JP2000001722A - Method for hardening inner diameter surface of outside drum in traction roller type speed change gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the imperfect hardening near the surface and the deformation of an outside drum and to reduce a cost for grinding and heat treatment by hardening the inner diameter surface of the outside drum with high energy beam in the state of inserting the outside drum into a die. SOLUTION: In the state of holding a first rotary shaft 2 of the outside drum 1 after cold-forging and grinding processes with a chuck 4 of a motor 3, the outer diameter surface of the outside drum 1 is inserted into a cavity 6 in the die 5 by extending the chuck 4 to restrict the whole outer diameter surface of the outside drum 1 in the die 5. Successively, the inner diameter surface of the outside drum 1 is irradiated with a laser beam from the upper opening part of the die 5 while rotating the outside drum 1 by driving the motor 3 to harden the whole inner diameter surface. During the beam irradiation, the thermal expansion of the outside drum 1 occurs, but since this thermal expansion is restricted with the die 5, the deformation of the outside drum 1 is corrected and the high circularity is secured. Further, since the heat capacity needed to harden with the beam is mode large by the die 5 and the cooling capacity is raised with the heat dispersion, the sufficient air-cooling effect is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for quenching the inner surface of an outer drum of a traction roller type transmission which is incorporated as a speed reducer or a speed increaser in various mechanical devices.

[0002]

2. Description of the Related Art As shown in FIGS. 5 and 6, a traction roller type transmission has an outer drum 1 integral with a first rotating shaft 2 and an intermediate roller 3 on an inner diameter surface of the outer drum 1. A second rotating shaft 4 that frictionally engages, and applies a preload between the second rotating shaft 4 and the intermediate roller 3 and between the intermediate roller 3 and the inner diameter surface of the outer drum 1; The rotation of the motor shaft is transmitted at a reduced or increased speed by frictional force via an oil film such as grease or grease. When the first rotating shaft 2 is used as an input shaft, the speed increasing rotation is transmitted to the second rotating shaft 4 to become a gearbox, and when the second rotating shaft 4 is used as the input shaft, the first rotating shaft 2 becomes the first rotating shaft. The decelerated rotation is transmitted to the rotating shaft 2 to function as a reduction gear.

[0003] As described above, the traction roller type transmission is a transmission system using a frictional force via an oil film, so that the noise generated even when rotating at high speed is smaller than that of a gear type transmission such as a planetary gear. Generally, it is incorporated in an output section of an electric motor and used as a speed reducer.

When the traction roller type transmission is driven, the inner surfaces of the second rotating shaft 4, the intermediate roller 3, and the outer drum 1 are pressed against each other at a contact stress of 1 to 2 GPa, and the rolling surface is subjected to surface pressure. A corresponding internal shear stress occurs. For this reason, in order to harden the rolling contact portion on the inner diameter surface of the outer drum 1, the present applicant has filed Japanese Patent Application No. Hei 9-26926.
As shown in the specification of 2373 (not disclosed), a technique in which a low-carbon alloy steel such as SCr420 is used as a material of the outer drum 1 and carburizing and quenching treatment is performed has been proposed.

However, the carburizing and quenching treatments have a large heat treatment deformation, so that the first rotary shaft 2 and the like integral with the outer drum 1 are deformed. Such measures must be taken, which increases the grinding cost. Furthermore, considering new equipment, carburizing equipment is very expensive, which hinders a reduction in the manufacturing cost of the outer drum, which requires a significant cost reduction because the traction roller type transmission is inexpensive.

Therefore, in order to eliminate such inconvenience, it is necessary to harden only the inner diameter surface (rolling contact portion) of the outer drum, so that inexpensive partial quenching may be considered. Examples of the partial quenching method include induction quenching or quenching with a high energy beam such as an electron beam, a CO ₂ laser, or a YAG laser.

In induction hardening, an induction coil is arranged in the vicinity of a part to be hardened, an eddy current is caused to flow through an alternating current, and the work is heated by hysteresis heat. After heating, the work is rapidly cooled by applying cooling water. It is often used to quench a relatively deep and wide area.

On the other hand, electron beam, CO ₂ laser, YAG
In quenching by a high energy beam such as a laser, a portion having a high energy density is irradiated to a portion to be hardened and heated by the beam energy. After heating, the material is air-cooled and quenched by diffusion of heat due to the heat capacity of the work. Since quenching by these high energy beams is rapid heating, narrow portions can be quenched shallowly.

[0009]

However, induction hardening hardens the outer drum 1 because it is difficult to obtain a shallow hardened layer and hardens thin portions.
It easily penetrates up to the outer diameter surface, and cracks easily occur, and heat treatment deformation becomes a problem, and even if it hardens, it is necessary to increase the grinding allowance to ensure roundness, and grinding costs increase, furthermore However, there is a disadvantage that the use of cooling water requires a cooling facility and deteriorates the environment.

