Rolling forging method and device

Abstract

To provide a rolling forging method and a rolling forging device capable of increasing the circularity of a final product shape without the possibility of interference between outer peripheral surfaces of a roll.SOLUTION: This rolling forging device comprises: two edge rolls 1 and 2 that abut against the inner diameter of an annular forging blank c4 from both sides of the forging blank c4 in an axial direction to apply an axial pressing force; and two reception rolls 3A and 3B that are arranged to face each other on the outer peripheral side of the forging blank c4 with a plane including the axis of the two edge rolls 1 and 2 set as a boundary and that apply a pressing force to the outer peripheral surface of the forging blank c4.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a rolling forging method and apparatus. [Background technology]

[0002] Conventionally, ring gears used in automobile differentials and the like are manufactured by rolling forging. A rolling forging device used for this forging is disclosed in Patent Document 1 (Japanese Patent No. 2507867) as a rolling machine.

[0003] This rolling machine has two edge rolls that contact the inner diameter of the annular blank from both axial sides at an angle to apply an axial pressing force, and one backing roll that applies a pressing force to the outer peripheral surface of the forged blank. The two edge rolls and the backing roll form a triangular closed area, and the final product shape is formed in this closed area by closed rolling. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2507867 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional rolling machines had the problem that the inner and outer circumferences of the forged blank were in a free state (unsupported state) on both circumferential sides (upstream and downstream) of the triangular closed area, resulting in poor roundness of the final product shape. In addition, when the two edge rolls and one backing roll approach each other on the outer periphery side of the triangular closed area, there was a risk of interference between the outer peripheries of these rolls. This placed restrictions on the final product shape that could be produced by rolling forging.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a rolling forging method and apparatus which can improve the roundness of the final product shape and which eliminates the risk of interference between the outer peripheral surfaces of the rolls. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the rolling forging method of the present invention is characterized by comprising a forging press process for forming an annular forged blank, and a rolling and forming process for rolling and forming the final product shape from the forged blank using two edge rolls that abut against the inner diameter of the forged blank from both axial sides of the blank at an angle to apply an axial pressing force, and two receiving rolls that are arranged opposite each other on the outer periphery of the forged blank, with a plane including the axes of the two edge rolls as the boundary, and that apply a pressing force to the outer periphery of the forged blank.

[0008] In addition, the rolling forging device of the present invention is characterized in that it comprises two edge rolls that abut against the inner diameter of a ring-shaped forged blank from both axial sides of the forged blank in an inclined state, thereby applying an axial pressing force, and two receiving rolls that are arranged opposite each other on the outer periphery of the forged blank, separated by a plane including the axes of the two edge rolls, and that apply a pressing force to the outer periphery of the forged blank. Effect of the Invention

[0009] According to the present invention, the roundness of the final product can be improved, and interference between the outer circumferential surfaces of the rolls can be prevented. [Brief description of the drawings]

[0010] [Figure 1A] 1 is a perspective view of a rolling forging device according to the present invention, seen obliquely from above. [Figure 1B] 1 is a perspective view of a rolling forging device according to the present invention, seen obliquely from below. [Figure 2A] 1 is a plan view of a rolling forging device according to the present invention. [Figure 2B]FIG. 2 is a bottom view of the rolling forging device according to the present invention. [Figure 3A] 1 is a front view of a rolling forging device according to the present invention. [Figure 3B] FIG. 2 is a right side view of the rolling forging device according to the present invention. [Figure 4] FIG. 2B is a plan view of FIG. 2A with the upper edge roll omitted. [Diagram 5] FIG. 2 is a perspective view of (a) an upper edge roll and (b) a lower edge roll. [Figure 6A] 1 is a cross-sectional view of an example 1 of an annular product produced by the rolling forging method according to the present invention. [Figure 6B] FIG. 2 is a cross-sectional view of an example 2 of an annular product produced by the rolling forging method according to the present invention. [Figure 6C] FIG. 4 is a cross-sectional view of an example 3 of an annular product produced by the rolling forging method according to the present invention. [Figure 6D] FIG. 4 is a cross-sectional view of an example 4 of an annular product produced by the rolling forging method according to the present invention. [Figure 7] FIG. 1 is an explanatory diagram showing steps of a conventional rolling forging method. [Figure 8] FIG. 1 is an explanatory diagram of an apparatus used in a conventional rolling forging method. [Figure 9] 1A is a cross-sectional view of a forged blank used in a conventional rolling forging method, FIG. 1B is a cross-sectional view of a rolling forging device, and FIG. 1C is a plan view of the rolling forging device. [Figure 10A] FIG. 1 is a side view of a conventional rolling forging device. [Figure 10B] FIG. 1 is a plan view of a conventional rolling forging device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Rolling forging method and equipment An embodiment of a rolling forging method and device according to the present invention will be described below with reference to the drawings. Fig. 1 is a perspective view of a rolling forging device as seen obliquely from above, and Fig. 1B is a perspective view of the same device as seen obliquely from below.

