Patent Description:
Patent document <NUM> describes heating and annealing a portion of a hot stamped article with a laser. Patent document <NUM> describes a method for manufacturing a component having a rigid zone and a soft zone by sandwiching and deforming a heated blank with a die assembly and cooling a first portion of the blank while heating a second portion of the blank with an infrared lamp.

It is desired to be able to efficiently soften regions of any size at any location of the press-molded article formed by hot stamping (also referred to as hot-pressing or the like), cold-pressing, or the like.

The problem is solved by a method according to claim <NUM> and a manufacturing system according to claim <NUM>.

A method for manufacturing a press-molded article according to the present invention includes molding a blank material which is a steel plate into a press-molded article by sandwiching the blank material between a first molding surface and a second molding surface of a die, and press-molding the blank material into a predetermined shape. The method for manufacturing a press-molded article may include irradiating a predetermined portion of the press-molded article with infrared light after removing the press-molded article from the die.

The molding may include press-molding the blank material, which is a heated steel plate, into the predetermined shape by sandwiching the blank material between the first molding surface and the second molding surface of the die, and cooling the blank material with the blank material sandwiched between the first molding surface and the second molding surface, in order to mold the blank material into the press-molded article.

The irradiating includes sandwiching the press-molded article between a first retaining surface and a second retaining surface of a retainer along a shape of the press-molded article, after removing the press-molded article from the die. The irradiating may include irradiating the predetermined portion with infrared light from a first infrared irradiating unit provided in a first recess of the first retaining surface opposed to the predetermined portion of the press-molded article, with the press-molded article sandwiched between the first retaining surface and the second retaining surface.

The first infrared irradiating unit includes a infrared heater.

The infrared heater may be disposed along one surface of the predetermined portion.

The irradiating may include irradiating the predetermined portion with infrared light from a second infrared irradiating unit provided in a second recess of the second retaining surface opposed to the predetermined portion of the press-molded article, with the press-molded article sandwiched in contact with the first retaining surface and the second retaining surface.

The irradiating may include cooling at least surrounding portions of the predetermined portion of the press-molded article, while irradiating the predetermined portion with the infrared light.

The cooling may include cooling at least surrounding portions of the predetermined portion of the press-molded article by delivering a coolant through a flow path provided along at least one of the first retaining surface and the second retaining surface of the retainer.

The predetermined portion may be a portion of the blank material deformed due to press-molding by the die.

The infrared light may be near-infrared light.

A retainer of the claimed manufacturing system includes a first retaining surface along a shape of a press-molded article which is press-molded with a die. The retainer may include a second retaining surface opposed to the first retaining surface. The retainer may include a first infrared irradiating unit provided in a first recess of the first retaining surface opposed to a predetermined portion of the press-molded article. The predetermined portion may be irradiated with infrared light from the first infrared irradiating unit with the press-molded article sandwiched between the first retaining surface and the second retaining surface.

The second retaining surface may have a second recess opposed to the predetermined portion.

The retainer may include a second infrared irradiating unit provided in the second recess for irradiating the predetermined portion with infrared light.

The claimed manufacturing system for a press-molded article according to the present invention may include a die having a first molding surface and a second molding surface opposed to the first molding surface, wherein the die is for molding a blank material which is a steel plate into a press-molded article by sandwiching the blank material between the first molding surface and the second molding surface, and press-molding the blank material into a predetermined shape. The manufacturing system includes the retainer described above for irradiating the predetermined portion of the press-molded article molded by the die with infrared light.

The die may have a flow path for delivering a coolant, provided on at least one of the first molding surface or the second molding surface. The die may mold the blank material, which is a heated steel plate, into the press-molded article by sandwiching the blank material and press-molding the blank material into the predetermined shape, and cooling the blank material with a coolant delivered through the flow path with the blank material sandwiched between the first molding surface and the second molding surface.

The summary clause does not necessarily describe all necessary features of the embodiments of the present invention, which is in any case given by the claims.

Hereinafter, the invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all combinations of the features described in the embodiments are necessarily essential to the solution of the invention.

<FIG> describes a method for manufacturing a press-molded article according to the present embodiment. At the heating step, a blank material <NUM> which is a steel plate is heated to a temperature in an austenite region (for example, a temperature of <NUM> degrees or higher, preferably from <NUM> degrees Celsius to <NUM> degrees Celsius) in a heating furnace <NUM>. The heated blank material <NUM> is removed from the heating furnace <NUM> and is set in a die <NUM>.

