KR20180000663A - Impact Beam And Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to a method of manufacturing an impact beam, and more particularly, to a method of manufacturing an impact beam for a vehicle capable of entirely improving straightness and elongation, and preventing deterioration of physical properties at both ends which are a bracket joint. To this end, the present invention includes a heating step and a cooling and calibration step.

Description

[0001] The present invention relates to an impact beam manufacturing method,

The present invention relates to a method of manufacturing an impact beam, and more particularly, to a method of manufacturing an impact beam for a vehicle in which straightness and elongation as a whole are improved and property deterioration does not occur at both ends of a bracket joint portion.

Generally, a reinforcing member called an impact beam is installed inside a door of a vehicle in order to minimize deformation damage of the vehicle body and damage to the occupant when the vehicle collides.

Here, the impact beam is installed between the inside and outside panels of the door in a lateral direction, and the metal plate is formed into a hollow tube having a circular cross section so as to have a good impact resistance and shock absorbing property without causing weight increase of the car body. Molding, heat treatment and other necessary processing.

At this time, when the elongation of the impact beam is low, brittle fracture can cause serious injury to the occupant during a collision. When the straightness of the impact beam is low, it is difficult to mount the impact beam stably in the space between the panels It can be easily deformed by impact.

Therefore, the impact beam is used by improving the mechanical properties such as strength and elongation through quenching which is quenched after being heated at a high temperature and tempering which removes residual stress by heating at a middle temperature.

However, in the related art, a large amount of bending deformation has occurred due to a rapid temperature change in the process of quenching the impact beam, and a separate calibration process is required to improve the straightness of the bending deformation of the impact beam, The productivity of the product is deteriorated.

In addition, since it is difficult for each part of the heated impact beam to be uniformly cooled, the internal structure becomes nonuniform, and internal defects or residual stresses are often excessive, so that there is a problem that a large deformation or breakage of cracks occurs in a subsequent processing step such as welding there was.

Prior Art 1 (Korean Registered Patent No. 10-1258766, entitled " High Strength Hot-Formed Door Beam Manufacturing Method with Tensile Strength of 1800 MPa ", Registered on Apr. 23, 2013) is used to heat a steel pipe and heat the steel pipe by an impact beam And cooling it by quenching by a water channel formed in the mold. In the prior art 1 described above, the cooling water is not uniformly supplied to the steel pipe due to the cooling by the water channel provided in the metal mold, so that uneven cooling is performed and the overall elongation rate is lowered.

Particularly in the case of both ends of the steel pipe, since the supply of cooling water is not smooth as compared with the body portion of the steel pipe, the impact beam produced by the same method as in the prior art 1 has a problem of being broken near both ends.

On the other hand, in the prior art 2 (Korean Patent Registration No. 10-0994646, " High Strength Automobile Door Stiffener, Method for Manufacturing the Same and Method for Mounting the Same ", Registered on November 11, 2010), a steel pipe having a cut- Is transferred to a press die and rapidly cooled in a press die. As in the prior art 2, the cooling water is not uniformly supplied to the steel pipe due to the cooling by the water channel and the like provided in the mold, so that uneven cooling is performed, and the overall elongation is lowered. Particularly, in the case of both ends of the steel pipe, the supply of the cooling water is not smooth as compared with the body portion of the steel pipe, so that the impact beam produced by the same method as in the prior art 2 has a problem of being broken near both ends.

Korean Registered Patent No. 10-1258766, " Method of manufacturing a high-strength hot-formed door beam having a tensile strength of 1800 MPa " Korean Registered Patent No. 10-0994646, " High Strength Automobile Door Stiffener, Method for Manufacturing the Same, and Method for Installing the Same ", 2010.11.10

It is an object of the present invention to provide a method of manufacturing an impact beam for a vehicle which has improved straightness and elongation as a whole and which does not cause deterioration of properties at both ends of a bracket joint portion.

According to an aspect of the present invention, there is provided a method of manufacturing an impact beam, the method comprising: a heating step of heating a steel pipe to 800 ° C to 950 ° C to change a texture of the material into austenite; And a cooling / calibrating step of performing quenching by calibrating and water-cooling the steel pipe heated in the heating step, wherein cooling / quenching by water cooling is performed for a period including part or all of the period during which the steel pipe is calibrated At the same time, a method of manufacturing an impact beam.

In the present invention, the calibration in the cooling / calibrating step is performed by at least one roller disposed under the steel pipe and at least one roller disposed under the steel pipe, and quenching in the cooling / The steel pipe may be directly contacted with the water jetted by one or more nozzles disposed along the longitudinal direction of the steel pipe.

In the present invention, in the cooling / correcting step, the steel pipe can be rotated by the roller to perform calibration and rapid cooling.

The present invention may further include a slow cooling step of cooling the steel pipe in the air after the heating step.

In the present invention, in the cooling / calibration step, the quenching may be performed until the temperature of the steel pipe reaches 40 째 C to 150 째 C.

In the present invention, the impact beam manufacturing step may further include, between the heating step and the cooling / correcting step, an end forming step of performing hot forming on at least one end of the steel pipe in a state in which the steel pipe is heated have.

In the present invention, in the end forming step, in the state that the steel pipe is supported by the stationary support, the molding can be performed by the upper part metal mold and the corresponding lower part metal mold corresponding to the end of the steel pipe.

In the present invention, the end forming step may form a pressed portion on at least one end of the steel pipe, and the height of the pressed portion may be smaller than the diameter of the steel pipe.

In the present invention, the manufacturing method of the impact beam may include: an end heating step of performing heating on at least one end of the steel pipe before the heating step; And an end molding step of performing hot forming on at least one end of the steel pipe in a state where at least one end of the steel pipe is heated.

In the present invention, in the end forming step, in the state that the steel pipe is supported by the stationary support, the molding can be performed by the upper part metal mold and the corresponding lower part metal mold corresponding to the end of the steel pipe.

In the present invention, the end forming step may form a pressed portion on at least one end of the steel pipe, and the height of the pressed portion may be smaller than the diameter of the steel pipe.

The method of manufacturing an impact beam according to the present invention is characterized in that after the cooling / correcting step, at least one end of the steel tube subjected to the end forming step is heated by an induction heating coil in a temperature range of 100 to 250 for 2 to 30 minutes Followed by air tempering.

In order to solve the above problems, the present invention provides an impact beam, wherein the impact beam is heated to a temperature of 800 to 950 DEG C to change a texture of the material to austenite with respect to the steel pipe; And a cooling / calibrating step of calibrating and cooling the steel pipe heated in the heating step by water cooling and cooling step.

In order to solve the above-mentioned problems, the present invention provides an impact beam in which a compression portion is formed on at least one end portion, the impact beam is moved to a steel pipe at 800 ° C to 950 ° C ; An end molding step of performing hot forming on at least one end of the steel pipe heated by the heating step; And a cooling / calibrating step of performing quenching by calibrating and water cooling on the steel pipe heated in the heating step, wherein the crushing part is formed on the steel pipe by an end molding step, Which is smaller than the diameter of the impact beam.

