JPS609822A - Method and heating coil for non-uniform tempering of step part of stepped member and its neighboring part - Google Patents

Abstract

PURPOSE:To heat easily and uniformly the step part of a stepped member and its neighboring part with one-shot heating by heating the large-diameter parallel part and small-diameter parallel part of said member at the different heating rates by separate conductors and heating the step and its neighboring part by the heat conducted from both parallel parts. CONSTITUTION:Heating of an axially rotating work W by using heating coils is accomplished by impressing the magnetic flux phis generated from a conductor CS in the prescribed circumferential angle part to the part to be heated of the small-diameter parallel part S of said work and the magnetic flux phil generated from a conductor CL in the remaining circumferential angle part to the part to be heated of the large-diameter part L respectively at the different density per unit area and heating said parts to the different temps. within the prescribed time by impressing said magnetic fluxes respectively without deviation in the longitudinal direction of the parts to be heated. The step part sandwiched by both parts to be heated is heated mainly by the heat inflow from both parts to be heated and partly by the slight heat generated by the magnetic fluxes leaking from the conductors CS and CL according to the above-mentioned heating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for uneven tempering near the step portion of a stepped member and a heating coil for uneven tempering.

A stepped member W having a large diameter portion and a small diameter portion S as shown in FIG. 1 is often used as a component of mechanical devices. The stepped member W may have screws or splines formed on both the large diameter portion and the small diameter portion S, or may have screws or splines formed on either one, or may have no screws or the like at all, depending on the usage. There are various methods, but in order to improve the mechanical strength or wear resistance of a predetermined length of the stepped portion and both parallel portions following the stepped portion, the portion is surface hardened and then tempered after the surface hardening. This is required. Therefore, in the above-mentioned tempering, there are cases where it is required to heat one side of the parallel part and the other side at a different temperature so that each part has a different hardness after tempering1. Induction heating, which requires extremely short heating time, is used for heating, especially when heating short and small ranges. For 1L, one shot heating with a single-turn heating coil is required during treatment +Mj
Although it is convenient, a single-turn heating coil can be used to assemble the stepped part of the stepped member, and the stepped gold ingot can be heated at a predetermined length of one parallel part and a predetermined length of the other parallel part. Due to the characteristics of induction heating, it is extremely difficult to heat with a difference.

The reason for this difficulty will be explained below.

That is, as shown in FIG. 1(a), a predetermined length portion of a small diameter portion S and a predetermined length portion of a large diameter portion of a stepped member (hereinafter referred to as a work) W are tempered at a tempering temperature TS of the small diameter portion S, for example. The tempering temperature is set to 4 (TS) TL from the tempering temperature TL at the large diameter of the grape. In this case, with the conventional single-turn heating coil, in accordance with the characteristics of induction heating, the inner circumferential wall of the workpiece W? In the part C'S facing the small diameter part S, there is a gap fs' (i7 small,
In the part C'L facing the large diameter part, the gap ftf is made large, and in the stepped part, a groove C'A is provided to avoid overheating of the shoulder A, and a collar C'B is provided to avoid insufficient heating of the corner B. In order to prevent the quenching hole width from escaping due to magnetic flux leakage near the end face of the coil, an extremely complicated structure such as providing a proximal portion C'D'z is unavoidable. The technical idea on which this heating coil is based is that, as shown in Fig. 1 (C), the magnetic flux C generated from a conductor C' that is half-wound with a width opposite to the entire length of the heated part of the workpiece W is , by adjusting the gap between the workpiece W and the inner wall of the conductor, making it denser in the small diameter part S and slightly coarser in the large diameter part, as well as adjusting the gap between the axis of the workpiece W in the stepped part. For points A and B#lc, which are at close distance on a plane almost perpendicular to O, point A, which is closer to conductor C' than point B, is separated in the direction of arrow The purpose is to guide the conductor in the direction of arrow Y to the point B which is far from the conductor C' in order to reduce the influence. For this reason, groove C'
A and the tsuba C'B are very delicately related to each other, and it is extremely difficult to set the width and depth of the groove C'A and the protrusion and length of the tsuba C'B, and it has taken many reworks. Currently, it is possible to create a heating coil C' that can achieve a heating effect close to uniform heating.Therefore, in order to create the heating coil C', it took a lot of skilled (~~) manufacturers to create the heating coil C'. This has been a problem because it requires a lot of time and cost to create the heating coil C', and the heating effect of the heating coil C' obtained thereby is still at a very low level.

