KR20180074469A - Method for manufacturing stabilizer bar - Google Patents

Abstract

Disclosed is a method for manufacturing a stabilizer bar. The present invention comprises: a step of firstly applying of a sealing solution to both ends of a pipe; a step of heating the pipe to which the sealing solution is applied, pressing the both ends of the pipe to form a plate, and forming a press processing unit; a step of drilling a hole in the press processing unit; and a step of secondly applying the sealing solution to the hole-punched press processing unit, followed by drying. The sealing solution includes: an acrylic-urethane copolymer resin; a phenoxy resin; a silane compound; thio-urea; and titanium carbonate.

Description

[0001] METHOD FOR MANUFACTURING STABILIZER BAR [0002]

The present invention relates to a method for manufacturing a stabilizer bar.

Automotive chassis components, such as stabilizer bars, are among the components that require excellent fatigue durability and corrosion resistance. These parts are generally applied as final parts through various forming process and heat treatment process using a hot-rolled steel material as a base material. In many cases, in this molding and heat treatment process, water and acid solution penetrate into the pipe, Hydrogen ions or hydrogen atoms generated as a result of corrosion are concentrated on the grain boundaries of the hot-rolled steel material as the base material, causing intergranular corrosion or grain boundary embrittlement, and fatigue durability of parts is remarkably deteriorated. There was a problem of premature abortion. Prior arts for solving such problems include Patent Documents 1 to 3 and the like.

Korean Patent Publication No. 10-2012-0037586 Korean Patent Laid-Open No. 10-2011-0012895 Korean Patent Registration No. 10-1547599

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a stabilizer bar for sealing a hollow portion of a stabilizer bar so as to be completely watertight. will be.

One aspect of the present invention relates to a method of manufacturing a pipe, comprising the steps of: applying a sealing solution to both ends of a pipe; heating the pipe to which the sealing solution is applied; pressing both ends of the pipe; A step of punching a hole in the press-working part, a step of applying a sealing solution to the hole-punched press part secondarily and then drying the sealing solution, wherein the sealing solution is an acrylic-urethane copolymer resin, The present invention provides a method for producing a stabilizer bar comprising a resin, a silane compound, thio-urea, and titanium carbonate.

As one of various effects of the present invention, the stabilizer bar manufactured according to the present invention is advantageous in that the hollow portion is completely sealed and the water tightness is excellent.

In addition, the sealing solution used in the present invention can be applied to the sealing of steel materials having various compositions and shapes without causing volatilization at high temperatures as well as causing hot shortness in steel materials.

In addition, the sealing solution used in the present invention has a short drying time and can minimize the time required for sealing. Thus, there is an advantage that productivity can be maximized in manufacturing the stabilizer bar.

It is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

An example of a manufacturing process of a normal stabilizer bar will be described below.

First, a hot-rolled pipe having a hollow portion as a base material is prepared as a base material for manufacturing a stabilizer bar, both side ends of the hot-rolled pipe are heated, and the heated both end portions are pressed to form a plate to form a pressed portion . Thereafter, a hole is drilled in one side of the central portion of the press-working portion, and the end of the press-working portion is cut so as to have a shape of eye part.

However, even if the eye part of the stabilizer bar manufactured by a conventional method is pressed and pressed, a gap is formed between the upper and lower contact surfaces of the eye part to be in contact with each other. Therefore, as described above, The water and the acid solution penetrate into the pipe through the gap of the eye part to cause corrosion on the inner wall of the pipe and hydrogen ions or hydrogen atoms generated as a result of corrosion are concentrated on the grain boundaries of the hot- Causing fatigue durability of the component remarkably, and there is a problem of premature cutting during use.

In view of the above, the inventors of the present invention have studied in detail to solve such a problem. As a result, through the combined control of the sealing method, the composition of the sealing solution and the composition of the hot-rolled pipe as the basic material of the stabilizer, And the present invention has been completed.

Hereinafter, a method of manufacturing the stabilizer bar, which is one aspect of the present invention, will be described in detail.

First, the sealing method will be described in detail.

As described above, in the stabilizer bar, after heating the pipe, both ends of the stabilizer bar are press-processed and pressed into a plate shape to form a press-processed portion; Pressing the both end portions in a plate shape to form a press working portion; In order to effectively seal the hollow portion of the stabilizer bar, a sealing solution is first applied to both end portions of the pipe before heating the pipe, It is necessary to apply the sealing solution twice in total, that is, to apply the sealing solution secondarily to the press-processed portion where the rear hole is perforated. In this case, a separate drying step is not required due to the subsequent pipe heating step in the primary coating step.

