KR102376595B1 - Press-formed product for steel sheet having ultra high strength and manufacturing method thereof - Google Patents

Abstract

An invention relating to a molded product for ultra-high strength steel sheet and a method for manufacturing the same is disclosed. The molded product for ultra-high strength steel sheets of the present invention includes: a body portion formed from an ultra-high strength steel plate, a through-hole portion forming a hole in the body portion, and a molding enhancement portion coupled to the through-hole portion and molded from a material with a greater elongation rate than the body portion. It is characterized by

Description

Molded products for ultra-high strength steel sheets and manufacturing method thereof {PRESS-FORMED PRODUCT FOR STEEL SHEET HAVING ULTRA HIGH STRENGTH AND MANUFACTURING METHOD THEREOF}

The present invention relates to a molded product for ultra-high strength steel sheets and a manufacturing method thereof, and more specifically, to a molded product for ultra-high strength steel sheets and a manufacturing method thereof that can facilitate the forming of ultra-high strength steel sheets even by cold forming.

Generally, ultra-high-strength steel parts produced through the existing hot press forming process are produced in a continuous process in which steel sheets are heat-treated in a heat treatment furnace at 950°C, then formed and cooled in a press at the same time.

This hot forming or hot stamping process requires approximately 5 to 10 billion won worth of equipment per production line, making it difficult to form parts using ultra-high strength steel sheets. Therefore, there is a need to improve this.

The background technology of the present invention is published in Republic of Korea Patent Publication No. 2014-0141222 (published on December 10, 2014, title of the invention: ultra-high strength hot rolled steel sheet and method of manufacturing the same).

The present invention was created to improve the above problems, and the purpose of the present invention is to provide a molded product for ultra-high strength steel sheet and a manufacturing method thereof that can facilitate the forming of ultra-high strength steel sheet even by cold forming.

The molded product for ultra-high strength steel sheets according to the present invention includes: a body part formed from an ultra-high strength steel sheet, a through-hole part forming a hole in the body, and a molding improvement part that is coupled to the through-hole part and is formed of a material with a greater elongation than the body part. It is characterized by

In addition, after the molding of the body portion and the molding of the molding enhancement portion are respectively performed, the molding enhancement portion is inserted and fixed in the through-hole portion.

In addition, the molding enhancement part is cold formed together with the body part while being fixed to the through hole part.

Additionally, the body portion is characterized by having a strength of 1,000 to 2000 MPa or more.

In addition, the position and size of the through hole are set through molding analysis of the body part.

In addition, a plurality of through-hole parts are installed along the boundary where the body part is bent, and the molding enhancement part is made up of a plurality of pieces with different elongation, strength, and thickness, and is inserted and fixed inside the through-hole part.

In addition, with the molding enhancement part inserted inside the through-hole portion, the molding enhancement portion is fixed to the body by welding using a laser.

In addition, the body part is in the shape of a plate, and the forming enhancement part is in the shape of a piece of plate corresponding to the size of the through hole.

In addition, the cross-section of the molding enhancement portion is trapezoidal, and the through-hole portion is characterized by having an inclined surface in contact with the side surface of the molding enhancement portion.

In addition, the thickness of the molding improvement portion is the same as or greater than the depth of the through hole, and the molding enhancement portion is pressed to the inside of the through hole using a press or roller.

The method of manufacturing a molded product for ultra-high strength steel sheet according to the present invention includes: setting the position and area where the through hole is formed in the body through forming analysis, cutting the portion where the through hole is formed in the body, and cutting the body portion where the through hole is formed. It is characterized in that it includes the step of inserting and welding the molding improvement part, which is formed of a material with a greater elongation rate than the part, into the through hole, and the step of cold forming the body part to which the molding improvement part is assembled.

In addition, the body portion is a steel plate with a strength of 1,000 to 2000 MPa or more, and the forming improved portion is a steel plate with a lower strength than the body portion.

In addition, the molding enhancement part is fixed to the through-hole part by welding using a laser.

In addition, the cross-section of the molding enhancement portion is trapezoidal, and the through-hole portion is characterized by having an inclined surface in contact with the side surface of the molding enhancement portion.

In addition, the thickness of the molding improvement portion is the same as or greater than the depth of the through hole, and the molding enhancement portion is pressed to the inside of the through hole using a press or roller.

