JPH0457728B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides induction heating for relatively narrow widths such as a locally predetermined width peripheral surface of a cylindrical member, a peripheral surface of a disc-shaped member, and an inner and outer peripheral surface of an annular member. The present invention relates to a one-shot quenching cooling method and apparatus for surface quenching.

(Prior art) Normally, relatively narrow widths such as the local predetermined width circumferential surface of a cylindrical member, the circumferential surface of a disc-shaped member, and the inner and outer circumferential surfaces of an annular member are targeted for hardening, and the diameter of the member is relatively small. In this case, a one-shot quenching method is used in which a heating coil suitable for the quenching width is used, the member and the heating coil are opposed to each other in a fixed position without relative movement in the axial direction, and the member is heated and rapidly cooled while rotating the shaft. used.

A conventional one-shot quenching cooling method will be explained below with reference to FIG. 3a.

In FIG. 3a, W is an annular member, and its inner peripheral surface is hardened to serve as a sliding surface. Heating coil used for hardening the inner peripheral surface
C' is made of a tube material, and a large number of pores s are provided on the outer circumferential surface of the member W that faces the hardened inner circumferential surface.
A cooling fluid supply pipe H connected to a cooling fluid supply source is opened in the heating coil C' pipe, and when cooling fluid is supplied, the cooling fluid for quenching is supplied to the opposite surface of the member W from the small hole s via the heating coil C' pipe. It is possible to inject towards.

In the quenching operation, first, a heating coil C' is arranged to face the inner periphery of the member W to be quenched, the heating coil C' is energized to heat the periphery to be quenched to a predetermined quenching temperature, and then the cooling fluid is supplied to the cooling fluid supply pipe. Heating coil from H
The cooling fluid flowing into the tube of C' is ejected from the pores s and impinges on the heated surface to rapidly cool and harden the circumferential surface, and also removes the self-heated heat of the heating coil C'. (If the heating time is long, use the heating coil.
For cooling C', a cooling fluid circulation pipe fixed to the outside of the pipe may be used. ) By the way, this applies not only to one-shot quenching but to all types of quenching cooling. When the quenching liquid comes into contact with a heated surface that has been heated to at least the quenching temperature, it instantly vaporizes and forms a vapor film. , which prevents the vapor film from coming into direct contact with the heated surface of the following liquid and impedes the cooling effect. Therefore, while rotating the member, the cooling fluid is injected at an injection pressure sufficient to break through the vapor film. It is customary to do so.

(Problems with conventional technology) In the conventional one-shot quenching cooling method, since the member is rotated on its axis, a substantially uniform quenching finish can be obtained over the entire circumferential direction of the heated peripheral surface.
Satisfactory results have not always been obtained regarding the finish in the width direction.

This is because the width of the heating coil C' should be approximately the same as the quenching width as shown in Fig. 3a, or if the circumferential surface is a ball race track, as shown in Fig. 3c. The width is smaller than the hardened width. Therefore, in the former case, the cooling fluid injection holes s provided in the heating coil C' strike the heated circumferential surface from a right angle direction, and in the latter case, the cooling fluid injection holes s spread out in a fan shape to cover the quenching width. The cooling fluid ejected from the injection holes s, which are drilled so as to cover and collide with each other, behaves as shown in FIGS. 3b and 3c, respectively.

In other words, the cooling fluid ejected from the injection holes s comes into contact with the opposing surface through an extremely narrow gap (usually about 1 to 3 mm)...the coil clearance, and then reverses upward at the upper side and tries to flow down. However, because the flow force is strong at the center in the width direction, the flow is delayed and tends to stagnate near the edge.The fluid flows downward on the lower side, but near the edge, the fluid has heated up due to heat removal. There is a tendency to concentrate, and when the hardened surface is examined closely, the quenched hardness is lower at both edges in the width direction than at the center, although it is slightly smaller, and the depth is shallower, resulting in an uneven finish.

Furthermore, in the one-shot quenching process, as mentioned above, because the coil clearance is narrow and because the heating coil itself, which primarily performs the heating action, also serves as the cooling mechanism, it is necessary to ensure an injection pressure sufficient to break the vapor film. Although injection holes are provided, the diameter of the injection holes is naturally limited and the hole diameter cannot be increased, so a large flow rate of the cooling fluid cannot be obtained, and the quenched hardened layer and effective hardened layer are not deep enough. The weakness was that it could not be formed.

Until now, it was considered that the above-mentioned slight non-uniform finish in the width direction of the hardened surface by conventional methods was unavoidable, and the shallowness of the hardened layer and the effective hardened layer was also tacitly accepted. Due to the trend toward more sophisticated equipment, precise uniformity of the surface to be hardened and higher durability of the surface to be hardened are strongly required, and a situation has arisen in which countermeasures are required.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems of conventional methods and devices for one-shot hardening the circumferential surface of a member. It is an object of the present invention to provide a quenching cooling method and apparatus that can achieve a precisely uniform quenching finish in the width direction and form a deep quench-hardened layer and an effective hardened layer.