The present invention uses a heating coil with a single turn all around the step part of a stepped member.
This was done for the purpose of solving problems existing in conventional heating methods and heating coils when performing uneven shot tempering.

The gist of the first invention is as follows: (1) A temperature difference is created between a predetermined length portion of one parallel portion and a predetermined length portion of the other parallel portion connected to the step portion of the stepped member. When tempering is applied at the same time,
(2) In a single-turn heating coil, the predetermined circumferential angle portion of the conductor is opposed to one parallel portion, and the remaining circumferential angle portion is opposed to the other parallel portion, and (3) Magnetic flux is generated from the conductor in the predetermined circumferential angle portion. (4) By making the magnetic flux generated from the residual circumferential angle partial conductor discontinuous and separate from the member, (4) each circumferential angle facing the predetermined length portion of each of both parallel parts of the stepped member that rotates on its axis; The vicinity of a stepped part of a stepped member, characterized in that the partial conductors are heated at individually different heating rates, and the stepped part is heated as a main temperature raising source from the parallel portion of the heated parallel part. In the uneven tempering method.

In other words, the technical idea of the present invention is to divide one turn of the conductor into two portions with predetermined winding circumference angles, to make the magnetic flux generated from each partial conductor independent and independent of each other, and thereby to separate all the parallel portions of the conductor into two. The purpose is to heat the step part sandwiched between the two parallel parts that are heated to different temperatures, and as a result, to raise the temperature by heat conduction of the step part sandwiched between the two parallel parts, which has a width equivalent to the entire length of the heating part like the conventional heating coil mentioned above. This is completely different from the concept of separating or guiding the magnetic flux generated from the wound conductor in the width direction.

The gist of the second invention for carrying out the uneven tempering method near the step of a stepped member of the first invention of the present application is as follows: (1) The step of the stepped member that rotates on its axis and both parallel parts connected thereto. (2) In the single-turn heating coil, a predetermined circumferential angle partial of the single-turn conductor in the single-turn heating coil is applied to one parallel part and the remaining circumferential angle part to the other parallel part. (3) The ends of the predetermined circumferential angle partial conductor and the remaining circumferential angle partial conductor are divided into conductors corresponding to the respective predetermined lengths of both parallel portions; (4) A desired difference per unit area is formed in each of the predetermined length portions of both parallel portions with the step portion as the boundary. The heating coil for uneven tempering near the stepped portion of a stepped member is characterized in that the amount of magnetic flux can be applied.

The heating coil according to the present invention will be described in detail below according to the embodiment shown in FIGS. 2(a) to 2(d).

In the heating coil C shown in FIGS. 2(a) to (c), the heating width of the small diameter portion S of the workpiece W is narrow, the heating width of the large diameter portion is relatively small, and the heating temperature is T8>TL. This applies to all cases. The single-turn conductor in the heating coil C is located at the small diameter portion S (9) and faces the conductor CS at a predetermined circumferential angle portion with a fixed gap between them, and the conductor CS at the large diameter portion with the same predetermined gap as above. The conductor CL of the remaining circumferential angle portion and the conductor C8 and CLi
It is composed of connecting conductors CJ-CJ.

The width of the conductor C8 is set to be small because the heating width of the opposing small diameter portion S is small, and the heating width of the large diameter portion facing the cut conductor CL is small. Of course. When connecting the end of the conductor C8 and the end of the conductor CL, each of the connecting conductors CJ and CJ connects the end of the conductor CL from the outer periphery of the part furthest away from the conductor CL in the width direction of the conductor CS. It is bent into a shape, that is, a forge, to connect the two. Therefore conductor C8 and connecting conductor C
A notch shown as K is formed between C8 and J. For example, in FIG. 2(d), the current flowing toward the end of conductor C8 at a certain moment is indicated by the arrow. As shown in FIG. 1, the conductor CJi is once pulled upward (10) and raised upward, and the connecting conductor CJi descends to reach the conductor CL, and then the conductor CLr (flows away toward the other end). This is where the most distinctive feature of the technical idea of the present invention is embodied, and by doing so, even if magnetic flux is generated from the connecting conductor CJ, it is shielded by the conductor C3-CL and has almost no effect on the workpiece W. Therefore, the magnetic flux 8 generated from the conductor C8 and the magnetic flux ρt generated from the conductor CL are discontinuous and separated.

