JP2001329317A - Heat treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat treatment method by which the capacity in a heating furnace can effectively be utilized when heat treatment is performed to a thin sheet-made member of a maraging steel. SOLUTION: The heat treatment is performed to the thin sheet-made member of the maraging steel by using a jig 11 for heat treatment provided with a plurality of ring holding members 12 provided with respective cylindrical parts 14 having the height exceeding the width of rings 4 and flange parts 15 extended to the outer peripheral side from the lower end parts of respective cylindrical parts 14 and on which the end surfaces of the rings 4 are mounted, and freely stacked through respective cylindrical parts 12. A plurality of rings 4 having the diameters avoidable mutual contact, are mounted on the respective flange parts 15 at the end surfaces of the rings 4. A plurality of ring holding members 12 on which the rings 4 are mounted are stacked through the cylindrical parts 14. At the inner peripheral side of each stacked ring holding member 12, a drum 2 is held.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heat-treating a member made of a sheet of maraging steel, for example, solution treatment of a cylindrical drum formed by welding the ends of the sheet, and setting the drum to a predetermined width. The present invention relates to a heat treatment method such as solution treatment of a ring formed by cutting and rolling, or aging and nitriding treatment of the ring.

[0002]

2. Description of the Related Art A belt for a continuously variable transmission used for power transmission of a continuously variable transmission or the like includes a laminated ring in which a plurality of metal rings are laminated, and a number of metal elements assembled to the laminated ring. It is configured.

[0003] Among them, the above-mentioned laminated ring is conventionally manufactured by the following method. 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 hardness of the drum, which has been partially increased by the heat at the time of welding, is homogenized. For this purpose, a first solution treatment is performed. Next, the drum after the solution is cut into a predetermined width and rolled to form a ring. Next, a second solution treatment is performed on the rolled ring in order to recrystallize the rolled structure and restore the shape of the metal structure deformed by rolling. Then, the solution-annealed ring is corrected to a predetermined circumferential length, and after aging and nitriding to improve hardness, a plurality of rings having slightly different circumferential lengths are laminated one upon another to form the laminated ring. Form.

[0004] The second solution treatment, which is a heat treatment for the rolled ring, is generally performed by heating the ring in a heating furnace at a temperature equal to or higher than the recrystallization temperature of the maraging steel. However, at this time, if the ring is hung on a hook and heated, there is a problem that the ring undergoes creep deformation due to its own weight, resulting in an extremely elongated elliptical shape. When the shape of the ring is an extremely elongated elliptical shape as described above, it becomes difficult to perform the circumference correction performed after the second solution treatment.

When the ring is placed flat so that the end face of the ring contacts the floor of the heating furnace or the mesh belt moving in the heating furnace, creep deformation due to the weight of the ring is prevented as described above. Thus, an annular ring can be obtained. However, if the rings are laid flat as described above, the number of rings that can be arranged in the heating furnace is limited, and the volume of the heating furnace cannot be used sufficiently effectively in the heat treatment.

Therefore, as shown in FIG.
It is conceivable that the heat treatment is performed using a ring holding member 32 having a flange portion 35 extending from the lower end portion of the cylindrical portion 34 to the outer peripheral side. The ring holding member 32
Inserts the cylindrical member 34 into the inner peripheral side of the ring 4, places the ring 4 on the flange 35 at the lower end surface 4 a thereof, and simultaneously inserts the plurality of ring holding members 32 through the cylindrical portion 34. Are laminated. According to the ring holding member 32, the area occupied by one ring 4 in the heating furnace has a large number of rings 4.
And the solution can be solution-contained, and the volume of the heating furnace can be used effectively.

However, in order to reduce the manufacturing cost, it is desired to utilize the capacity of the heating furnace more effectively.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a heat treatment method capable of effectively utilizing the volume of a heating furnace when heat treating a member made of thin maraging steel. Aim.

[0009]

SUMMARY OF THE INVENTION Therefore, the heat treatment method of the present invention is directed to a ring formed by cutting a cylindrical drum formed by welding the ends of a thin sheet of maraging steel to a predetermined width. A cylindrical portion which is inserted on the peripheral side and has a height exceeding the predetermined width, and an end face of a ring which is extended from the lower end portion of the cylindrical portion to the outer peripheral side and the cylindrical portion is inserted on the inner peripheral side are mounted. And a heat treatment jig provided with a plurality of ring holding members that can be freely stacked via the cylindrical portion. A plurality of rings having a diameter that can avoid contact with each other are mounted on the flange-shaped portion of the ring holding member at the end face of each ring, and the plurality of ring holding members on which the plurality of rings are mounted are mounted on the cylindrical member. It is characterized in that heat treatment is performed by laminating via the shape part To.