At the hot stamping step, the heated blank material <NUM> is cooled until martensitic transformation occurs, while being press-molded using the die <NUM>.

The die <NUM> includes an upper die <NUM> having a molding surface <NUM> and a lower die <NUM> having a molding surface <NUM>. The molding surface <NUM> is an example of a first molding surface. The molding surface <NUM> is an example of a second molding surface. The die <NUM> has a flow path <NUM> for delivering a coolant, such as water, to cool the blank material <NUM>, along the molding surface <NUM> and the molding surface <NUM>. The heated blank material <NUM> is sandwiched between the molding surface <NUM> and the molding surface <NUM> to be press-molded into a predetermined shape. While being press-molded, the blank material <NUM> is cooled by the coolant delivered through the flow path <NUM> with the blank material <NUM> sandwiched between the molding surface <NUM> and the molding surface <NUM>. The blank material <NUM> is molded into a press-molded article <NUM> by the above-mentioned hot stamping step. The press-molded article <NUM> has strength of <NUM> GPa to <NUM> GPa, for example.

Then, at the tempering step or the annealing step, the press-molded article <NUM> removed from the die <NUM> is set into a retainer <NUM> and a predetermined portion <NUM> of the press-molded article <NUM> is irradiated with infrared light. In this way, the predetermined portion <NUM> is softened. That is, the predetermined portion <NUM> of the press-molded article <NUM> is subject to tempering or annealing, by irradiating the predetermined portion <NUM> of the press-molded article <NUM> with infrared light.

The retainer <NUM> includes an upper die <NUM> having a retaining surface <NUM> along the shape of one surface of the press-molded article <NUM>, and a lower die <NUM> having a retaining surface <NUM> along the shape of the other surface on the opposite side of said one surface of the press-molded article <NUM>. The retainer <NUM> has a flow path <NUM> for delivering a coolant, such as water, to cool the press-molded article <NUM>, along the retaining surface <NUM> and the retaining surface <NUM>. The retainer <NUM> has a recess <NUM> and a recess <NUM> in regions of the retaining surface <NUM> and the retaining surface <NUM> opposed to the portion <NUM> of the press-molded article <NUM>. The recess <NUM> and the recess <NUM> are examples of a first recess and a second recess. The recess <NUM> and the recess <NUM> may be grooves provided on the retaining surface <NUM> and the retaining surface <NUM>. Note that, the retainer <NUM> may not have the flow path <NUM>.

An infrared heater <NUM> for irradiating the portion <NUM> of the press-molded article <NUM> with infrared light is provided in the recess <NUM> of the upper die <NUM>. The infrared heater <NUM> is an example of a first infrared irradiating unit. The infrared heater <NUM> may irradiate the portion <NUM> of the press-molded article <NUM> with near-infrared light. The retainer <NUM> may have an infrared lamp instead of the infrared heater. The retainer <NUM> may have a plurality of infrared heaters disposed along the portion <NUM>. The retainer <NUM> may have a plurality of infrared lamps arranged along the portion <NUM>. The near-infrared light may be electromagnetic waves with a wavelength of <NUM> to <NUM> micrometers. The width of the recess <NUM> may be a width corresponding to the width of the portion <NUM>. The recess <NUM> may function as a shielding wall for shielding infrared light to prevent portions other than the portion <NUM> of the press-molded article <NUM> from being irradiated with the infrared light irradiated from the infrared heater <NUM>. In addition, by providing the recess <NUM>, the air inside the recess <NUM> functions as a heat insulation layer to suppress heat radiation through the lower die <NUM> of the heat in the portion <NUM> of the press-molded article <NUM> heated by the infrared light from the infrared heater <NUM>.

The retainer <NUM> may also have an infrared heater in the recess <NUM> to heat the portion <NUM> of the press-molded article <NUM> from both sides. The infrared heater provided in the recess <NUM> is an example of a second infrared irradiating unit.

For example, the press-molded article <NUM> is an automobile frame component or the like. The automobile frame component may be softened by partially reducing its strength. In this way, in case of a motor vehicle collision, the softened portion can deform and absorb the collision energy. By partially softening the press-molded article <NUM> as described above, the safety of passengers on the motor vehicle can be ensured.