Furthermore, the configuration of the above-mentioned connecting conductor CJ is conductor C8 and conductor CL.
This results in uniformity of current density in each width direction, that is, uniformity of magnetic flux density in the width direction. This can be clearly understood by comparing it with the comparative example described below.

Fig. 3 (a) to (e) Comparative example heating coil C (shown in K)
The conductor CIS facing the small diameter part S of Kuyuku W and the conductor C"L facing the large diameter part are connected at their respective ends by the shortest distance, and are similar to and different from the heating coil C according to the present invention. This is because the magnetic flux βS generated from the conductor CIS and the magnetic flux Ωt generated from the conductor C"L are shown in Fig. 3 (b).
), the magnetic flux generated from the connection part C'J is continuous with 0, and because of this, the current tends to flow through the shortest path, so the current concentrates at the corner part C'A of the connection part. flow,
Therefore, not only magnetic flux concentrates on the shoulder A of the workpiece W that the ridge C"A faces, but also current flows to the lower side in the width direction of the conductor C"S and the upper side of the conductor C"L in the width direction as shown. causes a tendency to concentrate and flow, and each conductor C “S-C”
This makes the magnetic flux density in the width direction in L non-uniform, resulting in almost no temperature rise in the vicinity of both ends of the heated portion of the workpiece W. Therefore, the comparative example heating coil C does not embody the technical idea of the present invention.

In the heating coil C according to the embodiment of the present invention described above, the heated portion of the small diameter portion S of the workpiece W is long, and the heated portion of the large diameter portion is relatively short. The heated portions of the small diameter portion S and large diameter portion of the heating coil CFi shown in FIG. This is an example of the case.

The connecting conductor CJ in the heating coil CVc has a small diameter portion S.
The outer periphery of the upper part of the conductor C8 facing the large diameter part and the lower part of the conductor CL facing the large diameter part, that is, the outer periphery parts of the conductor at the positions furthest apart from each other in the middle direction, are bent into a metal cap shape and connected. ing. Therefore, a notch 2 is formed between the conductor C8 and the connecting conductor CtL, and a notch 2 is formed between the conductor C8 and the connecting conductor CJ.

Now, how to divide the single-turn conductor into a predetermined circumferential angle partial conductor and a remaining circumferential angle partial conductor will be described below.

Since a predetermined current flows through the single-turn conductor, the magnetic flux generated from the conductor by the current is uniform in all parts. However, since the widths of the conductors C8 and CL are set according to the length of the heated portion of each parallel part of the workpiece W, for example, one turn of the conductor is divided into two (13) and the workpiece W and the conductor are stationary. If they are facing each other in the state, the magnetic flux density applied per unit area of the heated surface is determined by the inside of the conductor; the wider the conductor, the thinner the conductor, and the narrower the conductor, the thicker the magnetic flux density. However, since the work WFi is kept rotating,
If the amount of magnetic flux applied per unit area of each parallel part during one rotation is the same, the heating rate will be the same,
Conversely, if n is made different, the rate of temperature rise will be different. In the present invention, as described above, the magnetic fluxes generated from each of the conductors C8 and CL are separated, so they can be considered as independent end-face heating coils. Workpiece W being rotated
The winding circumference of the single-turn conductor may be divided into a predetermined circumferential angle partial conductor and a remaining circumferential angle partial conductor such that the amount of magnetic flux applied per unit area of the heated portion is different.

Therefore, when designing the coil, it is only necessary to give empirical consideration to the escape of the heated portion due to leakage magnetic flux in the direction of the end face.

(14) In addition, in conventional heating coils, the gap between the parallel portion that increases the heating temperature and the inner circumferential wall of the heating coil is set as an appropriate gap, and the gap between the parallel portion that lowers the heating temperature and the inner circumferential wall of the heating coil is made wider than the appropriate gap. However, it is extremely difficult to determine how wide the heating setting should be, and there was no other way than to make a prediction based on experience and past data.