[0010] According to the heat treatment method of the present invention, the ring holding member in a state where the ring is flatly placed at the end face is laminated on the flange portion through the cylindrical portion, so that the inside of the heating furnace is conventionally provided. Thus, the heat treatment can be performed by accommodating a large number of rings in the vertical direction with respect to the area required for heat treatment of one ring. Moreover, at this time, since a plurality of rings having a diameter that can avoid contact with each other are placed on the end face of each ring on the flange-shaped portion, conventionally, it is necessary to heat-treat one ring in the heating furnace. The heat treatment can be performed by accommodating a large number of rings in the horizontal direction for the set area. Therefore, the heat treatment can be performed by using the volume of the heating furnace much more effectively.

The heat treatment method according to the present invention is also directed to a cylindrical drum formed by welding the ends of thin maraging steel plates to the inner peripheral side of each ring holding member of the heat treatment jig. The heat treatment is carried out by containing the heat treatment.

After cutting the drum, the ring
Since the ring is formed by rolling, the diameter of the ring is larger than that of the drum, and when the ring holding member is stacked through the cylindrical portion inserted on the inner peripheral side of the ring, a stacked cylinder is formed. A space that can accommodate the drum is formed inside the shape. Therefore, by accommodating the drum in the space and performing heat treatment simultaneously with the ring, the volume of the heating furnace can be more effectively utilized.

[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 manufacturing process of a thin plate member of maraging steel used in the present embodiment, and FIG. 2 is an explanatory sectional view showing one embodiment of a heat treatment jig used in the present embodiment.

The heat treatment method of the present embodiment is applied to heat treatment of a thin plate made of maraging steel used for a lamination ring of a belt for a continuously variable transmission.

The laminated ring is manufactured by the process shown in FIG. In the step shown in FIG. 1, first, a thin plate 1 of maraging steel is bent to form a loop, and then the ends are welded to form a cylindrical drum 2. At this time, since the maraging steel exhibits age hardening due to the heat of welding, high hardness portions appear on both sides of the welded portion of the drum 2.

Then, the first solution treatment is performed by housing the drum 2 in the vacuum furnace 3 and heating it to remove hardness unevenness. 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, it is rolled. Since the rolled ring 4 has a rolled structure near the surface, the rolled ring 4
Is heated in a heating furnace 5 to form a second solution, thereby eliminating the rolled structure and forming uniform metal crystal grains. After cooling, the solution-solutioned ring 4 is corrected to have a predetermined circumferential length, and is subjected to an aging treatment and a nitriding treatment.

Then, among the rings 4 subjected to the nitriding treatment, a plurality of rings 4 each having a slightly different circumferential length, for example, 12
By laminating the rings 4 to each other, a laminated ring (not shown) is formed. In the laminated ring, adjacent rings 4 have a diameter difference of, for example, 0.4 mm or less.

The heat treatment method of the present embodiment uses the drum 2
And the second solution to the ring 4 after the rolling. In the present embodiment, the heat treatment is performed using the heat treatment jig 11 shown in FIG.

As shown in FIG. 2, when the heat treatment jig 11 has a ring holding member 12 for holding the ring 4 and a plurality of ring holding members 12 stacked on the ring holding member 12 on the uppermost layer. And a lid member 13 to be formed. Each of the ring holding member 12 and the lid member 13 can be manufactured by punching a punching metal having a large number of small holes by a press.

The ring holding member 12 has a cylindrical portion 14 inserted into the inner peripheral side of the ring 4 and a flange portion 15 extending from the lower end of the cylindrical portion 14 in the outer peripheral direction. The upper end of 14 has a small-diameter portion 16 that is smaller in diameter than the cylindrical portion 14 and that is fitted into and engaged with the lower end of the cylindrical portion 14 of the upper ring holding member 12. Also, the lid member 1
3 is formed to have a size that covers the upper part of the ring 4 placed on the flange portion 15 of the lower ring holding member 12, and the small diameter portion 16 of the lower ring holding member 12 is fitted on the inner peripheral side. It has a hole 17 for locking.

