JP4360178B2 - Manufacturing method of toroidal type continuously variable transmission - Google Patents

Description

The present invention relates to an improvement in a manufacturing method of a toroidal continuously variable transmission that can be used, for example, as a transmission unit for an automatic transmission of an automobile or as a transmission for various industrial machines.

  The use of toroidal continuously variable transmissions as automatic transmissions for automobiles has been studied and implemented in part. This toroidal continuously variable transmission has a configuration as described in Patent Document 1, for example. 1 and 2 schematically show the basic configuration of this toroidal-type continuously variable transmission. In the structure shown in FIGS. 1 and 2, the input side disk 2 is supported concentrically with the input shaft 1, and the output side disk 4 is fixed to the end of the output shaft 3 disposed concentrically with the input shaft 1. Yes. Further, trunnions 6 and 6 that swing around pivots 5 and 5 that are twisted with respect to the input shaft 1 and the output shaft 3 are disposed inside a casing (not shown) in which a toroidal-type continuously variable transmission is housed. Provided.

  Each trunnion 6, 6 has the pair of pivots 5, 5 concentric with each other for each trunnion 6, 6 on both ends in the length direction (front and back direction in FIGS. 1 and 2). It is provided one by one. The central axes of the pivots 5 and 5 do not intersect with the central axes of the disks 2 and 4 but are twisted at right angles or substantially perpendicular to the direction of the central axes of the disks 2 and 4. Exists in the position. Further, the base half of the support shafts 7 and 7 is supported at the center of the trunnions 6 and 6, and the trunnions 6 and 6 are swung around the pivots 5 and 5 so that the support shafts are supported. 7 and 7 can be adjusted freely. Power rollers 8 and 8 are rotatably supported around the front half portions of the support shafts 7 and 7 supported by the trunnions 6 and 6, respectively. These power rollers 8 and 8 are sandwiched between the inner side surfaces 2a and 4a of the input side and output side disks 2 and 4, respectively.

  The inner side surfaces 2a and 4a of the input side and output side discs 2 and 4 facing each other are obtained by rotating a cross section of an arc centered on the pivot 5 or a curve close to such an arc. It has an arcuate concave surface. And the peripheral surfaces 8a and 8a of each power roller 8 and 8 formed in the spherical convex surface are made to contact | abut to the said inner surface 2a and 4a. Further, a loading cam device 9 is provided between the input shaft 1 and the input side disc 2, and the input cam 2 is elastically pressed toward the output side disc 4 by the loading cam device 9. It can be freely rotated.

  When the toroidal continuously variable transmission configured as described above is used, the loading cam device 9 presses the input side disk 2 against the plurality of power rollers 8 and 8 as the input shaft 1 rotates. Rotate. The rotation of the input side disk 2 is transmitted to the output side disk 4 via the plurality of power rollers 8, 8, and the output shaft 3 fixed to the output side disk 4 rotates.

  When the rotational speeds of the input shaft 1 and the output shaft 3 are changed and when the deceleration is first performed between the input shaft 1 and the output shaft 3, the trunnions 6 and 6 are swung around the pivot shafts 5 and 5. As shown in FIG. 1, the peripheral surfaces 8a and 8a of the power rollers 8 and 8 are arranged near the center of the inner surface 2a of the input side disk 2 and the outer peripheral portion of the inner surface 4a of the output side disk 4, respectively. The support shafts 7 and 7 are inclined so as to contact each other. On the contrary, when the speed is increased, the trunnions 6, 6 are swung so that the peripheral surfaces 8a, 8a of the power rollers 8, 8 are as shown in FIG. The support shafts 7 and 7 are inclined so as to abut the outer peripheral portion 2a and the central portion of the inner side surface 4a of the output disk 4 respectively. If the inclination angles of the support shafts 7 and 7 are set in the middle between those shown in FIGS. 1 and 2, an intermediate gear ratio can be obtained between the input shaft 1 and the output shaft 3.

