JP2000008122A - High-frequency hardening jig - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hardening jig which reduces contraction in a diametrical direction and then deformation of an opening by forming a part not in contact with and a part in contact with an outer wall face at a part facing the outer wall face and arranging an annular restricting part to restrict the outer wall. SOLUTION: While an upper part of an outer wall face 62 of a steel member 60 is restricted from outside by a restricting part 20, an inner wall face is heated to a hardening temp. by an induction coil 104, a cooling liquid is injected from cooling liquid injection holes 106, 110 and the steel member 60 is rapidly cooled to be subjected to high-frequency hardening. An outer wall part of the steel member 60 is restricted by the restricting part 20 of a high-frequency hardening jig 10, e.g. a position of a groove not forming a flange part 90 in the outer wall face 62, that is, a part of the steel member 60 likely to contract in a diametrical direction is positioned to a non-contact part formed by removing a part of the restricting part 20. By this method, a part of the outer wall face 62 likely contracting is freely expanded by heating, this expansion quantity and a contraction margin after hardening are balanced, as a result, a contraction quantity is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction hardening jig for restraining an outer wall surface of an object to be heated from the outside when the inner wall surface of the object to be heated is induction hardened.

[0002]

2. Description of the Related Art Induction quenching, in which an object to be heated such as a steel member is heated using induction heating, and then the heated portion is rapidly cooled and hardened, has been widely used. One of the objects to be heated to be subjected to the induction hardening is a tubular steel member.

[0003] Some cylindrical steel members have a plurality of grooves extending in the height direction formed on the inner wall surface side by side in the inner circumferential direction. The plurality of grooves extend, for example, from one opening or its vicinity of the cylindrical steel member to the other opening or its vicinity. Further, a flange may be formed on an outer wall surface at an end of a portion corresponding to the back side of a predetermined groove among the plurality of grooves. When the inner wall surface of such a tubular steel member is induction hardened, a tubular steel member is formed at a position where a flange is not formed on an outer wall portion corresponding to the back side among a plurality of grooves. The present inventor has found that there is a possibility that the opening of the steel member may become elliptical due to contraction in the diameter direction.

[0004]

When the cylindrical steel member shrinks in its diameter direction and its opening becomes elliptical, problems such as difficulty in inserting a mating part to be inserted into the inside of the cylinder occur. . If the opening is elliptical, extra work such as cutting the inner wall surface to make the opening close to a perfect circle is required, which contributes to an increase in cost. Further, in some cases, the hardened layer on the inner wall surface is shaved off by the cutting process, and the induction hardening may be wasted.

In view of the above circumstances, an object of the present invention is to provide a jig for induction hardening capable of reducing shrinkage in a diameter direction and reducing deformation of an opening when induction hardening is performed on a cylindrical object to be heated. And

[0006]

A first induction hardening jig according to the present invention for achieving the above object is a jig for induction hardening the inner wall surface of a cylindrical object to be heated. In the induction hardening jig that restrains the outer wall from the outside, (1)
A ring-shaped constraining portion for constraining the outer wall from the outside is formed in a portion facing the outer wall, and a contact portion in contact with the outer wall and a non-contact portion not in contact with the outer wall are formed. It is characterized by the following.

In order to achieve the above object, a second induction hardening jig of the present invention has a plurality of grooves extending in a height direction from one opening or its vicinity to the other opening or its vicinity. A cylinder formed on the inner wall surface side by side in the circumferential direction, and a portion of the outer wall surface of the cylinder located at the peripheral edge of the other opening, and a predetermined groove of the plurality of grooves; In the induction hardening jig for restraining the object to be heated when induction hardening the inner wall surface of the object to be heated having a flange formed on a portion corresponding to the back side,
(2) Of the outer wall surface of the cylinder, the outer wall is fitted into a portion located at the peripheral edge of the one opening from the outside to restrain this portion, and when fitted into this portion, the plurality of grooves out of the plurality of grooves are formed. It is characterized in that a restraining portion having a concave portion is provided in a portion corresponding to the back side of the groove except for the predetermined groove.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

An embodiment of an induction hardening jig will be described with reference to FIG.

