WO2012120989A1

WO2012120989A1 - Method for forming sheet material, sheet material forming apparatus, method for determining forming conditions for sheet material forming apparatus, and device for determining forming conditions for sheet material forming apparatus

Info

Publication number: WO2012120989A1
Application number: PCT/JP2012/053717
Authority: WO
Inventors: 佐藤　広明; 孝洋橘
Original assignee: 三菱重工業株式会社
Priority date: 2011-03-09
Filing date: 2012-02-16
Publication date: 2012-09-13
Also published as: JP2012187600A

Abstract

Provided are a method for forming sheet material, a sheet material forming apparatus, a method for determining forming conditions for the sheet material forming apparatus, and a device for determining forming conditions for the sheet material forming apparatus that can process sheet material with excellent precision when locally heating and forming the sheet material. This method for forming sheet material includes a pressing step that presses a part of a sheet material (10) being formed, which is loaded with a tensile force in a state where the tensile force load has been applied to the sheet material (10), which is formed from titanium or a titanium alloy, to a metal mold (2) that has a curvature for the molding objective and a heating step for continuously heating or intermittently heating at least the part of the sheet material (10) being formed on a plurality of lines parallel to each other.

Description

Sheet material forming method, sheet material forming apparatus, forming condition determining method for sheet material forming apparatus, and forming condition determining apparatus for sheet material forming apparatus

The present invention relates to a plate material forming method, a plate material forming device, a forming condition determining method for a plate material forming device, and a forming condition determining device for a plate material forming device, in which a plate material is formed by locally heating.

When titanium alloy is cold worked, springback and cracking are likely to occur. Further, in cold working, it is essential to remove residual stress generated after molding. For this reason, in the plate processing of a titanium alloy, the residual stress removal is unnecessary and hot forming with good formability is performed. However, hot processing requires dedicated equipment for heating and processing, and the cost of equipment and jigs such as a mold having strength against high temperatures is expensive. Moreover, in hot processing, heating time and holding time are required, and there is a problem that processing time is long.

On the other hand, the local thermoforming technique is different from the conventional hot working in which the whole plate material is thermoformed, and the plate material is locally heated to form a target shape. For the local heating, for example, a heating source that is movable and can heat the plate material in a dot shape or a relatively small circular shape is used. This technology is cheaper in equipment cost and jig cost than conventional hot working, and can be processed in a short time.

Patent Document 1 describes basic specifications regarding a local heat forming apparatus.

US Pat. No. 6,601,426

Titanium alloy has low thermal conductivity, and the temperature gradient increases at the boundary between the heating region irradiated by the heating source and the non-heating region other than the heating region. Therefore, the thermal expansion of the heating region is constrained to the surrounding non-heating region, which is at a lower temperature than the heating region, and an out-of-plane deformation as shown in FIG. 1 occurs. That is, the plate member 10 is not formed into a shape along the mold 2 due to thermal expansion of the portion irradiated by the heating source 4.

Also, strain mismatch occurs at the boundary between the high temperature heating region and the low temperature non-heating region, and residual stress is generated at the boundary after molding. Furthermore, while the heating source is moving, the stress distribution of the material changes, causing non-uniform distortion in the moving direction of the heat source.

On the other hand, the local heating technique using the local heating molding apparatus such as Patent Document 1 does not describe specific molding conditions, and there is a cause for the reduction in shape accuracy as described above, and the molding conditions must be adjusted. It is not pointed out that high-precision molding cannot be performed. Therefore, it has been difficult to form a plate material with high accuracy by the molding method using the local heat molding apparatus according to the prior art.

The present invention has been made in view of such circumstances, and a plate material forming method, a plate material forming apparatus, and a plate material that can accurately process a plate material when the plate material is locally heated and formed. It is an object of the present invention to provide a molding condition determination method for a molding apparatus and a molding condition determination apparatus for a sheet material molding apparatus.

In order to solve the above problems, the plate material forming method, the plate material forming apparatus, the molding condition determining method for the plate material forming apparatus, and the molding condition determining device for the plate material forming apparatus of the present invention employ the following means.
That is, in the plate material forming method according to the first aspect of the present invention, in a state in which a tensile force is applied to a plate made of titanium or a titanium alloy, a molded portion of the plate material loaded with the tensile force is set to a curvature of the forming target. A pressing step for pressing against the mold having the heating step, and a heating step for heating at least a molded portion of the plate material continuously or intermittently on a plurality of parallel lines.

According to the first aspect, a tensile force is applied to a plate made of titanium or a titanium alloy, and a mold having a molding target curvature is pressed against a formed portion of the plate applied with the tensile force. Then, at least a molded portion of the plate material is continuously or intermittently heated on a plurality of lines parallel to each other. In addition, although a board | plate material deform | transforms with heating and a board | plate material may float from a metal mold | die, when a board | plate material floats from a metal mold | die, it will become easy to raise | generate an out-of-plane deformation. Therefore, when the plate material floats from the mold, it is desirable to adjust the position of the mold or the pulling direction of the plate material to heat the plate material while keeping the mold and the plate material in close contact with each other.

