JPH0616912B2 - Hollow billet expansion method - Google Patents

Description

The present invention relates to a hollow billet hole expanding method performed in the process of producing a seamless tube by a hot extrusion tube forming method.

[Prior art]

When a seamless pipe is manufactured by the hot extrusion manufacturing method using the Eugene Sejournet method, the material used is a billet, which is a so-called hollow billet, in which guide holes are previously drilled along the axial center line by machining. The billet is subjected to a hole expanding process for a hollow billet by a vertical or horizontal press device before being provided to the horizontal press device for pipe making.

When the hollow billet is expanded using a vertical press, for example, a heated hollow billet is usually placed concentrically in a container with shirring on the bottom and expanded from the upper end to the lower end of the hollow billet. This is done by press fitting the hole plug.

By the way, in such a hole expanding process, the outer diameter of the hollow billet is regulated by the inner peripheral wall of the container, so that the material reduced by the hole expansion appears as a change in length, but It is not converted into length, but part of the material is extruded by the hole expansion plug, cut off when passing through the shirring, discharged to the outside as it is, and becomes a waste, which cannot be ignored in terms of material yield. Many.

As a countermeasure against this, in the above-mentioned case where the end that should be the end of the hole expanding process, that is, the vertical press is used, the end of the guide hole at the lower end of the hollow billet is expanded in advance toward the end side. The present inventors have already applied for the technology of using the hollow billet as a material for pipe making (Japanese Patent Application No. 61-227498, Japanese priority: Japanese Patent Application No. 62-26990).
Issue = JP-A-63-183715).

[Problems to be solved by the invention]

However, although such expansion processing has been conventionally attempted to be performed by cutting or press fitting of a plug or the like, there has been a problem that an increase in man-hours and steps associated with this has been unavoidable.

As a result of experiments and researches conducted by the present inventors to efficiently perform the expanding process for one end of the guide hole at the hole expanding end of the hollow billet, as a result, it is efficient to perform the original expanding process for the hollow billet. It was found to be a target.

The present invention has been made on the basis of such findings, and its object is to perform expansion processing for the guide hole end portion at the hole expansion processing end portion of the hollow billet without increasing man-hours and steps. It is to provide a method for expanding the hole of a hollow billet that enables the above.

[Means for solving problems]

In the hollow billet hole expanding method according to the present invention, the hollow billet 2 is loaded into the container 1 with one end abutted against the shirring 1b, and the other end of the hollow billet 2 is inserted. The expansion plug 4 whose outer diameter decreases from the one end side of the hollow billet 2 to the one end of the guide hole 2a while pressing and fixing the portion with a tubular stem 7
After press-fitting and opening one end of the guide hole 2a so that the inner diameter increases toward the end side, the stem 7 is retracted or retracted, and then the hollow billet 2 Guide hole from the other end to the one end
The expanding hole plug 3 whose outer diameter is reduced toward the tip along 2a is press-fitted and penetrated.

[Action]

In the present invention, the expansion plug and the tubular stem are combined, and the expansion plug is first press-fitted into one end of the hollow billet to form the guide hole 2a in a tapered hole over substantially the entire length. The plug for expanding the hole is press-fitted from the other side to the one end along the guide hole of the hollow billet so that both plugs do not interfere with each other, so even for short hollow billets. It is applicable, and at the same time, the amount of slag can be greatly reduced.

〔Example〕

Hereinafter, a case where the method of the present invention is carried out by using a vertical press device will be specifically described with reference to the drawings.

FIGS. 1 to 5 are explanatory views showing an embodiment of the method of the present invention, in which 1 is a container, 2 is a hollow billet, 3 is a hole expanding plug whose outer diameter is reduced toward the tip, and 4 is the same. An expansion plug whose outer diameter decreases toward the tip, and 7 indicates a stem. After the hollow billet 2 is heated to a high temperature, it is loaded into the container 1 at a loading / unloading station (not shown) and transferred to the press center in the mode shown in FIG.

The container 1 is provided with a cylindrical accommodating portion 1a having an inner diameter slightly larger than the outer diameter of the hollow billet 2, and a shirring 1b which also serves as a support for the hollow billet 2 is arranged at the bottom thereof so as to be movable up and down. The hollow billet 2 loaded in the accommodating portion 1a is positioned concentrically with the accommodating portion 1a and the shirring 1b with its lower end supported by the upper surface of the shirring 1b.

When the hollow billet 2 is positioned at the press center, the stem 7 and the hole-expansion plug 3 supported inside the container 1 are lowered from above the container 1, and the lower end portion of the stem 7 is brought into pressure contact with the upper end surface of the hollow billet 2. The movement of the hollow billet 2 in the container 1 in the axial direction and the movement in the thickness direction intersecting with the movement are restricted. The stem 7 is formed in a cylindrical shape, the outer diameter is slightly smaller (about 1 mm) than the inner dimension of the housing portion 1a of the container 1, and the inner diameter is set slightly larger than the maximum diameter portion of the hole expanding plug 3. The upper end is connected to a hydraulic or hydraulic device (not shown).

