JPS6327845Y2 - - Google Patents

Description

[Detailed description of the invention] The invention is one of the methods for manufacturing seamless pipes. This invention relates to improvements in the rolls of inclined rolling mills such as piercers and elongators used in the so-called Mannesmann perforation method.

In general, when manufacturing seamless pipes by the inclined rolling method, a piercer is used as a means for perforating holes along the axis of a round steel piece, or a hollow shell is expanded by drilling along the axis of a round steel piece. An elongator (also referred to as a second piercer) used for reducing the diameter and thickness of a round steel piece or hollow shell is used to rotate a round steel piece or hollow shell around its axis and move it in the axial direction, so-called spiral movement. Alternatively, barrel type rolls are used to perform diameter expansion and thinning rolling. The general configuration of a conventional barrel type roll is used, for example, in an elongator. The general construction of conventional barrel type rolls, such as those used in elongators, is as shown in Figures 1, 2, and 3.
In the figure, 30 and 30r are rolls, 40 is a plug, and rolls 30 and 30r are mandrel M
On both sides of the plug 40 installed horizontally at the tip of the
They are arranged equidistantly apart from the plug 40, respectively. Each of the rolls 30, 30r is formed as a rotating body symmetrical about the axial center line, and is provided with a gorge part 31 having the maximum diameter in the middle part in the axial direction, and on both sides of the gorge part 31 in the axial direction. It has an inlet side surface 32 and an outlet side surface 33 each having a truncated conical shape, the diameter of which gradually decreases toward both ends.
Its shape is as shown in FIG.
Lg, the angle of the inlet side 32 with respect to the axis -;
That is, it is specified by giving the angle of the outlet side surface 33 with respect to the inlet face angle α and the axis -, that is, the outlet face angle β.

Both rolls 30, 30r are positioned with their axes parallel to the axis of the plug 40 in plan view, and in side view, one roll 30, 30r has its inlet end facing upward, and the other roll The rolls 30r each have a plug 40 with its outlet end facing upward.
at a predetermined angle θ in opposite directions above and below with respect to the axis of
The hollow shell H is placed in a tilted state, and is pressed against the outer circumferential surface of the hollow shell H, and is driven to rotate in the same direction as shown by the arrow by a drive source (not shown).

The hollow shell H is guided from the top between the rolls 30 and 30r by a guide shaft (not shown), is bitten between the gorge parts 31 and 31 of both the rolls 30 and 30r, and is rotated around the axis. The plug 40 is penetrated into the core hole while being moved in the axial direction, so-called spiral movement, and is elongated and rolled by the plug 40 and the rolls 30, 30r.

However, when rolling with an elongator using such rolls 30, 30r and piercing with a piercer, pit flaws and spiral flaws occur frequently on the inner surface of the tube, and local wear occurs on the plug 40, causing the plug to become damaged. It had drawbacks such as a significantly short lifespan.

The present inventors conducted an experimental study on the relationship between the inner surface flaws, local wear of the plug, and the shape of the roll as described above.
The fact that 1 is a ridge line that is the intersection of the inlet side surface 32 and the outlet side surface 33 causes discontinuity in rolling, an excessive reduction in wall thickness, frequent internal defects, and local wear on the plug. We discovered that this is a major cause of this.

The present invention was made based on such knowledge, and its objectives are the length dimension in the axial direction, the gorge formation position in the axial direction, the gorge diameter, the angle of the inlet side surface, and the angle of the outlet side surface. A roll of an inclined rolling mill having a shape specified by giving a shape, the center of which is on a plane including the gorge and perpendicular to the axis, passing through the end of the inlet side, and The gorge portion is formed by forming the space between the point of contact between the circular arc and the reference line on the outlet side surface and the reference line to the inlet end into the shape of a rotating body in which the generatrix of the circular arc is drawn around the axis. The inlet and outlet sides on both sides of the plug are continuous with a gently curved surface, eliminating rolling discontinuities and excessive wall thickness reduction, preventing local wear of the plug, and improving the inner surface properties of the tube. An object of the present invention is to provide a roll for an inclined rolling mill that can be significantly improved.

Hereinafter, the present invention will be specifically explained based on drawings showing embodiments thereof. FIG. 4 is a perspective view showing a roll of an inclined rolling mill according to the present invention (hereinafter referred to as the proposed product);
Fig. 5 is also a partial explanatory diagram of the proposed product, and the proposed product is configured as a rotating body whose generatrix lines M ₁ and M ₂ are drawn around the axial center line, and the diameter is maximum at the midpoint in the axial length direction. A gorge portion 11 is provided, and on both sides of the gorge portion 11 are provided an inlet side surface 12 and an outlet side surface 13 whose diameters decrease toward both ends in the axial direction. The bus lines M ₁ and M ₂ are determined as follows with reference to a conventional roll as shown in FIG. 3 (referred to as a conventional product). As mentioned above, the reference roll has the following dimensions: the dimension L in the axial direction, the gorge formation position Lg in the axial direction, the gorge diameter D, the entrance surface angle α of the entrance side surface 32, and the exit side surface 32 as shown in FIG. By giving an exit face angle β of It has a truncated conical shape whose diameter gradually decreases toward both ends in the axial direction, and has an inlet side surface 32 and an outlet side surface 33 that are inclined by α and β, respectively, with respect to the axial center line. is specified. In a roll having such a shape, the generatrix M ₁ extends along the outlet side surface 33 as described above in its inclination direction, and is inclined at an angle β equal to the outlet surface angle with respect to the axis, at a midpoint c ( 5) as shown in FIG. 5, which is a part of a reference line Y extending from the end b of the outlet side surface 33 (see FIG. 5).