In order to solve the above-mentioned problems, the present invention provides an impact beam having at least one end portion with a pressing portion, wherein the impact beam is subjected to heating for at least one end of the steel pipe; An end molding step of performing hot forming on at least one end of the steel pipe in a state where at least one end of the steel pipe is heated; A heating step of heating the steel pipe to 800 占 폚 to 950 占 폚 in order to change the texture of the material into austenite structure; And a cooling / calibrating step of performing quenching by calibrating and water cooling on the steel pipe heated in the heating step, wherein the crushing part is formed on the steel pipe by an end molding step, Which is smaller than the diameter of the impact beam.

In the method of manufacturing an impact beam according to an embodiment of the present invention, since the cooling is performed while the steel pipe is calibrated after the heating step, the effect of preventing deformation due to a rapid temperature change upon cooling can be exhibited.

Since the steel pipe is rotated according to the rotation of the lower roller and the upper roller, the outer peripheral surface of the steel pipe can be uniformly pressurized and cooled so that the longitudinal straightness is accurately maintained, The densification and stabilization of the tissue can improve the strength of the product.

In the method of manufacturing an impact beam according to an embodiment of the present invention, support projections projecting at multiple stages along the longitudinal direction are formed on the outer periphery of the lower roller and the upper roller to stably support the outer periphery of the workpiece, The cooling fluid can be smoothly supplied to the entire surface of the workpiece through the fluid flow grooves, so that the effect of quick cooling can be achieved.

The method of manufacturing an impact beam according to an embodiment of the present invention includes manufacturing an impact beam with an end portion formed without performing molding on both ends, simplifying the manufacturing process, reducing manufacturing costs And the productivity can be improved.

The method of manufacturing an impact beam according to an embodiment of the present invention can secure an elongation of 10% or more continuously in the entire portion from the end portion to the center portion of the impact beam and exhibit the effect of having a high straightness.

The method of manufacturing an impact beam according to an embodiment of the present invention can exert the effect of further improving the impact absorbing capability of the formed end by performing end tempering at both ends.

1 is a view schematically showing a step of a method of manufacturing an impact beam according to an embodiment of the present invention.
2 is a diagram illustrating a process line of an impact beam according to one embodiment of the present invention.
Figure 3 is a schematic diagram of a first heater according to one embodiment of the present invention.
4 is a schematic view of a front view of a cooling calibrator in which a cooling / calibrating step according to an embodiment of the present invention is performed.
5 is a schematic diagram of a cooling / calibration step according to an embodiment of the present invention.
6 is a diagram illustrating a side view of a cooling calibrator in which a cooling / calibrating step according to an embodiment of the invention is performed.
7 is a schematic view of the arrangement of the lower roller and the upper roller of the cooling calibrator in which the cooling / calibrating step according to an embodiment of the present invention is performed.
8 is a schematic view of a cooling section of a cooling calibrator in which a cooling / calibration step according to an embodiment of the present invention is performed.
9 is a view schematically showing steps of a method of manufacturing an impact beam according to an embodiment of the present invention.
10 is a view schematically showing an end forming part in which an end forming step according to an embodiment of the present invention is performed.
11 is a view schematically showing a step of a method of manufacturing an impact beam according to an embodiment of the present invention.
Figure 12 is a schematic diagram of a second heater in which an end tempering step according to one embodiment of the present invention is performed.
13 is a view schematically showing steps of a method of manufacturing an impact beam according to an embodiment of the present invention.
14 is a view schematically showing a time-temperature graph of a method of manufacturing an impact beam according to an embodiment of the present invention.
15 is a view schematically showing a time-temperature graph of a method of manufacturing an impact beam according to an embodiment of the present invention.
16 is a view schematically showing a time-temperature graph of a method of manufacturing an impact beam according to an embodiment of the present invention.

Various embodiments and / or aspects are now described with reference to the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects. However, it will also be appreciated by those of ordinary skill in the art that such aspect (s) may be practiced without these specific details. The following description and the annexed drawings set forth in detail certain illustrative aspects of one or more aspects. It is to be understood, however, that such aspects are illustrative and that some of the various ways of practicing various aspects of the principles of various aspects may be utilized, and that the description set forth is intended to include all such aspects and their equivalents.

As used herein, the terms "an embodiment," "an embodiment," " an embodiment, "" an embodiment ", etc. are intended to indicate that any aspect or design described is better or worse than other aspects or designs. .

In addition, the term "or" is intended to mean " exclusive or " That is, it is intended to mean one of the natural inclusive substitutions "X uses A or B ", unless otherwise specified or unclear in context. That is, X uses A; X uses B; Or when X uses both A and B, "X uses A or B" can be applied to either of these cases. It should also be understood that the term "and / or" as used herein refers to and includes all possible combinations of one or more of the listed related items.

It is also to be understood that the term " comprises "and / or" comprising " means that the feature and / or component is present, but does not exclude the presence or addition of one or more other features, components and / It should be understood that it does not.

It is also to be understood that the singular forms "a" and "an" above, which do not expressly state otherwise in this specification, include plural representations. Thus, in one example, a " component surface " includes one or more component surfaces.

Also, terms including ordinal numbers such as first, second, etc. may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Also, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Furthermore, in the embodiments of the present invention, all terms used herein, including technical or scientific terms, unless otherwise defined, are intended to be inclusive in a manner that is generally understood by those of ordinary skill in the art to which this invention belongs. Have the same meaning. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and, unless explicitly defined in the embodiments of the present invention, are intended to mean ideal or overly formal .

1 is a view schematically showing a step of a method of manufacturing an impact beam according to an embodiment of the present invention.

The method of manufacturing an impact beam shown in FIG. 1 includes a heating step (S10) of heating a steel pipe to 800 ° C to 950 ° C to change the texture of the material into austenite structure; And a cooling / calibrating step (S20) of performing quenching by calibrating and water-cooling the steel pipe heated in the heating step. The impact beam thus manufactured is an intuitive impact beam. The bracket is first coupled to both ends by spot welding or the like, and the bracket is attached to the inside of the door member, so that the impact beam can be finally provided to the door.

It is preferable that quenching by water cooling is simultaneously performed for a period including part or all of the period during which the steel pipe is calibrated. Thus, as the steel pipe S is quenched and the calibration is performed while the structure is transformed into the martensite structure, the steel pipe S has a high strength of 1000 MPa or more as a whole from both ends to the center portion without any additional process, And the straightness can be secured.

Here, the steel pipe may contain at least one or more curing ability improving elements such as chromium (Cr), molybdenum (Mo), boron (B), vanadium (V), nickel (Ni), titanium (Ti) It is preferable that the steel sheet is produced by kneading the steel sheet.

