JPS5877701A - Flat rolling method for steel bar and wire rod an inlet guide for flat rolling - Google Patents

Abstract

PURPOSE:To roll steel bars and wire rods with high elongating efficiency by small diameter rolls without lateral inclination of trailing ends by providing bill- like holding parts between flat rolls and guiding rolls of inlet guides and specifying the ratio between the diameter of the flat rolls and the roll gap. CONSTITUTION:In the stage of flat rollings of steel bars and wire rods, materials are rolled with the high elongating efficiency by the small diameter rolls of which the ratio D/H of the roll diameter D with respect to a roll gap H is expressed by D/H<=100/H+5. Two mating guide plates having taperes are provided to inlet guides for guiding a material to be rolled into the roll gap of flat rolls 4 and said plates are held by means of guide plates 7, by which the material to be rolled is guided and passed through guiding rolls 3. The material is grasped by bill-like holding parts 5 and is conducted to the rolls 4. Thus the lateral inclination which tends to arise at the trailing end of the rolled material is decreased and the yield of products is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention combats flat roll rolling methods and flat roll rolling guides for steel bars and wire rods.

When manufacturing products such as steel bars and wire rods with a square or round cross section from materials with a rectangular cross section by rolling, hole type p-sil pass rolling has so far been exclusively used. In other words, as shown in Figure 1, a typical example of the path +&-
A rectangular PEl1li material W is subjected to groove rolling using a square hole die 8 and a diamond hole die d once or twice, and then a square steel ° product p is formed by the same groove rolling with almost the same forming pass. A round steel product p' is produced by hole-type rolling using hole 0 and round hole r alternately.
It was customary to obtain

On the other hand, for the above-mentioned materials, the upstream rolling pass whose main purpose is to reduce the cross section is rolled with flat rolls, and only the forming pass that gives the product a predetermined shape is the hole type p-
So-called flat roll rolling, which relies on rolling passes, has recently been proposed.

The basic pass schedule is shown in the diagram jlJ, where t is the upstream pass and m is the pass just before forming, flat rolls are used in both of these, and groove roll rolling is performed only for forming pass f.

When rolling with flat rolls instead of grooved rolls, turning of the P-Caliver is not only unnecessary, but also there is less roughness and wear on the roll surface, so %W
- Roll life is longer and p-rucos) is lower, and even if the shape and dimensions of the product to be rolled change, there is no need to change rolls or holes as in the past, so rolling stop times are shortened. Although there are many advantages such as being able to do this, there are disadvantages as shown below.

(1) Unlike the hole-diameter roll pass, the flat roll pass does not have a hole shape that restricts deformation in the width direction, so the elongation in the rolling direction is smaller than that of the hole-type roll pass. If you try to obtain the same elongation as the hole I-joll pass, you will have to increase the rolling reduction, but the flatness will become excessive, so in the next 7 rat roll passes, it will collapse as shown in Figure 3.
/H increases according to flatness Bo/Ho, making it impossible to continue rolling.

(2) In addition, in flat roll baths, large pressure reduction,
When this is done, the shape of the free surface that does not contact the roll becomes convex, but as shown in the figure, if the degree of convexity b/Ho becomes excessive, this also causes the collapse a/lI to become large. to prevent the continuation of the flat p-Lewis.

(8) Even if an attempt is made to switch from a grooved roll pass to a flat rule pass in the existing equipment, it is difficult to obtain the same elongation effect due to the reasons already mentioned, resulting in an increase in the number of passes and a decrease in productivity. Therefore, additional rolling mill stands will be required.

In an attempt to solve the above-mentioned problems, the inventor, Raba, conducted numerous experiments and studies on the rolling behavior using a flat roll bath, and as a result, flat row/? It has been found that the elongation rate due to the bath is significantly dependent on the roll diameter. An example of the experimental results is shown in Figure 3. In this case, 7 rat rolls with various roll diameters are applied to a 1,201B11 square material, and the elongation rate λ is calculated depending on the roll diameter. This is the plot. Here, the smaller the diameter of the flat roll is used, the higher the elongation rate λ is obtained.

