JPS6360097B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for induction hardening the inner peripheral surface of a thin cylindrical article having a flange portion.

B. Prior art In general, in induction hardening of the inner circumferential surface of a thin-walled cylindrical article with a wall thickness of 10 mm or less, the temperature rise due to induction heating occurs up to the outer circumferential surface of the article, and the expansion due to induction heating occurs in an unrestricted state, and internal stress In addition, in the case of articles with different wall thicknesses, the dimensions of each part change due to quenching, causing abnormal deformation during the cooling process. For these reasons, when the inner peripheral surface of a thin-walled cylindrical article is induction hardened, it deforms into a thin-walled cylindrical article,
There were problems with quenching cracks, etc.

Therefore, in order to solve the above problem, when the inner peripheral surface of a thin cylindrical article is induction hardened, by fitting and installing a restraining outer ring or outer cylinder on the outside thereof, uneven heating and uneven cooling can be achieved. There is an induction hardening method that corrects this and prevents induced deformation, quench cracking, etc. As this type of quenching method, for example,
There is a ``method for induction internal hardening of rings and cylinders'' described in Japanese Patent No. 43-17059.

In addition, when rolling life and fatigue life are required on the inner circumferential surface of this kind of cylindrical article, such as in bearings, constant velocity ball joints, etc., only the specified surface layer of the inner circumferential surface is quenched and hardened to extend each life. Since it is necessary to maintain the characteristics above a certain level, at this time, a restraining outer ring or outer cylinder is fitted and installed on the outside of the thin-walled cylindrical article, and cooling water is injected onto the outer peripheral surface of the thin-walled cylindrical article.
An induction hardening method is used that prevents an increase in the temperature of the outer peripheral surface and adjusts the depth of the hardened layer.

Figure 2 shows a ball transfer groove C formed on the inner circumferential surface B as shown in Figure 1 a and b using the above-mentioned hardening method.
This is an apparatus for induction hardening the inner circumferential surface B of a thin cylindrical article A having a petal-shaped flange portion D on the outer circumferential surface.

In the figure, 1 is a rotating main shaft of the object to be hardened, 2 is a main shaft bearing housing that rotatably supports the rotating main shaft 1 via a bearing 3, and 4 is a thin-walled cylindrical shape arranged on the upper part of the rotating main shaft 1 of the object to be hardened. Lower outer peripheral edge A of article A
This is a lower outlet ring for restraining 1.

5 is an upper outlet ring for restraining the upper outer peripheral edge A2 of the thin cylindrical article A placed above the lower outlet ring 4; 6 is an induction hardened coil bracket placed above the upper outlet ring 5; 7 is an induction hardened coil supported by an induction hardened coil bracket 6, and the upper outlet ring 5 and the induction hardened coil bracket 6 are arranged to be vertically movable.
Reference numeral 8 denotes an outer circumferential cooling jacket for cooling the outer circumferential surface of the thin-walled cylindrical article A held by the upper and lower concentrating rings 4 and 5; and a cooling jacket 9 for cooling the inner circumferential surface B of the thin-walled cylindrical article A to be quenched. A quenching cooling water nozzle (10) is a quenching cooling water nozzle drilled in the axis of the object rotation main shaft 1, and cooling water ejected from the quenching cooling water nozzle 9 is applied to the thin-walled cylindrical article A.
This is a rectifying plate for spraying uniformly onto the inner circumferential surface B of.

In order to perform induction hardening on the inner circumferential surface of a thin cylindrical article A having a petal-shaped flange portion D on its outer circumferential surface using the induction hardening apparatus having the above configuration, first, the induction hardening coil bracket 6 and the upper outlet are Place the thin cylindrical article A on the upper surface of the lower outlet ring 4 with the ring 5 waiting upward;
The lower outer peripheral edge A1 of the thin cylindrical article A is restrained (before quenching, there is a predetermined gap with the outer diameter surface of the article A). Next, the upper outlet ring 5 and the induction hardened coil bracket 6 are lowered, and the upper outer circumferential edge A2 of the thin-walled cylindrical article A is restrained by the upper outlet ring 5. At the same time, the induction hardening coil 7 supported by the induction hardening coil bracket 6 is placed inside the thin cylindrical article A. Then, in this state, rotate the main shaft 1 of rotation of the object to be quenched,
While rotating the thin cylindrical article A, the induction hardening coil 7 is energized, and the inner peripheral surface B of the thin cylindrical article A is heated.
Perform induction hardening. At this time, thin-walled cylindrical article A
Cooling water is sprayed onto the outer circumference of the thin-walled cylindrical article A from an outer circumferential cooling jacket 8 to prevent a rise in temperature of the outer circumferential surface of the thin-walled cylindrical article A. When the heating of the thin cylindrical article A is completed in this way, cooling water is sprayed from the quenching cooling water nozzle 9 onto the inner circumferential surface B of the thin cylindrical article A through the rectifying plate 10. Cool quickly. After that, after raising the induction hardening coil bracket 6 and the upper outlet ring 5, the thin cylindrical article A can be taken out from the induction hardening apparatus.