[0012] This rolling forging device has an upper edge roll 1, a lower edge roll 2, and a pair of front and rear support rolls 3A and 3B. The upper edge roll 1 and the lower edge roll 2 press the inner diameter surface (inner peripheral surface) of the final product d, and the support rolls 3A and 3B press the outer diameter surface (outer peripheral surface) of the final product d.

[0013] The upper edge roll 1 and the lower edge roll 2 are connected to a rotation drive means and are driven to rotate in the direction of the arrow as shown in Fig. 1A. The upper edge roll 1 and the lower edge roll 2 are configured to be horizontally movable along a plane P in Fig. 2A. The plane P is a plane that includes the axes of the upper and lower edge rolls 1 and 2.

[0014] The axes of the upper edge roll 1 and the lower edge roll 2 are inclined at a predetermined angle with respect to the rotation plane of the final product d. The inclination direction is toward the outside in the radial direction of the final product d.

[0015] The predetermined inclination angle of the axis of the upper edge roll 1 and the lower edge roll 2 can be set according to the inner diameter shape of the final product d. Basically, the predetermined inclination angle of the upper edge roll 1 and the lower edge roll 2 can be the same.

[0016] For example, the inclination angle of the upper edge roll 1 and the lower edge roll 2 can be set to about 60 degrees. However, depending on the inner diameter shape of the final product d, the predetermined inclination angles of the upper edge roll 1 and the lower edge roll 2 can be made different from each other.

[0017] The axes of the upper edge roll 1 and the lower edge roll 2 are inclined so that the inner diameter shape of the final product d is shared and forged by the upper and lower edge rolls 1 and 2. By inclining the edge rolls 1 and 2, the inner diameter of the final product d can be pressed in both the axial and radial directions. This makes it possible to handle the diverse and complex inner diameter shapes of the final product d.

[0018] The upper edge roll 1 and the lower edge roll 2 are shown in Figures 5(a) and 5(b). As shown in Figure 5(a), the upper edge roll 1 has four annular steps 1h, 1g, 1f, and 1e following the main cylindrical portion 1i. These four annular steps 1h, 1g, 1f, and 1e correspond to the four annular steps d8, d7, d6, and d5 (see Figure 1A) formed on the inner diameter of the final product d, respectively.

[0019] As shown in Fig. 5(b), the bottom edge roll 2 has three annular steps 2g, 2f, and 2e. These three annular steps 2g, 2f, and 2e correspond to the three annular steps d11, d10, and d9 (see Figs. 1B and 2B) formed on the inner diameter of the final product d, respectively.

[0020] The front and rear receiving rolls 3A, 3B are disposed facing each other on the outer periphery side of the final product d, with a plane P including the axes of the upper and lower edge rolls 1, 2 as the boundary. The height positions of the receiving rolls 3A, 3B are at the same height as the rotation surface (support surface) of the final product d.

[0021] The bottom surface of the final product d is supported by a horizontal support plate having long holes into which the tips of the edge rolls 1 and 2 are inserted so as to be movable along the plane P in FIG.

[0022] 2A, a plane P including the axes of the upper and lower edge rolls 1 and 2 is indicated by a horizontal dashed line. The axes 3Ac and 3Bc of the backing rolls 3A and 3B are disposed at an equal distance E from the plane P.