Titanium or a titanium alloy has a lower thermal conductivity than aluminum or an aluminum alloy, and the temperature gradient increases at the boundary between a heated region heated by the heating unit and a non-heated region that is not heated. Therefore, the thermal expansion of the heating region is constrained by the non-heating region, and the heating region is deformed out of plane by the thermal expansion. In the first aspect, the plate is heated continuously or intermittently on one line, and is heated on a plurality of lines parallel to each other. For this reason, in the plate material, the molded portion against which the mold is pressed is not entirely heated or only by one line, but the heated portion is at least two lines, and the heating region is controlled. Therefore, it is easy to mold the plate material to the curvature of the molding target as compared with the case where the entire surface is heated or the case where it is heated only by one line.

In addition, when the plate material is heated intermittently on one line, the amount of elongation can be reduced and lifting can be suppressed compared to the case where the plate material is heated continuously on one line. Can be improved.

Note that the heating of the plate material may be such that the heating unit can move relative to the plate material, and the heating unit heats the plate material continuously or intermittently in one direction, and then moves on the adjacent line. Good. Alternatively, a black body paint may be applied to the surface of the plate material and the heating unit may be heated uniformly with respect to the plate material. The portion to which the black body paint is applied has a higher absorption capacity than the metallic luster portion and is easily heated. In addition, the portion where the black body paint is applied does not change the emissivity due to oxidation due to heating, and can be heated to a stable temperature. Furthermore, the heating unit may be configured to have a shape in which a heating pattern is formed, and the plate material may be heated in a heating pattern shape by a single heating.

In the first aspect, it is desirable to heat at least a molded portion of the plate material at 500 ° C. or higher.

Titanium or a titanium alloy usually has a strength lower than 500 ° C., that is, yield stress decreases. Therefore, according to the present invention, it becomes easier to give plastic deformation to the plate material than in the case of normal temperature, and the amount of elastic deformation is reduced by lowering the yield stress of the plate material, so the amount of springback after forming is also reduced. As a result, it is easy to process the plate material into a shape along the mold.

In the first aspect, the pitch between adjacent lines in the heating step may be a length determined according to the curvature of the forming target of the plate material.

According to the first aspect, since the pitch between the lines is determined according to the curvature of the forming target of the plate material, the interval between the heating region and the non-heating region is adjusted in the plate material. As a result, since the thermal expansion in the plate material is adjusted, the plate material can be accurately molded to the desired curvature.

In the first aspect, the heating temperature of the heating unit in the heating step may be determined according to the curvature of the forming target of the plate material.

According to the first aspect, since the heating temperature is determined in accordance with the curvature of the forming target of the plate material, the expansion length generated by the thermal expansion in the plate material is adjusted. As a result, it is possible to accurately mold the plate material to the desired curvature. The heating temperature may be adjusted by the set temperature of the heating unit, or may be adjusted by heating the same scanning line a plurality of times.

In the first aspect, the tensile force applied in the loading step may be determined according to the curvature of the forming target of the plate material.

According to the first aspect, since the tensile force is appropriately set according to the curvature of the forming target of the plate material, the strain generated in the plate material is adjusted. As a result, it is possible to accurately mold the plate material to the desired curvature.

In the first aspect, in the heating step, a movable light source may be used as a heating source, and the heating area may be controlled in accordance with the curvature of the plate material forming target.

According to the first aspect, the plate is heated by the movable light source. At this time, the heating area by the heating source is controlled by the curvature of the forming target of the plate material. The light source is, for example, a lamp using light energy such as a halogen lamp, or various lasers. Further, as long as the amount of heat input and temperature can be controlled, it is generally possible to use a flame associated with combustion of an arc or gas generally used in welding, or heating by high frequency. In this case, it is desirable that the temperature can be controlled and the heat source can be moved.

In the first aspect, when a gap is generated between the plate material and the mold due to heating, the plate material may be heated and molded in a state where no gap is generated between the plate material and the mold.

According to the first aspect, when a gap is generated between the plate material and the mold due to the plate material floating from the mold, the mold and the plate material are adjusted by adjusting the position of the mold or the tension direction of the plate material. The plate material is heated while maintaining the close contact state. When the plate material floats from the mold, the plate material is likely to be deformed out of plane, but this can be prevented.

In the first aspect, the heat input during heating and the temperature control may be performed by changing the emissivity between the heating region and the non-heating region of the plate material.

According to the first aspect, since the plate material is titanium or a titanium alloy, the light absorption rate is usually poor on the surface of the plate material. On the other hand, before the heating step, for example, by applying black body paint or oxidizing treatment at a required portion, by changing the emissivity between the heating area and the non-heating area on the surface of the plate material, Heat input and temperature control can be performed.

In the first aspect, the temperature of the portion heated by the plate material may be measured by a radiation thermometer.

According to the first aspect, the temperature of the portion where the radiation thermometer is heated by the plate material is measured, and the output of the heating source is controlled based on the measured temperature. By controlling the temperature of the heating section, process reproducibility can be improved and material deterioration due to overheating can be prevented. If the heating source is movable, the radiation thermometer may be movable with the heating source.

In the first aspect, when the heating unit intermittently heats the plate material in the moving direction in the heating step, the heating distance or non-heating distance on one scanning line is determined according to the curvature of the forming target of the plate material. The length may be the same.

