JP4179009B2 - Crankshaft manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing method of the crankshaft that make up the engine of an automobile or the like.
[0002]
[Prior art]
In the prior art, the crankshaft for high output engines, after the journal and the shaft portion and a crank pin, fillet portions are junctions of such shaft portion and the crank web quenching process to (R portion), the fillet Some parts were rolled to obtain bending strength and bending fatigue strength. Such a crankshaft is described in, for example, Japanese Patent Laid-Open No. 2000-337345.
[0003]
Japanese Patent Publication No. 6-45826 discloses a technique in which the entire surface of the crankshaft is subjected to surface quenching by nitriding or carburizing, and then an annular corner portion (fillet portion) is locally quenched by a laser or a high frequency. A heat treatment method for increasing the fatigue strength of the shaft is described.
[0004]
[Problems to be solved by the invention]
However, in the conventional crankshaft as described above, when roll processing is adopted in its manufacture, the R shape of the fillet portion differs depending on the engine type or the like, and it is necessary to prepare a dedicated roll for each. In addition, since the frequency of replacement of the consumable roll is relatively high, there is a problem that the equipment cost is increased. Further, when roll processing is performed, the crankshaft may be bent. For this reason, there is a problem that a process for correcting the bending must be added, and a part of the compressive residual stress applied by the roll processing is released by the correction.
[0005]
Furthermore, when performing local quenching on the fillet part after performing surface quenching on the entire surface, the problem is that lot production is unavoidable due to two processes, and the production lead time becomes longer and productivity decreases. In addition, since the entire surface is hardened, even parts that are not functionally necessary are cured, and the workability is lowered in the subsequent finishing process, and the tool life is reduced and the machining time is increased. There was a problem.
[0006]
OBJECT OF THE INVENTION
The present invention has been made in view of the above-described conventional situation, and can reduce the number of manufacturing processes and equipment costs, and ensure bending strength and wear resistance only in necessary parts. and its object is to provide a method of manufacturing a crankshaft bets that can be.
[0007]
[Means for Solving the Problems]
In the manufacturing method of the crankshaft according to the present invention, when the crankshaft is manufactured, the fillet portion which is a joint portion between the shaft portion which is a journal or a pin and the crank web is subjected to quenching with a high energy beam. In this case, a laser beam is used as a high-energy beam, a reflecting cylinder having a pair of condensing reflecting surfaces and an irradiating reflecting surface is used on the inside, and the laser beam is passed through the reflecting cylinder and is reflected by the pair of condensing reflecting surfaces. Is reflected by multiple reflection , and the fillet portion is irradiated so that the laser beam is incident on the S-polarized light by the reflection surface for irradiation.
[0008]
【The invention's effect】
According to the manufacturing method of the crankshaft bets according to the present invention, such as the fillet portion a joining portion between the shaft portion and the crank webs such a journal or crank pin, a portion flexural strength and wear resistance are required only In addition, it is possible to ensure predetermined characteristics, and since the other portions are not cured, the amount of bending can be extremely reduced as the total heat input decreases. This makes it possible to abolish the bending correction process, machining allowance setting, and rough polishing process, thereby reducing the number of manufacturing processes and significantly reducing the equipment cost and cost. it can. In addition, high energy beam processing equipment is more versatile than induction hardening and roll processing equipment, so it can easily cope with quenching of multiple types of crankshafts with different shapes depending on the engine type, etc. Improvements in availability and productivity can be realized.
Furthermore, in the manufacturing method of the crankshaft, the reflective tube, the laser beam by multiple reflections from irradiating the fillet so as to become S-polarized light incident as well as condensed, the laser absorption rate due to changes in illumination angle impact is reduced, since the laser beam good hardened layer even when the angle close to perpendicular to the irradiation angle with respect to the axis of the journal is obtained, particularly the miniaturization of the tip portion of the reflective tube, simplification of the apparatus structure and further Miniaturization can be realized.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, with reference to the drawings, an embodiment of a method for manufacturing a crankshaft bets according to the present invention.
[0010]
The crankshaft A shown in FIG. 1 includes a journal J on the axis and a crank pin P for connecting rods as shafts, and a crank web W, a counterweight C and a flange (or rear (or rear)) between these shafts. A flange (collar) F is provided, and a fillet portion (R portion) ft is provided between the shaft portion and the crank web W or the like as a joint portion for smoothly connecting both.
[0011]
The crankshaft A has a high energy beam such as a laser beam on the outer peripheral surface of each shaft portion (J, P) including the fillet portion ft and the outer peripheral surface of the flange F as a part requiring bending strength and wear resistance. Has been subjected to local quenching.