However, when induction hardening is performed on the inner peripheral surface B of a thin cylindrical article A having a petal-shaped flange portion D using the above-mentioned apparatus, there is no problem in terms of quench cracking and hardened layer depth, but quenching deformation occurs. I had a problem that was large, from /100 to 11/100. For this reason, the inner peripheral surface B of the thin cylindrical article A having the flange portion D of the petal
If there is a ball transfer groove C etc. in the ball transfer groove C,
In order to perform high precision grinding work efficiently, it is necessary to suppress the quenching deformation to 2/100, or at most 3/100. There was a problem that was said to lead to a decrease in efficiency.

The reason for the large quenching deformation during induction hardening of the inner peripheral surface of the thin cylindrical article A having the petal-shaped flange portion D is that when the inner peripheral surface of the thin cylindrical article A is induction hardened, the thin cylindrical article A begins to expand approximately in the circumferential direction, but the thickness of the thin cylindrical article A in the circumferential direction is uneven and the rigidity differs at each position in the circumferential direction.
The amount of expansion is different at each position in the circumferential direction, and at the same time, the elastic limit of article A is lowered due to heating and temperature rise. This seems to be because the thin cylindrical article A acts non-uniformly on the outer periphery of the thin cylindrical article A, causing local plastic deformation of the thin cylindrical article A.

Note that when the inner circumferential surface B of the thin cylindrical article A having the petal-shaped flange portion D is induction hardened, the thin cylindrical article A expands differently depending on each part.
Experimental data conducted to confirm that contraction occurs are shown in the graphs of FIGS. 5a and 5b. The quenching conditions at this time were to heat the thin-walled cylindrical article for 3.5 seconds at 40KHz without restraining the inner and outer peripheries, and then cool it for 8 seconds.
Figure 1 shows the expansion and contraction in the Y-Y direction, and Figure 5 b
is the expansion of the thin-walled cylindrical article A in the X--X direction in FIG.
The results are shown in which the shrinkage was measured using an electric micrometer. As can be seen from this graph, the thin cylindrical article A expands and contracts non-uniformly in each region.

B. Object of the invention To provide an induction hardening method that can minimize quenching deformation of a thin cylindrical article when induction hardening the inner circumferential surface of a thin cylindrical article having a petal-shaped flange portion on the outer circumferential surface. That's true.

C. Structure of the Invention While holding the cylindrical article A by means of outlet rings 28 and 29 having fitting parts 28a and 29a that fit into the inner peripheral surface B of the thin cylindrical article A having the flange part D on the outer peripheral surface, While cooling the outer circumferential surface of the cylindrical article A, the inner circumferential surface B of the cylindrical article A is high-frequency induction heated by the induction hardening coil 24, and after the induction heating, the inner circumferential surface B is rapidly cooled and hardened. ,
In addition, during rapid cooling, the inner circumferential surface B of the cylindrical article A, which has shrunk from its dimensions before induction heating, is attached to the center ring 2.
The fitting portions 28a and 29a of 8 and 29 are used to restrain and prevent quenching deformation.

D. Example FIG. 3 shows a first example of an induction hardening apparatus that performs induction hardening on the inner circumferential surface B of a thin cylindrical article A having a petal-shaped flange portion D by the method according to the present invention. FIG.

In Fig. 3, reference numeral 20 denotes a rotating main shaft of the object to be hardened, 21 a main shaft bearing housing that rotatably supports the rotating main shaft 20 of the object to be hardened via a bearing rig 22, 23 an induction hardened coil bracket, and 24 an induction hardened coil bracket. An induction hardening coil supported by a coil bracket 23, 25 an outer cooling jacket for cooling the outer periphery of the thin cylindrical article A, and 26 a quenching cooling water nozzle provided at the center of the main shaft 20 of rotation of the object to be hardened. , 27 is a rectifying plate attached to a lower inner diameter concentrating ring 28, which will be described later, and each of the above members may be the same as the conventional induction hardening apparatus shown in FIG.