According to the first aspect, when the plate material is intermittently heated in the moving direction, the heating distance or non-heating distance on one scanning line is determined according to the curvature of the forming target of the plate material. Therefore, the area | region which reduces elongation amount in a board | plate material or suppresses a lift is adjusted. As a result, it is possible to accurately mold the plate material to the desired curvature.

In the first aspect, in the heating step, the heating unit may heat the plate material other than the molded portion.

According to the first aspect, not only the molded portion but also the molded portion of the plate material is heated, and the non-heated region becomes a region deviated from the molded portion. Thereby, it becomes possible to shape | mold without leaving a residual stress in a shaping | molding part, and high quality shaping | molding can be performed.

In the first aspect, after the forming by the heating step, a non-heated region that is not heated by the heating unit may be removed from the plate material.

According to the first aspect, the non-heated region that is not heated by the heating unit in the plate material is removed from the formed plate material after the forming by the heating step. Thereby, the residual stress which arises in the boundary of a heating area | region and a non-heating area | region can be reduced. In particular, the residual stress can be removed and the molding accuracy can be improved by cutting the material on the heating region side of the boundary.

Further, the plate material forming apparatus according to the second aspect of the present invention includes a load portion that applies a tensile force to a plate material made of titanium or a titanium alloy, and a formed portion of the plate material that is loaded with the tensile force, with a curvature of a forming target. And a heating section that heats at least a molded portion of the plate material continuously or intermittently on a plurality of parallel lines.

According to the second aspect, the tensile force is applied to the plate made of titanium or titanium alloy by the load portion, and the formed portion of the plate material to which the tensile force is loaded by the pressing portion has a forming target curvature. The mold is pressed. Then, at least a molded portion of the plate material is continuously or intermittently heated on a plurality of lines parallel to each other.

The plate material is continuously or intermittently heated on one line and heated on a plurality of lines parallel to each other. For this reason, in the plate material, the molded portion against which the mold is pressed is not entirely heated or only by one line, but the heated portion is at least two lines, and the heating region is controlled. For this reason, it is easier to mold the plate material to the molding target curvature as compared to the case where the entire surface is heated or the case where the plate material is heated only by one line. In addition, when the plate material is heated intermittently on one line, the amount of elongation can be reduced or the lifting can be suppressed compared to the case where the plate material is heated continuously on one line. Accuracy can be improved.

In the second aspect, the heating unit may use a movable light source as a heating source, and the heating area may be controlled in accordance with the curvature of the forming target of the plate material.

According to the second aspect, the plate is heated by the movable light source. At this time, the heating area by the heating source is controlled by the curvature of the forming target of the plate material.

In the second aspect, the temperature of the portion heated by the plate material may be measured by a radiation thermometer.

According to the second aspect, the temperature of the portion where the radiation thermometer is heated by the plate material is measured, and the output of the heating source is controlled based on the measured temperature. If the heating source is movable, the radiation thermometer may be movable with the heating source.

Moreover, the molding condition determination method of the plate material molding apparatus according to the third aspect of the present invention includes a load portion that applies a tensile force to a titanium or titanium alloy plate material, and a molded portion of the plate material that is loaded with the tensile force. , Forming a plate forming apparatus comprising: a pressing portion that presses against a mold having a curvature of a forming target; and a heating portion that continuously or intermittently heats at least a forming portion of the plate on a plurality of parallel lines. A method for determining conditions, in which a pitch between adjacent lines, a heating temperature for heating a plate material, and a setting step for setting a tensile force applied to the plate material, and the plate material is heated by the set pitch, heating temperature and tensile force The calculation step of calculating the curvature of the plate material obtained from time to time based on the strength change and thermal expansion of the material due to heating of the plate material, the curvature of the forming target, and the calculated curvature of the plate material And compare, and a determining step of determining pitch, the heating temperature and the tensile force in the actual sheet molding.

According to the third aspect, first, the pitch between adjacent lines, the heating temperature for heating the plate material, and the tensile force applied to the plate material are set, and then the set pitch, heating temperature, and tensile force are set. The curvature of the plate material obtained when the plate material is heated by is calculated based on the change in strength of the material (for example, softening of the material) and thermal expansion due to the heating of the plate material. Then, the calculated curvature of the plate material is compared with a predetermined curvature of a forming target, and a pitch, a heating temperature, and a tensile force when actually forming are determined based on the comparison result. Therefore, appropriate molding conditions in the above-described plate material forming apparatus can be estimated and determined in advance, and the plate material can be formed with high accuracy.

In addition, a molding condition determination device for a plate material forming apparatus according to the fourth aspect of the present invention includes a load portion for applying a tensile force to a plate material made of titanium or a titanium alloy, and a formed portion of the plate material to which the tensile force is applied. , Forming a plate forming apparatus comprising: a pressing portion that presses against a mold having a curvature of a forming target; and a heating portion that continuously or intermittently heats at least a forming portion of the plate on a plurality of parallel lines. It is a condition determining device, and the plate material is heated by the setting portion for setting the pitch between adjacent lines, the heating temperature for heating the plate material, and the tensile force applied to the plate material, and the set pitch, heating temperature and tensile force. Comparing the curvature of the obtained plate material based on the strength change and thermal expansion of the material due to heating of the plate material, the molding target curvature and the calculated plate material curvature, Comprising pitch, and a determination unit that determines the heating temperature and the tensile force in the sheet molding.