The method of manufacturing a molded product for ultra-high strength steel sheet according to the present invention includes: setting the position and area where the through hole is formed in the body through forming analysis, cutting the portion where the through hole is formed in the body, and cutting the body portion where the through hole is formed. It is characterized in that it includes the step of cold forming the portion and the step of inserting and welding the molding improvement portion, which is formed of a material with a greater elongation rate than the body portion, into the through hole.

In addition, the molding enhancement part is inserted into the through-hole part in a state in which the molding is completed separately from the body part and is fixed by welding.

The molded product for ultra-high strength steel sheet and its manufacturing method according to the present invention perform cold forming by disposing the forming improvement part in the area where forming is frequently performed and placing the body part using the ultra-high strength steel sheet in the area where forming is not performed, thereby improving the formability of the ultra-high strength steel sheet. can be improved.

In addition, the present invention enables cold forming of ultra-high-strength steel sheets by forming a through-hole in a body formed of an ultra-high-strength steel plate and then fixing the forming improvement part with good formability to the through-hole by welding, thereby reducing production costs. .

Figure 1 is a perspective view schematically showing a molded product for ultra-high strength steel sheet according to an embodiment of the present invention.
Figure 2 is a perspective view showing a body portion according to an embodiment of the present invention.
Figure 3 is a perspective view showing a state in which a through hole is formed in the body according to an embodiment of the present invention.
Figure 4 is a perspective view showing a state in which the molding enhancement part is coupled to the through-hole part according to an embodiment of the present invention.
Figure 5 is a cross-sectional view showing a state before the molding improvement portion is coupled to the through-hole portion according to an embodiment of the present invention.
Figure 6 is a cross-sectional view showing a state in which the molding improvement part is coupled to the through-hole part according to an embodiment of the present invention.
Figures 7 and 8 are cross-sectional views showing a state in which a molding improvement part wider than the through hole is pressed and fixed to the through hole according to an embodiment of the present invention.
Figure 9 is a diagram schematically showing a state in which a press according to an embodiment of the present invention presses the molding enhancement part into the through hole.
Figure 10 is a diagram schematically showing a state in which a roller presses a molding enhancement portion to the inside of a through hole according to an embodiment of the present invention.
Figure 11 is a view showing a state in which a molding enhancement part thicker than the body part is inserted into the through-hole part according to an embodiment of the present invention.
Figure 12 is a diagram illustrating a state in which welding is performed by irradiating a laser vertically while the molding enhancement part according to an embodiment of the present invention is inserted inside the through hole.
Figure 13 is a diagram showing a state in which welding is performed by irradiating a laser obliquely while the molding enhancement part according to an embodiment of the present invention is inserted inside the through hole.
Figure 14 is a flowchart showing a method of manufacturing a molded product for ultra-high strength steel sheet according to an embodiment of the present invention.
Figure 15 is a flowchart showing a method of manufacturing a molded product for ultra-high strength steel sheet according to another embodiment of the present invention.

Hereinafter, a molded product for ultra-high strength steel sheet and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the attached drawings. In this process, the thickness of lines or sizes of components shown in the drawing may be exaggerated for clarity and convenience of explanation.

Additionally, the terms described below are terms defined in consideration of functions in the present invention, and may vary depending on the intention or custom of the user or operator. Therefore, definitions of these terms should be made based on the content throughout this specification.

Figure 1 is a perspective view schematically showing a molded product for ultra-high strength steel sheet according to an embodiment of the present invention, Figure 2 is a perspective view showing a body portion according to an embodiment of the present invention, and Figure 3 is an embodiment of the present invention. It is a perspective view showing a state in which a through hole is formed in the body portion according to , and Figure 4 is a perspective view showing a state in which a molding enhancement part is coupled to the through hole according to an embodiment of the present invention.

As shown in Figures 1 to 4, the molded product 1 for ultra-high strength steel sheet according to an embodiment of the present invention includes a body portion 10 formed of an ultra-high strength steel plate and a hole formed in the body portion 10. It is characterized in that it includes a through-hole portion 20 and a molding improvement portion 30 that is coupled to the through-hole portion 20 and is molded from a material with a greater elongation rate than the body portion 10.