  During operation of the toroidal type continuously variable transmission constructed and operated as described above, rolling contact portions between the inner surfaces 2a, 4a of the disks 2, 4 and the peripheral surfaces 8a, 8a of the power rollers 8, 8 ( A traction oil film is interposed in the traction section. This traction oil has the role of transmitting power in this traction part, and also has the role of lubricating moving parts such as rolling bearings, so it is made of hard metal such as burrs and wear powder that has separated from the constituent members. It is inevitable that foreign matter gets mixed in. The presence of such foreign matters causes the rolling fatigue life of the surfaces 2a, 4a and 8a constituting the traction portion to be reduced. For this reason, in order to ensure the rolling fatigue life of each of the surfaces 2a, 4a, 8a even when traction oil mixed with foreign matter is used, the two disks 2, 4 and the power rollers 8, 8 have been conventionally used. The amount of retained austenite on the surface is increased. In order to increase the amount of retained austenite, the surface of each member 2, 4, 8 is subjected to heat treatment of carburizing treatment or carbonitriding treatment that has been widely performed in fields other than toroidal-type continuously variable transmissions. It was also used for processing.

  On the other hand, each of the members 2, 4, and 8 constituting the toroidal continuously variable transmission requires a particularly high surface hardness and a deep hardened layer depth, so that the amount of retained austenite is increased as described above. It is necessary to perform the carburizing process and the carbonitriding process for a long time. For this reason, the productivity of each of the members 2, 4, and 8 is poor, and the manufacturing cost of each of the members 2, 4, and 8 and thus the toroidal continuously variable transmission incorporating these members 2, 4, and 8 is low. It is a cause of bulkiness. Moreover, with the heat treatment for a long time, a grain boundary oxide layer and coarse proeutectoid carbide are likely to be generated in each of the members 2, 4, 8. Such a grain boundary oxide layer and coarse pro-eutectoid carbide cause undesired damages such as cracks and cracks, so that it is not preferable to be generated.

  Further, when carburizing or carbonitriding is performed on each of the members 2, 4 and 8, the hardness distribution from the surface of the applied member to the core portion is almost the same over the entire surface except for the influence of the shape. Similarly, it is difficult to adjust the hardness depending on the location. Specifically, a portion that does not require much rigidity, wear resistance, fatigue resistance, etc. is hardened more than necessary. For this reason, after heat processing, the part which needs post-processing, such as cutting and grinding | polishing, becomes hard, and it becomes difficult to perform this post-processing, and the malfunction said that productivity of each said member 2,4,8 falls arises. . Furthermore, when no measures are taken, portions that should not be high in hardness, such as screw portions that are likely to be delayed fracture, are similarly cured. It is necessary to apply a carburizing agent to prevent hardening of these parts to prevent hardening, but since the carburizing process is complicated, not only is productivity low, but the effect is not necessarily uniform. It cannot be obtained, and the problem that it is difficult to stabilize the quality is caused.

  On the other hand, if heat treatment for hardening only the necessary part is performed by induction hardening, the treatment time can be significantly shortened and excellent productivity can be obtained as compared with carburizing and carbonitriding. Moreover, since only an arbitrary place can be hardened, productivity can be improved also from the surface of post-processing, for example, if the part processed after heat processing is not hardened. However, the high-frequency heating performed in the induction hardening process has a short heating time, and the carbide is not sufficiently dissolved in the parent phase as compared with so-called quenching. In general, the material for induction hardening used for bearing components is generally about 0.4 to 0.6% by weight of carbon, but with such materials, The amount of dissolved carbon in the matrix is reduced. For this reason, it is difficult to increase the amount of retained austenite on the surface of the treated member, and when applied to the heat treatment of each of the members 2, 4, 8, the surfaces 2a, 4a, 8a associated with the contamination life The rolling fatigue life cannot be ensured as much as when carburizing or carbonitriding is performed.

