KR101676250B1 - Producing method for steering shaft - Google Patents

Producing method for steering shaft Download PDF

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Publication number
KR101676250B1
KR101676250B1 KR1020150109636A KR20150109636A KR101676250B1 KR 101676250 B1 KR101676250 B1 KR 101676250B1 KR 1020150109636 A KR1020150109636 A KR 1020150109636A KR 20150109636 A KR20150109636 A KR 20150109636A KR 101676250 B1 KR101676250 B1 KR 101676250B1
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KR
South Korea
Prior art keywords
jig
steering shaft
yoke
wire
manufacturing
Prior art date
Application number
KR1020150109636A
Other languages
Korean (ko)
Inventor
조혜민
Original Assignee
현대자동차주식회사
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Priority to KR1020150109636A priority Critical patent/KR101676250B1/en
Application granted granted Critical
Publication of KR101676250B1 publication Critical patent/KR101676250B1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K1/00—Making machine elements
    • B21K1/06—Making machine elements axles or shafts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
    • B21J5/08—Upsetting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
    • B21K1/00—Making machine elements
    • B21K1/06—Making machine elements axles or shafts
    • B21K1/066—Making machine elements axles or shafts splined
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P2700/00—Indexing scheme relating to the articles being treated, e.g. manufactured, repaired, assembled, connected or other operations covered in the subgroups
    • B23P2700/50—Other automobile vehicle parts, i.e. manufactured in assembly lines

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Steering Controls (AREA)

Abstract

The present invention relates to a method for manufacturing a steering shaft. More specifically, the present invention comprises: an upsetting step; a spline forming step; a yoke unit forming step; and a yoke unit correcting step. The present invention designs a material of a wire used for a steering shaft to be made of an alloy having high toughness and high strength. Moreover, the present invention relates to the method for manufacturing a steering shaft, optimizing a pressing condition and a jig shape when the steering shaft is formed.

Description

Technical Field [0001] The present invention relates to a manufacturing method for a steering shaft,

The present invention relates to a method of manufacturing a steering shaft, and more particularly, to a method of manufacturing a steering shaft, which comprises a manufacturing process including an upsetting step, a spline forming step, a yoke forming step and a yoke part correcting step, The present invention relates to a method of manufacturing a steering shaft that is designed as an alloy capable of achieving high toughness and high strength and further optimized pressing conditions and jig shapes at the time of molding.

Generally, a steering shaft of an automobile is a component installed in a steering system for determining a running direction of an automobile, and is installed to be inclined downward at the center of rotation of a steering wheel of an automobile to transmit a rotational torque of the steering wheel to a wheel .

Such a steering shaft has to be excellent in wear resistance and strength, and is also a component requiring precise dimension adjustment.

FIG. 1 shows the structure of a general steering shaft, and a method of manufacturing the steering shaft will be described with reference to the drawings.

Generally, two manufacturing methods are used for manufacturing the steering shaft.

First, a yoke 10 is manufactured by pressing a wire by a hot forming method, and a shaft 20 is formed separately from the yoke 10 by a cold forming method. 10 and the shaft portion 20 by carbon dioxide (CO2) welding, and performing a high frequency or carburizing heat treatment process for imparting abrasion resistance and strength, and then performing a water proofing process to manufacture a steering shaft.

Secondly, after the wire member is cold-formed to form the shaft portion 20, the end portion of the molded shaft portion 20 is pressed to form the yoke portion 10, and a high-frequency or carburizing heat treatment for imparting abrasion resistance and strength And then performing the inspection process to manufacture the steering shaft.

The steering shaft manufactured as described above has a thin and long thin plate spline formed on the shaft portion 20. A ball is placed on the shaft portion 20 on which the spline is formed and the steering shaft is assembled So that the slide operation of the steering shaft is performed.

Therefore, since the straightness and the dimensional accuracy of the spline formed on the shaft portion 20 have an important influence on the quality of the steering shaft, the defective products are selected through a separate inspection process after the manufacturing process, .

This is because not only the shape of the shaft portion 20 itself, which is poorly manufactured, but the shape of the shaft portion 20 is difficult to correct, but also the surface quality of the shaft portion 20 for the slide operation of the steering shaft is important.

