JPH0616911B2 - 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 pipe manufacturing method using the Eugene Sejournet method, a billet, which is a so-called hollow billet, in which guide holes are previously drilled along the axial center line by machining is used as a material. 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 proposed a technique of using the hollow billet as a material for pipe making (Japanese Patent Application No. 61-227498, domestic priority: Japanese Patent Application No. 62-26990).
Issue = JP-A-63-183715).

[Problems to be solved by the invention]

However, although it has been attempted to perform such expansion processing by cutting or press-fitting 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,
A hollow billet is formed by press-fitting a hole-expansion plug whose outer diameter decreases from the one end to the other end of the hollow billet along the guide hole toward the tip. Simultaneously with the start of press-fitting the hole-expansion plug from one end side of the hollow expansion plug from the other end side of the hollow billet whose outer diameter decreases toward the tip while pressing the hole-expansion plug. The other end of the guide hole is directed to the terminal side while the pressure input of the expanding plug is pressed against the end of the guide hole and applied in the axial direction of the hollow billet against the pressure input of the expanding plug. The inner diameter of the expansion plug to expand, and then pull out the expansion plug from the guide hole or apply a pressure input to the expansion plug before the tips of the expansion plug and the expansion plug interfere with each other. Open up Characterized in that through which the plug the reaming to the other end the end of the hollow billet.

[Action]

The processing method of the present invention requires special means for restraining the movement of the hollow billet in the axial direction by opposing the force input of the expansion plug and the force input of the hole expansion plug. do not do.

〔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.

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, and 4 is a expanding plug. After the hollow billet 2 is heated to a high temperature, the container 1 is loaded at a loading / unloading station (not shown) and is 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 hole expanding plug 3 is lowered from above the container 1, the tip end thereof is engaged with the guide hole 2a, and further lowered as it is to the lower end along the guide hole 2a. Start press-fitting toward the department side.

The hole-expansion plug 3 has a small apex with a small apex, a cone part 3a whose outer diameter decreases toward the tip, and a short column part 3b connected to the bottom of the cone part 3a. The top end is connected to a hydraulic or hydraulic device (not shown). The mandrel 3c is connected to the lower end of the hollow mandrel 3c so that the mandrel 3c can be pressed into the hollow billet 2 by water pressure or a hydraulic device.

When the conical portion 3a and the cylindrical portion 3b of the hole expanding plug 3 are both press-fitted into the hollow billet 2, the expansion plug 4 is inserted from below the container 1 as shown in FIG. Ascending, the tip end is inserted into the guide hole 2a from the lower end of the hollow billet 2 through the shirring 1b, and the expansion plug 4 is pressed into the guide hole 2a as it is as shown in FIG. In this state, the force input of the expanding hole plug 3 and the force input of the expanding plug 4 oppose each other in the upward and downward directions, and the hollow billet 2 is expanded by the pressing force of the expanding plug 4. The movement of the hollow billet 4 in the press-fitting direction can be restrained by the force input of the expanding hole plug 3, and a special means for restraining the movement of the hollow billet 2 due to the pressure input of the expanding plug 4 is unnecessary. .

The expansion plug 4 is also composed of a conical body portion 4a whose outer diameter decreases toward the tip, and a short cylindrical portion 4b connected to the bottom portion thereof, like the expanding hole plug 3, and the bottom portion and the cylindrical portion of the conical body portion 4a.
The diameter of 4b is set to be slightly smaller than that of the shirring 1b. As shown in FIG. 3, when the bottom portion of the conical body portion 4a of the expanding plug 4 is pressed into the guide hole 2a to a position flush with the upper end surface of the shirring 1b, the expanding plug 4 and the expanding hole 4a are expanded. The expansion plug 4 is lowered and pulled out from the guide hole 2a before the tips of the expansion plug 3 interfere with each other. The drive control of the hole expanding plug 3 and the hole expanding plug 4 is performed by, for example, the movement amount detectors attached to the mandrels 3c and 4c, respectively. The positions of the hole expanding plugs 3 and 4 are monitored by detecting the amount of movement of the mandrels 3c and 4c with reference to the initial positions of the mandrels 3c and 4c at the time of, and based on this detection signal. The drive control can be performed. Of course,
Not limited to this, the position may be obtained based on the moving speed and moving time of the mandrels 3c and 4c, and control may be performed based on this.