According to the fourth aspect, first, the pitch between adjacent lines, the heating temperature for heating the plate material, and the tensile force applied to the plate material are set by the setting unit. Next, the curvature of the plate obtained when the plate is heated by the set pitch, heating temperature, and tensile force is calculated by the calculation unit, and the strength change (for example, softening of the material) and thermal expansion due to the heating of the plate Is calculated based on Then, the calculated curvature of the plate material is compared with the curvature of the molding target determined in advance, and the pitch, heating temperature, and tensile force when actually forming are determined based on the comparison result. The Therefore, appropriate molding conditions in the above-described plate material forming apparatus can be estimated and determined in advance, and the plate material can be formed with high accuracy.

According to the present invention, when the plate material is locally heated and molded, the plate material can be processed with high accuracy.

It is a side view which shows a metal mold | die and a board | plate material in order to show the out-of-plane deformation | transformation which arises by local heating. It is a top view which shows a metal mold | die and a board | plate material in order to show the heating area | region and component part in local heating. It is a graph which shows the relationship between stress and temperature. It is a side view which shows the board | plate material shaping | molding apparatus which concerns on one Embodiment of this invention. It is a side view which shows the board | plate material shaping | molding apparatus which concerns on one Embodiment of this invention. It is a side view which shows the board | plate material shaping | molding apparatus which concerns on one Embodiment of this invention. It is a side view which shows the board | plate material shaping | molding apparatus which concerns on one Embodiment of this invention. It is a side view which shows the board | plate material shaping | molding apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the board | plate material shaping | molding method by the board | plate material shaping | molding apparatus which concerns on one Embodiment of this invention. It is a perspective view which shows an example of the shape | molded board | plate material. It is explanatory drawing which shows the irradiation area | region and heating pitch by a heat source. It is a graph which shows the relationship between the curvature radius and irradiation rate of the board | plate material after shaping | molding. It is a graph which shows the relationship between the curvature radius of the board | plate material after shaping | molding, and heating temperature. It is a graph which shows the relationship between the curvature radius of the board | plate material after shaping | molding, and tensile stress. It is a top view which shows a metal mold | die and a board | plate material in order to show the heating pitch in local heating. (A) is a fragmentary sectional view which shows the cross section of a metal mold | die, (B) is a graph which shows the relationship between the curvature radius of the board | plate material after shaping | molding, and the distance from a metal mold | die center. It is a graph which shows the relationship between the height from the vertex of the board | plate material after shaping | molding, and the distance from a metal mold | die center. It is a graph which shows the relationship between the height from the vertex of the board | plate material after shaping | molding, and the distance from a metal mold | die center. It is a top view which shows a metal mold | die and a board | plate material in order to show the heating pitch in local heating. It is a perspective view which shows an example of the shape | molded board | plate material. It is a top view which shows a metal mold | die and a board | plate material in order to show the irradiation part in local heating. It is a top view which shows a metal mold | die and a board | plate material in order to show the irradiation part in local heating. It is a top view which shows a metal mold | die and a board | plate material in order to show the irradiation part in local heating. It is a graph which shows the relationship between the distance from the metal mold | die of the board | plate material after shaping | molding, and the distance of the width direction from a board | plate material edge part.

Embodiments according to the present invention will be described below with reference to the drawings.
The plate material forming by the plate material forming apparatus according to an embodiment of the present invention is, for example, a plate material made of titanium or a titanium alloy. By forming the plate material, for example, an aircraft fuselage outer plate, a wing leading edge, a metal cover of a helicopter blade, and the like can be obtained. The titanium alloy is an alloy containing titanium as a main component, and contains aluminum, iron, tin, molybdenum, vanadium, and the like as additive elements.

As shown in FIG. 6, the plate material forming apparatus 1 according to the present embodiment includes a mold 2, a hydraulic cylinder 3 for moving the mold 2, a heating source 4, a clamp 5, a hinge 6, and a clamp And a hydraulic cylinder 7 for moving 5. The mold 2 is arranged between the two clamps 5. Two clamps 5, hinges 6 and hydraulic cylinders 7 are provided. In this embodiment, a hydraulic cylinder is used, but an electrically driven cylinder or a cylinder using air pressure may be used as long as the length and load can be adjusted.

The mold 2 is a mold for making the plate material 10 a target shape, and is fixed to the hydraulic cylinder 3. The hydraulic cylinder 3 can move the mold 2, and can bring the mold 2 close to the plate material 10 to be molded or can separate the mold 2 from the plate material 10. The hydraulic cylinder 3 is an example of a pressing portion, and presses the mold 2 against a molded portion of the plate material 10.

The heating source 4 is an example of a heating unit, for example, a lamp using light energy such as a condensing halogen lamp, or a light source such as various lasers. The heating source 4 is movable and can heat the plate 10 in a dot shape or a relatively small circular shape. In this embodiment, the heating source 4 continuously or intermittently heats at least a molded portion of the plate material 10 on a plurality of lines parallel to each other. In addition, the temperature of the part currently heated with the board | plate material may be measured with a radiation thermometer (not shown). At this time, the radiation thermometer measures the temperature of the portion heated by the plate member 10, and the output of the heating source 4 is controlled based on the measured temperature. If the heating source 4 is movable, the radiation thermometer may be movable together with the heating source 4.