The reason for applying the sealing solution twice in this manner is to form a hardened coating layer on both the inner wall and the outer wall of the stabilizer hollow portion. Therefore, if only the first application or only the second application is performed, Can be difficult.

On the other hand, in general, when the pipe is heated, the pipe is heated to a high temperature of 800 to 1000 ° C, which completely transforms the microstructure of the ferrite into the austenite structure and, in the subsequent pressing process, And to ensure the physical properties of the final product by minimizing the formation of the tissue.

However, in the present invention, the sealing solution is first applied to both end portions of the pipe prior to heating the pipe. The sealing solution is not easily volatilized at a heating temperature of 800 to 1000 ° C, It is necessary not only to have a sufficient viscosity but also to select a composition which does not cause a high temperature cracking defect on the inner wall of the pipe and does not react with the pipe. In addition, it is necessary to select a composition having a short curing time so that the sealing does not take too much time.

Hereinafter, components and preferable content ranges of the sealing solution which can be preferably applied to the present invention will be described in detail. It should be noted, however, that this is a preferable example, and it is not necessary to satisfy the following content ranges. On the other hand, the content of each component to be described below is all based on weight unless otherwise specified.

The sealing solution applied to the stabilizer bar manufacturing method of the present invention may include a main resin, an inorganic additive and a solvent, and more specifically, an acrylic-urethane copolymer resin, a phenoxy resin, a silane compound, a thio-urea, Carbonates. On the other hand, if necessary, it may further comprise at least one of vanadium phosphate, Zr compound, silica and zinc phosphate. The solvent may be distilled water, methanol, ethanol, isopropanol, 2-methoxyethanol, dimethylformamide, butanol, pentanol, Hexanol (Hexanol), and heptanol (Heptanol), but the present invention is not limited thereto.

Acryl-urethane copolymer resin

The acrylic-urethane copolymer resin functions as a binder without impairing the dispersibility of the inorganic additive, and is very effective in improving the compactness of the sealing material. More specifically, the urethane emulsion and the acrylic emulsion immediately before the completion of the synthesis are mixed with TEA (triethylamine) at a temperature of 80 ° C, And then mixing them.

In order to obtain the technical effect desired in the present invention, it is preferable that the content is 12 wt% or more based on the solid content excluding the solvent. If it is less than 12%, the tightness of the sealing material may be insufficient and the sealing effect may not be sufficient. On the other hand, if the content thereof is too large, the effect of improving the physical properties due to the addition is insufficient, so that the content thereof is preferably controlled to 36% or less.

On the other hand, as the weight average molecular weight (Mw) of the acryl-urethane copolymer resin is lower, the crosslinking density becomes dense but the stability of the inorganic additive can be deteriorated. The control of the weight average molecular weight of the phenoxy wax resin is important Element. If the weight average molecular weight is less than 40,000, precipitation of the inorganic additive may occur. If the weight average molecular weight exceeds 90,000, it may be difficult to secure the desired sealing effect. In consideration of this, the weight average molecular weight (Mw) of the acrylic-urethane copolymer resin is preferably controlled to 40,000 to 90,000, more preferably 65,000 to 70,000.

Phenox Watches Resin

The phenoxy resin serves to prevent delamination of the sealant due to curing shrinkage which may be caused by various heat treatments experienced during the manufacture or use of the components in which the sealant is formed.

In order to secure the technical effect aimed at in the present invention, it is preferable that 8 wt% or more based on the solid content excluding the solvent is included. If it is less than 8% by weight, the effect of preventing delamination may not be sufficient. On the other hand, even if the content thereof is too large, the effect of improving the physical properties due to the addition is insufficient, so that the content thereof is preferably controlled to 24% or less.

On the other hand, the phenoxy resin is preferably a phenoxy-nano-silicate composite resin. Such a composite resin can be prepared by adding a nano-silicate in the process of synthesizing a phenoxy resin. When the phenoxy resin includes nano-silicate, the corrosion resistance of the sealing material is improved and the sealing effect can be further maximized.

In this case, the amount of the nanosilicate is preferably 1.0 to 3.0% by weight. If the content of the nano-silicate is less than 1.0 wt%, the effect of improving the corrosion resistance of the sealing material may be insufficient, while if it exceeds 3.0 wt%, the solution stability of the composition may deteriorate.

