JP2021037533A - Method for producing circular material - Google Patents

Abstract

To provide a method for producing a circular material, capable of preventing overlap defects from occurring.SOLUTION: A method for producing a circular material includes a first forging step and a second forging step. In the first forging step, a columnar stock is placed on a first female mold 10B while one end surface of the heated columnar stock is faced with the first female mold 10B. Thereafter, a first male mold 10A is moved down to pressurize the columnar stock with a processing surface 12A of the first male mold 10A and a processing surface 12B of the first female mold 10B, so that upper and lower rim parts 111A, 111B of the columnar stock are moved to an outside of the processing surfaces 12A, 12B of the first male mold 10A and the second male mold 10B, respectively, thereby forming an intermediate body 120, the rim part 111A of which is positioned on an upper end of the processing surface 12A and the rim part 111B of which is positioned on a lower end of the processing surface 12B. In the second forging step, an outer peripheral part 121 of the intermediate part 120 including the rim parts 111A and 111B is pressurized with a second male mold 20A and a second female mold 20B.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a method for producing a circular material.

Circular materials such as railroad wheels, gears, rings, etc. are manufactured, for example, as follows. First, the cylindrical material is heated. Next, forging is performed on the heated cylindrical material. After that, rolling, heat treatment, machining, etc. are carried out as necessary to manufacture a circular material having a predetermined outer shape and dimensions.

For example, Patent Document 1 discloses a method for manufacturing an idle gear, which is a kind of circular material. In this manufacturing method, the cylindrical material is first reduced by the upper mold and the lower mold. The machined surfaces of the upper and lower dies include a flat surface and a curved surface arranged in the outer peripheral region of the flat surface. The curved surface of the upper mold and the curved surface of the lower mold are separated from each other toward the outer side in the radial direction. The cylindrical material is deformed along the machined surfaces of the upper and lower dies, and the outer peripheral region becomes a thick-walled primary molded product. An idle gear is manufactured by further pressing the primary molded product with another mold and performing cutting or the like.

JP-A-2018-24012

By the way, in the production of a circular material, after heating the cylindrical material, the temperature of the cylindrical material drops to some extent before forging is started. The edge of the cylindrical material is more likely to be cooled than the other parts, and its deformation resistance is likely to be high. Therefore, for example, when the entire columnar material is pressed down on the machined surfaces of the upper and lower dies as in the manufacturing method of Patent Document 1, the edge of the columnar material may come into contact with the machined surface and be restrained by the machined surface. is there.

On the other hand, the portion of the cylindrical material other than the edge portion has a relatively high temperature and its deformation resistance is small, so that the portion flows outward in the radial direction. The flowed material also wraps around the edge constrained by the machined surface, but there may be a portion near the edge where the material is not filled. This portion remains as a dent on the end face of the finally manufactured circular material. Further, even if the fluid material wraps around the edge portion and is filled in the vicinity of the edge portion in a form that does not cause a dent, the end face of the finally manufactured circular material is constrained by the processed surface. Linear flaws can occur along the edges. Such dents and linear flaws are called fold flaws.

An object of the present disclosure is to provide a method for producing a circular material capable of suppressing the occurrence of fold defects.

The method for producing a circular material according to the present disclosure includes a first forging step and a second forging step. In the first forging step, one end surface of the heated cylindrical material is opposed to the first lower mold, and the cylindrical material is placed on the first lower mold. Then, by lowering the first upper mold and pressing the cylindrical material on the processed surface of the first upper mold and the processed surface of the first lower mold, the upper and lower edges of the cylindrical material are pressed on the first upper mold and the first lower mold. It is moved to the outside of the machined surface of the mold to form an intermediate whose edges are located at the upper and lower ends. In the second forging step, the outer peripheral portion of the intermediate body including the edge portion is pressed by the second upper die and the second lower die.

According to the method for producing a circular material according to the present disclosure, the occurrence of fold defects can be suppressed.