(Structure of the Invention) The structure of the first invention of the present application is such that, in one-shot quenching in which a predetermined width of the circumferential surface of an axially rotating member is heated to a predetermined quenching temperature with heating coils facing the predetermined width and then rapidly cooled, the rotating state of the member is determined. The present invention provides a one-shot quenching cooling method for a circumferential surface of a member, characterized in that the entire circumferential surface to be heated is rapidly cooled with a plurality of fluids divided in the circumferential direction and jetted alternately in opposite directions.

Further, the configuration of the second invention of the present application for carrying out the method of the first invention of the present application includes a heating coil and a member capable of heating a predetermined width of the circumferential surface of the member that rotates around the shaft. In a one-shot hardening device that is equipped with a cooling mechanism that can rapidly cool the circumferential surface to be heated without relative movement in the axial direction, the cooling mechanism is arranged to sandwich the heating coil from both end faces, and holes are provided in each cooling mechanism. The cooling fluid injection holes for quenching are divided into a plurality of holes at the same angle in the circumferential direction, and the holes are installed in intermittent hole ranges and in the opposite intermittent hole ranges in the same angle range, and the cooling of each cooling mechanism is There is provided a one-shot quenching and cooling device for a circumferential surface of a member, characterized in that the perforation angles of the fluid injection holes are directed from the width direction toward the surface to be heated.

(Function of the invention) The present invention provides a plurality of cooling streams divided into a plurality of parts in the entire circumferential direction and alternately injected in opposite directions onto the peripheral surface of a predetermined width heated to a predetermined quenching temperature of a rotating member. The cooling fluid is made to flow alternately from one side to the other side in the width direction and from the other side to the other side with almost no restriction on the flow rate, and the steam generated when the cooling fluid touches the heated surface is spread across the width. At the same time, the upper edge in the width direction does not have time for the cooling fluid to accumulate, and the lower edge has no time for the cooling fluid to accumulate due to heat absorption. It works to prevent only fluid from flowing down.

(Example) The present invention will be described in detail below using an example apparatus shown in FIGS. 1a and 1b.

In this embodiment, the race track of an annular member W whose inner peripheral surface is a ball race track is hardened. As shown in FIG. 1a, the heating coil C is in this case made of a circular tube material in order to form a hardened layer, indicated as Wh, on the concave surface. For example, the cooling mechanism according to the present invention penetrates through the winding of the heating coil C and has an integral structure, but in the internal structure described later, it is substantially divided into two parts, and the heating coil C has both ends. There are two mechanisms shown as Ja and Jb arranged to sandwich this from the surface direction.
In other words, the mechanism has a cavity inside, and the cavity is a cooling mechanism partitioned by plates perpendicular to the axial direction.
Divided into Ja and Jb. Therefore, the cooling mechanism Ja
A cooling fluid supply pipe Ha is opened in the cavity of the cooling mechanism Jb, and a cooling fluid supply pipe Hb is opened in the cavity of the cooling mechanism Jb. In addition, the circumferential surface of each of the cooling mechanisms Ja and Jb is divided into 6 parts of the entire circumference of 360°, as shown in Figure 1b, which shows this as a developed view, and the cooling fluid injection holes s are arranged at intervals of 60°. The hole formation range is intermittently continuous, and Ja and Jb are alternated in the circumferential angle range corresponding to the hole formation range of the cooling fluid injection holes s. Furthermore, as shown in Figure 1a, the cooling fluid injection holes s are provided diagonally downward to the outside in the cooling mechanism Ja, and diagonally upward to the outside in the cooling mechanism Jb. The hole diameter is set to be much larger than that in conventional cases where the heating coil also serves as a cooling mechanism.

When hardening is performed using the above device, the heating coil C and the member W are positioned facing each other, the member W is rotated, and the heating coil C is energized for a predetermined period of time from a power source (not shown). The inner race track surface is heated to a predetermined quenching temperature, and after the energization is stopped, cooling fluid is introduced into the cooling mechanisms Ja and Jb through the cooling fluid supply pipes Ha and Hb, respectively. A sufficient flow of cooling fluid introduced into the cavities of the cooling mechanisms Ja and Jb immediately fills the cavities, and then the cooling fluid injection holes s provided in each of the cavities are filled.
The jet of cooling fluid impinges on the rotating heated surface in the direction according to the hole installation angle, and then the jet of cooling fluid jetted from the cooling fluid injection hole s of the cooling mechanism Ja as shown in Fig. 1c. Follow the arrow drawn by the dashed line to locate the cooling mechanism.
The jet of cooling fluid injected from the cooling fluid injection hole s of Jb rushes over the heated surface according to the arrow drawn by the solid line, and then flows away.

