KR101124239B1 - Automotive seat rail having high strength and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a method for producing a high strength automobile seat rail using press hardening, and to an automobile seat rail manufactured by the present invention having excellent strength.

Method for producing a high-strength vehicle seat rail according to the present invention, (a) at least one element selected from the group consisting of chromium (Cr), molybdenum (Mo), boron (B), vanadium (V) and nickel (Ni). Preparing a steel sheet containing the; (b) forming the steel sheet into a basic shape through a process including blanking and piercing; (c) heating the steel sheet to a temperature corresponding to an austenite region; (d) rapidly transferring the steel sheet to the press mold at a speed within which no pearlite, ferrite or bainite phases are formed; And (e) rapidly cooling the steel sheet in a press mold and simultaneously molding the steel sheet into a vehicle seat rail having a predetermined shape.

The high-strength automobile seat rail of the present invention produced by this is excellent in tensile strength of 1200MPa to 1700MPa.

Steel plate, automobile, sheet rail, press

Description

High-strength car seat rail and manufacturing method thereof {AUTOMOTIVE SEAT RAIL HAVING HIGH STRENGTH AND MANUFACTURING METHOD OF THE SAME}

1 is a photograph of a typical car seat.

2 is a photograph of various seat rails applied to an automobile.

3 is a flowchart illustrating a method of manufacturing a vehicle seat rail using conventional press molding.

4 is a flowchart illustrating a method of manufacturing a vehicle seat rail using a conventional roll forming.

5 is a flowchart illustrating a method of manufacturing a high strength automobile seat rail according to an embodiment of the present invention.

The present invention relates to a high-strength automobile seat rail and a method for manufacturing the same, and more particularly, to a manufacturing method of an automobile seat rail using a press hardening and to an automobile seat rail manufactured by this and excellent in strength.

Recently, researches for lightening automobiles have been actively conducted for fuel efficiency improvement, exhaust gas reduction, and environmental protection. There are various methods of weight reduction, and in terms of materials, a method using aluminum, magnesium, plastic, or the like, which is a high tensile strength steel or a lightweight material, is applied.

Accordingly, automotive seats are also designed to be lighter by applying high-strength steel or lightweight materials. In a typical automobile seat, as shown in FIG. 1, the automobile seat 10 is composed of a seat frame, a seat rail, a seat fan, a recliner, a back spring, a cushion spring, and the like.

Among them, various types of seat rail photographs currently applied to automobiles are shown in FIG. 2. As shown in FIG. 2, the seat rails 30, 32, and 34 are formed of the upper rails 30a, 32a, and 34a and the lower rails 30b, 32b, and 34b, and have different shapes depending on the vehicle model. It is common. Seat rails (30, 32, 34) is to move the seat back and forth to fit the body shape, it should have a uniform thickness and excellent shape for smooth operation. In addition, the strength should be high so as not to be easily deformed, and fatigue properties should be excellent.

Such seat rails are generally manufactured by press molding (Comparative Material 1 in Table 1).

Referring to FIG. 3, according to the method of using press molding, a sheet rail is manufactured by blanking a prepared steel sheet and then pressing molding. The sheet rail having a hole shape is pierced during press molding.

However, in the method using the press molding, since the formability is deteriorated when a high strength steel sheet is used, only a steel sheet having a tensile strength of 590 MPa or less should be used. For this reason, seat rails used in domestic passenger cars vary depending on the automobile company or model, but the tensile strength is only 390MPa to 590MPa. Accordingly, in order to satisfy the characteristics required for the seat rail, the thickness of the steel sheet must be increased, thereby increasing the weight of the seat rail.

In order to solve this problem, a method of manufacturing a sheet rail using roll molding having excellent moldability has been proposed.

As shown in Fig. 4, according to the method using roll forming, the prepared steel sheet is roll formed into a sheet rail. The perforated seat rail pierces before roll forming.

Roll molding is excellent in formability compared to press molding, and can be applied to molding high tensile strength steel having a tensile strength of 780 MPa to 980 MPa. That is, the sheet rail manufactured using roll forming may use a high strength steel sheet as compared to press forming, and thus the thickness of the steel sheet may be reduced. However, roll forming is also difficult to form a steel sheet having a tensile strength of 980 MPa or more.

That is, according to the prior art, there is a certain limit in manufacturing a car seat rail from a high strength steel sheet, and thus there is a limit in weight reduction of the car seat rail.