FIG. 1 is a one-sided vertical cross-sectional view of a press device used in the method for manufacturing a circular material according to the first embodiment. FIG. 2 is a diagram showing a state in which the cylindrical material is placed on the first lower mold in the first forging step. FIG. 3 is a diagram showing the start of reduction of the cylindrical material by the first upper die and the first lower die in the first forging step. FIG. 4 is a diagram showing a state in which the intermediate is formed in the first forging step. FIG. 5 is a diagram showing the start of reduction of the outer peripheral portion of the intermediate body by the second upper die and the second lower die in the second forging step. FIG. 6 is a diagram showing the end of the second forging step. FIG. 7 is a diagram showing immediately after the start of reduction of the cylindrical material by the general upper mold and lower mold. FIG. 8 is a diagram showing fold defects generated in a circular material manufactured by a general upper mold and lower mold. FIG. 9 is a diagram showing a state in which the intermediate is molded in the method for manufacturing a circular material according to the second embodiment. FIG. 10 is a diagram showing a state in which the outer peripheral portion of the intermediate shown in FIG. 9 is reduced to some extent. FIG. 11 is a diagram showing another example of the first forging step. FIG. 12 is a diagram showing another example of the second forging step.

The method for producing a circular material according to the embodiment includes a first forging step and a second forging step. In the first forging step, one end surface of the heated cylindrical material is opposed to the first lower mold, and the cylindrical material is placed on the first lower mold. Then, by lowering the first upper mold and pressing the cylindrical material on the processed surface of the first upper mold and the processed surface of the first lower mold, the upper and lower edges of the cylindrical material are pressed on the first upper mold and the first lower mold. It is moved to the outside of the machined surface of the mold to form an intermediate whose edges are located at the upper and lower ends. In the second forging step, the outer peripheral portion of the intermediate body including the edge portion is pressed by the second upper die and the second lower die (first configuration).

In the method for producing a circular material according to the first configuration, in the first forging step, an intermediate is formed by pressing the cylindrical material on the processed surface of the first upper mold and the processed surface of the first lower mold. When the cylindrical material is pressed down, the edges of the cylindrical material move to the outside of the machined surfaces of the first upper die and the first lower die, and are not constrained by the machined surfaces. In the second forging step following the first forging step, the outer peripheral portion of the intermediate including the edge portion is pressed by the second upper die and the second lower die. Since the edges are located at the upper and lower ends of the intermediate, they first come into contact with the second upper die and the second lower die and are crushed. As a result, the material is also filled in the vicinity of the edge portion, so that the circular material produced from the cylindrical material is less likely to have a dent. Moreover, since the edge portion itself is crushed, linear flaws are unlikely to occur in the circular material. Therefore, it is possible to suppress the occurrence of fold-in flaws.

In the first configuration, the cylindrical material preferably has a radius equal to or greater than the radius of the machined surfaces of the first upper die and the first lower die (second configuration).

When the radius of the cylindrical material is larger than the radius of the machined surface of the first upper mold and the first lower mold, the edge of the cylindrical material is positioned outside the machined surface when the cylindrical material is placed on the first lower mold. Be done. Therefore, the edge portion of the cylindrical material does not come into contact with the processed surfaces of the first upper die and the first lower die and is not restrained. When the radius of the cylindrical material is equal to the radius of the machined surface of the first upper mold and the first lower mold, when the cylindrical material is pressed down by the first upper mold and the first lower mold, the edge of the cylindrical material becomes the first upper mold. And, without being constrained by the machined surface of the first lower mold, it is immediately extruded to the outside of the machined surface. Therefore, according to the second configuration, it is possible to more reliably prevent the edge portion of the cylindrical material from being restrained by the processed surfaces of the first upper die and the first lower die.

In the first or second configuration, the second upper mold is arranged on the outer peripheral side of the first upper mold and surrounds the first upper mold, and the second lower mold is arranged on the outer peripheral side of the first lower mold. It is preferable to surround the first lower mold (third configuration).

