JP2019155477A - Method for manufacturing circular material - Google Patents

Abstract

To provide a method for manufacturing a circular material by which underfill can be suppressed, and yield reduction can be suppressed.SOLUTION: A method for manufacturing a circular material is a method for manufacturing a circular material from a cylindrical material 5 which includes a center part 6 and an edge part 7 including an outer peripheral surface 9. The method for manufacturing the circular material comprises the steps of: rolling down the center part 6 of the cylindrical material 5 and deforming the cylindrical material 5 in a radial direction; restricting radial deformation of the cylindrical material 5 which is deformed in the radial direction; rolling down the center part 6 of the cylindrical material 5 and rolling down the edge part 7 of the cylindrical material 5 at a rolling reduction speed slower than a rolling reduction speed of the center part 6 after the step of restricting radial deformation of the cylindrical material 5; and rolling down the center part 6 and the edge part 7 of the cylindrical material 5 at the same rolling reduction speed after the step of rolling down the edge part 7.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method for manufacturing a circular material.

  For example, circular materials represented by railway wheels, gears and rings are manufactured as follows.

  First, a cylindrical material (billet) is heated. An intermediate product (forged wasteland) is manufactured by performing wasteland forming processing on the heated cylindrical material. In the rough ground forming process, forging is performed once or a plurality of times. A circular material is manufactured by performing finish rolling, finish forging, and the like on the forged wasteland. If necessary, heat treatment and machining are performed on the circular material after finish forging.

  In such a circular material, the cross-sectional shape along the central axis of the circular material is often H-shaped. In the case of upsetting forging a circular material having an H-shaped cross section, it is necessary to greatly deform the cylindrical material, so that the material does not flow to every corner of the mold, and the forging waste may be thin. If the volume of the columnar material is increased in order to suppress the forging wasteland thinning, a large amount of burrs are generated after the wasteland forming process, and the yield decreases.

  For example, Japanese Utility Model Laid-Open No. 50-117137 (Patent Document 1) discloses a method for suppressing the lack of a forged product. A method for suppressing the yield reduction of a forged product is disclosed in, for example, Japanese Utility Model Publication No. 7-44350 (Patent Document 2).

  In Patent Document 1, upset forging is performed using a die including an upper die, a lower die, and a guide ring. The guide ring surrounds the cylindrical material and is attached to the lower mold via a coil spring. When the upper die rolls down the cylindrical material, the cylindrical material is deformed in the radial direction. A cylindrical material deformed in the radial direction hits the guide ring. The guide ring then reaches the bottom dead center with the upper die. At this time, since the columnar material is in contact with the guide ring, when the guide ring is lowered, the region in contact with the guide ring of the columnar material is also lowered due to friction. Thereby, it is described in Patent Document 1 that the lack of a corner region formed by the lower mold and the guide ring is suppressed.

  In Patent Document 2, upset forging is performed using an upper die including an inner punch and an outer punch, and a lower die. The outer punch surrounds a circular material and is attached to the inner punch via a disc spring. When forging starts, the outer punch first hits the lower die, and the cylindrical material is confined in a sealed space formed by the upper die and the lower die. In this state, the inner punch reduces the cylindrical material. When the cylindrical material is deformed, the internal pressure of the sealed space increases. When the internal pressure exceeds a predetermined value, the outer punch rises due to the pressure, and the sealed state of the cylindrical material is released. Therefore, the cylindrical material is forged while forming burrs. As a result, Patent Document 2 describes that since no burrs are formed at the initial stage of molding, unnecessary burrs are suppressed and the yield is improved, and burrs are formed at the final stage of molding so that the lack of thickness can be suppressed.

Japanese Utility Model Publication No. 50-117137 No. 7-44350

  However, in the method of Patent Document 1, even if the lack of a corner region (corner region formed by the lower die and the guide ring) of the forged product having an H-shaped cross section can be suppressed, the other corner region (upper region) It is difficult to suppress the lack of thickness in the corner area formed by the mold and the guide ring. Similarly, in the method of Patent Document 2, it is difficult to suppress the lack of the corner region formed by the inner punch and the outer punch, that is, the corner region above the mold.