The present invention was devised to solve the above problems, and an object of the present invention is to produce an automobile seat rail that can easily form a high strength steel sheet and to produce an automobile seat rail which is excellent in strength and can be made lightweight. To provide.

In order to achieve the above object, a method of manufacturing a high-strength automobile seat rail according to the present invention includes (a) a group consisting of chromium (Cr), molybdenum (Mo), boron (B), vanadium (V), and nickel (Ni). Preparing a steel sheet containing at least one element selected from; (b) forming the steel sheet into a basic shape through a process including blanking and piercing; (c) heating the steel sheet to a temperature corresponding to an austenite region; (d) rapidly transferring the steel sheet to the press mold at a speed within which no pearlite, ferrite or bainite phases are formed; (E) rapidly cooling the steel sheet in a press mold and simultaneously molding the steel sheet into a vehicle seat rail having a predetermined shape; It includes. According to this manufacturing method it is possible to improve the strength of the car seat rail can be reduced in weight.

Hereinafter, a method of manufacturing a high strength vehicle seat rail and a high strength vehicle seat rail manufactured thereby according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Table 1 compares the high-strength automobile seat rail manufacturing process of the present invention with the prior art.

division Automotive Seat Rail Manufacturing Process The tensile strength thickness Lightweight
effect Remarks Comparative material 1 Cold Rolled or Hot Rolled Coil-Blanking-Press forming into sheet rail 600
MPa
Below Thick none 1. Current application process
2. Limit on high strength Comparative material 2 Cold rolled or hot rolled coil-Piercing (for seat rail shape with holes)-Roll forming to seat rail shape 1000
MPa
Below middle Has a little 1. Current application process
2. Press molding
High strength is possible
Limit to high strength Invention
One

칭 - 뜨임
* 필요시 뜨임공정은 생략가능Cold Rolled or Hot Rolled Coil-Blanking and Piercing-High Frequency Induction Heating-Press

Ching-Tempering
* Tempering process can be omitted if necessary 1200
~
1700
MPa tenuity greatness 1.Max 1700MPa Class
High strength up to
2. Through thickness reduction
Larger weight reduction effect Invention 2 Cold Rolled or Hot Rolled Coil-Blanking and Piercing-Batch Furnace, Continuous or Rotating Furnace-Press

Ching-Tempering
* Tempering process can be omitted if necessary 1200
~
1700
MPa tenuity greatness 1. High strength up to 1700MPa
2. Through thickness reduction
Larger weight reduction effect

An embodiment of the present invention will be described in detail with reference to Table 1.

5 is a flowchart illustrating a method of manufacturing a high strength automobile seat rail according to an embodiment of the present invention.

As shown in Figure 5, the manufacturing method of the automobile seat rail according to this embodiment is a steel sheet preparation step (ST10), blanking piercing step (ST20), rapid heating step (ST30), rapid transfer step (ST40), press hardening A step ST50 and a tempering step ST60 are included. Each step is described in more detail as follows.

First, in the steel sheet preparation step (ST10), hardenability improving elements such as chromium (Cr), molybdenum (Mo), boron (B), vanadium (V), nickel (Ni), titanium (Ti), and manganese (Mn) Prepare a steel sheet containing at least one. The steel sheet may also include other elements such as carbon (C), silicon (Si), phosphorus (P), sulfur (S), and aluminum (Al).

It is preferable that content of B in a hardenability improvement element is 0.0005 weight%-0.005 weight%, respectively. It is because the hardenability improvement effect which B contains below 0.0005 weight% is not big, and when B contains more than 0.005 weight%, toughness can be reduced. More preferably, it does not exceed 0.003% by weight, because if it exceeds a large amount of precipitates called Fe ₂₃ (BC) ₆ is precipitated to harden the material and rather hardenability.

Since Mn is an effect of improving hardenability as an element for improving hardenability, Mn should be added by 0.2 wt% or more, but when added in 2.0 wt% or more, workability deteriorates. Therefore, it is preferable that content of Mn is 0.2 weight%-2.0 weight%.

Ti should be added at least 0.005% by weight in order to prevent the precipitation of B added to improve the hardenability by precipitating nitrogen in the steel with TiN to prevent precipitation into BN, but when 0.15% by weight or more is added, precipitates other than TiN Impact impact. Therefore, it is preferable that content of Ti is 0.005 weight%-0.15 weight%.

Cr is added in an amount of 0.2% by weight or more in order to help improve the hardenability of B during quenching, but the effect is saturated and causes a cost increase even when 2.0% by weight or more is added. Therefore, it is preferable that content of Cr is 0.2 weight%-2.0 weight%.