  Further, as a heat treatment technique that combines the above-described techniques, Patent Documents 2 and 3 include a technique for performing induction hardening after performing carburization or carbonitriding on the components of the toroidal-type continuously variable transmission. Are listed. According to such techniques described in Patent Documents 2 and 3, the time required for carburizing treatment and carbonitriding treatment is shortened as compared with the prior art, and productivity is improved. The effect of suppressing the formation of carbides can be obtained. However, in the case of the improved prior art described in Patent Documents 2 and 3, no special consideration is given to the metal structure after carburizing or carbonitriding. For this reason, for example, the hardness and hardness distribution obtained after induction quenching performed after carburizing or carbonitriding may not be stable. In addition, as in the case where the heat treatment of each of the members 2, 4 and 8 is only carburizing treatment or carbonitriding treatment, the portion subjected to cutting or grinding after the heat treatment is cured, so that workability and productivity are improved. However, the problem that the cost is high remains.

JP 2003-222216 A Japanese Patent No. 3028688 JP-A-10-103440

In view of the circumstances as described above, the present invention is to obtain the input side and output side disks and power rollers that can secure a sufficient rolling fatigue life even when using traction oil mixed with foreign matters at a low cost. It is aimed. Specifically, the productivity of the input and output disks and power rollers with a high amount of retained austenite on the surface is improved by shortening the heat treatment time, and grain boundaries that cause damage such as cracks and cracks. The object is to realize a production method capable of suppressing the formation of an oxide layer and coarse proeutectoid carbide. Furthermore, only the desired portions where hardness is required are cured, and other portions are not unnecessarily cured, and the hardness can be set to a level suitable for cutting and grinding performed after heat treatment. The purpose is to improve the workability of grinding.

The toroidal-type continuously variable transmission that is the object of the manufacturing method of the present invention is a concave surface having a circular arc cross section, each of which is made of steel, on the inner side surfaces of both the input side and output side discs, each having a partial spherical shape Power is transmitted between the input side disk and the output side disk by bringing the peripheral surfaces of a plurality of steel power rollers into rolling contact with each other via an oil film of traction oil.
In particular, in the method for manufacturing a toroidal-type continuously variable transmission according to the present invention, at least one member of the both disks and the power rollers is subjected to carburization or carburization with a Cp value of 0.7 to 1.5. After the nitriding treatment , cooling is performed to lower the temperature of the tempering heat treatment performed after the cooling, and then the A ₁ transformation point or lower, which is 160 ° C. or higher and 250 ° C. or lower, or 450 ° C. or higher. By performing a heat treatment for tempering at a temperature of 700 ° C. or lower, the average particle size of the carbide on the surface is set to 3.0 μm or less, and thereafter, induction hardening is applied to necessary portions.

In the case of the manufacturing method of the toroidal type continuously variable transmission of the present invention configured as described above, the inner surface of both the input side and output side disks and the peripheral surface of the power roller (and the inner ring formed on one side surface in the axial direction). The carbon concentration and nitrogen concentration on the surface of the orbit) are increased by carburizing or carbonitriding performed before induction quenching. Further, the amount of retained austenite on the inner surface of both the input side and output side disks and the peripheral surface of the power roller can be increased as compared with the case of induction hardening alone. Moreover, since the metal structure before induction hardening is adjusted, stable quality can be obtained.

  In addition to the inner surface of both the input side and output side disks and the peripheral surface (and inner ring raceway) of the power roller, the parts subjected to machining such as cutting and grinding after heat treatment are subjected to the carburizing process or the carbonitriding process. It can be tempered to make it suitable for processing. The hardness of the portion subjected to the machining after the heat treatment can be adjusted by changing the tempering conditions.

  In the case of the present invention, the hardened layer depth of the inner surface of both the input side and output side discs and the peripheral surface (and inner ring raceway) of the power roller is determined by induction hardening performed after carburizing or carbonitriding. Secured. Therefore, assuming that the hardened layer depth is the same, the processing time of the carburizing process or the carbonitriding process as compared with the case where the hardened layer is formed only by the carburizing process or the carbonitriding process as in the prior art described above. Can be shortened. For this reason, generation | occurrence | production of a grain boundary oxide layer and coarse pro-eutectoid carbide can be suppressed, and it can make it hard to generate | occur | produce damages, such as a crack and a crack.