Generally, in the case of the joint-type manufacturing method, the defective ratio among the manufactured steering shaft is 8 to 10%, and in the case of the integral manufacturing method, the defective ratio among the manufactured steering shaft reaches 10 to 15%.

The reason why the integral manufacturing method has a higher defect rate is because the integral manufacturing method has a merit that the welding process is omitted and the process is simple. However, since the molding of the yoke portion 10 and the shaft portion 20 is performed by a single wire rod It is understood that the molding process itself of the yoke portion 10 adversely affects the straightness of the shaft portion 20 and the dimensional accuracy.

Accordingly, the present invention provides an integrated manufacturing method of a steering shaft, in which welding is omitted and the process is simplified. In this way, the straightness and dimensional accuracy of the splines formed in the shaft portion can be well maintained, The present invention provides a method of manufacturing a steering shaft capable of drastically reducing the defective rate of the method.

According to an aspect of the present invention, there is provided a method of manufacturing a steering shaft including a step of performing an upsetting step, a spline forming step, a yoke forming step, and a yoke part correcting step. The material is designed as an alloy capable of achieving high toughness and high strength, and further, a pressing condition and a jig shape are optimized during molding.

The method of manufacturing a steering shaft according to the present invention having the above-described structure is characterized in that a material optimized for an integral manufacturing method of a steering shaft is designed through the design of an alloy of high toughness and high strength, The present invention is a very advanced invention that exhibits the dimensional accuracy and straightness of the spline of the present invention, which is very good, and reduces the defective ratio of the steering shaft, thereby achieving cost reduction in manufacturing.

1 is a view showing the configuration of a general steering shaft,
2 is a schematic diagram of a manufacturing process of a steering shaft according to the present invention.

Hereinafter, the configuration of the steering shaft manufacturing method of the present invention will be described with reference to the drawings.

It is to be noted, however, that the disclosed drawings are provided as examples for allowing a person skilled in the art to sufficiently convey the spirit of the present invention. Accordingly, the present invention is not limited to the following drawings, but may be embodied in other forms.

In addition, unless otherwise defined, the terms used in the description of the present invention have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. In the following description and the accompanying drawings, A detailed description of known functions and configurations that may be unnecessarily blurred is omitted.

FIG. 2 is a schematic diagram of a manufacturing process of a steering shaft according to the present invention, and a manufacturing method of the present invention will be described with reference to the drawings.

A manufacturing method of a steering shaft according to the present invention is an integrated manufacturing method by a cold forming method. A steering shaft is manufactured by molding a yoke portion 110 after forming a shaft portion 120.

1) upsetting step S1;

The step of setting the length, the width and the straightness of the wire rod 100 as the basic material of the steering shaft is performed by inserting the wire rod 100 into the first jig M1 and pressing the wire rod 100 with the press member P The wire member 100 is formed to have the length, width, and straightness of the first jig M1.

2) Spline forming step (S2)

The step of forming a spline on the shaft portion 120 of the steering shaft includes the steps of inserting the wire 100 having undergone the upsetting step into the second jig M2 and pressing the wire member 100).

At this time, the shape of the spline to be formed is molded inside the second jig M2, and the spline 130 is formed on the shaft portion 120 of the wire member 100 through the pressing of the press member P.

3) Forming the yoke part (S3)

The step of molding the yoke part 110 in the wire rod 100 includes the step of inserting the wire 100 having the spline as described above into the third jig M3 and forming the shaft part 120 having the spline 130 at one end, The yoke portion 110 is formed by pressing the end portion of the other end of the wire member 100 formed with the pressing member P by the pressing member P. [

The third jig M3 is molded with the shape of the yoke to be formed so that the yoke portion of the third jig M3 has a shape of the yoke of the third jig M3 at the end portion of the wire 100, (110) is formed.

4) Calibration step of yoke part (S4)

The wire member 100 formed with the shaft portion 120 and the yoke portion 110 is inserted into the fourth jig M4 through the first yoke forming step S3 and the yoke portion 110 is inserted into the press member P And then the shape of the yoke portion 110 is corrected so that the shape of the yoke portion 110 formed through the yoke forming step S3 is corrected.