[0023] By using the two receiving rolls 3A and 3B in this way, the roundness of the final product d can be improved. That is, in Figures 2A and 4, the inner diameter of the final product d is pressed rightward along the plane P with an outward force vector F1 by the upper and lower edge rolls 1 and 2, while the outer diameter of the final product d is pressed evenly toward the rotation center C with inward force vectors F2 and F2 by the two receiving rolls 3A and 3B from both the upper and lower sides sandwiching the plane P.

[0024] In addition, the upper edge roll in Fig. 2A is omitted in Fig. 4. The balance of the three force vectors F1, F2, and F2 in Fig. 4 regulates the radius of curvature of the final product d, and as a result, the circularity of the final product d is improved.

[0025] The straight lines connecting the center of rotation C of the final product d and the axes 3Ac and 3Bc of the receiving rolls 3A and 3B form an equal angle θ with the plane P. The triangle (C, 3Ac, 3Bc) with the center of rotation C as its vertex is an isosceles triangle.

[0026] The diameter of the backing rolls 3A and 3B and the angle θ can be freely changed depending on the size (diameter) of the final product d. However, the diameters of the backing rolls 3A and 3B must be the same, and the angle θ with respect to the plane P must also be the same for the backing rolls 3A and 3B. If this relationship is not met, it will affect the roundness of the final product d, resulting in a defective product. Therefore, the aforementioned "isosceles triangle" is essential for product quality.

[0027] In the illustrated example, the angle θ is set to about 30 degrees, but it is of course not limited to this angle. Also, in the illustrated example, the diameter of the receiving rolls 3A and 3B is slightly smaller than the diameter of the final product d, but it is of course not limited to such a large-small relationship.

[0028] A cassette-type integrated roll support shaft is fitted into the central holes 3Aa, 3Ba of the support rolls 3A, 3B. The roll support shaft is supported by bearings arranged on a common frame (fixed) so as to be freely rotatable.

[0029] The width (vertical width) of the outer peripheral surface of the receiving rolls 3A and 3B is slightly wider than the width (vertical width) of the outer peripheral surface of the final product d, as shown in Fig. 3A. This ensures that the entire outer peripheral surface of the final product d is supported by the receiving rolls 3A and 3B.

[0030] The upper edges of the receiving rolls 3A and 3B are tapered surfaces 3Ai and 3Bi, respectively, which are configured to prevent interference with the main cylindrical portion 1i of the upper edge roll 1.

[0031] In other words, even if the receiving rolls 3A, 3B are arranged close to each other, or the upper and lower edge rolls 1, 2 are arranged close to the receiving rolls 3A, 3B, the upper edge roll 1 is prevented from interfering with the receiving rolls 3A, 3B.

[0032] However, the tapered surfaces 3Ai and 3Bi are not essential for preventing interference between the upper edge roll 1 and the backing rolls 3A and 3B. In this embodiment, since the backing rolls 3A and 3B are configured from two rolls, interference between the rolls can be easily avoided by increasing the mutual distance between the backing rolls 3A and 3B.

[0033] When a single backing roll is used as in the past, the backing roll 3 is likely to interfere with the upper and lower edge rolls 1 and 2 as shown in Figure 9(b)(c). This places restrictions on the shapes of the edge rolls 1 and 2 and the backing roll 3, and ultimately on the shape of the final product d that can be formed by rolling forging.

[0034] By configuring the backing rolls as a pair of front and rear backing rolls 3A, 3B as in this embodiment, it is possible to prevent the upper and lower edge rolls 1, 2 from interfering with the backing rolls 3A, 3B. Therefore, the shapes of the edge rolls 1, 2 and the backing rolls 3A, 3B can be freely designed, and therefore the shape of the final product d that can be rolled forged can also be freely designed.

[0035] Example of final product d with different shape 6A to 6D show examples of final products d with different shapes. The shapes of the upper edge roll 1 and the lower edge roll 2 correspond to the shapes of the respective final products d. In each example, the outer peripheral surface of the final product d is pressed by two receiving rolls 3A and 3B.

[0036] In Fig. 6A and Fig. 6B, the outer peripheral surfaces of the two backing rolls 3A and 3B are simple cylindrical in shape corresponding to the outer peripheral surface of the final product d, but in Fig. 6C, the outer peripheral surfaces of the backing rolls 3A and 3B are tapered (conical) surfaces corresponding to the outer peripheral surface of the final product d. Also, in Fig. 6D, an annular convex portion is formed on the outer peripheral surfaces of the backing rolls 3A and 3B corresponding to the outer peripheral surface of the final product d.

