KR101322634B1 - Manufacturing method of disk type spring for vehicle using boron steel - Google Patents

Abstract

PURPOSE: A method for manufacturing a vehicle disc type spring is provided to satisfy material properties required for the vehicle disc type spring, to reduce manufacturing costs, and to improve productivity. CONSTITUTION: A method for manufacturing a vehicle disc type spring includes the following steps of: plate-processing a flat plate of boron steel; heat-treating the blanked flat plate at a temperature of 900-1000°C; rapidly cooling the heated flat plate while bending-processing the flat plate at a pressure of 15-30 ton/m; heat-treating the tempered flat plate at a temperature of 280-370°C; and air-cooling the heat-treated flat plate. The boron steel comprises 0.47-0.53 wt% of C, 0.15-0.35 wt% of Si, 0.5-0.9 wt% of Mn, 0.01-0.03 wt% of P, 0.01-0.03 wt% of S, 0.03-0.13 wt% of Cr, 10-30 ppm of B, and the rest of Fe and unavoidable impurities.

Description

Manufacturing method of disk type spring for vehicle using boron steel}

The present invention relates to a method for manufacturing a plate spring for a vehicle, and more particularly, to a method for producing a plate spring showing the physical properties applicable to the vehicle by using boron steel which is a low-cost material.

Dish-shaped springs are metal springs having a relatively large load capacity in a small space and are variously used in vehicles. For example, the dish spring may be used for a return spring for an automobile automatic transmission clutch, an application interposed between an automobile bumper and a vehicle body in a bumper stay, and the like. The following describes a dish type spring used as a return spring for a dual vehicle automatic transmission clutch.

In general, an automatic transmission of a vehicle is a device that converts the transmission ratio to follow the set shift pattern according to the opening state of the throttle and the change of the vehicle speed while driving. Not only that, but also smoothing the start, acceleration and deceleration to improve the ride comfort.

In the configuration of the automatic transmission, there is a planetary gear device that forms a predetermined gear train through a plurality of gears, and the planetary gear device has an input shaft or a transmission of the gear train and the transmission to form a plurality of gear stages when shifting. There are a number of friction elements that connect between the casings to selectively enforce power transmission and limiting operation.

The friction element is divided into a clutch and a brake, wherein the clutch is coupled to the transmission input shaft 1 in a slip joint manner as shown in FIG. 1 and a clutch retainer 2 installed to rotate integrally; A piston piston 6 provided to form a working hydraulic chamber 3 between the clutch retainer 2 and a piston retainer 6 provided to form a balanced hydraulic chamber 5 between the clutch piston 4. And the clutch retainer 2 and the clutch hub 7 between the clutch retainer 2 and the clutch hub 7 so as to transmit rotational power of the clutch retainer 2 to the clutch hub 7. The clutch piston 8 and the piston retainer 6 at both ends are provided so as to provide a resilient return force to the operation of the clutch piston 4 and the plurality of clutch plates 8 installed to connect. Is supported is configured to include the installed plate-shaped return spring (10).

Then, the clutch retainer 2 has a hydraulic pressure supply hole 2a for supplying operating oil to the hydraulic oil pressure chamber 3 side and a balance pressure supply hole for supplying balance oil to the balance hydraulic pressure chamber 5 side ( 2b) is formed.

When the clutch configured as described above is supplied with hydraulic pressure through the hydraulic pressure supply hole 2a to the hydraulic pressure chamber 3 so that the clutch piston 4 overcomes the force of the return spring 9 and moves toward the piston retainer 6. When the clutch piston 4 presses the clutch plate 8, the clutch plate 8 is frictionally engaged with each other by pressing the clutch piston 4, and thus the transmission input shaft 1 is applied. ) Power is transmitted to the clutch hub (7) via the clutch retainer (2) and clutch plate (8).

Then, when the hydraulic pressure is discharged from the working hydraulic chamber 3, the clutch piston 4 is returned to its original position by the restoring force of the return spring 9, and at the same time, the clutch plates 8 are in a non-contact state, so that the transmission input shaft 1 At this time, the rotational force is not transmitted to the clutch hub 7.