The elongation rate λ is the ratio of the length of the material after rolling to that before rolling, and for such an actual elongation rate, it is assumed that the elongation is entirely in the rolling direction without any expansion of the material by the rolls. By defining the elongation efficiency da as the ratio to the ideal elongation rate λ′,
We carried out experiments on roll fields and rolling conditions in which this elongation efficiency was equal to or higher than that of a normal hole-type p-ru pass. It has been found that high elongation efficiency can be obtained under flat roll rolling conditions that occupy the area indicated by diagonal lines below the dashed line α in the figure. This area β
If it happens, it is approximately expressed by the following formula.

When this region β is approximated by a broken line, when H≧60slI, D/H≦5. 20 =i> When H≧101111, D/H≦2
cA-3-, when H<101111, D/H≦
85-IH, it is more easily calculated.

As can be seen from the ratio D/H value, the roll diameter is
The conventionally used flat roll is Habo J40 ms.
Since it is necessary to make the diameter much smaller than φ, it is desirable in practice to use a backup roll to support the rolling reaction force in order to compensate for the necessary roll rigidity. It is easy to implement if you follow the knowledge on rolling mills.

In this way, under high elongation efficiency, the ratio of effective energy spent on elongation deformation of the material, that is, cross-sectional reduction, of the total energy applied for EEi is high, and the wasted energy for radial expansion deformation is Since the ratio is small, it is also useful from the viewpoint of energy saving, and stable flat roll rolling can be performed by effectively suppressing the spread of radiation.

Generally, in the above-mentioned flat roll pass, an entrance guide is used to accurately guide the material to be rolled to the roll train in much the same manner as in the conventional slotted roll pass. As shown in FIG. 7, the material to be rolled is held by guide rollers 3 and 3' from between the guide plates and -' of the entrance guide L, and is placed on the flat rule and the guide plate. The material is guided and rolled.

Here, while the rolled material W is held by the guide rollers 3 and 3' (5L) in FIG. 7, the rolled material W does not fall horizontally, but as shown in As soon as the tail end of the material W separates from the guide rollers 3, 3', its retention is lost and the tail end falls sideways, and the tail end 0 tends to have a rhombic cross section as shown in the figure, and the rolled material flatness B. /H0, convex b/
The larger H0 is, the more serious the area reduction becomes, and the more difficult it becomes to undergo the prescribed surface reduction process. For this reason, as shown in Fig. 9, an example of the shape of the tail end of a product that has undergone a forming pass, a protrusion e occurs at the tail end 0 in a hole-type roll bath, and this part must be discarded as a defective product. If the occurrence of such protrusion e becomes even more severe, rolling action occurs on the circumferential surfaces of the rolls on both sides of the small gap outside the groove surface, resulting in an abnormally large rolling load. In the past, there was a risk of stopping rolling or destroying the equipment, but there is also a good chance that rolling would stop or the guide would be destroyed without falling over.

In order to advantageously solve the problems peculiar to such a flat rule pass, the inlet guide of the flat roll supports the material to be rolled all the way to the axillary exit of the flat roll where rolling is completed, and the material is supported at its tail end. It reduces the horizontal fall that is likely to occur, improves productivity under the high elongation efficiency mentioned above, and eliminates the waxiness that occurs at the tail end of the rolled material and is hindered by the decrease in yield due to pruning. Here, we propose an entrance guide for flat rolling.

Figures 1/1 and 12 are explanatory diagrams showing the basic structure of the entrance guide improved as described above, including guide plates J, Ko I,
It is similar to the one shown in FIG. 7 in that it has guide rollers J and 31, but it has guide rollers 3, 3' and 7 rat P.
- The material to be rolled W is sandwiched and supported in the axial direction of the flat rule between the roll and the roll, and passes through the p-rule gap of the flat rolls to reach the exit point of the roll acid, at least where the deformation of the material due to rolling is completed. a beak-shaped holding part 3 extending between;
j'.

