JP2891048B2 - Mold for rotary forging - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary forging apparatus for forming a ring-shaped mechanical part such as a gear by warm or hot forging, and more particularly, to a structure of a die used in the rotary forging apparatus. It is about.

[0002]

2. Description of the Related Art As a rotary forging device for forming a ring-shaped mechanical part such as a gear, for example, Japanese Patent Application Laid-Open No. Sho 61-242 is disclosed.
No. 738 and Japanese Patent Application Laid-Open No. 2-30350 are known. As shown in FIG. 4, a conventional die structure used in the rotary forging apparatus has a ring-shaped bottom die 1a for restraining the outer peripheral side surface of the work 2.
And a ring-shaped die insert 1 mounted coaxially and integrally with the bottom die 1a and having an upper surface as a molding surface.
b and the lower die 1 are formed, and the inner peripheral surface of the die insert 1b forms a concave portion.

The upper die 6 facing the lower die 1 has a large-diameter cylindrical portion 6b and a large-diameter cylindrical portion 6b forming a molding surface.
A small-diameter cylindrical portion 6a protruding coaxially from the center of the lower surface, and the small-diameter cylindrical portion 6a forms a projection.
The upper die 6 is connected to driving means (not shown), and the axis M of the upper die 6 is driven by the driving means.
The drive means is configured to rotate while swinging around a rotation center axis (vertical axis) L.

Then, the upper die 6 rotated by the driving means is lowered toward the lower die 1 on which the ring-shaped workpiece 2 is placed, and the small-diameter cylindrical portion 6a of the upper die 6 is moved to the die of the lower die 1. The upper die 6 is fitted into the insert 1b and aligned, and a part of the upper die 6 comes into contact with a part of the work 2, and the upper die 6
By rotating while swinging at a predetermined swing angle θ, the work 2 is rolled and pressed down sequentially in the circumferential direction, thereby forming the work 2 into a predetermined shape.

At this time, since the die insert 1b of the lower die 1 and the small-diameter cylindrical portion 6a of the upper die 6 are swingably fitted, the work 2 is rotated when the upper die 6 rotates. When the die insert 1b and the small-diameter cylindrical portion 6a abut against each other with a predetermined load at a position opposite to the pressing side and the opposite side of the rotation center axis L, the swing angle θ of the upper mold 6 with respect to the center axis becomes a predetermined value. The upper die 6 is guided by the die insert 1b of the lower die 1 while being regulated by the value.

[0006]

However, in the mold having the above-described structure, when the upper die 6 swings and rotates for forging, the convex portion of the upper die 6 and the concave portion of the lower die 1 are formed. The contact surface with the rubbing surface is rubbed while receiving a predetermined load. When the above-mentioned wear occurs, the contact surface between the concave portion and the convex portion recedes outward in accordance with the amount of wear, so that the swing angle of the upper mold 6 increases in proportion to the amount of wear. The lower surface of the large-diameter cylindrical portion 6b of the upper die 6, which is located on the opposite side to the surface, that is, the portion where the work 2 is pressed down, has its outer peripheral side closer to the lower die 1 than the set value, and Becomes larger than the set load, and at the same time, the load on the inner peripheral side becomes smaller than the set load. Then, the work 2 flows toward the inner peripheral side more than the setting due to the above-described reduction, and the load applied to the inner peripheral side is reduced, so that the inner peripheral end of the formed work 2 is warped. I will.

For this reason, when the amount of wear becomes equal to or more than a predetermined value, it is necessary to replace the die insert 1b of the lower die 1 and the like. The present invention has been made in view of the above-described problems, and has as its object to reduce the frictional resistance between the lower mold and the upper mold.

[0008]

In order to achieve the above object, a rotary forging die according to the present invention is characterized in that a lower mold having one of a concave portion or a convex portion at the center of a molding surface is provided on a molding surface. With the upper mold having the other of the concave or convex parts relatively approaching the center of the upper mold or the lower mold in a state where the concave and convex parts are swingably fitted and aligned. A rotary forging die that rotates while being pressed and oscillated to form a ring-shaped work placed between the two dies, wherein a bearing is interposed between the inner surface of the concave portion and the outer surface of the convex portion. It is characterized by wearing.