[0037] Conventional rolling forging methods and equipment The rolling forging method and rolling forging device of the present invention are basically the same as the conventional rolling forging method and device disclosed in Patent Document 1 (Japanese Patent No. 2507867) except that the rolling forging method and rolling forging device are configured with two backing rolls. Therefore, the conventional rolling forging method and device will be described below with reference to Figs. 7 to 10B.

[0038] Fig. 7 is a process diagram showing a conventional rolling forging method. In this process, the billet c1 on the left end is first heated to a predetermined temperature (e.g., 1250°C) in an induction heating furnace. The heated billet c1 is then upset into a disk-shaped blank c2 using an upsetting punch and die.

[0039] Next, a bottomed annular intermediate blank c3 having a diameter smaller than the inner and outer diameters of the final product d and a thickness in the axial direction greater than that of the final product d is formed using a punch and die having a diameter smaller than that of the final product d. The center of the bottom of this blank c3 is punched out using a punch and die to form an L-shaped cross-sectional annular forged blank c4 having a diameter smaller than that of the final product d and a thickness in the axial direction greater than that of the final product d.

[0040] The forging press process is described above. This forging press process will be explained in more detail with reference to Fig. 8. First, the billet c1 is heated to a predetermined temperature in an induction heating furnace 4, and then upset into a disk-shaped blank c2 by an upsetting punch 5 and a die 6.

[0041] Next, a bottomed annular intermediate blank c3 having a diameter smaller than the inner and outer diameters of the final product d and a thickness in the axial direction greater than that of the final product d is formed using a punch 7 and a die 8 having a diameter smaller than the inner and outer diameters of the final product d. The center of the bottom of this blank c3 is punched out using a punch 9 and a die 10 of a forging press 11 to form an L-shaped cross-sectional annular forged blank c4 having a diameter smaller than the inner and outer diameters of the final product d and a thickness in the axial direction greater than that of the final product d.

[0042] The forging press 11 is configured so that the punches and dies are set at equal intervals and their forming operations are performed in a synchronized manner, and a transfer feeder (not shown) is used to sequentially supply the items to be forged to the processing positions of each punch and die.

[0043] The forged blank c4 with the bottom center punched out is rolled and forged into the final product shape by a rolling machine 12 shown at the right end of Fig. 8. This rolling machine 12 has two edge rolls 1 and 2 that come into contact with the forged blank c4 from both axial ends to apply an axial pressing force, and one backing roll 3 that comes into contact with the outer circumferential surface of the forged blank c4 in a plane substantially the same as the plane on which the two edge rolls 1 and 2 apply their pressing forces to the forged blank c4, applying a radially inward pressing force to give the outer circumferential surface shape of the final product d (two backing rolls 3A and 3B in this embodiment).

[0044] As shown in Fig. 9, the two edge rolls 1 and 2 have cut surface shapes along the axial direction at both axial end surfaces of the final product d. That is, one edge roll 1 is integrally provided with a first forming surface 1a for forming the web d1 of the final product d, a second forming surface 1b continuing thereto for forming the inner diameter tapered surface of the flange portion d2 of the final product d, and a third forming surface 1c continuing thereto for forming one axial end surface d3 of the final product d. The other edge roll 2 is also provided with substantially similar first forming surface 2a, second forming surface 2b, and third forming surface 2c.

[0045] As shown in Figures 10A and 10B, these two edge rolls 1, 2 are installed on a base 13 via support members 14, 15 in a vertically opposed state at a predetermined angle and supported rotatably, with the upper edge roll 1 being able to retreat upward. The backing roll 3 may be attached in a fixed position to a roll support shaft supported on a fixed stand as described above, or may be supported rotatably on a sliding stand 17 installed on the base 13 via a pressing means 16 so as to slide horizontally. The backing roll 3 applies a radial pressing force to the forged blank c4 during rolling.

[0046] A plurality of guide rolls 18 are supported by a base 13 so as to be able to come into contact with the outer peripheral surface of the forged blank c4 during rolling and to automatically move in the radial direction in response to the expansion of the diameter of the forged blank c4 during rolling. In Fig. 10B, 19 is a carrying-in means for the forged blank c4 and 20 is a carrying-out means for the final product d.

