JPS6349879B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an induction heating coil that makes it possible to form a predetermined number of closely spaced horizontal striped surface hardening layers around the inner wall of a small-diameter cylinder.

Cylinders of various sizes are used as mechanical parts, and very often the entire inner wall of the cylinder or only a predetermined surface is used as a sliding surface. When the inner wall of a cylinder is used as a sliding surface, surface hardening treatment is performed to increase wear resistance, as is the case with other parts. It has been praised for its ability to locally harden the required areas and its excellent productivity.

However, if we talk about the current situation when surface hardening is performed by induction heating on the inner wall of a small-diameter cylinder, such as one with a diameter of 100 mm or less, especially 50 mm or less, even if the inner wall is a cylinder with only a predetermined portion of the inner wall serving as a sliding surface. However, due to the constraint that the inside of the cylindrical body cavity is extremely narrow, conventional heating coil designs have limited quenching to the entire circumferential surface of the inner wall. This will be explained using FIG. For example, a heating coil C', which has a plurality of turns around the outer circumferential diameter that separates the inner wall and a predetermined gap, is inserted into the cavity of a cylinder W whose one end face is closed from the direction of the open end face, and the cylinder W is closed. As the axis is rotated as shown by the arrow, the heating coil C' is energized, and the cylindrical body W is heated over the entire inner wall circumference by the action of magnetic lines of force generated from the heating coil C' due to the energization, to a predetermined temperature. When this temperature is reached, the power supply is stopped and the entire wall circumference is rapidly cooled and hardened with a jet of cooling liquid. The heating coil C' used in this case is constructed by winding a single conductor diagonally multiple times so as to have a predetermined coil length, so that the lines of magnetic force generated from each winding conductor are aligned with the coil axis as shown by the dotted line. The result is a combined magnetic flux φ along the direction, and the entire inner wall periphery facing the entire length outer periphery of the heating coil C' is heated.

Hardening of the entire circumferential wall of the inner wall of a small-diameter cylinder using a conventional heating coil as described above does not cause any problems if the cylinder wall is sufficiently thick, but if the cylinder wall is thin, quenching distortion may occur. The problem was that the cylindrical body was deformed by the process, resulting in a large number of non-conforming products. As a solution to this problem, if you do not harden the entire circumference of the inner wall, but instead form a hardened layer partially, or form a hardened layer only in particularly necessary areas, you can prevent the occurrence of hardening distortion. Although it has been proposed that it can provide wear resistance, there is no way to implement the above solution in the extremely limited cylindrical body cavity space as described above, and this solution has been desired.

The present invention has been created to meet the above-mentioned needs and provides an induction heating coil that can provide wear resistance by forming a hardened layer in the form of horizontal stripes on the inner wall of a small-diameter cylinder that is free from the risk of hardening distortion.

The basic idea of the present invention will be explained with reference to FIGS. 2a to 2c. For example, a case will be described in which four horizontally striped surface hardening layers are formed at equal intervals around the inner wall of a small-diameter cylindrical body. The number of turns of the conductor c of the heating coil C of the present invention is 4 turns, which is the same as the number of stripes to be formed. Therefore, each of the wound conductor parts c ₁ , c ₂ , c ₃ and c ₄ has a winding circumference on a virtual plane P ₁ , P ₂ , P ₃ and P ₄ that maintains equal intervals in the direction perpendicular to the coil axis. It is wound in a similar manner, and is wound in reverse winding alternately. Therefore, if the wound conductor part c ₁ wound on the virtual plane P ₁ located at the forefront from the heating power source E is wound, for example, in the counterclockwise direction indicated by the arrow, then the next virtual plane P The wound conductor part c ₂ wound on the _third virtual plane P 3 is wound clockwise, and the wound conductor part c ₃ on the third virtual plane P ₃ is wound in the opposite direction to the wound conductor part c _2. The winding conductor portion c _{4 on the fourth virtual plane P 4 is} wound clockwise in the opposite direction to that of the winding conductor portion c ₃ . Therefore, at the beginning of winding, the conductor c constituting each winding conductor portion c ₁ , c ₂ , c ₃ and c ₄ is wound perpendicularly from the coil axis center direction and bent in the circumferential direction, and at the end of winding, It returns to the direction of the coil axis center and moves to the next virtual plane P near the coil axis center. As shown in Figure 2b, the heating coil with the above configuration generates lines of magnetic force that are in opposite directions between the adjacent ones, so the coil axis is similar to that generated in the conventional heating coil C' shown in Figure 1. The resultant magnetic flux φ along the direction is never the same. In the heating coil C of the present invention, the lines of magnetic force are canceled out at the midpoint n of the parallel conductors c, so the surface to be heated corresponding to the midpoint is theoretically not affected by the lines of magnetic force, and there are separate areas e affected by the lines of magnetic force. It will be formed. Of course, since the induced heat generation in the magnetic field line affected zone e is transmitted by thermal conduction, no limitless temperature rise occurs. However, it is effective to prevent the occurrence of quenching distortion by keeping the thermal influence as local as possible and preventing it from affecting the entire circumference of the inner wall. Very often, the periphery is the only part that requires wear resistance. To achieve this purpose, the present invention provides each winding conductor portion c ₁ ,
For c ₂ , c ₃ and c ₄ , a core made of a magnetic material, for example, is attached to each wound conductor portion c so that the lines of magnetic force generated from the conductor portion c are converged and concentrated only on the opposing inner wall surface of the wound conductor c. It is an additional configuration. Although not shown in the conventional heating coil C' shown in FIG. 1, a core is often used. However, in the conventional heating coil C', the core was used for the purpose of guiding the lines of magnetic force generated toward the inner circumference of the coil into effective magnetic flux toward the outer circumference of the coil, but the present invention Then, each winding conductor part c
In addition to the effect of effectively directing the lines of magnetic force generated toward the inner circumference of the coil toward the outer circumference of the coil, the lines of magnetic force effectively directed toward the outer circumference of the coil are converged to form a predetermined area facing the wound conductor portion c. It is used to concentrate the action only on the inner wall portion and to provide a portion unaffected by the lines of magnetic force between the mutually adjacent wound conductor portions c and the opposing inner wall portion. That is, as shown in FIG. 2c, by adding a core ko to each wound conductor part c, a hardened layer h is formed on the inner wall of the small diameter cylindrical body W, which corresponds approximately to the opposite surface of the wound conductor part c. The purpose is to form a non-hardened portion N between each of the hardened layers.