At this time, it is preferable that a collar made of a cemented carbide is fitted to a peripheral surface of at least one of the rolling wheels of the bearing that can contact with a mold.

[0010]

The concave and convex portions which are fitted so as to be swingable are in contact with each other via the bearing, so that the frictional resistance at least in the rolling direction of the bearing is significantly reduced. Further, since it is the rolling wheel of the bearing that directly contacts the convex portion and the concave portion, for example, when the outer ring of the bearing is fixed to the inner peripheral surface side of the concave portion, there is no friction on the concave portion side and the concave portion has the concave portion. The mold life on the side is greatly extended, and the convex portion rubs against the inner ring of the bearing. However, as described above, the frictional resistance is reduced, and the degree of wear of the convex portion is smaller than in the conventional case. The tool life of the provided side is also extended.

Further, as described in claim 2, when the collar is fitted, the collar comes into direct contact with the mold, so that wear due to friction with the mold occurs on the collar instead of the bearing. However, the collar is easier to replace than the bearing and the mold, and the maintainability is improved. Further, when the collar is made of a cemented carbide, the wear resistance of the collar is improved, and the interval between color exchanges is lengthened.

[0012]

An embodiment of the present invention will be described with reference to the drawings.
It should be noted that the basic structure of the rotary forging device having the mold of the present embodiment has the same mechanism as that of the conventional one. First, the configuration of the mold will be described. As shown in FIG. 2, a ring-shaped die insert 1b is coaxially fitted to a ring-shaped bottom die 1a from below, and the bottom die 1a and the die insert 1b are fitted.
The lower mold 1 is constituted by the above.

The inner peripheral surface of the bottom die 1a is
The upper surface of the die insert 1b constitutes a molding surface for machining the lower surface of the work 2. Also, the inner peripheral surface of the die insert 1b forms a recess of the lower mold 1, and the rolling bearing 3 is formed on the inner peripheral surface.
Are coaxially fitted.

A collar 4 made of cemented carbide is coaxially fitted to the inner ring 3a of the rolling bearing 3. And
The lower mold 1 is fixed to a bed 5. Further, an upper die 6 is disposed above the lower die 1 so as to face the lower die 1. The upper die 6 is composed of a small-diameter cylindrical portion 6a and a large-diameter cylindrical portion 6b coaxial with the small-diameter cylindrical portion 6a and continuous and integrated with the upper end of the small-diameter cylindrical portion 6a.

The small-diameter cylindrical portion 6a is provided with a step along the circumferential direction at an intermediate position so that the lower end portion 6d has a further smaller diameter, and the outer peripheral surface of the lower side 6d is interposed between the bearing 3 and the collar 4. Thus, the diameter of the die insert 1b can be fitted to the inner peripheral surface of the die insert 1b, and the outer peripheral surface of the upper end 6c forms a forming surface for processing the inner peripheral surface of the work 2. The large-diameter cylindrical portion 6
The ring-shaped lower surface of b forms a forming surface for processing the upper surface of the work 2.

The outer periphery of the large-diameter cylindrical portion 6b of the upper die 6 is fixed to a head 7, and the head 7 is connected to driving means (not shown). The driving device rotates the axis M of the upper die 6 around the rotation center axis (vertical axis) L via the head 7 similarly to the conventional rotary forging device. In the rotary forging device provided with the mold having the above-described configuration, first, the ring-shaped work 2 heated to 500 ° C. or higher, preferably 800 to 1200 ° C. by the heating device in the previous process is coaxially transferred to the lower die 1. Place.

Next, the upper die 6 which has been swung and rotated by the driving means is coaxially lowered with the lower die 1 while being guided by a guide member (not shown), and as shown in FIG.
Is inserted into the die insert 1b. The upper die 6 and the lower die 1 are aligned by fitting the die insert 1b and the small-diameter cylindrical portion 6a, and a part of the lower side of the small-diameter cylindrical portion 6a is connected to the die insert via the collar 4 and the bearing 3. 1b, the swing angle θ of the upper die 6 with respect to the rotation center axis is guided to the inner peripheral surface of the die insert 1b while being restricted to, for example, 5 degrees, and the portion in contact with the collar 4 The opposite side of the rotation axis L presses down the work 2.