On the other hand, the plate-shaped return spring 10 that provides an elastic return force to the operation of the clutch piston 4 is formed in a circular ring shape plate portion 11 is fixed to the clutch piston 4, and the A plurality of elastic parts 13 are formed to be arranged at equal intervals along the inner circumferential surface of the plate part 11 and are installed to contact the piston retainer 6.

The elastic portion 13 is bent to protrude toward one side of the plate portion 11, one end is integrally connected to the inner peripheral surface of the plate portion 11 and the other end is radially toward the center of the plate portion 11 It has a structure formed to protrude.

The dish-type return spring 10 as described above is bulkier than the wave coil type return spring 21 as shown in FIG. 2 or the wire coil type return spring 23 as shown in FIG. Since it is possible to compact the clutch because of its small size, the use is increasing recently.

4 shows a conventional manufacturing method of the dish-type return spring 10 as described above.

That is, in the product design and analysis step (S1), the shape of the plate-shaped return spring corresponding to the finished product is designed and the spring performance according to the shape is analyzed, and in the next step, the shape production step (S2), According to the result, the plate material formed of a circular ring shape by processing a flat material made of steel material with a fine blanking press, and are disposed at equal intervals along the inner circumferential surface of the plate part 31. The primary semifinished product 30 having a plurality of protrusions 33 was produced.

In the first semi-finished product 30, the protrusion part 33 is a flat structure which does not protrude from the plate part 31, and one end of the protrusion part 33 is integrally connected to the inner circumferential surface of the plate part 31 and the other end thereof. Is a structure protruding radially toward the center of the plate portion 31.

In the first process step S3, the first burr generated in the first semi-finished product 30 in the shape manufacturing step S2 is removed by using a belt grinding machine. The surface roughness of the semi-finished product 30 will be increased.

In the second process step S4, which is a next process, the protrusion 33 of the first semi-finished product 30 is bent by using a bending machine, thereby protruding to one side from the plate part 41. The secondary semifinished product 40 having the elastic portion 43 was manufactured.

After the production is completed up to the second semi-finished product 40 is subjected to a restoration prevention step (S5) of fixing the elastic portion 43 by using a jig 50 to prevent the elastic portion 43 is restored.

That is, after the protrusion part 33 of the primary semifinished product 30 is processed by a bending machine at room temperature and manufactured into the elastic part 43 of the secondary semifinished product 40, the elastic part 43 is a plate part 41. Toward the shape will be restored.

If left unchecked, the plate-shaped return spring of the finished product has a problem that the defective rate is increased by decreasing the function as a spring by changing the shape of the elastic portion.

Therefore, after the secondary processing step (S4) to put the secondary semi-finished product 40 into the jig 50 consisting of the upper mold 51 and the lower mold 53 to prevent the restoration of the elastic portion 43, the upper mold ( 51 and the lower mold 53 are combined using a coupling member 55 such as a bolt and a nut, so that the elastic part 43 of the secondary semifinished product 40 is bent in the jig 50. It exists as it is.

Then, the process is a step of tempering the jig 50 including the secondary semifinished product 40 (S6), and after passing through the tempering step, the elastic part 43 of the secondary semifinished product 40 There is no restoring property so that the shape remains as it is bent.

In addition, after the tempering step, the residual stress remaining in the secondary semifinished product 40 is removed and at the same time, the mechanical properties are stabilized.

The next process is a shot peening step (S7) to improve durability and increase the surface roughness, and after completion of the shot peening step, the finished plate-shaped return spring 10 was produced.

However, in the conventional manufacturing method as described above, the process in which the protrusion part 33 of the primary semifinished product 30 is processed into the elastic part 43 of the secondary semifinished product 40 is performed at room temperature, thereby bending a large processing pressure. The machine can not only be used, because the bending machine with a large processing pressure as described above is expensive, there is a problem that the plate-shaped return spring 10 of the finished product is expensive. In addition, the conventional manufacturing method is to use a separate jig 50 to prevent the restoration of the elastic portion 43 of the secondary semi-finished product 40, thereby increasing the manufacturing cost and delay in working time due to the use of the jig 50 There was also a problem of reduced productivity.