Of the carburizing treatment and carbonitriding treatment, a more preferred treatment method is carbonitriding treatment. If the Cp (carbon potential) value is too high in the carburizing process, pro-eutectoid carbide with a particle size of 10 μm or more in the thinned parts such as the input and output disks and the edge of the power roller. This causes the possibility of damage such as chipping during manufacture and use. On the other hand, in the case of carbonitriding, nitrogen is diffused together with carbon, so the Cp value can be set low, and precipitation of proeutectoid carbide can be suppressed. In order to actively reduce the particle size of the carbide, it is preferable to increase the NH ₃ flow rate during carbonitriding. The surface nitrogen concentration after carbonitriding is preferably 0.05% or more, more preferably 0.2% or more. In addition, Cp value shall be 0.7-1.5 also when performing a carburizing process and a carbonitriding process.

  In any case, when the particle size of the carbide formed on the surface is reduced, the carbide easily dissolves in the parent phase even by heating for a short time such as induction hardening, and the amount of retained austenite is stabilized stably. I can get it. On the other hand, if the particle size of the carbide existing before induction hardening is too large on the inner surface of both the input side and output side disks and the peripheral surface (and inner ring raceway) of the power roller, this induction hardening is performed. As a result, overheating is caused, and there is a possibility that proper hardness and hardness distribution cannot be obtained. In order not to cause such overheating, the average particle size of the carbide before induction hardening is set to 3 μm or less.

The tempering temperature is determined so that the hardness required for the non-hardened portion, that is, the inner surface of both the input side and output side discs and the peripheral surface of the power roller (and the inner ring raceway) can be obtained. ₁ transformation point or less. However, when the tempering temperature exceeds 700 ° C., the coarsening accompanying the spheroidization of the carbide becomes remarkable, and the high frequency hardenability performed after the tempering is lowered. On the other hand, in the range of 250 ° C. to 450 ° C., temper embrittlement is manifested depending on the material components, and there is a possibility that damage such as chipping or cracking of the member occurs. When these things are considered, the preferable range of the said tempering temperature shall be any temperature range of 160-250 degreeC or 450-700 degreeC. The tempering may be performed by high frequency induction heating. If tempering is performed by high-frequency induction heating, the hardness of the portion not subjected to high-frequency quenching can be adjusted to an arbitrary value.

When practicing the present invention, pearlite is preferably included in the metal structure before induction hardening.
If comprised in this way, since a carbide | carbonized_material dissolves easily in a parent phase with induction hardening, the amount of residual austenates can be made high.
Thus, in order to more effectively perform solid solution of carbide in the matrix accompanying induction hardening, in order to include pearlite in the metal structure before induction hardening, after carburizing or carbonitriding It is preferable that the cooling of this is performed slowly by furnace cooling or standing cooling rather than rapid cooling.

  Induction hardening to obtain the required hardness and hardened layer depth is performed on the inner surface of both the input and output disks, the peripheral surface of the power roller and the inner ring raceway where high hardness is required. Do. Induction hardening is performed on the inner side surfaces of both the input side and output side discs, the peripheral surface of the power roller and the inner ring raceway on portions where high hardness is required. Such parts include spline grooves and key grooves for transmitting rotational force between any of the disks and a rotating shaft that passes through the disks, and the outer surface of the input side disk to form a loading cam device. And a tooth surface of a gear for taking out the power formed on the outer peripheral edge of the output side disk. However, the processing for obtaining the necessary hardness and the hardened layer depth by induction hardening is not limited to such a portion, but can be performed for any portion. In addition, regarding the hardness and hardness distribution of the hardened part by induction hardening, by changing the induction hardening conditions (coil shape, gap between coil and workpiece, power output, output frequency, cooling method, etc.) Can be adjusted arbitrarily.