On the other hand, quenching with a high energy beam represented by laser quenching or electron beam quenching is effective in this respect because it does not require cooling equipment and is effective in this respect. Because of its low heat capacity, the air cooling effect for quenching was insufficient, causing a problem that incomplete quenching occurred near the surface.

Also, since the meat is quenched into thin parts,
As in the case of induction hardening, heat treatment deformation becomes a problem,
Even if it is hardened, it is necessary to increase the grinding allowance in order to secure roundness, and the grinding cost is increased. Further, a deep hardened layer cannot be obtained with a high energy beam. May cause the cured layer to disappear.

As a conventional deformation correcting method, there is a press quench method, which is performed by heating the whole body to restrain and correct it in an austenite state, such as carburizing quenching or soot quenching, or restraining just above the MS point. However, it is not applicable as a method for correcting the above-mentioned partial quenching.

The present invention has been made in order to solve such inconvenience, and the invention of claim 1 prevents incomplete quenching near the surface when quenching the inner surface of the outer drum with a high energy beam. It is an object of the present invention to provide a method of hardening the inner surface of the outer drum of a traction roller type transmission, which can prevent deformation of the outer drum and reduce grinding cost and heat treatment cost.

Further, according to the second aspect of the present invention, when quenching of the inner surface of the outer drum is performed by induction hardening, it is possible to prevent quenching cracks and to prevent deformation of the outer drum to reduce grinding cost and heat treatment cost. It is an object of the present invention to provide a method of hardening the inner surface of an outer drum of a traction roller type transmission that can reduce the amount of reduction.

[0015]

According to a first aspect of the present invention, there is provided a method of quenching an inner surface of an outer drum of a traction roller type transmission, wherein the outer drum is integral with a first rotating shaft. A second rotating shaft that frictionally engages the inner surface of the outer drum via an intermediate roller, and the outer drum of a traction roller type transmission that transmits the rotation of the motor shaft at a reduced or increased speed via an oil film The method for quenching the inner diameter surface is characterized in that the outer drum is inserted into a mold, and in this state, the inner diameter surface of the outer drum is quenched using a high energy beam.

According to a second aspect of the present invention, there is provided a method of hardening the inner surface of the outer drum of the traction roller type transmission according to the first aspect, wherein the inner surface of the outer drum is hardened by induction hardening instead of the high energy beam. And

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of a quenching apparatus used for a method of quenching the inner surface of an outer drum of a traction roller type transmission according to an embodiment of the first aspect of the present invention.
FIG. 3 is an explanatory diagram for explaining a deformation measuring unit of the outer drum, FIG. 3 is an explanatory diagram for explaining a focal position of a high energy beam, and FIG. 4 is a traction roller according to a second embodiment of the present invention. It is the schematic of the quenching apparatus used for the quenching method of the outer drum inner diameter surface of a type transmission.

First, a method for hardening the inner surface of the outer drum of the traction roller type transmission according to the first embodiment of the present invention will be described. In FIG. 1, reference numeral 1 denotes an outer drum integrated with a first rotating shaft 2, and the first rotating shaft 2 is held by a chuck 4 of a motor 3. As the motor 3, an AC servomotor or the like capable of variably controlling the number of rotations is used.
The chuck 4 is driven to expand and contract to move the outer drum 1 up and down. A mold 5 is fixedly disposed above the motor 3, and the mold 5 has a cavity 6 for rotatably restraining the outer diameter surface of the outer drum 1. The material of the mold 5 may be a raw material such as mild steel or carbon steel, but in consideration of heat resistance and wear resistance, a super steel, a high speed tool steel or a ceramic is desirable. In this embodiment, High speed tool steel SKH57 is used. The thickness of the mold 5 can be variously selected according to the strength of the material, but in consideration of the cooling capacity, the diameter of the outer drum 1 is +20 m with respect to the outer diameter.
m or more is desirable.

After the first rotary shaft 2 of the outer drum 1 after the cold forging and turning steps is held by the chuck 4 of the motor 3, the chuck 4 is extended to remove the outer diameter surface of the outer drum 1. It is inserted into the cavity 6 of the mold 5, whereby the entire outer diameter surface of the outer drum 1 is restrained by the mold 5.

Next, while the motor 3 is driven to rotate the outer drum 1, a laser beam (or an electron beam) is irradiated from the upper opening of the mold 5 onto the inner surface of the outer drum 1 to quench the entire inner surface. .

When the beam is applied to the inner diameter surface of the outer drum 1, the outer drum 1 thermally expands. However, since the thermal expansion is suppressed by the mold 5, the deformation of the outer drum 1 is corrected and the roundness is secured. Is done. In addition, the mold 5 functions to increase the heat capacity required for beam quenching and to increase the cooling capacity by heat diffusion, so that a sufficient air cooling effect can be obtained.