FIG. 1 is a perspective view showing an embodiment of an induction hardening jig according to the present invention.

The induction hardening jig 10 includes a ring-shaped restraining portion 20 having a circular hole 22 formed in the center, and four positioning rods 50. On the lower surface (back surface) of the restraining portion 20, four screw holes 24 are formed at equal intervals in the circumferential direction. A rod 50 is provided in each of the four screw holes 24.
Is screwed in and fixed. The length of each bar 50 corresponds to the height of an object to be heated (steel member 60) described later. Further, the number and the fixing position of the rods 50 also correspond to a flange 90 of an object to be heated (steel member 60) described later.
Easy positioning. Note that the rod 50 may be fixed to the restraining portion 20 by welding. Further, the rod 50 may not be provided.

The upper surface (front surface) of the restraining portion 20 is a flat surface. On the other hand, the inner portion of the lower surface (back surface) of the restraining portion 20 is more recessed than the outer portion. That is, the restraining portion 20
Is composed of a thinner inner ring 26 and a thicker outer ring 28. Although the inner ring 26 and the outer ring 28 are formed integrally, there is a step at the boundary between them. A step surface (an example of a contact portion according to the present invention) 30 of the step comes into contact with an upper portion of an outer wall surface 62 of a steel member 60 (see FIG. 2). In addition, the lower surface of the inner ring 26 contacts the upper end surface 64 of the steel member 60 (see FIG. 2). The inner diameter of the inner ring 26 is smaller than the inner diameter of the steel member 60. On the other hand, the inner diameter of the outer ring 28, that is, the inner diameter of the step surface 30 substantially matches the outer diameter of the cylinder of the steel member 60.

A feature of the outer ring 28 is that the concave portion 3 is provided at a position symmetrical with respect to the lower surface (at a position 180 degrees away from the central angle).
2 is formed. In this concave portion 32, the step surface 30 is cut, and in this portion, the step surface 30 does not contact the outer wall surface 62 of the steel member 60. Here, the concave portion 32 is an example of the non-contact portion according to the present invention. In FIG. 1, a groove-shaped recess 32 penetrating from the inner peripheral surface (step surface 30) to the outer peripheral surface of the outer ring 28 is formed, but from the inner peripheral surface of the outer ring 28 to a point in the radial direction. May be formed. In short, the portion of the steel member 60 that does not contact the outer wall surface 62 may be formed at a predetermined position determined by the steel member 60. Such a recess 32
The reason for forming is described later.

Referring to FIG. 2, a steel member to be induction hardened using the induction hardening jig 10 will be described.

FIG. 2A is a plan view showing a steel member, and FIG. 2B is a sectional view taken along line AA of FIG.

The steel member 60 has a cylindrical shape as a whole.
It has one cylinder 70 and four flanges 90. Cylinder 70
Are formed with upper and lower openings. The opening 72 formed above is an example of one opening according to the present invention, and the opening 74 formed below is an example of the other opening according to the present invention.

The inner wall surface 76 of the cylinder 70 has six grooves 78, 80, 82, 84, 86, extending in the height direction (arrow B direction) from the opening 72 to the opening 74 and having a substantially semicircular cross section.
88 are formed at equal intervals in the inner circumferential direction. Of these six grooves 78, 80, 82, 84, 86, 88, the four grooves 78, 82, 84, 88 (which are examples of the predetermined grooves in the present invention) correspond to the back side of the opening 74 side. Each portion is formed with a flange 90 projecting outward from the outer wall surface 62.

Accordingly, the outer wall surface 62 is a portion located on the peripheral edge of the opening 74 and has four grooves 78 and 8.
Flanges 90 corresponding to the rear sides of 2, 84 and 88 are formed. Also, two grooves 8
The flange 90 is not formed in the portion corresponding to the back side of the opening 74 side of 0,86.

Referring to FIGS. 3 and 4, induction hardening of a steel member 60 using the above-described induction hardening jig 10 will be described.

