JP2002173713A - Heat-treating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-treating method with which a circumferential length difference between both edge parts of a metallic ring can be reduced. SOLUTION: The circumferential lengths of both edge parts 4a, 4b of the metallic ring 4 formed by rolling after cutting a drum 2 formed by welding a thin plate of maraging steel 1 into a prescribed width, are compared, and the ring is flatly laid at the edge part side 4a having shorter circumferential length. A cylindrical part 12 is inserted into the inner peripheral side of the ring 4 by using a metallic ring holding member 11 and flatly laid on a flange part 13 at the edge part side 4a, and also, a plurality of metallic ring holding members 11 are stacked through the cylindrical parts 12. When the ring 4 is flatly laid on the flange part 13 of the metallic ring holding member 11 at the edge part side 4a, a gap S between the edge part side 4b having longer circumferential length and the flange part 13 of the stacked other metallic holding member 11, is regulated in the range of 1-2 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a continuously variable transmission (CV).
The present invention relates to a heat treatment method such as solution treatment of a metal ring used for a belt such as T).

[0002]

2. Description of the Related Art Conventionally, a laminated ring used for a belt for a continuously variable transmission or the like is manufactured as follows. First, the ends of thin plates of maraging steel, which is super-strong steel, are welded to each other to form a cylindrical drum, and the drum is cut to a predetermined width to form a metal ring, and the metal ring is rolled. Next, solution treatment is performed on the rolled metal ring in order to recrystallize the rolled structure and restore the shape of the metal structure deformed by rolling. Then, the metal ring after solution treatment is corrected to a predetermined circumferential length, and after aging and nitriding treatment to improve hardness, a plurality of metal rings having slightly different circumferential lengths are laminated on each other to form a laminated ring. To form

[0003] The solution treatment is generally performed by heating the metal ring in a heating furnace at a temperature equal to or higher than the recrystallization temperature of the maraging steel. At this time, if the metal ring is heated in a state of being hung on a hook, the metal ring undergoes creep deformation due to its own weight, and the metal ring becomes extremely elongated and elliptical, and it becomes difficult to correct the circumference in a subsequent process. . Therefore, at the time of the solution treatment, in order to prevent the creep deformation, the metal ring may be flatly placed at one end thereof on a floor surface of the heating furnace or a mesh belt moving in the heating furnace. Conceivable.

[0004] However, when the metal ring is placed flat as described above, when the metal ring is cooled after the solution treatment, the edge of the metal ring on the side in contact with the floor surface or the mesh belt is formed. Since the opposite edge exposed to the cooling atmosphere is hardly cooled and the cooling is fast at the opposite edge exposed to the cooling atmosphere, the edge exposed to the cooling atmosphere shrinks more and deforms so as to fall down to the inner peripheral side of the metal ring. There is an inconvenience that sometimes. If one edge of the metal ring is deformed as described above and a difference occurs in the peripheral lengths of both edges, the amount of processing is made uniform in the width direction of the metal ring in the peripheral length correction in a later process. In addition, the difference in the circumferential length is increased in the aging treatment and the nitriding treatment in the subsequent steps.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat treatment method capable of solving such inconveniences and reducing the difference in the circumferential length between both edges of the metal ring.

[0006]

In order to achieve the above object, a heat treatment method of the present invention is to cut a cylindrical drum formed by welding the ends of a thin maraging steel sheet into a predetermined width. A method of performing a heat treatment by placing a metal ring formed by rolling flat at one edge, and comparing the perimeters of both end edges of the metal ring, the perimeter at the shorter edge. It is characterized by being placed flat.

[0007] The metal ring has a difference in the peripheral length of both end edges due to the rolling process in the previous step. Therefore, in the heat treatment method of the present invention, first, the perimeters of the both ends of the metal ring are compared to determine which side has the shorter perimeter. The comparison of the perimeters may be performed by measuring the length of the perimeters of both ends of the metal ring, or may be performed by measuring the diameters of both ends of the metal ring.

Next, when it is determined which side of the circumference is shorter, the metal ring is placed flat at the edge having the shorter circumference and subjected to heat treatment.