  The objective of this invention is providing the manufacturing method of the circular material which can suppress a thinning and can suppress the fall of a yield.

  The manufacturing method of the circular material of this embodiment is a method of manufacturing a circular material from the cylindrical raw material containing a center part and the edge which has an outer peripheral surface. The method of manufacturing a circular material includes a step of rolling down a central portion of a cylindrical material and deforming the cylindrical material in a radial direction, a step of restraining radial deformation of the cylindrical material that is deformed in the radial direction, After the step of constraining the deformation in the radial direction, after the step of rolling down the edge of the columnar material with a reduction speed lower than the reduction speed of the center, and the step of rolling down the edge And a step of rolling down the central portion and the edge portion of the cylindrical material at the same rolling speed.

  According to the manufacturing method of the circular material of this embodiment, a lack of thickness can be suppressed and a decrease in yield can be suppressed.

FIG. 1 is a cross-sectional view of a circular material forging device according to a first embodiment. FIG. 2 is a cross-sectional view showing the central part reduction process of the first embodiment. FIG. 3 is a cross-sectional view showing the restraining process of the first embodiment. FIG. 4 is a cross-sectional view showing forging by a general manufacturing method. FIG. 5 is a cross-sectional view showing the initial stage of the different speed reduction process of the first embodiment. FIG. 6 is a cross-sectional view showing the final stage of the different speed reduction process of the first embodiment. FIG. 7 is a cross-sectional view showing the same speed reduction process of the first embodiment. FIG. 8 is a cross-sectional view showing the boundary between the first upper die and the second upper die in the forging device of the first embodiment. FIG. 9 is a cross-sectional view showing a boundary between the first upper mold and the second upper mold different from FIG. FIG. 10 is a cross-sectional view of the forging device according to the second embodiment. FIG. 11 is a cross-sectional view showing a state after the restraining step in the manufacturing method of the second embodiment. FIG. 12 is a cross-sectional view showing a pressurizing step in the manufacturing method of the second embodiment. FIG. 13 is a cross-sectional view illustrating a state where the first upper mold and the second upper mold have reached bottom dead center in the manufacturing method of the second embodiment.

  (1) The manufacturing method of the circular material of this embodiment is a method of manufacturing a circular material from the cylindrical raw material containing a center part and the edge part which has an outer peripheral surface. The method of manufacturing a circular material includes a step of rolling down a central portion of a cylindrical material and deforming the cylindrical material in a radial direction, a step of restraining radial deformation of the cylindrical material that is deformed in the radial direction, After the step of constraining the deformation in the radial direction, the step of further reducing the center part of the cylindrical material, and the step of reducing the edge of the cylindrical material at a reduction speed lower than the reduction speed of the central part, and the step of reducing the edge part And a step of rolling down the central portion and the edge portion of the cylindrical material at the same rolling speed.

  In upsetting forging of a circular material having an H-shaped cross section, it is often difficult to fill the mold with the material. In particular, the molding of the region above the end (edge) in the radial direction of the H-shaped cross section is difficult because it is necessary to cause the material to flow against the rolling direction of the upper mold. In this regard, in the manufacturing method of the present embodiment, in the upsetting forging (raw ground forming process) of the cylindrical material, the rolling speed of the edge of the cylindrical material is slower than the rolling speed of the central portion. Therefore, the edge is pushed upward relative to the center. As a result, a forged rough ground in which the lack of the region above the edge is suppressed is obtained, and hence the lack of the circular material subjected to the subsequent finish rolling or the like is also suppressed. Moreover, in order to suppress the lack of thickness above the edge, in general upset forging, it is usually necessary to increase the volume of the columnar material. However, according to the manufacturing method of the present embodiment, the lack of thickness in the region above the edge is suppressed, so the volume of the columnar material does not need to be increased. That is, a decrease in yield is suppressed.