On the other hand, in the manufacture of a plate spring for a vehicle, a sheet metal made of steel is generally used as a starting material. Steel refers to an iron-based alloy containing about 0.04 to 1.7% carbon. High-carbon alloy steel is used for special applications such as dish springs, for example, 0.47 to 0.53% carbon (C), silicon (Si) 0.15 to 0.40% by weight, manganese (Mn) 0.7 to 1.1% by weight, phosphorus (P) 0.03% by weight or less, sulfur (S) 0.01 to 0.03% by weight, chromium (Cr) 0.9 to 1.2% by weight, titanium (Ti) There is an alloy steel containing 0.02 to 0.06% by weight, vanadium (V) 0.1 to 0.2% by weight, remaining iron (Fe), and inevitable impurities. However, the high-carbon alloy steel generally used to manufacture the plate spring includes a large amount of expensive alloy elements such as chromium and vanadium, thereby increasing the manufacturing cost of the plate spring for a vehicle. In order to solve this problem, studies are being actively conducted to replace expensive high-carbon alloy steel with low-cost alloy steel as a starting material in manufacturing of a plate spring for a vehicle.

The present invention is derived from the above background, an object of the present invention is to provide a method for manufacturing a plate of the spring plate for the vehicle that can satisfy the physical properties required for the plate-shaped spring for the vehicle, and at the same time improve the productivity while reducing the manufacturing cost Is in.

The inventors of the present invention can reduce the manufacturing cost when using a sheet metal material made of borum steel in the manufacture of a plate spring for a vehicle, and adjust the process conditions while introducing a simple process to satisfy the physical properties required for a plate spring for a vehicle At the same time, the present invention has been completed by discovering that productivity can be improved.

In order to achieve the above object of the present invention, the present invention comprises the steps of: (a) blanking a flat material consisting of boron steel; (b) induction heating the blanked plate material to a temperature of 900 to 1000 ° C .; (c) die quenching the induction heated plate material at a pressure of 15 to 30 ton / m 2; And (d) tempering the die quenched flat material at a temperature of 280 to 370 ° C., wherein the boron steel is 0.47 to 0.53 wt% carbon (C) and 0.15 to 0.35 wt% silicon (Si). %, Manganese (Mn) 0.5-0.9 wt%, phosphorus (P) 0.01-0.03 wt%, sulfur (S) 0.01-0.03 wt%, chromium (Cr) 0.03-0.13 wt%, boron (B) 10-30 ppm , Provides a method for producing a plate-shaped spring for a vehicle, characterized in that the alloy steel containing the remaining iron (Fe) and inevitable impurities. In addition, a preferred example of the manufacturing method of the vehicular plate spring of the present invention may further comprise (e) peening the tempered flat plate material.

The manufacturing method of the vehicular plate spring of the present invention can significantly reduce the manufacturing cost because it uses a plate material made of low-cost boron steel as the starting material. In addition, the manufacturing method of the vehicular dish spring of the present invention can greatly improve the manufacturing process by greatly simplifying the manufacturing process, the process conditions are adjusted so that the physical properties required for the vehicular dish spring can be exhibited Hardness (Hardness) Rockwell C, HRC) is available for the manufacture of car springs of about 42-48.

1 is a view for explaining the clutch of the automatic transmission provided with a plate-type return spring,
2 and 3 are views of the wave coil type return spring and the wire coil type return spring,
4 is a view for explaining a conventional manufacturing method of a dish-type return spring,
5 is a view schematically showing a process sequence of a preferred example for producing a dish-like spring of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 5 is a view schematically showing a process sequence of a preferred example for producing a dish-like spring of the present invention. As shown in FIG. 5, the method for manufacturing a vehicular plate spring of the present invention comprises the steps of blanking in unit processes; Induction heating; Die quenching; And tempering, preferably, further comprising a peening step. Hereinafter, a description will be given of the method of manufacturing a plate spring for a vehicle of the present invention by dividing the unit processes separately.

