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Steel bar for steering rack, method for producing the same, and steering rack using the same

A technology for steering racks and manufacturing methods, applied in the direction of manufacturing tools, mechanical steering gears, furnace types, etc., can solve problems such as fracture, insufficient wear resistance, expansion, etc.

Inactive Publication Date: 2006-06-21
JTEKT CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] For example, even if the bending strength of the steering rack is improved by induction hardening, if an excessive load acts on the induction hardened layer and temporarily cracks, the crack may expand inward until it breaks
[0011] In addition, in the electric power steering that has become popular in recent years, the contact surface pressure between the steering rack and the pinion gear (Pinion Gear) tends to be higher than that of the hydraulic power steering, and the wear resistance of S45C steel is insufficient.
In addition, in medium carbon steel, if the content of C is increased to improve wear resistance, impact resistance will decrease

Method used

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  • Steel bar for steering rack, method for producing the same, and steering rack using the same
  • Steel bar for steering rack, method for producing the same, and steering rack using the same
  • Steel bar for steering rack, method for producing the same, and steering rack using the same

Examples

Experimental program
Comparison scheme
Effect test

experiment example 1～36

[0064] Steel materials having the compositions shown in Tables 1 to 2 below were melted and rolled into steel bars with a diameter of 30 mm. Then, after heating to the temperature shown in Tables 1-2, quenching was completed by controlling cooling to room temperature. In addition, in this controlled cooling, the structure of the bar steel is controlled by changing the amount of water and the water cooling time. After cooling, the steel bar was tempered by staying in the furnace heated to the atmospheric temperature shown in Tables 1 and 2 for the time shown in Tables 1 and 2. The steel bars after tempering are allowed to cool.

[0065] The structure of the D / 4 part of the quenched steel bar and the structure of the D / 4 part of the tempered steel bar were observed with an electron microscope (5000 times the magnification), and the martensite structure and the bainite structure were obtained. , and the area ratios of tempered martensite, tempered bainite, and regenerated pearl...

Embodiment

[0140] Using a steel material with a C content of 0.53 mass%, a Si content of 0.23 mass%, a Mn content of 0.8 mass%, a S content of 0.018 mass%, a Cr content of 0.30 mass%, and a B content of 0.015 mass%, the diameter is formed by rolling. After the 30mm steel bar is heated to 780°C, it is then controlled to cool to room temperature. After cooling, the steel bar is tempered by staying in a furnace heated to an ambient temperature of 660° C. for 15 minutes. The steel bars after tempering are allowed to cool. More preferably, the heating temperature is 820°C, and the atmosphere temperature during tempering is 690°C.

[0141] The bar steel obtained in this way was drawn to have a diameter of 27.5 mm, and then cut to form a flat portion 21 , and rack teeth 8 a were formed on this flat portion 21 as the rack tooth forming portion 22 . Next, heat the rack tooth forming part 22 for 5.5 seconds, and then perform induction quenching with a cooling time of 10 seconds by water cooling,...

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PUM

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Abstract

The present invention provides a steel bar for steering rack, which contains C: 0.50-0.60% by mass, Si: 0.05-0.5% by mass, Mn: 0.2-1.5% by mass, B: 0.0005-0.003% by mass, Ti: 0.005-0.05% by mass % by mass, Al: 0.0005 to 0.1% by mass, and N: 0.002 to 0.02% by mass. Assuming that the diameter of the steel bar is D, the quenched and tempered structure of the portion of the steel bar at a depth of D / 4 from the surface satisfies the conditions of I), II) and III) below. I) The total area percentage of the tempered bainite structure and the tempered martensite structure is 30 to 100%. II) The area percentage of the regenerated pearlite structure is 0-50%. III) The total area percentage of tempered bainite structure, tempered martensite structure and regenerated pearlite structure is 50-100%.

Description

technical field [0001] The present invention relates to a steel bar for a steering rack used in a steering device of an automobile, a manufacturing method thereof, and a steering rack using the same. Background technique [0002] Steering of automobiles is classified into a method of assisting by oil pressure (hydraulic steering assist) and an assisting method by electricity (electric steering assist). [0003] The hydraulic power steering is the current mainstream, which utilizes the engine output to boost the operating force by the pressure oil sprayed from the operating oil pump. However, in the hydraulic power steering, since the output of the engine is used as the power source, there will be a problem of reducing the fuel efficiency of the vehicle. [0004] In contrast, electric power steering uses an electric motor that operates on electrical energy from the battery to assist the steering force. Compared with the above-mentioned hydraulic power steering, electric pow...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B62D3/12C22C38/00C21D9/32C22C38/14C22C38/60
Inventor 太田敦彦龟井亮渡边和宏金池幸伦塚本修池田正一阿南吾郎井户尻弘
Owner JTEKT CORP
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