[0012]
As shown in FIG. 2, the quenching is performed by rotating the crankshaft A around the axis at a high speed, and by applying a high energy beam to the crankshaft A from a plurality of positions on the same rotation surface around the axis, that is, two places above and below different in the figure. While irradiating EB, each high energy beam EB is scanned in the axial direction of the crankshaft A. At this time, the high-energy beam EB has a heat amount that does not involve surface melting of the quenched portion. In addition, the high energy beam EB can be scanned in the axial direction by, for example, moving the irradiation unit parallel to the axis, but in order to correspond to the fillet part ft having an R shape, as shown in FIG. Further, the scanning is performed in the axial direction by changing the irradiation angle by rotating the irradiation unit.
[0013]
Thereby, the hardened layer B by quenching is obtained on the crankshaft A as shown in FIG. At this time, in the crankshaft manufacturing method, while rotating the crankshaft A at a high speed, the high energy beam EB is irradiated from two locations, scanned in the axial direction, and quenched with a heat amount that does not cause surface melting of the quenched portion. Therefore, for example, quenching is performed without causing surface melting as shown in FIG. Therefore, as a matter of course, the process of removing the melted portion is unnecessary, and this can improve productivity. In addition, according to the manufacturing method, a spiral or linear annealing layer G as shown in FIGS. 5A to 5D is not generated, and a uniform hardened layer as shown in FIG. B is obtained continuously.
[0014]
Here, in this manufacturing method, the local quenching is performed such that the amount of heat applied to the fillet portion ft is larger than the amount of heat applied to the shaft portion (J, P). Thereby, as for the hardened layer B, the depth D2 of the fillet part ft becomes larger than the depth D1 of the shaft part (J, P). This is because, for the shaft part, it is only necessary that the surface is functionally hard to ensure wear resistance and uniformity of processing during finishing processing, and to prevent dents, so that it does not require much depth. The hardened layer B is shallow. In addition, since the deformation amount tends to increase when the hardened layer B in the shaft portion is deepened, the hardened layer B in the shaft portion is made shallower.
[0015]
On the other hand, the fillet portion ft is hardened to apply compressive residual stress by utilizing the fact that volume expansion occurs when martensite is formed. Since the compressive residual stress is a stress in the direction opposite to the bending stress, it contributes to an improvement in wear resistance. And since intensity | strength works with the volume (depth and width) of hardening, the hardening layer B is made deep about the site | parts where bending strength etc. are requested | required like a fillet part ft.
[0016]
In order to change the depths D1 and D2 of the hardened layer B by changing the amount of heat applied to the shaft portion (J, P) and the fillet portion ft as described above, the amount of energy of the high energy beam to be applied can be increased or decreased. Specifically, the irradiation output of the high energy beam, the irradiation time, or the processing speed (rotation speed, scanning speed) is appropriately changed.
[0017]
As described above, according to the crankshaft A and the manufacturing method thereof, the shaft portion that is the journal J and the crankpin P, the fillet portion ft that is the joint portion between the shaft portion P and the crank web W, and the flange portion F are provided. Thus, a predetermined characteristic can be ensured in a portion where bending strength and wear resistance are required, and at this time, a stable hardened layer B is formed without generating surface melting or annealing layer G. In addition, the depths D1 and D2 of the hardened layer B can be changed according to the requirements of each part. Since the other portions are not cured, the amount of bending becomes extremely small as the total heat input becomes small, and the amount of deformation after finishing is also very small.
[0018]
Therefore, it is possible to abolish the conventional roll processing, the bending correction process, the machining allowance setting and the rough polishing process, and as described above, the process of removing the melted part is also unnecessary, thereby making the manufacturing process The number can be greatly reduced, and the equipment cost and cost can be greatly reduced. Further, by eliminating the bending correction process, it is possible to eliminate a problem that the compressive residual stress of the fillet portion ft is released, and to prevent a decrease in bending strength.
[0019]
In particular, the amount of heat applied to the fillet portion ft is larger than the amount of heat applied to the shaft portion (J, P), so that the cured layer B of the fillet portion ft is deeper than the depth D1 of the cured layer B of the shaft portion (J, P). If the depth D2 is increased, the residual stress due to the heat treatment is reduced for the shaft portions (J, P), and no bending occurs, and the workability is improved. On the other hand, the compressive residual stress remains and the strength of the fillet part ft is improved, and since it is a local part rather than a part extending in the longitudinal direction as in the shaft part (J, P), the amount of heat is small. There is no influence of the bending of the shaft due to the addition, and since it is not a part that supports the shaft like the journal J, machining is unnecessary. Therefore, no bending is caused by the high energy beam EB, the subsequent bending correction becomes unnecessary, and the workability is improved.