After the expansion plug 4 is pulled out, the lower end of the guide hole 2a is expanded and formed so that the inner diameter of the lower end of the guide hole 2a increases toward the lower end as shown in FIG. .

The expansion plug 3 continues to be pressed into the lower end side as it is, and penetrates to the lower end of the hollow billet 2 for shirring.
Go down through 1b. At this time, a part of the material is cut between the hole expanding plug 3 and the shirring 1b, and is discharged downward as a slag 5 as shown in FIG.
When the hole expanding process is completed, the container 1 is returned to the loading / unloading station, and the shirring 1b is moved up to the extrusion cylinder.
The hollow billet 2 is lifted and taken out from the container 1, and a new hollow billet 2 is loaded.

In the embodiment described above, the expanding plug 4 is press-fitted into the guide hole 2a after the conical body portion 3a and the cylindrical portion 3b of the expanding hole plug 3 are both press-fitted into the hollow billet 2. The tip of the expansion plug 3 may be pressed into the guide hole 2a at the same time. Further, the case where the expansion plug 4 is press-fitted into the lower end portion of the guide hole 2a up to its maximum diameter portion and then withdrawn downward before interfering with the expansion hole plug 3 has been described. The expansion plug 4 may be allowed to freely fall by releasing the pressure input applied to the expansion plug 4, or may be pushed downward by the expansion hole plug 3.

FIGS. 6 (a) and 6 (b) are explanatory views showing the dimensional specifications of the hole expanding plug 3 and the expanding plug 4, and the cone portions 3a, 4 thereof.
The inclination angles α and β with respect to the axis of a are set according to the workability of the hollow billet 2, the coefficient of friction between the hollow billet 2 and the wall surface of the container 1a of the container 1, and the like. Maximum diameter of opening plug 4 (diameter of cylindrical parts 3b, 4b)
Are equal to each other, the force required for press-fitting depends on α and β, so normally if α ≧ β is set, the force required to press-fit the hole-expansion plug 3 into the guide hole 2a of the hollow billet 2. Is necessarily the same as that of the expansion plug 4, or the latter becomes smaller according to the difference between α and β. Therefore, by setting in this way, the hollow billet 2 can be securely restrained in the axial direction when the expansion plug 4 is press-fitted. However, the force that restrains the hollow billet 2 against the force input of the expansion plug is the sum of the force input of the hole expansion plug and the frictional force between the hollow billet 2 and the wall surface of the housing portion 1a. Of course, if it is sufficiently large, α <β may be satisfied. Immediately after the hole expanding plug 3 starts to be press-fitted into the hollow billet 2, the outer diameter of the hollow billet 2 is increased so that the outer peripheral surface of the hollow billet 2 is accommodated in the container 1a
Is in contact with the wall surface of. Therefore, when the expansion plug 4 starts to be pressed in, a frictional force is generated on the contact surface.

After that, the contact area between the peripheral wall surface of the hollow billet 2 and the wall surface of the accommodating portion 1a of the container 1 increases with the progress of press-fitting of the hole expanding plug 3 and the expanding plug 4. The frictional force also increases. Such frictional force acts as a force that restrains the hollow billet 2 from moving in the press-fitting direction of the expanding plug 4.