  (2) The manufacturing method of the above (1) further includes a first upper mold and a side wall portion facing the outer peripheral surface of the cylindrical material, and is disposed on the outer side in the radial direction of the cylindrical material than the first upper mold, A step of disposing a columnar material in a forging device including a second upper die that is slidable in the down direction relative to the upper die, and a lower die that opposes the first upper die and the second upper die. preferable. In this case, in the step of deforming the cylindrical material in the radial direction, the first upper mold presses down the central portion of the cylindrical material. In the step of restraining the radial deformation of the columnar material, the side wall portion of the second upper mold is in contact with the outer peripheral surface of the columnar material, and the radial deformation of the columnar material is constrained. In the step of rolling down the center portion of the cylindrical material and rolling down the edge of the cylindrical material at a rolling speed slower than the rolling speed of the central portion, the second upper mold has a lowering speed slower than the lowering speed of the first upper mold. Squeezes the edge of the cylinder material.

  The manufacturing method of this embodiment uses a divided upper mold. Thereby, it becomes possible to make the rolling-down speed of an edge part slower than the rolling-down speed of a center part.

  (3) In the manufacturing method of the above (2), in the step of reducing the central portion and the edge portion of the cylindrical material at the same reduction speed, it is preferable that the first upper die reaches the bottom dead center at the same time as the second upper die. .

  If the first upper mold first reaches the bottom dead center, a gap is created between the second upper mold and the lower mold when the first upper mold reaches the bottom dead center. Therefore, the material flows out from the gap between the second upper mold and the lower mold, and excessive burrs are generated, which may reduce the yield. If the second upper mold first reaches the bottom dead center, after the second upper mold reaches the bottom dead center, the edge of the columnar material is not rolled down. Therefore, it is difficult for the material to flow at the edge of the columnar material, and a lack of thickness may occur at the edge. On the other hand, if the first upper mold reaches the bottom dead center at the same time as the second upper mold, it is easy to maintain a balance between the filling of the material into the edge of the cylindrical material and the suppression of the yield reduction.

  (4) It is preferable that the manufacturing method of (1) to (3) further includes a step of pressing the edge of the columnar material in the direction opposite to the reduction direction after the step of deforming the columnar material in the radial direction.

  According to such a manufacturing method, after the cylindrical material is deformed in the radial direction, the downward flow of the material at the edge of the cylindrical material is limited. Thereby, the material of the columnar material which was going to flow downward becomes easy to flow upward, and the lack of the region above the edge is further suppressed.

  (5) In the manufacturing method of (2) or (3), further comprising a step of pressing the edge of the columnar material in a direction opposite to the reduction direction after the step of deforming the columnar material in the radial direction, The mold includes a first lower mold and a second lower mold that is disposed on the outer side in the radial direction of the cylindrical material than the first lower mold and is attached to the first lower mold via an elastic member, In the step of pressurizing the edge portion in the direction opposite to the rolling-down direction, it is preferable that the second lower mold pressurizes the edge portion of the cylindrical material.

  According to such a manufacturing method, the lower mold is divided, and it is possible to prevent the material of the edge from flowing downward by the second lower mold that is in contact with the edge of the cylindrical material, and in the region above the edge. The lack of meat is suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated. First, the forging apparatus used for the manufacturing method of the circular material of 1st Embodiment is demonstrated. In addition, the forging apparatus of 1st Embodiment is used in the wasteland forming process which manufactures a forge wasteland.

[First Embodiment]
[Forging device 1]
FIG. 1 is a cross-sectional view of a forging device 1 according to the first embodiment. Since the forging device has an axisymmetric shape, FIG. 1 shows a one-side cross section along the central axis of the columnar material 5. Referring to FIG. 1, forging device 1 includes a first upper die 2, a second upper die 3, and a lower die 4. The forging device 1 performs upset forging on a cylindrical material.

  The first upper mold 2 faces the central portion 6 of the columnar material 5. The central part of the columnar material 5 means a region having a predetermined radius from the central axis of the columnar material 5, and does not include the edge 7 and the outer peripheral surface 9 of the columnar material 5. The first upper die 2 has a shape corresponding to the central portion of the forged waste land after molding. The first upper mold 2 is attached to a bolster plate (not shown).