Blanking ( blanking ) Steps

Blanking is a type of press processing in which sheet metal is processed into various forms using punches and dies. In the present invention, the blanking step consists of sheet metal working of the boron steel. At this time, the shape of the plate material after the blanking step may vary depending on the shape of the pre-designed dish spring, the shape corresponding to the planar structure of the shape designed by the blanking step is processed. For example, when the dish-type spring is a return spring for an automatic transmission clutch, the blanked plate material may include a plate portion formed in a circular ring shape and a plurality of protrusions disposed at equal intervals along the inner circumferential surface of the plate portion. At this time, the protrusion is a flat structure that does not protrude into the plate portion, one end of the protrusion is integrally connected to the inner peripheral surface of the plate portion, the other end is a structure formed radially protruding toward the center of the plate portion.

On the other hand, in the manufacturing method of the vehicular plate spring according to the present invention, the blanking is preferably fine blanking (Fine blanking). Fine blanking refers to the press working technology that can produce products with fine shear surface and excellent precision throughout the thickness with one blanking. Normal blanking is a single-action, in which only one shearing force is applied, and blanking is performed without clamping the material. Therefore, in the case of general blanking, a product having a shear surface in which about one third of the shear surface is clean and sheared and the remaining two thirds are roughly broken is produced. Machining these products into parts with precise shear surfaces requires two or more secondary processes, such as shaving, milling, reaming, broaching or grinding. On the other hand, fine blanking is a triple action in which three types of forces are applied: shearing force, stripping force to fix the material at the top, and counter force to support the material at the bottom. triple-action), blanking is performed with the material fixed by stripping force and counter force. Therefore, it is possible to produce a precise product with a clean shear surface without cracks or rupture throughout its thickness in a single process.

In addition, the plate material used as the starting material in the manufacturing method of the vehicular plate spring of the present invention is made of boron steel, wherein boron steel is 0.47 to 0.53% by weight of carbon (C), 0.15 to 0.35% by weight of silicon (Si) , Manganese (Mn) 0.5-0.9% by weight, phosphorus (P) 0.01-0.03% by weight, sulfur (S) 0.01-0.03% by weight, chromium (Cr) 0.03-0.13% by weight, boron (B) 10-30 ppm, It is characterized in that the alloy steel containing the remaining iron (Fe) and inevitable impurities. Boron steel is an inexpensive alloy steel in which boron is added instead of expensive alloying elements nickel, chromium, vanadium and molybdenum to improve hardenability and the like, and is excellent in toughness and impact resistance.

Induction heating induction heating ) Steps

Induction heating is a method of heating electrical energy by converting electrical energy into thermal energy by electromagnetic induction, and using Joule's heat generated when a secondary current induced by electromagnetic induction flows through a material to be heated. . Induction heating in the present invention consists of heat-treating the blanked plate material at a temperature of 900 ~ 1000 ℃. Induction heating time in the dish-type spring manufacturing method of the present invention is preferably 5 to 25 seconds, more preferably 6 to 20 seconds. Moreover, it is preferable that it is 200-400 Hz, and, as for an induction heating frequency, it is more preferable that it is 300-400 Hz. Moreover, it is preferable that it is 150-400W, and, as for induction heating power, it is more preferable that it is 200-300W. In addition, the rotational speed during induction heating is preferably 20 ~ 500rpm, more preferably 40 ~ 400rpm. However, the induction heating time, frequency, power, and rotation speed are not particularly limited and may vary depending on the size, thickness, and the like of the induction heating apparatus and the material to be heated.