FIG. 3 is a cross-sectional view schematically showing a state in which the steel member 60 is induction hardened using the jig 10 for induction hardening. FIG. 4 is an explanatory diagram illustrating a positional relationship between the restraining portion 20 and the steel member 60.

The induction hardening apparatus 100 includes a jig 10 for induction hardening and a steel member 6 together with the jig 10 for induction hardening.
A turntable (not shown) for rotating the rotary member 0 and an induction heating coil 104 inserted from the opening 74 of the steel member 60 are also provided. A cooling jacket having a large number of cooling liquid ejection holes 106 is integrally fixed to the induction heating coil 104. . Further, the induction hardening apparatus 100 also includes a cooler 108 for cooling the steel member 60 from the outside.
A large number of ejection holes 110 for ejecting the cooling liquid are formed at 08.

The induction hardening jig 10 restrains the steel member 60 from the outside to reduce the deformation of the steel member 60. The constraining portion 20 is provided on a portion of the outer wall surface 62 of the cylinder 70 of the steel member 60 which is located at a peripheral portion of the opening 72.
It is fitted from the outside and restrains this part. Restraint part 20
In fitting, as shown in FIG.
Of the outer wall surface 62 is located at a portion corresponding to the back side of the upper portion of the grooves 80 and 86. As a result, of the upper portion of the outer wall surface 62, the portion (non-contact portion) 62a corresponding to the upper portions of the grooves 80 and 86 does not contact anything, and is not restrained by the restraining portion 20. on the other hand,
The upper surface of the outer wall surface 62 other than this portion is in contact with the step surface 30 and is restrained by the restraining portion 20.

If, for example, a convex portion 92 is formed below the outer wall surface 62 of the steel member 60 as shown in FIG. 3, this portion shrinks in the diameter direction after induction hardening, and the opening 74 becomes elliptical. May be deformed. In this case, if the lower portion of the outer wall surface 62 is placed in contact with the auxiliary jig 40, such deformation can be reduced. The shape of the auxiliary jig 40 is similar to the shape of the restraining portion 20.

The steel member 6 is formed by using the induction hardening device 100.
In induction hardening, the inner wall surface 76 of the steel member 60 is restrained from the outside by the restraining portion 20 while the inner wall surface 76 is heated to a quenching temperature equal to or higher than the austenite transformation point by the induction heating coil 104. After heating, the coolant is ejected from the coolant ejection holes 106 and 110 to rapidly cool the steel member 60 from inside and outside. This rapid cooling causes the inner wall surface 76
Is transformed into martensite. Thereafter, tempering is performed at a predetermined temperature.

As described in the section of the prior art, a flange 90 is formed on an outer wall surface portion of a plurality of grooves (here, grooves 78, 80, 82, 84, 86, 88) corresponding to the back side of the grooves. At the positions of the grooves (the grooves 80 and 86 in this case), there is a possibility that the cylindrical steel member 60 shrinks in its diameter direction and the opening 72 becomes elliptical. However, as a result of induction hardening using the above-described induction hardening jig 10, shrinkage in the diameter direction is reduced at the outer wall portion corresponding to the back side of the grooves 80 and 86, as will be apparent from the experimental results described later. Thus, the deformation of the opening 72 is reduced.

The reason is that the lower end of the steel member 60 where the flange 90 is formed is constrained by the flange 90 and the thick portion during the heat treatment. In order that the flange 90 and the thick portion are also formed,
This is because it was restrained by the induction hardening jig 10.
The groove 78, 82, 84, 88 and the groove 80, 86 have different effects from the flange 90 during the heat treatment. Therefore, it is considered that the recess 32 is formed in the induction hardening jig 10 in consideration of this point. Can be

With reference to FIG. 5 and Table 1, a description will be given of a change in the inner diameter when the tubular steel member 60 is induction hardened using the above-described induction hardening apparatus 100.

5A and 5B show a measurement position of the inner diameter, FIG. 5A is a plan view, and FIG. 5B is a cross-sectional view as viewed from the side. Table 1 shows the measurement results of the inner diameter.