  FIG. 3 shows the case where the present invention is applied to the power roller 8, and FIG. 4 shows the case where the present invention is also applied to the input side disk 2 (or the output side disk 4). In any case, the carbon concentration or the carbon concentration and the nitrogen concentration are higher in the surface portion 10 (oblique lattice portion) than in the core portion 11 by carburizing treatment or carbonitriding treatment. In any case, after tempering, induction hardening is applied to the portion 12 where high hardness is required. That is, in the case of the power roller 8 shown in FIG. 3, a circumferential surface 8 a (traction surface) that contacts the input side disk 2 (or output side disk 4) and a thrust ball bearing are formed on one side surface in the axial direction. The formed inner ring raceway 13 is subjected to induction hardening. Further, in the case of the input side disk 2 (or the output side disk 4) shown in FIG. 4, an inner side surface 2a (4a) contacting the peripheral surface 8a of the power roller 8 and a loading cam device are configured. The outer surface 14 (only in the case of the input side disk 2) on which a cam surface is formed is subjected to induction hardening.

  The portion 12 shown in FIGS. 3 and 4 that is hardened by induction hardening and requires high hardness is merely an example, and if necessary, induction hardening can be applied to any portion. For example, when it is necessary to increase the hardness of a part integrally formed with a disk or a power roller, as in the case where an output gear is integrally formed on an output side disk, induction hardening is also applied to that part. Can be applied. Further, in the case of the output side disk 16 as shown in FIG. 5, which is incorporated in a double cavity type toroidal type continuously variable transmission, the both side surfaces 15 and 15 are traction surfaces for rolling contact with the peripheral surface of the power roller. Since the both side surfaces 15 and 15 become the portion 12 requiring high hardness, the both side surfaces 15 and 15 are subjected to induction hardening.

  Next, an experiment conducted for confirming the effect of the present invention will be described. In the experiment, first, a traction unit for transmitting power by constructing both input side and output side disks and power rollers by using six types of steel materials A to F having the composition shown in the following Table 1 and combining them. The durability life of each of these traction units was evaluated. Both the input side and output side disks and the power roller constituting the same traction unit were made of the same kind of steel.

In addition, the six types of steel materials A to F were subjected to the heat treatment shown in the following Table 2, and 11 types of samples (Examples 1 to 11) belonging to the present invention and 5 types of samples that deviated from the present invention. (Comparative Examples 1 to 3 and Conventional Examples 1 and 2) were made.

  The heat treatment pattern in Table 2 was any of those shown in FIGS. Of these, pattern 1 is performed in the order of “carburizing treatment → refining → high frequency quenching → tempering”, and more specifically, in the process shown in FIG. Pattern 2 is performed in the order of “carbonitriding → refining → high-frequency quenching → tempering”, and more specifically, the process shown in FIG. Further, the pattern 3 is performed in the order of “carbonitriding treatment → tempering”, and more specifically, in the process shown in FIG. Further, the pattern 4 is performed in the order of “high frequency quenching → tempering”, and more specifically, the process shown in FIG.

In addition, the conditions of induction hardening are within the range described below, so that a hardness gradient is obtained such that the hardness at the maximum shear stress depth Zst position generated in the endurance life test is Hv 700 or more. Determined. Therefore, the induction hardening conditions in each part of the input side and output side disks and the power roller are different within the following conditions. However, regarding the same parts, all of the examples, the comparative examples, and the conventional examples are the same except for the conventional example 1.
High frequency output: 50-250kW
Frequency: 10～200KH _Z heating time 3-10 seconds Cooling method: 60 ° C. oil cooling Also, with respect to the cooling condition after carburizing or carbonitriding treatment, the furnace cooling, the average cooling rate to 300 ° C. 10 ° C. / In the oil cooling, cooling (rapid cooling) was performed in a heat-treated oil at 60 ° C. immediately after the treatment.

  For the 11 types of samples that belonged to the present invention and the 5 types of samples that deviate from the present invention made under such conditions, after the tempering of both the input side and output side disks and the power roller was completed (high-frequency baking). Table 3 below shows the quality of the product (before placing), the quality of the finished product (after induction hardening), and the results of the durability test. In addition, a quality survey was conducted on lots (same material as those used in the durability test) that were subjected to the same heat treatment as the input side and output side disks and power rollers used in the durability test.

