JP3779129B2 - Heat treatment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a heat treatment method for a sheet member made of maraging steel, for example, forming a solution of a cylindrical drum formed by welding end portions of the sheet, and cutting and rolling the drum to a predetermined width. The present invention relates to a heat treatment method such as solution treatment of a ring or aging / nitriding treatment of the ring.
[0002]
[Prior art]
A continuously variable transmission belt used for power transmission of a continuously variable transmission or the like includes a stacked ring in which a plurality of metal rings are stacked, and a number of metal elements that are assembled to the stacked rings.
[0003]
Of these, the laminated ring is conventionally manufactured by the following method. First, the ends of thin sheets of maraging steel, which is a super strong steel, are welded together to form a cylindrical drum, and the hardness partially increased by the heat during welding is homogenized with respect to the drum. Therefore, the first solution treatment is performed. Next, the solution-treated drum is cut into a predetermined width and rolled to form a ring. Next, in order to recrystallize the rolled structure on the rolled ring and restore the shape of the metal structure deformed by rolling, a second solution treatment is performed. And after correcting the ring after the solution to a predetermined peripheral length, and performing aging and nitriding treatment to improve the hardness, a plurality of rings having different peripheral lengths are laminated to each other little by little. Form.
[0004]
The second solution treatment, which is a heat treatment for the rolled ring, is generally performed by heating the ring at a temperature equal to or higher than the recrystallization temperature of the maraging steel in a heating furnace. However, if the ring is heated while being suspended from the hook at this time, there is a problem that the ring undergoes creep deformation due to its own weight, resulting in an extremely elongated elliptical shape. If the shape of the ring becomes an extremely long and narrow elliptical shape as described above, it is difficult to correct the circumferential length performed after the second solution treatment.
[0005]
When the ring is placed flat so that the end face of the ring contacts the floor surface of the heating furnace or the mesh belt moving in the heating furnace, the creep deformation due to the weight of the ring is prevented as described above, 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.
[0006]
Therefore, as shown in FIG. 3, it is considered to perform the heat treatment using a ring holding member 32 including a cylindrical portion 34 and a flange-like portion 35 extending from the lower end portion of the cylindrical portion 34 to the outer peripheral side. It is done. The ring holding member 32 has a cylindrical member 34 inserted into the inner peripheral side of the ring 4, and the ring 4 is placed on the flange portion 35 at the lower end surface 4 a thereof, and a plurality of the ring holding members 32 are interposed via the cylindrical portion 34. The ring holding member 32 is laminated. According to the ring holding member 32, a large number of rings 4 can be accommodated in the area occupied by one ring 4 in the heating furnace, and solutionization can be performed, and the volume of the heating furnace can be effectively used. Can do.
[0007]
However, in order to reduce the manufacturing cost, it is desired to use the volume of the heating furnace more effectively.
[0008]
[Problems to be solved by the invention]
In view of such circumstances, an object of the present invention is to provide a heat treatment method capable of effectively utilizing the volume of a heating furnace when heat treating a thin plate member of maraging steel.
[0009]
[Means for Solving the Problems]
Therefore, the heat treatment method of the present invention is inserted into the inner peripheral side of a ring formed by cutting a cylindrical drum formed by welding end portions of thin sheets of maraging steel to each other to obtain the predetermined width. Yes a cylindrical portion of the height, extending to the outer peripheral side from the lower end portion of the cylindrical portion, and a flange portion end face of the ring which the cylindrical portion is inserted into the inner circumferential side is placed more than And a method for performing heat treatment of the maraging steel thin plate member using a heat treatment jig provided with a plurality of ring holding members which can be laminated via the cylindrical portion, and a diameter which can avoid contact with each other. A plurality of rings comprising: a plurality of rings , each ring is placed on a collar-like portion of the ring holding member so that each ring is concentric, and the plurality of ring holding members on which the plurality of rings are placed are attached to the cylindrical portion. placing a heat treatment jig formed by laminating through the heat treatment furnace And performing heat treatment.
[0010]
According to the heat treatment method of the present invention, the ring holding member in a state where the ring is placed flat on the end surface on the bowl-like portion is laminated via the cylindrical portion, so that conventionally, one piece in the heating furnace. With respect to the area required for the heat treatment of the ring, heat treatment can be performed by accommodating a large number of rings in the vertical direction. In addition, at this time, since a plurality of rings having diameters capable of avoiding contact with each other are mounted on the bowl-shaped portion, they are conventionally required for heat treatment of one ring in the heating furnace. A large number of rings can be accommodated in the horizontal direction with respect to the area, and heat treatment can be performed. Accordingly, the heat treatment can be performed by effectively using the volume of the heating furnace.