Mo, V, and Ni are added as 0.002% by weight or more as a hardenable complement element, but even when 1.0% by weight or more is added, the effect is saturated and causes a cost increase. Therefore, it is preferable that content of Mo, V, and Ni is 0.002 weight%-1.0 weight%, respectively.

In the case of C, when the content is more than 0.60% by weight, the material may be hardened, resulting in poor weldability and weldability, and may also reduce impact resistance of the product after quenching. When the C content is less than 0.01% by weight, hardenability is insufficient, so it is difficult to obtain the hardness or strength required after hardening and tempering.

In the case of other elements, it is generally preferable to maintain the following contents, but the present invention is not necessarily limited thereto.

Since Si has a high solid solution hardening effect and improves hardenability, it should be added in an amount of 0.01% by weight or more, but when it is 1.0% by weight or more, the surface of the hot rolled sheet is bad and the micronization effect of the structure is saturated.

Since P causes brittleness during tempering, the impact resistance is significantly deteriorated. Therefore, the P content is preferably limited to 0.03% by weight or less.

When S is an impurity of 0.03% by weight or more, the amount of nonmetallic inclusions is increased to lower the impact resistance, so S is limited to 0.03% by weight or less.

      Al is added for the purpose of deoxidation of the steel, but if it is less than 0.005% by weight, the deoxidation effect is less. When the Al content is added in excess of 0.2% by weight or more, Al decreases the cleanliness by the formation of oxides, thereby reducing the impact resistance.

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

In the above, the content of the steel sheet-containing element was described, but the present invention is not limited thereto. Of course, the content may be adjusted in consideration of characteristics required for the seat rail for automobile parts.

The hardenability enhancing elements such as chromium, molybdenum, boron, vanadium, nickel and the like improve the hardenability of the steel sheet so that the main structure of the steel sheet may be martensite after the press hardening step (ST50). This will be described in more detail in the press curing step ST50.

Such steel sheet may be a hot rolled steel sheet or a cold rolled steel sheet.

Subsequently, the steel sheet is blanked and pierced according to the desired shape in the blanking-piercing step ST20. Blanking and piercing may be performed out of order or simultaneously. In addition, if the process performs the same function as blanking or piercing, it is a matter of course that it can be interpreted to represent such a process, without being limited to a term.

Subsequently, in the rapid heating step ST30, the steel sheet is rapidly heated to a temperature corresponding to the austenite region. At this time, the steel sheet is preferably heated to a temperature of 800 ° C to 1000 ° C in view of the temperature drop in the rapid transfer step ST40.

It is preferable to use a high frequency induction heating method in which a steel sheet is placed in a high frequency induction furnace and heated for rapid heating. The high frequency induction heating method does not need to control the gas atmosphere inside the furnace, and has a merit of shortening the heat treatment time since rapid heating is possible.

However, the present invention is not limited thereto, and of course, a batch furnace using electricity or gas as a heat source for heating the steel sheet can be used continuously, such as a rotary furnace or the like.

Subsequently, the steel sheet is rapidly conveyed to the press hardening facility in the rapid conveyance step ST40. When the transfer time of the steel sheet is long, the temperature of the steel sheet is lowered, so that ferrite, pearlite, bainite, etc. may be generated inside the automobile seat rail after press hardening, thereby reducing the strength. Therefore, in consideration of the components of the steel sheet, it is preferable to transfer the steel sheet at a speed that can prevent the decrease in strength.

In other words, it is preferable to transfer the steel sheet at a speed within the extent that no pearlite or ferrite phase is formed, and more preferably at the fastest speed possible. Considering the cooling rate in air, it is preferable to transfer within about 10 seconds.

Here, the steel sheet may be transferred by a robot or manually. However, the present invention is not limited thereto, and the steel sheet may be transferred in various ways.

칭하는 것을 말하며, 당업계에서는 프레스 담금질, 프레스

칭, 다이

칭, 열간 프레스 성형, 핫 프레스 포밍 등으로 불리우기도 한다. Subsequently, in the press hardening step ST50, a steel sheet is molded from a press mold to form an automobile seat rail having a predetermined shape. Here, press hardening refers to press hardening the steel sheet at a high temperature with low strength and excellent ductility, and simultaneously to form the steel sheet by a cooled mold.

Refers to, in the art press quenching, press

Ching, die

It may also be referred to as hot pressing, hot press forming, or the like.

