KR20200067280A - Hot stamping method - Google Patents

Abstract

Provided in the present invention is a hot stamping method, which comprises: a mold designing and mold fabricating step of designing and fabricating a cold-forming mold which cold-forms a blank supplied to manufacture a product; a cold-forming step of inserting the blank into the fabricated cold-forming mold to shape the same into a temporary product having a shape of a product to be fabricated; a mold trimming step of inserting the temporary product shaped by means of the cold forming into a fabricated mold trim to be trimmed; a heating step of heating the temporary product trimmed in the mold trim at a high temperature in a heating furnace; and a thermal treatment step of performing thermal treatment while cooling the temporary product after inserting the temporary product which has undergone the heating step into a press mold. Therefore, because a product can be trimmed before the thermal treatment which changes a raw material into a super high tensile steel, the product can be smoothly cut. Furthermore, a harmful gas which is generated when the super high tensile steel is cut can be prevented. In addition, processing time can be shortened to improve the productivity of the product.

Description

Hot stamping method

The present invention relates to a hot stamping method, and more specifically, if the rigidity is insufficient in the event of a vehicle accident, a center pillar or rail roof, which is a component directly connected to human injury, is used as an ultra-high tensile steel using a blank. It relates to a hot stamping method that can perform heat treatment while forming.

Recently, the trend of technological development in the automotive industry has led to the reduction in body weight for low carbon emission and energy efficiency, and the representative technologies are carbon fiber reinforced plastic (CFRP) material technology and hot stamping method technology. There is this.

Among these, the hot stamping method technology is a general method by forming a tensile strength of a material from 600 MPa to 1470 MPa or higher by heat-treating a steel material heated to a high temperature of 950°C into a mold and then rapidly cooling it in a mold to heat it. It is a technology that can have the same strength performance with less weight than steel materials.

The advantages of the hot stamping method are that the raw materials can be made of ultra-high strength steel, can be processed into complex shapes, and have excellent dimensional accuracy. In addition, due to the weight reduction effect of the vehicle body, the area where hot stamping technology is applied to the vehicle body is gradually increasing worldwide.

This conventional hot stamping method is performed in the order of heating, hot forming, and laser cutting, and the existing hot stamping method requires expensive auxiliary facilities, problems of low productivity due to long fixing time, and laser cutting process after hot forming. Accordingly, as a product made of ultra-high-strength steel is cut using a laser, cutting of the ultra-high-strength steel product does not proceed smoothly, and a problem occurs in that harmful gas is generated when cutting.

The background technology of the present invention is disclosed in Korean Patent Registration No. 10-1581940 (December 31, 2015 announcement).

The present invention was created to solve the problems as described above, and excludes the laser cutting process of cutting the heat-treated product and trims the temporary product before the heating step after the cold forming step to trim the product to proceed smoothly. The purpose is to provide a stamping method that can prevent the generation of gas.

In order to achieve the above object, the present invention is a mold design and mold manufacturing step of designing and manufacturing a cold forming mold for cold forming a blank supplied to produce a product; Cold forming step of molding the blank into a manufactured product having a shape of a product to be produced after inputting the blank into the produced cold forming mold; A mold trim step of trimming by inserting the molded product through the cold molding into a mold trim produced; A heating step of heating the trimmed appliance from the mold trim to a high temperature in a heating furnace; And it provides a hot stamping method comprising a heat treatment step of heat-treating while cooling the appliance by putting the appliance that has undergone the heating step into a press mold.

In the hot stamping method according to the present invention, the mold design and the mold manufacturing step may be performed when the mold design step is completed, and the mold design step may form a 2D blank into a 3D temporary product. Cold forming prediction step for predicting the amount of blanks required at the time, and spring back analysis step for analyzing the spring bag of the temporary product generated after the cold forming step, and the cold product of the temporary product generated after the cold forming step A molding surface shape error analysis step of analyzing the thickness reduction of the corner round portion may be included, and in the molding surface shape error analysis step, the thickness reduction of the corner round portion of the temporary product may use a molding surface error data map.

The mold design step may further include an inspection step of inspecting the strength and quality of a product manufactured after sequentially passing through the cold forming step, the mold trim step, the heating step, and the heat treatment step.