As a matter of course, the material to be rolled W is deformed by expanding in the direction of the roll axis by this seven-roll rolling. So, the 12th
As shown by gJ, the deformation of the rolled material W progresses in a streamlined manner in the roll axis direction due to width expansion between the start and end of rolling, and its shape is roughly predicted from the rolling conditions. Therefore, the beak-shaped holding part j,! The inner surface of 71 has flank surfaces 4 and 4' that approximately correspond to the deformation transition of the rolled material W in the roll axis direction as shown in FIG. 12, and the play @k with the rolled material W is optimized. Set it so that In other words, if the free play ak is less than 7 m, there is a risk that the side surface of the rolled material W may come into contact with the flank surface 4.6', and therefore scratches are likely to occur on the surface of the rolled material W. On the other hand, the free play @ When it becomes larger than 71111, the holding effect is almost lost and it becomes virtually useless for preventing sideways falling. Therefore, it is preferable to set the play @ to /~3M. In this way, there is no lateral fall over the entire length of the material to be rolled, and stable flat roll pass rolling operations can be performed.

In addition, beak retention 1ISj,! ' is also useful for reliable biting guidance at the tip of the rolled material W, so the guide roller 3,
When relying only on the guide 3', the protruding end of the rolled material W often rotates as shown in Figure 1J.

This eliminates the disadvantage of being unable to guide the rolling mill to the next rolling mill and causing rolling troubles.

Figure 1 (6) (b) shows a cross-sectional view of the main parts and a plan view of the main part, and an example in which the concrete implementation structure of the above-mentioned entrance guide I is applied to the horizontal axis flange as well. Fig. 1j shows the external appearance, and Fig. 16 is an exploded perspective view. 2 in the figure. 7.7' is a guide plate (two guide plates with a tapered inner surface), and 7.7' is a guide plate that holds -' and supports the side surface of the rolled material W from the tip of the inner surface of the taper. It is a pair of holders equipped with guiding rollers 3 and 3', and t is
Guide plateco.

Place the assembly of holder 7 and holder 7 and 7' and guide roller J.
, 3' is a box-shaped guide that controls fixation that can be adjusted between 1III and 11.

In addition, 9 in the figure penetrates the side wall of the 1m type guide l and the holder 7
．． 7' is screwed into the screw hole 9' to fix the holder, and 10 is an adjusting set screw screwed into the side wall of the box-shaped guide l to set the mutual gap between the holders 7 and 7'.
In addition, l/ is an adjustment set screw that is screwed into the holder 7 and 7' and is supported by the reaction force receiver/2 of the box-shaped guide t to control the setting of the p-ra distance between the guide p-ra 3 and 3'. 1 and/
J 't tp are respectively screwed into the top wall of the box-shaped guide l to form the guide guide λ.

2I and a set screw for fixing holder 7.7', and n
is the pin shaft of the guide roller, and /4 is the bearing.

In the illustrated example, the beak-shaped holding parts j and j' extending within the roll gap of the flat p-ruder and the da I until reaching their exit points are as follows:
Although the case where the holder 7 and 7' are integrally formed at the end thereof is shown, a separate member may be attached by welding, screwing, or other means.