Preferably, the steel pipe contains carbon (C) in an amount of 0.10 to 0.40 wt%, Si in an amount of 0.05 to 1.00 wt%, and manganese (Mn) in an amount of 0.5 wt% to 2.0 wt%.

When the content of C is 0.40% by weight or more, the material is hardened to deteriorate the weldability and toughness, and the impact resistance of the product after quenching may be lowered. When the C content is less than 0.10% by weight, the hardenability is insufficient and it becomes difficult to obtain hardness and strength required after quenching and tempering.

Si has a high effect of hardening of the solid solution and improves the hardenability. Therefore, it should be added in an amount of 0.05 wt% or more, but if it is 1.0 wt% or more, the surface of the hot rolled plate becomes bad and the effect of fineness of the structure is saturated.

Mn has an effect of improving hardenability as an element for improving hardenability, so that it should be added in an amount of 0.5 wt% or more, but when it is added in an amount of 2.0 wt% or more, workability is deteriorated. Therefore, the content of Mn is preferably 0.2 wt% to 2.0 wt%.

The content of B is preferably 0.0005 wt% to 0.005 wt%. B is less than 0.0005% by weight, the hardenability improving effect is not large, and when B is contained in an amount exceeding 0.005% by weight, the toughness can be lowered. More preferably, it should not exceed 0.003% by weight, because if it exceeds this amount, a large amount of precipitate called Fe23 (BC) 6 precipitates to cure the material, and rather the hardenability decreases.

Cr is added in an amount of 0.2 wt% or more for improving the hardenability of B during quenching, but the increase of the effect is not significant when added in an amount of 2.0 wt% or more. Therefore, the content of Cr is preferably 0.2 wt% to 2.0 wt%.

P causes brittleness at the time of tempering, so that the impact resistance is markedly deteriorated. Therefore, it is preferable that P is limited to 0.03 wt% or less.

When S is at least 0.03 wt% as an impurity, the amount of nonmetal inclusions is increased to lower the impact resistance, so that the S content is limited to 0.03 wt% or less.

Al is added for the purpose of deoxidation of steel, but when the amount is less than 0.005% by weight, the effect of deoxidation is small. When the amount of Al is more than 0.2% by weight, the degree of cleanliness is lowered due to the formation of oxides.

When N is added in an amount of 0.01% by weight or more, B added for the purpose of improving the hardenability is precipitated in BN to reduce the amount of solid solution B contributing to the improvement in hardenability, Limit.

Mo, V, and Ni are added in an amount of 0.002 wt% or more as a hardenability complementary element, but even when 1.0 wt% or more is added, the above effect is saturated and the cost increases. Therefore, the content of Mo, V, and Ni is preferably 0.002 wt% to 1.0 wt%, respectively.

The steel pipe governed by the roll forming and welding processes is preferably subjected to the defective part inspection and then the heating step (S10). In the heating step, the steel tube is preferably rapidly heated to a temperature corresponding to the austenite region.

At this time, in the heating step S10, it is preferable to heat up to 800 ° C to 950 ° C in consideration of a temperature drop in a section where the steel pipe moves from the heating step S 10 to the cooling / calibration step S 20. Such rapid heating is preferably performed by a high frequency induction heating method. The high frequency induction heating method is a method in which a steel pipe is continuously passed through an induction coil to heat it. When the steel pipe is rotated during induction heating, uniform heat treatment is possible, thereby minimizing thermal deformation of the steel pipe. Such a high frequency induction heating method is advantageous in that it is not necessary to control the gas atmosphere in the heating furnace, and rapid heating is possible, thereby shortening the heat treatment time. Alternatively, the heating step S10 may be performed using a heating furnace.

On the other hand, after the heating step (S10), it may further include a slow cooling step of cooling the steel pipe in air. This can be performed by moving the steel pipe from the heating step S10 to the cooling / calibrating step S20.

Preferably, the heating step is performed by heating for 5 seconds to 2 minutes and 30 seconds in a temperature range of 800 to 950, and the slow cooling step is performed for 0.1 to 10 seconds in the air. In the cooling / Quenching is carried out by a water less than 40 in the calibrator.

The internal structure of the steel pipe S is martensed by the heating step S10 and the cooling / correcting step as described above, so that the hardness and strength of the product can be remarkably increased. Meanwhile, it is preferable that the heating step (S10) is set to 1 minute or less so as not to form an image of ferrite, pearlite, bainite or the like other than martensite. On the other hand, in the case of heating in a temperature range of 800 to 950 for 5 seconds to 2 minutes and 30 seconds, it is preferable that the steel pipe S contains 0.15 to 0.30% by weight of C and 0.001 to 0.002% by weight of B, The site structure can be more firmly generated throughout the steel pipe S. Further, when the steel pipe S contains 0.15 to 0.30% by weight of C and 0.001 to 0.002% by weight of B, better moldability can be achieved even in the end molding step (S15) described later.

On the other hand, if the slow cooling step becomes long, the temperature of the steel pipe becomes low, and after the cooling / correcting step, ferrite, pearlite, bainite or the like may be generated in the steel pipe to lower the strength. Therefore, it is preferable that the slow cooling step is performed for a period in which the strength reduction can be prevented in consideration of the components of the steel pipe.

In other words, it is preferable to transfer the steel pipe at a speed within a range that does not cause a pearlite or ferrite phase, and it is more preferable to transfer at the highest possible speed. Considering the cooling rate in the air, it is preferable to transfer within about 10 seconds.

2 is a diagram illustrating a process line of an impact beam according to one embodiment of the present invention. The heating step (S10) and the cooling / calibrating step (S20) may be performed in the process line as in FIG.

It should be understood that the process line 1 of the impact beam means an automated system for performing the heating step S10 and the cooling / calibrating step S20. In the heat treatment process line 1, It is also possible that devices for performing the end molding step and the end tempering step described later are connected to each other.

First, the steel pipe S may be formed by welding after rolling-forming a 1.6 to 3.5t rolled steel sheet, and after cutting the steel sheet S to a predetermined standard, the steel sheet is stacked. Then, it can be sequentially supplied to the transferring means 3 of the heat treatment process line 1 by a feeding means such as a step feeder.

Here, the conveying means 3 may be a conveyor belt, a chain belt, a conveying roller, etc., and the steel pipe S is conveyed along the conveying means 3 to the first heater 2, the cooling calibrator 100 Moved to the outside or next stage after the cooling / calibration step (S20) is performed. Alternatively, as described later, after the cooling / calibrating step S20 is performed on the steel pipe S, a second heater 4 for tempering other than the first heater 2, as shown in Fig. 2, If configured, may be finally delivered to the next location via the second heater (4) after the cooling / calibration step (S20).

The conveying means 3 is provided with a cylinder or the like for bringing the steel pipe S into the respective devices along the portion connected to the first heater 2, the cooling calibrator 100, and the second heater 4 And a carry-out means for carrying the carried steel pipe S to the conveying means is preferably provided in each of the devices.