In the heat treatment, during cooling, the edge on the opposite side exposed to the cooling atmosphere cools faster than the edge on the grounded side, and the shrinkage is larger. Therefore, by laying the metal ring flat at the shorter peripheral edge as described above, the longer peripheral edge has a larger amount of shrinkage, and the metal ring has two ends. The difference in circumference can be reduced.

A heat treatment method according to the present invention is directed to a metal ring holding apparatus comprising: a cylindrical portion having a height larger than the width of the metal ring; and a flange portion extending from a lower end of the cylindrical portion to an outer peripheral side. Using a member, the cylindrical portion is inserted into the inner peripheral side of the metal ring, and the metal ring is placed flat on the flange portion with the shorter peripheral edge, and is inserted through the cylindrical portion. And stacking a plurality of metal ring holding members. As described above, when heat treatment is performed with metal rings placed flat, the number of metal rings that can be accommodated is limited by the floor area of the heating furnace. Therefore, using the metal ring holding member,
By stacking a plurality of metal ring holding members via the cylindrical portion and performing heat treatment, it is possible to increase the number of metal rings that can be accommodated with respect to the floor area of the heating furnace. The floor area can be used effectively.

At this time, if the gap between the edge opposite to the side grounded to the flange and the flange of another holding member stacked thereover is narrow, the edge is May not be sufficiently shrunk due to the heat of other holding members. Therefore, the heat treatment method of the present invention is characterized in that, when the metal ring is placed flat on the flange portion of the metal ring holding member with the shorter peripheral edge, the metal ring has the longer peripheral length. And the gap between the flange of the other metal ring holding member laminated on the cylindrical portion of the metal ring holding member is 1 to 3.
It is characterized by being in the range of 2 mm.

If the gap is less than 1 mm, the edge having the longer circumference may not be sufficiently shrunk due to the influence of heat of another metal ring holding member. On the other hand, if the gap exceeds 2 mm, the overall volume becomes bulky when a large number of the metal ring holding members are stacked.

[0013]

Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is a process diagram schematically showing a main part of a manufacturing process of a metal ring, and FIG. 2 is an explanatory sectional view showing a heat treatment method of the present embodiment.

When manufacturing a metal belt used for a belt of a continuously variable transmission or the like, first, as shown in FIG. 1, a thin plate 1 of maraging steel is bent to form a loop, and then the ends are welded to each other. Thus, a cylindrical drum 2 is formed.
At this time, since the maraging steel shows age hardening due to the heat of welding, high hardness portions appear on both sides of the welded portion of the drum 2, thereby causing welding distortion.

Then, the first solution treatment is performed by holding the drum 2 in the vacuum furnace 3 and holding it at a predetermined temperature for a predetermined time, and the hardness partially hardened by the heat at the time of welding is reduced. Homogenize. When the first solution treatment is completed, the drum 2 is unloaded from the vacuum furnace 3 and cut into a predetermined width to form a ring 4.

The ring 4 formed as described above is
Next, after being rolled at a rolling reduction of 40 to 50%, it was stored in a heating furnace 5 and maintained at a predetermined temperature for a predetermined time to perform a second solution treatment, recrystallize a rolled structure, and was deformed by rolling. Restores the shape of the metal structure.

When the second solution treatment is completed,
The ring 4 is moved from the heating furnace 5 to the cooling chamber 6, cooled in the cooling chamber 6, then carried out, and the circumference is corrected. Then, the ring 4 having undergone the perimeter correction is next housed in a heat treatment device (not shown), subjected to aging treatment and nitriding treatment, and thereafter, a plurality of rings 4 each having a slightly different perimeter are laminated on each other. Thereby, the metal belt is formed.

The heat treatment method of this embodiment is applied to the second solution treatment, and is performed using the metal ring holding member 11 shown in FIG. The metal ring holding member 11 includes a cylindrical portion 12 inserted into the inner peripheral side of the ring 4 and a flange portion 13 extending from the lower end of the cylindrical portion 12 to the outer peripheral direction.

The ring 4 after rolling is as shown in FIG.
The circumference may be different between the edge 4a and the edge 4b. Therefore, in the present embodiment, first, the edge 4 of the ring 4
By comparing the circumferences of a and 4b, it is determined which circumference is shorter. The circumference may be compared by measuring the circumference itself or by measuring the diameter.