Reference numeral 28 denotes a lower inner diameter concentrating ring installed above the rotation main shaft 20 of the object to be quenched, and 29 indicates an upper inner diameter concentrating ring disposed above the lower inner diameter concentrating ring 28 . The surfaces of the upper and lower outlet rings 28 and 29 are provided with stepped portions 28a and 29a, respectively, which serve as fitting portions that fit with the upper and lower inner circumferential edges B1 and B2 of the thin cylindrical article A, respectively.
The upper and lower inner circumferential edges B1 and B2 of the thin cylindrical article A are held by the stepped portions 28a and 29a. Note that the gaps between the stepped portions 28a, 29a and the upper and lower peripheral edges B1, B2 of the thin cylindrical article A are approximately 2/100 to 4/100, or each member is configured so that the gap is 0. I'll keep it.

A thin-walled cylindrical article A having a petal-shaped flange portion D is produced using an induction hardening apparatus having the above-mentioned configuration.
To perform induction hardening on the inner peripheral surface B, first, the thin cylindrical article A is placed on the lower inner diameter concentrating ring 28 with the induction hardening coil bracket 23 and the upper inner diameter concentrating ring 29 waiting upward. Lower inner peripheral edge B1 of thin cylindrical article A
is fitted into the stepped portion 28a of the lower inner diameter outlet ring 28. Next, induction hardened coil bracket 2
3 and the upper inner diameter outlet ring 29 is lowered, and the stepped portion 29a of the upper inner diameter outlet ring 29 is lowered.
At the same time, the induction hardened coil bracket 23 is fitted onto the upper inner circumferential edge B2 of the thin cylindrical article A.
An induction hardening coil 24 supported by is placed inside the thin-walled cylindrical article A. In this state, the rotating main shaft 20 of the object to be hardened is rotated to rotate the thin cylindrical article A, and at the same time, the induction hardening coil 24 is energized to perform induction hardening on the inner circumferential surface B of the thin cylindrical article A. . At this time, the outer circumferential surface of the thin cylindrical article A is cooled by the cooling water jetted from the outer circumferential cooling jacket 25. When the induction hardening of the inner circumferential surface B of the thin-walled cylindrical article A is completed in this way, cooling water is sprayed from the quenching cooling nostle 26 to the inner circumferential surface B of the thin-walled cylindrical article A through the rectifying plate 27, The inner peripheral surface B is rapidly cooled. After that is induction hardened coil bracket 23
After raising the upper inner diameter concentrating ring 29, the thin-walled cylindrical article A may be taken out from the induction hardening apparatus.

In this way, by performing induction hardening on the inner circumferential surface B of the thin cylindrical article A while holding the inner diameter side of the thin cylindrical article A, differences in wall thickness at various parts of the outer periphery of the thin cylindrical article A can be reduced. Therefore, even if the amount of expansion at each part of the outer periphery of the thin cylindrical article A is different, the outer periphery of the thin cylindrical article A is in an unrestricted state, so no plastic deformation occurs due to external compressive force.

Furthermore, after induction heating, due to the rapid cooling of the inner circumferential surface B of the thin cylindrical article A, the inner diameter dimension of the thin cylindrical article A tends to shrink from the dimension before induction heating, but the inner circumferential surface B of the thin cylindrical article A Upper and lower inner diameter outlet ring 2
8 and 29, the inner circumferential surface B of the thin cylindrical article A is fitted with the stepped portions 28a and 29a.
a, 29a, and temporarily enters a mold-hardened state during cooling, reducing quenching deformation.

6a and 6b show that when the inner circumferential surface B of the thin cylindrical article A is cooled as described above, the inner circumferential surface B of the thin cylindrical article A is It is a graph showing experimental data when induction hardening is performed on the inner circumferential surface B in a restrained manner. The quenching conditions at this time are:
After heating at 40KHz for 3.5 seconds, cooling for 8 seconds is shown. Figure 6a shows the expansion and contraction of the thin cylindrical article A in the Y-Y direction in Figure 1, and Figure 6b shows the thin cylindrical article A. The expansion and contraction of article A in the direction XX in FIG. 1 are measured using an electric micrometer.

As can be seen from this graph, when the inner circumferential surface B of the thin-walled cylindrical article A is cooled, the inner circumferential surface B is restrained, and the inner circumferential surface B of the thin-walled cylindrical article A is subjected to induction hardening. , quenching deformation can be kept to a minimum.