According to the third configuration, since the second upper mold and the second lower mold are arranged so as to surround the first upper mold and the first lower mold, after forming the intermediate in the first forging step, the second upper mold and the second lower mold are arranged. The second forging step can be carried out in a state where the intermediate body is sandwiched between the upper die and the first lower die and held. That is, the outer peripheral portion of the intermediate can be stably reduced.

In the third configuration, the second forging step may be started after the first upper die reaches bottom dead center (fourth configuration).

As the first upper mold approaches the bottom dead center, the force with which the first upper mold holds the intermediate together with the first lower mold increases. According to the fourth configuration, the first upper mold reaches the bottom dead center, and the second forging process is started with the intermediate body firmly held by the first upper mold and the first lower mold. The outer peripheral portion of the body can be pressed down more stably.

In the third configuration, in the first forging step, the first upper die is stopped before reaching the bottom dead center to form an intermediate, and in the second forging step, the lowering of the first upper die is restarted. The first upper die and the second upper die may reach the bottom dead center at the same time (fifth configuration).

As the first upper die approaches the bottom dead center, the volume of the material extruded to the outside of the machined surfaces of the first upper die and the first lower die increases. The larger the volume of this material, the more difficult it is to form the outer peripheral portion of the intermediate into a desired shape. On the other hand, in the fifth configuration, the first upper mold is stopped before reaching the bottom dead center to form an intermediate, so that the first upper mold and the first lower mold are extruded to the outside of the machined surface. The volume of the material can be reduced. Therefore, the outer peripheral portion of the intermediate can be easily formed into a desired shape, that is, a shape in which the edge portions are located at the upper and lower ends. Therefore, in the second forging step, the leading reduction of the edge portion by the second upper die and the second lower die can be performed more reliably.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

<First Embodiment>
[Structure of press device 100]
In the method for manufacturing a circular material of the first embodiment, the circular material is manufactured by using the press device 100 shown in FIG. FIG. 1 is a one-sided vertical cross-sectional view of the press device 100. First, the configuration of the press device 100 will be described with reference to FIG. The press device 100 includes a first upper mold 10A, a first lower mold 10B, a second upper mold 20A, and a second lower mold 20B.

The first upper mold 10A is attached to the slide 30 via the holder 11. The first upper mold 10A has a machined surface 12A. The machined surface 12A is provided on the lower surface of the first upper mold 10A.

The first lower mold 10B is arranged below the first upper mold 10A. The first lower mold 10B is fixed to the bolster plate 40. The first lower mold 10B has a machined surface 12B. The machined surface 12B is provided on the upper surface of the first lower mold 10B. The machined surface 12B faces the machined surface 12A. Each of the machined surfaces 12A and 12B has a substantially circular shape and has a radius R1.

The second upper mold 20A is arranged on the outer peripheral side of the first upper mold 10A and surrounds the first upper mold 10A. The inner peripheral surface of the second upper mold 20A is in contact with or close to the outer peripheral surface of the first upper mold 10A. The second upper mold 20A is attached to the slide 30 via the expansion / contraction mechanism 21A. The expansion / contraction mechanism 21A is, for example, a hydraulic cylinder or an air cylinder. The second upper mold 20A has a machined surface 22A on the lower surface.

The second lower mold 20B is arranged below the second upper mold 20A. The second lower mold 20B is arranged on the outer peripheral side of the first lower mold 10B and surrounds the first lower mold 10B. The inner peripheral surface of the second lower mold 20B is in contact with or close to the outer peripheral surface of the first lower mold 10B. The second lower mold 20B is attached to the bolster plate 40 via a telescopic mechanism 21B different from the telescopic mechanism 21A. The expansion / contraction mechanism 21B is, for example, a hydraulic cylinder or an air cylinder. The second lower mold 20B has a machined surface 22B on the upper surface. The machined surface 22B faces the machined surface 22A. The machined surfaces 22A and 22B each have a substantially annular shape.

[Manufacturing method of circular material]
Next, a method of manufacturing a circular material using the press device 100 will be described with reference to FIGS. 2 to 6. The method for producing a circular material includes a first forging step and a second forging step.