The body portion 10 is formed of ultra-high strength steel plate. The body portion 10 according to one embodiment uses a steel plate having a strength of 1,000 to 2,000 MPa or more, thereby providing improved durability. The body portion 10 uses an ultra-high strength steel plate that has been heat treated to improve strength.

Only the parts that require a lot of formability in the body portion 10 are cut with a laser to form the through-hole portion 20, and then the molding enhancement portion 30 is inserted into the through-hole portion 20 and the body portion (20) is then laser welded. Fix the molding enhancement part (30) to 10).

The through-hole portion 20 can be modified in various ways within the technical idea of forming a hole in the body portion 10. The position and size of the through hole 20 are set through molding analysis of the body portion 10. A plurality of such through-hole portions 20 are installed at the boundary portion where the body portion 10 is bent or at the portion where most forming takes place, and the molding enhancement portion 30 is made up of a plurality of pieces with different elongation, strength, and thickness. It is inserted and fixed inside the study (20). The shape and number of molding enhancement parts 30 correspond to the shape and number of through-hole parts 20.

Since the forming enhancement part 30 is cold formed together with the body part 10 in a press device while being fixed to the through hole part 20, forming of an ultra-high strength steel sheet can be easily performed.

Alternatively, cold forming is performed in a press device with only the through portion 20 formed in the body portion 10, and the molding enhancement portion 30 to be inserted into the through hole 20 is also formed in the press device separately from the body portion 10. After cold forming, the molding enhancement part 30 is inserted and fixed into the formed through hole 20. That is, after the molding of the body portion 10 and the molding enhancement portion 30 are respectively performed, the molding enhancement portion 30 is inserted into the through hole 20 and fixed.

If the hole of the through hole 20 is perforated in the vertical direction and the edge of the molding enhancement portion 30 coupled thereto is also cut in the vertical direction, the molding enhancement portion 30 is inserted into the through hole 20. It is fixed by laser welding.

Figure 5 is a cross-sectional view showing a state before the molding improvement part is coupled to the through-hole according to an embodiment of the present invention, and Figure 6 shows a state of the molding improvement part being coupled to the through-hole according to an embodiment of the present invention. This is a cross-sectional view.

As shown in FIGS. 5 and 6, the cross-section of the molding enhancement portion 30 has a trapezoidal shape, and the through-hole portion 20 has an inclined surface 22 in contact with the side surface of the molding enhancement portion 30. When the upper hole of the through hole 20 is formed large and the lower hole of the through hole 20 is formed small, the inclined surface 22 is installed in a shape that opens upward.

The side surface of the molding enhancement part 30, which has a trapezoidal cross-section, is fixed in contact with the inclined surface 22 of the through-hole part 20. At this time, the section where the inclined surface 22 and the cross section of the molding improvement portion 30 come into contact is called the joint section (A). Since the side of the molding analysis unit and the inside of the through hole 20 are joined while being cut diagonally, processing errors can be compensated to some extent.

Compared to the body portion 10, which uses an ultra-high-strength steel plate, the formability improvement portion 30 is made of a steel plate with lower strength and higher elongation, so the formability can be improved. In addition, the body portion 10 is in the shape of a plate, and the molding enhancement portion 30 is in the shape of a piece of plate corresponding to the size of the through hole 20. Therefore, by installing the forming improvement part 30 only in areas where high formability is required and performing cold forming in a general press equipment, production line installation costs can be reduced and forming of ultra-high strength steel sheets can be facilitated.

Figures 7 and 8 are cross-sectional views showing a state in which a molding improvement part wider than the through hole is pressed and fixed to the through hole according to an embodiment of the present invention.

As shown in Figures 7 and 8, when the left and right width of the molding enhancement portion 31 is larger than the diameter of the hole of the through hole 20, the molding enhancement portion 31 is draped over the through hole 20. There is a method of fixing the molded portion by welding as is, and a method of fixing the molded portion by pressing it using the press 40 or the roller 50.

Figure 9 is a diagram schematically showing a state in which a press according to an embodiment of the present invention presses the molding improvement portion to the inside of the through hole, and Figure 10 is a diagram schematically showing a state in which a roller according to an embodiment of the present invention presses the molding enhancement portion to the inside of the through hole. This is a diagram schematically showing the state of pressing the molding enhancement part.