Then, as shown in FIG. 2, the ring 4 is placed on the metal ring holding member 11 in a state where the ring 4 is placed flat on the flange 13 with the shorter edge 4a, and the ring 4 is placed thereon. A plurality of metal ring holding members 11 placed on the cylindrical portion 12
To be laminated. Then, the plurality of metal ring holding members 11 are accommodated in the heating furnace 5 in a stacked state. Also,
After the solution treatment in the heating furnace 5 is completed, the ring 4 is moved to the cooling chamber 6 while being placed on the metal ring holding member 11, and is cooled in the cooling chamber 6.

When the ring 4 is cooled in the cooling chamber 6, the ring 4 is in contact with the flange 13 at the edge 4a having the shorter circumference, but the edge 4b having the longer circumference has no effect. Because there is nothing to contact and it is exposed to the atmosphere in the cooling chamber 6, the edge 4
b is easier to cool. As a result, the ring 4 has a larger amount of contraction at the edge 4b having the longer circumference than the edge 4a, and is deformed as shown by the imaginary line in FIG.
The circumference difference of b is reduced.

At this time, the edge 4b having the longer circumference of the ring 4 and the metal ring holding member 11
If the gap S with the flange 13 is not at least 1 mm or more, the edge 4b cannot be sufficiently shrunk, and the effect of reducing the circumferential length difference between the edges 4a and 4b is sufficiently obtained. I can't. On the other hand, if the gap S exceeds 2 mm, for example, when the metal ring holding members 11 are stacked in 5 to 6 levels, the total of the gaps S exceeds the width of the ring 4 and the number of rings 4 that can be processed at one time decreases. This is disadvantageous. Therefore, it is preferable that the gap S be in the range of 1 to 2 mm.

In the present embodiment, the heat treatment of the ring 4 is performed using the metal ring holding member 11, but the ring 4 is heated without using the metal ring holding member 11 and the floor surface of the heating chamber 5 and the cooling chamber 6 are used. Alternatively, the heat treatment may be performed by directly placing the heating belt 5 and the mesh belt moving in the cooling chamber 6 in a flat manner.

In the present embodiment, the second solution treatment after the rolling treatment is described as an example.
The present invention can be applied to other heat treatments such as a first solution treatment after welding, an aging treatment, and a nitriding treatment.

[Brief description of the drawings]

FIG. 1 is a process diagram schematically showing a main part of a manufacturing process of a metal ring.

FIG. 2 is an explanatory sectional view showing one embodiment of the heat treatment method of the present invention.

[Explanation of Signs] 1 ... Malaging steel thin plate, 2 ... Drum, 4 ... Metal ring, 5 ... Heating furnace, 6 ... Cooling room, 11 ... Metal ring holding member, 12 ... Cylindrical part, 13 ... Flange part .

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tomoji Takahashi 1-10-1 Shinsayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. F-term (reference) 4K034 AA02 AA10 BA01 BA06 CA05 EA11 EC06 GA08 4K042 AA23 AA24 BA10 CA15 DA06 DB07 DF01 4K055 AA06 HA07 HA12 HA18 HA27

Claims (3)

[Claims] 1. A metal ring formed by cutting and rolling a cylindrical drum formed by welding the ends of a thin sheet of maraging steel to a predetermined width and flattening at one end at a heat treatment. A heat treatment method characterized by comparing the perimeters of both edges of the metal ring, and laying flat at the edge having the shorter perimeter. 2. A metal ring holding member comprising: a cylindrical portion having a height greater than a width of the metal ring; and a flange portion extending outward from a lower end of the cylindrical portion. A cylindrical portion is inserted into the inner peripheral side of the metal ring, and the metal ring is placed flat on the flange portion with the shorter peripheral edge, and a plurality of metal rings are inserted through the cylindrical portion. The heat treatment method according to claim 1, wherein the holding members are laminated. 3. When the metal ring is placed flat on the flange-shaped portion of the metal ring holding member with the edge having the shorter circumference, the edge having the longer circumference of the metal ring is connected to the edge. 3. The heat treatment method according to claim 2, wherein a gap between the metal ring holding member and a flange portion of another metal ring holding member laminated on the cylindrical portion is in a range of 1 to 2 mm.