JPH0653897B2 - How to quench a crank shaft - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improved quenching method suitable for quenching a crankshaft, particularly a journal portion.

(Prior Art) Induction hardening of the journal portion of the crankshaft is carried out by using JP-B-56-48764 and JP-A-59-3736.
A semi-circular high-frequency heating coil such as No. 2 is loosely fitted in the journal from above and below, or from the left and right, and a high-frequency current is passed through the high-frequency heating coil to heat the surface of the journal, and after heating, it is built into the high-frequency coil. Cooling water is jetted from the cooling water jacket to the heating part to cool it and quench it.

(Problems to be Solved by the Invention) In the above-mentioned conventional techniques, hardening is performed around the shaft portion of the journal portion to form a hardened layer having a predetermined depth to improve strength and wear resistance. At both ends in the axial direction of
Part, that is, a quench hardened layer is formed on the surface of the fillet,
The fatigue strength of this part is improved.

By the way, the thickness of the fillet part is thick in the continuous part with the pin part, but the thickness of the part on the opposite side is extremely thin,
Even the thick side is thinner than the pin part. Therefore, at the time of heating for quenching, the thin portion of the fillet portion is overheated because the heat mass is small, and as a result, the cooling rate of the thin portion is high at the time of cooling and the fillet portion and the shaft are overheated. There is a possibility that quenching cracks may occur due to an extreme difference in cooling rate between the parts.

Therefore, in order to deal with the above, as in Japanese Patent Publication No. 61-887 and Japanese Patent Laid-Open No. 61-64819, induced current, voltage, shape of heating coil, clearance between work and coil, moving speed of coil, heating temperature, cooling speed. Although it is the current situation that induction hardening is performed by setting induction hardening conditions such as, it is difficult in practice to adjust and control the above conditions in the production process. Even if it can prevent quenching cracks, it is unstable in quality.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a crankshaft journal portion,
This is to prevent quench cracking of the thin portion of the fillet portion while satisfying the quench hardening characteristics of each fillet portion, and to obtain a crankshaft of excellent quality with stable quality.

(Means for Solving Problems) A means for solving the above problems is to make a high frequency heating mechanism face the outer periphery of the journal portion of the crankshaft, and rotate the crankshaft about the central axis to rotate the journal portion. In a quenching method for a crankshaft, which comprises heating and quenching, the high-frequency heating mechanism has a narrow axial distance from the wall of the fillet portion and a predetermined radial distance from the shaft portion of the journal portion. With the heating part of the fillet part that heats the shaft part of the fillet part and the journal part with a wide axial distance from the fillet part and the axial part of the journal part is located at a predetermined radial distance from the shaft part of the journal part. And a flat part heating part that heats the periphery of the part, and detects the angular position of the journal part as the crankshaft rotates, This is to control so that the output of the high-frequency heating mechanism is lowered at the angle at which the let portion heating portion faces the thin portion of the fillet portion.

(Operation of the Means) According to the above means, the high-frequency heating coil is provided with a fillet heating portion near the fillet thin portion on the journal portion in contrast to the approximately 1/4 circle portion, and the heating portion is provided in the thin portion. The output is reduced only when the crankshaft rotates to prevent overheating of the thin part, the output is increased in other parts, and heating and quenching suitable for each part around the crankshaft journal can be performed. Since the rotation angle of the shaft is detected and the output of the high-frequency heating device is controlled, the control can be performed accurately, highly accurately, and easily.

(Embodiment) Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a side view for schematically explaining a quenching method according to the present invention. (1) shows a crankshaft, and the crankshaft (1) is a journal (101), (102), (which forms a rotation axis. 103),
(104), (105) and the pin part (106), (107), (108), (1
09) and the embodiment shows one for four cylinders.
The journal section in which the present invention is implemented is (102) and (104)
, The journal part shaft parts (102a), (104a) are formed with fillet parts (102b), (102c), (104b), (104c) at both ends in the axial direction, and the fillet part is connected to the bin part at one end in the axial direction. The continuous rising portions (102d), (104d) are formed thick, but the portions on the side opposite to the rising portions (102d), (104d) are thin portions (102e),
(104e), and, the thin parts (102e), (104e) are the shaft parts (102a),
Angles in the circumferential direction at both axial ends of (104a), 9 in the embodiment
The phase is shifted by 0 °.