Preferably, a polyurethane foam (PUR foam) is disposed inside the steel pipe S provided as a hollow tube at a stage before the steel pipe S is brought into the heating device 2 in which the heating step S10 is performed. An EPOXY foam, and a polypropylene foam (EPP foam).

Such foamed resin is heated together with the steel pipe S in the first heater 2 and foamed to improve the overall strength of the steel pipe S while minimizing the increase in strength, torsion and bending resistance .

Meanwhile, the first heater 2 may be provided with an induction heating coil for generating a high frequency induction current. The steel pipe S brought into the heating device 2 may be pre-set through a high- Can be heated to a heat treatment temperature.

On the other hand, the heated steel pipe S is continuously conveyed into the cooling calibrator 100 by the conveying means 3. Here, the term " continuously transferred " is understood to mean that the process in which the steel pipe S is heated and transferred to the inside of the cooling calibrator 100 is continuously performed with respect to the plurality of steel pipes S.

That is, when the steel pipe S is heated and transferred to the inside of the cooling calibrator 100, the next steel pipe S is heated and transferred to the inside of the cooling calibrator 100 can be repeatedly performed.

It is preferable that the cooling calibrator 100 is provided at a position adjacent to the first heater 2 in the process line 1 and that the heated steel pipe S is heated in a non- Can be minimized.

3 is a view schematically showing a first heater 2 according to an embodiment of the present invention.

The first heater (2) includes an induction heating coil (2.1). Preferably, the induction heating coil (2.1) is disposed so as to surround the outer circumference of the steel pipe (S) in the longitudinal direction of the steel pipe (S). In order to change the texture of the steel pipe (S) to austenitic structure by the first heater (2), the steel pipe is heated to 800 to 950 DEG C.

Figure 4 schematically illustrates a front view of a cooling calibrator in which a cooling / calibrating step according to an embodiment of the present invention is performed, and Figure 5 schematically shows a cooling / calibrating step according to an embodiment of the present invention 6 is a diagram illustrating a side view of a cooling calibrator in which a cooling / calibrating step according to an embodiment of the invention is performed.

As shown in Figures 4 to 6, the calibrations in the cooling / calibrating step are performed by one or more rollers disposed below the steel tube and one or more rollers disposed below the steel tube, and the cooling / Is performed by directly contacting the steel pipe with water jetted by one or more nozzles arranged along the longitudinal direction of the steel pipe.

The jig device 30 of the cooling calibrator 100 includes a pair of lower rollers 30b and an upper roller 30a disposed on the upper portion of the lower roller 30b. Here, the jig device 30 may support the steel pipe S, which is carried into the cooling calibrator 100, to rotate at a predetermined height.

The lower roller 30b and the upper roller 30a may be formed in a cylindrical shape made of metal or ceramic having excellent strength and heat resistance and may be brought into the casing 10 of the cooling calibrator 100 The length of the lower roller 30b and the upper roller 30a may be longer than the length of the steel pipe S so as to integrally support the outer circumferential surface of the steel pipe S.

Here, the lower roller 30b is arranged in parallel and arranged in a pair so as to support the lower portion of the steel pipe S. That is, each of the lower rollers 30b is provided to have the same diameter cross-section, and is disposed at the same height, but is disposed adjacent to each other in the lateral direction.

Preferably, the gap between the lower rollers is set to be narrower than the diameter of the steel pipe S, and the steel pipe S is seated in a space between upper and lower outer peripheral surfaces of the lower rollers, .

Each of the lower rollers 30b may be laterally moved in parallel so as to adjust the spacing between the lower rollers 30b. The height of the steel pipe S supported at the upper portion of the lower roller 30b may vary depending on the diameter The loading and unloading through the opening 11 can be made easier.

At this time, the upper roller 30a is disposed on the upper portion of the lower roller 30b, and the seated steel pipe S is raised and lowered to be pressed. That is, when the steel pipe S is seated in the space formed between the lower rollers 30b, the upper roller 30a can be lowered to press the upper peripheral surface of the steel pipe S.

In this way, the steel pipe S is fixed in shape between the three rollers arranged on the lower outer periphery side by the pair of lower rollers 30b and being arranged to form a triangle as the upper periphery is pressed by the upper roller 30a It is possible to prevent deformation that may occur due to a sudden temperature change upon cooling.

This eliminates the need for a separate calibration process to calibrate the deformation after cooling, simplifying the production process and reducing the cost and time of the product

The acidity can be improved.

In addition, since the steel pipe S having various diameters can be fixed and rotated on the upper portion of the lower roller 30b as the upper roller 30a is lifted and lowered, the compatibility of the product can be improved.

7 is a schematic view of the arrangement of the lower roller and the upper roller of the cooling calibrator in which the cooling / calibrating step according to an embodiment of the present invention is performed.

The upper roller 30a is preferably disposed so as to face the space between the lower rollers 30b. That is, the upper roller 30a is arranged such that its widthwise center line is aligned with the upper portion of the widthwise center line of the space between the lower rollers.

Thus, when the upper roller 30a descends to press the upper peripheral surface of the steel pipe S, the upper outer peripheral surface of each lower roller 30b supports both sides of the lower outer peripheral surface of the steel pipe S with the same force And the steel pipe S can be stably supported between the three rollers.

It is preferable that the lower roller 30b and the upper roller 30a are rotated along a rotation axis parallel to the longitudinal direction of the steel pipe S. [ At this time, it is preferable that at least one of the lower roller 30b and the upper roller 30a is rotationally driven.

That is, when any one of the lower roller 30b and the upper roller 30a is driven to rotate while the lower roller 30b and the upper roller 30a are in close contact with the outer circumference of the steel pipe S, S and another roller in close contact with the outer periphery of the steel pipe S can be rotated.

The steel pipe S is pressed between the upper roller 30a and the lower roller 30b to prevent the deformation of the steel pipe S due to the temperature change during cooling. So that the straightness in the longitudinal direction can be accurately maintained.

In addition, the product of high straightness can be produced without a separate calibration process for correcting the deformation, so that the productivity and quality of the product can be improved. In addition, according to the width of the upper roller 30a, it can be applied to a workpiece s having various diameters without requiring a separate mold or a design change, so that compatibility of products can be improved.

Further, since the steel pipe S carried into the casing 10 in the heated state is rotated together with the ejection of the cooling fluid, not only uniform cooling can be performed, but also, due to the uniform pressure applied to the surface together with cooling, Can be densified and the strength of the product can be improved by stabilizing the tissue through reduction of defects such as cavities and uniform tissue distribution.

Meanwhile, as shown in FIG. 4, the jig device 30 may further include rotation driving means for rotating the lower roller 30b. In detail, the rotation driving means may be provided as a hydraulic motor 35 provided at one side of the casing 10.