On the other hand, the lower the weight average molecular weight (Mw) of the phenoxy resin is, the higher the crosslink density becomes, but the stability of the inorganic additive can be deteriorated. Thus, the control of the weight average molecular weight of the phenoxy resin is an important factor in the present invention . If the weight average molecular weight is less than 40,000, precipitation of the inorganic additive may occur. If the weight average molecular weight exceeds 90,000, it may be difficult to secure the desired sealing effect. In consideration of this, the weight average molecular weight (Mw) of the phenoxy resin is preferably controlled to 40,000 to 90,000, more preferably 74,000 to 82,000.

Silane compound

The silane compound improves the water repellency of the sealing material and prevents penetration of the corrosive factors.

In order to secure the desired technical effect in the present invention, it is preferable that 36 to 78% of the solids content is included. If it is less than 36%, the effect of improving the water repellency may be insufficient, while if it exceeds 78%, the solution stability may be deteriorated.

On the other hand, epoxy silanes, chloro silanes, amino silanes, acrylic silanes, vinyl silanes and the like are widely known as silane compounds. In the present invention, alkoxy silanes and at least one silane among vinyl and epoxy compounds In a ratio of 1: 0.85 to 1: 7.15. In this case, the water repellency of the sealing material and the solution stability of the composition can be most effectively achieved.

Thio-urea

Thio-urea is a curing accelerator and plays a role in shortening the time required for curing the sealing material.

In order to secure the technical effect aimed at in the present invention, it is preferable that the content is in the range of 0.5 to 7% based on the solid content excluding the solvent. If it is less than 0.5%, the effect of shortening the curing time of the sealing material may not be sufficient. On the other hand, if it exceeds 7%, the solution stability of the composition may deteriorate.

Titanium carbonate

Titanium carbonate serves as a coupling agent between the main resin and the inorganic additive, together with improvement of the stability of the composition.

In order to secure the desired technical effect in the present invention, it is preferable that 0.5% or more is contained based on the solid content excluding the solvent. If it is less than 0.5%, the effect may not be sufficient. On the other hand, if the content is too large, the effect of improving the physical properties due to the addition is insufficient, so that the content thereof is preferably controlled to 3.4% or less.

Vanadium phosphate

Vanadium phosphate plays a role in chemically preventing the penetration of corrosive factors and improves the sealing effect of the sealing material. However, even if vanadium phosphate is not added, there is no problem in securing desired physical properties. On the other hand, if the content exceeds 11%, the appearance of the steel material changes under high temperature and high humidity atmosphere, which may cause a blackening phenomenon. Therefore, the upper limit of the content is limited to 11%.

Zr compound

Zr compound also plays a role of chemically preventing the penetration of corrosive factors to improve the sealing effect of the sealing material. However, even if the Zr compound is not added, there is no problem in securing the desired properties. On the other hand, when the content exceeds 4%, the effect of improving the sealing effect against the input amount is insignificant, so the upper limit of the content is limited to 4%.

Silica

Silica also plays a role in chemically preventing the penetration of corrosive factors to improve the sealing effect of the sealing material. However, even if silica is not added, there is no problem in securing desired physical properties. On the other hand, if the content exceeds 3% by weight, the solution stability may be deteriorated, so that the upper limit of the content is limited to 3% by weight.

Zinc phosphate

Zinc phosphate also plays a role in chemically preventing penetration of corrosive factors to improve the sealing effect of the sealing material. However, even if zinc phosphate is not added, there is no problem in securing desired physical properties. On the other hand, when the content exceeds 1.5% by weight, the effect of improving the sealing effect with respect to the input amount is insignificant, so that the upper limit of the content is limited to 1.5% by weight.

Hereinafter, the alloy components and preferable content ranges of the hot-rolled pipe as the basic material of the stabilizer will be described in detail. It should be noted, however, that this is a preferable example, and it is not necessarily satisfied with the following composition. On the other hand, it is to be noted in advance that the content of each component described below is based on the weight, unless otherwise specified.

C: 0.2 to 0.5%

C is an element which forms a carbide in the steel or is dissolved in ferrite and contributes to the improvement of the strength of the hot-rolled pipe. In order to secure the target strength of the stabilizer bar, it is necessary to include 0.2% or more. However, if the content is excessive, the weldability may be deteriorated, and the upper limit of the present invention is limited to 0.5%.