(1st forging process)
With reference to FIG. 2, first, the cylindrical material 110 is prepared and heated in a known heating furnace. The cylindrical material 110 is heated to, for example, 1000 to 1200 ° C. In the first forging step, the cylindrical material 110 is placed on the first lower mold 10B with one end surface of the heated cylindrical material 110 facing the first lower mold 10B. The cylindrical material 110 is arranged on the machined surface 12B so that its central axis coincides with the center of the machined surface 12B of the first lower mold 10B.

The cylindrical material 110 has a radius R equal to or greater than the radius R1 of the processed surfaces 12A and 12B of the first upper die 10A and the first lower die 10B. In the first embodiment, the cylindrical material 110 has a radius R larger than the radius R1 of the machined surfaces 12A and 12B. Therefore, with the cylindrical material 110 placed on the first lower mold 10B, the edges 111A and 111B of the cylindrical material 110 are located outside the machined surfaces 12A and 12B. One end surface of the cylindrical material 110, that is, the outer peripheral edge portion of the lower surface is the edge portion 111B. The other end surface of the cylindrical material 110, that is, the outer peripheral edge portion of the upper surface is the edge portion 111A.

After placing the cylindrical material 110 on the first lower mold 10B, the slide 30 is lowered to lower the first upper mold 10A. As the slide 30 descends, the second upper mold 20A also descends. However, since the expansion / contraction mechanism 21A is in the contracted state, the machined surface 22A of the second upper die 20A is located above the machined surface 12A of the first upper die 10A. Therefore, as shown in FIG. 3, only the machined surface 12A of the first upper die 10A comes into contact with the upper surface of the cylindrical material 110. When the first upper die 10A is further lowered, the cylindrical material 110 is reduced by the machined surface 12A of the first upper die 10A and the machined surface 12B of the first lower die 10B.

The cylindrical material 110 is pressed from above and below by the machined surfaces 12A and 12B. The material of the pressed portion of the cylindrical material 110 flows outward in the radial direction, that is, toward the outside of the machined surfaces 12A and 12B. Since the outside of the machined surfaces 12A and 12B is not constrained by the machined surfaces 12A and 12B, the material of the cylindrical material 110 flows not only outside in the radial direction but also in the vertical direction. The flow of this material causes the edges 111A and 111B to move further outward of the machined surfaces 12A and 12B and also in the vertical direction.

When the first upper mold 10A reaches the bottom dead center, the slide 30 is stopped. As a result, the intermediate 120 shown in FIG. 4 is formed, and the first forging step is completed.

In the intermediate 120, the edges 111A and 111B are located at the upper and lower ends. The edge portions 111A and 111B are included in the outer peripheral portion 121 of the intermediate body 120. The outer peripheral portion 121 is a portion of the intermediate body 120 located outside the processed surfaces 12A and 12B of the first upper die 10A and the first lower die 10B. The outer peripheral portion 121 has a substantially horizontal fan shape in a vertical cross-sectional view. The edge portion 111A constitutes the upper end portion of the arc in the fan-shaped outer peripheral portion 121 in the vertical cross-sectional view. The edge portion 111B constitutes the lower end portion of the arc in the fan-shaped outer peripheral portion 121 in the vertical cross-sectional view. The wall thickness of the intermediate 120 is maximized at the positions of the edges 111A and 111B. That is, in the intermediate 120, the edges 111A and 111B project upward and downward, respectively, with respect to the other portions. The intermediate 120 has a wall thickness of t1 in the portions of the first upper mold 10A and the first lower mold 10B that are pressed by the processed surfaces 12A and 12B.

(Second forging process)
After the completion of the first forging step, the second forging step is carried out. In the second forging step, the outer peripheral portion 121 of the intermediate body 120 including the edge portions 111A and 111B is reduced by the second upper mold 20A and the second lower mold 20B. Specifically, the expansion / contraction mechanism 21A is extended and the second upper mold 20A is lowered while the slide 30 is stopped, that is, the first upper mold 10A is positioned at the bottom dead center. In addition, the expansion / contraction mechanism 21B is extended to raise the second lower mold 20B. As a result, as shown in FIG. 5, the machined surface 22A of the second upper die 20A comes into contact with the edge portion 111A, and the machined surface 22B of the second lower die 20B comes into contact with the edge portion 111B. The machined surfaces 22A and 22B preferably come into contact with the edges 111A and 111B at the same time.