If the pressure contact time of the stem 7 against the hollow billet 2 becomes long, the temperature of the hollow billet 2 may decrease, which may hinder the hole expanding process described later. The smaller the area, the better. However, if it is too narrow, the portion of the upper end surface of the hollow billet 2 that does not come into contact with the stem 7 rises during expansion processing, and a step is formed on the upper end surface of the hollow billet 2.

Therefore, it is desirable to make the area of the lower end surface of the stem 7 narrow within a range in which no step is formed on the upper end surface of the hollow billet 2.

On the other hand, the hole-expanding plug 3 is provided with a conical body portion 3a having a small apex and a short cylindrical portion 3b connected to the bottom portion, and a mandrel whose upper end portion is connected to a hydraulic or hydraulic device (not shown).
The stem 7 is housed and held in the lower end portion of the stem 7 in a state of being connected to the lower end portion of 3c.

When the hollow billet 2 is restrained in the axial direction by the stem 7, the expanding plug 4 is raised from below the container 1 as shown in FIG. 2, and its tip is guided from the lower end of the hollow billet 2 through the shirring 1b. Enter the hole 2a,
As shown in FIG. 3, the expansion plug 4 is pressed into the end of the guide hole 2a.

The expansion plug 4 has the same cone portion 4a as the expansion hole plug 3.
And a short cylindrical part 4b connected to the bottom of the conical part.
The diameter of the bottom portion of 4a and the cylindrical portion 4b is set to be slightly smaller than that of the shirring 1b. As shown in FIG. 3, the bottom of the conical portion 4a of the expanding plug 4 is the shirring 1b.
When pressed into the guide hole 2a to a position flush with the upper end surface of the, the expanding plug 4 is immediately lowered and pulled out from the guide hole 2a.

The press-fitting depth of the expanding plug 4 with respect to the lower end of the hollow billet 2 may be appropriately determined in consideration of the effect of reducing the amount of slag, but if the press-fitting depth is higher than the position shown in FIG. Since the hole at the lower end of 2 has a cylindrical shape, it is desirable to reach the maximum position.

The lower end portion of the guide hole 2a after the expansion plug 4 is pulled out is expansion-molded so that the inner diameter increases toward the lower end as shown in FIG. When the withdrawal of the expansion plug 4 is completed, the stem 7 is elevated or after the elevation and the withdrawal are completed, the press-fitting of the expansion hole plug 3 is started.

The hole expanding plug 3 is pressed and penetrated along the guide hole 2a from the upper end portion to the lower end portion of the hollow billet 2 as it is, and is further lowered therethrough through the shearing 1b. At this time, a part of the material is cut between the hole expanding plug 3 and the shirring 1b and discharged downward as a slag 6 as shown in FIG. When the hole expanding process is completed, the container 1 is returned to the loading / unloading station and the extrusion cylinder is shirred 1b.
And raise the hollow billet 2 to raise the container 1
Then, insert a new hollow billet 2.

In the above embodiment, the expansion plug 4 is press-fitted into the lower end of the guide hole 2a up to its maximum diameter portion and then pulled out downward. However, the pressure applied to the expansion plug 4 is simply applied. The expansion plug 4 may be allowed to fall freely by releasing the input, or the expansion plug 3 may be pushed downward.

It should be noted that the dimensional specifications of each part of the hole expanding plug 3 and the expanding plug 4 are not particularly limited, and the dimensional specifications of the hollow billet, the hole expanding process, etc. are prevented so that the two plugs do not interfere with each other. It should be set in consideration of.

Further, the case where the expansion plug 3 and the expansion plug 4 are both composed of the conical body portions 3a, 4a and the columnar portions 3b, 4b has been described, but the present invention is not limited to this, and for example, the conical body portions 3a, 4a. Each may be formed into a warhead type or the like. In this case, a guide hole at the lower end of the hollow billet 2 which is the end of the hole expanding process.
The lower end of 2a will be expanded into a similar warhead type.

Further, although the above-described embodiment has been described with respect to the case where the method of the present invention is carried out by using the vertical pressing device, it goes without saying that the same can be carried out by using the lateral pressing device.

〔effect〕

As described above, in the method of the present invention, it is possible to expand the hole without changing the direction of the hollow billet and without causing interference between the hole expanding plug and the expanding plug even for a short hollow billet. The present invention has an excellent effect such that the material yield can be greatly improved in combination with the fact that the amount of slag can be greatly reduced.

[Brief description of drawings]

1 to 5 are explanatory views showing an implementation state of the method of the present invention. 1 ... Container, 2 ... Hollow billet 3 ... Expanding plug, 4 ... Expanding plug 6 ... Slag, 7 ... Stem

Claims (1)

[Claims] 1. A hollow billet (2) is loaded into a container (1) with one end of which is in contact with the shirring (1b), and the other end of the hollow billet (2) is inserted. An expanding plug whose outer diameter decreases from the one end of the hollow billet (2) to the one end of the guide hole (2a) while pressing and fixing with the tubular stem (7). Press (4) into the guide hole
(2a) after expanding one end of the stem (7) so that the inner diameter is enlarged toward the end side, while retracting the stem (7), or after retracting, the other of the hollow billet (2) A hollow billet expanding hole, characterized in that a hole expanding plug (3) whose outer diameter decreases from the end side to the one end along the guide hole (2a) toward the tip is inserted through. Processing method.