FIG. 4 shows another embodiment of the upper and lower concentrator rings to be installed in the induction hardening apparatus used when the inner circumferential surface B of the thin-walled cylindrical article A is induction hardened by the induction hardening method according to the present invention. It is a drawing. The upper inner diameter outlet ring 29 and the lower inner diameter outlet ring 28 shown in this figure are respectively a ring-shaped end outlet ring 28b,
29b and end outlet rings 28b, 29b
tapered cone outlet rings 28c, 29c slidably inserted into the inner periphery of the cone outlet rings 28c, 29c; pressurized spring presser covers 28d, 29d for closing one opening surface of the end outlet outlet rings 28b, 29b;
Tapered cone center ring 28c, 29c
The tapered cone center rings 28c, 2 are configured by pressurizing springs 28e, 29e press-fitted between the end faces of the pressurizing spring presser covers 28d, 29d, and the tapered cone center rings 28c, 2
Tapered Cone Concentration Ring 2 by 9c
8c and 29c are always pressed outward. In addition, a tapered cone center ring 28c,
Clamp bolt 2 for fixing the position of 29c
8f and 29f are installed.

In order to hold the inner circumferential surface B of the thin cylindrical member A by the upper and lower outlet rings 28 and 29, the tapered surfaces of the tapered outlet rings 28c and 29c are connected to the upper and lower inner circumferential edges B of the thin cylindrical article A.
1 and B2, tighten the clamp bolts 28f and 29f to fix the tapered cone center rings 28c and 29c.

In this way, the taper cone concentration rings 28c, 29c are used as the concentration ring, and the taper cone concentration rings 28c,
If 29c is made slidable, when the inner circumferential surface of the thin cylindrical article A is held by the outlet ring, the inner circumferential surface of the article A and the outlet ring 28c will be connected to each other regardless of variations in the inner diameter of the thin cylindrical article A. ，
29c The gap with the outer diameter surface can be ensured at 0.

In the above description, the present invention was applied to a thin cylindrical article A having a petal-shaped flange portion D on the outer circumferential surface. A thin-walled cylindrical article A' having two flange portions D', or an inner circumferential surface B', B'' of a thin-walled cylindrical article A'' having a cross-shaped flange portion D'' on the outer circumferential surface as shown in FIG. It can also be applied to induction hardening.

E. Effects of the Invention As described above, when induction hardening is performed on the inner peripheral surface of a thin-walled cylindrical article having a petal-shaped flange portion, the outer periphery of the thin-walled cylindrical article is in an unrestricted state when the inner peripheral surface is heated. In addition, when the inner circumferential surface is rapidly cooled and the inner diameter of the thin-walled cylindrical article tries to shrink from the dimension before induction heating, the inner circumferential surface is restrained, thereby reducing quenching distortion during induction hardening. can be kept as small as possible.

[Brief explanation of the drawing]

FIG. 1a is a plan view of a thin cylindrical article having a petal-shaped flange portion, FIG. 1b is a longitudinal cross-sectional view thereof,
FIG. 2 is a sectional view showing a conventional induction hardening device, FIG. 3 is a sectional view showing a first embodiment of the induction hardening device used in the present invention, and FIG. 4 is a sectional view showing a second embodiment. It is a diagram. Figures 5a and b are graphs showing the amount of expansion and contraction of the outer diameter when the inner peripheral surface of a thin-walled cylindrical article is induction hardened in an unrestrained state, and Figures 6a and b are graphs showing the amount of expansion and contraction of the inner circumferential surface of a thin-walled cylindrical article. It is a graph showing the amount of expansion and contraction of the outer diameter dimension when induction hardening is performed on the inner circumferential surface while the circumferential surface is restrained. FIGS. 7 and 8 are plan views showing other shapes of the thin-walled cylindrical article. A, A′, A″…thin cylindrical article, B, B′, B″…
Inner peripheral surface, D, D', D''...Flange part, 24...Induction hardened coil, 25...Outer cooling jacket, 28
...Lower inner diameter outlet ring, 29...Upper inner diameter outlet ring.

Claims (1)

[Claims] 1. A method of induction hardening the inner circumferential surface of a thin cylindrical article having a flange portion on the outer circumferential surface, the method comprising: induction hardening the inner circumferential surface of a thin cylindrical article having a flange portion on the outer circumferential surface, the cylindrical article being while holding
While cooling the outer circumferential surface of the cylindrical article, the inner circumferential surface of the cylindrical article is high-frequency induction heated by an induction hardening coil, and after induction heating, the inner circumferential surface is rapidly cooled to perform hardening. A thin-walled cylindrical article having a flange portion, characterized in that the inner circumferential surface of the cylindrical article, which has shrunk from its dimensions before heating, is restrained by the fitting portion of the above-mentioned center ring to prevent quenching deformation from occurring. A method for induction hardening the inner peripheral surface of an article.