JP2005344192A - Method for adjusting condition of heat treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for adjusting the condition of a heat treatment by which a desired hardness layer can continuously and stably be formed by minimizing the variations of hardness depth, hardness width, hardening/tempered hardness in the hardening layer caused by the wearing of a chip member for laying a coil. <P>SOLUTION: This method is performed by passing through the following steps, that is; a step for presetting the plurality of conditions of the heat treatment corresponding to shot number N of the heat treatment or gap S between the heating part and the high frequency induction heating coil; a step for detecting the shot number N of the heat treatment or the gap S: a step for selecting the condition of the heat treatment corresponding to the detected value in the plurality of conditions of the heat treatment based on the detected value; and a step for performing the heat treatment based on the selected condition of the heat treatment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a semi-open saddle type high frequency induction heating coil is placed on a pin portion or a journal portion of a crankshaft of an engine, for example, via a coil placement tip member, with a predetermined gap, and induction hardening is performed. -It is related with the method for adjusting heat processing conditions suitably in the heat processing operation to temper.

  For example, a cylindrical outer peripheral surface of an engine crankshaft pin portion or journal portion is subjected to high-frequency induction heating to a required temperature by a high-frequency induction high-frequency induction heating coil and rapidly cooled to cause a desired quenching depth and quenching. A hardened layer having a penetration width and a quenching hardness is formed. In this case, a semi-open saddle type coil is generally used as the high-frequency induction heating coil, and this high-frequency induction heating coil is placed close to the cylindrical outer peripheral surface of the pin portion or journal portion which is the heated portion with a slight gap therebetween. It is arranged to perform heat treatment work (high frequency induction heating).

  FIG. 1 shows a high-frequency induction heating apparatus 1 used for this kind of heat treatment operation. The apparatus 1 has a pair of side plates 2a and 2b facing each other in a direction orthogonal to the paper surface of FIG. 1, and a semi-open saddle type high frequency induction heating coil 3 and a pair of side plates 2a and 2b, for example, Three ceramic or cemented carbide coil mounting chip members 4a, 4b and 4c are fixedly held. Thus, during the heat treatment of the pin portion 5 (or journal portion), the coil mounting chip members 4a, 4b, 4c are brought into contact with the upper portion of the cylindrical outer peripheral surface 5a of the pin portion 5 as shown in FIG. The open saddle type high frequency induction heating coil 3 is disposed close to the cylindrical outer peripheral surface 5a of the pin portion 5 with a gap S therebetween, and the high frequency induction heating coil 3 includes three coil mounting chip members 4a and 4b. , 4c is placed on the pin portion 5. Under this state, the high frequency induction heating coil 3 is moved following the pin portion 5 as the crankshaft is driven to rotate about its axis, and is connected to the transformer side (not shown). The high-frequency current is supplied to the high-frequency induction heating coil 3 through the power supply lead conductors 6a and 6b, and the pin portion 5 is accordingly heated by high-frequency induction. The shape of the pin portion 5 to be heat-treated is, for example, as shown in FIG. 2, and the pin portion 5 has a quenching depth, a quenching width and a quenching / quenching as shown by cross-hatching in FIG. A tempered hardened layer 7 (flat hardened layer) is formed. On the other hand, the same applies to the journal portion of the crankshaft.

  In the initial stage of the heat treatment operation (starting time of use of the high-frequency induction heating device 1, that is, a time when the coil mounting chip members 4a, 4b, and 4c are not yet worn), the power supplied to the high-frequency induction heating coil 3 and the like The quenching and tempering conditions are set so that the desired quench hardened layer 7 is formed correctly (in a regular shape and a regular dimension). However, the high-frequency induction heating apparatus 1 performs a quenching / tempering operation continuously for at least about 30,000 shots (the tempering process is performed after the quenching process). The coil mounting chip members 4a, 4b, and 4c are gradually worn as they overlap. Specifically, the cylindrical outer peripheral surface 5a of the pin portion 5 (or the journal portion rotated around the axis) that rotates (revolves) and rotates (revolves) and the tips of the support members 4a, 4b, and 4c. The tip portions of the support members 4a, 4b, and 4c are gradually worn due to the contact with each other. In particular, since a considerably large load is applied to the tip end of 4b (see FIG. 1) arranged in the vertical direction, the amount of wear is considerably large. Therefore, the gap S between the high-frequency induction heating coil 3 and the cylindrical outer peripheral surface 5a of the pin portion 5 is gradually narrowed due to the wear of 4b. When the gap S is narrowed, the heating efficiency of the high-frequency induction heating coil 3 is improved. If the initial heat treatment conditions are maintained, the quenching depth is deepened, the quenching width is widened, and the high-frequency induction heating temperature is also increased. As a result, the tempering hardness is lowered.