At this time, the hydraulic motor 35 may provide rotational force to the lower roller 30b through a belt or a chain. As the hydraulic motor 35 is connected to the lower roller 30b fixed to the inside of the casing 10 rather than the upper roller 30a which is driven to move up and down, Can be simplified, the connection can be stably maintained without failure of the belt or the chain, and the durability of the product can be improved.

The cooling unit 20 is installed in the space between the lower roller 30b and the upper roller 30a to rapidly cool the steel pipe S rotated in the partition space k, Thereby supplying a cooling fluid.

At this time, the cooling fluid may be water, water-soluble oil, mineral oil or the like having a temperature of 20 to 30 ° C, and a rust preventive agent for preventing corrosion may be added to the cooling fluid.

The injection pressure is preferably set to 3 to 5 kg / cm 2, and the injection pressure is such that the steel pipe S is cooled to 100 ° C. or lower within a set time, so that the internal structure of the martensite phase is changed into another phase Transition can be prevented.

6, on the outer circumference of the lower roller 30b and the upper roller 30a, a plurality of support protrusions 34a.36a are formed along the longitudinal direction of the workpiece s in the circumferential direction It is preferable that the cooling fluid flow grooves 34 and 36 are formed.

The cooling fluid flow grooves 34 and 36 are recessed along the circumferential direction on the outer circumference of the lower roller 30b and the upper roller 30a. Is formed in multiple stages along the longitudinal direction of the roller (30b) and the upper roller (30a)

The formed cooling fluid flow grooves 34, 36 can be partitioned by the support protrusions 34a, 36a.

The support protrusions 34a and 36a support the outer circumferential surface of the steel pipe S through the protruded outer surface and the cooling fluid flow grooves 34 and 36 are formed in the steel pipe S between the support protrusions 34a and 36a. Thereby increasing the contact area with the cooling fluid, thereby enabling rapid cooling of the steel pipe S.

Here, the cooling fluid flow grooves 34, 36 and the support protrusions 34a, 36a are preferably spiral. The steel pipe S may be rotated in conjunction with the rotation of the lower roller 30b and the upper roller 30a in a state where one end and the other end of the steel pipe S are held by the shielding cover 12 and the unloading cylinder 14. [ have.

At this time, the portion of the outer circumference of the steel pipe S which is in contact with the support protrusions 34a and 36a gradually changes in accordance with the rotation of the lower roller 30b and the upper roller 30a.

That is, the portion of the outer circumference of the steel pipe S which is in contact with the support protrusions 34a and 36a is disposed on the side of the cooling fluid flow grooves 34 and 36 in accordance with the rotation of the rollers 30a and 30b, Exposed portions of the steel pipe S disposed in the cooling fluid flow grooves 34 and 36 are brought into contact with the support protrusions 34a and 36a in accordance with the rotation of the rollers 30a and 30b, Lt; / RTI >

Accordingly, the outer circumferential surface of the steel pipe S can be cooled at a uniform speed, and the densification and stabilization of the structure due to the pressurization can be made uniform over the entire surface of the steel pipe S, thereby improving the quality of the heat treatment of the product .

It is most preferable that both the lower roller 30b and the supporting protrusions of the upper roller 30a and the cooling fluid flow grooves are spirally formed. However, as shown in the figure, only the support protrusions of the lower roller 30b and the cooling fluid flow grooves It may be provided in a spiral shape.

Meanwhile, as shown in FIG. 4, the upper roller 30a is rotatably coupled to the lifting frame 31 connected to the lifting and lowering means.

More preferably, the lifting frame 31 is coupled to and guided by a guide portion 13 provided in the casing 10 in a vertical direction, and the lifting and lowering means is provided on the upper portion of the casing 10 It is preferable that the hydraulic cylinder 33 is provided. Here, the guide portion 13 is provided to vertically connect the upper and lower surfaces of the casing 10, and a plurality of guide portions 13 may be provided along an outer area of a portion where the lower roller 30b is installed.

The lifting frame 31 is connected to a hydraulic cylinder 33 provided on the upper portion of the casing 10 and can be moved up and down according to the expansion and contraction of the hydraulic cylinder 33. At this time, the lifting frame 31 may be provided with a guide connection portion 32 along a portion corresponding to each of the guide portions 13.

Here, the guide connection portion 32 may have a vertical hollow corresponding to the outer diameter of the guide portion 13, and may be coupled to surround the guide portion 13.

At this time, the lifting frame 31 can be coupled to the guide portions 13 through the guide connection portion 32 so that the lifting frame 31 can be vertically guided along the forming direction of the guide portion 13 . Accordingly, the upper roller 30a can press the upper peripheral surface of the steel pipe S in the correct direction.

8 is a schematic view of a cooling section of a cooling calibrator in which a cooling / calibration step according to an embodiment of the present invention is performed.

The cooling unit 20 is preferably coupled to the lifting frame 31 to be disposed on both sides of the upper roller 30a. The cooling unit 20 includes a plurality of first injection nozzles 20a spaced apart from each other at predetermined intervals along one side of the upper roller 30a and a plurality of second injection nozzles 20b spaced from each other along the other side of the upper roller 30a And a plurality of second injection nozzles 20b disposed to face the spaced spaces between the first injection nozzles 20a.

Since the first injection nozzle 20a and the second injection nozzle 20b are disposed in mutually offset shapes, the first and second injection nozzles 20a and 20b are uniformly sprayed onto the workpiece s in a state where the superposition of the cooling fluids ejected from the respective injection nozzles is minimized And efficient cooling is possible without waste of the cooling fluid.

The injection nozzles 20a and 20b may be inclined downward along the tangential direction of the lower roller 30a. That is, the injection nozzles 20a and 20b may be provided such that the injection direction is directed to the lower end of the lower roller 30a.

Accordingly, when the lifting frame 31 is lowered and the workpiece s comes into contact with the lower outer circumferential surface of the upper roller 30a, the injection nozzles 20a and 20b can move the workpiece s, And the cooling fluid can be accurately sprayed to the outer circumferential side of the workpiece s disposed in the space between the lower roller 30b and the upper roller 30a.

Since the injection nozzles 20a and 20b are coupled to the lifting frame 31 and are inclined downward along the tangential direction of the lower roller 30a in contact with the lower outer peripheral surface of the upper roller 30a, The cooling process for spraying can be performed immediately, and rapid heat treatment is possible.

It is also possible to control the angle of the injection nozzles 20a and 20b as the steel pipe S is rotated together with the injection of the cooling fluid through the injection nozzles 20a and 20b, The workpiece s having various diameters can be cooled according to the lift width of the roller 30a or the lifting frame 31 so that the compatibility of the product can be improved.

