JPS61129250A - Production of disc - Google Patents

Abstract

PURPOSE:To prevent the cavity defect due to the tensile stress of the center part and to make a disc non-defective product by making the heated metal blank placed on the rotary lower anvil in a disc shape with pressing by forging in a tapered shape with pressing the center part in order by a metal die. CONSTITUTION:The surface of the heated metal blank 5 is made in the tapered shape with steps by forging the metal blank 5 of on a rotary lower anvil 2 like pressing the front forging part of the center in order by a metal die 3. Therefore the forged part 6 of the first round makes a comparatively large step with the initial time forged part. With repeating this operation it is made to the final plane face disc shape. The center part is always pressed with forging and the cavity defect due to the tensile stress of the center part is prevented. The biased elongation of the outer peripheral part is less compared with the conventional product and the bigger ultrasonic bottom face echo makes the disc or good quality.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a method of manufacturing a metal disk (disk) used for a tube sheet (plate) of a heat exchanger, etc.
In particular, the present invention relates to an improved forging method for manufacturing such disks from steel ingots by press forging.

[Background technology]

Forging is generally a processing method in which a metal material is placed between a mold or the like, compressed and formed into a desired shape, and at the same time improves the mechanical properties of the material.

FIG. 5 shows a general schematic diagram of one aspect of forging. In Fig. 5, 9 is an upper anvil, 1o is a metal material, and lli is a lower anvil.

By the way, conventionally, a disk-shaped disk has been manufactured by such forging.

An example of this method is shown in FIG. 6. To explain an example of this method, a pre-forging disk 12A made of a steel ingot (having an angular shape, etc.) is placed on a rotary table 13, and then 13, move the disk 12B to the upper anvil 14Vc, 1
First, compression forging is performed partially, and then reversal and finishing are performed to obtain a disc forged product 12G.

That is, in this method, as shown in FIG. 7, press forging is carried out sequentially so that the shaded area +5 becomes the surface to be newly rolled.

However, in the disk manufacturing method using the forging method, tensile stress is generated in the center of the disk, resulting in cavity defects, which is not desirable in terms of disk quality. Therefore, the central part of the disk is prone to such problems.

A method has been proposed in which the convex portion is left in its original shape and finally the convex portion is rolled down.

The outline of this method will be explained with reference to Figures 8 to 10.
Disc 16A'ft before the forging process: Place it on the rotary table 17 and use the upper anvil 18 so that the lower surface of the Shinjo per pass becomes the shaded area 19 (Fig. 9), and As shown in FIG. 10, forging is performed with the disk central portion 20 left in a convex shape to obtain a disk forged product 16C.

However, even with this method of leaving the central part of the disk in a convex shape and finally rolling down the convex part 20,
Tensile pressure was applied to the center of the disk, causing a cavity defect, and no solution to the problem was found.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art, and to provide a disk that does not generate tensile stress in the center of the disk, does not cause capacitance defects, and has excellent quality.

[Summary of the invention]

Generally, as seen in the above-mentioned disk, defects are likely to occur in the center of forged products, and eliminating these defects is considered an important problem to be solved.

The inventors of the present invention conducted extensive studies on disc forging using conventional methods, and found that in the past, the lower surface of the Shinjo was kept in the shaded area as shown in Figure 7), or
As shown in Figures 1 and 10, forging was carried out by keeping the lower surface of the Shinjo in the shaded area, leaving the central part in a convex shape, and finally rolling down the convex part. Although forging was carried out to avoid as much as possible the central part of the disk, where this is likely to occur, it was discovered that this would actually apply tensile stress to the central part of the cavity, resulting in cavity defects. It has been found that if forging is performed in such a manner that the tensile stress in the center can be reduced and cavity defects can be reduced.

[Structure of the invention]

The present invention is based on the above knowledge, and the present invention is a method for manufacturing a disk in which a disk-shaped object is obtained by forging from a metal material, in which the material is sequentially forged into a tapered shape while suppressing the center part using an upper anvil. The present invention relates to a method for manufacturing a disk, which is characterized in that a disk-shaped object is obtained.

Next, a method for manufacturing a disk according to the present invention will be described in detail with reference to FIGS. 1 to 4.

As shown in FIG. 2, the disc 1 before forging is placed on a rotary table 2, and the upper anvil 3 is used for press forging, but as shown in FIG. Shaded area 4
is the lower surface of Shinjo for 1 pass of upper anvil 3,
The disk 5 is forged.

That is, as shown in FIG. 3, when the upper anvil 5 (3B) of the second stage is fully rolled after the upper anvil 3 (5A) of the first stage is rolled down in the tangential direction of the disk 5, the shaded area in the figure 4, the central part (center) t of the disk
- Perform forging while holding down.