  6, FIG. 7, and FIG. 8 are graphs showing the relationship between the number N of heat treatment shots or gap S and the quenching depth, quenching width, quenching / tempering hardness. In the figure, the horizontal axis indicates a gap (S), and the vertical axis indicates the quenching depth (see FIG. 6), quenching width (see FIG. 7), quenching / tempering hardness (FIG. 8 (a) and FIG. 8B) is shown. As shown in the figure, the quenching depth, the quenching width, the quenching / tempering hardness greatly change due to the change in the gap S, and it is sufficiently guessed that if this is left as it is, it exceeds the standard value.

  As described above, if the heat treatment conditions are left at the initial stage due to wear of 4a, 4b, and 4c, the quenching depth, the quenching width, the quenching / tempering hardness change, and a desired quality of quenching is achieved. The hardened layer 7 cannot be obtained, and in some cases, a problem of non-standard defective products arises. Further, when the quenching depth is deepened and the quenching width is widened, the heat treatment distortion is increased, and flat quenching (quenching form in which the quenching hardened layer 7 is formed only on the cylindrical outer peripheral surface 5a of the pin portion 5). In the case of, burning cracks may occur around the oil hole 8 (see FIG. 2). Further, fillet R quenching (not only from the cylindrical outer peripheral surface 5a of the pin portion 5 but also from this cylindrical outer peripheral surface 5a to the corner between the cylindrical outer peripheral surface 5a and the fillet portion 9, that is, the fillet R portion 10) Even in the case of a quenching mode in which a hardened and hardened layer is formed in a continuous region), the oil hole 8 may be cracked or melted. Further, there is a possibility that the cracks may occur in the fillet portion 9. In order to eliminate this problem, conventionally, the quenching depth, quenching width and quenching / tempering hardness are controlled during the heat treatment operation, and when the predetermined management width is exceeded, quenching / quenching is performed. The return condition is adjusted, and when the wear of the coil mounting chip members 4a, 4b, 4c (especially the coil mounting chip member 4b arranged in the vertical direction) reaches a predetermined value, it is replaced with a new one. The method is actually used.

  However, it is quite troublesome to adjust the heat treatment conditions each time by measuring the quenching depth, the quenching width and the quenching / tempering hardness during the heat treatment operation, and misadjustment is likely to occur. In addition, the work of detecting the wear state of the coil mounting chip members 4a, 4b, 4c is quite troublesome, and there is a problem that the work efficiency is lowered as a whole.

  On the other hand, when the object (workpiece) to be heat-treated is determined, the amount of wear of the coil mounting tip members 4a, 4b, and 4c becomes as much as the number of heat treatment shots (number of shots) is increased. It is possible to determine whether or not the amount of wear of the coil mounting tip members 4a, 4b, and 4c and the time required for adjusting the heat treatment conditions can be predicted. For this reason, the number of heat treatment shots (the number of heat treatments) N and the gap S between the high frequency induction heating coil 3 and the cylindrical outer peripheral surface 5a of the pin portion 5 are detected. If the relationship is obtained in advance and the heat treatment conditions are automatically adjusted based on this relationship, the working efficiency can be improved far more than before, and high quality can be maintained.

  The present invention has been made on the basis of the knowledge as described above, and its purpose is to quench the hardening depth of the hardened hardened layer by the wear of the coil mounting chip member, the quenching width, the quenching / quenching. An object of the present invention is to provide a heat treatment condition adjusting method capable of reducing a change in rebound hardness as much as possible and continuously forming a desired hardened and hardened layer stably. That is, an object of the present invention is to set a plurality of heat treatment conditions determined in advance based on the heated portion based on the number N of heat treatment shots or the gap S between the high frequency induction heating coil and the heated portion. Select the optimum heat treatment condition (optimum heat treatment condition according to the amount of wear of the coil mounting tip member) from the inside so that the heat treatment work of quenching and tempering can be advanced while adjusting the heat treatment condition. Another object of the present invention is to provide a heat treatment condition adjusting method.

In order to achieve the above-mentioned object, in the present invention, a semi-open saddle type high frequency induction heating coil is placed on the heated portion by bringing a coil mounting tip member into contact with the cylindrical outer peripheral surface of the heated portion. It arrange | positions in the proximity position which left the clearance gap with respect to the cylindrical outer peripheral surface of this, and the said to-be-heated part is high frequency induction heating, rotating the said heating part or rotating and making the said high frequency induction heating coil track the said to-be-heated part In order to obtain a desired quenching depth, quenching depth, and quenching hardness or quenching and tempering hardness, when quenching or tempering heat treatment is performed by rapidly cooling the heated portion. A method of adjusting the heat treatment conditions,
(A) a step of predetermining a plurality of heat treatment conditions corresponding to the number of heat treatment shots or a gap between the heated portion and the high frequency induction heating coil;
(B) detecting the number of heat treatment shots or the gap during heat treatment;
(C) selecting a heat treatment condition corresponding to the detected value from the plurality of heat treatment conditions based on the detected value;
(D) performing a heat treatment based on the heat treatment conditions selected thereby;
To have.
In the present invention, the heated portion is a pin portion or a journal portion of a crankshaft.