The mold designing step may further include a database storage step of making the database of the modified contents when manufacturing the final cold forming mold, the mold trim and the cold forming mold, and the mold trim that have passed the inspection step.

In addition, the hot stamping method according to the present invention may further include a mold trim design and a mold trim manufacturing step of designing and manufacturing a mold trimming a temporary product manufactured through the cold forming step, and the mold trim design and mold The trim production step may be performed after the mold design and mold manufacturing step and before the mold trim step.

In the mold trim design and the mold trim manufacturing step, a mold trim manufacturing step may be performed when the mold trim design step is completed, and the mold trim design step is hot to predict the amount of the trimmed appliances expanded when heated in a heating furnace. Prediction of molding, thermal expansion analysis step for predicting the amount of the heated temporary product shrinks when heat-treated in the press mold, and predicting the amount of shrinking of the corner round part of the temporary product when the heated temporary product heats up in the press mold It may include a step for analyzing the shape error of the curved surface.

The hot forming prediction step and the thermal expansion analysis step may predict the amount of expansion and contraction of the temporary product using palm stamp software, and the amount of contraction of the corner round portion of the temporary product in the curve surface shape error analysis step may be a curved surface. You can use the error date map.

The hot stamping method according to the present invention can smoothly advance the cutting of the product by trimming before heat treatment to change the raw material to ultra-high tensile steel, can block harmful gases generated when cutting the ultra-high tensile steel, and shorten the process time To improve the productivity of the product.

1 is a flowchart schematically showing a hot stamping method according to an embodiment of the present invention.
FIG. 2 is a view schematically showing the sequence of the mold design step of the mold design and mold manufacturing step shown in FIG. 1.
FIG. 3 is a view schematically showing a sequence of a mold trim design step of the mold trim design and mold trim manufacturing step shown in FIG. 1.
4 and 5 are views schematically showing the procedure of the hot stamping method shown in FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to ordinary or lexical meanings, and the inventor appropriately explains the concept of terms in order to explain his or her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

Referring to Figure 1, the hot stamping method according to an embodiment of the present invention is a mold design and mold manufacturing step (S100), cold forming step (S200), mold trim step (S300), heating step (S400) and , It includes a heat treatment step (S500), may further include a mold trim design and mold trim manufacturing step (S600).

In the mold design and mold manufacturing step (S100), the blank 10 supplied to manufacture a center pillar or rail roof, which is a part of a vehicle, is cold formed into a temporary product having a shape of a part. After the cold forming mold 20 is designed, it is a step of manufacturing the designed cold forming mold 20.

1, 2, 4 and 5, the mold design and mold manufacturing step (S100) includes a mold design step (S120) and mold manufacturing step 140, the mold design step (S120) When is completed, the mold manufacturing step (S140) proceeds.

The mold design step (S120) includes a cold forming prediction step (S121), a spring back analysis step (S122), a molding surface shape error analysis step (123), an inspection step (S124), and a database storage step (S125). It may further include.

The cold forming prediction step (S121) is a step of predicting the amount of the blank 10 required when molding a blank product, which is a 2D-type raw material, into a 3D-type temporary product, and the cold forming prediction step (S121). Estimates the approximate amount of the blank 10 required when molding with a 3D-type temporary product.

The spring back analysis step (S122) is a step of analyzing the spring back phenomenon of the cold-formed home appliance through the cold forming step (S200) described below. Here, the spring back phenomenon refers to a phenomenon in which a material is bent in a bending process of a plastic material and then removed to remove pressure, and the spring back analysis step (S122) means that a 3D-shaped molded appliance is 2D. It is a step of analyzing the amount that is deformed in order to return to the original shape, and it is preferable to analyze the springback of the home appliance using "Autoform" or "Pamstamp2g", and the program "Autoform" that analyzes the springback of the home appliance Or "Pamstamp2g" is a program widely used in the field, and detailed description thereof will be omitted.

The shaping surface shape error analysis step (S123) is a step of analyzing the amount of reduction in the thickness of the corner round portion of the cold-formed appliance after passing through the cold shaping step (S200) described later, and the shaping surface shape error analysis step In (S123), it is preferable to use a molding surface error data map to reduce the thickness of the corner round portion of the temporary product.