When the second upper mold 20A is further lowered and the second lower mold 20B is further raised, the edge portions 111A and 111B are pressed down by the machined surfaces 22A and 22B. After crushing the edge portions 111A and 111B, the machined surfaces 22A and 22B press down the outer peripheral portions 121 other than the edge portions 111A and 111B.

With reference to FIG. 6, when the second upper die 20A reaches the bottom dead center and the second lower die 20B reaches the top dead center, the circular member 130 is completed. At this time, the distance between the machined surface 22A of the second upper mold 20A and the machined surface 22B of the second lower mold 20B is the distance between the machined surface 12A of the first upper mold 10A and the machined surface 12B of the first lower mold 10B. Match. That is, the circular member 130 has a wall thickness t1 as a whole. The circular material 130 may be a final product, but the circular material 130 may be further forged, rolled, heat-treated, machined, or the like to be a final product.

[effect]
When the circular material is manufactured by a general method, for example, as shown in FIG. 7, the entire cylindrical material 110 is pressed down on the processed surfaces 51A and 51B of the upper die 50A and the lower die 50B. In this case, the edges 111A and 111B of the cylindrical material 110 come into contact with the machined surfaces 51A and 51B from the start to the end of the reduction and are restrained. Further, the edge portions 111A and 111B have a lower temperature than the other portions of the cylindrical material 110 and have a high deformation resistance. Therefore, even if the material is pressed down on the machined surfaces 51A and 51B, the material hardly flows outward in the radial direction at the edges 111A and 111B and their vicinity. On the other hand, in the portion of the cylindrical material 110 other than the edges 111A and 111B, the material flows outward in the radial direction. This material wraps around the edges 111A and 111B constrained by the machined surfaces 51A and 51B (see arrows in FIG. 7). However, since the material does not easily flow in the edges 111A and 111B and their vicinity, some parts are not filled. As shown in FIG. 8, this portion remains as a fold defect (reference numeral X portion) on the surface of the circular member 140. Further, even if the material is filled in the vicinity of the edge portions 111A and 111B, the surface of the circular material 140 has a linear fold flaw (a linear fold defect) along the edge portions 111A and 111B constrained by the processed surfaces 51A and 51B. (Not shown) may occur. Such a fold-in defect may cause a large crack in the circular member 140. Therefore, it is necessary to remove the fold defects from the circular material 140 by machining.

On the other hand, in the method for manufacturing the circular material 130 of the first embodiment, the cylindrical material 110 is formed into the intermediate 120 in the first forging step, and the circular material 130 is manufactured from the intermediate 120 in the second forging step. In the first forging step, when the cylindrical material 110 is pressed down on the processed surfaces 12A and 12B of the first upper die 10A and the first lower die 10B, the edges 111A and 111B of the cylindrical material 110 are moved to the outside of the processed surfaces 12A and 12B. Moving. Therefore, the edge portions 111A and 111B do not come into contact with the machined surfaces 12A and 12B and are not restrained. In the subsequent second forging step, the outer peripheral portion 121 of the intermediate body 120 is pressed down by the machined surfaces 22A and 22B of the second upper die 20A and the second lower die 20B. Since the edge portions 111A and 111B are located at the upper and lower ends of the outer peripheral portion 121, they are pressed down and crushed by the machined surfaces 22A and 22B prior to the other portions. As a result, the material is filled in the vicinity of the edges 111A and 111B in the manner shown in FIGS. 7 and 8 without wrapping around. Therefore, it is possible to suppress the occurrence of fold-in flaws. As a result, machining for removing the fold defects becomes unnecessary, the manufacturing process of the circular material 130 can be simplified, and the manufacturing cost can be reduced.