  The second upper mold 3 is arranged outside the first upper mold 2 in the radial direction of the columnar material 5. The second upper mold 3 has a shape corresponding to the edge of the forged waste land after molding. The edge part of a forged wasteland means the area | region of the radial direction outer side than the center part of a forged wasteland, and an outer peripheral surface is included. Further, the edge of the forged wasteland is a region corresponding to the edge 7 and the outer peripheral surface 9 of the columnar material 5.

  The second upper mold 3 is suspended from the first upper mold 2. That is, the second upper mold 3 is not attached to the first upper mold 2 via an elastic member such as a spring, and only the own weight is applied to the second upper mold 3. The second upper mold 3 is freely slidable by a predetermined distance in the reduction direction with respect to the first upper mold 2. For example, the second upper mold 3 can be slid by providing a key groove in the first upper mold 2 and the second upper mold 3. The forging device 1 is provided with a stopper (not shown) that restricts sliding of the second upper die 3. The second upper mold 3 includes a side wall portion 8 that faces the outer peripheral surface 9 of the columnar material 5. In addition, that the side wall part 8 opposes the outer peripheral surface 9 means that the side wall part 8 opposes the outer peripheral surface 9 during upset forging.

  The forging device 1 includes a ram (not shown). The ram can move the bolster plate in the downward direction. That is, the ram can raise or lower the first upper mold 2 and the second upper mold 3. With this configuration, as described later, after the columnar material 5 comes into contact with the side wall portion 8 of the second upper mold 3, when the first upper mold 2 descends, the second upper mold 3 becomes the first upper mold. Relative to 2

  The lower mold 4 faces the first upper mold 2 and the second upper mold 3. The lower die 4 has a shape corresponding to the central portion and the edge portion of the forged waste land after forming.

[Production method]
Then, the manufacturing method of the circular material of 1st Embodiment is demonstrated. The manufacturing method of the circular material of a 1st embodiment includes a central part reduction process, a restraint process, a different speed reduction process, and a same speed reduction process. In the manufacturing method of the circular material of 1st Embodiment, the forging apparatus 1 of 1st Embodiment mentioned above is used.

  With reference to FIG. 1, first, a cylindrical material 5 is prepared. The material of the column material 5 is, for example, steel. The size of the columnar material 5 is not particularly limited. The size of the columnar material 5 is appropriately set according to the size of the forged wasteland (or circular material) to be manufactured.

  Next, the cylindrical material 5 is heated in a heating furnace. The heating furnace is, for example, a gas atmosphere heating furnace or an induction heater. The heating temperature of the columnar material 5 is not particularly limited. The heating temperature is appropriately set depending on the material of the column material 5, the processing amount, and the like.

  Subsequently, the heated columnar material 5 is placed in the lower mold 4 of the forging device 1 as shown in FIG. And a central part reduction process is implemented. Before the central part reduction step is performed, the cylindrical material 5 may be pre-formed (first wasteland forming process). Thereby, the volume of the cylindrical raw material 5 is distributed appropriately, and the fall of a yield is suppressed.

[Center part reduction process]
FIG. 2 is a cross-sectional view showing the central part reduction process of the first embodiment. Referring to FIG. 2, the ram lowers the bolster plate in the central reduction step. As a result, the first upper mold 2 and the second upper mold 3 suspended from the first upper mold 2 are lowered. In the central part reduction step, the first upper mold 2 reduces the central part 6 of the cylindrical material 5, and the second upper mold 3 does not reduce the cylindrical material 5. When the central portion 6 of the cylindrical material 5 is crushed, the cylindrical material 5 is deformed toward the outside in the radial direction.