At this time, the shape of the yoke molded in the fourth jig M4 is different from the shape of the yoke molded in the third jig M3, and the shape of the yoke molded according to the shape of the yoke of the third jig M3 The portion 110 is calibrated to the shape of the yoke molded in the fourth jig M4.

As described above, in the method of manufacturing the steering shaft of the present invention, the yoke portion 110 is formed through the two steps of the yoke forming step S3 and the yoke portion correcting step S4, The load applied to the yoke 110 during molding can be reduced through the distribution of the molding amount and the adverse effect of the molding process of the yoke 110 on the shaft 120 can be minimized.

5) Inspection step (S5)

The steering shaft of the present invention including the shaft portion 120 formed with the yoke portion 110 and the spline 130 finally molded to the required dimensions through the yoke portion correcting step S4 is completed, Is shipped after inspection process to select defective products.

According to the method for manufacturing a steering shaft of the present invention having the above-described steps, it is possible to manufacture a steering shaft with better quality according to the material characteristics and the forming conditions of the wire rod 100, and will be described in detail below.

First, the wire rod 100 used in the manufacturing method of the present invention uses an alloy having the same metal composition as the wire rod of the present invention shown in Table 1 below.

C Si Mn P S Ni Cr Mo B Nb Al Conventional
Wire rod
(Reference value) 0.12-0.18 0.15-0.35 0.55-0.90 0.01-
0.03 0.01-
0.03 0.01-
0.25 0.85-1.25 0.15-0.35 none none none example
invent
Wire rod 0.10-0.15 0.15-0.35 1.20-1.80 0.01-
0.03 0.01-
0.03 0.01-
0.25 0.50-0.70 none 0.001-0.004 0.015-0.035 0.025-0.045

* Remark: The unit of each metal component is% by weight, and the balance is the content of Fe (Fe) contained in the alloy.

Here, the carbon (C) is effective for improving the strength of the wire, but the carbon (C) has a composition ratio of 0.01-0.15 wt.

The manganese (Mn) has a composition ratio of 1.20-1.80% by weight. The pearlite of the wire is finer and the ferrite is solid-strengthened to improve the yield strength of the carbon steel.

The chromium (Cr) improves the incombustibility of the wire, increases the resistance to tempering to improve the strength, and has a composition ratio of 0.50-0.70 wt%.

The boron (B) is a strong incombustibility improving element, which can improve the strength of the material after heat treatment by improving the ingot property even with a small amount of the boron (B), and has a composition ratio of 0.001-0.004 wt%.

The niobium (Nb) is a strong grain microfine element and can be added to the alloy at a composition ratio of 0.015-0.035% by weight because it can contribute to the strength enhancement by increasing the grain coarsening temperature.

Since the aluminum (Al) precipitates fine and is effective in refining the grain of the steel, it can improve the strength of the material and is incorporated into the alloy at a composition ratio of 0.025-0.045 wt%.

Silicon (Si), phosphorus (P), sulfur (S), and nickel (Ni) used in the alloy of the wire of the present invention are the same as those of the conventional wire shown in Table 1, and detailed description thereof will be omitted.

Table 2 below is a table showing the composition ratios of the examples of the wire rod of the steering shaft satisfying the composition ratio section of the present invention and Comparative Examples 1 to 6 having different composition ratios for comparison with the present invention examples.

division
Constituent C Si Mn P S Ni Cr Mo B Nb Al Example
0.13 0.25 1.70 0.010 0.015 0.03 0.60 none 0.003 0.020 0.030 Comparative Example
One 0.16 0.20 0.65 0.005 0.010 0.02 1.15 0.25 none none none Comparative Example
2 0.16 0.25 1.70 0.010 0.015 0.03 0.60 none 0.003 0.020 0.030 Comparative Example
3 0.09 0.25 1.70 0.010 0.015 0.03 0.60 none 0.003 0.020 0.030 Comparative Example
4 0.13 0.25 1.10 0.010 0.015 0.03 0.60 none 0.003 0.020 0.030 Comparative Example
5 0.13 0.25 2.00 0.010 0.015 0.03 0.60 none 0.003 0.020 0.030 Comparative Example
6 0.13 0.25 1.70 0.010 0.015 0.03 1.10 none 0.003 0.020 0.030

* Remark 1: The unit of each metal component is% by weight, and the remainder is the content of Fe (Fe) contained in the alloy.