As shown in Figure 9, when the molding enhancement portion 31 is larger than the through hole 20 and the molding enhancement portion 31 is caught on the upper side of the through hole 20, the molding enhancement portion 31 is used by using the press 40. 31) can be welded after pressurizing. The molding enhancement part 31 pressed by the press 40 is inserted into the through hole 20 and fixed thereto, and then welded. Additionally, since the welding work of the forming enhancement portion 31 can be omitted if necessary, productivity can be improved.

As shown in Figure 10, when the molding enhancement portion 31 is larger than the through hole 20 and the molding enhancement portion 31 is caught on the upper side of the through hole 20, the molding enhancement portion (31) is used using the roller 50. 31) can also be pressurized.

Figure 11 is a view showing a state in which a molding enhancement part thicker than the body part is inserted into the through-hole part according to an embodiment of the present invention.

As shown in Figure 11, when the thickness of the molding enhancement portion 32 is the same as the depth of the through hole 20 or is formed larger than the depth of the through hole 20, the molding enhancement portion 32 is not caught in the set position. Even if this is not possible, one end of the molding enhancement portion 32 is caught inside the through hole 20.

In a state where the molding enhancement portion 32 is hung on the through hole 20, if the molding enhancement portion 32 is flipped 180 degrees along with the body portion 10, the molding enhancement portion 32 is moved to the upper side of the body portion 10. is installed in a protruding shape. In this way, the molding enhancement portion 32 is turned over along with the body portion 10 and the molding enhancement portion 32 is pressed to fix the molding enhancement portion 32 to the inside of the through hole 20. Processing in which the molding enhancement portion 32 is pressed while the molding enhancement portion 32 protrudes toward the upper side of the body portion 10 while the molding enhancement portion 32 protrudes toward the lower side of the body portion 10. The formability is improved compared to other methods.

The molding enhancement portion 32 protruding to the outside of the body portion 10 is pressed to the inside of the through-hole portion 20 using the press 40 or roller 50, so that the molding enhancement portion 32 is coupled to the hollow portion. do.

Figure 12 is a diagram showing a state in which welding is performed by vertically irradiating a laser with the molding enhancement part inserted inside the through hole according to an embodiment of the present invention, and Figure 13 is a diagram showing a state in which welding is performed according to an embodiment of the present invention. This is a diagram showing a state in which welding is performed by irradiating a laser at an angle while the forming enhancement part is inserted inside the through hole.

As shown in FIGS. 12 and 13, with the molding enhancement portion 30 inserted inside the through hole 20, the molding enhancement portion 30 is fixed to the body portion 10 by welding using a laser. do.

At this time, if the irradiation area of the laser beam is wider than the step of the inclined surface 22 of the molding enhancement portion 30 and the through hole 20, the area perpendicular to the boundary between the molding enhancement portion 30 and the through hole 20 Since welding is performed by irradiating a laser beam to the first irradiation area 60, the molding enhancement part 30 can be fixed to the through-hole part 20.

When the irradiation area of the laser beam is smaller than the step of the inclined surface 22 of the molding enhancement part 30 and the through-hole part 20, a second irradiation area ( 65) A laser beam is irradiated. Therefore, a relatively smaller amount of laser than the first irradiation area 60 is irradiated to the second irradiation area 65, so that the molding enhancement part 30 can be fixed to the inside of the through hole 20 by welding.

Hereinafter, a method of manufacturing a molded product 1 for ultra-high strength steel sheet according to an embodiment of the present invention will be described in detail with reference to the attached drawings.

Figure 14 is a flowchart showing a method of manufacturing a molded product for ultra-high strength steel sheet according to an embodiment of the present invention.

As shown in Figure 14, the manufacturing method of the molded product 1 for ultra-high strength steel sheet according to the present invention includes the step of setting the position and area where the through hole 20 is formed in the body 10 through forming analysis. (S10)

When the body portion 10 formed from an ultra-high-strength steel plate is cold worked into a set shape, the parts requiring formability above the set value are predicted through computer simulation. Then, the formation position of the corresponding through-hole portion 20 and the shape and material of the molding enhancement portion 30 to be coupled to the through-hole portion 20 are set.