The inspection step (S124) is a step of inspecting the strength and quality of a product manufactured after sequentially passing through a cold forming step (S200), a mold trim step (S300), a heating step (S400), and a heat treatment step (S500), which will be described later. It is preferable to inspect the products manufactured through the cold forming step (S200), the mold trimming step (S300), the heating step (S400), and the heat treatment step (S500) sequentially, It is preferable to correct the cooling channel (not shown) of the press mold 50 performing the heat treatment step (S500) when predicting the strength and quality of the manufactured product, and when the result of the predicted strength and quality is lower than the expected value.

When the inspection step (S124) of the mold design step (S120) is completed, the final cold forming mold 20, the mold trim 30 and the cold forming mold 20 and the mold trim (which have passed the inspection step (S124)) 30) It is preferable to perform a database storage step (S125) in which the modified contents are databased at the time of production.

1 and 5, after the mold design and mold manufacturing step (S100) of designing and manufacturing the cold forming mold 20, and then introducing the blank 10 into the produced cold forming mold 20 Cold forming step (S200) of molding into a temporary product having a shape of a product to be produced is performed.

While passing through the cold forming step (S200), the blank 10, which is a raw material having a 2D shape, is molded into a 3D shape of the home appliance, and the home appliance molded through the cold molding step (S200) is a mold trim step (S300). ).

The mold trim step (S300) is a step of cutting and trimming the molded appliance by inserting it into a mold trim 30 previously manufactured. It is possible to uniformly carry out the cutting and trimming work by cutting and trimming the molded appliance by inserting the molded appliance into the mold trim 30, and to prevent the generation of harmful gas by cutting and trimming the appliance that has not been heat treated. do.

The home appliance that has undergone the mold trimming step (S300) is supplied to the heating furnace 40 and then heated to a high temperature (S400). The heating step (S400) is a step of heating the home appliances supplied to the interior of the heating furnace 40, and heating the supplied home appliances to a temperature of 930° C. for 250 seconds to thereby bring the home appliances into the heating furnace 40. To expand locally.

The temporary product subjected to the heating step (S400) is subjected to a heat treatment step (S500). The heat treatment step (S500) is a step of shrinking the locally expanded appliance by cooling the appliance after passing the heating appliance (S400) into a press mold (50).

In the heat treatment step (S500), the temporary product is locally contracted by cooling it in the press mold 50 for 15 seconds, and the temporary product having a strength of 540 MPa is subjected to 1500 MPa by passing through the heat treatment step (S500). It is changed to have.

It is preferable to perform a mold trim design and manufacturing step (S600) of designing and manufacturing a mold trimming a temporary product manufactured through the cold forming step (S200), wherein the mold trim design and manufacturing step (S600) is the It is preferable to proceed before the mold design step (S300) after the mold design and mold production step (S100).

1 and 3, the mold trim design and manufacturing step (S600) includes a mold trim design step (S620) and a mold trim manufacturing step (S640), and when the mold trim design step (S620) is completed The mold trim production step (S640) proceeds.

3 and 4, the mold trim design step (S620) includes a hot forming prediction step (S621 ), a thermal expansion analysis step (S622 ), and a curve surface shape error analysis step (S623 ). The hot forming prediction step (S621) is a step of predicting the amount of expansion of the appliance that has undergone the mold trimming step (S300) when heated in the heating furnace 40, and the thermal expansion analysis step (S622) is the heating furnace. This is a step of predicting the amount of the provisional product heated at (40) shrinking during heat treatment in the press mold (50).

In the hot forming prediction step (S621) and the thermal expansion analysis step (S622), it is preferable to predict the amount of expansion and contraction of a household product using palm stamp software, and the palm stamp software is widely used in the field. In detail, detailed description thereof will be omitted.

The curve surface shape error analysis step (S623) is a step for predicting the amount of the corner round portion of the temporary product contracted when the temporary product heated in the heating furnace 40 is heat-treated in the press mold 50. In the curve surface shape error analysis step (S623), it is preferable to use a curve surface error date map for the amount of the corner round portion of the appliance to be contracted, and detailed description thereof will be omitted. .

