on the temperature data of each region provided from the temperature sensor.

The control unit 700 controls the output of the second heater unit 400 located in the upper region, central region, and lower region according to Equations 1 to 3 described later, and outputs so as to satisfy Equation 4 below. .

Equation 1: H1 = a(Tm-T1)

Equation 2: H2 = b(Tm-T2)

Equation 3: H3 = c(Tm-T3)

Equation 4: [H1/(Tm-T1)] ≤ [H2/(Tm-T2)] ≤ [H3/(Tm-T3)]

However, H1 is the output of the second heater unit 400 located in the upper region, H2 is the output of the second heater unit 400 located in the central region, and H3 is the output of the second heater unit 400 located in the lower region. output, Tm is the target temperature, T1 is the temperature measured by the sensor located in the upper area, T2 is the temperature measured by the sensor located in the central area, T3 is the temperature measured by the sensor located in the lower area, a, b , c are conversion constants, respectively.

The conversion constants a, b, and c are determined according to the absolute value of the measured temperature and a kind of table that returns a predetermined value according to the difference between the target temperature and the measured temperature.

The conversion constants a, b, and c may be prepared to return the same value according to given conditions, but it is preferably controlled to return different values to satisfy Equation 4.

That is, even if the differences between the target temperature Tm and the temperature T1 of the upper region, the temperature T2 of the central region, and the temperature T3 of the lower region are all the same, the output of the second heater unit 400 located in the upper region is located in the central region rather than the output of the second heater unit 400 located in the upper region. The output of the second heater unit 400 is controlled to be higher or equal, and the output of the second heater unit 400 located in the lower area is higher than the output of the second heater unit 400 located in the central area. It is controlled to be higher or equal.

The reason why the control is performed at a higher output the lower it is located in the chamber 100 is that, as described above, the upper area of the chamber 100 shows a higher temperature as high-temperature gas rises due to convection, and the lower area shows a lower temperature. This is because the gas descends, resulting in a lower temperature.

In other words, when the same temperature is measured in the upper area, central area, and lower area, and the second heater unit 400 installed in each area is controlled and heated with the same output, the upper area is heated to a higher temperature. This results in the central region and lower region being heated to a lower temperature.

Therefore, if the difference from the target temperature (Tm) is the same, the output of the second heater unit 400 that heats the upper region is controlled to be weakest, and the output of the second heater unit 400 that heats the lower region is controlled to be strongest. The second heater unit 400, which heats the central area, must be controlled by the intermediate output of the second heater units located in the upper and lower areas to uniformly heat all spaces inside the chamber.

This is expressed by Equation 4 above.

Meanwhile, the conversion constants a, b, and c used to calculate the output in the control unit 700 are derived as a≤b≤c by equations 1 to 4, so it is necessary to control the size between each conversion constant in this way. there is.

At this time, the reason for using the ideal inequality sign (≤) instead of the excess inequality sign (<) in the size comparison between Equation 4 and the conversion constant is that the difference between the internal temperature of the chamber 100 and the target temperature (Tm) is large at the beginning of heating, so the upper region, It is more effective to heat all the second heater units 400 installed in the central area and the lower area at 100% output, and when the internal temperature of the chamber reaches the target temperature (Tm), all heaters are then turned off or set to a predetermined level. This is because heating can be maintained with the same output. In the above cases, Equation 4 and the conversion constants all represent the same numerical value.

As described above, although the present invention has been described with reference to preferred embodiments, those skilled in the art may make various modifications and changes to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that you can do it.

100: Chamber 200: Mold unit
210: upper mold 220: lower mold
300: first heater unit 310: heating block
320: cartridge heater 310a: slot
400: second heater unit 500: driving cylinder
600: plate unit 610: case
620: load support bar 630: insulation material
700: Control unit
D: Door H: Hydraulic mechanism
M: Material B: Bracket

Claims (8)

A chamber provided with an openable door on at least one side;
A mold unit including an upper mold accommodated in the chamber and installed to be able to be raised and lowered within the chamber, and a lower mold that enters and exits the chamber, is selectively joined with the upper mold within the chamber, and supports a material;
a first heater unit that transfers heat to the material through the mold unit;
a second heater unit installed on the inner wall of the chamber to individually heat at least three regions of the upper, middle, and lower regions in the height direction of the chamber, and individually controlled according to the temperature of each location of the inner space of the chamber;
a driving cylinder that elevates the upper mold;
a gas supply unit that provides gas pressure to the material so that the material can be superplastically molded; and
A plate unit coupled to one end of the driving cylinder to pressurize the material to prevent vibration during superplastic processing of the material,
The plate unit is,
a case formed to have a width equal to or greater than the width of the material, and the inside of which is formed as an empty space; and a plurality of load support bars installed at regular intervals in the longitudinal direction of the case and installed elongated in the vertical direction inside the case.
The load support bar absorbs vibration transmitted from the mold unit to the plate unit during superplastic processing of the material,
The second heater unit is a superplastic forming device for large-area materials, characterized in that controlled by the following equation.

Formula: [H1/(Tm-T1)] ≤ [H2/(Tm-T2)] ≤ [H3/(Tm-T3)]
However, H1 is the output of the second heater unit located in the upper area, H2 is the output of the second heater unit located in the central area, H3 is the output of the second heater unit located in the lower area, Tm is the target temperature, T1 is the temperature measured by the sensor located in the upper area, T2 is the temperature measured by the sensor located in the central area, and T3 is the temperature measured by the sensor located in the lower area.
delete In claim 1,
A superplastic molding device for large-area materials, characterized in that the empty space inside the case is filled with an insulating material.
In claim 3,
The first heater unit,
A superplastic forming device for a large-area material, which is installed inside the case and one surface of which is exposed from the case.
In claim 4,
The plate unit and the first heater unit are installed as a pair,
A superplastic molding device for a large-area material, characterized in that it is installed to face each other at a certain distance in the vertical direction with the mold unit in between.
In claim 5,
A plurality of driving cylinders are installed at regular intervals in the width direction of the material,
The first heater unit includes a heating block with a slot formed, and a cartridge heater inserted into the slot.
delete The method according to any one of claims 1, 3, and 6,
A superplastic forming device for large-area materials, characterized in that the material is a titanium alloy plate with a width of 1 m or more.

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