Then, there is a step of cutting the part of the body 10 where the through hole 20 is formed. (S20) The laser cutter moves in response to a control signal and cuts the body 10, so that the inside of the body 10 is cut. A through hole 20 is formed.

Then, there is a step of assembling the molding improvement part 30, which is made of a material with a greater elongation than the body part 10, by inserting it into the through hole 20 and welding it (S30).

The molding improvement part 30, which is a piece of sheet material with good formability, is inserted into the cut part of the body part 10 and fixed by welding. In general, parts of the body 10 that require a lot of formability are set to less than about 20 to 40% of the total. By replacing only the parts requiring formability with the formability improvement part (30), which is a material with good formability, formability can be increased locally, and in most areas of the molded product (1) for ultra-high strength steel sheet, the rigidity of the ultra-high strength steel sheet is reduced. It can be maintained.

The body portion 10 according to one embodiment is a steel plate having a strength of 1,000 to 2000 MPa or more, and the forming improved portion 30 is a steel plate having a lower strength than the body portion 10. And the molding enhancement part 30 is fixed to the through-hole part 20 by welding using a laser.

On the other hand, when the cross-section of the molding enhancement portion 30 is trapezoidal and the through-hole portion 20 is provided with an inclined surface 22 in contact with the side surface of the molding enhancement portion 30, the molding enhancement portion 30 and the through-hole portion 20 ) increases, so stable bonding can be achieved.

In addition, the thickness of the molding improvement portion 32 is the same as the depth of the through hole 20 or is formed to be larger than the depth of the through hole 20, and the thickness of the through hole 20 is formed using the press 40 or the roller 50. Since the molding enhancement portion 32 is pressed inward to form an interference fit, separate welding work can be omitted.

Then, there is a step of cold forming the body portion 10 on which the molding improvement portion 30 is assembled (S40).

Since the body portion 10 to which the forming improvement portion 30 is combined is cold processed through general press molding, it is possible to easily form ultra-high strength steel sheets without a separate hot press molding device.

The method of manufacturing a molded product 1 for an ultra-high strength steel sheet according to an embodiment may further include the step of first sensing the size of the molding improvement portion 30 and then sensing the hole size of the through-hole portion 20 to make a comparative judgment. You can. If the shapes of the molding enhancement part 30 and the through-hole part 20 are compared and judged to be incorrect, assembly can be stopped to reduce the defective rate of the product.

Figure 15 is a flowchart showing a method of manufacturing a molded product for ultra-high strength steel sheet according to another embodiment of the present invention.

As shown in FIG. 15, the manufacturing method of the molded product 1 for ultra-high strength steel sheet according to another embodiment of the present invention determines the position and area where the through hole 20 is formed in the body 10 through forming analysis. There is a setting step. (S10)

Then, there is a step of cutting the portion of the body 10 where the through hole 20 is formed (S20).

Then, there is a step of cold forming the body portion 10. (S100) The body portion 10 to which the molding improvement portion 30 is not coupled is cold formed, and the forming shape portion is also cold formed separately from the body portion 10. do.

Then, there is a step of inserting the molding enhancement portion 30, which is molded from a material with a greater elongation rate than the body portion 10, into the through-hole portion 20 and assembling it by welding. (S200) That is, the molding enhancement portion 30 is the body portion 10. Separately from (10), when the molding is completed, it is inserted into the through hole 20 and fixed by welding.

As described above, according to the present invention, the forming improvement part 30 is placed in a part where forming is frequently performed, and the body part 10 using ultra-high strength steel sheet is placed in a part where forming is not performed, thereby cold forming the ultra-high strength steel sheet. The formability can be improved. In addition, after forming the through-hole portion 20 in the body portion 10 formed of ultra-high-strength steel plate, the forming improvement portion 30 with good formability is fixed to the through-hole portion 20 by welding to perform cold forming of the ultra-high-strength steel plate. This makes it possible to reduce production costs.

The present invention has been described with reference to the embodiments shown in the drawings, but these are merely illustrative, and those skilled in the art will understand that various modifications and other equivalent embodiments are possible therefrom. will be. Therefore, the true technical protection scope of the present invention should be determined by the scope of the patent claims below.