Mn: 0.6 to 1.8%

Mn is an element that increases the hardenability of the steel, which enhances the austenite stability and facilitates the formation of the low temperature transformation phase, thereby increasing the strength of the hot-rolled pipe. In order to obtain such effects in the present invention, it is necessary to include 0.6% or more. However, if the content is excessive, the strength may be excessively increased or the pipe toughness may be deteriorated due to the manganese segregation, which may cause processing cracks. In order to prevent the occurrence of such a crack, it is preferable that the content is 1.8% or less.

Si: 0.3% or less (excluding 0%)

Silicon increases ferrite hardening and carbide formation to increase residual austenite stability and increase the ductility of hot rolled pipes. However, if the content is excessive, the surface roughness of the hard coating may be reduced, thereby deteriorating the surface quality of the hot-rolled steel sheet and causing a bare spot during hot-dip coating. In order to prevent such surface quality deterioration and unplated occurrence, it is preferable that the content is 0.3% or less.

Al: 0.05% or less (excluding 0%)

Al is an element that contributes to improvement of ductility of a steel sheet by improving the cleanliness of steel by reacting with oxygen in steel and increasing the stability of retained austenite by suppressing formation of carbide in steel. However, if the content is excessive, AlN is formed by reacting with nitrogen in the steel, and slab cracking may be caused in the manufacture of thin slabs, thereby deteriorating the quality of the slab or hot-rolled pipe. In order to prevent the deterioration of quality and the like, it is preferable that the content is 0.05% or less.

P: 0.02% or less (excluding 0%)

P contributes to the strength improvement of the hot-rolled pipe. However, if the content is excessive, it may be formed at grain boundaries and / or intergranular grain boundaries during performance and rolling, resulting in brittleness, and may be segregated at the manganese segregation position of the hot-rolled pipe welded portion to cause high temperature cracking. In order to prevent this, it is necessary to limit the upper limit to 0.02% or less.

S: not more than 0.004%

S is an impurity inevitably contained in steel, which causes surface defects on the slab and causes deterioration of ductility and weldability of the steel sheet. In addition, it is preferable to control the content to be as low as it is an element which is combined with Mn in the steel to form MnS non-metallic inclusions, segregates during the performance solidification and causes high temperature cracks. In theory, it is advantageous to limit the content of S to 0%, but it is inevitably contained inevitably in the manufacturing process. Therefore, it is important to manage the upper limit, and in the present invention, the upper limit of the S content is controlled to 0.004%.

N: 0.01% or less (excluding 0%)

N is an austenite stabilization and nitride forming element. However, the nitrogen element dissolved in the steel may react with the alloy element forming the precipitate to reduce the content of the precipitation element required for precipitation strengthening, resulting in a decrease in strength. Therefore, in the present invention, it is preferable to control the content of nitrogen to 0.01% or less.

Total tram element (Ca + Sn + Sb): not more than 0.05%

The tram element (Ca, Sn, Sb) is an impurity element derived from scrap used as a raw material in a steelmaking process. When the content of the tramp element is excessively large, surface cracks of the slab may occur and the surface quality of the hot- It is preferable to control the content to be as low as possible. In the present invention, the sum of the tramp element contents is controlled to 0.05% or less.

The rest of the composition is Fe. However, it is not possible to exclude inevitable impurities that are not intended from the raw material or the surrounding environment in a conventional manufacturing process, since they may be inevitably incorporated. These impurities are not specifically referred to in this specification, as they are known to one of ordinary skill in the art.

On the other hand, addition of an effective component other than the above-mentioned composition is not excluded, and it may further include, for example, Ti, B and the like.

Ti: 0.08% or less (excluding 0%)

Ti is an element which forms precipitation (TiC, TiCN, TiNbCN) and increases the strength of steel. However, if the content exceeds 0.08%, the cost of producing hot-rolled steel sheet may increase, or the yield or the tensile strength may be drastically increased. In addition, This can lead to poor machining during pipe forming.

B: 0.005% or less (excluding 0%)

B is an element that increases the hardenability of steel. When added in an appropriate amount, ferrite formation is inhibited and is effective for increasing the hardenability. However, when the content is excessive, the austenite recrystallization temperature is increased and the weldability is deteriorated. On the other hand, in the present invention, since the steel sheet is produced from the electric furnace molten steel, the solid nitrogen content in the steel is high, so that the precipitation strengthening effect by the precipitate forming element can be reduced. Boron (B) is added to form nitrides by reacting with nitrogen dissolved in the steel to increase the precipitation strengthening effect of the steel sheet and to maintain the hardenability of the steel, thereby ensuring proper strength and workability.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the description of these embodiments is intended only to illustrate the practice of the present invention, but the present invention is not limited thereto. And the scope of the present invention is determined by the matters described in the claims and the matters reasonably deduced therefrom.