However, in the present invention, the gap between each of the parallel parts and the conductor is constant, and the heating temperature can be varied depending on the winding angle of the conductor, so it is extremely easy to do so. Note that it is of course possible to perform adjustment using both the gap and the circumferential angle.

When a rotating workpiece W is heated using the heating coil C of the present invention having the above configuration, the heated portion of the small diameter portion S is heated by the conductor C.
The magnetic flux σS generated from S and the magnetic flux Ωt generated from the conductor CL are applied to the large-diameter heated part at predetermined different densities per unit area, and in the length direction of each heated part. Since the power is applied evenly, both parts to be heated are heated to predetermined different temperatures within a predetermined time.

As a result of the above heating, the stepped portion of each conductor sandwiched between the opposing heated parts becomes a temperature rise source mainly due to the heat flowing in from both heated parts by thermal conduction, and leakage from the conductor C3-CL. The temperature is increased by supplementing heat by a small amount of heat generated by the magnetic flux. In this way, the parallel portions each having a predetermined length, including the stepped portions, are heated in one shot to a predetermined temperature with a difference in temperature, and this heating results in a tempering treatment with a difference in hardness.

The inventor conducted the following experiment to confirm the effects of the present invention.

Experimental example (1) Specimen: Stepped member...Material SCM415H equivalent material ○Small diameter equivalent diameter...30mm σ Length...30 Threaded over 20mm from the stepped part ○Large diameter part Diameter...・44 length ρ Length: 45 mm from the long stepped part is splined.The specimen has been carburized and quenched over its entire length and has a surface hardness of HRC 57 to 60. (2) Experimental case; Harden the entire length of the small diameter part from the thread crest to a depth of 0.4 tm 'j to a hardness of HRC 40 to 36, and harden the large diameter part from the stepped part to 1011III+ to a depth of 0.4 tm from the spline crest. Each is tempered to HRC45.

(3) Experimental method: A heating coil having the shape shown in FIG. 2 was used. The dimensions of the heating coil and heating conditions were as follows.

Heating coil dimensions: Winding circumferential angle of small-diameter opposing conductor: 210° Winding circumferential angle of large-diameter opposing conductor: 150° However, square layer (17) based on the widthwise center of the connecting conductor. Conditions Power output: 8KW Frequency: 8KHz Power and heat time: 385ec (4) Experimental results: The hardness of the specimen after tempering was measured using a Vickers hardness meter, and the measured value was converted to Rockwell hardness HRC. It was written on the enlarged cross-sectional view shown in Figure 5.

From the above experimental results, both parallel parts are individually heated at the same time, and as a result, the small diameter part has a hardness of HRC 40 to 36.
The hardness of the large diameter part 10 is within the range of hardness HR.
It was confirmed that each part had been tempered to C45, and at the same time, it was clear that the resting part and shoulder of the stepped part were also tempered without insufficient heating or overheating, indicating that the present invention is extremely effective in uneven tempering near the stepped part. It has been proven to be effective.

As mentioned above, although the present invention is a single-turn heating coil, the magnetic flux is discontinuous and separated, as if two end-face heating coils (18) were used, and it acts independently on the heated portion of each parallel portion. By implementing the present invention, (1) conventionally, the inner circumferential wall with grooves and flanges was used to completely prevent overheating of shoulders and insufficient heating of corners at stepped portions; The difficulty in designing and manufacturing heating coils has been resolved. (2) Designing and manufacturing is extremely easy, just by calculating the circumferential angle, as in the case of end-face heating coils that heat the heated parts of both parallel parts. (3) At the same time, the parallel parts are heated at different temperatures,
In addition, each parallel part can be heated uniformly in the axial direction, making it extremely easy to achieve the desired uneven tempering. (4) Furthermore, there is no overheating or insufficient heating of the stepped parts, so uneven tempering does not occur. The technical, production, and even economic effects of this reduction are significant.