The wavelength range of the infrared light irradiated by the infrared heater <NUM> is wider than the wavelength range of a laser light irradiated by a laser as in Patent document <NUM>. Therefore, the portion <NUM> to be softened of the press-molded article <NUM> can be irradiated with light having various wavelengths. As such, the absorption of light with which the portion <NUM> of the press-molded article <NUM> is irradiated can be facilitated. That is, the portion <NUM> of the press-molded article <NUM> can be efficiently heated and softened. The laser light is irradiated locally. On the other hand, infrared light irradiated by the infrared heater <NUM> is irradiated over a wide range. Therefore, the productivity of softening process of the portion <NUM> of the press-molded article <NUM> can be improved.

In addition, the portion <NUM> is heated by irradiating with infrared light from the infrared heater <NUM>, with the press-molded article <NUM> sandwiched between the retaining surface <NUM> of the upper die <NUM> and the retaining surface <NUM> of the lower die <NUM>. In this way, the portion <NUM> of the press-molded article <NUM> can be accurately softened while suppressing deformation of the press-molded article <NUM>. Deformation of the press-molded article <NUM> can be further suppressed and the portion <NUM> of the press-molded article <NUM> can be more accurately softened by heating the portion <NUM> by irradiating the portion <NUM> with infrared light from the infrared heater <NUM> while cooling portions other than the portion <NUM> to be softened of the press-molded article <NUM>, with the press-molded article <NUM> sandwiched between the retaining surface <NUM> of the upper die <NUM> and the retaining surface <NUM> of the lower die <NUM>.

Deformation due to heat by infrared irradiation can be more certainly suppressed by irradiating the entire press-molded article <NUM> with infrared light, with the entire press-molded article sandwiched between the retaining surface <NUM> of the upper die <NUM> and the retaining surface <NUM> of the lower die <NUM>.

Moreover, portions other than the portion <NUM> of the press-molded article <NUM> is cooled by a coolant delivered through the flow path <NUM>, while the portion <NUM> of the press-molded article <NUM> is irradiated with infrared light. In this way, the transition width of the hardness at a boundary portion between the portion <NUM> to be softened and other portions whose hardness are to be maintained may be narrowed.

Note that, in the present embodiment, an example is shown in which the entire portion other than the portion <NUM> of the press-molded article <NUM> is cooled. However, instead of the entire portion other than the portion <NUM> of the press-molded article <NUM>, only portions around the portion <NUM> of the press-molded article <NUM> may be cooled. In addition, the press-molded article <NUM> may not be cooled while being irradiated with infrared light.

In addition, as described in Patent document <NUM>, when infrared light is irradiated at the hot stamping step, portions that can be irradiated with infrared light is limited to flat portions that are not deformed by press-molding. That is, when infrared light is irradiated at the hot stamping step, the portions deformed by press-molding cannot be softened. In addition, when a steel plate heated to a temperature in an austenite region or higher is rapidly cooled and partially heated at the same time, the position of the portion to be softened shifts by the amount of contraction of the steel plate upon rapid cooling. Due to such shift in the position, the stability of the shape of the press-molded article becomes lower, and the transition width of the hardness at the boundary portion between the portion to be softened and the portion not to be softened becomes wider.

As described above, according to the present embodiment, regions of any size at any location of the press-molded article can be efficiently softened.

<FIG> describes another example of a retainer used in the tempering step or the annealing step. The retainer <NUM> has an infrared irradiating function and a cooling function. The retainer <NUM> includes an upper die <NUM> having a retaining surface <NUM> with a shape along one surface of the press-molded article <NUM>, and a lower die <NUM> having a retaining surface <NUM> with a shape along the other surface of the press-molded article <NUM>. The upper die <NUM> has a recess <NUM> in a region opposed to the portion <NUM> to be softened of the press-molded article <NUM>. An infrared heater <NUM> for irradiating infrared light from the side of one surface of the portion <NUM> is provided in the recess <NUM>. Similarly, the lower die <NUM> has a recess <NUM> in a region opposed to the portion <NUM> to be softened of the press-molded article <NUM>. An infrared heater <NUM> for irradiating infrared from the side of the other surface of the portion <NUM> is provided in the recess <NUM>. The upper die <NUM> and the lower die <NUM> have a flow path <NUM> for delivering a coolant, along the retaining surface <NUM> and the retaining surface <NUM>.