In order to obtain the surface carbide average particle diameter in the data shown in Table 3, the depth position corresponding to the machining allowance in the finishing process performed after completion of the heat treatment for both the input side and output side disks and the power roller, Each field of view was observed with a metal microscope at a magnification of 1000 times. And the average particle diameter of the spherical carbide was converted into the equivalent circle diameter.
Whether the pearlite structure was present or not was observed at the same position where the surface carbide average particle diameter was obtained.
As for the carbon concentration and nitrogen concentration, measurements were made at three arbitrary points at the same position where the surface carbide average particle diameter was obtained by EPMA (Electoric Probe Micro Analyzer). The average value was shown.
Regarding the surface hardness after the tempering, arbitrary three points on the surface of each of the input side and output side disks and the power roller were measured, and the average value was calculated. Note that a Vickers hardness tester was used for the measurement, and at the time of measurement, some polishing was performed to improve the surface roughness.

Regarding the surface hardness of the finished product, the average value of the hardness at the maximum shear stress position Zst of the traction surfaces of both the input and output disks and the power roller is described. For the hardness measurement, a Vickers hardness tester was used, and arbitrary three points were measured for each of the input side and output side disks and the power roller, and the average value was calculated.
The amount of retained austenite (γ _R ) was determined as an average value of measured values at a depth position of 20 μm from the inner surface of both the input and output disks and the peripheral surface of the power roller (traction surface). The measurement was performed by measuring the traction surfaces of both the input side and output side disks and the power roller, and calculating an average value.
The presence or absence of pro-eutectoid carbide was determined by observing the microstructure of the cross-section of the thinned corners of both the input and output disks and the power roller circled in FIG. The presence or absence of pro-eutectoid carbide exceeding 1 was investigated. In the investigation, observations were made on cross sections in three directions orthogonal to each other in all cross sections in the circled portion in FIG.

The durability test was performed under the following conditions by assembling the traction unit as a toroidal continuously variable transmission. The test was conducted until any part of the traction unit was damaged or until 100 hours had passed.
Input shaft speed: 3000 min ^-1
Input torque: 400Nm
Gear ratio of toroidal-type continuously variable transmission: 1 (constant speed)
Lubricating oil: Commercial traction oil Lubricating oil supply temperature: 80 ° C
Contaminated foreign matter: 100 ppm of 74 to 147 μm iron powder (mixed with iron powder imitating foreign matter from each part of the actual transmission)

As a result of the endurance test conducted under such conditions, the test was completed without any breakage in any part of the traction unit until 100 hours passed. It described in Table 3.
From the results of such experiments, in each of the examples belonging to the present invention, a durable life equal to or higher than that of the conventional example 1 in which the heat treatment is only carbonitriding is obtained, and only induction hardening is performed. Since the amount of retained austenite is higher than that of Conventional Example 2, the result is that the durability life is more excellent. As described above, the conventional example 1 is not particularly problematic in terms of durability, but the manufacturing cost increases.

Moreover, from the comparison between Example 1 and Example 2, in the carburizing treatment and the carbonitriding treatment, due to the difference in the surface carbon concentration, the carbonitriding treatment has a smaller average particle size of the carbide after the tempering is completed. Therefore, it can be seen that the amount of retained austenite in the finished product increases. This tendency is also observed in other examples, and it can be seen that the carbonitriding treatment is more preferable than the carburizing treatment.
Further, when Example 2 and Example 9 are compared, in Example 9 where the tempering temperature is high, the spheroidization of the carbide proceeds, and the average particle size of the carbide after tempering is increased. I understand. For this reason, when induction hardening is performed, Example 9 in which the average particle size of the carbide is large reduces the amount of solid solution in the parent phase and decreases the amount of retained austenite. The hardness after refining is lower in Example 9 where the refining temperature is 700 ° C than in Example 2 where the refining temperature is 500 ° C. In Comparative Example 1, the tempering temperature of Example 2 was set to 740 ° C. However, since the spheroidization of the carbide further progressed, the retained austenite after induction hardening decreased. And since the amount of retained austenite is small, a sufficient durability life could not be obtained. From this, it can be seen that the tempering temperature is preferably 700 ° C. or lower.