Using the flat roll rolling guide I according to the above, a material with a cross section of 739 m was subjected to flat roll rolling of 12 noise, and then subjected to groove roll rolling of ≦pass to finish it into a round steel of 16 ■ψ. On the other hand, the guide roller 3
A comparison was made of the sideways falling situation at the tail end of the rolled material in each case where a similar rolling process was applied using a conventional entrance guide equipped with 13' but without the beak-shaped holding parts j and j'. , especially the flanks of the beak-shaped holding parts j and j'6. ≦L gap between the tail end of the rolled material k t J = 1
sm, the lateral inclination angle shown in Fig. 17(a) at the tail end of the rolled material in each bus was within jO, and there was no problem in the subsequent groove rolling. As shown in Fig. 17 (b), the tail end fell sideways so severely that approximately - of the test pieces could not pass through the inlet guide of the next rolling mill, resulting in rolling trouble, and the remaining rolling mills were l≦-ψ.
Even if rolling could be achieved, the tail end/protrusion length would be more than five times longer than in the case of this invention, as shown in FIG. experienced.

Next, an example will be described in which the method of the present invention was applied to flat roll rolling of small diameter steel bar wire rods, in which the use of such a flat roll rolling operator guide is particularly important in terms of yield improvement.

In other words, regarding an example in which the method of the present invention is applied to a finishing continuous mill for producing //Haφ round steel, a tandem rolling mill with four horizontally and vertically alternately arranged tandem rolling mills is used in the upstream dapas as shown in Fig. 19. , double roll type rolling mill with pack-in rolls /7, /I.

/9, 21), and a double roll rolling mill (22) was connected to the downstream copass, and rolling was carried out sequentially starting from the /1slI0 material with the rolling reduction distribution shown in the pass schedule in Figure 3.

On the other hand, in the case of conventional full-hole roll rolling, the pass schedule is as shown in Figure 1, which uses oval-round alternating rolling to roll from a 71:m' material to a round steel product of l/φ□ in 6 passes. Although it can be rolled, it has the disadvantages mentioned above, and on the other hand, it is similar to full-hole rolling by applying flat roll rolling to the upstream pass using a J-type roll rolling mill that follows the conventional knowledge of flat rolling. When attempting to finish a round steel of //11m1φ from a 7fts 0 material, the WE rolled material becomes excessively flattened in each of the 7 rat roll passes, resulting in unstable rolling, as shown in FIG. This is because - in a heavy roll rolling mill, the roll diameter is as large as 3401111φ for strength reasons, so the value of the D/H ratio also becomes large, so as already mentioned, the elongation efficiency becomes extremely stratified.In other words, in each pass This is because the width is unnecessarily widened. The following table shows the difference in elongation efficiency between the pass schedule of the flat roll scrap comparison method shown in FIG.

In the method of this invention, the four-wheel strength is guaranteed by the backup rule when necessary, and the roll diameter of the roll pass is reduced to about 100 mm, so No. H is much smaller than that of the comparative method. As a result, the elongation efficiency is high, that is, the width expansion is small, so that the material to be rolled does not become too flat during each of the 7 rat roll passes as shown in FIG. 2, and stable rolling can be performed.

Although this example has been described with respect to the application of the method of the present invention to a finishing continuous mill in the manufacturing process of ll-φ round steel products, the upstream passes other than the forming pass that adjusts the cross-sectional shape of the final product are generally The present invention is advantageously applicable to the rolling stage corresponding to such an upstream pulse, and may be applied not only to a continuous mill but also to a single mill such as a reverse mill, and may also be applied to a rolling mill such as a reverse mill. A roll type rolling mill is a typical example of a multi-roll type EE rolling mill, and there is no problem with the backup means.

As described above, the method of the present invention is useful for stably performing 0-roll rolling of steel bars and wire rods with high elongation efficiency, and also makes a significant contribution to productivity improvement. The flat roll rolling guide, which is directly used to carry out this flat roll rolling method, securely holds the rolled material during the flat roll pass to the exit point of the roll gap, thereby securing the ends of the rolled material. This effectively eliminates the troubles that tend to occur and are unique to flat roll rolling, contributing to effective use of rolling energy and significant improvement in product yield.