In the method for manufacturing the circular member 130 of the first embodiment, the cylindrical material 110 has a radius R larger than the radius R1 of the processed surfaces 12A and 12B of the first upper die 10A and the first lower die 10B. Therefore, at the time when the cylindrical material 110 starts to be pressed down on the machined surfaces 12A and 12B of the first upper die 10A and the first lower die 10B, the edges 111A and 111B are already located outside the machined surfaces 12A and 12B. Therefore, the edge portions 111A and 111B can be surely made non-contact with the machined surfaces 12A and 12B, and the restraint of the edge portions 111A and 111B during the first forging step can be prevented. Therefore, it is possible to suppress the occurrence of fold-in flaws.

The radius R of the cylindrical material 110 may be the same as the radius R1 of the processed surfaces 12A and 12B of the first upper die 10A and the first lower die 10B. In this case, when the cylindrical material 110 is pressed down on the processed surfaces 12A and 12B of the first upper mold 10A and the first lower mold 10B, the edges 111A and 111B of the cylindrical material 110 are immediately extruded to the outside of the processed surfaces 12A and 12B. .. Therefore, the cylindrical material 110 can be pressed down without the edges 111A and 111B being constrained by the machined surfaces 12A and 12B of the first upper die 10A and the first lower die 10B. Therefore, it is possible to suppress the occurrence of fold-in flaws.

However, the radius R of the cylindrical material 110 may be slightly smaller than the radius R1 of the processed surfaces 12A and 12B of the first upper die 10A and the first lower die 10B. In this case, at the start of reduction by the machined surfaces 12A and 12B, the edge portions 111A and 111B come into contact with the machined surfaces 12A and 12B. However, the material of the cylindrical material 110 flows outward in the radial direction due to the reduction, so that the edges 111A and 111B are immediately extruded to the outside of the machined surfaces 12A and 12B. Therefore, even in this case, the edge portions 111A and 111B are not restrained by the machined surfaces 12A and 12B, and the occurrence of fold flaws can be suppressed.

The ratio R / R1 of the radius R of the cylindrical material 110 to the radius R1 of the processed surfaces 12A and 12B of the first upper die 10A and the first lower die 10B is preferably 0.8 or more and 1.5 or less. .. More preferably, the lower limit of the ratio R / R1 is 0.9 and the upper limit is 1.2.

In the method for manufacturing the circular material 130 of the first embodiment, the circular material 130 is manufactured by using the press device 100 in which the first upper mold 10A moves up and down independently of the second upper mold 20A and the second lower mold 20B. .. That is, the circular material 130 is manufactured by so-called composite processing, and the first forging step and the second forging step are continuously carried out by using one press device 100. In the second forging step, the outer peripheral portion 121 can be pressed down by the second upper die 20A and the second lower die 20B while the intermediate body 120 is held by the first upper die 10A and the first lower die 10B. As a result, the outer peripheral portion 121 of the intermediate body 120 can be stably pressed down, and the circular member 130 having a desired shape can be easily formed.

The holding force of the first upper mold 10A and the first lower mold 10B increases as the reduction by the first upper mold 10A and the first lower mold 10B progresses. In the method for manufacturing the circular material 130 of the first embodiment, the second forging step is carried out after the first upper die 10A reaches the bottom dead center. That is, since the second forging step is started in a state where the holding force of the first upper die 10A and the first lower die 10B is sufficiently high, the outer peripheral portion 121 of the intermediate body 120 can be stably reduced.

<Second Embodiment>
Subsequently, a method for manufacturing the circular member 130 of the second embodiment will be described with reference to FIGS. 9 and 10. In the method for manufacturing the circular material 130 of the second embodiment, the circular material 130 is manufactured by using the same press device 100 as that of the first embodiment.

