JP4150927B2 - Roll forging method - Google Patents

Description

  The present invention relates to a method for roll forging a rough profile to be subjected to stamping forging.

  For example, when manufacturing parts with large diameter differences in the axial direction, such as steering knuckles and connecting rods for automobile parts, by stamping forging, a deformed rod-shaped rough shape (preliminary product) is usually formed by roll forging. However, this rough shaped material is subjected to stamping forging (see, for example, Patent Document 1).

  FIG. 4 shows a rough shaped member 1 used for steering forging of a steering knuckle. A large-diameter portion 2 is provided on one end side, a small-diameter portion 3 is provided in the middle, and a stepped intermediate-diameter portion 4 is provided on the other end side. In addition, the tapered portion 5 and 6 are connected to each other between the large diameter portion 2 and the small diameter portion 3 and between the small diameter portion 3 and the medium diameter portion 4. At the time of die forging, as shown in FIG. 5, the rough shaped member 1 is positioned and mounted on the forging die 7 such that the large diameter portion 2 is positioned at the large end molding portion 8 a of the impression 8. As a result, the material is sufficiently filled up in the impression 8, and a steering knuckle having a desired shape can be obtained.

  Here, as shown in FIG. 6, roll forging for forming the rough shape member 1 is performed in such a manner that a pair of roll dies 11 and 12 having a hole mold portion 10 on a part of the outer peripheral surface are in opposite directions. This is carried out through a heated rod-shaped material 14 whose one end is supported by a manipulator 13 in the hole mold 10 of the rotating roll molds 11 and 12. In this case, since it is difficult to make the final shape (coarse shaped material 1) from the rod-shaped material 14 at a time, the plurality of hole mold portions 10 are usually arranged at a predetermined pitch in the axial direction of the roll dies 11, 12. The bar-shaped material 14 is horizontally fed by a predetermined pitch while being rotated 90 degrees by the manipulator 13, and, for example, as shown in FIG. 7, the cross-sectional shape is changed from an oval to a square, and from a square to an oval, a plurality of passes ( Here, the rough shaped material 1 having a desired shape is formed by taking 4 passes). The portion of the rod-shaped material 14 gripped by the manipulator 13 remains as an unformed part, but this unformed part (non-formed part) becomes the large-diameter part 2 of the rough shaped member 1 as it is.

By the way, as shown in FIG. 8, the roll dies 11 and 12 used for the roll forging described above have an intersection P between the end face 15 and the die face 16 of the hole mold portion 10, which has a large diameter in the rough shape material 1. It is set according to the boundary A (FIG. 4) between the portion (unformed portion) 2 and the tapered portion (formed portion) 5. However, when the rod-shaped material 14 is formed by performing a plurality of passes while laterally feeding the rod-shaped material 14 at a predetermined pitch by the manipulator 13 as described above, if the moving pitch of the manipulator 13 is slightly shifted, the intersecting portion P becomes the rod-shaped material 14. Sharply bite into the surface, and a large scratch is formed in the vicinity of the boundary A, resulting in poor molding. Therefore, conventionally, as shown in FIG. 8 as well, a chamfered radius (R) having an appropriate size (5 to 15 mm) is provided along the intersection P to prevent the occurrence of the above-described scratches.
Japanese Utility Model Publication No. 5-60636

  However, when roll forging is performed on the aluminum-based rod-shaped material 14 using the roll dies 11 and 12 having chamfered rounds at the intersection P, as shown in FIG. 9, the large diameter portion (unformed portion) 2 is likely to occur near the boundary A between the taper portion 5 and the taper portion 5 (in the case of an iron-based material, such a step S does not occur). Then, when the rough shaped material 1 having such a step S is used for the forging die 7 (FIG. 5) and die forging is performed, the step S is scratched or ridged on the forged product F as shown in FIG. L remains clearly and causes a problem in quality. The step S is presumed to be caused by a difference in material properties between the aluminum-based material and the iron-based material, particularly a difference in work hardening index. That is, in the case of an aluminum-based material, since the work hardening index is small, a portion that contacts the portion 17 (FIG. 8) provided with the chamfered radius is likely to be pushed in locally, which is presumed to be caused by this. .

  The present invention has been made in view of the above-described conventional problems, and the problem is that even if an aluminum-based material is targeted, a step may be generated near the boundary between the unformed part and the formed part. There is no roll forging method.