On the other hand, the generatrix M ₂ is located within a plane including the straight line and the axial center line, and the center o is within a plane that includes the gorge portion 31 and is orthogonal to the axial center line, in the roll that is also used as a reference (see FIG. 5). It is given as a circular arc ac as shown in FIG. 5, passing through the end a of the inlet side surface 32 and touching the reference line Y on the outlet side surface 33 at a point c. The generatrix M ₂ is based on three conditions: the center is on a plane that includes the gorge part 31 and is orthogonal to the axis line -, it passes through the end a of the inlet side surface 32, and it touches the reference line Y at the outlet side surface 33. Uniquely determined, its diameter is
D becomes ₀ .

As shown in Fig. 4, the diameter of the rotating body drawn around the axis by the generatrix M ₁ and M ₂ gradually decreases as it moves toward the outlet end between c and b in the axial length direction. It is formed into a truncated cone shape to be reduced, and a barrel shape with a maximum diameter portion in the middle between a and c. The product formed in this manner has a gorge portion 11 with a maximum diameter at the middle portion in the axial direction, and an inlet on both sides of the gorge portion 11 whose diameter decreases toward both ends in the axial direction. Side surface 12, exit side surface 13
The shape includes the peripheral surface shape of the part drawn by the generatrix _M1 , the length dimension L in the axial direction, the position Lg of the gorge part 11 in the axial direction, the inlet end,
The radii r ₁ and r ₂ of the outlet end are both the same as those of the conventional roll shown in FIG _. The only difference is that That is, the fifth
As is clear from the comparison with the peripheral surface shape of the reference roll shown by the broken line in the figure, the diameter of the product in the vicinity of both sides including the gorge portion 11 is slightly smaller than that of the reference roll. The diameter from the vicinity of the gorge part 11 to the inlet end is slightly larger than that of the reference roll, and in the case of this product, the gorge part 31 is connected to the inlet side surface 32 and the outlet side surface 33 as in the reference roll. The inconvenience of having a ridge line as an intersection line is eliminated, and the inlet side surface 12 and the outlet side surface 13 are connected to the gorge part 1.
It is a continuous curved surface including 1.

However, in the case of this product, the diameter of the gorge portion 11 is D ₀
is smaller than the diameter D of the gorge portion 31 in the reference roll by Δd. Therefore, when designing the proposed product, when obtaining a roll as shown in Fig. 5 based on the roll shown in Fig. 3 whose shape was specified by giving the dimensional specifications of each part as described above, The gorge part 3
Find the relationship between the diameters D and D ₀ of 1 and 11,
When obtaining a roll having a gorge portion 11 with a desired diameter D ₀ , the gorge portion 3 of the roll as a reference is
The diameter D of 1 may be given based on the following equation (1).

D=D ₀ +Δd In addition, bus bars M ₁ and M ₂ when designing this product
The position of point c, which is the point of contact with This may be changed as appropriate over time.

FIG. 6 is a graph showing the results of a comparative test of the Elongator with the same specifications as the present product and the conventional product.
The position is set to zero, and the upper and downstream positions are taken on both sides of this, and the vertical axis shows the wall thickness reduction rate in %. The thick solid line p in the graph indicates the product,
Moreover, the broken line q shows each result when the conventional product was used. In the graph, for reference, the present product and the plugs 2 and 40 are shown with a chain line, and the conventional product is shown with a chain double-dot line.

As is clear from this graph, when the present product is used, the biting point of the hollow shell H against the roll is a ₀ point, and the wall thickness reduction rate is rapidly increasing from the ₀ point to just before the gorge part. It rises, passes through the gorge, then descends in a gentle curve, reaching zero at the midpoint between _a6 and _a7 , and the peak of the wall thickness reduction rate is lower than when using the conventional product. The quality of
It can also be seen that the range in which wall thickness reduction occurs is also long and dispersed in the axial direction of the hollow shell H.

As described above, in the case of the proposed product, discontinuity in rolling is eliminated by forming a rotating body with an arc drawn between the end of the inlet side face, beyond the gorge part, and the middle of the outlet side face. The rolled material is continuously and smoothly rolled from the inlet side, beyond the gorge, to the outlet side, so that there is no local wear on the plug, and there is no damage to the gorge as with conventional products. In addition, the peripheral speed difference with the rolled material is also reduced, preventing the occurrence of spiral flaws and pit flaws within the rolled material, which significantly improves the inner surface quality. The present invention has excellent effects such as improved performance.

[Brief explanation of the drawing]

Figure 1 is a plan view schematically showing the general structure of the Elongator, Figure 2 is a side view, Figure 3 is a partially enlarged view of a conventional roll, Figure 4 is a perspective view of the proposed product, and Figure 5. 6 is a partially enlarged view of the proposed product, and FIG. 6 is a graph showing the results of a comparative test between the proposed product and the conventional product. 1... Roll, 2... Plug, 11... Gorge part, 12... Entrance side, 13... Outlet side, 30
...Roll, 31...Gorge Department, 40...Plug.

Claims (1)

[Scope of utility model registration request] A roll of an inclined rolling mill whose shape is specified by giving the length dimension in the axial direction, the gorge formation position in the axial direction, the gorge diameter, the face angle of the inlet side face, and the face angle of the outlet side face. having a center on a plane including the gorge portion and perpendicular to the axis,
and a rotation of a generatrix of the arc about the axis centering on the arc that passes through the end of the inlet side surface and touches the reference line of the outlet side surface, from the point of contact between the arc and the reference line to the inlet end. A roll of an inclined rolling mill characterized by being formed into a body shape.