[0020]
Furthermore, the high energy beam processing apparatus is more versatile than the induction hardening or roll processing apparatus, and therefore it is extremely easy to cope with quenching of multiple types of crankshafts having different shapes depending on the engine type. As a result, the operating rate of the apparatus is increased and the productivity is increased.
[0021]
FIG. 6 shows an inclined surface shape for avoiding interference with the high energy beam EB on the counterweight C of the crankshaft A when scanning the crankshaft A while changing the irradiation angle of the high energy beam EB. It is a figure which shows the case where this relief shape Q is provided.
[0022]
Thus, if the relief shape Q is provided in the counterweight C, the high energy beam EB and the counterweight C do not interfere with each other, and in particular, the irradiation angle with respect to the fillet portion ft can be increased. As shown in 4 (a), by keeping the quenching end B1 away from the fillet ft as much as possible, the occurrence of cracks at the quenching interface B2 due to bending fatigue can be suppressed. Further, as the irradiation angle of the high energy beam EB increases, the degree of freedom of the quenching shape is also increased.
[0023]
(Example 1)
As a material to be processed, an S45C material having a diameter of 40 mm, 50 mm, or 84 mm and having a shaft portion and a fillet portion was used. A laser beam was used as the high-energy beam, and the spot size at the processing point was set to φ4.8 mm.
[0024]
For the shaft portion, the output of the laser beam is 1.5 to 2.0 kW, the rotational speed around the axis of the material to be processed is 330 rpm, and the scanning speed (feed speed) in the axial direction of the laser beam is 0.1 m / min. It was. The laser beam was scanned by changing the irradiation angle from −6.3 ° to 6.3 °, and the feed length was 22 mm, 23 mm, or 8.5 mm. For the fillet portion, the output of the laser beam was 0.7 to 1.5 kW, and the rotation speed around the axis of the material to be processed was 5 rpm, 6.3 rpm, or 8 rpm. The laser beam was scanned by changing the irradiation angle from −6.3 ° to 6.3 °.
[0025]
When the shaft portion and fillet portion of the material to be treated were quenched under the above conditions, the shaft portion had a surface hardness of about HRC 50 to 55, a hardened layer depth of 0.05 to 0.20 mm, and surface melting. There was no outbreak. In the fillet portion, the surface hardness was about HRC 50 to 55, the hardened layer depth was 0.5 to 0.7 mm, and no surface melting occurred. Further, the amount of bending before and after quenching was less than 0.2 mm, and the amount of deformation before and after finish polishing was less than 0.02 mm.
[0026]
As a result, it has been confirmed that the crankshaft manufacturing method can provide a crankshaft having a sufficiently small amount of bending as well as sufficient strength for necessary portions such as the shaft portion and the fillet portion.
[0027]
FIG. 7 is a view for explaining another embodiment of a crankshaft manufacturing method and a quenching apparatus according to the present invention. Note that the same components as those of the previous embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0028]
The illustrated quenching apparatus holds the crankshaft A so that the crankshaft A can rotate in a state where its axis is horizontal, and a high energy beam is applied to the fillet portion ft which is a joint portion between the journal J which is the shaft portion and the counterweight C. By irradiating the laser beam LB, the fillet portion ft is hardened. The quenching apparatus includes a laser oscillator 1 and a reflecting cylinder (callide scope) 2 through which the laser beam LB passes from a direction orthogonal to the axis of the journal J, that is, in a vertical direction in the illustrated example.
[0029]
The reflection cylinder 2 includes a holder portion 3 connected to the laser oscillator 1 and a reflection portion 4 extending from the holder portion 3 between the pair of counterweights C and C. The holder unit 3 incorporates a condensing concave lens 5 that condenses the laser beam LB oscillated by the laser oscillator 1. The reflecting section 4 has a pair of concentrating reflecting surfaces (mirror surfaces) 4A and 4A facing each other, and an irradiating reflecting surface (mirror surface) arranged 90 degrees different from the condensing reflecting surfaces 4A and 4A. 4B is provided.
[0030]
The pair of condensing reflecting surfaces 4A and 4A are provided so as to extend in the vertical direction of the reflecting portion 4, and are inclined so that the interval gradually decreases downward, and the laser beam LB is subjected to multiple reflection to condense. To do. The reflection surface for irradiation 4B is provided on the lower half of the reflection portion 4 and is inclined so as to narrow the in-cylinder space downward, so that the laser beam LB is directed toward the incident reflection surface with respect to the fillet portion ft. Thus, the light is reflected in the direction in which the plane of polarization is orthogonal.