After the quenching is completed, the chuck 4 of the motor 3 is contracted to release the outer drum 1 and is removed from the chuck 4 and then subjected to a grinding finish. As is apparent from the above description, in this embodiment, the deformation of the outer drum 1 is corrected by the mold 5 at the time of quenching and the roundness is secured, so that the grinding cost can be reduced, and Since partial quenching is performed using a high energy beam, heat treatment costs can be significantly reduced as compared with carburizing and quenching.

Also, since the mold 5 functions to increase the heat capacity required for beam quenching and to increase the cooling capacity by heat diffusion and to obtain a sufficient air cooling effect, the mold 5 has an undesired effect near the surface of the quenched portion. A hardened layer with a sound martensite structure can be obtained without the completely quenched layer.

[0024]

EXAMPLE 1 Comparative Example A was obtained by carburizing and quenching the outer drum of SCr420, and Comparative Example B was obtained by laser quenching the inner surface of the outer drum of S53C. Electron beam was applied to the inner surface of the outer drum of S53C. The quenched product was Comparative Example C, and the laser quenched inner surface of the outer drum of S53C using the quenching apparatus of FIG.
An example in which the inner surface of the outer drum of S53C was subjected to electron beam quenching using the quenching apparatus of FIG.
The deformation amount (deformation amount C: see FIG. 2), roundness (d portion roundness: see FIG. 2) of the first rotating shaft, and the surface hardness of the inner surface of the outer drum were measured. The outer drum has the same shape and size in both the comparative example and the example, and the deformation amounts C and d are used.
The roundness was measured using a dial gauge.
Laser hardening and electron beam hardening in Comparative Examples B and C and Examples A and B were performed under the following conditions. Laser quenching conditions Laser used 5 kW multi-mode CO ₂ laser Circumferential speed 0.3 m / min Beam oscillation 100 Hz Width 6 mm Defocus amount a / b = 1.2 (see FIG. 3) Output 1.5 kW Electron beam quenching conditions Electron beam used Welder 6 kW 150 kV EBW Circumferential speed 0.3 m / min Beam oscillation 500 Hz Width 10 mm Defocus amount a / b = 1.2 (see FIG. 3) Beam current 2 mA Table 1 shows the results.

[0025]

[Table 1]

As is clear from Table 1, the carburized product of Comparative Example A can obtain a sufficient surface hardness, but the bending (deformation C) of the first rotating shaft is large due to the heat treatment deformation. Cannot be used.

In the laser quenching and the electron beam quenching of Comparative Examples B and C, since only the inner diameter surface of the outer drum is quenched without using a mold, the amount of deformation C of the first rotating shaft is almost nil. The roundness of the d part is poor. In addition, since the heat capacity required for air cooling was not obtained, the hardness near the surface of the inner surface of the outer drum was low. When the structure was examined, the structure was a troostite structure and an incompletely quenched layer.

On the other hand, in the laser quenching and the electron beam quenching of Examples A and B using the molds, the hardened layer having the smallest deformation amount C and the roundness of the d portion was the smallest, and the hard surface near the surface of the inner surface of the outer drum was hard. Obtained.

Next, a method of quenching the inner surface of the outer drum of the traction roller type transmission according to the second embodiment of the present invention will be described. This embodiment differs from the above-described embodiment of the first aspect only in that high-energy beam quenching is changed to induction quenching. Omitted.

In this embodiment, the high-frequency heating device 20 is inserted from the upper opening of the mold 5 and the device 5 is connected to the outer drum 1.
In this state, the motor 3 is driven to rotate the outer drum 1, and a high-frequency current is supplied to the heating coil 21 of the high-frequency heating device 20 to heat the entire inner surface of the outer drum 1. Thereafter, cooling water is supplied from the cooling water port 22 of the high-frequency heating device 20 to the entire inner surface of the outer drum 1 to perform cooling for quenching.

When the inner surface of the outer drum 1 is heated by the heating coil 21, the entire outer drum 1 thermally expands. However, since the thermal expansion is suppressed by the mold 5, the deformation of the outer drum 1 is corrected and a perfect circle is formed. Degree is secured. Also, the mold 5 has a function of adjusting the quenching depth of the induction quenching, and since it has a small thickness, it plays a role of appropriately suppressing the penetration of the hardened layer from the inner diameter surface to the outer diameter side. Has become.

After quenching is completed, the chuck 4 of the motor 3 is contracted to release the outer drum 1 and is removed from the chuck 4 and then subjected to a grinding finish. When the outer drum 1 is released from the mold 5, the outer drum 1 is contracted by cooling.

