JPH062035A - Metallic member to be applied torsional stress - Google Patents

Abstract

PURPOSE:To improve torsional strength by forming a forged metallic member into a forged material where flow-lines are twisted in the direction equal to the direction in which torsional stress is applied at the time of use. CONSTITUTION:A forged material 24 prepared by forging an ingot of steel, such as spring steel, is applied to permanent torsional deformation, by which flow-lines 22 are made torsional on the axis. By the above procedure, the occurrence of plastic deformation, breakage, etc., can be prevented at the time of use. A superior effect can be obtained in the case where the angle of torsion of the flow-lines 22 is regulated to 30-60 deg.. The torsional deformation can be applied, e.g. by applying hot, warm, or cold permanent torsional deformation, by rotating a die in the course of manufacture, or by twisting the steel material. By this method, the forged material 24 having the torsional flow-lines 22 can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal member to which a torsional stress is applied during use, and more particularly to a technique for improving the strength against the torsional stress.

[0002]

2. Description of the Related Art Steel rods, wire rods and pipes are manufactured by subjecting a cast raw steel ingot to forging, rolling, extruding and drawing. Forging is the same as forming steel
While refining the coarse dendritic structure generated during casting,
It is carried out for the purpose of correcting internal defects, and a training coefficient (working ratio) is usually required to be 3 or more. In the wrought material such as the bar material or the wire material that has been wrought in this way, the mechanical strength in the longitudinal direction is high and the excellent toughness is obtained because the grain flow lines extend substantially parallel to the longitudinal direction.

[0003]

However, the wrought material having grain flows extending in the longitudinal direction as described above is relatively vulnerable to the torsional stress around the axial center, and thus the torsion bar, the coil spring, the cylindrical shaft, and the milling cutter. When it is used for a metal member to which a torsional stress is applied when it is used, such as a rotary tool, etc., it is not always possible to obtain sufficiently satisfactory mechanical strength.

The present invention has been made in view of the above circumstances, and its object is to improve the torsional strength of a metal member to which a torsional stress is applied during use.

[0005]

In order to achieve such an object, the present invention is to form a cylindrical or cylindrical shape by forging a metal material, and in use, twist stress in one direction around the axis. A metal member to which is added,
The grain flows are twisted in the same direction as the direction in which the torsional stress is applied.

[0006]

In the metal member as described above, the grain flows are twisted in the same direction as the direction in which the torsional stress is applied during use. The maximum torsional strength and torsional elastic limit have been improved, and torsion bars, coil springs, cylindrical shafts,
By being applied to a rotary tool such as a milling cutter, plastic deformation, breakage or the like of them is suppressed. The twist angle of the grain flow, that is, the inclination angle from the direction parallel to the axis, is within the range of 10 ° or more and 60 ° or less on the outer peripheral surface in order to obtain an excellent mechanical strength improving effect. Is desirable.

[0007]

EXAMPLES Next, in order to clarify the effects of the present invention,
The test results conducted by the present inventors will be described. First, as shown in FIG. 1, grip portions 12 and 14 are provided at both ends, and a parallel columnar shape having a diameter of 8 mm and a length of 20 mm is formed between the grip portions 12 and 14. Part 16
A torsion test piece 10 having is prepared. Grips 12, 14
Has a columnar shape with a diameter and a length of 20 mm, and a part of the outer peripheral surface thereof is chamfered flat. Further, between the parallel portion 16 and the grip portions 12 and 14, R chamfering with a radius of 5 mm is performed within a length of 5 mm. FIG. 1A shows a test piece 10.
And (b) is a right side view of (a).

The torsion test piece 10 is a commercially available cast steel ingot of chrome vanadium spring steel SUP10 that is forged, rolled, extruded, drawn or otherwise forged, and has a diameter of 25 mm in which the grain flow line extends substantially parallel to the axis. Using the forged material of Fig. 1, after applying a torsional stress around the axis while hot to give a permanent torsional deformation,
It was cut into the shape of. Forged material 20 of FIG.
Indicates that a grain flow line 22 indicated by an alternate long and short dash line extends substantially parallel to the axis, and the wrought material 24 of FIG. 3 is obtained by subjecting the wrought material 20 of FIG. 2 to permanent twist deformation. The forged material 24 is cut to manufacture the torsion test piece 10. Due to the permanent torsional deformation, the grain flow line 22 is twisted around the axis, but in this embodiment, as shown in FIG. 4, the twist angle of the grain flow line on the surface of the parallel portion 16 is -45 °, 0 °,
Six kinds of 30 degrees, 45 degrees, 60 degrees, and 75 degrees were prepared.
A twist angle of "-" means twist in the direction opposite to the direction of the torsional stress applied during the test. Further, the torsion test piece 10 was quenched at 870 ° C. by oil cooling and then tempered at 470 ° C. The final hardness is HRC4
5 to 46.