The clamp 5 grips the plate material 10 and releases the grip of the plate material 10. The clamp 5 fixes the plate 10 by, for example, screwing or a hydraulic mechanism. The hinge 6 has one end connected to the clamp 5 and the other end connected to the hydraulic cylinder 7. The clamp 5 can be rotated with respect to the hydraulic cylinder 7 to change the direction of the clamp 5. Although not shown in the figure, the hinge 6 preferably has a function of adjusting the angle with respect to the hydraulic cylinder 7.

The hydraulic cylinder 7 can move the clamp 5 and can move the clamp 5 closer to the mold 2 side or away from the mold 2. When the mold 2 is pressing the plate material 10, the hydraulic cylinder 7 can apply a tensile force to the plate material 10 by moving the clamp 5 in a direction away from the mold 2.

Next, with reference to FIG. 9, the board | plate material shaping | molding method by the board | plate material shaping | molding apparatus of this embodiment is demonstrated.
First, as shown in FIG. 4, the plate 10 that is a material to be molded is restrained by the clamp 5 in a state where the mold 2 is lowered (step S <b> 1). Next, as shown in FIG. 5, the position of the clamp 5 is adjusted while raising the mold 2 (step S2). That is, as the mold 2 moves up, the hydraulic cylinder 7 operates so that the clamp 5 is brought closer to the mold 2 side. At this time, the plate 10 is brought into close contact with the mold 2 by the rotation of the hinge 6.

Then, while the hydraulic cylinder 3 fixes the position of the mold 2, the hydraulic cylinder 7 applies a tensile force to the plate material 10 (step S3). With a soft plate material made of aluminum or aluminum alloy instead of titanium or titanium alloy, molding is completed in the state up to step S3 of the present embodiment. However, titanium and titanium alloys have high yield stress, and spring back occurs after forming at room temperature, so that a sufficient shape cannot be imparted. In this embodiment, a plate material made of titanium or a titanium alloy is used as a material to be molded, and therefore the surface of the plate material 10 is heated by the heating source 4 while maintaining the state of step S3.

First, for example, as shown in FIG. 6, the heating source 4 is arranged at the heating position (step S4). And the required part of the board | plate material 10 is heated with the heat source 4 (step S5). For example, the plate material 10 is heated using the heating source 4 until the plate material 10 to which the tensile force is applied is in a temperature range in which plastic deformation is applied to the plate material 10. The temperature range where plastic deformation is applied is the temperature range when the strength is increased to about half of the strength at room temperature. If it is a material which has a characteristic as shown in FIG. 3, the board | plate material 10 will be heated to 500 degreeC or more which material strength begins to fall rapidly. Thereby, compared with the case of normal temperature, it becomes easy to give plastic deformation with respect to the board | plate material 10, and since the amount of elastic deformation reduces by the fall of the yield stress of the board | plate material 10, the amount of springbacks after shaping | molding also becomes small. As a result, it is easy to process the plate material 10 into a shape along the mold 2.

When the plate 10 is heated to a predetermined temperature by heating, the heating source 4 is moved in the longitudinal direction of the plate 10 or in the direction perpendicular to the longitudinal direction. At this time, the heating source 4 heats the plate 10 continuously or intermittently on the line. When the predetermined heating area is covered by the movement of the heating source 4, the heating is finished. In addition, when the phenomenon which the board | plate material 10 floats from the metal mold | die 2 arises by the deformation | transformation accompanying heating, a tensile force is increased by driving the hydraulic cylinder 3 and the hydraulic cylinder 7, and the board | plate material 10 and the metal mold | die 2 are increased. Adhere. Then, in a state where no gap is generated between the plate material 10 and the mold 2, the plate material 10 is heated and molded to obtain a more accurate component.

After the heating is finished, the external force that restrains the plate 10 that has been molded by heating to become a molded product is removed (step S6). That is, the tensile force generated by the

hydraulic cylinders

3 and 7 is released. And as shown in FIG. 8, the metal mold | die 2 and a molded product are removed (step S7). Thereby, a molded product is obtained. If necessary, in order to reduce the residual stress that occurs at the boundary between the heated area and the non-heated area, the part is made to remove residual stress and form accuracy by cutting the material on the heated area side of the boundary. It is possible to improve.

Next, a heating pattern by the heating source 4 will be described.
In step S5 described above, in order to obtain a target shape when the plate material 10 is heated and molded, not only the shape of the mold 2 but also the setting of the portion (heating region) where the heating source 2 irradiates the material, Set the heating temperature and tensile force.

The curvature radius R1 of the cross section of the molded product by the plate 10 shown in FIG. 10 and the curvature radius R2 in the width direction vary depending on the heating range, heating temperature, and tensile force. For example, as shown in FIG. 15, the heating range is a continuous straight line 14 in the width direction, and is heated intermittently with a predetermined interval (heating pitch) in the direction perpendicular to the width direction. The heating pitch may be narrowed as shown in FIG. 15A or widened as shown in FIG.