[Brief explanation of drawings]

Figures 1 and 2 are rolling schedules for conventional method rolling of steel bars and wire rods using slotted rolls and flat rolls. The graph showing the influence, Figure q, is a graph showing the cause of the convex shape on the free surface, Figure 3 is a graph showing the influence of the diameter of the beam on the elongation rate, and
The figure is a diagram that summarizes the conditions for obtaining the same elongation efficiency as flat roll rolling and recessed roll rolling. Fig. 1 is an explanatory diagram showing how the material to be rolled is guided by the entrance guide. FIG. 70 is a cross-sectional view showing the adverse effects on groove type P-roll rolling, and FIG. 11 is a cross-sectional view perpendicular to the roll axis showing the basic structure of the entrance guide according to the present invention. Fig. 12 is a cross-sectional view parallel to the roll axis, and Fig. 13 is an explanatory view of the twist occurring at the rolling tip of the material to be rolled. 17 (a) and (b) are rolled material FIG. 11 is a cross-sectional view comparing the degree of inclination of the tail end, FIG. 11 is a graph comparing the length of the tail end protrusion, and FIG. FIG. be. Ko, 2'...Guide plate, Je3'...Guidance roll,! , j'...Beak-shaped holding part, 4 m 4'.
... Flank surface, 7°7'... Holder, l... Box-shaped guide 0 Patent applicant Kawasaki Steel Corporation Figure 1 Figure 2 Figure 3 □ ~. Fig. 4 Fig. 5 Roll work Fig. 6) / (mm) Fig. 7 Fig. 8 Fig. 12 Fig. 13 Fig. 14 (a) Fig. 15 Fig. 16n 9 Procedural amendment February 1982 2 Day 1, Indication of the case 1982 Patent Application No. 178704 2 Title of the invention 3, Person making the amendment - Relationship to the case Patent applicant (125) Kawasaki Steel Corporation 1, Specification page 10 The 18 lines were corrected as follows, and the LLF was corrected. 〇 In the case of "make it. It is preferable to use guide rollers to strengthen material retention, and it is even more preferable to use a guide with rollers on the exit side as well.

Claims (1)

[Scope of Claims] L In the rolling process, which goes through a rolling step using seven flat roll baths during the forming pass that gives a product with a square or round cross section a predetermined shape from a rectangular cross-section material, the roll A 7-rat roll rolling method for steel bars and wire rods, which is characterized by performing rolling with high elongation efficiency using small-diameter rolls whose ratio of roll diameter to the gap H is determined by the following formula: %. z When the flat roll path is R≧some according to roll Ill[H, D/II≦6.80wI>H≧1
When 10m, D/H≦tz, 5--L. 1Q wn:) When li≧1Qss, D/H≦go
-u, when 'sH<10811, D/1is85-
4. The method according to 1, using a small diameter roll that satisfies the approximate relationship of 4H,'. & A method described in lt or 2, in which the flat roll pass is based on a multi-roll rolling mill equipped with a backup roll that supports the rolling reaction force caused by the flat roll pass. 47 A two-piece guide plate with a tapered inner surface that guides the side surface of the material to be rolled toward the roll gap of the roll, and a guide plate that holds these guide plates and supports the side surface of the material to be rolled from the tip of the inner surface of the taper. The holder mainly consists of a pair of holders each having a guide roller, and a box-shaped guide that accommodates the assembly of the guide plate and holder and fixes the guide roller so that the gap between the guide rollers can be adjusted.
A beak-shaped beak extending within the roll lj of the flat roll that rolls down the material to be rolled, at least up to the exit point of the roll gap, and serves to prevent twisting of the end of the material to be rolled, which is not guided by the guiding p-roller. Flat roll rolling guide for steel bars and wire rods with a holding part in the body. & 4. The guide according to 4, wherein the beak-shaped holding portion faces the material to be rolled and has a clearance surface corresponding to the width expansion caused by the rolling reduction by the flat roll. & The flank of the beak-shaped holding part is between the side surface of the rolled material /w
The guide O according to 5, which forms the play of jw.