칭하는 방법이 개시되어 있다. 이에 개시된 것처럼 종래 프레스

칭 방법은 강판에 대한 급냉 성형 방식으로 사용되어 왔으나, 본 발명에서의 시트레일과 같이 프레스면으로 단순히 접촉하여 냉각할 수 없는 구조의 부품 성형에는 구조적 특성상 이러한 방법이 사용되지 못했다.Steel plate is pressed in Patent Publication No. 2002-12644 or Japanese Patent Publication No. 2003-231915

A method of calling is disclosed. Conventional press as disclosed herein

The quenching method has been used as a quenching method for steel sheets, but such a method has not been used for forming a part having a structure in which the sheet rail in the present invention cannot be cooled simply by contact with a press surface.

칭하기 위하여 다음과 같은 냉각 방법이 적용될 수 있다. In the present invention, the seat rail having an inner surface not in contact with the press surface is formed together with press molding.

The following cooling method may be applied to refer to.

칭 방법에서 일부 개시된 내용이다. 그러나, 강판과 달리 시트레일과 같이 그 내면이 냉각된 프레스면에 접할 수 없는 형상을 갖고 있는 경우 금형의 접촉에 의한 냉각만으로는 냉각효과를 기대하기 어렵다. 또한, 금형의 냉각효과를 높이기 위해, 냉각 물질의 순환구조를 시트레일의 형상에 따라 복잡하게 구성하는 것도 경제적인면이나 실질적인 면에서 바람직하지 못하다.First, there is a method of press molding while circulating a cooling material in a mold. This is a conventional press

Some of the disclosures in the method are described. However, unlike steel sheets, when the inner surface of the sheet rail has a shape that cannot be in contact with the cooled press surface, it is difficult to expect a cooling effect only by cooling by contact of the mold. In addition, in order to increase the cooling effect of the mold, it is not economical or practical in terms of complicated configuration of the circulation structure of the cooling material according to the shape of the seat rail.

칭한다. 이로써, 금형 표면에 형성된 다수의 작은 노즐을 통하여 냉각물질이 시트레일에 계속하여 분사됨으로써 냉각효과를 더욱 높일 수 있다. 이는 같은 기온하에서도 바람이 부는 곳에서 물체의 냉각속도가 더 빠른 원리와 같다고 볼 수 있다. 즉, 찬 공기 중에서 물체가 냉각되는 경우보다 찬 공기가 물체에 계속 부딪치면서 물체주위에 높아진 공기를 찬 공기로 계속 대체하는 경우가 더 빠른 냉각효과를 나타내는 것과 유사한 것이다. 이러한 방식에 의해 냉각효과가 향상되게 된다.Therefore, in the present invention, the sheet rail is pressed while injecting the cooling material into the seat rail through a small nozzle on the surface of the mold together with the circulation of the cooling material into the mold.

It is called. As a result, the cooling material is continuously sprayed onto the seat rail through the plurality of small nozzles formed on the mold surface, thereby further increasing the cooling effect. This is similar to the principle that the cooling rate of an object is faster in the place where the wind blows even under the same temperature. In other words, cold air continuously hits an object and cold air is replaced by cold air continuously while the object is cooled in the cold air. In this way, the cooling effect is improved.

Here, the cooling material refers to materials such as cooling water and cooling oil.

In this embodiment, by applying press hardening, the steel sheet is formed at a high temperature having low strength and excellent ductility, thereby easily forming a high strength steel sheet. That is, an automobile seat rail can be manufactured using a high strength steel sheet, thereby improving the strength of the automobile seat rail.

칭하여, 자동차 시트 레일의 주조직이 높은 강도의 마르텐사이트가 되도록 한다. 이에 자동차 시트 레일의 강도를 보다 향상시킬 수 있다. In addition, in the present embodiment, a steel sheet having excellent hardenability is used.

In other words, the main structure of the automobile seat rail is a high strength martensite. This can further improve the strength of the vehicle seat rail.

칭이 이루어지므로 금형이 자동차 시트 레일의 열변형 및 이에 따른 뒤틀림을 효과적으로 방지한다. 결과적으로 본 실시예에 따르면 우수한 형상의 자동차 시트 레일을 제조할 수 있다. 자동차 시트 레일이 상온에 도달한 후에 금형에서 취출하는 것이 바람직하지만, 생산성 향상을 위해 오스테나이트에서 마르텐사이트로의 변태가 완료된 온도 직하에서 자동차 시트 레일을 취출하는 것도 무방하다. When press hardening is completed, the car seat rail is taken out of the mold of the press hardening facility. In this embodiment, inside the mold

As the mold is made, the mold effectively prevents thermal deformation and consequent distortion of the car seat rail. As a result, according to this embodiment, an automobile seat rail of excellent shape can be manufactured. Although it is preferable to take out from a metal mold | die after the car seat rail reaches normal temperature, it is also possible to take out a car seat rail just under the temperature which the transformation from austenite to martensite is complete for productivity improvement.