In this case, the large flow jet of cooling fluid injected from the cooling fluid injection holes s of each of the cooling mechanisms Ja and Jb absorbs the steam generated from the heated surface corresponding to the flow path from the lateral direction without giving time for the formation of a steam film. At the same time, the jet flows obliquely because the member is rotating. At the same time, the jet flows from the cooling fluid injection hole s of the cooling mechanism Jb and flows upward over the heated surface, and the upper end of the heated surface in the width direction The cooling fluid that has reached the edge does not have time to stay at the upper edge, and flows down on the torrent of cooling fluid injected from the cooling fluid injection hole s of the adjacent cooling mechanism Ja, which flows downward. , and only the cooling fluid whose temperature has increased due to heat removal from the heated surface does not flow to the lower edge.
The surface to be heated is rapidly cooled uniformly over the entire circumference and in the width direction to a depth toward the core.

(Example) The present inventor conducted the following experiment in order to confirm the effects of the present invention.

○ Experimental method: An inner race member having the same dimensions and the same material and shape as shown in Figure 1a was used as the specimen, and the heating conditions were the same, but the A specimen was heated using the cooling method of the present invention as shown in Figure 1. Embodiment of the method Using an apparatus, the B specimen is rapidly cooled and quenched using an apparatus according to the conventional cooling method shown in FIG. The hardness of each cross section indicated by X and Y of the hardened layer was measured.

○Hardness measurement test results: Plot the hardness measurement test results on a chart with hardness (Hv) on the vertical axis and distance from the surface on the horizontal axis, and plot the X cross-section in Figure 2b and the Y cross-section in Figure 2b. Shown in Figure 2c. Curves XA and YA in each figure represent the results of the specimens implemented by the present invention, and curves XB and YB represent the results of the specimens implemented by the conventional cooling method.

From the results of the above experimental examples, it was confirmed that the present invention forms a uniform and deep hardened layer and effective hardened layer regardless of the center portion and the edge portion in the width direction.

(Other Examples) In the above example, the case where the concave surface of the inner circumferential surface of the annular member was used as the surface to be hardened was described, but not only the concave surface but also a flat surface can be similarly hardened using the same cooling mechanism as in the example. Even when quenching and cooling are performed and the concave or flat outer circumferential surface of the annular member is to be hardened, the heating coil should be opposed to the outer circumferential surface of the annular member, and the cooling mechanism should be arranged in the direction of both end faces of the heating coil. For example, the surface to be heated can be uniformly and deeply quenched over the entire circumference and width direction by the same principle as in the above embodiment.

The quenching and cooling method of the present invention is applicable not only to the annular member of the above embodiment, but also to one-shot quenching when induction heating surface quenching is performed on a relatively narrow circumferential surface of a cylindrical member with a predetermined width, the circumferential surface of a disk-like member, etc. equipment is applicable.

In addition, in the above embodiment, the cooling mechanism disposed on both end faces of the heating coil has an integral structure in appearance but is internally divided into two parts. Alternatively, the cooling mechanism may be an annular body depending on the size of the inner diameter or outer diameter of the member.

Furthermore, the circumferential dividing angle of the cooling fluid injection hole installation range is not limited to the angle in the embodiment, and although it is not preferable to make it too large, it may be set arbitrarily; This is a design matter, and can provide the same functions and effects as those of the above embodiment.

(Effects of the Invention) If the present invention is implemented when the peripheral surface of a member is one-shot hardened, the hardened finish is precisely uniform not only in the circumferential direction but also in the width direction, and a deep hardened layer and effective hardened layer can be formed. It is highly effective as a means of improving hardening technology in line with the trend toward more precision and longer durability of machinery and equipment.

[Brief explanation of drawings]

FIG. 1a is a cross-sectional front view of an apparatus according to an embodiment of the present invention, FIG.
FIG.
Figure a is a cross-sectional view of the specimen showing the hardness measurement position in the experimental example, Figures 2b and c are diagrams showing the hardness measurement test results, respectively, and Figure 3a is a member produced by an apparatus based on the conventional method. FIGS. 3b and 3c are sectional front views for explaining one-shot hardening of the circumferential surface, and FIGS. 3b and 3c are sectional front views for explaining problems existing in the conventional method, respectively. W... Member, C... Heating coil, Ja, Jb...
Cooling mechanism, s...cooling fluid injection hole.

[Claims]

1. A work coil is provided so as to be able to move relatively back and forth along the surface to be processed of the work, and a gap sensor is provided whose stylus portion presses against the surface to be processed of the work to detect a gap between the work and the work coil. In an automatic high-frequency hardening apparatus, the apparatus includes a gap control means for moving the work coil forward and backward in a direction orthogonal to the traveling direction thereof in order to maintain the gap at a predetermined value in accordance with a detection signal from the gap sensor.
An edge detection sensor for detecting an edge of the surface to be processed of the workpiece is provided, and a position control means is provided for causing the gap sensor to come into contact with and separate from the surface to be processed of the workpiece in accordance with a detection signal from the edge detection sensor. Features: High frequency automatic hardening equipment.