Also, the effective lengths of the hole expanding plug 3 and the hole expanding plug 4 (in the axial length direction between the positions A and B and the maximum diameter portions C and D that are in contact with the peripheral edge of the guide hole 2a when engaged in the guide hole 2a). Dimension) he, h
Although t is set relatively by the axial length dimension of the hollow billet 2, the effective length ht of the expansion plug ht is the cone portion of the expansion plug 4 in order to avoid interference with the expansion hole plug 3.
The length from the bottom surface to the tip of 4a is shorter than the length obtained by subtracting the length from the bottom surface to the tip of the conical body portion 3a of the hole expanding plug 3 from the axial length dimension of the hollow billet 2 before processing.

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 the tip end portion to the base end side are The shape may be such that the diameter increases as it goes, and for example, the conical body portions 3a and 4a may each have a warhead shape. In this case, the lower end of the guide hole 2a is expanded and formed into a similar warhead shape.

Next, the conditions for carrying out the method of the present invention will be described with specific numerical values. Create a hollow billet with an outer diameter of 248 mm, an inner diameter of 28 mm, and a length of 600 mm, heat it to about 1200 ° C, and then
I put it in a container equipped with 134.5mm shirring,
Using a hole expansion plug with a cone part inclination angle α of 20 ° and a cylindrical part diameter of 134 mm and an expansion plug of the same specification as this, the hole expansion plug was press-fitted into the hollow billet from its upper end side. At this point, the expansion plug was press-fitted, the expansion plug was pulled out, and then the expansion plug was press-fitted to the lower end of the hollow billet.

In addition, a hole expanding process was performed under the same conditions except that the angle of inclination of the expanding plug was 15 °, and similar results were obtained in this case as well.

In addition, although the above-mentioned embodiment explained the case where the method of the present invention was 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, when the press-fitting of the hole-expansion plug 3 whose outer diameter decreases from the one end side of the hollow billet 2 toward the tip thereof is started at the same time, or the hole-expansion plug 3
During the press-fitting of the hollow billet, the expansion plug 4 whose outer diameter decreases toward the tip is press-fitted from the other end side of the hollow billet 2 to the end of the guide hole 2a and is applied in the lateral direction of the hollow billet. Since the other end of the guide hole 2a is formed so that the inner diameter increases toward the end side while opposing the force input of the hole plug, the hole expanding end portion of the hollow billet 2 during the hole expanding process. It is possible to form the end portion of the guide hole 2a that is expanded in diameter toward the terminal side, and it is possible to significantly improve the yield of the material at the time of the hole expansion processing without increasing the number of steps. The present invention has excellent effects such as the above.

[Brief description of drawings]

1 to 5 are explanatory views showing a working process by the method of the present invention, and FIGS. 6 (a) and 6 (b) are explanatory views of dimensional specifications of the hole expanding plug and the expanding plug. 1 ... Container, 1a ... Container, 1b ... Shirring,
2 ... Hollow billet, 2a ... Guide hole, 3 ... Expanding plug, 4 ... Expanding plug

Claims (1)

[Claims] 1. A hollow billet (2) is press-fitted and penetrated along a guide hole (2a) from one end side to the end of the other end, the hole expanding plug (3) having an outer diameter decreasing toward the tip. In the processing method for expanding the hole of the hollow billet (2), the hole expanding plug (3) is inserted from one end side of the hollow billet (2).
Simultaneously with the start of the press-fitting of the plug, or during the press-fitting of the hole-expansion plug (3), from the other end side of the hollow billet (2), the expansion plug (4) whose outer diameter decreases toward the tip Guide hole
(2a) is press-fitted into the end of the hollow billet (2) and is applied in the axial direction to the expansion plug (4).
Molding the other end of the guide hole (2a) so that the inner diameter expands toward the end side while opposing the pressure input of (3), and then the expansion plug (4) and the expansion plug (3 ) And the tip of the expansion plug (4) before they interfere with each other.
(2a) is pulled out or the pressure input given to the expansion plug (4) is opened, and the expansion hole plug (3) is penetrated to the end of the other end of the hollow billet (2). Hollow billet expanding method.