In order to solve the above-mentioned problems, a roll forging method according to the present invention is a roll forging method in which a rough shaped material for punching forging is formed through an aluminum-based rod-shaped material in a hole mold part of a pair of roll molds rotating in opposite directions. In the conventional roll mold, the end surface of the hole mold portion of the roll mold is designed in accordance with the boundary between the non-molded portion and the molded portion of the rod-shaped material at the intersection between the end surface of the hole mold portion and the mold surface. It is displaced by a predetermined angle to the front side in the rotational direction from the prescribed end surface, and along the portion where the surface including the displaced end surface intersects the extended surface of the mold surface of the hole mold part, the conventional roll mold By setting a chamfering radius of the same size as the chamfering radius of the conventional roll type, starting from the vicinity of the intersection of the end surface of the hole mold portion and the mold surface, the hole type portion of the roll type, Processing of the conventional roll type When starting to contact the aluminum-based stick-shaped material elephant work the same shape, and wherein placing the chamfered portion of the rolled outside the outer peripheral surface of the rod-like material. In this case, it is desirable that the end face of the roll-type hole part is displaced at least 3 degrees from the specified end face.

In the roll forging method performed in this way, the end surface of the hole mold part of the roll mold is displaced by a predetermined angle to the front side in the rotational direction from the specified end surface , and the surface including the displaced end surface and the mold surface of the hole mold part By setting a new chamfering radius that is the same size as the conventional roll-type chamfering radius along the part where the extension surface intersects, the chamfering of the roll-type hole portion when it begins to contact the rod-shaped material The portion is placed outside the outer peripheral surface of the rod-shaped material, so that the material is not locally pushed by the chamfered portion. That is, even if an aluminum-based material having the same shape as the workpiece to be processed in the conventional roll mold is used, there is no step near the boundary between the unformed part and the formed part. Scratches or ridge lines due to steps are not generated in the forged product.

  According to the roll forging method performed using the roll die according to the present invention, even if an aluminum-based material is used as the rod-shaped material, there is no step near the boundary between the unformed part and the formed part. The quality of the forged product obtained by stamping forging is good.

  Hereinafter, the best mode for carrying out the present invention will be described.

FIG. 1 shows a main structure of a roll type as one embodiment of the present invention. The present roll-type, the aluminum-based coarse profile 1 to be subjected to stamping forging of steering knuckle (Fig 4, 5) intended to roll forging, as the overall structure thereof is shown in FIG. 6 Since they are the same, here, the same parts are denoted by the same reference numerals. In the present embodiment, the end face 15 ′ of the hole mold part 10 of the roll dies 11, 12 is set in a plane displaced by θ degrees to the front side in the rotational direction from the conventional end face (specified end face) 15. Further, a chamfered radius (R ′) is set along an intersecting portion P ′ between the newly set surface including the end surface 15 ′ of the hole mold part 10 and the extended surface of the mold surface 16 of the hole mold part 10. . In FIG. 1, a two-dot chain line C that surrounds the outer peripheries of the roll dies 11 and 12 represents a boundary line of a clearance set between the pair of roll dies 11 and 12.

  By the way, in the conventional roll molds 11 and 12, the intersection P between the end face 15 of the hole mold part 10 and the mold surface 16 is passed through the hole mold part 10 of the roll molds 11 and 12, as shown in FIG. It was set at a position aligned with the outer peripheral surface of the rod-shaped material 14. On the other hand, the intersection part P ′ in the present embodiment has a surface displaced by θ degrees from the prescribed end surface 15 of the hole mold part 10 to the front side in the rotation direction and the mold surface 16 of the hole mold part 10 as described above. Since it is an intersection with the extended surface, it is set outside the outer peripheral surface of the rod-shaped material 14. Here, when the angle θ to be displaced forward in the rotational direction is about 3 degrees and the chamfering radius (R ′) is the same size (5 to 15 mm) as the conventional chamfering radius (R), the chamfering The starting point of the radius (R ′) substantially coincides with the conventional intersection site P, and the entire chamfered portion 17 ′ newly provided with the chamfered radius surface (R ′) is placed outside the rod-shaped material.

The roll forging by the roll dies 11 and 12 described above is exactly the same as the conventional one, and in the mode shown in FIGS. 6 and 7, the bar-shaped material 14 is rotated 90 degrees by the manipulator 13 and is laterally fed by a predetermined pitch. While changing the cross-sectional shape from an oval to a square and from a square to an oval, a rough shaped material 1 having a desired shape is formed through a plurality of passes. In this roll forging, since the entire chamfered portion 17 ′ of the hole mold portion 10 is placed outside the outer peripheral surface of the rod-shaped material 14 as described above, the material 14 is locally localized by the chamfered portion 17 ′. It will not be pushed into. That is, when forming a plurality of passes while traversing the rod-shaped material 14 at a predetermined pitch by the manipulator 13 as described above , targeting an aluminum-based material having the same shape as a conventional roll-type workpiece , as described above, Even if the movement pitch of the manipulator 13 is slightly shifted , as shown in FIG. 9, the step S is not generated near the boundary A between the large diameter portion (unformed portion) 2 and the tapered portion 5 (formed portion). As a result, scratches or ridge lines (FIG. 10) due to steps are not generated in the forged product obtained by die forging.