[0047] When the forging press 11 and the rolling machine 12 are configured in a continuous line, the residual heat of the hot-forged forged blank c4 is utilized, and the forged blank c4 is supplied between two edge rolls 1, 2 of the rolling machine 12 either as is or after being slightly heated in an induction heating furnace to a predetermined temperature (e.g., 950°C). The two edge rolls 1, 2 press the forged blank c4 from both axial ends, and one backing roll 3 is pressed against the outer peripheral surface of the forged blank c4 to apply a radial pressing force (in this embodiment, the pressing force is applied by two backing rolls 3A, 3B).

[0048] In this state, the backing roll 3 is rotated to rotate the forged blank c4 in contact with it, while the two edge rolls 1, 2 and the backing roll 3 perform closed rolling of the forged blank c4 to produce the final product d. The two edge rolls 1, 2 may be rotated actively, or may be rotated drivenly.

[0049] After the rolling is completed, the rotation of the backing roll 3 is stopped, the backing roll 3 is retreated in the radial direction, and the upper edge roll 1 is retreated upward. As a result, the final product d which has completed the rolling is discharged by the discharge means 20, and the next forged blank c4 is brought in by the delivery means 19, and the above operation is repeated.

[0050] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible. For example, in the above embodiment, both the upper edge roll 1 and the lower edge roll 2 are stepped, but the stepped shape depends on the shape of the final product d, and depending on the shape of the final product d, for example, only one of the upper edge roll 1 or the lower edge roll 2 can be stepped and the other can be tapered. [Explanation of symbols]

[0051] 1: upper edge roll 1a: first forming surface 1b: 2nd molding surface 1c: 3rd molding surface 1h, 1g, 1f, 1e: stepped portion 1i: cylindrical body portion 2: Lower edge roll 2a: First forming surface 2b: 2nd molding surface 2c: 3rd molding surface 2g, 2f, 2e: stepped parts 3A, 3B: receiving rolls 3Aa, 3Ba: Center hole 3Ac, 3Bc: Axis line 3Ai, 3Bi: Tapered surface 4: Induction heating furnace 5: Upsetting punch 6: Die 7: Punch 8: Dice 9: Punch 10: Die 11: Forging press 12: Rolling machine 13: Base 14, 15: Support members 16: Pressing means 17: Slide table 18: Guide roll 19: Loading means 20: Discharge means C: Rotation center E: Equidistant P: Plane c1: billet c2: blank c3: Intermediate blank c4: Forging blank d: Final product d1: Web d11, d10: Stepped portion d2: Flange portion d3: Axial end face d8, d7: Stepped part F1: Outward force vector F2: Inward force vector θ: Angle

Claims

1. a forging press process for forming an annular forged blank; a rolling and rolling process in which the forged blank is rolled into a final product shape using two edge rolls that contact the inner diameter of the forged blank from both axial sides of the forged blank at an angle to apply an axial pressing force, and two receiving rolls that are arranged opposite each other on the outer periphery of the forged blank, with a plane including the axes of the two edge rolls as the boundary, and that apply a pressing force to the outer periphery of the forged blank.

2. two edge rolls that contact the inner diameter of an annular forged blank from both axial sides of the forged blank in an inclined state and apply a pressing force in the axial direction; A rolling forging device characterized by comprising two support rolls that are arranged opposite each other on the outer periphery of the forged blank, with a plane including the axes of the two edge rolls as the boundary, and that apply a pressing force to the outer periphery of the forged blank.

3. 3. The rolling forging apparatus according to claim 2, wherein the two backing rolls have the same outer diameter and the axes of the two backing rolls are disposed at equal distances from a plane containing the axes of the two edge rolls.

4. A rolling forging device as claimed in claim 2 or 3, characterized in that the two edge rolls are connected to a rotational drive source, the forged blank is rotated by the rotation of the two edge rolls, and the two backing rolls are rotated by the rotation of the forged blank.

5. A rolling forging device according to claim 2 or 3, characterized in that the two backing rolls are connected to a rotational drive source, the forged blank is rotated by the rotation of the two backing rolls, and the two edge rolls are rotated by the rotation of the forged blank.

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