In the first forging step, as shown in FIG. 9, the lowering of the slide 30 is controlled, and the first upper die 10A is stopped before reaching the bottom dead center to form the intermediate body 150. Specifically, after the heated cylindrical material 110 is placed on the first lower mold 10B, the slide 30 is lowered, and the cylindrical material 110 is placed on the machined surfaces 12A of the first upper mold 10A and the first lower mold 10B. It is reduced at 12B. However, before the first upper die 10A reaches the bottom dead center, the descent of the slide 30 is stopped, and the descent of the first upper die 10A is stopped. As a result, the material flows outward to some extent in the radial direction, the intermediate 150 is formed, and the first forging step is completed.

The intermediate body 150 has a wall thickness t2 at the portions pressed by the processed surfaces 12A and 12B of the first upper mold 10A and the first lower mold 10B. The wall thickness t2 is thicker than the wall thickness t1 of the intermediate 120 in the first embodiment (FIG. 4). In the intermediate body 150, the portion located outside the processed surfaces 12A and 12B is the outer peripheral portion 151. The outer peripheral portion 151 includes edge portions 111A and 111B. The edges 111A and 111B are located at the upper and lower ends of the intermediate 150.

In the second forging step following the first forging step, first, the edge portions 111A and 111B of the intermediate body 150 are pressed down by the machined surfaces 22A and 22B of the second upper die 20A and the second lower die 20B. Specifically, while the slide 30 is stopped, the expansion / contraction mechanism 21A is extended, and as shown in FIG. 10, the processing surface 22A of the second upper mold 20A is the same height as the processing surface 12A of the first upper mold 10A. Lower it to the position where it will be. Further, the expansion / contraction mechanism 21B is extended, and the second lower mold 20B is raised to a position where the machined surface 22B is at the same height as the machined surface 12B of the first lower mold 10B. It is preferable that the second upper mold 20A and the second lower mold 20B simultaneously descend and ascend at the same speed.

As a result, the distance between the machined surface 22A of the second upper mold 20A and the machined surface 22B of the second lower mold 20B becomes the distance between the machined surface 12A of the first upper mold 10A and the machined surface 12B of the first lower mold 10B. Match. After the intervals between the upper and lower molds 10A, 10B, 20A, and 20B match, the expansion and contraction mechanisms 21A and 21B are stopped from extending, and the lower and lower molds 20A and the second lower mold 20B are stopped from descending and ascending. As a result, the outer peripheral portion 151 of the intermediate body 150 is reduced to some extent.

Next, the descent of the first upper die 10A is restarted, and the first upper die 10A and the second upper die 20A reach the bottom dead center at the same time. Specifically, while the second lower mold 20B is stopped, the lowering of the slide 30 is restarted, and the first upper mold 10A and the second upper mold 20A are lowered again. As a result, the outer peripheral portion 151 is further reduced by the processed surfaces 22A and 22B of the second upper mold 20A and the second lower mold 20B, and the outer peripheral portion 151 is further reduced by the processed surfaces 12A and 12B of the first upper mold 10A and the first lower mold 10B. The parts other than the above are further reduced. When the first upper mold 10A and the second upper mold 20A reach the bottom dead center, the circular member 130 is completed.

According to the method for manufacturing the circular material 130 of the second embodiment, in the first forging step, the first upper die 10A and the first lower die 10B are stopped in order to stop the first upper die 10A before reaching the bottom dead center. The volume of the material extruded to the outside of the machined surfaces 12A and 12B is reduced. As a result, the volume of the outer peripheral portion 151 of the intermediate body 150 can be reduced, and the edges 111A and 111B can be easily formed into a shape located at the upper end and the lower end. Therefore, in the second forging step, the edge portions 111A and 111B can be reliably pre-pressed on the machined surfaces 22A and 22B of the second upper die 20A and the second lower die 20B. Therefore, it is possible to suppress the occurrence of fold-in flaws.

The method for producing the circular material of the present embodiment has been described above. In addition, the present disclosure is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present disclosure.