  According to the first aspect of the present invention, a high-frequency induction heating coil is heated in a state where a semi-open saddle type high-frequency induction heating coil is placed on a heated portion via a coil mounting chip member with a gap. When performing heat treatment for quenching and tempering by induction induction heating while following the part, a plurality of heat treatments corresponding to the number of heat treatment shots or the gap between the heated part and the high frequency induction heating coil Predetermining conditions, detecting the number of heat treatment shots or the gap during heat treatment, and selecting a heat treatment condition corresponding to the detected value from the plurality of heat treatment conditions based on the detected value, thereby Since the heat treatment is performed based on the selected heat treatment conditions, according to the heat treatment condition adjustment method of the present invention, the number of heat treatment shots and gaps are detected, and the amount of wear of the coil mounting tip member The heat treatment operation can be carried out by selecting the optimum heat treatment condition for the current wear amount of the coil placement tip member from a plurality of predetermined heat treatment conditions. Even if the amount of wear of the chip member changes, it is possible to form a good hardened hardened layer as specified, always at the desired quenching depth, quenching depth, and quenching hardness or quenching and tempering hardness. You can get it. Therefore, according to the present invention, desired quenching can be achieved by minimizing changes in the quenching depth, quenching width, quenching / tempering hardness of the quench-hardened layer due to wear of the coil mounting chip member. The cured layer can be continuously formed stably. Further, periodic measurement of the coil mounting tip member is not necessary, and the working efficiency can be greatly improved.

  According to the second aspect of the present invention, since the heated portion is a pin portion or a journal portion of the crankshaft, according to the method of the present invention, the cylinder of the pin portion or the journal portion of the crankshaft. Even if the coil mounting tip member abutted on the outer peripheral surface of the coil is worn, the desired quenching depth, quenching depth, and quenching hardness or quenching and tempering hardness are always applied to the pin portion or journal portion. You can get it.

  Hereinafter, a heat treatment condition adjusting method according to an embodiment of the present invention will be described with reference to FIGS. Here, as a heat treatment object (work), for example, a pin portion of a crankshaft will be described as an example. In the following description, the same reference numerals as those used in the above description and FIGS. 1 and 2 are used.

  When quenching and tempering the pin portion 5 of the crankshaft, it is found from experience that it is not necessary to replace the coil mounting chip members 4a, 4b, and 4c up to about 30,000 as the number N of heat treatment shots. As is recognized, it is necessary to adjust the heat treatment conditions a plurality of times until at least the number of shots reaches 30,000. Table 1 below shows an example of the relationship between the number N of heat treatment shots or the gap S between the high frequency induction heating coil and the cylindrical outer peripheral surface 5a of the pin portion 5 and a plurality of predetermined heat treatment conditions. It is a thing.

  That is, when the number N of heat treatment shots is 1 to 6,000 (the gap S is 1.3 mm to 1.1 mm), the heat treatment is performed under the heat treatment condition 1. Next, when the heat treatment shot number N is 6,000 to 12,000 (the gap S is 1.1 mm to 0.9 mm), the heat treatment condition 2 is obtained, and the heat treatment shot number N is 12,000 to 18,000. (If the gap S is 0.9 mm to 0.7 mm), the heat treatment condition is 3, and the number N of heat treatment shots is 18,000 to 24,000 (the gap S is 0.7 mm to 0.5 mm). In this case, the heat treatment condition 4 is set, and when the heat treatment shot number N is 24,000 to 30,000 (the gap S is 0.5 mm to 0.3 mm), the heat treatment condition 5 is set. The heat treatment shot number N and the gap S can be automatically and accurately detected using a counter, a distance meter or the like even during the heat treatment operation, so that the number of heat treatment shots is based on the detected value. N or gap S (and hence the wear amount of the coil mounting tip member) is obtained, and actual heat treatment is performed according to the number N of heat treatment shots or gap S (and thus wear amount) from a plurality of predetermined heat treatment conditions. The optimum heat treatment conditions at the time of work are selected and heat treatment for quenching and tempering is performed.