[Restriction process]
FIG. 3 is a cross-sectional view showing the restraining process of the first embodiment. Referring to FIG. 3, even in the restraining step, the reduction of the central portion 6 of the cylindrical material by the first upper mold 2 is continued. On the outer side in the radial direction of the columnar material 5 that is deformed by the reduction of the central portion 6, there is a side wall portion 8 of the second upper die 3 that is lowered together with the first upper die 2. Therefore, when the reduction of the central portion 6 by the first upper mold 2 proceeds, the outer peripheral surface 9 of the deformed columnar material 5 hits the side wall portion 8 of the second upper mold 3. Thereby, the deformation | transformation of the radial direction of the cylindrical raw material 5 is restrained.

  FIG. 4 is a cross-sectional view showing forging by a general manufacturing method. Referring to FIG. 4, there is one upper die 100 in general forging. In this case, when the columnar material 5 is deformed radially outward and the edge 7 hits the side wall 102 of the upper mold 100, the edge 7 is dragged downward (lower mold 101 side) by the side wall 102. Therefore, the corner region A1 above the edge portion 7 (on the upper mold 100 side) is difficult to be filled with the material, and the manufactured circular material is likely to be thin.

  On the other hand, in the manufacturing method of the first embodiment, the edge 7 of the columnar material 5 is prevented from being dragged downward in the different speed reduction process as described below. Hereinafter, this point will be described in detail.

[Different speed reduction process]
FIG. 5 is a cross-sectional view showing the initial stage of the different speed reduction process of the first embodiment. Referring to FIG. 5, after restraining the radial deformation of the cylindrical material 5 in the restraining step, the first upper mold 2 further reduces the central portion 6 of the cylindrical material 5. As a result, the columnar material 5 tends to deform in the radial direction, but the deformation of the columnar material 5 in the radial direction is constrained by the side wall portion 8. As described above, the second upper mold 3 is suspended from the first upper mold 2. Furthermore, since the side wall 8 of the second upper mold 3 has a draft, it is slightly inclined. Therefore, the second upper mold 3 rises relative to the first upper mold 2 by the force applied to the side wall portion 8 by the columnar material 5 that deforms in the radial direction. Accordingly, the lowering speed of the second upper mold 3 is slower than the lowering speed of the first upper mold 2. In other words, the rolling speed of the edge portion 7 of the cylindrical material is slower than the rolling speed of the central portion 6. In the present specification, “reducing” means that the shape of the cylindrical material changes depending on the mold. Therefore, since the shape of the edge 7 of the columnar material 5 changes due to the rise (slide) of the second upper die 3 with respect to the first upper die 2, this change in shape is also included in the reduction.

  Due to the rise of the second upper mold 3 relative to the first upper mold 2, the material that has flowed to the edge portion 7 also rises relative to the first upper mold 2. As a result, the corner area A1 formed by the first upper mold 2 and the second upper mold 3 can be easily filled with the material, and the area above the edge of the circular material that is the product (the first upper mold 2 and the second upper mold 2). Insufficient wall thickness in the corner region A1 formed by the mold 3 is suppressed. Such a manufacturing method of the first embodiment is particularly effective when the volume of the region above the edge of the circular material having the H-shaped cross section is larger than the volume of the region below the edge.

  FIG. 6 is a cross-sectional view showing the final stage of the different speed reduction process of the first embodiment. With reference to FIG. 6, as described above, the rise of the second upper mold 3 relative to the first upper mold 2 ends at a predetermined distance. The predetermined distance is appropriately set depending on the shape of the circular material to be manufactured. When the rise of the second upper mold 3 relative to the first upper mold 2 is finished, the different speed reduction process is finished.

[Same speed reduction process]
FIG. 7 is a cross-sectional view showing the same speed reduction process of the first embodiment. Referring to FIG. 7, the same speed reduction process is performed after the different speed reduction process. After the rise of the second upper mold 3 relative to the first upper mold 2 is completed, the bolster plate is further lowered. In this case, since the second upper mold 3 does not slide relative to the first upper mold 2, the second upper mold 3 is lowered integrally with the first upper mold 2. That is, in the same speed reduction process, the reduction speed of the first upper mold 2 with respect to the cylindrical material 5 is the same as the reduction speed of the second upper mold 3. That is, the central portion 6 of the columnar material 5 is crushed by the first upper mold 2, and the edge portion 7 of the columnar material 5 is crushed by the second upper mold 3 at the same rolling speed as the central portion 6. Thereafter, the first upper mold 2 and the second upper mold 3 reach the bottom dead center. When the first upper mold 2 and the second upper mold 3 reach the bottom dead center, a forged wasteland is obtained.