In each of the above embodiments, the second upper die 20A and the second lower die 20B manufacture the circular member 130 by the press device 100 arranged on the outer peripheral side of the first upper die 10A and the first lower die 10B. However, the method for producing the circular material 130 of the present disclosure is not limited to this. For example, as shown in FIG. 11, in the first forging step, even if the cylindrical material 110 is pressed down by the press device 200 to which only the first upper die 10A and the first lower die 10B are attached to form the intermediate 120. Good. In this case, in the second forging step, as shown in FIG. 12, the intermediate 120 is pressed by the press device 300 to which the second upper die 60A and the second lower die 60B, in which the shape of the entire circular member 130 is molded, are attached. It is reduced to produce a circular material 130.

Even in such a method for manufacturing the circular material 130, in the first forging step, the edges 111A and 111B of the cylindrical material 110 are placed on the outside of the processed surfaces 12A and 12B of the first upper die 10A and the first lower die 10B. It can be moved and positioned at the upper and lower ends of the intermediate 120. In the second forging step, the edges 111A and 111B of the intermediate 120 can be reduced in advance of the other portions on the processed surfaces 61A and 61B of the second upper die 60A and the second lower die 60B. Therefore, it is possible to suppress the occurrence of fold-in flaws.

In the press device 200 shown in FIG. 11, the first upper die 10A and the first lower die 10B have a substantially cylindrical shape. However, the first upper mold 10A and the first lower mold 10B may have a substantially truncated cone shape. For example, the first upper die 10A and the first lower die 10B may include tapered surfaces (not shown) arranged on the outer peripheral side of the machined surfaces 12A and 12B, respectively. This tapered surface is provided so as not to come into contact with the edge portions 111A, 111B that have moved to the outside of the machined surfaces 12A, 12B due to the reduction of the machined surfaces 12A, 12B.

In each of the above embodiments, the processed surfaces 12A and 12B of the first upper die 10A and the first lower die 10B are substantially flat. However, the machined surfaces 12A and 12B do not have to be flat. For example, the processed surfaces 12A and 12B may each have a shape corresponding to the circular member 130. However, the outer peripheral edges of the machined surfaces 12A and 12B have a substantially circular shape. In this case, the radius R1 of the machined surfaces 12A and 12B is the horizontal distance from the central axis of the first upper die 10A and the first lower die 10B to the outer peripheral edge of the machined surfaces 12A and 12B.

10A: First upper mold 12A: Machined surface 10B: First lower mold 12B: Machined surface R1: Radius 20A: Second upper mold 20B: Second lower mold 110: Cylindrical material 111A, 111B: Edge R: Radius 120, 150: Intermediate 121, 151: Outer circumference 130: Circular material

Claims (5)

It is a manufacturing method of circular materials.
One end surface of the heated cylindrical material is opposed to the first lower mold, the cylindrical material is placed on the first lower mold, the first upper mold is lowered, and the cylindrical material is placed on the first upper mold. By pressing on the machined surface and the machined surface of the first lower die, the upper and lower edges of the cylindrical material are moved to the outside of the machined surface of the first upper die and the first lower die, and the edge portion is moved. The first forging step of forming the intermediates located at the upper and lower ends of
A method for producing a circular material, comprising a second forging step of pressing the outer peripheral portion of the intermediate including the edge portion with a second upper die and a second lower die. The method for producing a circular material according to claim 1.
A method for producing a circular material, wherein the cylindrical material has a radius equal to or greater than the radius of the processed surface of the first upper mold and the first lower mold. The method for producing a circular material according to claim 1 or 2.
The second upper mold is arranged on the outer peripheral side of the first upper mold and surrounds the first upper mold.
A method for manufacturing a circular material, wherein the second lower mold is arranged on the outer peripheral side of the first lower mold and surrounds the first lower mold. The method for manufacturing a circular material according to claim 3.
The second forging step is a method for producing a circular material, which is started after the first upper die reaches bottom dead center. The method for manufacturing a circular material according to claim 3.
In the first forging step, the first upper die is stopped before reaching bottom dead center to form the intermediate.
In the second forging step, a method for producing a circular material, in which the lowering of the first upper die is restarted and the first upper die and the second upper die reach the bottom dead center at the same time.

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