Die quenching ( die quenching ) Steps

Die quenching is a method of forcibly cooling by using a metal mold when quenching steel, also known as press quenching, and is used when quenching to a predetermined shape with minimal quenching deformation. Die quenching in the present invention consists of quenching, while bending the induction heated plate material at a pressure of 15 ~ 30 ton / ㎡. At this time, since the flat plate material is maintained near the induction heating temperature during bending processing, it becomes ductile and can be easily processed, and the processing pressure is relatively low, thereby improving productivity through shortening of processing time. When the plate spring is manufactured in the bending process at room temperature as in the prior art, the processing is not only difficult, but also takes a lot of processing time to reduce the productivity, and the manufacturing cost increases due to the use of a processing device with a high processing pressure There is this. In the present invention, the shape of the plate material is changed from the planar structure to the three-dimensional structure by the bending process, for example, when the plate spring is a return spring for the automatic transmission clutch plate portion of the circular ring shape by the bending process and the It is provided with an elastic portion protruding to one side from the plate portion. The die-quenched flat plate material maintains the shape as it is processed because bending and quenching are performed at the same time. For example, when the plate spring is a return spring for an automatic transmission clutch, the protrusion is restored to the plate part. There is no tendency to become an excellent elasticity. On the other hand, induction-heated flat plate material is quenched to a certain temperature, for example, 200 ~ 300 ℃ by bending fluid and the like at the same time. In the dish-type spring production method of the present invention, the die quenching pressure is preferably 15 to 25 ton / ㎡. Moreover, it is preferable that it is 4-20 seconds, and, as for die quenching time, it is more preferable that it is 4-15 seconds.

Tempering tempering ) Steps

Quenched steels generally have higher hardness but tend to be more fragile and require heat treatment such as tempering. Tempering is an operation to remove internal stresses by reheating to a temperature below A ₁ transformation point and then cooling, softening and stabilizing the structure in the air, and mainly refers to heat treatment for lowering hardness and increasing viscosity. In the present invention, the step of tempering consists of heat-treating the die quenched flat material at a temperature of 280-370 ° C. and cooling in air. In the present invention, the logwell hardness (Hardness Rockwell C, HRC) required for a vehicle dish spring is finally adjusted in the tempering step, and in the case of manufacturing a dish spring for a vehicle from a flat plate made of boron steel, the heat treatment step of tempering The temperature is closely related to the range of Logwell Hardness (Hardness Rockwell C, HRC). In the dish-type spring manufacturing method of the present invention, the tempering temperature is preferably 300 to 360 ° C. Moreover, it is preferable that it is 20 to 80 minutes, and, as for tempering time, it is more preferable that it is 30 to 60 minutes.

Pinning ( peening ) Steps

The method of manufacturing a vehicular plate spring of the present invention may preferably further comprise a step of pinning. Pinning is an operation of applying a plastic deformation to the surface layer by hammering the surface of the metal continuously with a hammer, and has an effect of relieving tensile residual stress. In the present invention, the step of pinning consists of continuously applying a predetermined impact to the tempered flat material, wherein the pinning is preferably shot peening. Shot peening is a kind of surface treatment hardening method which injects a granule called a shot into the surface of steel, and produces a compressive residual stress in a surface layer. In the case of shot peening, fatigue strength is increased, which is advantageous for surface processing such as spring. At this time, the shot is made of cast iron chill shot, rigid shot, cut wire shot, martens shot and the like. In the method for manufacturing a plate spring for a vehicle of the present invention, the pressure condition of the shot peening is not particularly limited, and is preferably 0.4 to 0.6 MPa. Moreover, it is preferable that it is 1-30 minutes, and, as for shot peening time, it is more preferable that it is 2-25 minutes.

Dish-shaped spring for a vehicle manufactured by the manufacturing method according to the present invention satisfies the logwell hardness (Hardness Rockwell C, HRC), which is a physical property required in automobiles, etc., wherein the appropriate range of logwell hardness (Hardness Rockwell C, HRC) Is 42-48.

Hereinafter, the present invention will be described more specifically with reference to the following examples. However, the following examples are intended to clearly illustrate the present invention and do not limit the scope of protection of the present invention.