Subsequently, a tempering step ST60 may be further performed to temper the vehicle seat rail. Automotive seat rails can be used without tempering but can be tempered at low temperatures when high toughness is required. The tempering temperature is preferably 150 ° C. to 400 ° C. so as to increase toughness without a large decrease in strength. However, the present invention is not limited thereto, and the tempering temperature can be appropriately adjusted according to the components of the vehicle seat rail.

The tensile strength of the high-strength car seat rail according to the present invention thus produced is 1500MPa to 1700MPa, it can be seen that it is very excellent about 1.5 to 4 times the tensile strength of the car seat rail manufactured by the prior art. As described above, since the tensile strength is excellent, an automobile seat rail may be manufactured from a thin steel sheet, and the weight of the automobile seat rail may be effectively reduced.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the scope of the invention.

As described above, according to the manufacturing method of the automobile seat rail according to the present invention, since the steel sheet is formed at a high temperature having low strength and excellent ductility using press hardening, a high strength steel sheet can be easily formed. That is, the vehicle seat rail can be manufactured from a high strength steel sheet, thereby improving the strength of the vehicle seat rail.

칭함으로써 자동차 시트 레일의 주조직이 마르텐사이트가 되도록 하여 제조된 자동차 시트 레일의 강도를 좀더 향상시킬 수 있다. 프레스 경화 이후에 템퍼링을 수행하여 해당 자동차 시트 레일의 인성을 향상시킬 수 있다. And the steel sheet excellent in hardenability

In this case, the main structure of the car seat rail is made martensite, so that the strength of the manufactured car seat rail can be further improved. Tempering after press hardening can improve the toughness of the vehicle seat rail.

칭하므로, 열변형 현상을 방지하여 자동차 시트 레일이 우수한 형상을 가질 수 있다. Steel plate inside the mold of press hardening equipment

Therefore, it is possible to prevent the heat deformation phenomenon, the vehicle seat rail can have an excellent shape.

In addition, by applying various cooling methods, even the inner surface not in contact with the press surface can be uniformly cooled, and by obtaining a uniform martensite structure, the strength of the sheet rail for parts can be further improved.

On the other hand, since the automobile seat rail manufactured by the manufacturing method of the present invention is very excellent in strength, it is possible to reduce the thickness of the steel sheet constituting the automobile seat rail, and as a result, it is possible to greatly reduce the weight of the automobile seat rail. Applying such a lightweight car seat rail to a car can improve the fuel efficiency of the car and reduce the exhaust gas, thereby contributing to environmental protection.

Claims (8)

(a) preparing a steel sheet containing at least one element selected from the group consisting of chromium (Cr), molybdenum (Mo), boron (B), vanadium (V), and nickel (Ni); (b) forming the steel sheet into a basic shape through a process including blanking and piercing; (c) heating the steel sheet to a temperature corresponding to an austenite region; (d) rapidly transferring the steel sheet to the press mold at a speed within which no pearlite, ferrite or bainite phases are formed; And (e) rapidly cooling the steel sheet in a press mold and simultaneously forming the sheet into an automobile seat rail having a predetermined shape; Including; In the step (e), the press mold is a manufacturing method of the high strength automobile seat rail, characterized in that the cooling material is circulated therein and the cooling material is injected into the steel sheet through the nozzle of the surface of the press mold. delete delete The method of claim 1, In the step (c), the steel sheet is heated to a temperature of 800 ℃ to 1000 ℃ manufacturing method of high strength automobile seat rail. The method of claim 1, In the step (b), the steel sheet is a high-frequency induction heating furnace, batch (batch), a continuous method of manufacturing a high strength car seat rail, characterized in that the heating in any one furnace selected from the group consisting of a rotary furnace. The method of claim 1, After step (e), The method of manufacturing a high-strength car seat rail further comprises the step of tempering the car seat rail at 150 ℃ to 400 ℃. delete A high strength automobile seat rail manufactured by the method for producing a high strength automobile seat rail according to any one of claims 1 and 4 to 6, wherein the tensile strength is 1500 MPa to 1700 MPa.

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