JPH0857571A - Rotary forging method of thin thickness disk - Google Patents

Abstract

PURPOSE: To obtain the rotary forging method of thin thickness disk not having material floating from a lower die during forming and not generating underfill and outer peripheral burr in the lower die side of formed bode. CONSTITUTION: In executing forming of a disk by rotary forging, forming dies are set so that a rotating axis of upper die and a revolving axis around the whole die of upper die satisfy the inequality of 0.01<=δ/d<=-0.3, here, δ: a deviation quantity (mm) between a rotating axis of upper die and a revolving axis around the whole die of upper die on the upper face of material in the opposite direction of upper die reduction face, (d): an outer diameter (mm) of thin thickness disk, and then forming is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary forging method for producing a thin disk.

[0002]

2. Description of the Related Art The rotary forging method is a technology for processing the entire material to a desired shape by repeating partial processing, unlike processing the entire material at once by applying a large load. It is known as a plastic working means capable of forming with a relatively small working force. In particular, the rotary forging method is an extremely effective production means for the production of disc materials, etc., which are produced in small quantities for a wide variety of products. Currently, as this rotary forging method, the lower die is driven to rotate and the upper die is driven. The "lower mold rotating type" for forming and the "oscillating die type" for fixing by lowering the lower mold and swinging the upper mold are in practical use.

Whichever type of rotary forging method is applied, the material to be molded and the relative motion of the lower die and the upper die are the same. However, when a disk is formed by this rotary forging method, The setting of the forming die is performed as follows to minimize the slippage between the upper die and the material. That is,
When a lower die rotary type rotary forging machine is used, as shown in FIG. 2, the upper die rotation axis and the lower die rotation axis (which coincide with the revolution axis of the upper die) are formed so as to intersect at the material upper surface position. The mold is set. On the other hand, when an oscillating die type rotary forging machine is used, the result is the same as in the case of the lower die rotating type, but in the forming die so that the upper die rotating shaft and the upper die revolution axis intersect on the upper surface of the material. Settings are made.

However, in addition to downsizing the equipment, noise,
Even in the rotary forging method, which is useful because of its low vibration, the following problems have been pointed out, for example, when molding a thin disk. a) With a thin disk shape, the material easily floats on the side opposite to the side where the material is pressed down by the upper die (the side opposite to the "contact surface between the upper die and the material" shown by hatching in Fig. 2). ,
In extreme cases, it may get out of the mold and cause scratches and flesh. b) When the “diameter / thickness ratio” of the disc becomes large (thinner becomes thinner than the disc diameter), the center of the disc is thinned (center-thinning phenomenon), and in the worst case, there is a hole in the center. Evil. c) The rotary forging method has a propensity to have excellent moldability on the upper die side but poor formability on the lower die side, and therefore a disk shape having a rim on the outer periphery (see, for example, FIG. 5 described later).
In the case of molding, flesh is likely to occur at the lower die side corner of the rim (this tendency is more remarkable for thin-walled discs). Moreover, if the rim is forcibly filled, a large amount of burr is generated on the outer circumference.

Therefore, the object of the present invention is to prevent the material from rising from the lower mold during molding.
The object of the present invention is to establish a rotary forging forming means for a thin-walled disc that suppresses the occurrence of the above-mentioned center-thinning phenomenon and that does not cause a thin wall on the lower die side of a molded product or an outer peripheral burr.

[0006]

The present invention has been completed in view of the results of the research conducted by the present inventor, who have been eager to achieve the above-mentioned object, and states, "When forming a disk by rotary forging, The upper die rotation axis and the upper die revolution axis are expressed by the formula 0.01 ≤ δ / d ≤ 0.3 By setting and forming the mold so that the above conditions are satisfied, the material rises from the lower mold during molding,
A major feature is that it enables stable production of sound products by suppressing the lack of wall thickness defects in molded products and the peripheral burr of molded products. "

As described above, the present invention is different from the conventional method in which the forming die is arranged so that the upper die rotating shaft intersects the upper surface of the material on the upper die revolution shaft (lower die rotating shaft). The feature is that the intersection of the rotation axis and the upper surface of the material is displaced in the "direction opposite to the upper die pressure lower surface". That is, as shown in FIG. 3 (the upper die is not shown), the upper die rotation axis A ₂ and the material upper surface P
To shift the intersection point B with ₂ in the “direction opposite to the upper die pressure lower surface” means that the plane P ₁ including the upper die revolution axis (lower die rotation axis) A ₁ and the upper die rotation axis A ₂ is moved to the upper die revolution axis. (Lower mold rotation axis) D ₁ at right angle to A ₁ , and upper mold revolution axis (lower mold rotation axis) A ₁
On the other hand, the upper die mainly shifts the material in the direction D ₂ opposite to the surface P _{3 on} which the material is pressed.

[0008]

The present invention will be described in detail below together with its operation with reference to the drawings. However, as mentioned earlier, there are two types of rotary forging methods: "lower die rotating type" and "oscillating die type". Regardless of which type is used, the relative movement between the material and the lower die and the upper die Are the same and do not influence the present invention,
The following description will be represented by the lower mold rotation type.