[0031]
Here, FIG. 8 shows the relationship between the incident reflection surface of the laser beam LB and the polarization plane. FIG. 8A shows a case where the incident reflection surface F1 including the incident reflection path and the polarization plane F2 are the same plane when the workpiece W is irradiated with the laser beam LB, and this case is P-polarized light. . FIG. 8B shows a case where the incident reflection surface F1 and the polarization plane F2 are orthogonal to each other, and this case is S-polarized light.
[0032]
FIG. 9 is a graph showing the relationship between the incident angle of the laser beam LB and the laser absorptance. When the incident angle with respect to the irradiation surface is perpendicular to 0 degree, the incident angle is approximately 0 for P-polarized light. If it exceeds 15, the laser absorptivity gradually decreases. On the other hand, with S-polarized light, the laser absorption rate is substantially constant until the incident angle reaches about 70 degrees, and thereafter the laser absorption rate decreases.
[0033]
Therefore, in the quenching apparatus and the crankshaft manufacturing method using this apparatus, the S-polarized light that has a small influence on the laser absorption rate due to the variation in the irradiation angle is adopted, and the laser beam LB is passed through the reflecting tube 2 to provide a pair. The condensing reflecting surfaces 4A and 4A collect and condense the laser beam LB, and the irradiation reflecting surface 4B irradiates the fillet portion ft with S-polarized light.
[0034]
At this time, in the quenching apparatus and the crankshaft manufacturing method, it is assumed that the laser beam LB has a heat amount that does not involve the surface melting of the quenching site, and the crankshaft A is rotated around the axis line, so that the fillet portion ft The fillet portion ft is quenched by irradiating the entire circumference with the laser beam LB.
[0035]
As a result, as shown in FIG. 10, a substantially symmetrical hardened layer is obtained on the counterweight side (vertical surface side) and the journal side (horizontal surface side) in the fillet portion ft. A relatively uniform depth without melting.
[0036]
In addition, when the depth of a hardened layer is extremely non-uniform | heterogenous, surface melting generate | occur | produces in the part where the depth of a hardened layer is large, and desired hardened quality may not be obtained. Even when quenching is established in a range where surface melting does not occur, it is necessary to reduce the processing speed or set the laser output high.
[0037]
In contrast, in the quenching apparatus and the crankshaft manufacturing method, the depth of the quenching layer is made relatively uniform, and a quenching layer with a stable quality can be obtained without melting the surface. In addition, it is possible to process at a relatively low laser output or high speed, thereby shortening the processing time and switching to an inexpensive laser oscillator, reducing production costs and improving productivity. Can be realized.
[0038]
In the quenching apparatus and the crankshaft manufacturing method, since the S-polarized light of the laser beam LB is employed, the influence on the laser absorption rate due to the fluctuation of the irradiation angle is reduced. Even when the angle is close to the normal to the axis, a good hardened layer can be obtained as described above, and thus the size of the tip of the reflecting tube 2 can be particularly reduced. Further, in the quenching apparatus and the crankshaft manufacturing method, the reflecting cylinder 2 condenses the laser beam LB while performing multiple reflection on the reflecting surfaces 4A and 4B on the inner side thereof, so that the structure is simple and further. Miniaturization is possible.
[0039]
Thereby, in the quenching apparatus and the manufacturing method of the crankshaft, it is possible to easily cope with quenching to the fillet portion even for the crankshaft whose shaft portion is shortened for the purpose of reducing friction and reducing the size and weight. As a result, it can also contribute to the performance improvement of the engine using the crankshaft.
[0040]
In the above embodiment, the quenching to the fillet portion ft has been described. However, it is possible to quench the shaft portion with a high energy beam before and after the quenching, and in this case, FIG. It is possible to employ quenching to the shaft portion in the previous embodiment described with reference to FIG. 6, and the same effects as in the previous embodiment can be obtained. In addition, when quenching the fillet portion ft, it is possible to irradiate the laser beam LB from a plurality of positions on the same rotational surface around the axis, and in this case, the processing time can be further shortened. To gain.
[0041]
The quenching apparatus and the crankshaft manufacturing method according to the present invention are applied to the crankshaft, but can naturally be applied to other materials to be processed having similar fillets.
[0042]
(Example 2)
A direct diode laser (wavelength: 805 nm) manufactured by Nuvonyx was used for the laser beam, and a reflecting cylinder shown in FIG. 7 was used for the condensing optical system. The laser output is 2.0 to 3.0 kW at the processing point, the beam spot size at the processing point is 6 × 8 mm, the beam irradiation angle is 38 degrees with respect to the axis of the shaft, and the peripheral speed when the shaft is rotated Was set to 0.3 to 1.4 m / min.