[0011]
Further, the heat treatment method of the present invention is a cylindrical shape formed by welding the ends of maraging steel thin plates to the inner peripheral side of each ring holding member of the heat treatment jig placed in the heat treatment furnace . A space capable of accommodating a drum is formed, and the drum is accommodated in the space and placed in the heat treatment furnace to perform heat treatment.
[0012]
Since the ring is formed by rolling after cutting the drum, the diameter of the ring is larger than that of the drum, and the ring is inserted through the cylindrical portion inserted on the inner peripheral side of the ring. When the ring holding members are stacked, a space capable of accommodating the drum is formed inside the stacked cylindrical portions. Therefore, by accommodating the drum in the space and performing heat treatment simultaneously with the ring, the volume of the heating furnace can be used more effectively.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
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 production process of a maraging steel thin plate member used in the present embodiment, and FIG. 2 is an explanatory sectional view showing an aspect of a heat treatment jig used in the present embodiment.
[0014]
The heat treatment method of this embodiment is applied to the heat treatment of a thin plate member of maraging steel used for a laminated ring of a continuously variable transmission belt.
[0015]
The laminated ring is manufactured by the process shown in FIG. In the process shown in FIG. 1, first, a maraging steel thin plate 1 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 by the heat of welding, high hardness portions appear on both sides of the welded portion of the drum 2.
[0016]
Therefore, next, the drum 2 is accommodated in the vacuum furnace 3 and heated to perform the first solution treatment to remove the 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 the ring 4.
[0017]
The ring 4 formed as described above is then rolled. Since a rolled structure is formed in the vicinity of the surface of the rolled ring 4, the rolled ring 4 is accommodated in a heating furnace 5 and heated to form a second solution. As well as disappearing, uniform metal crystal grains are formed. After the solution ring 4 is cooled, the circumference is corrected to a predetermined circumference, and further subjected to aging treatment and nitriding treatment.
[0018]
Then, among the rings 4 subjected to nitriding treatment, a plurality of rings 4 having different circumferential lengths, for example, twelve rings 4 are laminated one on another to form a laminated ring (not shown). In the laminated ring, the adjacent rings 4 have a diameter difference of 0.4 mm or less, for example.
[0019]
The heat treatment method of the present embodiment relates to a first solution treatment for the drum 2 and a second solution treatment for the ring 4 after the rolling. In the present embodiment, the heat treatment is performed using the heat treatment jig 11 shown in FIG.
[0020]
As shown in FIG. 2, the heat treatment jig 11 is a lid that is stacked on the uppermost ring holding member 12 when a ring holding member 12 that holds the ring 4 and a plurality of ring holding members 12 are stacked. It consists of the member 13. Both the ring holding member 12 and the lid member 13 can be manufactured by punching a punching metal in which a large number of small holes are formed with a press.
[0021]
The ring holding member 12 includes a cylindrical portion 14 that is inserted on the inner peripheral side of the ring 4, and a flange-shaped portion 15 that extends from the lower end portion of the cylindrical portion 14 in the outer peripheral direction, and the upper end of the cylindrical portion 14. The portion is provided with a small-diameter portion 16 that is smaller in diameter than the cylindrical portion 14 and is fitted into and engaged with the lower end portion of the cylindrical portion 14 of the upper ring holding member 12. The lid member 13 is formed to have a size that covers the upper side of the ring 4 placed on the bowl-shaped portion 15 of the lower ring holding member 12, and the small diameter portion 16 of the lower ring holding member 12 is formed on the inner peripheral side. It has a hole 17 that is fitted and locked.
[0022]
The ring 4 is placed flat on the bowl-shaped portion 15 by one end face thereof, but in this embodiment, two rings 4 having diameters that can avoid contact with each other are placed concentrically. Here, twelve rings 4 having different circumferential lengths forming one laminated ring are sequentially directed from the ring 4 located on the innermost side toward the outer periphery in order # 1, # 2,. Then, the ring 4 is placed on the bowl-shaped portion 15 in combination such as # 1 and # 7, # 2 and # 8,..., # 6 and # 12.