The infrared heater <NUM> and the infrared heater <NUM> can be deformed into any shape and disposed. Therefore, as shown in <FIG>, the portion <NUM> to be softened of the press-molded article <NUM> can be heated using the infrared heater <NUM> and the infrared heater <NUM>, even when the portion is a portion along a hat-shaped cross section. By adjusting the number and thickness of the infrared heaters, the portion <NUM> to be softened can be heated at a time, without restriction on the size of the portion's area. Even when the portions <NUM> to be softened are scattered, the portions can be heated at a time. The press-molded article <NUM> is sandwiched between the retaining surface <NUM> of the upper die <NUM> and the retaining surface <NUM> of the lower die <NUM>, while being heated with the infrared heaters <NUM> and <NUM>. Therefore, deformation of the press-molded article <NUM> due to heating can be further certainly suppressed.

<FIG> describes another example of a retainer used in the tempering step or the annealing step. The retainer <NUM> has an infrared irradiating function and a cooling function. The retainer <NUM> includes an upper die <NUM> having a retaining surface <NUM> with a shape along one surface of the press-molded article <NUM>, and a lower die <NUM> having a retaining surface <NUM> with a shape along the other surface of the press-molded article <NUM>. The upper die <NUM> has a recess <NUM> in a region opposed to the portion <NUM> to be softened of the press-molded article <NUM>. An infrared heater <NUM> for irradiating infrared light from the side of one surface of the portion <NUM> is provided in the recess <NUM>. Similarly, the lower die <NUM> has a recess <NUM> in a region opposed to the portion <NUM> to be softened of the press-molded article <NUM>. An infrared heater <NUM> for irradiating infrared from the side of the other surface of the portion <NUM> is provided in the recess <NUM>. The upper die <NUM> and the lower die <NUM> have a flow path <NUM> along the retaining surface <NUM> and the retaining surface <NUM> for delivering a coolant. Note that, at least one of the upper die <NUM> and the lower die <NUM> may not have the flow path <NUM>.

The infrared heater <NUM> and the infrared heater <NUM> can be disposed at any place on the retaining surface <NUM> and the retaining surface <NUM>. For example, as shown in <FIG>, the infrared heater <NUM> and the infrared heater <NUM> can also be disposed at a place opposed to the portion deformed by press-molding during the hot stamping step.

As described above, according to the present embodiment, regions of any size at any location of the press-molded article <NUM> can be further efficiently softened with infrared light, at the tempering step or the annealing step after the press-molding step.

Note that, in the above-mentioned embodiment, an example has been described in which a region of any size at any location of the press-molded article <NUM> is irradiated with infrared light at the tempering step or the annealing step after the hot stamping step. However, the press-molded article to be tempered or annealed with infrared irradiation is not limited to a press-molded article formed by hot stamping. For example, the press-molded article to be tempered or annealed with infrared irradiation may be a press-molded article formed by cold-pressing a steel material such as a high strength material.

While the embodiments of the present invention have been described, the technical scope of the invention is not limited to the above described embodiments. It is apparent to persons skilled in the art that various alterations and improvements can be added to the above-described embodiments. It is also apparent from the scope of the claims that the embodiments added with such alterations or improvements can be included in the technical scope of the invention.

Claim 1:
A method for manufacturing a press-molded article (<NUM>), comprising
molding a blank material (<NUM>) which is a steel plate into a press-molded article (<NUM>) by sandwiching the blank material (<NUM>) between a first molding surface (<NUM>) and a second molding surface (<NUM>) of a die (<NUM>), and press-molding the blank material (<NUM>) into a predetermined shape; wherein the method comprises
irradiating a predetermined portion of the press-molded article (<NUM>) with infrared light after removing the press-molded article (<NUM>) from the die (<NUM>), wherein the irradiating comprises:
sandwiching the press-molded article (<NUM>) in contact with a first retaining surface (<NUM>, <NUM>, <NUM>) and a second retaining surface (<NUM>, <NUM>, <NUM>) of a retainer (<NUM>, <NUM>, <NUM>) along a shape of the press-molded article (<NUM>), after removing the press-molded article (<NUM>) from the die (<NUM>); and
irradiating the predetermined portion with infrared light from a first infrared irradiating unit (<NUM>, <NUM>, <NUM>) provided in a first recess (<NUM>, <NUM>, <NUM>) of the first retaining surface (<NUM>, <NUM>, <NUM>) opposed to the predetermined portion of the press-molded article (<NUM>), with the press-molded article (<NUM>) sandwiched in contact with the first retaining surface (<NUM>, <NUM>, <NUM>) and the second retaining surface (<NUM>, <NUM>, <NUM>),
the first infrared irradiating unit (<NUM>, <NUM>, <NUM>) includes an infrared heater (<NUM>, <NUM>, <NUM>), and
the predetermined portion includes a bent portion with a shape deformed by press-molding.