FIG. 4 shows a result of measuring the torsional strength and the like in the parallel portion 16 by grasping the pair of grasping portions 12 and 14 of the torsion test piece 10 and applying torsional stress. As is clear from the above results, in the four types of torsion test pieces 10 having a grain flow twist angle of 30 ° or more, “*” is shown in comparison with those having a twist angle of 0 °, that is, parallel to the axis. The maximum torsional strength shown by the mark, the torsional elastic limit shown by the "△" mark, and the elastic torsion angle shown by the "+" mark are all improved, especially 30 ° ~
An excellent effect can be obtained at 60 °. On the other hand, when the twist angle twisted in the opposite direction is −45 °, the strength is rather lowered as compared with the case where the twist angle is 0 °. In addition,
The elastic torsion angle is the torsion angle at the torsion elastic limit.

FIG. 5 shows a case where a high speed tool steel SKH51 having a diameter of 22 mm is used as the forged material 20 in place of the chrome vanadium spring steel SUP10. In addition, permanent twist deformation was applied to produce a forged material 24 in which the grain flows 22 were twisted, and then the forged material 24 was cut to produce a torsion test piece 10. Then, after quenching from 1210 ° C. by oil cooling, tempering at 575 ° C. was repeated twice, and the final hardness was HRC64. In this case, as is clear from FIG. 5, the test was conducted by preparing four kinds of grain line twist angles of 0 °, 15 °, 30 ° and 45 ° on the surface of the parallel portion 16. As the twist angle increases, the maximum torsional strength indicated by “*”, the torsional elastic limit indicated by “Δ”, and the elastic torsion angle indicated by “+” are all improved. Also, the diameter is 8m
m, 90 mm long high-speed tool steel SKH51 forged material was subjected to hot permanent torsional deformation so that the twist angle of the grain flow line at the outer peripheral surface was 45 °, and then the same heat treatment as above A bending test piece was prepared and subjected to a stress test from the direction perpendicular to the axis by a one-point load formula at the center of the fulcrum distance of 70 mm. Compared to the original forged material with a twist angle of 0 °,
Both the maximum bending strength indicated by "x" and the bending elastic limit indicated by "○" decreased.

The twisting test using the twisting test piece 10 shown in FIG. 1 has been described above in detail. From these test results, according to the present invention, the twisting strength, the twisting elastic limit and the elastic twisting angle can be improved. Is clear, and thus the grain flow 2
Various members such as torsion bars, coil springs, cylindrical shafts, and rotary cutting tools such as milling cutters, taps, drills, etc., which are subjected to torsional stress in one direction around the shaft center when they are used When manufactured, such plastic deformation and damage can be suppressed. The forged material 24 of FIG. 3 in which the grain flows 22 are twisted, the torsion spring, the cylindrical shaft, and the rotary cutting tool manufactured from the twisted material correspond to the metal member according to the present invention.

In the above example, the commercially available forged material 20 is subjected to permanent torsional deformation hot to twist the grain flows 22 around the axis, but it is possible to permanently twist the grain flow 22 cold or warm. By giving deformation, rotating a die in a forging process such as rolling or drawing, or twisting a steel material, the grain flow line 22
It is also possible to manufacture a twisted forged material 24. Further, in the above example, the case where the forged material 20 of the chrome vanadium spring steel SUP10 and the high speed tool steel SKH51 is used has been described, but the present invention can be similarly applied to other metal materials. It can be implemented in various modified and improved modes based on the knowledge of the trader.

[Brief description of drawings]

FIG. 1 is a diagram showing a test piece used in a torsion test for clarifying the effect of the present invention, which is manufactured from the forged material of FIG.

FIG. 2 is a view showing a forged material in which a grain flow line used for manufacturing the test piece of FIG. 1 is substantially parallel to an axis.

FIG. 3 is a view showing a state in which the forged material of FIG. 2 is permanently twisted and twisted so that a grain flow line is twisted.

FIG. 4 is a diagram showing a torsion test result when the test piece of FIG. 1 is manufactured using chrome vanadium spring steel SUP10.

FIG. 5 is a diagram showing a torsion test result when the test piece of FIG. 1 is manufactured using the high speed tool steel SKH51.

[Explanation of symbols]

 22: Grain flow line 24: Forged material (metal member)

Claims (2)

[Claims] 1. A metal member, which is formed into a columnar shape or a cylindrical shape by subjecting a metal material to forging, and to which a torsional stress is applied in one direction around an axis during use, the direction in which the torsional stress is applied. A metal member to which a torsional stress is applied, characterized in that the grain flows are twisted in the same direction as. 2. The twist angle of the grain flow is 1 on the outer peripheral surface.
The metal member to which a torsional stress is applied according to claim 1, which is in a range of 0 ° or more and 60 ° or less.