Accordingly, in the cooling / correcting step, the steel pipe is rotated by the roller to perform the calibrating and quenching. Since the calibration is made by the roller and the cooling water directly flows to the cooling water sprayed by the plurality of nozzles at the same time and the cooling water flows along the entire surface of the steel pipe S as the steel pipe S rotates, More uniform cooling can be achieved. Accordingly, the steel pipe S can have overall good structural characteristics from the center portion to the end portion, and as a result, can exhibit an effect of uniformly maintaining a high elongation.

Meanwhile, quenching in the cooling / calibration step is performed until the temperature of the steel pipe reaches 40 째 C to 150 째 C. If the quench finishing temperature is higher than 150 캜, there is a problem that the elongation becomes low. On the other hand, when the quenching finishing temperature is lower than 40 캜, there is a problem in that the time and cost for production of the product are increased.

9 is a view schematically showing steps of a method of manufacturing an impact beam according to an embodiment of the present invention.

The method of manufacturing an impact beam shown in FIG. 9 includes a heating step (S10) of heating a steel pipe to 800 ° C to 950 ° C to change the texture of the material into austenite structure; An end forming step (S15) of performing hot forming on at least one end of the steel pipe in a state that the steel pipe is heated; And a cooling / calibrating step (S20) of performing quenching by calibrating and water-cooling the steel pipe heated in the heating step. The impact beam thus produced is a double-ended impact beam, which improves the coupling with the brackets at both ends or reduces the volume of the door to reduce the thickness of the door, or both ends can be flat- It corresponds to the type of impact beam.

The method of manufacturing the impact beam shown in FIG. 9 is the same as the method of manufacturing the impact beam shown in FIG. 1 except that the end forming step S15 is added. The impact beam thus produced is a double-ended impact beam, which improves the coupling with the brackets at both ends or reduces the volume of the door to reduce the thickness of the door, or both ends can be flat- It corresponds to the type of impact beam.

In the method of manufacturing the impact beam shown in Fig. 9, it is preferable that quenching by water cooling be simultaneously performed for a period including part or all of the period in which the steel pipe is calibrated. Thus, as the steel pipe S is quenched and the calibration is performed while the structure is transformed into the martensite structure, the steel pipe S has a high strength of 1000 MPa or more as a whole from both ends to the center portion without any additional process, And the straightness can be secured.

Preferably, the heating step (S10) is performed by heating for 5 seconds to 2 minutes and 30 seconds in a temperature range of 800 to 950, and in the cooling / calibrating step, quenching is performed by 40 or less water in a cooling calibrator do.

The internal structure of the steel pipe S is martensized by the heating step S10 and the cooling / calibrating step S20 as described above, so that the hardness and strength of the product can be significantly increased. Meanwhile, it is preferable that the heating step (S10) is set to 1 minute or less so as not to form an image of ferrite, pearlite, bainite or the like other than martensite. On the other hand, in the case of heating in a temperature range of 800 to 950 for 5 seconds to 2 minutes and 30 seconds, it is preferable that the steel pipe S contains 0.15 to 0.30% by weight of C and 0.001 to 0.002% by weight of B, The site structure can be more firmly generated throughout the steel pipe S. Further, when the steel pipe S contains 0.15 to 0.30% by weight of C and 0.001 to 0.002% by weight of B, it is possible to achieve better moldability even in the end molding step (S15).

On the other hand, the time interval from the completion of the heating step S10 until the end forming step S15 is performed and the cooling / calibration step S20 is started is 0.1 second to 20 seconds, more preferably 0.1 second to 10 seconds First time is preferable.

If the time interval is longer than 10 seconds, the temperature of the steel pipe is lowered, and ferrite, pearlite, bainite or the like is generated in the steel pipe after the cooling / correcting step (S20).

As described above, the cooling / calibrating step (S20) is performed such that the calibration in the cooling / calibration step is performed by at least one roller disposed under the steel pipe and at least one roller disposed under the steel pipe, Quenching in the cooling / calibrating step is performed by directly contacting the steel pipe with water injected by one or more nozzles arranged along the longitudinal direction of the steel pipe.

As described above, in the method of manufacturing an impact beam according to an embodiment of the present invention, the heating step S10 is performed, and the end forming step S15 and the cooling / calibrating step S20 are performed successively. In addition, since the calibration by the roller and the quenching by the cooling water jetted by the nozzle are performed in the cooling / calibration step including such a step, the manufactured impact beam is not only partially press-molded at the end portion And can maintain a high elongation rate over the entire impact beam.

10 is a view schematically showing an end forming part in which an end forming step according to an embodiment of the present invention is performed.

The end molding step S15 is preferably performed by the end molding part 300 including a partial mold covering only the end of the steel pipe S. [

The end forming part 300 shown in FIG. 10 includes a stationary support 301 for supporting a steel pipe S; And an upper portion mold 320 and a lower portion mold 310 disposed at one or both ends of the fixed support.

The upper part mold 320 is about the end of the steel pipe, and the lower part mold 310 has a shape corresponding to the upper part mold.

On the other hand, a steel pipe support hole 301.1 is formed on the upper surface of the fixed support 301, and a steel pipe S is placed in the steel pipe support hole 301.1. Therefore, in the end forming step S15, the molding is performed by the upper partial mold and the corresponding lower partial mold with respect to the end of the steel pipe, with the steel pipe supported by the fixed support 301. [

In one embodiment of the present invention, the steel pipe is not formed by a metal mold that covers the entire steel pipe, but both ends of the steel pipe are formed by a partial mold covering only the region corresponding to the end portion of the steel pipe, As the cooling / calibrating step by the calibrator is carried out, it is possible to obtain the effect of forming a steel pipe with a small-sized metal mold and holding a high elongation and strength with respect to the entire steel pipe. In addition, since the entire mold is not used, the cost for manufacturing the mold equipment can be drastically reduced, and the size of the factory equipment can be greatly reduced.

9, even though one end or both ends of a steel pipe are formed by a metal mold, cooling and calibration in the cooling / calibrating step (S20) are performed uniformly throughout the steel pipe (S) It is confirmed that the formed elongation at the one end portion or both end portions can have a high elongation and a good tissue characteristic similar to the central portion.

In the end forming step S15 as described above, the crimping portion is formed on at least one end of the steel tube, and the height of the crimping portion is smaller than the diameter of the steel tube.

Such a pressing portion can exert the effect of further improving the adhesion with the bracket or reducing the volume occupied by the impact beam inside the door. Also, depending on the shape of the upper part mold and the lower part mold, the compression part itself may be formed so as to function as a bracket.

11 is a view schematically showing a step of a method of manufacturing an impact beam according to an embodiment of the present invention.

The manufacturing method of the impact beam shown in Fig. 11 includes a heating step (S10) of heating a steel pipe to 800 ° C to 950 ° C to change the texture of the material into austenite structure; An end forming step (S15) of performing hot forming on at least one end of the steel pipe in a state that the steel pipe is heated; A cooling / calibrating step (S20) of performing quenching by calibrating and water-cooling the steel pipe heated in the heating step; And an end tempering step (S30) in which at least one end of the steel pipe subjected to the end forming step is heated by an induction heating coil in a temperature range of 100 to 250 for 2 to 30 minutes, followed by air cooling treatment. The impact beam thus produced is a double-ended impact beam, which improves the coupling with the brackets at both ends or reduces the volume of the door to reduce the thickness of the door, or both ends can be flat- It corresponds to the type of impact beam.