  In the same speed reduction process, the material pushed out by the reduction of the first upper mold 2 and settled on the edge portion 7 is reduced by the second upper mold 3 toward the lower side of the edge portion 7. Thereby, it becomes easy to fill material also in area | region A2 below the edge part of the forge wasteland which has an H-shaped cross section.

  The manufactured forged waste land is subjected to a well-known finishing process to obtain a circular material (product). For example, finish rolling is performed on the forged rough ground using a rolling mill. After finish rolling, finish forging is performed to produce a circular material.

  Here, in the same speed reduction process, it is preferable that the first upper mold 2 reaches the bottom dead center simultaneously with the second upper mold 3. If the first upper mold 2 reaches the bottom dead center first, a gap is formed between the second upper mold 3 and the lower mold 4 when the first upper mold 2 reaches the bottom dead center. After the first upper mold 2 reaches the bottom dead center, the central portion 6 of the columnar material 5 is not crushed. Therefore, the material is not extruded toward the edge portion 7 by the first upper mold 2. For this reason, there may be a lack of thickness at the edge. Moreover, when the size of the columnar material 5 is sufficiently large, the material may flow out from the gap between the second upper mold 3 and the lower mold 4, which may cause excessive burrs. Therefore, the yield may be reduced. On the other hand, if the second upper mold 3 reaches the bottom dead center first, after the second upper mold 3 reaches the bottom dead center, the edge 7 of the columnar material 5 is not rolled down. Therefore, it is difficult to fill the edge portion 7 with the material, which may cause a lack of thickness. If the first upper mold 2 reaches the bottom dead center at the same time as the second upper mold 3, it is easy to maintain a balance between the filling of the material of the columnar material and the suppression of the yield reduction.

  FIG. 8 is a cross-sectional view showing the boundary between the first upper die and the second upper die in the forging device of the first embodiment. Referring to FIG. 8, the boundary between the first upper mold 2 and the second upper mold 3, that is, the division position of the upper mold is a position that coincides with the boundary between the central portion 6 and the edge portion 7 of the columnar material 5. Preferably there is. A corner 10 on the radially outer side of the corner region formed by the first upper mold 2 and the second upper mold 3 exists on an extension line in the flow direction of the material. However, the radially inner corner 11 does not exist in the material flow direction but exists at a negative angle.

  When the boundary position between the first upper mold 2 and the second upper mold 3 coincides with the boundary between the central portion 6 and the edge portion 7 of the columnar material 5, the central portion 6 of the edge portion 7 of the columnar material 5 is rolled down. The first upper mold 2 and the second upper mold 3 are not contacted until a certain amount of time has passed. Therefore, since the edge portion 7 does not contact the mold at an early stage, the reduction proceeds while the fluidity of the material is high, and the corner 11 on the radially inner side is easily filled with the material.

  However, the manufacturing method of this embodiment is not limited to the case where the boundary position between the first upper mold 2 and the second upper mold 3 coincides with the boundary between the central portion 6 and the edge portion 7 of the columnar material. Since the fluidity changes depending on the heating temperature, the composition of the material, etc., even when the boundary between the first upper mold 2 and the second upper mold 3 does not coincide with the boundary between the central portion 6 and the edge portion 7 of the cylindrical material, the radial direction This is because the inner corner 11 may be filled with the material. For example, as shown in FIG. 9, the boundary between the first upper mold 2 and the second upper mold 3 may be a position that coincides with the outer peripheral surface 9 of the columnar material 5 (forged wasteland).