It is possible to suppress warpage that occurs in the width direction of the plate 10 by heating the plate with a gap without heating the entire plate. Further, when the heating temperature is set to a relatively low temperature and the heating pitch is wide, the radius of curvature R1 of the cross section of the molded product by the obtained plate material 10 becomes large. Furthermore, the warp in the width direction of the material 10 becomes larger when the heating temperature is set to a relatively high temperature and the heating pitch is narrowed. Furthermore, the warpage in the width direction of the material 10 increases as the heating temperature is set to a relatively high temperature and the tensile force is increased.

In addition, as shown in FIG. 2, the boundary between the portion 12 that is irradiated by the heating source 4 and becomes high temperature and the portion that is not irradiated at all and remains at a low temperature is outside the part obtained by molding (mold 2). This makes it possible to prevent residual stress generated at the boundary between the high temperature portion and the low temperature portion from remaining in the molded part. After molding, the part portion can be improved in shape accuracy and the residual stress can be reduced by cutting on the irradiation part (heating region, high temperature portion) side from the boundary.

Further, the deformation amount per time due to the movement of the heat source may be suppressed, and the deformation amount may be imparted so as to obtain a target shape by heating the same heating region a plurality of times. As a result, it is possible to prevent uneven distortion from occurring in the direction of movement of the heat source.

As described above, the plate material 10 can be formed into a target shape by setting an appropriate heating region (heating pitch), heating temperature, and tensile force. The heating region (heating pitch), heating temperature, and tensile force are determined by numerical analysis that estimates the curvature of the plate 10 after forming in consideration of preliminary tests or strength change characteristics and thermal expansion characteristics due to heating of the plate 10. Done.

Next, a method for determining the heating pattern will be described.
A case where the heating pitch is changed according to the curvature radius of the target shape will be described. The relationship between the radius of curvature and the irradiation rate is, for example, a graph as shown in FIG. The relationship between the radius of curvature and the irradiation rate can be derived by a preliminary test or numerical analysis. Here, the irradiation rate is determined by the heating radius (L1) and the heating pitch (L) as shown in FIG. That is, the heating radius (L1) is the width of a region that can be uniformly heated by a heating source (diameter in the case of a circle), and the heating pitch (L) is the distance between the irradiation centers (L1 / L). ) Is 1, the entire surface is heated, and when the irradiation rate (L1 / L) is larger than 1, a portion to be heated repeatedly is generated. When the irradiation rate (L1 / L) is smaller than 1, The part which is not heated arises.

As shown in FIG. 12, when the heating temperature is set to a relatively low temperature and the heating pitch is widened to reduce the irradiation rate, the curvature radius in the width direction of the obtained plate member 10 is increased. In the example of FIG. 12, when the target radius of curvature is 600 mm, the target shape can be achieved by setting the heating temperature to 650 ° C. and the irradiation rate to 0.46.

In order to derive the relationship between the radius of curvature after forming and the irradiation rate by numerical analysis, based on the forming conditions such as the set temperature and tensile force, the strength change due to heating of the plate 10 in the set heating region and the plate 10 Calculate thermal expansion. And the curvature radius of the board | plate material 10 obtained by shaping | molding is derived | led-out by calculating the shape change in the whole area | region of the board | plate material 10. FIG. By changing the irradiation rate among the setting conditions, for example, the relationship between the radius of curvature and the irradiation rate as shown in FIG. 12 can be obtained.

Next, the case where the heating temperature is changed according to the radius of curvature of the target shape will be described. The relationship between the radius of curvature and the heating temperature is, for example, a graph as shown in FIG. The relationship between the radius of curvature and the heating temperature can be derived by a preliminary test or numerical analysis. As shown in FIG. 13, the curvature radius R1 of the cross-section of the molded article by the obtained plate member 10 becomes larger when the heating temperature is set to a relatively low temperature. In the example of FIG. 13, when the target radius of curvature is 500 mm, the target shape can be achieved by setting the heating temperature to 680 ° C.

In order to derive the relationship between the radius of curvature after molding and the heating temperature by numerical analysis, the strength change due to heating of the plate 10 at the set heating temperature or the plate 10 based on the molding conditions such as the set heating region and tensile force. The thermal expansion of is calculated. And the curvature radius of the board | plate material 10 obtained by shaping | molding is derived | led-out by calculating the shape change in the whole area | region of the board | plate material 10. FIG. By changing the heating temperature among the set conditions, for example, the relationship between the curvature radius and the heating temperature as shown in FIG. 13 can be obtained.

Also, the case where the tensile load is changed according to the curvature radius R1 of the target shape will be described. The relationship between the curvature radius R1 and the tensile stress is, for example, a graph as shown in FIG. The relationship between the radius of curvature R1 and the tensile stress can be derived by a preliminary test or numerical analysis. As shown in FIG. 14, as the tensile stress is increased, the curvature radius R1 in the width direction of the obtained plate member 10 is increased. In the example of FIG. 14, when the target curvature radius is 500 mm, the target shape can be achieved by setting the tensile stress to 100 MPa.

In order to derive the relationship between the radius of curvature after molding and the tensile stress by numerical analysis, based on the molding conditions such as the set heating region and heating temperature, the strength change due to heating of the plate 10 at the set tensile stress and the plate 10 The thermal expansion of is calculated. And the curvature radius of the board | plate material 10 obtained by shaping | molding is derived | led-out by calculating the shape change in the whole area | region of the board | plate material 10. FIG. By changing the tensile stress among the set conditions, for example, the relationship between the radius of curvature and the tensile stress as shown in FIG. 14 can be obtained.