Then, by rotating while swinging, the work 2 is sequentially pressed down while the upper die 6 rolls along the circumferential direction to form the work. At this time, the small-diameter cylindrical portion 6 of the upper die 6
The contact portion between the a and the collar 4 moves in the circumferential direction relatively to the lower mold 1, but the contact portion between the small-diameter cylindrical portion 6a and the collar 4 only rubs in the vertical direction. The friction in the direction is suppressed, and the collar 4 and the die insert 1
The frictional resistance is greatly reduced by the collar 4 between b.

When the upper die 6 rotates, the lower die 1 also rotates in the same direction due to the contact resistance through the work 2, but as described above, the small-diameter cylindrical portion 6a of the upper die 6 and the lower die 1 Since the frictional resistance with the die insert 1b is small, the rotation speed is different. As described above, the wear of the inner surface of the die insert 1b is suppressed, and the degree of wear of the small-diameter cylindrical portion 6a of the upper die 6 is reduced, so that the life of the mold is improved as compared with the conventional case.

Although the collar 4 is worn, the degree of wear is smaller than that of the conventional die insert 1b, and the collar 4 can be easily replaced, thereby improving maintainability. I do. In the above embodiment, the inner peripheral surface of the collar 4 is provided with a taper of 0 ° 30 ′ in order to improve the adhesion at the contact portion between the small-diameter cylindrical portion 6a of the upper die 6 and the collar 4. In consideration of the peak load applied to the bearing 3 at the time of the rotary forging as shown in FIG. 3, the position of the bearing roller 3b, which is a rolling element, is offset to the peak load position, so that the support by the bearing 3 is stabilized. .

In the above embodiment, the inner race 3a of the bearing 3 is provided.
Although the collar 4 is fitted to the upper ring 6, the upper die 6 of the inner race of the bearing 3 may be directly contacted. In the above embodiment, the lower mold 1 has a concave portion and the upper mold 6 has a convex portion. However, the upper mold 6 has a concave portion and the lower mold 1 has a convex portion. May be adopted. In this case, for example, the bearing 3 and the collar 4 may be provided on the outer peripheral surface of the convex portion of the lower mold 1.

[0022]

As described above, in the rotary forging die of the present invention, one of the upper die and the lower die does not rub and the other die of the upper die or the lower die does not. The resulting rubbing also has the effect that the frictional resistance is greatly reduced, the wear is reduced, and the service life of the upper and lower dies is longer than before.

Further, by fitting the collar, wear of the rolling wheel of the bearing which rubs against one of the molds is prevented, and replacement of the worn collar in place of the rolling wheel is easy, so that maintainability is improved. There is an effect of doing.

[Brief description of the drawings]

FIG. 1 is a side view during processing showing a rotary forging die according to an embodiment of the present invention.

FIG. 2 is a side view showing a rotary forging die according to an embodiment of the present invention.

FIG. 3 is a view showing a bearing and a collar according to the embodiment of the present invention.

FIG. 4 is a side view showing a conventional rotary forging die.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower die 1b Die insert 2 Work 3 Bearing 3a Inner ring 4 Collar 6 Upper die 6a Small diameter cylindrical part

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-133753 (JP, A) JP-A-2-30350 (JP, A) JP-A-61-242738 (JP, A) 135143 (JP, U) JP-A 62-183937 (JP, U) JP-A 62-183938 (JP, U) JP 2-108538 (JP, U) JP-B 52-21982 (JP, B2) (58) Field surveyed (Int.Cl. ⁶ , DB name) B21J 1/00-13/14 B21J 17/00-19/04 B21K 1/00-31/00

Claims (2)

(57) [Claims] 1. An upper mold having a concave portion or a convex portion at the center of a molding surface relatively approached to a lower mold having a concave portion or a convex portion at the center portion of the molding surface. In a state where the concave portion and the convex portion are swingably fitted and aligned, the upper die or the lower die is rotated while being pressed and rocked to form a ring-shaped member placed between the two dies. A rotary forging die for forming a workpiece, wherein a bearing is interposed between the inner surface of the concave portion and the outer surface of the convex portion. 2. The rotary forging die according to claim 1, wherein a collar made of a cemented carbide is fitted on a peripheral surface of at least one of the rolling wheels of the bearing that can contact the die.