JPH08132171A - Forging method for ring-shaped products - Google Patents

Abstract

PURPOSE: To improve material transfer formability and yield and to suppress generation of inner peripheral burr. CONSTITUTION: When forming is executed so that material is transferred to the outer periphery of ring shape part by rotary forging, a forming die is set with selecting a value of upper die rotating axis offset ratio δ/d to 0.01-0.3 and forming is executed. Here is δ: offset quantity (mm) of intersecting point between material upper face and upper die rotating axis from lower die center axis in upper die rolling down direction, d: inner diameter (mm) of ring shape part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forging a ring-shaped product such as a ring gear material.

[0002]

2. Description of the Related Art In recent years, it has been possible to produce disk-shaped products because of its advantages such as small processing force, downsizing of machine and die structure, less vibration and noise, and smaller die surface friction, which improves machining limit. In contrast, the number of cases where the rotary forging method is used has increased. In this rotary forging method, there are used two types of methods, from an upper die rolling type to an oscillating die type (Fig. 1 (a)) and a lower die rotating type (Fig. 1 (b)) as shown in Fig. 1. Regarding the positional relationship between the upper die 4 and the lower die 3, in the swing die type rotary forging press, the upper die rotary shaft 2 and the upper die revolution shaft 1 (which coincide with the lower die central axis) are covered. The molding material (hereinafter simply referred to as material) 5 is set so as to intersect on the upper surface, and in the lower die rotary type rotary forging press, the upper die rotation shaft 2 and the lower die center axis 1 are arranged so as to intersect on the upper surface of the material 5. Is set.

Although the rolling type of the upper die 4 is different, the relative movement of the material 5 and the upper die 4 and the lower die 3 is the same in any type of rotary forging press, and the purpose of setting as described above is It is to minimize the slippage of the mold 4 and the material 5.

By the way, recently, an attempt has been made to use the rotary forging method, which has been used for molding a disk-shaped product, for molding a ring-shaped product, but an upper mold and a lower mold for rotary-forging a ring-shaped product. As for the positional relationship, the same as in the case where the disk-shaped product is rotationally forged as shown in FIG. 2, and therefore various problems have occurred.

That is, in molding a ring-shaped product,
When shape is formed by moving meat (material) to the outer periphery,
When the outer peripheral part is filled with the material to some extent, the degree of material restraint by the mold increases, and conversely the material flows to the inner peripheral part. Burrs will occur. For this reason, there is a problem in that the yield is reduced and the inner peripheral burr must be removed.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to improve the wall movement formability to the outer peripheral portion and to improve the yield and the occurrence of inner peripheral burrs when a ring-shaped product is formed by the rotary forging method. It is an object of the present invention to provide a rotary forging method for a ring-shaped product that realizes suppression.

[0007]

The present inventor has obtained the following findings as a result of earnest studies for solving the above problems. There are two types of rotary forging presses, a swing die type and a lower die rotating type. As described above, the relative movement of the material and the lower and upper dies is the same in any type of rotary forging press. Therefore, the following description will be represented by the lower mold rotation type.

When a ring-shaped product is formed by the rotary forging method, in the conventional method, as shown in FIG.
Is at the position where the slip between the upper die 4 and the material 5 is the smallest,
That is, the upper mold rotation axis 2 and the lower mold center axis 1 are set so as to intersect with each other on the upper surface of the material 5. The tangential velocity of the material 5 and the tangential velocity of the upper die 4 in this case are compared and shown in FIG. 3. However, when the elongation of the material due to the rolling reduction is neglected, there is almost no relative velocity between the upper die and the material. Therefore, little outward force acts on the material.

On the other hand, the following knowledge was obtained by shifting the intersection of the upper mold rotation axis and the material upper surface from the lower mold center axis, which will be described in detail later, in the "upper mold pressure lower surface direction".

That is, by shifting the intersection of the upper mold rotating shaft and the upper surface of the material from the central axis of the lower mold in the "upper die pressure lower surface direction", an outward force acts on the material to promote an outward metal flow. As a result, it is possible to suppress the formation of inner peripheral burrs by improving the wall transfer moldability to the outer peripheral portion and conversely suppressing the metal flow in the inner peripheral direction.

The gist of the present invention based on the above findings is the following method for forging a ring-shaped product.

The value of the upper mold rotating shaft eccentricity ratio δ / d, which indicates the positional relationship between the upper mold rotating shaft and the lower mold center axis when the shape is formed by moving the meat to the outer peripheral portion of the ring-shaped product by rotary forging. The method for forging a ring-shaped product is characterized by setting a molding die with 0.01 to 0.3.

However, δ: The amount of deviation (m in the "upper die pressure lower surface direction") from the lower die center axis at the intersection of the upper surface of the material and the upper die rotation axis.
m) d: Inner diameter of ring-shaped product (mm)

[0014]

The present invention will be described in detail below with the operation and effect thereof represented by the lower mold rotation system.

First, as shown in FIG. 4 (the upper die is not shown), "the intersection point B between the upper die rotating shaft 2 and the material upper surface P2 is shifted from the lower die center axis 1 in the" upper die pressure lower surface direction ". That is, "the intersection point B is a plane including the lower mold center axis 1 and the upper mold rotation axis 2 and is perpendicular to the lower mold center axis 1 and the upper mold is relative to the lower mold center axis 1. D1 which is the direction in which the rotary shaft 2 is inclined
It is defined as "to shift in the direction of."