The above-mentioned FIG. 2 shows that, when a lower die rotary type rotary forging machine is used to form a disk, the upper die rotary shaft (that is, the center of the rotary shaft) is most likely to slide on the material surface. FIG. 3 is a schematic view showing a molding method according to a conventional method of “setting at a reduced position, that is, a position on the upper surface of the material that intersects with the lower mold rotation axis”. In this case, ignoring the elongation of the material, the tangential velocities of the material and the upper mold are the same as shown in the figure, and there is no difference. Thus, in the past, even in the case of the "lower mold rotating type", the "oscillating die type"
Even in the above case, when the elongation of the material due to the rolling reduction was ignored, the rotary forging of the disk was carried out in the state where there was almost no relative speed difference between the upper die and the material.

However, the present inventor has discovered that, contrary to the above-mentioned conventional method, when the rotational center position of the upper mold is moved, the formability of the disk changes. That is, as shown in FIG. 1, the upper die rotation axis is opposite to the lower die rotation axis (which coincides with the upper die revolution axis) from the upper die pressure lower surface (the surface where the upper die and the material come into contact). Moving in the direction of causes a difference in the tangential velocity between the material and the upper die, which causes an inward force to act on the material and suppress deformation in the outer peripheral direction. By suppressing the deformation in the outer peripheral direction, a part of the material moves in the lower mold direction without flowing in the outer peripheral direction, and the filling property of the lower mold is improved.

Therefore, if the center of rotation (viewpoint axis) of the upper die is moved with an appropriately adjusted amount of movement, the lower die, which has been particularly problematic when molding a disc having a rim on the outer periphery, The filling of the rim is improved, and rotary forging without rim wall thickness or peripheral burrs is possible.
Moreover, in this case, the surface of the upper die that presses down the material increases beyond the center of the material, so that "lifting of the material from the lower die" during molding is also prevented.

In this case, however, the amount of deviation between the upper die rotating shaft and the upper die revolution shaft (= lower die rotating shaft) in the direction opposite to the upper die pressure lower surface at the material upper surface position is δ, and the outer diameter of the thin disk is If d is less than 0.01, there is almost no effect of moving the center of rotation of the upper die. If the above value is greater than 0.3, the material moves from the lower die during rolling, which is normal. In the present invention, the above δ
/ D is set to be in the range of 0.01 to 0.3.

Next, the effects of the present invention will be described more specifically by way of examples.

EXAMPLE First, a high carbon steel billet having an outer diameter of 450 mm as shown in FIG. 4 was heated to 1250 ° C., scale was removed, and a 3000 ton press was installed for centering.
A part of the boss portion as shown in (1) was molded.

Then, this intermediate material is subjected to a rotary die forging machine of a lower die rotary type, and the "outer diameter d of the thin disk" and "on the upper surface of the material of the upper die rotary shaft and the lower die rotary shaft (= upper die revolution shaft)". Rotation forging was performed by changing the ratio of the upper die pressure lower surface and the deviation amount δ ″ in the opposite direction, and the outer shape as shown in FIG. 6 was 860 mm.
We tried to form a disc material with high carbon steel rim. The molding test conditions and results are shown in Table 1.

[0015]

[Table 1]

From the results shown in Table 1, if the upper die rotation center (rotation axis) movement amount is within the range specified by the present invention,
It can be seen that even in the case of forming a thin-walled disc with a rim, the occurrence of peripheral burrs and the lifting of the material at the initial stage of rotary forging are both suppressed, and good formability is exhibited. On the other hand, when the amount of movement of the upper die rotation center is outside the range specified in the present invention, outer peripheral burrs are generated, and rims have a lack of wall thickness, or the material protrudes from the die at the initial stage of rotary forging and cannot be rolled. I understand.

[0017]

[Summary of Effects] As described above, according to the present invention, it is possible to stably form a thin-walled disk having a healthy shape while suppressing the inconvenience such as the material being lifted from the lower die during forming by rotary forging and the occurrence of peripheral burrs. It brings about useful effects in industry.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a rotary forging method according to the present invention.

FIG. 2 is a schematic explanatory view of a conventional rotary forging forming method.

FIG. 3 is an explanatory view of “a direction opposite to an upper die pressure lower surface”.

FIG. 4 is an explanatory diagram of a steel slab used as a raw material in an example.

FIG. 5 is an explanatory view of the shape of an intermediate material obtained by press forming a raw steel piece.

FIG. 6 is an explanatory view of the shape of a disk material with a rim, the manufacture of which is attempted in Examples.

Claims (1)

[Claims] 1. When forming a disk by rotary forging, the upper die rotation axis and the upper die revolution axis are expressed by the formula 0.01 ≤ δ / d ≤ 0.3. A rotary forging method for a thin-walled disk, which comprises setting a molding die so as to satisfy the above conditions, and performing molding.