As is apparent from the above description, in this embodiment, the deformation of the outer drum 1 is corrected by the mold 5 at the time of quenching and the roundness is secured, so that the grinding cost can be reduced. In addition, since the induction hardening is partial quenching, the heat treatment cost can be significantly reduced as compared with carburizing quenching.

Also, since the mold 5 has a function of appropriately preventing the hardened layer from penetrating from the inner diameter surface of the outer drum 1 to the outer diameter side, the occurrence of burning cracks in the outer drum 1 is satisfactorily prevented. can do.

In each of the above embodiments, the hardening of the inner surface of the outer drum 1 of the traction roller type transmission has been described. However, the hardened layer may be formed on the inner surface of the ring-shaped work other than the outer drum. Can be applied.

[0036]

Example 2 Comparative Example D obtained by carburizing and quenching the outer drum of SCr420, Comparative Example E obtained by performing induction hardening on the inner surface of the outer drum of S53C, and S53C using the quenching apparatus shown in FIG. In Example C, the inner diameter surface of the outer drum was subjected to induction hardening, and the deformation amount (deformation amount C: see FIG. 2) and the roundness (d portion roundness:
2) was measured using a dial gauge, and the occurrence of burning cracks on the outer drum was investigated. The outer drum used had the same shape and size in both the comparative example and the example. Further, induction hardening in Comparative Example E and Example C was performed under the following conditions. Induction hardening condition Induction heating device 400 kHz, 50 kW Motor rotation speed 240 rpm Output 11 V × 4 seconds Tempering condition 180 ° C. × 90 minutes Table 2 shows the results.

[0037]

[Table 2]

As is clear from Table 2, the carburized product of Comparative Example D has a sufficient surface hardness, but the first rotating shaft has a large bending (deformation amount C) due to heat treatment deformation. Cannot be used.

Further, in the induction hardening of Comparative Example E, since only the inner surface of the outer drum is hardened without using a mold, the amount of deformation C of the first rotary shaft is almost nil. Bad, the hardened layer penetrates to the outer diameter side,
Burnt cracks were seen.

In contrast, in the induction hardening of Example C using the mold, the amount of deformation C and the roundness of the d part were the smallest, and a sound hardened layer without quenching cracks was obtained.

[0041]

As is apparent from the above description, according to the first aspect of the present invention, the deformation of the outer drum is corrected by quenching and the roundness is secured, so that the grinding cost can be reduced. Moreover, since the partial quenching is performed by the high energy beam, the effect that the heat treatment cost can be significantly reduced as compared with the case of carburizing and quenching can be obtained.

Also, since the mold functions to increase the heat capacity necessary for beam quenching and to increase the cooling capacity by heat diffusion and to obtain a sufficient air cooling effect, the imperfections near the surface of the quenched portion are not sufficient. The effect is obtained that a hardened layer having a sound martensite structure can be obtained without the quenched layer.

According to the second aspect of the present invention, since the deformation of the outer drum is corrected by the mold at the time of quenching and the roundness is ensured, the grinding cost can be reduced, and the partial quenching is performed by induction hardening. Therefore, the effect that the heat treatment cost can be significantly reduced as compared with carburizing and quenching is obtained.

Further, since the mold has a function of appropriately preventing the hardened layer from penetrating from the inner diameter surface of the outer drum to the outer diameter side, it is possible to appropriately prevent the occurrence of burning cracks in the outer drum. The effect that it can be obtained is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus used for a method of hardening an inner diameter surface of an outer drum of a traction roller type transmission according to an embodiment of the first aspect of the present invention.

FIG. 2 is an explanatory diagram for explaining a deformation measuring unit of an outer drum.

FIG. 3 is an explanatory diagram for explaining a focal position of a laser beam.

FIG. 4 is a schematic view of an apparatus used for a method of hardening an inner surface of an outer drum of a traction roller type transmission according to an embodiment of the second aspect of the present invention.

FIG. 5 is an explanatory sectional view illustrating a traction roller type transmission.

FIG. 6 is a sectional view taken along line VI-VI of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Outer drum 2 ... 1st rotating shaft 3 ... Intermediate roller 4 ... 2nd rotating shaft 5 ... Mold 20 ... High frequency heating device

Claims (2)

[Claims] An outer drum integrated with a first rotating shaft, and a second rotating shaft frictionally engaged with an inner peripheral surface of the outer drum via an intermediate roller, wherein rotation of the motor shaft via an oil film is provided. In the method of quenching the inner surface of the outer drum of the traction roller type transmission for reducing or increasing the speed of transmission, the outer drum is inserted into a mold, and in this state, the inner diameter of the outer drum is increased by using a high energy beam. A method of quenching the inner surface of the outer drum of a traction roller type transmission, wherein the surface is quenched. 2. The method for quenching the inner surface of the outer drum of a traction roller type transmission according to claim 1, wherein the inner surface of the outer drum is quenched by induction hardening instead of the high energy beam.