Note 2: Comparative Example 1 is the composition ratio of the conventional wire shown in Table 1, and Comparative Example 2 to Comparative Example 6 were similar to those of Examples of the present invention, except that molybdenum (Mo) was not included and boron (B), niobium ) And aluminum (Al).

Table 3 below is a table for measuring the tensile strength, yield strength and elongation of Examples of the present invention and Comparative Examples 1 to 6 shown in Table 2 above.

division Tensile Strength (Mpa) Yield strength (Mpa) Elongation (%) Remarks Example 470 376 15 Strength and formability
Good Comparative Example 1 430 344 16 Lack of strength
Comparative Example 2 485 380 12 Lack of formability Comparative Example 3 390 310 18 Lack of strength Comparative Example 4 445 356 16 Lack of strength Comparative Example 5 475 395 14 Lack of formability Comparative Example 6 475 380 12 Lack of formability

The results of Table 3 indicate that the wire rod of the steering shaft using the alloy material having the composition ratio of the present invention had a tensile strength and yield strength improved by about 10% as compared with the wire rod of the steering shaft of Comparative Example 1 of the conventional reference value And the elongation ratios were comparable to those of Comparative Examples 2 to 3 which had a composition ratio including boron (B), niobium (Nb) and aluminum (Al) Compared with the example 6, the strength and the moldability were better than those of the comparative example.

Further, the method of manufacturing a steering shaft of the present invention makes it possible to manufacture a steering shaft of better quality by adjusting the shape of the jig of the steering shaft and the pressing speed of the press member.

division Condition 1 Condition 2 Condition 3 The present invention Pressing speed 300 mm / s 200 mm / s 100 mm / s 150 mm / s Jig Life 3000 Get 3700 Get 4500 Get 4000 Jig-shaped
Management scope * Second jig (M2):
Finished dimensions + 500μm
* Third Jig (M3):
Finished dimensions + 50μm
* Fourth jig (M4):
Finished size + 10μm * Second jig (M2):
Finished dimension + 100μm
* Third Jig (M3):
Finished dimensions + 50μm
* Fourth jig (M4):
Finished size + 10μm * Second jig (M2):
Finished dimension + 100μm
* Third Jig (M3):
Finished dimensions + 50μm
* Fourth jig (M4):
Finished size + 10μm * Second jig (M2):
Finished dimensions + 50μm
* Third Jig (M3):
Finished size + 10μm
* Fourth jig (M4):
Finished size + 10μm Straightness Bad Bad Good Good OBD measurement
(Outer Ball Diameter) Bad Bad Bad Good

The results of the OBD measurements in Table 4 are shown in Table 5 below.

division standard Minimum Maximum Difference between maximum value and minimum value Average Defect rate Remarks Condition 1
24.577 ±
0.015
(24.562 - 24.592)
24.572 24.602 0.03 24.589 43% Defect level Condition 2 24.568 24.599 0.03 24.580 23% Defect level Condition 3 24.577 24.597 0.02 24.587 8% Conventional
Equivalent level Invention
Condition 24.577 24.585 0.008 24.581 0% Good level

As a result of producing the steering shaft under the conditions of the shape of the jig and the pressing speed of the press member of the manufacturing method of the present invention, the straightness is satisfied at a satisfactory level and the defective rate Lt; RTI ID = 0.0 > significantly < / RTI >

Therefore, the present invention exhibits the following excellent effects as compared with the conventional method of manufacturing a steering shaft.

That is, as compared with the joint type manufacturing method using the conventional welding process, the manufacturing method of the present invention can omit the welding process of the hot part, the shaft part, the CO2 welding process and the welding part inspection, And the manufacturing time can be reduced by about 50%.

In contrast to the defect rate of 8 to 10% in the conventional method of joining the steering shaft and the defective ratio of 10 to 15% in the conventional method, the manufacturing method of the present invention has a defective ratio of 0% ), And it is expected to achieve a defective rate of less than 3% even in mass production in the future.