Journal parts (102), (10) of the above crankshaft (1)
4) Place the high frequency heating mechanism (2) around the coil (1/2)
The heating mechanism (2) is connected to a power source (not shown) via a control device (3), and the control device (3) detects a change in the rotation angle of the journal axis of the crankshaft. The heating mechanism is controlled by the detection signal of the phase detector (4)
Control the output of (2). In the embodiment, the heating mechanism (2) is of a type having a cooling jacket (201). The heating mechanism (2) is of a gate type and has nozzles (202) for jetting a cooling medium on the opposite surfaces of the lower end, and a coil (210) inside. Prepare On the other hand, the heating mechanism (2) is faced from above so as to surround a half circumference of the journal portion, and the fillet portion cooling mechanism (5) is faced below to cool the fillet portion at the time of heating.

The details of the heating coil (210) are as shown in FIGS. 3 and 4, and are in a front (back) view (viewed from the axial direction of the journal portion).
It has a semi-circular shape and is equipped with two terminal portions (211) and (212) that stand in parallel with one end side in the axial direction of the journal portion, for example, if it is the front side, close to the center of it and stand upright. Symmetrically extending from the front part (213), (214) of approximately 1/4 circular shape, and these front parts (213), (214) are spaced apart and fused to the axial circumference of the journal part. A part (2) that forms a circular part (215) and is parallel to the left and right journal parts from the lower ends of the front parts (213), (214)
16) and (217) are integrally extended, and a semi-circular rear portion (218) that is opposed to the front portion in the axial direction (front-back direction) is separated from the rear ends of the parallel portions (216) and (217). Unlike the front part, the rear part (218) is continuous and integrally, and the one terminal part (211) to the other terminal part (212) are continuously integrated. As shown in the bottom view of FIG. 4, the above coil (210) has a horizontally long rectangular frame shape in bottom view, and the horizontal parallel portions (216) and (217) are fitted between the fillet portions at both axial ends of the journal portion. It is set to length.

The above coil (210) is virtually divided into left and right symmetrical shapes with the axial direction of the journal shaft as the vertical direction in FIG.
As shown in FIG. 4, the front part (214) on the right side has a large width in the front-rear direction and projects forward so that the fillet part heating portion (A)
And the front part of the right flat part is referred to as the part (A). The adjacent left side portion (213) is lowered one step rearward from the right side portion (214) to form a flat portion heating portion (B). Thus, each of the parts (A) and (B) is semicircular, and therefore the front part (215) forming an arc of 180 ° is circumferentially divided into 90 °. Semicircle, therefore the rear part (218) provided to form an arc of 180 ° corresponds to the front part, and the 180 ° arc is virtually divided into right and left, that is, the front part (214) is for heating the fillet part. The rear half (218a) corresponding to the portion (A) is the flat portion heating portion (B), and the left half, that is, the front portion (213) is the rear half portion (B) corresponding to the flat portion heating portion (B). 218b) is a portion (A) for heating the fillet portion protruding rearward. That is, the coil (210) is constructed such that the left and right halves (a), (b) are axially out of phase.

Therefore, as shown in FIGS. 5 and 6, the shaft portion of the journal portion (104)
As shown in FIG. 5, the clearance (D) between the fillet portion heating portion (A) and the raising wall (104f) of the fillet portion (104b) is small when it is loosely fitted to the (104a). R part (104g)
R of the corner opposite to is small and maintains a distance (C) from the circumference of the shaft part (104a), while the part of the journal part (104) on the same side that is out of phase in the circumferential direction is flat. The portion (B) for the heating section has a larger spacing (E) from the rising wall (104f) than the above (D), and the R at the corner facing the R portion (104g) is r. And the distance (C) from the circumference of the shaft portion (104a) is the same as above.