The end tempering step S30 may be performed on the entire steel pipe S as well as the end of the steel pipe S.

The manufacturing method of the impact beam shown in FIG. 11 corresponds to the manufacturing method of the impact beam further including the end tempering step (S30) in comparison with the manufacturing method of the impact beam shown in FIG.

In the end forming step S15, one end or both end portions are hot formed using a partial die. The end tempering step S30 may be performed to further improve the tissue characteristics with respect to the formed one end or both ends. According to the end tempering step S30 as described above, the weak points at one end or both ends where the press forming is performed can be completely improved, and the elongation at one end or both ends can be secured to the same level as the center part of the steel pipe S can do.

12 is a view schematically showing a second heater 4 in which an end tempering step according to an embodiment of the present invention is performed.

The second heater (4) includes an induction heating coil (4.1). Preferably, the induction heating coil 4.1 is disposed so as to surround the outer periphery on the end side in the longitudinal direction of the steel pipe S. An end tempering step (S30) in which at least one end of the steel pipe subjected to the end forming step is heated by the induction heating coil in the temperature range of 100 to 250 for 2 to 30 minutes and then subjected to air cooling by the second heater (4) ) Can be performed.

The manufacturing method of the impact beam shown in Fig. 13 is the addition of the end heating step S8 and the end forming step S9 in the method of manufacturing the impact beam shown in Fig. The impact beam thus produced is a double-ended impact beam, which improves the coupling with the brackets at both ends or reduces the volume of the door to reduce the thickness of the door, or both ends can be flat- It corresponds to the type of impact beam.

In the method of manufacturing the impact beam shown in Fig. 13, it is preferable that quenching by water cooling is simultaneously performed for a period including part or all of the period in which the steel pipe is calibrated. Thus, as the steel pipe S is quenched and the calibration is performed while the structure is transformed into the martensite structure, the steel pipe S has a high strength of 1000 MPa or more as a whole from both ends to the center portion without any additional process, And the straightness can be secured.

Preferably, the heating step (S10) is performed by heating for 5 seconds to 2 minutes and 30 seconds in a temperature range of 800 to 950, and in the cooling / calibrating step, quenching is performed by 40 or less water in a cooling calibrator do.

The internal structure of the steel pipe S is martensized by the heating step S10 and the cooling / calibrating step S20 as described above, so that the hardness and strength of the product can be significantly increased. Meanwhile, it is preferable that the heating step (S10) is set to 1 minute or less so as not to form an image of ferrite, pearlite, bainite or the like other than martensite. On the other hand, in the case of heating in a temperature range of 800 to 950 for 5 seconds to 2 minutes and 30 seconds, it is preferable that the steel pipe S contains 0.15 to 0.30% by weight of C and 0.001 to 0.002% by weight of B, The site structure can be more firmly generated throughout the steel pipe S. Further, when the steel pipe S contains 0.15 to 0.30% by weight of C and 0.001 to 0.002% by weight of B, it is possible to achieve better moldability even in the end molding step (S15).

Meanwhile, an end heating step (S8) for heating the at least one end of the steel pipe before the heating step (S10); And an end molding step (S9) for performing hot forming for at least one end of the steel pipe in a state where at least one end of the steel pipe is heated is performed.

It is preferable that the end heating step S8 is performed by using the second heater 4 or the device having the same structure as the second heater 4 shown in Fig. Specifically, the end heating step (S8) is performed by heating the end portion in a temperature range of 600 to 950 for 3 seconds to 1 minute so that hot forming can be performed.

Meanwhile, the end molding step S9 is performed in the same manner as the end molding step S15 in FIG. 9 described above. Preferably, this is done by the end forming portion 300 shown in Fig.

Preferably, after the end forming step S9, the steel pipe is moved into the air without special cooling, and the steel pipe is heated in the heating step S10.

As described above, the cooling / calibrating step (S20) is performed such that the calibration in the cooling / calibration step is performed by at least one roller disposed under the steel pipe and at least one roller disposed under the steel pipe, Quenching in the cooling / calibrating step is performed by directly contacting the steel pipe with water injected by one or more nozzles arranged along the longitudinal direction of the steel pipe.

As described above, in the method of manufacturing an impact beam according to an embodiment of the present invention, the end heating step (S8) and the end forming step (S9) are performed, whereby a pressing portion is formed at one or more ends of the steel pipe, (S10) and the cooling / calibration step (S20) are performed consecutively. In addition, since the calibration by the roller and the quenching by the cooling water jetted by the nozzle are performed in the cooling / calibration step including such a step, the manufactured impact beam is not only partially press-molded at the end portion And can maintain a high elongation rate over the entire impact beam.

14 is a view schematically showing a time-temperature graph of a method of manufacturing an impact beam according to an embodiment of the present invention.

The method of manufacturing the impact beam shown in FIG. 14 corresponds to the time-temperature graph for the method of manufacturing the impact beam shown in FIG.

15 is a view schematically showing a time-temperature graph of a method of manufacturing an impact beam according to an embodiment of the present invention.

The method of manufacturing the impact beam shown in FIG. 15 corresponds to the time-temperature graph of the method of manufacturing the impact beam shown in FIG.

16 is a view schematically showing a time-temperature graph of a method of manufacturing an impact beam according to an embodiment of the present invention.

The method of manufacturing the impact beam shown in FIG. 16 corresponds to the time-temperature graph for the method of manufacturing the impact beam shown in FIG.

Hereinafter, the impact beam manufactured by the above-described method of manufacturing an impact beam will be described.

The impact beam according to an embodiment of the present invention is an impact beam, wherein the impact beam is heated to a temperature of 800 ° C to 950 ° C to change a texture of the material to austenite with respect to the steel pipe; And a cooling / calibrating step of calibrating the steel pipe heated in the heating step and quenching by water cooling.

The impact beam thus manufactured can be disposed inside the door by being coupled with the bracket by spot welding or the like as an intuitive impact beam. The description of the impact beam thus produced corresponds to the description of the method of manufacturing the impact beam shown in Fig. 1 described above.

The impact beam according to an embodiment of the present invention is an impact beam having a compression part formed on at least one end thereof, and the impact beam is applied to a steel pipe at 800 ° C to 950 ° C ; An end molding step of performing hot forming on at least one end of the steel pipe heated by the heating step; And a cooling / calibrating step of performing quenching by calibrating and water cooling on the steel pipe heated in the heating step, wherein the crushing part is formed on the steel pipe by an end molding step, Which is smaller than the diameter of the impact beam.

The impact beam thus produced is formed as a hot-formed impact beam at one or more end portions. The description of the impact beam thus produced corresponds to the description of the method of manufacturing the impact beam shown in Fig. 9 described above. Alternatively, such an impact beam may be manufactured by performing the end tempering step S30, and the description thereof corresponds to the description of the method of manufacturing the impact beam shown in Fig. 11 described above

An impact beam according to an embodiment of the present invention is an impact beam formed with a pressing part against at least one end thereof, the impact beam having a pressing part against at least one end thereof. The impact beam is heated to at least one end of the steel pipe ; An end molding step of performing hot forming on at least one end of the steel pipe in a state where at least one end of the steel pipe is heated; A heating step of heating the steel pipe to 800 占 폚 to 950 占 폚 in order to change the texture of the material into austenite structure; And a cooling / calibrating step of performing quenching by calibrating and water cooling on the steel pipe heated in the heating step, wherein the crushing part is formed on the steel pipe by an end molding step, Which is smaller than the diameter of the impact beam.

The impact beam thus produced is formed as a hot-formed impact beam at one or more end portions. The description of the impact beam thus produced corresponds to the description of the method of manufacturing the impact beam shown in Fig. 9 described above. Alternatively, such an impact beam may be manufactured by performing the end tempering step S30, and the description thereof corresponds to the description of the method of manufacturing the impact beam shown in Fig. 13 described above

Results of physical property test

Example 1 A steel tube containing 0.21% by weight of carbon, 0.33% by weight of Si, 1.21% by weight of Mn, 0.015% by weight of P and 0.006% by weight of S was sintered and heated at 900 for 1 minute to carry out the heating step , A three-point pressing correction by a roller by the cooling calibrator and a cooling through contact with the sprayed water are performed to perform a cooling / correcting step until the temperature of the steel pipe reaches 40 degrees

Example 2 A steel tube containing 0.21% by weight of carbon, 0.33% by weight of Si, 1.21% by weight of Mn, 0.015% by weight of P and 0.006% by weight of S was sintered and heated at 900 for 1 minute to carry out the heating step , Press molding is performed on the one end portion with a partial mold for 5 seconds, and the 3-point pressing correction by the roller is performed by the cooling calibrator immediately, and cooling is performed through contact with the injected water, so that the temperature of the steel pipe reaches 40 degrees Perform cooling / calibration steps until

Example 3 A steel tube containing 0.21% by weight of carbon, 0.33% by weight of Si, 1.21% by weight of Mn, 0.015% by weight of P and 0.006% by weight of S was sintered and heated at 900 for 1 minute to carry out a heating step , Press molding is performed for one end with a partial mold for 5 seconds, and 3-point pressing correction by a roller is performed by the cooling calibrator immediately, and cooling is performed through contact with the injected water, so that the temperature of the steel pipe reaches 40 degrees / RTI > cooling / calibrating step is performed, and end tempering is performed on the one end at a temperature of 120 degrees

Example 4 A steel tube containing 0.21% by weight of carbon, 0.33% by weight of Si, 1.21% by weight of Mn, 0.015% by weight of P and 0.006% by weight of S was sintered for 10 seconds at a temperature of 800 for one end, The heating step is carried out, the one-end portion is subjected to a press forming process with a partial mold for 5 seconds, the resultant is conveyed in air and heated at a temperature of 900 for 1 minute to perform a heating step, Cooling through contact between the pressure reduction and the sprayed water is performed to perform the cooling / calibration steps until the temperature of the steel pipe reaches 40 degrees

Comparative Example 1: Steel tube containing 0.21% by weight of carbon, 0.33% by weight of Si, 1.21% by weight of Mn, 0.015% by weight of P and 0.006% by weight of S was sintered by heating at a temperature of 900 for 1 minute, Cooling is performed until the temperature of the steel pipe reaches 40 degrees while molding the end of the steel pipe inside the mold in which the cooling pipe is formed in the inside of the entire steel pipe.

Experimental results on the elongation ratios of Examples 1, 2, 3 and 4 and Comparative Examples are as follows.

("One end" in the following table refers to one end formed in Examples 2 and 3)

From one end
1/8 point From one end
Quarter point From one end
2/4 point From one end
3/4 point From one end
7/8 branch Example 1 11% 11% 11 12 11 Example 2 8% 9% 9% 8% 8% Example 3 10.5% 12% 11% 11% 11% Example 4 10% 11% 10% 10% 9% Comparative Example 4% 7% 8% 9% 5%

As shown in the table, it can be seen that the impact beam manufactured by the method of manufacturing an impact beam of the present invention has a high elongation as a whole along the longitudinal direction of the impact portion and the shaped portion of the end portion.

In the method of manufacturing an impact beam according to an embodiment of the present invention, since the cooling is performed while the steel pipe is calibrated after the heating step, the effect of preventing deformation due to a rapid temperature change upon cooling can be exhibited.

Since the steel pipe is rotated according to the rotation of the lower roller and the upper roller, the outer peripheral surface of the steel pipe can be uniformly pressurized and cooled so that the longitudinal straightness is accurately maintained, The densification and stabilization of the tissue can improve the strength of the product.

In the method of manufacturing an impact beam according to an embodiment of the present invention, support projections projecting at multiple stages along the longitudinal direction are formed on the outer periphery of the lower roller and the upper roller to stably support the outer periphery of the workpiece, The cooling fluid can be smoothly supplied to the entire surface of the workpiece through the fluid flow grooves, so that the effect of quick cooling can be achieved.

The method of manufacturing an impact beam according to an embodiment of the present invention includes manufacturing an impact beam with an end portion formed without performing molding on both ends, simplifying the manufacturing process, reducing manufacturing costs And the productivity can be improved.

The method of manufacturing an impact beam according to an embodiment of the present invention can secure an elongation of 10% or more continuously in the entire portion from the end portion to the center portion of the impact beam and exhibit the effect of having a high straightness.

The method of manufacturing an impact beam according to an embodiment of the present invention can exert the effect of further improving the impact absorbing capability of the formed end by performing end tempering at both ends.

The description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features presented herein.

Claims (1)

A method of manufacturing an impact beam,
A heating step of heating the steel pipe to 800 DEG C to 950 DEG C so as to change the texture of the material into austenite structure; And
And a cooling / correcting step of performing quenching by calibrating and water-cooling the steel pipe heated in the heating step,
Quenched by water cooling is simultaneously performed for a period including a part or all of the period during which the steel pipe is calibrated,
The calibration in the cooling / calibration step is performed by one or more rollers disposed below the steel pipe and one or more rollers disposed below the steel pipe,
Quenching in the cooling / calibration step is performed by directly contacting the steel pipe with water sprayed by one or more nozzles arranged along the longitudinal direction of the steel pipe,
In the cooling / calibration step,
Wherein the steel pipe is rotated by the roller to perform calibration and quenching.



.

Images