  Incidentally, when chamfering radius (R) is provided along the intersecting portion P set on the outer peripheral surface of the rod-shaped material 14 as in the prior art, as shown in FIG. A portion of the portion 14 bites into the material 14, whereby the step S is likely to occur near the boundary A between the unformed portion 2 and the formed portion 5. The angle θ for displacing the new end face 15 ′ of the hole mold part 10 to the front side in the rotational direction from the specified end face 15 may be larger than 3 degrees. Since the volume increases and causes an increase in weight and cost, it is sufficient to set the value to 3 degrees or close to this.

  As in the above embodiment, the end face 15 ′ of the hole mold 10 is set within a plane that is displaced forward by 3 degrees from the specified end face 15, and the intersection of this face and the extended face of the mold face 16 is set. Using roll dies 11 and 12 (Fig. 1) with chamfered radius (R ') along part P', roll forging is performed on a rod-shaped material made of JIS 6061 series aluminum alloy with an outer diameter of 90 mm. 4 was molded. The rough shaped material 1 (present invention material) having the shape shown in FIG. Roll forging was performed by heating the rod-shaped material to 450 ° C. and taking 4 passes in the manner shown in FIGS. In the rough shaped member 1, the diameter of the small diameter portion 3 was 40 mm, and the length of the taper portion 5 connecting the small diameter portion 3 and the unformed portion 2 was 236 mm. In addition, for comparison, roll forging was performed using the same roll dies 11 and 12 (FIG. 8) as those in the prior art under the same conditions as described above to obtain a rough material (comparative material) having the same size and shape. And after shaping | molding, height was continuously measured with the shape measuring device over the predetermined length from the unmolded part 2 to the taper part 5 as shown in FIG. 3, and the dimensional change was calculated | required about this invention material and the comparison material. . FIG. 3 shows the results. In the present invention material, the height smoothly changes from the unformed portion 2 to the tapered portion 5 across the boundary A, whereas the comparative material is. The height is greatly reduced on the taper portion 5 side with respect to the boundary A, and it is clear that the step S is generated.

It is a schematic diagram which shows the principal part structure of the roll type | mold which concerns on this invention, and the state at the time of the start of roll forge by this roll type | mold. It is an enlarged view which expands and shows the X section of FIG. It is a graph which shows the dimension measurement result about the rough shaped material obtained by performing roll forging using the roll type | mold which concerns on this invention, and the conventional roll type | mold. It is a top view which shows the shape of the rough shaped material used for the die forging of a sterling knuckle. It is a top view which shows the state which set the rough shaped material shown in FIG. 4 to the forging die for stamping forging. It is a schematic diagram which shows the general implementation condition of roll forging. It is a schematic diagram which shows the raw material shape change for every pass in roll forging. It is a schematic diagram which shows the state at the time of the start of roll forge by the conventional roll type | mold. It is a schematic diagram which shows the malfunction occurrence state by the conventional roll forging. It is a top view which shows the malfunction occurrence state at the time of performing stamping forge using the conventional rough shape material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hole type | mold part 11,12 Roll type | mold 14 Rod-shaped raw material 15 Prescribed end surface 15 'Newly set end surface 16 Mold surface 17 Conventional chamfered part 17' Newly set chamfered part R Conventional chamfer R's Newly set Chamfer

Claims (2)

In a roll forging method in which a rough shaped material for punching and forging is formed through an aluminum-based rod-like material in a pair of roll molds rotating in opposite directions, the end face of the roll mold hole mold part is defined by the hole mold. The intersection part of the end surface of the part and the mold surface is displaced by a predetermined angle to the front side in the rotational direction from the specified end surface of the conventional roll mold designed according to the boundary between the non-molded part and the molded part in the rod-shaped material, Starting from the vicinity of the intersection between the end surface of the hole mold portion and the mold surface in the conventional roll mold, along the portion where the surface including the displaced end surface intersects the extended surface of the mold surface of the hole mold portion. By setting a chamfering radius of the same size as the conventional roll-type chamfering radius , the roll-type hole mold portion is formed into an aluminum rod-shaped material having the same shape as the workpiece to be processed of the conventional roll-type. Before you start touching Roll forging method characterized by placing the chamfered portion of the rolled outside the outer peripheral surface of the rod-like material. The roll forging method according to claim 1, wherein the end face of the roll mold hole portion is displaced at least 3 degrees from the specified end face.

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