It is preferable to suppress the central portion so that the suppressing area of the central portion is as wide as possible.

The above-mentioned Fig. 3 illustrates the relationship between the rolling reductions in the first stage and the second stage, and even when rolling down from the fifth stage onwards, the Shinjo lower surface per pass is illustrated by the shaded area 4 in the figure. As if
Forging is carried out so that the center part is held down, preferably so that the holding area of the center part is as wide as possible.

To do this, for each pass of the upper anvil, forging is carried out in a tapered shape so that the rolled surface goes down in accordance with the rolling.

Figure 1 shows the state of the disk manufactured by the forging process shown in the center of Figure 2 after being sequentially forged (rolled down).
- It is shown that due to the six rolling steps, the rolling surface 6 #i at the last stage is the lowest surface.

FIG. 4 is a diagram illustrating disk taper forging as shown in FIG. , YFi reduction amount (W), 2 is the reduction j[I
II) is shown.

As shown in FIG. 4, forging is carried out sequentially according to press cycle 7 with a constant reduction pitch (Xl) so that the leveling height corresponds to the reduction surface bVC of the final stage from the initial height of the disk. That is, as shown in Figure 4, one waveform of the press cycle 7 corresponds to the rolling pitch X, and as shown in Figure 4, one pass (press cycle 7), forging is carried out while gradually pushing.

This rolling pitch (pushing) X is not particularly limited as long as the central portion of the disk is held down and the holding area is preferably made as large as possible, but the rolling pitch is set to 5 wm/bath, for example.

Further, although there is no particular limit to the amount of reduction (as far as the desired purpose of the present invention can be achieved regarding ZJ), the incidence of cavity failure will vary depending on the amount of pushing per bath.

As a result of intensive study on the above-mentioned taper forging, the present inventor found that the rolling reduction rate when the rolling pitch is 5 tm/bath?
Good results were obtained when the rolling reduction was set at 15% (reduction amount Z≦140w/pass).

In addition, in FIG. 4, the amount of reduction YFi, as also shown in the figure, represents the amount of reduction that is half of the amount of reduction -iZ.

After the above-mentioned forging, it is turned over and finished to obtain a disk-shaped article 8 (FIG. 2) used as a tube sheet of a heat exchanger or the like.

〔Example〕

Next, the aA of the present invention will be explained using Examples and Comparative Examples.

Examples 1 to 5 and Comparative Examples 1 to 3 Using a 3500T forging press, taper forging was performed on the steel types shown in Table 1.

Set the reduction pitch to 5 blades/pass, and set the forging dimensions (disc outer diameter, height) as shown in Table 1, and carry out forging.

The obtained disk had no cavity defects and had a large ultrasonic backplane echo value. Table 1 shows the measurement results of this echo value.

In addition, according to the conventional forging method shown in FIG. 8, forging was carried out at a rolling reduction rate of 15% similar to that of the above embodiment, to obtain a disk.

The echo values of the disks are also listed in Table 1.

As shown in Table 1, the products of the examples of the present invention had higher echo values than the comparative products.

〔Effect of the invention〕

(1) According to the present invention, since the disc is forged into a tapered shape while suppressing the central part, a large compressive strain can be constantly applied to the central part of the disc, and the tensile stress in the central part of the disc can be kept small. , the occurrence of cavity defects can be prevented, and a disk without cavity defects can be obtained.

(2) The product according to the present invention has the advantage that the eccentric elongation of the outer peripheral portion is smaller than that of conventional products.

(3) Furthermore, according to the present invention, as shown in the examples, it was possible to obtain a disk of excellent quality with a larger ultrasonic bottom echo (BJ value) than the conventional product.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a tapered forged disk showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of the forging process of the present invention, Fig. 3 is an explanatory diagram of the forging process of the present invention, and Fig. 4 is an explanatory diagram of the forging process of the present invention. Figure 5 is a general schematic diagram of forging, Figure 6 is an explanatory diagram of the conventional forging process, Figure 7 is an explanatory diagram of the conventional forging process, and Figure 8 is another conventional example. Explanatory diagram of the forging process showing the 9th
The figure is an explanatory diagram of a forging process showing another conventional example, and FIG. 10 is a perspective view of a forged product showing another conventional example. 3-・Friday 11 5-・〒”Isk

Claims (1)

[Claims] A method for manufacturing a disk, in which a disk-shaped object is obtained by forging from a metal material, the disk-shaped object being obtained by sequentially forging the material into a tapered shape while suppressing the central part of the material using a mold. Production method.