[0023]
In this way, as described above, the rings 4 stacked adjacent to each other in the stacked ring have a diameter difference of 0.4 m or less, so that the ring arranged on the outer peripheral side on the bowl-shaped portion 15. 4 and the ring 4 disposed on the inner peripheral side have a diameter difference of about 2.0 mm and do not contact each other. Moreover, since the rings 4 and 4 placed concentrically as described above are expanded by the heat treatment at the same expansion rate, there is no possibility of contact after the heat treatment.
[0024]
The heat treatment jig 11 is formed by laminating a plurality of ring holding members 12 on which the ring 4 is placed on the bowl-shaped portion 15 as described above, and laminating the lid member 13 on the uppermost ring holding member 12. And accommodated in the heating furnace 5. At this time, the small-diameter portion 16 formed at the upper end portion of the cylindrical portion 14 of the lower ring holding member 12 is fitted into and engaged with the lower end portion of the cylindrical portion 14 of the upper ring holding member 12, or By being fitted and locked in the hole 17 of the lid member 13, the stacked state can be maintained stably and reliably.
[0025]
According to the method of the present embodiment, since two rings 4 are mounted on the hook-shaped portion 15 for each ring holding member 12, compared to the case where the rings 4 are mounted one by one, they have the same volume. In the case of a heating furnace, the number of rings 4 that can be accommodated at one time is doubled.
[0026]
The number of the rings 4 that can be placed on the bowl-shaped portion 15 of one ring holding member 12 is not limited to two, and it is possible to avoid the placed rings 4 from contacting each other. For example, a larger number of rings 4 may be placed on the bowl-shaped portion 15. For example, a set of # 1, # 4, # 7, # 10, # 2, # 5, # 8, # 11, # 3, # 6, # 9, # 12 each on the bowl-shaped portion 15 As an alternative, four rings 4 may be placed. In this case, the interval between the adjacent rings 4 on the bowl-shaped portion 15 is about 1.2 mm.
[0027]
The heating furnace 5 can also serve as heat treatment by the vacuum furnace 3 by adjusting the atmospheric conditions. When solution of the ring 4 is performed by the heating furnace 5, the drum 2 is accommodated in the space formed on the inner peripheral side of the cylindrical portions 14 stacked as described above, and the drum 2 is simultaneously formed with solution of the ring 4. Can be solutionized.
[0028]
In the above embodiment, the case where the drum 2 and the ring 4 are in solution is described as an example. However, the heat treatment method of the present invention can also be used for the aging / nitriding treatment of the ring 4. In this case, the ring 4 is placed on the upper surface of the bowl-shaped member 15 of the laminated ring holding member 12 in exactly the same manner as in the above embodiment, but the drum 2 is disposed on the inner peripheral side of the ring holding member 12. Do not place.
[Brief description of the drawings]
FIG. 1 is a process diagram schematically showing a manufacturing process of a member made of maraging steel sheet.
FIG. 2 is an explanatory cross-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, 12 ... ring holding member,
13 ... Lid member, 14 ... Cylindrical part, 15 ... Gutter-like part.

Claims (2)

A cylindrical portion inserted into the inner peripheral side of a ring formed by cutting a cylindrical drum formed by welding ends of thin sheets of maraging steel to a predetermined width and having a height exceeding the predetermined width; It is extended to the outer peripheral side from the lower end portion of the cylindrical portion, and a flange portion end face of the ring which the cylindrical portion is inserted into the inner circumferential side is placed, via the cylindrical portion A method of performing heat treatment of a thin plate member of maraging steel using a heat treatment jig comprising a plurality of ring holding members that can be laminated,
Combining a plurality of rings having diameters that can avoid contact with each other , placing each ring in a conical shape so that each ring is concentric, a plurality of ring holding members on which the plurality of rings are placed A heat treatment method characterized in that heat treatment is performed by placing a heat treatment jig formed by laminating a film through the cylindrical portion in a heat treatment furnace . On the inner peripheral side of each ring holding member of the heat treatment jig placed in the heat treatment furnace, a space is formed that can accommodate a cylindrical drum formed by welding the ends of the thin plates of maraging steel. The heat treatment method according to claim 1 , wherein the heat treatment is performed by housing the drum in the space and placing the drum in the heat treatment furnace .

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