Therefore, D <E, r <R, C = set to a constant relationship.

As described above, the coil (210) is rotated around the center axis of the crankshaft (1) as described above, and the coil (210)
It is fixed by loosely engaging the circumference of the shaft portion (104a) of (104). The journal part (104) rotates, while the fixed coil (210) is energized, so that the shaft part (104a) circumference of the journal part (104) and the fillet parts (104b), (104c) at both axial ends are connected. High frequency heating.

By the way, in the fillet portions (104b) and (104c), one of the axial ends is a thin portion (104e) near about 1/4 circumference, and the other of the axial ends is shifted in the circumferential direction from the above to substantially Thin section near 1/4 lap
(104e). Therefore, when the heating portions (A) and (A) approaching the fillet portion-a pair of front and rear are provided at both ends in the axial direction of the coil with a 90.degree. Phase shift, the coil is applied when approaching the thin portion (104e). To lower the output, and heat at a temperature lower than the shaft circumference. This can be seen in FIGS. 7 and 8 where the journal portion (104) of the crankshaft is viewed from the front and back, with FIG. 7 viewed from the front and FIG. 8 viewed from the rear, for example. Now, the journal part (104) is divided into four equal parts, and (I) is a fillet part thin-walled part, and the thin-walled part (I) is axially separated, and in the embodiment, the phase is shifted by 180 °. Coil (21
The left half (A) of the front part in FIG. 7) and the right half part (A) in FIG. 8 are the heating parts for the fillet part, and the journal part (104) on the front side of FIG. Crankshaft (1)
When rotating in the right direction in the figure, the back side in FIG. 8 rotates in the opposite left direction, and the center of the thin portions (I) and (I) with a phase difference of 180 ° in the axial direction is for heating the fillet portion. When the parts (A) and (A) are encountered, the output of the coil (210) is reduced. As described above, when heating the thin portions (I) and (I), heating is performed at a lower output than that of other portions, and the cooling mechanism (5) described above in the heating diagram is used to cool the cooling medium such as water. May be injected to suppress overheating. As a result, overheating of the thin-walled portions (I) and (I) is suppressed, and quenching can be performed without causing quenching cracks. On the other hand, the thin-walled portions (I) and (I) are the fillet heating portions (A) and (A). ) Is detected by the phase detector (4), and the other zones (II), (II
In I) and (IV), the output of the coil (210) is increased. As a result, the shaft portion (104a) and the fillet portions (104b) and (104c) are heated at high output except for the fillet portion thin portion (104e).
The fillet portions (104b) and (104c) have sufficient thickness in the portions other than the thin portion due to the standing portions (104d) and (104e), and the heat mass is large. ), (104c), it is heated sufficiently at high power, and after heating it is quenched by supplying cooling water.

FIG. 9 shows a quenching pattern of the journal portion (104) according to the method of the present invention described above. The thin portions (104e) and (104e) of the fillet portions (104b) and (104c) have a shallow quench hardening layer (H), Around the shaft portion (104a), the depth gradually increases in the opposite direction from the thin portion, and the portion of the fillet portion other than the thin portion becomes deeper. Therefore, according to such a quench hardening pattern, quench cracking can be prevented in the thin portion, and the R portion of the fillet portion on the opposite side has a deeper quenching depth, so that the fatigue strength is further improved.

The other journal section (102) is similarly quenched.