One. Dish type  Flat plate material used in spring manufacture

In the present embodiment, a flat plate material made of a general high carbon steel (product name: DIN-50CrV4; manufacturer: POSCO, South Korea) and a plate material made of boron steel having a characteristic composition as shown in Table 1 as a plate material when manufacturing a plate spring (Product Name: POS10B50; Manufacturer: POSCO, South Korea) was used. Generally DIN-50CrV4 is 0.47 ~ 0.53% by weight of carbon, 0.15 ~ 0.40% by weight of silicon, 0.7 ~ 1.1% by weight of manganese, 0.03% by weight of phosphorus (P), sulfur (S) 0.01 ~ 0.03% by weight or less, chromium (Cr) 0.9-1.2% by weight, titanium (Ti) 0.02-0.06% by weight, vanadium (V) 0.1-0.2% by weight, the remaining iron (Fe) and inevitable impurities It consists of alloy steel, POS10B50 is 0.47 ~ 0.53 wt% of carbon (C), 0.15 ~ 0.35 wt% of silicon (Si), 0.5 ~ 0.9 wt% of manganese (Mn), 0.01 ~ 0.03 wt% of phosphorus (P), sulfur (S) ) 0.01 ~ 0.03% by weight, chromium (Cr) 0.03 ~ 0.13% by weight, boron (B) 10-30 ppm, the alloy steel containing the remaining iron (Fe) and unavoidable impurities.

Flatbed material
product name Component and Content (% by weight, but B is ppm) C Si Mn P S Cr B Ti V DIN-50CrV4 0.50 0.22 0.92 0.015 0.006 1.02 - 0.023 0.16 POS10B50 0.49 0.21 0.63 0.013 0.004 0.05 14 0.024

In Table 1, the balance of each flat material is iron and contains a small amount of impurities.

2. Dish type  Manufacture of springs and measurement of properties

The plate-shaped spring was manufactured from the flat plate material consisting of alloy steel shown in Table 1 through the unit processes shown in FIG. 5. The logwell hardness (Hardness Rockwell C, HRC) measurement of the plate material after the conditions of each unit process and each unit process is shown in Table 2 below.

reputation
Material
division Unit process induction heating die quenching tempering shot peening DIN-50CrV4 frequency
(㎐) 358.6 pressure
(ton / ㎡) 19 Temperature
(℃) 390 pressure
(MPa) 0.5 to 0.6 Heating power
(W) 209 time
(sec) 7 Pressurization time
(sec) 5 time
(min) 60 time
(min) 15 Rotation speed
(rpm) 300 Hardness
(HRC) 58.5 ...
59.7 Hardness
(HRC) 45-46 Compressive residual stress
(MPamin) 600 POS10B50 frequency
(㎐) 360.5 pressure
(ton / ㎡) 19 Temperature
(℃) 390 pressure
(MPa) 0.5 to 0.6 Heating power
(W) 211.1 time
(sec) 7 Pressurization time
(sec) 5 time
(min) 60 time
(min) 15 Rotation speed
(rpm) 300 Hardness
(HRC) 60.2 ...
61.4 Hardness
(HRC) 37-38 Compressive residual stress
(MPamin) 600 POS10B50 frequency
(㎐) 360.5 pressure
(ton / ㎡) 19 Temperature
(℃) 340 pressure
(MPa) 0.5 to 0.6 Heating power
(W) 211.1 time
(sec) 7 Pressurization time
(sec) 5 time
(min) 60 time
(min) 15 Rotation speed
(rpm) 300 Hardness
(HRC) 60.2 ...
61.4 Hardness
(HRC) 45-46 Compressive residual stress
(MPamin) 600

3. Dish type  Condition of Unit Process and Property Change of Spring Manufacturing Method

0.47 to 0.53 wt% of carbon (C), 0.15 to 0.40 wt% of silicon (Si), 0.7 to 1.1 wt% of manganese (Mn), 0.03 wt% or less of phosphorus (P), 0.01 to 0.03 wt% or less of sulfur (S), Chromium (Cr) 0.9 to 1.2% by weight, titanium (Ti) 0.02 to 0.06% by weight, vanadium (V) 0.1 to 0.2% by weight, the rest of the iron (Fe) and inevitable plate material consisting of alloy steel containing impurities DIN-50CrV4 wt%, phosphorus (P) 0.01 ~ 0.03 wt%, sulfur (S) 0.01 ~ 0.03 wt%, chromium (Cr) 0.03 ~ 0.13 wt%, boron (B) 10-30 ppm, remaining iron (Fe) And for a plate material made of alloy steel containing impurities inevitably incorporated impurities POS10B50 was prepared by changing the conditions of the unit processes, the spring-like spring was prepared, and the results are shown in Table 3 below.