A heating coil implementing the above-mentioned basic idea is shown in FIG. The heating coil C has an outer diameter of 60 mmφ and an inner diameter of 50 mm.
It was created in order to form three surface hardening layers h around the inner wall of a cylindrical body W whose both end faces are open at mmφ. The distance between the centers of the first surface hardening layer h ₁ and the second surface hardening layer h ₂ is 15 mm, and the second surface hardening layer h ₂
and the third surface-hardened layer h ₃ The distance between the centers of each is 20 mm, and the width of each surface-hardened layer h is approximately 8 mm.
It is designed to be approximately mm. Therefore c ₁ ,
The three-turn conductor sections, denoted c ₂ and c ₃ , are wound on a virtual plane that maintains the above-mentioned spacing, and the wound conductor sections c ₁ , c ₂ and c ₃ have cores ko ₁ , ko _{2 ,} respectively.
and ko ₃ are fitted. R is a coolant distribution chamber, which is connected to the liquid supply pipe P and is connected to each core.
An injection hole J is provided for injecting a quenching coolant toward the outer circumference through the space between the holes. Although not shown, cooling water for self-cooling of the heating coil C is passed through the pipe of the conductor C. In this case, the thickness of the cylinder wall is 5
mm, it is preferable to inject a cooling liquid onto the outer periphery of the cylindrical body W during the quenching process to prevent the quenching layer from deepening, and this also leads to prevention of quenching distortion. In addition, what is shown as S in the figure is a spacer provided between the wound conductor parts.

Insert the heating coil C into the cylindrical body W, and
When the hardening process is performed while rotating the cylinder, a horizontally striped surface hardening layer consisting of h ₁ , h ₂ and h ₃ is easily formed around the inner wall of the cylinder without causing any hardening distortion, as shown in FIG.

In the induction heating coil according to the present invention, each winding conductor portion of a conductor having a predetermined number of turns constituting the heating coil is wound in a reverse direction and alternately so as to be on a plane perpendicular to the coil axis separated by a predetermined interval. At the same time, a magnetic material for converging magnetic lines of force is added to each of the wound conductor portions, making it possible to form the same number of horizontally striped surface hardening layers as the number of wound conductor portions spaced close to each other on the wall circumference of the small-diameter cylinder. By using this material, (1) it is possible to impart desired wear resistance to the inner wall of a small diameter cylinder without causing quenching distortion, and (2) it is possible to provide the desired wear resistance to the inner wall of a small diameter cylinder without causing quenching distortion. Since the position can be set so that the winding is done on a plane at a specified position, a hardened layer can be obtained only in the specified area. By setting the winding diameter of each corresponding wound conductor part, it is not only possible to form a surface hardening layer under the same conditions, but even if the specified position is a groove, it is possible to harden the surface only at the bottom of the groove. It is extremely effective for surface hardening of the inner wall of small diameter cylinders.

Furthermore, although the induction heating coil was invented for use with small-diameter cylinders, (4) it is not limited to small-diameter cylinders, and may cause problems when used for surface hardening of horizontal stripes around the inner wall of large-diameter cylinders. However, its practicality is enormous.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional front view for explaining the problems that exist in surface hardening of the inner wall of a small diameter cylinder using a conventional induction heating coil, and Fig. 2a is a perspective view schematically showing the structure of the conductor of the induction heating coil of the present invention. Figure 2b is a cross-sectional front view for explaining the magnetic lines of force generated by the wound conductor in the present invention and their effects, and Figure 2c is a cross-sectional front view for explaining the effects of the magnetic material used in the present invention. FIG. 3 is a cross-sectional front view of an induction heating coil according to an embodiment of the present invention. C...Induction heating coil, c...Conductor, _c1 , _c2 ,
c ₃ , c ₄ ... wound conductor section, P, P ₁ , P ₂ , P ₃ , P ₄ ...
Plane in the direction perpendicular to the coil axis, ko...Magnetic material for converging lines of magnetic force, W...Small diameter cylindrical body.

Claims (1)

[Claims] 1. The respective wound conductor portions of the conductor having a predetermined number of turns constituting the heating coil are alternately reversely wound so as to be on a plane perpendicular to the coil axis separated by a predetermined interval, and the respective wound conductor portions are A magnetic body for converging lines of magnetic force is added to the magnetic body, and a cooling fluid passage for hardening with an opening in the circumferential direction is provided between each of the magnetic bodies for converging magnetic lines of magnetic force, and a wound conductor part and a wound conductor part closely spaced from each other are provided around the wall circumference of the small diameter cylinder. An induction heating coil that enables the formation of the same number of horizontal striped surface hardening layers.