Next, concrete examples will be described. Using S48 high frequency (JIS) material as the material of the crankshaft, after hot forging into a crankshaft shape, the pin part and the journal part are machined to perform the high frequency heating described above. It was set in the mechanism and heated. During heating of the crankshaft, the crankshaft was rotated, and heating was performed while cooling the fillet thin portion of the journal portion with the cooling medium by the outer periphery. Then, at this time, the phase shift change at the time of rotation from the central axis of the crankshaft is detected by the transfer detector, and the thin portion of the fillet portion of the journal portion passes directly below the portion (A) for heating the fillet portion of the coil, and this portion The phase change is detected until it passes through, and the high frequency output is reduced only during this period. Next, when the thin portion has passed through the heating portion (A), it is returned to the original high frequency output. This series of operations is performed in one rotation, the journal part is heated to the quenching temperature, and when the quenching temperature is reached, the heating is stopped,
Quenching was performed by ejecting a cooling medium from a nozzle incorporated in the coil to cool it.

As a result of the above quenching treatment, cracks did not occur in the thin portion near the fillet portion of the journal portion of the crankshaft, and a crankshaft having a good quench hardened layer, quenching depth, and quenching hardness was obtained.

The conditions and results of the above quenching treatment are as follows.

(Effect of the Invention) As is apparent from the above, according to the present invention, when the angular position of each journal portion is detected by the rotation of the central axis of the crankshaft, the fillet heating portion of the coil of the high-frequency heating mechanism faces the thin portion. Since the high-frequency output is reduced and the heating part is controlled so that the output is restored to the original state when the heating part is out of the thin-walled part, the output is applied to the thin-walled part of the journal part fillet where quench cracks easily occur. Control is easy and accurate. Therefore, it is possible to generate the quench-hardened layer necessary for each part of the journal part such as the shaft part, the fillet part, and the thin part of the fillet part without quenching cracks in the thin part, and the wear resistance and fatigue required for the function as a whole as a whole. It is possible to obtain a crankshaft with excellent strength and quality, and it is possible to control the high-frequency output for heating by detecting the rotation angle of the central axis of the crankshaft, so output control is easy and accurate. The obtained crankshaft having excellent reliability and stable quality can be efficiently produced.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is an explanatory side view of quenching a crankshaft, FIG. 2 is a perspective view of a high frequency heating mechanism, FIG. 3 is a perspective view of a heating coil, and FIG. Fig. 5 is a bottom view, Fig. 5 and Fig. 6 are explanatory sectional views showing the relationship between the heating portion of the fillet portion of the coil and the heating portion of the flat portion of the coil, and Figs. 7 and 8 are the heating portion of the fillet portion and the journal. Fig. 9 is an explanatory view showing the relationship between the fillet portion and the thin portion of the portion, and Fig. 9 is an explanatory view of the quenching pattern by the method according to the present invention. In the drawing, (1) is a crankshaft, (102) and (104) are journal parts, (102a) and (104a) are shaft parts, (102b), (102c) and (104
b) and (104c) are fillet parts, (102e) and (104e) are thin wall parts,
(2) is a high frequency heating mechanism, (210) is a heating coil, (A)
Is a fillet heating unit, (B) is a flat heating unit,
(4) is a phase detector.

Claims (2)

[Claims] 1. A quenching method for a crankshaft, wherein a high frequency heating mechanism is exposed to the outer periphery of the journal portion of the crankshaft, and the journal portion is heated and hardened while rotating the crankshaft about a central axis. The high-frequency heating mechanism has a narrow axial distance from the raising wall of the fillet portion and a predetermined distance in the radial direction from the shaft portion of the journal portion to heat the fillet portion and the journal portion around the shaft portion. And a flat portion heating portion that mainly heats around the shaft portion of the journal portion by widening the distance in the axial direction from the fillet portion and facing the shaft portion of the journal portion at a predetermined distance in the radial direction. The angular position of the journal part is detected as it rotates, and high frequency is applied at the angle at which the fillet heating part faces the thin part of the fillet part. Hardening method of a crank shaft, characterized in that so as to control so as to lower the output of the thermal mechanism. 2. The method of quenching a crankshaft according to claim 1, wherein the thin portion of the fillet portion of the journal portion is cooled during heating at the low output.