( Example )

First, a hot-rolled pipe having the composition shown in the following Table 1 was prepared, heated at 900 占 폚 for 20 seconds, pressed at both ends thereof, pressed to form a press-formed portion, and then holes were drilled in the press- A stabilizer bar was produced. In the stabilizer bar manufacturing process, the sealing of the stabilizer bar was attempted using a sealing solution having the composition shown in Table 2, and in each example, only whether the primary sealing and the secondary sealing were performed was different. On the other hand, after the secondary sealing, the PMT (peak metal temperature) was heated to 140 ° C using an induction heater and baked for 2 minutes.

Each of the stabilizer bars thus manufactured was subjected to watertightness evaluation and air permeability evaluation. More specifically, for the watertightness evaluation, water was poured into the pipe through the opposite end of the compression molding section of the stabilizer, and whether or not the water seeped out through the gap between the compression molding sections was visually confirmed. , NG when water droplets were generated, and one end of the stabilizer compression molded part was immersed in water for evaluation of air permeability, and strong air pressure was injected through the opposite end part to visually check whether or not the air was discharged out of the gap between the compression molded parts. The results were evaluated as GO when no air permeation occurred and NG when air permeation occurred. The results are shown in Table 3 below.

Steel grade Alloy composition (% by weight) C Si Mn P S Al N B Ca + Sn + Sb A 0.22 0.15 1.15 0.011 0.001 0.01 0.0045 - 0.05 or less B 0.36 0.3 1.5 0.010 0.002 0.05 0.0075 0.0020 0.05 or less

ingredient Acryl-urethane copolymer resin Phenox Watches Resin Silane compound Thio-urea Titanium carbonate Content (% by weight) 30 20 42 5 3

No. Steel grade Primary sealing
Implementation Secondary sealing
Implementation Water tightness evaluation Air permeability evaluation Remarks One A O O GO GO Inventory 1 2 A O X NG NG Comparative Example 1 3 A X X NG NG Comparative Example 2 4 B O O GO GO Inventory 2 5 B O X NG NG Comparative Example 3 6 B X O NG NG Comparative Example 4

As can be seen from Table 3, Inventive Examples 1 and 2 satisfying all the conditions proposed in the present invention were found to be excellent in watertightness and air permeability. On the contrary, in the case of Comparative Examples 1 to 4 in which only the primary sealing or the secondary sealing was performed, both watertightness and air permeability were inferior.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

Claims (6)

Firstly applying a seal solution to both end portions of the pipe;
Heating the pipe to which the sealing solution is applied, pressing the both ends of the pipe to form a plate, and forming a press-working portion;
Drilling a hole in the press working portion;
Applying a sealing solution secondarily to the hole-punched press-processed portion, and then drying the sealing solution,
Wherein the sealing solution comprises an acrylic-urethane copolymer resin, a phenoxystyrene resin, a silane compound, thio-urea, and titanium carbonate.
The method according to claim 1,
Wherein the heating temperature of the pipe to which the sealing solution is applied is 800 to 1000 占 폚.
The method according to claim 1,
Wherein the pipe is composed of 0.2 to 0.5% of C, 0.6 to 1.8% of Mn, 0.3% or less of Si (excluding 0%), 0.05% or less of Al (excluding 0% %), S: not more than 0.004%, N: not more than 0.01% (excluding 0%), the total tram element (Ca + Sn + Sb): not more than 0.05%, the balance Fe and other unavoidable impurities .
The method of claim 3,
Further comprising at least one of Ti: not more than 0.08% (excluding 0%) and B: not more than 0.005% (excluding 0%).
The method according to claim 1,
Wherein the sealing solution contains a main resin, an inorganic additive, and a solvent, and contains 12 to 36 wt% of an acryl-urethane copolymer resin, 7 to 24 wt% of a phenoxy resin, 7 to 24 wt% of a silane compound, 0.5 to 7% by weight of thio-urea, and 0.5 to 3.5% by weight of titanium carbonate, based on the total weight of the stabilizer bar.
6. The method of claim 5,
Zr compound: 4 wt% or less (excluding 0 wt%), silica: 3 wt% or less (excluding 0 wt%) and zinc phosphate: 1.5 wt% (excluding 0 wt%), vanadium phosphate: 11 wt% % Or less (excluding 0% by weight) of the stabilizer bar.