[0043]
As the material to be processed, a crankshaft for an automobile engine made of S45C equivalent material is used, the distance between the tip of the reflecting cylinder and the shaft is 0.5 to 1.5 mm, and the distance between the side of the reflecting cylinder and the counterweight is The length of the reflecting part of the reflecting tube (symbol D in FIG. 7) was 115 m. The length of the shaft portion is 15 mm.
[0044]
When the fillet part (R part) was quenched under the above conditions, the quenching layer had a depth of about 0.7 mm at the R apex part, and a good quenching layer having a surface hardness of about HRc 55-60 ( (See FIG. 10).
[Brief description of the drawings]
FIG. 1 is a side view with an enlarged view illustrating a crankshaft.
FIG. 2 is a perspective view illustrating a state in which a high energy beam is irradiated on a shaft portion.
FIG. 3 is a side view illustrating a state in which a high energy beam is irradiated to a shaft portion and a fillet portion.
FIG. 4 is a cross-sectional view (a) illustrating a hardened layer formed by the manufacturing method according to the present invention, and a cross-sectional view (b) illustrating a state where surface melting has occurred.
FIG. 5 is a cross-sectional view (a) and a perspective view (b) showing a helical annealing layer, and a cross-sectional view (c) and a perspective view (d) illustrating a linear annealing layer.
FIG. 6 is a side view for explaining a case where a relief shape is provided in the counterweight of the crankshaft.
FIG. 7 is a side sectional view (a) and a front sectional view (b) for explaining a quenching apparatus.
FIG. 8A is a perspective view showing a case where the incident / reflecting surface of the laser beam and the polarization plane are the same plane, and FIG. 8B is a perspective view showing a case where the incident / reflecting surface of the laser beam and the polarization plane are orthogonal to each other. is there.
FIG. 9 is a graph showing a relationship between an incident angle of a laser beam and a laser absorptance for P-polarized light and S-polarized light.
FIG. 10 is a photograph showing a cross section of a fillet portion that has been quenched.
[Explanation of symbols]
A Crankshaft C Counterweight EB High energy beam F Flange ft Fillet part J Journal (shaft part)
LB laser beam (high energy beam)
P Crank pin (shaft)
Q Relief shape W Crank web 2 Reflecting cylinder 4A Condensing reflecting surface 4B Irradiating reflecting surface

Claims (10)

When manufacturing the crankshaft, the fillet part, which is the joint between the journal and pin shaft and the crank web, is hardened with a high energy beam, using a laser beam as the high energy beam. , a reflective tube having a radiation reflecting surface and a pair of condenser reflecting surface on the inside, through the laser beam to the reflecting tube, the laser beam while converging by multiple reflection by a pair of condensing reflecting surface, irradiated A method of manufacturing a crankshaft, comprising irradiating a fillet portion with a laser beam incident on an S-polarized light by a reflective surface for use .   The method of manufacturing a crankshaft according to claim 1, wherein the fillet portion is irradiated with a laser beam while rotating the crankshaft about an axis.   The method for manufacturing a crankshaft according to claim 1, wherein the shaft portion is quenched with a high energy beam before and after quenching the fillet portion.   The method for manufacturing a crankshaft according to claim 3, wherein the amount of heat applied to the fillet portion is larger than the amount of heat applied to the shaft portion.   The method of manufacturing a crankshaft according to any one of claims 1 to 4, wherein the quenching with a high energy beam is performed with a heat amount that does not cause surface melting of a quenching site.   The method for manufacturing a crankshaft according to any one of claims 3 to 5, wherein the crankshaft is rotated around an axis, and quenching is performed by scanning a high energy beam in the axial direction.   The method for manufacturing a crankshaft according to any one of claims 1 to 6, wherein the crankshaft is irradiated with a high energy beam from a plurality of positions on the same rotation surface around the axis.   The crankshaft manufacturing method according to any one of claims 1 to 7, wherein the crankshaft is scanned with a high energy beam while changing an irradiation angle in an axial direction.   9. The method of manufacturing a crankshaft according to claim 8, wherein the counterweight of the crankshaft is provided with a relief shape that avoids interference with a high energy beam. In the manufacture of crankshafts, this is a device that hardens the fillet, which is the joint between the journal and pin shaft and the crank web, with a high energy beam, and uses a laser beam as the high energy beam. And a reflecting tube for irradiating the fillet portion with the laser beam being incident on the S-polarized light by the reflecting surface for irradiating the laser beam with multiple reflection by the pair of reflecting surfaces. And quenching equipment.

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