  3, 4, and 5 show changes in quenching depth, quenching width, quenching / tempering hardness (predetermined heat treatment conditions) by the heat treatment condition adjusting method according to one embodiment of the present invention. Is shown. FIG. 3 shows the heat treatment conditions 1 to 5 shown in Table 1 above and the quenching depth is shown on the vertical axis. In FIG. 4, the horizontal axis represents the heat treatment conditions 1 to 5 shown in Table 1 above, and the vertical axis represents the quenching width. FIG. 5A shows the heat treatment conditions 1 to 5 shown in Table 1 on the horizontal axis and the quenching hardness on the vertical axis. FIG. 5B shows the heat treatment conditions on the horizontal axis. The heat treatment conditions 1 to 5 shown in Table 1 are taken, and the ordinate shows the tempering hardness.

  As shown in FIG. 3, even if the number of heat treatment shots N or the gap S changes, the adjustment from heat treatment condition 1 to heat treatment condition 5 is performed sequentially (as appropriate) correspondingly, so that each time quenching is performed. It can be seen that the depth is returned to a state close to the initial state and hardly changes. 4 and 5 (a) and 5 (b) show that the quenching width and the quenching / tempering hardness hardly change.

  The heat treatment conditions 1 to 5 are naturally different depending on the kind and material of the heat treatment object (work), and the number of adjustments is not limited to the above, but is experimental according to the work. , You can decide empirically.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications and changes can be made based on the technical idea of the present invention. For example, the number N of heat treatment shots that define the heat treatment conditions 1 to 5 is not limited to the numerical values described in Table 1 above, but the types of the pin portion 5 and the coil mounting chip members 4a, 4b, and 4c. It can be set as appropriate. In the above-described embodiment, the case where the pin portion 5 of the crankshaft is heat-treated has been described. However, the crankshaft journal portion and various heat treatment objects other than the crankshaft pin portion 5 or the journal portion are also described. It goes without saying that the heat treatment condition adjusting method can be applied to the present invention.

It is a side view which shows the high frequency induction heating apparatus used in enforcing the heat treatment condition adjustment method which concerns on one Embodiment of this invention. It is sectional drawing which shows the shape of the pin part of the crankshaft induction-hardened, and the hardening hardening layer formed in the cylindrical outer peripheral surface of the pin part. It is a graph which shows the relationship between the quenching depth in the heat processing condition method of this invention, and heat processing conditions. It is a graph which shows the relationship between the quenching width in the heat treatment condition method of this invention, and heat treatment conditions. FIG. 5A shows the relationship between quenching / tempering hardness and heat treatment conditions in the heat treatment condition method of the present invention. FIG. 5A is a graph showing the relationship between heat treatment conditions and quenching hardness, and FIG. ) Is a graph showing the relationship between heat treatment conditions and tempering hardness. It is a graph which shows the relationship between the quenching depth and the number of heat treatment shots, or a clearance gap in the conventional heat treatment condition adjustment method. It is a graph which shows the relationship between the hardening width | variety in the conventional heat processing condition adjustment method, the number of heat processing shots, or a clearance gap. FIG. 8A shows the relationship between quenching / tempering hardness and the number of heat treatment shots or gaps in the conventional heat treatment condition adjusting method, and FIG. 8A is a graph showing the relationship between heat treatment conditions and quenching hardness, FIG. (B) is a graph which shows the relationship between heat processing conditions and tempering hardness.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High frequency induction heating apparatus 2a, 2b Side plate 3 Semi-open saddle type high frequency induction heating coil 4a, 4b, 4c Coil mounting chip member 5 Pin portion 5a Cylindrical outer peripheral surface N Number of heat treatment shots S Gap

Claims (2)

A semi-open saddle type high frequency induction heating coil is brought close to the cylindrical outer peripheral surface of the heated portion with a gap by contacting a coil mounting tip member on the cylindrical outer peripheral surface of the heated portion. The heating unit is placed at a position, and the heating unit is rotated or rotated to cause the high-frequency induction heating coil to follow the heated part, so that the heated part is subjected to high-frequency induction heating, and then the heated part is rapidly cooled. A method of adjusting heat treatment conditions to obtain a desired quenching depth, quenching depth, and quenching hardness or quenching and tempering hardness when performing quenching or tempering heat treatment,
(A) a step of predetermining a plurality of heat treatment conditions corresponding to the number of heat treatment shots or a gap between the heated portion and the high frequency induction heating coil;
(B) detecting the number of heat treatment shots or the gap during heat treatment;
(C) selecting a heat treatment condition corresponding to the detected value from the plurality of heat treatment conditions based on the detected value;
(D) performing a heat treatment based on the heat treatment conditions selected thereby;
A method for adjusting a heat treatment condition, comprising:   2. The heat treatment condition adjusting method according to claim 1, wherein the heated portion is a pin portion or a journal portion of a crankshaft.

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