A determination method when the radius of curvature R1 is not constant will be described.
For example, as shown in FIG. 16, in the case of a mold shape in which the curvature radius R1 is not constant and the curvature radius R1 varies depending on the distance from the mold center, the heating pitch is not fixed, but the mold center. The heating pitch is changed in accordance with the distance from.

FIG. 17 and FIG. 18 are graphs showing the shapes formed according to the heating conditions. 17 indicates the shape when the heating temperature is 650 ° C. and the heating pitch is 70 mm, and the solid line b in FIG. 17 indicates the shape when the heating temperature is 650 ° C. and the heating pitch is 35 mm. 18 indicates the shape when the heating temperature is 600 ° C. and the heating pitch is 35 mm, and the dotted line d in FIG. 18 indicates the shape when the heating temperature is 700 ° C. and the heating pitch is 35 mm. The thin line e indicates the shape when the heating temperature is 650 ° C. and the heating pitch is 35 mm.

From the above, when the heating temperature is 600 ° C. and the heating pitch is 35 mm (solid line c), compared to the target shape (mold shape indicated by the broken line in FIG. 18), there is insufficient bending near the apex after molding. You can see that it happens. Therefore, as shown in FIG. 19, a straight line 15 was added as a heating region, the heating pitch was made fine near the apex, and the thickness was set to 17.5 mm. This is because the heating pitch was made fine to compensate for the lack of plastic deformation. Thus, based on numerical analysis or experimental results, it can be seen that the target molding shape can be obtained as a result of optimizing the molding conditions by changing the heating pitch, heating temperature, etc. according to the radius of curvature.

Next, the case where it is necessary to consider the curvature radius R2 in the width direction of the plate 10 will be described. Depending on the heating conditions, warpage may occur in the width direction of the plate 10. Therefore, a case will be described in which a warp is formed and the shape shown in FIG. 20 is formed. That is, as shown in FIG. 22, when the plate member 10 is heated linearly, the plate member 10 formed as shown by the broken line a in FIG. 24 causes warpage as compared with the mold. On the other hand, as shown in FIG. 23, when the plate member 10 is intermittently heated, warpage of the plate member 10 formed as shown by the solid line b in FIG. 24 can be reduced. In this way, by setting an appropriate interval, it is possible to form the plate member 10 into a shape having no warpage or unevenness in the width direction.

And by heating the board | plate material 10 by providing a heating pitch, heating the board | plate material 10 intermittently as shown in FIG. 23, it may be made to arrange the heating area | region 16 in zigzag form as shown in FIG. Good. By heating with such a heating pattern, molding accuracy can be improved. The interval between the heating regions is changed depending on the width and rigidity of the plate material to adjust the processing accuracy.

Next, the other heating method of the board | plate material by a heating source is demonstrated.
In the above description, the case where the heating source is moved while heating the plate material 10 in a dotted shape (or a circular shape) by the heating source using a light source such as a halogen lamp or a laser has been described. It is not limited to.

For example, a plurality of heating sources may be arranged continuously or intermittently so that a portion necessary for heating can be irradiated at once. FIG. 7 shows a state in which the plate material 10 is heated by a plurality of heating sources 4. As a result, the amount of movement of the heating source can be reduced, the portion necessary for heating can be efficiently or continuously heated, and the plate material can be formed into a target shape.

Also, the amount of heat incident on the plate 10 may be changed by changing the radiation rate on the plate 10 side. For example, when heating using a halogen lamp, a complicated heating pattern can be realized by applying a black body paint to the surface of the plate material and heating it with a constant output by the halogen lamp.

The plate material 10 is a metal member made of titanium or a titanium alloy, and the surface is glossy and has a low emissivity. The emissivity is, for example, 0.3 or less at room temperature. Therefore, the plate 10 has a poor light absorption rate such as a lamp or a laser. However, when a black body paint is applied to the plate member 10, the applied portion has a radiation rate of 0.9 or more, and heat absorption is good. Alternatively, when the plate member 10 is oxidized, the oxidized portion has a radiation rate of about 0.7 and relatively good heat absorption. Therefore, the coating material is applied to the portion to be heated of the plate 10 prior to heating for molding, or is subjected to oxidation treatment, and then the processing portion is heated at a constant speed, so that the heating source 4 described above is used. The plate 10 can be heated. When the material 10 is titanium, the surface is oxidized by heating and the emissivity is changed. Therefore, when an optical heat source is used, stable heating is difficult. By performing the treatment, stable heating becomes possible.

In the above description, the light source is described as being a lamp or various lasers, for example, but the present invention is not limited to this example. For example, as long as the heat input and temperature can be controlled, the plate material may be heated and molded by a flame accompanying the combustion of an arc or gas generally used in welding, a high frequency, or the like. In addition, when shape | molding by these methods, it is desirable to be able to control temperature and to move a heat source.