The ring 4 has one end face formed by the flange 1
5, the two rings 4 having a diameter that can avoid contact with each other are concentrically mounted on the flat plate 5. Here, twelve rings 4 having different circumferential lengths forming one laminated ring are sequentially turned toward the outer circumference from the ring 4 located at the innermost side, and # 1, # 2,.
., # 12, the ring 4 is, for example, # 1, # 7, #
2 and # 8,..., # 6 and # 12, and placed on the flange 15.

In this case, as described above, the rings 4 that are adjacently stacked in the stacked ring have a difference in diameter within 0.4 m from each other. The diameter difference between the ring 4 to be formed and the ring 4 arranged on the inner peripheral side is about 2.0 mm, and does not contact each other. In addition, the rings 4, 4 concentrically mounted as described above expand at the same expansion rate by the heat treatment, so that there is no risk of contact after the heat treatment.

The heat treatment jig 11 stacks a plurality of ring holding members 12 each having the ring 4 mounted on the flange 15 as described above, and attaches the lid member 13 to the uppermost ring holding member 12. They are stacked and housed in the heating furnace 5. At this time, the small diameter portion 16 formed at the upper end of the cylindrical portion 14 of the lower ring holding member 12 is attached to the upper ring holding member 12.
The above-mentioned laminated state can be stably and reliably maintained by being fitted inside and engaged with the lower end of the cylindrical portion 14 or fitted inside the hole 17 of the lid member 13 and locked. .

According to the method of the present embodiment, two rings 4 are mounted on the flange portion 15 per one ring holding member 12, so that compared to the case where one ring is mounted one by one,
A ring 4 that can be accommodated at once if the heating furnace has the same volume
Is doubled.

The flange 1 of one ring holding member 12
The number of rings 4 that can be placed on the ring 5 is not limited to two, and if it is possible to prevent the placed rings 4 from contacting each other, a larger number of rings 4 can be connected to the flange-shaped portion 15. It may be placed on top. For example, on the collar 15
1, # 4, # 7, # 10 and # 2, # 5, # 8, # 11
And # 3, # 6, # 9, and # 12 as one set, and four rings 4 may be placed.
In this case, the interval between the adjacent rings 4 on the flange portion 15 is about 1.2 mm.

The heating furnace 5 can also serve as a heat treatment in the vacuum furnace 3 by adjusting the conditions of the atmosphere. When the ring 4 is solution-solutioned by the heating furnace 5, the drum 2 is housed in the space formed on the inner peripheral side of the cylindrical portion 14 stacked as described above, In solution.

In the above embodiment, the drum 2 and the ring 4
Although the case of solution treatment is described as an example, the heat treatment method of the present invention can also be used for aging and nitriding of the ring 4. In this case, the ring 4 is mounted on the upper surface of the flanged member 15 of the laminated ring holding member 12 in exactly the same manner as in the above-described embodiment. Do not place.

[Brief description of the drawings]

FIG. 1 is a process diagram schematically showing a manufacturing process of a thin plate member made of maraging steel.

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

FIG. 3 is an explanatory sectional view showing another heat treatment method.

[Explanation of symbols]

2 ... drum, 4 ... ring, 11 ... heat treatment jig, 1
2 ring retaining member, 13 lid member, 14 cylindrical portion, 15 flange portion.

Claims (2)

[Claims] 1. A height which is inserted into the inner peripheral side of a ring formed by cutting a cylindrical drum formed by welding end portions of a thin sheet of maraging steel to a predetermined width and exceeding the predetermined width. A cylindrical portion extending from a lower end portion of the cylindrical portion to the outer peripheral side, and a flange portion on which an end surface of a ring in which the cylindrical portion is inserted on the inner peripheral side is placed. A method for heat-treating a thin plate made of maraging steel using a heat-treating jig including a plurality of ring holding members that can be freely stacked via a shape portion, the plurality of rings having diameters capable of avoiding contact with each other. A ring is mounted on the flange portion of the ring holding member at the end face of each ring, and a plurality of ring holding members on which the plurality of rings are mounted are stacked via the cylindrical portion to perform heat treatment. A heat treatment method characterized by the above-mentioned. 2. A heat treatment is performed by accommodating a cylindrical drum formed by welding the ends of a thin maraging steel plate to the inner peripheral side of each ring holding member on which the heat treatment jig is laminated. The heat treatment method according to claim 1, wherein: