JPS61193702A - Tandem rolling method for producing bar and wire having round section - Google Patents

Abstract

PURPOSE:To obtain a product having a round sectional shape with high cost performance by inserting a rolling material without twisting into rolls of oval groove from rolls of diamond groove thereby rolling the material. CONSTITUTION:The coefft. of spread in an equation for predicting the spread is preliminarily determined by experiment. The sectional size of the rolling material on the i-1 pass inlet side, the sectional size of the round section, the permissible filling rate of the oval groove and the permissible filling rate of the round groove are preliminarily determined as initial conditions. The filling rate of the oval groove is determined by using the equation for predicting the spread with the ellipticity of the oval groove and the width of the oval groove as variable. The width of the oval groove is so determined that the difference between the value thus obtd. and the permissible filling rate of the oval groove attains the permissible value or below. The filling rate of the round groove is determined by using the equation for predicting the spread in accordance with such value and the height of the oval groove. The ellipticity of the oval groove is determined in such a manner that the difference between the value thus obtd. and the permissible filling rate of the round groove attains the permissible value or below. Further the shape of the oval groove is determined and the material is inserted between the rolls of oval groove from the rolls of diamond groove, by which the material is rolled.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a diamond hole type for the (i-2)th bus stand, an oval hole type for the (i-1)th bus stand, and an oval hole type for the (i-1)th bus stand.
This invention relates to a tandem rolling method for manufacturing rods and wire rods with a round cross section, which is carried out using a round hole type bus.

(Prior Art) Conventionally, in state-of-the-art mills for rolling rods and wire rods, the rolling mills are arranged in an IIV arrangement in order to roll the rolled material between stands with no twist. There are various advantages of not twisting, such as prevention of misrolls during rolling, prevention of scratches caused by twisting, and no need for equipment such as twist rollers.

However, even this state-of-the-art mill has at least one twist. It is used to manufacture rolled products with round cross sections.
This is because there is a process to change the cross-sectional shape from square to oval to round. At the location where twisting is performed, a rolled material with a square cross section is twisted by 45° from the corner to an oval, and the rolled material is inserted into an oval hole type roll and rolled.

Rod and wire rod mills have a large number of bus schedules because they produce small lots and a wide variety of products. Therefore, even when twisting is done at just one location, the twisting locations are different, which poses a problem of increasing the number of equipment such as twist rollers and complicating the rolling operation.

- As an example, a typical bus schedule for manufacturing round bars in a continuous mill is shown in Figure 8 (oval-inner method) and Figure 7 (
Indicates the rhombus (inner method). In the figure, the area reduction rate and the location where the twist is to be performed are clearly indicated with arrows on the left side.

From the figure, it can be seen that in both cases, a square-oval I-bus is used as a connecting bus to a circle, and a 45° twist is performed here.

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to manufacture products with a round cross-sectional shape that are excellent in cost performance by rolling without any twisting as described above. An object of the present invention is to provide a tandem rolling method for manufacturing rods and wire rods with a round cross section.

(Structure of the Invention) In order to achieve the above object, the present invention provides the (i-2)
A tandem rolling method for manufacturing rods and wire rods with round cross sections using a diamond hole type for the bus stand, an oval hole type for the (i-1) bus stand, and a round hole type for the IT bus stand. In this method, the width expansion coefficient in the width expansion prediction formula for determining the width expansion of the rolled material by rolling using a groove die is determined in advance by experiment, and in addition to this value, the (i-1)th bus input is set as an initial condition. In addition to determining in advance the cross-sectional dimensions of the side rolled material, the cross-sectional dimensions of the round cross section, the allowable filling rate of the oval hole type, and the allowable filling rate of the round hole type, the ellipticity of the oval hole type and the oval hole type, which are unknown quantities, are determined in advance. Let the width of be a variable,
Using the width spread prediction formula above, find the filling rate of the oval hole type, and calculate the width of the oval hole type, which is an unknown quantity, so that the difference between this value and the allowable filling rate of the oval hole type above is less than the allowable value. While determining, based on this value and the height of the oval hole shape expressed by this value and the ellipticity of the oval hole shape above,
Using the above width spread prediction formula, find the filling rate of the round hole type,
The ellipticity of the oval hole type, which is an unknown quantity, is determined so that the difference between this value and the allowable filling rate of the above round hole type is less than the allowable value,
The shape of the oval groove was determined based on this value and the oval groove shape 11 above, and the rolled material was inserted into the oval groove roll from the diamond groove roll to be rolled with no twist.

(Example) Next, one embodiment of the present invention will be described with reference to the drawings.

The feature of the present invention is that the stand of the (i-2) bus uses a diamond hole type, the stand of the (i-1) bus uses an oval hole type, and the stand of the i-th bus uses a round hole type. Rolling is performed by inserting the rolled material from a diamond hole type roll into an oval hole type roll without twisting. Therefore, diamond
Oval bath rolling must be done properly.

Here, the diamond refers to a diamond shape with an apex angle of 90° or more and less than 180°.

For this purpose, it is first necessary to know the rolling characteristics of the Guyer oval bath, especially the width spreading characteristics. That is,
The problem is to find the 11 spread coefficient α in the width spread prediction formula, which is a well-known formula as the so-called Shino Yu's formula, by experiment for the bus schedule of the present invention.

Next, FIG. 2 shows symbols for describing the prediction formula for this width spread. The meaning of each symbol in the figure is as follows.

That is, H,, H,: Height of the cross section of the rolled material l before and after rolling. The subscript 0 indicates the front, and the subscript 1 indicates the rear. (Similarly below) B,, B,: Width of the cross section of rolled material 1 with rolling overlap FH: Area where rolled material 1 is removed by groove 3 (portion indicated by a crosshatch knob in the figure) Rolled material in Foz rolling station 1 cross-sectional area B,. The distance in the middle direction between the contour of the cross-section of the rolled material before rolling and the intersection with the groove 3 (o, H+: the area before and after rolling between distance l3ito is B)
Value divided by MO: Rc・collar radius S of roll l, roll gap i-9 average roll diameter (R=Rc 10s/2 H+/2)
It is.

The billing formula can be expressed using the above symbols as follows.

(B, -BO)/BO-α-(2-, Ed/(■-r
o+2・Bo))-(r;'H/r;'o)-(
t) where id is the average roll contact length and Ed
−[・(Ho-t-t, )).

Further, α indicates a width spread coefficient, and takes a unique value for each rolling method. Therefore, a hot rolling experiment was conducted under the conditions shown in the table below, 28 pieces of data were collected, and based on this, the value of the width spread coefficient α was determined by regression.

In other words, as shown in Figure 3, (2・ld/Q(
, + 280) l ・(F o / F o), and (B, /Bo) are taken on the vertical axis, and the relationship between the above two values is investigated from the data obtained as a result of the diamond oval rolling experiment. Ta. As a result, the relationship between both numerical values was approximated by a regression line as shown in the figure, and a value of α=0.96 was obtained. Also,
In the case of oval-round rolling according to the bus schedule of the present invention, it was similarly confirmed that α=1.

table The meaning of each symbol in the table is as follows.

That is, Specific roll diameter δ=　D　o　/　I(.

For the hole ellipticity m -HK/BK...(
2) Pore filling rate ξ-B, /BK...(3
).

However, as shown in Fig. 4, the roll diameter HK at the bottom of the groove 3 is:
Groove height BK of hole pattern 3: represents the width of the ellipse extrapolated from hole pattern 3.

Next, using the rlJ spread coefficient α obtained as described above, the bus design of the Guyer oval bus is carried out according to the procedure shown in FIG. 1 as an example.

The unknowns in this design are the hole ellipticity mK, which gives the oval hole shape, and the hole width B, which gives the hole size.In order to determine the oval hole shape, these two are necessary. I need to decide on the value.

Therefore, in the first step, the cross-sectional dimensions (BO, H8, FG) of the rolled material on the (i-1)th bus entry side, the cross-sectional dimensions of the round material to be manufactured, that is, the diameter d, and the (i-th
1) Determine the collar radius nc of the roll 2 of the bus, the roll gap S, the allowable filling rate ξ for the oval hole type, and the allowable filling rate ξROUND for the round hole type VAL.

In addition, here is the allowable filling rate ξ of the oval hole type. VAL is
It is an empirical value determined to prevent overfilling, taking into consideration the width spread specific to the steel type, and is usually in the range of 0.90 to 0.94. Also, ξ. UND is a range that guarantees roundness, and is defined based on, for example, the JIS standard.

In the second step, the ellipticity m of the oval hole shape, which is an unknown quantity, is
The initial value of K is appropriately set in the range of 0 to I.

In the third step, the initial value of the width BK of the oval hole shape, which is an unknown quantity, is appropriately set within the range of dd/mx.

In the fourth step, the above equation (1) (charging equation) is used to calculate the
i-1) Find the width B1 of the cross section of the rolled material l on the exit side of the bus, and further calculate the hole filling rate ξ at the (i-1)th bus, that is, the pulse bus, from equation (3). , calculate.

In the fifth step, allowable filling rate ξ. VAL and pore filling rate ξ
. It is determined whether the difference from 7 is within an allowable value.

This difference exceeds the allowable value, ξ. ,〈ξ. In the case of VAL, the value of BK is appropriately decreased and then the process returns to the fourth step, while in the case of exceeding the allowable value and ξ0VAL, the value of B is appropriately increased and the process returns to the fourth step. Repeat the same steps as above.

If the difference is less than or equal to the allowable value, proceed to the next step.

In the sixth step, the width B of the cross section of the rolled material l on the exit side of the i-th bus is determined using the above equation (1), and then the width B of the cross-section of the rolled material l on the exit side of the
Calculate the hole filling rate ξro in a bus, that is, a round bus.

In the seventh step, allowable filling rate ξ and hole type filling 0tlN
D Determine whether the difference from the full vehicle ξrO is within the allowable value.

If this difference exceeds the allowable value and ξro>ξROUND, the value of 111 is appropriately decreased, and then the process returns to the third step.
In the case of D, after increasing the value of mK as appropriate, return to the third step □ and repeat the same steps as above.

If the difference is less than or equal to the allowable value, proceed to the next step.

In the eighth step, the hole shape ellipticity mK obtained in the above step is
, the width I3 of the hole shape is adopted, the shape of the oval hole shape of the (i-1)th bus is determined, and the bus design of the diamond-oval bus is completed.

Note that the flowchart in Figure 1 does not include the bite angle and rolling load, which are the constraint conditions for large reductions, in the calculation, but the area reduction rate ( 20-30%), these two conditions can be ignored without any problem.

Therefore, by using the oval groove having the above-mentioned shape, the rolled material 1 is rolled without twisting in the (i-2)th bus, followed by the (+-1)th bus, and then the i-th bus to achieve the desired round cross-sectional shape. rods and wires can be manufactured.

Based on the bus schedule according to the above method, roll diameter 4
When a rolling test was conducted with a 40mm mill, the results shown in Figure 5.
As shown in FIG. 6, a round material lb with a diameter of 34+n+++ could be manufactured from a diamond material 1a with a cross-sectional area of 1378 mm.

Furthermore, this rolling test confirmed that stable rolling can be performed using conventional roll guides when guiding the rolled material in actual operation.

Note that, although the i-th bus mentioned above may be the final bus, it is not necessarily limited to this.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, the width expansion prediction formula The shape of the oval hole is determined without considering the twist between the diamond and the oval bus.

Therefore, it is now possible to manufacture rods and wire rods with a round cross section by completely no-twist rolling, and the twisting process can be omitted, which reduces the occurrence of product defects and reduces equipment costs and maintenance costs.

In addition, since the twisting process is no longer necessary, the distance between stands can be shortened, which also contributes to reducing equipment costs, and has the effect of making it possible to roll products with high heat even in block mills. ing.

[Brief explanation of the drawing]

Fig. 1 is a flowchart showing the procedure for determining the shape of an oval hole type by the method according to the present invention, Fig. 2 is a cross-sectional view for explaining symbols, and Fig. 3 is a B + based on experimental data of square-oval rolling. / B o and 2・! d・F H/ (F
o' (Ho+2Bo)), FIG. 4 is a cross-sectional view for symbol explanation, and FIG. 5. FIG. 6 is an explanatory sectional view showing the results of rolling using the method according to the present invention, and FIGS. 7 and 8 are explanatory views showing a typical conventional bus schedule for producing round bars in a continuous mill. It is. 1, Ia, lb...rolled material, 2...roll, 3...
- Hole shape, H,, H,...height of the cross section of the rolled material before and after rolling, Bo. B,...width of the cross section of the rolled material before and after rolling, FH...area where the rolled material is removed by the groove, Fo...cross-sectional area of the rolled material before rolling, 13yo...cross section of the rolled material before rolling Distance in the middle direction between the intersection of the contour and the hole shape, Rc...roll collar radius, S...roll gap, mK...hole shape ellipticity, ξ...hole shape filling rate, Do ...Roll diameter at the bottom of the groove, HK...groove height of the hole, BK...width of the ellipse extrapolated from the hole. Patent Applicant Kobe Steel Co., Ltd. Agent Patent Attorney Mr. Uegi and 2 others Figure 1 Figure 51! I Figure 6 Figure 7
Figure 8

Claims (1)

[Claims] (1) A diamond hole type is used for the stand of the (i-2) bus, an oval hole type is used for the stand of the (i-1) bus, and a round hole type is used for the i-th bus stand. In the tandem rolling method for manufacturing rods and wire rods, the width spread coefficient in the width spread prediction formula for determining the width spread of rolled material by rolling using a groove is determined in advance by experiments, and in addition to this value, the initial conditions are As such, the cross-sectional dimensions of the rolled material on the entrance side of the (i-1) bus, the cross-sectional dimensions of the round cross section, the allowable filling rate of the oval hole type, and the allowable filling rate of the round hole type are determined in advance, and
Using the unknown ellipticity of the oval hole shape and the width of the oval hole shape as variables, use the above width spread prediction formula to find the filling rate of the oval hole shape, and calculate this value and the allowable filling rate of the oval hole shape above. While determining the width of the oval hole shape, which is an unknown quantity, so that the difference in Find the filling rate of the round hole type using the width spread prediction formula, and determine the ellipticity of the oval hole type, which is an unknown, so that the difference between this value and the allowable filling rate of the round hole type above is less than the allowable value. The shape of the oval groove was determined from this value and the width of the oval groove described above, and the rolled material was inserted from the diamond groove roll into the oval groove roll and rolled without twisting. Characteristic round cross-section rod・
A tandem rolling method for producing wire rods.