1: Molded products for ultra-high strength steel sheets
10: body part 20: through hole part
22: Inclined surface 30, 31, 32: Molding improvement part
40: press 50: roller
60: 1st irradiation area 65: 2nd irradiation area
S10: Forming analysis stage
S20: Cutting step
S30: Assembly stage
S40: Forming stage
S100: Forming step
S200: Assembly stage
A: Junction section

Claims (17)

Body formed of ultra-high strength steel plate;
A through-hole portion forming a hole in the body portion; and
A molding enhancement portion coupled to the through-hole portion and molded from a material with a greater elongation rate than the body portion; Includes,
A molded product for an ultra-high strength steel sheet, characterized in that the molding enhancement portion is inserted and fixed into the through hole after the molding of the body portion and the molding enhancement portion are respectively performed.
delete Body formed of ultra-high strength steel plate;
A through-hole portion forming a hole in the body portion; and
A molding enhancement portion coupled to the through-hole portion and molded from a material with a greater elongation rate than the body portion; Includes,
A molded product for an ultra-high strength steel sheet, characterized in that the forming enhancement part is cold formed together with the body part while being fixed to the through hole part.
According to claim 3,
A molded article for ultra-high strength steel sheet, characterized in that the body portion has a strength of 1,000 to 2000 MPa or more.
According to claim 4,
A molded product for ultra-high strength steel sheets, wherein the position and size of the through hole are set through molding analysis of the body portion.
According to claim 4,
The through-hole portion is installed in plural numbers along the boundary portion where the body portion is bent, and the molding enhancement portion is made of a plurality of pieces with different elongation, strength, and thickness, and is inserted into and fixed inside the through-hole portion. Molded products for ultra-high strength steel sheets.
According to claim 6,
A molded product for an ultra-high strength steel sheet, wherein the forming improvement part is fixed to the body by welding using a laser while the forming improvement part is inserted into the through hole.
According to claim 7,
A molded product for ultra-high strength steel sheets, wherein the body portion is in the shape of a plate, and the molding enhancement portion is in the shape of a piece of plate corresponding to the size of the through hole.
In clause 8,
A molded product for ultra-high strength steel sheets, wherein the forming enhancement portion has a trapezoidal shape in cross section, and the through-hole portion has an inclined surface in contact with a side surface of the forming enhancement portion.
According to clause 9,
The thickness of the forming enhancement is the same as the depth of the through-hole or is greater than the depth of the through-hole, and the forming enhancement is pressed into the through-hole using a press or roller. .
Setting the position and area where the through hole is formed in the body through forming analysis;
cutting a portion of the body where the through hole is formed;
Inserting and welding a molding improvement part formed of a material with a greater elongation rate than the body part into the through hole; and
A method of manufacturing a molded product for an ultra-high strength steel sheet, comprising the step of cold forming the body part in which the forming improvement part is assembled.
According to claim 11,
A method of manufacturing a molded product for an ultra-high strength steel sheet, characterized in that the body portion is a steel sheet having a strength of 1,000 to 2000 MPa or more, and the forming improvement portion is a steel sheet having a lower strength than the body portion.
According to claim 11,
A method of manufacturing a molded product for an ultra-high strength steel sheet, characterized in that the forming improvement portion is fixed to the through-hole portion by welding using a laser.
According to claim 11,
A method of manufacturing a molded product for ultra-high strength steel sheet, characterized in that the cross-section of the forming improvement portion is trapezoidal, and the through-hole portion has an inclined surface in contact with a side surface of the forming enhancement portion.
According to claim 14,
The thickness of the forming enhancement is the same as the depth of the through-hole or is greater than the depth of the through-hole, and the forming enhancement is pressed into the through-hole using a press or roller. Manufacturing method.
Setting the position and area where the through hole is formed in the body through forming analysis;
cutting a portion of the body where the through hole is formed;
Cold forming the body portion; and
A method of manufacturing a molded product for an ultra-high strength steel sheet, comprising the step of inserting and welding a molding improvement part formed of a material with a greater elongation rate than the body part into the through hole.
According to claim 16,
A method of manufacturing a molded product for an ultra-high strength steel sheet, characterized in that the forming improvement part is inserted into the through-hole part in a state in which the forming part has been completed separately from the body part and fixed by welding.

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