Further, as a result of the fatigue life evaluation of the steering shaft according to the manufacturing method of the present invention, it is possible to obtain a result that the torsional life of the conventional steering shaft is improved by about 1.2 times as compared with the conventional twist life of the steering shaft, and the durability is improved.

The tensile strength of the steering shaft according to the present invention was improved by about 10% as shown in Table 3, and the tensile strength was 897 MPa and the surface hardness (HRC) was 57 to 60 even after the carburizing treatment, And a result that the physical properties were improved by about 5% compared to Comparative Example 1 was obtained.

Description of the Related Art [0002]
100; Wire rod
110; Yoke part
120; Shaft portion
130; Spline
P; Press member
M1; The first jig
M2; The second jig
M3: Third jig
M4: fourth jig

Claims (7)

A method of manufacturing a steering shaft of an automobile,
The wire member 100 is inserted into the first jig M1 and the wire member 100 is pressed by the press member P so that the wire member 100 is formed to have the length, width, and straightness of the first jig M1 Upsetting step S1;
The wire member 100 having been subjected to the upsetting step is inserted into the second jig M2 having a shape of a spline to be formed therein and the wire member 100 is pressed by the press member P, A spline forming step S2 of forming a spline 130 on the part 120;
The spline formed wire 100 is inserted into a third jig M3 molded in the shape of a yoke and the distal end of the wire 100 is pressed by a press member P to form a yoke 110, (S3);
The yoke portion 110 of the wire member 100 having the yoke portion 110 formed thereon is inserted into the fourth jig M4 and the yoke portion 110 is pressed again by the press member P, A step S4 of correcting the shape of the yoke portion; And,
The wire rod (100)
0.10-0.15 wt% of carbon (C), 0.15-0.35 wt% of silicon (Si), 1.20-1.80 wt% of manganese (Mn), 0.01-0.03 wt% of phosphorus (P) (B) 0.001-0.004 wt.%, Niobium (Nb) 0.015-0.035 wt.%, Aluminum (Al) 0.025-0.045 wt.%, And And the balance of iron (Fe).
The method according to claim 1,
A verification step (S5) of validating the steering shaft through the yoke correction step (S4); Wherein the first and second shafts are formed on the first and second shafts.
2. The apparatus according to claim 1, wherein the fourth jig (M4)
Wherein a shape of the yoke portion is different from a shape of the yoke portion molded in the third jig (M3).
delete The wire rod according to claim 1, wherein the wire rod (100)
0.13 wt% of carbon (C), 0.25 wt% of silicon (Si), 1.70 wt% of manganese (Mn), 0.01 wt% of phosphorus (P), 0.015 wt% of sulfur (S) (B), 0.02 wt% of niobium (Nb), 0.03 wt% of aluminum (Al), and the balance of iron (Fe) .
The method of manufacturing a steering shaft according to claim 1, wherein the pressing speed of the pressing member (P) is maintained at 150 mm / s.
The method according to claim 1,
The second jig M2 is a jig having a management range of the finished dimension + 50 mu m,
The third jig M3 is a jig having a management range of finished dimension + 10 mu m,
And the fourth jig M4 is a jig having a management range of finished dimension + 10 mu m.
KR1020150109636A 2015-08-03 2015-08-03 Producing method for steering shaft KR101676250B1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102099956B1 (en) * 2019-03-21 2020-04-10 아신유니텍 (주) A Press Fitting System for Manufacturing a Parking Shaft Spline of an Electrical Vehicle

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20090100011A (en) * 2008-03-19 2009-09-23 주식회사태진정공 Universal joint manufacturing method
KR101029220B1 (en) * 2010-10-06 2011-04-14 주식회사 신일 Forging method to make yoke shaft in upsetter

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20090100011A (en) * 2008-03-19 2009-09-23 주식회사태진정공 Universal joint manufacturing method
KR101029220B1 (en) * 2010-10-06 2011-04-14 주식회사 신일 Forging method to make yoke shaft in upsetter

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102099956B1 (en) * 2019-03-21 2020-04-10 아신유니텍 (주) A Press Fitting System for Manufacturing a Parking Shaft Spline of an Electrical Vehicle

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