Referring to FIG. 1, the blank 10 is subjected to a cold forming step (S200) in which a cold molding is performed with a cold appliance by being put into a cold forming mold 20 manufactured through a mold design and a mold manufacturing step (S100), The blank 10 is cold formed in the cold forming mold 20 for 3 seconds, and the manufactured product that has been subjected to the cold molding with the blank 10 has a strength of 540 MPa.

The temporary product subjected to the cold forming step (S200) performs a mold trim step (S300), and when the temporary product is put into the mold trim 30, cutting and trimming are performed by the mold trim 30 for 3 seconds. It will perform.

After the mold trim step (S300), the temporary product is subjected to a heating step (S400) that is heated in the heating furnace 40, and the temporary product that has undergone the heating step (S400) is cooled in a press mold (50). After going through the heat treatment step (S500) it will be made of ultra-high tensile steel products.

Therefore, by trimming the raw material before heat treatment to change it into ultra-high-strength steel, the product can be cut smoothly, harmful gases generated when cutting the ultra-high-strength steel can be cut off, and the process time is shortened to improve the productivity of the product. I can do it.

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

10: blank 20: cold forming mold
30: mold trim 40: heating furnace
50: press mold

Claims (8)

A mold design and mold manufacturing step of designing and manufacturing a cold forming mold for cold forming a blank supplied to manufacture a product;
Cold forming step of molding the blank into a manufactured product having a shape of a product to be produced after inputting the blank into the produced cold forming mold;
A mold trim step of trimming by inserting the molded product through the cold molding into a mold trim produced;
A heating step of heating the trimmed appliance from the mold trim to a high temperature in a heating furnace; And
A hot stamping method comprising the step of heat-treating the coolant by cooling the appliance by putting the appliance that has undergone the heating step into a press mold.
The method according to claim 1,
In the mold design and mold manufacturing step, when the mold design step is completed, the mold manufacturing step proceeds,
The mold design step,
Cold forming prediction step for predicting the amount of blanks required when forming a 2D blank into a 3D temporary product,
A spring bag analysis step of analyzing a spring bag of a temporary product generated after the cold forming step,
Hot stamping method comprising the step of analyzing the shape of the shape error to analyze the thickness reduction of the corner round portion of the temporary product generated after the cold forming step.
The method according to claim 2,
Hot stamping method, characterized in that using the molding surface error data map to reduce the thickness of the corner round portion of the temporary product in the shape surface shape error analysis step.
The method according to claim 2,
The mold design step,
A hot stamping method further comprising an inspection step of inspecting the strength and quality of the manufactured product after sequentially passing through the cold forming step, the mold trim step, the heating step, and the heat treatment step.
The method according to claim 4,
The mold design step,
A hot stamping method further comprising a database storage step of database of the modified contents when the final cold forming mold, the mold trim and the cold forming mold, and the mold trim that have passed the inspection step are manufactured.
The method according to claim 1,
It further includes a mold trim design and mold trim production step of designing and manufacturing a mold trimming a temporary product manufactured through the cold forming step,
The mold trim design and mold trim production steps,
Hot stamping method characterized in that it proceeds before the mold trim step after the mold design and mold manufacturing step.
The method according to claim 6,
In the mold trim design and mold trim manufacturing step, when the mold trim design step is completed, the mold trim manufacturing step proceeds,
The mold trim design step,
Hot forming prediction step for predicting the amount of the trimmed appliances expand when heated in a heating furnace,
Thermal expansion analysis step for predicting the amount of the heated appliance shrinks during heat treatment in a press mold,
A hot stamping method comprising a step of analyzing a curved surface shape error for predicting an amount of shrinkage of a corner round portion of a temporary product when the heated temporary product is heat-treated in a press mold.
The method according to claim 7,
The hot forming prediction step and the thermal expansion analysis step predict the amount of expansion and contraction of the home appliance using palm stamp software,
The hot stamping method characterized in that the amount of the corner round portion of the temporary product contracted in the curve surface shape error analysis step uses a curve surface error date map.

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