reputation
Material
division Unit process induction heating die quenching tempering shot peening DIN-50CrV4 frequency
(㎐) 200-380 pressure
(ton / ㎡) 15 to 30 Temperature
(℃) 380-420 pressure
(MPa) 0.4 to 0.6 Heating power
(W) 150-400 time
(sec) 6 to 20 Pressurization time
(sec) 4 to 20 time
(min) 30-90 time
(min) 10-25 Rotation speed
(rpm) 30 to 500 Hardness
(HRC) 54-62 Hardness
(HRC) 42-48 Compressive residual stress
(MPamin) 580-620 Heating temperature
(℃) 930-1000 POS10B50 frequency
(㎐) 200-380 pressure
(ton / ㎡) 15 to 30 Temperature
(℃) 380-420 pressure
(MPa) 0.4 to 0.6 Heating power
(W) 150-400 time
(sec) 6 to 20 Pressurization time
(sec) 4 to 20 time
(min) 30-90 time
(min) 10-25 Rotation speed
(rpm) 30 to 500 Hardness
(HRC) 56-64 Hardness
(HRC) 35 to 40 Compressive residual stress
(MPamin) 580-620 Heating temperature
(℃) 930-1000 POS10B50 frequency
(㎐) 200-380 pressure
(ton / ㎡) 15 to 30 Temperature
(℃) 280-360 pressure
(MPa) 0.4 to 0.6 Heating power
(W) 150-400 time
(sec) 6 to 20 Pressurization time
(sec) 4 to 20 time
(min) 20-80 time
(min) 10-25 Rotation speed
(rpm) 30 to 500 Hardness
(HRC) 56-64 Hardness
(HRC) 42-48 Compressive residual stress
(MPamin) 580-620 Heating temperature
(℃) 930-1000

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, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. In addition, many modifications may be made to adapt a particular situation and material to the teachings of the invention without departing from the essential scope thereof. Accordingly, the protection scope of the present invention should not be construed as being limited to the particular embodiments disclosed as the best mode contemplated for carrying out the invention but to cover all embodiments falling within the scope of the appended claims.

Claims (10)

(a) blanking a plate material made of boron steel;
(b) induction heating the blanked plate material to a temperature of 900 to 1000 ° C .;
(c) die quenching the induction heated plate material at a pressure of 15 to 30 ton / m 2; And
(d) tempering the die quenched plate material at a temperature of 280-370 ° C.,
The boron steel is 0.47 to 0.53% by weight of carbon (C), 0.15 to 0.35% by weight of silicon (Si), 0.5 to 0.9% by weight of manganese (Mn), 0.01 to 0.03% by weight of phosphorus (P), and 0.01 to 0.01% of sulfur (S). 0.03% by weight, chromium (Cr) 0.03 ~ 0.13% by weight, boron (B) 10 ~ 30 ppm, the method of producing a plate-shaped spring for a vehicle, characterized in that the alloy steel containing the remaining iron (Fe) and unavoidable impurities .
The method of claim 1, wherein the manufacturing method further comprises (e) peening the tempered flat plate material.
The method of claim 2, wherein the peening is shot peening.
The method of claim 1, wherein the blanking is fine blanking.
The method of claim 1, wherein the vehicle spring is a return spring for an automatic transmission clutch.
The method of claim 1, wherein the induction heating time of the step (b) is 5 to 25 seconds.
The method of claim 1, wherein the die quenching time of step (c) is 4 to 20 seconds.
The method of claim 1, wherein the tempering time of the step (d) is 20 to 80 minutes.
4. The method of claim 3, wherein the shot peening is performed for 1 to 30 minutes at a pressure of 0.4 to 0.6 MPa.
The method according to any one of claims 1 to 5, wherein the log well hardness (Hardness Rockwell C, HRC) of the vehicle-shaped spring is 42-48.

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