[Second Embodiment]
Then, the manufacturing method of the circular material of 2nd Embodiment is demonstrated. Below, only a different point from 1st Embodiment is demonstrated and description is abbreviate | omitted about the same point as 1st Embodiment. First, a forging device according to the second embodiment will be described.

[Forging equipment]
FIG. 10 is a cross-sectional view of the forging device 1 according to the second embodiment. Referring to FIG. 10, lower die 4 of forging device 1 includes a first lower die 4A and a second lower die 4B.

  The first lower mold 4A has a shape corresponding to the central portion of the forged waste land after molding.

  The second lower mold 4 </ b> B is disposed outside the first lower mold 4 </ b> A in the radial direction of the columnar material 5. The second lower mold 4B has a shape corresponding to the edge of the forged waste land after molding. The second lower mold 4B is connected to the first lower mold 4A via the elastic member 12. The elastic member 12 supports the second lower mold 4B so as to be movable in the vertical direction. The elastic member 12 is, for example, a spring or a hydraulic device. Before the cylindrical material 5 is crushed, the upper surface of the second lower mold 4B is positioned below the upper surface of the first lower mold 4A.

[Production method]
Then, the manufacturing method of the circular material of 2nd Embodiment is demonstrated. The manufacturing method of the circular material of 2nd Embodiment uses the forging apparatus 1 of 2nd Embodiment mentioned above. In addition to the manufacturing method of 1st Embodiment, the manufacturing method of the circular material of 2nd Embodiment contains a pressurization process. Hereinafter, with reference to FIGS. 11-13, the manufacturing method of the circular material of 2nd Embodiment is demonstrated.

[Pressure process]
Referring to FIG. 11, also in the manufacturing method of the second embodiment, as in the first embodiment, first, a central portion reduction step of reducing the central portion 6 of the columnar material 5, and the outer peripheral surface of the edge portion 7 of the columnar material 5 A restraining step for restraining the radial deformation of 9 is performed.

  After the restraining step, since the side wall portion 8 of the second upper mold 3 restrains the deformation of the columnar material 5 in the radial direction, the center portion 6 of the columnar material 5 is further reduced by the first upper mold 2. In the edge portion 7, the material flows in the vertical direction. When the material flows in the vertical direction, the second lower mold 4B is disposed below the edge portion 7, so that the lower surface of the edge portion 7 comes into contact with the second lower mold 4B.

  Referring to FIG. 12, after the lower surface of the edge portion 7 comes into contact with the second lower mold 4 </ b> B, when the first upper mold 2 further reduces the central portion 6 of the columnar material 5, the material is vertically moved at the edge portion 7. Although it tries to flow, the downward flow of the material is suppressed by the second lower mold 4B. Therefore, the material of the edge portion 7 of the columnar material 5 that was going to move downward flows upward. As the material flows upward at the edge portion 7, the second upper mold 3 also slides relative to the first upper mold 2. When the first upper mold 2 is further lowered from this state, the upward sliding of the second upper mold 3 is completed (the different speed reduction process is completed), and the first upper mold 2 and the second upper mold 3 are the same. The cylindrical material 5 is crushed at a descending speed (the same speed squeezing step is performed).

  When the first upper mold 2 and the second upper mold 3 squeeze the columnar material 5 at the same descending speed, the material flows downward at the edge 7 of the columnar material 5 and is pushed by the second lower mold 4B downward. Moving. At this time, since the second lower mold 4 </ b> B is supported by the elastic member 12, the second lower mold 4 </ b> B applies a force upward to the edge 7 of the columnar material 5. In this state, the first upper mold 2 and the second upper mold 3 reach the bottom dead center as shown in FIG.

  Thus, according to the manufacturing method of the circular material of 2nd Embodiment, the 2nd lower mold | type 4B suppresses that a material flows below in the edge part 7 of the cylindrical raw material 5. FIG. Even after the slide of the second upper mold 3 is finished, an upward force is applied to the edge 7 of the columnar material 5 by the pressurizing action of the second lower mold 4B supported by the elastic member 12 that contracts. to continue. Therefore, the material of the edge 7 of the columnar material 5 easily flows upward, and the lack of the region above the edge of the circular material that is the product is further suppressed.