  Further, in Example 10, the tempering temperature was set to 160 ° C., but the hardness after the tempering was completed is almost the same as that of Conventional Example 1 in which only the carbonitriding process is performed. However, in the case of Example 10 combined with the induction hardening process, the carbonitriding time was about 5 hours, whereas in the case of only the carbonitriding process of Conventional Example 1, the same hardened layer depth was used. Therefore, the carbonitriding time was 40 hours. From this, it can be seen that according to the method of the present invention, the time required for the heat treatment can be shortened and the productivity can be remarkably improved.

In Comparative Example 2, the Cp value at the time of the carburizing process is 1.6, and the precipitated carbide is coarse. For this reason, partial overheating occurred during induction hardening, and precipitated carbide having a particle size of 10 μm or more was observed at the edge portion of the member (the portion circled in FIG. 10). Similarly, in Comparative Example 3, since the precipitated carbide diameter was large and a sufficient amount of retained austenite was not obtained, a sufficient durability life could not be obtained.
As is apparent from the experimental results as described above, according to the present invention, both the input side and output side disks and the power rollers constituting the traction part of the toroidal-type continuously variable transmission are secured and produced. This contributes to a reduction in the cost of the toroidal continuously variable transmission.

The side view which shows the basic composition of the toroidal type continuously variable transmission used as the object of this invention in the state at the time of maximum deceleration. The side view similarly shown in the state at the time of maximum acceleration. Sectional drawing which shows the case where this invention is applied to a power roller. Sectional drawing which shows the case where it applies to an input side disk similarly. Sectional drawing which shows the case where it applies to an output side disk similarly. Process drawing which shows the 1st example of a heat processing pattern. Process drawing which shows the 2nd example. Process drawing which shows the 3rd example. Process drawing which shows the 4th example. Sectional drawing of both the input side output disk and the power roller which shows the part which observed the presence or absence of pro-eutectoid carbide.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input shaft 2 Input side disk 2a Inner side surface 3 Output shaft 4 Output side disk 4a Inner side surface 5 Pivot 6 Trunnion 7 Support shaft 8 Power roller 8a Peripheral surface 9 Loading cam apparatus 10 Surface part 11 Core part 12 High hardness is required 13 Inner ring raceway 14 Outer side 15 Side 16 Output side disc

Claims (4)

By rolling and contacting the peripheral surfaces of a plurality of power rollers, each of which is a partial spherical shape, on the inner side surfaces of both the input side and output side discs, each of which is a concave surface having an arcuate cross section, via an oil film of traction oil, Of the toroidal type continuously variable transmission that transmits power between the input side disk and the output side disk, at least one member of both the disks and the power rollers has a Cp value of 0.7 to 1 After the carburizing treatment or carbonitriding treatment in .5 , the cooling is performed to lower the temperature of the heat treatment for the tempering performed after this cooling, and the temperature is 160 ° C. or higher, which is not higher than the A ₁ transformation point. or less, or, after an average particle size of the carbide of the surface and 3.0μm or less by a heat treatment of performing refining at a temperature of 450 ° C. or higher 700 ° C. or less, the induction hardening a necessary portion Method of manufacturing to the toroidal type continuously variable transmission. The manufacturing method of the toroidal type continuously variable transmission according to claim 1 , wherein pearlite is included in the structure before induction hardening. The manufacturing method of the toroidal type continuously variable transmission according to any one of claims 1 to 2 , wherein cooling by furnace cooling or standing cooling is performed after carburizing or carbonitriding. The method for manufacturing a toroidal continuously variable transmission according to any one of claims 1 to 3 , wherein the desired portion is tempered by high-frequency induction heating.

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