¡Determining the molding conditions includes a preliminary analysis and a numerical analysis method, which can be executed by an information processing device such as a personal computer. The information processing apparatus, for example, heats a plate by a setting unit that sets a pitch between adjacent lines, a heating temperature for heating the plate, and a tensile force applied to the plate, and a set pitch, heating temperature, and tensile force. Comparing the curvature of the obtained plate material based on the strength change and thermal expansion of the material due to heating of the plate material, the curvature of the molding target and the calculated curvature of the plate material, A determining unit that determines a pitch, a heating temperature, and a tensile force in molding.

According to the numerical analysis, appropriate molding conditions in the above-described plate material forming apparatus can be estimated and determined in advance, and the plate material can be formed with high accuracy.

DESCRIPTION OF SYMBOLS 1 Board | plate material shaping | molding apparatus 2

Mold

3,7 Hydraulic cylinder 4 Heat source 5 Clamp 6 Hinge 10 Board material

Claims

In a state where a tensile force is applied to a plate made of titanium or a titanium alloy, a pressing step of pressing a molded portion of the plate loaded with the tensile force against a mold having a curvature of a molding target;
A heating step of heating at least the molded portion of the plate material continuously or intermittently on a plurality of parallel lines;
The board | plate material shaping | molding method containing.
The plate material molding method according to claim 1, wherein at least the molded portion of the plate material is heated at 500 ° C or higher.
The plate material forming method according to claim 1 or 2, wherein a pitch between adjacent lines in the heating step is a length determined according to a curvature of a forming target of the plate material.
4. The plate material forming method according to claim 1, wherein the heating temperature in the heating step is determined according to a curvature of a forming target of the plate material.
5. The plate material forming method according to claim 1, wherein the tensile force applied in the loading step is determined according to a curvature of a forming target of the plate material.
The plate material according to any one of claims 1 to 5, wherein in the heating step, a movable light source is used as a heat source, and a heating region of the heat source is controlled according to a curvature of a forming target of the plate material. Molding method.
When the clearance gap arises between the said board | plate material and the metal mold | die with heating, the said board | plate material is heated and shape | molded in the state which did not produce a clearance gap between the said board | plate material and the said metal mold | die. The board | plate material shaping | molding method of any one of Claims.
The plate material forming method according to any one of claims 1 to 7, wherein the heat input and the temperature are controlled during heating by changing a radiation rate between a heated region and a non-heated region of the plate material.
The plate material forming method according to any one of claims 1 to 8, wherein a temperature of a portion heated by the plate material is measured by a radiation thermometer.
When the plate material is intermittently heated in the moving direction in the heating step, the heating distance or non-heating distance on one scanning line is a length determined according to the curvature of the forming target of the plate material. Item 10. The plate material forming method according to any one of Items 1 to 9.
The plate material forming method according to any one of claims 1 to 10, wherein in the heating step, the heating unit heats the plate material other than the formed portion.
The plate material forming method according to claim 11, wherein after the forming by the heating step, a non-heated region that is not heated by the heating unit is removed from the plate material.
A load section for applying a tensile force to a plate made of titanium or a titanium alloy;
A pressing portion that presses a molded portion of the plate material loaded with a tensile force against a mold having a molding target curvature; and
A heating unit that heats at least the molded portion of the plate material continuously or intermittently on a plurality of parallel lines;
A plate material forming apparatus.
The plate forming apparatus according to claim 13, wherein the heating unit uses a movable light source as a heating source, and the heating source is controlled in a heating region according to a curvature of a forming target of the plate.
The plate material forming apparatus according to claim 13 or 14, wherein the temperature of the portion heated by the plate material is measured by a radiation thermometer.
A load section for applying a tensile force to a plate made of titanium or a titanium alloy;
A pressing portion that presses a molded portion of the plate material loaded with a tensile force against a mold having a molding target curvature; and
A heating unit that heats at least the molded portion of the plate material continuously or intermittently on a plurality of parallel lines;
A molding condition determining method for a plate material molding apparatus comprising:
A setting step for setting a pitch between adjacent lines, a heating temperature for heating the plate material, and the tensile force applied to the plate material;
A calculation step of calculating the curvature of the plate material obtained when the plate material is heated by the set pitch, the heating temperature, and the tensile force based on the strength change and thermal expansion of the material due to the heating of the plate material;
A determination step of determining the pitch, the heating temperature, and the tensile force in actual plate forming by comparing the curvature of the forming target with the calculated curvature of the plate;
A molding condition determination method for a plate material molding apparatus comprising:
A load section for applying a tensile force to a plate made of titanium or a titanium alloy;
A pressing portion that presses a molded portion of the plate material loaded with a tensile force against a mold having a molding target curvature; and
A heating unit that heats at least the molded portion of the plate material continuously or intermittently on a plurality of parallel lines;
A molding condition determining device for a plate material molding apparatus comprising:
A setting unit for setting a pitch between adjacent lines, a heating temperature for heating the plate material, and the tensile force applied to the plate material;
A calculation unit that calculates the curvature of the plate material obtained when the plate material is heated by the set pitch, the heating temperature, and the tensile force based on a change in strength and thermal expansion of the material due to the heating of the plate material;
A determining unit that compares the curvature of the molding target with the calculated curvature of the plate material and determines the pitch, the heating temperature, and the tensile force in actual plate material molding,
A molding condition determining apparatus for a plate material molding apparatus.