  Further, when the second lower mold 4B pressurizes the edge 7 of the columnar material 5 upward, the corner region formed by the first lower mold 4A, the second lower mold 4B, and the second upper mold 3 is formed. Since the molding can be performed at an early stage, the lack of thickness in the region below the edge of the circular material that is the product is also suppressed.

  In addition, in 2nd Embodiment mentioned above, after the lower surface of the edge part 7 of the columnar raw material 5 contacted the 2nd lower mold | type 4B, the case where the upward slide of the 2nd upper mold | type 3 was complete | finished was demonstrated. However, the lower surface of the edge 7 of the columnar material 5 may contact the second lower mold 4B after the upward sliding of the second upper mold 3 is completed. In short, the pressurization step may be performed after the central portion reduction step, and the timing may be set as appropriate.

  In the above, the manufacturing method of the circular material of this embodiment was demonstrated. In addition, it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in each of the above-described embodiments, the case where a circular material is manufactured by hot forging has been described. However, the method for manufacturing a circular material according to the present invention is not limited to this, and when a circular material is manufactured by cold forging. Is also applicable. In this case, the heating process in each embodiment described above is omitted.

1: Forging device 2: First upper die 3: Second upper die 4: Lower die 5: Column material 6: Center portion 7: Edge portion 8: Side wall portion 9: Outer peripheral surface

Claims (5)

A method of manufacturing a circular material from a cylindrical material including a central portion and an edge portion having an outer peripheral surface,
A step of rolling down the central portion of the cylindrical material, and deforming the cylindrical material in a radial direction;
Constraining the radial deformation of the cylindrical material deforming in the radial direction;
After the step of constraining the radial deformation of the columnar material, the step of further reducing the center portion of the columnar material and rolling down the edge of the columnar material at a reduction speed lower than the reduction rate of the center portion When,
And a step of rolling down the central portion and the edge portion of the cylindrical material at the same rolling speed after the step of rolling down the edge portion. The method for producing a circular material according to claim 1, further comprising:
A first upper mold;
A second upper portion that includes a side wall portion that opposes the outer peripheral surface of the columnar material, is disposed on a radially outer side of the columnar material with respect to the first upper die, and is slidable in a downward direction with respect to the first upper die; Type,
Arranging the columnar material in a forging device including a lower die facing the first upper die and the second upper die,
In the step of deforming the cylindrical material in the radial direction, the first upper mold squeezes the central portion of the cylindrical material,
In the step of constraining the radial deformation of the columnar material, the side wall portion of the second upper mold is in contact with the outer peripheral surface of the columnar material, constraining the radial deformation of the columnar material,
In the step of rolling down the central portion of the cylindrical material and rolling down the edge of the cylindrical material at a rolling speed slower than the rolling speed of the central portion, the first lower mold has a lowering speed than the lowering speed of the first upper mold. (2) A method for producing a circular material, wherein the upper mold reduces the edge of the cylindrical material. It is a manufacturing method of the circular material according to claim 2,
In the step of rolling down the central part and the edge of the cylindrical material at the same rolling speed, the first upper mold reaches the bottom dead center at the same time as the second upper mold. The method for producing a circular material according to any one of claims 1 to 3, further comprising:
A method for producing a circular material, comprising a step of pressing an edge of the columnar material in a direction opposite to the reduction direction after the step of deforming the columnar material in a radial direction. The method for producing a circular material according to claim 2 or 3, further comprising:
After the step of deforming the columnar material in the radial direction, the step of pressurizing the edge of the columnar material in the direction opposite to the reduction direction,
The lower mold of the forging device is a first lower mold and a second lower mold that is disposed on the outer side in the radial direction of the cylindrical material than the first lower mold and is attached to the first lower mold via an elastic member. Including a lower mold,
In the step of pressing the edge of the columnar material in the direction opposite to the reduction direction, the second lower mold pressurizes the edge of the columnar material.

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