The material of the steel member 60 used in the experiment was S53.
C (JIS standard), external dimensions 62.6m high
m, inner diameter 77.3 mm, wall thickness 5 to 10 mm. When the inner wall 76 of the steel member 60 was induction-heated, the frequency of the high-frequency power supply was 30 kHz, the output was 350 kW, and heating was performed for 2.5 seconds. In addition, when cooling after heating, the cooling liquid was ejected from the cooling liquid ejection holes 106 and 110 (see FIG. 3) for 10 seconds to rapidly cool.

The measured inner diameter is the inner diameter R1 between the groove 80 and the groove 86, the inner diameter R2 between the groove 82 and the groove 88, and the groove 7
The inner diameter R3 between the groove 8 and the groove 84. In addition, the steel member 6
The measurement positions in the height direction 0 are a position (a) 15 mm from the upper end surface 64, a center (b) in the height direction, and a position (c) 45 mm from the upper end surface. Table 1 shows the measurement results. The measurement results shown in Table 1 show the difference from the inner diameter (reference inner diameter) before induction hardening.

[0031]

[Table 1] As shown in Table 1, even after induction hardening, the inner diameter became almost the same at any position, and it was found that the shrinkage in the diametrical direction at the outer wall portion corresponding to the back side of the grooves 80 and 86 was reduced.

[0032]

As described above, by using the first induction hardening jig of the present invention, the non-contact portion of the ring-shaped restraining portion is positioned on the outer wall surface which is easily contracted in the diameter direction. By constraining the outside of the outer wall with the constraining portion, the shrinkable outer wall portion can be freely expanded by heating, and the amount of free expansion and the amount of shrinkage after quenching are balanced, and as a result, The amount is reduced.

Further, according to the second induction hardening jig of the present invention, in the restraining portion, a concave portion is formed in a portion corresponding to the back side of the plurality of grooves excluding a predetermined groove. Therefore, the portion corresponding to the back side of the groove excluding the predetermined groove can be freely expanded by heating, and the amount of this freely expanded and the amount of shrinkage after quenching are balanced, and as a result, the amount of shrinkage is reduced .

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an induction hardening jig according to the present invention.

FIG. 2A is a plan view showing a steel member,
(B) is AA sectional drawing of (a).

FIG. 3 is a cross-sectional view schematically showing a state in which a steel member is induction hardened using an induction hardening jig.

FIG. 4 is an explanatory diagram showing a positional relationship between a restraining portion and a steel member.

5 (a) is a plan view, and FIG. 5 (b) is a cross-sectional view as viewed from the side, showing a measurement position of an inner diameter of a steel member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Induction hardening jig 20 Restraining part 30 Step surface 32 Depression 50 Bar 60 Steel member 62 Outer wall surface 78, 80, 82, 84, 86, 88 Groove 90 Flange

Claims (2)

[Claims] 1. An induction hardening jig for restraining an outer wall surface of an object to be heated from the outside when the inner wall surface of the cylindrical object to be induction hardened is provided. A jig for induction hardening, comprising a ring-shaped restraining portion for restraining the outer wall surface from outside, wherein a contact portion that contacts the outer wall surface and a non-contact portion that does not contact the outer wall surface are formed. . 2. A tube formed on an inner wall surface with a plurality of grooves extending in a height direction from one opening or its vicinity to the other opening or its vicinity, and a plurality of grooves formed on an inner wall surface. An inner wall surface of the object to be heated, comprising: a portion located at a peripheral portion of the other opening; and a flange formed at a portion corresponding to a back side of a predetermined groove among the plurality of grooves. In the induction hardening jig for restraining the object to be heated when induction hardening is performed, the outer wall of the cylinder is fitted from the outside into a portion located at a peripheral portion of the one opening, and this portion is restrained. And a restraining portion having a recess formed in a portion corresponding to the back side of the plurality of grooves except for the predetermined groove when fitted into the portion. Necessary jig.