Furthermore, the technical idea of the present invention is to apply the same amount of magnetic flux per unit area to each heated part of both parallel parts during rotation, which is completely contrary to the uneven tempering near the stepped part of a stepped member which is the object of the present application. By dividing the single-turn conductor and making it face each heated part, a predetermined length of each parallel part including the stepped part can be uniformly heated without causing overheating or insufficient heating of the stepped part. It should be added that this is also possible, and that this allows not only uniform tempering but also uniform quenching.

[Brief explanation of the drawing]

Fig. 1(a) is a front cross-sectional view of a stepped member to be subjected to uneven tempering of the present invention, Fig. 1(b) is a partially cutaway front view of the i'j subordinate heating coil, Fig. 1(c) is a cross-sectional front view for explaining all the problems that exist in conventional heating coils, and Fig. 2 (a)
) to (d) are respectively a plan view, a perspective view, a sectional view taken along line II in (a), and ■-■ of the heating coil according to the embodiment of the present invention.
3(a) to Cc) are respectively a perspective view, a cross-sectional front view, and a magnetic flux line diagram of a heating coil of a comparative example, and FIG. 4 is a part of a heating coil of another example of the present invention. Sectional front view, 5th
The figure is a hardness distribution diagram showing the results of a tempering experiment using the heating coil of the present invention. W...Stepped member, S, L...Parallel portion, C...Heating coil, C8, CL...Predetermined circumferential angle partial conductor and remaining circumferential angle partial conductor, CJ...Connecting conductor. Patent applicant Koshuha Netsuren Co., Ltd. Representative Patent attorney Fu Kobayashi (21) Figure 2 (C) Q (J Figure 3 (a) Figure 2 (d) Figure 3 (b) Figure 3 (c) ) Fig. 4 W Fig. 5 Box Furano Mound Size---0.4mm ---------0
, 2mm HRC 1 B-40 40-40 10 mm 38-39 39-39 39-40 40-38 38-38 38-38 ” mm36-37 + 36-37 36-36 37 -37 36-36 36-36 38-38 10 mm 37 3 s +0-'394545 38-38 37-38 43-43

Claims (1)

[Claims] 1.) Simultaneously tempering with a temperature difference between a predetermined length portion of one parallel portion and a predetermined length portion of the other parallel portion connected to the step portion of the stepped member. When applying
In a single-turn heating coil, the predetermined circumferential angle portion of the conductor faces one parallel portion, and the remaining circumferential angle portion faces the other parallel portion, and the magnetic flux generated from the predetermined circumferential angle portion conductor and the remaining circumferential angle portion conductor By making the magnetic flux generated from the magnetic flux discontinuous and separate for all members, the temperature rises individually in each circumferential angle portion conductor facing a predetermined length portion of both parallel parts of the stepped member that rotates. 1. A method for unevenly returning a step part of a stepped member, characterized in that the step part is heated at a high speed, and the step part is heated as a main temperature increase source from the parallel part heated by heat conduction. 2.) Rotation in which the magnetic fluxes generated from the conductors at each of the circumferential angles of the conductor at the predetermined circumferential angle portion and the conductor at the remaining circumferential angle portion are opposed, heating the predetermined length portions of each parallel portion at different heating rates. The steps of the stepped member according to claim 1 are set in accordance with the inside of each conductor so that different amounts of magnetic flux per unit area are applied to each predetermined length portion of the step member. Non-uniform tempering method. 3.) In a single-turn heating coil that tempers the step part of the stepped member that rotates on its axis and the predetermined length portions of both parallel parts connected thereto, the single-turn conductor in the single-turn heating coil The predetermined circumferential angle portion is divided so that it corresponds to one parallel portion, and the remaining circumferential angle portion corresponds to the other parallel portion, respectively, and is formed into a conductor according to a predetermined length of each of both parallel portions, and the predetermined circumferential angle portion is The end portions of the conductor and the remaining circumferential angle portion conductor are configured into a connected closed circuit by connecting conductors that connect the outer circumferential portions of the conductors at the positions furthest apart from each other in the middle direction of each conductor, and both parallel portions are formed at the step boundary. 1. A heating coil for uneven tempering near a stepped portion of a stepped member, characterized in that a desired different amount of magnetic flux can be applied per unit area to each predetermined length portion of the stepped member.