When the intersection of the upper mold rotating shaft and the upper surface of the material is moved from the central axis of the lower mold in the "upper die pressure lower surface direction" according to the above definition, as shown in FIG. Differences in tangential velocities result in relative velocities, which exert an outward force on the material. For this reason, the outward metal flow of the material is promoted, so that the wall transfer formability to the outer peripheral portion is improved. On the other hand, since the metal flow in the inner peripheral direction is suppressed, the occurrence of inner peripheral burr is suppressed.

However, in this case, the upper die rotating shaft eccentricity ratio δ / d (where,
δ: The amount of deviation (mm) of the intersection of the upper surface of the material and the rotation axis of the upper mold from the center axis of the lower mold in the “upper mold pressure lower surface direction”, d: the inner diameter (mm) of the ring-shaped product is 0.01. If it is less than 1.0, the effect of moving the center of rotation of the upper die hardly occurs, and if it is more than 0.3, the speed mismatch between the material and the upper die becomes too large, so the material moves from the lower die in the initial stage of rolling. Then it rises and normal processing becomes impossible. Therefore, the value of the upper mold rotating shaft eccentricity ratio δ / d is limited to the range of 0.01 to 0.3.

[0018]

[Example] The outer diameter of S45C (JIS G 4051 (1979)) is φ4.
A steel piece with a diameter of 00 mm and an inner diameter of φ240 mm was heated to 1200 ° C. and then the scale was removed, and then, under various conditions, a steel ring-shaped product having a raised outer peripheral portion as shown in FIG. I investigated the situation. In this forming, the meat at the inner peripheral portion of the ring-shaped material shown by the broken line in FIG. 6 is pressed down and moved to the outer diameter side, and processed into the finish shape shown by hatching. Table 1 shows the molding test conditions and results of the rotary forging method.

From the results shown in Table 1, also, when the upper mold rotary shaft eccentricity ratio δ / d is within the range defined by the present invention, the outer peripheral part has good build-up formability and the occurrence of inner peripheral burrs. It is clear that it shows almost no good moldability.

On the other hand, when the upper mold rotating shaft eccentricity ratio δ / d is less than the range of the present invention, inner peripheral burrs are generated and outer peripheral part is lacked (test number 2). When the rotating shaft eccentricity ratio δ / d exceeded the range of the present invention, the material was extruded from the mold at the initial stage of the rotary forging and the forging was impossible (Test No. 6).

[0021]

[Table 1]

[0022]

According to the method of the present invention, the thickness of the outer peripheral portion is suppressed to promote the movement of the wall to the outer peripheral portion to improve the formability (for example, build-up formability) and suppress the occurrence of the inner peripheral burr. However, since a ring-shaped product having a sound shape can be stably molded with a high yield, the industrial effect of the ring-shaped product molding method is extremely large.

[Brief description of drawings]

FIG. 1 is a diagram showing a positional relationship between an upper die and a lower die in a rotary forging method. The upper die rolling type is (a) a swing die type, and (b) is a lower die rotating type.

FIG. 2 is a diagram showing a positional relationship between an upper die and a lower die in a conventional rotary forging method for ring-shaped products.

FIG. 3 is a diagram showing a comparison between the tangential direction speed of the material and the tangential direction speed of the upper mold when the upper mold rotation axis and the lower mold center axis are set so as to intersect with each other on the upper surface of the material.

FIG. 4 is an explanatory diagram of shifting an intersection between an upper mold rotation axis and a material upper surface from a lower mold center axis in an “upper mold pressure lower surface direction”.

FIG. 5 compares the tangential velocity of the material and the tangential velocity of the upper die when the intersection point between the upper die rotation axis and the upper surface of the material is set by shifting from the center axis of the lower die to “upper die pressure lower surface direction”. FIG.

FIG. 6 is an explanatory diagram of a ring-shaped product whose production is tried in an example.

[Explanation of symbols]

1: Lower mold center axis, 2: Upper mold rotation axis, 3: Lower mold, 4: Upper mold, 5: Material, B: Intersection point between upper mold rotation axis and material upper surface, P
1: a plane including the lower mold center axis and the upper mold rotation axis, P2: the upper surface of the material, P3: the material pressure lower surface of the upper mold, D1: a direction in which the intersection of the upper mold rotation axis and the material upper surface is displaced from the lower mold center axis, δ: amount of deviation (mm) from the center axis of the lower mold at the intersection of the material upper surface and the upper mold rotation axis, d: inner diameter of the ring-shaped product (mm),

Claims (1)

[Claims] 1. An upper mold rotating shaft eccentricity ratio δ / d showing a positional relationship between an upper mold rotating shaft and a lower mold center axis when shape is formed by moving meat to an outer peripheral portion of a ring-shaped product by rotary forging. A method of forging a ring-shaped product, which comprises setting a molding die with a value of 0.01 to 0.3 and molding. However,
δ: Amount of deviation of the intersection of the upper surface of the material and the upper mold rotation axis in the "upper mold pressure lower surface direction" from the lower mold center axis (mm) d: Inner diameter of the ring-shaped product (mm)